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THE DESALINATION DEBATE
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Journal of the Australian Water Association ISSN 0310-0367
Volume 38 No 3 May 2011
contents REGULAR FEATURES From the AWA Chief Executive Stopping The Policy Rot
Tom Mollenkopf
4
My Point of View
Is Sustainability Scalable? Prof Stephen Gray
6
From the AWA President
Leading the Conversation
WaterAustralia Update
An aerial view of Perth’s Desalination Plant. Experts disagree on the sustainability of desalination for water supply. See page 38.
Lucia Cade 10
The US – A Natural Water Partner
Les Targ 12
Crosscurrent
14
Industry News
22
AWA News
30
Conference Reviews
54
SPECIAL FEATURES Water, Water, Everywhere Experts debate the viability of desalination
Neil Palmer & Jochen Kaempf
38
Building With Nature Innovative flood management systems in the Netherlands The Future of Urban Water State of the Water Sector Report Update
Andrew Speers
42
James Cameron
48
Andrew Speers
52
AWA CONTACT DETAILS Australian Water Association ABN 78 096 035 773 Level 6, 655 Pacific Hwy, PO Box 222, St Leonards NSW 1590 Tel: +61 2 9436 0055 Fax: +61 2 9436 0155 Email: info@awa.asn.au Web: www.awa.asn.au
DISCLAIMER Australian Water Association assumes no responsibility for opinions or statements of fact expressed by contributors or advertisers.
COPYRIGHT AWA Water Journal is subject to copyright and may not be reproduced in any format without written permission of the AWA. To seek permission to reproduce Water Journal materials, send your request to journal@awa.asn.au
WATER JOURNAL MISSION STATEMENT ‘To provide a journal that interests and informs on water matters, Australian and international, covering technological, environmental, economic and social aspects, and to provide a repository of useful refereed papers.’ PUBLISH DATES Water Journal is published eight times per year: March, April, May, July, August, September, November and December.
EDITORIAL BOARD Chair: Frank R Bishop; Dr Bruce Anderson, AECOM; Dr Terry Anderson, Consultant SEWL; Michael Chapman, GHD; Robert Ford, Central Highlands Water (rtd); Anthony Gibson, Ecowise; Dr Brian Labza, Vic Health; Dr Robbert van Oorschot, GHD; John Poon, CH2M Hill; David Power, BECA Consultants; Professor Felicity Roddick, RMIT University; Dr Ashok Sharma, CSIRO; and E A (Bob) Swinton, Technical Editor.
EDITORIAL SUBMISSIONS Water Journal welcomes editorial submissions for technical and topical articles, news, opinion pieces, business information and letters to the editor. Acceptance of editorial submissions is at the discretion of the editor and editorial board. • Technical Papers and Technical Features Bob Swinton, Technical Editor, Water Journal – bswinton@bigpond.net.au AND journal@awa.asn.au. Papers 3,000–4,000 words and graphics; or topical articles of up
Floating houses are just one of Holland’s ‘working with nature’ approaches to flood management. See page 42.
to 2,000 words relating to all areas of the water cycle and water business. Submissions are tabled at monthly editorial board meetings and where appropriate are assigned referees. Referee comments will be forwarded to the principal author for further action. Authors should be mindful that Water Journal is published in a three-column ‘magazine’ format rather than the fullpage format of Word documents. Graphics should be set up so that they will still be clearly legible when reduced to two-column size (about 12cm wide). Tables and figures should be numbered with the appropriate reference in the text (eg, see Figure 1), not just placed in the text with a position reference (eg, see below), as they may end up anywhere on the page when typeset. • General Feature Articles, Industry News, Opinion Pieces and Media Releases Anne Lawton, Managing Editor, Water Journal – journal@awa.asn.au • Water Business and Product News Lynne Bartlett, National Relationship Manager, AWA – lbartlett@awa.asn.au
UPCOMING TOPICS JULy – Ozwater’11 Report & Selected Papers; Public Health Aspects; Disinfection, UV. AUGUST – Desalination; Coal Seam Gas Water; Recycling; Operational Experiences; Governance; Sewerage; Cleaning; Repairs; Rehabilitation. SEPTEMBER – Wastewater Treatment; On-Site & Small Systems; International Developments.
ADVERTISING Advertisements are included as an information service to readers and are reviewed before publication to ensure relevance to the water sector and the objectives of the AWA. Contact Lynne Bartlett, National Relationship Manager, AWA – lbartlett@awa.asn.au Tel: +61 2 9467 8408 or 0428 261 496.
PUBLISHED BY Australian Water Association (AWA) Publications, Level 6, 655 Pacific Hwy, PO Box 222, St Leonards NSW 1590; Tel: +61 2 9436 0055 or 1300 361 426, Fax: +61 2 9436 0155, Email: journal@awa.asn.au, Web: www.awa.asn.au
OUR COVER (Photo courtesy Water Corporation, WA) Reverse osmosis racks at the desalination plant in Perth. The controversial issue of desalination sparks strong feelings among the public, environmentalists, and within the water sector itself. Please turn to page 38 to read opposing views from two respected water professionals.
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Journal of the Australian Water Association ISSN 0310-0367
Capstone Micro-turbine installation at the Melton Recycled Water Treatment Plant in Victoria. See page 98.
TECHNICAL FEATURES (
Volume 38 No 3 May 2011
contents
Aerial view of the treatment train at the CSBP vertical flow wetlands site at Kwinana in WA. See page 103.
INDICATES THE PAPER HAS BEEN REFEREED)
DEMAND MANAGEMENT Separating Indoor and Outdoor Water Consumption Tracking water savings using customer-metered data The Influence of Declining Perceptions of Scarcity Exploring a new paradigm of future demand management options Energy Consumption of Domestic Rainwater Tanks Why supplying rainwater uses more energy than it should Sydney Water’s Smart Metering Residential Project An insight into the benefits, costs and challenges of smart metering Customer Behaviour Modelling For Predicting Future Demand A modelling and forecasting platform simulated over 40,000 households with 95% accuracy
YC Wang
63
D Giurco, T Boyle, S White, B Clarke, P Houlihan
68
G Hauber-Davidson, J Shortt
72
C Doolan
77
D Perugini, M Perugini, B Clarke, J Frdelja
81
S Ireland
86
DJ Batstone, PD Jensen, H Ge
90
WPF Barber
94
J Boan, R Howick, A Davey
98
SS Domingos, S Dallas, S Fellstead
103
F Barendregt, M Selleck
105
BIOSOLIDS Biosolids Process Optimisation at Sydney’s North Head STP Recuperative thickening increases solids throughout Biochemical Treatment of Biosolids – Emerging Technologies Pre-treatment methods such as biological processes can improve economic performance RESOURCE RECOVERY Cogeneration Potential from the Anaerobic Digestion of Sludge Modelling the influence of various parameters Cogeneration by a Micro-Turbine Operating on Biogas Capstone Micro-turbine technology reduces greenhouse gas emissions WETLANDS FOR WASTEWATER TREATMENT Vertical Flow Wetlands for Industrial Wastewater Treatment Vertical flow wetlands at a chemical and fertiliser manufacturer in Kwinana MEMBRANES & DESALINATION Treating Contaminated Groundwater with Reverse Osmosis Improved pre-treatment reduces severe bio-fouling problems WATER BUSINESS New Products and Business Information
110
Advertisers’ Index
116
2
MAY 2011
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from the chief executive
Forget Reform – Let’s Stop the Policy Rot Tom Mollenkopf – AWA Chief Executive In recent weeks both the National Water Commission and the Productivity Commission have released major reports into reform in the urban water sector. The cry from both reports is that reform is urgently required in order to improve efficiencies in the sector and to maximise benefits to local communities. I won’t be drawn at this stage on some of the more colourful language used in the reports. The Productivity Commission report, for example, claims: “An urban water sector under stress”; this is a great headline, but overplays the current circumstances just a little. Many of us have been working in water long enough to appreciate that the sector has already experienced substantial reform over the past two decades. In addition, we are constantly innovating and seeking the next opportunity for improvement. The benefits of this have been apparent in material gains in efficiency, innovation and operational performance. Consequently, we have an urban water sector that is the envy of many developed nations around the world. The sector in Australia does, however, recognise the need for further reform. I mention some priorities further on in this column, but let me first observe that the approach to future reform should be cautious and strategic, otherwise we are at risk of suffering from reform fatigue. There has been a plethora of reports from different bodies over recent years, often covering the same issues. Let’s focus on the few core areas that will deliver real value to the community, the economy and the environment.
by some governments – for example, on planned potable reuse – has worked against water security objectives and excluded a potentially cost-effective option. Clarifying objectives and responsibilities of the growing number of agencies makes perfect sense. And it is refreshing to see a focus on improving governance, regulation, pricing and so on, rather than trying to create a competitive market as in the electricity sector. However, as we talk about moving the water sector forward the recent decision by the Queensland Government to set an arbitrary cap on water prices has the potential to move the sector two steps backwards. Of course, the announcement plays well in an election cycle. But putting a cap on water prices raises the question – if water consumers don’t pay for the necessary cost of water security and maintaining water quality, then who will? For too long water in Australia has been undervalued and underpriced. If we are to have a rational allocation of scarce resources, we must have prices that reflect the true cost of delivering services. To do otherwise jeopardises our nation’s ability to construct and maintain key infrastructure, forcing the burden onto the next generation. In my view the priority need for ‘reform’ in Australia is the depoliticisation of the price of water through robust independent pricing regulation. Until we get this reform right, all the other reforms are just window dressing.
The recommendation by the Productivity Commission to remove bans on particular supply augmentation options is a step in the right direction. The introduction of policy bans
4 MAY 2011 water
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my point of view
Is Sustainability Scalable? Professor Stephen Gray, Director of the Institute for Sustainability and Innovation, Victoria University. Professor Gray is responsible for the Institute’s water research program and is actively involved in water treatment and membrane research. Soaking rains over the east coast of Australia this spring and summer, and the construction and completion of many seawater desalination plants, has led the water industry to focus on improving bottom lines, coping with floods and creating “sustainable water systems”. Indeed, the last few contributions of “My Point of View” have identified drivers for change towards more sustainable systems. These challenges include: • A 40% increase in population over the next 20-30 years; • Climate change resulting in sustained drier periods and extreme rainfall events; • The need to reduce energy requirements to lower greenhouse gas emissions; and • How to integrate more sustainable water systems into existing infrastructure, so as to reduce capital expenditure.
Rainwater Tank Energy Consumption Survey Decentralised systems are often considered the panacea to these problems, by offering lower transport requirements for water, new non-traditional sources of water, and flexibility in how they integrate into existing infrastructure. However, a recent survey of the energy used by rainwater tanks by the University of Technology Sydney (UTS) (http:// utsescholarship.lib.uts.edu.au/iresearch/scholarly-works/ bitstream/handle/2100/888/retamaletal2009waterenergynexus. pdf?sequence=4) has shown that the actual energy use varied from 0.9–4.9kWh/kL, with a typical energy use of 1.5kWh/kL. This compares to specific energy consumptions of <1kWh/kL for delivery of drinking water in most Australian capital cities (the exception being Adelaide at 1.84kWh/kL) and around 1kWh for brackish water desalination. Clearly, while the theoretical energy required for transport of water from a rainwater tank to household end uses should be lower than sourcing it from distant supplies, this is not currently realised. There is a need to improve the design of rainwater tank systems, and the technologies used in the widespread roll out of water tanks, if lower energy water systems are to be achieved. The issue can be addressed by the use of more efficient pumps and gravity systems in low pressure applications.
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These approaches need to be promoted through planning policies, so that more of the potential benefits that rainwater tanks can afford may be realised. It also underscores the need for monitoring the performance of alternative water systems, as called for by Ted Gardner in his March 2011 “My Point of View”, as there can be large differences between actual and theoretical performances.
Small-Scale, High-Cost Solutions Small-scale wastewater treatment plants, often in the basements of large high-rise buildings, are also seen by many as a more sustainable solution for suppling recycled water. Indeed, star rating systems for buildings, such as BASIX, give credit for the inclusion of such systems. While they are capable of supplying high quality water, the cost is usually considerably higher than potable water supplies, with production costs of $20/kL having been claimed in some instances. The high production costs of these systems are associated with the need for compliance monitoring and regular site visits for maintenance. In order for these systems to be financially competitive with centralised reuse systems, improved on-line monitoring and process diagnostics are required. There has been a significant research effort for development of new sensors nationally via the Environmental Biotechnology CRC and CSIRO, as well as international efforts. As yet this has not led to significant outcomes in the reduction of operating costs for small-scale wastewater treatment systems. Perhaps it is time for a targeted research program to identify specific sensors and control strategies to reduce the operational costs of distributed smallscale reuse systems so as to lower their operating costs. In locations where expensive augmentation of distribution and/or collection systems is required, then the use of smallscale reuse systems may be cost competitive. However, in these situations the cost of these systems should be compared against demand management and peak levelling approaches, as these concepts are also suitable under such circumstances. Another approach to decentralised systems is to use stormwater, but to date there are very few working examples available to demonstrate the implementation issues of these systems. As the increasing interest in these systems leads to demonstration sites, monitoring programs along the lines of
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my point of view Ted Gardnerâ&#x20AC;&#x2122;s approach will be necessary for us to effectively disseminate the operating knowledge gained from them. Therefore, while small-scale distributed systems may have significant potential benefits, they still face significant challenges and have not yet been widely implemented. Instead, large-scale reuse systems and desalination plants have been used to address the shortfall in supplies.
Desalination Plants The case of seawater desalination plants is interesting with respect to sustainable water systems, as the energy required for production makes this water energy intensive. However, the greenhouse gas emissions from Australian desalination plants are largely offset by green energy sources, and if we are willing to accept this as a valid approach to reducing greenhouse gases, then the greenhouse gas emissions associated with this water are similar to that of dam waters or from inter-basin transfers. Furthermore, these plants do not always operate. For instance, the Sydney desalination plant operates intermittently, shutting down when the reservoirs are full and only producing water when the reservoirs are low. Such an approach to operation reduces overall energy use, but also leads to underutilisation of the asset. Similar operating protocols are also in place for the indirect potable reuse scheme in Brisbane, which only delivers water to the drinking water system when reservoirs are low and community acceptance is higher.
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The flexibility of these systems to deliver water only when required comes at the expense of redundancy in the system, increasing costs. Such redundancy may also be present in small-scale water systems, for example, the use of potable water as backup for rainwater tanks or stormwater systems. Therefore, perhaps the need for redundancy in the system is something that requires an effective communication campaign as an outcome of moving towards systems that are more sustainable, cost being a trade-off for lower energy use and water security.
Future Strategies So what does this mean for the future of water systems in Australia? We currently have seawater desalination and large-scale water recycling plants for another 20â&#x20AC;&#x201C;30 years, and small-scale distributed systems still have significant challenges before they can claim to outperform large-scale systems. They also need to compete against demand management and peak levelling approaches in areas requiring significant augmentation of their networks. However, the potential for lower-energy water transport that exists for distributed systems, and their ability to address stormwater discharges, still makes them interesting to consider. Perhaps we should use the time before the next renewal phase of our large systems to ascertain if the potential of distributed systems can be realised and how other strategies can be implemented in a more sustainable way.
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from the president
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Lucia Cade – incoming AWA President It is an honour to take over as AWA National President this May. As an organisation AWA is forever focussed on better delivering our mission to foster knowledge, understanding and advancement in sustainable water management through advocacy, collaboration and professional development. The key ways in which we do this are by being the hub for water professionals, providing a knowledge network and ‘leading the conversation’ on water issues. The Ozwater’11 Conference provides just such an environment, bringing together people who work in water from urban and regional utilities, rural water providers, service providers, key customers in resources and agriculture, and international colleagues and counterparts. There will be many interesting conversations over the three days; networks will be established and re-established and knowledge shared. Beyond Ozwater, the conversations we lead relate to the big water issues being faced across the country. At a recent Strategic Advisory Council meeting in Brisbane, AWA leaders from around the country shared the challenges being faced in their regions. Common themes related to: • Political and media questioning of recent capital investments made by metropolitan city water suppliers to diversify their water supply sources to be more resilient in times of drought, now that many storages are on the recovery and some are overflowing; • The related issue of water pricing and the impact of large capital investment programs on consumers’ water bills; • Further, the issue of what diverse supply options are being considered and, importantly, not considered. In particular, water professionals remain frustrated by the ongoing reluctance of political decision-makers to consider indirect potable reuse of water, and the slow uptake of stormwater harvesting for potable augmentation. There is plenty of evidence in community and sector surveys that we are ready for these steps; • Across northern Australia, from Western Australia through the Northern Territory to northern Queensland, the issue of the mining and resources boom and the pressure it is putting on our water resources in terms of both water supply and water quality; the stress on the environment in those regions and the scarcity of available human resources. In February, I participated in a round-table discussion with the Federal Minister for Sustainability, Environment, Water, Population and Communities, the Hon. Tony Bourke MP. The questions
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posed to us sought AWA’s advice on the issues that should be considered if Australia is to have a sustainable level of population. They also asked us to provide ideas about what we need to measure and report to know we are sustainable and, more importantly, to inform us of when we are failing to be sustainable. The main idea AWA conveyed was the need to consider the capacity of our water resources to sustain a growing population and an expanding economy. Water is fundamental to economic activity in regional areas for agriculture, mining and resources and forestry, as well as in urban areas for public health and urban amenity and recreation. In considering the capacity of water resources to meet all these needs, we must consider the spatial and temporal variability in the amount of water available. There is a huge range in the amount of water available in any place at any given time and over periods of time. Our planners, policy makers and resource managers need to consider ways to ensure water can be provided to support all these uses in times of extended drought, in times of plenty and also in times of over-abundance (sometimes destructive over-abundance). Indeed, the response of managers and decision-makers during floods is under intense scrutiny with the inquiry that is currently underway into the South-East Queensland floods. AWA’s response to the Sustainable Population Strategy and the reports presented by the Government’s three panels is available on the AWA website (www.awa.asn.au). The three independent panels each considered a different perspective of a sustainable population: demography and liveability; productivity and prosperity; and sustainable development.
About the new President Lucia has worked in the metropolitan and regional urban water authorities in various roles from hydraulic modelling, general management and as a director. In recent times she has provided strategic advice to companies in the infrastructure sector regarding operational improvement, procuring services from the private sector and dealing strategically with key stakeholders to achieve the right outcomes. She is currently General Manager of Growth with construction company Comdain Infrastructure. She is married, has three children and a dog, and lives in Melbourne.
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wateraustralia update
The US – A Natural Water Partner Les Targ – CEO, waterAUSTRALIA Over recent years, Austrade, led by its Regional Manager Americas, Grame Barty, has been working to raise Australia’s water profile in the United States. Austrade’s efforts have aroused considerable interest, most notably in the south-west corner of the US which embraces California, Nevada, Arizona, New Mexico and Colorado. US water authorities are keenly interested in what Australia has achieved in the water sector and, equally, Australia is open to the US experience. The World Bank in Washington DC has also shown considerable interest in Australia’s water capabilities and is a key part of Austrade’s US activities. The credibility enjoyed by Australia with US audiences has been confined in the main to our Government and utility sectors, which have done such outstanding work around issues such as water trading, demand management, major project facilitation and balancing various stakeholders’ needs. Industry’s role in supporting the Government sector has not been well publicised and, as a general consequence, Australian industry capability is not fully understood, with the exception of our internationally successful larger consulting and services firms.
Over the past 12 months, since the establishment of waterAUSTRALIA, we have been communicating with Austrade as to how best to build the Australian water industry’s profile in the US as the next logical step in its US strategy. As a result, Grame Barty and his team developed an excellent program of events in conjunction with the 2011 G’Day USA program held in January. The program included participation in: • The Cities of the Future Conference, San Diego, CA; • The Australia – USA Water Series Forum & Industry Mission, Los Angeles, CA; • Forum on Global Water Crisis: Challenges and Opportunities for Clean Energy, Sunnyvale, CA; • The Colorado Water Congress Convention – Water Forum and River Systems Management, Denver, Colorado; • Water Forum: Energy and Water Conference, Houston, Texas; • World Bank Water Forum: Living with Climate Change, Washington, DC; and
Achieving Our Potential
• United Nations Water Forum, New York.
waterAUSTRALIA shares Austrade’s hypothesis that Australian industry has significant opportunities in the US market and has not yet achieved its potential there. More broadly, beyond business there are likely to be substantial benefits to flow both ways from a more systemic approach to collaboration between our two countries on water. Apart from benefits for each other’s customers, a closer collaboration with the US water sector could also yield benefits for developing countries confronted with water infrastructure crises.
These events highlighted the many similarities in water challenges being faced by both countries and further reinforced the desire on both sides for a closer relationship on water. There are several common issues which naturally draw policy makers, regulators, scientists and engineers from our respective countries together to build the collective knowledge pool. As just one example, there are significant parallels between the Murray-Darling and Colorado river systems. The US participants were enthusiastic and engaged our delegates in many purposeful discussions, and ongoing networks were formed.
Sharing science, research and educational resources, as well as technologies, seems such a natural thing to do between long-standing allies that not only face common water challenges, but also enjoy common values and compatible Government, legal and administrative systems. Austrade has been investing heavily into what it describes as “Water Series” events, held in conjunction with the high profile G’Day USA promotion. These events have been tremendously supported by Commonwealth and State Government water agencies with world-class experts who have fought water shortage from the trenches and who present their experiences in a compelling yet modest way. In short, they have built an image of Australia as an innovative solver of significant water problems.
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The commercial result of the mission was also very encouraging – six of the participating SMEs were able to quantify the opportunities they are now pursuing as a direct result of the mission at over $125m. This is just the tip of the iceberg. This is exactly the reason why waterAUSTRALIA was formed and it is now working closely with the Water Supplier Advocate, Austrade, Commonwealth and State Government water and trade agencies and industry on a national strategy for the US. See the waterAustralia column in the next issue of Water Journal for more information on this initiative.
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International A new study by the National Academy of Sciences suggests that as urban populations around the world continue to grow, water shortages in cities will become even more severe. The study, Urban Growth, Climate Change and Freshwater Availability, suggests that by 2050 almost a billion people will live with less than 100 litres of water each per day, while another 3.1 billion people in cities around the world will confront water shortages on a seasonal basis.
the Murray–Darling Basin, but it is expected that many of the findings will be applicable to other river and wetland systems.
The National Water Commission and WSAA have developed a new Integrated Resource Planning model for water planners around Australia. The web-based tool can be applied to any urban water supply in Australia. The new tool is part of a project designed to build capacity and improve planning by urban water utilities and to assist the urban water utility sector and Local Government water managers to better incorporate community values and public benefits as part of their water planning and investment decisions.
National Tenders for water purchases in the southern-connected Murray system in Victoria and South Australia and Queensland Lower Balonne catchment have opened. The Federal Government’s approach to announce smaller and more regular tenders for buybacks in the Murray-Darling Basin aims to give communities confidence in a steady, measured pace of water purchasing.
The National Water Commission has released a technical report examining the impact of climate change and variability on diffuse dryland groundwater recharge in the Murray-Darling Basin. The report is the first output of the ‘Investigating the Impact of Climate Change on Groundwater Resources’ project. The research was undertaken by CSIRO in close collaboration with the Murray-Darling Basin Authority to support development of the Murray-Darling Basin Plan.
Water sector representatives have expressed broad support for the emerging findings in the National Water Commission’s 2011 assessment of water reform progress. In a recent stakeholder forum, more than 50 irrigation, environment, Indigenous, urban water, research and industry representatives expressed a strong view that priority should be given to the “unfinished business” in the National Water Initiative (NWI), and highlighted the need to inform and engage the community so that the decision-making process can take full account of local knowledge and concerns. The success of the NWI in establishing well-defined entitlements and opening up the water market was noted.
The latest Organisation for Economic Co-operation and Development comparison of the environmental behaviour of households in 10 member nations found that, of the 10 nations surveyed, Australians are among the least satisfied with tap water, but are also among the least ready to drink bottled water. Eighty-eight per cent of Canadians drink bottled water compared to 30% of Australians. Australians are almost twice as likely as Koreans to have water-efficient washing machines, showers and toilets.
CSIRO is working with other leading Australian research organisations to develop science which will support improved management and assessment of the health of Australia’s river and wetland ecosystems. The research will initially focus on
14 MAY 2011 water
Ministers from across the Murray-Darling Basin have met to discuss a broader approach for governments and communities to develop and implement a plan for the Basin. Ministers agreed the need to better align Commonwealth and State programs and policies aimed at improving water use efficiency and infrastructure programs, recovery of water for the environment and environmental water use and infrastructure. This would go beyond the work being undertaken by the Murray-Darling Basin Authority.
The Australian Water Recycling Centre of Excellence has awarded $200,000 in funding to the development of a National Validation Framework for water recycling. The framework will provide a consistent and efficient approach to validation, which does not compromise the safety of the water recycling process. Australia has national guidelines that set recycled water quality requirements. However, each State and Territory has its own validation approach, often with different criteria and testing requirements.
The National Water Commission has released a new report, Urban water in Australia: future directions. The report calls for changes to institutional and policy settings in the urban water sector in order to improve performance now and in the future. According to the NWC, incentives are needed to encourage utilities to invest not only in securing water supply, but also in more innovative, cost-effective and fit-for-purpose services. AWA welcomed the report but urged the Government to be strategic and targeted in its future reform efforts, focusing on the few core areas that will deliver real value to the community, the economy and the environment.
South Australia A draft policy issues paper to help shape a Water Allocation Plan for the south-east region of South Australia has been released by the State Government. A comprehensive review of water science in the region has also been released, which will underpin planning and management of water resources in the region through the water allocation plan.
Construction has begun on an $8.7 million wetland project to capture stormwater for use at the Adelaide Botanic Gardens. The system will divert stormwater from First Creek as it enters
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crosscurrent the gardens, treat it through the wetlands and then store it in an underlying aquifer. The State Government has contributed $5.35 million to the project, while the Adelaide and Mount Lofty Ranges Natural Resource Management Board has also contributed $450,000.
The South Australian Government is monitoring the River Murray between Mannum and Wellington to determine the impacts of acid drainage water which has been discharged from some salt drains. Acid water has been detected at nine salt drains in the Lower Murray Reclaimed Irrigation Area and further drains are currently undergoing testing. The acid drainage water is likely to be a result of the unprecedented low river levels during the recent prolonged and severe drought.
The Government in South Australia has commenced a process to account for water demands and supplies in the Northern and Yorke region of the state, including consideration of the impacts of climate change and population growth. It will set a baseline of regional water resources and the demands upon it; take stock of all water resources for drinking and nondrinking purposes; the current and projected future demands on these resources; and the likely timing of any possible future demand-supply imbalance.
Adjunct Professor Don Bursill, AM, has been appointed South Australia’s new Chief Scientist. As Chief Scientist, he will help to raise the State’s Research and Development profile and ensure research and development capabilities support important and emerging industry sectors such as health, resources, defence and agriculture. Professor Bursill is the Chair of the Ozwater’11 committee.
Work has commenced to remove the remaining section of the bund in the Narrung Narrows in South Australia in order to fully reconnect Lake Albert with Lake Alexandrina for the first time in three years. Removing this temporary structure is expected to further help reduce salinity levels in Lake Albert by restoring natural flows from Lake Alexandrina. The bund was built at the height of the drought in the Murray-Darling Basin in March 2008, when record low inflows saw the water level in the lakes and Goolwa Channel fall to around a metre below sea level.
Enhanced Level 3 Water Restrictions in place across the Eyre Peninsula have now ended and been replaced with Water Wise Measures. Improved recharge into the region’s Southern Groundwater Basins and lower water usage by SA Water customers has led to an improvement in the region’s current water situation. Water consumption in 2010 in the Eyre Peninsula community is almost one gigalitre lower when compared to 2009.
Eminent hydrologist Dr Tony Minns has been appointed first Director of the $50 million Goyder Institute for Water Research. Dr Minns is a graduate of the University of South Australia who has pursued a career in water in Europe since 1985.
16 MAY 2011 water
Victoria A Monash University graduate has designed a sustainable water purification device that can produce up to three litres of clean water every day. The ‘Solarball’ absorbs sunlight and causes dirty water contained inside to evaporate. As evaporation occurs, contaminants are separated from the water, generating drinkable condensation. The condensation is collected and stored, ready for drinking. The product was designed to help the 900 million people around the world who lack access to safe drinking water.
The final section of pipeline for the $650 million Northern Sewerage Project has been installed 64 metres underground. The new infrastructure will increase the capacity of the sewerage system for Melbourne’s northern suburbs, ensuring the sewerage system keeps pace with the expected population growth in the suburbs.
The Victorian Government has announced that Melbourne will remain on Stage 2 water restrictions in order to give dams in the region a better chance to recover without impacting severely on Melbourne water users. Many storages around the state have recovered significantly in the last few months; however Melbourne’s dams are still only a little more than half full.
New South Wales The NSW Government has donated $1 million to Japan’s Disaster Relief Appeal following this month’s devastating earthquake and tsunami. “Anyone who saw the shocking pictures out of Japan could not feel anything but sorrow and despair for its people,” said NSW Premier Mr Barry O’Farrell.
Water will be incorporated into the Department of Primary Industries instead of having its own ministry in the new Liberal State Government cabinet. Katrina Hodgkinson has been appointed to the role of Minister for Primary Industries and Water, and her portfolio covers water and environment issues that relate to primary industries.
Northern Territory Residents of Alice Springs are being urged to cut water use through a $15 million plan that aims to drive smarter, more efficient use of water in homes, businesses, parks and gardens. The Alice Water Plan project will increase water recycling, provide additional rebates and retrofits for customers and encourage the installation of smart water meters to allow Alice residents to monitor their water use. The plan aims to reduce water use in the region by 1600 megalitres per year.
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Queensland Queensland Minister for Energy and Water Utilities, Stephen Robertson, has announced that he will not contest the next State Election. Mr Robertson was responsible for introducing the Water Resource Plans throughout Queensland and developing the SEQ Water Strategy.
The Queensland Government has launched new online tools and information for wetlands managers and planners. The new best practice Queensland Wetland Buffer Planning Guideline tool will help planners and managers design the most appropriate buffer to stop the impacts on Queensland wetlands of development and other threatening activities.
A SEQ Water report on the operation of Wivenhoe and Somerset dams during the January floods has been released by the Department of Environment and Resource Management (DERM). The report addresses its compliance with the Flood Mitigation Manual for Wivenhoe and Somerset dams and the
Western Australia The Environmental Protection Authority (EPA) has rejected a proposal from Vasse Coal Management to develop a mine in the Margaret River region. The EPA considered there are likely to be significant impacts from the proposal on the Leederville and Sues Aquifers, including the social surrounds of the region.
An online calendar partnering Indigenous weather knowledge with western science has been launched by the Kimberley Land Council, the Mirima Language and Cultural Centre and the Bureau of Meteorology. The Miriwoong Interactive Seasonal Calendar captures the six seasons of the east Kimberley and is the result of the Miriwoong traditional owners sharing their knowledge of weather and climate through paintings and documentaries.
Water Corporation has launched a new water saving program in a number of towns in the south of the state. H2ome Smart will provide residents with one-on-one advice from a consultant on areas where water savings could be made. It is expected that the program will save more than 415 megalitres of water each year.
scope for potential changes in dam operational arrangements related to flood mitigation. It notes that the combined effects of the Somerset Dam and Wivenhoe Dam did reduce flood damage downstream; however it was not possible to fully mitigate the impacts of the flood without putting the safety of the dams at risk.
The Queensland Government has announced changes
The Economic Regulation Authority of Western Australia (ERA) has released the final report on its Inquiry into Water Resource Management and Planning Charges. The inquiry provides the West Australian Government with a range of recommendations for the recovery of the water resource management and planning expenses incurred by the Department of Water. The ERA has recommended licensed water users be charged an annual fee, which would allow the department to recoup $14 million.
to the South-East Queensland Water (Distribution and Retail Restructuring) Act 2009. The changes will cap distribution and retail annual water and sewerage price increases at CPI, which currently stands at 2.7 per cent. The Local Government Association of Queensland has criticised the changes, stating
A new pipeline will be constructed in the Carnarvon horticulture district to deliver a reliable water supply for growers. The pipeline will provide irrigation across the entire Carnarvon horticulture precinct in order to support intensive agriculture development.
that the “so-called cap on water prices contains no commitment to reduce bulk water charges, which are the major driver of price increases”.
The Commission of Inquiry into the Queensland Floods has opened for public hearings. The commission will review the lead-up to, response and aftermath of the floods which affected 70% of the state in January 2011. Submissions from interested individuals and organisations are available for download.
Tasmania Tasmania’s independent Economic Regulator has released its third annual review of the state’s urban water and sewerage industry. Drinking water quality across the state remains an issue, with 24 permanent boil water alerts in place to manage the potential risk to public health. The performance of the state’s wastewater treatment plants (WWTPs) continues to be a problem, with 71 out of the 78 WWTPs underperforming against the compliance limits set by the Environment Protection Authority.
Australian Capital Territory The Australian National Botanic Gardens will be irrigated with water from Lake Burley Griffin, saving up to 170 megalitres of Canberra’s drinking water each year. A new $2.9 million pipeline will draw the Gardens’ irrigation requirements from the Lake.
18 MAY 2011 water
Southern Water has started to roll out water meters across southern Tasmania. According to Southern Water, the introduction of meters will deliver a fairer two-part pricing system, which allows customers to pay a fixed fee that contributes to pipes, treatment plants and dams, and a variable fee allowing people to pay only for the water they use.
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Member News AECOM is expanding its national operations within the water sector, which includes the appointment of three key specialists: Bill Barber has recently joined the company as Technical Director for Biosolids and Wastewater Treatment, operating across Australia and New Zealand. Bill joins from United Utilities in the UK, where he was a Technical Specialist for Biosolids and Sustainability, so brings an international perspective to the local biosolids market. Bill is based in Sydney. Peter Hillis (also previously with United Utilities in the UK) has taken up the role of Technical Director for Water Treatment. Peter specialises in water treatment process design and membrane technology. He is based out of Melbourne but operates across the Australian and New Zealand region, and supports AECOM’s global water treatment practice. Malcolm Brassey (previously with Laing O’Rourke) has recently joined AECOM in the Sydney office in the role of Technical Director for EPCM & Program Management, operating across the Australia and New Zealand markets. Prior to moving to Australia, Malcolm ran similar program management businesses with Atkins and MWH in the UK.
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Erik Tynes, PE (California and Florida) and marine biologist, has recently been appointed as a Senior Process Engineer with GHD in the Perth office. Erik had major input into the design and commissioning of the Luggage Point Advanced Water Treatment Plant in Brisbane.
Veolia Water won a National Infrastructure Award for operator and service excellence at Sydney’s Desalination Plant at the annual awards night in March, organised by Infrastructure Partnerships Australia.
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The Water Services Association of Australia (WSAA) has been recruiting for a successor to outgoing Executive Director Ross Young who left the organisation in April 2011. Ross will take up the role of Business Leader Water Australia with GHD.
Black & Veatch has expanded operations in Brisbane, moving to new premises and making a number of key appointments and transfers. Richard Dagwell, Managing Director of expanded scope projects in Asia Pacific for Black & Veatch’s global water business, has also returned to Brisbane from the Perth office.
Allen Gale has been appointed MD of Parsons Brinckerhoff India. Allen is a past Federal President of AWA.
MWH has appointed Hayden Pauley to the position of NSW Business Development Manager. Hayden will be responsible for growing the company’s water business. Hayden has been with MWH since 2009 and previously worked for United Utilities Australia (now Trility Pty Ltd) and Sydney Water Corporation.
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industry news MDBA Chair’s Speech Following a tour of the Basin, Mr Craig Knowles made this landmark speech on 6 April to the Sustaining Rural Communities Conference in Narrabri, NSW. Good morning to you all. At the outset I would like to acknowledge the Gomilaroi community and pay my respects to them, the traditional owners of the land. Can I also thank Mal Peters, an old partner in crime, for the personal invitation to talk with you this morning. Indeed, to all the distinguished guests and particularly the Mayor of Narrabri, thank you for the invitation. In the context of a conference that is all about sustaining rural communities I think it is important, right at the front end of my remarks, that I acknowledge my work is all about re-engaging people who have been left out of the process to date and to ask for your help in making the work I do better and more relevant to the people who live and work in the Murray-Darling Basin. It is no secret that I have a poor opinion of the Guide that was released last year. But it’s time to move on. I have said that I do not have a high degree of ownership of the Guide and that both symbolically and practically my appointment as the new Chair is a chance for a fresh start. So over the last couple of months I’ve begun the process of re-engagement. In short summary, I’ve been criss-crossing the Basin talking with and listening to local communities. I’ve been talking to your governments, the Ministers and the Sir Humphries, and of course I’ve been talking to all the peak industry groups in an attempt to restart a conversation which stalled last year. I haven’t added them up, but I think the meetings are now in their hundreds, as are the phone calls and the conversations, and I can tell you that the messages are pretty consistent. • People want to have a say; they don’t want to be ‘consulted’, they want a chance to have a conversation; • People want to have their historic efforts recognised; • They want certainty, but it’s a certainty that has a future; • They want me to get on with things and not delay; • People understand that balance is the objective – you can’t have a healthy environment without a healthy economy and you can’t have healthy economies and strong social fabrics unless your river and landscapes are constantly nurtured and in a strong state of health; • In particular, people who work the land find it insulting to be accused by some sections of the community of being environmental vandals. Many of those farmers have a generational attachment to the land and a vested interest in maintaining a healthy landscape – next year’s profit and their legacy for future generations of their family depend on it; • Likewise, aboriginal communities have a 40,000-year-plus attachment to the land. Their cultural and spiritual heritage and beliefs need to be respected and taken into account; • People warm to the concept of a healthy working Basin; they understand that the Murray-Darling is a major contributor to our Nation’s wealth. It provides food and fibre as well as jobs and homes for literally hundreds of thousands of people;
22 MAY 2011 water
• People expect their governments to be better at managing water – the stories of the left hand not knowing what the right hand is doing are too numerous to mention and it’s about time we got it right, that the processes of buyback and infrastructure funding and State Government programs, as well as the role and functions of the environmental water holders at Commonwealth and State levels, be better aligned and more streamlined to serve and benefit communities rather than tie them up in more red tape; • And, most of all, people will tell you (as they have told me for the last 25 years of my public life) that if they are just given the resources and the opportunity and a degree of trust they can deliver at a local level the results that are just impossible to deliver if you try and do it from Capital Hill. So these are the messages from the valleys. And I want to assure you that I’ve taken them direct to the Ministers who oversee water, right around the Basin. Just last Friday all of the Water Ministers met in Sydney and signed off on an agreement which is fundamentally important to the work that we are now undertaking. All the messages I’ve just read to you I told to them. I can assure you that they heard them loud and clear, and in return, they demonstrated a clear commitment to a better way forward. Specifically a commitment to: • Work more closely together; • Review all of the opportunities to better align programs like buyback, infrastructure programs and environmental water management; • And, perhaps most importantly, they signed off formally on a commitment to strengthen the involvement of local communities in the design and rollout of State and Commonwealth programs right across the Basin, including the Basin Plan. These three points are fundamental. The first, about working more closely together, sends a clear message to State and Commonwealth bureaucracies, including the MDBA, that the Mexican stand-off that has been in place for the last couple of years over water is now at an end. There is a clear expectation by Ministers that their senior officials will work together, share information, develop practical solutions and create workable, sensible water-sharing plans that can be implemented in a coordinated and rational fashion. Importantly, the Ministers have agreed to meet on a regular monthly basis to benchmark performance. The second point is about making sure that the very large buckets of money in buyback and infrastructure programs are put to work in better ways to deliver better results. I make the point that the draft Basin Plan which will go on exhibition in the middle of this year will only be successful if it is cast in a context of a more holistic plan for the Basin. How buyback is used, how infrastructure money is employed to do clever things in environmental management, as well as on-farm and off-farm works, will be critical to the implementation of the Plan. Equally, how the Commonwealth and States manage environmental water in the context of a market-based system will be vital to the success of any water management plan produced by the MDBA. The Governments’ collective agreement to better align all of these programs and, along the way, speed up the processes of implementation, gives me great hope that we are at last getting onto the same page. And finally, the Ministers’ decision on localism is the real breakthrough. Many of us know through our own experience that the best results,
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The Basin is full of examples where, with some resources and some authority, local groups are already working in partnership, striking the balance between production and environmental needs. There are lots more – in fact, after I leave here this morning I’m going to have a look at some more local initiatives here in the Namoi. Of course, what this is all about is an understanding that the fine-grained solutions to Dartmouth Dam, Victoria, which is operated by Goulburn-Murray Water on behalf of the MDBA. finding the balance and managing river health is What that means is that there will be ample time to use best done by local people who know their part of the river the processes of infrastructure funding, buyback, environmental with intimate and detailed knowledge. water management to continuously move toward achieving the plan. In some river valleys the plan will be achieved early in It’s a recognition that solutions that might work in one the period; other places will take longer. catchment or on one river system might not work in another – river management really is about horses for courses – and It also means that there will be time to interrogate the to pretend that you can develop the detailed solutions from draft plan on a catchment-by-catchment basis. I envisage Canberra or Macquarie St, Sydney, is simply naïve. that the numbers will be challenged. As I said earlier the numbers that I produce in the next couple of months should Years ago I developed Catchment Management Authorities be the start of a process of implementation rather than the in NSW in an attempt to devolve land and water management end of a conversation. away from the centre and empower the regions. Years later my belief that local communities are more likely to get it right Logically that implies that, if it can be demonstrated that the remains undiminished. That’s why I’m so pleased that the environmental objectives for a given catchment can be achieved Ministers have decided to start a conversation about what with a different regime of water management, then we should localism might mean in the management of water. be willing to accept the evidence. It is really important that you all join in and have your say, because the work that is currently underway in the development of the draft Basin Plan will be encouraging localism too. In that context I want to give an opportunity for local communities to take ownership of the plan and manage their part of the system for the long term. The plan we put out in the next couple of months will, of course, comply with the Act and it will contain our best estimates of the sustainable diversion limits and the environmentally sustainable level of take. But the big thing that will be different to the Guide is that these numbers will not be an end point; they will be the start of a process, a process to turn my plan into our plan. Where the Guide gave the image of a big cut all happening on one day, our process will talk about how much we’ve already done and what’s left to do. We will have regard to our history of effort. In addition, the water sharing plans of the States need to be better aligned. As you know, water sharing plans in each State have different end dates ranging from 2012 in South Australia through to 2019 in Victoria, with other States somewhere in between at around 2014 and 2015. I think it is inevitable that alignment will occur around 2019.
Photo: murrayriver.com.au
and the ones that last, are those that come from local settings.
This process within the context of a proper strategic framework, which is the Basin Plan, gives more time for regional communities to adjust and take ownership of finding solutions for improvements in water use efficiency. By taking ownership we provide a higher level of certainty that the solutions that are developed are ones that will last and be accepted by local communities. Part of the work will be to develop the process of how that can happen, and as I’ve said I believe it’s more likely that local processes and local engagement will produce better results. So unlike the Guide, the next few months presents an opportunity to those of you who want to engage in the process and to build a framework for local implementation. It’s a chance to take control of the agenda and do the things you’ve told me you can do if only the Government would give you that chance. Well the opportunity is here, now. If you choose to take it I am confident that the Basin plan can be a collaborative effort, owned and operated by local communities, not a competition between conservation and production and a plan which will underpin, for generations to come, a healthy working Basin.
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industry news Time to Take the Politics out of Water? The release of four reports within one week in April from different Government bodies shows how highly political the urban water industry has become, says Water Services Association of Australia (WSAA). The securing of clean drinking water is a fundamental human need, with a focus on planning for healthy, liveable cities, says the organisation, and taking the politics out of water planning would avoid expensive political turnarounds and short-term thinking. According to Adam Lovell, WSAA Acting Executive Director, “The urban water industry welcomes the debate to develop efficient options for the pricing and delivery of water services, as long as it benefits our customers. We trust our water utilities to take care of our health, which they do efficiently and well, but when it comes to water planning for our cities, the industry is hampered by politically motivated decisions. “We urge Queensland to stay the course on the National Water Initiative and previous COAG reforms. A return to userpays, full-cost reflective pricing must be back on the agenda. We are cautious about the merits and practicality of scarcity pricing at the bulk supply level, and support the view of the National Water Commission that this requires further detailed analysis. To be considered worthwhile it must demonstrate it delivers real benefits to customers.” Reform of regional Queensland and New South Wales urban water services is a priority issue, Lovell continues. The regionalisation of Victorian water utilities is largely a success story and Tasmania has shown its commitment to reform with three new utilities for the whole state. These reforms deliver economies of scale, sharing of resources, more efficient capital investment and the ability to attract skilled staff to an incredibly important part of the Australian economy. Investment in maintaining and renewing critical infrastructure should not be constantly delayed by short-term thinking. ‘Justtoo-late’ maintenance doesn’t work and future generations will face increased costs as a result, concludes WSAA.
Report on the Future of Urban Water Praised by Irrigation Australia Trevor Le Breton, Acting CEO of Irrigation Australia Ltd (IAL) has welcomed the report released last month by the National Water Commission entitled: Urban Water in Australia: future directions. Mr Le Breton says he is looking forward to working with both the National Water Commission and the Council of Australian Governments (COAG), for the benefit of the Australian community and of Irrigation Australia’s members. “Now is the time, whilst we have reasonable levels of water storages, to work on strategies to ensure that water conservation measures are sustainable into the future. We encourage the jurisdictions to continue with ongoing water conservation measures to ensure we meet the needs of open space and public health, and to use this water efficiently. We must separate supply of water for human needs (e.g. drinking, washing, household), from industry and irrigation (both domestic/household), and open spaces such as parks, gardens, and playing fields,” says Le Breton. “It is inevitable that water prices will continue to rise, but we need to ensure the entitlement to green space is not linked to wealth. Our open spaces are there to be enjoyed by all in the community. We need a sustainable approach to achieving this efficiency. To that end, Irrigation Australia welcomes the opportunity to work in a partnership approach with the water authorities to inform their customers regarding irrigation efficiency, standards and guidelines.”
A sustainable approach to water is essential to ensure that green spaces such as parks remain available to all in future.
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24 MAY 2011 water
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industry news Asia-Pacific Sanitation Conference It’s well-known that many Asian and Pacific regions lack adequate household sanitation and face an urgent need to treat wastewater and clean up its waterways. Just ask 1.8 billion people or take a walk along any Asian river. Yet this terrible state of affairs for many offers great opportunities for Australian business to get involved in partnerships with Governments, Development Agencies and NGOs. “Making Sanitation a Sustainable Business” is a major strategic initiative of the Asian Development Bank and its partners, including AusAID. The forum, which takes place May 23–25 in Manila, Philippines, will bring together over 200 government decision-makers, financiers and private sector representatives to share solutions, explore partnerships and develop action plans. Private sector firms will showcase products and services at the trade exhibition and sanitation and wastewater management investment opportunities will feature. For details email SanitationDialogue@adb.org or go to www. adb.org/documents/events/2011/sanitation-dialogue/default.asp.
i2O Water Signs Partnership Agreement with Malaysian Distributor i2O Water has signed a partnership agreement with Jalur Cahaya Sdn Bhd, the Malaysian non-revenue water (NRW) specialist company. Jalur Cahaya will now be responsible for the marketing and distribution across Malaysia of i2O Water’s technology to reduce water leakage.
The official signing ceremony took place in March at the Asia-Pacific Regional Water Conference (APRWC) in Kuala Lumpur, Malaysia. The international conference focuses on seeking long-term solutions to increase the global supply of clean, safe drinking water in the Asia-Pacific region. Datuk Seri Peter Chin Fah Kui, Malaysia’s Energy, Green Technology and Water Minister, attended the ceremony, while i2O Water was represented by CEO Adam Kingdon and Jalur Cahaya by Managing Director Sheikh Mazlan Sheikh Hassan. The Minister also visited the i2O Water stand, where Asia-Pacific Managing Director Gary Wyeth gave a presentation on i2O’s systems. i2O Water’s technology is being used across the UK and many other countries. Systems have been installed in Spain, Italy, Mexico, South Africa, the Philippines and Malaysia.
