Water Journal June 2010 by australianwater

Volume 37 No 4

JUNE 2010

AWA JOURNAL OF THE AUSTRALIAN WATER ASSOCIATION

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Journal of the Australian Water Association ISSN 0310-0367

Volume 37 No 4 June 2010

contents REGULAR FEATURES From the AWA Chief Executive

Who Pays?

T Mollenkopf

P Binney

My Point of View Crosscurrent

8 RKnee

Aquaphemera

Industry News

AWA News

Events Calendar

Twinning Developments at City West Water - see page 38

FEATURE REPORTS Water Reform in the Apple Isle RBorg, Director Water - Hyder Consulting

Twinning Developments at City West Water KJohns, Manager Operations and Maintenance; DMaple, Manager Field Services, City West Water

Water Optimisation through Intelligent Infrastructure S Doran, Senior Managing Consultant, IBM/1/NZ

An Environmental Approach to Desalination

AWA CONTACT DETAILS Australian Water Association ABN 78 096 035 773 Level 6, 655 Pacific Hwy, PO Box 222, St Leonards NSW 1590 Tel: +61 2 9436 0055 Fax: +61 2 9436 0155 Email: info@awa.asn.au Web: www.awa.asn.au DISCLAIMER Australian Water Association assumes no responsibility for 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, April , May, June, August, September, November and December. EDITORIAL BOARD Chair: Frank R Bishop; Dr Bruce Anderson, AECOM; Dr Terry Anderson, Consultant SEWL; Michael Chapman, GHD; Robert Ford, Central Highlands Water (rtd); Anthony Gibson, Ecowise; Dr Brian Labza, Vic Health; Dr Robbert van Oorschot, GHD; John Poon, CH2M Hill; David Power, BEGA Consultants; Professor Felicity Roddick, RMIT University; Dr Ashok Sharma, CSIRO; and EA (Bob) Swinton, Technical Editor.

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

An Environmental Approach to Desalination - see page 44

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 AND journal@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 Helen Kelton, Editor, Water Journal - journal@awa.asn.au • Water Business and Product News Brian Rault, 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 Rault, 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

There's nothing like a long drop! Sydney's major sewage treatment plants are perched on top of the cliffs which look out to the ocean. The out fall tunnels are below the sea bed. At North Head the drop is 60 m. What better place for a min-hydro-electric turbine? This plant was built by Worley Parsons and Energetics, and supported by the NSW Government's Climate Change Fund. It is part of the upgrade of the North Head plant (see page 14). Photo courtesy of Sydney Water.

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JUNE 201 0 1

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Journal of the Australian Water Association ISSN 0310-0367

Biosolids in a Real Farm Situation - see page 91

Volume 37 No 4 June 2010

contents

Geo-Engineering Dams for Both Global Cooling and Water Conservation see page 101

TECHNICAL FEATURES ( LJil INDICATES THE PAPER HAS BEEN REFEREED) DESALINATION & MEMBRANE TECHNOLOGY

[i]

Adelaide Desalination Project Piloting Experience Comparison of conventional and membrane pre-treatment for seawater RO

M Blaikie, C Pelekani

ESSENTIAL WATER LISTINGS GUIDE

46 53

DESALINATION & MEMBRANE TECHNOLOGY (Continued)

[I]

Treatment of Coal Seam Gas Water Pilot and full-scale experience

S Chalmers, A Kovse, P Stark, L Facer, N Smith

B Bolto, M Hoang, Z Xie

B Sparrow, J Zoshi

J McKay

J T Aiken, C Derry, RAttwater

W Rajendram, A Surapaneni, G Lester-Smith

G Egan

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Pervaporation - A Further Low Energy Desalination Option? Too slow at present, but there is potential

Thermo-Ionic Desalination Driven by Solar or Waste Heat A novel concept undergoing scale-up from pilot plant AGRICULTURAL USE

[i]

America's Fascination with Australia's National Water initiative Comparing water policies and laws

[ii]

Impact of Improved Recycled Water Quality on a Sydney irrigation Scheme Storage of recycled water is part of the treatment train

[i]

Biosolids in a Real Farm Situation

Analyses of both nutrients and contaminants in the feed produced WATER TRADING

The Maturing Water Market in the Southern Murray-Darling Basin The market is working well but is still developing WATER SUPPLY

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Geo-Engineering Dams for Both Global Cooling and Water Conservation Potential for offsetting carbon credits against capital cost

I Edmonds 101

TECHNICAL NOTE

Fluoride Testing for Seepage Identification: Beware! Percolation through soils can have unexpected effects

GRuta 105

WATER BUSINESS

New Products and Business Information

108

Advertisers' Index

120

2 JUNE 201 o water

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Water Reform in the Apple Isle Ray Borg, Director Water - Hyder Consulting The State of Tasman ia has recently undertaken an ambitious reform process by establishing three new Water Corporations (Ben Lomond Water, Cradle Mountain Water and Southern Water) with a fourth business (Onstream) created to efficiently perform the functions common to the three water businesses.

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The 29 local councils, which previously had responsibility for water supply and sewerage services, have been overlaid with the three water corporations, w ith support from Onstream.

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Why Was the Reform Needed?

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Tasmania has 14 per cent of Australia's tot al water resource, but it is crucial that the State makes the best use of this valuable resource in order to avoid the crises experienced in mainland Australia.

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The Tasmanian government therefore embarked on Tasmania's Water and Sewerage reform process in order to secure the long term sustainability of the wat er resources and ensure that social, health and environmental issues in all communities were addressed.

Figure 1. The council boundaries and the jurisdiction of the Water Businesses. addition to the three new Water Corporations and the supporting business, Onstream, the new legislation also establishes an economic regulator (Office of the Tasmanian Economic Regulator-OTTE R) who wil l independently set prices, set minimum customer service standards and monitor the performance of the businesses. The new legislation also provides an expanded role for the Tasmanian Ombudsman to resolve complai nts from water and sewerage customers. Yearly

Early in 2008, the Water and Sewerage A ct 2008, and t he Wa ter and Sewerage Industry Act 2008, were passed unanimously through the Legislative Council. Th is legislation is a significant milestone for the water sector, paving the way for the required structural and reg ulatory reform. In brief, the new legislation establishes new water and sewerage corporations and an enhanced regu latory system. In

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Annual Performance Report for the Sector informs policy development (publicly available)

Treasurer and Portfolio Minister

Dialogue on Strategic ,Issues I

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Figure 2. The structure of the legislative framework. Extract from Jim Martin's Presentation for the Tasmania Water & Sewerage Reform Program. 34 JUNE 201o

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Primary Legislation Acts of Parliament

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Subordinate Legislation Regulations Made under a power in the Act. Needs to be approved by Parliament Water and Sewerage Industry (General) Regulations 2009

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Non-Statutory Guidelines

Guidelines , policy, codes of practice, standards Recommended by an office holder or agency - not enforceable Liquid Waste to Sewer Guidelines 1994

Figure 3. The new legislation. State of the Industry reports that monitor water quality and performance, as well as the financial performance of the corporations, are also a provision of the Act.

What is Important to the New Businesses? The Water Corporations rece ived the water and sewerage assets, previously operated by local counci ls, on 1 July 2009, and initially undertook an evaluation of the assets to determine the status of each network, facility and process. The outcome of this evaluation highlighted that the majority of the existin g Sewage Treatment Plants (STPs) were licenced decades ago. The STPs with the antiquated licences are struggling to maintain compliance with the current licences and wou ld undoubtedly fall short should the EPA consider issuing contemporary licences. To the credit of all concerned, each Chief Executive Officer, Executive Manager and their charges responsible for Source Management/Trade Waste and Treatment Works operations have identified a strategy going forward. The Water Corporations faced a number of challenges, including recognition that aging assets were serving catchments with major industrial precincts. These assets requ ired either/or a combination of new facilities, upgrades to existing facilities, consolidation and/or decomm issioning facilities to assist industrial dischargers to conserve and pretreat their effluent to a greater standard than is currently the case. For a raft of reasons, this wi ll lead to a mutually beneficial out come. Additionally, as detailed in the National Water Initiative , recommendations for Water Utilities to transparently recover the true costs of supply and service provision will be the impetus for industry in Tasmania to adopt Resource Efficiency/Cleaner Production principles. Representatives from the four businesses have held discussions and agreed to pool resources to ensure the adoption of a consistent Trade Waste/Source Management approach across the State. To this end, a State wide Trade Waste Industry Group has been formed to develop plans for a common philosophy relative to policy, strategy, pricing principles, acceptance standards, risk management, operational philosophy and standardised consent/agreement templates. The group is systematical ly working on all fronts and has been set deadlines by the CEO's of each business to achieve

36 JUNE 2010 w ater

Whilst each business is approaching the sequence of tasks required slightly differently they are all aiming t o achieve the same outcomes. Therefore the businesses overarching needs are t o:

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Statutory Guidelines Approved Management Methods Issued under a power of the Act or Regulation by a Minister- may be called up in legislation

predetermined milestones that demonstrate progress.

