Water Journal February 2009 by australianwater

Volume 36 No 1

FEBRUARY 2009

AWA JOURNAL OF THE AUSTRALIAN WATER ASSOCIATION

Water loss is a US$14 billion problem.

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HAMMER 111 - r ed uc es breakages caused by high pressure t ransients.

Bentley111 Water - identifie s aging infrastr ucture and enab les reme diation planning strat eg ies.

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Journal of the Australian Water Association ISSN 0310-0367

Volume 36 No 1 February 2009

contents REGULAR FEATURES From the AWA President

From Challenges to Solutions

From the AWA Chief Executive A New KISS Principle?

D Barnes 4 T Mollenkopf 5

J Gill AO 6

My Point of View

Crosscurrent

R Knee 14

Aquaphemera

Young Engineer of the Year - see page 20

Industry News

AWA News

Events Calendar

FEATURE REPORT

Sustainability and Climate Change - Water Sector Response 52 It is clear that the water sector is one of the first impacted by climate change. This also means it has to be one of the first to respond. Clare Porter looks at how. CPorter People Will Drink Recycled Water - just Keep Them in the Loop 58 In media outlets Australian's appear to be polarised about drinking recycled water. But is this really so? A Hurlimann Water Quality Research Australia Limited (WQRA) 60 The water industry's baby is off and running. DHalliwell, J Dawe, AGackle, MAkeroyd Symposium on Water Reclamation and Reuse: Korea Pursues Recycling AWA CONTACT DETAILS Australian Water Association ABN 78 096 035 773 Level 6, 655 Pacific Hwy, POBox 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 opinion or statements of facts 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 media@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: February, March, May, June, August, Septem ber, November and December. EDITORIAL BOARD Chair: Frank R Bishop; Dr Bruce Anderson, ENSR Australia; Dr Terry Anderson, Consultant SEWL; Greg Finlayson, GHD; Robert Ford, Central Highlands Water (rtd); Anthony Gibson, Ecowise; Dr Brian Labza, Vic Health; Professor Felicity Roddick, RMIT University; Mike Muntisov, GHD; David Power, BEGA Consultants; Dr Ashok Sharma, CSIRO; and Bob Swinton, Technical Editor.

AWA

EDITORIAL SUBMISSIONS Water Journal welcomes editorial submissions for technical and topical articles, news, opinion pieces, business

62 J Radcliffe

Saving Water Key to Reducing Energy Use - see page 24

information and letters to the editor. Acceptance of editorial submissions is at the discretion of the editor and editorial board. • Technical Papers and Features Bob Swinton, Technical Editor, Water Journal- bswinton@bigpond.net.au ANDjournal@awa.asn.au Papers 3,000-4,000 words and graphics; or topical articles of up 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 3 column 'magazine' format rather than the full-page 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 need to be numbered with the appropriate reference in the text e.g. see Figure 1, not just placed in the text with a (see below) reference as they may end up anywhere on the page when typeset. • Industry News, Opinion pieces and Media Releases Edie Nyers, Editor, Water Journal- journal@awa.asn.au • Water Business and Product News Brian Raul!, National Sales and Advertising Manager, Hallmark Editions - brian.rault@halledit.com.au

ADVERTISING Advertisements are included as an information service to readers and are reviewed before publication to ensure relevance to the water sector and objectives of the AWA. Brian Raul!, National Sales and Advertising Manager, Hallmark Editions - brian.rault@halledit.com.au Tel: +61 3 8534 5014 AWA BOOKSHOP Copies of Water Journal, including back issues, are available from the AWA Bookshop for $12.50 plus postage and handling. Email: bookshop@awa.asn.au PUBLISHER Hallmark Editions, PO Box 84, Hampton, Vic 3188 Tel: 61 3 8534 5000 Fax: 61 3 9530 8911 Email: hallmark.editions@halledit.com.au

OUR COVER The environmental benefits of pressure sewerage are manifest both for installation of mains and during the customer connection (pump installation) process. For the Flinders/Shoreham backlog project, the consultative process employed by 'us' - Utility Services resulted in an 85% vol untary uptake of connections in the first year. See page 68. Photo courtesy of 'us' - Utility Services.

water FEBRUARY 2009 1

from the president

From Challenges to Solutions David Barnes AWA President

"Ozwater 2009's theme 'From Challenges to Solutions' acknowledges the emerging and current solutions for the many challenges facing the water industry, such as climate change, water shortages and skills shortages. These solutions are essential to ensure sustainability, not only for water but tor the whole planet." (Allen Gale, Chairman, Ozwater09) Some 12 keynote speakers and over 200 presenters encompassing experiences, challenges and solutions from within Australia, Europe, Asia, the Indian sub-conti nent and the Americas are presenting under the themes of integrated water management, water and wastewater systems and processes, policy, strat egy, and emerging technolog ies and research. It is particularly interesting to observe that there are centres of expertise throughout the world and beyond the more traditional centres in Europe and North America. I am especially looking forward to hear from Professor Kim from the Gwangji Institute of Science and Technology in Korea. He has a wide range of tech nical interests that include formation of biofilms in membrane bioreactors, anaerobic processes, bio generation of hydrogen, and the development of rapid pathogen biosensors using nano particle technology. All fascinating emerging technologies in water management. In addition, I am pleased to not e that interest in the extensive Ozwater09 trade exhibition that has has been enormously positive, reflecting the value that the whole industry places on the opportunity to observe fi rst-hand the goods and services available. The majority of the 200 available exhibitor spaces were already booked before Christmas. Experience suggests that the exhibition area provides unrivalled networking opportunities in addition to access to technology and service providers, and thus is an essential part of the Ozwater experience. In addition to the well established technical, trade, techn ical tours, social and networking events there will be some additional activities that include: The Young Water Professionals workshop looking at Water and Life in a Changing World - Facing the Challenges of Climate Change. The guest speaker Anna Rose is the founder and coordi nator of the Australian Youth Climate Coalition and has represented Australia in national and international forums.

4 FEBRUARY 2009 water

No doubt this workshop format will provide an effective a methodology to gather opinions and develop useful outcomes. The community event 'Have 2g0' is being held in Melbourne's City Square on Sunday 15 March. The aim is to raise awareness of water issues in Vict oria and the rest of Austral ia. It wi ll showcase a series of interactive displays and provide a forum for some of our water leaders to discuss issues with the community that our sector serves. Several sessions of mini presentations have been included within the main conference programme. These offer a short platform presentation opportunity to develop the key outcomes from selected poster authors. I am also looking forward to the brand new electronic posters, in what will be one of the first applications in Australia of this sophisticated method of presentation. A series of screens will be provided and individual posters can be displayed from the associated computer. Th is provides not only a modern format to display informat ion but direct email access to authors at all times. This will raise the importance and profile of the post er programme and provide a genuine contribution to the information exchange. To further quote from Allen Gale, "Ozwater09 has all the ingredients to continue the internationally-acclaimed conference and exhibition established by previous Ozwaters. The only other ingredient is you - the delegates. I invite you to come along and contribute to the solutions required to the many challenges faci ng the Australian and international water industries."

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Join us for a cocktail at Ozwater on Tuesday March 17 from 3:30 - 4:30pm, booth XS. www.veoliawater.com.a u

feature article - sustainability and climate change

SUSTAINABILITY AND CLIMATE CHANGE - WATER SECTOR RESPONSE Clare Porter, AWA Sustainability Manager There is a high level of awareness about climate change and sustainability and it is clear that the water sector is one of the first impacted. This also means that t hey are one of the first able to respond ... But, is this happening, and how is this happening? The Australian Water Associat ion (AWA) conduct ed research in November 2008 to find out.

organisations. Additionally, there was also equal representation from organisations ranging from the smaller companies and councils, through to the larger utilities and consultancies.

Organisation Type

Survey q uestions were drafted, reviewed and placed on an online su rvey tool. Notifications were t hen sent out t hrough the AWA networks and participants were given 2.5 weeks to respond to the 40 questions under t he following headings:

• Consultancy

• Organisational profi le

• Supplier

• Addressing corporate sustainability

• Government

• Response to climate change

• Water Authority

• Engagement, barriers & pathways, and

• Other

• Prioritising opportunities More than 100 responses were received representing 82 organisations from across the water sector around Austral ia and New Zealand. Responses were collated to represent individual and organisational results.

Addressing corporate sustainability and response to climate change

Organisational profile

Respondents were asked to rank their progress on addressing

Survey respondents represented a good cross-section of organisational type, w ith an equal balance from consultancies, suppli ers, government, water authorities and a number of other

corporate sustainabi lity and responding to climate change, and

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feature article - sustainability and climate change Work already completed on climate change and corporate sustainability

Question

Respondents were asked a series of questions in relation to work already undertaken on both cl imate change and corporate sustainability. The average results are outlined in the table. Organisations were most likely to have conducted a baseline inventory of emissions, developed an action plan or strategy, followed by adopting an emissions reduction target. The lowest score was forecasting emissions into the future. In terms of implementing activities to reduce emission, the highest ranked activity was energy efficiency initiatives, with employee and stakeholder engagement closely following. Most work within organisations in terms of corporate sustainability was assessing water use, closely followed by waste production and energy use. Fleet and/or transport impacts and impacts on biodiversity came in last on what organisations were acting on. Not surprisingly, most work had been undertaken within the social field with the highest results for occupational health and safety, training and education and equal opportunity and diversity. Respondents were asked to rank progress with incorporating environmental, social and economic factors into project management. Results showed more favourably at the beginning and end stages of project management, with a dip during manufacturing and constru ction.

Triple Bottom Line Assessment in Phases of Project Management

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Engagement, barriers & pathways Most organisations had engaged with their employees on some level regarding sustainability and climate change with a response of 74%. Many initiatives evolved from an initial green team, climate action team or sustainability team and included activities like presentations, bulk purchase arrangements for useful products for the home, staff newsletters, movie nights, training and prizes. A common initiative was to link in to already established external events like Ride to Work Day, the An nual Energy Week and Earth Hour. Success was based around senior management support and st aff time being allocated to the activity. An initial survey helped organisations to assess the needs of the empl oyees, and in some cases, success was linked to the enterprise agreements.

Prioritising opportunities In terms of prioritising opportunities for AWA, 84% of respondents were supportive of AWA taking a leadership position within the corporate sust ainability and climate

56 FEBRUARY 2009 water

Average Result

Has your organisation:

Conducted a baseline inventory of emissions Developed an action plan or strategy Adopted an emissions reduction target Forecast emissions into the future

Underway Early Stages Early Stages Early Stages

Has anything been implemented to reduce emissions?

Energy efficiency initiatives Engagement with employees Engagement with stakeholders Investment in new technologies A process to avoid emissions in the first place Utilising waste streams Engagement with community Investment in renewable energy Purchasing offsets

Underway Early Stages Early Stages Early Stages Early Stages Early Stages Early Stages Early Stages Not yet Started Not yet Started

Carbon capture / storage Has your organisation identified and/or addressed?

Organisational, operational or direct environmental impacts Underway Office based environmental impacts Underway Indirect, sector wide or third party environmental impacts Early Stages Has your organisation identified, reduced and recycled (where appropriate) the following:

Water use

Underway

Waste production Energy use

Underway Underway Underway

Materials selection / use Fleet and/or transport impacts Impacts on biodiversity

Early Stages Early Stages

Does your organisation have the following employee programs in place?

Occupational health and safety Training and education Equal opportunity and diversity Work / life balance Ideas and innovation programs Mentoring opportunities Access to fundraising opportunities Access to volunteering

Advanced Advanced Underway Underway Underway Underway Early Stages Early Stages

change arenas. Mostly respondents were interested in best practice examples, benchmarking capabilities and network ing through formalised groups like the already established Specialist Networks for Sustainability Practitioners and Climate Change.

Conclusion It is clear that work is already underway in both respondi ng to climate change and corporat e sustainability but there is certainly interest and enthusiasm for learning more from each other. The challenge for an organisation like AWA is to bring all of these interests and knowledge groups together and assist the industry to remain responsive to the challenges that lie ahead. More comprehensive information from the survey is available in the 'Programs' section of the AWA website.

feature articles

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feature article - recycled water

PEOPLE WILL DRINK RECYCLED WATER - JUST KEEP THEM IN THE LOOP

Dr Anna Hurlimann is a senior lecturer in urban planning at the University of Melbourne with a particular research interest in water policy and public attitudes to water. The water crisis has changed ou r attitude to this precious resource. In 2005 I was invited t o present at a federal parliamentary library seminar on recycled water. I had a bottle of NeWater - the Singaporean recycled water product - at the ready to see if anyone wanted to try it. I thought t his would be a good icebreaker, but I got more than I bargained for. One well-known minister scampered up the front for a taste , w hile another stayed at the back quizzing me intently as to how I had smuggled t his contraband into the country - as if quarantine officials wou ld have any interest in a smal l bottle of water! Would you have tried the recycled water? The use of recycled wat er for drin king purposes already occurs in many parts of the world, including Australia and Victoria (as acknowledged on page 52 of the Victo rian Government's Central Region Sustainable Water Strategy). In many media outlets, and in public policy documents, Australians appear to be polarised about drinking recycled water, but is t his really so? In the past six years of my research - perhaps as the drought has worsened and discussion of recycled water in the media has increased - a sign ificant c hange has occurred in people's opinions on drinking recycled water.

58 FEBRUARY 2009 water

Mawson Lakes is a "greenfields" suburb in South Australia. Its residents were among the first in the country to use recycled water in a "third pipe" system that services toilets, gardens and car washing. In 2002, only 2 per cent of the residents said t hey'd be willing to drink recycled water. Five years later, after they'd been using the third pipe for two years, 58 per cent indicated t hey'd be willing to drink recycled water, and an additional 12 per cent were undecided. This increase in support for drinking recycled water can be explained by a number of factors - an important one is that these people have had positive experiences with recycled water for nondrinking uses. Further research, conducted with people who wi ll soon be working in office buildings where recycled water systems are being installed, has indicated similar results. In 2006, 42 per cent said they would be willi ng to drink recycled water; by 2007 this had risen to 47 per cent. A significant factor in the acceptability of such water for drinking is usually experience with water reuse. Other factors that have been found to influence acceptance of recycled water use are: trust in the water authority, perception of fairness in terms of price, belief they are being properly informed, and belief that there is no risk. These findings have important public policy implications. It indicates that the manner in which agents interact w ith t he public can influence acceptance outcomes. This is also demonstrated by the experience of fai led projects internationally. The way in w hich the community is engaged, and the way in w hich its w ill ingness to drink recycled water is elicited is influential. In regional Victoria, people were asked not on ly about their willingness to drink recycled water, but also of t heir w illingness to drink recycled water that had been "added to the drinking water reservoir/river after treatment ". Acceptance increased from 42 to 56 per cent. This demonstrates that the context of the question, and of the proposed

project , can have important implications for wi llingness to drink recycled water. When dilution is made explicit, acceptance increases. In a recent national study by the universities of Melbourne and Wo llongong, 90 per cent of people said that if the d rought worsened they would consider drinking recycled water. The same percentage said t hey would drink desalinated water for t he same reason. In focus groups about drinking recycled water, the group is t ypically d ivided 50:50 at the beginning. Commonly, the discussion unfolds with a few people sayi ng t hey drank recycled water in London, or that their septic tank used to be located near the dam or well on their farm. Others confess that they once found 10 dead mice in t heir water tank. They say they don't have a problem w ith drinking recycled water as they have done it before. It is commonplace that ot hers, originally against the idea, then say that perhaps recycled water is someth ing t hey just have to get t heir head around. Public discussions about our water future are critical, as are c lear explanations of the context and implications of proposed projects. Public demonst ration projects wi ll be crucial in allowing the public t o experience recycled water. Reducing our consumption of water is paramount. Only by reducing our demand for all sources of water (including recycled water and groundwater) will we reach a truly sustainable, long-term and cli matechange - resilient approach to water management. For this reason , community engagement should now focus on better understanding the long-term ecological and economic impacts of desalination. We must question whether this public infrastructure project should be bui lt.

This article was first published in The Age (Fairfax) on 12 December 2008. Page 17. Kindly reprinted with the permission of Dr Anna Hurlimann.

feature articles

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feature article - water quality research australia

WATER QUALITY RESEARCH AUSTRALIA LIMITED (WQRA) David Halliwell, Jodieann Dawe, Angela Gackle, Michele Akeroyd

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CRC for Water Quality and Treatment

The water industry's baby is off and running ... Since the establishment of the Cooperative Research Centre (CRC) program in 1991 , there have been more than 168 CRCs formed. They have created an opportunity to bridge the gap between government, industry and the university sectors, and do so with significant financial support from the Federal government. The CRC for Water Quality and Treatment (CRC WQT) completed two terms (13 years) and had a significant impact on the Australian Water Industry. But perhaps the greatest testament to the accomplishments of the CRC has been the Water Industry's support to form a new entity which will continue to undertake targeted research for the industry beyond the life of the CRC. The baton has been passed to Water Quality Research Australia Limited (WQRA). WQRA, which was officially launched in August 2008, aims t o build on the successful collaborative model of the CRC, bringing together industry, research organisations and general members, and will continue to work with state and territory health regulators and other national agencies and groups. Whilst many of the members are the same as those in the CRC, many are new, and the operating conditions have changed significantly. • The start-up budget is small compared with the CRC. This was anticipated, but is forcing members to focus much more tightly on their priorities.

2. Adopt a risk-based approach to research in order to underpin the implementation and further development of relevant Australian guidelines for drinking water and recycled water.

3. Facilitate knowledge transfer and up-t ake of the research outcomes in the water industry. This is the first of two articles that will provide the broader water industry with an overview of WQRA and its objectives. The second part will outline the progress of development of the WQRA Research Portfolio - a suite of research projects that is designed to address a range of issues as defined by WQRA members. The formation of WQRA, and the project development process to date, highlights the wi llingness of the water industry, government, researchers and the community to wqrk together in an area of utmost national significance - the provision of safe and reliable water.

Governance WQRA has a small number of staff (8) to provide flexibility and keep overhead costs low to enable the bulk of member funds to be utilised for undertaking research projects. The CEO, Jodieann Dawe, reports to a Board of Directors elected by the WQRA Members. The independent Board Chair is Professor Michael Moore. The current Board Members of WQRA are: • Michael Moore, Independent Chair • Keith Cadee, Water Corporation of WA • Dharma Dharmabalan, Caliban Water • Anne Howe, SA Water Corporation • Jan Bowman, Department of Human Services, Victoria • Chris Davis, University of Technology, Sydney

• The secretariat is small - it will have to be lean and mean.

• John Howard, Australian Water Quality Centre

• There are many more water research centres now than a decade ago, hence more researchers - some working in highly specialised areas.

• John McNeil, Monash University

• Drought-related issues are more important and this continues to influence both the political landscape and the research direction. In its short time of operation WQRA has started to form international links with 'like' organisations including Water Research Foundation (formerly AwwaRF) and the Water Environment Research Foundation (WERF), and was successful in its application for membership of the Global Water Research Coalition (GWRC). WQRA has the mandate to undertake collaborative research with a national application, focussing on drinking water quality, recycled water and relevant areas of wastewater management. The primary aims of WQRA are to:

1. Conduct and advocate for high quality research on the priority issues for the Australian water industry, including urban, peri-urban and regional water supplies, relating to public health.

60 FEBRUARY 2009 water

• Jodieann Dawe, CEO WQRA The Board is supported by two advisory committees: Scientific Advisory Committee and Regulatory Advisory Committee to ensure the Board is kept abreast of emerging issues that may impact the Australian Water Industry. WQRA also has significant interactions with Water Services Association of Australia (WSAA), to ensure that the Australian Water Industry research needs are well addressed.

WQRA Membership WQRA membership is open to Australian water utilities, research organisations (e.g. universities), private sector compan ies, consultant s, state and territory government departments and water resource managers. Industry members provide the core WQRA funding , whi le research members' contributions are in-kind through the provision of people and infrastructure. Additional funds for specific research areas have been obtained through targeted research grants, from organisations including the National Water Commission (NWC),

feature articles

feature article - water quality research australia Australian Research Council (ARC) and the Smart Water Fund of Victoria. New members are welcome and enquiries should be directed to Jodieann Dawe, CEO WQRA (Jodieann.dawe@wqra.com.au).

Science and Research Directions The future presents new challenges for the urban water industry. The impacts of climate change and urban growth will exert increased pressure on existing potable supplies, as well as dictating greater diversity and scale of future urban water supply. Many regions have already begun to investigate and implement various wastewater recycling, stormwater harvesting, groundwater source and desalination options. This diversity presents greater complexity and therefore many challenges for the industry and policy makers. Furthermore, on-going scientific discovery will provide improved understanding of existing risks, whether these are known or as yet unknown. In response to this, targeted research outcomes from WQRA will play a pivotal role in building the confidence of the community and regulators in the urban water industry's ability to provide safe and acceptable water products and services whether these are potable or alternative water sources, or an integrated comb ination of both. WQRA's core Research Program will therefore focus its efforts on addressing: • Emerging public health challenges posed through the development, introd uction and integration of new and alternative water products and services into the urban water product and service cycle.

• Current public health challenges identified through the latest scientific developments and improved understanding of key risk factors. WQRA will continue the CRC's research program aimed at improving water quality and public health in remote areas, especially with regard to access to appropriate drinking water for remote indigenous communities. While many of the issues are similar to those in urban water supplies, the solutions need to take account of the different infrastructure and social situations in rural areas. WQRA's Research Program will address key water industry scientific and technical knowledge gaps and emerging risks. Research funded by WQRA wi ll support the industry by underpinning the decision-making process with weight-ofevidence based science and research outcomes. In the latter half of 2008, two Program Managers were appointed to administer the WQRA research portfolio. Dr David Halliwell leads the Recycled Water/Wastewater Program and Dr Michele Akeroyd leads the Drinking Water Program. They are currently managing a number of projects that are residuals from the CRC WOT, and some exciting new project agreements that were signed as the transition from CRC to WQRA was taking place. But the most important task in the past months has been to work with WQRA members to commission new research in priority areas. In the next issue we will focus on the outcomes so far in the process of determining how the Members will spend WQRA's research dollars.

• •

:::·env1roaer industries

feature article - professional development

SYMPOSIUM ON WATER RECLAMATION AND REUSE: KOREA PURSUES RECYCLING Dr John Radcliffe AM FTSE In December 2008, the Korean Ministry of Environment (MOE) convened a major Symposium on Water Reclamation and Reuse to raise wat er industry and related market interest in water reuse in Korea. The Symposium was organised by Dr. Eun Namkung (Professor, Dept. of Environmental Engineering, Myongji Univ.) who currently is leading the Eco-STAR Project in Korea. The Eco-STAR Project is a national R&D program for Water Treatment Technology supported by the Ministry of Environment in Korea. Earlier Dr. Namkung was Director General of the Drinking Water and Wastewater Bureau in the Korean Ministry of the Environment which had assumed integrated responsibility for drinking water, wastewater, water reclamation and reuse and general waste management from 1994. Particular emphasis in the Symposium was to be on the needs and aims for recycling, such as cost saving and lack of water supply; basic plans and applied technologies; quality guidelines and how they should be established; related regu lations and laws; demand (quantity) and how it is determined; capital costs and treatment costs, and the potential extent of governmental support for installation and operation of sewage/wastewater reuse facil ities. Examples of case studies were also sought. Several overseas speakers were invited The Symposium was preceded by a briefing meeting on 8 December 2008 convened at Seoul National University. The briefing was attended by about 20 senior administrators and researchers drawn from Korean universities and the public service, and by the four international guests, viz Dr Shuvaji Deshmukh (Orange County Water District, California), Dr. Tao Guihe, (PUB Singapore, but formerly from Shanghai), Dr Oon Siwei (PUB Singapore) and Dr John Radcliffe (CSIRO Australia). The discussion and following symposium were driven by the fact that since Korea's national drinking water and wastewater treatment infrastructure now covers 90% of the country, a complex set of industries has developed needing 1GUday, only half of wh ich could be reliably guaranteed from reservoirs. It is difficult to interlink many water supplies due to the mountainous nature of the country. The government has determined that it wishes to increase water recycling in areas where the drinking water comes from a distant resource. It was also noted that some areas of the country, notably Daegu (Taegu), were approaching water stress. A valuable informal discussion was held around issues of water sources, technologies, quality, costing and pricing and public acceptance, with the international guests discussing their local experiences. The Symposium was held at the Seoul Convention and Exhibition Centre (COEX), located at Yeongdongdaero, Seoul, on Tuesday 9 December 2008, and was attended by 800 participants drawn from national and local government, universities and industry. All participants were provided with a

62 FEBRUARY 2009 water

Symposium organiser Eun Namkung speaking.

set of proceedings incorporating Powerpoint slides at two per page, though those used in the actual presentations were somewhat reduced in number to allow accommodation in the time available. Korean speakers presented slides largely in hangul (two slides from an Australian National Water Commission presentation, suitably acknowledged, appeared in one speaker's presentation), whereas the international visitors' Powerpoints were in English. A simultaneous Korean/English translation service was provided to delegates. The symposium was opened by Dr B U Lee, Vice-M inister of the Ministry for the Environment (a UK-educated resource economist), who went on to give the keynote address, starting with outlining the development of a total management system for the four principal rivers of Korea. He advised that the Korean environment is seen as a resource for economic growth, with Korea to undergo a process of change towards "eco-efficiency", increasing it by 50-100%, though the audience was cautioned that it cannot be determined simply by input-output calcu lations. Korea wants to reduce use of its energy resources, its greenhouse gas emissions and its water resources as components of "eco-efficiency". The speaker recognised that Korea needed to set targets in all areas but had not yet done so. The government has therefore adopted a philosophy of "green growth" to gain a competitive edge. Producers' and consumers' attitudes would have to change. It was recognised that current water prices were very much distorted ; furthermore, social welfare policies should be separated from water pricing policies. Water demand was rising, supply was becoming more difficult and it was not practicable to build more dams. Korean water recycling had reached 9.9% by 2007, with 24 water reclamation facilities

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feature article - professional development around the country. An objective was to achieve 19% recycling by 2016. It had been made obligatory for public buildings to collect and use rainwater. Consideration is being given to wider grey water treatment and ultimately recycled wastewater for drinking. It was considered that Korea had a good track record on recycling, albeit not all had been successful. However, disappointment was expressed that Korea had yet to develop its own world-leading water recycling technology companies. Dr Zuwhan Yun from Korea University presented on the current status of Korean water reuse. He noted that the economic impacts of climate change wou ld fall greatest on public utilities, with the banking sector second-hardest hit. He asserted that water stress would become much more significant in the BRIC countries and Korea compared with OECD countries as a whole. Pusan already has a water shortage. He went on to give recycling examples from Hawaii, Germany, Spain, Australia, and Singapore. He also commented that although recycling was increasing in Korea, the reality was that most of it was actually used within the Waste Water Treatment Plants. Dr Yun saw a further progressive reduction in the capital cost of Membrane Bioreactor Plants (perhaps 1130th of the cost of the first-installed plants) and the increasing use of submerged MBR as providing significant encouragement for recycling. A development of MBR by Kolon-POSCO in Korea, known as the 13 system, was outlined. Dr Shivaji Deshmukh of Orange County Water District described its problems, its wat er sources, its need for around 430GL water annually, and that about 200GL of wastewater discharged from upstream cities is the principal source of base flow. He gave the background of the Water Factory 21 and its current expansion based on microfiltration, reverse osmosis and UV light oxidation with hydrogen peroxide to produce 265GL of near-distilled quality water per year. Half is being used for expanding the seawater intrusion barrier and half for replenishing groundwater basins in Anaheim. Spreading in percolation basins commenced in January 2008. The Ground Water Replenishment System is fed 80% from activated sludge plants and 20% from trickling filter plants. It was noted that there were no industries directly taking this recycled water. He also described the "Green Acres Plant" which uses tertiary treatment (flocculation, filtration, chlorination, blending) for golf courses, landscaping etc. the water being sold at 80% of the cost of groundwater (drinking water). Revenues cover operations and maintenance but not debt servicing. Five qualities are provided for industrial use depending on need, ranging from tertiary treated for irrigation to two-pass RO for high pressure boiler feed. Detailed quality data from the plants were provided in the hand-out proceedings. Dr Tao Guihe, a Senior Research Scientist from the Centre for Advanced Water Technology (part of Singapore's PUB) discussed the development of NEWater, its uses, and the decision to increase recycled water to 30% of Singapore's water demand (albeit largely for industry) by 2011 rather than 15% as originally intended. Details were given of the Bedok, Kranji , Seletar and Ulu Pandan plants. The introduction of pilot Membrane Bioreactor - Reverse Osmosis - UV disinfection treatment trai ns in place of Activated Sludge - Microfiltration Reverse Osmosis - UV disinfection treatment trains was discussed in some detail. Comparative analytical data were provided. Dr John Radcliffe (CSIRO) , presented on "Adoption of Water Recycling across Australia". Issues covered included drivers for water recycli ng, the Australian governance system, the National Water Initiative, the extent of recycling by stat es

64 FEBRUARY 2009 water

Delegates at Symposium.

and the main capital cities, uses of recycled water, and various case studies with costs. These included the Virginia - Northern Adelaide Plains, the Wi llunga Basin Water Company, Fosters Brewery at Yatala Queensland, the lnkerman Street St Kilda apartments, Melbourne Council House 2, Parafield Wetlands and the South-East Queensland Water Grid / Western Corridor system. Costing and pricing issues were addressed. The five major desalination plants were detailed. Assistance provided by government via the Australian Government Water Fund was summarised. Dr HaYeon Yoon from the lncheon Development Institute presented a case study of wastewater reuse in Song-Do lncheon Free Economic Zone. The aim is to create a hub for logistics, international business, leisure and tourism for the Northeast Asian region. There, foreign nationals can live and invest freely in a self-contained living and business district featuring convenient air and sea transportation, a logistics complex, an international business centre, financial services, residences, schools and hospitals, and shopping and entertainment centres. A Waste Water Treatment Plant is producing 13,000 tonnes recycled water /day distributed through 25.9 km of pipelines. Dual reticu lation will be provided in two of the four quadrants of the city, wh ich is planned to have 250 000 residents by 2020. Mr J Y Lee of Hyundai Steel , which uses electro-furnaces with scrap steel, produces 10 million tons of steel annually and is aiming at 20 million tons. He outlined the movement of the company into using recycled water. Examination of the concept commenced in 1998, identifying a demand for 1.2MUday. A Waste Water Treatment Plant 1.2 km distant was available for source water which had above 1000TDS, asserted to be due to the locals' taste for salty food. A pilot plant was built in 2001, with a full scale plant in 2002. The company has a large storage area and undertakes chemical processing, microfiltration, and reverse osmosis for use in boilers, the result being better than the locally reticulated drinking water previously used. In addition, recycling of 96% of the water used in the steel plant is now being introduced. Mr Lee was not prepared to discuss the component costs, but indicated that membranes were being changed every three years. Recycling led to a saving of 6 billion KRW annually (approximately $5 million) and had proved more economic than originally anticipated. Dr Yon-Woo Lee from Samsung Engineering indicated that the Korean electronic industry (a major economic driver) was water intensive with a considerable waste stream which had come under tighter environment protection legislation. The principal Samsung uses were for Liquid Crystal Display (LCD -

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flat screens) and semi-conductor manufacture. A detailed examination was made of the target wastewaters. LCD manufacture waste water is high in organics while that from semi-conductors is high in inorganics, particularly calcium. The aim was to develop recycling of the company's wastewater to be cheaper than buying in drinking water. Recycling from the LCD plant involved installing a Membrane Bioreactor plant followed by Reverse Osmosis, while the semi-conductor plant required development of a Hyperkinetic Vortex Crystallization (HVC) process characterized as seed crystallization with cavitation for the removal of calcium from the electronics wastewater. By application of the cavitation technology, the dominant particle size decreased and the specific surface area increased. After cavitation, the shape of the calcite changed to spherical, which presumably increased the clarification efficiency and prevented the formation of scale in pipelines. It was presented that by 2013, the company expects to be recycling 120MUday in the LCD plant and 24MUday in the semi-conductor plant. Dr Lee considered that the Korean electronics industry was at the forefront of industrial water recycling with scope to export the technology overseas.

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A representative of the Ministry for the Environment then introduced the Korean government's "Basic plan for the reuse of sewage for industrial use". The government proposed to invest 10 billion KAW ($9 million) but was seeking considerable private capital to assist as water shortages were becoming a real issue. There are 65 billion tonnes of sewage effluent available annually as source water. It was noted that a much larger budget of 1.4 trillion KAW (about $1 billion) has been set aside for the overall maintenance of the quality of streams and rivers in Korea. The level of government support for recycling (35-50%?) might vary depending on the quality of recycled wastewater - further modelling was still required . The government's aim was to encourage profit-seeking private investment aiming at 440GL annual reuse by 2016, with prime encouragement directed to 19 areas identified as short of water to achieve 1.22GUday recycling. Details of various Internal Rates of Return were exhibited (higher for larger plants). Preference was expressed for BOT rather than BTL schemes. (There was some subsequent discreet comment from those present that the enthusiasm for private sector coinvestment was being driven by difficulties faced by the government as a result of the "world financial crisis", with disappointment being expressed about the proposed level of government investment.) The symposium concluded with a plenary presentation in which a range of speakers each took three minutes to express their aspirations on issues for the future of water recycling, including the likely impacts of climate change, the need for and availability of private investment in the face of the financial crisis, market risk, lack of liquidity, better guidelines for the private sector, new technologies with more international collaboration, the need for cities such as Daegu and Wuhan having no choice but to adopt recycling and a potential conflict of interest between the Korean Water Corporation and the Korean government's stated policy direction. It seemed evident that the Korean public was not real ly aware of the water constraints the country faced and there has been little or no society-wide discussion on the topic.

The Author

MCCONNELL DOWELL

Dr John Radcliffe AM FTSE is an Honorary Research Fellow in CSIRO and was a Commissioner of the National Water Commission from 2005 to 2008.

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PRESSURE SEWERAGE: IMPLEMENTING BEST PRACTICE ENVIRONMENTAL ENGINEERING AND STAKEHOLDER CONSULTATION R Edwards, S French, R Ogier Abstract With increased legislation, environment al awareness and community expectation the time and cost to plan and design backlog sewerage projects have increased over recent years. This paper describes project planning and delivery innovations the 'us' - Ut ility Services Alliance has incorporated into South East Water's Flinders and Shoreham Backlog Sewerage Project.

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A pressure sewerage system was preferred because of the high environmental impact of on-grade works for the traditional gravity sewer. Project planning innovations for the pressure sewerage works have been developed which have significantly reduced the cost and timeframes associated with stakeholder and statutory approvals, while improvi ng community and stakeholder support for these important projects.

Introduction The coastal townships of Flinders and Shoreham are located on the eastern side of the Mornington Peninsula, 70 km south of Melbourne. 'us' - Utility Services is currently completing the Flinders and Shoreham backlog sewerage scheme to reduce the impact of septic tanks effluent on the local waterways which ultimately drain into Western Port, which has popular surf beaches and nearby RAMSAR protected wetlands. Through best practice environmental engineering and stakeholder consu ltation the project has been able to: 1. avoid vegetation removal, disturbance and minimise environmental impacts 2. improve timeframes for planning approvals, project development and construction 3. reduce project cost

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requ ired to avoid disturbance to the environment and private assets.

5. eliminate the risks associated with septic tank effluent to public health and the environment

Due to these high environmental and cultural heritage values within the Flinders and Shoreham Township and the increasing levels of statutory approvals which caused increasing costs and timelines, an innovative design process was required for the Project.

Benefits of Pressure Sewers for Backlog Sewerage Schemes Flinders was originally designed as a gravity sewerage system. However, a gravity sewer system was found not to be financially viable, due to the problems of on-grade trenchless construction

Engineering, environmental management and customer consultation come together.

A pressure sewer system was adopted, not only for its more efficient energy requirements, but also because it offered the lowest impact on the natural environment. It also presented a socially acceptable option and minimised stat utory procedures with significant time savings. The pressure sewer systems were able to use small diameter pressure mains in road reserves, constructed predominantly by directional drilling, with little regard for grade. This resulted in lower capital costs and a significant

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pressure sewerage reduction in disturbance to the environment and local community during the project construction.

Historical Construction of Pressure Sewer Systems When South East Water installed Australia's first large scale pressure sewer system in Tooradin (Mann G, 2001) the majority of the works was undertaken using traditional trenching methods, when laying the smaller diameter poly pipe work. The next pressure sewer project undertaken by South East Water was within the townships of Warneet and Cannons Creek (Santamaria, 2004). These towns - within which there is extensive protected vegetation - were located at the northern end of Western Port which is within the protected RAMSAR wetlands. To ensure the protection of the environment much of the reticu lation system was installed using direction drilling technology. During this project the benefits of non-

destructive installation of pressure sewer system was realised with all veg etation protected and a significant red uction of reinstatement requ ired.

works to be open-cut. This confirmed our approach and was adopted across the project. The approach of directional drilling has now been incorporated into all South East Water's Backlog Pressure Sewerage Schemes, with works currently being installed in the Nar Nar Goon and Tynong PSSs.

With the experiences of the previous Pressure Sewer System project, the Flinders Pressure Sewerage Project (French, 2008) was also predominantly installed by directional drilling. Although Flinders did not have the extremely high environmental and cultural values as the previous projects, the significant reduction in the degree of reinstatement and with a consistent construction method it was anticipated that further construction efficiencies could be realised. To confirm this, tendered rates were requested from three contractors for both open-cut and trenchless construction ( in areas of the project that did not requi re trenchless construction to avoid vegetation). Allowing for the usual tender rate variations the rates for trenchless and open-cut construction on average were the same, w ith one contractor submitting dearer rates for

Issues with Statutory and Stakeholder Approvals With the significant size of Backlog Sewerage Projects and the configuration of straight pipe network construction there is the need for planning approvals at Local, State and Federal levels of government - mostly associated with the removal of vegetation which is always associated with habitat of native fauna. The key statutory approvals are: Planning Permit, referral to DSE flora and Fauna, EPA approval, Water Authority approval, EPBC Act referral for controlled or non controlled action, Aboriginal Cultural Heritage Management Plan

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70 FEBRUARY 2009 water

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pressure sewerage

Figure 2. Typical Construction Impact Zone (Excavation, pipe insertion and (road) reinstated). currently referred to Aboriginal Affairs Victoria (AAV). These statutory approvals will always add significant time requ irements and often delay a project due to their administrative complexity, under- resourced planning departments, duplication of processes at Local, State and Federal Levels of Government, complex comm unity consultation and negotiation and complex surveys for environmental and cultural heritage impact assessments. These delays can result in planning approvals taking 12 18 months before any works can commence. For example, Flinders was originally designed as a gravity sewerage system and required a planning permit for vegetation removal. This planning permit received one objection, which was sent to VCAT. This objection was withdrawn 2 days before the hearing, but resulted in the planning permit taking 7 months to be approved from the time it was submitted. The statutory process also has the capacity to increase the project cost by 10-20% due to requirements for "net gain offsets" for vegetation removal and salvage of cultural heritage artefacts. This may also require the proponent to undertake remediation works and maintenance for up to 10 years post construction.

A New Approach for the Shoreham Pressure Sewerage Project Although the project team was confident that we could meet the challenge of completing the Shoreham Pressure Sewer Project with complete environmental protection, a new process was needed to be developed to demonstrate this level of protection to our statutory referral authorities during the design and stakeholder consultation activities associated w ith the project's design, which would avoid the need for a planning permit.

72 FEBRUARY 2009 water

Applying a Critical Impact Zone Although the works were to be undertaken predominately by directional drilling, excavation works are required at all changes of pipeline direction, at fittings (valves, etc) and at intervals of approximately 100m which is the standard length the directional drilling machines can drill per operation. These locations were nominated as Construction Impact Zones (CIZ). All works were to be undertaken only from these CIZ, which would be demonstrated (during the design development) to be clear of vegetation or cultural heritage sites. A typical plan is shown in Figure 1 and the work in a typical CIZ in Figure 2. Where once design plans would indicate where "trenchless" construction replaced trench construction, SEWL pressure sewer plans now show the reverse , ie. trenched construction as the exception (a fascinating evolution).

The Job Environmental and Heritage Assessment The adoption of CIZ simplified the Environmental Impact Assessment process and development of the Job Environmental and Heritage Assessment (JEHA) process to focus on approximately 100 CIZ, rather than reviewing and assessing 11 km of pipeline alignments - which, due to the environmental and potential cultural heritage values, was not practical. The JEHA process requ ires environmental impact assessment of the alignment but only detailed assessment within the CIZ. The JEHA includes a clearly written and concise description of actions to protect important flora, fauna and cultural artefacts with procedures relevant to statutory requirements. The JEHA also forms a key document for induction at toolbox meetings with all staff working on site.

Collaboration of Three Disciplines: Engineering Design/Construction, Environmental and Survey Throughout the JEHA process there were a number of important desktop and field reviews undertaken on the alignment in collaboration with engineers, ecologists, surveyors and stakeholders to ensure all works could be completed with minimal impact. In order to identify clearly the extent of vegetation within the area of impact the survey team developed a broader scope of measurement to include trees on the peripheral and their Tree Root Zone (TRZ). This identified the TRZ for all trees near a CIZ on preliminary plans which aided the design assessment and avoided impacts on flora and fauna or cultural heritage. The inclusion of the CIZ and TRZ on the design plans clarified and confirmed our ability to Avoid or Minimise deleterious effects and proved an effective communication tool for key stakeholders including statutory authorities and construction crews. After the design and JEHA process the Design and JEHA documents where packaged together and presented to statutory authorities and agreement was obtained that planning permit approvals were not required for the project. Further, the JEHA also became part of the construction contract documents, to ensure all works are completed in a manner that meets the approved design's intent.