Abigroup Water Partners with Sydney Water for Program Alliance Abigroup Water has secured a contract to upgrade Sydney Water’s wastewater treatment plants as part of the Sydney Odour Management Program in Sydney and the Illawarra. The first stage will involve an $80 million upgrade to the Malabar, Cronulla and North Head wastewater treatment plants. The five-year Odour Management Program Alliance between Sydney Water, Abigroup Water and CH2M Hill will reduce odour at the plants through capture and treatment. Abigroup Water’s General Manager Chris Bulloch said, “We’re excited to be working with Sydney Water and look forward to delivering exceptional results. Program alliancing
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industry news is an excellent vehicle to deliver capital works and ensures consistencies and significant savings across the projects through efficiencies and economy of scale.” Sydney Water established its Odour Management Program to reduce the risk of odours impacting on surrounding communities to its wastewater treatment plants. It will also ensure Sydney Water meets its licence requirements from the Department of Environment, Climate Change and Water. Sydney Water collects and treats more than 1.3 billion litres of wastewater from homes and businesses every day. The wastewater network includes over 24,000km of pipes and services around 1.7 million homes and businesses in Sydney, the Illawarra and the Blue Mountains. Much of the wastewater at the 16 treatment plants is recycled for use by industry and for irrigation; Sydney Water also produces about 180,000 wet tonnes of biosolids annually which are 100 per cent beneficially used in agriculture, composting and land rehabilitation.
eWater CRC Appoints New International Business Development Manager eWater CRC has announced the appointment of Dr Robert Carr as Manager, International Business Development. Dr Carr was formerly President of the USA arm of DHI Water and Environment and Director, Australia, New Zealand and Canada. Dr Carr has a Bachelor of Engineering (Civil) from the University of Queensland (1980), a Masters in the Physical Modelling of Energy Dissipaters and a PhD in Surface/ Groundwater Modelling from US-based Iowa State University.
Dr Robert Carr
He is the recipient of several major awards including Iowa State’s Research Excellence prize, and was awarded a Churchill Fellowship in 1990 to investigate Drainage and Salinity Modelling Systems in Europe and Israel. Carr’s fields of special competence include Hydraulic Investigations and Design, Hydrologic Assessment, Flood Estimation and Contaminant Transport Investigations. He has extensive experience in managing urban, riverine, estuarine and groundwater data collection and modelling projects.
Sydney Water’s wastewater network services about 1.7 million homes in the Sydney, Illawarra and Blue Mountains regions.
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He is a member of the Australian Institution of Engineers Australia, CPEng NPER-3 and the Australian Water and Wastewater Association.
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industry news CEA Australia Wins Multi-Million Tender in New Caledonia CEA Australia has won a tender for the refurbishment of a 2.5km long and 1.1m in diameter steel pipeline at the Neaoua Hydro Electric Power Station in New Caledonia. The water is drawn from the dam and passes through a 2km-long concrete tunnel and the 2.5km steel pipe. The pipeline transfers water from the dam to the hydro-generating units and is the drinking water supply for the local villages. The pipeline has been in service since 1982 and is currently coated with a Coal Tar Epoxy system.
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“Inspections over the last five years have revealed that the existing coating is breaking down and areas of the coating are blistering and delaminating,” says Mr Peter Hatchard, State Manager, CEA Australia. CEA Australia has been appointed to refurbish the pipeline, to ensure a reliable supply of water to the turbines, without the prospect of corrosion causing holes in the pipeline. The scope of work includes removing the existing coating and replacing with a coating system in excess of 25 years’ service life. Challenges of the project include a drop of 470m in one section of the pipeline, and two areas which are only accessible by helicopter. The job requires CEA Australia to design and provide a custom-made machine just to access and repair the pipelines. The work must be carried out with minimal disruption to the local area and the environment, and the quality of water supply to the local village, which is normally supplied through the pipeline, needs to be maintained throughout the project duration of 12 weeks. Due to the power generation requirements there is also a limited time scale to carry out the work. For more information, please visit: www.ceaaustralia.com.au
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industry news Norit Awarded Water Technology Company of 2011
“The Goyder Institute aims to strengthen ties between science and policy to support growing economies, thriving lifestyles and healthy environments through water research,” Mr Caica said.
Norit has been awarded Water Technology Company of the Year during the Global Water Summit 2011. The award was presented by former Secretary General of the United Nations, Kofi Annan, during a special Global Water Awards ceremony on April 18 in Berlin, Germany.
The Goyder Institute for Water Research is a collaboration between the State Government, the CSIRO and South Australia’s three universities.
Every year, Global Water Intelligence (GWI) honours top performers in the world of water. The category, Water Technology Company of the Year, recognises the company that has made the most significant contribution in the field of water technology during the past year. Norit had been nominated because of its reputation for innovation and for breathing new life into an old technology – activated carbon, and pushing a new technology – ultrafiltration – further than it has been taken before. In recent years, Norit has grown into a global organisation with a strong focus on continuous innovation and environmental protection. Norit’s varied technologies, including pre-treatment for seawater desalination, effective ways to remove hormones, viruses, bacteria, and cysts from water, and high-capacity pumps and turbines that are fish-friendly, make it a market leader in a wide range of segments and at the forefront of reducing man’s impact on the environment.
Director for Goyder Institute for Water Research Appointed Eminent hydrologist Dr Tony Minns has been appointed as the first Director of the $50 million Goyder Institute for Water Research in Adelaide. SA Water Minister Paul Caica said Dr Minns is a graduate of the University of South Australia who has pursued a career in water in Europe since 1985.
International Earthquake Experts to Take on Environmental Disasters Experts in earthquakes and tsunamis from Australia and Indonesia have met at the Australian Academy of Science to explore how the two nations might collaborate to tackle global environmental problems and natural disasters. “The recent disaster in Japan has highlighted how crucial it is for the international community to have a better understanding of earthquakes, tsunamis and other catastrophic environmental events,” said Australian Academy of Science President, Professor Suzanne Cory. “Scientists are keen to work together across national boundaries to enhance understanding of how and why these large-scale natural disasters occur, and to explore ways to better protect both the natural world and the human habitat.” The 14 senior researchers came from a range of environmentrelated disciplines, including geothermal science, earthquakes and tsunamis, marine biology and oceanography. The gathering was part of a range of activities organised under the Treaty for Cooperation in Scientific Research and Technological Development, signed by Australia and Indonesia in 2005. The 2011 Australia-Indonesia Environmental Science Workshop was convened by Indonesia’s Professor Syamsa Ardisasmita and Professor James Fox of the Australian National University at the Australian Academy of Science’s Shine Dome.
“We are fortunate to entice Dr Minns back to his home town to lead the Goyder Institute’s work to enhance the State Government’s capacity to develop and deliver science-based policy solutions in water management,’’ he said. “After leaving the University of South Australia, Dr Minns completed a PhD in Hydrology at the University of Delft and has since worked for several Dutch water research and consultancy organisations. “Dr Minns joins the Goyder Institute from Dutch water consulting firm, Deltares, where he worked as the Scientific Director of Hydrological Engineering, playing a senior role in managing a research and development program for the Dutch Government.
Earthquake damage in Christchurch, New Zealand.
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MAY 2011 29
awa news Young Water Professionals (YWP)
Katrina Annan – AWA YWP Vice President; YWP National Representative Committee It is hard to believe we are almost at the end of April and it’s Easter time again. The question “Where is the year going?” can be heard throughout elevators and in tea rooms in every workplace. From a national YWP perspective, the year is going full steam ahead, as branches and committees have been as busy as ever. WA Branch is getting ready to host its inaugural Water Future Forum, where YWPs will present their current work and experiences on the topic ‘Water in Changing Climates’ to fellow YWPs to encourage knowledge sharing, interaction and professional development. Excitement is also surrounding YWP-organised group tours to the newly opened Groundwater Replenishment Trial at Beenyup. Results from the first three months of trials are proving positive, with all water samples meeting health and environmental guidelines.
Water in the Pub Northern Territory YWPs have been busy collaborating events with the Australia Health Promotion Association, including an upcoming technical session on ‘Health in All Policies for Water Security’ in late May. Their regular event on the social calendar, ‘Water in the Pub’, continues to be a great opportunity for YWPs to catch up in a relaxed manner and talk all things water (and beer). Queensland Branch’s mentoring program is off to a strong start with 13 mentee/mentor pairs enjoying a YWP-organised breakfast to kick it off. Another Queensland success was the recent workshop, ‘Hydrology: Managing Water in Queensland’, providing an informative overview of different aspects of
hydrology, including drought and flood, and their impacts on water management in Queensland. A diverse range of guest speakers from CSIRO, UQ, DERM and SEQ attracted over 100 guests. Queensland YWPs now look forward to their next workshop on 30 May, ‘Water Leaders of Tomorrow’, organised by the International Water Forum and co-supported by Engineers Without Borders. NSW Branch, meanwhile, held the first of its three seminar series for the year – ‘Water Resources NSW’. Their next seminar, which takes place in June, will focus on ‘Developing Communities and Disaster Relief’. The annual Water Careers Evening at UNSW was a great success, utilising YWP efforts to promote the water industry to university students. Approximately 100 students came to hear from a panel of five water industry professionals, representing careers across construction, consulting, research, water supply and a water industry recruiter who was able to provide students with job-seeking advice.
Victorian Regional Conference Victoria’s YWP Regional Conference in Geelong was a great success, with those attending from Melbourne utilising public transport to support YWP’s sustainability principles. Victorian YWPs also recently held a technical seminar evening looking at the past, present and future Murray-Darling Basin with a variety of speakers representing MDBA, GHD and CSIRO. And the committee has been busy welcoming new members and mapping stakeholder engagements. South Australian YWPs are bracing for the Ozwater’11 Conference in Adelaide, with more than 1300 participants already registered. The YWP Ozwater program is jampacked this year, with a workshop on Sunday focusing on the topic ‘Water Quality and Disaster Management’, ironically selected more than six months ago, before Australia’s recent disaster season. There will be a variety of keynote speakers, and scenarios covering bushfires, floods, water quality, disaster risk management and infrastructure development.
Northern Territory YWPs catching up at their ‘Water in the Pub’ event.
30 MAY 2011 water
A YWP Breakfast will be held on the Tuesday and this year YWPs are being given the chance for roles and responsibilities as Assistant Chairs for many sessions, allowing them to report and summarise key outcomes. If you are attending Ozwater be sure to ask our YWP Assistant Chairs for their opinions and summaries on the conference proceedings. And thanks to the many SA students and young water professionals who have raised their hands to help with satchel packing.
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awa news National Action Plan On a national level the National Representative Committee has been busy working through its action plan items. Watch this space for more news on the YWP Strategic Plan review, YWP committee management, including standardising roles and succession planning, YWP involvement with National Water Week, further promotion of student subscriptions and YWP social media online forums (aka Facebook). Yes, YWPs are embracing what they know best, so you will soon be able to keep up to date and interact with us more easily online.
Weather Forecast So, is La Niña over yet? As I work at the centre of forecasting expertise [the Bureau of Meteorology], I have been advised that the La Niña pattern is weakening as the Southern Oscillation Index returns to neutral. Furthermore, word from the north (Broome) is that the dragonflies are already out and about in their masses and in full colour-spectrum glory, which usually signifies the end of the wet season. However, officially the cyclone season doesn’t end until 1 May, and as I write this article [in April] Tropical Cyclone Errol has just been named situated near Kalumburu (WA). I predict there will be a lot of parties and huge relief around the end of the season when warning operations and emergency management can hang up their hats for a while. While northern Australia had record rainfall during this season, it was the complete opposite situation in the south-west, where a record number of days without rainfall was experienced – sparking the age-old debate on water supply solutions, including transporting water from the north to the south by pipelines via Kalgoorlie or
Attendees at Victoria’s YWP Regional Conference in Geelong. a canal from Fitzroy to Perth. Another notion is to encourage regional town populations over metropolitan, and new solutions include looking at towing water via cargo vessels. A comparison of annual rainfall totals to date between Brisbane (660mm) and Perth (35mm) and Gibb River in northern WA (1652mm) show further issues for Urban Water design. Furthermore, the National Water Commission has recently released its key findings and recommendations from the Urban Water in Australia: Future Directions project. All these issues, options and debates prove that we are living in a very watersensitive time and a career in the water industry is a challenging, interesting and rewarding one.
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MAY 2011 31
awa news AWA Signs New Collaborative Agreement A new collaborative agreement between two of the leading water associations in Australia is set to deliver long-term benefits for the Australian water sector. The agreement, signed in April between the Australian Water Association (AWA) and the Water Services Association of Australia (WSAA), will offer the sector a stronger and more consistent voice, as both organisations pursue the joint goal of advancing an innovative and sustainable water sector in Australia. The agreement outlines the principles of cooperation and specific areas for collaboration, including conference delivery and international relations, in order to achieve improved outcomes for the Australian water industry.
Commenting on the agreement, AWA outgoing President Peter Robinson said: “AWA and WSAA share a common vision for a world-class water sector. Working together to improve and advance the industry is in the best interests of our members and I am confident we can make great progress as a result of today’s agreement.” WSAA Chairman Kevin Young said: “WSAA welcomes this agreement, which formalises the way our two associations will work together to support the urban water industry. Tackling high priority challenges including water industry skills development, sustainable water services and international collaborations are important joint initiatives. We look forward to a continued strong collaboration.”
Call for IWAA YWP Representative Nominations – Dr Rita Henderson, Senior Research Associate UNSW Water Research Centre School of Civil and Environmental Engineering University of New South Wales, Sydney.
WSAA Acting Executive Director Adam Lovell, Chairman Kevin Young, AWA President Peter Robinson and AWA CEO Tom Mollenkopf.
Having spent over two years on the International Water Association Australia (IWAA) Committee as the YWP representative, the imminent start of my maternity leave tells me the time has come for me to step down and hand over to another YWP. We therefore call for nominations from enthusiastic YWPs with a passion for influencing decisions,
Presents
Making It Happen: Building and Communicating Your Business Case for Education for Sustainability A one-day workshop giving you tools to write a successful business case
This workshop will focus on practical aspects of building a business case. A ‘template’ for a business case will be provided and worked through by undertaking a series of interactive activities as part of the workshop. Time Dates
9.30am – 4.30pm June 14 SA Water Learning Centre, SA Water House Level 1, 250 Victoria Square, Adelaide June 23 Water Recycling Education Centre, Gate 4, 33-73 Links Road, St Marys (UBC Ref 165 E2) Sydney
Workshop Provider
32 MAY 2011 water
Cost $440 (incl. GST) NPDISE organisation members; $495 (incl. GST) non-members Registration Please visit our website: www.npdise.com.au Want more information? Contact Terra Cordis Pty Limited (our RTO Partner) P: 02 9453 1396 E: admin@terracordis.com.au Workshop supporters
Government of South Australia
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awa news organising events and implementing change within the water sector, both nationally and internationally. As the IWAA YWP representative you will not only join the IWAA Committee but also the YWP National Representative Committee, currently chaired by Amanda Hazell, lending the opportunity to participate within both the rapidly growing national and international IWA YWP communities. Indeed, after signing up for the role of IWAA rep, I was selected to join the IWA YWP committee (2008-2010), although this is not a prerequisite of the IWAA YWP representative position. My time as IWAA YWP representative has certainly been enjoyable and rewarding! I have written articles on Australian YWP activities for a number of different publications including both the AWA and IWA YWP newsletters and magazines, Water Journal and Water 21. I was also invited to Japan to talk to the newly formed Japanese IWA YWPs about the exciting initiatives that are being implemented by young people in Australia. However, I believe my greatest achievement was the Chairing of the IWA International YWP Conference that was held in Sydney, July 2010 – thanks to all those who participated in this memorable event. I have no doubt that my contributions on the IWAA Committee played a large part in my being awarded the IWA YWP Award for 2010, which enabled me to attend the IWA World Water Congress in Montreal, Canada. I would like to say a big “thank you” to everyone who has provided me with the support required to make such positive contributions during my term as IWAA YWP representative.
Getting involved in committees like the IWAA can certainly assist in kick-starting your career in the water sector and I hope this invitation will inspire you to consider becoming the next IWAA YWP representative. Please email Despina Hasapis at AWA (dhasapis@awa.asn.au), to register your interest, including a copy of your CV with relevant experience to date.
Healthy Catchments, Healthy Communities National Water Week is just a few months away. This year the annual water awareness event takes place from 16–22 October. The 2011 National Water Week theme will focus on catchment management, under the tagline Healthy Catchments, Healthy Communities, in order to educate communities about the importance of taking care of our catchments. AWA is responsible for coordinating National Water Week across Australia, engaging with local communities and the water sector to foster grassroots participation in the week. A range of materials is currently being developed to help raise awareness of National Water Week and encourage organisations and individuals to get involved. Look out for these on the National Water Week website. Importantly, if you are hosting a National Water Week event, don’t forget to register the details on our website. It is an effective way to promote your event For more information about National Water Week, please visit: www.nationalwaterweek.org.au
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AWA - May & September issues
MAY 2011 33
awa news National Water Week Ambassador Initiative
AWA Anaerobic Digestion Workshop Report
AWA is looking for members to take part in the 2011 National Water Week Ambassador Initiative. Launched last year, the initiative aims to raise awareness of water issues among local communities. We estimate that over 6,000 young people were reached through the initiative in its first year.
This single day workshop, which took place 12 April 2011 in Sydney, is the first that AWA has organised in the Master Class format. The aim of this and subsequent workshops is to focus on different process improvement strategies, new and emerging technologies or new investigative tools that will improve the operation of core water and wastewater services delivered by AWA’s members.
In 2011 we plan to grow this initiative, reaching more schools and young people during National Water Week. There are also plans to build on the educational resources provided to ambassadors and schools. In short, the National Water Week Ambassador Initiative will be bigger and better in 2011. Feedback from teachers and community group leaders suggest they really valued the initiative and welcomed the opportunity to have a water professional visit their school. If you are interested in becoming a National Water Week ambassador please go to the National Water Week website at: www.nationalwaterweek.org.au
The NWW Ambassador Initiative helps raise community awareness.
In the past 10 years the focus of wastewater treatment has shifted to the recovery of resources from wastewater: water, energy and nutrients. Anaerobic digestion has recently become the preferred process as it produces biogas that could be used to heat the digesters to improve performance and reduce operating costs. It yields the following products: • Biogas, as green energy on its own or via co-generation of electricity. • Biosolids for beneficial use in various markets: agriculture, forestry, mine rehabilitation, compost and potentially energy production. The characteristics of biosolids product (such as stability, nutrients, odour emission, solids content, texture etc) determine the most suitable market. Many of the major utilities such as Sydney Water, SA Water and the Water Corporation in Western Australia have been conducting a series of optimisation projects to improve the performance of the existing digestion processes at their wastewater treatment plants to meet the challenge of this shift to resource recovery focus, particularly in regard to biogas. In addition, many of the major utilities have problem plants whose performance is lagging due to a variety of problems that differ with each facility. The Anaerobic Digestion Workshop heard from wastewater engineers at each of these utilities on their experiences in dealing with these challenges, while also hearing from academics researching specific aspects of the treatment processes with a goal to further improvements.
Workshop Speakers Dr Paul Jensen from the Advanced Waste Management Centre (AWMC) at the University of Queensland looked at the process of assessing the efficiency of digestion processes at STPs. This involves relating the fraction of biologically degradable material removed in the process to the stability of the final biosolids product. Consideration is also given to the resources required to achieve this level of stabilisation in terms of capital (reactor volumes, supporting infrastructure) and energy usage. The biodegradability and bioavailability of organic sludges under anaerobic (and aerobic) conditions represents a benchmark for potential digester performance and can be represented by two key parameters – degradability, or the percentage that can be effectively destroyed during digestion, and 1st order hydrolysis coefficient, or the speed at which material breaks down. Professor Paul Slatter, from RMIT University, took an even more basic approach by focusing on the flow properties of sludges. He began by defining rheology (from the Greek “rheos” – flow – and “logos” – knowledge) as the science of flow phenomena. The eminent physicist Sir Isaac Newton postulated a direct proportionality relationship between the shear stress and shear rate in a fluid. The viscous characteristics of
34 MAY 2011 water
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awa news sewage sludge do not follow Newton’s law. Hence, rheology can be defined generally as the viscous characteristics of a sludge. According to Professor Slatter, understanding the hydrodynamics of wastewater treatment sludges requires an understanding of sludge rheology. This approach serves as a fundamental precursor to efficient engineering design in the wastewater treatment industry. Associate Professor Damien Batstone from AWMC, highly regarded for his expertise in modelling anaerobic digestion processes, pointed to a number of the challenges in model application, identification and utilisation and practical applications of the anaerobic digestion model 1 (ADM1) for process evaluation. He explained that modelling has been extensively applied for activated sludge processes, mainly to optimise the process across the range of degrees of freedom in design and operation. These can include sludge age, mixed liquor suspended solids, aerobic fraction, clarifier inventory, and sludge and external recycle rates. Anaerobic digestion lacks these degrees of freedom in operation: the main design parameter is digestion time. Dynamic modelling using the ADM1 is highly useful to design, diagnose and optimise processes, as its biochemical structure closely mimics the known processes in anaerobic digestion. In returning from theory to practice, Tim Shea, from CH2M Hill, talked about his consulting experiences involving the tricky matter of fats, oils and greases needing to be processed at waste facilities. He drew attention to the fact that the acceptance and processing of fat-oil-grease (FOG) wastes from trucks at municipal wastewater treatment plants (WWTPs) is of increasing interest. These materials need to be kept out of wastewater collection systems, while at the same time they offer added energy recovery potential when FOG wastes are anaerobically digested or incinerated. The addition of FOG wastes to the WWTP usually requires at some point the co-mingling of FOG waste and sludges or biosolids, and usually in a process that utilises the energy from FOG such as anaerobic digestion or incineration. The manner in which this is done can impact the performance of the anaerobic digesters or thermal oxidation unit, as well as other solids handling processes, and so must be done properly.
Tim presented a series of examples where FOG waste had been accepted and co-processed with sludge with varying degrees of success. Problems which were encountered included: blockage of pipes and pumps; digester foaming; grit accumulation in digesters; “stuck” digesters (curtailed methanogenesis); clogging of gas collection and handling systems; flashback and air emission exceedences in multiple hearth incineration systems; and excessive downtime for maintenance.
AWA Water Directory 2011 Out Now
The Australian
Water Directory
The Australian Water Directory is AWA’s essential guide to the Australian water sector. It features a comprehensive ‘Who’s Who’ of the industry, as well as facts and figures, contacts, a buyer’s guide and a useful overview of industry bodies, regulation, education and changes in the sector. The Directory is the perfect space for AWA members to showcase their business.
2011
An invaluable resource and reference tool for the Australian water industry
Copies are available for $80 (inc GST) by contacting AWA on (02) 9436 0055.
Climate Change Adaptation Course Developed in response to a call from AWA members, this course will assist attendees in developing a better understanding of the adaptation risks their organisations face due to climate change, help them to take the first steps in developing a climate change adaptation plan, and identify tools that will support them in implementing that plan. This will be achieved by stepping through a planning process, and demonstrating application through scenarios and real-life case studies. Upon completion, attendees will have developed a draft plan of action to build upon once back in the workplace. The course takes place in Perth on 1 June, Melbourne on 15 June, Sydney on 21 June and Brisbane on 28 June. Go to: www.awa.asn.au/Climate_Change_Adaptation_Planning.aspx Managed by
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awa news New Members AWA welcomes the following new members since the most recent issue of Water Journal:
NEW CORPORATE MEMBERS NSW Corporate Silver Odis Pty Ltd Corporate Bronze Sumitomo Australia Pty Ltd
QLD Corporate Silver New Water Corporation Ltd Corporate Bronze Johns Environmental Pty Ltd
VIC Corporate Silver Fcubed Australia P/L – Solar Water Processor
NEW INDIVIDUAL MEMBERS NSW J. Cody, P. Knights, M. Furbock, A. Selwood, B. Barber, C. Dumbrell, G. Collins, S. Dinning, S. Greenaway, S. Gilchrist, T. Matsuo, J. Schrotter, M. Brassey, F. Smith, S. Wanless, V. Kalimugogo, R. McInnes, M. Loconte, I. Tanner, C. Roberts, A. Richardson, F. Holm, N. Berry, R. Carr, D. Ford
NT M. Marshall, R. Randall, M. Thompson, P. Saunders, E. Vervetjes, R. Ram Vengaldas, P. Bourchier, W. Sharp, D. Chin, A. Wright, L. Morgan QLD R. McLeod, O. Benichou, W. Nelson, V. Verakumaran, G. Theo, H. Mohr, K. Gee, K. Goraya, F. Jacobsen, C. Cartlidge, D. Elms, D. Mathers, A. Schultz, A. Kam, B. Wood, J. Allen, P. Eder, P. Porter, P. Donaghy, S. Barnes, S. Edmonds, G. Bellizia, G. Dransfield, G. Watson, H. Mahardhika, C. Wood, A. Massie, B. Sheedy, D. Tunnah, D. West, R. Corbett, R. Naidu, S. Ackaert, S. Alfredson, J. Bailey, J. Evans, M. Griffiths, M. Doherty, P. O’Connor, P. Glenn, A. Appelcryn, B. Lennox, B. Highfield, G. Kolenbet, G. Babington, G. Harsh, C. Haynes, M. Johns, M. Froude, J. Morton, E. Gandashanga, A. Ernst, A. Spinks, A. Schoenmaker, S. Walker, T. Brammer, T. Ferrero, R. Manfield, S. Williams, P. Willey, P. Johnson, C. Barr, B. Nel, P. Hagan, G. Wood SA L. Moran, J. Carne, S. Munakata, J. Kahl, M. Wickramasekera, K. Shishido, E. Moir, S. Dorricott, R. Emblem, K. Falster, J. Rishworth TAS C. Webb, J. Elliott, G. Walters, P. Cullinane VIC N. Clarke, P. Hillis, S. Dickons, S. Eastaugh, S. Evans, S. Bahl, D. Alderton, T. Dunn, M. Clarke, D. Tickner, T. Lohman, N. Jones, K. Price, J. Sunner, S. Muthukumaran, S. Ponnusamy, P. Stephens, J. Bowman, C. Dixon, E. MacKenzie WA J. Suhaib, L. Baddock, P. Green, P. Snowsill, S. Johnson, N. Wende, S. Day, A. Massey, D. Brunton, H. Hanafy, M. Milnes, S. Hadley, P. Bertolucci, J. Barton, C. Gros
OVERSEAS MEMBERS K. Morrison, B. Ball
NEW STUDENT MEMBERS ACT W. Reinhardt NSW S. Fitzgerald SA F. Zheng
YOUNG WATER PROFESSIONALS ACT E. Hampton, K. Alexander, K. Hodges, K. Scott, A. Wilkinson, C. Chak, S. Kelly NSW A. Jeffrey, L. Yapp, M. Villon NT P. Jolly QLD K. Watson, C. Wilson, W. Speirs, S. Vis, J. Rickuss, A. Masci SA E. Plant VIC M. Duke, T. Callingham, M. Kennedy, E. Clark, S. Glenny, S. Coutts, Y. Kim WA A. Tremayne
CONTACT US If you think a new activity would enhance the AWA membership package please contact us on our national local call number 1300 361 426 or submit your suggestion via email to membership@awa.asn.au.
AWA EVENTS CALENDAR This list is correct at the time of printing. Please check the AWA online events calendar for up-to-date listings and booking information at: www.awa.asn.au/events May
Fri, 13 May Tue, 17 May
Wed, 18 May Wed, 25 May Tue, 31 May June Wed, 01 Jun - Thu, 02 Jun Wed, 01 Jun Thu, 02 Jun Tue, 07 Jun Wed, 08 Jun Wed, 15 Jun Thu, 16 Jun Tue, 21 Jun Wed, 22 Jun Wed, 22 Jun Thu, 23 Jun Thu, 23 Jun Tue, 28 Jun July Wed, 06 Jul Thu, 14 Jul Wed, 20 Jul Thu, 21 Jul Fri, 22 Jul Tue, 26 Jul Tue, 26 Jul Wed, 27 Jul August Mon, 01 Aug - Wed, 03 Aug Fri, 05 Aug Wed, 10 Aug Thu, 11 Aug Sun, 14 Aug Tue, 16 Aug Thu, 18 Aug Mon, 22 Aug - Tue, 23 Aug Tue, 23 Aug Wed, 24 Aug Wed, 24 Aug 36 MAY 2011 water
VIC Young Water Professionals Annual Dinner, Melbourne, VIC WA: Disinfection By-Product Workshop – Emerging Issues in DBP Research & the Way Forward, Perth, WA QLD Monthly Technical Meeting – Healthy Waterways, Brisbane, QLD Water Treatment, South Tasmania, TAS WA Seminar – Water Future Forum Half-Day Conference, Perth, WA WIOA Conference, Toowoomba, QLD Sustainability Leadership – How to Facilitate Positive Change, Perth, WA Climate Change Adaptation Planning, Perth, WA VIC Technical Event – Community Engagement, Melbourne, VIC NSW Seminar 2 – ‘Developing Communities and Disaster Relief’, Sydney, NSW Climate Change Adaptation Planning, Melbourne, VIC Sustainability Leadership – How to Facilitate Positive Change, Melbourne, VIC NT Technical Meeting, Darwin, NT Coal Seam Gas – Half-Day Workshop, Melbourne, VIC TasWater 2011, Wrest Point, TAS WA Technical Event, Perth, WA VIC YWP PD Seminar – Climate Change Adaption, Melbourne, VIC ACT Water Matters Annual Conference, Canberra, ACT SA Awards Review Seminar, Adelaide, SA AWA Victorian Branch Presidents’ Dinner, Melbourne, VIC NSW Seminar 3 – Stormwater Harvesting – Perception vs Reality, Sydney, NSW WA YWP Mid Year Mingle, Perth, WA QLD Annual Gala Dinner, Brisbane, QLD TAS Technical Seminar, South Tasmania, TAS ACT Technical Seminar, Canberra , ACT WA Water Industry Lunch, Perth, WA IWA Stabilisation Ponds, Adelaide, SA NSW Heads of Water Gala Dinner, Sydney, NSW Special Event – Water Reform Panel Discussion, Brisbane, QLD 49th Vic Branch Annual Dinner, Melbourne, VIC Water to Wine Gumboot Tour, Canberra, ACT NSW YWP Mentoring Breakfast, Sydney, NSW WA Technical Event, Perth, WA AWA Catchment Management Conference, Melbourne, VIC TAS Technical Seminar, South Tasmania, TAS Queechy Pumping Station, Northern Tasmania, TAS NT Technical Meeting, Darwin, NT
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debate
Water, Water, Everywhere, Nor Any Drop To Drink… So goes the line from the famous poem by Samuel Coleridge, ‘The Rime of the Ancient Mariner’. But times have changed and with today’s technology seawater is emerging as a major potential source of potable water. With its enthusiastic champions and equally passionate opponents, desalination is an issue that incites strong points of view in industry players and the public alike. So is it a sustainable solution for Australian water security? AWA Project Manager – Sustainability, Gregory Priest, sought the opinion of two experts.
In Defence of Desalination Neil Palmer, CEO, National Centre of Excellence in Desalination, Western Australia Neil Palmer has degrees in civil and public health engineering. His career spans 35 years in the Australian water industry – 20 in Government and 15 in the private sector. Neil is the CEO of the Australian National Centre of Excellence in Desalination, a partnership of 13 Australian universities and research organisations seeking to improve desalination performance. Neil is also a Director of the International Desalination Association, a member of the Institution of Engineers Australia and a Life Member of the Australian Water Association (AWA). Email: Neil.Palmer@murdoch.edu.au
Introduction Of the water on Earth, 97% is too salty to drink. Of the fresh water, two-thirds is locked up in ice and glaciers. This means only 1% of the planet’s water is readily available for human use. So why not look to the 97% as a water resource? It is not easy to look out to sea from the Gold Coast or Cottesloe and conclude that either place has a water shortage. The key is desalination. The technology is well proven, affordable and has only a small environmental impact.
Well-Proven Technology There are more than 15,000 desalination plants operating in the world today, delivering 65,000ML/d of fresh water from brackish or seawater resources to 300 million people in 150 countries (GWI 2010, IDA 2010). The installed capacity is growing by around 10% per year. Large scale desalination commenced in the Middle East in the 1950s using distillation technology. Since the 1980s lower energy reverse osmosis desalination has gradually become the dominant technology.
Ninety-seven per cent of the world’s water is seawater.
38 MAY 2011 water
The industry is mature. Having agreed an industrystandard reverse osmosis membrane size in the 1980s, competition between major membrane manufacturers has resulted in better performance and lower prices. There has been a 10-fold reduction in specific energy consumption since 1980 and this trend is likely to continue as new membrane materials, for example those derived from nanotechnology, are developed. Increasing demand for membranes also brings new entrants to the market with significant growth in supply from Asia, further improving performance and reducing price. The Australian Government has also invested $20 million over five years in the National Centre of Excellence in Desalination. One of the centre’s research priorities is to improve energy efficiency of the desalination process. The world population is increasing and with limited alternative water sources, decision makers will look to desalination to fill the gap between increasing demand and limited supply. In Israel, for example, desalinated water currently supplies 20% of drinking water. By 2020, the Israeli Ministry of Health expects this to increase to 50% (WQRA 2011). In Australia, there has been a large investment in desalination technology in all mainland state capitals. This has been driven by drought and the desire to provide a secure and sustainable water supply that is not dependent on rainfall. By 2015, up to 30% of Perth’s water needs, 10% of Brisbane’s, 15% of Melbourne’s, 10% of Sydney’s and 40% of Adelaide’s will be available through desalination.
Affordable Cost The total cost of desalinating seawater, including finance, operations, maintenance, consumables and energy, typically varies from $0.75 to $1.25 per kL (IDA, 2010). Australian desalination plant prices reflect the more expensive cost of construction, attention to minimise environmental impact and, in the case of Perth, purchase of wind energy (at double the cost of coal energy) as an offset for all energy consumed by the plant. The total cost of desalinated water to the Water Corporation from the new Southern Seawater Desalination Plant will be $2.40 per kL (West Australian, 2011). $2.40 for a tonne of water compares favourably with bottled water, which typically sells for $2.40 per bottle, or $4,000 per tonne! By comparison, the total cost of water from a domestic rainwater tank supplying just a fraction of the average household demand would be up to $17 per kL (Marsden Jacob Associates, 2009). The total cost of water from a 3000km pipeline from the Kimberley to Perth would be almost $10 per kL (Water Corporation 2009). While the cost of pumping groundwater from the South West Yarragadee Aquifer may have been less than for desalinated water, the environmental risk of (and community opposition to) drying large and sensitive wetlands in the South West were significant factors in favour of building the Southern Seawater Desalination Plant.
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debate Environmental Impact
Conclusion
Seawater reverse osmosis requires 3.5kWh to make a kilolitre of drinking water (IDA 2010). By comparison, it takes 70kWh/ kL to run a typical domestic hot water service (Kenway, 2008). The energy to provide a household’s typical water needs from seawater desalination is 1.9kWh per day – the equivalent to running a typical 4kW household air conditioner for 25 minutes.
Desalination is not for the short term. These plants are strategic investments to provide a sustainable base load water supply over the next 100 years. This ensures water supply for growth and also insures against drought and climate change. Water gives life: without water, there can be no life. Human activity impacts on our environment, and we manage this impact in order to receive a benefit. The impact of desalination is relatively small and the cost modest, but the benefit (fresh water) is astonishingly large.
Desalination plants use a small proportion of the community’s energy. For example, on 18 January 2010, the temperature in Perth rose to 42˚C and the peak power demand on the SW Electricity System was 3790MW (AAP, 2010). Of this total, the Perth Seawater Desalination Plant took 22MW, or 0.6%.
References Cunard, 2011: Queen Mary 2 Technical.
On 17 February 2011, the cruise ship Queen Mary 2 visited Fremantle. The ship is powered by four diesel engines and two gas turbines totalling 117MW (Cunard 2011). This is about the same amount of power which would be required to supply the whole of Perth (1.5 million people) with desalinated water.
GWI, 2010: DesalData GWI/IDA 23rd Worldwide Desalting Plant Inventory 2010. Water Quality Research Australia, 2011: Desalination decision for Israel, Health Stream, March, p. 4 IDA, 2010: Video – Desalination Myths and Misconceptions, www.idadesal.org
Seawater reverse osmosis desalination produces around 45% fresh water from the feed water. The remaining concentrate is about 1.8 times saltier than normal seawater and, because of the very large volumes, is returned to the sea. The concentrate from the Perth Seawater Desalination Plant in Cockburn Sound is returned through an outfall consisting of 20 diffuser nozzles at 5m spacings. Within 30m of the outfall, the concentrate is diluted 42 times. The impact of the outfall on the marine environment of the Perth plant (which has been operating since 2006) is one of the most observed in the world. The principal concern was that the concentrate would settle on the sea floor and reduce dissolved oxygen, affecting marine life. In 2007, after a 12-month study, the University of WA concluded:
West Australian, 2011: Cost ruled out all Kimberley Plans, Friday April 8, p. 4. AAP 2010: Perth Sizzles, Power Consumption Soars, January 18. University of WA Centre for Water Research, 2007: Summary of Investigations into the Impact of the Perth Seawater Desalination Plant Discharge on Cockburn Sound, August 2007. Marsen Jacob Associates, 2009: The cost effectiveness of residential rainwater tanks in Perth. Kenway SJ et al., 2008: Energy use in the provision and consumption of urban water in Australia and New Zealand. CSIRO: Water for a Healthy Country National Research Flagship. Water Corporation, 2009: Water Forever: Options for our Water Future.
“The effluent from the desalination plant is so highly diluted that it does not have a measurable impact on stratification or dissolved oxygen in the deep basin (>10m) of Cockburn Sound” (UWA 2007).
The Case Against Desalination Jochen Kaempf, Associate Professor, School of the Environment, Flinders University, Adelaide, South Australia
Regular inspections of the outfall pipe indicate healthy growth of marine organisms and sea life attached to, and living around, the pipe and diffusers. Taking into account the much larger scale of tides, wind and waves, the environmental impact of a well-designed and well-constructed seawater desalination plant concentrate return outfall is minimal.
Associate Professor Kaempf completed his PhD in Natural Sciences (Oceanography) in 1996 at the University of Hamburg, Germany. He moved to Australia in late 1999. Since then, he has been working as a researcher and lecturer in the field of Ocean & Climate Sciences at Flinders University in Adelaide. He has been actively involved as independent scientific adviser in the assessment of various Australian desalination projects, namely the Adelaide and Victorian projects and the BHP Billiton proposal. Email: jochen.kaempf@flinders.edu.au
Photo: Water CorPoration
Introduction
Reverse osmosis racks at the Perth Desalination Plant.
The construction of seawater desalination plants in most capital cities of Australia has been prompted by water scarcity in the past 10 years, owing to continued drought conditions and some mismanagement of water resources. Alternative options such as wastewater and stormwater recycling have received comparatively little attention. In this essay, I make the case against seawater desalination by adopting the concept of maladaptation (“mal-” is a Latin prefix meaning “bad”, “evil”, “ill”) to climate-change impacts proposed by Barnett and O’Neill (2010). In addition, I make the plea against a specific Australian seawater desalination project planned for construction in an ecologically particularly valuable marine area.
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debate The Concept of Maladaptation
the future. This reduces the portfolio of adaptation options in the future, and such path-dependent responses may lead to decreased flexibility to respond to unforeseen changes in climatic, environmental, economic and social conditions.
Barnett and O’Neill (2010) defined maladaptation as “action taken ostensibly to avoid or reduce vulnerability to climate change that impacts adversely on, or increases the vulnerability of other systems, sectors or social groups”. They define five distinct types through which maladaptation arises; namely actions that, relative to alternatives: increase emissions of greenhouse gases, disproportionately burden the most vulnerable, have high opportunity costs, reduce incentives to adapt, and set paths that limit the choices available to future generations. Barnett and O’Neill (2010) evaluated these types of maladaptation for the Victorian desalination plant at Wonthaggi.
Environmental Impacts: A Big Economic Risk for Operators Operation license Operation of a desalination plant is subject to an operating licence that specifies environmental performance criteria in accordance with the Environmental Protection (Water Quality) Policy 2003. The nitty-gritty here lies in the details of the operating licence that specifies conditions under which a desalination plant has to be shut down. (Note: the Perth desalination plant at Kwinana was shut down on two occasions in 2008 due to reduced dissolved oxygen levels.) Hence, the choice of an adequate location of outlet and inlet pipes is extremely important, not only for the marine environment, but also for plant operators to avoid interruptions of water production in case of license breaches.
Increased emissions of greenhouse gases The Wonthaggi plant will create about 900,000 tonnes of CO2 equivalent greenhouse gases per year, equivalent to the average energy use of about 120,000 households (assuming each household produces 8 tonnes of CO2 per year). With an average household size of 2–3 persons, this increase in energy demand is equivalent to an extra population of 240,000 to 360,000 people. The increase in energy use for all Australian desalination projects together may correspond to an equivalent virtual population increase exceeding 1 million people (or 5% of the total population). Australian political leaders seem to keep this unpleasant truth of increased rather than decreased energy use a secret. The claim that this extra energy required is (partially) supplied by green energy is without substance, given that this green energy could rather be used to reduce Australia’s carbon footprint.
For desalination-dependent industries, such as the proposed Olympic Dam expansion in South Australia, such interruptions can have dramatic economic consequences.
Adequate choice of location According to international experts, exposed rocky or sandy shorelines with strong currents and surf should be generally preferred over shallow, sheltered sites with little water exchange, and regions of high ecologic value should be avoided (Lattemann and Höpner, 2008). Unfortunately, short-sighted economic cost analyses have led to proposals to build desalination plants in ecologically valuable and sheltered marine regions in Australia.
Disproportionately burdening the most vulnerable Most Australian desalination plants are directly funded as infrastructure upgrades via (substantial) increases in electricity and water prices. Relative to higher income groups, poorer households are socially disadvantaged by these increases. Ironically, the proposed carbon tax, if it is implemented, will hit hardest on energy-intensive industries such as the desalination industry.
The most striking example is the seawater desalination plant proposed by BHP Billiton for Upper Spencer Gulf at Point Lowly in South Australia. This region is a unique ecologic hotspot and accommodates the only known mass spawning aggregation of the iconic and distinctive Giant Australian Cuttlefish. Environmental disasters in this region can have dramatic ecologic and economic consequences. Unfortunately, BHP Billiton has ignored the ecologic value of this region and, instead, has attempted to negotiate exempts from the Environmental Protection (Water Quality) Policy 2003 in their draft Environmental Impact Statement (EIS), in particular that their “zone of ecologic effect” may extend to a distance of 2.5km, which substantially violates the allowed maximum extent of the mixing zone of 100 metres.
High opportunity costs Approaches may be maladaptive if their economic, social or environmental costs are high relative to alternatives. A range of recent studies suggests that a combination of alternative strategies (including increased storage capacity of dams) can deliver large volumes of water and reduce demand at lower cost than desalination (see Barnett and O’Neill, 2010). For unknown reasons, decision makers have largely ignored these strategies.
Path dependency A major issue with large infrastructural developments such as desalination technology is the way they commit capital and institutions to trajectories that are difficult to change in
Conclusion
Photo: Water CorPoration
The conclusion based on the above argumentation is that Australia’s decision to “put most money on one horse”, namely seawater desalination technology, has not been a wise political one. Instead, relative to alternatives, it has already led to enormous economic, social and environmental costs, which are difficult to justify. Construction of a seawater desalination plant in Upper Spencer Gulf is an economically unwise decision by BHP Billiton and a liability for the entire international desalination industry.
Aerial view of Perth’s desalination plant.
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References Barnett J & O’Neill SJ, 2010: Maladaptation. Global Environmental Change, 20, pp.211–213. Lattemann S & Höpner T, 2008: Environmental Impact and impact assessment of seawater desalination. Desalination, 220, pp.1–15.
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Building With Nature Dutch authorities are active in investigation of flood incidents around the world, including the recent floods in Queensland and other significant events such as those occurring in New Orleans and Brazil. A component of this work is to provide the opportunity for other nations to gain insight into some of the lessons learned and the activities undertaken in the Netherlands to mitigate or prevent flooding. AWA’s National Manager Policy, Andrew Speers, was invited to the Netherlands by the Government of the Kingdom of the Netherlands as part of this outreach initiative. The comment was made recently by two Americans visiting the AWA National Office that the average Australian has a remarkably wide knowledge of water issues. When the securing of water supplies is a much-discussed policy priority, when the nation’s poetry is about droughts and flooding rains, when water restrictions and the failure of crops are constant reminders of the scarcity of water, this is probably not surprising. Water is part of the Australian psyche. So, too, with the Dutch – although for different reasons. Twenty-five per cent of Holland is below sea level and a further 25% is subject to flooding. The threat of inundation affects national priorities and the way in which the Dutch define themselves; the history of the Netherlands is, after all, a history of a people’s fight against rising waters. As the Dutch themselves often mention, their Water Boards are among the world’s oldest democratic institutions, being formed some 800 years ago to construct flood prevention devices – generally dykes and levees. Huge investments continue to be made to protect dry land and extend it. There appear to be very few Dutch citizens who can’t provide some valuable information about how the nation deals with water management issues.
Land of Windmills and Dykes The stereotypical view of the Netherlands is a land of windmills and dykes. While the windmills may have given way to electric pumps (many of the windmills were constructed to pump water, not just mill grain), dykes are a feature in the otherwise flat landscape of the country. However, the way in which dykes are viewed is changing and their role as the primary defence against flooding is being reconsidered.
This is true also because new threats are emerging. Unprecedentedly, a recent drought in Holland led to soil drying and cracking, which caused a dyke to slump and become breached. A further threat is to the commercial security of the Netherlands. In his well-known documentary An Inconvenient Truth, former US vice-president, Al Gore showed a map of the way he suggested the Netherlands would look under a future climate change scenario; approximately 70% of the country was inundated. The Dutch Government takes the view that it is important to dispel the idea that the nation is under such threat, lest the international community think that the country is a poor place in which to invest. Accordingly, policy is directed to ensuring that the country will be safe even under the maximum plausible sea level rise (130cms) between now and 2100. One option to maintain the integrity of dykes is to increase their height, and this may be considered in some circumstances. When this is done consideration may also be given to ‘multi-purpose’ approaches, such as including a public transport option, say a subway, embedded within the expanded dyke. Increasingly, however, approaches that seek to take advantage of natural conditions rather than working against them are being considered.
Photo: RijkswateRstaat
This is not to say that existing dykes will be abandoned or substantially modified; without dykes much of the Netherlands would be flooded permanently. However, in the face of rising sea levels – already measured along Holland’s North Sea coast – and changes in the seasonality and peakiness of runoff from neighbouring mountain ranges, it is time to think anew about the approaches that can best be used to protect the country.
Floodwaters being held back by a dyke in Holland.
Slumping of a dyke following a recent, unprecedented period of low rainfall.
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An artist’s impression of a completed ‘Zandmotor’.
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feature article The Dutch defence against flooding is usefully considered in two parts: defence against sea level rise and against coastal storm surges; and defence against flooding from the rivers which flow through the Netherlands.
to replace the sand that is naturally eroding further along the coast for the next 20 years. Initially, 21.5 million tonnes of sand will be used to construct the zandmotor. Its construction will be completed later this year at a cost of €70 million (A$95 million).
Unsurprisingly, some of the solutions developed involve heavy engineering-based defences. To protect against storm surge a program of ‘Delta Works’ has been implemented to protect Port of Rotterdam, the world’s second largest port, and certainly the busiest in Europe. The Delta Works comprises a series of dams and moveable storm surge barriers (see Rotterdam Delta Works, page 45). The works are so massive that the Dutch refer to them as the ‘8th Wonder of the World’.