• Develop an appropriate regu latory structure for trade waste across the state in consu ltation with broader stakeholders • Develop and implement policy for trade waste management and pricing • Develop and implement appropriate pricing models that meet national and state pricing principles • Develop and implement model consents and agreements to support the development of a positive and forward looking relationship between the corporations and their customers

• Develop a management system framework for the Corporations consistent with the National Wastewater Source Management Guidelines • Develop a communication plan that supports awareness, engagement and commitm ent to the objectives of a contemporary trade waste management system The legislation created and comp lemented by existing guidelines to enable the new entities to fulfill their functions is described in the Figure 3. In addition to the Water and Sewerage Industry Act 2008 and Water and Sewerage Industry (General) Regulations 2009, a list (not exhaustive) of existing additional legislation that the Water Businesses (Lic ensees) need to conform to include: • Water Management Act 1999 • Environmental Management and Pollution Act 1994 • Environmental Protection and Biodiversity Conservation Act 1995 (Commonwealth) • Public Health Act 1997 • Fluoridation Act 1968 • Water Act 2007 (Commonwealth) • Land Use Planning and Approvals Act 1993 With the benefit of the lessons learned from previous water reforms in the states of Victoria (circa 1994) and south east Queensland (circa 2007), and with the recent development and publication of a number of National Guidelines such as the WSAA National Wastewater Source Management Guidelines July 2008, Tasmania is in the enviable position of capitalising on these platforms and potentially drafting the most comprehensive and robust system for Trade Waste/ Source Management in the country. The article was produced by Ray Borg, Member of the Source Management Specialist Network committee. The Source Management Network provides an excellent information portal for source management issues Australia wide. The network holds national and state level conferences as well as producing newsletters and articles on topical issues. If you are interested in getting involved, please check their webpage at www. awa.asn.au/L TW.

feature articles

feature article

Twinning Developments at City West Water Keith Johns, Manager Operations and Maintenance; David Maple, Manager Field Services, City West Water City West Water (CWW) has been twinning with the Metropolitan Cebu Water District (MCWD) for the last two years as part of the Asian Development Bank's Water Operator Partnerships Program. CWW has found the twi nning to deliver a number of benefits including an excellent opportunity to develop its staff, to increase its knowledge of what's happening in water around the world and to enable CWW to provide help to developing countries in a practical and very cost effective way. With the twinning with MCWD now coming to a conclusion, CWW has embarked on a second twinning project, this time with a water utility in China. In April 2010, CWW visited Zhengzhou Water in the Peoples Republic of China (PRC) to estab li sh a twi nning project, again sponsored by the Asian Development Bank (ADB). This initial diagnostic visit to Zhengzhou Water involved Keith Johns, Manager Operations & Maintenance and David Maple, Manager Field Services from City West Water and ADB representatives Joanna Masic and Michael White. The visit took place over the period 25 - 30 April 2010. The commitment of Zhengzhou Water to the project was evident by the involvement of the company's senior management throughout the visit, including t he General Manager Zhang Zhanjun, General Engineer Shi Dongwen, and several Departmental Managers. Zhengzhou Wat er is recognised as one of the significant utilities in the Peoples Republ ic of China (PRC) and has been well recognised through the country as a major utility. It has a preeminent position within the Henan Region of the PRC and is a member of the China Urban Water Association. Zhengzhou Wat er Supply Corporation, established in 1953, services over three million people within the Zhengzhou region and has a service area of 303 kms2 with over 624,000 metered connections. The total length of the water distribution syst em is 2,392 km. Zhengzhou relies on water supply from the Yellow River and a number of groundwater extraction points. Water is treated at one of five water treatment plants in the Zhengzhou area. The supply of water and the pressures across the water system are managed in the Zhengzhou Operational Control Centre.

Twinning in action in the Zhengzhou Water Board Room.

Zhengzhou City is supplied through an extensive pipeline network and most properties are metered and all pipes, valves and hydrants are managed using a GIS. The oldest pipe in the network dates back to the 1970s. The pipes used for the transfer and reticu lation systems are mainly ductile iron and a range of steel pipes, with PVC pipes only being used for 100 mm diameter pipes and below. The city is sp lit into five water operational districts and mainten ance activity is distributed via the cust omer service centre. All maintenance vehicles are tracked using GPS locators. As part of the twinning program there were a number of issues initially identified. These projects were: • Non Revenue Water • Water Quality Issues • Leak Det ection process • Asset Management • Operation and Maintenance Activities These core issues were discussed in some detail and a number of site visits were organised to show and verify the activities under discussion. As a resu lt of these activities the twin ning partners agreed that improving water main failure data within one of the operating regions could lead the way to the development of an Integrated Asset Management Plan for the company. This was seen as a key step in the development of Zhengzhou Water and should enable the replication of the project throughout the five operating districts. The activities at this stage include preparing a plan showing the location of all assets within the designated area and collecting the maintenance history of each water main failure. It is expected that some field work wi ll be required to confirm the location of existing assets or locate assets not currently in the GIS. This data needs to be readily available and would be evaluated by personnel from both companies.

A cultural exchange.

38 JUNE 201 o water

The evaluation of the processes and systems used to record water main failure information and failure data wi ll be

feature articles

feature article necessary to determine whether the recording process is effective and the data is comprehensive, accurate and reliable and can be referenced to specific assets. Historical recording of water main failure data will also be evaluated. This process will support identification of training needs within Zhengzhou Water and, together with planned visits to Australia, should enable the development of the first stages of an Integrated Asset Management Plan. Under the ADB's twinning guidelines it is important that there are real and measurable outcomes. The key outcomes expected from this twinning project are: • Asset management accountabilities assigned • Consistent water main failure data collection system established • Draft asset management policy developed Repairing a leak on a busy Zhengzhou street.

• Preventative maintenance programs considered • Water main renewal criteria established

AWA is collaborating with agencies offering International Water Utility Partnerships such as the Asian Development

Having completed this first stage of the twinning program and agreed a specific project, both companies are keen to develop a close and long term relationship which should benefit both parties in the future. The initial project is supported by the Asian Development Bank and will span 15 months.

and interests of the Australian water industry. If your utility is interested in participating in one of these partnerships, contact

For more information please contact Keith Johns Manager Operations and Maintenance at City West Water 03 9313 8708

ahinchliffe@awa.asn.au or tel: 02 9467 8418.

Bank's Twinning Program, to tailor these programs to the needs

Ann Hinchliffe, Project Manager- Industry Programs, AWA on

••• ••• Australian

Water Quality Centre

High quality analytical services, leading edge research and professional advice on water quality issues. New state of the art laboratories now located at SA Water House, 2S0 Victoria Square, Adelaide

Tel: 1300 653 366 www.awqc.com.au

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feature article

Water Optimisation Through Intelligent Infrastructure By Shalome Doran

Shalome Doran is a Senior Managing Consultant in IBM's Energy & Utilities Practice, IBM A/NZ. It is clear that unprecedented urbanisation and population growth is placing greater demands on t he infrastructures that deliver vital services such as transportation, energy, water, education and public safety. The Treasury predicts that Australia's population will increase to 35 million by 2049. This growth is likely to place enormous pressure on Australia's resources and infrast ructure, including our water supply. How will the driest inhabited continent in the world cope with unprecedented demand for one of our most precious resources? The Organisation for Economic Cooperation and Development (OECD) estimates that more than 75 per cent of Austral ia's population will be facing severe water stress in terms of supply by the year 2030. Given the fin ite source of our fresh water, it is increasingly imperative to balance our use of t his precious resource with our responsibilities toward the environment through improved water management techn iques.

However, these systems are quickly reaching the end of their useful lives. Water infrastructure is three times more expensive to build and maintain than electricity infrastructure, but neglecting it may be even more costly. The assets in a number of ou r capital cities are not on ly very old. In many cases assets are not well mapped or recorded and occasionally only discovered throug h routine maintenance in previously untouched areas. The challenge is not only based in the cities either; much of Australia's exist ing rural water infrastructure is aging, inefficient and in a state of disrepair.

Sustainable Water Infrastructure

One of IBM's key focus areas is on reducing water wastage through improved asset management and making better use of a fin ite resource. With an aging workforce that stores much of the vital asset information in their heads, t he need to develop a com prehensive and efficient asset management infrastructure is evident. At the data level, the need to detect and locate leaks in pipelines, measure and assess pipe conditions, and map pipeline systems noninvasively is paramount. Tech niques suc h as acoustics, digital robot inspection, ground penetrating radar, wireless sensor networks and benchmark-based flow modelling can al l be dep loyed. In fact, recent innovative advancements make it possible to envisage a fully integrated distribution system with high accuracy smart metering, potentially with remote shut-off capabil ity to control sudden leakages and reroute resource flows t o and from critically affected areas.

Complex and aging water t reatment, distribution, and wastewater treatment systems - some more t han 100 years old, are critical for basic sanitation, health, and public safety.

IBM is leveraging its integration ski lls and leading-edge technologies, such as Maximo Asset Management, to deliver the abi lity to measure and manage the availability and use of

Technological advances in computational power, pervasive technology, telecomm unications (internet) and data analytics, means we have an opportunity to solve problems which have previously seemed elusive. Today we have the ability to bring this technology t o bear on complex societal problems, and provide hol ist ic solutions to global trends such as exploding population density in our cities.

MELBOURNE

ADELAIDE

Peter Everist 0398633535

Owen Jayne

pevertst@w,group.com.au

ojayne@wigroup.com.au

BRISBANE

SYDNEY Hugh McGriley 02 8904 7504

Graeme Anderson 07 3260 2170

08 83481687

ganderson@wigroup.com.au hmcgn ley@wigroup.com.au

40 JUNE 201o water

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feature articles

Water and Waste Water

International@ Paint supplies innovative coating technology to the Water & Waste markets for both new construction and maintenance project s. Our extensive market focused product range includes Polibrid@705-E, lnterline@975 and lnterfine@1080, designed for application in areas such as desalination plants, sewage treatment plants, sewage manhole pits, penstocks, pipelines, tanks and handrails.