Improvements to Pump Unit Installation and Customer Connection The Pump Unit Installation & Customer Connection process is undertaken as a separate stage to the installation of the reticu lation network. Once the reticulation network has been installed and commissioned, Connection Information Packs are sent to all

technical features

pressure sewerage property owners within t he township, with an invitation to connect. (Figure 3) This allows consultation regarding t he works on t heir property with the cust omer on t heir terms. This is important as the customer con nection process is relatively complex given it involves: • Locating a pressure sewer unit and associated works with in t he customer's property; • Assessment and considerat ion of the su itability of existing house d rai ns for connection to the pressure sewer unit; and • Connection of the pump unit to the householders electrical power supply. 'us' - Utility Services put considerable effort into developing a streamlined and consultative customer connection process. Once a customer applies to connect they are fully consulted regard ing the wo rks within their property. A full time project office, located within the township, has enabled close relationships throughout the project. Property owners have the flexibility to select the location of the pressure pump

Figure 3. Pamphlet examples from connection kit.

unit so t hat it can be close to their existing pipe work, wh ich for t he majority of property owners will also minimise thei r plumbing connection costs. Importantly a customer satisfaction rate of 98% is being achieved with this sewer connection process. The following feedback is representative of our customers' view of the new con nection process:

"Just want to say how impressed I was with the entire difficult job. It was completed smoothly with good humour, cooperation & care. It could have been a nightmare, but it wasn't" - Geraldine Richards. "Many thanks to those involved in the planning and installation of the system. A very helpful & professional team on site ensured a great result" - J & M Angwins.

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pressure sewerage Use of Directional Drilling for the Property Discharge Lines During the customer connection stage of the Flinders Project a trial was undertaken, where all property discharge lines were installed also using directional drilling, with surprising results. With careful packaging and procurement and the reduction in rei nstat ement the total cost of the customer connection remai ned below budget targets. Also , the discharge lines could also be installed deeper (reducing the likelihood of being damaged in the future) (Figure 4).

Increased Customer Acceptance and Connection Traditionally the rate at which customers connect to sewerage upon completion of Backlog Sewerage Projects can be slow (with less than 40% connection in the first 12 months generally seen in other similar schemes). The seamless, unobtrusive, consultative and discretionary manner in which the works have been carried out assisted in a greater t ake up of properties wanting to connect than originally planned, with over 85% of cust omer applying to connect in the first twelve months.

Great Success! This project has significantly improved South East Water's reputation as a socially responsible corporation throughout our stakeholders and achieved a greater level of understanding of environmental issues between all staff involved within the internal design and construction process. The benefits have extended to the key stakeholders including Local Government, Department of Sustainability and Environment DSE and the Department of Environment Wat er, Heritage and the Arts DEWHA Canberra. This was achieved through the ability to successfully adopt the key preferences of statutory authorities by Avoiding and Minimising Impacts. The need to obtain planning permits for vegetation removal , the high level of detail in the design plans including the Tool Box meeting and JEHA assists us in meeting our regu latory obligations by setting clear and concise guidelines for effective management of potential impacts. Pressure sewerage has significantly reduced the environmental footprint by

74 FEBRUARY 2009 wat er

Figure 4. Directional Drilling of property discharge line.

avoiding the removal of any native vegetation whilst the application of t he above process offers pract ical solutions for construction and compliance of statutory regulation. The application of this method benefits not only this project but withi n all current and future projects with special environmental and cu ltu ral heritage considerations. (FIGURE 5) The processes developed for the Flinders and Shoreham Backlog project are being used successfu lly on other sensitive projects and has now expanded to our maintenance and renewals section within SEWL operations. Most importantly this process has avoided delays associated with statutory approvals and the project will be delivered on time and below the original budgeted likely cost.

Conclusion In summary, this project is a clear example of engineering, environmental management and customer consultation coming together to deliver a net environmental benefit to our community. The key benefits are: • reduced septic tank effluent discharge t o ground water and Western Port (including RAMSAR wetlands) • avoidance of destructive construction tech niques • engaging the community in consu ltation on protecting the environment and ambience of their township

• protection of native f lora, fauna and the ecosystem supporting it • reduction of costs t hrough avoiding long delays and best pract ice in engineering, procurement and environmental management.

Ac knowledgments The support of the Morn ington Peninsula Shire, together with the communities of Flinders and Shoreham is gratefully acknowledged .

The Authors

Russell Edwards is the Specialised Services Manager for the 'us' - Utility Services Al liance, Capital Delivery Group (emai l: Russell.Edwards@ sewl.com.au); Steven French is the Design Manager (email: Steven.French@ usus.com.au); and Rohan Ogier is the Project Management Manager (email: Rohan.Ogier@ usus.com.au)

References French S (2008) "Pressure Sewerage: The Flinders Project" Water 35 No 4, June Mann G (2001) Delivering financial benefits can be achieved with social and environmental benefits, Case Study: Tooradin Backlog Sewerage Project, VicWater Santamaria D, Mann G (2004) "Pressure sewers at Tooradin, Victoria", Water, 31 , No 2. March

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Programme Themes Feasibility and Benefits (economic, social, environmental and technical) of undertaking water loss reduction projects.

Performance Indicators and Best Practice. It is important to understand which indicators are required to evaluate feasibility of options. Intervention Techniques to find leaks and reduce water loss. Sustainability. Success stories achieving lower sustainable water losses. Scientific Programme The draft technical programme is available on the website www.waterloss2009.com Conference Proceedings will officially commence on Tuesday morning 28 April 2009 with an optional half-day workshop on the Basic Concepts of Water Demand Management on Monday 27 April 2009.

Social Programme The social programme includes: Welcome Reception on Sunday evening, 26 April 09 incl in reg fee

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onsite treatment

SUSTAINABLE BACKYARDS & BEYOND! Report by Goen Ho, Murdoch University The Onsite and Decentralised Sewerage and Recycling (ODSR) Conference was held in Benalla, Victoria in October and was very well attended by 220+ delegates from all states in Australia, as well as from the USA, Canada and New Zealand. The conference continues the strong link that has developed with professionals from these cou ntries, which I first observed at the International Water Association (IWA)'s 6th International Specialized Conference on Small Wat er & Wastewater Systems in Fremantle in February 2004. The then AWA National Onsite Interest Group (NOSSIG}, Onsite New Zealand and the US's National Onsite Wastewater Recycling Association (NOWRA) participated in a joint effort with the conference. ODSR at Benalla was the first meeting of the newly formed AWA's interest group in Small Water and Wastewater Systems, formed by the merger of NOSSIG and Integrated & Decentralised Water Systems in September. The new name aligns with the International Water Association's specialist group and is a welcome development. I attended the four keynote addresses and listened to half of the fifty technical presentations equivalent to one stream of the two parallel streams), but missed the 12 workshops arranged in parallel with the two streams. Solutions for towns with failing septic tanks , septic tanks in nutrient-sensitive environment and the problem of direct discharge of raw greywater to the stormwater system received much attention and interests, because the Victorian government is providing funding (reportedly over $40 mfllion in regional areas) to assist with overcoming these problems. Not surprisingly the workshops covered topics related to these and ranged from selection of tech nologies, engagement with the community, regu latory compliance and achieving the ideal close loop system. Papers reported progress in technology, incl uding systems incorporating the use of membrane separation/reverse osmosis, and so very

76 FEBRUARY 2009 water

Future House with Nutrient Separation and Recovery and Water Reuse

Urine collection vehicle

Water for toilet flushing

Curbside vacuum pumpoul connection

Low-pressure membrane To landscape drip irrigation

Treatment unit

Urine storage tank

Figure 1. Example of the home of the future incorporating urine separation for nutrient recovery, septic tank with methane control biofilter, a biological treatment unit for BOD, TSS and partial nitrogen removal, water reuse by means of drip irrigation, and the use of a low pressure membrane for production of water for toilet flushing. high quality water can be produced. The reliability of membrane technology is now so high that the possibility of water reuse in onsite and decentralised applications appears to be unlimited. There is also evidence of the interest of the private sector for onsite and decentralised systems as these are perceived to increase the environmental and sustainability image of the land development and hence value of the real estate. Ben Kele presented in his keynote paper a case study that showcases the confluence of advances in technology, interest of the private sector and more importantly how the regulatory requirements are met. The paper is appropriately titled a New Dawn for Decentralised Sewerage. My own group, the Environmental Technology Centre, presented nine papers on various aspects of onsite and decentralised water systems being implemented at three land developments near Perth, but there are numerous case studies reported from all parts of Australia. These are worthwhile reading for those

who would like to find out what is currently happening in Australia. I commend the proceedings of the conference, because the papers were thoroughly reviewed by two reviewers plus by Sarah West. Feedback was provided to authors and only revised papers were published. Outlines of the workshops are also included in the proceedings. For a relative veteran, having chaired the /WA Specialist Group on Small Water and Wastewater Systems from 2000-04 and followed developments in this field, I learnt something new at the conference. This is the concept of utilising the Soil Mantle, which I understand as the top soil where micro-organisms are active and roots of plants reside, that was promoted by the International Keynote Speaker, Professor George Tchobanoglous. He advocated that if wastewater is distributed evenly in the soil mantle, then there is unlikely to be ponding or run-off of excess water and nutrients. In practice this means that

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onsite treatment water from a septic tank, for example, could be distributed at closer intervals using subsurface drips at shallow depth or even perhaps on top of the soil beneath a layer of mulch, without having to consider the type of soil (porous sand or tight clay). This is in stark contrast to the current practice guided by AS1547 of having to consider the type of soil and the need to conduct soil permeation test. Professor Tchobanaglous' other ideas can be gleaned from his Home of the Future, shown in Figure 1 and taken from his keynote paper at the conference, The Role of Onsite and Decentralised Wastewater Management in the Twenty First Century.

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I had the privilege of interviewing George Tchobanaglous during the conference, and realised that he had just spent a couple of weeks with various state and local government agencies and water authorities in Victoria making his expertise available as part of the sponsorship programme to bring him to the conference. I asked him three broad questions as an expert from the US, who, as an outsider, can see more clearly than a local. Here are his answers, though seen through a lens coloured by my interpretation. What is your impression of the onsite and decentralised wastewater scene in Australia (Victoria specifically)?

There are two separate regimes for the management, operation of centralised and onsite/decentralised systems. Not only are they separate, one by a water authority or equivalent and the other by a local authority or equivalent, but they are also distinct from each other, with apparently little interaction between the two. Centralised systems operate primarily in urban areas and onsite systems in regional and urban communities in Victoria. The septic tank is still the main form of onsite system, and failure is common. The development of alternative technologies is hampered by a lack of standardisation, and the implementation of onsite technologies by a lack of clarity about the responsibility for management of onsite systems.

to be involved in fixing and managing septic tanks and onsite and decentralised systems, and local authorities wh ich do not have the expertise in onsite technologies having to deal with failing septic tanks or implementing alternatives. This led to my second question: Do you have suggestion or solution for the problems facing communities with failing septic tanks?

Water authorities and local councils should work together, initially by setting up pilot programmes to demonstrate what properly designed, installed, run and managed onsite or decentralised syst ems can achieve. Technology is currently not the constraint to the solution, but clear government poli cy on the responsibility, management and funding for onsite and decentralised systems is. The long-term solution lies in working with the regulatory authorities to achieve clear and unambiguous governance for onsite and decentralised systems. My final question was on the future of onsite and decentralised systems: What is your outlook for onsite and decentralised systems?

He reminded me of his keynote address (see above), illustrated by his Future House. He added that not all features will be adopted, and new features may appear, but the future for onsite and decentralised systems is bright because we want a sustainable future. Finally I must mention that I enjoyed the conference dinners (two of them instead the usual one), where raffles were sold which raised nearly $2,000 for Australian Wat erAid, with prizes provided by some of the delegates. I recommend the Conference Proceedings to you, which can be purchased from AWA.

It was refresh ing to me to hear George confirm what some of us have observed about the dilemma we are in, that water authorities which have the expertise in sewerage but do not want

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onsite treatment

~ refereed paper

SAND MOUNDS FOR EFFECTIVE DOMESTIC EFFLUENT MANAGEMENT J Whitehead, P Geary Abstract Sand mounds can offer a suitable treatment and land application option for constrained sites, particularly those where separation distance to the water table is limited. Sand mound technologies, commonly called "Wisconsin Mounds", have been extensively developed and utilised in the United States and a number of studies report on their performance. There is growing interest in the application of sand mounds in Australia, but to date little has been published on the performance of such mounds in Australian settings. As failing septic tanks had been contributory to viral pollution of oysters grown in an estuary, Port Stephens Council required upgrades. One option was to replace the adsorption field by a sand mound and currently 58 mounds are receiving primary treated effluent and nine receiving secondary treated effluent in Port Stephens. This paper reports results where two of the mound systems were monitored in detail for a period of six months from mid-2007 using a variety of soil water samplers and groundwater bores.

Introduction Various water quality investigations in the Tilligerry Creek catchment (30 kilometres north of Newcastle, NSW) have, over the years, characterised the often poor quality of estuary waters with the contami nation being attributed to a variety of sources including urban runoff, agricultural wastes and failing on-site wastewater systems. Work characterising the sources of faecal material in estuary waters by Geary and Davies (2003) concl uded that "while no single source emerged as the most significant contributor of faecal contamination to This paper has been prepared from two papers presented by the authors at the On-Site and Decentralised Sewerage and Recycling Conference, Benalla, October

2008.

80 FEBRUARY 2009 water

Figure 1. Wisconsin mound - Wisconsin. either the oyster leases or to Tilligerry Creek, cattle, human and chicken faeces were all found to be contributing to faecal contamination of the drains and estuary". During 2005 human viruses were found in oyster tissue in part of the estuary and the harvesting of oysters from commercial leases was prohibited by the NSW Food Authority. As a consequence, a number of oyster farms closed . At most unsewered residences near the estuary, wastewater is treated in a standard septic tank and then dispersed subsurface using a small soil absorption system. Given the high water table and sandy soils in the area, there are times when the base of each trench is in contact with the groundwater. The groundwater is intercepted in a number of shallow drains and enters the nearby estuary. For this reason domestic wastewater systems were considered to

Protecting a sensitive oyster lease catchment.

be the primary source of the human faecal contamination within the estuary. The local regulatory authority (Port Stephens Council) embarked on an estuary remed iation program t o improve the quality of runoff waters from the various land use activities with in the Tilligerry Creek catchment. In addition to detailed inspections of onsite systems and identification of those that posed a risk to public health or the environment, an investigation was also undertaken to examine the contributions that unsewered development was making to both surface runoff and groundwater in the area (Lucas et al., 2007). While this recently completed study used a variety of chemical and microbiological indicators and concluded that human sourced contaminant transport to the estuary from unsewered development was likely to be minor, there were no other identifiable sources of human faecal contamination other than on-site wastewater systems. As part of the estuary remediation program, a number of sewerage

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onsite treatment (reticulated and decentralised) options for wastewater on individual properties in the Tilligerry Creek area were considered. One of these on-site options to overcome the land capability constraints of the area was to construct sand (Wisconsin) mound systems. Council commissioned best practice standard designs (Whitehead & Associates, 2005) for two land application options to address the high water tables experienced at the sites: a) secondary treatment with pressure compensating drip irrigation to raised beds and b) primary or secondary treatment followed by Wisconsin mounds. Upgrades of existing on-site systems were required but in recognition of the cost to individual homeowners for site specific designs, Port Stephens Council has made the standard designs available to homeowners to reduce the overall cost of the necessary system upgrades (Port Stephens Council, 2005).

Mounds as an On-Site Wastewater Management Option Mound systems were originally developed in North Dakota, USA in the late 1940s and known as NODAK disposal systems (Witz, 1974). Modifications of the NODAK system by researchers at the University of Wisconsin - Madison in t he early 1970s led to the mound design most commonly used today and these are most often referred to as Wisconsin mounds (USEPA, 1999). Many t housands of these mound systems are now installed across the USA (Converse and Tyler, 2000) (Fig ure 1). Mounds offer the smallest footprint combination of secondary on-site treatment and land application. Consequently they are often su ited to small and constrained sites and in particu lar to sites with the following limitations: â&#x20AC;˘ Slow or fast permeabi lity soils; â&#x20AC;˘ Shallow soils over creviced or porous bedrock; and

[ ] refereed paper

ground level distribution manifold in coarse aggregate from septic tank pump chamber

Figure 2. Wisconsin mound (Source: Geary et al., 2005). â&#x20AC;˘ Soils with high water tables (USEPA, 1999). In summary, mounds dose primary t reated septic tank effluent, by pump or siphon, to a distribution manifold of perforated pipes set in an aggregate d istribution bed which sits near t he top of an appropriately sized sand-fill media mound (Figure 2). They are considered secondary treatment systems with the characteristics and features as summarised in Table 1. Effluent passes t hrough a mound in much the same way as it would if it passed through an intermittent sand f ilter, where it undergoes treatment before it enters the native soil beneath. Mounds have the benefits of increasing separation d istance between t he point of application and the soil and groundwater, they facilitate nitrogen reduction and they permit increased evaporation and transpiration due to their being raised above ground level. Amended media designs offer opportunities for phosphorus removal where t his is a requirement. Mound design and sizing requires professional input and with appropriate design, higher hydraulic loading rates can be applied than to conventional trenches. Mounds can offer an attractive landscape option in situat ions where soils, high groundwater tables or climate otherwise restrict alternatives.

Table 1. Mound System Description. Description

Pre-treated effluent is pressure dosed via a manifold in coarse aggregate near the top of a mound of sand through which it permeates. The mound is constructed above grade.

Uses

Mounds are used where soil permeability Is low, rock is close to the surface, or if water tables are high. They are suited to most climates.

Performance

Depending upon design, mounds can significantly reduce B0D5 and TSS. Nitrification can be significant.

Space requirements

Area Is determined by analysis of soil tests and is quite variable but can require a large footprint.

Maintenance

The system requires reliable power and pump and control maintenance or replacement; alternately on sloping sites siphons may be used to eliminate the need for power or maintenance. Mound vegetation requires maintenance.

,8 2 FEBRUARY 2009 water

A significant advantage of mound systems over most other types of domestic on-site wastewater management systems is t hat they offer both treatment and land application on the same footprint. Hence when land availability is limited, mounds may provide both a high (secondary) level of treatment and permit relatively high loading rates for land application. On occasion, on constrained sites, mounds may be the on ly feasible servicing option. In the case of irrigation systems, wastewater treatment t o secondary standard is general ly by means of either an aerated wastewater treatment system (AWTS) or a sand filter. In the case of the mound, which acts as a bottom less sand filter, an equivalent secondary treatment standard is achieved by passage of effluent through the media in the mound. Where appropriate sand media for mound construction are avai lable within close proximity to the site, costs of mound construction are comparable to those of a secondary treatment system pl us irrigation. Where transport of media is required, this can add significantly to mound costs, but nevertheless the significantly smaller land area required may prove attractive or indeed may offer the only feasible land application option if the site is small.

Current Practice in Regulation, Design and Construction Relevant and detailed information is available in t he literat ure, alt hough much of this is published in the United States, and consequently perhaps less readily accessed by practitioners in Australia. Useful guidance on Wisconsin mound siting, design and const ruction can be obtained from Converse and Tyler (2000). Many aspects of this available literature were reviewed and considered in the light of optimising mound designs in the Australian setting by Bishop & Whitehead (2007). The sizing and design of mounds is addressed to on ly a limited degree by

technical features

onsite treatment

~ refereed paper

Figure 3. Wisconsin mound at Site F - near Tilligerry Creek. cu rrent Australian guidelines and Standards. While mound systems have become increasingly popular as an alternative for domestic on-site wastewater management, there is usually only brief reference given and limited guidance provided on design and construction. AS/NZS 1547:2000 (Standards Australia, 2000) provides information on Wisconsin mounds that is mostly consistent with best practice designs available in overseas guidelines. However, it is limited in its scope and coverage of design and construction issues. A review of the 2008 consultation draft of this standard suggests that no major changes are proposed. In Victoria,

DRAIN

Site F

a Certificate of Approval has been issued by the EPA (EPA VIC, 2006), for a generic Mound System (CA 1.4/06), however, this offers little advice for design , no information on sizing and does not represent a best practice mound design. Despite stating that the system must be designed, installed and operated in accordance with AS/NZS 1547:2000, the design does not look anything like a true Wisconsin mound and appears more like raised absorption trenches or an inverted leach drain. The approval requires secondary level pre-treatment before the mound. It has been recognised that lack of trained professionals and/or unproven

~bsurface flow

Wisconsin Mound

•

GW1

•

Figure 4. Wisconsin mound at Site T - near Tilligerry Creek.

GW4

•

Groundwater

GW2

GW3

NOTTO SCALE

Soll water sample,.

Figure 5. Schematic of Monitoring Network - Site F. Site T

----

Subsurface flow

• • •

Wisconsin Mound

!j• !·o !L

GW1

•

GW3

NOTTO SCALE

Figure 6. Schematic of Monitoring Network - Site T.

.84 FEBRUARY 2009 water

GW2

s,,_,.mmplo~ Groundwater

design modifications (Converse & Tyler, 2000) and lack of rigour in design, selection of appropriate materials and attention to detail in construction (Bishop & Whitehead, 2007), are major impediments to successful mound operation. By incorporat ing much more detail on design and construction, based on the sound research available elsewhere, AS/NZS1547:2000 and t he State Government codes and guidelines could help advance Australian mound practice significantly.

Study Methodology As previously mentioned, two of the sand mound systems installed in 2006 (according to standard designs for mound systems (Whitehead & Associates, 2005)) were monitored in detail to determine the effectiveness of the systems in treating and reducing contaminants from each household and as the effluent entered the groundwater. The unsewered properties were located in the Michael Drive subdivision at Salt Ash adjacent to the Ti lligerry Estuary. The mound at Site F had a surface area of 146 m 2 (Figure 3) and that at Site T had a surface area of 170 m 2 (Figure 4). The properties studied were typical of the 40 other lots in the subdivision (one hectare allotments) where existing subsurface systems were performing poorly due t o the presence of sandy soils and high groundwater tables. There was no reticulated water supply, and rai nwater at each residence is used for potable purposes, although the majority of properties extract shallow groundwater for outside and garden use. Water use was monitored at each property (Sites F and T) using Smartmeters and the direction of groundwater flow determined using a

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onsite treatment

~ refereed paper

180

~ ~

::,

.?:-

:5 _g 8,

100

.. <

180

,e 120

100 80 .

80 <40 · 20 0

Tue

ll1.r

2 3 4 s

s ro

7 a

~ ~

ffl

~ ~ ~ ~ ~ ~

Hour

Figure 7. Daily Average Water Use and Average Diurnal Water Use Pattern - Site F. 500

500-1----------

§ : L___ -~ .... use~(ave,age)

400

~~-~-~

<(()

300

i:' :ro

29:)

120

J!:, '

100

2(X)

150

160 140

Site T (Indoor only)

-----

i.,

<~ 20 0

Tt.e

123456789WttU~M~~ff~~20~~~~ Hour

1tu

Figure 8. Daily Average Water Use and Average Diurnal Water Use Pattern - Site T. network of shallow bores. The direction of flow was consistent with the regional groundwater flow towards the estuary. Groundwater level variation was recorded in-situ using data loggers installed in piezometers and groundwater samples were collected (Geary et al., 2008). Suction lysimeters were also installed (Figures 5 and 6) and a suite of wastewater contam inants in the septic tank, vadose zone and groundwater (incl uding nitrate and orthophosphate) was measured between mid 2007 and January 2008. A groundwater tracer (LiBr) was also added to each of the mound systems at Sites F and T on 26/09/07 to confirm hydraulic connections between the wastewater treatment systems and the groundwater samplers.

Hydraulic Loads and Effluent Quality

known that effluent quality varies between individual households and can even vary over a 24 hour period in a household. At this household, grey water from the laundry was directed to the garden, so the effluent quality from the septic tank which is shown in Table 2, reflects the remai ning combined wastewater streams. The analysis results indicated that the concentrations of nitrogen (as ammonium) and phosphorus were relatively high, electrical conductivity was also high, BOO5 was moderate and faecal coliform numbers, as expected, were high and highly variable.

Site F. The average daily indoor water use for the family of four was 295 Uday. The weekday figure was as low as 250 Uday with the highest use of up to 370 Uday occurring on a weekend as shown in Figure 7. The average diurnal water use pattern is typical of a working family with two high school age children. Distinct morning and evening peaks can be observed. Nine septic tank samples were collected and analysed at each of the sites to gauge the typical quality of effluent delivered to each of the mound systems. Characterising the quality of the effluent is important as a background to understanding the treatment afforded by the sand mounds, however, it is well

Site T. The average daily indoor water use for the family of five was higher than at Site F and was between 400 and 450

Table 2. Septic Tank Effluent Quality - Site F and T. Site

units Septic Tank F

Septic Tank T

Average Maximum Minimum

7.2 7.6 5.7

0.7

Average Maximum Minimum

7.7 7.8

SD 86 FEBRUARY 2009 water

7.4 0.1

NOf

NH4+

Total P

P043·

B0D5

uS/cm

mg/L

cfu/100 ml

mg/L

1944 2430

232

1230 377

0.2 0.3 0.1 0.2

1234 1420 1140

0.4 0.4 0.4

300 170 45 133 165 100 22

20 24 16 3

17 20 14 2

13 18

10 11

1.18

X 106

6.00 X 106 2.50 X 104 2.13x106 3.44x10 4 6.70x104 5.46 X 103 2.15x104

215 303 102 75 187 324 85 99

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onsite treatment

~ refereed paper

Table 3. Water Quality Analysis of Groundwater Samples - Site F. Site

GW1

GW2

GW3

GW4

n=9

Depth to GW

units

N03·

NH4•

Total P

P043·

FC n = 7

uS/cm

mg/L

cfu/100 ml

Average

5.7

225

0.73

0.33

0.43

0.27

Maximum

6.5

422

1.1

0.68

0.80

0.56

Minimum

5.3

107

0.40

0.11

0.18

0.07

0.4

0.24

0.21

0.19

0.18

Average

5.4

445

0.99

0.43

0.25

0.21

149

Maximum

6.6

2.5

0.90

0.68

0.58

1000

Minimum

4.6

599 216

0.10

0.07

0.1 4

0.09

0.6

119

0.68

0.33

0.15

0.23

376

Average

5.2

500

0.79

0.89

0.19

0.12

Maximum

5.8

828

1.30

1.92

0.32

0.14

120 2

Minimum

4.9

266

0.40

0.13

0.07

0.10

0.3

180

0.30

0.71

0.07

0.03

Average

5.2

212

1.0

0.99

1.97

0.25

228

Maximum

6.5

386

1.70

1.90

8.40

0.40

1000

Minimum

4.8

0.40

0.29

0.13

0.10

0.6

59 103

0.50

0.61

3.21

0.13

391

Uday, as shown in Figure 8. All wastewater was delivered from the household to the septic tank (i.e., no separate grey water use). The average diurnal pattern of water use also had morning and evening peaks, however, the morning peak was smaller and broader than at Site F. The effluent quality in the septic tank at this site, while also of variable quality (shown in Table 2), indicated that the concentrations of most of the parameters measured were lower than at Site F. In short, the effluent quality/quantity at Site F was characterised as high concentration/low volume compared to relatively lower concentration/higher volume at Site T.

Groundwater Monitoring Results Groundwater samples were collected from the piezometers which had been installed along the general direction of groundwater flow. The summarised results at both Sites F and T which are

shown in Tables 3 and 4 should be examined in relation to the schematic diagrams of each of the monitoring networks (Figures 5 and 6). Also shown in these tables are the recorded depths to groundwater at each of the monitoring locations. The results from the monitoring of soil water in the vadose zone using the suction lysimeters are not reported here. If the septic tank effluent quality is considered typical of the concentrations pumped to the mound system, then it is possible to examine the data in Tables 3 and 4 to determine the effectiveness of the system in removing or reducing contaminant concentrations. Of interest also were the contaminant concentrations as they entered and travelled in the groundwater along the general direction of flow. In overall terms there were significant reductions in the concentrations of all measured parameters from the septic tank to the groundwater concentrations measured down-gradient from each mound system.

pH was typically two units lower on average in the groundwater than the septic tank effluent. As the mound treatment is an aerobic process and as nitrification is an acid-forming process, this wou ld normally be expected in these sandy, coastal locations. Electrical conductivity was substantially lower in the groundwater, possibly due to dilution and dispersion processes. Of major interest and significance, however, were the reductions in nitrogen (both nitrate and ammonium), phosphorus (both total and ortho) and faecal coliforms in the groundwater relative to the input concentrations from the septic tank. In an aerobic environment such as the unsaturated soil in a sand mound, ammonium is readily nitrified to nitrate, yet the maximum nitrate concentration recorded at any groundwater sampler was only 2.5 mg/L (GW2 at Site F). The maximum ammonium concentration of 1.92 mg/L was at GW3 at Site F. Overall there was substantial nitrogen loss as the

Table 4. Water Quality Analysis of Groundwater Samples - Site T. Note: GW1 contained negligible water on all occasions. Site

GW2

GW3

n=9

Depth to GW

units

N03·

NH4+

Total P

P0i·

FC N = 7

uS/cm

mg/L

cfu/100 ml 38 250

Average

5.0

135

0.90

0.21

0.34

0.24

Maximum

5.4

199

1.40

0.41

0.52

0.38

Minimum

4.9

0.60

0.11

0.26

0.10

0.1

0.20

0.1

0.11

0.20

Average

4.7

236

0.70

0.27

0.23

0.12

280

Maximum

5.1

396

0.90

0.41

0.48

0.22

1960

Minimum

4.5

0.50

0.14

0.06

0.03

0.2

0.10

0.08

0.14

0.08

741

88 FEBRUARY 2009 water

technical features

onsite treatment effluent from t he septic tank passed through t he mound and vadose zone into the groundwater. Processes such as dilution, plant uptake and soil adsorpt ion (for ammonium), and even denitrification under certain anoxic conditions can be potential loss mechanisms for nitrogen. While they were not individually assessed, the mound system results in a better outcome for groundwater quality with respect to nitrogen compared to a nearby soil absorption syst em area where high nitrate concentrations can be fou nd only metres away from subsurface trenches (Geary, 2005). In terms of the high phosphorus concentrations which were applied to each mound, the majority of groundwater samples collected had very low concentrat ions (relative to t he septic tank), even though the native soils on site are known to have low phosphorus adsorption. While one sample collected on 23/08/07 at GW4 had a high concentrat ion of Total Phosphorus of 8.40 mg/ L, the majority of samples collected were sufficiently low to suggest that phosphorus was being removed within the mound. Again, processes such as dilution and plant uptake may also be responsible for these reductions but t hey were not individually assessed. The outcome whereby approximately 99% of the phosphorus applied to the mound from the septic tank was lost and not recovered in the groundwater suggested that the treatment system resu lted in a better outcome for groundwater quality. Phosphorus has previously been shown to be t ransported in groundwater in this sandy environment over considerable distances from subsurface trenches (Geary, 2005), so the loss of phosphorus is an important outcome. Of most interest, however, are the substantial reduct ions in the faecal bacteria concentrations in all t he groundwater samples collected (Tables 3 and 4). The 2-3 order-of-magnitude decrease in concentrations wou ld appear to reflect a variety of bacterial removal processes including die-off which occur during the passage of effluent through the mound.

[1l directly linked to t he increased vertical separation distance to the groundwater which is provided by the mound and t he unsaturated conditions which exist as a result of the periodic dose loading of effluent from the septic tank. Compared to higher results obtained from groundwater monitoring adjacent to subsurface absorption trenches in the area, it wou ld appear that the sand mounds monitored are performing very effectively in reducing contaminants entering the shallow groundwater in the area. There has been substantial interest in the overall performance of these systems within various sections of the comm unity given t hat they are su bstantially more expensive t han the soil absorption systems they are replacing. Based on these data they do appear to have a better environmental outcome and do offer a suitable t reatment and land application option for these constrained sites.

Acknowledgments The financial su pport of Port Stephens Council in undertaking the research reported in this paper is gratefully acknowledged as is the field and laboratory assistance provided by Dr Steven Lucas and Katherine Horn from The University of Newcastle.

The Authors

Joe Whitehead (email Joe.Whitehead@ newcastle.edu.au) is a Senior Lecturer at The University of Newcastle, Director of the Centre for Environmental Training and Principal of Whitehead & Associates Environ mental Consu ltants Pty Ltd. His research interests include the design and performance of sand filter and mound systems and the catchment scale impacts of on-site and decentralised wastewater management systems.

Conclusion On the basis of the groundwater results presented in this paper, it is clear that the two sand mounds are performing effectively as treatment systems. The treatment afforded by each of the mounds resulted in significantly reduced contaminant concentrat ions entering the shallow groundwater wh ich, throug hout the study period, was always less than one metre from the surface. The overall efficacy of the treatment system can be

90 FEBRUARY 2009 water

Phillip Geary (email Phil.Geary@ newcastle.edu .au) is an Associate Professor in the School of Environmental and Life Sciences at The University of Newcastle. He has lectured in Environmental Science at the University of Newcastle s in ce 1990 and is currently

refereed paper

Head of the Discipline of Earth Sciences. His research interests include the design and performance of small-scale on-site waste management systems and the transport and fate of contaminants in soil and groundwater.

References Bishop, A. & Whitehead, J.H. 2007. Optimising Mound Designs Incorporating Best Practice and Innovation. In Patterson, R.A. & Jones, M.J. (Eds.) Proceedings of On-site '07: Innovation and Technology for On-site Systems. Lanfax Laboratories, Armidale. Converse, J.C. & Tyler, E.J. 2000. Wisconsin Mound Soil Absorption System: Siting, Design and Construction Manual available at: http://www.soils.wisc.edu/ sswmp/SSWMP_15.24.pdf Geary, P.M. 2005. Effluent Tracing and the Transport of Contaminants from a Domestic Septic System, Wat.Sci. Tech., 51 (10), 283 - 290. Geary, P.M. & Davies, C.M. 2003. Bacterial Source Tracking and Shellfish Contamination in a Coastal Catchment, Wat.Sci.Tech., 47 (7/8), 95-100. Geary, P.M., Lucas, S., Weekes, A. & Horn, K. 2008. On-site Wastewater Treatment Using Sand Mounds near Port Stephens, NSW. In Proceedings of On-site and Decentralised Sewerage and Recycling Conference, 12th-1 5th October, 2008, Australian Water Association, Benalla, Victoria, pp 325-333, ISBN 978-1-92133506-8. Geary, P.M., Stafford, D. & Whitehead, J.H. 2005. On-site Domestic Wastewater Treatment and Reuse. BDP Environmental Design Guide DES 24, Royal Australian Institute of Architects. Lucas, S.A., Geary, P.M. , Coombes, P.J. & Dunstan, R.H. 2007. Evaluation of Nutrient/Microbial Contributions from an Unsewered Area to the Tilligerry Creek Estuary, Final Report to Port Stephens Council. Port Stephens Council. 2005. Onsite Wastewater Standard Designs for Tilligerry Creek. http://www.portstephens. nsw.gov.au/files/50094/File/PSCOnsite WastewaterStandardDesignsforTilligerry Creek.pdf Standards Australia / Standards New Zealand. 2000. AS/NZS 1547:2000 On-site Domestic-wastewater Management. Sydney. USEPA. 1999. Decentralised Systems Technology Fact Sheet Mound Systems. EPA 832-F 99-074. USEPA, Washington DC, September 1999. Whitehead & Associates. 2005. Standard Designs for On-site Wastewater Management Systems in Tilligerry Creek. Prepared for Port Stephens Council. Witz, R.L. 1974. Twenty-five Years with the North Dakota Waste Disposal System. Home Sewage Disposal. ASAE

Publication. Proc 175. ASAE, St Joseph, Ml.

technical features

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onsite treatment

URINE SEPARATION: TRIALS IN QUEENSLAND AND VICTORIA The Editor Introduction Separate collection of urine from specially designed toilets has been in operation in Europe for some years and offers advantages both for sustainability and for decentralised sewage systems. A trial in SE Queensland commenced in 2008 at a private residence in the Currumbin Eco Vi llage. In western Victoria, a trial at a high school of waterless toilets incorporates urine separation. The two papers which follow this introduction (Hood, Gardner, Beal and Crockett, Daniels) summarise their results to date. Public acceptance of the concept is a vital component of the trials, as well as the value of the agricultural use of the stored urine as a nitrogen, phosphorus and potassium fertiliser.

Nutrient Balance Concepts of long-term global sustainability are focussed on energy, water and food. For the latter, apart from soil and water availability, an adequate supply of nutrients is essential. Fossilised nitrogen ferti lisers were exhausted a century ago and large scale agriculture relies on fixation of atmospheric nitrogen, a process which demands huge amounts of energy, currently mainly from fossilised fuel. The supply of the other two essential elements, phosphorus and potassium, relies on mining fossil deposits. These sources are approaching economically viable limits. Mass balance studies in Europe suggest that the average adult excretes about 1.5-3.8 kg N, 0.4 kg P and 1kg K each year which is equivalent to the same mass of nutrients in 200 kg wheat. All of this could possibly be recycled if the compost from waterless toi lets was usable for local agriculture, and of course this has long been normal practice in peasant economies, with inherent health dangers. The question is whether the practice can be replicated in a 'civilised' community without such risks, and in a manner acceptable to a residential community and local

92 FEBRUARY 2009 water

agriculture. (The agricultural use of biosolids from large-scale sewage treatment plants only partially fulfils this function). Another approach is to collect the bulk of the urine from a specially designed low-flush toilet, store it until it is sterile, then use it as an agricultural fertiliser. This approach is based on the fact that of the total amount excreted in faeces and urine, the urine accounts for, very approximately, 80-% of the total excretion of nitrogen, 50% of phosphorus and 70% of the potassium (Larsen and Gujer 1996; Maurer et al., 2003). Urine separation and reuse has long been common in small scale farming, but only recently has it been considered as a component of larger scale agriculture. Several experiments have been conduct ed in Europe where up to 130,000 urine separating toilets are currently in use (Johanssen et al. 2000, van Betuw, 2007, Wilsenach et al. 2002). Another possible benefit of urine separation is the saving of energy in a treatment plant. Considerable energy is expended in removing nitrogen , and phosphorus in particular, in treatment processes and often req uires the inputs of extra chemicals such as methanol or molasses to balance the C/N for the microbial biota. Thus the separation of urine may be particularly suitable for decentralised developments.

Water Economy In a water-short community, or where discharge of sewage effluent to the environment is problematical, waterless, or composting, toilets have long been used. They were first developed in Scandinavia, for use on the rocky islets commonly used for holiday homes where the ' long-drop' used by rural communities was not feasible, and discharge to the sea proscribed. Numbers of commercial designs have been available for over 30 years, and

Continued trials would be valuable.

within Australia are used both in rural residences and in National Parks. Whether, in such situations, the 'compost' is actually used beneficially may be doubtful. One difficulty with such designs is that the volume of urine has to be reduced by evaporation, otherwise the compost becomes saturated and anaerobic. In cooler climates this usually necessitates an electrical heating system. Full or at least partial separation of urine helps to solve this problem. With regard to water-flushed urine separating toilets, trials in Europe (Johansson et al, 2002) have shown that since it only requires 0.1-0.3 L of water to flush the urine (about 10% of the usual low-flush) and design of the bowl enables a 2-6 L flush for the solids, there is a significant saving in flush water.

Conclusion Despite the challenges, it is worth continued trials of such systems to assess their suitability for Australian conditions and the following papers make a start.

References (Extracted from Hood , et al, Benalla Conference paper) Johansson M, et al. 2000. Urine separation - closing the nutrient cycle. Final report on the R & D project: Source Separated Human Urine- a future source of fertiliser for agriculture in the Stockholm region? Prepared for the Stockholm Water Company, Stockholm. Larsen T. A and Gujer W. 1996. Separate management of anthropogenic nutrient solutions (human urine), Water,Science and Technology. Vol 34 (3-4) pp. 87 - 94. Maurer M., Schwegler P. and Larsen T.A., 2003. Nutrients in urine: energetic aspects of removal and recovery. Water, Science and Technology Vol. 48 pp.3746. Van Betuw W., Meis A. and Braadbaart 0., 2007.Technology selection and comparative performance of sourceseparating wastewater management systems in Sweden and The Netherlands. Water, Science and Technology Vol 56. Wisenach J. and Van Loosdrecht M. 2002. Separate urine collection and treatment. prepared for STOWA, Utrecht.

tee h n ica I features

onsite treatment

~ refereed pape r

DOMESTIC URINE SEPARATION CAPTURES PLANT MACRONUTRIENTS B Hood, E Gardner, C Beal Abstract A trial of urine separation has been installed in a residence in South East Queensland and preliminary results are reported have shown that substantial amounts of macro nutrients at high solution concentration (2400mg/L for nitrogen, 480 mg/L for potassium and 140 mg/L for phosphorus) can be recovered whose mass approximates the agronomic needs to produce 200kg of grain per person every year. Other issues discussed pertinent to the safe reuse include human pathogens and trace organic pollutants as well as toilet use behaviour and social acceptance. The latter has been largely positive to date not withstanding some odour issues from the under house storage bladder.

on a number of criteria to maximise the benefit of urine separation. These include:

•

The body corporate was approached by the Queensland Department of Natural Resources and Water (NRW) with a proposal to participate in a trial of urine separation and researchers established contact with interested parties and prepared brochures and information packages outlining the nature of the study, highlighting the benefits of urine separation to the users. Extensive discussions with the voluntary participants were conducted prior to formalising agreements with each household. Discussions were also This paper is a much reduced version of the paper presented at the On-Site and Decentralised Sewerage and Recycling Conference, Benalla, October 2008.

9 4 FEBRUARY 2009 water

• easy to clean • lack of specialised moving parts • compatibility with Australian plumbing fittings • accessible urine pipe for clearing of blockages • ability to collect urine while men urinate while standing • minimal metal components in contact w ith urine • comfort and ease of use (Beal et al., 2007).

Introduction The Ecovillage, a new development at Currumbin, Queensland, has communal treatment of sewage for around 11 O detached dwellings of the total 144 allotments at the site. Energy saving at this development wi ll be particularly important as the aim for the whole development is to achieve zero draw from grid electricity by using solar generation and energy efficiency measures in water and wastewater systems.

• low flush volume, 0.2 litres per half flush

Installation Figure 1. The wall mounted Gustavberg urine separating toilet at an Ecovillage home showing the urine weir at the front of the pan, urine collection pipe and the main waste with the water seal. conducted with the Queensland Environmental Protection Agency, Queensland Health and the Gold Coast City Council. In the event, twenty were agreeable and one house was selected for the initial trial. The willingness of the residents at the Ecovillage to consider urine separation and reuse is an important consideration for this trial, making this study a unique opportunity. Proposals for the trial were summarised in Beal et al., 2008.