The zandmotor is a unique project and will be subject to intensive study to determine its environmental impact or benefit; whether the sand erodes along the coast as predicted; and the extent to which it offsets the need to replenish sand artificially in other locations. It is hoped that the zandmotor will also provide habitat – certainly for plants and seabirds, and possibly for seals – and provide recreational opportunities.
However, other approaches have more recently been developed that attempt to utilise more natural processes, or to ‘build with nature’. Holland’s North Sea coast is protected by sand dunes that have been extended artificially over time to provide increased protection. Historically, the extension required the deposition of sand along the coast, which eroded over time and needed to be replaced at least once every five years. More recently, an experiment has begun to develop a ‘zandmotor’ (literally, ‘sand motor’). This involves the creation of an artificial peninsula of approximately 100 hectares, extending from the beach at the western end of the Dutch coast in the shape of a hook, two kilometres long and one kilometre from the beach. This peninsula will provide both wildlife habitat and a recreational area. Like the artificially created berm, the peninsula will erode over time under the influence of wind and waves, but as the current flows east the sand will be transported along the coast, reinforcing the existing dunes. The movement of sand from the peninsula will eliminate the need
Risks from Rivers and Sea Building effective barriers against the sea is essential for the Netherlands; protection from floods from the rivers that run through the country is equally important. Much of Holland and surrounds, and particularly Rotterdam, is situated on a delta formed primarily by the Rhine, Waal, IJssel and lower Meuse Rivers. The catchment area of these rivers encompasses large regions of Germany, Switzerland, France, Belgium and the Netherlands itself. The average discharge rate of the Rhine is 2,200m3/second with a peak average seasonal flow of 12,000m3/s and a maximum currently predicted flow of 16,000m3/second, with a recurrence risk of 1:1,250 years. Currently, the maximum possible discharge rate from the Rhine is 15,000m3/second. Flows above this level would cause significant flooding. There is evidence, however, that under the influence of climate change, the peaks in flow may change. In particular, runoff during the spring melt is likely to become peakier. It may also be that rainfall events become less evenly spread throughout the year.
Floating Houses Houseboats are nothing new. There are 40,000 of them in the Netherlands and anyone who has visited Amsterdam would be familiar with the myriad moorings throughout the canals of the city. However, they are no more than they claim to be – houses on boats. They are practical in many circumstances, but must always float and will require the same maintenance as any other vessel. An alternative approach taken recently in the Netherlands is the construction of ‘floating houses’. Some of these float permanently and in that sense are not substantially different from houseboats, although their design is a level of comfort above the traditional houseboat. However, A floating house at Massbommel, The Netherlands. a number of the dwellings float only during flood conditions, while at other times they rest on foundations built into the banks of an estuary at Massbommel. During peak flow The common service conditions they float on the water, but remain conduit of a floating where constructed, rising and falling as needed house at Massbommel. along several pillars built into their foundations. Utilities such as gas, electricity, water and sewer are provided through a common conduit, which is flexible and also rises and falls with the house. The houses can rise four metres from their base. A similar approach has been taken to the construction of larger public buildings. An experimental exhibition centre has been built adjacent to the centre of Rotterdam. While this does not sit on a permanent foundation, as is the case with the floating houses, it is an example Interior of the Floating Exhibition Centre, Rotterdam. of a major public building designed to rise and fall on floods.
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Photo: Room foR the RiveR
feature article
Photo: Room foR the RiveR
Figure 2: River constriction at Nijmegen before the Room for the River program commenced (left); and artist’s impression of the site in flood after completion of works.
Figure 3: River constriction at Hondsbroekse (left) and in flood after completion of the Room for the River works (the flow control structure is circled). There are clear risks in not taking action to ensure that floods are contained. For these reasons, the Netherland’s Delta Commission is recommending that works be undertaken to manage a peak flood flow of 18,000m3/second by 2050.
Instead a new initiative – Room for the River – has been developed, involving an extensive body of works designed primarily to provide the rivers room to flood and to convey discharges more rapidly. Throughout the delta on which major cities including Rotterdam, Amsterdam and Den Haag (The Hague) are located, a program of 39 works is planned at a cost of €2.5 billion ($A3.4 billion). When completed in 2015, the maximum discharge rate will have been increased to 16,000m3/second. At Nijmegen, in the south-east of the Netherlands, the river is constricted. Dykes contain the flow and constrict the historical floodplain. A bridge has been built downstream which is also an impediment to flow, as the river is channelled beneath the bridge currently. At this site, several initiatives that are characteristic of the Room for the River program are proposed. Figure 2 is an image of the River Waal at Nijmegen as it is currently. The dyke containing the river under flood conditions runs approximately in line with the road that can be seen at the bottom right of the image. Works at this site include relocation of the dyke northward to create additional floodplain and flood storage. The works also include construction of an additional passage under the bridges, removing the significant constriction that exists at these points. During periods of low flow, the land that is available can be used for recreation and for vegetation regeneration and habitat. A similar example of dyke relocation is planned within the same general area. In this case, the relocation will provide an additional channel that can be used either for flood storage or to widen the river to increase its discharge rate depending on the flow predicted (see Figure 3). The flow control structure, circled, can be manually opened or closed to provide for flow or impoundment or both, depending on the number of gates opened. Additionally, the groynes along the river will be removed as these are an impediment to flow during flood conditions.
Raising and strengthening dykes is one option that will be included in the suite of options to be implemented. Such an approach is costly, and also potentially technically difficult and unpopular. The technical difficulties arise from the risk of land subsidence and dyke slumping under certain conditions, which might be exacerbated were dyke levels to be raised and their weight increased. But even if technical challenges can be overcome, people do not always want to live behind barriers. Further, containment of the river itself may have aesthetic, ecological and social impacts as land available to nature is constrained, access to the river becomes more limited and opportunity for riverside recreation is diminished.
Making Room for the River Figure 1 shows the reduction in floodplain that has occurred since 1850, primarily due to river reclamation for urban development and agricultural use. The Netherlands is a densely populated area and urban and agricultural land is at a premium (401 people/km, compared to the European Union overall at 93/km and Australia at 3/km). There is increasing recognition that reclamation of space formerly occupied by the river and its floodplain may be a false economy if a revised assessment of the potential maximum flow means that dykes protecting the low lying area of the country need to be raised and strengthened.
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Photo: Room foR the RiveR
Figure 1: Reduction in available floodplain, 1850–2000.
The flow control structure at Hondsbroekse.
The 39 works sites that make up the Room for the River program include nine different approaches, and of course the approach taken at each site will differ according to the circumstance of each location. Upon completion of the works, there will be a decrease in available agricultural land of 1280 hectares and an increase in ‘natural’ land of 1852 hectares. One-hundred-andfifty houses and 50 farms will also be relocated.
There is insufficient room in this article to detail each of the basic options included in the Room for the River program. However, a selection would include the following (all diagrams are courtesy of the Room for the River program): • Floodplain lowering – or excavation to create a deeper flood channel. The river may break its banks more frequently, but will have a much greater volume on the floodplain to fill when it does.
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Rotterdam Delta Works
In 1953, a storm surge forced sea water up the Nieuwe Waterweg (a manmade extension to the River Scheur), and from there to the River Nieuwe Maas and along a tributary of that river. At that point the impounded water weakened and eventually breached an important dyke, the Groenendijk, resulting in flooding across 150,000 An aerial perspective of the hectares and leading to the deaths of almost 2000 people in Zeeland and South Holland, although the actions by the captain of the ship, de Twee Gebroeders (The Two Brothers) in Maeslant Barrier. wedging his vessel into the breach prevented the flooding from being even more catastrophic.
Photo: Deltawerken
Rotterdam, indeed much of the Netherlands, lies at the end of a series of major and minor rivers, including the Rhine which drains a very large area of Europe. But Rotterdam is a delta city, and while its wealth of waterways has been its lifeblood as a major port, they also threaten it.
Within five years of this event, the Government embarked on the Delta Works program to protect the city and surrounds by installing dams and barriers across the estuaries on which Rotterdam is sited. Most of the works comprise dams that have ‘compartmentalised’ the estuary. In a number of locations these dams have resulted in formerly saline environments becoming fresh. A similar plan was put forward for the Eastern Schelde river, but there was significant community resistance, and resistance by commercial fishermen to the proposal on environmental grounds. Instead a surge barrier consisting of 62 openings, each 40 metres wide, was constructed to enable the free flow of tidal water. The Eastern Schelde storm surge barrier is one of the largest structures on earth.
The Maeslant barrier, showing the view from the ball joint to the barrier.
As impressive as that is, it is the most recent addition to the Delta’s protection that attracts the most attention. This is the Maeslant barrier, one of the largest moving structures on the planet. The barrier was constructed to prevent storm surges travelling up the Nieuwe Waterweg, thereby alleviating the need to raise the level of dykes protecting Rotterdam. The Nieuwe Waterweg is Europe’s most commercially important waterway, with ships passing the barrier every 60 seconds. Thus, the barrier was designed to provide no impediment to the passage of shipping.
The arms of the barrier swing together to close the waterway; the decision to close the barrier is rules-based in response to sea levels and is fully computerised. Twenty-four hours’ notice is given of the need to close the barrier. The two arms of the barrier are kept in dry docks, 210 metres long on each side of the river. The dry docks are flooded to start the process of closing the barrier. Once floating, the arms of the barriers swing together, a process that takes approximately 30 minutes. They are then slowly filled with water, but held for a period above the concrete threshold on which they will ultimately sit. This increases the current under the barrier and washes away any silt that has gathered. The barrier takes approximately two hours to sink fully. The force against the barrier even during a storm is as great as 360 meganewtons. Once closed, the barrier can remain in place for 36 hours, at which point the volume of water retained on the upstream side will have reached the maximum. Because of the importance of the waterway to shipping, the barrier is designed to close only one or two times every 10 years. The full complement of Delta Works protects this part of the Netherlands against a flood of 1:10,000 years.
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feature article • High water channel This involves construction of a dyked area that branches off from the main river to discharge peak flows via an alternative route. • Lowering of groynes Groynes stabilise the location of the river and ensure that the river remains at the correct depth. However, at high water levels groynes can form an obstruction to the flow of water in the river. Lowering the groynes increases the flow rate of water in the river. • Deepening the summer bed The river bed is deepened by excavating the surface layer of the river bed. The deepened river bed provides more room for the river. • Removing obstacles Removing or modifying obstacles in the river bed where possible, or modifying them, increases the flow rate of the water in the river. • Water storage The Volkerak-Zoommeer Lake south of Rotterdam provides for
temporary water storage when exceptional conditions result in the combination of a closed storm surge barrier and high river discharges to the sea.
Valuable Lessons to be Learned The Room for the River program is not an inexpensive initiative. Upon completion it will elevate the maximum discharge rate from the river by approximately seven per cent. If the initiatives prove cost effective, it is proposed that additional measures be implemented to raise the discharge rate to 18000m3/second by 2050. Reports of the cost-effectiveness of the initiatives may provide valuable lessons for the Dutch and for governments of other ‘Delta Cities’ (see Connecting Delta Cities, below). Activities in the Netherlands are not solely about building barriers or creating more room for river flow. Clever spatial planning and land use is also a vital element. For example, building structures, roads and other infrastructure on elevated land or specifically protecting that infrastructure against flooding are important elements, as are multiuse buildings; for example, a carpark now being built in Rotterdam provides both secure parking and flood storage under adjacent parkland. Floating or partially floating structures are also being considered (see Floating Houses, page 43). While all of the approaches taken recently in the Netherlands involve heavy engineering (for example, 20 million cubic metres of soil will be moved as part of the Room for the River initiative), there is an increasing focus on working with nature, rather than against it. There should certainly be important lessons learned from this effort.
Connecting Delta Cities The C40 group of cities is a network of large cities dedicated to tackling climate change. Both Sydney and Melbourne are part of this body. Within the group a related cluster has been established for cities that sit on deltas and which are likely, therefore, to be more prone to the impacts of climate change, particularly sea level rise and increasing peakiness in river flows. This is known as the Connecting Delta Cities initiative. The Connecting Delta Cities goal is: “To develop a network of delta cities that are active in the field of climate-change related spatial development, water management, and adaptation, in order to exchange knowledge on climate adaptation and share best practices that can support cities in developing their adaptation strategies.” According to its website the Connecting Delta Cities network will benefit delta cities through: • Exchange of adaptation strategies and best practices; • Stimulating adaptation practice and enlarging operation capacity; • Supporting the inclusion of climate adaptation in water management and spatial development; • Contributing to the image of delta cities by enhancing their vision of the future; • Raising awareness among citizens and administrations. The current Connecting Delta Cities network includes Rotterdam, Tokyo, Jakarta, Hong Kong, New York, New Orleans, London and Ho Chi Minh City. A number of other cities are potential candidates for membership. Melbourne is considering joining. More information is available at www.rotterdam climateinitiative.nl/nl/delta_cities_website/home or search on ‘Connecting Delta Cities’.
46 MAY 2011 water
City of Rotterdam, host to the Connecting Delta Cities initiative.
feature articles
THINK PIPES. THINK PVC.
Photo by The Wimmera Mail-Times
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feature article
The Future of Urban Water In spite of extensive reform in the water sector over the last few decades, many industry leaders believe more change is needed to secure our water future. The National Water Commission’s recently released report, Urban water in Australia: future directions, identifies the main areas of concern and suggests ways to move forward. James Cameron, CEO of the National Water Commission, outlines the key points of the report.
Photo: NatioNal Water CommissioN/Csiro
The enormously impressive knowledge base developed over the last 15 years (itself a result of the reform process) shows clear progress and subtleties, and shows how the next generation of reforms need to deepen and build on the very successful competition policy-era reforms. – Contributor report (Urban water in Australia: future directions) Australia’s water sector has undergone profound reforms over the past 30 years, to the extent that contemporary businesses bear little resemblance to their precursors. Important changes have seen separation of policy, regulation and service provision, and encouragement of commercial behaviour. Increasingly, the industry is also moving from an asset-focused culture to a customer-service culture. Because of these important achievements, the water sector is much better positioned to manage future challenges. Many reforms, however, have been unevenly applied, leaving unfinished business that constrains the sector’s efficiency, transparency and performance. Pressing challenges now facing the sector include the need to secure supply efficiently in the context of significant uncertainty about inflows to catchments and continuing growth in urban population, while also maintaining effective wastewater services and maximising opportunities for efficient integrated water management solutions without compromising public health and the environment.
The Case for Change The National Water Commission (NWC) considers that the case for further urban water reform has been clearly demonstrated in the way the sector responded to the recent prolonged drought. Arrangements in place in many parts of Australia proved unable to deal effectively – and efficiently – with the climatic shocks that the urban water sector faced over the past decade. As a result, governments intervened to restrict demand and then to boost supplies in a manner that has blurred ongoing accountability for supply security and raised questions about the transparency and cost-effectiveness of investment decisions. This has created lasting uncertainty about roles and responsibilities. To encourage discussion and provide a platform for change, the NWC has released its report Urban water in Australia: future directions. Drawing on contributions from more than 50 Australian and international water management and policy experts, the report aims to catalyse an informed and practical discussion of the national priorities for urban water, leading to a sound and coherent program of action.
Photo: NatioNal Water CommissioN
At the same time, there is increasing pressure to meet customer and community expectations in an effective and efficient manner. The urban water sector also faces a number of cultural and organisational challenges. An ageing workforce means there is a risk of losing knowledge and expertise in managing urban water systems at the very time that the systems are becoming more complex to operate.
Pressures on urban waterways pose a range of challenges.
Customer service and water safety and security are basic issues that need to be addressed.
48 MAY 2011 water
Analysis and recommendations build on the Commission’s 2007 and 2009 biennial assessments, which raised concerns about the performance of the urban water sector (NWC 2007, 2009) and commented that the National Water Initiative (NWI) did not give sufficiently clear guidance on the required direction for urban water reform. More generally, in its work over the past six years, the Commission has encountered divergent views on how well the policy and institutional settings in the urban water sector are performing, whether further reform is necessary, and, if so, the nature of those reforms.
feature articles
Photo: NatioNal Water CommissioN/miChael Bell
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Uncertainty around inflows to catchments and growing populations impact heavily on future planning. In response, the Commission launched the Developing Future Directions for the Australian Urban Water Sector project in mid-2010. The aim was to catalyse an informed and practical discussion of the national priorities for urban water, as the basis for a sound and coherent program of action to ensure we develop a sector that is efficient, adaptive, resilient and customer-driven. The report produced as a result of this work undertakes an extensive status assessment of the current performance of the urban water sector against a proposed set of national objectives. The case for reform is based on evidence of existing shortcomings and opportunities. Key points are: • Further change is needed to institutional and policy settings in the urban water sector to address ongoing inadequacies. • There are opportunities to improve service delivery and focus on customers. The water sector is out of step with other utilities in terms of genuine customer focus.
• How potential trade-offs between equity and efficiency should be addressed (particularly in relation to pricing); • The relative roles and appropriate use of centralised planning (by government) and decentralised decision-making by service providers, the market, or both; • How sustainability is defined and achieved; • How much the urban water industry should be responsible for broader objectives (encapsulated in the term ‘liveable cities’) in urban areas. The NWC considers that the absence of a coherent set of objectives for the sector, which underpins these diverging views, has led to policies that are ineffective and costly, policies that operate at cross-purposes, and confusion between means and ends. This, in turn, undermines accountability and transparency.
• Current regulation of water quality, public health and environmental outcomes is not cost-effective and creates barriers to integrated water management. • Confusion about the role of the urban water sector in delivering liveability outcomes is stalling progress.
Photo: NatioNal Water CommissioN/ColiN Chartres
Objectives for a Successful Australian Urban Water Sector The Commission found that there is a wide range of views on the role and objectives of our urban water sector. Competing perspectives on boundaries and objectives, which were not necessarily based on discipline or location, included: • Whether water conservation is a public policy objective in its own right or a contributor to economically efficient water use; • Whether customer choice is worthwhile and whether it has adverse equity impacts; • How customer service and broader community and environmental outcomes are balanced against the costs of achieving them;
Effects on the environment need to be minimal and well managed.
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feature article Figure 1: A road map to the report, Urban Water in Australia: future directions.
Supply Security
Customer Service
Objectives
Public Health and the Environment
Liveability
Economic Efficiency and Sustainability The urban water sector meets clear and agreed objectives (in the areas above) in a resilient, flexible, efficient, transparent, accountable and customer-focused manner
Characteristics Specific objective
Current performance
Main factors determining current performance
Current and future challenges
Primary recommendations
50 MAY 2011 water
• Meet customers’ needs for secure and reliable supplies, in a sustainable and efficient manner
• Meet customers’ other service needs efficiently
• Manage public health and environmental impacts efficiently and in accordance with community expectations
• Met restricted demand through severe & prolonged drought • Several ‘close calls’ • Very high costs • High level of public debate and reduction in public confidence
• Widespread access to uniform levels of service which are generally high quality • Limited service differentiation • Poor asset condition
• Emerging but limited • Major public health and application of integrated environment risks and solutions (water poor asset condition in sensitive urban design, some areas stormwater, recycling) • Strong resource allocation • Widely divergent framework approaches across • Barriers to recycling water service providers opportunities
• Inadequate planning tools and processes to deal with variability • Institutional roles and responsibilities lack robustness under pressure • Over-reliance on central planning • Unclear objectives, including inadequately defined supply security objectives • Ineffective policies and policy barriers
• Strong institutional framework (e.g. independent economic regulation) but not universally applied • Insufficient transparency • Lack of customer focus and choice in price/ service level trade-offs • Limited competition and incentives for innovation • Competing equity and efficiency objectives
• Regulatory system struggling to implement complex risk-based approaches • Some regulatory obligations lack transparency • Poor pricing practices and insufficient capacity and resources in regional areas • Institutional constraints in non-metro NSW and Queensland
• • • • • • • • • • •
• Contribute to community liveability objectives effectively and efficiently
• Broader liveability objectives not clearly defined • Costs and benefits unclear and hard to assess • Role of water service providers unclear • Coordination is difficult • Gaps in broader urban planning • Inadequate cost-sharing arrangements • Conflicting views on roles and objectives
Rapid population growth and urban development in many areas Extreme climatic variability, impact of climate change on inflows and other climatic events (e.g. bushfires, storms) Increasing and divergent customer needs Potentially major future investment needs in wastewater systems and network infrastructure Increasing labour, capital and energy costs and need to manage high-cost sources Political and community pressure on water price increases Competition from external sources New technology Skills shortage and ageing workforce Greenhouse gas emissions Pressures on urban amenity, urban waterway health, public health
COAG should: • Adopt an agreed set of national objectives for the urban water sector. • Adopt an improved approach to urban water reform implementation. All jurisdictions should: • Define more robust policy frameworks, rather than continual day-to-day involvement. • Amend institutional roles and responsibilities to ensure that accountability under all foreseeable conditions. • Adopt risk-based approaches to supply-demand planning. • Review and change the suite of other policy settings influencing the supply-demand balance to ensure that an efficient portfolio of supply-and-demand side measures to emerges and evolves over time. • Give a greater voice to customers. • Recommit to using pricing to promote economic efficiency. • Work actively towards a goal of more market-determined bulk water prices and other market-oriented options to promote efficiency and innovation. • Undertake reforms in regional, rural and remote areas to ensure that there is sufficient organisational, financial, technical and managerial capacity to meet service delivery requirements and protect public health and the environment, particularly in NSW and Queensland. • Better embed mandatory benefit-cost analysis and community engagement in the regulation of public health and the environment (particularly for investment in wastewater systems). • Improve the sector’s cost-effective contribution to more liveable communities through clearer definition of the roles and responsibilities
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One of the new sedimentation tanks at North Head WWTP in Sydney, which recently underwent $150 improvement works. The Commission therefore recommends the adoption by COAG of an agreed set of national objectives for the urban water sector. A successful Australian urban water sector will, in the Commission’s view, provide secure, safe, healthy and reliable water-related services to urban communities in an economically efficient and sustainable manner. More specifically, the sector should: 1. Understand and meet the long-term interests of all water consumers in the price, quality, safety, reliability and security of supply of fit-for-purpose water and wastewater services through the efficient use of, and investment in, systems, assets and resources. 2. Protect public health and the environment by ensuring that the impacts of the sector’s operations and investments are managed cost-effectively in accordance with society’s expectations and clearly defined obligations. 3. Enhance its effective contribution to more liveable, sustainable and economically prosperous cities in circumstances where broader social, public health and environmental benefits and costs are clearly defined and assessed, or where customers or other parties are willing or explicitly obliged to pay for the outcomes.
• Maximising opportunities to empower customers and deliver better services to meet their needs; • Enabling the sector to contribute to creating liveable cities under clear mandates and with transparent funding; • Refining the mix of market, planning and regulatory settings. While reform requires effort from governments, regulators and water service providers, they will also obtain major benefits: • Governments will have greater confidence and certainty that supply security and other planned outcomes are being achieved and that risks are being managed; • Governments and water businesses will be able to demonstrate performance achievements to customers and the community. Decisions will be made with greater confidence and certainty due to improved information, tools and processes; • The sector as a whole will be more diverse and open to change, and be better prepared to deal with known and unknown risks and future challenges; • Regulators will be able to perform their enforcement roles with greater clarity and confidence;
These three objectives address customer service needs, the management of the impacts of the sector on public health and the environment, and the potential for the sector to play a positive role in shaping the future of urban areas.
• Water businesses will have greater flexibility and incentives to meet customer needs in the most cost-effective manner.
Recommendations
An important lesson from the earlier reform era is that significant change takes time. Given the heightened community and political debate about urban water, there is a need for governments, regulators and water service providers to prioritise and adequately resource a fresh cycle of policy and institutional reform with long-term benefits in mind.
The NWC is convinced there are opportunities to improve urban water outcomes and there is a national interest in doing better. In making our recommendations, the Commission is focused on ensuring the sector is placed to meet future challenges. Figure 1 (opposite page) provides a road map to the report Urban water in Australia: future directions, identifying the key points in the Commission’s analysis. The Commission’s recommendations include: • Creating clarity about the objectives of the urban water sector; • Clearly defining institutional roles, accountabilities and performance measures;
Conclusion
There is no doubt that the industry’s impressive knowledge base provides a foundation for the sector to drive the necessary reforms for the benefit of customers, water service providers, regulators and governments. The future for the urban water sector in Australia is not yet written. Now is the time for safeguarding that future by building a robust, dynamic and flexible sector that focuses on a customer-driven approach.
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feature article
State of the Water Sector: Survey Update In October last year AWA, in partnership with Deloitte, released the Preliminary Report of the State of the Water Sector 2010–2015 Survey. The report included the results of quantitative analysis of the views of the almost 1200 people who responded to questions put to water sector professionals in August–September 2010. The results of this qualitative analysis will be released towards the end of May–early June as a single report with the results of the Preliminary Report.
The survey produced some interesting and, sometimes, unexpected results. For example, sustainability was seen as the most important issue facing the water sector, but one of the least well addressed. Unforeseen results included the majority view that capital expenditure will remain at current levels or increase in real terms over the next 3–5 years – surprising in the light of the very high levels of expenditure that have occurred in order to diversify urban supplies in the face of drought – and that economic regulation of the industry is not as effective as health, environmental and corporate regulation. Respondents also had strong views about the effectiveness of vertical disaggregation of utilities and the extent to which the sector is investing appropriately in infrastructure upgrades.
These state-based reports will be released at OzWater’11 on 9 May and will cover: Queensland; New South Wales and the ACT; Victoria and Tasmania; South Australia and the Northern Territory; and Western Australia. The state-based reports will be available in electronic format and will be free to download from the AWA website (www.awa.asn.au) or from the Deloitte website at (www.deloitte.com.au)
To explore these issues further, AWA and Deloitte have been conducting interviews with water sector leaders. These discussions provide the opportunity to understand better what might be driving particular views, whether the general view is one shared by sector leaders and how the views expressed might be interpreted.
It is also possible to dissect the reports by a range of demographic criteria (regional/urban; level of seniority/ employer/profession etc) and further analyses can be generated on request. Researchers are invited to contact Andrew Speers, AWA’s National Manager – Policy, to discuss any additional data requirements. Email: aspeers@awa.asn.au or call (02) 9467 8426.
In the meantime, there is the opportunity to analyse the data on a state-by-state basis, which will provide some insight into the differing views held in each jurisdiction. It will be interesting to know, for example, whether there is stronger or weaker support for a disaggregated industry in Queensland than there is nationally, or whether economic regulation is considered more or less effective in states with a less mature regulatory environment than in states with more established regulators that have proved their independence.
The survey identified sustainability, capital expenditure, urban supply and investment in infrastructure as key issues to be addressed.
52 MAY 2011 water
feature articles
conference reviews National Water Education, Water Efficiency and Water Industry Capacity Development Conferences: 1-3 March 2011 Reported by E A (Bob) Swinton, C Cheeseman and F Mackenzie AWA combined three national conferences after the success of this format in 2008. Some 220 delegates heard from two common keynote speakers, then streams focusing on each of the conference specialties of Water Education, Water Efficiency and Water Industry Capacity Development (WICD) ran concurrently.
Lead Keynote Speakers Linda Macpherson: Destigmatising the water cycle Vice President and Reuse Principal of CH2MHill, Linda was involved in the design of the Visitor Centre in Singapore which has been highly successful in educating and, indeed, enthralling, the Singapore population, young and old, about potable reuse, branded as NEWater. Her message was simple… “destigmatise the water cycle... change the mindset from ‘used’ to ‘reusable’, and concentrate on images – they are more powerful than words. As we well know, cartoonists thrive on lavatory humour and are gleefully employed by opponents of reuse, in whatever form, and journalists themselves do not have a proper understanding of the water cycle, but they thrive on conflict. Opponents of reuse thrive on fear: they can use powerful words and the politicians react since the majority are merely barometers of public opinion, as reported by the media, and there are very few who are prepared to lead, except in situations of emergency.” The Water Research Foundation Report (07/03), which will be available soon, reported that the water industry’s own vocabulary inhibits understanding. In 2009 they conducted a questionnaire containing 33 questions, in five cities, including Perth, exploring the public’s understanding of and reactions to the water cycle. It found that the adjective ‘potable’ was not understood by a fair percentage of people, but the common word ‘drinking’ was well understood. One cohort was treated to information sessions, using Jenifer Simpson’s booklet, From waste-d water to pure water, with its simple vocabulary and star-rated system, and it became obvious that acceptance of reuse was vastly improved, to the extent that Direct Potable Reuse (DPR) was judged safer than Indirect Potable Reuse (IPR). It was also found that the source of the water ranked low (23%), and technology (84%) and monitoring (60%) were the highest rankings, followed by residual disinfection at 45%. In dealing with the public and the media, Linda said we must avoid jargon, acronyms and stigma. Words such as ‘sewage’, ‘wastewater’, even ‘treated wastewater’ have negative images and should not be used. The emphasis should be on ‘purity’. We must showcase the technology of purification. Singapore may have led, but Australia is already on the way, in Gippsland, Victoria, Perth in WA and St Marys in NSW. There are currently seven reuse projects worldwide, and they can learn from each other. The ultimate aim is to engender trust, that living systems continuously purify water – and so can we – and that properly purified water is the safest water.
54 MAY 2011 water
With the younger generation so involved with Twitter, Facebook, YouTube and i-Phone apps, there are new opportunities to inform, educate and stimulate. Question-time raised some interesting points. Colin Nash remarked that in the bottled water market safety was a ‘given’, but taste was a marketing driver and could be applied to reuse. Peter Robinson asked if the survey had shown any difference between rural and urban perceptions. Linda said that was not assessed, but in irrigation areas and urban third pipe gardens signs such as “Recycled Water: Do Not Drink” tended to put such water into the same box as nuclear radiation. A discussion on ‘point-of-use’ filters brought out the fact that purveyors of such devices used inflammatory language even about municipal tap water, but in general purchasers were more concerned about taste than safety. Nonetheless, membrane filters at the kitchen tap might be a useful tool to alleviate the anxiety of a section of the public.
Chris Davis: Putting together the pieces Retired CEO of AWA, and now a member of the National Water Commission, Chris presented a keynote address entitled “Putting Together the Pieces”. He fully applauded Linda’s address on reuse, but he intended to address the wider issues facing the water industry. The concluding words of his Abstract are: “It is illuminating to see just how interconnected the three topics (of this conference) are. If we are to deliver on a goal of safe, reliable and affordable water systems, sustainably delivered to Australia’s urban communities, then we need … to work with the links between efficiency, community understanding and an effective human resource for water.” Considering, first, community perceptions about the water industry, he insisted that though people may be vague about semantics, they are not ignorant and focus groups are a lot more astute than we estimate. It is patronising to think that we can just ‘pour in information’ and that will solve the situation. It is a great pity that SEQ’s plan to put highly purified water into the Wivenhoe Dam has been put on the back-burner by a combination of the break in the drought and political anxiety. It would have been a front runner, even though it would have been IPR, not DPR. But the politicians read the media every morning and, as Linda remarked, the media thrive on conflict. To add to the media reactions, reuse is so bedevilled by regulatory hangups that the overall impression to the public is very negative. Addressing recruitment to the industry, Chris made the point that community perceptions about the water industry are just as significant in influencing students, whether secondary or tertiary. In 2006, AWA advocated for a Questacon water display in Canberra, but it took until 2010 for it to be installed. The spark of excitement may well affect a child’s decisions later in their career. Public recognition is needed. Indeed, a TV sitcom focusing on engineers rather than doctors, lawyers and police would be very useful, he suggested. Instilling pride in one’s chosen career is vital, and the water industry’s collegiate rather than competitive nature has certainly retained both professional and trade staff in the water industry far longer than in many other industries – but it has to be backed up by proper remuneration for new recruitment. Regarding water efficiency (or demand management), he wondered whether our outstanding performance during drought
conference reviews would survive now that it is raining and the dams are filling. Yet climate predictions are ominous. We are faced with more aridity, punctuated by extreme rainfall events, which, as in Queensland, overflow the dams and so are ‘wasted’. The situation in Perth is worse than ever. The Water Efficiency Labelling Scheme (WELS) is still underdone. There is no mandatory level and the facility for cheating is ever-present. The Smart Approved Watermark is working well in its field. BASIX in NSW is a good concept, but frequently obeyed in the letter, not the action. For example, a survey has shown that a number of rainwater tanks installed to attain the points are, in fact, never used. The impacts of efficient appliances may last; individual behaviour may shift, yet a culture of water savings has been instilled. Can it be sustained? Not just for the next drought, but solely because efficiency is far cheaper and has a lesser carbon footprint than developing new water sources (such as desalination or reuse). Smart meters, where usage costs are fed back immediately to the customer, may be worth further development, but to be economic the current price would have to be reduced to less than a quarter by mass production. Three-block electricity metering certainly works. One success which will be maintained is the encouragement of water efficiency in industry and commercial premises, Chris concluded. It makes better economic sense to the accountants as well as meaning better sustainability.
Water Efficiency Conference Keynote Speakers The theme of reducing domestic usage was continued by Tony Kelly, Managing Director of Yarra Valley Water, Melbourne, looking at Past, Present, Future. The Past: “Seven years of drought have taught us much, with 2006 being the lowest rainfall on record for Melbourne’s catchments, which necessitated the North-South pipeline and the desalination plant. Currently rainfall is reasonable, but future prospects are not optimistic, so a major challenge for the water utilities is no longer civil engineering but social engineering, to maintain low consumption patterns. “Throughout the drought the trigger levels, which Melbourne Water established in the earlier years, have focused the community. Dam levels have been widely advertised (even taxi drivers could quote them) and Stage 1 to 3 restrictions were accepted. Yarra Valley’s Smart Water Account won us an international award, but more importantly, it kicked teenagers out of the shower. “Rebates on appliances and rainwater systems were offered; some were valuable, others less so, but together they helped to change perceptions. Our TV advertisements were aimed at inspiring people, and by keeping people ‘in the loop’ we achieved a 36% reduction in domestic demand, and a 33% reduction in commercial demand, all voluntary. Yarra Valley Water spent about $0.5m; the direct benefit was about $2.5m, but far more if carbon pricing could be factored in.
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MAY 2011 55
conference reviews “What didn’t work? Easing restrictions too early only confused the public. Our water rates were too complex and provided little incentive for single occupants (old and young). We were slow to penalise the cowboys – and public shaming might be more effective than mere fines. Appliance standards need to be mandatory. Some industries have been put out of business, but alternative jobs have grown.” The Present: “The fixed component of pricing is too high; it dilutes the water-saving component. The public is confused by continuation of water saving while it is raining, and there is nostalgia for the past… for example, kids playing under the sprinklers. So can we assume that the public will still co-operate? Yet even though restrictions are a blunt instrument, they have less impact on the public than the price rises which would otherwise be necessary to finance new sources, many years ahead of actual demand.” The Future: “Even though it has been a wet spring, Melbourne’s Thompson Reservoir is only 31% of capacity, run-off is 10% less than long-term average, and future rainfall is uncertain. Population growth is a concern, but unlike Nature it is slow and steady and we can plan for it. We cannot turn behaviour on/off but we should be able to offer choices. But overall, the campaigns are saving 60GL/a, compared to the design yield of 150GL/a for the expensive desalination plant.” Regarding the saving accomplished by working with industry, the same result was achieved by Sydney Water. Mohan Seneviratne summarised the “Every Drop Counts” campaign which he supervised. He said that 10 years ago there was as little understanding of the water cycle in industry as in the domestic sector. We have come a long way since then, but there were lessons learned along the way and he listed a score card of achievements to date (see Table 1).
Table 1: Balance score card. Initiative
Damien Giurco speaking on “Banking on Savings”. There are currently many challenges which this and similar efficiency programs face. • As a result of the recent rain (in the eastern states) there is a perception that we can return to ‘normal’. • Because of the financial crisis there is no cheap money for new investment. • Desalination plants may be considered a remedy for all ills. • Cuts in State funding (new Governments) • Cuts in utility funding. But he warned there will be increases in water prices. Goldman Sachs has identified water scarcity as one of the top five risks for the 21st century, so security of water supply is more significant for industry than cost saving. Even though the true cost of water and its discharge may be five times its purchase price, an AIG survey has shown that out of total sales, electricity accounts for 0.5%, gas 0.2% and water only 0.15% of expenses.
Status
Details
Water conservation strategy
+
Portfolio of products. Some have resource efficiency targets
Water saving plans – mandatory/voluntary
?
Water saving action plans, water maps, WEMPs – do they achieve the objective?
Funds, grants and rebates
+
Some are more active than others
Market segmentation and savings potential
+
Water audits of high water users
?
In progress or stopped doing them
Water diagnostics
?
Some elements
Small business programs
+
Pre-rinse spray valve, waterless wok stove, laundries, councils
Best practice guidelines
?
Not for all sectors
Access to third parties for recycling
?
In some states
Internal reuse
+
Good case studies available
Capacity development
+
Well-developed service providers market
Permanent water restrictions
+
On-line monitoring of high water users
+
Schools monitoring program
+
56 MAY 2011 water
Some utilities
Yet there is value in continuing the program … doing more with less by creative thinking. We are far behind Japan which boasts an average of 60% reuse for the major industries. Mohan said we should be careful to identify the true drivers for industry. Evaluation of any project should be based on levelised cost, not payback time or NPV alone. We should harness the energy/water nexus (every drop means a watt). We should focus on the industries (eg. food processing) which could yield the biggest bang for the buck, and focus on in-house reuse rather than end-of-pipe reuse. “Water Pinch” models identify the best re-use opportunity. Rather than offering subsidies or rebates, he suggests accelerated tax deductability. It is a better tool since owners take the risk of failure, and Governments can never understand the complexities of the true drivers in any particular industry. Finally, resource recovery will be increasingly significant, particularly for phosphorus, which will be increasingly critical.
Conference Streams There was a significant difference between the papers presented at this conference compared to previous water efficiency conferences. In previous years papers described technological systems for saving water. In this conference there were none of these. Nearly all
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conference reviews the papers focused on demand management systems, either outlining the programs, reporting the results or analysing the patterns of water usage. The ‘social engineering’ mentioned by Tony Kelly was very much in evidence.
From Queensland, Dana Hallett (United Utilities) and Sue Larsen (DERM) discussed their successful demand management programs, and Sue, in a second paper, the research into, for example, the best ways for local councils to frame their water bills.
In Sydney, Kate Beatty reported the results of differentiating indoor usage from outdoor usage by focusing on the sewage flows on carefully selected low demand days. The results clearly demonstrated the effects of various levels of restrictions. Overall, savings of 36 LPD were achieved outdoors, but at the same time, 30 LCD was achieved indoors, even though restrictions did not apply to indoor usage.
Anthony Coates (Local Government Infrastructure Services) reported on the Government’s ClimateSmart Home Service, which provides not only showerhead and light-bulb exchange but also advice by the visiting electrician, using a customerinteractive tool, for better energy and water efficiency.
This was backed up by Yue-cong Wang, who utilised Kate’s data then performed very detailed econometric analyses involving household size and lot sizes to estimate the savings from better appliances. Corinna Doolan applied smart metering to a 600-household development. Tony Cartwright had a different focus, analysing peak demands to assist reticulation design. Melbourne’s contributions were Julian Shortt’s report of the Early Performance Contract System’s application to the large number of facilities operated by the City Council, and Michael Quilliam estimated the effectiveness of the Target 155 campaign by applying climate corrections. Ballarat has been faced with extreme water shortages and CHW had applied very severe restrictions. However, the company has now employed Don Perugini (Intelligent Software) and Damien Giurco (UTS) to model future scenarios now that the drought has broken.
John Brennan, Water Corporation, reported on that organisation’s similar Social Marketing approach, the difference being that the consultant continues coaching the household for at least six months, with 21% savings achieved in their second trial. Cilla deLacy discussed the problems and successes when sprinkler bans were imposed on the Perth suburbanites, and in contrast Nerida Beard of NT Power and Water spoke on the problems, and opportunities, for engaging the locals in better management of water in their 72 remote indigenous communities. There were papers reporting on demand management programs in gardens, hotels, pubs, aquatic centres, high-rise apartment and commercial buildings, all of value. Finally, Julian Fyffe, UTS, compared the real-world performances of demand management systems to the estimated engineering yields and found a significant drop-off with time. Accounting for double-accounting, free-ridership and stock modeling can bring projections much closer to actuality.
CAll for PAPERS Submissions open May 30, 2011 Submissions close September 1, 2011 Presented by
A u s t r A l i A’ s n At i o n A l WAt e r C o n f e r e n C e A n d e x h i b i t i o n
See www.ozwater.org for details
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conference reviews Water Education Conference Summary The Water Education Conference went beyond your typical conference format (paper presentations and questions from the audience). AWA’s Water Education Network Committee seized the opportunity to tap into the needs of participants as a means to guide its action plan for the next two years. To do this a series of participatory workshop sessions were run over the course of the program. These sessions followed the theme Challenges and Solutions for Future Water Education in Australia. The first session provided background on AWA and the Water Education Specialist Network (known as WEN) and, importantly, started the audience thinking about the challenges facing their area of work – water education. Perhaps surprisingly, or not so surprisingly given the audience educators, in this first session many participants contributed challenges freely. These were documented and taken forward into the workshop session which followed the next day.
Keynote Speakers The keynote speakers for the education conference provided great insight into their respective areas of expertise. Andre Taylor of Andre Taylor Consulting focused on leadership in the water sector and its contribution to achieving sustainability. Andre provided details on leadership theory and development
and opportunities for leadership in the water sector. Andre described the role water educators have to play in: • Maintaining an awareness of leadership development (LD) as one tool to drive change in the water sector; • Identifying opportunities and facilitating high quality leadership development initiatives; • Participating in leadership development initiatives as ‘developing leaders’. Jessica Dart of Clear Horizon spoke on moving beyond data collection and reporting to ‘Learning-Based Evaluation’, which focuses strongly on collecting data to help teams adaptively manage their programs and navigate complexity. Jessica provided a framework and tools which can be applied successfully to evaluate education programs.
Conference Streams To continue on the theme Challenges and Solutions for Future Water Education in Australia, keynote speakers Andre and Jessica joined a panel with Roy Hallam (Water Corporation, WA), Don Alcock (Water Secure, Qld) and Linda Macpherson (CH2MHill). The audience was invited to pose “challenges” to the panel so that advice on “solutions” could be put forward. With insights from the panel fresh in the minds of participants, these challenges were taken forward into a workshop style (modified world café) session where participants had the
Table 2: Workshop Outcomes – Challenges and Solutions for Future Water Education in Australia. Challenges
Solutions (through the Water Education Network)
How do we create better networking opportunities?
Create a WEN Skills Directory made up of expertise/talents across hot topics Collate sample business cases pertaining to certain issues Collate sample case studies across hot topics Collate sample evaluation techniques What is being developed/done across Australia
How do we collaborate better?
Identify key stakeholders – who’s who state by state Identify and build partnership opportunities Define and create strategic linkages
How do we capitalise and link to global and international initiatives?
Identify key stakeholders – who’s who Define and create strategic linkages Identify and build partnership opportunities thorough programs such as international prizes (SJWP), sister school programs, global programs such as World Water Monitoring Day, etc
How do we use technology to deliver water education and messages?
Update resources for new platforms Adopt new technologies How to use technology in water education? Professional development for water educators in relevant new technology platforms being used in schools, etc
How do we improve the leadership skills in water educators so they contribute at a higher level to the sector?
Build case by investigating links between business and community and education Share success stories in leadership Develop case studies – how-to examples Template development to share ideas Capture who has done what
How do we manage online tools for water education resources better?
Create a simple database of what is available Australia-wide collection Ensure present databases are up to date Include resource rating system
How do we make evaluation more meaningful to our stakeholders?
What is being done in the area of evaluation? Develop expert panel Develop case studies and best practice
How do we raise the status of water education?
Identify experts Develop leadership skills in educators Link to education to strategic plans Publish in newsletters, journals etc
58 MAY 2011 water
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conference reviews opportunity to explore each of the challenges and work on solutions. The output from this session is shown in Table 2. The Water Education Network Committee is utilising the information in this table in the development of its action plan which it will deliver in 2011–2012. The papers submitted via an open call for papers, and delivered during the water education conference streams, showcased a number of well established programs such as Water Corporation’s Waterwise Schools Program and newer initiatives such as SA Water’s very comprehensive suite of programs delivered through its relatively new Education Centre in Adelaide. The presentations on programs included demonstrations of a variety of tools and models now used in water education. Evaluation now seems to be core to the delivery of education programs in water, which was not necessarily the case a decade ago. Likewise, best practice in behaviour change programs has come a long way. There has also been a continuation, in recent years, of the use of engaging techniques such as theatre and the arts to deliver key messages and learning about water. As a result of increasing diversity of water supply and treatment (such as desalination, recycling etc) it is becoming more common for water businesses to invest in water ‘interpretive centres’ where school groups and the community can go to learn and see water technology in progress. These centres are strongly linked to the businesses’ water education activities, but the design of interpretive centres is a specialised skill and conference participants identified the need to bring such people into the water education community so this expertise can be shared. On the final day of the conference a specific workshop to uncover the opportunities that the Australian Curriculum provides the water sector was led by members of the Water Education Network, Roy Hallam (Water Corporation) and Jenny Fisher (Sydney Water). This workshop was designed to look at the opportunity for a collaborative approach nationally to ensure that water education is utilised within the Australian Curriculum Framework. The major outcome of the Curriculum Workshop was a commitment to the development of a specific project, under the auspices of AWA, which will see a strategic approach by
The Australian Curriculum Workshop. the sector in engaging with the Australian Curriculum. A reference group is currently being formed to develop a business plan for the project. A funding model will then be confirmed before industry support is sought. If your organisation is interested in this project, please send an email to AWA’s Project Manager – School and Community Education, Fleur Johnson at fjohnson@awa.asn.au.
Water Industry Capacity Development (WICD) Conference Human resource management is a strategic priority across many industries and countries and the Australian water sector is no exception. The National Water Skills Strategy and Business Plan completed last year encapsulated skills challenges, recognised current activities and proposed new projects. In addition to these and the focus/efforts/activities of WICD, there are numerous other networks and programs which demonstrate and emphasise the need for us to effectively lead and collaborate for optimal outcomes for the water sector. The WICD Conference included: • Eight themes: Human Resources, Culture Change, Training Initiatives, State Skill Projects, International Learnings, and workshops on National Strategies, Maximising Technology and Employee Health and Welfare;
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MAY 2011 59
conference reviews • 15 WICD presenters, six workshop presentations and two WICD keynotes; • The WICD Conference Committee: Nicole Latham, Melbourne Water (Chair), Alison Nolan, South East Water and Darryl Hancock, MidCoast Water.
Summary The conference included a range of diverse themes, from Culture Change to Employee Welfare, and attracted interested delegates from across the breadth of organisations in the water skills arena. The opening keynote by Philip Bullock, Chair, Skills Australia, highlighted national workforce trends and the belief that the industry must take responsibility to develop innovative solutions to skills issues. Rohan Anderson, Manager, Industry Engagement, Energy Skills Queensland, provided a contrasting industry perspective about broad skills management in a rapidly evolving sector. Both keynotes highlighted the importance of industry innovation and champions to meet their organisation and sector’s skill needs.
WICD Conference: Employee Health and Welfare Workshop. • Must increase the number of RTOs; • Get private sector support; • All organisations need to invest in capacity development – benchmarking; • Need organisations to have workforce planning;
This challenge was adopted by the WICD stream presenters, who shared their ideas and contributions to their enterprises and regions. In the three workshops on National Strategies, Maximising Technology and Employee Health and Welfare, delegates took advantage of the opportunity to discuss critical concerns.