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feature article all strategic assets. Planned maintenance of an accurate asset register allows proactive management of all production assets, reducing cost inefficiencies and optimising operations. Building and repairing water infrastructure is disruptive, inconvenient and time-consuming. However, we now have the opportunity to improve our existing networks and most importantly, do it better and smarter, by adding intelligence and instrumentation into the asset management system. Today we have an opportunity to future-proof our national water infrastructure, to help us prepare for the undeniable challenges ahead. A full smart grid solution for water would be an obvious step forward. Further since Australia's incredibly successful local and global agricultural market would not exist without irrigation, this smart grid must also include irrigation. By continuing to make water systems smarter, particularly for agricultural use, water industry stakeholders can make money and save water.

Irrigation with Intelligence Smart irrigation wi ll play a vital role in drought stricken areas where farmers have to maximise water supplies. Many have pointed out that the future of farming wi ll include the integration of crop models, geographic information system (GIS) data, local soil maps, historic weather information, and precision agricultu re that takes site-specific data entered into a smart controller to manage irrigation scheduling. Industry solutions in the early stages of commercialisation range from weather monitoring interfaced with irrigation systems either through web-based sites or installation of on-site weather stations, to models based on extensive evapo-transpiration data interfaced with more than 40,000 National Oceanic and Atmospheric Administration weather stations.

42 JUNE 2010 water

To support advanced site-specific solutions, ensuring that enough water is supplied to the plants is critical to ensure a good-yielding crop. Smarter water management systems would directly translate into better usage of rural water tables, thus leading to better irrigation and less wastage of ground water in farm ing techniques. Furthermore, it would provide better accountability, enabling future generations of systems to t arget specific optimisation goals in a systematic manner.

A New Look at Smarter Water Despite the fact that we often treat water as a ubiquitous undervalued commodity, there are numerous exciting and innovative opportunities to address our water challenges. Currently, emerging technologies tend to focus on desalination, rainwater catchment and treatment, and industrial reuse, all of which are designed to increase supply, an undeniably important part of the equation. Far more promising, both socially and economically, is the less-developed market for technology that decreases water demand. At IBM, we believe that we can help to make our economy sustainable and manage our most precious resource by creating an integrated and intelligent water system. A smart network that monitors its own health, remotely senses damage, assesses water availability and predicts demand. We know that to achieve this vision will require a collaborative approach from a broad ecosystem of partners and stakeholders. We can conclusively state that the only way to ensure the supply of fresh water to meet growing consumption needs is to manage it better. We cannot increase what we get from a finite source, but we can certainly collectively get smarter with what we do with it. Water well managed, is water saved!

feature articles

Thermo Fisher SCIENTIFIC

feature article

An Environmental Approach to Desalination Just over ten months since the Victorian Government appoint ed Aq uaSure* to deliver the $3.5 billion Victorian Desalination Project, work is well underway on the state's Bass Coast, near Wonthaggi. For the past ten years, Australia has been plagued by drought. So much so that securing rainfall-i ndependent water supplies is now seen as a crucial response to economic and population growth. By 2013, the country's five largest coastal cities will all have desalination plants - the biggest will be in Victoria and is currently being designed by Parsons Brinckerhoff (PB) and Beca engineers. When complete, the desalination plant wi ll supply 150 bi llion litres of water a year to Melbourne, Geelong and, via other connections, South Gippsland and Western Port towns. Th e design and construction contractor for the project, Thiess Degremont, has engaged PB and Beca to design the plant, which is due to deliver water by t he end of 201 1. The water is needed urgently, so the design and construct ion teams are working hard to meet a challenging schedule. The whole project will be designed and delivered in 28 months. Much has already been achieved. To date, more than 180,000 hours have been spent on project design. Earthworks are nearing completion on the plant site, concrete footings have been poured, almost 400 tonnes of structural steel has been erected, construction of the pipeline and underground power supply are underway and the first of two tunnel boring machines have arrived on site.

Environmenta lly Sustainable Design The Victorian State Government was determined that this plant should be as green as possible. Planning and design work will ensure the plant is as sustainable as possible and meets the environ mental performance requ irements for the project. Environmental initiatives planned for the site include a 'living green roof' - the largest of its kind in Australia. The architectural concept is based on a 'green line' that runs

Parsons Brinckerhoff and Beca engineers review drawings in front of the pre-treatment site.

t hrough the site, allowing the plant to blend into the natural landscape. The roof will be covered with living indigenous vegetation to camouflage the plant, providing acoustic protection, corrosion resistance and thermal control, and reducing maintenance needs. Using indigenous vegetation will also help restore the natural ecology of the area. The plant site will be lowered, allowing the plant to be int egrated into the landscape and reduce the amount of energy needed to lift seawater into the plant. The highest point of the main building will be 26 met res above sea level - 20 metres above ground level, but will be barely visible from surrounding areas. Large water storage ponds will capture runoff from the 'living roof' and other buildings for irrigation on site.

Energy Efficient Design As well as its compact, modular design, the plant will use world-leading energy recovery devices in the reverse osmosis process to significantly reduce power consumption. The plant and transfer pipeline's power requirements will be 100% offset by renewable energy and the 87km powerline will be underground, minimising impacts on landowners, farmers and other people living and working in the area.

Small Plant Footprint Above ground, the plant wil l have a very small footprint, taking up just 38 hectares of the 263 hectare site.

The architectural concept is based on a 'green line' that runs through the site.

44 JUNE 201 o water

The remaini ng 225 hectares will become the focus of one of the largest ecological rest oration projects in Victoria's history restoring and enhancing the natural habitat and creating a new coastal park for future generations to enjoy. Wetlands, coastal and swampy woodlands and new habitats wi ll be created for local fauna.

feature articles

feature article Around 4 million plants and 150,000 trees will be used to reinstate indigenous vegetation cleared over the years to make way for mining and grazing. A new 8km network of pedestrian cycling and horse riding paths on the plant site wil l link with existing t rails .

A Strong Design with Minimal Impact The Victorian Desalination Project brings toget her architecture, ecology, the landscape and world- class t echnology to create one of the most significant and large scale environmental design projects in Australia. Responsible governments around the globe need to look at alternatives to rainwater supplies. Given that the plant is a necessity, t he design and construction teams are determined to build it efficiently, to minimise environmental impacts as much as possible, and to see it make a difference to the water eq uation as soon as possible.

The plant will occupy just 38 hectares of the 263 hectare site. The remainder of the area will see one of the largest single ecological restoration projects of its kind ever undertaken in Victoria.

*About AquaSure AquaSure brings together three companies, all leaders in their fields:

• Thiess - one of Australia's largest and most tru sted construction and services companies

• Degremont - a SUEZ ENVIRONNEMENT company and world leader in reverse-osmosis desalinat ion t echnology

• Macquarie Capital - t he world 's strongest and most experienced infrastructure advisor.

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refereed paper

ADELAIDE DESALINATION PROJECT PILOTING EXPERIENCE M Blaikie, C Pelekani Abstract Media filtration has historical ly been the preferred pre-treatment process for seawater desalination , however ultrafiltration (UF) has emerged as a viable option. The Adelaide Desalination Pilot Plant facilitated operating comparisons of conventional and UF pre-treatment. Silt density index (SDI) and flow cytometry were utilised to characterise system performance. Differential pressure profiles provided useful information on fouling and cleaning efficacy. UF was fou nd to provide superior filtered seawater quality (98.5% SDl 15 below 3.5 and 90% below 3) and far more efficient microbial removal. Media filters required significant ripening for SDl 15 to stabilise below 3.5. Membrane fouling was controlled despite forced operating challenges.

Introduction Project background The Adelaide Desalination Project (ADP) was announced by the South Australian government in December 2007, including the construction of a 50GL seawater desalination plant and associated works. Since the announcement, the First Water date was accelerated by 12 months to December 2010, and the plant capacity doubled to 100 GL. Full production from Stage One (50GL) is scheduled for August 2011 , with Stage Two (1 00GL) online by December 2012. The plant will be located at Pt Stanvac, 30 km SW of the Adelaide central business district. The ADP is being delivered by AdelaideAqua (AA) under a Design, Build, Operate, Maintain (DBOM) contract. The AA consortium includes Acciona Agua, McConnell Dowell, Abigroup and United Utilities. The Transfer Pipeline System (TPS) is being delivered by McConnell Dowell in joint venture with Built Environs and will convey the desalinated water into the distribution system at the Happy Valley Water Filtration Plant. AGL successfully tendered for the energy contract and will supply 100 % of the plant energy requirements from renewable sources. The ADP will be the first large-scale munic ipal seawater desalination plant to

46 JUNE 201o water

Conventional Pre-treatment

Residu als Management

Reverse Osmosis

Laboratory (Corrosion Monitoring)

Chemical Dosing Containers

Membrane (UF) Pre-treah11ent

Post Treatment

Figure 1. Adelaide Desalination Pilot Plant Layout. utilise submerged ultra-filtration (UF) for pre-treatment. In February 2008, the SA government approved $9.5M for t he design, construction, operation and maintenance of the Adelaide Desalination Pilot Plant (ADPP). The plant would facilitate testing of various technologies, gather data on raw and process water quality and generate samples for environmental testing. Water Infrastructure Group (WIG) won the contract and was granted full site possession in June 2008. All systems, except the reverse osmosis (RO) and post-treatment, were operational by August 2008. The plant was fu lly operational in December 2008. The ADPP is located 1km south of the full-scale plant.