Materials and Methods The toilet supplied by the NRW to the participating residents was a Gustavberg urine separating unit that was selected

Direct nutrient recycling is more sustainable and also saves energy.

The first toilet, one of the proposed 20 urine-separating toilets at the site, has been installed in a new residence. The toilet was connected to a 300 litre polyurethane storage bladder via 50 mm polyethylene pipe. The storage bladder was locat ed under the house as close as possible to the toilet while still allowing access for sampling and emptying. Polyethylene fittings were used to minimise scaling problems from struvite deposition, which can occur when using metal pipes, and also to comply with local building covenants. Sufficient fall was incorporated in the collection pipes of 1 in 60 to allow the urine solution to drain to the storage vessel. The toilet was a wall mounted wet design that incorporates a P-bend water seal in both the main waste from the pan and the urine pipe. The wall behind the toilet must also contain the plumbing for both the main waste and the urine pipes so in this residence a plumbing space was incorporat ed in the wall behind the toi let. The wall behind the toilet unit was also appropriately braced with extra noggins to provide a solid mount for the cantilevered toi let, and the waste pipes were routed to clear any floor joists or electrical cable trays.

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~ refereed paper

onsite treatment To separate urine from solids, the pan has an in-built weir at the front of the conventional pan to collect and drain urine to the storage bladder. The flush is dispersed in a normal manner through a flush rim that encircles the entire pan area. The cistern was a dual flush system of 2/4 litre volume and the half flush was not isolated to the front of the pan. The urine separating toilet is shown in Figure 1 as it was installed in the residence. Figure 2 shows the plumbing connection to the storage bladder as installed .

Measurements The urine solution was sampled at intervals that coincided with bladder pump-outs by vacu um truck, usually at 4-5 weeks intervals Three replicates of the separated urine were analysed to determ ine the total nitrogen, total Kjeldahl nitrogen (TKN), ammonium, nitrates, nitrites and total phosphorus as phosphate were also determined. Measurements of pH and electrical conductivity were also recorded at the time of sampling. The urine solution was also analysed for the concentrations of the metal cations potassium, sodium, calcium and magnesium and this allowed the calculation of the sodium adsorption ratio (SAR).

Figure 2. The 300 L urine storage bladder (full) under the residence showing the urine collection pipe and the reinforced vacuum pumpout hose for emptying the bladder.

Residents

3500

Residents C (n•3)

3000

200

....I

1/)

2500

r::

2000

E QI

s 0

I-

150

Tot N TKN NH4 NOx Total P Ca Mg Na K SAR pH Elec. Cond. Volume

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L nil nil µScm·1 Upp/day

2927 2787 2683 140 170 6 <0.5 685 608 72 8.7 17000 4.7

1500

100

1000 50

500

...I Cl

.s::. E

I-

Sample group -

Nitrogen

-+- Phosphorus

Figure 3. The comparison of the total nitrogen and phosphorus concentrations of the separated urine. The volumes of the diluted urine solution were measured by means of a water meter connected to the suction pipe during pump-outs. The reinforced

Ave

Urine*

2483 2440 2377 43 150 9 <0.5 744 456 65 9 17000 2.9

1153 1143 1068

1318 1300 1250 19 87 8 <0.5 407 355 37 9 9700 3.8

4014 3333 3197 680 211 9 <0.5 623 656 54 9 20230 1.9

2380 2200 21 15 178 138 8 <0.5 570 484 52 9 14360 3.1

9200

75 10

<0.5 393 344 33 9.3 8200 2.4

*Data compiled from Wisenach et al. 2002 and Jonsson et al. 2004.

96 FEBRUARY 2009 water

-a 1/)

Table 1. compares the concentrations in the urine, diluted with flush water, with full strength urine as reported by Johansonn. units

...0

The toilet was calibrated to determine the volume of flush water that enters the urine separation plumbing. Volumes were 200 ml for a half flush, and 400 ml for full flush. Two cistern-mounted magnetic proximity switches and a digital counter record the number of full and half flushes.

Sample

250

(n•2)

581

hose that connects between the storage and the pump truck is clear to allow the tester to see that the hose is full and ensure that the meter reads the correct volume. The calculation of the volume of flush water allows the volume of raw urine to be determined by subtracting of the flush volume from the total volume measured during pump out.

Results and Discussion Nutrients

720 170 100 2200 3300 33 6.2-8.2 1.25

The results obtained to date relate to one UST with three different sets of residents measured over five sampling occasions. The storage was emptied prior to each new set of tenants. The variation between sampling events was substantial as shown in Figure 3. The dominant form of nitrogen present in the storage was ammonium with an average concentration of 2,115 mgN/l with a range between 1 ,100 mgN/l and

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~ refereed paper

onsite treatment 3,200 mgN/L (Table 1). Nitrates and nitrites were present at a combi ned average concentration of 178 mgN/ L. The TKN concentration was 2,200 mgN/ L (vs 2115 mg/ L of ammonium-N) indicating only a small amount of organic nitrogen was still present in the solution. These results are as expected as urea is readily hydrolysed microbologically and promoted by the alkaline conditions that accompany the reaction (Jonsson et al. 2004). However anoxic conditions do not favour the conversion of ammonium to nitrate. The average (total) phosphorus concentration was 138 mg P/L and varied between 75 and 212 mgP/L. Concentrations of the major cations in fresh urine were included for comparison in Table 1. Calcium (8 mg/L) and magnesium (<0.5 mg/ L) concentrations are two orders of magnitude less than sodium (570 mg/ L) and potassium (484 mg/L) concentrations, but display less variation between sampling events. The sodium adsorption ratio (SAR) of 52 was averaged over all sampling events. The pH of the stored urine solution remained strongly alkaline and averaged 9.0, whilst the average electrical conductivity was 14,360 µScm· 1 (about 9000mg/ L TDS). The nitrogen available from the urine solution at the Ecovillage is around 3 kg/person/year based on the average concentrations and the generation of urine solution to date. Table 2 shows the comparison between the measured values in urine from the Ecovillage, and the crop requirements for producing 200kg of grain. As can be seen from this table the solution at Currumbin may not be optimal for wheat, however other crops may be more suitable. However significant challenges exist for the w idespread use of urine.

Salinity and pH The solution, with an electrical conductivity of 14360 µscm· 1 and an SAR of 52 would be considered too high for irrigation, however small frequent doses of the ferti liser solution followed by deep irrigation would minimise the risks of salinity and sodicity. The pH of the stored solution was around 9 so that volati lisation of ammonia would occur. Standard agronomic practice suggests that deep placement in moist soil with a fair cation

98 FEBRUARY 2009 water

Table 2. Nutrient loads and crop requirements for wheat. Nutrient N p

Urine solution kg/p/yr

Nutrients (kg) contained in 200 kg grain

3.1 0.2 0.7

4.5 0.6

exchange capacity will limit these types of losses (Johanssen et al. 2000). Irrigation following surface application of urine would seem to achieve most of these requirements.

Struvite Phosphorus in hydrolysed urine can precipitate as struvite, MgNH4 PO4 .6H 2O, particularly if metal piping is used in the collection system causing blockages in pipes and a potential loss of nutrients, as reported in European studies. In this study struvite precipitation was very low in the 50mm polyethylene piping. However the very low concentrations of Mg and Ca in the urine solution compared to undiluted urine (Table 1) strongly suggests these cations have precipitated in phosphorus compounds (struvite and hydroxyapatite, Udert et al. 2003) in the bladder.

Pathogens Urine is not sterile, and pathogens and benign micro-organisms occur. These organisms can include the normal enteric microflora such as Escherichia coli and enterococci spp. , dermal bacteria like Staphylococci spp. or opportunistic pathogens such as Chlamydia and a range of viruses. This occurrence raises concerns for the end use of the urine solution and some form of treatment will be needed. The studies conducted in northern Europe have shown that urine can be effectively sanitised by storage for a period of six months with an average temperatu re of 10°C. A study is currently underway to measure microbial die-off at a range of temperatures and urine concentrations. Further, the concentrations of faecal sterols such as coprostanol wil l be analysed to determine the potential faecal contamination and the associated viral load of the solution (Stewart et al.2007, Jonsson et al., 1997).

Micropollutants Lienert and Larsen, 2007, Pronk et al. 2006 and Escher et al. 2006 have conducted recent studies into the issue of pharmaceuticals in separated urine in northern Europe. Lienert and Larsen 2007, state that up to two-thirds of all

1.0

pharmaceuticals are passed in urine although the route of excretion is often dependent on the individual compound. Ensuring that the urine solution will comply with conservative Australian standards and guidelines, for locally used pharmaceuticals and potential ecotoxins, will be a priority of the research team.

Social Acceptance The volunt ary participants were surveyed to assess their environmental awareness (Dunlap et al 2000) particularly about the issues of using urine separation and use as a fertiliser. At this time the responses wil l not be published as the sample set of respondents is statistically far too small. However, a monthly checklist has established usage patterns of the toilets and any problems. To date all the residents have been happy with the performance of the toilet (aesthetics, flush efficiency, odour, comfort, ease of cleaning) and there has been only one (external) odour issue reported. An important factor in the setup that can affect the dilution rate of the solution is the behaviour of the users and the manner in which they use the toilet flush. Many users may not flush every time they use the toi let especially when they have only passed urine and this would tend to concentrate the urine solution. However, different users, including visitors, may use the toilet differently, fl ushing the toilet at every use. Three groups of users have resided in the dwelling to date and the rate of fill of the bladder has varied with each group. The normal pattern of use appears to be that the half flush is used each time urine is passed and the full flush is used when faeces are passed. With this pattern of use, the bladder fills in approximately 5 weeks. However, one group of users have reported that this particular toilet is efficient enough to use the half flush to remove solids. The fil l rate of the bladder with these users has been much slower than with previous users with the bladder not filled after six weeks.

technical features

~ refereed paper

Conclusion There are several benefits that may be possible with the adoption of urine separation and the reuse of the solution. Separated urine is rich in plant available forms of nutrients such as nitrogen , phosphorus and potassium and reusing a product that is normally considered a waste can lead to energy savings in production of these nutrients and in their removal from wastewater streams. Careful engineering of urine separation and storage systems can reduce the unpleasant aspects associated with this product and losses of the valuable nutrients. Other barriers such as microbial contamination of urine also requires the users to be aware of the risk factors of using human physiological wastes but solutions are being actively sought to enable the safe reuse of separated urine. A further challenge is the small but possibly significant amount of micropollutants such as pharmaceuticals and their metabolites. However the "yuk" factor may still be the greatest challenge to wider applications of urine separation, in spite of strong support to date at the Ecovi llage at Currumbin.

Acknowledgments The authors would like to acknowledge the contributions of the following people: • The participating residents at the Ecovillage at Currumbin. • Chris Walton and Kerry Sheppard, the driving forces behind the development of the Ecovi llage and strong advocates for the introduction of urine separating t oilets at the Ecovi llage. • Anne Gardiner, Joe Lane and Col Christiansen, tireless workers at the Department of Natural Resources and Water.

The Authors

;·I, ,~i

Barry Hood was responsible for running the trial in 2008 and is a research scientist at the Queensland Department of Natural Resources and Water in the Water Cycle Sciences group (email Barry.Hood@nrw.qld.gov.au). Ted Gardner is the Principal Scientist of the group and Adjunct Professor at Queensland University of Technology. Dr Cara Beal is also a research scientist

onsite treatment in the group who initiated the project in 2007.

References Beal C., Gardner T., Ahmed W., Walton C. and Hamlyn-Harris D. 2007. Closing the nutrient loop: A urine separation and reuse trial in the Currumbin Ecovil/age, Qld. Proceedings of AWA Conference, On Site 07, Armidale, September 2007. Beal C, Gardner T, Ahmed W, Walton C, Hamlyn Harris D, 2008. Urine Separation and Reuse Trial. Water, 35 No 1. February, pp . 46-49. Dunlap R.E., van Liere K.D. and Jones R.E. 2000. Measuring endorsement of the new ecological paradigm: A revised NEP scale. Journal of Social Issues Vol. 56 No. 3 pp.425-442. Escher B.I, Pronk W., Suter M. and Maurer M. 2006. Monitoring the removal efficiency of pharmaceuticals and hormones in different treatment processes of source-separated urine with bioassays. Environmental Science and Technology, Vol. 40 no 16, pp. 50955101. Johansson M, et al. 2000. Urine separation closing the nutrient cycle. Final report on the R & D project: Source Separated Human Urine- a future source of fertiliser for agriculture in the Stockholm region? Prepared for the Stockholm Water Company, Stockholm. a) Jonsson H., Stenstrom T-A., Svensson and Sundin A. 1997 . Source separated urine-nutrient and heavy metal content, water savings and faecal contamination. Water, Science and technology Vol.39 No. 9 pp. 145-152. b) Jonsson H., Stinzing A. R., Vinneras B. and Salomon E. 2004. Guidelines on the use of urine and faeces in crop production. Prepared for EcoSanRes, Stockholm. Lienert J. and Larsen T.A. 2007. Soft paths in wastewater management- the pros and cons of urine source separation. Gaia, Vol. 16 No 4 pp. 280-288. Pronk W., Plamquist H., Biebow M. and Boller M. 2006. Nanofiltration for the separation of pharmaceuticals in sourceseparated urine. Water Research, Vol. 40, pp. 1405-1412. Stewart J., Ahmed W., Gardner T. , Brooks P., Katouli M. Tindale N. and Sullivan D. 2007. Identifying human sourced stormwater contamination in three SouthEast Queensland catchments. In proceedings of, Onsite 07, 25-27th September 2007, University of New England, Armidale, Australia. Udert K. Larsen T.A. , Biebow M. and Gujer W. 2003. Urea hydrolysis and precipitation dynamics in a urinecollecting system. Water Research Vol. 37 2571-2582 Wisenach J. and Van Loosdrecht M. 2002. Separate urine collection and treatment. prepared for STOWA, Utrecht.

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~ refereed paper

onsite treatment

URINE-SEPARATING DRY TOILETS AT MARYBOROUGH, VICTORIA J Crockett, E Daniels Abstract A trial of urine-separating dry composting toilets at the Maryborough Education Centre in central Victoria is attempting to demonstrate the benefits of moving towards more sustainable sanitation methods. Preliminary results are reported.

Introduction The project was a result of local community pressure and was based on the encouraging results of a study of the feasibility of use of dry toilets in schools for the Victorian Department of Education and Early Childhood Development. The waterless toilet block, housing six RotalooÂŽ urine-separating composting toilets and two waterless urinals, was opened in April 2007 and has operated for over 250 school days. It is one of 5 student toilet blocks at the school. The project is being funded in part by a $170,000 grant from the Smart Water Fund, an initiative of the Victorian government and the Victorian water industry that supports the development of innovative water conservation, water recycling and sustainable bio-solids solutions. GHD and other participants have also contributed substantially to the project. A report for the Victorian Smart Water Fund (GHD, 2003) reviewed much of the work on urine separation and composting around the world. The final report on the project will be available in mid-2009.

Facility Description Figure 1 shows the toilet block and its greenhouse-type west-facing structure. The three pipes pointing up from the ground on the right are from an in-ground biofilter, which removes odour from the urine and leachate tank vents. The three pipes exiting the roof are the vents from the composters. Figure 2 shows the basement below the toilet rooms with th ree RotalooÂŽ Maxi 2000 composters on the left, t he grey PVC 2700 L leachate tank to collect liquid drained from the composters in the centre (in the floor) and the edge of the black HOPE 4300 L separated urine tank on the far right.

100 FEBRUARY 2009 water

Figure 1. General view.

Figure 2. Basement.

Figure 3 shows one of the urineseparating pedestals. There are two pedestals connected to each of the three composters with 4 pedestals in the female toilets and two pedestals in the male toilets. Within each of the three composters are 8 triangular compost bins sitting on a carousel. Two bins are active at any one time . There are two waterless urinals in the male toilets and these drain directly to the urine tank. Urine pipework from the pedestals comprises 25 mm flexible PVC hose connected to 100 mm graded PVC pipework visible in Figure 2. There are inspection openings at each bend in the rig id PVC pipework.

in a clean st ate and that there are no obvious increased health risks compared to conventional water-flush t oilets. However there have been several instances of smouldering and one minor fire withi n the compost bins caused by students droppi ng lighted material down the pedestals.

The separate collection of urine keeps the com post drier and also reduces the nitrogen-to-carbon ratio to a more optimum value for composting. The drier compost is more permeable to air and this should help the composting process. Ventilat ion is an important part of the process. 17 W electric fans on each composter discharge vent maintain a flow of air down through the toilet pedestals to prevent odour in the toilet room and also draw air in from the greenhouse. Wi nd-driven fans in the vent cowls also provide some air movement. Timers control the electric fans so that energy use and the cooling effect of air is minimised over night.

Usage has been much lower than the expected 200 uses by students and staff per day. Actual use has averaged fewer than 3 student uses per day, with negligible use by st aff. The reasons for this include the location of the toi lets at the far end of the school and bad behaviour by some students around and in the toilets that has discouraged use by others. A significant quantity of data on airflow, air humidity and air and residue temperature has been co ll ected. The literature to date has not included such information. Airflow and evaporation appear to be the main cause of heat loss from the com posters.

Results to Date Data collected on the toilet installation Overall, the project has demonstrated that such toilet s are workable in a school, are odour-free for users, are readily kept

Significant achievements so far.

Figure 3. Urine-separating dry toilet pedestal.

technical features

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onsite treatment Airflow into the open pedestals has been measured on several occasions and was estimated to be typically around 0.24 mis (range 0.18 to 0.3 m/s), which equates to airflow of 23 m 3/hr down the 185 mm diameter pan outlet. This has proved adequate (and possibly more than adequate) to positively prevent odour release into the toilet rooms.

40 35 30 25

Figure 4 shows the temperature history of the compost. The compost has shown no sign of generating heat to date and its temperatu re has closely followed the temperature of the air.

E ~ 10 5

1:5 0

Fly breeding (of the common vinegar fly often found in compost) has only been noted on one occasion, possibly due to the low use and desiccating conditions.

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e .... N

1:5 0

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in N

.... 8 ~

....0 0

~ ~

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Psychrometric calcu lations on the air stream indicate that heat loss from each of the composters is probably of the

· --

~ 10

- F1 Discharge Temp, 'C

F2 Discharge Temp, •c

Figure 5. Air temperatures at composter discharge. 102 FEBRUARY 2009 water

Urine tank temperature has also been monitored and it has ranged from a minimum of 10°C to a maximum of 27°C. This indicates some possible benefit from the greenhouse although, to keep the urine at the highest possible temperature which is thought to aid pathogen die-off, it would probably be desirable to provide both insulation and a means of getting additional heat into the tank from the greenhouse.

35 , - - - - - - - - - - - - - - - - - - - - - - - - - -..

- -

accumulat ed during the day and using it to keep the air stream warm at night. For much of the trial, the venti lation fans have been turned off at night to conserve energy and heat but this was stopped in May 2008 wh ich may explain slightly lower temperatures in August 2008 compared to August 2007.

Figure 5 shows the air temperatures at the discharges of composters. High temperature is achieved in hot sunny weather when inlet air from the greenhouse can reach temperatures of over 50°C. A heater was placed on one of the composters (F2) in June 2007 and after overcoming control system problems it has been maintaining temperature at the discharge of this composter at around 20°c. Note that in wi nter there is little benefit from the greenhouse, partly as there is no provision for storing heat energy

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Figure 4. Temperature of 'compost' in one of the bins.

It has been particularly pleasing to observe that the toilet pedestals have remained clean and (with the exception of one damaged seat) undamaged throug hout the trial despite considerable damage to the building itself. The cleaner reports that it is easy to keep the t oilets clean and he is certain that there has only been odour within the toilet rooms when fans have been off.

25 - - - - - - - - · - · -

refereed paper

M Discharge Temp, •c

order of 250 W and does not exceed 500 W. In fact, the heater installed on F2 has a 500 W element and it has been able to maintain t emperature in F2. Water evaporated is estimated from the same calcu lations to be possibly up to 2 Ud. Water addition has been up to 3 Ud per composter to control moisture but despite this, compost has still remained in a desiccated state. It is concluded that the current air system and greenhouse does little to keep the compost material warm in cold periods but it does generate effective desiccation . This desiccation is probably preventing any significant composting.

Cost The cost of the toilets was expected to be high as construction was slab on ground over rock. The greenhouse structure was also costly. As well as this a number of items were included specifically for the trial. Th us the additional cost was $24,000 per fixture, much more than estimated for a large permanent scheme (G HD 2003). Improvements could be made to the design to reduce cost, energy use for fans and to simplify the system. It is probable that, w ith urine separation, composting in-situ will be difficult to achieve as solids are rapidly desiccated. This makes it doubtful that the costly greenhouse structure provided is necessary. One simple option wou ld be to provide only one or two small bins for solids from each pedestal and to remove desiccated solids reg ularly to a central controlled com posting faci lity. This would significantly reduce the cost of below ground equipment and

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onsite treatment structu res and probably g ive better results in terms of fly, odour and health risk control.

Table 1. Available Analyses of Urine and Leachate. Analyte

Units

Urine and Leachate Quality and Salt Impact Table 1 shows the quality of leachate and separated urine collected in the trial based on two rou nds of sampling. The first round data were estimated from measurements (to allow for some initial water in the tanks). When compared to published concentrations in urine (GHD 2003), these concentrations for urine are of a similar magnitude. The collected urine is dark brown in colour and contains relatively soft sheetlike pieces of what appears to be chemical scale from the tank surfaces. It has a strong, sharp and unpleasant ammonia-amine odour. Leachate is more dilute as a resu lt of regular addition of water to the compost bins to maintain moisture content and minimise the risk of fire.

The Agricultural Trial The urine and leachate was sucked out of the tanks by a conventional eductor truck and carted 20 km to the agricultural trial site. Approval was obtained from various parties on the basis that the materials applied would meet quality req uirements in guidelines published for biosolids application and provided access to the site was limited. Any large scale application wil l require development of specific guidelines and rules. The 585 L of urine and leachate collected was placed in a 600 L storage tank at the farm. Half of t his was pumped into a 440 L water tank on a utility and diluted with bore water. This was t hen sprayed onto a 98.8 m 2 pasture plot. Odour was appreciable but did not last for long. A f urther 440 L of water was applied to wash the material from the pastu re plants. This process was

Figure 6. Urine-fertilised canola plot on final day of trial (day of harvest). Tape is 1.2m high. 104 FEBRUARY 2009 water

refereed paper

Estimated Leachate Composition 27/8/08

pH Specific Gravity Calcium

mg/l

Estimated Urine Composition 27/8/08

Leachate sampled 6/11/08

Urine Sampled 6/11/08

6.5

7.8

4.5

7.7

1.0006

1.0171

1.0064

1.0134

Magnesium

mg/l

161

3.6

170

1.9

Sodium

mg/l

1406

3221

1400

2300

Potassium

mg/l

864

2653

900

2000

Bicarbonate Alkalinity as CaC03

mg/l

121

4926

<10

3000

Carbonate Alkalinity as CaC03

mg/l

Chloride

mg/l

2813

5874

2900

4000

Sulfate

mg/l

693

1800

750

1200

Total Solids (Evaporation at 105Â°C)

mg/l

8237

28421

7300

15000 1500

Suspended Solids

mg/l

683

493

180

Fixed Total Solids

mg/l

6830

14211

6000

9600

7000

14000

Total Dissolved Solids (105Â°C)

mg/l

6830

28421

Organic Total Solids

mg/l

1406

14211

1300

5200

Conductivity at 25Â°C

11049

49263

11 000

31000

Kjeldahl Nitrogen

uS/cm mg/l

151

3221

110

2300

Ammonia as N

mg/l

121

436

1800

Organic N

mg/l

2842

530

Nitrite as N

mg/l

750

Nitrate as N

mg/l

2274

100

1200

Total Oxidised N

mg/l

2274

110

2000

Total Phosphorus as P

mg/l

360

250

Ortho Phosphate as P

mg/l

322

200

E.coli Faecal Streptococcoi

per 100 ml

131

<19

<10

<1 0

Total Viable Aerobic Count

per 100 ml

230000

<10

per ml

100446

1080000

1800

5000

None of the metal concentrations exceeded guidelines for irrigation water. repeated with the remaining half of the material on a plot of growing canola. The plot area was set to give a nitrogen application rate of 50 kg N/ha, based on advice from t he farmer and t he local fertiliser supplier. Applied phosphorus and potassium on t he urine/leachate plots was 4.85 kg P/ ha and 34.6 kg K/ha. Two control plots were fertilised with chemical fertiliser to give simi lar loading rates and these had 440 L of water applied to wash chem ical from the plants. Two unfertilised control plots were also used. Soils on t he trial areas were tested prior to and after the trial and results will be reported in t he final report. The response of the canola was determined by counting pods and seeds per pod, by measuring plant heights and by weighing the crop. Response of pasture was measured by cutting and weig hing. There appeared to be a visible and measureable response on both the pasture and canola w ith the urine/leachate canola plot showing a statistically significant response

compared to the contro l plot and possibly the chemically fertilised plot. The calculated sodium absorption ratios are approximately 20 for leachate and 120 for urine. There was no obvious impact on the plants or soil in the agricultural trial. The sodium load applied was only around 140 kg/ha which is probably less t han is applied annually on most irrigation plots. The results from the agricultural trial indicate that application of urine and leachate to growing canola and pasture as fertiliser is feasible. The materials were easily collected, transported and applied. Figure 6 shows the canola plot at the conclusion of t he trial.

User Survey Results Two user surveys have now been completed. The first, prior to opening of the toilets, indicated a low level of knowledge of composting toilets but considerable agreement that the water

technical features

onsite treatment

refereed paper

····--..... WAI E:.K.'-U ~

Water, the liquid of life The toliets were better than other toliets around the Campus

No response 8%

COMMERCIAL FIBREGLASS WOUND VESSELS

I did not like the

experience 18%

I was pleasentty surprised

The toilets were not as bad as I expected

28%

46%

Total Respondents

Capable of processing up to 396 m3 /hr. Suitable for commercial, industrial, municipal and water treatment applications.

Figure 7. User reactions from the second user survey.

and resource-conservation benefits made sense. There was a significant indication that some people (more females than males) would not use the toilets as they regarded them as inferior or undesirable. The second survey showed that only around 25% of students and staff have used the toilets (17% of females and 35% of males). However, the majority of those using the toilets have found it either not as bad as they expected or were pleasantly surprised by the experience as indicated in Figure 7. Many students indicated that they did not use the toi lets because smokers use them. This is a significant confounding factor in the overall project that is not related to the type of toilet but the location in the school and the behaviour of students.

Odour is effectively contained by use of fans to the extent that t he toilet rooms have no odour. The pans can be kept clean readi ly and absence of flushing does not make the insides of t he pedestals unpleasant. Urine and leachate can be applied to growing crops with benefit. However, much needs to be done for such toilets to gain wide acceptance by users. Guidelines and regulations need to be developed to provide for beneficial use of the recovered resources.

The Authors

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Conclusions Increasing acceptance by st udents, absence of odour in the toi let rooms, absence of fly nuisance, saving of at least 5 kl of water and successful demonstration of the fertiliser potential of separated urine have been the significant achievements so far. There is still prej udice against "different" toilets and composting toilets in particular suffer from some stigma as they are often equated to pit latrines or composting toilets in remote locations which are rarely, if ever, cleaned. The overall conclusion from t he trial so far is that urine-separat ing dry composting toilets of t he type installed at Maryborough is an acceptable, safe and effective sanitation option for a school and for wider application. Water is saved and resou rces can be recovered, probably for no additional energy use compared to conventional sewerage.

Jonathan Crockett (emai l Jonathan.crockett@ghd.com.au) is Executive Consultant at GHD, Melbourne.

ELECTRONIC COAGULATION Precipitates and coagulates a wide range of contaminants.

Elise Daniels (Elise.daniels@ GHD.com.au) is a civil engineer with GHD.

Suitable for grey water recycling applications.

Reference GHD, December 2003, Composting Toilet Demonstration Feasibility Study, Report to the Smart Water Fund, Victoria, can be downloaded from GHD's website using the following link: http://www.ghd.com. au/aptrixpublishing.nsf/Content/ CompostingToilets_prj.

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biosolids

SUSTAINABLE THERMAL DRYING OF SLUDGE: NOT AN IMPOSSIBLE DREAM! D W Browne, T Fernando Abstract

Dreaming of a Better Future

Three developments in series may allow primary and waste sludge to be dried with a net recovery of energy. The first development is a novel electrodewatering process, enabling a belt filter press or decanter to produce up to 40% dry solids. The second is a two-stage dryer, eliminating the need to recycle partially dried product. The third, still in development, is gasification of the dried pellets to provide the fuel for the drying process.

Creating a sustainable process requires thinking in terms of overall processes rather than focusing just on individual unit operations. Flo-Dry Engineering Ltd has considered three areas of improvement that, taken together, wi ll produce an optimal situation in terms of net energy use. These areas are:

The Background Dewatered municipal sludge is unstable and microbiologically unsafe. Converting t his sludge to a safe and useable product has been the subject of much investigation and market activity over the years. One complete treatment is to use thermal drying, but traditional drying processes involve a substantial input of energy and cost (capital and operating). For thermal drying the single largest operating cost is fuel energy. Because of the human origin associated with municipal sludge, a low economic val ue is accorded to the dried product, so there are no easy financial offsets to the costs of processing the sludge. For these reasons simple processes such as partial stabilisation followed by land application have been preferred over more complete processing steps such as thermal drying. A further implication of the energy intensive nature of the thermal drying process is the carbon footprint it produces. Thermal drying is seen to be intrinsically negative (and therefore unsustainable) in terms of net energy use and net emission of greenhouse gases.

No net energy required to safely dispose of biosolids 1 06 FEBRUARY 2009 water

â&#x20AC;˘ Increase the dry solids achieved from dewatering. â&#x20AC;˘ Improve the energy efficiency of the drying process itself. â&#x20AC;˘ Effectively capture the energy in the dried biosolids particle. Doing any of these actions in isolation gives an improvement. But if all three are addressed together then it is possible to move towards a situation of minimal energy input, even after consideri ng all efficiencies of energy conversion. Ultimately the aim is to achieve a situation where the process produces a net surplus of energy. Flo-Dry has been working on the three steps with the intention of achieving a fully integrated and sustainable process.

Working to Achieve the Dream: Improving Dewatering Typical dry solids contents achieved in municipal sludge after dewatering are in the range 15 to 25% DS. This still represents a large amount of water to be removed, including free, interstitial and vicinal water, the latter not removable by mechanical means only. Any process which can remove this loosely bound water at a low energy cost will substantially improve the cost of later thermal processes. A number of workers have reported on the use of electro-kinetic based processes for improving the dewaterability of municipal sludge (e.g. Thomason & Lamont-Black, 2006). These rely on the application of a DC voltage across the sludge, in order to induce an electro-osmotic flow to supplement the hydraulic flow caused by a pressure

gradient (belt press) or centrifugal force (decanter centrifuge) applied to the sludge. Most of the plant designed to perform this task involves a retrofit or enhancement to the dewatering equipment. Preliminary trials

Flo-Dry's process (known as "FEDW") takes a different approach. The DC voltage is applied across the sludge in a much more liquid st ate, namely the 1.52.5% DS sludge obtained direct from the digester or other pre-treat ment eq uipment. This decouples the dewat ering enhancement process from the dewatering equipment, thus making the process able to be retro-fitted to any type or brand of dewat ering equipment. It is considered that the effectiveness of the DC voltage wi ll be much higher when applied across a liquid containing only a few percent solids as opposed to applying it across the more complicated sludge matrix that exists withi n the dewatering equipment. Flo-Dry carried out a series of laboratory and pilot scale tests at its faci lity in Auckland, New Zealand. These tests were made on sludge from five different plants, covering both belt press and decanter dewatering options, and including sludge from plants with extended aeration, SBA and digestion . Based on positive resu lts from this work, a full scale site trial was initiated at the Whangarei Waste Wat er Treatment Plant. The construction and operation of this pilot plant has been described in a paper given to the NZWWA Conference in Christchurch, New Zealand, Oct 2008. The results of the pilot scale tests were confirmed with the on site trial (see Table 1). Note that some of these results probably understate the DS level both with and without FEDW because of the test method inaccuracy outlined below, but the percentage improvement should still be indicative. It was found that testing of the sludge samples for dried solids (DS) content is

technical features

PORTABLE DESALINATION PLANTS INDUSTRIAL WATER TREATMENT SYSTEMS

biosolids inaccurate if the samples are only dried in an oven at 102Â°c overnight, as volatile solids are lost giving low OS readings. This was observed with samples whether treated with FEDW or not. An alternative analysis procedure has been devised which involves pressing out free moisture from the sample before drying, and this has given more accurate absolute values of OS. -

Table 1. FEDW results summary. Experiments at Flo-Dry premises Rodney

Watercare

North Shore

Whangarei

3.4 15.9 21.6 36

2.7 16.3

2.1 15.3 22.8 49

2.5 16.3

Feed sludge OS (%) Oewatered sludge OS (%) - without FEOW Oewatered sludge OS (%) - with FEOW % improvement in OS with FEOW

Applying the FEDW process results in a marked change to the texture of the sludge after the dewatering device. The sludge becomes more friable and crumbly.

This plant was commissioned during November 2008. Results from a series of runs taken between Dec 1 and 4, 2008 showed an improvement in the dewatered sludge from 20-22%DS up to 35-45%DS. This represents an incredible overall reduction in weight of the sludge of at least 38% and up to 48%!

Polymer usage is reduced when using the dewatering enhancement, while solids capture remains well above 95%. This saves operating costs, although the savings are partly offset by the need to sometimes use acid to adjust the pH to an optimal range. It may on occasions also be necessary to heat the sludge.

Working to Achieve the Dream: Improving the Efficiency of Thermal Drying

Demonstration plant - Korea Figure 1 shows a full scale demonstration plant installed at ILSAN WWTP, Goyang City, Korea. The plant has a capacity of 7.5m 3 wet sludge per hour. The feed to the FEDW system was taken from digesters at between 1.5 and 1.8%DS.

Site experiments

Previous papers (Browne et al., 2006, Jordan et at., 2006, Browne et at., 2007) have described a two- stage drying process ("enersaver2") developed by FloDry Engineering. These papers have covered in detail the basis for design of the process and the construction and

23.8 46

23.0 41

operation for 18 months of a working demonstration plant at the Mangere plant of Watercare Services Ltd in Auckland, New Zealand. Sludge handled included not only that from the Mangere plant but also sludge trucked in from four other plants. This experimental work has confirmed fuel savings of around 25% compared to conventional single stage processes, with an expected operational figure of 2.7 MJ/kg water evaporated. In addition, electrical energy use per kg of wet sludge is now expected to be lower in a fully operating "enersaver2" plant than in conventional thermal drying plants Overall it is anticipated that for a system costi ng much the same as a conventional single stage drying syst em, the "enersaver2" plant will achieve a 20% operating cost saving (Browne et al., 2007).

Working to Achieve the Dream: Capturing the Energy in the Dried Biosolids The calorific value of dried Biosolids is typically in the range of 13-18 MJ/kg. _This is similar to low t o medium grade coal. If this energy can be effectively captured, then a major improvement in the economics of thermal drying can be achieved. From the viewpoint of sustainability, it is not essential that this energy capture is recycled directly into the drying syst em, but on occasions this will be possible.

Figure 1. Demonstration plant at ILSAN WWTP, Korea. Table 2. Two-stage sludge drying system performance summary.

Specific gas usage (MJ/ kg evaporated) Electricity usage (kWh/ kg wet sludge)

108 FEBRUARY 2009 water

Average: initial proving tests

Expected: based on full trial period

Conventional thermal drying

2.84 0.048

2.70 0.045

3.5-3.8 0.049 - 0.063

The pelletised product of thermal drying is able to be handled, stored and transported using conventional means. It is also in a form that is easily incorporated with another material for co-combustion. Potential energy capture uses include incorporation into cement kilns, but in some cases it is difficult to persuade end users to pay the equivalent energy price for the material. Instead it merely becomes for the water authority a useful alternative to landfill at a marginally lower cost. It is of more interest to capture the energy in a way that is useable within the

technical features

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biosolids thermal drying process. In this respect Flo-Dry is interested in pursuing the gasification route . If the dried biosolids could be successfully gasified, then the syngas could be used directly in the first stage drum dryer. This mitigates concerns regarding air discharges because the syngas wil l be completely consumed in the burner and the final exhaust air from both first and second stage dryers is treated in a conventional biofilter.

GJ/h

10 8 6 4 2 0 -2 -4

Calculations have been made for a sludge flow of 1 t/h dry solids at various DS concentrations after normal dewatering . Low DS is defined as 15%, medium as 20% and high as 25% in Figure 2. Energy usage is calculated using 3.5MJ/kg water evaporated for conventional thermal drying and 2.7 MJ/kg for the two-stage drying process. An appropriate improvement in dewatering DS when the electrodewatering system (FEDW) is applied is assumed. Allowances are made in the energy calculation for the electrical energy associated with both the drying system and the dewatering equipment, and for the electro-dewatering system where used. We have assumed the efficiency of the gasifier is 75%. Figure 2 then plots the net energy of the process per operating hour assuming recovery of the energy in the dried Biosolids. If t he three enhancements described above are used, at al l levels of OS there is a net positive energy situation. Conversely, if only conventional processes are used there is a net energy requi red even with high DS sludge.

110 FEBRUARY 2009

water

medium DS

lowDS

This is sti ll very much a work in progress as it is taking time to organise the necessary on-site trials. But from a theoretical standpoint, this third step will be the key to achieving the dream of a sust ainable overall process.

high DS

D enersaver2 conventional I!:'.! FEDW+enersaver2 Figure 2. Net energy demand of thermal drying: with energy capture from dried Biosolids.

Conclusion

References

This paper has described continuing work in three areas that contribute to t he more sustainable processing of dewatered sl udge. Viable processes have been devised that produce the expected improvements in terms of dewatering and drying . It remains to 'close the loop' by proving the energy capture step. Once t his is done an overall process will exist where no net energy is required to treat and safely dispose of dewatered municipal and industrial biosolids.

Browne D.W., Kurvink M.R., Fernando T. (2006) "Two is Better than One: A More Efficient Drying System" Proceedi ngs of the 11th European Biosolids and Organic Resources Conference, Wakefield, 13-15 November 2006.

Jordan P.J., Herritsch A., Fernando T., Tomalla M. (2006) "Modelling of a Novel Two-Stage Demonstration System for Drying of Treatment Sewage Sludge" Proceedings of the 11th European

The Authors

, l

Denis Browne

Browne D.W., Kurvink M.R., Fernando T. (2007) "More Efficient Drying of Biosolids: Reporting on the Results of a Demonstration Plant" Proceedings of Ozwater'07 Conference, Sydney, 5-7 March 2007.

Tissa Fernando

Denis Browne is Marketing Manager and Tissa Fernando is Managing Director for Flo-Dry Engineering Ltd, Auckland, New Zealand. Email: info@flo-dry.com

Biosolids and Organic Resources Conference, Wakefield, 13-15 November

2006. Thomason M. and Lamont-Black J. (2006) "Improved Belt Press Performance Using EKG Technology" Proceedings of the 11th European Biosolids and Organic Resources Conference, Wakefield, 13-15

November 2006.

technical features

international sanitation

THE SANITATION AND WATER CONFERENCE 2008, SE ASIA AND PACIFIC Reported by Juliet Willetts, James Wicken and EA (Bob) Swinton This report has been drafted for Water from the very thorough Synthesis Report on the conference prepared by Dr Juliet Willetts (Institute for Sustainable Futures, University of Technology Sydney), James Wicken (WaterAid Australia) and Andy Robinson (consultant). The production of the report was managed by International WaterCentre and funded by AusAID and is available at http://www.isf.uts.edu.au/publications/willetts2009synthesisreport.pdf Throughout 2007, WaterAid Australia, World Vision Australia and the Institute for Sustainable Futures at the University of Technology Sydney, worked together on water and sanitation advocacy. This included the production of the "Getting the Basics Right" report on the water and sanitation situation in South East Asia and the Pacific (Willetts et al, 2007). One aim and achievement of this work was the formation of the "Water and Sanitation Reference Group", currently with about 20 members, to facilitate engagement between AusAID and NGOs, academics and the private sector working in water and sanitation and development and act as a commun ity of practice. In December 2007, AusAID agreed to support a regional water and sanitation conference overseen by the Reference group and organised by World Vision Australia. Piers Cross, Consultant and former Global Manager of World Bank Water and Sanitation Program (WSP) was invited to take on the role of Master of Ceremonies and facilitated the development of the conference program. The conference was held from 27th to 29th October 2008 in Melbourne and was attended by 200 delegates, from a broad

water Future Features MARCH - Recycling, stormwater MAY - Ozwater 09 report, membranes/desalination, climate change JUNE - Pumping & pipelines, industrial waste AUGUST - Disinfection, asset failures, project delivery

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Figure 1. Indonesian villagers and officials celebrating the official declaration of 'Open Defecation Free' status. Photo by Andy Robinson. set of stakeholders including governments in the region, nongovernmental organisations (NGOs), private sector, international agencies and water utilities. This article begins by presenting the main points of the opening keynote address by Bob McMullan, MP and Parliamentary Secretary for International Development Assistance, and goes on to highlight some of the important learning from the presentations made at the conference.

previous level. This is in line with the current Australian Government's commitment to support the achievement of the Millenium Development Goals in the region.

Keynote Address: Bob McMullan, MP, Parliamentary Secretary for International Development Assistance

A draft strategy to guide Australia's work in the area of water supply and sanitation wil l be made available shortly, with opportunity for public consultation. The strategy will have four key objectives: (i) to expand access to the poor, (ii) to undertake sector reforms to improve sustainability, (iii) to improve understanding of how behaviour can be changed t o improve hygiene, and (iv) to enhance aid effectiveness.