• Get school interest, build traineeship and apprenticeship programs;
There was consensus on a number of items, with some of the most significant ones including:
• Take into account the regional, small organisation perspective;
• The desire for national strategy and collaboration while accounting for different regions’ needs;
• H2Oz is good for awareness and attraction, school focus;
• Better linkages to schools and regulatory bodies; • That work is required to address operator training; • The importance of ongoing and continual improvement of employee welfare policies; • And a shared and combined system to share tools and resources. The feedback and contacts from the conference will be utilised to direct and contribute to WICD and AWA activities. For example, AWA intends to work more closely with schools utilising AWA’s recent recruit Fleur Johnson, Project Manager – School and Community Education, and as part of the H2Oz careers in water campaign; AWA has meanwhile developed and distributed school career posters. In addition, an operator training project scoping document is underway and a WICD sub-committee is proposed to pool resources and focus on emerging technologies. It was promising to see the strong capability and interest from all stakeholders. This provides support for cohesive and national skill activities such as the National Water Skills Business Plan and the WICD network itself. Overall the WICD Conference was a resounding success and we look forward to convening skills stakeholders again for the biennial workshop next year.
National Strategies Workshop Tamara Shinners, Government Skills Australia and Fiona Mackenzie from AWA presented updates on current and planned projects. Discussion and feedback ensued. Key discussion points • Diverse issues, but needs national co-ordination;
60 MAY 2011 water
• Quality of RTOs is questionable, need an industry approval process to be set up; • Strategic co-ordination, not only on training but all HR aspects;
• Share the good news and ideas;
• Engagement with regulatory agencies; • Reduce duplication of projects. The National Water Skills Business Plan is the first to capture, build and share skill project information; • Approach should take into account state and regional versus metropolitan differences; • General interest in national collaboration; • Help kids to get into entry level programs; • Drive the national perspective; • More engagement with regulators. Agreed items • Discussion prioritised operator training issues; • Consideration of regional and state differences and needs; • Better engagement with regulatory agencies; • Promote careers at a school level and offer entry level programs; • National strategy and collaboration is important.
Employee Health and Welfare Workshop Jenny Legge from JobFit Systems presented on assessments that comply with the five principles of pre-employment functional assessments: safety, reliability, validity, practicality and utility. Melbourne Water’s Martin Bowles presented on data collected and their innovative ‘No harm’ policy and welfare scheme.
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conference reviews Darryl Hancock from Midcoast Water stated the importance and consequences of not looking after employees. He stressed the importance of physical and mental health and that the onus should be on the manager to look after the welfare of the team.
integrated performance management system and shared their implementation experience; and Rob Fearon, CEO at qldwater directorate, who mentioned the e-learning project and then opened the discussion about technology more broadly.
• The impetus to improve employee health and welfare is poor safety performance;
Desirable systems
• Building safety culture first and then incorporating other welfare elements;
• Online lawyer templates and standards, LGSA are using this. Cost is approximately $2000/year; • Workers Compensation Management Tool which includes prompts for action;
• Possible link to the WSAA OHS group’s activities. Agreed items Organisations need to focus on staff welfare in three ways:
• National and centrally hosted information on Australian Drinking Water Guidelines and regulations; • Industry induction online including Occupational Health and Safety;
• Wellbeing is concerned with both the physical and psychological health of employees; • Employee welfare is everyone’s responsibility and managers especially need to observe and manage their team’s needs; • Safety assessments are encouraged to be on a regular basis rather than just an initial activity and taking into consideration the ageing workforce.
Maximising Technology Workshop Workshop attendees were asked to provide technological systems they utilised, implemented recently or were planning to invest in, and the primary function they served. This was followed by active discussion about potential IT collaboration opportunities. Presenters included Pam Erving and Connie Brakoulias from South East Water, who showcased their new
• Online directory of resources that can be viewed and shared across the industry; • Online training such as e-learning requiring delivery and partnering with RTOs; • Integrate new online systems to sit within one larger and consistent shared area. Action items • If there’s enough interest in the concept, a small WICD technology sub-committee could be formed to focus on this topic. The sub-committee could coordinate the industry (urban, rural, contractors and RTOs) through researching desirable systems and co-funding the development of software.
NCED Biofouling Workshop 23 – 24 June 2011 Mercure Sydney Hotel The National Centre of Excellence in Desalination is holding its second Biofouling workshop on 23-24 June 2011 in Sydney. This workshop will give you the opportunity to learn about leading global biofouling research and industry developments. The workshop will include participants from large Australian municipal desalination plants discussing the biofouling problems they have faced and mitigated. For further information and to register visit: http://desalination.edu.au
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large sample size.
This paper presents a methodmanagement for estimating the method for refereed estimating the paper demand indoor and outdoor water use of residential water use of residential properties using econometric models. ometric models. Indoor and nctions were constructed Household demand is defined as a function of the ations from metered data. number of people in the dwelling (household size) applied to track indoor and and lot size (square metres) as the proxy of ng drought restrictions. It garden size. This function is fitted using quarterly have chosen to use Tracking water savings using customer metered data, the propertymetered lot size and household ter indoors even though data outdoor and econometric models size data collected through Sydney Water’s nly targeted use. demand management programs. as also applied to estimate YC Wang ney Water’s Such data collection exercises are often Before constructing the indoor AbstractWaterFix and expensive and impractical for a reasonably and outdoor demand functions, it ebate programs. OBSERVATIONS FROM CONSUMPTION DATA This paper presents Savings a method for large sample size. is worth noting how water use in a the indoor and outdoor pproach estimating are consistent with residential house varies with lot size This paper presents a method for water use of residential properties using and household size and over time. the participant and control estimating the indoor and outdoor econometric models. Indoor and outdoor It is well known that the water use of a residential water use of residential properties demand functions were constructed Figure 1 shows the monthly d. house comprises indoor and outdoor components. using econometric models. based on the observations from metered consumption of all residential houses data. The method has been applied (about 1 million) plotted with five lot The water usesize bands. depends mainly on Householdindoor demand is defi ned as to track indoor and outdoor savings The overall reduction in a function of the number of people in during drought restrictions. It shows that household size and efficiency devices demand overof timewater is mainly due to the dwelling (household size) and lot people have chosen to use significantly drought restrictions introduced from size (square metres) as the proxy of within a house. The outdoor water use depends less water indoors even though drought November 2002 (Voluntary restrictions garden size. This function is fitted using restrictions only targeted outdoor use. from November 2002; Mandatory Level on garden size, type, ownership of a quarterly metered data, the propertyplant lot se ‘endTheuse’ modelling to same method was also applied to 1 restrictions from October 2003; Level 2 size and household size data collected swimming pool and/or rainwater tanks. savings from Sydney for waterestimate andtheestimate the Water’s through from June 2004; Level 3 from June 2005; Sydney Water’s demand WaterFix and washing machine rebate replaced by Water Wise Rules from July management programs. efficiencyprograms. (WE)Savings programs estimated on using 2009); water use efficiency improvement A key challenge in modelling indoor andand outdoor approach are consistent with (for example, showerheads washing model, thisindoor residential Observations from those identified using the participant machines) and potable water substitution water useData is that there is no separate metering of Consumption om individual end uses such and control group matching method. (for example, rainwater tanks); and It the is well known the waterdemands. use of a two that water A single behaviour change. meter serves shing, clothes washing etc. Introduction residential house comprises indoor and mostcomponents. residential properties whileprofound a common meter Another feature revealed outdoor Indoor water use h indoorMany endwater use isuseusually utilities “end use” from this diagram is that the demand depends mainly on household size and serves most blocks of units. to forecast thewater demand for y data. modelling For example increases with the increase of the lot the efficiency of water devices within a water and estimate the likely impact of size during both drought restrictions house. Outdoor water use depends on s a function the water effiof ciency (WE) type programsof on water periods. garden size, plant type, ownership of a use. In this model, indoor residential Before constructing theand pre-restrictions indoor and outdoor ber of showers per person swimming pool and/or rainwater tanks. consumption is built from individual end Sydney Water has implemented one demand functions, it is worth noting how water average uses duration of toilet each such as showering, flushing, of the most comprehensive demand A key challenge in modelling indoor clothes washing etc. The water use of in the world and and outdoor use is that there is use in water a residential housemanagement varies programs with lot size consumption is usually each indoor end use is usually estimated (SWC 2010a). Since 2001, over half no separate metering of the two water household size and over time. survey data. For example, water a million residential dwellings have demands. A single meter serves most over, i.e.using the total metered use from showering is a function of residential properties, while a common participated in at least one demand mated indoor the typeuse. of showerhead, the number meter serves most blocks of units. management program. For the residential
SEPARATING INDOOR AND OUTDOOR WATER CONSUMPTION
Consumption (L/hh/d)
<=200 m2 201-400 m2 401-600 m2 601-800 m2 >800 m2
1,000
800
600
Ju
n01 D ec -0 1 Ju n02 D ec -0 2 Ju n03 D ec -0 3 Ju n04 D ec -0 4 Ju n05 D ec -0 5 Ju n06 D ec -0 6
400 ec -0 0
is very well constructed r, it is very data intensive. applied models are usually The end use model is very well constructed conceptually. However, data poor”. In order to it is very data intensive. As a consequence, the it is normally required to applied models are usually “assumption rich and data poor”. In order to calibrate ses or meter at a very short the model, it is normally required to meter an 1 minute) together individual end uses or meterwith at a very short time their interval (less than 1 minute), together diary of water use. with customers keeping a diary of their es have water been carried out in have use. Several end use studies been carried out in Australia (Loh and ghlan, 2003; Roberts, 2005; Coghlan, 2003; Roberts, 2006; Willis et al., 2009); and overseas (Mayer and and DeOreo, and overseas (Mayer 1999; Mayer et al., 2004; Heinrich, 2007). er et al., 2004; Heinrich, ection exercises are often
1,200
D
of showers per person per year and the average duration of each shower. Outdoor consumption is usually calculated as the leftover – i.e. the total metered consumption less estimated indoor use.
Figure 1: Variation of consumption with lot size.
Figure 1: Variation of consumption with lot size water
MAY 2011 63
02
80 0
80 0
02
06
06 most ams most alf a ams n at alfthe a ner’s at the er’s
Average Consumption (kL/Yr) Average Consumption (kL/Yr)
Frequency Frequency
005 5 50 0 50 0 -1 -1 10 0010 00 001 1 15 5015 50 002 20 20 020 00 0 025 2 -25 25 0 5 0 003 3 30 0030 00 0 035 3 -35 35 0 5 0 004 4 40 0040 00 004 4 45 5045 50 0 050 5 -50 50 0 0 0 005 5 55 5055 50 006 6 60 0060 00 0 065 6 -65 65 0 5 0 007 7 70 0070 00 007 7 75 5075 50 0080 80 0 0 >8 >8 00 00
Frequency Frequency
005 5 50 0 50 0 -1 -1 10 00 10 00 001 1 15 50 15 50 0 020 2 -20 20 0 0 0 002 2 25 50 25 50 0 030 3 -30 30 0 0 0 003 3 35 50 35 50 004 4 40 00 40 00 0 045 4 -45 45 0 5 0 005 5 50 00 50 00 005 5 55 50 55 50 006 6 60 00 60 00 0 065 6 -65 65 0 5 0 007 7 70 00 70 00 007 7 75 50 75 50 0080 80 0 0 >8 >8 00 00
Average Consumption (kL/Yr) Average Consumption (kL/Yr)
80 0
80 0
this the this ught the ght
expected. The variation of the annual consumption in each household sizeofgroup can beconsumption attributed toinmany The variation the annual each causes, such as group different responding household size canbehaviours, be attributed to many refereed paper to weather conditions differently, different efficient causes, such as different behaviours, responding devices in individual properties, etc. In this study, to weather conditions differently, different efficient we are only focused on estimating the average devices in individual properties, etc. In this study, houses participating in Sydney Water’s WaterFix program With this in annual each group. we areconsumption only focusedforon estimating the average (to installmind, a new efficient showerhead,annual a toilet cistern flush the average consumption wasin annual flush consumption for each group. With this arrestor plotted for single against toilets and tap flow regulators), the lot size for different household mind,collected the household average annual consumption was Sydney Water size information from size groups as shown in Figures 4 and 5. The plotted the the lot frequency size for distributions different household customers. Figuresagainst 2 and 3 show same data was also plotted against household of consumption for various sizes during 2001–2002 size groups ashousehold shown in Figures 4 and 5. The size for different lot size groups in Figures 6 and and 2005–2006, same respectively. data was also plotted against household 7. size different lot size groups in group Figures 6 and Although the for annual consumption for each property
WaterFix program (to install a new efficient 40% WaterFix program installflush a new efficient showerhead, a toilet(tocistern arrestor for 35% showerhead, a toilet cistern flush arrestor for 40% 1 Person single flush toilets and tap flow regulators), 2 Persons single flush toilets and tap flow regulators), 30% 35% Sydney Water collected household size 31 Persons Person 42 Persons Sydney Water collectedFigures household size Persons 25% information from customers. 2 and 3 show 30% 53 Persons Persons information from customers. Figures 2 and 3 show 64 Persons the20% for Persons 25%frequency distributions of consumption 5 Persons the frequency distributions of consumption for various household sizes during 2001-02 and 15% 6 Persons 20% various household sizes during 2001-02 and 2005-06, respectively. Although the annual 10% 15% 2005-06, respectively. Although the annual consumption for each property group ranges from 5% 10% consumption for800 each group ranges from 0 to more than kL,property the frequency distribution ranges from 7. 0kL to more than 800kL, the frequency distribution 0 to0% 800askL, frequency distribution 5%more curve shiftsthan to right thethe number of people in the curve shifts450 to the right as the number of people in the house curve to right as themeans numberthat of people in the increases. This means that the more people in the house, the house increases. This the more 0% shifts 400 house This the means more higher the average 450 people increases. in the house, higherthat the the average annual consumption and its variability. Consumption (kL/Yr) people in the house, higher the average Comparing350 400 Figure 2 to Figure 3, the drought restrictions cause annual consumption and the its variability. Comparing 300 distribution curves to move left and squash the annual consumption and itsannual variability. Comparing the frequency 350 Figure Variation consumption Figure 2 to2:Figure 3, of the drought restrictions Consumption (kL/Yr) 250 overall variabilities as expected. Figure 2 to Figure 3, the drought restrictions cause the frequency distribution curves to move distribution with household size during 2001-02 300 Figure 2:Figure Variation annual consumption distribution 2:of Variation of annual consumption 200 cause the frequency distribution curves to move left household and squash overall variabilities as with size during the 2001–2002. The variation 250 of the annual consumption in each household distribution with household size during 2001-02 left and squash the overall variabilities as size group 150 can expected. 200 be attributed to many causes, such as different behaviours,100 responding to weather conditions differently, expected. 150 40% 1 Person 2 Persons 3 Persons different efficient devices in individual properties, etc. In this 50 The variation of the annual consumption in each 6 Persons 4 Persons 5 Persons 100 35% 1 Person study, we are0 only focused on estimating the average annual 40% 1 Person 2 Persons 3 Persons household sizeofgroup can beconsumption attributed to many The variation the annual in each 2 Persons consumption50for With 500 this in mind, average 30% 100 each 200 group. 300 4 400 600 700 the 800 900 1,000 1,100 1,200 Persons 5 Persons 6 Persons 35% 31 Persons causes, such asgroup different responding household size canbehaviours, be attributed to many annual consumption Person 0 2 was plotted against the lot size for different 42 Persons Lot Size (m ) 25% Persons to weather conditions differently, different efficient 30% causes, such as different behaviours, responding 200 as300 400 in500 600 4 700 800The900 1,000 1,100 1,200 household size100 groups shown Figures and 5. same 53 Persons Persons 20% 2 devices in individual properties, etc. In this study, 6 Persons to weather conditions differently, different efficient Figure 4. Consumption against lot size data was also plotted against household lot during 4 Persons Lot size Sizefor (mdifferent ) 25% 5 Persons we15% are only focused on estimating the average size groups in Figures 6 and 7. devices in individual properties, etc. In this study, 2001-02 20% 6 Persons Figure 4. Consumption against lot size during annual consumption foroneach group. With this in we are only focused estimating the average 10% These figures demonstrate that consumption 15% 2001-02 increase is mind, the average for annual wasin annual consumption each consumption group. With this almost proportional to the household size regardless of the 5% 450 10% plotted against the lot size for different household mind, the average annual consumption was lot size. Consumption increases steeply from <=200m2 lot 400 0% 5%groups as shown in Figures 4 and 5. The 2 450 size to 301m –400m2 lot size cluster, then flattens out plotted against the lot size for different household size cluster350 400 (Figures 4 and 5). Drought restrictions not only reduced the same data was also plotted against household 0% size groups as shown in Figures 4 and 5. The 300 overall consumption of each property group, but also reduced size for different lot size groups in Figures 6 and 350 same data was also plotted against household 250 consumption, as the slope of curves in Figure Consumption (kL/Yr) the per person 7. 300 size 3: forVariation differentannual lot size groupsdistribution in Figures Figure consumption with6 and 200 6 is steeper than those in Figure 7. This means that indoor Figure 3:ofVariation of annual consumption 250 Consumption (kL/Yr) 7. household size during 2005–2006. consumption was also reduced during drought restrictions. 150 distribution with household size during 2005-06 200 450 Figure 3: Variation of annual consumption 100 150 400 1 Person 2 Persons 3 Persons distribution with household size during 2005-06 Formulation 450 50 Sydney Water has implemented one of the most Persons 5 Persons 6 Persons 100 we attempt 4 350 In this section, to construct a model which can 400 0 1 Person 2 Persons 3 Persons comprehensive demand management programs 300 50100 characteristics of demand in a700 residential house 200 300 4 Persons 400 500 600 1,000 1,100 1,200 Sydney Water has implemented one of the most reproduce the 5 Persons 800 900 6 Persons in350 the world (SWC 2010a). Since 2001, over half a displayed in the last section. Regarding the right 2function for 250 0 comprehensive demand management programs 300 Lot Size (m ) million residential dwellings have participated in at indoor consumption for each cluster, outdoor 100 200 300 lot 400size 500 600 the 700 average 800 900 1,000 1,100 1,200 200 in250 the world (SWC 2010a). Since 2001, over half a consumption 2 can be assumed to be a constant value. Figure 5: Consumption against lot size during least one demand management program. For the 150 Lot Size (m ) 200 million residential dwellings have participated in at 2005-06 2 2 residential houses participating in Sydney Water’s For example, choosing the 401m -600m lot size cluster in 100 150 Figure 5: Consumption against lot size during least one demand program. For the 1 Person management 2 Persons 3 Persons 50 Figure 7, the average consumption for various household sizes 4 Persons 5 Persons 6 Persons 100 2005-06 residential houses participating in Sydney Water’s was subtracted by a constant outdoor consumption, say 30, 0 Average Consumption (kL/Yr) Average Consumption (kL/Yr)
rom om rom om1 1 rom om 005; 05; July July (eg (eg and and ater ater
demand management restrictions and pre-restrictions periods.
50
100
200
1 Person 300 4 Persons 400 500
0
2 Persons 600 700 800 5 Persons
3 Persons 900 1,000 1,100 1,200 6 Persons
2
100
200
300
400
Lot Size (m )
500
600
700
800
900 1,000 1,100 1,200
2 Figure 4. Consumption against Lot Size (m ) lot size during 2001-02 Figure 4: Consumption against lot size during 2001–2002. Figure 4. Consumption against lot size during 2001-02
Average Consumption (kL/Yr) Average Consumption (kL/Yr)
all all with with in in
diagram that the feature demand revealed increasesfrom with this the Another isprofound increase of the lot size during both drought diagram is that the demand increases with the restrictions pre-restrictions periods. increase ofand the lot size during both drought
and then plotted as diamond points in Figure 8. Trying different functions such as linear, logarithmic, polynomial, power, etc to fit through the data points, only the power function will give the best fit as shown by the black line in Figure 8. The same can be applied to other lot size clusters. Therefore, the indoor consumption can be expressed as
450
400 450 350 400 300 350 250 300 200 250 150 200 100 150 50 100 0
50 100
where a, k and
α
Q Indoor = a+kH α
(1)
are constants. H is the household size.
Table 1: Parameters from regression. Lot Size (m2) 1 Person 4 Persons 200
300
1 Person 400 500 4 Persons
0
2 Persons 5 Persons
3 Persons 6 Persons
2 Persons 600 700 800 5 Persons 2
3 Persons 900 1,000 1,100 1,200 6 Persons
Lot Size (m )
100 200 300 400 500 600 700 800 900 1,000 1,100 Figure 5: Consumption against lot against size duringlot2005–2006. Figure 5: Consumption size during
1,200
Avg Lot Size (m2)
Qi (kL/Yr)
<=200
151.99
-1.99
201-400
303.65
19.18
401-600
531.00
29.95
680.19
34.85
1,113.34
52.10
601-800 >800
K (kL/Yr)
a
75.95
0.736
2
Lot Size (m ) 2005-06 Figure 5: Consumption against lot size during 2005-06
64 MAY 2011 water
technical features
(2)
where Qi is the combination of the outdoor consumption for lot size cluster i and the constant a in Equation (1). Applying Equation (2) as an auto-regression equation for the data set in Figure 7 and adjusting α value to maximise the R2 value, the parameters obtained are listed in Table 1 (opposite). The Qi values in the table are plotted against the average lot size as shown by the blue diamond points in Figure 9. Applying a similar process used for selecting the indoor demand function, the logarithmic function is found to have the best fit.
Average Consumption (kL/Yr)
These figures demonstrate that consumption Although the Qi values include theto constant a , which is less increase is almost proportional the household than –1.99 (because outdoor consumption for lot size less than size regardless of the lot size. Consumption 200m2 has to be greater than or equal to zero), the outdoor 2 increases steeply from <=200m lot size cluster to demand 2 function should be a logarithmic function as 301-400m lot size cluster, then flattens out = restrictions b+cln(L) not only (3) (Figures 4 and 5). QDrought Outdoor reduced the overall consumption where b and c are constants. L is the of lot each size of aproperty house. Finally group, but also reduced the per person the total consumption of a residential house can be expressed as consumption, as the slope of curves in Figure 6 is α Q = a+b+cln(L)+kH steeper than those in Figure 7. This means that (4) indoor Unfortunately consumption during a and was b valuesalso cannotreduced be solved independently for cross-sectional drought restrictions. data due to multi-colinearity. So a + b will be solved as a single parameter. However, they can be solved separately when Equation (4) includes seasonality and weather 500 conditions. This will be discussed further in the next section. <=200 m2 201-400 m2 401-600 m2 400 Applications 601-800 m2 and >800 m2 350 Track indoor 450
outdoor savings over time
The first application is to run the regression model (Equation (4)) on the WaterFix properties for each financial year from 2001– 250 2002 to 2008–2009. For each financial year, property samples 200 were chosen to satisfy the following conditions: 300
150
• Participating in WaterFix program only
100 50
• Owner occupied 1• Not
2 during the 3 modelling 4 period5 sold Household Size • No swimming pool
6
7
Figure 6: Consumption against household size • Not a Department of Housing (DoH) property during 2001-02
Average Consumption (kL/Yr)
• The property exists for whole year 500
• No check meters and/or related properties connecting to it.
450
201-400 m2parameter values and indoor and outdoor The estimated savings401-600 due tom2 drought restrictions over time are shown in Table 601-800 m2 2 (overleaf). A constant α value of 0.72 was applied. Sensitivity >800 m2 analysis with a range of a values from 0.68 to 0.78 shows little effect on R2 value and final results.
400 350 300 250 200 150 100 50
>=200 m2
The indoor and outdoor savings were estimated as the difference in consumption between year 2001–2002 and the year estimated based on a typical house with a family of three people and a lot size of 500m2. The key assumption made is that a remains constant over time, so it would disappear in the saving estimation. For example, the indoor savings for year 2002–2003 1 2 3 4 5 6 7 can be calculated using Equation (5a) and (5b) (overleaf). Household Size
Figure 7: Consumption against household size during 2005-06
200 100 150 50 100
1
2
3
4
5
6
7
1 2 3 4 5 6 size 7 Figure 6: Consumption against household Household Size during 2001-02 Figure 6: Consumption against household size during 2001–2002. Figure 6: Consumption against household size during 2001-02 power function will give the best fit as shown by 500 >=200 m2 the in Figure 8. The same can be 450 black line 201-400 m2 401-600 m2 applied to other lot size clusters. Therefore, the 500 400 601-800 >=200 m2 m2 indoor consumption can be expressed as 450 >800 m2m2 350 201-400
400 300 350 250
401-600 m2 601-800 m2 >800 m2
QIndoor = a + kH α
45 35
40 30
35 25
30 20
25 15
20 10
155
10
5
F
Fi For out con For out con
wh
250 where a , k and α are constants. H is the 150 200 household size. Normally, the more the people in 100 15050 house the less the per person consumption, the 3 6 7 α 2is less than or 4equal to5 1. therefore, 100 1
Household Size
Figure 7: Consumption against household sizehousehold during 2005–2006. Figure 7:2Consumption against size 7 1 3 4 5 6
during 2005-06 Household Size Figure 7: Consumption against household size 450 FORMULATION 401-600 m2 during 2005-06 400 500
350
FORMULATION In300this section, we are trying to construct a model, which can reproduce the characteristics of 250 in a we residential house displayed in the 0.7439 Indemand this section, are trying to construct a model, 200 y = 75.274x last section. Now let’s look at what is the right 2 which can reproduce the characteristics R = 0.9996 of 150 function for indoor consumption. For each lot demand in a residential house displayed in size the 100 cluster, the outdoor consumption be last50 section. average Now let’s look at what is thecan right assumed to be a constant value. For example, function for indoor consumption. For each lot size 2 0 lot size cluster in choosing the 401 to 600mconsumption cluster, the average outdoor 1 2 3 4 5 6can be7 Figure 7, the average consumption for various assumed to be a constant value. For example, Household 2 Size by a constant householdthesizes was subtracted lot size cluster size. in choosing 401 to 600m Figure 8: Relation between indoor consumption and household Figure7,8: Relation between consumption outdoor consumption, say 30,indoor and then as Figure the average consumption forplotted various 60 and sizeTrying diamond points inhousehold Figure 8. different household sizes was subtracted by a constant functions such as linear, logarithmic, polynomial, outdoor consumption, say 30, and then plotted as 50 power etclot to size fit through theit data points, different only For each is that the the diamond points incluster, Figure 8. assumed Trying outdoor consumption is constant, so the total 40 functions such as linear, logarithmic, polynomial, y = 25.946Ln(x) - 131.72 consumption be expressed power etc to can fit through the dataaspoints, only the 2 R = 0.9883
30 20
45
50 40
(1)
300 200
50
50
Household Size
50
Average Consumption (kL/Yr) Average Consumption (kL/Yr)
Q = Q i +kH α
300 200 250 150
Average Consumption (kL/Yr)
For each lot size cluster, it is assumed that the outdoor consumption is constant, so the total consumption can be expressed as
<=200 m2 201-400 m2 401-600 m2 <=200 m2 m2 601-800 201-400 >800 m2m2 401-600 m2 601-800 m2 >800 m2
450 500 400 450 350 400 300 350 250
Consumption (kL/Yr)
Normally, the more the people in the house, the less the per-person consumption, therefore, α is less than or equal to 1.
Average Consumption (kL/Yr) Average Consumption (kL/Yr)
demand management
refereed paper
whe the hou the the the Average Consumption (kL/Yr)(kL/Yr) Average Consumption
group, also in reduced person steeper but than those Figure 7.theThisper means that consumption, as the slope of curves in Figure 6 is indoor consumption was also reduced during steeper those in Figure 7. This means that droughtthan restrictions. indoor consumption was also reduced during drought restrictions. 500
Q = Qi + kH
α
(2)
con whe a aut con 7 aa the aut 7a the
Lo ( <=2 Lot 201 ( 401 <=2 601 201 >80 401 601 The >80 aga dia The pro aga fun diam The the pro outd fun time the 0.72 of α 2 R v
Tab
10
where 0
Qi is the combination of the outdoor
consumption for lot size cluster i and the constant a -10in Equation (1). Applying Equation (2) as an 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 auto-regression equation for the data set in Figure 2 Lot Size (m ) 2 α value to maximise thelotRsize.value, 7 and adjusting Figure 9: Relation between outdoor consumption and 9: Relation between theFigure parameters obtained areoutdoor listed inconsumption Table 1. and lot size water
MAY 2011 65
Table 1: Parameters from regression
Although the Qi values include the constant a , which is less than –1.99 (because outdoor
Yea
01-0 02-0 03-0 04-0 05-0 06-0 07-0
tion
02-03 SIndoor = (a+kH α)01-02 – (a+kHα)02-03
Table 2: Model parameters and saving estimates. a+b
Year
c
Indoor Savings (kL/Yr)
k
Outdoor Savings (kL/Yr)
08-09 500
400 450
21.2
75.0
26.9
29.5
1 Person
2 Persons
3 Persons
4 Persons 1 Person
5 Persons 2 Persons
6 Persons 3 Persons
4 Persons
5 Persons
6 Persons
94,414
S
02-03 Indoor
R2
0.98
350 400 300 350 250 300 200 250 150 200 100 150
= (kH )
α 01-02
– (kHα)02-03
(5b)
Drought restrictions only targeted water use, the but function of household size. outdoor For simplicity, significant indoor savings were achieved overpaper. the [about] six-year same power coefficient is used in this function of household size. the restrictions period. By the end of the For Levelsimplicity, 3 drought restrictions, same power coefficient is used in this paper. the indoor savings reached 26.9 kL/hh/Yr a typical The regression equation (6) isforrun on house the with aprocessed family of three people, consumption or 24.6 LPD. The results are same consistent monthly data. The Thetheregression equation (6)project is run how on the with from theprocess research sampleoutcomes preparation used into in the people first processed monthly consumption data. The same2010b). reduced their water use during drought restrictions (SWC application is also applied here, but in this sample preparation used in the was first In this research project, theprocess dry weather sewer application, properties participating ininflow WaterFixused application is indoor also consumption applied here, but in this as a proxy of the 2011). and/or washing machine rebate (Beatty, are also included.
application, properties participating in WaterFix InOutdoor order savings to solve the regression those very much depend are onequation, weather conditions. and/or washing machine rebate also included. properties that have not participated yet but will Negative indicate outdoorequation, water use in 2002– In ordersavings to solve the higher regression those participate in WaterFix and/or washing machine 2003 than in 2001–2002, voluntaryyet restrictions properties that have even not under participated but willfor rebate programs need to be included. seven months. is later mainlyalso due to the relatively hotter and drier participate inThis WaterFix and/or washing machine These properties serve as a control group, sosavings the conditions in 2002–2003. the higher rebate programs laterSimilarly, also need to beoutdoor included. in indoor consumption before participating in the 2006–2007 and 2007–2008 to relatively wetter These properties serve are as due a control group, so weather the water efficiency program can be estimated in these years. indoor consumption before participating in the through the same regression equation. water program can be estimated Figuresefficiency 10 and 11 show the comparison of the predicted through the same regression equation. and consumption 2001–2002 (pre-restrictions) Themetered daily savings overfortime for a typical family of and 2005-–2006 (Level 3 drought restrictions), respectively. 3 people are estimated and shown in Figure 12. In The daily savings timethe formetered a typical family of lines these figures, the dotsover represent data and the 3 people are estimated and shown in Figure 12. indicate the model predictions. Clearly the model predictions 80
200
300
400
500
600
700
800
900
1,000 1,100 1,200
500
Consumption (kL/Yr) Consumption (kL/Yr)
1 Personis also 2 Personsapplied 3 Persons here, but in this application 450 500 4 Persons 5 Persons 6 Persons application, properties participating in WaterFix 1 Person 2 Persons 3 Persons 400 450 and/or washing machine rebate are also included. 4 Persons 5 Persons 6 Persons 350order to solve the regression equation, those In400 properties that have not participated yet but will 300 350 participate in WaterFix and/or washing machine 250 300 rebate programs later also need to be included. 200 250 These properties serve as a control group, so the 150 indoor consumption before participating in the 200 water efficiency program can be estimated 100 150 through the same regression equation. 50 100
100
200
300
400
500
600
700
800
900 1,000 1,100 1,200
50 daily savings over time for The Lot Size (m2) a typical family of 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 3Figure people are estimated shown in Figure 12. Figure 11: 11: Comparison of predicated consumption with metered 2 Comparison ofand predicated consumption
Lot Size (m )
data during with 2005–2006. metered data during 2005-06
Figure 11: Comparison of predicated consumption 80 with metered data during 2005-06 70 Estimate savings from WE programs 60
Estimate savings from WE programs 50 second application is to use the model to The 40 estimate the savings from the water efficiency The second application is to use the model to (WE) programs. In this study, only the WaterFix 30 estimate the savings from the water efficiency and washing machine rebate programs are 20 (WE) programs. In thisWaterFix study, only the WaterFix included and the equation (4) Machine can beRebate expanded as 10 and washing machineWashing rebate programs are included and the equation (4) can be expanded as 0 Q = a + b + c ln( L) + kH α + rH + wH α (6)
Q = a + b + c ln( L) + kH α + rH + wH α (6)
Figure 12:rDaily WaterFixfactors and washing machine where andsavings w are from the saving for WaterFix Figure 12: Daily savings from WaterFix and rebate programs. and washing machine rebate programs,
where r washing and w aremachine the saving factors for WaterFix rebate programs respectively. WaterFix savings are mainly from rebate programs, the new efficient showerhead and usually a linear respectively. WaterFix savings are mainly from The variation of savings function of household size. reflects Savings the from underlying a new the new efficient showerhead and usually a linear efficient improvement of the control agroup efficient washing machine is normally powerand
66 2011 watermachine andMAYwashing
80
60 Estimate savings from WE programs 70
Savings (L/d) (L/d) Savings
100
Figure 10: ComparisonLot of Size predicated consumption (m2) The regression equation (6)2001-02 is run on the with metered data during Figure 10: Comparison of predicated consumption with metered Figure 10: Comparison of predicateddata. consumption processed monthly consumption The same data duringwith 2001–2002. metered data during 2001-02 sample preparation process used in the first
compare well with the metered consumption. 70 50
The60second application is to use the model to estimate the 40 50 savings from the water efficiency (WE) programs. In this study, 30 only 40 the WaterFix and washing machine rebate programs are 20 included and the Equation WaterFix (4) can be expanded as 30 10 20 0 10
Washing Machine Rebate WaterFix α
Q = a+b+cln(L)+ kH + rH + wHα Washing Machine Rebate
(6)
where 0 r and w are the saving factors for WaterFix and washing machine rebate programs, respectively. WaterFix savings are Figure 12:new Daily savings from WaterFix anda linear mainly from the efficient showerhead and usually machine rebate programs function ofwashing household size. Savings from a new efficient washing Figure 12: Daily savings from WaterFix and machine are normally a power function of household size. For washing machine rebate programs The variation ofpower savings reflects the inunderlying simplicity, the same coefficient is used this paper. Ju l- 0 2 Ja n03 Ju l- 0 3 Ja n04 Ju l- 0 4 Ja n05 Ju l- 0 5 Ja n06 Ju l- 0 6 Ja n07 Ju l- 0 7 Ja n08 Ju l- 0 8 Ja n09 Ju l- 0 9
50
100 function of 300 household size. For900simplicity, the 100 200 400 500 600 700 800 1,000 1,100 1,200 2 in this paper. 50 same power coefficient is used Lot Size (m )
Ju l- 0 2 Ja n03 Ju l- 0 3 Ja n04 Ju l- 0 4 Ja n05 Ju l- 0 5 Ja n06 Ju l- 0 6 Ja n07 Ju l- 0 7 Ja n08 Ju l- 0 8 Ja n09 Ju l- 0 9
Consumption (kL/Yr) Consumption (kL/Yr)
450 500
-105.9
(5a)
or Sample Size
Figures 10 and 11 show the comparison44,095 of the0.98 01-02 -274.9 52.8 87.2 predicted and metered consumption for 2001-02 Figures 10 and show the of the 02-03 -340.1 64.811 84.5 6.0 comparison -10.2 3 52,049 (pre-restrictions) and 2005-06 (Level drought0.98 predicted and metered consumption for 2001-02 03-04 -182.1 respectively. 34.7 82.5 10.5 20.7figures, 53,272 restrictions), In these the0.97 (pre-restrictions) and 2005-06 (Level 3 drought dots the 78.4 metered and the lines 0.97 04-05 represent -141.9 26.9 19.4 data 29.6 55,352 restrictions), respectively. In these figures, the indicate the model 78.5 predictions. Clearly the66,852 model 05-06 represent -151.0 28.5 19.2data 28.6 dots the metered and the lines 0.99 predictions compare well with the metered indicate the model model 0.94 06-07 -145.0 26.6 predictions. 78.3 19.7 Clearly 34.7 the79,277 consumption. predictions compare well with the metered 07-08 -94.8 18.4 75.2 26.5 35.8 92,293 0.94 consumption.
Savings (L/d)
00 1,200
refereed paper
Ju l- 0 2 Ja n03 Ju l- 0 3 Ja n04 Ju l- 0 4 Ja n05 Ju l- 0 5 Ja n06 Ju l- 0 6 Ja n07 Ju l- 0 7 Ja n08 Ju l- 0 8 Ja n09 Ju l- 0 9
the 1-02 ught the nes odel ered
demand management
efficient improvement of the control group and The variation regression Equation (6) is reflects run on thethe processed monthly The of savings underlying change in the number of participants and controls consumption data. The same preparation process efficient improvement ofsample the control group andas over time. In this analysis, the control groups are used in theinfirst is also applied here, in this change theapplication number of participants andbut controls those properties that have not participated in application, participating WaterFix and/or are washing over time. properties In this analysis, theincontrol groups WaterFix and/or washing machine rebate program machine rebate programs also included. In order to solve those properties thatarehave not participated in the yet but will become participants later. The WaterFix and/or washing machine rebate program annualised savings are listed in Table 3. Tablebut 3: Annual from participants WaterFix and washing yet will savings become later. machine The rebate programs. annualised savings are listed in Table 3. Table 3: Annual savings from WaterFix and Savings rebate programs Savings washing machine Table 3: AnnualWaterFix savings from WaterFix Year Washingand Machine washing machine (kL/Yr) rebate programs (kL/Yr) Savings Savings 02-03 16.79 WaterFix Washing Machine Year Savings Savings (kL/Yr) (kL/Yr) 03-04 18.14 19.95 WaterFix Washing Machine Year 02-03 16.79 04-05 19.19 20.06 (kL/Yr) (kL/Yr) 03-04 18.14 19.95 05-06 21.44 19.64 02-03 16.79 04-05 19.19 20.06 03-04 18.14 19.95 06-07 21.58 24.84 05-06 21.44 19.64 04-05 19.19 20.06 07-08 17.51 18.84 06-07 21.58 24.84 05-06 21.44 19.64 08-09 16.40 12.62 07-08 17.51 18.84 06-07 21.58 24.84 08-09 16.40 12.62 Average 18.72 19.32 07-08 17.51 18.84 18.72 19.32 Average 08-09 16.40 12.62 18.72technical 19.32 Average features The savings from the WaterFix program ranged from 16.4 to 21.58 kL/hh/Yr with the long term The savings from the WaterFix program ranged average of 18.7 kL/hh/Yr. This is consistent with
demand management
refereed paper
regression equation, those properties that have not participated yet but which will participate in WaterFix and/ or washing machine rebate programs later also need to be included. These properties serve as a control group, so the indoor consumption before participating in the water efficiency program can be estimated through the same regression equation. The daily savings over time for a typical family of three people are estimated and shown in Figure 12. The variation of savings reflects the underlying efficient improvement of the control group and change in the number of participants and controls over time. In this analysis, the control groups are those properties that have not participated in WaterFix and/or washing machine rebate programs yet but will become participants later. The annualised savings are listed in Table 3.
a constant value into, or subtracting a constant value from, the indoor and outdoor consumption would not change the seasonal variation. As seen from Figure 13, the indoor and outdoor water use display different (generally opposite) seasonal patterns. It is easy to understand the seasonal pattern of the outdoor water use. It is high in summer and low in winter, as summer requires more watering in the garden. However, higher indoor water use in winter may be attributed to fewer outdoor activities or more indoor activities, such as longer hot showers and washing heavier/more clothes during winter. This means it is necessary to model separate seasonal functions for indoor and outdoor water use as follows
This paper was originally presented at the AWA Water Efficiency Conference, March 2011.
Acknowledgements The author wishes to thank Barry Abrams for reviewing the paper and for his valuable comments. The author also wishes to thank Frank Spaninks for many fruitful discussions and useful suggestions over the years.
The Author
Dr Yue-cong Wang (email: Yue-cong. wang@sydneywater.com.au) is Senior Modelling Specialist with Sydney Water.
Consumption (L/d)
Q = (b+cln ( L ) )f O (s t ,w t ) (7) + (a+kH α)fI(st,wt) References the savings of 20.9 kL/hh/Yr obtained using theoutdoor and a and b in equation (7) can be Parameters and f are indoor where f O I The savings from the WaterFix program Beatty K, 2011: How people in Sydney saved participant and control group matching approach solved separately as drought they restrictions. also have opposite functions for seasonal variation and water during AWA Water ranged from 16.4 to 21.58kL/hh/Yr with (ISF 2003). The savings of the washing machine weather conditions (temperature, rainfall Efficiency Conference, March 2011. seasonal patterns (SWC 2011). the long-term average of 18.7kL/hh/ programwith estimated in this analysis is also and evaporation). Yr.rebate This is consistent the savings Heinrich M, 2007: Water end use and efficiency within the range of the independent estimate from of 20.9kL/hh/Yr obtained using the project (WEEP) – Final Report. BRANZ Study CONCLUSIONS Parameters a and b in Equation (7) can Report 159. Judgeford, New Zealand, Branz. 18 kL/hh/Yr for 4A machines et alseparately 2006) as they also have participant and control group matching (Kidson be solved approach (ISF 2003).for The4 savings of to 24 kL/hh/Yr star machines. opposite seasonal patterns (SWC 2011). Institute for Sustainable Futures (ISF), 2003: This paper presented a method for separating the washing machine rebate program Residential retrofits – analysis of water savings. indoor and outdoor consumption from customer estimated in this analysis is also within the Conclusions Institute for Sustainable Futures. Prepared for Seasonal variation of indoor water use metered data using size and lot size of Sydney household Water Corporation. range of the independent estimate from This paper presents a method for 18kL/hh/Yr for 4A machines (Kidson et al., individual residential houses. Kidson R, Spaninks F & Wang YC, 2006: separating indoor and outdoor Using the results in the second application, the 2006) to 24kL/hh/Yr for 4-star machines. Evaluation of water saving options: Examples consumption from customer metered frombeen Sydneyapplied Water’s demand management indoor variation and outdoor consumptiondata ofusing a household typical size andThe method has to track indoor and lot size Seasonal programs. Australian Water Association house without WE programs and with a family of 3 of individual residential houses. The of indoor water use 2 outdoor savings during drought restrictions. It Regional Conference, October 2006. in Figure 13.applied to track people and 500m lot size are shown method has been indoorthat shows people have chosen to use Using the results in the second Loh M & Coghlan P, 2003: Domestic water use and outdoor savings during drought b in Equation (4) cannot a and Since constants significantly less water indoors even though application, the indoor and outdoor study. Perth, Water Corporation. It shows that people have be solvedof aseparately, the indoorrestrictions. consumption drought restrictions only targeted outdoor use. consumption typical house without chosen to use significantly less water Mayer P, DeOreo W, Towler E, Martien L & Lewis herein the a family household size dependent WE programsisand with of three The results are consistent with the outcomes from D, 2004: Tampa Water Department residential indoors, even though drought restrictions 2 lot size are shown in people and 500m consumption (ie the last term in only Equation (4)), the research project into howstudy: people reduced water conservation The impacts of high their targeted outdoor use. The results Figure Since constantsconsumption a and b in while13.the outdoor is are theconsistent household efficiency plumbing fixture retrofits in singlewater use during the drought restrictions (SWC with the outcomes from Equation (4) cannot be solved separately, family homes. Tampa, Aquacraft, Inc. Water size independent consumption (iethe the first three research project into how 2010b). people the indoor consumption herein is the Engineering and Management. theirvalue water use during the terms in Equation (4)). Adding a reduced constant household-size dependent consumption Mayer P & DeOreo WB, 1999: Residential end drought restrictions (SWC 2010b). into or term subtracting The same method was extended to estimate the (ie, the last in Equation a (4)),constant while the value from the uses of water. Boulder, CO, Aquacraft, Inc. indoor and outdoor consumption would not savings from Water Sydney Water’s WaterFix and outdoor consumption is the household The same method was extended Engineering and Management. change the seasonal variation. size independent consumption (ie, the to estimate the savings from Sydney washing machine rebate programs. The results Roberts P, 2006: Residential end use first three terms in Equation (4)). Adding Water’s WaterFix and washingare machine similar with those the measurement study. obtained Water Journal 33using (3). rebate programs. 600 participant and control group matching method. 500 400 300
Indoor - Household size dependent component Outdoor - Household size independent component
200 100
Ju l- 0 2 Ja n03 Ju l- 0 3 Ja n04 Ju l- 0 4 Ja n05 Ju l- 0 5 Ja n06 Ju l- 0 6 Ja n07 Ju l- 0 7 Ja n08 Ju l- 0 8 Ja n09 Ju l- 0 9
0
Figure 13: Seasonal variation of indoor and outdoor consumption.
Figure 13: Seasonal variation of indoor and outdoor consumption As seen from the above figure, the indoor and
Sydney Water Corporation 2010a: 2009–10 Water The results are Conservation and Recycling Implementation similar to those This method can also be used for forecasting total Report. Sydney Water Corporation. obtained using water use by Sydney residential properties (SWC the participant Water Corporation 2010b: Unsung 2011). water savings – How people in Sydney saved water and control group during drought restrictions. Sydney Water matching method. Corporation. This method can ACKNOWLEDGMENTS also be used Sydney Water Corporation 2011: Residential for forecasting demand forecasting model. Sydney Water The use author wishes to [Under thank Barry Abrams for Corporation. preparation.] total water by residential reviewing theWillis paper and valuable comments. The R, Steward R, Panuwatwanich K, Capati properties author also wishes toD,thank Frank Spaninks for B & Giurco 2009: Gold Coast domestic (SWC many 2011). fruitful discussions water end use study. and useful suggestions
over years. REFERENCES
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MAY 2011 67
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refereed paper
THE InfluEnCE of DEClInInG PERCEPTIonS of SCARCITy Exploring a new paradigm of future demand management options D Giurco, T Boyle, S White, B Clarke, P Houlihan Abstract Many jurisdictions have implemented major supply augmentation schemes to compensate for population growth and climatic variability. Demand management (water efficiency) strategies are also embedded into urban water management across many Australian utilities. However, the focus on demand management is now at risk of dilution in a less supplyconstrained context. This paper explores the future of demand management in utilities with (perceptions of) reduced water scarcity. Using the Central Highlands Water (CHW) Ballarat & District and Maryborough Water Supply Systems (hereafter referred to as Ballarat and Maryborough) as case studies, this paper details current efforts to not only sustain existing efficient water use behaviour but explore additional strategies for managing demand after major supply augmentation and perceived ‘breaking of the drought’. Following the case study findings, the role of demand management in the future is discussed, including how programs can be measured and justified, both in terms of water and energy saved and wider sustainability and community engagement benefits.