Pilot plant design The ADPP intake pipe is 1,620 m long with seawater abstracted from a depth of 15 m. It is situated within the intake corridor of the full-scale plant. The intake is capable of delivering 570 kUday at a

Comparison of conventional and membrane pre-treatment for seawater RO. -

maximum inlet velocity of 0.15 m/s. The intake structure incorporates a 15 mm copper/nickel screen to minimise biogrowth. Either of two pre-screening devices, a 60 µm 'baleen ' filter or a 500 µm Amiad strainer, were available to filter the seawater before entering t he raw water tank. The plant is able to simultaneously operat e two pre-treatment systems: a Norit Seaguard™ pressurised UF system and a conventional pre-treatment system (coagulation, flocc ulation, sediment ation, media filtration). Each pre-treatment system is capable of producing more than 250 kUday of filtered seawater. The RO system can be fed by either or both pre-treatment systems. The RO plant is capable of producing 100 kUday of permeate through a partial two pass system. The first pass was designed to operate at 40 - 50% recovery, with 50% of the First Pass permeate polished through a two stage second pass operating at 90% recovery. The system incorporated an ERi PX-30 energy recovery device and in the first year of operation employed 'extra high boron rejection ' elements in the first pass (XHR400i; Dow Filmtec). The final permeate stream undergoes post-treatment remineralisation. Carbon

technical features

desalination & membrane technology

refereed paper

dioxide and hydrated lime are added to the permeate to increase alkal inity, adjust the pH and reduce the corrosivity t hus producing drinking water compliant with the Australian Drinking Water Guidelines (2004). A corrosion testing rig faci litates assessment of desalinated water impact on pipes in t he dist ribution system, electric hot water systems and selected materials in customer services (copper, brass, mild steel). Dirty backwash water from the multimedia filters (MMFs) and the UF is clarified to remove solids. Supernatant is blended with other process streams before discharge to t he outfall. Sludge is trucked off site. A dechlorination system employs sodium bisulphite neutralisation of ch lorinated waste streams generated from periodic UF membrane cleaning. All process streams (clarified supernatant, permeate, concentrate, product water and surplus filtered or raw seawater) are blended and ret urned to the ocean through a 600 m long outfall pipe. Water quality paramet ers are measured on-line and via manual sampl ing to ensure compl iance with environmental discharge requirements. Figure 1 shows a photograph of the Adelaide Desalination Pilot Plant with subsystem locations.

under alternate pre-screening (type and screen size). • Opt imisation of t he dechlorination system to minimise deoxygenation. • Outfall dispersion characteristics during dodge tide using Rhodamine dye. • Performance assessment of UF and conventional pre-treatment systems (CPT). • Corrosion characteristics of postt reated desalinated water. • Generation of process streams for ecotoxicity testing. • Microbiological water sampling to characterise biolog ical fouling 'hot spots' in the system.

Process and Analytical Methods Conventional pre-treatment system (CPT)

The CPT was designed for 250 kUday net filtered seawater production. The system comprised coagulation using ferric sulphate, two stage f locculation, lamella clarificat ion and multimedia filtration. LT25 (Ci ba Magnafloc) polymer could be dosed before the flocculation tanks and/or the M MFs.

Pilot studies

The CPT could be operated in 3 distinct modes:

During the first year of operation studies included:

• Full conventional - coagulation, flocculation, clarificat ion, MMF.

• Characterisation of inlet seawater quality (chemical, physical, microbial).

• Contact filtration - coag ul ation, flocculation, MMF

• Operation of First Pass RO at elevated pH to improve boron rejection and monitor fouling potential.

• Direct filtration - coagulation, MMF

• Scanning Electron Microscopy and particle sizing analysis of inlet water 6 ~ --

The MMF design consisted of two pressure vessels with the following media composition: 200 mm of 0.3 mm ES garnet, 300 mm of 0.5 mm ES sand and

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• Aut o SDI 15

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Figure 2. $D115 and differential pressure for conventional pre-treatment by MMF run time.

750 mm ES coal. This is a similar compositio n as that used at Penneshaw Desalination Plant (Kangaroo Is ., SA). A conservative loading rate of 8 m/h was adopted. In normal operat ion the MMFs were set to backwash when t he different ial pressure (DP) in either of the media vessels reached 45 kPa or when the filtrat ion time reached 4,300 minutes (approx. 3 days). Backwashing consisted of both low and high MMF filtrate flow with air scour. There was no chemical addit ion to the backwash water. Jar testing and limited initial optimisation of the CPT led to the selection of a ferric sulphat e coagulant dose of 8 mg/L for ful l conventional pretreatment and 2 mg/L for direct and contact fi ltration. Ultrafiltration pre-treatment system (UF)

The UF was designed for 250 kUday net filtered seawater production. The system comprised 2 two-element pressure vessels. Normal operating flux was 84 LMH. Nominal filtration t ime was 30 minutes between backwashes. In normal operation, chemically enhanced backwashes (CEBs) were performed after 17 backwash cycles but this was varied during trials . During each CEB a hypochlorite soak/flush (200 mg/L; pH 10.2) fol lowed by sulphuric acid soak/flush (pH 1.8) was initiated with variable soak times selectable for each CEB so lution. Clean in place (CIP) was initiated when UF fouling could not be contro lled by routin e backwash and CEB. Both a citric acid 2% w/v solution (with pH adjusted to two with sulph uric acid) and a 1% w/v oxalic and 0.25% w/v ascorbic acid sol ution were used. Analytical methods

Filtered seawater quality was measured using silt density index (SDI) based on ASTM 0 4189-07. SDI analysis of both CPT and UF fi ltered seawater was possible using manual apparatus or with an automatic unit (MABAT SDl-2200, Israel). In addition, online turbid ity measurement and weekly water quality sampling was employed to further characterise filtered seawater quality. Microbiological characterisation of the filtered seawater samples was achieved through f low cytometry analysis. Flow cytometry uses a laser light source to count the number of cells per ml in a water sample. The light is scattered by t he cells as they pass through the beam

water JUNE 2010 47

desalination & membrane technology one at a time and a cell count can be calculated. Dead and live bacteria are differentiated using a preferential dye stain. Trans-membrane pressure {TMP) & DP measurements provided useful information on fouling and backwash/ CEB efficacy. DP across the MMFs was measured onl ine. TMP across the UF was calculated from onl ine DP measurements providing a temperature corrected indication of pressure loss.

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refereed paper

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Silt density index (SDI) SDl 15 profiles from the CPT are shown in Figure 2. Results are plotted against filtration run time. The SDl 15 results are at a maximum immediately after a backwash (fi ltration run time=O) and progressively decreases as the filter ripens. SDl1 5 was observed to decrease below 4 after approximately 150 min (2.5 hours) filt ration, below 3.5 after approximately 500 min (8.3 hours) fi ltration and does not stabilise below 3 until 2,000 min (33 hours) of filtration. Operation of t he CPT in the three different filtration modes did not significantly influence SDl 15 profiles (Figure 3). The outlier values are likely to be caused by filter breakthrough due to excessive coagulant dose or other process upset. The effect of filter- aid polymer dose on filter ripening t imes was evaluated in d irect filtration mode. Polymer doses of between O - 0.04 mg/L (0.01 mg/L increments) were tested. No discernable impact was found for either ripening t ime o r SDl 15 profile. SDl 15 data from the UF pre-treatment is illustrated in Figure 4. Unlike the CPT, the UF SDl15 data is not influenced by filtration time as there is no ripening time associated with UF. This is reflected in early data plotted against backwash cycle number (Figure 5). The SDl 15 observed for the UF pretreatment remai ned below 4 for all recorded data with 98.5 % of the data below 3.5 and 90% below an SDl 15 of 3 . SDI was found to be a far more sensitive measurement of filtered seawater quality than turbidity which was stable in the 0.03 - 0.05 NTU range . Interestingly, manual SDI measurements tended to be lower than those from t he automatic unit. Th is may be attributed to variation between the

48 JUNE 2010 water

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Figure 3. S01 15 for different modes of conventional pretreatment by MMF run time. 0.6 • UFAutoSDl15 o UF Manual SDI 15

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would be expected to have higher repeatability.

technical features

refereed paper

desalination & membrane technology

UF filtered seawater. Clarified seawater samples were only available when the CPT was operating in Full Conventional mode. Flow Cytometry analysis provided cells/ ml counts for each process stream. Bacterial counts from each pre-treatment sample were compared with t he raw seawater bacterial count and Log removal values (LRVs) were calculated. The data is illustrated in Figure 6.

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LRVs for the UF are consistently higher than those observed for the CPT. The UF displayed an average LRV of 2.75 (99.8% removal) compared with a LRV of 0.8 (84.2 % removal) for the CPT. When the CPT was operated in Full Conventional mode (fou r samples only) no appreciable log removal by the MMF was observed (i.e. LRV after clarification was similar to t hat after MMF filtration for samples taken over the same period and both compared w ith raw seawater).

Differential/trans-membrane pressure Figure 2 includes a trend of DP versus filtration time for the MMF. Backwash was set to occur once t he DP exceeded 45 kPa. Result ant filtration ru n ti mes were in the range of 2,800 to 4,300 minutes. The average run time was approximately 3,500 minutes. Backwash was able to consistently reduce the DP to 4 kPa (consist ent with starting DP at com missioning). Operating mode did not affect backwash performance. Typical SCADA screenshots of UF TMP and backwash/CEB f low trends are shown in Figure 7. In this case 18 filtrat ion cycles of 30 minutes d uration can be observed between each CEB. A backwash takes place after each filtration cycle.

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Ave. TMP increase over CEB cycle (kPa}

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0.12

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Ave. unrecoverable TMP increase over CEB cycle (kPa} seq uences (with backwash) between CEBs was varied. The number of these fi ltration cyc les is also shown on Figure 9 as horizontal purple bars. During some periods of UF operation t he number of filtration cycles was not stable due to a range of operat ional issues. This is most evident in early operation as displayed by the wide scatter in filtration cycle number.