The Government of Australia has committed to increasing its Aid budget to 0.5% of GNP by 2015, and in the May 2008 budget allocated $300M to water and sanitation, over the next three years. By the end of the current government's first term the annual foreign aid expenditure on water supply and sanitation will have quadrupled from its

Key features of the strategy will include: doubling the sanitation allocation of the Water Supply and Sanitation budget from 15% to 30%, increasing support to urban initiatives (while maintaining a strong rural-focused program), scaling up of successful approaches (without losing opportunities for innovation) and increasing

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international sanitation engagement and partnership with other stakeholders (e.g. multilaterals, bilaterals, civil society, global partnerships, state and local authorities and private sector). The geographical focus will be South East Asia and the Pacific, while also including new programs in South Asia and Africa, where there are large unserved populations (South Asia) and progress is extremely off-track (SubSaharan Africa). The latter work signifies a renewal of Australian government engagement with Africa and South Asia. Whi le sanitation needs more attention than water it is far more difficult to gain the necessary political wi ll to prioritise sanitation. However, beside the strong moral and ethical arguments that suggest the sanitation situation is unacceptable there is a sound economic argument for increased spending on sanitation. The Draft Strategy includes a focus on clean water, sanitation service provision and hygiene education in schools. Girls need separate sanitation facilities in schools, and until facilities are provided, equity in education will not be achieved. Sustainability is important and represents a long-term challenge. Public awareness is important and increasing community support in Australia and in target countries is critical. In addition, increasing hygiene awareness in communities is critical. The current three-year program, named the Water and Sanitation Initiative, is a start. However, the world com munity faces a generational challenge and wi ll therefore need to be prepared to make a long-term commitment. The Austral ian government is ready to play its part in this and is looking at a much longer program which wi ll have lasting impacts.

The Presentations Twenty-five presentations and workshops followed, with speakers ranging from NGO practitioners, to governments in the region, donors, international agencies and water utilities. This article highlights merely a few of the valuable contributions made at the conference. All the speakers' Powerpoint presentations are published on the conference website at www.worldvision.org.au Speakers included Tom Mollenkopf, CEO of the Australian Water Association, who noted that the incredible enthusiasm expressed by the Australian industry to get involved cou ld be better chan nelled if a framework and support network was constructed. However, any approach

Table 1. Overview of sanitation (UNICEF and WHO, 2008, and WHO and SOPAC, 2008). Sanitation coverage

South East Asia

378 million people in the region, 67%, had access to improved sanitation facilities in 2006, this is 156 million more people than in 1990. The population without access to sanitation decreased by 32 million, from 219 million in 1990 to 187 million in 2006. However progress across the region is uneven - in 4 countries in the region coverage is 52% or below, namely Indonesia, Timor Leste, Lao PDR and Cambodia, and one in five people in South East Asia (102 million people) continue to practice open defecation.

Pacific

The Pacific Islands are not on track to meet the MDG sanitation target and achieving this will require an effort nearly five times higher than in the 1990-2006 period. In the Pacific Island countries the number of people served with sanitation increased from 2.9 million in 1990 to 4 million in 2006. However this is only 48% of the population and the huge population growth overshadowed these achievements - the number of unserved has increased by 30% from 3 million in 1990 to 4.3 million in 2006. In this region too, progress is incredibly uneven - nearly 40% of the Pacific Island countries have coverage with improved sanitation below 50% {including Papua New Guinea and the Solomon Islands), while three countries {Cook Islands, Niue and Samoa) have achieved universal access.

must consider cultural sensitivity, gender and engineering solutions appropriate to local skills, capacity and aspirations. There was a final message from Tony Kelly, CEO of Yarra Valley Water, and Chairman of WaterAid Austral ia, on the need t o build people's capacity by increasing knowledge, skills and experiences. Support for local educational institutions, networking and conferences enhances the knowledge of leaders, managers, planners, engineers, hygiene educators and others. Australia can: (i) lend its knowledge, skil ls and experiences; (ii) establish educational institutions; (iii) create governmental

links; (iv) engage with professional associations; and (v) encourage water utility partnerships. A word of caution is that Austral ian solutions are unlikely to work for the region, and attention to the economic and environmental sustainability of approaches and solutions in the developing country context is paramount. Clarissa Brocklehurst, Chief of Water and Environmental Sanitation Section, UNICEF, reported on the current status of WASH (Water, Sanitation, Hygiene) in East Asia and the Pacific, drawn from the latest Joint Monitoring Program snapshot report (UNICEF, 2008).

Table 2. Overview of safe drinking water access (UNICEF and WHO, 2008, and WHO and SOPAC, 2008). Safe drinking water coverage

South East Asia

86% of the population in South-east Asia uses an improved source as their main source of drinking water. The region almost met its MDG target for water in 2006, nine years ahead of 2015, and eleven of the countries in the region have met this target. If these trends continue, 93% of the population in the region will use an improved drinking water source in 2015, 44 million short of universal access. In only three countries in the region coverage remains below 65%, Cambodia, Lao PDR and Timor Leste.

Pacific

Despite being on-track as a country, the largest number of unserved in the region are in Indonesia (46 million of the 82 million unserved). The Pacific islands are not on-track to meet the MDG target for water. In the Pacific 46% of the population have access to an improved water supply, this is around half the global coverage level, and access to a piped supply is only 13%. There are huge disparities in access, three in five of the region's countries have coverage beyond 80% {smaller population countries), however Papua New Guinea, with over three quarters of the region's population determines the average. Increasing access to piped water has almost stagnated with only 300,000 people gaining access to this service since 1990 against population growth of 2.5 million over this period. The Pacific will require an annual level of effort over five times higher than between 1990 and 2006 to achieve the target.

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international sanitation Access a nd needs T he key points are that sanitation is lagging well behind water; that regional figures, in aggregate, mask extremely uneven progress across the region and the significant need for up-scaled activity in several countries. Table 1 summarises the sanitation statistics. Table 2 the water statistics. There are stark rural-u rban disparit ies: In South-east Asia, seven out of ten people without access to improved sanitation and drinking water facilities live in rural areas. The disease burden and health costs are higher in rural areas: for example, in Indonesia and Vietnam, infant and child mortality rat es are 75% higher in rural than in urban areas; water-related infectious diseases 53% more prevalent; and child malnutrition rates are 22% higher.

• Indonesia, 110 • Viet Nam, 31 • Philippines, 19 • Cambodia, 10 Myanmar, 9 Papua New Guinea, 3 • Lao People's Dem. Republic, 3 • Thailand, 3

Figure 1. 192 million people without improved sanitation facility in South East Asia and the Pacific (UNICEF and WHO, 2008).

• Indonesia, 65.6 • Viet Nam, 10.3 • Cambodia, 9.6

In the Pacific, improved drinking-water coverage in rural areas is barely half that in the urban areas. However, the number of unserved people in urban areas is rising, as is the threat posed by open defecation and unsafe excreta disposal in densely populated urban settlements, thus urgent actions are needed in both rural and urban areas. Many people in the East Asia Region use sanitation, but of low quality - the challenge for this segment of the po pulation is to upgrade facilities. In contrast, one in five people in South East Asia (102 million people) continue to practice open defecation, suggesting that the challenge here is changing behaviour towards the use of basic sanitation facilities (Figures 1, 2). The discrepancy between urban and rural coverage for sanitation is summarised in Table 3. Although the data for the Pacific region is poor, what data we have show that it is lagging very badly. In add ition, although the p ercentages for the rural population are worse, rapid urbanisation presents a " hidden" problem wit h low po litical priority. Large informal and slum housing areas are expan ding and investment in basic urban infrastructure is not keeping pace, with sanitation being the laggard. Clarissa also presented a thoughtp rovoking session on Myths and

Philippines, 7.1 Myanmar, 2.8 • Lao PDR, 2.6 • Papua New Guinea, 1.1 • Timor-Leste, 0.5

Figure 2. More than 100 million people still practice open defecation in South East Asia and the Pacific (UNICEF and WHO, 2008). Realities in Rural Water Supply (summarised in Box 1).

Why some countries make better progress Almud Weitz, Regional Team Leader Water and Sanitation Program, East Asia and Pacific, examined the characteristics of on-track and off-track countries in terms of t he MDGs. Experience shows that resources are not the only constrai nt for sanitation development - poor countries can and do outpace richer countries in terms of MDG achievements. What matt ers most is prioritisation, as policy, funding and action all follow. On-track countries are characterised by clear prioritisation of sanitation within national development frameworks; a demand-based sanitation policy implemented through agreed st rategies; application of policy-based financing strategies; specific approaches to the provision of sanitation services for

Table 3. Sanitation Coverage (estimated % of population ) (UNICEF and WHO, 2008).

South East Asia Pacific

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Urban

Rural

58 43

the poor; and increased participation of users, civi l society and the private sect or. She summarised the, unfortunately, com mon perceptions about sanitation in some countries:

• Sanitation is considered a 'private matter', so the responsibi lity is being passed down fro m central to local governments, from local governments to households ("not my problem"). • Water will flush it out: East Asia is a predominantly 'wet ' region, so the rains will clear it up. • Sanitation services are 'extras': better services are seen as 'add-ons' once economies have grown to a certain level, not as foundations for growth. • Lack of compelling data for policy makers: true costs of lack of sanitation are not readily available for policy makers to make their case. • Competing priorities: addressing sanitation can lose out when countries are faced with many other urgent issues. To address the latter problems the WSP conducted a study " Economic

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international sanitation Box 1. Myths and reality in global rural water supply. Clarissa Brocklehurst

• Myth 1 - government and donor money is the most important source of finance for rural water supply. Reality: Recent data shows most expenditure in the sector is from households and private sector. This implies we need to find ways to trigger and support household investments. • Myth 2 - external resources for rural water supply are going to the right places. Reality: New data shows most aid flows are going to improving services to the already served. This means we need to track aid better; work out how to use aid in the most optimal/catalytic way recognising the small proportion of total funds required that aid can provide. •

Myth 3 - community management of water supply is always good. Reality: New data on the rate of non-functioning hand-pumps in many countries in Africa is very high and should make us question our faith in the community management approach. This implies the need to develop and support alternative models (self-supply, private sector services) and focus on sustainability. • Myth 4 - water professionals understand what rural people want. Reality: Rural people are not homogenous; most communities use water for multiple uses; and people value reliability and convenience rather than 100% safe water. This means we need to move out of comfort zone and take up new concepts such as home drinking water treatment (rather than an over emphasis on quality at source), lightweight pumps, manual drilling, water for multiple uses (kitchen and market gardens). • Myth 5 - the private sector is being harnessed to its full potential. Reality: To meet the MDGs in Sub-Saharan Africa 35,000 new borewells are needed each year governments and donors do not have this capacity. However donor practices normally stifle rather than enable the private sector. The implications for donors are a need to review procurement systems and examine ways to encourage (rather than discourage) a vibrant private sector.

Impacts of Sanitation in Southeast Asia" covering Cambodia, Indonesia, the Philippines, and Vietnam , published in November 2007. They found that these four countries lose approximately $9 billion per year due to poor sanitation (2% of combined GDP, varying from 1.3% in the Philippines to 7.2% in Cambodia (WSP, 2007)). Impact on health resources accounts for 50% of losses, followed by water resources (29%), environment, other welfare, and tourism.

Are external investments well targeted? Clarissa Brocklehurst examined recent data made available through the World Health Organisation Global Annual Assessment of Sanitation and DrinkingWater (GLAAS) (2008) showing that most expenditure in the sector is by households and the private sector, with only a small proportion of expenditure financed by external aid or government. The financial needs are far too high to cover through public finance and aid flows, so governments and donors need to use their funding more creatively in order to trigger and support household investments. These data also highlight the limited external aid that goes to the countries that need it most - the poorest and most off-track countries. Furthermore, aid is being used to give incrementally better services to the already served, through

upgrading of urban systems that serve only some sections of a city, despite other systems falling out of service and many areas without any systems. There is insufficient focus on long-term sustainability and renewal and, as a result, the number of unserved in some

regions is increasing as systems breakdown. More than one paper focussed on how supply of 'hardware' by a wellintentioned funding agency was useless unless accompanied, or best preceded , by a 'software' program to change perceptions and behaviour. This is particularly true for sanitation interventions. Andy Robinson , international sanitation specialist, described how subsidies for rural sanitation with a limited focus on behaviour change resulted in abandoned toilets, and expensive designs led to low cost-effectiveness. His paper is summarised in Box 2.

WASH and other Millennium Development Goals WASH is increasingly accepted as critical to achieving other Millennium Development Goals (MDGs), including improving goals about health, education, gender equality, education amongst others. Discussions at this conference highlighted that stronger inter-sectoral linkages are important to ensure WASH actively contributes towards the achievement of other MDGs and, perhaps counter-intuitively, WASH may compete with other MDGs without more holistic development planning and implementation.

BOX 2. Changing Sanitation Behaviour. Andy Robinson

Traditional subsidy based sanitation programs have not been successful and the Community Led Total Sanitation (CLTS) is an alternative approach that addresses many problems of the past. The main messages were that: ., • CLTS recognises that to maximise the health impact of sanitation everyone needs to use a latrine all the time. • rapid behaviour change is possible with the right tools (for example in communities in Indonesia, everyone stopped open defecation in six weeks) (See Figure 1). • there is a need to encourage low-cost, local, technical solutions (e.g. Figures 3, 4 and 5). • small steps, phased programs allowing time for perceptions and priorities to change (phased incentives/rewards). • large scale sanitation improvements require cost effective approaches - if we are thinking national level must think about cost per outcome. • public finance should be used to finance collective outcomes. There has been an evolution in thinking around sanitation behaviour change along the following continuum: 1. Health Improvement (germ theory: you'll get sick without a toilet) Mode: Lecture style (teacher to student) Result: effective on educated, health-interested individuals 2. Comfort and Prestige (toilet is a home improvement) Mode: Marketing style (salesperson to customer) Result: effective on non-subsistence households 3. Shame and disgust (open defecation leads to ingestion of excreta) Mode: Self-discovery (site visit, excreta calculation, contamination routes) Result: universal effectiveness, even for poor households It is vital that all organisations working in a given area follow the same approach to sanitation - this should be set by local government. Indeed, once convinced of an approach local government can become powerful advocates at high levels of government, as has been the case in Indonesia.

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international sanitation Contributions to other MDG goals could be enhanced by stronger focus on cross-cutting issues, such as gender equity. Improved water and sanitation facilities and hygiene promotion in schools c an lead to greater school attendance by girls (relating to MDG Goal 2 for universal primary education), with subsequent gains in women's empowerment (MDG Goal 3 for gender equality and empowering women).

Box 3. The Global Sanitation Fund, Water Supply and Sanitation Collaborative Council (WSSCC).

There are significant challenges associated with engaging and supporting women in decision-making where this is not the cultural norm , requiring substantial gender training. Whilst not discussed directly at the conference, the minimal presence of women in government agencies (e.g. public works , environment, water and sanitation engineering) and programs is another barrier to maximising gender equality outcomes.

Box 4. NGO Partnerships and Roles.

Another area of potential contribution is the value of nutrients from human waste for fertiliser, which can assist with food security and poverty (Goal 1). The International Fund for Agricu ltural Development (IFAD) is currently investigating improvements to food security for poor smallholder farmers through recycling and use of waste products in agriculture. However, significant shifts in beliefs, habits and policies will be required before some cultures are convi nced that this is a safe and acceptable practice. Providing access to clean water and sanitation, potentially undermines other MDG goals, particularly in urban or more

Over-engineered latrine designs

Supply-driven (single model)

l Limited user choice

l Little behaviour change

Barry Jackson As Manager of the fund he presented a case study on the Global Sanitation Fund - Opportunities for East Asia and the Pacific. The Fund was launched in March 2008 in seven countries; Round Two countries are now being identified and Expressions of Interest received from this region. The fund is a pooled fund supporting work to raise awareness, create demand, and work with government and the private sector to meet demand. The fund will: work at scale through proven approaches, insist the poor are included, be demand driven, innovative and function at scale.

Dr Juliet Willetts Recent research for AusAID was conducted to provide clarity on the present and potential role of NGOs in the sector, including a strategic approach to facilitate and maximise benefits from engagement, and specific investment options for AusAID to consider. A large number of NGOs were consulted (13 Australian-based and 73 in-country, including both international NGOs and local NGOs). It was found that NGOs can and do play an important role in the water supply, sanitation and hygiene (WASH) sector, and there is opportunity for other organisations to engage more strongly with NGOs where they offer benefits. Examples include roles in: (i) Facilitation of service delivery - direct or as an intermediary (ii) Advocacy and accountability - to promote the issue among community and policy makers and to increase effectiveness through ensuring transparent processes and appropriate oversight (iii) Community education - awareness-raising, sanitation and hygiene promotion and marketing (iv) Mobilising other actors - building partnerships and promoting networking between communities, private sector and local, provincial and national governments (v) Capacity building for local governments, service providers, civil society groups and end-users (vi) Research and innovation - piloting of innovative, locally adapted approaches and technologies (vii) Engaging in policy dialogue - bringing grounded perspectives to the table. NGOs should look to maximise their strategic influence and coordinate with other sector actors. NGOs should build on their strengths in community mobilisation and engagement and working in remote and challenging environments, and look to overcome their weaknesses in cases of inadequate technical expertise and capitalising on small-scale successes to have larger-scale impact. They have significant capacity and interest to support an increasing volume and quality of work in this area the region. See full report (http://www.isf.uts.edu.au/publications/willettsetal2008ngopartner.pdf and ) or conference paper presented at IWA Hanoi Sanitation Options, November 2008 for further information.

densely populated areas. Approaches that ignore the negative impacts of untreated wastes will adversely affect MDG Goal 7 to ensure environmental

Unaffordable latrines (for poor)

... ... l ... .; ....

Need for subsidv

Rationing {limited numbers)

Partial coverage

Targeting issues

l Risk of subsidy capture

Continuing open defecation

Slow progress + limited benefits

Figure 3. Over-engineered latrine designs increase the unit cost of sanitation facilities, thus run the risk of rationing, targeting issues, partial coverage, and continuing open defecation. Source: Andy Robinson, independent consultant. 116 FEBRUARY 2009 water

sustainability, and will also impact on other goals such as child mortality (Goal 4) and disease control (Goal 6). The use of water to transport human wastes is a critical issue, as it results in a huge quantity of sewage and wastewater that contam inates water-bodies resulting in both health and environmental issues. Evidence of this effect is already obvious in Pacific Islands with contaminated shallow ground water tables (e.g . Tuvalu), and in Indonesia, where densely populat ed islands like Java have now heavily contaminated water bodies.

Looking Ahead This conference is part of an increased effort to accelerate efforts to achieve the MDGs in the region and the event must be seen as just the beginning. The conference statement {http://www. worldvision.com.au/learn/conferences/ watsan/files/pdf/ConferenceStatement. pdf) provides a framework in wh ich the sector might advance, keeping the poor, and particularly women, at the core of all

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international sanitation MP, at the start of the conference, Australia's response to the crisis is t he Water and Sanitation Initiat ive (2008201 1) and t he formulation of a new Water, Sanitation and Hygiene Strategy.

• •

:::9env1roaer industries

Both of these will be informed by the outcomes of the conference presented in this report. In conclusion , the Sanitation and Water Conference resulted in a reinvigorated sector in ou r region, ready to launch off from the International Year of Sanitat ion and t he MDG mid-point year, with new knowledge and passion to turn around the WAS H sector in this region.

References Figure 4. A low-tech latrine using local materials, Muara Enim district, South Sumatra. Photo Andy Robinson.

UNICEF and WHO (2008) A Snapshot of Drinking Water and Sanitation in SouthEast Asia and the Pacific. A regional perspective.

efforts. Three key paradigm shifts demanded by the conference were:

WHO and SOPAC (2008) Converting commitment into action: Sanitation, hygiene and drinking water in the Pacific Island countries,

• to rethink t he role of aid and public finance and use it more strategically to leverage household and private sector investment;

Willetts, J ., Mitchell, C and Garrard N. (2007) Getting the Basics Right, http://www. wateraid.org/documents/water_report_ final_03_07_1.pdf

• to do sanitation differently, always including a software element in interventions, and aiming for collect ive outcomes by triggering large scale and rapid sustainable behaviour change; and

WSP (2007) Economic impacts of sanitation in Southeast Asia: Summary The World Bank, Water and Sanitation Program East Asia and Pacific, <http://esa. un.org/ iys/docs/san_lib_docs/ ESI SynthesisReport.pdf>.

• t o use more sustainable approaches, including low- cost appropriate locallydeveloped tech nologies, demand management and leakage reduction, consider water resources management and decentralised and alternative sanitation solut ions.

For further information please contact J uliet Willetts: Juliet.Willetts@uts.edu.au.

To contact the Water and Sanitation Reference Group please contact James Wicken: james.wicken@wateraid.org.au

Unsurpassed Quality

The Water and Sanitat ion Reference Group is well positioned to promote dialogue between Australian sector players to encourage learning and exchange of lessons in implementation. Its envisioned role over the coming years is to improve and monitor the quality and volume of Aust ralia's foreign aid for sanitat ion, hygiene and water, particularly through building up and sharing the evidence base on effective approaches, and to increase awareness and support amongst t he general p ublic for ending the global WASH crisis. The Reference group has comm itted to following up participati ng agencies' use and adoption of t his framework in a future process in 2010, as all st akeholders have vital roles to play. The conference came at an opportune time to provide vital inputs to AusAID processes. As outlined by Bob McMullan,

Uncompromised Protection

:-HYDRO-DYNE ~'' Engln...-tng. In<.

Figure 5. A raised latrine in an area of high water table in Cambodia. Photo Andy Robinson.

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refereed paper

SUSTAINABILITY WITHIN THE AUSTRALIAN WATER INDUSTRY: AN OPERATIONAL DEFINITION D Marlow, R Humphries Abstract Sustainability is a concept that has been discussed widely and adopted by many organisations. Wh ile the philosophy and int ent of sustainability is well defined, in an operational sense there remains a lack of clarity about what sustainability actually means. Drawing on the literature and comments made in interviews undertaken with sector professionals, this paper revisits the meaning of sustainability and sustainable development and shows that the concept can be thoug ht of at a range of levels and scales, which is the source of much of the confused debate in the sustainability space. To contribute to the development of clear and concise terminology, an operational definition of sustainability is also proposed, expressed in terms that align with economic and business language.

Introduction The Austral ian water sect or today faces a complex range of chal lenges, including declining availability of water from the terrestrial environment, an unstable global economy, increasing energy prices, and increasingly complex regulatory and social circumstances. Meeting these challenges is vital if water utilities are to maintain the confidence of the communities they serve. Adapting business thinking to cope with emerging realities requires a new operating paradigm to be embraced - that of sustainability. Sustainability is a concept that has been discussed widely and which has been adopted by government at national, stat e and local levels, and by many businesses. In fact, the level of commitment is such that one could easily draw the conclusion that the concept of sustainability is thoroughly understood and well defined. However, at a recent WSAA workshop focusing on energy and sustainability (held in Newcastle, November 2008) a persistent theme played in the background of the

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vein, WERF (2007) notes sustainability can be considered from a number of perspectives, including the context of the organisation or enterprise, w hich implies the ability of a business to remain effective and functional despite large scale changes (or shocks) in its operating environment.

Figure 1. The Dependence of the Economy on Society and the Biosphere. discussions - that there was still a lack of clarity on what sustainability actually means to water sector professionals, and on how the concept may be usefully and pragmatically applied to the solution of real business problems. With these issues in mind, the authors feel that there remains an imperative to seek clarity over what is actually meant by sustainability in an operational sense. To this end, this paper explores the meaning of the terms 'sustainability' and 'sustainable development', both from the perspective of overall philosophy and from the operational perspective of the Australian water sector. The discussions draw upon the literature and also the opinion of industry professionals compiled during recent qualitative research (see Marlow, 2008a).

Sustainability as a Multifaceted Concept At a basic level, 'sust ainability' merely implies the ability to continue to do something indefinitely. A focus on a long term view is thus always implicit within any use of the word , but after that it can be used in a variety of ways. For example, 'sustainable' can be used to refer to the financial longevity required t o deliver water services into the future (e.g. Gohier, 2005; Allbee, 2005). In a similar

Aligned with economic and business language.

Sustainability is, however, often taken to mean much more than just business longevity, since it is (or is becoming) synonymous with the concept of 'sustainable development', a widely quoted definition of which is given in the report from the Brundtland Commission (WCED, 1987) as: "Development that meets the needs of the present without compromising the ability of future generations to meet their own needs." The terms of reference outlined in the Brundtland report had a very strong focus on environmental issues, explicitly couched within an anthropocentric viewpoint. Emphasis was also given to the role that the environment plays in underpinning economic and social development, considering the limitations imposed by the present state of technology, social organisation and the ability of the biosphere to absorb the effects of human activity. Similar concepts were later restated in the Millennium Ecosystem Assessment (MEA, 2005), and have been embodied in simple conceptual models such as that shown in Figure 1, which seek to illustrate the critical dependence of both human society and economic activity on the biosphere (see for example, Porritt, 2005).

Putting Sustainability into Action - Issues of Scale While the Brundtland definition of 'sustainable development' is explicitly global in scope, the practical adoption of sustainability requires action to be taken at a local level, so a multi-scale view of sustainability is needed (hence the well known phrase 'think globally, act locally).

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, refereed paper

In reflection of this, Kain (in Soderberg & Karrman, 2003) noted that sustai nable development needs to be considered within a framework simi lar to that illustrated in Figure 2, which can be summarised thus: 1. Ethics: the ethic and philosophy of sustainable development ; i.e. the valuedriven ideology ... the core ideas, values and principles applied at multiple scales up to and including the global and intergenerational scale. 2. Strategy: a commitment to the et hic of sustainability, embodied w ithin the pol icy framework of a region , nation or company, and applied over t he planning horizons and influence of t he entity in question.

Ethics

Sustainable Developme11t

Action Figure 2. Sustainability as a Non-Hierarchical Interdependent Framework. Table 1. Sample of Interviewee's View of Sustainability. • Sustainability means ensuring something can happen forever; the formal/dictionary definition of sustainability. It is couched in terms of balancing TBL outcomes with the future in mind ... • Sustainability is a process you can carry on indefinitely; for example, if a borefield is managed in a sustainable manner, a certain amount of water can be taken out forever ... there is generally an economic, social and environmental aspect to sustainability

3. Action: local action and initiatives, including sustainability expressed as a set of design constraints and measured as an operational indicator.

• Sustainability is the provision of services to improve quality of life for customers and stakeholders; there is an intergenerational aspect, and also a social good and environmental aspect.

With this framework in mind, some of the potential issues with the vagueness of the sustainability debate can be elicited. For example, in any debate over sustainability it is possible that disagreement and misunderstanding can arise because issues are being viewed from different layers of this framework without parties being aware of the difference in each other's focus. Imagine, for example, an emot ive debate over the need for desalination plants. An opponent could argue from the ethical consideration that it is ' more sustainable' to implement demand-side options, but couch objections in terms of technical issues that can not be 'designed out' (e.g. energy demands or saline waste streams). Any attempt by a proponent to argue from a technical perspective wou ld then fail to address the underlying ethical concerns of the opponent.

• Previously, sustainability meant managing environmental impacts; these days, economists have hijacked the term; it now is about economic issues. There is certainly a TBL element now; what is the best you can do and continue to do without causing damage

A key barrier to achieving clear communication is that identical terminology is used to refer to sustainability wh ichever level of the framework is being considered; i.e. we tend to refer to 'sustain able development' and 'sustainability' at multiple scales and meanings using exactly the same terminology. Much confusion and perhaps argument would t hus be avoided if we adopted terminology that clearly indicated which level of sustainability was being discussed, rather than just using 'sustainability' or 'sustainable' as blanket terms.

• Sustainability is about meeting the needs of current and future generations; leaving the world in a better way ... of course, the key challenge is to define what is 'better'

• Sustainability is ensuring whatever activities are undertaken don't detract from society or the environment and future generations. • Sustainability is about leaving the planet in a better shape, it is about inter-generational equity, taking a long term views on achieving acceptable outcomes. It is about a whole of system, whole life assessment of issues with a long term view • Sustainability from a philosophical point of view tends to imply environmental sustainability; providing service within the carrying capacity of the natural environment. • Sustainability is a process a journey, rather than a specific thing, whereby what you do shouldn't detrimentally effect future generations.

View from the Australian Water Sector Given the prevalence of 'sustainability' as an overarching busi ness concept in t he Australian Water Sector, it is interesting to consider what water sector professionals understand by the term. To answer this and similar questions, Marlow (2008a and 2008b) undertook qualitative research using interviews as a data collection tool (e.g. Myers & Newman, 2008) with a t hematic approach to data analysis (e.g. Wang & Roulston, 2007). During the interviews the question was explicitly asked; 'What does the term 'sustainability' mean to you?'. Examples of comments made in response to this question are given in Table 1. With reference to Table 1, it is interesting to note that many of the concepts voiced reflect those associated w ith the Bruntland definition of 'sustainable development'. However, interviewees spoke from different aspects of the framework outlined above; from the philosophical through strategy

and down to operational aspects. Various scales were also referred to, ranging from the local through to t he global scale. To summarise the collated opinion, various themes were identified in the interview responses, and a count made of the number of times each theme was mentioned. Figure 3 shows a plot of these counts expressed in terms of the percentage of individuals who mentioned each theme. In total, twenty individuals gave an explicit answer to this question, and they can be divided into two professional roles: those concerned with asset management (AM) and those concerned with sustainability (SUS). Sustainability was considered by the majority of these interviewees in terms of environmental and social outcomes, with other themes like intergenerational equity also bei ng mentioned. It is interesting to note that four out of seven sustainability professionals referred to business sustainability (i.e. business continuity) directly in their response to this question, in contrast to just one asset manager

water FEBRUARY 2009 119

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regulation overall. Of these, three worked at an authority w here there had been an explicit initiative to communicate to staff that broader sustainability issues had to be set within a framework of overall business sustai nability if t hey were to be delivered. It was stated during the interviews that t he driver behind this initiative was related to the fact that individuals w ith in tne authority were more naturally inclined t o focus on environmental sustainability, rather than business sustainability per se. Th is example illustrates that a water authority can undertake initiatives to modify people's interpretation of sustainability in a way that is useful to the business without creating conflicts with t heir personal value systems. Overall, the view of sustainabi lity expressed in the interviews was closely aligned with the philosophy of sustai nable development. Given t he issues with the practical application of this philosophy, it can be inferred that individuals have a clear idea of what needs to be achieved in principle, but perhaps don't have a clear idea of how this can be attained. This provides some support for the earlier assertion in t his paper that a clear operat ional definition of sustainability is required.

An Operational Definition of Sustainability To contribute to the debate on what sustainability actually means in an operational sense, a definition of sustainability is proposed below. The starting point for developing this definition was to review the meaning of sustainability, as described above, and then to consider what would be required of any such definition. The main requirements identified were that a definition should: 1. Provide a basis for improving communication and faci litate assessment of whether 'sustainability' has been achi eved.

2. Not exclude the opportunity of becom ing ' more sustai nable' or preclude t he. possibility that a once-sustainable water authority could be shown to have slipped into unsustainable operations; i.e. a dynamic, rather than static, measure should be embedded into the definition. 3. Be couched in positive aspirational terms and not just in terms of ' no further deterioration', especially since there is compelling evidence that human pressure on the planet is t ruly unsustainable (MEA, 2005).

120 FEBRUARY 2009

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Key: 1) Maintaining assets and service into the future; 2) Business sustainability (continuity); 3) Environmental outcomes; 4) Social outcomes; 5) Intergenerational equity issues. NB: Number of interviewees making an explicit response to this question was 20 (13 interviewees from asset management roles, AM, 7 interviewees from sustainability roles, SUS).

Figure 3. Themes Noted in Opinions of Sustainability. 4. Address the needs of the now, not just the needs of the future, so as to engender a positive drive towards action. From the outset it was recognised that a definition could be constructed from a range of ethical perspectives, and it would be very difficult to embrace the myriad positions t hat can be taken (e.g. fro m deep ecology through to an anthropocentric view of the environment). As such, it was considered pragmatic to set the wording of the definition in business t erms, since it is intended to apply to the operat ions of a water business. Furthermore, it was also considered desirable for the definition to be couched in t erminology that would resonate with those in business orientated roles. A definition that meets all the above criteria is: "For a water utility, sustainability is practically achieved when all its activities, both internal to the business and across its supply chain, achieve net added value when assessed across each of the triple bottom line outcomes (financial, social and environmental) over the medium to long timescales, considering all costs and benefits, including externalities."

Conceptual Arguments for this Definition An important aspect of the proposed definition is that it is set explicitly at the level of t he water authority, rather than at the level of individual initiatives or schemes. This is important because, wh ile there is an understandable tendency within businesses to celebrate successes and report on projects that

place activities in a good light, in practice whether an individual decision, technology, scheme or even business unit is 'sustainable' does not give an indication of the overall sustainability credentials of a company; sustai nability is about the sum of t he parts, not just the parts themselves. A focus on the supply chain is also important to ensure the water authority is accountable for its actions, considering all relevant and significant upstream effect s. The reference to medium to long timescales in the definition allows for an adaptive management approach to be taken, where the success or otherwise of various initiatives can be measured and action taken according to the outcomes. Any attempt to assess sustainability on a short time scale is, in any case, confounded by issues w ith variability and the long term nature of the c hallenge. The focus on 'added value' in the definition, embracing externalities, is a key concept, because it aligns with the proposed transition t o full cost recovery for urban water use (Marlow & Burn, 2008; Hatton MacDonald et al. 2005; COAG, 1995). Achieving net added value also requires a focus on the balance between cost and benefits, rather than just consideration of benefits, w hich alig ns with economic principles. The req uirement to achieve net added value across each of the triple bottom line outcomes can be considered a statement to the effect that the business should make a 'net profit' not just financially, but also environmentally and socially. Leaving aside for a moment the

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practicalities of making this assessment, if it could be shown that such an overall net profit had been achieved, the water authority would have, by definition, added value to current and future generations' welfare at the scale of its influence, which would indicate that its operations were aligned with the philosophy of sustainable development. At the same time, the concept allows for more or less 'profit' to be made over time, as well as 'net loss', in line with the dynamic requirements for a definition referred to above. In c onceptual terms, this 'net added value' criterion can be construed as an extension to the triple bottom line (TBL) reporting approach discussed by Kenway et al. (2006); the extension being that, rather than requiring relative reporting of TBL metrics, what is needed is a direct assessment of whether 'net value' is being delivered by the water authority. This implies a capacity for social and environmental accounting equivalent to that of fin ancial accounting procedures; i.e. a capacity to reliab ly assess net TBL 'profits' and ' losses'. The question is; co uld suc h accounti ng be achieved in practice?

Whi le answering this question wi ll take further consideration, it is recognised that similar concepts have attracted criticism in the past. For example, in their critique of the triple bottom line reporting, Norman & MacDonald (2003) noted that reducing environmental and social outcomes to the equivalent of the trad itional 'bottom line' implies that aggregate measurements of social and environmental impact can be made. In practice, however, while it is possible to trade off financial income and costs across a business, 'good' and 'bad' social and environmental impacts do not cancel each other out in the same way; for example, positive impacts on a water course do not offset any significant harm done to another. Similarly, no degree of environmental improvement can offset any social blight or visa versa. With these issues in mind, 'TBL accounting' will need to avoid assessing tradeoffs between incompatible measures (e.g. social impacts versus environmental ones), which implies being able to account for all relevant environmental and social effects on a like-for-like basis using multiple metrics.

Protecting Dur Waterways with

While this discussion may seem rather abstract, the concept of accounting for 'added value' in the environmental or social space is in many ways analogous to the approach being adopted to account for greenhouse gas emissions, Carbon accounting procedures are already used to demonstrate a reduction in emissions. Two extensions are needed however. Firstly, alignment with the definition given above implies that instead of reducing carbon emissions or even becoming carbon neutral, there is a requirement to create net positive val ue; i.e. achieve 'carbon negative' business operations. Secondly, the approach needs to cover other outcome measures of relevance to the water sector, including nutrient discharge/recovery, biodiversity, river health and measures of social and com munity welfare. In practical terms, while it must be recognised that positive effects do not offset significant negative impacts, relative benefits can be traded off against one another, as can acceptable costs and impacts. This implies any tradeoffs should be made in the 'no significant harm' or 'relative benefit' space wherever possible. As such, impact assessments

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regulation would still be required to consider the significance of local and wider impacts, assessed in relation to the carryi ng capacity and resi lience of the natural environment and community, and to identify and quantify impacts that needed to be 'designed out' or offset somewhere else. Given issues of double counting and verification, any use of offsets would preferably involve direct action within the business itself, although offsetting through means akin to current carbon offsetting practices would still be considered a sustainable option if it were more economic, as long as it was verifiable.

Conclusion The changing circumstances of today's world mean that there are many reasons for progressive businesses to become part of the solution t o global and local problems, rather than clinging to failing 'business-as-usual ' approaches, not least those of enlightened self interest. Sustainability offers a philosophy to allow companies to achieve this transition. The philosophy of sustainability is already firmly embedded in the collective

consciousness of the Australian urban water sector, which is uniquely placed to lead the sustainability agenda for the nation, because of its long history of long-term planning and strong governance, and because it supplies a renewable resource to its customers. Furthermore, while it must be recogn ised that the impact that can be achieved by the sector is bounded in both space and time, we believe there is an ethical imperative to be part of the solution to the rapidly emerging problems of climate change, economic instability and declining biodiversity. To help the sector meet the sustainability challenge, there is a need for clear dialog ue and clear use of t erminology. Unfortunately, the operational interpretation of sustainability remains inherently vague, because sustainability concepts can relate to such a broad range of perspectives and scales; from the philosophical down to the operational, and from the global down to the local. To facilitate c learer communication, we need to be mindful of these differences and c lear about w hich level of sustainabi lity our focus is on at any one time.

An operational definition of sustainability has been proposed herein, expressed in terms that align with economic and business language. Self evidently, whether or not this definition meets the needs of the sector req uires much more debate. What is clear to the authors, however, is that there remains a real need for this debate if we are to move to a position where there is broad agreement on the operational meaning of sustainability. We believe such agreement is required if the sector is to develop a coherent message and exert positive influence that will help society shift towards a more sustainable future.

Acknowledgments The first author would like to express his deep appreciation to all organisations and individuals who participated in the qualitative research referred to in this paper and the fi nancial support of this research provided by the National Flagship 'Water for a Healthy Country'. The review of this paper by Leonie Pearson and Magnus Mog lia is also gratefully acknowledged.

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delivering clean water Brisbane Toowoomba Cairns Sydney Perth 122 FEBRUARY 2009 water

technical features

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, refereed paper

The Authors

Dr David Marlow (david.marlow@ csiro.au) is P roject Leader: Asset Management CSIRO Lan d & Water, H ighett ,Vict o ria.

Dr Robert Humphries {bob. hu mphries@

Gohier, L. (2005) Canada's lnfraguide: Bringing the Best of Research and Practice together for Sustainable Asset Management, Water Asset Management International, 1.3, Sep. , 14-15. Hatton Macdonald, D., Lamontagne, B & Connor, J (2005) The Economics of Water: Taking Full Account of First Use, Reuse and The Return to the Environment, Irrigation and Drainage 54: S93-S102 Kenway, S. , Howe, C. & Maheepala, S. (2006) Triple Bottom Line Reporting of Sustainable Water Utility Performance, AwwaRF Report 91179, AwwaRF, CO, USA. Marlow, D. & Burn , S. (2008) The Inclusion of Externalities in Asset Management Decision Making, Water Asset Management International, (accepted Nov 2008)

Myers, M. D. & Newman, M. (2006) The Qualitative Interview in IS Research: Examining the Craft, Information and Organization, 17, pp. 2-26 Norman, W. & MacDonald., C. (2003) Getting to the Bottom of "Triple Bottom Line" , Business Ethics Quarterly, 14(2): 243- 262. Porritt, J. (2005). Capitalism: as if the World Matters. Earthscan Publications Ltd, London Soderberg, H. & Karrman, (2003) MIKA; Methodologies for Integration of Knowledge Areas. The Case of Sustainable Urban Water Management, Henriette Soderberg & Erik Karrman (Ed itors), downloaded from http:// www.arch.chalmers.se/tema/ byggd-miljo/ personal/jh/ m ika_report.pdf (accessed November 2008)

Marlow, D. (2008a) Sustainability-Based Asset Management in the Water Sector, Water, the Australian Water Association Journal, Sept ember 2008, pp. 50-54

WCED (1987) World Commission on Environment and Development , Our Common Future (The Brundtland Report), Oxford: Oxford University Press.

Allbee, S. (2005) America's pathway to sustain able water and wastewater systems, Water Asset Management International, 1 :1, 9-14.

Marlow, D. (2008b) Sustainability-Based Asset Management in the Water Sector, Third World Congress on Engineering Asset Management and Intelligent Maintenance System Conference 2008, Beijing , October, 2008

Wang, J. & Roulston, K.J. (2007) An Alternative Approach to Conceptualizing Interviews in HRD Research, Human Resource Development Quarterly, 18: 2

COAG Expert Group (1995) Asset Valuation Methods and Cost Recovery Definitions for the Australian Water Industry, Canberra, Australia

MEA 2005. (Millennium Ecosystem Assessment) Ecosystems and Human We/I-being: Biodiversity Synthesis. World Resources Institute, Washington, DC.

watercorporation.com .au) is Manager Sustain ab ility, Wat er Corporation , L eederville WA 6902 Australia.

References

WERF (2007) An Economic Framework for Evaluating the Benefits and Costs of Biosolids Management Options, Water Environment Research Foundation, www.werf.org

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regulation

THE PRIVATE SECTOR COULD HELP SOLVE WATER SCARCITY WHY NOT? N Palmer, G Dooley Introduction Imagine the phone rings at an Adelaide consumer's home one night and a telemarketer is on the line. "Hello. "Hi. This is Blue Water. Would you like to say goodbye to water restrictions and do your part to help save the River Murray by buying all your water from a sustainable source? "Maybe. Tell me more. "How it works is that we make our own drinking wat er by harvesting rainwater that used to run out to sea. We let nature purify the stormwater in wetlands, then we store it in underground dams, then when we need it, pump it up and purify it to independently audited Australian Drinking Water standards and then put it into Adelaide's water pipes. "Sounds pretty good. "It is good. By buying your water from Blue, you do your part to beautify Adelaide and create more wetlands around Adelaide which means more frogs and birds. We're actually really proud of our wetlands and invite our customers to visit them and see what they've helped create. Also by switching to Blue you help the River Murray get healthy again. In 2007, 91 % of your water came from the Murray. Another neat sustainable thing we do is that all our electricity comes from renewable resources like wind and solar so you do your bit to cut greenhouse gases. The bottom line is you help Adelaide become a sustainable city. "So how does that water get to my home? "Well, if you think of Adelaide's water pipes as a river, we add water to that

This article is condensed from a presentation at the AWA Conference Desalting 2008 held in Perth in September.