Introduction Demand management: a changing context Demand management programs have been increasingly implemented in cities and towns across Australia. These have been driven by droughts and a focus on the need to conserve water as well as future supply-demand balance shortfalls resulting from rising population and uncertainty over future inflows to dams, including as a result of climate change. Demand management (water efficiency) programs, such as leakage repair and installing lower-flow showerheads are generally more cost-effective than looking to new supply infrastracture to meet any shortfall, and at the same time save energy through reduced system pumping – and
68 MAY 2011 water
in the case of end uses such as showers and washing machines – water heating. However, in addition to utlities implementing water demand management programs, many have built Figure 1: Population growth projections for CHW Ballarat & District new supply Water Supply System. infrastructure water utility, Central Highlands Water including Corporation, currently services around desalination plants, pipelines and the 120,000 people within the region (CHW development of new groundwater 2010b) and manages the bulk supply of resources. This increase in available around 12,500ML/yr of water (including supplies, together with recent rains 60,470 connections) (CHW 2010a). Head in several parts of Australia, has works infrastructure managed by the implications for community perceptions utility includes 31 reservoirs, 13 diversion of water scarcity and potentially changed weirs and 30 groundwater bores (CHW approaches to water conservation and 2010a). The region is set to experience demand management. From the utility significant population growth over the perspective, there is a need to manage future revenue streams to ensure recent next 50 years. The population serviced infrastructure investments can be paid for, by the Ballarat & District Water Supply while still promoting sustainable water use. System (c. 115,000), for example, is The future role of demand management expected to almost double, as shown needs revisiting in this unchartered context. in Figure 1 (CHW 2010b, VIF 2008). Further strain on water supplies may Aims of the Paper stem from the decline in projections to rain-fed storages and the number This paper uses Ballarat and Maryborough of persons per dwelling, following a as case studies to explore current efforts national trend of larger houses with fewer to sustain existing efficient water-use occupants and thus a greater number of behaviours following supply augmentation potable connections (ABS 2006). via connection of the Superpipe to Ballarat, and additional surface water and groundwater supplies to both Ballarat and Maryborough. Potential demand management options to complement the existing portfolio are explored and evaluated. Finally, the discussion focuses on the future of demand management in a post supply-constrained context in Australia and the need for a new framework in which to evaluate its benefits and costs.
Ballarat Context The Ballarat and Maryborough regions are located approximately 115km north-west of Melbourne, Victoria. The state-owned
Recent Events In the years leading up to 2008, prolonged drought and record low inflows saw Ballarat’s water supplies fall to a historical low of 7.4%. The situation resulted in the drying of Ballarat’s central recreation lake, Lake Wendouree. In 2006, following the release of the Victorian Government White Paper and Central Region Sustainable Water Strategy, the Institute for Sustainable Futures assisted CHW in creating a Demand Management (DM) Strategy which identified demand side options to be considered for
technical features
demand management
refereed paper
Figure 2: Historical demand by sector. implementation. The work conducted was based on the principles of Integrated Resource Planning (IRP) as outlined in the Water Services Association of Australia (WSAA) Guide to Demand Management (Turner et al., 2008). Since 2006, CHW has successfully implemented a number of DM programs that have significantly assisted in reducing demand. These include a targeted residential retrofit program with over 4,700 retrofits, saving around 170ML/yr; additionally, nonresidential efficiency programs have saved around 800ML/yr. The lack of water in Lake Wendouree and Ballarat storages brought the issue into focus within the community and assisted in accelerating the uptake of these programs. In addition, statewide programs have been implemented (together with CHW) which have also assisted in reducing demand, such as 3,600 residential water-efficient showerhead exchanges saving an additional 40ML/yr. Combined with stringent water restrictions these DM initiatives have aided a significant drop in potable consumption (see Figure 2).
In 2008, supply augmentation consisting of an $180m 87km Superpipe, connecting the Sandhurst Reservoir near Bendigo to the White Swan Reservoir near Ballarat, secured the region’s long-term water supply (Department of Premier & Cabinet, 2008); however, the pumping energy of around 2000kWh/ML (approximately 2–3 t CO2/ML) means a carbon price of $20–$30/t would translate to a carbon cost of $60–$90/ML. More recent supply upgrades include a $7m water recycling project to provide 600ML/ yr of water to Lake Wendouree.
The Post-Scarcity Conundrum
Water saving potential
0 Negligible
Efforts to encourage sustainable water use allow CHW to continue running its business in a ‘sustainable and responsible’ manner – namely, developing sustainable responses to future challenges which build on past successes. Continuing to engage with the community to promote water conservation also guards against bounce-back in water use. Demand management offers CHW a means by which the operational carbon intensity of recent supply augmentations can be offset, subsequently aiding the organisation to achieve its goals to reduce greenhouse gas emissions and satisfying compliance requirements set out in the Victorian EPA Corporate Licence Sustainability Commitment (CHW 2010a). Further, through demand management CHW continues to support the Victorian Water Industry Greenhouse Emissions Reduction Framework (CHW 2010a).
The prolonged water scarcities experienced in the region (2006–2009) had a big influence on community
Methodology
1
2
3
Low
Moderate
High
1-5ML/yr
5-25ML/yr
>25ML/yr High (pumping plus, e.g. hot water savings)
Greenhouse and energy savings
Negligible
Low
Medium (from water pumping
Community reach/impact
Negligible
Sector-specific (<20%)
Moderate (20-50%)
Costeffectiveness*
ModerateHigh >$3000/ML
Low-Moderate $1000-$3000/ML
Very Low <$1000/ML
No cost
LowModerate
Low
Negligible
None
Health risk*
organisational Goals
It is within this context of post-major supply augmentation that CHW seeks to continue supporting and promoting sustainable and responsible water use, while recognising severely restricted water use is no longer appropriate for either the community or the utility. Complementary gains in water efficiency will enable greater water security in the context of forecast climatic uncertainty and state-wide population growth serviced by major common water sources. It is important, however, that in lifting drought restrictions the community still uses water responsibly.
Table 1: Demand management triple bottom line evaluation criteria (semi-quantitative). Score
attitudes to water use. Low water levels in Lake Wendouree were particularly symbolic of water consumption and, among other issues, heightened awareness of the need to use water wisely. After the supply augmentation the current high levels of social capital remain as an opportunity for maintaining a water smart/wise message. Indeed, CHW predicted significant near-term water savings “due to an expectation that consumer memory from recent drought will help to achieve greater savings” (CHW 2010c). It is anticipated this social capital can be harnessed to promote future sustainable water use, notwithstanding that the lake has now re-filled.
*NB: Trend for 0=Nil to 3=high is reversed for cost-effectiveness and health risk (to maintain the higher the number the better).
High (>50%)
The approach taken for this research was for the Institute for Sustainable Futures, UTS, to review demand management initiatives implemented in other jurisdictions in Australia and assess their potential for implementation within CHW using a set of triple bottom line sustainability criteria (Table 1). The approximate costs and savings (or supply) of each option were based on indicative total resource unit costs (present value $/present value kL from the combined perspective of the utility, customer and other partners where applicable) of similar options implemented in other jurisdictions. Detailed modelling was not undertaken. Community reach/ impact refers to the breadth of customer base that an option potentially engages with to promote sustainable and responsible water use awareness.
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Results: Demand Management options
Discussion: future of Water Efficiency
Evaluation of options
Ballarat
The DM options assessed are summarised in Table 2. The analysis aimed to cover a diverse range of options and has already led to the successful establishment of an outdoor water saving program – “Ballarat Gardens Come Alive” and Maryborough “Gardens Come Alive” – with participation approaching 1,000 households. These programs encourage water efficiency through monitoring rainfall to reduce over-watering, and by encouraging efficient garden practices, including mulching.
Implementing water efficiency options in the Ballarat region may have merit for a range of reasons and over different time scales, for example:
Note, the list of options in Table 2 represents a menu of potential options, but it is not cost-effective for all to be implemented with the current supplydemand balance context. The next section discusses how changing drivers may affect the future selection and uptake of water efficiency options, both in Ballarat and nationally.
readily met, what drivers remain for the continuing pursuit of water efficiency? How efficient should we aim to be?
nationally These are open questions presented in a changing context, as much of Australia withdraws from drought due to the strengthening of La Niña and the construction of pipelines, interconnects or water grids and desalination plants. If populations continue to grow in our cities, in 30 years’ time even these augmented supplies may be inadequate. But for the intervening decades we must find new answers to the question of what role we think water efficiency should play in the urban context – year-on-year water savings, or just a rapid implementation as drought response? What are the appropriate strategies to manage demand and community expectations beyond the period of acute scarcity?
• Maintaining efficient water use behaviours in the community; • Cost-effective water saving options to close future supply-demand balance gaps; • Next generation options for longer term implementation, with water saving, greenhouse saving and nutrient recovery. In addition to the drivers for the utility to be sustainable and responsible, mandated Government water saving targets (in Victoria through the Central Region Sustainable Water Strategy) will continue to drive water efficiency options. However, in cases where such targets are
The authors propose that a new urban water efficiency framework is required to assess the contemporary drivers
Table 2: Assessment of demand management options (see Table 1 for scoring system.) Water Saving Potential
Unit Cost ($/kL)
Energy & GHG Savings
Community Reach
Health Risk
Ballarat water-clock and website to raise awareness of real-time community use
3
2
2
3
3
Outdoor garden program: home visits, in-home advice on water-efficient garden practices
3
1
2
2
3
Outdoor program: workshops/nurseries. Point-of-sale advice on water-efficient gardens
2
2
2
2
3
Evaporative air conditioners: supply and ‘tune up’ option; reduce new bleed rate
2
2
1
1
1
Accommodation: water-wise information; raise awareness of efficient water use for visitors
2
2
3
2
3
Secondary schools: Smart meters – installation of smart meters (e.g. Hydroshare)
2
1
2
1
3
Primary schools: water saving clubs – school-based competition/awareness raising
2
3
2
2
3
Raintank users’ guide and servicing maintenance information to tank owners
2
1
2
1
3
Additional residential retrofits: potential to target public housing and renters;build on success of Aquarius retrofit program
3
1
3
2
3
Toilet retrofits: potential to target accommodation; extend toilet retrofit to accommodation sector
3
1
2
2
2
Washing machine rebate: could target lower income families
3
1
3
2
3
Urine diverting toilets: links to potential for nutrient recovery (P, N)
3
1
2
1
1
Smart metering: residential –reduce leakage; better understanding of end uses
3
1
3
2
3
Smart metering: non-residential – extend focus on high users
3
2
3
2
3
Smart growth: new developments includes smart sewers, local treatment and reuse
3
1
3
2
1
Option
70 MAY 2011 water
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refereed paper
and wider (non-monetary) benefits from current and future water efficiency measures. This would enable the foundations on which water efficiency initiatives are proposed or withdrawn to be better understood, not as individual options, but recognising the cumulative impacts of the range of demand management options already in place across many communities. To what extent might utilities use demand management programs to “manage demand” both down and up, as the external operating environment and commitments to capital expenditure change? Further work is also needed to better understand the extent to which waterefficient behaviours have become deeply embedded in community behaviours and the extent to which usage will rise as a result of building the new supply infrastructure and the recent rains.
Conclusion This paper has explored a range of demand management options for potential implementation in Ballarat, Victoria – a region where a prolonged period of water scarcity has led to the successful implementation of several demand management initiatives.
It also identifies factors which change the motivation to pursue water efficiency options and argues for further work to establish the role of water efficiency in this new paradigm affecting much of Australia.
Acknowledgement The authors wish to thank Paul O’Donohue, CHW General Manager Strategy & Communications, for his guidance and support of the project and John Frdelja, CHW Hydrologist, for his help with providing data to underpin the research.
The Authors
and Sustainable Buildings; and Professor Stuart White, Director of the Institute for Sustainable Futures. Brendon Clarke is Coordinator Demand Management and Paul Houlihan is Manager Customer Products, both at Central Highlands Water, Ballarat, Victoria.
References Australian Bureau of Statistics, 2006: Household and family projections, Australia, 2001 to 2026. Cat. no. 3236.0, ABS, Canberra. CHW, 2010a, Annual Report 2009/10: Central Highlands Water, Ballarat, Vic, Australia. CHW, 2010b: Population data projections, Central Highlands Water, Ballarat, Vic, Australia. CHW, 2010c: Demand History Data, J. Frdelja 16/3/10 Excel File. Department of Premier & Cabinet, 2008: Goldfields Superpipe Ballarat Link, Media Release, Melbourne, Vic, Australia.
Dr Damien Giurco (email: Damien. Giurco@uts.edu.au) is a Research Director at the Institute for Sustainable Futures, University of Technology, Sydney. His research focuses on Integrated Resources Planning, Smart Metering and Industrial Ecology. He works together with Thomas Boyle, Researcher in Urban Water Futures
Turner A, Willetts J, Fane S, Giurco D & White S, 2008: Guide to Demand Management. Prepared for the Water Services Association of Australia by the Institute for Sustainable Futures, University of Technology, Sydney. VIF, 2008: Population Projections, Victoria in Future, Department of Planning and Community Development, Melbourne, Vic, Australia.
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demand management
EnErGy ConSuMptIon of DoMEStIC rAInWAtEr tAnkS Why supplying rainwater uses more energy than it should G Hauber-Davidson, J Shortt Abstract This paper presents the results of a detailed study into the energy consumption of domestic rainwater tank systems. The study included eight different types and brands of common rainwater supply pumps combined with seven different types and brands of pump controllers and rain-to-mains switches. Detailed energy and water use logging provided a clear understanding of the four underlying factors that combined to make up the total system energy consumption. The study presents several recommendations. These include applying holistic systems thinking to rainwater systems (e.g. fast-filling toilet cisterns, header tanks and washing machines that use fewer starts/ stops per cycle); maximising the energy efficiency of pumps across end uses, and introducing an “Energymark” type rating system akin to the Watermark to raise awareness of the energy efficiency issue among homeowners.
Introduction There is a large amount of public interest in rainwater harvesting. Water retailers such as South East Water in Victoria have responded to this popularity with incentive programs to support and promote rainwater harvesting as an alternative to traditional water supplies. Adoption of domestic rainwater harvesting is generally considered to be more energy efficient than alternative water sources, such as large desalination plants. Recently, however, studies examining the energy to deliver rainwater from the tank to the end use have been conducted. These studies have shown a surprisingly high energy use. They include a study (HauberDavidson et al., 2010) for South East Water involving 30 houses. Similar studies have been conducted by the Institute for Sustainable Futures (Retamal et al., 2009) and by Sydney Water. These studies yielded widely varying specific energy requirements for domestic
72 MAY 2011 water
rainwater harvesting systems, from under 1kWh to over 10kWh to supply 1kL of rainwater. These figures are far higher than theoretically calculated values of well below 0.5kWh/kL. Indeed, some of the higher figures exceed the energy need for large scale desalination at 3.5kWh/kL–4.5kWh/kL. Australian Bureau of Statistics data states that 21% of the approximately 7,900,000 Australian households are equipped with a rainwater tank. From this, it can be extrapolated that there may be 1.6 million rainwater tanks with the potential to supply some 50GL/a, or about 10% of the planned capacity of all Australia’s seawater desalination plants. Their energy consumption would be in the vicinity of 100GWh/yr or 2% of a large 1GW coal-fired power station. Associated carbon emissions are 100,000t.CO2-eq. Efficiency improvements across the board of just 20%, such as those readily identified in this study, could lead to energy savings of 20GWh/yr or emissions reductions of 20,000t. CO2-eq/year – the equivalent of taking 4,000 cars off the road.
Study Aims The broad objectives of this study were to investigate and understand the specific energy consumption of a range of domestic rainwater harvesting components and systems over a range of end uses, and then draw from this a number of specific recommendations regarding how to maximise the energy efficiency of domestic rainwater harvesting systems. It was performed by Water Conservation Group Pty Ltd on behalf of South East Water, with co-funding from Davey Water Products P/L and Tankworks Australia.
Methodology The energy use of a rainwater harvesting is due to two basic components: 1. The pump that transfers water from the rainwater tank to the desired end uses; and
2. The pump controller and switch. It determines when the rainwater pump starts and stops and when it switches over to supply mains water instead of rainwater – for example, when the tank is empty or in case of power or pump failure. Figure 1 shows how these components are typically configured in domestic rainwater harvesting systems.
Figure 1: Typical process flow diagram for a rainwater harvesting system. In total, eight rainwater pumps and seven control/switch devices were included in the study. The matrix in Table 1 (overleaf) shows the combinations tested. The approach was to monitor the energy consumed by the rainwater pump and the controller/switch device separately. Energy consumption was recorded for the pumping of water under a range of different scenarios as well as the energy use caused by the controller/ switch and its control logic. The tests were undertaken in a residential house in Sydney. The house was vacated during the testing period so that each test could be performed in isolation from any other water use. A standard suite of tests consisting of simple flow tests (both for a variety of flow rates and run times), switch standby power tests, and toilet flushing tests were conducted on all pumps. In addition, a number of tests were run on a limited number of systems to test the specific effects of each end use. These consisted of tests on washing machine use, indoor and outdoor garden taps (both upstairs and downstairs), shower use, and a variety of toilets with different flushing mechanisms.
technical features
demand management The schematic diagram in Figure 2 shows a water flow diagram, the measuring points and the monitoring equipment used in the study.
Table 1: Pump-switch/controller testing matrix. Pump Switch and Controller
The monitoring equipment used to log energy consumption was a PowerMate energy meter, capable of logging electrical energy consumption to an accuracy of 0.0001kWh (0.1Wh). To record water consumption, Water Conservation Group’s MiniLogger device was used (Figure 3).
Pump
results and Discussion
Leader EcoWater
Davey HM60-10
Davey Rainbank
Davey Torium
Davey Speedman
X
Davey HP45-05
X
Davey 42A/B
X
Onga WaterSwitch
PressControl
SilverStorm PS-01B/1
X X
X
X
Onga SMH55
X
Onga SMH35
X
Onga TankBuddy
X X
A key parameter used for analysis in SilverStorm 800W this study is specific energy. The specific energy consumption is The energy consumption caused by defined as the total energy consumption the controller/switch can be broken used to supply a certain volume of water; down into two components: that is: • The controller/switch standby energy consumption, caused by the constant Specific Total Energy Used in Period power draw of the switch, regardless Energy = Total Water Supplied in Period of whether the pump is running or not (akin to the standby power of a TV set). Specific energy is thus measured as kWh/kL. Considering the energy consumption of rainwater systems in terms of specific energy use is advantageous, because it facilitates comparison between the energy consumption of different events and usage profiles. There are two elements which consume energy in domestic rainwater harvesting systems – the pump and the switch/ controller device. Analysis of these elements showed that, in turn, the energy consumption of the pump can be broken down into two components: • The pump start-up energy consumption, caused by a spike in energy as the pump overcomes initial friction upon starting. • The pumping energy consumption, caused by the energy consumption of the pump as it delivers water to the end use.
Table 2: Standby power of various pump-switch/controllers. Controller/Switch
Standby Power (W)
Davey Rainbank
1.84
Davey Torium
2.00
Davey Speedman
4.43
Onga WaterSwitch
1.38
PressControl
1.66
SilverStorm PS-01B/1
1.49
Leader APC
1.58
Leader APC
• The system shutdown energy consumption, caused by the switch requiring the pump to run on for a period of time after water demand has stopped. While this energy is consumed by the pump, and thus depends on the pump size, the controller/switch dictates for how many seconds the pump runs on before it shuts down.
X
Figure 2: Water flow diagram and monitoring equipment. that they pumped very little water; thus the majority of energy use was from
The relative importance of these elements is described below.
standby consumption.
pump start-up energy consumption Analysis of the pump start-up energy consumption indicated that it is a relatively insignificant component of the overall energy consumption of rainwater harvesting systems. For example, it consumed between 0% and 1.3% of the energy required for a full toilet flush.
standby energy consumption for the
Controller/switch standby energy consumption The controller/switch standby energy consumption is a significant element of rainwater system energy consumption. How significant it is for a given Annual installation depends on the level Consumption of use for the system. Because it (kWh) represents energy consumption 16.1 unrelated to rainwater supply, 17.5 the more water a system supplies to end uses, the lower 38.8 the significance of the controller/ 12.1 switch standby energy will be. 14.5 Some of the very high (>8kWh/ kL) overall specific energies 13.1 found in previous studies can be 13.8 attributed to the fact
Table 2 shows the controller/switch units tested in the study. The annual consumption of the units is added as a reference point. System shutdown energy consumption The system shutdown energy consumption is a significant element of the energy use of rainwater systems. It uses between 5% and 25% of the energy required for a full toilet flush. For short events, such as a small trigger from a garden spray gun, the energy consumption due to the shutdown control algorithm can be a multiple of the pumping-only energy required.
Figure 3: Water Conservation Group’s MiniLogger.
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MAY 2011 73
demand management Table 3: System shutdown energy per event for various pump-switch/controller combinations. System (Pump and Controller)
System Shutdown Energy Cons. (kWh)
Davey 42A/B (submersible) with Rainbank
0.00038
Davey HM60-10 with Rainbank
0.00054
Davey HM60-10 with Speedman @ 4bar
0.00074
Davey HM60-10 with Speedman @ 6bar
0.00095
Davey HP45-05 with PressControl
0.00157
Davey HP45-05 with Torium
0.00200
Leader with Pressure Switch
0.00184
Onga SMH35 with WaterSwitch
0.00132
Onga SMH55 with WaterSwitch
0.00184
Onga TankBuddy (sub.) with WaterSwitch
0.00189
SilverStorm 800W with PS-01B/1 PS
0.00174
Figure 4: Specific pumping energy for different flow rates.
Table 3 shows the shutdown energy consumption for each pump and controller combination tested in the study, for each event. pumping energy consumption For domestic rainwater harvesting systems with typical end use profiles (toilet flushing, washing machines, outdoor taps), the pumping energy is the most significant component of energy consumption. The pumping energy consumption (expressed in terms of specific energy) over a range of flow rates for a selection of the pumps included in the study is shown in Figure 4. The lower the specific energy, the more energy efficient a pump is. The specific pumping energy consumption was found to vary according to the flow rate. The greater the flow of water, the more efficient the pump becomes. This is because pump motors were found to have a very similar power draw regardless of the flow rate. Surprisingly, it was also noted that varying the pressure within practical limits (20 to 45kPa) had little impact on pumping energy. The graph in Figure 5 compares the specific pumping energy for two flow rates typically seen in domestic rainwater systems for the systems tested.
Figure 5: Specific pumping energy comparison for 8 and 17L/min. Figures 8 and 9 (both of which are on the same time scale on the x-axis) show the total water supply (in black) and the instantaneous power draw (in blue) for a full (6L) toilet flush. Each was filled using a Davey HP45-05 with a Torium pressure control switch. Note that the second chart shows two toilet flush events. The time scale is the same though. These figures clearly show that the time taken to fill the toilet with the sinker valve (fast-filling, Figure 9) was far less than the
Figure 5 shows a general trend in terms of a pump-by-pump comparison â&#x20AC;&#x201C; smaller pumps (in terms of pump motor power) typically have a lower specific energy use for a given flow rate, though there are some exceptions to this. This is essentially because smaller pumps with a lower power rating use less energy to achieve a given (low) flow rate than larger pumps with a higher power rating. The higher energy consumption to deliver a given volume of water at a lower flow rate leads to interesting observations related to filling toilet cisterns. Some cistern valves allow a fast filling at a higher flow, while others permit a slow filling at much smaller flow rates only.
Figure 8: Water supply and power consumption profile: Slow-filling cistern.
To quantify the impact of this, toilets with two different cistern filling valves were tested. The first toilet had an older float arm valve. The other had a newer sinker valve (Figures 6 and 7).
Figure 6: Toilet with float arm valve. Figure 7: Toilet with sinker valve.
74 MAY 2011 water
Figure 9: Water supply and power consumption profile: Fast-filling cistern.
technical features
demand management time for the toilet with the float arm valve. The characteristics of each of these events are described in Table 4. Thus the float arm valve causes the cistern to fill 3.5 times slower than the sinker valve, leading to an energy consumption almost three times higher (Table 4). This demonstrates the importance of flow rates. Figure 5 appears to suggest a clear order from least to most energy-efficient pumps. Since the pump size in terms of power rating in Watts (W) generally increases from left to right, Figure 5 seems to suggest that smaller pumps are more energy efficient than larger pumps for domestic rainwater harvesting purposes. However, further testing indicated that this was not necessarily the case. Figure 10 shows the total pumping energy for a standard toilet flush for each of the pumps studied. The specific energy use of each pump at a flow rate of 8L/min is also shown.
Table 4: Toilet valve comparison. Float Arm Valve Toilet
Sinker Valve Toilet
Volume of water supplied by pump
6.3L
6.2L
Cistern filling time
139s
40s
2.7L/min
9.4L/min
Total energy used
0.0270kWh
0.0092kWh
Overall system specific energy use
4.3kWh/kL
1.5kWh/kL
Average water flow rate
min in under 30s while the Onga SMH35 filled it at only 5.1L/min, taking 70s. Thus a larger pump can fill the toilet cistern in a shorter time meaning that the pump, although its power draw is much greater, runs for much less time and consumes less total energy. This can be further demonstrated by comparing the duty points on the pump curves for the two pumps (Figure 11). Initially, Figure 11 seems to confirm that the Onga SMH35 uses less energy than the Davey HM60-10. However, when considering the actual operating points for the filling of the cistern (green and blue dots), the results reverse. The Onga SMH35 operates at a specific energy use close to 1.25kWh/kL while the Davey HM60-10 runs at just below 1.1kWh/kL.
Figure 10: Specific pumping energy comparison – toilet flushing. Figure 10 suggests a quite different pump energy efficiency hierarchy than Figure 5. It shows that while some larger pumps, such as the Davey HM60-10 @6bar, have a higher specific energy for a given flow rate compared to smaller pumps such as the Onga SMH35, the total amount of pumping energy they use to fill a toilet cistern is actually lower. This is because the larger pump is capable of pumping water into the toilet cistern at a higher flow rate than the smaller pump. The Davey HM60-10 filled the toilet cistern at a flow rate of 13.5L/
Figure 11: Pump operating points for toilet cistern filling. Thus the specific energy use for filling a toilet cistern is some 10% lower for the larger Davey HMN60-10 than for the smaller Onga SMH35. Hence the simple conclusion that smaller pumps are more energy efficient in the domestic rainwater harvesting scenario is not always true. This suggests the following conclusion: For a pump to be judged as energy efficient for the purposes of domestic
Figure 12: Energy use breakdown by component – toilet flush.
rainwater supply, it must be energy efficient both in terms of specific energy for any given flow rate and for transferring a discrete volume of water such as when filling a toilet cistern. This will allow it to operate efficiently for both steady flow rate applications (such garden irrigation or hosing) and for applications where a given volume of water is transferred (such as filling a toilet cistern or a washing machine). pressure vessels Pressure vessels containing 5L–10L of pressurised water potentially have the ability to supply water to small-volume (1L–2L) end uses without the need for the pump to turn on, thus reducing pump start-up and system shutdown energy consumption. However, the tests undertaken with a pressure vessel suggested that this did not occur. When opening a tap for only a short period of time, the pressure vessel did not prevent the pump from turning on. Discussions with the pressure vessel’s supplier (Davey) indicated that this was due to the large drop in system pressure caused by opening the tap, making the pressure switch turn the pump on regardless of the presence of the vessel. filtration Many domestic rainwater harvesting systems are equipped with filtration systems. Testing of system responses both with and without these filters showed that when the filter cartridges are dirty, they can reduce pumping flow rates and thus push specific pumping energy consumption up – in the study, a filter which had been used to only a low-mid range level reduced energy efficiency by 3%. Thus the cartridges
Figure 13: Energy use breakdown by component – full day’s use.
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demand management should be replaced on a regular basis to minimise efficiency losses through them. relative importance of components The relative importance of each component and the increasing importance of controller/switch standby energy use are shown in Figures 12 and 13. Figure 12 shows the energy use breakdown for a single full (6L) toilet flush (Test system: Davey HP45-05 with Rainbank). In contrast to the single-event analysis in Figure 12, Figure 13 provides a breakdown of the energy consumption for an entire day. It is assumed that the system is connected to a toilet only, which is flushed 15 times. This chart demonstrates the significance of switch standby energy consumption. From insignificant, it increases to 29%. While the pump operates for a few minutes per day only, standby power draw is 24/7. Long-term system comparison In addition to the short-term targeted testing that is the subject of the majority of this report, the long-term performance of a domestic rainwater harvesting system was observed for two different pumps and switch/controller setups. Observations were made for normal real life conditions in the test residence. The two systems were: • An Onga SMH55 equipped with a WaterSwitch; • A Davey HP45-05 equipped with a Rainbank. The overall specific energies of these systems were recorded for a number of weeks for a similar usage pattern consisting of the following end uses: • Toilet flushing – both slow and fast cistern-filling valves; • Washing machine use; • Hand basin/kitchen sink tap use – cold and hot; • Showering (with both hot and cold water connected); • Garden irrigation/hosing/car washing. The diversity of these uses meant that there was a mix of high flow, high volume use (e.g. the washing machine) and low flow, low volume use (e.g. hand basin taps). The rainwater connection to the hot water system and to the cold water of hand wash basins meant that there were frequent short water uses. This is not a typical setup, although connecting rainwater to hot water does provide a cost-effective way of connecting a large demand to a rainwater harvesting system to a suitable end use.
76 MAY 2011 water
It was found that for this longerterm monitoring period, the Onga system averaged 2.4kWh/kL, while the Davey system averaged 1.9kWh/ kL. This provides a practical example of the findings contained in this report. In accordance with the conclusions described above, this is attributable to the following factors: • The superior pumping energy efficiency of the Davey pump used compared to the Onga; • The lower system shutdown energy consumption of the Davey Rainbank compared to the Onga WaterSwitch; • While the Davey Rainbank has a higher standby energy consumption than the Onga WaterSwitch, the high overall usage of rainwater at the residence makes this negligible in the overall calculations.
recommendations and Conclusions As a result of this study the following recommendations are made: • Apply holistic systems thinking (e.g. fast-filling toilet cisterns should be chosen for rainwater supplied systems, header tanks could be considered, and washing machines should be designed with fewer fill start/stops per cycle). • Minimise pumping energy consumption by using an energy-efficient pump and by transferring water at a flow rate as high as possible. • Minimise system shutdown energy consumption (and pump start-up energy consumption) by pumping water for long pump runs – and by using a switch/controller which minimises the run on time after water transfer is complete. • System shutdown energy consumption and pump start-up energy consumption could be further improved by developing switches that can work with pressure vessels, allowing small volumes of water (1L–2L) to be supplied without a pump start. • Minimise controller/switch standby energy consumption by designing these devices with a low or no standby energy use. • Minimise the relative contribution of controller/switch standby energy consumption by supplying as much water uses as possible – in a waterwise manner. • Where rainwater is not expected to run out, or where only small amounts of
top-up water are expected to be used (<7kL/year), a trickle top-up system should be used in lieu of an automatic rain-to-mains switch as the additional pumping cost for top-up mains water is less than the standby energy consumption of the switch. • Accept that for the currently available systems, frequent triggering of water use reduces the rainwater energy efficiency dramatically, even though it is water efficient. In relation to connecting rainwater to hand wash basins, or the hot water system, this means that the home owner will have to make a careful assessment of trading off additional water savings achieved vs. a higher specific energy use. • The industry should react to the findings of this study and provide more energy-efficient systems meeting the demands of typical domestic rainwater harvesting systems, such as more efficient rainwater pumps and controller/switches with lower standby energy consumption. • An “Energymark” type rating system (akin to the Watermark approval) should be introduced to readily indicate to the home owner exactly how energy efficient a particular rainwater harvesting system is.
Acknowledgements Bridget Wetherall, a Project Manager at South East Water, organised the project and its funding.
the Authors
Guenter Hauber-Davidson (email: guenterhd@watergroup.com.au) is the Managing Director of WCG Pty Ltd, a company which specialises in consulting and operations for integrated water efficiency solutions. Julian Shortt is a Senior Water Savings Engineer at WCG.
references Hauber-Davidson G, Shortt J & Wetherall B, 2010: Energy Consumption in Domestic Rainwater Harvesting. Report available on request from South East Water. Retamal M, Turner R & White S, 2009: Energy Implications of Household Rainwater Systems. Water Journal 36, No.8 (December).
technical features
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refereed paper
SyDney WATer’S SmArT meTerIng reSIDenTIAl ProjeCT An insight into the benefits, costs and challenges of smart metering C Doolan Abstract Sydney Water recently carried out an 18-month-long trial to assess the costs and benefits of smart metering. The trial was conducted from December 2008 to June 2010, in the district-metered Sydney suburb of Westleigh. Over 600 properties and almost 2000 customers were involved, with smart meters being installed to provide a comprehensive record of residential water consumption. One of the key findings was an overall 7%–10% reduction in water consumption in households with a digital in-home display (IHD). In the detection of household leakage, smart metering has proven to be an effective tool, with an average leakage rate at customer properties in the order of about 3% of total usage. The trial has also proved valuable in supporting the management of network leakage. The water consumption data generated is being used to develop a model of night-time water use to improve minimum night flow monitoring within networks. Attempts to directly measure network leakage on a near realtime basis have been less successful. At this stage smart metering is not cost effective and there are limitations to the current technology. Future advancements in technology might see an integrated multi-utility smart meter for which there may be significant cost reductions.
Introduction The Smart Metering Residential Project involved 630 properties in the northwest Sydney suburb of Westleigh. The project began in December 2008 with 468 properties being fitted with automatic meter reading (AMR) devices, enabling water consumption to be monitored and recorded remotely. A subset of 161 properties were equipped with a digital in-home display (IHD) that provided customers with near real-time and historical water use information. A control group consisting of over 200 properties was mainly located in an adjoining area.
The study area of Westleigh was selected because it is a district-metered area at the end of a water supply system. It has a single source of supply and a new electromagnetic flowmeter at the head of system. The study area needed to consist of about 400–500 single residential dwellings with a fleet of 20mm water meters to enable sufficient recruitment of households for the IHD trial and a similar-sized control group. The main objectives of the project were to: • Assess the impact of smart metering on reducing household water consumption through behavioural change; • Quantify the extent of household leakage and customers responses to those leaks; • Assess network leakage and refine minimum night flow calculations; • Quantify the costs of smart metering. The project was designed as a quantitative and qualitative study. Key components of the trial included the collection of water consumption data, bulk flow data, leakage data, household and participant surveys and two phases of in-depth interviews with 24 participants.
distributed throughout the Westleigh study area, each collecting data from about 20 transmitters. The Spider loggers automatically relayed water usage data on a daily basis to Sydney Water’s file transfer protocol (FTP) server. This was done via the mobile network using a built-in wireless internet capability. The third component was the IHD that was located in the customer’s home. Each IHD was set up to communicate with the wireless transmitter connected to the water meter of that particular house. The IHD obtained the current meter reading on an hourly basis through a low-power radio link and provided both real-time and historic information on water use. Each IHD was programmed according to the number of occupants in the home, giving a comparison to the average water-efficient Sydney household of the same size (see Table 1 for target figures). This target was programmed into the IHD as a result of the findings from the South East Water EcoPioneer Project1, which showed that a benchmark was needed so that customers could gauge their performance.
Table 1: Water-efficient household targets. No. Occupants
Litres/Day
The Technology
1
259
The smart metering technology adopted for the project consisted of three main components. A wireless transmitter was connected to the existing Elster V100 water meter at each property. Using the meter’s integral pulse output, the transmitter recorded water consumption at pre-set intervals. AMR logging intervals were initially set to five minutes, but these were changed throughout the study period to find a balance between data resolution and the battery life of AMR devices. A half-hourly logging interval was deemed to provide the optimal balance.
2
378
3
484
4
570
5
647
6
717
Water consumption data from each property was then transmitted every 11 hours to a concentrator called a ‘Spider’ logger using a radio frequency of 433 MHz. There were 23 Spider loggers
The IHD used for the project has four touch screens, representing the data graphically and numerically. The first screen (see Figure 1) shows the household’s average daily use over the last seven days. If the household use is below the average the bar is green, and if it is above the average then the bar is red. The remaining three screens were in the form of column graphs. In turn, they showed hourly use over the last 24 hours,
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demand management Qualitative research methods From a social behaviour perspective there were several elements to this research, which involved collecting information from customers through surveys and interviews. Figure 2 shows the social research stages.
Figure 1: IHD summary screen. a comparison of daily use from one week to the next and, finally, daily use over the last 28 days. The IHD devices also featured a leak alarm capability. If the unit detected continuous water use extending over a 24-hour period, it would display a ‘possible water leak’ message. This message cleared automatically once the leak had been rectified. Similarly, if a tap had been left on an alarm was sent, but once the tap was turned off, the leak alarm would disappear.
Quantative research methods The quantitative research involved the analysis of consumption data collected from all 468 properties and 15-minute supply data from the bulk flow meter. In terms of leakage management, the water usage data obtained from the study allowed night usage in single residential dwellings to be characterised according to changes in seasons and weather conditions. The intention was to incorporate this information into a larger night usage model, which in turn would be used to refine system minimum night flow calculations and hence network leakage estimates. The continuous water consumption readings from the smart meters were totalled and used for simultaneous comparison with the bulk supply flowmeter readings. Differences between the readings would provide a direct measure of supply system leakage at any given point in time and would aid the development of information technology tools for leakage monitoring using smart meters. Lastly, and to the extent that the existing meters were able to measure very low flows, the data would allow leakage on residential water services downstream of the meter to be quantified. The IHD had the capability of tracking the user’s screen touches. The number of touches was recorded half-hourly and sent to the Spider logger. This information is valuable in supporting the qualitative research to help understand how often the customers interacted with the device and how accepting they were of the technology.
78 MAY 2011 water
The participating households represented high, medium and low water users as well as a cross section of demographics and included households with and without IHDs. Twenty-four customers with an IHD also participated in a series of in-depth face-to-face interviews. The social research focused on gaining a better understanding of our customers, what their views and practices were in terms of water conservation, and what motivated or hindered their decisions about saving water. The emphasis of this part of the project was to determine if customers’ behaviours can be changed – and to what extent – if they are given more detailed and timely information on their water usage. The extended duration of the trial would allow for the sustained acceptance of the smart metering technology to be gauged.
results: Water Savings and Behavioural Change One of the key findings of the project was an overall 7–10% reduction in water consumption in households with an IHD, or an average water saving of 16kL per property per year. This behavioural change was sustained throughout the study period, despite the use of the IHD starting to decline after two months. Figure 3 (overleaf) shows the mean daily AMR consumption of households with and without IHDs. The relevant climate data has been added to the graph to provide context for consumption patterns. The data demonstrates that the comparative consumption of the IHD group was lower than the AMR group from the beginning of the IHD installation process in May 2009. As a group, those with IHDs continued to consume comparatively less water through to the end of the project in June 2010, when the IHDs were removed. The IHD group appeared to be able to save more water in comparison to the AMR
refereed paper
group in winter and spring (June 2009 to November 2009) than in summer and autumn (December 2009 to May 2010). These results could be interpreted as seasonal changes or initial enthusiasm in response to the IHDs. The majority of IHD participants liked having the IHD and their level of awareness was raised in terms of their water use. The behaviours that led to the reductions in water use were reported to be shorter showers, less garden watering, washing with full loads and installing water-efficient devices. For the IHD participants, a usage target was set that reflected the number of occupants in the household. These targets were met on an average daily basis of 61.5% of the time. While having a target was anticipated to be an incentive for participants, it proved to be a disincentive for those who were well above the target.
Household leakage Smart metering has proven to be an effective tool in detecting household leakage. About 80% of properties were identified as having a leak at some point in time during the project. Typically, on any given day, between 10% and 17% of properties had leaks. The average leakage rate at customer properties was in the order of about 3% of total usage, which is about 7kL per property per year. Over the study period, total leakage at individual properties ranged from 1.1L to 218kL and the duration of the leakage ranged from a single day to 468 days. Most of these properties (over 60%) had leakage that can be regarded as minor since the leaks detected were both relatively small and of less than 50 days duration. Leakage was much more significant at the remaining properties where the leaks were larger and/or extended over a considerable period. The ‘top’ 10% of properties in this category accounted for 62% of all leakage while the top 33% accounted for 92% of the volume of water suspected as lost due to leakage.
Figure 2: Qualitative research stages.
technical features
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refereed paper
The IHD participants had the advantage of being alerted to any possible leaks in their home. Just over half the households completed the final survey and 55% of those households indicated that they noticed the ‘potential leak alarm’. While 80% of those claimed to have looked for a leak to varying degrees, 40% actually found one or more leaks and had them repaired. Participants indicated that there were a number of limiting factors to having leaks repaired and these include costs, lack of time, convenience, lack of knowledge and skills.
network leakage and minimum night Flow estimates
Figure 3: Average daily consumption.
The trial has proved valuable in supporting the management of network leakage. The water consumption data generated is being used to develop a model of night-time water use to improve minimum night flow monitoring within networks. When finalised, the model should allow typical residential night usage patterns to be accurately depicted under varying weather and other conditions. This in turn will allow a better assessment of system leakage in different supply zones and the optimisation of leak detection efforts. Attempts to directly measure network leakage on a near real-time basis have been less successful. Uncertainties and discrepancies due to missing or erroneous bulk meter and/or AMR data were found to make short-term comparisons between supply and consumption an unreliable indicator of network leakage. Initially a network leakage figure of 2% was calculated for the Westleigh DMA. However, this figure is not a reliable leakage indicator, because the current method of transmitting the smart meter data wirelessly has not been perfected, and as such around 1–4% of consumption data was lost on a daily basis due to issues such as communication interference.
Key learnings As the trial tested the application and functionality of new technologies from the users’ and utilities’ perspectives, a great amount of flexibility and adaptability was required as the project evolved over time.
recruitment The recruitment of participants took a significant amount of effort. Although it commenced several months before the
technology was installed, recruitment continued well beyond the deployment phase. The process involved letters to customers, articles in the local newsletter and information posted on websites and shopping centre community boards. It also included presentations at community meetings and local open days. Despite these efforts, further measures were required such as phone calls, emails and face-to-face meetings in order to follow up prospective trial participants.
Technology In terms of the technology, there were numerous challenges in setting up the smart metering network. Installation of the Spider loggers on residential properties required the recruitment of customers in specific locations. While this option allowed for a constant and secure power supply there were issues in finding suitable locations and willing volunteers. Different scenarios were developed to overcome the problem of successful transmission of data between the AMR devices and the Spider logger. Difficult or unpredictable radio signals were caused by site geography, proximity of the smart metering components to each other, storms and obstacles such as buildings and parked trucks. Some properties proved unsuitable for the installation of an IHD due to poor data transfer between the AMR device and the IHD. A transmitter signal of greater than 30% of full strength was required to ensure the successful and continuous transmission of the data. Problems of defective or malfunctioning equipment were encountered, with more than 550 AMR devices being replaced, as some sites had multiple replacements.
There were some minor incidents of theft and vandalism. When AMR devices were replaced that also had an IHD on the property, updating the AMR radio frequency information in the IHD required direct access to the device within the property and to the customer. Often there were no customers at home during working hours and, therefore, delays were incurred in rectification of faults and greater loss of data or IHD operational continuity.
Data management Data reliability was also found to be an issue. The average monthly data transmission rates ranged from 84% to 99%, while individual transmission rates went as low as 27%. This current level of AMR data reliability would not be acceptable for billing purposes. The learnings from the project show that improvements to the technology and the communication set-up would be needed to minimise this issue in the future. As consumption data was measured on a household level, individual consumption within the home could not be measured in either the participant or the final survey. As an alternative strategy, the qualitative data provided a depth of understanding regarding consumption behaviour of individual household members. Both foreseeable and unforeseeable variables impacted on the consumption data throughout the trial. These included: • Heavy periods of rainfall ending the five-year drought; • Lifting of Level 3 Water Restrictions and the introduction of new Water Wise Rules;
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demand management • Climatic seasonal changes;
level of accuracy. The main issue appears to be the way data from the various sources is managed.
• The impact of a dust storm which was considered to be an extreme event and unusual for Sydney;
Cost
• Power outages due to interruptions to energy supplies; • Technical failures and adjustments; • Human error and interactions with the technology such as the IHD being switched off before the end of the trial. Tailored and effective solutions to these variables were implemented wherever possible to ensure that the data was as robust and valid as possible. Various comparisons between the Westleigh bulk flow meter data and AMR data were carried out in an effort to directly measure network leakage in a specific supply zone. Discrepancies between the data sources were identified. Meter accuracy does not appear to be a significant factor. It is considered highly unlikely that collective over-registration of the customer meters is the cause of the discrepancies.
water-efficient in an affordable manner. At this stage smart metering is costly and there are limitations to the current technology.
The cost associated with smart metering is currently very high. The cost per property was around $650 (for equipment) and $1,650 inclusive of all costs. These high costs can partly be attributed to the development, implementation and customisation costs associated with a research project of this nature. It has been estimated that in five years the cost would come down by almost half. This cost is based on a water meter with integrated smarts. It takes into account advancements in the technology, a better understanding of the system set-up and the improved efficiency and capability.
Future advancements in technology might see an integrated multi-utility smart meter for which there may be significant cost reductions.
Conclusions
Corinna Doolan (email: corinna. doolan@sydneywater.com.au) is Project Manager in the Water and Energy Futures Team within Science & Technology, Sustainability Division of Sydney Water.
Smart metering has proven that residential water reductions can be achieved and sustained through behavioural change. It is an effective tool in detecting household leakage as well as providing detailed data for minimum night flow calculations.
Similarly, the Westleigh flowmeter has been independently calibrated and found to be functioning within an acceptable
refereed paper
The challenge will be to use smart metering to assist customers in being
This paper was originally presented at the AWA Water Efficiency Conference, March 2011.
The Author
references 1. Wetherall B, 2008: South East Water. Final Report of the Eco-Pioneer Pilot Program.
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technical features
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refereed paper
CuStoMEr BEhAvIour MoDEllIng For PrEDICtIng FuturE DEMAnD A modelling and forecasting platform simulated over 40,000 households with 95 per cent accuracy D Perugini, M Perugini, B Clarke, J Frdelja Abstract Intelligent Software Development (ISD) consumer modelling and forecasting platform “SimulAIt” was used to create a detailed micro-simulation of over 40,000 individual households in Ballarat, Victoria, simulating their water use behaviour and reactions to water restrictions, price increases and marketing campaigns. Extensive validation of the model showed greater than 95% accuracy. SimulAIt forecasts showed that “bounce-back” in demand when restrictions are eased is likely to be modest due to consumers maintaining pre-existing water-saving behaviours. Additionally, demand is likely to be relatively insensitive to price increases, as the current level of behaviour maintenance provides limited opportunity for further reductions in water consumption. ISD’s forecasts can be used for corporate planning, and a more rigorous business case development to industry regulators. Traditional economic analysis of the effect of price increases was unable to model critical individual behavioural components, which, in this human-centric system, enabled an accurate prediction of consumption.
Introduction Background Drought has resulted in the implementation of severe water restrictions and various water conservation programs in the Ballarat and District Water Supply System (hereafter referred to as Ballarat) over many years. Recent increases in rainfall and augmented water supplies have allowed water restrictions to be eased. However, the impact on demand from easing water restrictions remains largely unknown. Historical data provides little insight into the likely impact of easing restrictions as no similar situation has occurred in the past. Better forecasts of demand and behaviour change from the easing of restrictions and increasing the water price, and quantification of the effectiveness of past conservation measures, are required
to help with short and long term planning, and to provide a more rigorous business case to industry regulators.
Shortfalls of traditional approaches: the human element Forecasting demand is becoming more difficult and there are many factors that need to be considered. Perhaps the most critical of these factors is the human decision-making element. In addition to considering this, it is also critical that the model be able to cope with the integration of large data sets and that the model can be validated. Traditional forecasting approaches such as spreadsheets, econometric/ mathematical models and statistical models are limited in addressing complex consumer modelling problems. Spreadsheets are two-dimensional and are unable to address complex multidimensional problems. They also have limited scalability and are most suitable for linear and not dynamic problems. Other approaches include econometric, mathematical and statistical methods. These top-down approaches are suitable for problems where the past is a good predictor of the future; however, they are limited in their ability to address non-linear, dynamic, and humancentric problems. Intelligent Software Development (ISD) has developed a demand model, “SimulAIt”, which uses cutting edge Defence technology to simulate the likely bounce-back in demand of residents in the community in response to the easing of water restrictions and increasing water prices. The SimulAIt demand model is able to consider both qualitative and quantitative factors that influence consumer decision making, including social, economic, environmental and political factors. By combining traditional economic and human factor analysis, SimulAIt can generate highly scalable, flexible and accurate simulations of large populations of consumers, enabling users to predict not only what consumers are doing, but to understand consumer
behaviour and, therefore, learn how to influence this behaviour to achieve desired outcomes. This sophisticated modelling approach allows the user to test what-if scenarios to determine the likely consequences of the implementation of new policies, pricing structures, or new products on their community. In doing so, decision makers are able to make informed decisions supported by quantitative analysis from a highly accurate model.