Three periods of relatively st able operation were achieved with 17, 15 and 23 filtrat ion cycles between CEBs. During these times no major operating changes or process upsets occurred . These periods are highlighted in Figure 9 . A summary of the TM P trends for t hese periods is illustrated in Table 1.

Figure 9 illust rates a history of the UF TM P trends by totalised filtration time (post co mmission ing). The increase in TMP between consecutive CEB cleans is shown as a red bar. Decrease in TMP attri buted to CEB cleans is shown as a blue bar. Operating TMP d irectly after CEB is shown in g reen. An increase in t he 'Starting TM P' t rend denot es that the increase in TM P over a CEB cycle is greater than t he red uction achieved by the CEB at t he completion of the cycle. Th is is defined as an unrecoverable TMP increase over a CEB cycle . During the t rial period the number of 30 min filtrat ion

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In general, w ith good feed water quality, no coagulant dosing and stable operat ion, the average TMP increase over a filtration time of 6.5 to 7 .5 hours (15 - 17 filtration cycles) was 5.7 - 6.4 kPa. Most of this increase was recoverable through CEB. For a filtration time of 11 hours (23 filtration cycles) the average TMP increase was higher at 14 kPa. Most of t he increase was observed over the final fi ltration cycles and CEB was not as successful at recovering TM P. Immediately after commissioning the starting TMP of the UF was approximately 20 kPa. This can be considered as the baseline TM P for clean and unfouled membranes.

Baseline recovery of pre-treatment systems

Figure 7. SCADA screenshots of UF TMP trends. (TMP in red, backwash/CEB flow in blue).

The basel ine recovery of each pre-treat ment system can be calculated as: volume of filtered

water

JUNE 2010 49

desalination & membrane technology water less volume of water used for backwash and/or CEB. This does not take into ac count filtered seawater quality.

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Filtered seawater quality is extremely important for RO. A superior feed water quality (low SDI) can extend t he life of the RO membranes, minimise energy consumption and maintain low salinity of the permeate.

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Six to eight hours to achieve 100% SDl15 below 3.5 is reasonab le for single stage media filtration . However t he tig ht er target of SDl 15 less than three is diffic ult to achieve and requi res significant ripening . This is where UF is

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12.0

Discussion and Analysis

Fro m the perspective of baseline feedwater recovery, the MMF (and CPT as a whole) performs better than the UF system. However, when water quality (SD1 15) is taken into account the recovery reduces substantially for the MMF. Table 2 summarises the effect ive recovery of each pre-treatment system for defined RO feed water quality targets.

A summary SDl 15 comparison between CPT and UF is shown in Figure 8.

refere ed paper

16.0

For 16 backwash cycle UF operat ion t he baseline recovery of the UF is 89% . For a 3,500 minute MMF filt ration cycle t he baseline recovery of the CPT is 98.9%.

SDl 15 is used by membrane manufacturers as t he primary specification for RO feedwater quality. Membrane warranties are often invalidated at a feedwater SDl 15 of greater than 5. However, RO plant specifications are often considerably t ighter t han this. The ADP project requires 100% SDl 15 less than 4 and 95% less t han 3. Th is is considered a c hallenging feed wat er quality target.

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superior with performance independent of filtration time.

particles and removed in the clarifier sludge.

Biolog ical fouling is also a major contributor to sub-opt imal operation of RO systems. Pre-treatment is important in minimising t he bacterial load to t he RO membrane surface.

The abil ity of UF to achieve close to 3 log removal of c ells is likely to be an advantage in t he control of RO biofouling.

Flow cytometry data revealed that UF achieved significantly higher removal of microbial cells. For t he CPT LRV was consistently less t han 1. From the limited amount of dat a when bot h c larification and media filtration were operating , it is evident that very little removal occurred in t he MMF. It is possible that most of t he removal of microbial cells is through the introduction of coagu lant and that as a result cells are captured in floe

Ultra-filtration trans-membrane pressure tre nd Duri ng the pilot testing of t he UF, attempt was made to challenge the system and observe its response. Isolated faults provided additional information regarding robustness of t he UF. Figure 10 illustrates the same UF TMP trend shown in Figure 9 w ith events of interest highlighted.

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Table 2. Effective feed water recovery for UF and CPT as a function of S0115. Recovery No SDl 15 spec.

100% SDl15 < 4.0 95% SDl 1s < 3.5 95% SDl1s < 3.0

JUNE 2010

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technical features

desalination & membrane technology

refereed paper

The first 56,000 minutes of filtration saw relatively unstable operation with large variation in filtration cycles between CEBs. This was largely due to extensive investigation and optimisation of the Dechlorination system during this early period. As a result, the dechlorinati on system was often off-li ne which would inhibit CEB. The TMP trended upwards during this period as extended filtration periods between CEBs resulted in unrecoverable fouling. A rapid upward trend in TMP was observed after 88,000 minutes of filtration time (Figure 10, star labelled "3"). A fault in the hypochlorite dosing system went undiagnosed for a period and Hypochlorite CEBs did not occur as a result. It is evident that the loss of chlorine exacerbated organic and biological fouling. Increasing the duration of the CEB soak time (from 10 to 20 minutes) was often able to reverse an observed TMP rise. Extended CEB soaks were initiated at various stages denoted by the arrows labelled "1" (Figure 10). In most cases this decreased the TMP back to baseline

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unable to restore membrane condition. Increasing the CEB soak duration was not able to counteract the fouling. It is likely that because the feed water quality was good (low DOC and turbidity) there was nothing for the Fe3 + to bind to, causing reaction with the membrane surface. Chemical cleaning using citric acid was performed twice during the trial period. CIPs are denoted by red arrows labelled "2 " in Figure 10. Citric acid CIPs were performed with a 2% w/v solution with pH adjusted to two with sulphuric acid. The solution was recircu lated for 30 minutes, left to soak overnight then recirculated for an additional 30 min prior to fl ushing. The first citric acid CIP was successful in reducing the TMP significantly. However, the second citric clean was only able to reduce the TMP t o 40 kPa (compared with 20 kPa for clean UF). This was attributed to excessive fouling from the ferric coagulant trial.

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In April 2009 a CIP was performed using 1 % w/v oxalic and 0.25% w/v ascorbic acid. This is illustrated in Figure 10 at the end of the trial period. The CIP was successful in reducing TMP to baseline levels. Starting TMP was observed at below 20 kPa after the clean. Oxalic acid is a powerful reducing agent and more effective than citric acid in removing iron foul ing. Ascorbic acid stabilises the oxalic acid structure but does not play an active role in removal.

Conclusion: Conventional Vs Membrane (UF) Pre-treatment Th e CPT produced acceptable filtered seawater quality (SDl 15 less than 4) after 2.5 hours ripening time. However, given a more challenging water quality target, the system was unable to perform adequately. The effective recovery was significantly reduced due to excessive filter ripen ing duration.

conditions, although the UF required more specialised cleaning chemicals to achieve ful l performance recovery. Improved performance and extended life of RO membranes is likely with better quality feed water and less biofouling potential. For these reasons it is evident that UF is a superior pre-treatment method for seawater RO.

Acknowledgments The work reported here could not have been completed without the contribution of Jek Rozitis (Process Engineer, SA Water) to the Pilot Plant day to day operation, monitoring and analysis. In addition, the assist ance and support from John Winter and the rest of the team at the Australian Water Quality Centre was gratefully appreciated .

The Authors

M att Blaikie (B.E. Civil/Environmental, BSc.) is a Water Treatment Engineer and Con Pelekani (B.E. Chemical, M.Sc., Ph.D.) is Principal Water Treatment Engineer with the South Australian Water Corporation. Both are members of the Process Team for the Adelaide Desalination Project. Email: matt. blai kie@sawater.com .au.

Glossary ADP - Adelaide Desalination Project ADPP - Adelaide Desalination Pilot Plant CEB - Chemically enhanced backwash CIP - Clean in place CPT - Conventional pre-treatment DP - Differential pressure

In contrast, UF was able to produce superior filtered water quality independent of filtration time. SDl 15 was observed to be less than 3.5 for 98.5% and less than three for 90% of data considered. In addition, UF achieved far greater removal of microbial cells from the raw seawater feed.

SDI - Silt density index

Both systems were able to recover well from challenging operating

TMP - Trans-membrane pressure UF - Ultra-filtration

ES - Effective size LRV - Log removal value MMF - Multi-media filter RO - Reverse osmosis SCADA - Supervisory control and data acquisition

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technical features

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Tenix Alliance

TenixÂˇ Level 5, 600 St Kilda Road Melbourne VIC 3004 Phone: 03 8517 9000 Fax: 03 8517 9062 Paul Miller - Business Development Manager, Water Tenix Alliance provides innovative water, wastewater, recycled water and drainage infrastructure solutions, tailored to meet the needs of an increasingly challenging market. With over thirty years experience in the water sector, we provide cradle-to-grave services for water infrastructure delivery, including project management, design, construction, commissioning, operation, maintenance, rehabilitation and asset management. Customers include water corporations, councils, irrigation companies, power generators, food and beverage manufacturers, and mining and resources companies.