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river and you can get that same amount of water out downstream. "OK that makes sense. What's the catch ? Do I still have to have water restrictions ? " No more water restrictions is one of the great advantages with Blue Water. Of course we encourage all our customers to follow the Government's water conservation principles like not watering your garden in the middle of the day and using five star appliances and so on, but if you become a Blue Water Customer, you can use water whenever you want and say goodbye to compulsory water restrictions. "Mmmm my lawn and garden will love that, not to mention being able to let the kids play under the hose. So how much will it cost? "Well you will still have to pay whatever you pay the Government to be connected to the pipes. On top of that, our drinking water prices start at 0.2 cents a litre compared with the 0.1 cents a litre that you pay at the moment. For an average Adelaide home, that will be less than $20 extra a month to have no restrictions and to know that you are doing your bit to help look after the Murray River. "So what do I have to switch to Blue? "It's really easy. I just take a few details from you and leave the rest up to us. The only difference is that you 'll stop receiving SA Water bills and just get one bill from us. Oh, and the other thing you will notice is a few more birds and wetlands around the city and no more restrictions".

Competition and Regulation This fictitious account forms part of a speech which has been presented a number of times in 2008 by Joe Flynn, CEO of South Australia's Water Industry Alliance. The story describes how competition, pricing, independent regulation and private sector involvement might work to solve water scarcity and sustainability.

Unlike telecommunications, energy, fuel and food, Australia's current water regulation prevents the operation of a free market for reticulated water. Yet the same is not true of all the water sector. For example, there is a strong demand for bottled water. A 600 ml bottle of Mt Franklin water from the supermarket sells for around $2.40 - that works out to $4,000 per kl! In July 2007, an Adelaide newspaper ran a survey of typical household expenditure (Sunday Mail, 2007). After paying $21,600 on mortgage repayments, $11,700 on groceries and $4,720 on utilities, out of a total expenditure of $48,000, the Hurst family spent $560 on water and sewerage. Assuming $300 of this was for water (the rest for sewerage), this amounts to 0.6% of the household budget. For something so vital to life, the price of water is too cheap. SA Water's current price of water (middle tier, for 120 - 520 kl per year) is $1.36/ kl. This has been increased to take into account the cost of desalinated water from the proposed 150 MUd Pt Stanvac plant currently out for tender. Sydney Water's price in 2009 will be $1.83/kl to account for the 250 MUd Kurnel l desalination plant currently under construction. A survey of world water prices published in 2004 indicated the retail price of reticulated water in Australia was about half that of typical European countries (Farmhand Foundation, 2004). Australia is the driest continent, our rainfall patterns require large storages and some of our water is pumped long distances. The price of water is too cheap. For the last ten years, severe water restrictions have been imposed on southeast Queensland consumers. Since 2002, WA, NSW, Victoria and SA have followed with water restrictions. Reticulated water,

Old regulatory regimes are hindering progress.

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regulation unlike other household commodities, is centrally planned. Governments dictate both the price you pay and the quantity you can use. But in respect of other utilities, we live in a market economy. It is the writers' view that had water been properly considered as a commodity in Australia, (regulated for service st andards and quality) the market wou ld have responded with infrastructure to better manage water resources. Extend ing the concept of the fictitious story, this could include wastewater recycli ng and desalination. Consumers have demonstrated wi llingness to pay very high unit prices for bottled water. It is indisputable that a large unsatisfied demand exists for reticulated water at a significantly higher price. The energy and creativity of the private sector might well provide additional independent water sources, given reasonable commercial returns as a consequence of some market freedom.

Desalination More than 13,000 desalination plants have been built worldwide since the introduction of large scale operations in the 1950s. The unit cost of seawat er desalination by reverse osmosis has been steadily coming down with improved membrane performance and energy efficiency. Large desalination plants financed, built and operated by the private sector for competitively tendered project s can deliver water "through the fence" at between $US0 .60 to $0.80 per kl (Voutchkov, 2007). At these costs, desalted seawater is competitive with many "harder to reach" conventional sources. But the big advantage is that it is an inexhaustible supply. A ll of Australia's capital cities (except Canberra) and in fact most of the population lives on the coast. Seawater desalination t herefore joins stormwater and indirect potable reuse of wastewater as a cost competitive water source. Australia has been slow to embrace seawater desalination. Western Australia's Water Corporation led the way with construction of the 145 MUd Perth Seawater Desalination Plant at Kwinana, commissioned in November 2006. Perhaps most affected by the impact of climate change, nevertheless the Water Corporation encountered significant criticism on environmental and energy grounds. Having weathered the storm, the plant has operated virtually continuously. The benefits have silenced the opposition and a second plant wi ll be

built at Binningup Since the success of the WA experience, a further 7 major seawater desalination plants are being built or developed at the Gold Coast, Sydney, Melbourne, Adelaide, Karratha and Whyal la. The total installed capacity will be more than 1,600 MUd. Spain (pop 44 million) has faced similar challenges, but embraced desalination much earlier. Spain is a federation of states (like Australia), but water resource management is the responsibility of the national Government (unlike Australia). The program has provided Spain with the opportunity to develop an exportfocussed desalination industry. The Perth Southern Seawater Desalination Plant was tendered by two consortia led by Spanish companies. A consortium led by Tecnicas Reunidas-Valorizas has been announced as the preferred tenderer. All other Australian plants have been won or are being t endered by French, Spanish or Israeli led consortia. Singapore has one seawater desalination plant (the 136 MUd Singspring plant, owned and operated by Singapore company Hyfl ux). The Singapore Government used this opportunity to development local industry and Hyflux now has an internat ional focus. It is constructing the largest reverse osmosis plant in the world at Maagta, Algeria (500 MUd) as well as owning and operating a stable of water plants across Asia.

The outcome, like the food industry, would mean better allocation of scarce water resources and much less waste. A national strategic plan including encouragement of the private sector could lead to an extremely successful export- focused Australian water industry. In addition, there would be no need for unpopular and in some cases draconian water restrictions. Food is also subject to cl imate change and drought. When was the last time we had food restrictions? We in the water industry have an opportunity to influence those with whom we have contact, our schools and commun ities and our politicians to change the way Australians think of water. To borrow from AWA's mission statement, this will lead t o better management of our water resources.

References Farmhand Foundation (2004) Talking Water Sunday Mail, (2007) Article on the Hurst Family 15 July p 5 Voutchkov, N (2007) Estimating Desalination Costs AWA Desalination DBOOT Master Class Adelaide 13-14 Sep 2007

The Authors

A Missed Opportunity An opportunity to develop an Australian desalination industry has been missed. This is partly due to the constitutional responsi bility for water being divided among the states (and therefore no national strat egy) and partly lack of confidence in Australian enterprise. It might be said Australians are much better at running competitions than they are at building industry capacity. As more desalination plants wi ll be needed, we have another chance to build Australian desalination capacity. Large sums of taxpayers' money are being spent on the water industry. It would be nice to see some government support for Australian desalinat ion companies.

Neil Palmer (email neil.palmer@ osmoflo.com.au) recently joined OSMOFLO Pty Ltd, the largest Australian desalination company, as General Manager Technical Services. He has worked for over 30 years in the water industry for Government and in the private sector. He is a Director of the International Desalination Association.

We live in a market economy. It is the writers' view that if reticulated water were to be considered as a commodity in Australia, the market would respond with infrastructure to better manage water resources. This would include groundwater, stormwater, wastewater recycling and seawater desalination.

Graham Dooley is currently CEO of the Surat Basin Rail Company. Graham has had a distinguished career in the Australian water industry at executive level in Sydney Water and as Managing Director of United Utilities Australia. He was recently elected t o the AWA Board.

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O&M ALLIANCE FOR THE PERTH SEAWATER DESALINATION PLANT G Mercer, S Sibma Abstract This paper outlines the principles involved in the decision by the Water Corporation to use an Alliance Contract for operation and maintenance of Perth's first Seawater Desalination Plant at Kwi nana. It also summarises the performance of the plant in its first two years.

Introduction

This paper was originally presented at the AWA Desalting Conference in Perth, October, 2008. The authors enlivened the presentation by comparing it to "An Arranged Marriage", following the sequence: • Dating • Choosing a Fiancee • The Engagement • The Wedding • The Marriage

The 144MUd Perth desalination plant was the first large-scale SWRO plant to be established in Australia. Since the owner, The Water Corporation of Western Australia, had, in 2005, no experience of operating a large SWRO plant, it decided to utilise the experience of an internationally established company to construct, operate and maintain the plant, working in partnership with the Water Corporation, particularly in areas of regulatory compliance, energy and chem ical supply and general operational expertise. A term of 25 years was decided for the O&M phase, and obviously for such a long-term alliance the choice of the company was of the utmost importance. (The analogy to an arranged marriage became evident.) In choosi ng the operational partner, the Water Corporation considered compatibility, expertise and professionalism, honesty, performance based results, safety driven and demonstration of behaviour conducive to an Alliance.

• The Lessons Learnt • The Secrets of a Good Marriage

Jim Gill (CEO of the Water Corporation) and Jean-Louis Chaussade (CEO of Suez Environment) officially open the plant in April 2007.

Both companies developed their final designs and costing. After an exhaustive evaluation process the project was awarded to the Joint Venture of SuezDegremont and Multiplex En gineering Pty Ltd . Construction co mmenced in May 2005, first water was delivered in November 2006 and handover for commercial operat ion commenced in May 2007.

• Safety First Culture • Best for Project philosophy • Roles, responsibilities and accountability clearly defined • Reward commensu rate with performance • Al liance behaviour to be encouraged at all levels.

The Principles

Responsibilities

In order for such an alliance to work for 25 years it was first necessary to establish the broad principles for sharing responsibility. They were:

The day-to-day responsibilities were shared accordi ng to the partner best able to perform them , as below:

• Open, ethical, dynamic and resultsoriented culture based on trust among all associated w ith the service

• Water Corporation holds the operating licences and the power supply contract

The compan ies who were interested had their own priorities, ie a long term comm itment, shared risk for this first Australian SWRO plant and professionalism. In the event the two French companies, Degremont and Veolia, with their Joint Venture partners, were short listed from a number of applicants and they were both engaged in an Alliance Development Phase (ADA) for a six month period with the Corporation.

Successful operation right from the start. 126 FEBRUARY 2009

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The Team of Water Corporation, Degremont and Multiplex with the Premier of WA - November 2006.

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project management • Degremont manages and operates the plant under the 25 year Alliance agreement

Asset Maintenance

• Degremont operates with in compl iance of the licences • Chemical procurement is through the Corporation to take advantage of the Corporation's bulk buying power

Power

Waste 4%

• Reporting is frequent with formal monthly reporting and meetings as well as daily commun ication • Shared faci lities and resou rces: - Office accommodation for Degremont operations team and Water Corporation support team - Environmental management of the saline discharge into Cockburn Sound managed by the Water Corporation with Degremont support - Trainees are seconded to the project from both alliance partners.

Mobilisation Once the contract had been signed, and the Multiplex and Degremont Joint Venture (MDJV) in Alliance with the Water Corporation progressed with

Other Fixed Costs 16%

40%

c Asset Maintenance •

Chemicals 12%

Staffing CJ Other Fixed Costs CJ Chemicals • Waste

c Power •

Sa\ings

Figure 1. Typical Budget Breakdown. construction, the Operations and Maintenance team was mobilised in parallel. Challenges were encountered right from the start. The mining boom in Western Australia had resulted in an overheated market for all levels of staff, particularly since the Kwi nana industrial area was heavily involved in the boom. Once recruited the operators had t o be trained on a new process, and training on plant specifics had to remain flexible as construction, commissioning and operation continued in parallel.

Procurement of specialist services and consumables requ ired for operation suffered the same difficulties, but chemical procurement was made easier by using the Corporations existing contracts with their large purchasing power.

Commissioning Commissioning was performed in parallel w ith production, and the integration of operation team with commissioning

project management

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overruns are shared by the alliance partners. A further risk and reward component applies to under- or over-production against the Target, i.e. agreed overproduction is rewarded , but under production results in risk deductions.

Outcomes

Figure 2. Monthly and Cumulative water production.

During the first eighteen months of operation the usual , and some unusual, challenges have been experienced, which have impacted on production. The most significant have been:

required constant coaching and support to ensure successful outcomes. However the production test run was completed successfully despite defects correction constraints. An important Lesson learned was that the QA process of documentation delivery was critical to successful commissioning and subsequent operation and maintenance.

O&M Deliverables The O&M team is responsible for the operation and maintenance of the facility as wel l as the delivery of the following: • Management system, including: - Safety and Environment - Emergency Response

O&M Budget The O&M Budget is established for each year following alliance principles: • Water Corporation takes the risk on unit rates • Degremont takes the risk on unit quantities • Actual costs are paid for: - Fixed Operating Costs - Staff, Maintenance, Other fixed costs - Variable Operating Costs Chemicals, Waste, Consumables and Power - Asset Replacement Costs. A typical budget breakdown is shown in Figure 1.

- Operational Quality management - Finance & Administration • Operating manuals - Implemented during comm issioning and updated through transition to operation • Asset management - CAMMS • QMS - achieving certification in quality, safety and environmental systems.

Risk and Reward Regime Degremont are paid on Actual Direct Costs incurred in operating the plant to meet its annual production target of 45 GL in 345 days. The alliance partners share in Risk and Reward - calculated on the variance between the Budget and Actual Costs in the three cost areas. Any cost savings or

• Inspection and servicing of High Voltage switchgear and defects correction shutdown • Cable failures • Pump bearing failures (resolved under warranty) • The copper nickel cooling coils on the High Pressure pump drives were replaced with titani um • Environmental licence: Two fortnight shutdowns were implemented in accordance with the operating license, as the levels of Dissolved Oxygen in Cockburn Sound had fallen due to the lack of wind mixing during the calm Autumn periods (April, May, June) • Gas Crisis shutdown: The explosion at the major natural gas production site in the North West necessitated stringent measures to reduce energy consumption in the state. It also impacted on supplies of lime and CO2 • The resultant production graph is shown in Figure 2.

Water Quality Drinking water quality has been withi n specification, unless agreement had been reached within the alliance to deviate during testing, eg: Alkalinity specification was relaxed during testing of clarifier performance under different operating regimes Bromide levels were tested in permeate and drinking water until optimum level achieved. Figures 3a to 3e summarise performance quality against targets.

Power Consumption

Interior of the plant.

128 FEBRUARY 2009 water

Power consum ption has been consistently below the target. Figure 4 summarises the breakdown into its components.

technical features

project management • Ensure commissioning phases are "locked in" as key deliverables

Lessons for all Operators and Owners • Early engagement with the reg ulator

• Develop O&M template (BOM)

• Early consultation with stakeholders

• Perform O&M tender reality check

• Set a reasonable D&C delivery period

• Consider the gain sharing arrangements carefu lly.

• Early appointment of key O&M personnel

Secrets to a Good Alliance

• Ensure O&M integration into comm issioning

• Our team = One Team • Respect and Trust

Export Water TDS

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Awards The Perth Seawater Desalination Plant was voted:

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• Global Water Intelligence - Winner, Desalination Plant of the Year 2007

Export W ater Alkalinity 100 ~ - - - - -- -- - - - - - - - - - - - - ~

• Australian Constructors Achievement Award - 2008 Winner Australian Constructors Association and Engineers Australia.

The Authors

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Greig Mercer is the O&M All iance Director for the proAlliance.

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He is a civil engineer with extensive international operational experience in the water industry. He has worked for SuezEnvironment/Degremont since 1991. Email Greig.mercer@degremont.com.au

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Sjoerd Sibma is the Desalination Manager in the Water Technologies Division for the Water Corporation and managers the alliance contract. He is a civil engineer with extensive operational and asset delivery experience. Email Sjoerd.si bma@waterco rporation.com .au.

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Figure 4. Power consumption breakdown.

water FEBRUARY 2009 129

project management

refereed paper

PROJECT DELIVERY: HANDOVER AS THE FOCAL POINT Z Slavnic Abstract Delivery of Construct-Only and Design & Construct projects, including projects in the water industry, usually encompasses several distinctive phases, i.e. design, construction, c ommissioning and handover. With this fragmented approach, the bigger picture to all parties involved may not be that clear. This paper provides an outline on projects delivery but w ith the focal point on facilities handover.

DESIGN

CONSTRUCTION

.0. COMMISSIONING

.0.

Traditional Project Delivery Concept Every project starts with planning where clients/end-users define their requirements, in particular in technical terms, but also budget, delivery method, timeframe, etc. In Construct-Only projects, design is either carried out by the client, or the client engages a consulting organisation (designer) to produce detailed design for execution by a contractor, w ho is engaged at a later stage. In D&C projects, the main contractor is responsible for both design and construction, where design may be done by a designer on a subcontract basis or in a joint venture (JV) with the designer. Whichever of the two

130 FEBRUARY 2009 water

Integrated Project Delivery Concept The need for an integrated concept when it comes to Construct-Only or D&C projects stems from the followi ng recognitions:

Introduction Traditionally, delivery of Construct-Only and Design & Construct (D&C) projects encompasses several distinctive phases, typically design, construction, commissioning and handover. The focus of the project team shifts as the project delivery progresses through each phase. With this fragmented approach, the bigger picture may not be that clear, and this applies equally to all parties involved in projects delivery, i.e. designers, constructors , clients/ end-users, etc. It is believed that an integrated approach, where each phase complements another, and where all parties work co llaboratively, will provide better outcomes, i.e. water/wastewater assets which can be operated and maintained by end-users in the most cost-effective way . Therefore, this paper provides an outline on projects delivery, but with the focal point on handover, and beyond.

is in most inst ances applicable to mainly proving chemical or biological processes. On the other side, it is very uncommon for a designer to get involved in construction or a commissioning specialist to get involved in design. Even when that is not the case, as far as the author has experienced it, this is rather an exception than a norm.

Figure 1. Traditional Project Delivery.

â&#x20AC;˘ Each of the delivery phases complements one another.

approaches a client selects, there are several delivery phases, i.e. design, construction and commissioning prior to handing over facil ities to the end-users for operation and maintenance (O&M), as shown in Figure 1.

â&#x20AC;˘ A facility cannot be handed over to a client if each phase, i.e. design, construction and comm issioning, is not fully completed.

A major shortcoming with this concept is that it is a fragmented approach. Namely, each delivery step is viewed as a distinctive phase; therefore each phase is, more or less, delivered by a 'separate' team, where collective input is far from that required. Typically, design documentation is developed by the designer with no input from the contractor (Construct-Only projects) or this input is limited (D&C projects). This documentation is then used by the construction team to procure the specified equipment and carry out the necessary civil, mechanical and electrical c onstruction works. Commissioning personnel then get involved to conduct required checks and tests to prove that all plant and equipment, unit processes, and the facility as a whole, perform in accordance with the specified requirements. It is recogn ised that the boundaries between delivery phases are not fully rigid , as for example a consulti ng engineer may participate in c ommissioning activities. However, this

Towaras smooth execution and handover.

The integrated project delivery concept is shown in Figure 2. Although there are still three main phases, i.e. design, construction and commissioning, the focal point is clearly on the handover, that is, the acceptanc e of a facility by cl ient. Further, each phase is complementary to another. Namely, the designer participates in construction and commissioni ng activities, whi le construction and commissioning personnel get involved in design. The latter is particularly important, as experienced site construction engineers can provide valuable comments on constructability aspects, hence ensuring rational and economic design, whi le skilled commissioning specialists know first-hand what would work and what would not or what would work better when it comes to mechanical equipment, instrumentation, control sequencing, etc. Obviously, design is a pivotal phase, as with a good design there should be fewer problems during construction and commissioning. In addition, design is a phase where opportunities to add value are the greatest. This mandates that everyone in the project delivery team is given a chance to participate, directly or indirectly, in design, as changes on paper are not costly. From the author's

technical features

project management

refereed paper

this delivery method all parties to an alliance (typically the client, designer, constructor and operator) work collaboratively as a united team from the project onset through to handover. Th is approach ensures that design incorporates constructability, commissioning and O&M req uirements. The same team is also responsible for construction and commissioning. Consideri ng the fact that the operator is part of the alliance, and actively participates in commissioning, the handover becomes an integral part of the project execution.

experience the following should be observed for D&C projects (but difficult to implement in ConstructOnly projects): • No design package should go for tender without being reviewed by engineers with experience in const ruction and commissioni ng. • No subcontract offer for an area of works should be accepted without being reviewed by both designer and contractor (construction and commissioning site personnel). • No design should be finalised and no equipment procured and/or works constructed without giving a chance to cl ient/end-user to comment.

Figure 2. Integrated Project Delivery Concept.

These basic principles are not only applicable to D&C projects but also for partnering arrangements such as alliances, which appear to be the only delivery method where these principles are being embodied. There are basically two available avenues for the implementation of the above principles in D&C projects. One invo lves forwarding design packages to site for circulation and review by all site engineers. Their key comments are then captured and, when agreed, design is amended accordingly. The other one is conducting formal design workshops where designers present their design to site engineers and design details are collectively discussed and agreed. This, from the author's experience, is the preferred way as the knowledge of an integrat ed team is always greater than t he sum of knowledge of its members. It is also highly recommended that the client/end-user's staff, in particular plant operators, are invited to attend these workshops, as they can provide invaluable comments when it comes to operation and maintenance. Further, despite being focused on facility acceptance, the integrated approach inherently looks beyond the handover, i.e. it takes into account O&M aspects in the long run. Namely, the time involved in design by construction and com missioning personnel (and plant operat ors) wi ll be well spent, and should result in a faci lity that is safer and easier to operate and maintain. The integrated approach would be beneficial to everyone involved, as catalogued below: • Design engineers will get a chance for a 'hands-on' experience and not just seeing what they have designed. This

wil l, no doubt, make them better designers. • Site engineers should benefit, as he/she will learn new skills and become interdisciplinary professionals (a rare breed these days). • Construction, equipment installation and comm issioning works wou ld be less cumbersome, hence saving projects time and money, as site engineers wil l be having their say during detailed design. • Clients (end-users) should benefit as this approach would provide the best value for money through improved design, hence red uced O&M costs throughout facilities economic life. • Respective D&C organisations wil l benefit through improved relationship with clients and, with proper knowledge management, would be better equipped for future projects. Water authorities continually endeavour to maximise the value for money in the long term, hence are looking for delivery methods other than traditional. An improvement to the traditional methods is Early Contract Involvement (ECI), a variance of D&C contracts. Here, usually one or two selected contractors work individually with a client and his consultant to develop a design to say 85% completion. The aim is to arrive to a design which incorporates all the client's needs as wel l as using construction methodology and equipment that suit the contractors, designers and specialised sub-contract ors and equipment suppliers. This delivery method smoothes execution of construction and commissioning works. Projects/programs delivered by alliances are gaining momentum. With

Conclusion A project delivery concept/method is only as good as outcomes it delivers. Projects in the water industry are multidisciplinary and require an integrated delivery method where design, construction and commissioning engineers work jointly with the client and plant operators. If this cardinal principle is abdicated, the full potential of a project team wi ll not be utilised and opportunities to add value at the right time wil l be missed. Considering that water facilities are crucial from both economic and social perspectives, we should all make an effort to work collaboratively in order to arrive at outcomes that are not fragment ed and partial, but produce rational and the most economical engineering solutions. This approach will ensure not only smooth execution and handover, but provide the best value for money in the long run.

The Author Zoran Slavnic, PhD, MBT, MEngSc, BEng(Mech), has over 25 years experience in the water industry encompassing design, construction, commissioning and asset management. He is Commissioning Manager with Laing O'Rourke Australia. Email: zslavnic@laingorourke.com.au

Previous papers by the author on this topic have been featured in Water: • Project Delivery: An O & M Perspective. December 2005 • Project Delivery and Commissioning: An Integrated Approach. November 2006 • Raising the Bar: Operators' Involvement in Design. November 2007

water FEBRUARY 2009 131

desalination

~ refereed paper

DESALINATION BY CAPACITIVE DEIONISATION M Hoang, B Bolto, TTran Abstract Capacitive deionisation (CDI) is a relatively new item in the desalination arsenal that has potential as a low energy process for brackish feed waters. Carbon electrodes of high surface area adsorb salt under an applied potential, and desorb it as a concentrated brine stream when the potential is released. A prototype module has shown that to lower the salinity from 2000 mg/L to 500 mg/L, a 70% recovery of water is achievable with an energy need less than a third that of reverse osmosis and electrodialysis. However, the capital cost is likely to be higher.

Introduction CDI has progressed along a long road. It started with some very early Russian studies on the adsorption of inorganic ions to carbon (Kuchinsky et al., 1940) taken up by later workers, including some at CSIRO (McNei l! and Weiss, 1960) and others (Arnold and Murphy, 1961 ). In these works carbon electrodes that responded to cations and anions were identified, and the electrical properties of conducting organic polymers studied (Soito and Weiss, 1962, 1965). However, the salt uptake capacities were miniscule. Some preference for divalent ion removal had been suggested (Johnson and Newman, 1971). Figure 1 illustrates the principle of operation during the active desalination half cycle. The feed water flows between pairs of high surface area carbon electrodes that are held at a potential difference of 0.8- 1.4 V, which is lower than the voltage needed to electrolyse water (Lee et al. , 2006). The system acts as a flow-through capacitor. Ions and other charged particles such as microorganisms are attracted to and adsorbed on the electrode of opposite charge. The negative electrode attracts positively charged species such as calcium, magnesium and sodium ions, while the positively charged electrode attracts negative species such as chloride and nitrate ions, and silica.

132 FEBRUARY 2009 water

Negative electrode

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Salty e • water___.,. •

__,,..clean 7 water

• =Cation

• =Anion

Positive electrode

Figure 1. Principle of operation, desalination stage (from van Limpt, 2008). Initial tests showed a 95% removal of salt from a 70 mg/L solution (Farmer et al., 1996). Another report shows 95% removal from a 500 mg/L solution with an energy requi rement of 0.65 KWh/kl (Andelman, 1998). Eventually the electrodes become saturated with ions and must be regenerated. The applied potential is reversed, and the ions released are flushed from the system, producing a concentrated brine stream. In practice, more than 80% of the feed water emerges as fresh, deionised potable water, and the remainder is discharged as a concentrated brine solution containing virtually all of the salts in the feed. Figure 2 shows the overall schematic of a CDI system. The primary advantage is the low operating cost, which is claimed to be about one third that of the main competitor, reverse osmosis (RO). The likely advantages that CDI could offer over RO include far less pretreatment of the feed water, a much lower tendency to foul, and because operation of the system involves reversing the charge on the electrodes, the stored energy is released , giving up to 80% energy recovery (Christen, 2006). The charge reversal also drives off fou lants adsorbed on the electrode

Low energy requirement for brackish waters.

surface (Andelman, 1998; Zou et al., 2008a). Electrodes from carbon aerogels have solved some of the problems of CDI because they can be prepared as monolithic sheets, eliminating the need for the porous separator used with electrodes based on carbon powders. Rather than flowing through a packed bed, the solution flows through channels between adjacent electrodes, eliminating pressure drops. Carbon aerogel electrodes have a very high surface area of up to 3000 m2/g, and a very low electrical resistivity. The main drawbacks are low salt capac ity, so that the approach is limited to low salinity waters, and their high capital cost. Studies have been made of the ion removal capacity and selectivity of carbon aerogel electrodes (Gabelich et al., 2002). Although the electrodes have been visualised as electrical double layer capacitors, the studies showed that ion adsorption fol lowed a Langmuir isotherm, indicating monolayer adsorption. The capacity of the electrodes was -0.1 -0.2 meq/g of aerogel, with an ion selectivity inversely proportional to the ionic hydrated radius. Monovalent ions with smaller hydrated radii such as sodium were preferentially removed before multivalent ions like calcium, contrary to earlier observations (Johnson and Newman, 1971). Because of the small average pore size of the carbon (4-9 nm),

technical features

desalination

~ refereed paper

Salty influent I

.11 ' /

' /

Deionized effluent

_ High surface - area material = Current collector

Figure 2. Overall operation of a COi system (from van Limpt, 2008). only 14-42 m2 /g of the surface area was available for ion adsorption. Organic aerogels have been synthesised from resorcinol formaldehyde and like polymers, some of which can then be pyrolysed in an inert atmosphere to give carbon aerogels (Pekala et al., 1998). They retain their high surface area of 400800 m2 / g and ultrafi ne pore size of < 100 nm. When used in a CDI unit treating 65 mg/L NaCl , there was a 99% removal of salt. Carbon aerogel electrodes have been cost-effectively made by pyrolysing resorcinol -formaldehyde aerogels at 800°C in a nitrogen atmosphere (Jung et al., 2007). The electrodes

had a surface area of 610 m2/ g and a high porosity of -80%. In a CDI system treating 50 mg/L NaCl there was an ion removal of 93% at 1.5 V and 98% at 1.7 V. Recent work on ordered mesoporous carbon electrodes has demonstrated that they have a higher adsorptive capacity than activated carbon , at 11.6 and 4.3 meq/g respectively (Zou et al., 2008b). This might not only be due to their suitable pore size (3.3 nm average), but to the ordered mesoporous structure that faci litates desorption of salt. The ordering and control of the number of micropores are two important parameters in optimising electrodes for CDI. Research on an industrial prototype module has shown that to lower the salinity of an artificial brackish water from 2000 mg/L to 500 mg/ L, a 70% recovery of water is achievable when a potential difference of 1.3 V is applied (Welgemoed and Schutte, 2005). The energy usage was compared with that needed for competing processes treating brackish water of 800-10,000 mg/L salinity, to give the data shown below. The val ues for COi depend on the energy recovered and the operating mode: Electrodialysis - 2.03 kWh/ L RO - 2.25 CDI - 0.13-0.59 For seawater desalination, however, ways would have to be fou nd to increase t he salt uptake capacity for COi treatment costs to be competitive. A further application is in the treatment of mixtures of seawater or RO brines and secondary sewage effluent, which has a lower salinity (Lee et al., 2008).

•I

I• I I

PPI Corporation Pty Ltd - Mining Industrial & Civil Sales Phone: (07) 3860 0388 (07) 3860 0392

Sales Fax:

Email: mic@ppi.com.au

Australia: Brisbane, Sydney, Melbourne, Hobart, Adelaide, Perth, Darwin & Townsviile.

water FEBRUARY 2009 13 3

desalination M odified Carbon Electrodes Incorporation of metal oxides Improvements in CDI have been made by modifying an activated carbon cloth with titania (Ryoo and Seo, 2003). The polar groups on the carbon were reacted with the alkoxides of titanium, si licon, aluminium and zirconium. All but titanium had a negligible effect. Titania was highly dispersed on the carbon surface, resulting in a decrease in the physical adsorption of NaCl from 0.02 to 0.005 meq/g when no charge was applied. However, the electric field adsorption of NaCl was significantly enhanced from 0.03 to 0.075 meq/g due to the increase in the number of adsorption sites under electric field conditions that arose from the participation of titanium atoms.

Surface modification The CDI behaviour of nanoporous activated carbon cloth has been improved by surface treatment with KOH or HNO3 (Oh et al., 2005). In experiments with 1400 mg/ L NaCl solution at applied voltages of 1.0 and 1.5 V, the desalination ratio after 160 s increased from 41 to 53% for untreated cloth on raising the potential, but increased from 44 to 58% for KOH-treated cloth and from 51 to 67% for HNO3 -treated material. The enhanced performance of the acid product was ascribed to the formation of carbonyl groups on the carbon surface which were transformed into hydroquinone groups during CDI, faci litating the process not only by ion adsorption via an electric double layer, but also via electron transport by Faradaic reaction, much as reported earlier for oxygen-treated activated carbon fabrics (Hsieh and Teng, 2002).

Carbon nanotubes A carbon nanotube (CNT)/graphite electrode has been made by directly growing nanotubes of 50 nm diameter on graphite foil (Chen et al. , 2002). The high specific capacitance obtained showed that the electrodes cou ld be excellent candidates for use as electrochemical double layer capacitors. Electrodes have been made from CNTs by hot pressing them with at least 20% of a phenolic resi n binder at 150°C for 15 min, followed by carbonisation at 850° for 2 h (Zhang et al., 2006). Carbonisation improved the electrochemical performance of the electrodes, giving products with higher specific capacitances and lower resistances. The salt removal efficiency was much higher at over 90%, versus 30% for the uncarbonised material,

134 FEBRUARY 2009 water

r e f e r ee d p a p er

Table 1. Desalination by CDI and membrane CDI. Salt Concn., mg/L

50 65 70 500 2000 3780t

Salt Removal, %

Energy Need, kWh/kl

93-98 99

Jung et al., 2007 Pekala et al., 1998

95 95 70 92

Reference

Farmer et al., 1996

0.65 0.13-0.59* 1.96

Andelman, 1998 Welgemoed & Schutte, 2005 Lee et al., 2006

• Depending on energy recovery & operating mode t Membrane CDI

although it is not clear what the salt level was in the feed water. The enhancement was considered to be related to the surface properties of the materials, with the creation of many new pores and acid sites which made the surface more hydrophilic and more accessible to ions. A combination multi-walled CNT and active carbon electrode has been proposed (Dai et al., 2006). If the CNT content was 10% the best desalting result was obtained, a 5000 mg/ L feed solution being reduced to 2900 mg/ L. The electrode had the highest surface area of the range of carbon electrodes made. Composite electrodes made from CNTs and nanofibres have been explored (Wang et al., 2006). They are claimed to have optimal network morphology and a favourable pore size distribution , plus a higher electrosorption capacity than carbon aerogels, although the surface area is smaller. The best result for salt removal appeared to be the production of 88 mg/ L product water from a 133 mg/L feed.

Incorporation of ion exchange membranes A membrane CDI system has been devised that incorporates cation- and anion-exchange membranes before the carbon electrodes (Lee et al., 2006). In a comparison of the modified cell with a conventional CDI unit, when a DC potential of 1 .2 V was applied for 10 min, followed by charge reversal for 5 min, salt removal was 19% higher for the membrane-modified CDI than for the conventional CDI. In treating a 3780 mg/L solution of salts, the membrane system gave a 92% removal with an electrical energy usage of 1.96 KWh/kl.

Summary and Conclusions The data to hand on salt removal and the energy requirement are summarised in Table 1. It would seem that there is a considerable energy consumption advantage in the treatment of low salinity

waters, as the com peting processes of RO and electrodialysis have brackish water needs of 2.25 and 2.03 kWh/kl respectively versus 0.13-0.59 kWh/kl for CDI (Welgemoed & Schutte, 2005). Higher feed salinities and higher salt removals are more expensive in energy terms, as with all other processes. It is difficult to see how the process could tackle seawater in a practical and economical way, as the adsorptive capacity of the system is so low. However, there are indications that t here is a concerted effort aimed at such high salinity waters (Straits Times, 2008). One possible solution is to mix seawat er with sewage effluent, to give a marked reduction in salinity to levels nearer those of brackish groundwaters, making the diluted seawater more amenable t o CDI. At the other end, the increase in ionic strength of the effluent can destabilise to some extent the dispersion of colloidal organic compounds, because of charge shielding by the higher level of ions causing some coagulation. Further attention would need to be paid t o eliminate possible foulants and com pounds of public health concern. The primary advantage claimed for CDI is the low operating cost, which is significantly less than that of its main competitors for brackish water desalination. Other advantages inc lude: • less pretreatment of the feed water • a much lower tendency to foul • up to 80% energy recovery • charge reversal also drives of any foulants adsorbed on the electrode surface.

Ac knowledgment Thanks are due to Bart van Limpt of Wetsus, Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands, for permission t o reproduce the two Figures we have used here.

technical features

desalination

~ refereed paper

on electric double-layer capacitance of activated carbon fabrics. Carbon 40, 667674.

The Authors

Johnson, A. M. and Newman, J. (1971). Desalting by means of porous carbon electrodes. J. Electrochem. Soc. 118, 510-517.

Dr Manh Hoang is Leader of Advanced Water Treatment (email: man h.huang@ csiro.com.au), Dr Brian Bolto is a Senior Scientist, and Dr Thuy Tran is a Research Scientist, at CSIRO Materials Science and Engineering, Clayton , Victoria.

Jung, H.-H., Hwang, S.-W., Hyun, s.-H ., Lee, K.-H. and Kim, G. T. (2007). Capacitive deionisation characteristics of nanostructured carbon aerogel electrodes synthesised via ambient drying. Desalination 216, 377-385. Kuchinsky, E., Burstein, R. and Frumkin, A. (1940). Adsorption of electrolytes on charcoal. Acta Physicochimica. URSS 12, 795-830. Lee, L. Y., Ng, H. Y., Ong, S. L., Hu, J. Y., Tao, G. H., Kekre, K., Viswanath , B., Lay, W. and Seah, H. (2008). Capacitive deionisation for RO brine recovery in NEWater production. Proc. Singapore International water Week, 23-27 June, p.

References Andelman, M. (1998). The flow through capacitor: A new tool in wastewater purification. Filtration & Sepn. 35, 345348. Arnold, B. B. and Murphy, G. W. (1961). Studies on the electrochemistry of carbon and chemically modified carbon surfaces. J. Phys. Chem. 65, 135-138. Bolte, B. A. and Weiss, D. E. (1962). Semiconducting polymers containing coordinated metal ions. Aust. J. Chem. 15, 653-667 . Bolte, B. A. and Weiss, D. E. (1965). Organic polymers that conduct electricity. Physics and Chemistry of the Organic Solid State, ed. Fox, D., Labes, M. M. and Weissberger, A., vol 2, pp. 67-120, Wiley, New York. Chen, J. H., Li, W. Z., Wang, D. Z., Wen, J. G. and Ren, Z. F. (2002). Electrochemical characterisation of carbon nanotubes as electrode in electrochemical double-layer capacitors. Carbon 40, 11931197.

5. Lee, J.-B., Park, K.-K., Eum, H.-M. and Lee, C.-W. (2006). Desalination of a thermal power plant wastew ater by membrane capacitive deionisation. Desalination 196, 125- 134. McNeil!, R. and Weiss, D. E. (1960). Some novel carbonaceous polymers. Proc. 4th Carbon Conf., Pergamon , New York, p. 281-290. Oh, H.-J., Lee , J.-H., Ahn, H.-J., Jeong, Y. , Kim, Y.-J. and Chi, C.-S. (2005). Nanoporous activated carbon c loth for capacitive deionisation of aqueous solution. Thin Solid Films 515, 220-225. Pekala, R. W., Farmer, J. C., Alviso, C. T., Tran, T. D., Maye, S. T., Miller, J. M. and Dunn, B. (1998). Carbon aerogels for

electrochem ical applications. J. NonCryst. Solids 347, 238-245. Ryoo, M.-W. and Seo, G. (2003). Improvement in capacitive deionisation function of activated carbon cloth by titania modification. Water Research 37, 1527-1534. Straits Times. (2008). Cheaper w ay found to make seawater drinkable. www .straitstimes.com/Free/Story/ STI Story_251016.html van Limpt, B. (2008). Capacitive deionisation. http:// net2client.hscg. net/ZZZ/08/ 08200/Salts%20Bart%20van %20Limpt.pdf Wang, X. Z. , Li , M. G. , Chen , Y. W. , Cheng, R. M., Huang, S. M. , Pan , L. K. and Sun, Z. (2006) . Electrosorption of NaCl solutions with carbon nanotubes and nanofibres composite film electrodes. Electrochem. So/id-State Letters 9(9), E23-E26. Welgemoed, T. J. and Schutte, C. F. (2005). Capacitive deionisation technologyâ&#x201E;˘: An alternative desalination solution. Desalination 183, 327-340. Zhang , D., Shi, L., Fang, J., Dai, K. and Liu, J. (2006). Influence of carbonisation of hot-pressed carbon nanotube electrodes on removal of NaCl from saltwater solution . Mater. Chem. Phys. 96, 140144. Zou, L., Morris, G. and Daoduo, Q. (2008a). Using activated carbon electrodes in electrosorptive deionisation of brackish w ater. Desalination 225, 329-340. Zou , L., Li, L., Song, H. and Morris, G. (2008b). Using mesoporous carbon electrodes for brackish water desalination. Water Research 42, 23402348.

Christen, K. (2006). Desalination technology could clean up wastew ater from coal -bed methane production. Environ. Sci. Technol. 40, 639. Dai, K., Shi, L. , Zhang, D. and Fang, J. (2006). NaCl adsorption in multi-walled carbon nanotube/active carbon combination electrode. Chem. Eng. Sci. 61 , 428-433. Farmer, J. C., Fix, D. V. , Mack, G. V. , Pekala, R. W. and Poca, J. F. (1996). Capacitive deionisation of NH4 CIO4 solutions with carbon aerogel electrodes. J. Electrochem . Soc. 143, 159-169. Gabelich, C. J., Tran , T. D. and Suffet, I. H. (2002). Electrosorption of inorganic salts from aqueous solution using carbon electrogels. Environ. Sci. Technol. 36, 3010-3019. Hsieh, C.-T. and Teng, H. (2002). Influence of oxygen treatment

41~. u,=rs~~~-

4/8 Leighton Place PO BOX 240 Hornsby NSW 2077 Toll Free (from land lines) 1800 25 30 40 Fax 02 9477 7363 Email: c lientservice@harvestore.com.au

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IN SITU (DOWNHOLE) DESALINATION TECHNOLOGY C Barber, S Marimuthu, C Dawson Abstract

lower as only permeate (high quality desalinated water) is pumped to the surface, and there is no need for holding tanks or additional pumps to provide treatment. The whole ISD system (RO, permeat e pumping to the surface, concentrate flow to lower in the bore and aquifer) is powered by a single submersible pump.