Emergent behaviour and consumers The SimulAIt platform is a microsimulation built using agent-based modelling. This is an emerging and maturing approach for consumer modelling and forecasting (Bonabeau, 2002, North et al., 2010, Farmer et al., 2009, Markose et al., 2007, Schenk et al., 2007, Zhang et al., 2007, Janssen et al., 2001, Twomey et al., 2002). The theory behind agent-based modelling can be described using ant behaviour as an example. Ants exhibit what appears to be efficient, coordinated and adaptable behaviour when collecting food – working together to feed the colony. One would assume there is a central manager coordinating this complex task, however, this is not the case. The complex behaviour of the ants is driven by each individual ant following three simple rules: i) if you see food pick it up; ii) then release a chemical signal; and iii) follow any chemical trails you come across. Ants’ sophisticated behaviour for collecting food is, therefore, a result of the emergent behaviour of the ants following these three rules. There are many cases where the emergent behaviours of these social systems are counter-intuitive, and understanding these systems using topdown traditional approaches is difficult, or indeed not possible (Bonabeau, 2002). Rather, a bottom-up modelling approach is more suitable whereby individual consumers and their rules (complex decision making) can be described,
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demand management and the emergent behaviour can be observed (Perugini et al., 2008). Agent-based modelling is the underlying technology behind the SimulAIt platform. Each “agent” represents a particular type of consumer. Agents are based on the human cognitive model and thus can mimic consumer behaviours and decision making. Using prescribed rules, each agent can mimic the complex behaviour of a broad range of individual consumers. Rules are constructed by integrating different types of (social, economic, environmental and political) data to describe how different people make decisions under different circumstances. The bottom-up approach is used where many agents are used to mimic the large numbers of people in the real world to simulate mass-consumers (i.e., a population). The simulation can be used to observe the emergent behaviour of the system (i.e., the forecasts), as well as the specific behaviours of individual consumers (i.e., the “why” behind the forecasts). Agent-based modelling has been successfully applied to environmental problems (Perugini et al., 2008, Rixon et al., 2007, Athanasiadis et al., 2004, Berger, 2001, Nuttal et al., 2009, Dietz et al., 2009), including the modelling of water pricing and water trading structures, and modelling household carbon emissions. Some of these models are still in their infancy.
the ChW Forecasting Model Creation In 2009, ISD was appointed by the Board of Central Highlands Water (Victoria) (CHW) to use SimulAIt to generate a behavioural micro-simulation of thousands of individual households in Ballarat (and, later, in Bendigo). The initial project (of two-month duration) was a retrospective analysis of efficacy of past water conservation programs. A second project (three-month duration) prospectively modelled demand management scenarios into the future. SimulAIt’s (cognitive) agents modelled individual consumers within households, how they made decisions in the house and garden, and how their decisions were influenced by different policies and communication signals, such as restrictions, prices, marketing and media communications. The model was created by integrating a wide range of complex qualitative and quantitative social, economic, environmental (engineering) and political data based on detailed demographic data (ABS 2006) and population dynamics. This included
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market research data, end-use studies (Willis et al., 2009), weather data, and economic and statistical data. The data was used to identify how different consumers made decisions under different situations or influences over time. The CHW forecasting model was created using a bottom-up approach and a detailed model of individual households and their occupants was constructed. The model details each area within individual households (for example, toilet, laundry), the composition of water-related products and appliances and water use behaviours, outdoor water usage and behaviours, and the change in product composition and community behaviours over time in response to demand management programs. The behavioural model was run over time (past and future) to assess the effects of various influences (scenarios) on decisions for change and decisions for usage for water consumption.
Influence-Behaviour Change Model The influence-behavioural change model describes in detail how social (including economic) influences may alter behaviours, decisions for change and, ultimately, water consumption. Influences are defined by four categories in the model: • Constraints (restrictions): Behavioural change forced upon residents (no legal choice). • Barriers (financial and other measures): Financial measures including prices, rebates and taxes (if applicable). The financial measures provide a barrier (when a choice is available) for water use and product acquisition behaviour.
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• obligation (severity of the situation and/or communications): Behavioural change resulting from (personal and social) obligation to reduce water consumption in response to the severity of the environmental situation (for example, current water levels or restriction levels). • Feedback (monitoring): Enables residents to obtain feedback from their behaviours, such as monthly statements and smart meters, to assist in controlling their behaviours. How influences ultimately result in behaviour change depends on messages received, as well as motivation and actions of individuals. The influencebehaviour change model describes the exposure of individuals to influences communicated (messages) through various media including radio, television, newspapers, phone, internet, billboards, or other people. Different individuals have different levels of exposure to particular media. The motivation of an individual to change behaviour is dependent on both the message and the individual, which is defined by the influence type, trust in the source of the message, message content, schedule of communication (e.g. frequency of communication), relevance of the message to the individual (e.g. garden restrictions have less relevance to those without a garden), and the level of interest (concern) that an individual may vest in the message. Individuals that are motivated to change their behaviour may translate this into action. The action (behaviour change) of an individual is determined by the causal relationship between possible behaviours and motivation. The extent to which behaviour changes (amount and persistence) is largely dependent on the level of motivation, the level of
Figure 1: Historical demand forecasts (red) versus actual demand (grey) in Ballarat.
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inconvenience for a particular behaviour change and any constraints preventing a choice (eg. water restrictions). Persistence describes how long an individual retains a particular behaviour and relates to the reversion/bounce-back in behaviour when influences are reduced. Persistence may be influenced by the extent to which an individual is inconvenienced with its current behaviour, the duration that an individual has endured a particular behaviour (ie. becomes accustomed to a behaviour, resulting in reduced inconvenience), and the level of influence still bearing on that behaviour.
validating the Model Methodology Extensive validation of the simulation model was conducted to prove the model and ensure confidence in the simulation results (forecasts). Validation is conducted by predicting forward from the past, where actual results (customer billing data) have not been explicitly used as an input to the model. The model can be validated at various levels (region, subregion, household area and product type). The CHW model was validated to a high level of accuracy for Ballarat. A more simplified version of the model was also validated in the unrelated Bendigo region, demonstrating the transferability of the model. Validation of the ability for the model to accurately forecast bounceback in demand was also performed.
validating demand forecasts in Ballarat Figure 1 shows a comparison of the simulated output versus the actual monthly water consumption of households in the Ballarat region. The graphs are closely aligned and show similar trends over an eight-year period from July 2001 to June 2009 where
different restrictions (Stages 1 to 4) and influences were present. The average accuracy for each monthly time point between the simulated and actual water consumption is 95.1%. Consistent with simulation results for Bendigo (see Figure 2), simulation forecasts show lesser water consumption when severe outdoor restrictions were first introduced, potentially indicating a high level of non-compliance at this time and/or a time lag for customers to become aware of restrictions and adjust their behaviour accordingly. As an extra point of validation, initial simulation results showed lower water consumption over the period from August 2003 to February 2005 where Stage 3 restrictions were in place. It was identified that the current Stage 3 water restrictions differed from Stage 3 restrictions in the past where greater garden watering was permitted. Therefore, the simulation model was able to identify this discrepancy, and as such the simulation results in Figure 1 use the actual Stage 3 water restriction definitions that applied.
validating bounce-back and transferability In order to validate bounce-back and transferability of the model, in 2009 the model was applied to the Bendigo region which had already commenced easing water restrictions. Results shown in Figure 2 show a high level of accuracy – greater than 96% in any given year. Validation results in 2009 when restrictions were eased show an accuracy of greater than 99% in forecasting demand. As with the Ballarat validation in the previous section, the forecasts were able to identify discrepancies in watering times with current and past water restrictions.
validating bounce-back – Part 2 As further validation of the model to predict bounce-back, a scenario was run in the Ballarat region using restrictions that were implemented in Horsham and Ararat, to determine if forecasts show a similar increase in water consumption as water restrictions are eased. Horsham and Ararat moved from Stage 4 to Stage 1 in October 2009, and observed a 35% and 28% increase in water consumption, respectively, between November 2009 and April 2010. Forecasts applying the same restrictions in Ballarat show a similar increase (34%) in water consumption as seen in Horsham and Ararat.
Evaluating Past Conservation Measures overview The CHW “forecasting” model was first used to retrospectively assess and quantify the effectiveness of past conservation measures that were implemented in the Ballarat region, including the Project Aquarius retro-fit program, Target 150, which provides households with feedback on their water usage compared with the target of 150L/p/d, and other influences from media and marketing communicating the severity of the water situation. The model was also used to assess past consumer behaviour and water demand in Ballarat (from July 2006 to June 2009) if particular water conservation measures had not been implemented. This allowed evaluation of the effectiveness of individual water conservation programs, using savings in water, energy, carbon and household bills as measures of effectiveness.
Quantifying Past Conservation Measures Results revealed that the Project Aquarius retro-fit program provided the greatest individual household savings (37.4KL), but provided the lowest overall regionwide savings (200ML over three years) as only a small proportion of households participated in the program. The greatest region-wide savings of 1.9GL over three years resulted from voluntary behaviour change of consumers in response to communications about the severity of the water situation. Feedback about water usage also contributed to 312ML of water savings, providing consumers greater awareness of their water usage.
Figure 2: Historical demand forecasts (red) versus actual demand (grey) in Bendigo.
The water conservation programs also provided energy and carbon savings by households, and thus provided savings to both their water and energy bills.
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demand in Ballarat based on different climate scenarios. Dry Scenario (KL) Three future scenarios in Ballarat were tested, from 2009 Figure 3: Forecasts for baseline, wet, and dry scenarios in KL/household/annum. to 2018, based on wet, normal (baseline) and dry reservoir inflow conditions. Associated with the different climate conditions, each scenario used different levels of drought increases in water storages, and social Figure 3: Forecasts for baseline, wet, Baseline and d(KL) ry scenarios restrictions, in KL/household/annum. Scenario (KL) Figure 3: Forecasts for baseline, wet, Wet influences from media and other communication and dry scenarios in KL/household/annum. Dry Scenario (KL) signals about the water situation. 60 40 20
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Figure 5 shows a forecast with the drier scenario, but with restrictions easing more quickly, similar to the baseline scenario. Forecasts show that although 0 120 20 restriction K levels are similar to the baseline, demand Figure 5 : F orecasts f or a d rier s cenario w ith l ow r estrictions L/household/annum. 0 100 is lower in the drier scenario. Therefore, results show Figure 80 5: Forecasts for a drier scenario with low restrictions that climate and social influences have a strong effect Figure 5: Forecasts for a drier scenario with low restrictions KL/household/annum. Drier: Low Restrictions 60 on moderating water consumption, regardless of KL/household/annum. Baseline 5: Forecasts for a drier scenario w ith low restrictions KL/household/annum. Figure restriction levels. 40 Scenario Price Rise Comparison - Annual WaterWetter Consumption Drier: High Restrictions 17020 The CHW forecasting model was also used to compare water consumption patterns between 0 Price Rise Comparison - Annual Water Consumption different demographic types, based on income, age, 170 160 Price Rise Comparison - Annual Water Consumption property tenancy, parental status and household 170 structure. For example, forecasts showed correlations 160 150 Figure 5: Forecasts for a drier scenario with low restrictions KL/household/annum. between high income and increased water consumption. 160 150 These results will be used to assist with targeted 140 marketing of future programs. 40 160 600
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behaviour change in the community and thus limited opportunity to further reduce consumption.
• Ability to understand and quantify the benefit of specific influences or strategies in a campaign;
Traditional economic approaches indicated a greater reduction in demand, but were unable to model the critical behavioural components that SimulAIt showed significantly affected the outcome, and thus fell short in accurately predicting consumption in this humancentric system.
• Identification of demand characteristics of different consumers (regions and demographics), to enable better targeting of future programs (micro-marketing);
Conclusion ISD’s agent-based SimulAIt consumer modelling and forecasting platform was used to create a highly detailed microsimulation of over 40,000 households in Ballarat. The model simulated individual people within households, how they made decisions in the house and garden, and how their decisions were influenced by different policies and communication signals, such as water restrictions, price increases, marketing campaigns and the media. The model integrated a wide range of qualitative and quantitative social, economic, environmental and political data. Extensive validation showed greater than 95% accuracy and tracked retrospectively the complex trends over eight years. Validation also showed that the model was transferable and could forecast bounce-back when applied to the Bendigo region. Future forecasts indicate that the “bounce-back” in water consumption from easing water restrictions is minimal, peaking below pre-restriction levels, due to water-saving behaviours of consumers being maintained as a result of the long period in which restrictions have been imposed. Forecasts also showed that demand is relatively insensitive to price increases. This is due to a high level of persistent behaviour change by consumers, and thus limited opportunity to further reduce consumption. Traditional economic analysis is unlikely to model these critical behavioural components, and thus fell short in accurately predicting consumption in this human-centric system. CHW received a range of benefits from the forecasting model, including: • Greater accuracy in sales and financial forecasts to inform short- and longterm plans; • More rigorous business case to industry pricing regulators; • Ability to assess and inform future water policies, programs and marketing;
• Greater understanding and quantification of the effectiveness and benefits of past programs and strategies; • Can better inform future conservation measures and policies.
Acknowledgements The authors would like to acknowledge the contribution of a wide range of people and agencies including the Victorian Department of Sustainability and Environment (DSE) for funding and support for the project. ISD acknowledges Central Highlands Water staff for assisting with data collection and providing feedback, as well as staff at Coliban Water, Yarra Valley Water, South East Water, City West Water and Barwon Water for data and knowledge provided. ISD also thanks Peter Guttmann, Helen Delaporte and Les Walker from DSE for providing useful insights and critical feedback.
the Authors
Berger T, 2001: Agent-based spatial models applied to agriculture: a simulation tool for technology diffusion, resource use changes and policy analysis. Agricultural Economics 25 (2001), pp. 245–260. Bonabeau E, 2002: Predicting the unpredictable. Harvard Business Review, March 2002. Dietz T, Gardner GT, Gilligan J, Stern PC & Vandenbergh MP, 2009: Proceedings of the National Academy of Sciences (PNAS), November 3, 2009. Farmer JD & Foley D, 2009: The economy needs agent-based modelling. Nature, Vol. 460, 6 August 2009. Janssen MA & Jager W, 2001: Fashion, habits and changing preferences: Simulation of psychological factors affecting market dynamics. Journal of Economic Psychology 22 (2001), pp. 745–772. Markose S, Arifovic J & Sunder S, 2007: Advances in experimental and agent-based modelling: Asset markets, economics networks, computational mechanism design and evolutionary game dynamics. Editorial, Journal of Economic Dynamics & Control 31 (2007), pp. 1801–1807. North MJ, Macal CM, Aubin J St. et al., 2010: Multi-scale agent-based consumer market modelling. Complexity Vol. 15, Issue 5, May/ June 2010, pp. 37–47. Nuttal WJ, Zhang T, Hamilton DJ & Roques FA, 2009: Second International Symposium on Engineering Systems, MIT, Cambridge, Massachusetts, June 15–17, 2009. Perugini D, Perugini M & Young M, 2008: Water Saving Incentives: an Agent-Based Simulation Approach to Urban Water Trading. SimTecT 08, Melbourne.
Dr Don Perugini (email: donperugini@ intelligentsoftware.com.au) has a PhD in Software Engineering and Computer Science from the University of Melbourne and spent 11 years at the Defence Science and Technology Organisation. He is the Managing Director and one of the founders (along with Dr Michelle Perugini) of Intelligent Software Development (ISD), Adelaide SA.
Rixon A, Moglia M & Burn S, 2007: Exploring
Brendon Clarke is the Coordinator of Demand Management and John Frdelja is a hydrogeologist at Central Highlands Water (CHW), Ballarat VIC.
modelling of customer behaviour in the
water conservation behaviour through participatory agent based modelling. Topics on Systems Analysis for Integrated Water Resource Management. Elsevier. Schenk TA, Loffler G, Rauh, Jurgen, 2007: Agent-based simulation of consumer behaviour in grocery shopping on a regional level. Journal of Business Research 60 (2007), pp. 894–903. Twomey P & Cadman R, 2002: Agent-based telecoms and media markets. Info Journal, 4, 1, 2002, pp. 56–63. Willis R, Stewart RA, Talebpour MR, Mousavinejad
references
A, Jones S & Giurco D, 2009: Revealing
ABS Census Data, 2006: Australian Bureau of Statistics.
and efficient devices on end use water
Athanasiadis IN, Vartalas P & Mitkas PA, 2004: DAWN: A platform for evaluating water-pricing policies using a software agent society. International Environmental Modelling and Software Society 2004 International Congress. Complexity and Integrated Resources Management, p. 42. iEMSs.
the impact of socio-demographic factors consumption: Case of Gold Coast, Australia. 5th IWA Specialist Conference on Efficient Use and Management of Urban Water. Zhang T & Zhang D, 2007: Agent-based simulation of consumer purchase decisionmaking and the decoy effect. Journal of Business Research 60 (2007), pp. 912–922.
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BIoSolIdS PRoceSS oPtImISAtIon At Sydney’S noRth heAd StP Recuperative thickening increases solids throughput S Ireland Abstract The biosolids process at North Head was reviewed in late 2009. Recuperative thickening was identified as a process operation that could be implemented using existing assets for very little investment. Recuperative thickening involves removing sludge from the digesters and thickening by Rotary Drum Thickeners (RDTs), thereby removing water before returning the thickened sludge back to the digesters. The process increases digester solids content and increases effective capacity for increased solids retention. A recuperative thickening trial was conducted throughout the first half of 2010 to collect operational data and assess its potential and impacts on the plant. Project results demonstrate reduced process bottlenecks, reduced solids recycles, increased raw sludge withdrawal volumes and process flexibility.
Introduction
North Head STP is the second largest STP in Sydney, treating 340ML/day from over one million residents in the north and west of Sydney. It is a high rate primary treatment plant that discharges effluent through a 3.5km Deep Ocean Outfall. Head of works
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A lime stabilisation plant was decommissioned and replaced with a new biosolids treatment facility in 2009. It incorporates the following unit processes: • Raw (primary) sludge withdrawal from primary sedimentation tanks (PSTs); • Raw sludge screening and de-gritting; • Raw sludge thickening; • Anaerobic digestion; • Biogas storage; • Biogas cogen plant; • High G centrifuge dewatering. Figure 1 shows the unit processes of the plant. Upon start-up of the new biosolids facility, it became apparent that the plant hydraulically performed differently from the design. An investigation determined the main contributing factors to be: • Overflows from the post-digestion tank, resulting in high solids recycling; • Impact of the above on higher solids inventory than the process was designed for; • Reduced digester solid retention time (SRT) as a result of processing more sludge than anticipated.
A technical review of the plant’s solids processing stream by Sinclair Knight Merz (SKM) in early 2010 proposed a recuperative thickening process as a means of relieving some of the existing process constraints. Recuperative thickening was previously implemented at Bondi STP with successful outcomes (Tang, 2009). Recuperative thickening is a closed loop sludge recycle that mechanically removes excess water from the digesters, effectively increasing digester capacity and solids retention time. The recuperative thickening circuit is illustrated in the modified process flow diagram (Figure 2). There are three mesophilic anaerobic digesters at North Head. Two operate as primary digesters, and the third digester as a secondary. Recuperative thickening draws digested sludge from the secondary digester, thickens this sludge and returns it to the primary digesters. The process uses existing technology in a novel way, which has only been utilised at a few full scale plants around the world. This paper demonstrates how recuperative thickening can be used to process higher raw sludge volumes, improve digestion and provide process flexibility. This paper will be of particular interest for plants with limiting digestion capacity.
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Figure 2: Process flow diagram with recuperative thickening circuit.
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The next stage of the project will involve SCADA modifications to enable continuous automatic operation and extended digester performance monitoring.
Process dynamics The sludge processing dynamics at North Head are unique in that the hydraulic throughput is limited by the digestion capacity and the degree of pre-thickening. Most plants operate as a “push-system”, whereby raw sludge is pushed from the PSTs to the biosolids process. In this situation, the sludge withdrawal is a function of efficient sludge consolidation matching solids inventory. North Head is unusual in that it is a “pull-system”. Due to limited digester capacity, the mass of solids processed is dictated by the hydraulic retention time. The digester feed operates by transferring a nominated volume of thickened sludge to the digester every hour. This intermittent feed regime results in the upstream processes stopping in a cascade effect as intermediate buffer tanks become full. Ultimately the raw sludge withdrawal process is inhibited from operating until the impact of the next digester feed cycle makes available head space in the tanks. During the construction phase of the Biosolids project and other site construction works, the effluent suspended solids concentration limit was relaxed under North Head’s Environmental Protection Licence (EPL) to the 50th percentile concentration limit of 250mg/L. The average suspended solids concentration in the early part of 2010 was 206mg/L, but by late 2010 with all site works complete this limit was returned to the original 200mg/L. The biosolids facility was designed to handle 36.7 dT/d of raw sludge; however it was determined that approximately 43.8 dT/d was actually being processed. A review of each unit process that makes up the biosolids facility revealed that about 5.5 dT/d of solids were being returned to head of works as solids recycles from RDT filtrate, centrifuge centrate and buffer tank overflows. The post-digestion buffer tank had been overflowing almost continuously since late 2009 due to reduced centrifuging capacity to match an undersized biosolids conveyor capacity. The buffer tank overflows alone were estimated to be 2.6 dT/d. Sydney Water is currently in the process of replacing these conveyors, which will
Table 1: Comparison of RDT operating parameters. Parameters
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mitigate the current tank overflows. In the meantime, recuperative thickening can mitigate the post-digestion tank overflow by providing an alternative path for digested sludge. Recuperative thickening causes the digester solids retention time (SRT) to become greater than the hydraulic retention time (HRT). This is because water leaves the system through RDT filtrate, while the solids remain in the system.
Rdt and trial Integration The Alfa Laval RDT units installed at North Head operate by passing conditioned sludge through a slowly rotating drum of filter cloth. The sludge remains inside the drum, while free-draining water passes through the filter cloth and is drained away. Polymer is used to enhance sludge flocculation and solids capture. SKM’s 2010 Biosolids Investigations revealed equipment redundancy in the four RDTs installed for raw sludge thickening. This meant that there was both capacity and the required equipment already installed to operate one of the RDTs in a recuperative thickening mode with only minor pipework modifications. Endorsement to conduct a trial was given with the first stage of the recuperative thickening trial, requiring installation of temporary pipework to verify the required hydraulic circuit. This enabled one of the four raw sludge thickeners to be operated in a recuperative thickening mode. The intent of this first stage was to collect operational data for process modelling and predicted performance outcomes to both digestion and the other unit processes. The initial recuperative thickening trial required manual operation for 5–6 hours a day. During this time, the volumetric feed rate to the digesters was varied, to establish the hydraulic implications of the process.
Rdt operating Parameters Due to differences in the properties of raw and digested sludge, the operating parameters for the RDTs servicing each sludge were different, as shown in Table 1, above. The RDTs’ operating parameters for raw sludge thickening are dynamic, as they are controlled by a feedback loop from an inline density meter aiming to achieve a target 6% thickened sludge output. For example, if the density is lower than the set point, the RDT will operate at a lower feed rate and faster drum speed in order to increase thickened sludge solids concentration out of the RDT. The operating parameters for the recuperative thickening RDT are fixed and were determined by optimisation given that the feed sludge from digestion is near constant in solids content.
Results on System dynamics One of the consequences of the “pullsystem” dynamic at North Head is that the digesters are fed in batches each hour. The digesters cannot be fed continuously because this would reduce solids retention time to a point that would risk digester stability. The digesters are not fed for around 20 minutes in every hour. When the digester feed has reached its volume set point for the hour, the feed pump will stop for up to 20 minutes until the next hourly cycle starts. This feed sequence pause causes: • The post-thickening tank to fill, reaching high level interlock; this shuts down the operating RDTs; • With no RDT processing the prethickening tank fills, reaching high level interlock; this shuts down the raw sludge withdrawal sequence.
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This cascade effect stops the raw sludge withdrawal for around 25 minutes in every hour, restricting the capacity to remove solids from the influent. Therefore, to increase the mass of raw sludge withdrawal, the volume fed to the digesters each hour must be increased or the sludge further thickened. Thickening the sludge to 6% TSR was considered the limit to mitigate high pressure pumping and impacts on digester mixing.
30 /0
6/ 2/ 10 07 / 4/ 10 07 / 6/ 10 07 / 8/ 10 07 10 /10 /0 7 12 /10 /0 7 14 /10 /0 7 16 /10 /0 7/ 10
Total digester capacity (m 3)
6/ 30 /2 0 7/ 10 2/ 20 7/ 10 4/ 20 7/ 10 6/ 20 7/ 10 8/ 2 7/ 010 10 /2 7/ 01 12 0 /2 7/ 01 14 0 /2 7/ 01 16 0 /2 01 0
Raw sludge withdrawal (dT/day)
digester feed Table 2: Digester parameters. rate has led to Parameters Design Actual reduced SRT in the digesters. With the Feed solids content 6.0% 5.5% implementation 3 12.4 16.0 Volumetric feed rate (m /h per digester) of recuperative SRT (days) 20.0 15.8 thickening, the removal of excess was observed that the raw sludge pumps water from the stop due to high downstream tank level digesters has effectively increased digester capacity. Figure 4 shows the only four minutes every hour, instead of effective change in digester capacity 25 minutes an hour with no recuperative as a result of running the process. thickening. This reduces the sludge Monitoring of raw sludge withdrawal inventory in the PST’s sludge hopper, volumes over the recuperative thickening operational flexibility reducing the risk of sludge rafting and trial has demonstrated the ability of The above discussion of raw sludge solids passing through to effluent. This this process to increase raw sludge withdrawal and digester performance benefit was seen in a gradual reduction withdrawal (see Figure 3). illustrates that without recuperative in raw sludge TSR over a few successive thickening, the operating range for days of operation. 60.0 digester feed is restricted. Assuming 50.0 In the “maximise digestion” scenario, a minimum SRT of 15.8 days this 40.0 operating range is only 14.5–16m3/h recuperative thickening improved 30.0 per digester. Increasing this set point digestion by increasing digester SRT. 20.0 10.0 would lead to very low HRT/SRT in This increases the solids concentration 0.0 the digester. Conversely, reducing this within the digester and reduces the set point would increase HRT/SRT but hydraulic volume leaving the digesters to would further throttle the hydraulic dewatering. This reduced hydraulic load capacity of raw sludge withdrawn, Date has a significant advantage of enabling Extra raw sludge withdrawn as a result of which would likely result in high effluent the throughput of the centrifuge to draw recuperative thic kening suspended solids carryover and possible Raw sludge withdrawal had recuperative down the post-digestion tank level, thus thickening not run breach of licence conditions. mitigating overflows and solids recycling. Figure 3: Raw sludge withdrawal. Figure 3: Raw sludge withdrawal. Recuperative thickening was trialled Recuperative thickening accounts Because the digester TSR increases, as a way to increase the available Recuperative thickening accounts for increases of 2% to 26% in daily raw sludge withdrawal, for increases of 2% to 26% in daily raw so too does the TSR of the dewatering depending on hours of operation. By running the process continuously for 20 hours on 17/7/10, a capacity of the digesters to provide 26% increase in raw sludge withdrawal was observed (54.3 dT/d, as opposed to the 43.0 dT/d sludge withdrawal, depending on hours feed. The combination of reduced in excess of the required 20 days SRT, predicted had recuperative thickening not run). hydraulic load and increased centrifuge of operation. By running the process thus providing process flexibility. To [mini x‐head] continuously for 20 hours on 17/7/10, feed solids is expected to lead to determine process implications a mass Digester performance a 26% increase in raw sludge withdrawal reduced centrifuge operating time and Table 2 shows how the digesters have been operated differently from the design specification. balance was prepared with the following was observed (54.3 dT/d, as opposed to improved operation. Manual operation operating scenarios: Parameters Design Actual the 43.0 dT/d predicted had recuperative of recuperative thickening for just seven Feed solids content 6.0% 5.5% • Design model: Raw sludge withdrawal Volumetric feed rate (m3/h per 16.0 hours per day reduced the sludge volume thickening not run). 12.4 digester) as predicted during plant design; transferred from digester to dewatering SRT (days) 20.0 15.8 digester performance and stopped the post-digestion tank • Current practise: the way the plant Table 2: Digester parameters. Table 2 shows how the digesters have is actually run without recuperative overflow for up 10 hours. To process the increased solids inventory in the PSTs, the digester feed rate was increased. This thickening; been operated differently from the design The centrifuge normally runs increased digester feed rate has led to reduced SRT in the digesters. With the implementation of specifications. recuperative thickening, the removal of excess water from the digesters has effectively increased • Maximise raw sludge withdrawal: 24 hours a day, however, while digester capacity. Figure 4 shows the effective change in digester capacity as a result of running the running recuperative thickening so To process the increased solids recuperative thickening the centrifuge process. that SRT is unchanged from current inventory in the PSTs, the digester feed shut down on low tank level for up to practise; 6.5 hours, a saving on both energy and rate was increased. This increased polymer costs. After two weeks of daily • Maximise digestion: running 13700 recuperative thickening operation, one recuperative thickening so that raw 13600 less biosolids truck was needed. This sludge withdrawal is unchanged from 13500 could represent significant long-term current practise. 13400 cost savings and environmental benefits. Some of the parameters from the 13300 mass balance are presented in Table 3 With recuperative thickening, the 13200 (see overleaf). digester feed operating set point is 13100 no longer restricted to a batch feed In the “maximise raw sludge 13000 of 14.5–16m3/h/dig (min. 15.8 days withdrawal” model, recuperative SRT=HRT). Now it can be increased thickening removed excess water from to 23-29m3/h/dig (SRT≠HRT). A wider the digesters creating headspace within Date operating range means the plant will the digester. This headspace allows higher Extra capacity generated by recuperative thickening be better equipped to cope with digester feed rates, which has the flow-on Digester capacity without recuperative thickening changes in solids inventory and effect of larger volumes of raw sludge to Figure 4: Digester capacity. digester performance. be withdrawn from PSTs. During the trial it
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Sydney Water is currently in the process of automating the recuperative thickening circuit for continuous operation to allow extended performance evaluation of the process and impacts on sludge digestion.
Future Improvements When the recuperative thickening circuit is automated, consideration will be given to the volume of the batch feed. By operating in the middle of the calculated operating range, the process can be used to benefit both effluent quality and the digestion process. Extended operation of recuperative thickening in this regime is expected to yield the following benefits: • Improved effluent quality: Withdrawing a greater mass of raw sludge reduces the mass of solids remaining in the effluent stream; • Greater VS destruction: Longer SRT leads to more complete digestion, as there is more time to convert solids into biogas. Reduced VS content in sludge could also reduce biosolids odour; • Increased biogas production: This increases the plant’s electricity production from the cogen engine
• Reduced sludge volume and solids mass to dewatering: This could reduce the daily run time of the centrifuge, saving power and polymer (the centrifuges and outloading system use more power than the RDTs);
This paper was awarded best paper at the AWA National Operations Conference, September, 2010.
Acknowledgements
• Increased dewatered cake TSR and decreased cake volume: This leads to cost savings and environmental benefits, as fewer truck movements are required to transport the biosolids cake.
The author wishes to thank the following colleagues: Andrew Ryan – Senior Mechanical Engineer, Sinclair Knight Merz, and John Tang – Production Officer, Bondi STP; also the plant operations team at North Head, in particular Michael Pinteric, Stuart McFarland and Prianta Kariawasam.
conclusion
the Author
The first stage of the recuperative thickening trial has demonstrated the benefits of the recuperative thickening process beyond improving digestion. These include removing process bottlenecks, reducing solids recycles, increased raw sludge withdrawal volumes and process flexibility. When the process is automated, continuous operation is expected to yield further benefits such as improved effluent quality, potentially more biogas production and lower biosolids odour and more efficient centrifuge operation.
Susan Ireland (email: susan.ireland@ sydneywater.com.au) is a Production Officer at Sydney Water’s North Head Wastewater Treatment Plant.
References Tang J, 2009: ‘Benefits of Recuperative Thickening at Bondi STP’, National Operations Conference.
Table 3: Plant performance data. Design model
Current practise (no recuperative thickening)
Maximise raw sludge withdrawal (with recuperative thickening)
Maximise digestion (with recuperative thickening)
Total raw sludge withdrawal (dT/day)
36.7
43.8
67.7
43.8
Raw sludge TSR (%)
2.8
3.5
3.0
3.5
Post-digestion tank overflow (dT/day)
0
2.6
1.8
0
Total solids recycles (dT/day)
1.9
5.5
6.7
4.2
Net raw sludge withdrawal (dT/day)
34.8
38.3
61.1
39.6
0
0
65
4
Digester SRT (days)
20.0
15.8
15.8
24.9
Digester HRT (days)
20.0
15.8
10.2
15.8
Scenario
Predicted improvement in effluent quality (mg/L)
Digester TSR (%)
3.24
2.22
2.22
3.49
Combined feed to digester (m3/h per digester)
12.4
15.7
29.4
23.7
Raw sludge feed to digester (dT/day)
35.8
41.6
64.3
41.6
Feed to recuperative thickener (kL/day)
0
0
691
691
Thickened digested sludge feed (kL/day)
0
0
243
381
Digested: raw sludge ratio in digester feed
0
0
2:9
5:9
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MAY 2011 89
biosolids
refereed paper
BiocHemicAL TReATmenT of BioSoLiDS – emeRGinG TecHnoLoGieS
Pre-treatment methods such as biological processes can improve performance economically DJ Batstone, PD Jensen, H Ge Abstract
Biosolids Source, Production Levels and Reuse
Changes in wastewater treatment design, with longer sludge ages, mean that waste solids streams are becoming more difficult to stabilise by conventional anaerobic processes. In this article, we focus on a variety of pre-treatment methods that can improve anaerobic digestion performance, either by increased speed of degradation, or by an increase in ultimate degradability.
The major solids streams produced by wastewater treatment plants are primary sludge (separated by the primary clarifiers), and excess waste activated sludge (WAS) (separated in the secondary clarifiers). The average production of dry solids is 50–65 grams per person, per day (Hudson 1995). A community of 50,000 persons will, therefore, produce 2.5 dry tonnes of biosolids per day, or approximately 20 wet tonnes per day (one truckload). This depends heavily on biosolids handling methods and wastewater process design, rather than upstream consumer habits (in contrast with total sewer flows).
In particular, we focus on biological pre-treatment (acid-phase and temperature), which mainly improves the speed of degradation. This can result in a substantial increase in gas production and an increase in VS destruction from 30%–45% depending on the main digester retention time. We also show that it is important to assess how pre-treatment affects the final solids, as this can determine the ultimate performance.
Biosolids handling is expensive and represents 25%–50% of total wastewater treatment plant costs (Murthy, Higgins et al., 2006). Costs are heavily related to final
handling costs (mainly transport), and are (as of 2011 in Australia) in the order of $35–$70 per wet tonne depending on the distance for final application. This is complicated in Australia by the fact that our activated sludges are inherently difficult to dewater, possibly related to inert solids and/or a higher bound water fraction (Novak, 2006). In the last 15 years, the focus of wastewater treatment has shifted more towards nitrogen removal, with a concurrent increase in sludge ages. This has had the following major impacts: • Removal of the primary sedimentation processes, or use of sludge prefermenters, as the carbon is needed for nutrient removal. • Decrease in overall biosolids amounts, due to long sludge ages and loss of the primary stream, though the secondary sludge production normally increases due to increased carbon turnover.
Table 1: Treatment options available in different wastewater treatment plant sizes. Stability Class
Type
Product Quality
Electrical Use (kWh/tonne at 13% dry solids)
Notes
Treatment – applicable at all sizes A or B4
++
400–8001
Increases dry solids 50%. Causes high pH solids.
Composting
A
+++
100
High labour requirements. Increases dry solids 50%. Needs additional dry material.
Aerobic digestion
B
-/+
50
25 days
Lime stabilisation
Treatment – applicable at larger scale Anaerobic digestion 30°C─40°C Anaerobic digestion with pre-treatment
Sludge age ~15 days. Co-generation gas available.
B
+
-35
A/B
++
-25 to -50 Post-treatment – applicable at all sizes
Solar drying
2
Thermal drying
2
A/B
+++
30
A
+++
1000
Based on continuous turning process. 3
Including electrical cost of lime production. Upper level (and Class A) includes heat treatment. 2 kWh per tonne water evaporated. 3 If gas is used, emissions are equivalent to 200kWh as electricity. 4 Class A (P1) is pathogen-free. Class B (P2) is stabilised biologically but may contain residual pathogens. 1
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• Even poorer sludge dewaterability due to loss of the primary stream. • Decrease in biosolids degradability, both because of long sludge ages and loss of the primary stream. There is a strong case for beneficial reuse of biosolids in Australia. The use of biosolids in agriculture across Australia is being extensively researched by the National Biosolids Research Program (NBRP). Use of biosolids has been generally found to have either the same or a positive benefit compared to use of mineral fertilisers at comparable nitrogen loading rates (Warne, McLaughlin et al., 2009). This is becoming even more important as the value of nutrients and energy rises. Our calculations have indicated that as of 2011, 1 tonne of wet biosolids (12% solids) has a value of $17, evenly divided between nutrient value (N & P) and energy. The value of bound water is $1 per tonne. Unfortunately, this is minimal compared with transport costs of >$30 per tonne, and is even marginal compared with basic agricultural spreading costs of approximately $10 per tonne.
Biosolids Stabilisation Processes Stabilised biosolids products that meet legislative requirements for agricultural use can be produced using a wide range of technologies. A summary of treatment processes and the different product qualities are shown in Table 1. They are split into technologies applicable at all sizes, technologies applicable at large scale only, and technologies that could be applied as either stand-alone or additional treatment options to the previous methods. All small-medium scale options are also available in large scale, but may have undesirable social impacts (e.g., open composting in large scale causes odour problems). While anaerobic digestion compares favourably with alternative treatment options shown in Table 1, it is considered as only being applicable at large scale. The reduction in highly degradable primary sludge streams, and the increase in poorly degradable waste-activated sludge streams, reduce the feasibility of conventional anaerobic digestion at modern N-removal wastewater treatment plants. At large scale this has been addressed through the development of advanced anaerobic technologies (e.g. thermal hydrolysis). However, these advances are currently impractical in smallmedium scale systems for reasons such as: • Although civil construction costs scale reasonably well for anaerobic digestion,
mechanical and electrical (e.g., flare, pumps, gas circulation system, gas storage, heating system) become proportionally much more expensive at smaller scale. • Smaller scale systems are more likely to be designed to operate at longer sludge ages, to provide for a more robust process (needing less attention) and reduce sludge production levels. • Process intensification (e.g., thermal pre-treatment) is capital intensive and can realistically only be applied in centralised (or very large scale) facilities. • Conventional internal combustion combined heat and power (CHP) cogeneration engines have a minimum size of approximately 250–500kW and cannot effectively operate at below 70% capacity. This means a system producing secondary sludge only would need a minimum of 100–200 tonnes per day at 12% solids. Loss of renewable energy as a product stream removes one of the motivations for anaerobic digestion.
Figure 1: Degradability vs. upstream sludge age, based on (Gossett & Belser, 1982) modified for Australian conditions. of pre-treatment methods has increased significantly in the last 10 years, though most are new variations on older themes. Pre-treatment methods for anaerobic processes have been recently reviewed (Carrère, Dumas et al., 2010), and will be briefly summarised here.
The current default treatment method for biosolids at small-medium scale is aerobic digestion, which produces a product with higher odour potential, and lower overall stability. Biosolids treated using anaerobic digestion have a lower odour potential. This is because anaerobic digestion effectively destroys volatile sulphur compounds present in biosolids (Murthy, Higgins et al., 2006).
All pre-treatment methods attempt to enhance the first stage of anaerobic digestion by a variety of mechanisms, including chemical/thermal solubilisation, lysis and particle size reduction. The net effect is to either increase the rate or extent of degradation, such that specific gas production and VS destruction are improved. Note that these are inherently linked, and claims of an increase in one without a corresponding increase in the other should be regarded with scepticism. An increase in VS destruction should also result in an improvement in ‘dewaterability’ (Novak 2006) and better mixing characteristics, reducing costs.
emergence of Pre-treatment options for Anaerobic Digestion
Pre-treatment methods can be divided into four key types:
As already stated, the movement towards enhanced biological nutrient removal and production of activated sludge rather than primary sludge has reduced degradability. There is a direct relationship between WAS sludge age and degradability (see Figure 1). WAS with an age of >15 days has poor degradability and, if applied to anaerobic digestion, is likely to result in a failed process, not producing enough energy to meet heating requirements, and requiring excessive mixing energy due to poor gas mixing and rheological characteristics.
1. mechanical pre-treatment: These can include sonication, impact plate, homogenisation, grinding and lysis-centrifuge. Particularly, sonication is well represented in both commercial applications and in research articles (see Carrère et al., 2010 for further details). In full-scale implementation, energy input is normally of the order of 30kWh.m-3 treated, with moderate (+10%) increases in final VS destruction.
This has decreased the applicability of anaerobic digestion, which is the leading practical method to achieve net energy generation, while producing a high-quality final product. To enhance applicability of anaerobic digestion, pre-treatment methods are often applied, to increase the speed of degradation (hence allowing intensification) and/or increase the ultimate extent of degradation. The range
2. Biological pre-treatment: There is a wide range of processes which use a biological agent, but most use a shortterm biological process (~2 day) prior to the main mesophilic digestion stage. This may involve higher temperature (temperature phased anaerobic digestion), or lower pH (acid-phase or enzymic digestion) that attempt to enhance the hydrolytic stage of anaerobic digestion. Performance is also further discussed overleaf, but improvements are similar to mechanical pre-treatment.
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pre-treatment process that just increases rate could be substituted by a larger main digester (though with increased mixing energy and other issues). In general, high intensity processes such as thermal hydrolysis will increase both rate and extent, while low intensity processes such as mechanical or biological will just increase rate. This, however, can have a massive impact on eventual performance.
Figure 2: Comparison of biogas production rates over a 24-hour period from a TPAD process comparing thermophilic-mesophilic and mesophilic-mesophilic processes (Ge, Jensen et al., 2010). 3. chemical pre-treatment: This involves chemical addition, normally acids or bases, but also possibly ozone, peroxide or other oxidants to enhance hydrolysis rates. Chemical pre-treatment methods have declined in popularity due to the high cost of chemicals, and potential environmental and product impacts. 4. Thermal pre-treatment or thermal hydrolysis (TPAD): Note that this does not include low temperature pretreatment, which is classed as biological. This involves heating the sludge stream to a high temperature (>140°C) with very good results. In particular, material with poor degradability (<30%) can be enhanced to a very degradable material (>55%)) (Batstone, Tait et al., 2009). However, it is capital intensive, and has additional operational requirements due to the use of 6 bar steam.
a similar concept, although interestingly, our work has found that depressed pH has a strong negative impact on final degradability, and indeed it is better to operate a pre-treatment stage at neutral pH (Ge, Jensen et al., 2010; Ge, Jensen et al., 2011).
Degradability Rate vs extent – Performance in Real Systems One aspect that has so far received very little attention in evaluations is whether the rate or extent of degradation is improved. That is, is more food made available to the microbial community through chemical changes, or is the existing food just made easier to digest? This is an important concept, since a
This is demonstrated in Figure 3, which shows expected digester performance (validated against continuous digesters) for different TPAD pre-treatment conditions. TPAD has a much stronger impact on rate (represented in khyd) than on degradability extent. As can be seen, TPAD can increase digester performance at 15 days retention time from 30% VS destruction with no pre-treatment to 45% VS destruction with 65°C pre-treatment. The impact of pre-treatment is to flatten out the performance curve and hence make it less dependent on digester hydraulic retention time. To fully assess this, however, requires either copious continuous digester performance data, or conducting biochemical methane potential tests, which is a conservative test that can identify both speed and extent (Ge, Jensen et al., 2011).
conclusion While the changing paradigm of nutrient removal in wastewater treatment design goals has made it more challenging to apply sustainable sludge digestion
Biological pre-treatment (2) is emerging as a lead contender for low intensity applications, especially due to its low capital cost, use of low grade heat energy in the first stage, and ability (with elevated temperatures) to produce a Class A sludge. This pre-treatment option makes anaerobic digestion more applicable at smaller scale, as smallscale heaters and vessels can be used, and the improvement in performance is sufficient to operate on material with poorer degradability. Performance has been largely related to an increase in degradation rate, rather than extent (Ge, Jensen et al., 2010), but can still result in substantial improvements in performance. For example, Figure 3 shows a 20% increase in biogas production rates over a 24-hour period from TPAD processes using thermophilic pre-treatment and mesophilic pre-treatment (representative of conventional anaerobic digestion). Enzymic or acid phase digestion employs
92 MAY 2011 water
Figure 3: Performance curves for performance vs. hydraulic retention time (HRT) in continuous feed-mixed conventional digesters fed with different materials, including untreated WAS, primary sludge (PS) and primary sludge pre-treated at different conditions (2 day HRT 50°C-70°C). Pre-treatment has a strong impact on rate (khyd), but less on extent (fd). TP = thermophilic pre-treatment; MP = mesophilic pre-treatment.
technical features
biosolids
refereed paper
processes such as anaerobic digestion at smaller scale, emerging pre-treatment methods such as biological processes can improve performance again to acceptable levels, while providing other benefits such as hygenisation and quality improvements. It is important to consider the way that the pre-treatment method fundamentally changes material properties, in particular whether it changes biochemical conversion speed, or ultimate extent. This can be used to assess design of downstream processes and inform expected performance under a wide range of possible future conditions.
Acknowledgements Our research into biological pre-treatment was funded by the Queensland State Government under the Smart State Research-Industry Partnerships Program (RIPP), Meat and Livestock Australia and Environmental Biotechnology Cooperative Research Centre (EBCRC), Australia as P23 “Small-medium scale organic solids stabilisation”. Huoqing Ge and Paul Jensen are recipients of an EBCRC postgraduate scholarship and postdoctoral award, respectively.
The Authors Damien Batstone (email: damienb@awmc. uq.edu.au) is an Australian Research Fellow at the Advanced Water Management Centre, and is joint leader of the Anaerobic Biotechnology research group. Paul Jensen is an EBCRC research fellow and is joint leader of the biosolids research program at the Advanced Water Management Centre. Huoqing Ge has recently completed her PhD in biological pre-treatment, and particularly the impact of temperature and other factors on digester performance.
References Batstone DJ, Tait S & Starrenburg D, 2009: Estimation of Hydrolysis Parameters in FullScale Anerobic Digesters. Biotechnology and Bioengineering 102(5): pp. 1513-1520. Carrère H, Dumas C, Battimelli A, Batstone DJ, Delgenès JP, Steyer JP & Ferrer I, 2010: Pretreatment methods to improve sludge anaerobic degradability: A review. Journal of Hazardous Materials 183(1-3): pp. 1-15. Ge H, Jensen PD & Batstone DJ, 2010: Pretreatment mechanisms during thermophilic-
mesophilic temperature phased anaerobic digestion of primary sludge. Water Research 44(1): pp. 123-130. Ge H, Jensen PD & Batstone DJ, 2011: Increased temperature in the thermophilic stage in temperature phased anaerobic digestion (TPAD) improves degradability of waste activated sludge. Journal of Hazardous Materials 187(1-3): pp. 355-361. Gossett J & Belser R, 1982: Anaerobic digestion of waste activated sludge. Journal of Environmental Engineering ASCE 108: pp. 1101-1120. Hudson JA, 1995: Treatment and Disposal of Sewage-Sludge in the Mid-1990s. Journal of the Chartered Institution of Water and Environmental Management 9: pp. 93-100. Murthy S, Higgins M, Chen YC, Peot C & Toffey W, 2006: High-solids centrifuge is a boon and a curse for managing anaerobically digested biosolids. Water Science & Technology 53: pp. 245-253. Novak JT, 2006. Dewatering of sewage sludge. Drying Technology 24(10): pp. 1257-1262. Warne M, McLaughlin M, Heemsbergen D, Bell M, Broos K, Whatmuff M, Barry G, Nash D, Pritchard D, Stevens D, Pu G & Butler C, 2009: Draft Position Paper Recommendations of the Australian National Biosolids Research Program on Biosolids Guidelines.