15-19 Kialba Rd (PO Box 1639) Campbelltown 2560 Tel: (02) 4626 5000 Fax: (02) 4625 4591 Email: sales@teralba.com Web: www.teralba.com Contacts: Alan Baker; Greg Haak, Sales Manager; Heat Exchangers: Andrew Baker; Mixers: Brent Ovenden Established in 1976, Teralba Industries design and manufacture Dimpleflo tubular heat exchangers, in stainless steels and titanium, to process viscous, slurried and difficult products. Dimpleflo tubular heat exchangers are used to heat sewerage sludge for anaerobic digestors. Teralba also produce under license in Australia, Mueller Accu-Therm plate heat exchangers. A range of Mixquip Agitators and Mixers completes a full range of locally made and internationally sourced fluid process equipment.

The Reed Group

f;Jddâ&#x20AC;˘I Level 3, 41 McLaren Street, North Sydney NSW 2060 Tel: 02 9965 0399 Fax: 02 9955 8812 Web: www.reedgroup.com .au Contacts: Norman Esber E: nesber@reedgroup.com.au Bernie Mitchell E: bernie.mitchell@reedgroup.com.au The Reed Group services the water sector with a diverse skills base with strong engineering, construction and project management skills. Expertise extends from design and construction of water and wastewater plants to tunneling, reservoirs and membrane technology. The Reed team can undertake complex projects with a sound understanding of civil implications. Success is based largely on The Reed Group's commitment to sound project delivery with strong technical credentials.

C&S BRAND AUSTRALIAN FILTER COAL GRANULAR MEDIA FILTRATION FOR DESALINATION PRETREATMENT Reliable Quality and Service from a Company with more than 100 years of experti se in the manufacture of Coal and Carbon Products for Australian Industry

C&S BRAND GRANULAR & POWDERED ACTIVATED CARBONS JAMES CUMMING & SONS PTY LTD 319 Parramatta Rd, AUBURN NSW 21 44 Phone: (02) 9748 2309 Fax: (02) 9648 4887 Email: jamescumming @jamescumming.com.au Website: www.jamescumming.com.au

I auanry

............ ISO 9001

Uc No. 1628

QUALITY ENDORSED COMPANY AS/NZS ISO 9001 SAi GLOBAL

water

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TREATM ENT OF COAL SEAM GAS WATER S Chalmers, A Kovse, P Stark, L Facer, N Smith Abstract Th is paper reports on the design, delivery and operational aspects of several recently executed Integrated Membrane Systems (IMS), used for desalination of produced water from the rapidly expanding Coal Seam Gas (CSG) Industry of the Surat and Bowen Basins in Queensland.

Introduction Coal Seam Gas (CSG) now accounts for approximately 80% of the gas used in Queensland, a remarkable achievement given that the first commercial production of CSG was 10 PJ in 1999 and usage has approximately doubled each year to the current levels in excess of 200 PJ/annum. A number of proposals are being developed to build Liquefied Natural Gas (LNG) facil ities at Gladstone using CSG as the feedstock, thereby providing a valuable export. The first exports of LNG are expected t o begin in 2013, with around 10 million tonnes being shipped. This will req uire 550 PJ of CSG, more than twice the domestic consumption, and could be as high as 3,250 PJ/annum by 2015 if all proposed LNG projects proceed (Queensland Government 2009). For many of the CSG fields , water is present over the coal deposit and in the coal cleats or fractures. Gas production

water Future Features AUGUST - Water treatment, advanced oxidation, demand management, international projects SEPTEMBER - Wastewate r treatmen t, water sensitive urban design, environmental water man agement NOVEMBER - Odour management, membrane processes, customer service

is initiated by lowering the pressure in the coal seam, by pumping off the water contained in the cleats, allowing the gas to 'desorb' from within the coals and flow to the surface. CSG production will typically involve a large flow of water initially and as the gas production ramps up, the water flow wi ll diminish. The water is highly variable and differs significantly not only from field-to-field, but also withi n the field itself from wellto-well and over the life of the wells. It can be moderately brackish to saline, with a wide range of potentially fouling/scaling constituents including high-suspended solid levels, metals, silica, and other ions. It typically contains significant levels of sodium, bicarbonate and chlorides (Van Voast - 2003). Unless influenced by surrounding aquifers or surface aggregation ponds they are often low in sulfates, calcium and magnesium. The potential for beneficial use has been discussed by Oldridge and What man, 2009. Potential environmental harm and practices associated with the management of the produced water are issues recog nised by the Queensland Government. The Department of Envi ronment and Resource Management (DERM) have responded with a series of policy guidelines to assist the CSG producers with disposal of the produced water, which aims to balance the need for environmental protection and the interests of regional communities and agricultural stakeholders, and devolve the responsibility onto the producer. Methods of dealing with the water range from direct discharge t o receiving waters, re-injection , evaporation ponds, irrigation and even urban supply, all depending on the water quality and location. The factors determining the method have been discussed by Mannhardt and Cameron, 2009. Most options req uire treatment to varying extents. The requi rement is generally for a non-specific separation process to desalinate or red uce ionic constituents, which gives the CSG producer options for water disposal, and the opportunity for beneficial reuse.

Membrane Systems for Desalination Piloting In 2004 Origin Energy began to formalise its water management strategy for the ir 'Spring Gully' CSG developments, north of Roma in the Bowen Basin, Queensland.

To further qualify the suitab ility of various treatment technologies and fully quantify the operational aspects of any proposed facility, a pilot trial was proposed. In line with local and global experiences, Reverse Osmosis (RO) membrane systems were identified as the most cost-effective method for reduction of the dissolved solids or salts. However, traditional spiral wound RO membrane systems requi re a feed that is virtually free from suspended particles or particulates. Therefore, assessment of a cost-effective and robust pre- t reatment process step became an important piloting objective, as well as proving the ability of the RO itself to produce water of acceptable quality. Pre-treatment technologies piloted included a hollow fibre microfi ltration (MF) system, in combination with dissolved air flotation (OAF) w ith and without appropriate coagulants/additives, sand fi ltration (SF), and ion exchange (IX) - wh ich was also investigated as an adjunct to acid dosing for control of calcium carbonate scaling in the RO unit. Pall Corporation was engaged to deliver a portable and purpose-built Integrated Membrane System (IMS) trial unit which was designed for complete automatic and unattended operation. T he unit was built with a very high degree of instrumentation to allow monitoring and logging of all process variables across both the MF and RO systems, and process flexibility to allow operation under a wide range of trial cond itions. Trials were conducted at two different fields for a duration of 6 months each. The emphasis of the trials was on a full

Pilot and full-scale experience. water JUN E 2010

desalination & membrane technology evaluation of the IMS technologies to fully understand the interdependency and limitations of each process, to allow designs to be developed for a robust and full scale facility.

refereed paper

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Microfiltration system evaluation Although able to deal with potentially large concentrations of fine suspended particles and organ ic matter, MF systems must be protected from ingress of large debris of solids. It became clear that a full-scale IMS facility should incorporate an automated self-cleaning 400 micron coarse strainer. The main objectives during the MF system evaluation phase of the pilot were to qualify that the filtrate produced was of appropriate quality to be sent to the RO system, as measured by Silt Density Index (SDI) values directly, and indirectly via online turbidity measurements. Secondly, to qualify stable operation and quantify operational and design conditions including flux (flow rate/ membrane surface area) usually expressed as LMH - litres per metre squared - hour, process unit recovery, air scru b and reverse flow (backwas h) flow rates and intervals, and t he need for any ongoi ng maintenance chemical cleaning. Results have proven that the filtrate quality throughout the trial was of sufficient quality to be presented directly to a spiral wound RO system, as expected, with SDI Values <3 and onl ine tu rbidity measurements of <0.1 Nephelometric Turbidity Units (NTU) (typically <0.02 NTU). It became apparent during the early phases of the Trial that the MF syst em would benefit from an Enhanced Flux Maintenance (EFM) regime, in addition to a more frequent (every 15-20 minutes) air scrub and reverse flush procedure. These steps were needed to provide the required volumes of fi ltrate to enable consistent operation of downstream RO processes. This is due to high levels of fou ling constituents including significant biological and organic foulants (in some cases algal loads > 1 million cells/ml) , and the corresponding rate of rise in Transmembrane Pressures (TMPs). The EFM process is a proven and extremely useful tool to minimise the effects of high variability feedwaters , and is only possible due to the advances in fluoropolymer chemistry and the manufacturing process of this specific highly porous membrane that increases its chemical compatibility, and physical strength for use over long periods. With increased understanding of cleaning

72 JUNE 2010 water

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Figure 1. RO operation - inorganic scaling. processes, it is recognised that the mass transfer of chemicals through the fouling layer and the reaction kinetics of chemicals regulate cleaning efficiency. Partially fouled membranes are a lot easier to c lean than completely fouled membranes (Chang et al., 2002). As such, the EFM process can be designed and engineered as a frequent or daily automated routine operation without operator's intervention, and the short, dilute and warm processes dramatically increase the ability of the system to handle highly foul ing and variable waters This was proven during pilots at both sites over 2 x 6 month durations, where a caustic/hypochlorite EFM process was performed frequently and in some cases daily.