A novel brackish groundwater desalination process aimed at relatively small scale users, utilises an RO module sunk into a borehole below the water table, powered by a single submersible pump. The concentrate is dispersed at the base of the aquifer using natural groundwater processes to maintain generally minor increases in salinity within the vicinity of the borehole.

Introduction In Australia, the National Land and Water Resource Audit (NHT, 2001) indicated that 72 % of readily accessible groundwater (2 1,000GL) was of potable quality (<1000mg/ L as TDS), and the majority of non-potable groundwaters had TDS of <15,000mg/ L, within the brackish water range. Given the poor datasets on non-potable waters, it is anticipated that there are significantly greater volumes of non-potable groundwater available than indicated above. Although desalination using reverse osmosis technology has improved significantly over the last decade, the process is still expensive and in inland areas particularly there are problems with disposal of concentrates. The latter are often disposed of improperly from smallscale plants (discharged uncontrollably to streams, sewers or groundwater) potentially giving rise to environmental contami nation. Disposal in evaporation basins is also used in inland areas in specially constructed basins, at significant expense. Given increasing demand for water supplies for drinking and other uses, an alternative to conventional RO treatment is required which is lower cost, and more environmentally friendly. In Situ Desalination {ISD) was developed to try to attain these goals.

ISD Process In Situ Desalination {ISD) of brackish groundwater, is a novel process which is a distributed treatment system (as opposed to centralised system) specifically aimed at relatively small scale

136 FEBRUARY 2009 water

Plate 1. The beta-model ISD system ready for installation at the Joel South site in Victoria, showing the main 250mm diameter steel treatment vessel, submersible pump and steel permeate lines on which the system is suspended in the borehole. users. However, it is scalable t o include medium-sized demands up to approximately 200MUy, possibly higher. The syst em is based on conventional reverse osmosis (RO) treatment (Barber, 2005) but is designed for downhole operation, where treatment is carried out entirely within a borehole below the water table (Barber, 2007). The technique essentially takes a hydrogeological approach to the design of the system to obtain significant benefits in costs and environmental impact. ISD treatment offers a number of advantages over conventional RO treatment. In general treatment costs are

High quality water at competitive cost.

Treatment is carried out under ambient groundwater conditions by pumping groundwater feed into the ISD syst em through an upper feed screen in the borehole. Groundwater conditions are low-energy compared with surface waters, with no sunlight, no photosynthesis, no algae, rare macrobiota (stygofauna), but with bacteria of various sorts. The aquifer also acts as a natural filter medium which limits the amount of suspended mineral solids in the groundwater feed. In most of the tests so far, the turbidity of feed groundwater has been <1 NTU, but biofouling of RO membranes from bacteria is an ever-present problem with ISD as it is for all RO membrane systems. However, a simple maintenance regime during treatment has been devised and tested to minimise this, and provide a more sustainable treatment regime. One of the main features of ISD is its ability to include concentrate disposal integrated within the overall RO treatment, using natural groundwater processes to maintain generally minor increases in salinity of feed groundwater within the vicinity of the ISD borehole. The concentrates are fed during ISD to a position which is lower in the borehole. The latter position is isolated from the groundwater "feed" zone within the bore by a sealing packer emplaced within bore casing. From there, these more saline fl uids exit the bore through the lower screened section into the aquifer. These fluids move to lower elevations in the aquifer due to the difference in density between these fluids and groundwater. From there they disperse naturally with the groundwater flow away from the borehole. Also because concentrates are redirected to lower in the aquifer, there is

technical features

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~ refereed paper

no need to minimise the volume of these, which allows the ISD-RO system t o run at low recoveries, avoiding scaling and precluding the add ition of chemicals such as antiscalants to t he feed groundwater. The latter clearly reduces the environment al impact on the aquifer. Dipole flow (localised return of concentrates into the feed stream) can occur, however, in severe cases resulting in a strong increase in feed ground water salinity until the treatment process fails due to the osmotic pressure being too large for treat ment to occur. In ISD, some dipole flow can be t olerated (possibly as much as 30% of the feed) but the dual effects of natural aquifer stratification and density-driven flow co mbine to limit this.

Research trials To better understand the impacts of dipole flow, the effects of ISD operation have been modelled using physical (sand-tank) simulations and numerical modell ing conducted at the Cent re for Water Research, University of Western Aust ralia (Reynolds et al, 2007). Th e numerical model was used to simulate flows in the physical model (Figure 1), and was also calibrated to results of field trial at a site in the Swan Val ley (Barber et al, 2007) to provide predictions of long-term impacts of ISD on groundwater at the site.

Field Trials Trial 1 A site in the Swan Valley was chosen for field-scale assessment of ISD operation, using a 165mm diameter cased and screened borehole drilled to a depth of 26m into a sandy-clay aquifer between 23m and 26m below ground The aquifer was confined beneath clays and clayey sand sediments, and the bore screen (slotted PVC casing) was set within the 3m-thick aquifer. Background groundw ater TDS was approximately 2800-3000mg/ L in the region of the bore. In the trial, a prototype ISD system, using 4 x 100mm diameter Hyd ranautics ESPA3-4040 RO elements, gave around 500-600Uh of permeate with TDS of - 120mg/ L (35% recovery) from a feed TDS wh ich stabilised at an average TDS of 3500mg/ L (Barber et al, 2007). Figure 2 shows the variation in the salinity of the feed groundwater duri ng the trial. The initial stage of optimisation of treatment (Stage 1) was followed by daytime ISD operation (Stage 2) and then continuous operation (Stage 3). The

Figure 1. Simulations of ISD pumping (extraction of feed groundwater from the upper part of the bore, and reinjection of concentrates in the lower section of the bore) in a sand-tank physical model for early time (5 hours, left-hand side views), and after 1000hours (right-hand side views). The numerical model FEFLOW was used in the simulations, to show flowlines developed for two anisotropy ratios ( ratio of vertical to horizontal hydraulic conductivity K/Kh) of 0.5 (upper) and 0.25 (lower), the latter showing the most stratification (from Reynolds et al, 2007). The left-hand side views show early-time establishment of upward dipole flow to the simulated feed zone of the bore. At later times of 1000hours (right views) a balance has established between dipole flow and downward and lateral (left to right) density-affected flow of concentrate in the lower section of the bore, and radial capture of groundwater feed in the upper section. Dipole flow in both cases in the longer term is limited by stratification and particularly by density contrast which moves concentrates to the base of the simulated aquifer. From this location they move away from the bore and disperse with natural groundwater flow. results show that t here was an estimat ed 20% dipole flow established within the 3m thick aquifer during ISD operation. The shallow thickness of the aquifer was a big challenge for the ISD system, but as a semi-constant feed concentration was maintained over most of the trial period of around 3 months, t his indicated t hat as shown in the simulations in Figure 1, density effects and natural aquifer processes combined to move the concentrates vertically and laterally away from the ISD borehole, dispersing these with natural groundwater flow. Interestingly, the feed TDS immediately after rest periods in the trial (for example see the 3 times in early February, and early and late March in Stage 3 in Figure 2) when no data was collected , was close to ambient levels of 3000mg/ L to 3200mg/ L, this increasing on startup of ISD as dipole flow again developed. Th is data showed that when the ISD system was turned off, concentrates moved quite rapidly to positions lower in the aquifer away from the feed zone during the rest periods, illustrati ng the dominance of the

density-driven flow process within the aq uifer. Monitoring of groundwater during the trial showed the highest TDS concentrations were largely present at the base of the 3m-thick aquifer. Numerical modelling of the long term (10 year) impacts of ISD showed increases in the salinity of groundwater by around 50% (i.e. from a background of 30003200mg/L to 4500mg/ L) mainly at the base of the aquifer withi n a short distance (50m) of the ISD bore. We consider this impact to be minimal, and likely to have negligible effect on a pumping bore close to this impacted zone. In most cases, these higher concentrations would be within natural variability in salinity within t he aquifer.

Trial 2 A second trial using a larger ISD system with 200mm diameter RO elements (DOW Filmtec XLE-440) was carried out in northwest Victoria at Joel South near the town of Landsborough , providing water for the nearby Glenkara Estate Vineyard . The ISD system was installed in sediments referred to locally as the

water FEBRUARY 2009 137

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4000

,~ 0

3600

~j l:,.t

l:,.

3200

/ls:,.

'l:,.

0 I-

pp,

l:,.l:,.

(;;,. l:,. 2800

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2400

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-+---,----.----,---..---,------,----,-----r----.---.

10/10/06

11119/06

12129/06

2/7/07

3119/07

4'28/07

Figure 2. Variation in the TDS of feed groundwater during the Swan valley trial. Note the much lower initial feed TDS immediately after periods when the ISD system was turned off for periods of 4-5 days, particularly in Stage 3 where the system was operated continuously.

Shallow and Deep Leads. These sediments are palaeochannels which are several kilometres wide, containing gravel layers of thicknesses up to 1Om or more. These form excellent confined aquifers but in most cases contain brackish groundwater. Groundwater TDS in this area varies from 3000-7000mg/L, but at Joel South was generally within the range 3000-3500mg/L. The trial commenced in August 2008, by emplacement of two 50mm diameter monitoring bores and an ISO bore with 300mm diameter screen and casi ng to accommodate the larger ISO system. Two gravel aquifers were present at the site, confined beneath 20m of mainly clayey sediments. These consisted of an upper aquifer zone between 20-27m below surface and a lower zone 30-33m, these being separated by a 2-3m th ick clay layer. The ISO borehole was completed w ith a 300mm diameter screen within the upper aquifer as a feed zone, and the lower part of the bore below 30m was fitted with a 175mm diameter screen within the lower gravel aquifer as the concentrate return zone. The two zones were separated by a packer situated within the 175mm casing. The submersible pump of the ISO system is shown in Plate 1 being connected to the treatment vessel within the bore, prior to being lowered into the borehole. The Swan Valley trial had identified that biofouling was a key problem with ISO, which required on-going maintenance regime to allow sustainable operation in the field. Consequently a system for in situ washing and sterilising of membrane elements was incorporated within the unit, and this was carried out daily for 40 minutes using sodium metabisulphite solution. The biostat solution was recycled and recovered at the surface. Because the ISO system was operated at low recoveries of permeate (40%, Table 1), there were no anticipated problems with scaling and no chemicals

138 FEBRUARY 2009 water

Plate 2. Attaching the submersible pump to the top of the 250mm diameter treatment vessel at the Glenkara trial site. The treatment vessel is suspended within the 300mm diameter borehole casing from a removable slip-plate and steel cover on top of the casing.

such as antiscalants were added during the trial to the groundwater feed . The results of the testing are summarised in Table 1, and compared with modelled system performance using the DOW ROSA 6.1 model of the RO process (DOW Filmtec, 2007). The results indicate that an average of 4 KUh of permeate can be extracted from the aquifer using the ISO system, under the conditions of the test. The quality of the permeate is very high (TDS 100mg/L). Unlike in the Swan trial, the feed groundwater concentration remained constant over the course of the trial (on average 3200mg/L) indicating no dipole flow is taking place because of the intervening clay layer. The TDS of concentrates has also remained steady at an average of 5000mg/L (Table 1). In addition, drawdown in the ISO borehole during pumping for 3 months and removing over 6ML of permeate, was small (-25cms). Impacts on TDS of groundwater and groundwater levels at the monitoring bore 50m from the ISO bore and within the lower aquifer to which concentrates are returned showed partial breakthrough of the dispersed concentrate (up to 4300mg/L) after 3 months of continuous ISO operation. Modelling using FEFLOW with input parameters (K, hydraulic gradient, porosity) as determined during site testing, suggests that any increased salt concentrations in groundwater wou ld

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~ refereed paper

Table 1. Summary of performance of the ISO system at the Glenkara (Victoria) trial site.

Feed groundwater TDS Feed groundwater flow Permeate TDS Permeate flow Concentrate TDS

Modelled*

After 60 days operation

3200mg/L

9.75KUh

10KUh

89mg/L

100mg/L

3.6KUh

3.8-4.2KUh

5000mg/L

4800-5040mg/L

Âˇoow ROSA v 6.1 model (DOW Filmtec, 2001) extend only 200m from the ISD bore after 10 years continuous pumping, with t he highest concent rat ions being close to the ISD bore. Perhaps more importantly, a production bore screened within the upper and lower aquifers and - 20m lat erally d istant from the ISD bore, within t he zone of lower aquifer impacted by concentrates, was found to have TDS concentrations of - 4000mg/L, only 300mg/L above initial background concentrations in this bore of 3700mg/L (Barber et al, 2007). Thus t he impact of ISD on t his bore a short distance from t he ISD b ore is within 10% of the background readi ng, well withi n natural variability in salinity.

The Authors

Dr Chris Barber is the Executive Director of Desaln8 Pty Ltd (email cbarber@desaln8.com). He was Director of t he Aust ralian Centre for Groundwater Stud ies until 2005, and is current ly Principal of Crisalis International Pty Ltd which developed the ISD concept.

Dr Selva Marimuthu and Chris Dawson are respectively Principal Hydrogeologist and Managing Director of Desaln8 Pty Ltd. Desaln8 Pty Ltd operates from Level 1, Unit 21 , Business Park Drive, Notting Hill, Victoria 3168.

References Barber C, 2005. Water Desalination. Patent AU2005/000052. Barber C, Pearson B, Reynolds DA and Dawson C, 2007. In Situ desalination of brackish groundwater: A new distributed approach for obtaining high quality water supplies in areas lacking fresh water. Proceedings 2nd International Water Association ASPIRE 2007 Conference, Water and Sanitation in the Asia-Pacific Region: Opportunities, Challenges and Technology. 29-31 October 2007, Perth, Western Australia. DOW Filmtec, 2007. Reverse Osmosis Systems Analysis (ROSA) model: ROSA 6.1. Dow Water Solutions (www.dow.com). Reynolds D A, Kington S and Barber C, 2007. Numerical modelling of In Situ Desalination Systems. Desaln8 Ply Ltd Confidential report T15, November 2007.

Future development of 15D The successful trials of ISD and back-up modelling have essentially provided proof-in-pri nciple of t he the ISD process. It is also felt that ISD can make a sig nificant contributio n, providing high quality water supplies at competitive cost s to communities and industrial and agricultural developments in areas where the only available water resou rces are brackish groundwater. Further invest igations of subsurface processes occu rring during ISD are being carried out in additional trials, and in particular, the nature and control of membrane fou ling is being actively investigat ed. Given the low and very localised environmental impact of ISD (see above), discussions are taking place with stat e regu lators in Australia (particularly in Victoria in relation to the results of the Glenkara trial) to provide mechanisms for allowing commercial ISD operations to go ahead.

Acknowledgments The authors wish to acknowledge support research funding from Land and Water Australia for groundwater modelling of dipole flow and for the Swan Valley ISD trial. We also acknowledge support from an Aus lndustry Commercial Ready grant for the Glenkara, Victorian t rial.

water FEBRUARY 2009 139

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[3]

refereed paper

REED-BED VERSUS SLOW SAND FILTRATION: A COST COMPARISON T Kuypers, M Ling, D Kilgore, M PTaylor Abstract This article models the economic cost of establishing and maintaining reed bed filtration for the production of potable water compared to a slow sand filtration (SSF) system capable of purifying an equivalent volume of water. Reed bed filtration has been used for potable water filtration at Clear Water Lagoon (CWL) in Mount Isa, northwest Queensland since 1968. The system req uires minimal maintenance and filters -60 ML of catchment runoff each day to a standard that complies with the Australian Drinking Water Guidelines (NHMRC, 2004). Although comparative analyses reveal minimal differences in the quality of water produced or the operating costs of the two systems, the capital outlay for establishing a reed bed system equivalent to CWL amounts to less than half that of an SSF system. A 100-year life cycle analysis found the cumulative expenses of CWL to be approximately $19.5 million compared to $32.1 million for a SSF facil ity. Economic evaluation has confirmed the absolute value of CWL to the Mount Isa water supply system. There are also several environmental benefits that arise from harnessing the free ecosystem services of a reed bed structure. These include relatively low maintenance requirements, lower energy consumption and running costs and the provision of substantial wetland habitat for biota.

Keywords: economic evaluation filtration, reed beds, potable, slow sand filtration, water.

Introduction The water purification services provided by wetlands have long been acknowledged and have inspired natural methods for the treatment of aqueous effluents (Rousseau et al., 2008). Horizontal and vertical structured reed beds, engineered wetland buffers and detention basins for municipal and industrial waste filtration have earned world-renowned respect for their efficacy (Lambert & Graham, 1995; O'Hagain, 2003; Vacca et al., 2005), economic viability, and inadvertent ecological worth (WRP, 1998, Hanley and Taylor, 2008).

140 FEBRUARY 2009 water

Figure 1. Lake Moondarra water supply catchment. However, such methods of filtration have never formally bridged to feature in the contemporary treatment of potable water. The utilisation of 'free ecosystem services' of wetland environments (i.e. filtration of water by wetlands and/or artificial reed bed type structures), provides a means of adding environmental value at a local scale that can also equate to economic savings. Clear Water Lagoon (CWL) is a unique system that integrates reed bed filtration and regulated flows to produce an average of 60 MUday of potable water (based on 2006-2007 usage, MIW, 2007). Kuypers et al. (2006) examined the functionality of CWL and found the system to be particularly efficient at addressing turbidity and particulate heavy metal concentrations in catchment runoff. The water fi ltered through the system (before chlorination) complied consistently with the Australian Drinking Water Guidelines (NHMRC, 2004). This article models the costs of establishing and maintaining a CWL system afresh and compares this to the costs associated with a slow sand

The Mt Isa Clear Water Lagoon is cheaper than slow sand filters.

filtration (SSF) plant capable of fi ltering an equivalent volume of potable water. Economic val uation of naturally based filtration systems that are specific to potable water production wil l assist in establishing their economic credibility and encourage the transfer of reed bed filtration technology to wider applications in suitable water supply catchments. In understanding both the economic savings and environmental alt ernatives, associated water supply operators wi ll have a greater range of technologies to help achieve ESD goals while supporting healthy ecological functioning of water supply systems. Mount Isa Water (MIW) identified SSF as the only viable alternative they would have considered implementing for potable water clarification in this catchment. Consequently, SSF was selected over rapid gravity and other forms of high-rate filtration for economic comparison with CWL for this article. Slow sand filtration is considered to be a relatively inexpensive and reliable method of runoff purification and is used by numerous water suppliers around Australia (Fogel et al., 1993; Lambert & Graham, 1995; Hijen et al., 2004) as well as internationally (Blackburn & Associates, 2006). Calculating the actual start-up and annual costs of CWL has enabled Mount Isa Water to verify the

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~ refereed paper

economic worth of their system. It is also helpful is ascertaining whether their reed bed style design is worth replicating in other water supply catchments as a viable environmental and economical alternative for potable water filtration.

Site Description Providing potable water to the inland city of Mount Isa presented a considerable challenge during the establishment phase of the mining community. The city, with a current population of approximately 22,000 (ABS, 2006), grew from modest beginnings in a valley between two elevated outcrops of the Selwyn Range of northwest Queensland. Substantial annual and inter-annual variations of the tropical continental rainfall patterns made it necessary to dam the ephemeral Leichhardt River to store water for the community and their mine (Xstrata Mount Isa Mines Pty Ltd). The dam was constructed in 1957 on the western branch of the Leichhardt River, 19 km downstream of the township to create Lake Moondarra (20° 34' S, 139° 35' E, max. capacity: 106,830 ML) (Figure 1). Once the dam and related storage and supply infrastructure was in place, the reliability of water quality became a prominent issue. It became evident that drinking water should not be sourced directly from Lake Moondarra without filtration, particularly during the wet season. The most significant urban sourced water quality concern can be traced to the Mount Isa Wastewater Treatment Plant (MIWRP) and its associated effluent reuse scheme (Boase & Wood, 2006). During prolonged heavy wet season rains direct and indirect contributions from the MIWRP are not uncommon. Concerns for water quality are heightened by the naturally mineral rich sub-catchment and associated Pb-Zn-Ag and Cu mining operations on the western side of the Leichhardt River (Finlayson, 1980). Recent studies have revealed significant metal-rich sediments remain in the Leichhardt River system despite remediation efforts in the early 1990s (Taylor et al. , 2007; Mackay & Taylor, 2008; Taylor and Hudson-Edwards, 2008, Taylor et al., in review). Since the longevity of the remote inland Mount Isa community was completely reliant on the continued discovery of viable lodes (Blainey, 1970), there was an initial hesitancy to invest large sums of money in Mount Isa's infrastructure. Arising from these dual demands was a need to develop a cost effective method to produce drinking water to an acceptable standard, hence the formation of CWL.

The Clear Water Lagoon Filtration System Clear Water Lagoon was first formed in 1968 when a shallow depression next to Lake Moondarra was dammed. Water was pumped from Lake Moondarra and into Clear Water Lagoon during times of low turbidity to ensure a 30-day supply of clear water during wet season river flows. However, since its inception CWL has been extensively modified to form an indispensable part of the Mount Isa's water treatment system, which is now used throughout the year. Water from Lake Moondarra is pumped using a floating pump station into the CWL system via an open-earth flume which directs flow via a settling pond, through reeds and other macrophytes, and finally into the primary holding lagoon (Figure 2). The macrophytes, present throughout the system, perform an integral role in the filtration process. The dominant macrophytes in the lower flume, settling pond and main lagoon include Hydril/a verticillata, Potamogeton tricarinatus, Typha orientalis and Vallisneria spiralis (Kuypers et al., 2006). Approximately 82% of the surface area of the lagoon has vegetation cover (extending from the shoreline to a depth of approximately Sm).

Figure 2. Clear Water Lagoon. The main lagoon covers an area of 0.67 km 2 and has an average depth of 6 m (Figure 2). Water is periodically pumped into the open-earth channel at a maximum rate of 70,000 m 3 day·1 to maintain a lagoon volume of 2.19 x 10m3 . The off-take pump (Figure 2) accesses water from the top 50 cm of the main lagoon at an average rate of - 41,500 Uminute. A compressed air destratifier in the northwest corner of the main

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water FEBRUARY 2009 141

water supply lagoon, near the off-take operates in automatic mod e throughout t he year to prevent stratification. Water quality was shown t o improve progressively from the intake through to the main lagoon by Kuypers et al. (2006). During this study, turbidity declined from 22 NTU (mean reading at intake) to 4 NTU (mean reading at out-take). Similarly, water metal concentrations were reduced significantly throughout the system. Al concentrations were reduced from 19 µg/L to less t han instrumental detection limits, Cu f rom 81 to 9 µg/L, and Fe from 300 t o 37 µg/L. Conductivity and pH remained steady throughout the system, averaging 329 µSiem and 8.2 respectively (Kuypers et al., 2006). From the out-take water is piped to, and chlorinated at, the Terminal Reservoir before being distributed to the town and various mining operations.

The Alternative Option - Slow Sand Filtration Although SSF is the oldest type of municipal water filtration it remains a reliable method for small populations. The process percolates untreated water slowly through a bed of porous sand. Influent water is introduced over the su rface of the filter and is then drained from the bottom. The filter consists of a tank, a bed of fine sand, a system of under-drains to collect the filter water and a flow regulator to control the filtration rate (0.10 m/h r). No chemicals are added to aid t he filtration process. Whi le SSF systems are considered to be relatively inexpensive, they do requi re skilled operators . Blackburn and Associates (pers. comm. , 2006) were consulted in 2006 to provide an outline of costings for an appropriate SSF water treatment faci lity for Mount Isa's water supply. An integrated syst em of 10 BFF1000 units was recommended to produce a vo lume of potable water comparable to the capac ity of CWL. The floating pump station in Lake Moondarra would pump water into a manifo ld that supplies the 10 BFF-1000 units. Th is allows flexibility in how many fi lters are in operation at any one time. Following filtration, water would be piped, chlorinated and distributed from the Terminal Reservoir. The specifications of the BFF-1000 (Blue Future Filters) are listed in Table 1.

Comparative Costs of CWL and SSF Capital costs The costs of excavating and establishing an equivalent CWL system with primary storage reservoir, open earth flume and

142 FEBRUARY 2009

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Table 1. Slow Sand Filtration BFF-1000 Specifications. Volume (ml)

1404

Installation man-hours

116

0.35 mm sand volume (m 3)

438

3-6 mm gravel (m3)

9-14 mm gravel (m3) 20-63 mm gravel (m3)

Total media (m3)

638

(Source: Blackburn & Associates, 2008) settling pond are estimated at $1,608,000. The macrophytes planted at the CWL have propagated naturally over the past 40 years. The estimated capital cost used here does not account for natural promulgation, but instead represents the cost of planting macrophytes to cover an equivalent surface area. Consequently, the planting represents the most significant start-up expense. The two dominant macrophytes in t he CWL system are Hydrilla verticillata and Typha orientalis, which cover approximately 60,000 m2 and 80,000 m2 , respectively. The total cost for procurement and planting is estimated to be between $2. 1 million and $3.5 million (Provincial Native Plants, ACT, pers. comm., 2006). Capital costs for t he BFF-1000 filters include all tanks, associated fitti ngs and other hardware necessary for a fu lly operational BFF-1000 system ($1.5 million, Table 2). The filter media costs relate to t he sand and gravel needed to effect proper operation and filtration of the catchment runoff. Miscellaneous costs refer to labour costs, site development costs, fencing and faci lity costs. The co nstruction of multiple units result in savings on miscellaneous expenses d ue to shared facilities, fencing and site development. The cost estimate for 10 BFF-1000 filtration units is estimated to be AU$12.6 million (Blackburn & Associates, pers. comm., 2006). This estimate was based on previous construction projects preformed by Blackburn & Associates and is not site specific.

Maintenance and operator costs Maintenance of CWL is estimated to be, on average, $100,000 pa, with an additional $4,000 for annual monitoring and diving expenses (lian Wilson, MIW, pers. comm., 2007). To ensure that build up of sediment does not interfere with the natural filtration processes it is necessary that both the main lagoon and the settling pond be cleaned every 5 years. The cost for this procedure is in the order of $50,000 (lian Wi lson, MIW, pers. comm., 2007). Annual dredging also includes the sectioned harvest of aquatic macrophytes. Cyclic harvesting of mature aquatic vegetation (particularly in the settling pond) reduces biolog ical oxygen demand and total suspended solid inputs from decaying biomass litter (Karathanasis et al., 2003). Frequent harvesting also encourages new growth and enhances nutrient and heavy metal removal (Alvarez and Becares, 2008), w hich sustains the systems clarification capacity. The annual cost for wet harrowing c leaning the 10 BFF-1000 filtration units has been quot ed at $60,000. For wet harrowing to occur, the water level in the supernatant above the sand bed is allowed to empty to just above t he sand layer by turning off the incoming f low. The top layer of sand is raked whi le inflowing water is allowed to create a stream across its surface. The filtered material is all owed to drain away flow via an o pen valve just above the sand layer. This process is continued until harrowed wat er is no longer turbid. Application of this technique means that neither resanding nor scraping is necessary, and that re-ripening of the biofilm is not required because is not destroyed Th is is a method that has been successfully used at other SSF systems comm issioned by Bl ackbu rn and Associates (Blackburn, 2006). In addition to cleaning costs, routine maint enance to pumps, fittings and the tanks is required throughout the year, bringing the annualised maintenance costs to $160,000 (Table 3). In addition to the annual maintenance costs (Table 3), both systems require a

Table 2. Comparative capital costs for CWL and an equivalent BFF-1000 system.

Capital Costs*

CWL

Cost($)

BFF-1000 System

Cost ($) per unit**

Cost($)

Excavation of Lagoon

1,608,000

Filters (Blue Future Filters)

595,000

5,950,000

Planting of Macrophytes

3,500,000

Filter Media Miscellaneous

225,000 717,000

2,250,000 4,400,000

Total

5,108,000

Total

1,537,000

12,600,000

* Capital costs for CWL refer to the estimated costs of re-creating CWL ** Cost of installation per BFF-1000 unit. 10 units are required

technical features

water supply

refereed paper

part-time operator. Coordinating the daily up-keep of the 10 BFF-1000 fi lter units is estimated to represent a per annum operational expense of $35,000. Clear Water Lagoon requires less time from support st aff. Routine operation of pumps and the destratifier, water quality monitoring and occasional maintenance comes to approximately $30,000/ year (lian Wilson , MIW, pers. comm., 2007).

Comparative life cycle analysis A comparison of costs and benefits of the CWL and SSF systems over their respective lifespans assists in clarifying the long-t erm financial commitments necessary to establish and maintain the two different filtration methods.

A lifespan of 100 years for the CWL system is a conservative estimat e. If maintained properly the system should be operational for much longer. However, as a remote inland mining commu nity it is not possible to predict if Mount Isa's population and their wat er requi rements wi ll exist this far into the future. Nevertheless, it is not unreasonable to expect that a typical munici pal instillation cou ld have a projected 100-year operational life span. Compared with the

Table 3. Comparative maintenance and operating costs for CWL and BFF-1000 systems.

Annualised

CWL

Cost($)

BFF-1000 System

Cost($)

General Maintenance

Cleaning (wet harrowing)

60,000 100,000

Labour

100,000 4,000 10,000 30,000

Labour

35,000

Total

144,000

Total

195,000

Diving

Costs

Dredging (annualised)

General Maintenance

Table 4. Cost comparison of the Clear Water Lagoon filtration system and SSF system over 30 and 100 years. Raw Total Cost ($) Clear Water Lagoon regulated flow/ buffer system (CWL)

Cost / Annum (no inflation) Cost / Annum (incl. inflation) Slow Sand Filtration (SSF)

Cost / Annum (no inflation) Cost / Annum (incl. inflation)

30 years

100 years

9,478,000 315,933 388,500 18,450,000 615,000 712,500

19,508,000 195,000 701 ,000 32,100,000 321,000 991 ,000

• Costs rounded up to the nearest whole figure and do no include the compound effect of inflation, which would have the effect of increasing the differential costs. •• Costs rounded up to the nearest whole figure, including the compound effect of inflation. A conservative estimate based on the Reserve Bank of Australia preferred range of inflation, 2-3%pa, an inflation rate of 2.5 % pa has been used.

CWL self-sustaining system, the lifespan of the SSF is more dependant on local environmental conditions (e.g. elevated salt concentrations in catchment runoff),

adequate maintenance and correct operation. Consequently Table 4 presents raw total costs over 30 and 100-year life spans.

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Using a lifespan of 100 years, the annualised comparison found CWL to be 40 % less than the cost of the SSF water potable water treatment system (Table 4). The results outlined in Figure 3 demonstrate clearly that the annualised operational costs are comparable for both systems, but that there is a significant difference in the initial capital costs for each system. Harnessing natural ecosystem services in the form of a regulated reed bed environment has proven to be both ecologically viable and economically advantageous for MIW. The best est imate for the excavation and planting of the natural reed bed system is less than half the cost of commissioning the establishment of a SSF system (Table 2). The annualised savings from CWL equate to $51,000 (or 26%, Table 3) when co mpared to the SSF system. When including inflation, the cost differential becomes more apparent over time, increasing to $289,000 pa or 30 % over 100 years (Table 3).

Conclusion Clear Water Lagoon is a demonstration of how reed bed technology can be

$14,000,000

$250.000 $200,000 $150,000

$10,000,000

c3*

r - - -- - ---================1

$12,000,000

refereed paper

$ 100,000 $50,000

$8,000,000

$6,000,000

, , 9 10 11 12 13

SSF CWL

S4,000,000 $2,000,000

Years

Figure 3. Comparison of the set-up and annual costs of a SSF system and CWL or an equivalent system. integrated into potable water treatment successfully. When compared to the SSF alternative, CWL represents an attractive method for the filtration of Leichhardt River runoff for potable purposes. Clear Water Lagoon has the capacity to produce water to within Australian drinking water standards (M IW, 2007). With the 100-year cu mulative cost estimate being 60 % of the alternative SSF system, Mount Isa Water can continue to use CWL with the knowledge

that it is both operationally and economically efficient. The cost estimates presented herein demonstrate that it is economically viable to consider an equivalent-type of CWL filtration system for application in other water supply catchments. However, prior to the imposition of such a system, it would be prudent to undertake extensive raw water quality analyses co upled with an assessment of the risks and hazards within the water supply catchment to

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water supply

refereed paper

ensure pollutant loadings are not beyond t he capacity of a natural filtration system. The benefits and values associated with the CWL system extend well beyond simple economic savin gs. The free ecosystem services provided by CWL are not o nly of significant value to the production of adequate quality water, but they have also become a v aluable part of t he local environment through the provision of wetland habitat for birds, fish, amphibians, reptiles and various invertebrates.

Acknowledgments The aut hors than k Mount Isa Water Board for t heir logistical and financial support during the course of t his st udy. lian Wilson, CEO of Mount Isa Water, is thanked for his support and encouragement without which th is project would not have been possible. We are grateful for the information supplied by Humphrey Blackburn of Blackburn and Associat es, WA USA, relating to the setup cost s for slow sand filtration systems. Lisa Roberts from Provincial Native Plants, ACT is thanked for her help in developing a cost estimate for a revegetation plan for Clear Water Lagoon.

AUSTRAL IA

recently moved from the Department of Physical Geog raphy at Macquarie University and is now working as a Commissioner of t he Land and Environment Court of NSW, Macquarie Street , Syd ney, 2000. Email: Commissioner_Taylor@courts. nsw .gov.au

The Authors

Tabitha Kuypers is a MSc student at the Department of Physical Geography, Division of Environmental and Life Sciences, Macquarie University, Sydney, NSW, 2109, Aust ralia. Email: tkuypers@els.mq.edu.au. Megan Ling is a Risk Analyst at Risk Frontiers - Natural Hazard Research Centre, Macquarie University, Sydney, NSW, 2109, Aust ralia. Email: mling@els.mq.edu.au. Daniel Kilgore is a Ph D student of the Department of Physical Geog raphy at M acquarie University. His research is based at t he Centre for Environmental Contaminants Research CSIRO Land and Water where he is carrying out his research with Dr Simon Apte. Email: Daniel.Kilgore@csiro.au. Mark P. Taylor, PhD, is an environmental scientist with specific research interests in lead and ot her metal contami nants, river systems and environmental plan ning. He has

Phone: 08 8431 2281

References Alvarez, J. , & Becares, E. 2008. The effect of Plant Harvesting on the Performance of a free water surface constructed wetland. Environmental Engineering Science. Vol. 25 (8), pp. 111 5-1122. Australian Bureau of Statistics (ABS). 2006. Available at: http://www.abs.gov.au/ AUSSTATS/abs@nsf- Accessed April 3rd 2007. Blackburn & Associates, 2008. Available at: http://www.slowsandfilter.com/, http://www.bluefuturefi lters. com/ munici pa I.html- Accessed May 1st 2008. Blackburn, H. 2006. Summary of Performance Characteristics of Blue Future Filters Slow Sand Filters. Blackburn & Associates, Washington. Boase, A. , & Wood, H. 2006. What are the statutory obligations for Mount Isa Water Board as a bulk supply authority to address water quality issues to customers? Golder Associates, for Mount Isa Water Board, Brisbane. pp. 15-21.

www.maric.com .au Email:mail@maric.com.au

wat er

FEBRUARY 2009 145

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Blainey, G. 1970. Mines in the Spinifex. Angus & Robertson , Australia. pp. 5-9. Finlayson, C.M. 1980. Aspects of the hydrobiology of the Lake

Moondarra-Leichhardt River water supply system, Mount Isa, Queensland. Unpublished Doctoral Thesis. James Cook University of North Queensland. pp. 55-67. Fogel, D. , Isaac-Renton, J., & Guasparini, R. 1993. Removing Giardia and Cryptosporidium by Slow Sand Filtration. Journal American Water Works Association. Vol . 85 (11 ), pp. 77-84. Gschlobl, T & Stuible, H. 2000. Reed bed systems: design, performance and maintainability. Water Science and Technology. Vol. 41 (1), pp. 73-76. Hanley, C. & Taylor, M.P. 2008. Wetlands minimise algal growth in a horticultural centre. Water, Vol. 35 (6), pp. 98-103. Hijen, W., Schijven, J., Bonne, P., Visser, A., & Medema, G. 2004. Elimination of viruses, bacteria and protozoan oocysts by slow sand filtration. Water Science and Technology. Vol. 50 (1), pp. 147-154. Karathanasis, A.O., Potter, C. L, and Coyne, M.S (2003). Degradation of emergent and submerged macrophytes in an oxb ow lake of an embanked backwater system: Implications for the terrestrialization process. Hydrobiology. Vol. 86, pp. 555- 563. Kuypers, T. , Mackay, A., & Taylor M.P. 2006. Engineered reed beds for the treatment of potable water. Water, Vol. 33 (8), pp. 72-76. Lambert, S.D., & Graham, N.J. 1995. A comparative evaluation of the effectiveness of potable water filtration processes. Aqua - Journal of Water Supply: Research and Technology [AQUA]. Vol. 44, (1 ), pp. 38-51.

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Mackay, A., Kuypers, T. , & Taylor, M. P. 2007. The identif ication and assessment of water quality hazards in the Leichhardt River, Mount Isa, Queensland. In Wilson , A.L., Dehaan, R. L., Watts, R.J., Bowmer, K.H. and Curtis, A. Proceedings of the 5th Australian Stream Management Conference. Australian Rivers: making a difference. Charles Sturt University, Thurgoona, New South Wales, pp. 241- 246. Mackay, A., & Taylor, M. P. 2008. Water chemistry and potent ial environmental toxicology risks associated w it h floodwaters downstream of a major Pb-Zn-Ag and Cu mine: Mount Isa, NorthWest Queensland. Water Down Under 2008 Conference, Adelaide, Australia pp. 2382-2391, (Available on Cd). Mount Isa Water, 2007. Mount Isa Water Annual Report 2007 . pp. 39. Available at: http://www.mountisawater.qld .gov.au/pdfs/annua1Report_2007. pdf - Accessed November 4th 2008. National Health and Medical Research Council & Natural Resource Management Minist erial Council (NHM RC), 2004. The Australian Drinking Water Guidelines (ADWG). Australian Government. Available at: http://www.nhmrc .gov.au/publications/synop ses/ eh1 9syn .htm - Accessed October 20th 2008. O'Hogain, S. 2003. The design, op eration and performance of mun icipal hybrid reed bed t reatment system. Water Science and Technology. Vol. 48, pp. 11 9-126. Rousseau, D. , Lesage, E. , Story, A. , Vanrolleg hem, P & Pauw, N. 2008. Constructed wetlands for water reclamation. Desalination. Vol. 2 18, pp. 181-189. Taylor, M.P. & Hudson-Edwards, K.A. 2008. The dispersal and storage of sediment -associated metals in an arid river system: the Leichhardt River, Mt Isa, Queensland. Environmental Pollution, Vol. 152 (1), pp. 193-204. Taylor, M.P., Mackay, A.K., Kuypers, T. L. & Hudson-Edwards, K.A. in review October 2008. Mining and Urban Impacts on Semi-arid Freshwater Aq uatic Systems: The Example of Mount Isa, Queensland. Journal of Environmental Monitoring. Vacca, G., Wand, H., Nikolausz, M., Kuschk, P., & Kastner, M. 2005. Effect of plants and filter materials on bacteria removal in pilotscale constructed wetlands. Water Research, Vol. 39 (7), pp. 1361-1373. World Resources Program (WRP). 1998. Valuing Ecosystem SeNices. World Resources Institute. pp. 1-4. Avai lable at: http://earthtrends.wri.org/features.php -Accessed October 3rd 2008.

technical features

water supply

BUTTERFLY VALVES: 50 YEARS OF SUCCESS T Weiler Butterfly valves have been quietly writing a true success story in the field of fluid conveyance for over 50 years. From the point of view of consultants, plant designers and users, the main reasons for their widespread use are both technical and economic in nature. The short face-to-face length, low weight and resistance to many fluids handled are the main criteria for the quick and lasting success that soft-seated butterfly valves have had in industrial applications. Other success factors are their hydraul ically favourable design and ease of automation. Function, economic efficiency and reliability, however, hinge on the select ed design of this valve type. Even if butterfly valves of different makes seem to closely resemble one another, they often vary greatly in details of design.

Centred-disc or Symmetric Butterfly Valves A soft-seated centred-disc butterfly valve is a valve whose disc rotates through an angle of 90 degrees about an axis at rig ht angles to the direction of a fluid flow. The pivot point is situated in the centre of the seat, which is also the centre of the pipeline In closed position, the valve disc seals against the liner that surrounds it which is made of elastomer or plastomer. When the valve is open, the fluid flows around the disc on both sides. Like any other piping elements, butterfly valves cause pressure losses, even in open position. However, these are of a much smaller magnitude than on other valve designs where the flow changes direction. They are, therefore, more energy-efficient than offset disc butterfly valves or globe valves. The reason for this is the slim, hydraulically favourable shape of the disc. Thei r short face-to-face length to EN 558-1-20 make symmetric butterfly valves suitable for use as wafer-type valves, for downstream dismantling or as dead-end valves.

Different Types of Body Centred-disc butterfly valves come in two main designs (Figure 1).

Figure 1 On the first, valve disc and stem are two separate parts. Thi s means a singlepiece body with an elastomer liner can be used. This design is less sensitive t o piping forces. On the second more expensive design, valve disc and stem form a single unit which means that the body must consist of two pieces. As this design provides extra safety, it is the valve of choice for chemical or corrosive applications. The valve body has a number of options, the main being: â&#x20AC;˘ Wafer-type body: Th is design is suitable for insertion between mating flanges only (Figure 2a).

There is also a semi-lug body which is suitable for downstream dismantling, a great advantage, for example, during pump maintenance, as well as a Usection body which, thanks to throughholes and threads, can be simply inserted between flanges or mounted to a flange. The advantage of valves fitted between flanges is that the body is only subject to pressure loads, because forces are passed directly from flange to flange vi a the bolted joint. All body types are available with flanged ends to various standards, for example AS4087, EN , ANSI or JIS. The connection between stem and valve disc follows either of two design principles: â&#x20AC;˘ Wetted disc/stem connection

â&#x20AC;˘ Full-lug body: The tapped holes of the lug body provide for straightforward mounting to and dismantling from a mating flange (Figure 2b).