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MAY 2011 93
resource recovery
refereed paper
CogeneRAtIon PotentIAl FRoM the AnAeRoBIC DIgestIon oF sluDge
Modelling the influence of various parameters
ture of operation (Chae et al., 2008), presence/absence of pre-‐ WPF Barber of pre-‐treatment; flare; and biogas arasitic energy requirements injection tAbstract o grid. The revised gas production plant data performance is put forward to an and bacteriological kinetics, set up to predict the influence ery section This of tpaper he mhighlights odel which then calculates power generation based the results of a number of parameters on the model whichhpredicts potential tion using of a caombined eat and power plant (generation CHP). The model of biogas and ultimately renewable energy generation from renewable energy. e heat required b y t he d igestion p lant a nd c ompares i t t o t he h eat sewage sludge based on a number of Sludgeetype was theamost m the CHP. variables. If deficient, ither the dditional eMethods nergy required to heat the influential parameter of those tested, nt is calculated or a revised energy generation is determined if biogas The backbone of the model was originally with primary sludge generating over ed. Heat requirements or the plant take into derived account ny diversion of fromacorrelations developed twice the energy fof secondary sludge. from data from a number of anaerobic As the type and quantity of sludge m CHP, e.g. to a gas supplier, therefore it is possible to determine the digestion plants worldwide and has been produced is fundamentally influenced version before fuel is required the digesters. presented previously (Barber, 2005a). by theauxiliary wastewater treatment process,to heat
The model used these correlations to it is suggested that they be looked at predict volatile solids destruction against in combination in order to maximise a number of variables including: sludge synergism. Pre-treatment technology ditions and highly efficient co-generation were quantity and type; digester retention time, dimensions; material of construction; the next most beneficial factors. conditions for the study are summarised in Figure 1. For anaerobic temperature of operation, etc. The operating tIntroduction emperature of 35°C (typical of mesophilic peration) has figure for destructionorate yields a basic biogas production. The previous d. In addition, time of 16 ays has been used with a void (or work Plantsretention for anaerobic digestion of d sewage been updated here to include more sludge haveis been traditionally designed of 20%. Void space that within the digester has which is unavailable and factors which influence energy generation. to reduce the levels of harmful bacteria,
o hydrodynamics r inert ofmsludge aterial r both. sludge type and odour andoquantity to o enable it The The biogas production is now further be stored or used fas ‘biosolids’. has been btoased on typical igures and Biogas wastewater reatment altered tdepending on hydraulic retention was of secondary importance. With the time using kinetic models presented by . With respect t o t he C ombined H eat a nd P ower p lant ( CHP), the drive towards a low carbon economy, the Tong and McCarty (1991) and temperature mes that the plant is available for use 85% of ofthe time, and that energy value of energy recovery has assumed operation (Chae et al., 2008), presence/ greater importance and new designs as he plant is converted to electricity and heat aabsence t a rate f 33% and parasitic 45% energy ofopre-treatment; well as operation of established plants are requirements of pre-treatment; flare; and All the baseline c onditions w ere a ltered a s v ariables t o d etermine their targeted at greater recovery of methane. biogas bypassing for injection to grid. The der these conditions, 10,000 per agas nnum generate revised production data is put forward This paper presents thetonnes outputs d ofry a solids to an energy recovery section of the model electricity (mathematical MWe). model based on both actual HRT (days): Dead Space: H:W ratio: Temperature:
16 20% 1.2:1 35¡ C
Availability: 85% Electrical conversion: 33% Heat conversion: 45%
Anaerobic Digestion TDSA: DS%: VS%: Primary: Secondary:
10,000 5% 75% 60% 40%
CHP
Sludge for further processing
Figure 1: Baseline conditions used in the study.
eline conditions used the study. 94 MAY 2011 in water
which then calculates power generation based on cogeneration using a combined heat and power plant (CHP). The model calculates the heat required by the digestion plant and compares it to the heat available from the CHP. If deficient, either the additional energy required to heat the digestion plant is calculated or a revised energy generation is determined if biogas use is preferred. Heat requirements for the plant take into account any diversion of gas away
from CHP (e.g. to a gas supplier), therefore it is possible to determine the maximum diversion before auxiliary fuel is required to heat the digesters.
Baseline Conditions The baseline conditions for the study are summarised in Figure 1. For anaerobic digestion an operating temperature of 35°C (typical of mesophilic operation) has been assumed. In addition, a retention time of 16 days has been used with a void (or dead space) of 20%. Void space is that within the digester which is unavailable and may be due to hydrodynamics or inert material or both. The sludge type and composition has been based on typical figures and wastewater treatment configuration. With respect to the Combined Heat and Power plant (CHP), the baseline assumes that the plant is available for use 85% of the time, and that energy used within the plant is converted to electricity and heat at a rate of 33% and 45% respectively. All the baseline conditions were altered as variables to determine their influence. Under these conditions, 10,000 tonnes dry solids per annum generate 0.76MW of electricity (MWe).
Results Dry solids concentration The concentration of dry solids (DS) in sludge fed into digesters is normally limited to approximately 6% DS due to non-newtonian flow behaviour, which makes mixing and handling increasingly difficult above this figure (Dawson et al., 2009). If rheology can be changed, however, the dry solids fed to a digester can be increased to a point where ammonia concentration influences loading (Wilson et al., 2009). Concentrations in excess of 10% have been successfully digested at full-scale by pre-teatment using thermal (Panter, and Kleiven, 2005) and acoustic hydrolysis (Barber, 2005b). In this study, the impact of adjusting dry solids from 2% to 7% is demonstrated in Figure 2.
technical features
handling increasingly difficult above this figure (Dawson et al., 2009). If rheology can be changed, however, the dry solids fed to a digester can be increased to a point where ammonia concentration influences loading (Wilson et al., 2009). Concentrations in excess of 10% have been successfully digested at full-‐scale by pre-‐ refereed teatment using thermal (Panter, paper and Kleiven, 2005) and acoustic hydrolysis (Barber, 2005b). In this study, the impact of adjusting dry solids from 2% to 7% is demonstrated in Figure 2.
100%
0.4 0.3 0.2 0.1 0 2%
3%
4%
5%
6%
7%
Dry Solids (%) Potential
After gas used
Figure 2: Influence of dry solids on energy
90% yield
80% 60%
40%
Secondary
0.5
16 days HRT
0.6
Percentage yield compared to that expected at 100 days
120%
0.8
0.7
Generation (MWe)
resource recovery
Primary
Figure 2: Influence of dry solids on energy output for municipal sludge digestion. output for municipal sludge digestion. 20% Dry solids results in a higher volumetric throughput concomitantly Dryreduction solids reduction results in a higher reducing hydraulic retention time. As the organisms responsible for biogas volumetric throughput concomitantly production are generally slow-‐growing (Zehnder et al., 1982), a reduction i0% n reducing hydraulic retention time.production As retention time w ill consequently lower biogas manifested in the 0 20 40 60 80 100 reduction in energy potential shown in for Figure 2. Also, if dry solids fall below a certain the organisms responsible biogas critical level, insufficient heat will be slow-growing produced by the CHP to heat the digester to production are generally HRT (days) mesophilic levels. The energy required to provide this heat is shown by the white e (Zehnder et al., 1982), a reduction in Figure 4: Influence of hydraulic retention time on biogas yield achievable bars in Figure 2. retention consequently This level of dry time solids will is dependent on sludge lower type, as primary acompared nd secondary to sludg that expected after 100 days of digestion for: primary (solid) generate different energy outputs, and Figure shows the minimum dry solids biogas production manifested in 3the and secondary required to enable sufficient digester heating, based on 45% recovery of heat from sludge (dashed) lines. reduction in energy potential shown the CHP. drop in gas production at 30°C and 25°C sludge (thereby reducing retention time in Figure 2. Also, if dry solids fall below
a certain critical level, insufficient heat will be produced by the CHP to heat the digester to mesophilic levels. The energy required to provide this heat is shown by the white bars in Figure 2.
respectively. Other than reduced biogas production, requirements for pathogen destruction may necessitate an auxiliary heat source if dry solids are below the levels shown in Figure 3.
This level of dry solids is dependent on sludge type, as primary and secondary sludge generate different energy outputs, and Figure 3 shows the minimum dry solids required to enable sufficient digester heating, based on 45% recovery of heat from the CHP.
The data in Figures 2 and 3 suggest 3 additional benefit in that there is little thickening above 4%, unless there are hydraulic constraints.
7% 6%
Dry Solids (%)
5% 4% 3%
hydraulic Retention time The influence of hydraulic retention time on gas yield was studied by determining a theoretical yield at 100 days’ digestion and calculating how much of that gas was generated with time. The results are shown in Figure 4 for primary (solid line) and secondary (dashed line) sludge.
The figure shows that 90% of the 100day gas yield can be obtained within five days for primary sludge but over 30 days 0% for secondary sludge. As primary and 100% primary 100% secondary 50/50 mix secondary sludge are generally digested Figure 3: Influence of sludge type on Figure 3: Influence of sludge type on minimum dry solids required to enable together, the data imply that at 16 days’ minimum dry solids required to enable sufficient digester heating. sufficient digester heating. retention time, the primary sludge has The data in Figure 3 suggest that primary sludge can be fed as low as 3% and be self-‐ ample retention time, but only 75% of sufficient for data heat, win hereas secondary sludge needs to be above 6.5% DS and mixed The Figure 3 suggest that the energy available from the secondary between 4% and 5%. If the sludge falls below these ranges, the digestion plant will primary sludge can be fed as low as 3% either: require auxiliary fuel (generally from a boiler using natural or bio-‐ gas) or has been extracted as shown in sludge and be self-sufficient for heat, whereas have to be operated at a lower temperature which causes a further reduction in graph. biogas production asludge s bacterial needs activity approximately halves every 10°C the reduction in As retention time falls further, secondary to be above temperature in accordance with the Arrhenius-‐van’t Hoff rule. Data modelled in this the lost energy from secondary sludge 6.5% DS and between 5%.at 30°C and 25°C study (not shown) imply mixed a 10% and >25% drop i4% n gas pand roduction becomes increasingly significant. For respectively. Other than reduced biogas production, requirements for pathogen If the sludge falls below these ranges, example, destruction may necessitate an auxiliary heat source if dry solids are below the levels at 10 days’ retention time the digestion plant will either: require shown in Figure 3. nearly 40% of the secondary sludge The data in Figures 2 a(generally nd 3 suggest that there ais boiler little additional auxiliary fuel from usingbenefit in thickening energy is unavailable. above 4 %, u nless t here a re h ydraulic c onstraints. natural or biogas) or have to be operated at a lower temperature, which causes a The results suggest that separate [x-‐head] Hydraulic Retention Time in biogas production as further reduction digestion of primary and secondary The influence of hydraulic retention time on gas yield was studied by determining a bacterial halves sludge theoretical yield activity at 100 days approximately digestion and calculating how much of that gas was may yield benefits with regard generated ith time. The results are in Figure 4 for primary (solid and generation. For instance, if everyw10°C reduction inshown temperature toline) biogas secondary (dashed line) sludge. in accordance with the Arrhenius-van’t a facility was digesting mixed sludge in Hoff rule. Data modelled in this study four digesters, separating the streams and using one digester for the primary (not shown) imply a 10% and >25% 2% 1%
for that sludge) and the remaining three digesters for the secondary sludge (increasing retention time) may prove beneficial. The data also demonstrate why there is a continued healthy interest in technology to improve digestion of secondary sludge such as: thermal hydrolysis; cell rupture; high pressure hydrolysis, and pulsed electric field technologies (Hunt and Wilson, 2008). By making sludges more biodegradable, these technologies could enable digestion plants to extract more biogas. Lastly, if sludge streams are separated, pre-treatment technology can be reduced in size as it can be designed only for the secondary sludge. However, the benefits of doing this should be weighed against sludge stabilisation requirements, as only the pre-treated secondary sludge may be compliant with higher pathogen standards.
Volatile solids Volatile solids were adjusted between 70% and 80% with a linear relationship of 1% volatile solids being equivalent to 10kWe, showing that as volatile solids content increases so does the energy available. With respect to sewage treatment, volatile solids content is controlled by sludge type and by any nutrient removal using chemicals. Regarding sludge type, secondary sludge generally contains higher volatile solids content than primary sludge due to a higher proportion of bacterial content (Barker and Stuckey, 1999; Speece, 2008). Typically primary sludge has volatile solids of approximately 70%, with secondary sludge 10% higher. Although higher in volatile content,
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replacing it with facilities designed to meet modern drivers may be neither viable nor economic. Therefore, in order to assist with targets for renewable energy and carbon footprint reduction it is necessary to make better and/or alternative use of existing facilities, irrespective of whether new infrastructure is installed or not. paper This work has looked at a number of variables with rrefereed espect to increasing renewable energy generation using existing infrastructure, and a graphical summary of the results are shown in Figure 6. 1.2 primary sludge. Highest Less beneficial At 16 days’ benefits 1 retention time, typical of the 0.8 UK, secondary sludge generates 0.6 approximately 40% of the 0.4 energy recovery from primary 0.2 sludge. 0 In fact, modelling conducted during this study has shown sludge type to be the Figure 6: Influence of various parameters on energy generation single most from 10,000 tonnes dry solids of sewage sludge digested at 5% Figure 6: Influence of various parameters on energy generation from 10,000 tonnes fundamental dry solids at 16 days. dry solids of sewage sludge digested at 5% dry solids at 16 days. influence on in the biogas; calorific value of the energy generation biogas and its fluctuation; number of from sewage digestion. This is consistent engines; of critical spares, Digesting 1 0,000 t onnes o f d ry solids of savailability ewage sludge can generate anything with findings by Winter and Pearce and volume of biogas holders.pThe impactFigure 10 between 0.4 yields to 1 Mfor W of electricity depending on site-‐specific arameters. (2010), who determined gas availability a straight linehwith that the most toinfluential ofparameter is tfollows he sludge itself, with igher primary sludge inshows the region of two a slope of 7.5kWe per percentage point proportions o f p rimary s ludge p roviding t he g reatest b enefits a s p reviously shown. three times those measured for secondary increase in availability. Electrical efficiency As on sludge ype is to type of wastewater treatment, it may be time sludge, depending the tunits ofintrinsically linked alsotreatment followedtarain linear to revisit he spite wastewater to erelationship. ncourage production of measurement referred to. tIn of this, process However, the influence was found to primary o ver s econdary o r c hemical ( e.g. f erric) s ludges. Enhancing primary sludge the proportion of primary and secondary be greater with a slope of 23kWe per production a lso h as b enefits o f r educing l oad t o t he d ownstream w astewater sludge typical of a sewage treatment
Methane Content Biogas methane content during anaerobic digestion is dependent on the oxidation state of carbon within the material being digested as highlighted in the work of Gujer and Zehnder (1983) and can be theoretically determined by stoichiometry (McCarty, 1966). For sludge digestion the methane content is approximately 65%. In this study it was varied between 55% and 75%. Energy generation follows a linear relationship with 1% methane content equivalent to 12kW of electricity. The methane content in biogas will become increasingly significant due to growing interest in the co-digestion of other waste streams. From the work of Gujer and Zendher (1983), methanol and fats will generate biogases with higher methane contents (compared with sewage sludge), while sugary wastes, proteins and fruit juices will generate lower methane content biogases. Urea, with a carbon oxidation state of +4 will generate biogas comprised entirely of carbon dioxide.
sludge type The energy generation from secondary sludge is significantly lower than that from primary at the same retention time, as shown in Figure 5. The figure shows that the dry solids in secondary sludge routinely generate less than half the energy of an equivalent amount in 1.2
Generation (MWe)
1 0.8 0.6 0.4 0.2
works has historically evolved to meet wastewater quality targets with little or no consideration for the type or quantity of sludge produced. Ironically, increasingly strict wastewater drivers will encourage the production of more secondary sludge at the expense of primary. Ammonia removal via nitrification requires longer sludge ages during secondary treatment, which, as well as generating more secondary sludge (which is increasingly difficult to biodegrade), encourages the growth of filamentous organisms which have been found to stimulate foaming problems in downstream digesters (Speece, 2008). There has been a trend in recent years to use the energy within the sludge as a carbon source for nutrient removal. This is generally practiced by purposely fermenting a proportion of the primary sludge, or bypassing primary treatment altogether and starting with aeration, resulting in plants generating no primary sludge. Thus there will be a corresponding reduction in biogas.
ChP (Cogeneration) Availability and electrical efficiency
0
In this context, availability refers to the 0 20 40 60 80 100 HRT (days) percentage of the time that the plant is available for use. This is dependent on Figure 5: Influence of sludge type on Figure 5: Influence of sludge type on energy generation against retention time. a number of operational parameters energy againstsludge retention time. Key: primary generation sludge (full); secondary (dashed) lines. such as: presence of contaminants, Key: primary sludge (full); secondary In fsludge act, modelling conducted during this study has shown sludge type to be as the hydrogen single such sulphide and siloxanes, (dashed) lines. most fundamental influence on energy generation from sewage digestion. This is consistent with findings by Winter and Pearce (2010), who determined gas yields for 96 sludge MAYin 2011 water primary the region of two to three times those measured for secondary sludge, depending on the units of measurement referred to. In spite of this, the proportion of primary and secondary sludge typical of a sewage treatment works has historically evolved to meet wastewater quality targets with little or no
All primary
Electricity at 41%
All advanced MAD
CHP available 90%
At 80% VS
At 8% DS
Clean digesters
At 6% DS
Baseline
CHP available 80%
At 30C
There is an increasing demand to remove phosphorus from wastewaters for environmental reasons. If instead of biological removal, iron or aluminium salts are used to precipitate the phosphorus, it ends up in sludge as an inert. This reduces volatile solids content, ultimately leading to reduced energy generation. Previous work has shown that calorific value of sludge is significantly lowered on a dry basis when ferric salts are added to it (Barber, 2007).
All SAS
secondary sludge is harder to digest as it contains large quantities of high molecular weight material (such as cell walls) for which the hydrolysis is rate limiting (Tong and McCarty, 1991).
Generation (MW)
resource recovery
percentage point increase in electrical efficiency. Modern engines are capable of generating a higher fraction of energy from a given amount of biogas, with the larger engines capable of achieving as high as 41% efficiency. However, this will come at the expense of the heat necessary to maintain mesophilic temperatures.
Discussion As the vast majority of anaerobic digestion infrastructure has long asset life, replacing it with facilities designed to meet modern drivers may be neither viable nor economic. Therefore, in order to assist with targets for renewable energy and carbon footprint reduction, it is necessary to make better and/ or alternative use of existing facilities, irrespective of whether new infrastructure is installed or not. This work has looked at a number of variables with respect to increasing renewable energy generation using existing infrastructure, and a graphical summary of the results are shown in Figure 6. Digesting 10,000 tonnes of dry solids of sewage sludge can generate anything between 0.4 to 1MW of electricity depending on site-specific parameters. Figure 10 shows that the most influential parameter is the sludge itself, with higher proportions of primary sludge providing
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the greatest benefits, as previously shown. As sludge type is intrinsically linked to type of wastewater treatment, it may be time to revisit the wastewater process treatment train to encourage production of primary over secondary or chemical (e.g. ferric) sludges. Enhancing primary sludge production also has benefits of reducing load to the downstream wastewater treatment, which concomitantly reduces aeration, which accounts for a large majority of a water company’s electricity consumption. The data suggest that wastewater treatment and sludge treatment can no longer be viewed in separate silos but should be viewed jointly, as choices made to meet a wastewater driver can have fundamental and long-lasting impacts on sludge processing. After sludge type, conversion to electricity with new engines, and installation of pre-treatment to enhance biogas production (Hunt and Wilson, 2008) are the most influential. However, highly efficient engines are limited to larger sizes and may not be viable on smaller sites, and pre-treatment plants may have parasitic demands which need to be accounted for in a full energy balance (Bungay, 2009). If there is sufficient existing capacity and sludge thickness is above the minimum threshold required to provide digester heat, then further thickening, cleaning digesters to increase retention time, slight increases in CHP availability and volatile solids have little influence. Nevertheless, any one or combination of these parameters may prove beneficial, dependent on site-specific conditions. Sludges fed to digesters below the minimum dry solids required for heat selfsufficiency should be thickened to levels above those shown in Figure 3, to avoid lost biogas production (from a drop away from ideal temperature conditions) and/or requirement of supplementary fuel. Finally, a number of technologies, some of which are common to other industries, can be employed to further optimise municipal sludge anaerobic digestion. These include: plug-flow configurations; high-rate digestion such as anaerobic filters or recirculation processes; or addition of nutrients, enzymes or biogas precursors.
Conclusions In the water industry, anaerobic digestion infrastructure was not originally built to meet modern drivers for renewable energy generation and carbon footprint reduction. As it is impracticable to completely replace this infrastructure, it needs to be
optimised and used in novel ways to assist with these targets. A number of parameters are influential in controlling the renewable energy potential from municipal sludge digestion. The most important of these is sludge type. Primary sludge produces over twice the energy from an equivalent content of secondary sludge. However, environmental drivers may encourage production of more secondary sludge. It is important that wastewater and sludge treatment be viewed jointly, as wastewater technology controls the amount and type of sludge produced, which in turn has downstream impacts. Separate treatment of primary and secondary sludge may generate benefits with respect to digestion performance. After sludge type, the most influential parameters are electricity-efficient CHP engines and pre-treatment technologies to enhance biogas production. If the sludge digested has reached a minimal dry solids required to provide digester heating, and the digestion plant is not hydraulically overloaded, there is little benefit in further thickening the sludge. As typical digestion configurations are inherently sub-optimal with respect to the biological processes taking place, it is possible to retrofit a number of high rate and advanced digestion processes to further enhance biogas production.
the Author
Water and Environmental Management, 19 (1), pp. 2–7. Barber WPF, 2007: Observing the effects of digestion and chemical dosing on the calorific value of sewage sludge. IWA Specialist Conference: Moving forward – Wastewater Biosolids Sustainability: Technical, managerial, and public synergy, June 24-27, 2007, Moncton, New Brunswick, Canada, pp. 351–358. Bungay S, 2009: Operational experience of advanced anaerobic digestion. Proceedings of the Aqua Enviro/CIWEM 14th Biosolids and Organic Residuals Conference, Leeds, UK. Chae KJ, Am Jang, Yim SK, and Kim IS, 2008: The effects of digestion temperature and temperature shock on the biogas yields from the mesophilic anaerobic digestion of swine manure. Bioresource Technology, Volume 99, Issue 1, pp. 1–6. Dawson MK, Heywood NI, Alderman NJ, Papachristou C & Loannou P, 2009: Sludge system pumping losses: UK Industry Standard is Flawed. Proceedings of the Aqua Enviro/ CIWEM 14th Biosolids and Organic Residuals Conference, Wakefield, UK. Gujer W & Zehnder AJB, 1983: Conversion processes in anaerobic digestion. Water, Science and Technology, 15, Copenhagen, pp. 127–167. Hunt P & Wilson T, 2008: Overview of recent developments in anaerobic digestion Technologies. Aqua Enviro/CIWEM 13th Biosolids and Organic Residuals Conference, Wakefield, UK. McCarty PL, 1966: Kinetics of waste assimilation in anaerobic treatment. Developments in Industrial Microbial Sciences, 7. American Institute of Biological Sciences, Washington D.C. McCarty PL, 1982: One hundred years of anaerobic treatment, In: Hughes et al. (eds). Anaerobic Digestion 1981, Elsevier Biomedical Press B.V., pp. 3–21.
Dr William (Bill) Barber (email: Bill. Barber@aecom.com) is Biosolids and Wastewater Technical Director for AECOM and is based in their Sydney office. He was previously Biosolids and Sustainability Technical Specialist for United Utilities in the UK where he was involved in developing biosolids strategies, and worked on a large number of different biosolids technologies including the world’s largest thermal hydrolysis facility. He is internationally regarded as an expert in biosolids treatment.
References Barber WP, 2005a: Modelling the influence of municipal sludge anaerobic digestion and co-digestion on downstream unit operations. Proceedings of the Aqua Enviro/CIWEM 10th Biosolids and Organic Residuals Conference, Wakefield, UK. Barber WP, 2005b: The effects of ultrasound on anaerobic digestion. CIWEM Journal for
Panter K & Kleiven H, 2005: Ten years’ experience of full scale thermal hydrolysis projects. 10th European Biosolids & Biowastes Conference, Wakefield, UK. Speece RE, 2008: Anaerobic Biotechnology and Odor/Corrosion Control for Municipalities and Industries. Archae Press, ISBN:1-57843-052-9. Tong X & McCarty PL, 1991: Microbial hydrolysis of lignocellulosic Materials, In: L R. Isaacson, Ed. Methane from Community Wastes, London: Elsevier Applied Science, pp. 61–100. Wilson CA, Novak JT & Murthy SN, 2009: Thermal Hydrolysis of the Lipid and Protein Fractions of Wastewater Sludge: Implications for Digester Performance and Operational Considerations. 82nd Annual Water Environment Federation Technical Exhibition and Conference, WEFTEC, New Orleans, LA, USA, pp. 3918–3922. Winter P & Pearce P, 2010: Parallel digestion of secondary and primary sludge, 15th European Biosolids & Biowastes Conference, Leeds, UK. Zehnder AJB, Ingvorsen K & Marti T, 1982: Microbiology of methane bacteria, In Hughes et al. (eds), Anaerobic Digestion 1981. Elsevier Biomedical Press B.V., pp. 45−68.
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CoGeneRAtIon By A MICRo-tuRBIne opeRAtInG on BIoGAs
Australia’s first application of Capstone Micro-turbine technology reduces greenhouse gas emissions J Boan, R Howick, A Davey Abstract In an Australian first, Western Water (Vic) partnered with Aquatec-Maxcon to design, supply and install a Capstone Micro-turbine at the Melton Recycled Water Treatment Plant to operate on anaerobically produced bio-gas. The single Capstone CR200 turbine can provide over 200kW of electrical power at the Melton Recycled Water Treatment Plant, along with 276kW of heat to enable the plant’s digesters to work at optimum efficiency. A pre-treatment system ensures that the turbine is protected from silica deposition.
Introduction Western Water is a Victorian water utility that services 135,000 people in the outer regions of Western Melbourne. One of Western Water’s core corporate values is to operate sustainably and the organisation has committed to be carbonneutral by 2017. The Melton Recycled Water Treatment Plant is a 10ML/day activated sludge treatment plant with tertiary lagoon treatment. It services the townships of Melton, Melton South, Toolern and Eynesbury with both Class C recycled water and Class A recycled water. The sludge treatment process at Melton Recycled Water Treatment Plant incorporates an anaerobic digester. Through Western Water’s design and tender process different technologies for capturing bio-gas to produce energy were investigated. Aquatec-Maxcon’s Capstone Micro-turbine technology was identified as providing the best present value. In an Australian first, Western Water partnered with Aquatec-Maxcon to design, supply and install a single Capstone CR200 turbine which can provide over 200kW of electrical power at the Melton Recycled Water Treatment Plant, along with 276kW of heat to make
98 MAY 2011 water
Figure 1: Capstone Micro-turbine installation at Melton Recycled Water Treatment Plant. the plant’s digesters work at optimum efficiency.
Cogeneration Facility
Western Water operating staff have spent a number of years optimising and understanding how to get the best out of the anaerobic digester at the Melton Recycled Water Treatment Plant, and have proven that a well-maintained digester is able to produce methane levels of up to 70%. This increases the enthalpy value of the biogas above 25 MJ/m3, increasing the ability of a cogeneration system to produce more power and thermal output, and provides a higher value on this important resource.
Anaerobic digester systems have been used for decades at municipal wastewater facilities and, more recently, have been used to process industrial and domestic wastes. These systems are designed to optimise the growth of the methaneforming (methanogenic) bacteria that generate CH4. Typically, using organic wastes as the major input, the systems produce biogas that contains 55% to 70% CH4 and 30% to 45% CO2. The Melton Recycled Water Treatment Plant utilises mesophilic anaerobic digestion operating at an elevated temperature of 35˚C to 38˚C. An external energy source is required to maintain this elevated temperature.
The conventional system adopted in Australia is a dual fuel diesel set, with the jacket cooling water used to warm the digester. However, Aquatec-Maxcon offered the alternative of a Capstone Micro-turbine. The model CR200 can produce 200kW of power with less than 100Nm3/hr of biogas. Secondly, an external heat recovery module working in combination with the exhaust from the Micro-turbine can deliver 200kW of thermal energy through cogeneration to supply the process heat requirements of the Recycled Water Treatment Plant. Figure 1 is a photograph of the facility.
Together, the combined heat and power produced has resulted in cuts in carbon dioxide emissions at the plant of 1800 equivalent tonnes per year. The implementation of this project represents a greenhouse gas emissions saving to Western Water of 8% of our total emissions and is a significant step towards carbon neutrality by 2017.
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together with the power produced, made it the best option. Hence, this did not just take into account energy efficiency but the per annum availability of the Capstone equipment, which is well over 99% when compared to other cogeneration technologies available in the marketplace. Typically, the only down time would be for servicing and Capstone estimate six hrs/yr per turbine per year. The Capstone Micro-turbine can operate for 8,000 running hours before the air and fuel filters need to be changed, and fuel igniters and actuators inspected.
Figure 2: The Capstone Micro-turbine. The Capstone Micro-turbine (Figure 2) is a simple elegant system incorporating a recuperator, combustor, turbine and a permanent magnet generator. The rotating components are mounted on a single shaft, supported by patented air bearings that are spinning at up to speeds of 60,000rpm. There is only one moving part in the turbine and it is simply cooled by inlet air. The system uses no oil, no lubricants and no coolants, and has no pumps, gearbox or other mechanical subsystems other than air bearings. Furthermore, the Capstone Microturbine technology requires minimal maintenance in terms of replacement parts, as engines are overhauled after a period of nine years and all other parts exposed to the biogas are suitable for hydrogen sulphide (H2S) levels of up to 60,000ppm. It has rapid start-up and shut-down and can be controlled to follow instantaneous power demand.
It is slightly less efficient than a dieselelectric set in producing power, but in cogeneration mode the heat is not wasted.
present Value and Choice of technology Western Water conducted a thorough review of the required thermal energy needs for the plant and biogas quality to establish a clear understanding of the tender requirements. A key learning throughout the process has been that the specific choice of technology is governed by the needs of the particular application. In the Western Water example we required less thermal output than other technologies could have provided, but we did require an equally high power production given the number of substantial power requirements required on-site for aeration, recycled water and other energy-intensive equipment necessary for advanced waste treatment.
Figure 3: Present Value Assessment Option
Aquatec-Maxcon Capstone CR200
Period of Assessment
20 years
Discount Rate
5.8%
Annual Indexing (%)
2.5%
Depreciation
2.5%
Tax Rate
30.0%
Assumed Power Cost
$0.19 per kWhr
Capital Expenditure
$1.6M
operational expenditure (over 20 years) (including media replacement for the carbon, engine planned maintenance and overhaul of the turbine every 9 years)
$1.6M
Cost offset Due to power savings (including projected reliability)
($8.3)M
present Value (After tax)
($1.1)M (nett saving)
Comparison to a Diesel-electric Genset option (using similar planned maintenance and recommended engine overhaul periods)
$0.5M (nett cost)
When providing the present value analysis (Figure 3) Western Water concluded the high availability per annum and low projected maintenance costs of the Capstone Microturbine proposed by Aquatec-Maxcon,
power efficiency The Micro-turbine can be set up to follow the site peak load as it varies during the day, providing power in excess of the base power supplied by the utility grid. The site power load can vary between 240kW and 630kW, depending on the operation of recycled water plant and the number of aeration blowers used for the wastewater plant. This allows the Micro-turbine to track electrical loads at the plant and supply only as much power as required. The Micro-turbine currently supplies between 100kW to 200kW of site power above the base load. This is achieved in either of two ways: â&#x20AC;˘ Use all the available biogas in the turbine (when there is sufficient volume in the gas holding tank) to produce 200kW of power and minimise electricity import from the power authority. Due to the small size of the existing gas holding tank there is not sufficient capacity to allow the Micro-turbine to operate for long periods at 200kW; or â&#x20AC;˘ When gas availability is low in the holding tank, the Capstone is run at half-capacity, i.e. 100kW, and turned off as necessary if the holding tank runs out of biogas. The Micro-turbine is expected to operate at full demand in the future once
Figure 4: The Micro-turbine operating at different power settings.
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more sludge digesters are brought online and there is sufficient biogas to continuously feed the Micro-turbine at full capacity.
ensure that the digester is always heated if the turbine is not operating. A simplified diagram is shown in Figure 6.
Performance tests for the different power demands are shown in Figure 4. The graph also shows gas consumption required for each power demand from 100kW to 200kW.
This thermal heat is transferred into the primary heat loop, which is connected to the sludge digester, ensuring a fully closed and rejuvenating system between biogas production and heat recovery. The heat loop control monitors temperature on the outlet of the primary heating loop to increase/decrease hot water pump flow. The flow rate of the primary heat loop will vary between 3.6m3/hr and 24m3/hr, depending on the outlet temperature from the heat exchanger. A temperature setpoint is entered into the temperature controller on the HRM between 68˚C and 72˚C. In the first instance it uses the exhaust gas to achieve the desired water temperature set point.
The peak load following mode allows the operator to reduce peak demand charges where applicable, when power draw from the utility grid is limited to supply equipment capacity, or installed capacity exceeds the minimum local load demand of the site. Using the site power demand setting as the main input, the output of the Capstone Micro-turbine is trimmed using the level in the existing gas holding tank (Figure 5), which is a floating storage tank and can hold up to 300 Nm3 of biogas and operates as buffer storage. The power output of the Micro-turbine system is adjusted according to the level in the gasometer attached to the gas holding tank. The Micro-turbine is operated mostly during the day when power tariffs are high and the treatment plant draws the most power. The control system has to wait for the gas holding tank level to be greater than 50% to start the Capstone Micro-turbine. If the holding tank reaches 70% then the Capstone can slowly ramp up in 5kW power increments over two to three hours, and if the level drops to less than 60%, the Micro-turbine ramps down in equal increments over the same amount of time. This ensures that the gas holding tank volume is maintained at a reasonable level and the turbine does not draw all the biogas produced. To satisfy the local power authority, Powercor, that the Microturbine would not damage the local network, Reverse Power Protection has been installed at the Melton site. Although the Micro-turbine can actually export to the power grid, the local power authority has not allowed Western Water to do so at this point in time. Hence, power is only produced on the site and not exported to the grid.
Hot water is also transferred to the heater attached to the Clean-In-Place tank on a secondary heat loop used for a membrane cleaning system, which is part of the Melton Recycled Water Plant. The Complete Heat Recovery System is shown in Figure 7.
Greenhouse emissions While carbon emissions were not measured in the whole-oflife costs, the ultra-low Nox emissions weighted heavily in the decision to choose the technology, since the Micro-turbine
Figure 5: The existing sludge digester and holding tank.
thermal efficiency Waste heat is generated through fuel combustion in the Capstone CR200. The strategy of how to recover this heat depends in part on the temperature of the waste heat gases. In the case of the Melton Recycled Water Treatment Plant, the Capstone CR200 Micro-turbine’s exhaust gas was typically 285˚C (continuous running), (instantaneous max 370˚C), which determined the sizing parameter for the Heat Recovery Module (HRM). The Capstone Micro-turbine is truly a cogeneration unit with the ability to produce both power and thermal heat. When the digester produces approximately 100 Nm3/hr of sludge biogas at 22 MJ/m3 it produces approximately 615kW from fuel gas and 400kW of thermal heat from the turbine exhaust. Given the electrical efficiency of the Capstone is about 32%, this produces 200kW of electricity after derating is taken into account. 400kW of sludge gas at 50% efficiency will produce 200kW of thermal heat. In particular, there are seasonal and daily variations in the digester heat load, so there must be occasions when either an additional heat source is required and/or excess waste heat is bypassed through the vent. Within the Heat Recovery Module, a supplementary biogas burner provides an additional 76kW of thermal heat when required, to total 276kW of thermal output. The supplementary burner operates when the methane content is low in the biogas and less heat is available to the loop from the exhaust stack on the Micro-turbine. An existing boiler is also available as a back-up to operate either on diesel or biogas to
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Figure 6: Thermal heat recovery from the cogeneration facility.
Secondary Heat Loop
Primary Heat Loop
Figure 7: Primary and secondary heat recovery loops.
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resource recovery
refereed paper
Figure 8: Greenhouse emissions from Micro-turbine versus other technologies. installed, and would lead to Model Fuel NOx CO2 premature failure CR200 Digester Gas 0.415 (1)(2)(3) 1375 (1)(2)(3) of the machine if allowed to develop. (1) Emissions at 63% NG & 37% CO2 Siloxanes are not (2) For combined heat and power (CHP) operation at 70% efficiency easy to measure (3) Emissions due to combustion and consist of a number of different produces a waste gas with less than compositions, as noted in the table. 4ppm NOX and 40ppm CO emissions, The sludge biogas consists mainly of which is significantly cleaner than the Decamethylcyclopentasiloxane. urban air environment. Furthermore, Western Water received a grant from Western Water conducted a number the Victorian Department of Sustainability of biogas tests over many seasons of and Environment, and Sustainability digester operation to establish a clear Victoria for investing in a project with understanding of the levels of siloxanes low greenhouse emissions. within the biogas, and this information
Table 1: Greenhouse emissions for Capstone CR200 in Kg/MWh
The figures shown in Figure 8 for CO2 and NOX emissions are typical for turbines vs. diesel engines operating on fuels (not particularly sludge biogas). Together, the combined heat and power produced has resulted in cuts to carbon dioxide emissions at the plant of 1800 equivalent tonnes per year. This equates to removing about 450 cars off the roads per annum. Emission levels for CR200 operating on biogas are shown in Table 1. This is certainly a win for the environment, given the original plant used to flare the biogas to the atmosphere over a number of years, which was a waste of a valuable resource.
was used in the detailed design of the pre-treatment system. There was seasonal variability in the levels of H2S and siloxane present in the biogas, making it hard to predict breakthrough of the adsorption material (see Figure 9). Based on the analysis of the biogas,
a maximum H2S concentration of 2700ppm was recorded for the design of the facility. The facility also requires a gas booster compressor to pressurise the gas before injection into the Micro-turbine (Figure 10). The Micro-turbine has a high tolerance to H2S of up to 60,000ppm. However, for the gas booster compressor, a maximum level of H2S in the biogas of 5000ppm is permissible to avoid corrosion. The most economical method of removal of siloxanes is through absorption in the pores of graphite media. AquatecMaxcon, through their in-house expertise with recycled water treatment plant design, has designed an activated carbon pre-treatment system to ensure that the siloxanes are removed prior to the biogas entering the Capstone turbine. The absorption capacity of the graphite material used to remove siloxanes is also influenced by the relative humidity of the gas crossing the carbon (known and under control), by the type and quantity of VOC present in the biogas (not known) and marginally also by the quantity of H2S present in the biogas. The system utilises a lead/lag/standby arrangement to ensure there is always a carbon vessel available should removal and filling be required. The siloxane adsorption vessels have been designed to adsorb a maximum of 34ppm decamethylcyclopentasiloxane. While it is early days yet, carbon replacement will be monitored and it is expected to be replaced every few years.
Table 2: Typical siloxanes in domestic wastewater. Cyclic Siloxanes
Linear Siloxanes
D3: Hexamethylcyclotrisiloxane
MM: Hexamethyldisiloxane
D4: Octamethylcyclotetrasiloxane
MDM: Octamethyltrisiloxane
D5: Decamethylcyclopentasiloxane
MD2M: Decamethyltetrasiloxane
D6: Dodecamethylcyclohexasiloxane
MDnM: Polydimethylsiloxane
Note: M-units: (CH3)3SiO½, D-units: (CH3)2SiO, T-units: (CH3) SiO2
pre-treatment Since the turbine can cope with H2S, the only issue associated with digester biogas is the presence of siloxanes, which can affect the operation of the turbine. Siloxanes come from domestic products such as cosmetics, hair sprays, deodorants, defoamers, water-repellent windshield coatings, food additives and some soaps, and are a characteristic of the particular catchment for the Recycled Water Treatment Plant (see Table 2). When siloxanes are present in the fuel for a Capstone Micro-turbine, tiny particles of silica form in the combustion chamber. The silica particles can build up and accumulate on the nozzle vanes of the turbine wheel and then exit through the recuperator and heat exchanger if
Figure 9: Seasonal variation of biogas composition.
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resource recovery Gas Approvals There were also significant challenges related to the application of hazardous area principles and the application of ventilation in accordance with AS (IEC) 60079.10. All equipment required an AGA or equivalent certification in accordance with NFPA 497 (Classification of Flammable Liquids, Gases or Vapours) and of Hazardous (Classified) Locations for Electrical Installations. However, the cogeneration plant is made up of a number of overseas technologies with foreign accreditation which are not often applicable to local standards. These items had to be approved by a local hazard area assessor and Energy Safe Victoria, and required minor modification to achieve local safety standards, or additional costs to certify the equipment to local AusEX code.
turbines are competitive and, in Western Water’s application at Melton Recycled Water Treatment Plant, they were the optimal choice. 2.
3.
4.
The cogeneration plant was designated as a Zone 2 Hazardous Area, and a number of issues had to be addressed with the operating staff, such as: • Adequate equipment spacing away from combustion sources, using the regulatory standards;
5.
• Adequate maintenance access and gas containment during shutdowns and servicing of gas pre-treatment equipment; • Self-venting of combustible gases during plant shutdown and sufficient draining, sampling and purging of the equipment to operate the system efficiently.
6.
Lessons Learnt There were a number of key lessons learnt, including: 1.
Although this was the first use of Capstone Micro-turbines at a recycled water treatment plant, the
refereed paper
7.
A life cycle assessment was a critical tool used by Western Water to decide on appropriate technologies, particularly when there were multiple technologies available in the market place with different characteristics. In this case, maintenance cost and availability became the critical factor. It is important to understand the quality of the various components within the biogas feeding into the turbine. Extensive testing, although costly, can help mitigate this risk and allow better understanding of the necessary requirements for pre-treatment. The operator and designer need to work closely together through the issues of hazardous area assessment and gas regulations to reach a point where the operators fully understand the risks of working safely with equipment operating on biogas. A base load of not less than 100kW was necessary to ensure the generator was able to operate in an efficient manner without an extensive number of stops and starts. There were challenges in ensuring that a reverse power situation back to the network grid did not occur and this required extensive discussions with the power authority. Any such facility operating in island mode will cause the power authority to be concerned about protection of their network infrastructure. Western Water has proven that a well maintained digester should be able to produce methane levels up to 70%. Western Water operating personnel
have spent a number of years optimising and understanding how to get the best out of the anaerobic digester at Surbiton Park. This has meant that biogas has an even higher value as a resource. 8.
The control system needs to be significantly robust to ensure stable operation of the turbine equipment in comparison to varying gas production from the holding tank and anaerobic digester.
9.
The combined heat and power produced has resulted in cuts in carbon dioxide emissions at the plant of 1800 equivalent tonnes per year. This is certainly a win for the environment, and has proven that biogas can provide a renewable source of energy. Western Water believes the facility will provide a platform for future installations at other recycled water plants across Australia.
Conclusion This was Australia’s first application of Capstone Micro-turbine technology operating from biogas produced at a Recycled Water Treatment Plant. Plant managers from Western Water predict that savings realised from the on-site generation of electrical and thermal power, plus the “green” incentives offered by the government, will justify the installation of a second CR200 system in 2010 and ultimately a third one as gas availability increases. Through careful consideration of the available technologies Western Water has reduced its greenhouse gas emissions by 8% and is moving towards carbon neutrality by 2017.
The Authors Justin Boan (email: justin. boan@westernwater.com. au) is a Project Manager with Western Water, Sunbury, Victoria. Ron Howick (email: ronh@ aquatecmaxcon.com.au) is the National Manager of Standard Products for Aquatec-Maxcon, Ipswich, Queensland.
Figure 10: Gas pre-treatment consists of a gas booster and siloxane adsorption vessels.
102 MAY 2011 water
Anthony Davey (email: anthonyd@aquatecmaxcon. com.au) is a branch manager with Aquatec-Maxcon, Melbourne, Victoria.
technical features
wetlands for wastewater treatment
VERTICAL FLOW WETLANDS FOR INDUSTRIAL WASTEWATER TREATMENT The largest combination of vertical flow wetlands in Australia is at a chemical and fertiliser manufacturer in Kwinana SS Domingos, S Dallas, S Felstead Abstract Wastewater from CSBP, a chemical and fertiliser manufacturer in Kwinana, Western Australia, comprising stormwater and low-strength process effluent, is diverted to a wastewater containment pond and treated via a series of nutrient stripping wetlands, prior to discharge to the Sepia Depression Ocean Outlet Landline (SDOOL). Firstly, wastewater is successfully nitrified in two fill-anddraw wetland cells operated in parallel. Subsequently, denitrification takes place with the addition of external carbon in a constantly saturated wetland. In an example of industrial synergy, high organic carbon waste streams from neighbouring industries have been dosed into the saturated wetland in order to improve nitrogen removal.
treatment train in 2009 by adding two VF wetland cells of 8,000m2 each to the already existing 12,000m2 saturated surface VF wetland, expanding the total wetland area to 2.8ha (Figure 1). The inorganic wastewater generated is characterised by high nitrogen, predominantly NH3-N, phosphorus and TDS content (and low COD and TSS).
The System
The treatment system includes a containment pond which serves as an equalisation and settling basin. From the containment pond water is alternately pumped into the parallel VF wetlands. Rather than intermittently fed freedraining systems, these cells operate in a sequencing batch (fill and draw) mode. Batches are ideally up to 1,600m3/day, but can be higher than 2,000m3/day depending on rainfall and wastewater production. Operation is usually 12hrIntroduction filling, 12hr-full, 12hr-draining and 12hrThe recognition of constructed wetlands resting empty. While one cell is filling, for reliably treating industrial effluents is the other one is emptying, then resting, on the rise in Western Australia. Evidence and vice versa. The nitrified effluent from of this is the recent construction of two the parallel VF cells is pumped into the full-scale vertical flow (VF) wetlands six-year-old saturated-surface VF system at CSBP Ltd, a chemical and fertiliser which has woodchips incorporated in the substrate and on the top of the sediment. manufacturer in Kwinana, 40km south of A full description and performance data Perth. CSBP upgraded its wastewater for this cell alone can be found in C Domingos et al. Nitrification Denitrification Sepia Depression (2009). VF 8,000m
1
The sand used for the 50cm main filtering layer was locally available from the site (Kwinana sits on a sand dune). This fine sand (0–0.5mm), however, would not be suitable for VF wetlands treating wastewaters with a BOD and TSS content, due to clogging potential. The combination of the local carbonaceous sand and the furnace slag was to provide good phosphorus retention capacity and alkalinity to support nitrification in the VF wetlands. The inlet pipe has several spreaders to allow even distribution of water across the surface (Figure 3). Seedlings were sourced from a local nursery and included native Schoenoplectus sp., Juncus sp. and Isolepis sp. (Full aerial photographic coverage of the construction can be scrolled at www.nearmap.com/?II=32.237093,115.7631&z=18&t=k&n md=20110314.)