Reverse osmosis system evaluation The membrane pre-treatment detailed above enabled trials to proceed on the RO system with a focus on understanding the scaling potential, as well as developing operational strategies and design parameters to manage the associated risks of a desire for high recoveries across the RO process. Additionally, it was to determine the propensity for biofouling and again develop a management strategy to be implemented in any full-scale designs. The RO unit was trialed over a range of conditions, again looking for limitations. "Scaling" is typically managed by controlling permeate output or ' recoveries' and addition of acid and/or special "antiscalant" chem icals. Initially, conservative parameter val ues were used, then t hey were gradually relaxed to reduce chemical consumption and maximise permeate output or recoveries. All reverse osmosis systems are limited

in the range of recoveries t hat can be achieved for the waters being treated. The limitations are a result of a fixed vessel/element array configu ration combined with the membrane element flow rate and pressure limitations. The system piloted was a 2-stage configuration, utilising inter-stage pumping with recycle capability on stage 2 to simulate a t hird stage operation. The first stage comprised of one effective vessel complete with six x 4" RO membranes. The second stage comprised of one effective vessel of four x 2.5" RO membranes. This system provides extreme f lexibility by enabling the "wastage" of some of the stage 1 RO concentrate, thereby enabling full flexibility in modifying the f lux balancing between stage 1 and stage 2 of the array (subject to membrane flow and pressure limitations only). Full scale designs would not normally have this feature. Recovery on the system was restricted to a maximum of about 82% due to flow rate limitations of the pilot plant and to not over-pressurise the RO vessels. This also seems to be c lose to an economic optimum - as scaling potential approaches the maximum recommended values. To determine if inorganic scaling is occurri ng, t he following sympt oms are expected: 1) a decrease in normalised permeate flow and 2) an increase in salt passage (detected by online conductivity instrumentat ion in the 2nd stage RO). Evidence of organic and/or biological fouling would typically be indicated by an increase in t he pressure drop from the feed to concentrate side of t he membrane, and often presents initially on the first elements (or 1st stage RO).

technical features

r e fereed pa p e r

desalination & membrane technology

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Figure 2. Origin Energy Spring Gully facility process flow diagram. During t rials, the RO system required a Clean-In-Place (CIP) once every month for inorganic scale removal and it was concluded that a suitable "non -oxidising" biocide needed to be dosed to control t he bio-film. The normalised t rends did not show any detectable sign of inorganic scali ng. A daily pattern is a result of t he daily RO permeate flush com bined with the d iurnal temperature changes. This pattern was repeated throughout the majority of t he t rial , until increased recoveries and reduced antiscalant dosages provided evidence of an inorganic precipitat ion or 'scal ing event' (as shown in Figu re 1 ).

Full-Scale IMS Process Design All th ree CSG IMS facilities t hat were designed (two currently are in operation), essentially have simi lar process designs based o n the piloti ng work detailed above, with Origin 's Spring Gully process detailed in Figure 2 . Within the process flow diagram the feed ponds t hemselves serve as a process unit wit h several important functions: • Temperature reduction - feedwater temperatures must be below 40°C before entering IMS facility • Hydraulic buffer - allows balancing of flows and in the event of plant unavailability, allows continuation of prod uction of CSG. It also provides a buffer for the variabil ity in water prod uced from the wells to ensure the IMS can operate continuously • Stabilisation of alkalinity - as small amounts of CO 2 (and gas) are liberated w ithin the ponds, t he pH is increased

tend ing to convert t he bicarbonates into carbonates , and the associated precipitation of select cat ions increases overall stability of t he water and lowers the scaling potential • Oxidation of metals - particu larly iron and manganese, which can otherw ise be limiting factors with in the process • Isolation in the event of incompatible fluids and/or hydrocarbons being present in the feed ponds. They also allow segregation of wastes and brine, which may provide future opportu nities for reprocessi ng and/or further brine concentration or salt recovery. However, algal growth can occur, w hich increases the load on the pretreatment system. Feedwater is drawn from Pond 2 by floating pontoon pumps wit h variable depth inlets, controlled by the central control system and main Progammable Logic Control ler (PLC). These pumps supply water to the plant that is first passed t hrough coarse strainers and then through the MF racks and membranes themselves, before entering the filtrate buffer tank, or RO feed tank. A flow control valve on the filtrate line is used t o control f low on each MF rack, to maintain tank level in the small buffer tank, and proportionately balance flux across available online racks when in filtration sequence, and also when one (or more) racks temporarily unavailable for req uired flux maintainence (backwash) o r EFM procedures. Low pressure pumps t hen feed water to the main RO systems, where it is dosed with the requ ired antiscalant and intermittently with a non-oxidising biocide. Additionally, the water is filtered again t hroug h "policeman " or "last chance" on-

skid cartridge filters of horizontal flow through design (to minimise chances for biofouling w ithin these vessels) to again ensu re no particulates are presented to t he RO membranes that may h ave been entrained between the MF and RO systems, or leftover during initial commission ing processes. The RO systems are a 3-stage tapered array design, with HP booster pump prior to st age 1 and interstage boosting pumps between stages 1 &2 and 2&3. They are specifically designed in response to projected water variabil it ies and piloting design inputs, and al low for a high level of control for f lux balancing and to adjust recoveries as req uired, w hich can be between 75-85%. Minimised power consumption was not only a design requirement for corporate environmental com pliance, but also required because the gas fired power generators were a critical path item for overall project schedule, and t he more read ily avai lable units set t he overal l plant consumption, and necessitated an efficient sol ution. Finally, the Orig in Energy Spring Gully RO unit has t he ability to bypass the thi rd stage. Under high feed water TDS and/or low water temperatures, the RO system recovery wi ll be limited. Under these circumstances, the third stage can be bypassed to conserve the membrane life and protect it from membrane scaling/fouling . The process design for Arrow Energy's cont ainerised IMS (two separate trains of 6 MLD each) uses the same proven design principles, but the process units (and a significant amount of supporting anc illary devices, i.e. - Motor Control Centres (MCC's), Clean in Place (CIP)

water JUNE 2010 73

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and compressed air systems) are enclosed in standard shipping containers to enable relocat ion at a later date, if required (see Figure 3). The third CSG IMS facility at Origin's Talinga Development, near Chinchilla, also in the Surat Basin, in corporates a weak acid cation IX system to remove scaling constituents between the MF and RO systems, and a secondary high recovery RO system as a final "brine recovery" step, further minimising the concentrate volumes and pondage required. Origin's Talinga site is now being com missioned.

Figure 3. Arrow Energy 'Daandine' Development Containerised IMS facility.

Full-scale IMS project execution Origin's Spring Gully IMS project was desi gned, fabricated, supplied, and commissioned in approximately 11 months, which would generally be considered to be 'fast tracked' . Due to the tight project schedule, complexity of the plant and integral importance of a successful outcome in delivery of the water treatment faci lity for the overall Spring Gully Development, both Pall Corporation and Origin Energy recognised the need to work together closely throughout the project. Both parties were jointly responsible for the development of the final plant layout, which was designed in conjunction with Origin Energy's operational personnel's input and support - in order to deliver a worl d c lass facil ity that is easy to maintain and operate in a remote location.

• Coarse filtration system • Microfiltration systems • Reverse osmosis systems • Chemical pre-treatment and dosing systems • Clean-in-Place (CIP) systems • Compressed air systems

• Civil construction (building, concrete, pondage, collect ion network, and IMS facil ity pipelines) • Gas fired power generator supp ly and installation

• Supervisory Contro l and Data Acqu isition (SCADA) systems

• Bulk chemical storage systems

• Motor Control Centre (MCC) and electrical panels

• Floating pontoon feed pumps and localised control

• Interconnecting pipework design and supply • Commission ing services and documentation. The emphasis was on pre-assembled and skidmounted systems where possible, to reduce t he t ime and cost associated with on-site labour, and to maximise the amount of factory acceptance testing work that can done prior to shipment to the site. Origin Energy's internal project staff performed a primary contractor role, which included overall project management, interfacing

The design allowed for an initial capacity of 9 MLD, easi ly upgradable to 12 MLD (which was done in 2008) and possi ble expansion to 15 MLD. The project included responsibility for process and eq uipment design and selection, as well as fabrication, supply, and com missioning of the following:

with all supplied equipment and integration of all onsite services, and scope including:

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• El ectrical installation • Overall site and project management. The facility has remote telemetry links, all owing not only remote supervision and monitoring, but the system will also automatical ly notify on-call operators of any alarm conditions present requiring attention and operator involvement. As such, and to t he maximum extent possible, this and al l subsequent projects and provided IMS skids are heavily automated with a very high degree of inst rumentation that wi ll allow ongoing optimisat ion and continual improvement of operational aspects. The plant wide SCADA system al lows t rending of a wide range of process and su pport equipment information via remote and centralised PLC control systems.

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The Spring Gully IMS faci lity was brought onli ne on Dec 23, 2007 and has been operat ional since that time, with an upgrade in capac ity during 2008. Discharge licence conditions have been consistently met, with pH and EC units being constantly measured and recorded. The microfi ltration system cont inues to operate reliably with little operator involvement and no integrity issues reported or recorded. EFM processes are

technical features

refereed paper

desalination & membrane technology

conducted frequently (Fig ure 4), and appear to manage the highly variable feedwater contaminant levels (continued evidence of widely fluctuating feedwater turbidities and organic/algal loads due to temperature and seasonal influences), with no long-term decrease in permeability detected, and low average TMPs. Operational data generated to date and water quality analysis received from Arrow Energy's contai nerised IMS and MF systems near Dalby in the Surat Basin, suggest reduced contami nant loadings and proportionately reduced requirements for EFM processes (Figu re 5) with stable and low average TMPs recorded. Normalised Permeate Flow (NPF) data for Origin's 3-stage #2 RO system is presented in Figure 6 to demonstrate the critical involvement of operators who are responsible for balancing the desire to maximise recoveries with fluctuating feedwater chemistry and temperat ure effects. The normalised data is a comparison of the actual performance to the

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feedwater composition and temperature as well as operational and adjustable set points. Despite high variability in feedwater conductivities the RO membrane operation remained steady with const ant

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desalination & membrane technology Normalised Differential Pressure (NOP) and NPF over t ime. This indicates that the RO membrane was not subject to biofouling or inorganic scaling during the data collection period. This has been achieved through appropriate design, operator involvement, process understanding, and predict ive maintenance clean ing regimes rather than reactive ones. Biological foul ing has been an issue in some previous installations within the CSG industry, but has been successfu lly managed at both operational facilities to date, as evidenced by stable Differential Pressures (dP's) across all stages. The RO concentrate is cu rrently being disposed of in small lined evaporation ponds. If Origin En ergy's proposed Australia Pacific LNG (APLNG) project is approved there will be a requi rement for significant additional water treatment capacity. In recognition of the requirements for an increased level of experienced operational staff, Spring Gully is being used for plant based training and to upskill existing operators. The developed internal train ing courses cover all operational aspects of the IMS faci lity, including OH&S requirements , general process knowledge for each individual process unit, and the integrated control system, as well as a variety of mechanical, analytical, and ongoing maintenance services required. Additionally, Origin is engaged with the local regional TAFE colleges and draft membrane system operator training materials and courses have been prepared, t hat will benefit both the local community and mitigat e risks t o their business for operational resource constraints as t hey further develop their CSG businesses and interests. The success of t his installation was recognised in 2008 when Origin Energy received the Category A National Environment Award from the Australian Petroleum Production & Exploration Association (APPEA) for contribution to environmentally sustainable practice.