This principle is mainly used on low-cost valves. The valve disc and stem are joined by means of a pin or bolt. As the interface is surrounded by the fluid and the disc and stem are made of different materials, there is a risk of electrolytic or chemical corrosion occurring withi n the gap. From there, corrosion can spread to the stem. This means an increased risk of fracture, possible leakage to

A practical and cost-efficient solution. water FEBRUARY 2009

147

water supply atmosphere and more difficult dismantling of parts.

disc compresses the liner varies. At the same time, the resilience of the liner prevents it from being damaged as the disc closes. The liner's conical contour up to the sealing line minimises the necessary flexing and deformation work. This makes for a longer useful life and lower actuating moments.

â&#x20AC;˘ Positive-locking disc/stem connection

This higher-grade design principle results in a "dry" disc/stem connection which is not wetted by the fl uid. The parts are joined by positive-locking action only, via a flat-end, square-end or a no-play keyed or splined con nection. These design variants prevent corrosion and minimise the risk of fracture. On butterfly valves with positivelocking disc/stem connection, only the discs and liners are in contact with the fluid. As an added advantage, the keyed or splined disc/stem connection is free of play, thus red ucing the risk of deflection.

Butterfly Valve Liners The liner is the most important part of a butterfly valve, because it ensures tight sealing at the flanges, at the seat/disc interface and at the stem passage (Figure 3).

It is either inserted into the body ("loose"), or it is vulcanised into the body direct or on to a backing ring mounted inside the body The advantage of a loose liner is that it can be easily replaced. To ensure tight sealing at the top and

bottom stem passages across the entire 90-degree valve disc travel, the liner should be spherically moulded at these points. The disc is also spherically machined at the stem passages and therefore fits snugly against the shape of the liner. The resu lt is reliable sealing to atmosphere. Depending on the differential pressure and the mechanical properties of the elastomer liner, the amount by which the

A large variety of elastomers are available to suit not only water but oils, oxidising agents such as ch lorine, and corrosive chemicals.

Valve Discs As well as discs made of standard materials, for example nodular cast iron , stainless steel and al uminium bronze, discs with a hard-rubber lining have also been in use for more than 25 years, in particular in water treatment applications. These are just as resistant as discs made from aluminium bronze or duplex steel. Against the backdrop of rising prices of noble and non-ferrous metals, this costefficient solution is gaining in importance. The five millimetre thick rubber lining is applied by vulcanisat ion in an autoclave.

water supply The use of Halar® ECTFE is also on the increase. The material in question is a fluoropolymer which is "powdered" onto the disc where it melts. To apply the coating, the surface of the disc has to be extremely smooth and clean. It is specially treated , so that the Halar powder will adhere to the surface. Every valve disc MUST undergo a high-voltage test to make sure that the coating has a thickness of between 600 and 800 1mm and that there are no flaws. As Halar® ECTFE is ideally suited for slightly corrosive media, it has proved to be a great success in areas like desalination plants, process engineering and water treatment.

Robust and Adaptable Thanks t o their adaptability t o a broad range of fluids and their tolerance of contaminants in the fluid handled, centreddisc or symmetric butterfly valves are today found in the following areas of use: • Water management and drinking water supply • Water treatment • Seawater desalination • Cooling water transport • Hot water circuits

Ease of Automation One generally distinguishes between manually operated and automated valves. Their quarter-turn motion and their st andardised stem ends and actuat or flanges make it relatively easy to equip the valves with actuators The following parameters are required to correctly select a suitable actuator: • The required actuating moment of the valve (information from the manufacturer) • The properties of the fluid (lubricating or not) • The type of auxiliary energy available (compressed air, hydraulic system or electricity) • The requ ired type of operation (on/off, control) The minimum size of the actuating elements for manually operat ed valves is determined according to EN 12570. One of the rules to be observed when selecting the size is that it must be possible to close the valve manually at maximum differential pressure. Up to size DN 250, it is standard practice to actuate the valves direct with a lever. Levers are available for either infinitely variable positioning of the valve disc or positioning by means of a notched plate. They are mounted in such a way that they indicate the valve disc position. Butterfly valves of size DN 300 and above are usually equipped with gearboxes in order to reduce the actuation forces. Today, these are either planetary gear or worm gear. The most important req uirement the gearboxes have to meet is that they be self-locking in every valve position. The gears are maintenance-free, packed with grease and have a position indicator to show the operator the valve disc position. When butterfly valves have to be frequently actuated or operated by remote control, they are equipped with pneumatic, hydraulic or electric actuators. All variants are suitable for on/ off service and control applications.

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Pneumatic Actuators: Sturdy as a Work Horse Most common are pneumatic actuators. For one thing, the necessary compressed air is available in most installations as

water FEBRUARY 2009 149

water supply an auxiliary power source anyway, and for another pneumatic actuators are much safer in potentially explosive atmospheres than electric actuators. There are two types of pneumatic actuator: double-acting and single-acting (Figure 4).

On double-acting actuators, compressed air opens and closes the valve. On single-acting actuators, the compressed air serves to operat e the valve in one direct ion and to pre-tension a spring assembly. The spring retu rn forces actuat e the valve in the other

direction. A distinction is made between spring-to-close and spring-to-open single-acting actuators. Compared with double-acting actuators, spring-closing actuators are larger, because they have to generate the actuating moment of the valve and also pre-tension the spring. In the event of a compressed-air failure, both spring-to-close and spring-to-open actuators return the valve disc to a given fail-safe position. An actuator will have to be complemented with a number of accessories, for example solenoid valves, positioners and mechanical or inductive limit switches. Today, innovative all-in packages are available wh ich combine the said components in a single device with an interface for mounting to the actuator. With this type of arrangement, t here is no need for the cumbersome tubing and wiring of the accessories to the actuators. The device can also be connected to a field bus system.

Conclusion The success factors of the centred-disc (symmetric) butterfly valves - short face-

to-face-length, low weight and, above all, their resistance to a wide variety of fluids handled - are the main reasons for their broad scope of application. Consultants and users alike value t his type of valve as a practical and costefficient solution for fluid flow shut-off or control. The valves' hydraulically favourable design and standardised automation interface also play an important part in their success. Due to the seemingly simple design, the quality differences between the various makes are above all found in details like the shape of the liner and disc and the method used to connect stems and discs. A long service life and frequent actuations are only achievable with highquality valve components. Supposedly cheap butterfly valves can in fact prove to be very expensive in day-to-day use.

The Author Dr Tobias Weiler, a mechanical engineer, is with KSB Aktiengesellschaft, at their headquarters in Frankenthal, Germany. He is Project Manager in Innovation and in charge of Business Development for East ern Europe.

water supply

refereed paper

DOMESTIC RAINWATER TANKS: USAGE AND MAINTENANCE PATTERNS IN SOUTH EAST QUEENSLAND A Gardiner Abstract Rainwater tanks are becoming a standard feature of urban homes in South East Queensland and yet we have limited knowledge about the way these t anks are used and maintained at a domestic level. T his paper reports on the second stage of a social research process that identified the attitudinal approaches, wat er use patterns and maintenance practices of domestic rai nwater tank owners as well as the installat ion features of tanks. Three attitudinal group s were identified amongst tank installers: environmentally committed owners who have a tank to reduce their environmental impact, garden-focussed retrofitters who are compensating fo r water restrictions, and a number of not really interested owners who see tanks as a valid means of supplementing supply during drought but who may not pe r severe with their t anks in t he long term. Data is presented on the water use patterns of different ownership categories.

Introduction Rai nwater tan ks have been installed in South East Queensland (SEQ) in unprecedented n umbers over the last three years spurr ed on by strict water restrictions in th e face of severe drought. Generous rebate schemes have been provided by both the state government throug h the Home and Garden Waterwise Rebate Scheme and by local councils. Since January 2007 new detached homes have been mandated under develop ment Code MP4.2 to provide at least 70kl of water per year for their own needs. The most common means of achieving this is throug h a rain water tank connected to toilets and laundry and for outdoor use. Currently approximately 40% of stand alone houses in S EQ have at least one rainwater tank (see Table 1). The

Table 1. Estimate of the total number of households in SEQ with rainwater tanks at August 2008. Category

Number

Assumptions

Peri-urban

74838

Households not on mains supply, calculated as % of total households (using representative data from the Qld Householders Survey May 2007)

Development conditions before DC MP4.2

2140

Tanks in estates with local development requirements that required tanks (mainly in Pimpama Coomera}

Rebate funded retrofits

208,110

Waterwise rebate claims to August 2008: 242,210 applications less 0.99% duplicate addresses+ 2457 separate rebates for plumbed in tanks. Reduced by GIS mapping methods to include only applications inside SEQ

Housing constructions (2007-June 2008)

28,295

Sum of housing construction data from Queensland Regional Statistical Information System. Some houses may not have tanks if DA submitted prior to Jan 2007

Total

313,382 36.7% of all houses

Total detached and strip home dwellings in 2006 Census (854,098} plus new constructions (28,295} = 882,393 houses in mid 2008 (includes houses, town houses, with roof spaces, excludes apartments and caravans, etc)

contribution to future water security of both the mandated tanks on new homes and voluntarily retrofitted tanks depends on a number of factors that are difficult to predict. Whi le modelling and real time measurements of domestic tanks can provide some estimates of the useful water that can be provided by a domestic tank, these predictions must be assessed against decisions at the household level. The management of internal connections, pumps, back-up switching devices and the tanks themselves are not common knowledge for urban residents and a lack of confidence by householders may mean tank water is not optimally used. This research attempts to go beyond the physical installation and use of rainwater tanks to consider the way tan ks are understood and val ued by

One third of mandated tanks owners do not value them.

householders. It is based on both inferential and descriptive social research to evaluate attitudes, knowledge and behaviour of householders in using and maintaining their tanks. The more difficult question is how tanks will continue to be used and valued in the future . This paper will suggest some basis to evaluate this issue by identifying some of the reasons why households may or may not achieve optimal levels of water use efficiency from their tanks, and the likelihood that tanks will continue to provide useful water for households.

Sampling and Methodology Domestic rainwater tanks have been installed in Queensland households under a number of different circumstances: â&#x20AC;˘ as an means of providing water where mains supply is not available in periurban and rural areas â&#x20AC;˘ voluntary inclusions in a new house prior to January 2007 or as a retrofit to an existing house. Over 200,000 rebates were provided by the Home

water FEBRUARY 2009 15 1

water supply

~ refereed paper

and Garden Waterwise rebate scheme from July 2006 to August 2008 in SEQ.

Tank ownership

• to meet the Queensland Development Code MP 4.2 conditions that requi re detached homes in SEQ (where the development approval was applied for after January 2007) to generate 70 kl of water savi ngs per year • in some estates where tanks were mandated, either as council-enforced master plans (eg Pi mpama Coomera) or under covenants established by some developers (eg Jacobs Ridge). Figure 1 summarises these ownership circumstances . These categories were used to structure the research process. Two telephone surveys were designed and sub-contracted to market research companies. The first survey, in June 2007, targeted a sample of 200 tank owners each from peri-u rban (non-mai ns supplied), rebate subsidised retrofits and residents of estates within the Pimpama Coomera area w here tanks were a development condition. The results were reported in Water, February 2008. (Gardiner, Skoien Gardner, 2008) The major concl usions of the first survey were that t he motivations and behaviour of these three categories were quite different. The peri-urban category were completely reliant on t heir tanks and were reasonably competent in their management. Retrofitters were mainly concerned w ith the needs of their gardens. Residents with mandated tanks were generally a younger cohort and, while receptive of t he need for water saving, were frequent ly lacking in knowledge. There was a c lear need for management strategies to address the effective use and maintenance of the tanks and to promote p lumbin g connections for internal household uses. The second survey, in June 2008 considered only urban t anks and targeted: 200 owners of retrofitted tanks, as well as 171 homes constructed between April and August 2007 in Redlands, Sunshine Coast and Ipswich where tanks connected to toilets and laundry were a condition of their development approval, and 80 residents selected from fou r estates w here tanks were required but internal plumbing was optional at the time ( Sunnybank Grove, Sanctuary Pocket, The Peninsula, North Ridge Deception Bay). All these residents of detached houses with tanks were asked about their

152 FEBRUARY 2009 water

Voluntary

Peri-urban or rural

Retrofitted to urban homes

Mandated

Development covenants

Pre-existing in home

Houses approved after Jan 2007

Figure 1. Categories of tank installation. attitudes to tanks and regional water security, t heir maintenance practices and their uses of the water coll ected. Comparisons were done between the behaviou rs and expectations of each ownership circumstance and factor analysis was used to group related attitudes and behaviours amongst t he second telephone survey respondents. The results presented here typically have a sampli ng variation of +4%. Analysis by target group (200 respondents) provides a maximum sampling variat ion of +7% although variation for t he smaller sample (80 homes in estates with required tanks not internally connected) is ± 11 %, both at a 95% confidence level.

Results Overall attitudes Rainwater tanks are generally highly valued in the community for both t he personal benefits and as a contribution to communal water supply regardless of the reasons for having a tank. Three q uarters of people believe that t anks cont ribute to significant mains water savings and nearly all expect to co ntinue to use their tanks as much as they do now when water restrictions are eased. There were no sig nificant differences across the segments. Nearly all believed that tanks would st ill be needed when there is more water in the dams and that all new houses should have a tank although 16% expressed concern t hat the expense for new home buyers is unnecessary. Responses were generally sti ll in favour of tanks when t heir own specific circumstances were questioned, although not quite so universally. Most said that they would install another tank if they moved house and three quarters agreed that they would pay more for a house fitted with a tank.

Knowledge and confidence to maintain tanks Although 95% agreed that they are confident in managing their tank, on ly half were concerned with the health risks

if tanks were not managed correctly. The most commonly performed maintenance task is clearing the filters and gutters, and half of tank owners do t his on at least a monthly basis. Half of tank owners reported t hat they never inspect inside their tanks. Few tanks installed in new houses have been modified or had problems fixed by their owners. One third of tank owners, however, have called t radesmen to fix problems. The rate of problems is the same for retrofitted tanks but those owners are more likely to have themselves fixed g uttering or pipe leaks. Pumps and safety devices were most commonly installed as part of a package but maintenance information provided was sketchy or non-existent. Rebate recipients expressed the view that they wou ld like more information about tanks and that the information they have received is mainly from tan k retailers.

Some surprises • Of the 171 residents of homes built w ith development approvals requiring internally con nected rainwater tanks, all had tanks but 10% were not connected for any internal end uses. • Over 1 in 5 owners of tanks in newly constructed homes report often drinking or cooking with their tan k water. • There is a high turnover of houses with rainwater tanks. Of the peri-urban areas (without mains water) targeted in the f irst stage 42% of residents reported their main tank was installed before they bought the property. 37% of the households contacted in estates bui lt w ithin the last five years had purchased their home with an existing rainwater tank. • Nearly half of early Waterwise tank rebate recipients (the 'retrofitters) are over 60 years of age. • Many tank owners have no strategies for knowi ng how ful l their tanks are. A

technical features

~ refereed paper

number of owners of tanks installed under development legislation, responded to an interview question about how closely they monitor tank volumes with a request for instructions on how to do it. In contrast 80% of retrofitted tank owners were able to describe the method they used.

water supply

D AIi

• Three quarters New home with Internal

• The proportion of roof area connected to tanks is not much different where the tanks were req uired under development legislation as compared to those voluntarily retrofitted (see Figure 2).

Voluntarily installed urban retrofits Tanks fitted to urban houses under rebate subsidies are primarily used for garden watering and outdoor cleaning. The owners typically quote their motivations for installing a tank as 'to save the garden' and 'to save water'.

< half

c Small portion

""'

Figure 2. What proportion of your roof area is water collected from? Particularly for the early rebate recipients, motivations are related to personal outcomes. Only 5% of 200 respondents referred to commun ity responsibility because of drought and limited mains water supplies as relevant to their decision to install a tank. More common motivations were to achieve independence from water use restrictions, to get the rebate and to top up the pool. Many of the retrofitters, while expressing concern for the greater environmental benefits, are motivated by the desire to maintain the lifestyle benefits of a pool and a garden , despite water restrictions.

For material, instrumentation, automation, valves, pipes and fittings. GF Piping Systems is the right partner for all of your water treatment applications. Desalination Waste water Potable water Water utilities Irrigation Aquatic

""'

Solutions for the complete water cycle

• • • • • •

o Half C

Re trotltten

• Tank owners o utside mains supply areas do not necessarily have any more experience in managing tanks than urban tank owners. Fewer than 10% of the tan k owners in Maleny, Beaudesert an d Tamborine Mountain are local to the area.

use

Three quarters strongly agree with the statement that the water is their own private resou rce and that they like the feeling of independence it gives them. These people would greatly resent any regu lation of their tank water. The Queensland government passed legislation (Water and Other Legislation Amendment Bill 2007) in November 2007 establishing the principle that no levies or charges would be placed on the rainwater collected by households. However anecdotal information suggests that a number of tank inst allers did not apply for rebates because there was a fear t hat their tank would be subject to

[]i]

water supply subsequent regulation and the contact details would facilitate unwanted approaches from authorities. A tank installer (not a retailer) consulted by a research colleague advised him not to apply for a rebate for this very reason. When rebate recipients were asked about their intentions for their tank's water as compared to their actual use patterns, there was little difference. Only one third of tanks are ever used to water lawns and half are used for car washing. The most common uses of the water are for ornamental and vegetable gardens and wateri ng pot plants (see Figure 3). None of the 200 owners reported that their tank had ever run out of wat er.

Mandated tanks not internally connected Despite the fact that this sample was derived from estates where tanks were a development condition, nearly half of the group identified their tank as being at least partly their own choice to install. Interpreting this is difficult as the formality of the arrangement varies from cove nants to more formal local authority development requirements in the Pimpama/Coomera area. While not necessarily mandated, purchasers of homes with existing tanks have not necessarily chosen to have a tank. When this group was compared to the vo luntary installers, their attitudes and water use patterns were not very different to the attitudes of the retrofitters. This on ly statistically significant differences in management practices as compared to vol untary tank installers are: • fewer owners know how much water is in their tanks and are less likely to use water to create space in the tank when rain is predicted • a smaller number consume their tank water (4%) compared to any other category • twice as many (25%) use their tank water for outdoor cleaning, although half never do so

Mandated tanks with required internal connections Residents with tanks that have been requi red to have internal connections are the least aware of the state of their tanks. The group includes the highest proportion of younger people with 43% under 40 and the fewest number of people w ith previous experience with tan ks. Most of their tanks were installed by a builder and few have modified the

154 FEBRUARY 2009 water

refereed paper

Water gardens Water pot plants

r_-_-_-_-_---~-~t;_-~_-_-_-_-_-_...·.·;..Ji/,rlllL-!I_-_-..:":!,_-_-j .

Water fruit trees/ vegie garden Wash car Drink/ cook 1--...,.,--......,....-----.....,..,..--------1 Water for animals

J-___;_;__- - -..::.....JL--_ _ _....::..:._

_ _ ___1111111

Pool top up Outdoor cleaning Water lawns

-F~::!!!!~~!!!!!!!!~~~==:;=~~::::::;:==d 0

100

% D Oft en • Sometimes D Rarely D Never II N/A

Figure 3. End uses of retrofitted tank water. collected. One third of the new households with internal connections complained about pump noise. Other ownership cat egories had fewer noise complaints presumably because their tanks are further from the house and, not having internal connections, are less likely to have the pump running as frequently.

inst allation in any way. Although still a small minority, they were the group most likely to answer "don't know' to questions of their tanks connections and fittings, and this was most apparent in questions about safety devices. Nearly 80% reported that their tank was primarily installed because it was a development condition and on ly 12% claimed to have exercised their own choice in instal ling a tank.

The water use patterns for this group are strikingly different from the voluntarily retrofitted or the owners of mandated tanks without internal connections (see Figure 4). Few chose the 'often' response for any of the end uses listed on the survey, however watering lawns was quoted more often as is to be expected for their establishment around new homes. The top two responses were garden watering and pot plants, as for the retrofitters. The general picture is, however, that the water is simply used

The confidence of householders with internally connected tanks to maintain and manage their tanks is significantly less than other categories with one third expressing no confidence in their knowledge and ability. Most are positive about the contribution that their tank makes to domestic water supply yet approximately 1 in 5 are dissatisfied with the system (pump and/or switching device) or the quality of the water Water gardens Wa ter pot plants Water fruit trees/ vegie garden

t~:::J••••c=~~:r===::::!~==]

Wash car Drink/ cook J-___;_:_ ___.:..i...__ _ _ ___:_-=--_

_ _ ___.

Water for animals Pool top up Outdoor c leaning Water lawns

100

% D Often • Sometimes D Rarely D Never • N/A

Figure 4. uses of water from tanks with internal connections.

technical features

~ refereed paper

water supply

less frequently for discretionary purposes.

mandated tanks form the vast majority of the Not Really Interested.

Attitudinal clusters

The 'Not Really Interested' represent nearly a third of tank owners surveyed and are generally much younger. Their tanks were typically installed by a builder as a part of the process of building their home or were in a home they subsequently purchased. This group lacks interest in learning about how to maintain their tanks and have extremely low rates of cleaning gutters and leaf screens. Many of this group have tanks connected to laundry and toilets with an automatic valve switching to mains if the tank runs 'dry'. Only a very few of these tanks have trickle top up systems or manual overrides. While agreeing that tanks are important for commu nal water supply they are less likely to believe that tanks wi ll be needed when the dams reach capacity.

While tanks are valued across all the ownership categories, the reasons why are not necessari ly linked to the reasons why a household came to have a tank in the first place. Factor analysis was conducted using responses to questions across a range of themes including attitudinal and behavioural questions about tanks spec ifically, as well as broader environmental position ing and expectations about the long term need for domestic rainwater collection. Figure 5 shows t he resulting attitudinal clusters. These attitudinal typographies had a stronger correlation with some of the use patterns for tank water than the acquisition status. For instance ' Environ mentalists' are the most likely to drink their tank water (34%) and the Compensators are nearly all gardenfocused but also use more tank water for other uses such as outdoor cleaning, car washing and growing fruit and vegetables. Wh ile the retrofitters appear across both the Environmentalist and the Compensating groupings, the owners of

Conclusions While nearly all tank owners rated tanks as an important and effective contribution to long term water security their response to questions on their personal motivation highlight some concerns. Environmentally motivated tank owners have broad

communal and long term motivations are the most likely to incorporate rainwater tanks into their household management. Voluntari ly installed tanks are primarily used to replace outdoor water usages where mains water for garden irrigation is restricted through regulation. However, it is unlikely the owners will cease using the tanks when restrictions are removed. These owners enjoy the independence of their tanks and are interested in learning to use and maintain them. Householders with mandatory, but non-internally plumbed tanks, also have a personal engagement with their tanks that is missing amongst the home owners with internally connected tanks, despite the similar you nger demographic. The major correlation with both the belief that tanks are a temporary response to drought, and the absence of a pattern of discretionary water use, is the presence of a required internal connection, not the fact that the tank itself was mandated or was previously installed in a purchased home. This suggests that the subsequent sale of houses with retrofitted tanks is not likely to cause additional problems; but that there is a possibility that internally

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water supply

• •

•

[j]

More likely to install tank if mo ved house Proud of tank Careful with how water is used Environmentally aware (avoid plastic shopping bags, recycle, compost) Believe water use restrictions will be needed in long term, Pro-legislation Greater incidence amongst Retrofitters Lived in house > IO years

• •

•

Proud of tank More likely to install tank if moved house Higher levels of concern about health r isks from tank water Less careful with wate r use Feel that water bills are lower because of tank Tank allows water use as if no restrictions Tank gives feeling of independence Tank water is own private resource Tank water lets me have garden the way I like it Against legislation for use of tank water

• •

Stronger amongst Retrofitters Aged 50+

•

Tank most likely s ituated > 3 metres from house More likely to have tank > 5,000 litres See no point in using tank water fo r internal purposes

• • • •

Tank most likely located approx. I metre from house

•

• • •

Would not install a tank if moved house Not confident in managing tank Would not pay more for a house fitted with a tank Not strong recyclers/ do not compost Do not see need for long term water restrictions No perceived need for tanks when dams are full

refereed p a p er

• •

Rarely cleans or inspects tank •

Mandated with internal connections Aged under 40 years Lived in house < 3 years Tank most likely to be s ituated close to house

Figure 5. Attitudinal clusters amongst tank owners. connected tanks will not be maintained in the long term. Nearly one third of tanks owners do not value their own tanks highly. In practice this means that these owners are not learning how to manage and maintain their tanks and may be more likely to stop using their tank if problems arise as opposed to investing time and resources in maintenance. Most of this attitudinal group have mandated tanks with internal connections and treat these tanks as a part of the standard household plumbing. Consequently owners are less likely to regard t he water as a personal resource. While the rate of technical problems is simi lar, this group is most likely to call a plumber to undertake repairs or modifications that vol untary owners carry out themselves. Educational materials for tank maintenance are needed across all tank acquisition categories. Few tank owners have substantial experience with tank maintenance even in semi-rural areas. As the previous paper reported, peri-urban residents are highly concerned about water quality and quantity, however the high rates of immigration into peri-urban areas indicates a need for educational

156 FEBRUARY 2009 water

materials across the board. The least interested are the owners of mandated tanks with internal connections although these tanks are the most likely to have safety devices fitted, such as first flush devices and leaf screens. For all ownersh ip categories the safety devices present are typically only those connected by the tank installer. Urban retrofitters are very receptive in issues to do with their tanks and very confident in their ability to manage their tanks. It will be harder to influence the new home owners.

Acknowledgments This research was conducted within the Natural Resources Sciences division in the Queensland Department of Natural Resources and Water. The author wishes to thank the Redlands, Sunshine Coast and Ipswich Councils for providing a list of houses constructed after the beginning of 2007, and the Qld Department of Natural Resources and Water 'Home and Garden Waterwise Rebate Scheme' for their data set of applicants. A special thank you to Gabrielle van Willigen for sorting through these data sets to extract sample sets for the telephone survey. The telephone

surveys were conducted by Footprints Market Research.

The Author

Dr Anne Gardiner (email: anne.gardiner @nrw.qld.gov.au) is a Senior Project Officer with the Queensland Department of Natural Resources and Water.

References Gardiner A, Skoien P, Gardner T (2008) Decentralised water supplies. South East Queensland householders' experience and attitudes. Water 35 No 1., February Queensland Development Code MP4.2 (previously part 25) Water Savings Targets, Queensland Department of Infrastructure and Planning http://www.dip.qld.gov.au/docs/temp/mp4_2 _water_savi ngs_targets. pdf Water and Other Legislation Amendment Bill 2007, Clause 398A, No charge for nonAct water in rainwater tanks, http://www.legislation.qld.gov.au/Bills/52 PDF/2007/WAOLAB0?.pdf

technical features

wastewater treatment

~ refereed paper

BIOCHEMICAL OXYGEN DEMAND (BOD) - FACT OR FICTION? K Brian Abstract Biochemical Oxygen Demand or BOD is one of the most widely used analytical tests used to assess the strength of wastewater. Most wastewater discharge consents in New Zealand, whether they are to land or to water, are likely to contain a limit for five day BOD (BOD5 ) either as an average, percentile or maximum value. The design of wastewater processes such as pond systems, trickling fi lters and act ivated sludge plants is often undertaken using the BOD of influent wastewater to size aeration equipment, reactor volumes, pond surface areas and media req uirements.

What is its relevance to

sizing treatment plants and assessing the impacts of wastewater discharges on the receiving environment.

design of a WWTP?

Introduction

Given that BOD is such a widely used parameter in the industry, what does it measure, what interferences are there in the test and what are the fundamental biological processes behind it? What does BOD actually tell the regulator or designer about a particular wastewater or discharge and are there any alternatives that can be used?

The Biochemical Oxygen Demand or BOD test was developed in Britai n shortly after the turn of the twentieth century. The idea of t he analysis was that in polluted water there is an oxygen demand caused by microorganisms and this was used to measure the extent of pollution.

This paper discusses the origins of the BOD test, what the test actually measures, the kinetics of the test and suggests some reasons why BOD is not always the most appropriate means for

The five day test duration was based on the assumption that most major surface waters in the United Kingdom take five days or less to reach the sea; hence the extent of pollution in these

., ., C, ~

,,("'

~ 8

8 88

.. "

8 9

<1'9tJ

.,..

. fl

~ refereed paper

wastewater treatment water bodies could be quantified. The test was developed to run at a temperature of 65°F (about 18°C) but has now been "standardised" to 20°c. Since its inception, the test has been modified by different countries to more accurately represent local conditions. For example, in France it is common practice to obtain both a five day BOD and a 21 day BOD and in Scandinavia the standard BOD duration is 7 days. In New Zealand, we have adopted the British standard and the majority of the tests conducted here are over a five day duration. In its original form the BOD test could measure oxygen consumption of carbonaceous compounds only or a combination of these and the oxygen used to convert ammonium to nitrate. It has become reasonably common practice today to define if the test was used to measure conversion of ammonium by defining either BOD5 or cBOD5 (c referring to carbonaceous or nitrification inhibited tests).

The Test The standard method for the BOD analysis is described in "Standard Methods for the Examination of Water and Wastewater, APHA, AWWA, WEF" and an overview is given below. The test sample is mixed with pure aerated water and placed in a bottle such that there is no air above the liquid. The bottle is then placed in a temperature controlled environment at 20°c. The test must be conducted in the dark such that no algal or other photosynthetic activity can contaminate the test by adding oxygen over time. The dissolved oxygen concentration at the start and end of the five day period is measured, and the initial dilution used to back calculate the oxygen demand of the original sample. The consumption of the dissolved oxygen in the sample must not be more than the theoretical saturation concentration (9.07mg/L at 20°C) and should be conducted such that there is a residual dissolved oxygen concentration at the end of the test of at least 2.0 mg/L. Oxygen levels below this may inhibit the test and are likely to produce invalid data. Given that the dissolved oxygen range of the test is quite small, strong samples must be diluted to ensure that the resultant DO difference is not greater than the theoretical maximum of 7 mg/L. In a "standard" 300ml BOD bottle the maximum BOD mass that can be tested without dilution is 2.1 mg or 7mg BOD/L.

158 FEBRUARY 2009 water

In New Zealand the BOD of typical domestic strength wastewater (untreated) is usually in the range of 200-300mg/L. Hence a dilution of about 50 times (6ml of sample to 294ml of water) is required such that the DO range is not exceeded. If nitrification is not inhibited (by the addition of allythiourea (ATU)) then the dilution is likely to be larger such that there could be a significant oxygen demand for conversion of ammonium to nitrate. As the BOD test relies on an oxygen demand by microorganisms, the test will not provide valid data if there is not a viable inoculum of organisms present in the sample. In raw untreated wastes this may not be an issue as there are often organisms present. In sterile wastewater, final effluent, and membrane filtered samples there are unlikely to be enough organisms present for the test to be valid. The Standard Method for BOD therefore includes the requirement of adding a "seed" of organisms to the test bottle. Generally this seed is obtained from the mixed liquor of an activated sludge plant, but in the case of industrial wastewater an acclimatised seed is needed. Standard Methods states that the oxygen demand of the seed should not be more than 0.6-1.0mgOiL over five days. Given that this is the case the minimum error associated with such a seed on the above example of typical raw domestic wastewater would be in the range of 30-50mg BOD/ L. As discussed above, the BOD can be tested with or without nitrification inhibitor. In New Zealand the standard nitrification inhibitor is allythiourea (ATU). This is added to the test bottle to inhibit the growth of nitrifying organisms that convert ammonium to nitrate. These organisms are not likely to be present in significant numbers in a raw wastewater sample, however if a seed is taken from the mixed liquor of an activated sludge process, then there is a much higher chance of nitrifiers being present. The addition of a nitrification inhibitor can also affect the respiration rate of some of the organisms that oxidise carbonaceous compounds. If this occurs then the results of the test are likely to be invalid as the total mass of oxygen used in such a test would be red uced if this were to occur.

Kinetics of the BOD Test As discussed above the BOD test measures the oxygen consumption of a water or wastewater sample over time and this is then used to quantify the

strength of the sample. The growth of microorganisms in the test can be described by typical chemical rate kinetics and these are described below. The rate of "BOD" oxidation can be described based on the assumption that the amount of organic material remain ing at time t is a first order function:

dBOD = -kBODr dt Integrating this equation from time t = 0 to t = t yields:

BODt = BODu(l - e-ki ) Where BODt = BOD at time t (typically 5 days) k

= reaction rate constant (d- 1)

BODu = ultimate BOD concentration (mg/L) The BOD ultimate value is the BOD that would be exerted at infinite time (about 100 days plus). Obviously th is is difficult and time consuming to measure, and is usually found by constructing a curve of BOD versus time as shown in Figure 1. This curve can also be used to find the reaction constant k that is required to fully describe the kinetics of the test. The rate constant fitted to the above set of data in this case was 0.26 days· 1 . From this curve it should be possible to determine the oxygen demand of this particular sample at any point in time. For example, if this wastewater was discharged to a river catchment that had a long transit time from the discharge to the point where the effect of the discharge was critical, (for example 10 days) the oxygen demand on the receiving water wou ld be 260mg/L. For the BOD test to be valid, all other tests with an ultimate BOD of 278mg/L (as in Figure 1) should contain the same amount of substrate (here assumed to only be carbon) such that the ultimate strength of the carbonaceous matter in each sample is the same. Figure 2 shows a plot of three BOD curves all with the same ultimate BOD, but having different rate constants (k). As shown the oxygen demand of the sample follows a very different curve for each of the three cases and t he oxygen demand at different points is quite different for each sample until the sample time is longer than 25 days. The BOD 5 of each of these is summarised in Table 1.

technical features

wastewater treatment

~ refereed paper

they would be in the environment or in an activated sludge process. These maintenance processes consume oxygen, hence the requirement by standard methods that the seed consume no more than 1 mg/L of DO for the duration of the test. As the sample is degraded, the organisms in the seed wi ll undergo a oxygen consuming decay process and t hose organisms grown during the test will also decay producing an additional oxygen demand that is not related to the original carbon content of the sample. The oxygen demand for decay of the seed can be described as shown below:

300

250

200 BODI• 278"( 1-e -(/.:«)

:r th

.S.

150

Ill

100

Time (days)

dO = -b(I - f)Xh integrating from t = 0 to t = t di

Figure 1. Plot of BOD versus time.

BOD=(l - f)Xh,. 0 (1 -e- 61 ) dO

Where -

:r th

= change m oxygen with lime

-b

= decay constant

.S. 150

heterotrophic (carbon utilising) organ isms

= fraction oforganisms that is inert residue

Ill

100

Time (d1ys)

[- k •0.1 -

k•0.15 -

k• 0.3 [

Figure 2. BOD versus time for different rate constants k. The range of BOD5 values from Table 1 is 109mg/L to 216mg/L, yet the samples are the same ultimate strength given that the ultimate BOD is the same in each case? Does this result mean that an activated sludge t ype process would req uire 50% more or less aeration for wastewater that h as been assumed to have the same total amount of carbon? Is t he effect on a waterway from this discharge going to be the same at every point given that a l I three wastes contai n the same amount of carbon based pollutant s? The above example illustrates that the BOD test does not tell the designer or

Table 1. BOD5 of Example BOD tests. Rate constant (k) Ultimate BOD (mg/L) 80D 5

0.1 0.15 0.3

278 278 278

109 147

216

regulator anything about the rate of degradability of the waste or its ultimate strength. This may mean that environmental effects or design of aeration equipment etc are over or under estimat ed. This is of particular importance to regulators as the rate of degradation of a waste will have an affect on how far downstream an environmental effect may be noticed and how quickly an oxygen deficit cou ld occur in the environment.

Oxygen Consumption for Decay The fundamentals of the BOD test as discussed above are to measure the oxygen consumed by microorganisms in a water or wastewat er sample over time. Th is consumption of oxygen is usually a result of the growth of organisms on the carbon and oxygen in the sample. The organisms that do this are also subject to the same competition, decay and predation (maintenance) processes that

This equat ion is based upon the initial concentration of organisms in the test being quantified. If the seed is taken from an activated sludge process it is very difficult to quantify t he number of organisms present and even more difficult in the actual test (with dilution). Figure 3 shows a plot of t he BOD exerted by the seed organisms in a simulated BOD test at 50 times dilution with initial active organism concentrations of 1, 2 and 3mgCOD/L respectively. Figure 3 shows that for a typical raw domestic wastewater sample (BOD of about 300mg/L) the seed organisms could add a BOD to the sample of between 30 and 85 mgBOD/L over five days that is totally unrelated to the strength of the sample being t est ed and would have no relevance to the oxygen demand in the environment or in a wastewater treatment process. Note that the above example does not include the additional oxygen demand from the decay of organisms grown in the test which wou ld add further demand.

Organism Yield Heterotrophic organisms in an aerobic environment use organic carbon compounds for both energy and growth. The substrate used as an energy source is given off as CO2 wh ile the carbon used for growth increases the cell mass and number of organisms present. As discussed above new organisms grown

water FEBRUARY 2009 159

wastewater treatment

~ refereed paper

on organic carbon undergo decay and maintenance processes and this also gives off CO2 . The ratio of the mass of carbon that is used for growth versus that used for energy is called the organism yield. In most circumstances this ratio is less than one unless a large amount of intracellular storage is occurring (for example in biological phosphorus removal processes). For the BOD test the organism yield is critical as only the carbon used as an energy source will exert a BOD. The rest wi ll be used to grow new organisms. The rate of decay and subsequent use of oxygen is usually very much slower than that for growth, hence over five days, all of t he carbon that is " lost" to cellular growth will not be measured in the test. For typical domestic/municipal wastewater without significant industrial input the yield ratio is about 0.67kg/kg, however many substances such as methanol, acetic acid and complex compo unds that may be found in industrial wastewater have yields that are very different from this val ue. For example under aerobic conditions the yield of acetate is about 0.4kg/kg. Figure 4 shows a plot of the simulated BOD for a "test" where the total Chemical Oxygen Demand (COD) of the wastewater sample is 500mg/L with acetate and "normal" COD from wastewater. Note that both simulated tests assume 100% readily degradable substrate and the same seed concentration of organisms. This makes mass balances using BOD impossible as it is impossible to tell how much carbon was used for each process. The above example illustrates the potential error in the BOD test from one group of organisms with varying yield on different substrates. It should also be noted that yield can be different between different organism groups as well as bet ween substrates. This is not likely to be a major problem for municipal wastewater but it can be a major issue in industries such as pulp and paper where the type of substrate and possibly the type of organisms using this substrate can vary with time.

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Figure 4. BOD versus time different organism yield. industrial wastewater or the sample contai ns compounds that are degraded by a specialist group of organisms. In this case the BOD measurement co uld be completely false as the seed may take a significant amount of the five days of the test to acclimatise or to reach sufficient numbers to utilise the substrate.

Other Sources of Error

Acclimatisation of Seed

The determination of the BOD in a test sample of water or wastewater assumes that the oxygen consumed during the test period was the result of a source of pollution (e.g. sewage). In some wastewater treatment systems there can be instances where the treatment system itself contributes to the oxygen demand.

The above simulated BOD tests all assume that the organisms used as a seed are acclimatised to the substrate being tested. This wi ll most likely always be the case where the sample and seed come from the same plant, but is very unlikely if a standard seed is used for an

Pond systems are a very common method of treating wastewater in New Zealand and these rely on the settlement of organics and the action of algae to promote oxygenation of wastewater. The algae use CO2 from the atmosphere, with sunlight, to produce oxygen and new

160 FEBRUARY 2009 water

Time (days)

cellular material. New algae cel ls contain carbonaceous compounds that will exert a BOD once released from the cel l during decay or predation. This oxygen demand may be measured in the effluent to a pond system, however the carbon that is utilised during the BOD test would have been fixed from atmospheric (dissolved) CO2 and would have nothin g whatsoever to do with the strength of the waste that the pond was treating. Using effluent BOD data from a pond therefore to quantify the performance of a pond system may not be val id if the measured oxygen demand did not originate from the influent wast ewater. This would be a large issue in summer where the population of algae cells is higher than in the winter.

Process Mass Balances for Design Biochemical oxygen demand is very widely used not only in the regulation and operation of treatment plants, but also in

technical features

wastewater treatment

~ refereed paper

their design. Sizing of aeration basins, sludge processing facilities and aeration systems are undertaken using BOD data. The design fu nd amentals for process design with BOD are typically based on empirical values or loading rates such as: • Areal loading rates of pond systems (old Ministry of Works design guideline of 84kgBOD/ ha/day) • Trickling fi lter media loading rates (kgBOD/ m3 of media)

users expect to see rather than this actually being used in the models themselves. Designers need t o be aware of the limitations of the BOD test when undertaking design and the implications it has for over or underestimating the amount of capital expenditure (concrete and mechanical equipment) that is needed to treat a particular wastewater.

Conclusions

• Activated sludge processes (food to microorganism ratio (F to M) kgBOD/ kgMLVSS.d) • Sludge production from an activated sludge process (kgTSS/ kgBO D .d) These loading rates are usually based on long term operational data where the influent BOD concentration has been correlated t o the plant performance. The empirical approach does not provide any information on how the process is actually worki ng, how sludge production changes with time or the kinetics of the processes involved in treating the waste. These issues may not be important from an operational point of view provided the empirical data can be used to optimise and run the plant properly. In complex systems such as nitrogen removal and biological phosphorus removal, and the digestion of biosolids, the empirical approach is limited as the designer knows nothing about rates of reaction, affinity to different substrates and s ludge production, all of which are needed to size and manage these complex systems more efficiently and effectively. Biochemical Oxygen Demand data has limited value in the design of com plex systems as mass balances cannot be closed using this data. As discussed above, the "strength" of the wastewater measured by the BOD t est does not actually relate to the total amount of carbon in the waste, therefore sludge production can not be properly quantified and therefore prediction of mixed liquor and sludge quantities cannot be predicted without empirical relationships such as those outlined above. Processes such as biological phosphorus removal cannot be designed on a BOD basis as the carbon can not be properly traced throughout the system.