Ocean Outfall (Water Corporation)
2
The new VF wetlands have an VF Saturated VF 2 HDPE liner covered 8,000m 2 12,000m by geotextile and incorporated a Potential recirculation/reuse 20cm drainage layer of blast furnace Figure 1: Treatment train at CSBP showing the two new VF Figure 1: Treatment rain at CSBP howing tand he two ew VF wetlands operating in parallel and the the slag covering wetlandstoperating in sparallel the nsix-year-old saturated 6-‐year-‐old ssurface aturated VF w etland. circle ith the etter Cinto going F drainageVpipes on VFsurface wetland. The circleThe with thewletter C lgoing theinto the saturated cell indicates the addition of hindicates igh carbon content wastewater into the wetland to favour nitrate (Figure the bottom saturated VF cell the addition of high carbon content removal. 1, wastewater 2 and 3 indicate ampling points. 2). This layer into sthe wetland to favour nitrate removal. The consists of 15cm numerals 1, 2 and 3 indicate sampling points. The new VF wetlands have an HDPE liner covered by geotextile and incorporated a 20cm drainage layer of blast furnace slag covering the drainage pipes on the bottom (Figure 2A). This layer consists of 15cm of 14mm slag on the bottom and a 5cm intermediate layer of 7mm slag on top (to avoid sand wash down into the slag layer). In an example of industrial synergy, CSBP has used slag from Kwinana neighbour HiSmelt (slag being a by-‐product of HiSmelt’s smelting activities) as the Influent Containment pond
of 14mm slag on the bottom and a 5cm intermediate layer of 7mm slag on top (to avoid sand wash down into the slag layer). In an example of industrial synergy, CSBP has used slag from Kwinana neighbour HiSmelt (slag being a by-product of HiSmelt’s smelting activities) as the aggregate for the new wetland cells.
2
3
Figure 2: The drainage layer taking shape – spreading the intermediate 7mm blast furnace slag on top of the 14mm layer. Note the “air” pipes which connect to the drainage system under the slag coming up in the centre and on the batter (far end).
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MAY 2011 103
wetlands for wastewater treatment From September 2009 effluent NH3-N dropped to <2.0 mg/L in several occasions, indicating efficient nitrification; as a result TN in the effluent is mainly composed of NO3-N, therefore the need to reduce it to N2 in the saturated VF.
Figure 3: The initial planting stage. Note the inlet distribution pipe covered by limestone rocks and central “air” pipes sticking out. After four years of continuous operation (2004–2008) the saturated VF wetland presented signs of surface clogging (slow draining of the wetland due to sludge accumulation). This problem was overcome by fully draining the wetland and mechanically removing, by small bobcat, the accumulated sludge and exposing the clear sand underneath over about 50% of the area. Some plant sacrifice was expected with this operation, hence the striped vegetation pattern seen in Figure 4. Within a year vegetation had recovered in the cleared areas. A recommendation to avoid (or postpone) clogging in the saturated VF wetland was to drop the water level to below the surface of the sand to allow drying and oxidation of the accumulated sludge on a monthly basis. Plant mortality was high in the new cells but survivors grew vigorously in the first year (Figure 5). Even though both VF wetlands are identical in terms of construction and operation, plant development and coverage was much higher in one of the cells for no evident reason. The effect of the new VF cells in terms of NH3-N oxidation can be seen in Figure 6. Within three months of commissioning, the pattern of higher NH3-N and lower NO3-N in the final effluent was permanently reversed.
Figure 4: An aerial view of the treatment train at CSBP. Alternate fill-and-drain operation is visible on the two VF parallel cells (far end) just prior to planting. Note the transverse vegetation strips on the saturated VF wetland as a result of removal of the top sludge layer to overcome clogging. As the influent lacks organic carbon (influent COD≈50mg/L), and whatever is available initially gets oxidised in the first-stage VFs, removal of NO3-N by denitrification can only be achieved with the introduction of external carbon to the saturated VF. Woodchips were added on the surface of the bed as a long-term, slow-release carbon source. The addition of sugar-rich wastewater from a nearby soft drink manufacturing plant has been successfully trialled in the laboratory (data not shown), but the full scale trial demonstrated that larger volumes or more concentrated wastewaters were needed to meet the demand. In a one-off exercise, acetic acid (1g Ac.acid = 1g COD) was dosed into the wetland at a 5 COD:NO3-N ratio for approximately three weeks during May/ June 2010. This addition resulted in NO3-N dropping to 2.7mg/L, the lowest concentrations achieved in the whole
period studied, July 2009–June 2010 (see Figure 6). The monthly average fell from 70mg/L in May to 12mg/L in June, when acetic acid was dosed. Cost, however, makes this practice prohibitive. More recently, ethylene glycol waste (spent motor vehicle coolant, COD=400,000–600,000mg/L) has been tested and demonstrated to be (as was the soft drink wastewater) a promising carbon source and a good example of industrial synergy with potential environmental and economical benefits.
Figure 5. A VF cell one year after planting. Influent concentrations of TN (NH3-N + NO3-N) are highly variable and can be quite high in isolated events; the capacity of the wetlands in handling these events has been demonstrated. The expansion of the total wetland area has resulted in increased storage and buffering capacity prior to discharge via the SDOOL. This system is, to our knowledge, the largest combination of VF wetlands operated in Australia. Total cost for the construction of the two new VF cells (8,000m2 each) was AU$2.1million (2009). The wetlands at CSBP will feature as a technical tour destination during the 13th IWA International Conference on Wetland Systems for Water Pollution Control to be held at Murdoch University, Perth, from 25–28 November 2012.
The Authors
Sergio Domingos (email: s.domingos @murdoch.edu.au) is a PhD candidate and Stewart Dallas is Adjunct Lecturer at the School of Environmental Science, Murdoch University, Perth. Stephanie Felstead is Senior Environmental Advisor at CSBP Ltd, Kwinana, Western Australia.
References: Figure 6: Daily monitoring of N concentrations in the influent (containment pond) and final effluent of the saturated VF wetland systems (sampling points 1 and 3). Influent TN is predominantly NH3-N. Acetic acid addition at COD:NO3-N =5 is indicated by the bracket (May/June 2010).
104 MAY 2011 water
Domingos S, Dallas S, Germain M & Ho G, 2009: Heavy metals in a constructed wetland treating industrial wastewater: distribution in the sediment and rhizome tissue. Water Science & Technology, 60 (6). pp. 1425-1432.
technical features
refereed paper
membranes & desalination
TreATIng ConTAMInATed groundWATer WITh reverSe oSMoSIS Improved pre-treatment reduces severe bio-fouling problems F Barendregt, M Selleck Abstract The Botany Groundwater Treatment Plant was plagued with severe biological fouling from start-up. Chloramine dosing was introduced, and high dosages achieved moderate success. Water re-use was limited by organic carbon and chloramine passage through into reverse osmosis permeate. Retrofitting to include biological treatment partially reduced organic carbon in the reverse osmosis feed, and allowed for the reduction of chloramine dose. The lower chloramine and organic carbon concentrations in permeate facilitated its re-use as feed water to demineralised water plants. Periodic flushing and reduced flux and recovery were implemented to extend the reverse osmosis run times.
Introduction As a result of historical manufacturing activities at Orica’s Botany site in Sydney, NSW, dating back to the 1940s, there is a legacy of groundwater contamination within the Botany Sands Aquifer. After trials of passive remediation proved unsuccessful, the Botany Groundwater Cleanup project was initiated to achieve hydraulic containment of the contaminant plumes. A key part of the project was construction of the Groundwater Treatment Plant (GTP) in 2005 to treat the groundwater contaminated with chlorinated hydrocarbons (CHCs). The spread of the contaminants and relatively fast-moving aquifer required a fast-track implementation of the project to prevent the contaminants reaching Botany Bay. This limited the time available for pilot trials, and hence only proven technologies were considered for the design of the plant. A number of options were considered for the management and disposal of the treated groundwater. Reinjection into the
aquifer was not preferred, as there are significant challenges in performing this reliably without disturbing the aquifer and causing flooding. Discharge into the sewer system was not feasible, because the sewer does not have adequate spare capacity. At the same time, Sydney in New South Wales, along with most of southeastern Australia, was experiencing a prolonged and severe drought. Re-use of the treated water by users on the Botany Industrial Park was identified as the preferred option, as it provided a sustainable outcome by reducing the demand from Sydney Water supply. Any treated water not re-used is disposed via a stormwater canal into Botany Bay.
Feedwater and Treated Water Quality Groundwater is extracted through 114 wells along three containment lines. Figure 1 shows the containment lines intercepting the groundwater flow before contaminants reach Penryhn estuary in Botany Bay. The feed water specification was derived from samples drawn from monitoring wells installed previously to monitor groundwater contamination, along with hydrogeological modelling to predict extraction rates required to achieve containment. The Treated Water specification was based on disposal considerations, but did not at the time consider the requirements of potential users. Table 1 (see overleaf) summarises key parameters used for the design of the treatment plant. The capacity of the plant was set at 15MLD, with 91% recovery of feed as product water. The high recovery and consequential reduced reject flow allowed the reject stream to be disposed via the sewer without hydraulic overload.
Figure 1: Hydraulic containment network.
Treatment Process The GTP commissioned in 2006 included the following major components: • Acidification of extracted groundwater with hydrochloric acid to maintain iron solubility; • Air stripping to remove volatile CHCs and sulphide; • Thermal oxidation of off-gas; • Sodium hydroxide addition to stripped water to precipitate iron; • Polymer dosing to sand-ballasted clarification and multimedia filtration (10 filters) to remove iron; • Thickening of clarifier and filter backwash effluents, with recovery of thickener overflow; • Two stages (lead/lag) of granular activated carbon (GAC) contactors (five per stage) to remove trace non-volatile CHCs; • pH correction of RO feed with hydrochloric acid; • Dosing of antiscalant; • RO cartridge filters fitted with 20 micron Ultipleat® elements; • Four-stage Reverse Osmosis (RO)
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membranes & desalination
refereed paper
Table 1: GTP Water Specifications Feed Water (mg/L)
Treated Water (mg/L)
4.5–6 (std units)
6.5–8.5 (std units)
1,2 DCE
169
0.003
Total volatile CHCs
226
0.4*
Total non-volatile CHCs
0.25
0.05
Sodium
396
20
Calcium
50
15
Magnesium
17
7
Parameter pH
Iron
14
0.3
Aluminium
1.2
0.0005
Silica
10
6
Chloride
617
30
Sulphate
184
20
Sulphide
5.5
0.015
Ammonia – N
11
0.5
Nitrate + Nitrite – N
0.08
1.0
Phosphorous as P
0.95
0.01
Acetate
46
Total Organic Acids
64
BOD
72
10
Alkalinity as CaCO3
57
40
Suspended Solids
0.5
10
To meet BOD
* Various limits for individual CHCs
membrane system, with four primary RO skids for first and second stages, and two secondary skids for third and fourth stages; • CIP system for RO membranes; • Product water storage tank and distribution. Figure 2 illustrates the water treatment component of the GTP at time of commissioning.
Figure 2: Botany GTP – initial flow diagram.
early operation The plant was started at 25% capacity, with only one primary RO skid and one secondary RO skid in operation. Treated water (permeate) was recycled to supplement primary RO reject feed to the secondary RO. Within days of start-up, the plant was plagued with severe biological fouling. The RO cartridge filters blocked within 48 hours of operation, and the final (fourth) stage of RO required cleaning within a few days. After a number of cycles of cleaning the RO skids and replacing filter cartridges, the RO process was bypassed, and filtered water diverted to the sewer.
The cartridge filters were examined with a scanning electron microscope, and were found to be covered with a layer of slime (see Figure 3). EDAX (Energy Dispersive X-ray analysis) revealed that the layer largely consisted of carbon and oxygen, with only traces of inorganic crystals of aluminium, calcium and silica on top of the organic material.
The RO skids were fitted with 8" x 40" Dow® Filmtec™ membrane elements with six elements per vessel; BW30-400 in the primary skids and BW30-400/34 in the secondary skids. Each primary RO skid was designed to operate at 70% recovery and a permeate flux of 24.9L/m2h, with 120 elements in a 14:6 array. Each secondary skid was also designed to operate at 70% recovery, yielding an overall plant recovery of 91%. The design permeate flux was 19.9L/m2h, with 90 elements in a 10:5 array.
Figure 3: SEM image of a fouled cartridge.
One of the primary skids was fitted with Toray TML720-430 elements for commissioning. These elements were recovered from a small scale interim treatment process that was operated while the main plant was under construction.
Cartridge filters are designed for particulate removal, which was being achieved, but they were being fouled by an amorphous material. After exhausting the stock of 20 micron filters, 40 micron filters were sourced
106 MAY 2011 water
and installed. This provided increased run times, but potentially allowed increased particulate loading on the membranes. Similar slimes were found elsewhere through the RO skids. At the same time, the GAC contactors required backwashing every one to two days, as opposed to the expected 14-day interval. Further examination of the GAC contactor units found: • High bacterial loads in GAC backwash, over 200,000 cfu/mL; • pH drop of 0.5–0.8 units; • TOC reduction of up to 13%; • Dissolved oxygen reduction of 3mg/L–6mg/L, with GAC outlet levels often below 1mg/L. This abundance of biological activity was attributed to the presence of readily biodegradable organic carbon (RBOC), predominantly as acetate. A series of sampling and analysis showed organic acid levels in the feed water ranging from 44mg/L to 88mg/L, compared to the 64mg/L feed specification.
Chloramine dosing Chloramine dosing of RO feed was proposed to mitigate biofouling of the membranes and cartridge filters. However, it was unclear whether the cartridge filter fouling was due to growth of biofilm on the cartridge surface, or from biological material sloughing off the GAC. To address the latter concern, the dual media filters were reconfigured so that five of the 10 filters would provide filtration of the GAC contactor product prior to cartridge filtration (effectively halving plant capacity). Chloramine formation was achieved by injection of aqueous ammonia and sodium hypochlorite into a carrier water stream. This stream was dosed into the GAC contactor product stream to also limit biofouling of the dual media filters. Dosing chloramine upstream of the GAC contactors was rejected, as the GAC would dechlorinate the water, and may adversely affect biological activity in the contactors which were removing non-volatile CHCs without exhaustion of the GAC.
technical features
membranes & desalination
refereed paper
Filtered water was directed back to the primary RO skids, but the secondary skids remained bypassed. Primary reject was diverted to sewer. Chloramine dosing was started at 2ppm, and was gradually increased to determine the optimum dose. A measurable impact was not achieved until 3ppm–4ppm, with further improvement up to 5ppm–6ppm. Doses above 6ppm did not yield further improvement. Figure 4 illustrates the effect of increasing chloramine dose on the total pressure drop and normalised permeate flow of the primary RO skid operating with the Toray membranes.
processes and sulphide from further biological reduction of sulphate. The high level of chloramine required to manage biofouling was not rejected by the membranes. Chloramine levels in the RO permeate levels were similar to that in the feed and reject. This required significant dechlorination to enable disposal of excess water to Botany Bay, and together with the elevated levels of total organic carbon (TOC) passing through the membrane, prevented the use of the water in demineraliser feed applications.
Biological Pre-Treatment Based on the opportunistic biological activity occurring in the GAC contactors, the first stage (lead units) of contactors were retrofitted with aeration to actively promote biological uptake of the RBOC. The GAC media was replaced with zeolite, to allow vigorous backwashing of the media.
Figure 4: Pressure drop and normalised permeate flow with the introduction of chloramine dosing. Two primary RO skids were operated with 5ppm–6ppm chloramine in the RO feed. Run times were still limited to two to four weeks. Operation of the secondary skids resumed, but run times were only four to seven days. A run was terminated and the skid cleaned when the variable speed high pressure feed pump reached full speed, causing permeate flow to decline by 10%. This represented a decline in normalised permeate flow of 30%, well in excess of the 10–15% accepted decline to initiate cleaning.
Membrane F ouling
Figure 5: Sulphur coating on RO end caps.
Figure 6: Fouling in secondary RO elements.
Inspection of the primary RO vessels revealed sulphur deposition on the end caps (Figure 5). The sulphur originated from sulphate in the feed water, which was being reduced to sulphide in the GAC contactors, as dissolved oxygen was consumed by the biological activity. Subsequent dosing with chloramine oxidised the sulphide back to sulphur, and the colloidal particles passed through the media filters and 40 micron cartridge filters. Inspection of the secondary RO vessels revealed severe membrane fouling (Figure 6) comprised of biomass and iron sulphide. The iron arose from incomplete iron removal in upstream
Although converting only the lead units would provide only half the expected required capacity, it was unclear whether non-volatile CHCs, which were being degraded in the GAC contactors under anoxic conditions, would be removed under aerobic conditions. The RBOC fraction of TOC was suspected as the major contributor to downstream biofouling. This fraction would be taken up first, leaving the less biodegradable fractions which would not support biofouling to the same extent.
Figure 7: Botany GTP – modified treatment process. Figure 7 shows modifications to the GTP process, including chloramine dosing and reconfiguration of the dual media filters. The GAC contactors were converted to biologically aerated filters (BAFs) one at a time. As each filter was commissioned and ripened, TOC levels in the feedstream to the RO skids were gradually reduced. Figure 8 shows the falling TOC concentrations over the duration of BAF conversion, and the corresponding reduction in chloramine dose required to maintain operation. The BAFs performed in line with expectations, removing approximately 50% of the influent TOC. The GAC contactors removed a further 20% TOC, and continued to remove the non-volatile CHCs to the required levels for discharge. However, recovery of the backwash waste had to be abandoned as the process could not effectively remove the waste biological sludge.
Figure 8: TOC reduction with BAF conversion.
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MAY 2011 107
membranes & desalination Attempts to further reduce the chloramine dose were unsuccessful. A reduction from 2mg/L to 1.5mg/L resulted in deteriorating RO performance.
Flux reduction The design flux for the Botany GTP (24.9L/m2.h for primary, 18.1L/m2.h for secondary) could be considered conservative when assessed against the Filmtec™ membrane system guidelines (2009) for well water (27–34L/m2.h). Although groundwater may normally be classified as well water for the purposes of RO system design, the brackish nature and presence of significant RBOC and upstream biological activity justifies classification as wastewater. The flux design guidelines for conventional filtered municipal effluent are 14–20L/m2.h. Due to ongoing process issues in the upstream clarifiers and media filters, iron residuals of 0.1–0.3mg/L in the RO feed water also contribute to RO fouling. While work continues to improve upstream iron removal, overall permeate flux was reduced to mitigate both iron and residual biological fouling. The GTP currently operates at fluxes 20% below the original design, and overall recovery reduced from 91% to 89%. In addition, interstage balancing has been retrofitted to each skid by installation of flowmeters and manual permeate throttling valves. Table 2 summarises the current operational parameters of the RO process. Due to groundwater extraction yields below prediction, the plant is only required to run at 50% capacity to achieve hydraulic containment. This is achieved by operating two of the four
refereed paper
primary skids and one of the two secondary skids, and maintaining one primary skid and one secondary skid in standby. The fourth primary skid sits idle, without membranes. All the original membrane elements have been replaced over time. Although the originally installed membranes have been subjected to numerous chemical cleans, membrane performance has been maintained. Most of the replaced membranes suffered physical damage, particularly glue line failures. The Toray and Filmtec™ membranes in Figure 10: Salt passage throughout the flush cycle. the primary skids have the flow. Particulate fouling from feed been replaced like-forcontamination is unlikely in the secondary like, while the Filmtec™ BW30-400/34i RO skids, having already passed through membranes in the secondary skids have two stages of membranes in the primary been replaced with BW30-440i membrane skids. However, rising differential elements. With this arrangement, primary pressure, particularly on the second stage RO skid run times now exceed nine of the secondary skids (stage four overall), weeks, and secondary skid run times is the most common initiator for chemical exceed four weeks. cleaning at the GTP. This is attributed to precipitation of residual iron and Periodic Flushing concentration of residual organic carbon Increasing differential pressure between facilitating biological activity, even with the feed and reject streams is caused by a chloramine residual. particulate fouling. Particles accumulate in the feed/concentrate channel spacer The improved run time on the secondary skids has in part been of the membrane elements, restricting attributed to an automated flushing regime. The membranes are flushed with permeate for four minutes every 24 hours. Recovery of differential pressure climb after a flush is not complete, nor immediate, as illustrated in Figure 9. The rise in differential pressure is arrested, and then falls slightly for about 12 hours after the flush before rising again. This response suggests further optimisation of flushing frequency may be possible.
Figure 9: Secondary skid performance with periodic flushing.
108 MAY 2011 water
Successive flushes have a diminishing effect. When the differential pressure reaches an alarm point, a warm water flush is initiated. Permeate is heated to 38˚C and circulated via the membrane CIP system. Each array is circulated separately for 10 minutes, and then flushed for 10 minutes through both arrays to waste. The warm water flush provides a significantly greater recovery
technical features
References Dow Water & Process Solutions, 2009: Filmtec™ Reverse Osmosis Membranes Technical Manual. Form No. 609-00071-1009.
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Water Journal is always seeking quality, well researched technical papers on a range of key and regularly addressed topics. Contributions from suitably qualified individuals are always welcome on these and other relevant topics of interest. Upcoming topics for the August, September, November and December 2011 issues include: August: • Coal Seam Gas Water, including methods using Desalination • Recycling, Operational Experiences • Governance
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The authors would like to thank Associate Professor Greg Leslie from UNESCO Centre for Membrane Science and Technology and Eddy Ostarcevic from Integrated Elements for their specialist advice and hands-on contributions.
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Acknowledgements
Michael Selleck (B. E. Chemical, BSc Molecular Biology) is the Technical Manager at Orica’s Groundwater Treatment Plant, after commencing as a process engineer in 2006. He previously worked for Orica developing and commercialising enzymes for the degradation of pesticides in wastewater.
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The GTP now produces treated water which is used for cooling tower make-up and demineraliser feed applications, with ultimate use in low and high pressure steam boilers and industrial chemical production. This water displaces 4–5MLD of potable water use from the Sydney Water supply.
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The complex and variable feedwater to the Botany GTP is considered unique. However, as the world searches for more water sources to reclaim for beneficial
Fred Barendregt (B.E. Chemical) (email: Fred.Barendregt@kbr.com) is a Principal Process Engineer with KBR. He was seconded to Orica in 2005 to lead the commissioning of the Botany Groundwater Treatment Plant, and continues to lead process development and improvement activities for the plant.
Conclusion
Chloramine dosing, flux reduction and periodic flushing are operational levers used to mitigate the impacts of biological fouling. However, without pre-treatment providing adequate removal of contaminants, the benefits of these levers are constrained.
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Flushing away the fouling layer would be expected to reduce salt passage. However, as illustrated in Figure 10, the reduced differential pressure after a flush (only Stage Two is shown) is accompanied by increased salt passage, and a subsequent reduction as differential pressure rises again.
The Authors
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Concentration polarisation is the increase in dissolved solids at the membrane surface. The formation of a particulate fouling layer increases the concentration polarisation, as back diffusion of salts is restricted by the particulate layer. This generally leads to an increase in salt passage as the membrane-active surface is presented with increasing salt concentration.
use, the lessons learnt in the development of this operation can be applied in a broader context. Pilot trials should be conducted on the whole process train, and for sufficient duration to demonstrate the impact of process upsets or changes on downstream units.
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in differential pressure, and extends the run time out to four weeks. The effect of a warm water flush is illustrated in Figure 9.
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New ArrivAl iN AustrAliAN wAstewAter MArket
SBR (sequential batch reactor technology) is widely introduced in Australia and overseas as a modern wastewater treatment process. The SBR process enjoys growing popularity worldwide and is based on the principle that treatment of wastewater works significantly better under defined volume conditions. Classic sewage plant technologies (i.e. continuous flow plants) cannot provide the same process stability. The more reliable operational performance of SBR plants can cover a wider range of dynamic wastewater discharges arriving at the plant. So far sewage lagoons and ponds were exempt from the benefits of the SBR technology, as constant SBR process volumes were not achievable due to pond geometry and process. Ten years ago, the German Company GAA mbH created a Constant-Waterlevel-SBR process (CWSBR®) for wastewater ponds, introducing a fully operational SBR system for any type of sewage pond. Due to the reduced structural costs and state-of-theart construction, savings are substantial and can be up to 50%. Distributed through GWS Technologies, Townsville and Taupo, CWSBR® pond systems are now also available in Australia and New Zealand. Like the original SBR system, CWSBR® is based on modern PLC technology and was also made possible through
the development of modern synthetic materials and geotextiles, creating the tools for a dynamic pond technology. CWSBR® combines the principles of a standard above-ground SBR plant with the low-cost installation of a traditional lagoon-type treatment plant.
Since batch processes are characterised by periodic changing water levels, common SBR plants use solid tanks or containers as reactors to handle large sewage quantities. In order to transfer SBR technology to a pond structure, replacing concrete walls with an earthworked lagoon, naturally supported by surrounding soils, the initial requirement was to eliminate fluctuations in water level. The CWSBR® system is equipped with “Hydrosails”, which are attached to the pond floor. Fixed floats on the top edge keep the sails upright, enabling the Hydrosails to separate the pond volume into the different SBR reactor zones with the simple difference that the volume changes are operated vertically compared to the horizontal changes in a standard SBR configuration (Figure 1). From the primary treatment zone, the CWSBR® system pumps the water into the activated sludge zone. The Hydrosails follow the change in volume passively. With balanced water tables on both sides of the sails, tension and stress is not a problem as the Hydrosails just move with the alternating flows. As the water table throughout the pond maintains a constant
level at all times, buoyancy problems for the pond liner caused by fluctuating volumes are unknown and slope stability is not an issue.
Development and plants constructed to date The first CWSBR®-plant was built in Germany in 2000 in order to retrofit an existing sewage pond system. After 10 years, GAA’s knowledge and experience with pond retrofitting can be summarised as follows: CWSBR® grants full SBR performance including nitrification, denitrification, phosphorus removal by Bio-P and fully stabilised sludge. The attribute that is typical for SBR technology, highlighting that the treatment success is independent from the plant size, also applies for the CWSBR® systems. To date, new plants sizing from 800 PE to 210.000 PE have been designed and constructed. Upgrades of existing ponds and lagoons have been carried out up to 5.000 PE by retrofitting and extending existing wastewater ponds (Figure 2 and 3).
Figure 2: CWSBR® is a full performance SBR process in the shape of a pond technology, which grants highest wastewater treatment standards.
Figure 1: Comparison of water volume changes of CWSBR® and standard SBR.
Figure 3: CWSBR® system under running conditions, showing aerated zone.
WaterGEMS® and SewerGEMS HYDRAULIC ANALYSIS SOFTWARE TO MAKE WATER SYSTEMS MORE EFFICIENT WaterGEMS and SewerGEMS come equipped with everything engineers need in a flexible multi-platform environment, from automated fire flow and water quality simulations, to criticality and energy cost analysis, to automated design, bottleneck detection, and water loss analysis. These applications are part of Bentley’s integrated water solution which addresses the needs of owner-operators and engineers who contribute to the infrastructure lifecycle. For more information, see the inside front cover of the May issue of Water Journal, visit www.bentley.com/AWA, or e-mail sales.haestad@bentley.com.
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new products & services Short construction time For retrofitting projects, an average construction time of three months has been established. New CWSBR® plants are typically constructed within three to six months depending on size and local conditions. As the CWSBR® system is a high-end wastewater treatment process, increasing the treated volume per time ratio substantially, approximately 70% of the total pond area will be available after the upgrade for other tasks such as stormwater retention or further sludge stabilisation processes. Existing buildings and structures will be incorporated in the design and used for the installation of the plant equipment. The decisive argument for a CWSBR® installation is the low investment to establish a state-of-the-art, full-scale SBR technology, where costs can be less than 50% compared to a standard aboveground SBR plant. Other cost advantages derive from OM advantages like the elimination of expensive pond sludge removal every five to seven years, which is replaced by continuous sludge stacking in a separate bed. Whereas energy demand for wastewater aeration is comparable to standard SBR plants, the cost for circulation pumping is reduced by 35%. This reduction is derived from the constant water level which requires the pumps to only overcome friction losses with no static head involved. Also, an important advantage of CWSBR® compared to classic SBR is the decrease of the required time for sedimentation and decantation. In the classic batch process the SBR zone is a homogenous mixture of water and activated sludge. After the treatment process, the sludge settles and a clear-water zone is established. This is separated from the sludge zone by a floating decanter, which follows the sludge
level until it has reached the minimum level of fill in the SBR reactor. In a CWSBR® plant with constant water level the decantation is performed without changes in the water level. As a result the decantation device operates at a greater distance from the sludge zone and a very good water-sludge separation can be achieved even at a high flow decanting velocity. The stability of the microbiological mixture in a CWSBR® system allows complete nitrogen elimination even at low BOD intakes (Table 1). CWSBR® systems operate well within the Environment Waikato operating guidelines for Nitrogen reduction and show a constant high level of performance at substantially less CE and OM cost.
Large CWSBR® plants The largest CWSBR® plants to date have been built in China for up to 210.000 population equivalents (PE). The latest plant was commissioned in 2010. With the size of those plants the CWSBR® system is now established as one of the world’s largest SBR systems, and has found its way from use in rural environments into the wastewater management of big cities. As already established for the smaller plants, the large plants are constantly showing the same treated effluent quality. CWSBR® systems are the first choice when it comes to building new plants or retrofitting and upgrading existing sewage ponds and lagoons to the standards of the largest SBR-plants at low cost. Ten years’ experience in building and operating CWSBR® plants have shown that this low price SBR alternative meets all expectations of modern wastewater treatment. CWSBR® applications are now established throughout the world ranging from 800 PE up to 210.000 PE
Table 1: Stability of nitrogen elimination within a CWSBR® plant in Nauroth-Mörlen, Germany (August 2010). Influent [mg/l] August 6
demonstrating that the CWSBR® system and its simple form of construction can be adapted to all rural and municipal wastewater treatment applications. The efficiency of wastewater treatment including the elimination of all relevant wastewater components was continuously demonstrated at a high level of reliability.
Effluent [mg/l]
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Figure 4: A large CWSBR® plant under construction.
PArticle ANAlyser reveAls HiddeN cHArActeristics of oPAque PArticles The new FlowCAM Front-Fill IlluminationTM particle imaging and analysis system from Fluid Imaging Technologies (www. FluidImaging.com) is the world’s first to feature bidirectional front and back lighting, which illuminates the surfaces of opaque particles and reveals their true colours and textures. Replacing two-dimensional black silhouettes with three-dimensional images, it combines both brightfield and darkfield microscopy in a single unit to precisely determine the actual size and shape of the particle detected, while automatically characterising and identifying each particle. Surface imperfections and defects, foreign matter, agglomerations, discolourations and other attributes previously invisible are revealed in seconds. While brightfield illumination works well for transparent particles, opaque particles create a “silhouette” image because they completely block the illumination coming from behind the particle. With FlowCAM Front Fill IlluminationTM, detail on the particle side facing the camera can be revealed. Front-Fill Illumination marks the latest advance in imaging particle analysis systems. The FlowCAM takes high-res
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Brightfield image of Teflon® particle on left. On right, another Teflon particle after adding Front-Fill™ illumination. digital images of particles and organisms in a fluid, measures each one in real time based on dozens of parameters, and automatically differentiates and classifies them for analysis. Praised by research scientists and water quality engineers and cited in peer-reviewed journals, the FlowCAM is used in a range of industries such as food, beverage, pharmaceutical, biotechnical, marine and water.
At EcoCatalysts we’re the experts at reducing your wastewater treatment costs. We can save you up to: 30% on energy costs 20% on sludge reduction 25% on maintenance costs We can also reduce your remediation time by up to 6% per day on hydro carbon contamination.
Visit us at Stand 22, learn how we can help you reduce your operation costs by up to 30%
While there, enter into the draw to win a BBQ Hamper. Hamper includes Portable BBQ, BBQ Tool Kit, Glenn McGrath Cookbook & much more!
For more information contact Bryn McDonagh, ATA Scientific, on (02) 9541 3500, or email: enquiries@atascientific.com.au
westerNPort wAter uses wAtergeMs to AcHieve AutoMAted distributioN Westernport Water provides water, wastewater and recycled water services to nearly 16,000 properties on Phillip Island in the state of Victoria, and an area of the mainland from The Gurdies to Archies Creek. Using Bentley’s WaterGEMS water distribution modelling software integrated with a geographic information system (GIS) and supervisory control and data acquisition (SCADA) system (both introduced into the utility in the past two years), Westernport Water’s managers were able to achieve a high-performance, automated system. This targeted investment in new technologies is currently delivering substantial cost savings and contributes to the effective operation and management of more than $43 million in water assets. The Open Spatial GIS, in conjunction with WaterGEMS, enables simple and easy updates of the system, including all new subdivisions. The Control Microsystems SCADA system allows field-measured data to be brought directly into WaterGEMS using the modelling software’s SCADAConnect and Darwin Calibrator modules.
Since SCADAConnect can use both historical and real-time data, the model is constantly up to date, but also has tables of previous values for trending and projections. This means that flow, pressure and tank-level data for each demand zone can be fed on a real-time basis, enabling the system to model real-world conditions. Using the imported SCADA values, Darwin Calibrator, and the demand inversing tool in WaterGEMS, Westernport Water engineers can proportionally change the demand values assigned to those nodes within each demand zone. This innovative first for the water industry in Victoria allows the model to continually update demand groups. As a result, all calculated values in the water model are more accurate, since the exact flow from the SCADA system is used to calculate, for example, velocity, losses, and system curves. An up-to-date and accurate model gives engineering design and operational personnel the best possible platform for decision making.
Cost benefits, efficiency and environmental improvements Previously, Westernport Water had engaged the services of external contractors to manually upgrade and calibrate its water model. The SCADAConnect technology with real-time updates will save Westernport Water the cost of these calibrations, which came to around $80,000. Additionally, the WaterGEMS water model will help deliver savings in leak detection by measuring and identifying nonrevenue water. Westernport Water aims to achieve a 25% reduction in water losses and recover up to $85,000 (retail value) of water. Reducing water losses also means that less water will need to be pumped to customers to achieve the same level of service, so carbon emissions will be reduced as well.
low-cost, HigHly soPHisticAted ANAlyser/coNtroller froM Pi For water engineers, many modern controllers and analysers provide just too much in terms of standard features that need to be paid for. For this reason Pi has developed the CRONOS, a highly sophisticated multi-lingual controller that is both simple to use and low in cost. The new controller follows the maxim “everything you need – and nothing you don’t”. CRONOS does indeed have everything you need in an analyser/controller, with up to three universal inputs and up to three universal analogue outputs, up to four relays and options for Profibus, Modbus, LAN and other comms protocols.
For more information call us on 1800 244 009 or email info@ecocatalysts.com.au
112 MAY 2011 water
Westernport Water’s water model importing field data captured by its SCADA system, using WaterGEMS’ SCADAConnect.
The user interface is highly intuitive and comes equipped in multiple languages and a set-up wizard for ease of use.
water business
new products & services types of fouling such as permeate flushing and acid/alkaline cleans. However, in spite of a well prepared operating system, occasionally incidents occur that require significant engineering and investigation to remediate. The Yabulu WRF has experienced both major types of fouling, organic and inorganic.
Organic fouling Each analyser/controller is built to the customer’s specification so the customer is only paying for the functionality they need and not for the functionality they don’t. A multi-colour backlight means that alarm conditions are clearly visible for up to 100 metres. The CRONOS is available as a residual chlorine analyser, a swimming pool controller, a DO meter, a pH meter, an ORP meter, a suspended solids meter, an ozone analyser and chlorine dioxide analyser. For more information please visit: www. processinstruments.net/products/cronos. php or contact George Benca, National Sales Manager, Bintech Products on (03) 9467 7300 or email: sales@bintech.com.au
MANAgeMeNt of ro MeMbrANe fouliNg At tHe yAbulu wAter recycliNg fAcility TRILITY Pty Ltd operates and maintains the Yabulu Water Recycling Facility, where they utilise Reverse Osmosis (RO) membranes to treat tailings water from the Queensland Nickel ore refining facility. These membranes are subject to a wide array of both organic and inorganic fouling that must be managed effectively so the treatment process is not impaired. Fouling is a common hindrance across all membrane processes. No matter the membrane size, type or process application, fouling is always an important factor to consider in the design and operation in membrane processes, as there are a wide array of mechanisms for it to occur. An increase in fouling can lead to a number of detrimental events such as increased breakdowns and equipment failure, as well as the deterioration of both quality and quantity of water produced.
The first major fouling incident was caused by organics. After an extended plant shutdown to undertake installation of new 8-inch membranes, it was noticed upon plant restart that there were higherthan-usual Differential Pressures (DP) being experienced in the system.
Figure 2: Fouling on an RO feed pump that has been removed and partially cleaned.
Further investigation revealed organic fouling, believed to be a form of iron bacteria, which had grown on almost every internal surface. These organics formed a slick coating on all pipe walls, pump internals, and the faces of the lead membranes within each train (Figures 1 and 2). The build-up of these organics on the membranes themselves led to the increased operational pressures experienced, and required removal.
Initially, the biocide DBNPA (2,2-dibromo3-nitrilopropionamide) was dosed into the system to kill the bacteria and inhibit further growth. This worked effectively in neutralising the bacteria; however, remnants of the organisms still existed physically within the system. Although no longer viable, another issue was created due to the now dead bacteria coating detaching from the WRF internals in ‘flakes’ and causing greater physical blockages of the membrane faces (see Figure 3). As a result, the entire WRF internals were pressure cleaned and flushed to remove all traces of the organic foulants.
Figure 1: The level of fouling of the Yabulu Refinery WRF internal systems by iron bacteria. This photograph was taken at the discharge side of an RO feed pump.
Figure 3: Organic fouling after biocide dosing. Note the patches of pipework where the bacteria have ‘flaked’ off.
The Yabulu WRF membranes are subject to water of varying extremes, and because of this their operation and maintenance needs to be heavily monitored. Tailings water from QN Yabulu Refinery is variable in its constituents, containing varying levels of heavy metals, organics and inorganics. The Yabulu WRF has systems in place to prevent the more common
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new products & services Huber disc tHickeNer
To prevent the same issues recurring, system shutdowns are kept to a minimum length of time, and a number of internal areas are inspected prior to restarting the system after a prolonged shutdown to check for bacteria growth. Biocide and associated dosing facilities are also kept on site in case they are required for future use.
The Huber Disc Thickener is a unique sludge thickening machine designed for smaller municipal and industrial treatment plants. Applications include thickening of waste-activated sludge, primary sludge and all sludge types produced in the sewage, food processing, brewery, meat processing and dairy industries.
Inorganic fouling The second major fouling incident involved high levels of inorganic sulfates being discovered within the system. This caused fouling of the lead membranes of each of the trains and created an increase in operational pressures. At one point there was, in fact, significant organic and inorganic fouling of the membranes simultaneously (see Figure 4).
Figure 4: Showing both organic and inorganic fouling on the face of an 8-inch lead membrane. The presence of these sulfates was thought to have been a product of higher levels of sulfates within the influent water. This formed a varying amount of sulfate salts with other available ions within the system. The increased level of sulfates quickly fouled the lead membranes to such a large degree that they could not be easily cleaned using the usual mechanisms. To add to this, it was also discovered upon inspection that there was a slight amount of fouling attributed to ABS swarf from recent pipework modifications that involved both cutting and drilling of the pipe, which had partially blocked and damaged a number of lead membranes. The high pressure experienced within the system resulted in the swarf deeply embedding itself within the membrane faces, separating the wound sheets and reducing effectiveness (see Figure 5).
Figure 5: Sulfate and swarf build-up on the face of one of the 8-inch membranes. It can be seen towards the centre that the membrane sheets are beginning to separate due to the swarf embedding. The lead membrane faces were pressure cleaned to remove all visible fouling, although this did not reduce the deeply embedded sulphate compounds within the lead element. Under guidance from membrane suppliers Woongjin and Australian representative Vitachem, the lead membranes were swapped with the lag membranes and rotated 180 degrees so the 20-bar operating pressure would effectively ‘blow’ the fouling out the back end of the system, with the membranes to be returned to their original positions after a short period. Due to the variable nature of the influent water, sulfate salts and other inorganic foulants always have the potential to appear within the system regardless of the preventative measures in place. To help combat this, an asset management strategy has been put in place where the lead membrane in each operational vessel is replaced on an annual basis. This aims to control the flux and operational pressure, resulting in a more balanced and consistent operation.
Depending on the sludge type, the capacity ranges from 10–38 m3/h. Typically sludges can be thickened to 6%, resulting in a volume reduction of up to 75%. The unit can handle an influent solids concentration of 0.2–3% w/w solids.
The Disc Thickener is totally enclosed, which contains aerosols and odours. The main case includes inspection hatches for visual examination of the thickening process. The main case, filtration disc and supports are fabricated in stainless steel, which allows the machine to be installed outdoors. The machine offers two sizes, with the biggest size being 2013mm in diameter, significantly smaller than other thickener types for the same capacity. Operating costs are minimal due to low power consumption.
Fouling is always going to be an issue with RO membrane systems, with the type and level of fouling differing depending on the site, environmental and process applications. It is important to ensure that comprehensive preventative measures and routine maintenance procedures are in place, as it is much easier and less costly to prevent a fouling incident than to fix it. This article was supplied by TRILITY Pty Ltd (previously United Utilities Australia). For more information contact amedlock@ trility.com.au
We harvest cool drinking water at extreme temperatures from salty sea, river, well or brackish water using just solar energy – without motors. For more information visit:
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new products & services Sludge is conditioned in a flocculation tank fitted with a stirrer. The flocculated sludge overflows by gravity to the Disc Thickener. The sludge is then drained over the circular filtration disc. As the disc rotates, the sludge is transported to the machine’s outlet. A stainless steel mesh is used as the filtration medium. This provides efficient drainage of the sludge and has a long life due to its rigid construction. The mesh requires wash water for cleaning, but unlike other thickener types, the wash water is directed back into the thickening side of the main case, resulting in high capture rates. The output speed of the disc is 4.5 rpm, which results in low life-cycle costs. Plows can be used to create additional drainage paths for certain types of sludge. The outlet of the machine contains a unique baffle plate that applies a gradual pressure to the sludge mass, resulting in maximum thickened sludge concentration. Huber manufactures the Disc Thickener in Germany and Ovivo Australia is the exclusive agent for Huber Technology in Australia. Contact (02) 9542 2366 or visit: www.ovivowater.com.au
The Rocla® CDS3030 is designed to treat up to 1700L/s of runoff, removing around 99% of gross pollutants and over 70% of sediment, resulting in more than 2.5 tonnes of rubbish a year being removed from the catchment. With a footprint of 7m x 5m it is the largest CDS® Unit in Queensland. The 3m-diameter continuous deflective screen has an effective screening area of almost 30m2 to treat stormwater. The unit was designed by Rocla using SWATT® modelling software, in conjunction with Stockland’s engineers, KN Group, to treat first flush volumes from severe storm events, before draining the treated stormwater into a bio-retention basin. Removing all of the gross pollutants and most of the sediment with the CDS3030 Unit will protect the bio-retention basin and maintain its environmental function. The large pollution storage provided by the unit ensures that maintenance by the Moreton Bay Regional Council will be minimised to a single annual clean.
giANt gPt keePs sAtellite city greeN A massive Rocla CDS® gross pollutant trap is helping to fulfill the green ambitions of the North Lakes development, a virtual satellite city 25km north of Brisbane. The Stockland master-planned community, which began in 1999, is a new suburb covering more than 1000 hectares that will be home to 20,000 people, with retail, commercial and industrial areas providing employment for some 13,000. It also includes an 18-hole golf course, a retirement village, parklands and wetlands.
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The HydroGuard HG-702 performs colorimetric testing in a closed self-cleaning colorimeter cell and is the only system that automatically and accurately measures chlorine residuals using small amounts of reagent, around 0.03 mL per sample.Once installed and calibrated, HydroGuard is fully automatic. It will monitor and control dosing systems directly or indirectly, releasing the proper quantity of chemicals based on frequent automatic measurements. The HydroGuard HG-702 is simple to use. Its straightforward control panel and parameters menu make chemical balance control an easy task. All basic information can be viewed at a glance, and changing settings is as simple as scrolling through the menu and adjusting the current settings.
ANy coMbiNAtioN of MeAsureMeNts iN A siNgle uNit
Many CDS® Units have already been installed at North Lakes, treating stormwater runoff from residential and commercial areas. The Rocla® CDS3030 Unit, the largest to date, is located in the North Lakes Business Park, Stage 6, which comprises four lots covering approximately 22 hectares, most of which will be hard surfaces. The Park began construction in 2007 and the $130 million development will ultimately cover 55 hectares and is expected to create 5000 jobs.
chemical balance are neither objective nor effective. The HydroGuard HG-702 measures Free or Total Chlorine (and optionally both Free and Total Chlorine), utilising the proven DPD colorimetric method with a digital photometer. Additional measurement parameters can be optioned for Turbidity, Conductivity, pH and ORP, Temperature and Flow Rate.
For more information contact Jeremy Bell, Thermo Fisher Scientific, on 1300 735 295, email: InfoWaterAU@thermofisher.com or visit: www.thermofisher.com.au
The HydroGuard HG-702 Water Quality Analyzer from Blue-I Water Technologies continuously monitors chemical levels in process water applications. The HydroGuard HG-702 automates free chlorine and total chlorine determinations with options for pH, ORP, temperature, turbidity, conductivity and flow rate.
lAtest HeAdworks systeM PAckAge foM cst
Various methods have been developed over the years to monitor the concentration and balance of chemicals used in water treatment, particularly residual Chlorine. The older, manual methods of monitoring
MELBOURNE Peter Everist 03 9863 3535 peverist@wigroup.com.au
SYDNEY Hugh McGinley 02 8904 7504 hmcginley@wigroup.com.au
BRISBANE Hugh McGinley 02 8904 7504 hmcginley@wigroup.com.au
ADELAIDE Owen Jayne 08 8348 1687 ojayne@wigroup.com.au
A pre-engineered packaged wastewater headworks system combining screening, grit removal and grit washing into one integrated system is being introduced to Australia by CST Wastewater Solutions. The PISTA® WORKS™ headworks package is the latest innovation
wigroup.com.au
water
MAY 2011 115
new products & services from Smith & Loveless, a world leader in municipal, government and industrial wastewater technology represented in Australia by CST Wastewater Solutions.
P ENS TO CK S S TO P B OA RD S BULKHEADS
The package incorporates the PISTA® wastewater grit removal chamber, which extracts an unprecedented 95 per cent of grit as small as 100 microns, says CST Wastewater Technology Managing Director, Mr Michael Bambridge. The system is pre-assembled and shipped direct to the job site, significantly reducing field-installation costs while allowing for a compact footprint.
Package components also include flanged connections, a 5mm fine auger screen, manual bypass bar screen, two platforms for easy equipment access, and epoxy-coated carbon steel skid support for the complete system with concrete fill. Additionally, the system comes with a PLCbased control system with touch screen, colour HMI interface and panel to operate the entire system. For further information, please contact Mr Michael Bambridge, Managing Director, CST Wastewater Solutions on (02) 9417 3611 or email: info@cstechnology.com.au
All equipment components are constructed of stainless steel and utilise multiple patented technologies including world-class grit removal technologies PISTA® 360™ with V-Force Baffle™, S&L Turbo Grit Pump and the PISTA® TURBO™ Grit Washer featuring Tri-Cleanse Technology™.
AD VE RTIS E RS ’ IN D E X Acacia Filtration Services Acromet ADS Environmental
113 33 8
Airvac
15
Aurecon
21
Australian Vinyl
47
AWMA Water Control Solutions
7
AWMA Water Control Solutions 116 Bentley Systems, Inc
IFC
Bentley Systems, Inc
110
Brown Brothers Engineers
26
By-Jas Engineering
33
Challenger Valves and Actuators City Water Comdain Infrastructure
DESIGN MANUFACTURE I N S TA L L Ph 1800 664 852 www.awma.au.com
116 MAY 2011 water
Industry Capability Network (ICN)
55
International Water Centre/ River Symposium
53
Irrigation Australia
62
ITT Fluid Technology
11
ITT Water & Wastewater
IBC
James Cumming & Sons
93
Ludowici Watergates
27
Magytec International
111
Merriman
19
Plasson Australia
13
Projex Group
26
Promains
9
17
ProMinent
20
71
Rockhampton Regional Council
28
5
Solarwasser
114
Cromford Group
31
Tenix
41
Detection Services
25
Thermo Fisher Scientific
37
TRILITY
24
EcoCatalysts Franklin Electric
112 OBC
Tyco Water
3
GWS Technology
34
Water Infrastructure Group
Heraeus
59
Weidmuller
115 29
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