The BOD test is the probably the most common ly used test in the wastewater industry for measuring the strength of wastewater. It was developed as an empirical measure to determine the oxygen depleting potential of water or wastewater, but does not measure the carbon content of the wastewater that is critical in the design of complex wastewater treatment systems. The five day duration of the test is not always the best indicator of the polluting effect of a discharge and is based upon the history of the test rather than any fundamental scientific principle. Many other countries use a different time basis for the BOD test to better reflect local conditions and this may be necessary in some cases in New Zealand. Wastewater plant regu lators, operators and designers should all be aware of what the BOD test actually is and take it limitations and advantages into account when using BOD based data.

The Author

Kevan Brian is Lead Process Engineer in AWT New Zealand in projects ranging from 200 PE to 250,000 PE. He leads AWTs team of nine specialist process engineers/ scientists and is responsible for running the process laboratory. Email: Kevan.brian@awtwater.com.

Possibly the most significant design issue related to BOD is the sizing of aeration equipment. As the BOD test includes endogenous respiration (see above) double accounting of the Bibliography oxygen needed f or this and carbon oxidation will occur as the Metcalf and Eddy, Wastewater Engineering, Treatment and Reuse, designer has no way of telling how much BOD was related to Mc Graw Hill, 2003. the sample, how much was endogenous activity and how much Standard Methods for the Examination of Water and Wastewater, of the oxygen demand is related to the specific yield of the 21st Edition, APHA, AWWA, WEF, 2005. substrate being treated. This is particularly difficult in a nitrogen Henze, M; Harremoes, P; la Gour Jansen, J and Arivin, E, Wastewater removal process where nitrate essentially replaces oxygen for Treatment, Biological and Chemical Processes, Springer, 1991. the electron transfer process. If cell ular yield is not included in this .. .__ . - ... analysis, aeration equipment wi ll be NOW WE SPEAK YOUR LANGUAGE! oversized and may operate very 2~~~b~:ds Our ftirl)l(fity & Cu11duct1v1ty SPllSlH~ c,111 now I.ilk lo your SDI 12 loqqrrs llubid ity $. conduchv ity se n sor~ inefficiently.

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The above issues are the primary reason why activated sludge models (ASM models) do not use BOD at all in the ir calculations or model structure. Mass balances over a process are not possible with BOD and therefore the process simulation models cannot be designed around this parameter. Most models use or back calculate BOD as this is what

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water FEBRUARY 2009 161

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LOGANHOLME WPCC SWITCHBOARD UPGRADE L Bichard, D Maguire Abstract Logan Water upgraded the main switchboard and motor control centre (MCC) at the Loganholme water pollution control centre (WPCC) in November 2007, following deterioration and plant upgrades.

Background The Loganholme WPCC serves approximately 170,000 people in Logan City, which is located 30 minutes d rive south of the Brisbane central business district. The upgrade is part of Logan Water's commitment to providing high standards of reliability and operabi lity for its customers. The Loganho lme WPCC experienced the failure of Energex 11 kV f uses to the plant in November and December 2004. Parsons Brinckerhoff (PB) was engaged to undertake a load study of the installation and a condition audit of the switchboard and MCC in July and November 2005 respectively. The replacement of the existing switchboards was recommended for the following reasons: â&#x20AC;˘ The loading of the Motor Control Centre (MCC) needed to be reorganised as it was now powered by two transformers with a less-thanoptimal feeding arrangement. â&#x20AC;˘ The swit chboards had deteriorated because of their age and the environmental co nditions in which they were located. PB subsequently produced the scope and technical specifications for the replacement of the switchboard and MCC. New MCCs were recommended to be housed in an airconditioned transportable switchroom. The new MCCs were temporarily connected to the same supply transformer as the existing MCC, allowing for easy changeover of the field equipment to the new MCCs. Following a tendering process, J&P Richardson constructed and installed a new MCC, variable speed drive (VSD) starter enclosures, a transportable

162 FEBRUARY 2009

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Photo 1. New switchroom. switchroom, and a self- contained generator.

Existing Installation The existing switchboards were located within the plant inlet works building where they were subject to the effects of hydrogen sulfide (H 2S) gases and high humidity. These effects were regularly compounded during times when the wet-well covers, adjacent to the switchboards, were opened for cleaning and replacement of the primary screens. While this arrangement was typical for facilities installed at the time, it is not considered best practice by today's standards. Several smaller grade 316 stainless-steel cont rol cabinets located in the bui lding had also been affected by H2 S gas and humidity, and were corroded. The switchboards were commissioned in 1983 and had been in service for over 25 years. Regard less of the switchboard's age, individual components housed within a switchboard need to be checked,

Replacement planning should commence after 10 - 12 years service.

maintained and, where necessary, replaced, on a yearly basis. The switchboards at this site had redundant and modified equipment panels which were the result of change in drive sizes and starter types due to several staged plant upgrades. In some cases, cables were being overheated; this was evident from the degradation of cable insulation around starter terminals. Some cables had been left unused after the removal of redundant starter equipment. Maintenance and repai rs were difficult because several components were unavail able. Although the existing MCC starters were in separate tiers, they were not entirely segregated from other starters or t iers, and shared common vents and cable and bus zones. This form of construction could be considered closest to Form 1 according to AS 3439.1.

Switchboard Construction Although considered suitable at the time of installation, the use of Form 1 or Form 2 switchboards presents a high risk to the security of the associated plant through the possible spread of fire and smoke-associated impurities that c an result in the event of a fault. Where there

technical features

~ refereed paper

wastewater treatment

is no segregation between starters or areas within a switchboard, several starters may be rendered inoperable should a fault spread.

Upgrade Strategy A new Form 3b MCC was recommended and ultimately constructed in a back-to-back configuration. The new MCC and 2 x 450-kW and 2 x 250-kW stand-alone VSD enclosures were housed in a new 16-m-long airconditioned transportable switchroom that was located outside the inlet building and away from the effects of H2 S gases and high humidity. The MCC was fitted with an Argonite fire-suppression system triggered by a Multiple Aspirated Smoke Detection System Apparatus (MASDA) system with sensing devices located in each MCC cable zone. The new switchroom (refer to Photo 1) was mounted on galvanised steel posts 1 .5 m from the ground, which allowed easy cabling to the MCC and kept it above the 1-in-1 00-year flood level. An adjoining water authority has fitted smoke detection in all switchboards and fire suppression in switchboards at remote plants. The most significant risk to the environment and operation of the plant during the change-over was the amount of downtime that wou ld be required to reconfigure the existing drives to the new MCC. To m itigate the risk of unwanted spills, the MCC and control system were configured so that the installation only req uired the disconnection of power t wice during the plant off. peak demand times. Permission was obtained from the supply authority to connect the new MCC to the same low-voltage (LV) supply transformers that powered the existing switchboard and MCC (refer to Photo 2). This resulted in a very short downtime of

Photo 2. New MCC and fire suppression.

only a few hours and allowed the plant to be recomm issioned without disruption. The new and old MCCs were then both reenergised, allowing the cables for existing equipment to be transferred to the new MCC without the need to disconnect power to other equipment that was still connected to the old switchboard. This was particularly important to ensure minimal downtime on the operational plant. A new GE Fanuc programmable logic controller (PLC) with RX3i central processing unit (CPU) was installed in the new MCC and was networked with the old GE Fanuc 90-30 PLC. This arrangement allowed the various drives to be changed over in a staged manner and recommissioned on the new PLC. The advantage was that common inputs/outputs (1/ 0), such as level switches and transmitters, could be shared by both PLCs, allowing the drives on the old and new MCCs to remain operational in automatic mode.

Fire Damage During the early stages of transferring the existing drives to the new MCC, the old MCC was extensively damaged by a fire caused by a high-impedance arcing fault in a contactor in one of the 450 kW raw-sewage pump starters (refer to Photo 3). The resultant damage caused melting of cable insulation, PVC ducts, door seals, and similar com ponents in compartme nts up to three tiers away from the origin of the fault (refer to Photo 4). The effects of the smoke damage reached further in the MCC, with smoke and carbon deposits covering starters and equipment and even the PLC tier located at the far end of the MCC. The damage meant that the existing MCC was unsafe for operation and was disconnected from power.

Recovery

Photo 3. Damage in starters at origin of arcing fault.

The contractor, J&P Richardson , responded quickly to the emergency and transferred the remaining drive cables onto the new MCC. Several drives were operated manually until they could be commissioned on the new PLC, where they then operat ed under automatic control. The manual operation of the equipment did not cause any problems to the plant process during this time.

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New Equipment The existing switchboard and MCC were not supported by a permanent backup generator. Backup power was considered desirable to improve the reliability of the plant. As a resu lt, a permanent 1.5 MVA generator was supplied and inst alled. It was housed in an acoustic container with onboard fuel for 8 hours of continuous operation (refer to Photo 5). The raw-sewage pump station was being upgraded by ABS at the same time the MCC was being installed. The upgrade incorporated replacement of one of the existing pumps with two new smaller 250 kW pumps. The new VSD starters for these pumps and the VSD st arters for the two existing 450 kW pumps were housed in the new switchroom and supplied from the new MCC.

Conclusion Strategic asset planning is an important tool in the management of the life cycle of switchboards and MCCs. It is essential that the condition of switchboards and MCCs, particularly those of mission-critical importance, are monitored regularly to detect any early signs of deterioration. Condition assessments are particularly significant as a switchboard nears the end of its design life. Usually a switchboard is built with a best-case design life of 20 to 25 years. Th e weakest part of the installation is generally the switchgear and starters,

Photo 4. Effects of heat sustained in adjacent tier. which depending on the operating conditions can approach the end of their useful life withi n 10 years. It is recommended therefore that, subject to thei r regular condition assessment, replacement planning for swit chboards should commence at a minimum in the last 2 to 3 years of their design life, and typically after 10 to 12 years of service.

The Authors

Lance Bichard is the Queensland Electrical Team Manager (email: lbichard@pb.com.au).

However, it is important to regularly inspect and maintain such plant, checking for early deterioration caused by corrosive gases, excess humidity and hot conductor joints. Dean Maguire is the National Electrical Executive for the Systems and Electrical division of Parsons Brinckerhoff's Power business unit (email: dmaguire@pb.com.au).

Water Advertising To reach the decision-makers in the water field, you should consider advertising in Water Journal, the official journal of Australian Water Association. For information on advertising rates, please contact Brian Rault at Hallmark Editions, Tel (03) 8534 5000 or email brian.rault@halledit.com.au

Photo 5. Diesel generator acoustic container. 164 FEBRUARY 2009

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~ refereed paper

FEMALE STP OPERATORS: PREGNANCY AND LACTATION ISSUES NTaylor Abstract Changes in technology, education, and automation have lead to a younger, more highly educated demographic, with an increased proportion of women, working at sewage treatment plants. The purpose of this paper is to outline the specific risks relating to pregnancy and breastfeeding (lactation) for women working at sewage treatment plants, and some practical steps that employers and employees can take to protect them (and their foetuses and babies) from harm. It also discusses some tools that Sydney Water has started to implement.

Introduction It is easy to think about workplace safety helping the people that you work with and talk to each day. It is harder to see the implications for the unborn (the foetus of a pregnant woman) and unseen (the breastfed baby of an employee), who are many times more vulnerable than adults to hazards in the work environment. The influx of women into trad itionally male dominat ed work environments, such as sewage treatment plants, has had a positive impact on many aspects of treatment plant operation, but alongside this there is the associated issue that historically there is very little data to show the impact on the foetus of pregnant women working at these sites. Risk assessment for pregnancy and breastfeeding has not generally been understood by employers, and many pregnant employees are in the dark. However, by careful early planning and application of some practical steps a pregnant worker and her baby can be kept safe While this paper deals specifically with pregnancy, and to a lesser extent breastfeeding, it is important to recognise that there are other areas of reproductive health that can be affected by workplace hazards. The fertility of both men and women can be affected by biological and c hemical agents, and this

should be addressed in the risk assessment process.

Why Know the Risks? Vulnerability of the foetus The foetus is susceptible to outside influences on the mot her, such as workplace hazards, throughout the entire pregnancy, and after birth if the mother is breastfeeding. The most critical time for a foetus is the time from when it implants into the wall of the uterus (at about 4 weeks gestation) until all the organs are formed at 10 weeks gestation. This means that in the time it may take a pregnant employee to ask for help with assessing the safety risks, the employee has passed the most critical period for foet al development. Because pregnancy usually goes undetected for the first few weeks after a conception, employers should identify hazards and risks for all female employees of childbearing age, not only those that they know are pregnant (Trades Union Congress, UK). A pregnant employee is under no obligation to tel l her employer that she is pregnant in the early months, but early notification can assist both the pregnant employee and her manager in managing the risks.

Lack of data/research Traditionally, worki ng at a sewage treatment plant has been considered to be a 'man's job', and there are probably many who still feel that way. Young female employees in these types of environments have been a relatively recent phenomenon, and in most cases they are still the minority. As a result, there isn't historical data available to conduct studies on the effects on unborn babies of women working at sewage treatment plants. While the risks to employees of working with sewage are widely known, no specific guidelines have been written on working with sewage while pregnant. Because of this uncertainty, this 'grey area' needs to be approached with care and caution.

Duty of care Your employer has a responsibility to do everything practicable to ensure your workplace is safe for you throughout your pregnancy and while you are breastfeeding (NSW Department of Commerce, 2007). Proper care of all employees is important, not only for employees, but also for the employer,so that they don't breach their responsibilities to provide a safe working environment under OHS or Sex Discrimination Legislation. Although pregnancy is not an illness, and shouldn't be considered such, there are ways in which pregnancy and breastfeeding can change the risks to a woman in a workplace. Once a woman lets her manager know that they are pregnant or breastfeeding, an employer is obliged to take the following steps: • Carry out a risk assessment on the employee's workplace. • Do all that is reasonable to remove or reduce the risks fou nd • Give the employee information on the risks and appropriate protective measures • If t he risks still remain, alter the employee's working conditions (e.g. hours of work or work location) (Source: WorkCover, 2002, p 16)

What are the Risks? The document called the Pregnancy and Work Guide (WorkCover, 2002) includes a lot of helpful information about what risks may be present in the general workplace and how to assess them. It provides an excellent starting point for considering the specific issues. There are a number of ways in which pregnancy can affect the way a woman

Practical measures to assess and control the risks. water FEBRUARY 2009 165

wastewater treatment works, and in wh ich a woman's workplace can affect her pregnancy. While a foetus is formi ng and growing, it is highly susceptible to a range of chemical, physical and biological risks from the environment that the mother is living and worki ng in. In addition, some of these risks can be transferred to a chi ld through breastfeeding after the mother has returned to work. The physical and biological changes in the mother's body during pregnancy can also put her at risk. Chemical There are a number of chemicals ranging from over the counter medications, alcohol, nicotine and household cleaners, to laboratory and process chemicals that can cause damage to a baby during pregnancy or may pass through breastmilk and harm a child. Exposure to harmful chemicals has been linked to developmental problems, lower IQs, deformities and even death in a foetus or baby. It is important for all employees, but especially for preg nant or breastfeeding women, or women planning a pregnancy, to check the material safety data sheets (MSDSs) for any chemicals that are used on site. Any chemical that mentions 'carcinogen', 'toxic' or 'birth defects' in the risk categories are of particular concern and the appropriate safety measures should be followed by all employees. Examples of chemicals onsite that may cause harm include diesel, petrol, oils and lubricants, test kits for nitrate and COD, calibration gas, spent pickle liquor (SPL), sodium hypochlorite, waterless hand cleaners, carbon monoxide, lead, and mercury. As sewage is to a certain extent unpredictable in its contents and composition, extra care should also be taken with sewage itself, and sewer gas, as they may contain harmfu l chemicals. Physical The physical conditions of the work environment can affect the health of a pregnant woman or her baby.

Noise Working for long periods in loud environments has also been shown to increase blood pressure during pregnancy which can be harmful to a baby and mother, and in the later stages of pregnancy a baby 's hearing can be permanently damaged if the mother works in a loud environment.

166 FEBRUARY 2009 water

Hearing protection doesn't help in these circumstances, so avoid working near blowers or other noisy machinery while pregnant.

Manual handling During pregnancy a hormone is released to relax the ligaments in the woman's body. This happens to help the woman's body accommodate the growing baby, and also prepares her for childbirth. It also makes a woman more prone to injury and overstretching. Changes to the shape of a pregnant woman makes it difficult to carry objects close to the body, so heavy objects cannot be lifted safely during pregnancy. Lifting can also alter the blood flow and can cause problems internally due to intra-abdominal pressures.

Heat Working in hot environments, or out in the sun on a hot day, can be a problem for any employee if they are not given adequate meal and drink breaks, and rest periods. A pregnant woman has 30 - 40% more blood than she does when she is not pregnant, putting additional strain on her heart, making it easy for a woman to faint or have heat stress. Overheating can cause problems for both mother and baby, and can impair breastfeeding if dehydration occurs.

Heights Changes in shape shift the centre of gravity in a pregnant woman, which can make some tasks more awkward to perform. It can make working on platforms or on ladders quite dangerous not only would a pregnant woman be more likely to fall , but also the consequences of falling could be more severe.

Working nightslshiftwork Studies have linked shiftwork with low birthweights (Pompeii et al, 2005), particularly where the mother worked nightshifts in the first 3 months of pregnancy. In addition, some of the complications of pregnancy, such as fatigue and nausea, can make shiftwork very difficult. Shiftwork or working at night can make it very difficult for a woman who is breastfeeding to feed her baby, and may affect milk supply, particularly whe n the times she wi ll be apart from her baby are unpredictable. Care should be taken when a pregnant or breastfeeding mother works shifts or nights to ensure that the mother does not become overtired , and if a pregnant woman's doctor advises them that they

[El

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should stop for health and safety reasons, they should be permitted to transfer to day work.

Standing or sitting for long periods The extra blood volume a woman has while pregnant can increase the chance of clots as blood tends to pool in the legs. It is recommended that pregnant women have the opportunity to move around while they are working , and avoid being in the same position all day.

Other considerations Hormonal, psychological and physiological changes going on in a woman during pregnancy can increase the hazards in the workplace. The following factors may also warrant consideration in the risk assessment process: • Morning sickness/nausea/vomiting • Heightened sense of smell • Headaches/ migraines • Backache • Carpal tunnel syndrome • Fatigue • Insomnia • Frequent urination • Inability to manage stress • Complications such as gestational diabetes or high blood pressure Considerations such as regular rest/toilet breaks, appropriate seating, and a private place to rest are helpful to include in the risk assessment process to reduce the impact of these factors. Biological When a woman is pregnant, her immune system is somewhat suppressed. This is a natural occurrence to protect the foetus from being rejected by the mother's body. The downside of this is that a woman is more susceptible to infection during pregnancy - to colds and flus, gastric upsets, and more serious illnesses. Many biological agents can affect an unborn child if the mother is infected during pregnancy. Hepatitis B, chicken pox, German measles and Toxoplasma are among the illnesses that can lead to death, deformity or illness in the foetus if contracted by the mother during pregnancy. Some of these illnesses can be passed on to a mother through contact with sewage, or by co-workers. It is worth noting that the usual treatments for infections, such as antibiotics, may present a risk to the health and safety of the foetus.

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~ refereed paper

Female employees planning a pregnancy should consult t heir doctor to determine if any vaccinations are required pre-pregnancy. To prevent illness, ext ra precautions should be taken with hygiene w hen working with sewage w hile pregnant and breastfeeding. Suitable personal protect iv e eq uipment (PPE), handwashing facilities and amenities, and first aid should be made available.

How Can the Risks be Controlled? Awareness and risk assessment Pregnancy is not an illness, and should not be treated as such. A woman's unborn baby has as much right to spend t heir days in a safe envi ron ment as any employee. Until very recently risk assessments of workplaces for pregnancy in male-dominated environments have been t reated on a case-by-case basis, usually driven by the pregnant employee herself, and were not often done pre- or in t he early stages of pregnancy. It is very difficu lt to explain to most doctors/ midwives/obstetricians what kind of work is involved at a sewage treat ment plant, and many occupational health and safety (OHS) consu ltants don't have a particular knowledge of the risks facing pregnant women. As a result, to a large extent the onus of evaluating the risks is put back onto the pregnant employee. There are a number of ways that a woman can protect herself and her baby by controlling the physical, chemical , and biological risks, but the greatest risk at this stage is not being aware of the issues. The Human Rig hts and Equal Opportunity Com mission recommends that em ployers d evelop simple, job specific information sheets for doctors to be com pleted in consultation with the pregnant employee. Sydney Water has developed Pregnancy & Breastfeeding Checklists (Taylor, 2008) to assist in the risk assessment process. There are 2 main parts t o t hese c hecklists:

opportunity to give advice and restrictions on certai n duties. A not e on clothing: where a risk assessment specifies that protective clothi ng or PPE is to be worn, the employer should ensure t hat employees are provided w ith appropriate clothing to fit their altered figure. If correctly fitting clothi ng or PPE is not avai lable, the requirement t o perform that task should be reassessed.

Further research and studies As previously mentioned , there is a lack of historical data about the safety of working at sewage treatment plants w hile pregnant or breastfeeding. Further research needs to be done by experts to assess t he risks, and provide advice on how to better manage these risks.

• Include pregnant employees in all steps of the decision-making process • Look for ways to accommodate breastfeeding Where women are given the appropriate tools and measures to assess and control the risks in their workplace, cont inuing to work through pregnancy can not only benefit the employer, but also has been shown to result in a lower incidence of pregnancy complications t han for women who do not work during pregnancy (Greenfield, 2008).

The Author

Breastfeeding safety Breastfed babies tend to have fewer illnesses as they gain more immunity from their mothers. Where a female employee chooses to breastfeed, the benefits to the employer for supporting that decision include: • improved retention of female employees • earlier ret urn to work • easier return to work transition • reduced use of sick or carers leave days Women who express breastm ilk at work need a comfortable, private area, with access to clean water (for handwashing and washing equipment) and refrigeration (to store the expressed breastmilk).

Recommendations and Conclusion With awareness and proper risk assessment, the risks of working at a sewage treatment plant wh ile pregnant or breastfeeding can be si gnificantly minimised o r eliminated. The foll owi ng recommendat ions will assist in red ucing the risk: • Workplace risk assessments should include pregnancy if there are women of child bearing age likely to work at that worksite

• Part 1 : A risk assessment form which outlines a num ber of t he risks, and allows a preg nant employee, her manager and OHS consultant to identify action and manage t he risks

• Provide pregnant employees with as much help as possi ble to find out what risks she might be exposed to

• Part 2: A su itable d uties checklist t o be comp leted by t he pregnant woman and her d octor, explaining the type of duties t hat the woman is likely to perform in her workplace, and giving t he doctor an

• Each employer should develop a ' Pregnancy & Breastfeeding Risk Assessment Checklist' for t heir workers , and a suitable d uties checklist for doctors to complete

Nonie Taylor (non ie.taylor@syd neywater. com.au) is an Envi ro nmental Engineer, worki ng as a Production Officer at Syd ney Water. She has developed a Pregnancy & Breastfeeding Risk Assessment Checklist to be used across the Treat ment Operations Division of Sydney Water. Nonie has worked at Treatment Plants through two pregnancies, and while breastfeedi ng.

References and Further Reading Australian Breastfeeding Association, Breastfeeding Friendly Workplaces

[Accessed Online 30/ 08/08] http :// breastfeed ingfriendly.com.au Greenfield, M., 2008, The Working Women 's Pregnancy Book, Yale University Press. Health and Safety Executive, 1994, A Guide for New and Expectant Mothers Who Work, HSE Books, [Accessed Online

30/08/08] http://www.hse.gov. uk/pubns/ indg373.pdf. NSW Department of Commerce, 2007, Maternity at Work 6th Edition. Pompeii, L., Savitz, D., Evenson, K., 2005, Physical Exertion at Work and the Risk of Preterm Delivery and Small for Gestational Age Birth, Journal of Obstetrics & Gynaecology, Vol 106, p. 1279-1288. Taylor, N., 2008, Sydney Water Treatment Operation Pregnancy & Breastfeeding Checklists , DRAFT. Trades Union Congress,(UK) Pregnant Women and Risk Assessment, [Accessed Online 30/08/08] http://www.tuc.org .uk/h_and_s/tuc-97 12fO.cfm. USDAW, 2005, Pregnancy Risk Assessment Checklist, [Accessed Online] http://www.usdaw.org.uk WorkCover NSW, Pregnancy and Work Guide 2002.

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wastewater treatment

~ refereed paper

SEWER MINING FOR GOLF COURSE IRRIGATION V Hadzihalilovic Abstract As Melbourne faces another season of water restrictions, it is evident that urgent solutions need to be found to bridge the gap in our water supply. Sunshine Golf Course in conjunction with City West Water has implemented a sewer mining scheme designed to utilise sewage from a neighbouring residential development. This project, with extended aeration treatment, provides a 76 hectare golf course with 0.25 ML of EPA Victoria Class 8 water every day relying on raw sewage generated by approximately 750 households. This paper summarises the concept, design and early operating data of a plant installed in the west Melbourne suburb of Sunshine.

Introduction At the time of writing this paper, Melbourne was experiencing another dry spring, with rainfall in September at only 21 % of the average total rainfall for the month. This means yet another summer of high level water restrictions. The shortage of water wi ll affect all consumers w ithin the next couple of months but particularly hard hit wi ll be golf clubs and parks that rely heavily on irrigation for their grass areas during the dry summer period. In 2004, Melbourne land developer Australand commissioned Maunsell AECOM (formerly Earth Tech Engineering) to prepare a concept development study to evaluate the potential for using recycled water for irrigation of the new Sunshine Golf Club, located at Mt Derrimut Rd, Derrimut. The first sewer mining for irrigation of recreational facilities in Australia commenced operation in Canberra in 1995, where a facility at Southwell Park, Lyneham, was constructed and the term WATERMINING was registered by ACTEW. This facility mined water from a large main beneath the site, treated it to a high standard and provided it for irrigation of the sports fields on site. The plant produces about 30 ML of reuse water a year.

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Australand is developing a parcel of land previously occupied by Sunshine Golf Club into a residential subdivision and the Golf Club has relocated to a site nearby, located on approximately 76 hectares of land. It comprises an 18-hole golf course along with a number of small buildings including the club house. Maunsell AECOM proposed a sewer mining scheme that would utilise sewage from the developing residential area at Brimbank Gardens. Currently this is the only sewer mining plant operating in the area of metropolitan Melbourne where sewage is abstracted directly from a sewer line specifically for the purpose of irrigation. There are, of cou rse, several water recycling plants operating within existing sewage treatment plants where treated effluent is used for irrigation.

Sewer Mining: Concept Development The process of recycled water production includes diverting a portion of raw sewage flow from an existing sewer into the wet well of an underground pumping station. Sewage is then pumped to a treatment plant where it is treated to the required level of quality for irrigation of the golf course. Treated water is then discharged int o a storage pond and pumped through the watering reticulation system as required. The concept development study undertook a demand analysis and identified three potential sewage abstraction points in the area. Regional wat er and wastewater retailing company City West Water (CWW) was contacted to provide information on current and estimated future flow through the three sewers. The decision was taken to abstract sewage from the 450 mm diameter Derrimut Branch Sewer. The abstraction point was selected for three main reasons:

80 ML/yr abstracted and treated to irrigation standard.

• its relative proximity to the golf course • expected growth in sewage flow due to development in the area • the catchment is almost exclusively residential. Sewage abstraction was expected to be of fairly uniform quality, allowing the treatment process to be relatively simple and reliable.

Irrigation Water Demand The design of the new golf course specified that, once established, the irrigation demand will average approximately 80 MUyear. Ideally greens, tees and fairways will be watered, but if water is limited, the irrigation to the fairways can be reduced . Typically, for irrigation of golf courses, water demand occurs over the spring/summer/autumn period, when grass water requi rements exceed the available soil moisture. In Melbourne, this period is from October to April and req uires some six months of watering. Stormwater is used to supplement the recycled water supply and is stored in a separate facility. Apart from the two main storages, there are several smaller dams at the golf course for the collection of stormwater. At the beginning of the planning phase, CWW provided Maunsell AECOM with a report analysing the expected future increase in sewage flows based on anticipated population growth in the sewage catchment. Analysis of the report indicated that the requi red sewage quantity for treatment would be reached when development in the area reaches about 620 households, at which stage an estimated total of 250 kl of sewage would be flowing through the sewer each day. The estimation was that the required flow level would be reached by winter 2007. However, a supplementary report undertaken in March 2007 indicated that the required level would not be reached until March 2008. This was attributed mainly to recently increased awareness of customers to water conservation. Recorded inflow at the inlet to the treatment plant after the start-up proved the revised estimate to be correct.

technical features

~ refereed paper

wastewater treatment

Figure 1. Outlet from pump station.

Figure 2. General view of the plant.

The golf course irrigation system features a dual network with separate lines for irrigation using potable water and recycled water/ stormwater. The irrigation system reticulates recycled water across the golf course, utilising t he water stored in the on-site storages and a potable water system provides drinki ng water to two locat ions on the course (at onsite toi let facilities). This means that there is physical isolation of the golf course watering system from the potable water distribution system. Although the golf course wil l mainly be irrigated during the summer, the prod uction of recycled water will occur year-round to enable the treatment and storage of enough water to meet the high demand for water during summer months.

Shared Responsibilities CWW has offered Sunshine Golf Club a commercial agreement to own and operate the proposed recycled water system on a cost recovery basis with the assets to be vested in CWW. Construction of the plant has been financed by Aust raland at a cost of around $750,000. However, this does not include costs associated with construction of t he pump station, sewage rising main, installation of the SCADA syst em and recycled water storages. Agreement has been reached for CWW to take responsibi lity for the entire treatment system comprising the pump station, sewer mining treatment plant (SMTP) and the recycled water produced and stored on sit e. The responsibility includes providin g Sunshine Golf Club with the required volume of Class B recyc led wat er on a daily basis, w hich involves

operating and maintaining the treatment plant, pump station and associated infrastructure up to the customer supply point. Sunshine Golf Club is obliged to use the recycled water for irrigation of greens and tees and if feasible, other green areas within the Golf Club. The Victorian EPA requires the Golf Club to use the recycled water in an environmentally sustainable manner. Monitoring the irrigation process, including reporting all incidents to CWW, is also required. The agreement is that CWW wi ll only charge the Club for the costs of operating the plant.

Plant Design Design of the pump station and t he diversion structure was completed by Maunsell AECOM with input and final review by CWW. Construction of the pump station and installation of mechanical and electrical equipment was completed by By-Jas Engineering. The outlet from the pump station is shown in Figure 1. The plant, as shown in Figure 2, was designed and constructed by By-Jas Engineering with Maunsell AECOM acting as Superintendent on behalf of Australand. Sewage is abst racted from Derrimut Branch Sewer at Middle Road by diverting the flow from the downstream pit of an existing gas check manhole. A stainless steel weir has been const ructed at the bottom of the pit to maintain the original level in the manhole without compromising funct ionality of the entire gas check structure. The pit modification works also include a screening fabrication to avoid blockage of the

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wastewater treatment

[SJ

Recycled water quality

instal led submersible pump by large solids entering the pump well. The pit is connected to the wet well of the pump station by a 200 mm pipe, approximately 4.0 m long. The pump well is 4 .8 m deep and has been constructed of prefabricated concrete ring beams. A single, Flygt submersible pump with closed channel impeller has been installed in the well. The pump installation is self-locking and is attached to guide rails, t hus eliminating the need for maintenance crew to enter the well to uncouple it. The pump duty point is approximately 7.0 Usec at 27 m head at 6.0 kW input power.

refereed paper

Sunsh ine Golf Club is now provided with Class B quality recycled water, as defined in Table 1.

Figure 3. Aeration tanks.

The pump is controlled by a Multismart Pump Station Manager manufactured by Multitrode. The Multismart unit has been set to operate the pump on either level or time basis. In other words, the pump starts when water in t he wet well reaches the pre-set high level or when the pre-set pump idle t ime expires, whichever occurs first. Conversely, the pump stops when water reaches a pre-set low level or after th e pump has been running for a pre-set time. Thus, t he amount of raw sewage that has been pumped to t he plant can be adjusted to su it the plant capacity. Sewage is transported from t he pump station to the treatment plant via a PE DN 110 pipeline, 1310 m long. The design velocity in the rising main is approximately 1.2 m/s which is suitable for transporting raw sewage. The designer's choices were limited by the relatively low flow required, and the minimum diameter of the rising main specified by CWW. The rising main was const ructed by Azzona Drainage Contractors. A Decoron signal commun ication cable, installed in a 63 mm PVC conduit, was laid in t he same t rench as the rising main. The recycled water plant has a design capacity of 250 kl over a 24 h day and is capable of treating raw domestic sewage with an organic loading of 96 kg/day BOD. The peak hour capacity of the plant is 20.8 kUh. Waste streams from the plant are returned to the sewer for further processing within the CWW and Melbourne Water sewerage treatment systems. The treatment process at the plant comprises: • bar screening at the plant inlet

• secondary clarification • dual media filtration • UV disinfection. The plant consists of two aeration tanks each of 180 kl capacity, as shown in Figure 3, and two double hopper settling tanks of 50 kl capacity each. Screened sewage is aerated in the aeration tanks and transported to the clarifiers. Sludge collected in the bottom of the settling tanks and the floating scum are pumped back to the aeration tanks. From t he settling tanks, effluent flows to a 2.5 m diameter gravel, sand and carbon fi lter. The filter is backwashed when the water level in the fi lt er reaches the overflow level. Backwashing is performed in two phases - firstly, by a mixture of water and compressed air from two plant air blowers, and secondly, by water only. The plant uses treated effluent for backwashing which is stored in a separate backwash tan k. Sodium hypochlorite is added into the backwash tank to prevent biological growth in the filter. The last stage of t reatment is disinfection of effluent in t he UV unit before discharging into the storage pond. Additionally there is a provision for automatic adjustment of pH val ue by injecting caustic soda at the plant inlet and into the aeration tanks.

Table 1. Class B Recycled water quality (Victorian EPA). Parameter

BOD

ss pH

E.coli

Class B quality (50 %ile)

A water, salt and nutrient budget has been prepared for the site, based on the expected water use during the establishment stage. However, the EPA has not established guideline levels for nitrogen and phosphorus in Class B recycled water. It is expected that subsequent to treatment in the SMTP, nitrogen and phosphorus levels in the recycled water will be nitrogen: 10 - 30 mg/l (equ ivalent to 35 - 106 kg/ha/yr) and phosphorus: 6 - 10 mg/l (equivalent to 21 - 35 kg/ha/yr). Recommended nitrogen and phosphorus application rates for couch grass are 100-200 kg/ha/yr and 0-50 kg/ha/yr respectively, therefore the application rates do not exceed limits and some additional fertiliser may be required . Nitrogen and phosphorus used by plants are generally applied to the soil in the form of fertilisers. The additional nitrogen and phosphorus available in the recycled water will minimise t he ferti liser application required and should not result in a buildup in the soil. The majority of irrigation of the golf course will be onto a grass such as couch grass.The ANZECC Guidelines state that couch grass tolerance to salinity in irrigation water (clay soil) is 3,600 µSiem. This is sig nificantly more than the expected electri cal conductivity of recycled water (800 µS/cm or 500 mg/l). The parameters described in Table 2 will be monitored by t he operator at the specified frequency.

Control System The operator at t he plant is able to rem otely monitor the status of the sewage pump station and a number of parameters at the plant such as: • Raw sewage flow at the inlet • Effluent flow at the plant outlet • Waste st reams from the plant returned to the sewer • pH value of the effluent • water level in t he storage pond.

<20mg/L <30mg/L 6 to 9 <100 org/100ml

There is also an interlock sig nal from the storage pond to the sewage pumping station that stops the pump when the pond is full. The CWW operator attends

• extended aeration biological treatment

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technical features

~ refereed paper

wastewater treatment

the plant no more than once a day, mainly to start the filter backwashing sequence, although it is not necessary for filter backwashing to occur every day under normal operating conditions. The treatment plant has been incorporated into CWW's SCADA system, which enables operators in the CWW control centre to receive up to 20 different alarms from the p lant and monitor four analogue values on a continuous basis. A CWW operator attends the plant if a critical alarm is raised .

Effluent Quality Risk Mitigation In the event of the plant not operating for a prolonged period, the blowers will operate manually for half an hour per day. Th is ensures that the biomass within the plant remains viable when there is no raw sewage inflow into the plant. This enables the effluent quality to meet Class B standards upon commencement of plant operation. The UV unit has been designed with contingency capacit y. Six lamps have been provided while fou r would be sufficient to treat t he nominated quantity of water. If a single UV unit lamp fai ls, an alarm is activated via the auto dialler and the operator will need to go on site to replace the lamp. Meanwhile the plant contin ues to produce treated water as before, since the remai ning UV lamps have a sufficient disinfection capacity. The plant Operation and Maintenance Manual prescribes replacing all UV lamps on an annual basis, providing an assurance that the lamps operat e co nstantly at or near 100% capacity or very close to it. In the case of power failure, the whole plant will stop and no water wi ll be discharged until the supply is re-est ablished.

System Operation to Date The plant commenced operation in August 2008 and, after a trial period of 6 weeks, has been successfully operating since. The results of three effluent quality tests taken within one week during the plant commissioning have shown that crucial effluent quality parameters are well within prescribed values as shown in Table 3.

Table 2. Monitoring Frequency. Parameter

Frequency (sample/year)

Biochemical Oxygen 0emand Suspended solids pH Floatable matter

monthly monthly monthly quarterly continuous continuous monthly

Chlorine residual Flow rate E.coli Blue Green Algae* Total Nitrogen Total Phosphorus Salinity

monthly in summer and quarterly in winter monthly monthly monthly

At times an exceptional ly high content of fat and solid matter has been noticed in the raw sewage. Gross solids (e.g. plastic, pieces of rock or wood) blocked the pump several times. Apart from this, raw sewage showed characteristics of fairly typical domestic sewage as wou ld be expected from a predominately residential area. The quantity of sewage flowing th rough the sewer during peak hours is greater than was expect ed during the design phase. Also the peak flow extends for longer periods, with morning peak flow sometimes lasting until midday. On the other hand, the flow outside peak hours remai ns fairly low. The pronounced flow variations have required adjusting the pump running time to suit the plant capacity. A gradual decline in the sewage flow was noted aft er initial operation and this may be attributed to increasing household use of grey wat er during mid to late spring .

Summary The plant has achieved the set target for recycled water quality for Class B effluent. It currently delivers on average 0.25 ML of effluent per day and is expected to exceed the required 80 MUyear of recycled water. This will make the golf cou rse drought-proof and non-reliant on potable water for irrigation th roughout the year.

â&#x20AC;˘ careful design of diversion works is required to reduce the amount of gross solids entering the pump well and to protect the equipment â&#x20AC;˘ the right balance needs to be found between the capital cost and the equipment redundancy. It is advisable that the raw sewage pumping station and the rising main be protected from entry of large objects that could block the system. This could be done either by screening the raw sewage before it enters the pump station and/or installation of a silt trap or macerator. A reasonable degree of contingency capacity in vital segments of the system is always a desirable choice, such as stand-by pumps, air blowers, UV lamps or membranes. Provision of contingency capacities in the design is inseparable from the design of control and alarm system featu res of a sewage treatment plant and its supporting facilities. Both design segments need to complement each other with the overall aim of providing effluent of the required quality, quantity and reliability.

The Author

Two main lessons learnt from the project are as follows:

Table 3. Effluent quality. Parameter

Units

Class B quality (50 %ile)

Range of test values

BOD

mg/L mg/L

<20 <30 6 to 9

3-5

4-6 7.0-7.4

org/10DmL

<100

0-12

pH E.coli

Vedran Hadzihalilovic (email vedran. hadzihalilovic@maunsell.com) is Senior Engineer - Water with Maunsell AECOM and has 12 years experience in design and construction of water and wast ewater pumping systems and treatment in Austral ia and overseas.

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CST WASTEWATER SOLUTIONS FORMS PARTNERSHIP One of Australasia's leading wastewater solution groups, CST Wastewater Solutions, has formed a partnership with the internationally respected Talbot & Talbot wastewater and energy environmental solutions group.

f\l Water Business aims to keep readers alert to business news and new product releases within the water sector. Media releases should be emailed to Brian Rault at brian.rault@halledit.com.au or Tel (03) 8534 5014.

AWA wishes to advise readers that Water Business information is supplied by third part ie s and as such, AWA is not responsible for the accuracy, or otherwise, of the information submitted.

a member of the Global Water and Energy Alliance, a group of select global compan ies committed to providing solutions in water and wastewater treatment for the recovery of green energy and water. The company's network of partners also includes Smith and Loveless and Berson UV-techniek. Contact Michael Bambridge 02 9417 3611, email: info@cstechnology.com.au, web: www.cstwastewater.com

MINISTER OPENS NEW MANUFACTURING FACILITY Tyco Water's Sintakote Steel Pipeline Systems new large-diameter steel waterpipe manufacturing facility at Somerton, Victoria, was officially opened by Tim Holding, the Minister for Water for Victoria.

The move comes as CST Wastewater Solutions expands its industrial and municipal services and technologies from a new headquarters established in Sydney after its name change from Contra-Shear Technology.

Through its established expertise and new partnership, CST Wastewater Technology plans to strengthen its position in the market through packaged wastewater solutions for projects rangi ng from small individual plants to complete industrial estates and mining developments.

CST Wastewater Solutions Managing Director, Michael Bambridge, said the new partnership wi ll give further impetus to the growth that led to the name change, with Talbot & Talbot bringing particular expertise through its four major divisions based in South Africa, including Talbot Laboratories, Talbot Engineering, Talbot Operations and Talbot Green Energy.

It wi ll also extend its anaerobic and aerobic wastewater treatment technologies focused on industries such as the food and beverage, chemical, pulp and paper and primary industries. CST is

Water Minister for Victoria Tim Holding officially opens new Tyco Water Steel Pipe large diameter manufacturing facility.

The $40 million Sintakote facility will be able to supply pipe for many of Southern Australia's water infrastructure projects. "Previously, the highest output from the sm all diameter facility was approximately 12,000 tonnes, wh ich was achieved last year. With the new plant c oming on line, the site's capability has ext ended to above 60,000 tonnes per annum with both manufacturing lines" said Tyco Water Steel Pipelines Marketing Manager, Rod ney Glocer. "Tyco Water's significant investment into further enhancing its Australian manufacturing presence has also resulted in 80 new fu ll-time Victorian jobs" he said.

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