Conclusions The sig nificant and rapid expansion of the Coal Seam Gas (CSG) industry will require extensive treatment and disposal of the resu ltant produced water. Lab and pilot tests indicated that the CSG produced water is highly variable and contains significant scaling and fou ling properties due to dissolved

76 JUNE 2010 water

refereed paper

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Figure 6. Origin R0#2 NPF, NDP and feed conductivity. inorganic salt s and periodic algal blooms. The use of integrated small scale membrane pilot systems was found to be an effective way to f ully define process requirements, and design full scale membrane treatment based facilities. Hollow Fibre Microfiltration processes were proven to be a highly effective means to protect the Reverse Osmosis (RO) membrane systems. Integrat ed control and highly automat ed flexible c leaning sequences were key aspects of the system that allowed reliable operation of the commercial CSG produced water treatment plants. Experience to date shows no signs of physical degradation or performance deterioration of these membrane systems. Given requi red availabi lity and reliability, and desire for maximised recoveries - the RO system must incorporate a range of features t o allow contin ued operation under a wide range of feedwater conditions, and allow for future 'unknowns' and changes as the CSG fields are further developed and 'age'. Th ree large scale commercial Integrated Membrane Systems (IMS) using Microfiltration (MF) and Reverse Osmosis (RO) have been executed. Arrow Energy selected a more mobile system placed in containers and Origin Energy proceeded w ith the execution of two plants that utilise modular and skidmounted process units at their 'Talinga' and 'Spring Gully' Developments. The first IMS facilit y at 'Spring Gully' has now entered it's 3rd year of operation.

material contained herein and t he ability to share operational information.

The Authors

Scott Chalmers is Industrial Water Manager (email: scott_chalmers@ ap.pall.com). Peter Stark is Engineering Manager, August Kovse is Piloting Manager, Lance Facer is Process Engineer, all with Pall Austral ia. Neil Smith is Operations Superintendent with Origin Energy.

References Chang, Y., Kramer, A. J. , and Lubben, D. R., 2002. Effective Membrane Fouling Control: A New Membrane Cleaning Concept, Proceedings of Water Qualit y Technology Conference, November 10-14, Seattle, WA. Energy Information Administrat ion (EIA): US Coalbed Methane, Past, Present, and Future, websit e at www.eia.doe.gov. Oldridge S and Whatman L, 2009. The Beneficial Use of Coal Seam Gas Water. Water. 36, 4. Osborne, T. J. and Adams, J.E., 2005. Opportunities and Limitations o f CBNG Produced Water Management Alternatives in the Powder River Basin, 12th Annual International Petroleum Environmental Conference, Houston. Mannhardt T and Cameron I, 2009 Coal Seam Gas Water: Viability and Treatment. Water 36,

7. Queensland Government, 2009, Blueprint for Queensland's LNG Industry. Department of Employment, Economic Development and Innovation. Squarek, J. and Dawson, M. , 2006. Coalbed Methane Expands in Canada, Oil & Gas

Journal.

Acknowledgment The authors thank both Origin Energy and Arrow Energy for assistance with the

Wayne A. Van Voast., 2003. Geochemical signature of formation waters associated with coalbed methane, American Association of Petroleum Geologists Bulletin, Vol 87, No. 4.

technical features

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PERVAPORATION - A FURTHER LOW ENERGY DESALINATION OPTION? B Bolto, M Hoang, Z Xie Abstract Pervaporation is a process that uses membranes for the selective removal of water from aqueous organic mixtures, and also for the separation of organic liquids. Its application to low energy desalination involves the evaporation of water through non-porous membranes. While undoubtedly low in energy requirements, the water flux in systems so far explored is generally quite low at - 5 Um2h: the existing process is too slow. High temperatures can speed thi ngs up, but to avoid excessive expenditure on energy, sources such as solar, geothermal and industrial waste heat need to be utilised. Mechanical energy in the form of extra applied pressure or vacuum can likewise be called upon to enhance the flux. Other key factors in need of study are the thickness of the membrane, where the active layer should be as thin as possible, and the permeability of the membrane polymer.

Introduction Pervaporation (PV), aimed at the separation of liquid mixtures, involves a membrane that is in contact with the feed solution on one side, while permeate is removed as a vapour from the other side (Baker, 2004). Commercial systems for the dehydration of azeotropic ethanol/water mixtures in the manufacture of alternative liquid fuel have been employed since the 1980s, with more

Capacitative Desalination Hoang, Bolto and Tran discussed the potential for such a system in Water, February, 2009, citing Andelman ,1998. His process has since been developed by Voltea, a subsidiary of Unilever. In April at the Global Water Awards for 2010, first prize in the Water Technology Idol section was awarded for their Flow Through Capacitator process. Init ial market entry in 2010 will focus on low-salinity industrial , domestic appliances and residential use. (In the Public Agency of the Year section the winner was Sydney Water, well ahead of San Diego).

Table 1. Factors affecting overall mass transport (Staudt-Bickel and Lichtenthaler, 1994). Intermolecular interactions

Molecular size and shape Polarity and polarisability Hydrogen bonding Donor-acceptor interaction State of aggregation of the polymer

Glass transition temperature Ratio of amorphous to crystalline domains Physical properties

Feed composition Thickness of boundary layers Thickness of selective nonporous layer Porosity of support Permeate pressure

than 100 plants being installed , the largest processing 5000 kg/h. The 200- to 500-fold separation achieved is due entirely to the selectivity of the membrane used, which is much more permeable to water than to ethanol. Transport through the membrane is driven by the vapour pressure difference between the feed solution and the permeate vapour. The vapour pressure difference can be maintained by applying pressure to the feed or a vacuum on the permeate side, or by cooli ng the permeate vapour so that it condenses, spontaneously creati ng a partial vacuum. As applied to desalination, PV involves the evaporation of water through nonporous membranes of the diffusion type, in contrast with membrane distillation (MD), wh ich is evaporation of water through open ly porous membranes composed of hydrophobic polymers (Kutznetsov et al. , 2007). It is claimed that MD has the disadvantages of a limited selection of industrial membranes of the required type, which are expensive, and a gross loss of heat in mass transfer. Leakage of water from the hot stream to the cold can also occur as the pores of the membrane become filled with water

Too slow at present, but there is potential.

during prolonged use (Korin et al. , 1996). Both MD and PV have the advantage that the energy need is essentially independent of the concentration of t he salt feed water, in contrast with other membrane technologies, such as reverse osmosis and electrodialysis. T hey are hence capable of concentrating salt solutions up to the supersaturated level, which allows for the recovery of salt by crystallisation (Gryta, 2002; Tun et al. , 2005). There is of course a further energy requirement for this additional step. PV involves a succession of stages of sorption of liquid water through the membrane, and its diffusion through the free volume of the membrane, during which there is a phase change from liquid to vapou r. Hence the use of hydrophilic instead of hydrophobic polymers in membrane fabrication should result in a high permeability. For good selectivity the free space regions in the polymer should be very small and comparable with the diameter of the water molecu le (0.27 nm). This would require a highly ordered structure in the polymer, such as is obtained with hydrated cellulose, where there is dense packing of the polymer chains because of the network of hydrogen bonds.

Membrane Selection A detailed review of appropriate polymers for membrane manufacture has been published (Staudt-Bickel and Lichtenthaler, 1994). As virtually all PV membranes are non-porous polymeric systems, membrane selection is focussed on polymer design and modification. The polymers most suitable for particular PV operations are discussed, along with their limitations. The development of the optimum polymer for PV appl ication is a challenge for polymer chemists and may need entirely new concepts and ideas. A trial and error approach in the past has revealed that, for the dehydration of organic liquids hydrophilic polymers are preferred, and for the removal of organics from aqueous solutions hydrophobic elastomers are the most suitable. These days, the selection of the membrane polymer is usually made on the basis of solubility and diffusivity data for the

water JUNE 2010 77

desalination & membrane technology various components of the mixtures in a membrane polymer. Solubility and diffusivity of low molecular mass sol utes in polymers strongly depend on the molecular size and shape of the solute, the polymer solute interactions, and the chemical and physical structure of the polymer. Table 1 summarises some key factors important for mass transport through a PV membrane. Diffusivity not only depends on molecular interactions, but also on the solute size and the state of aggregation of the membrane polymer; it differs significantly for glassy and rubbery polymers. However, the improvement in diffusivity necessary for good fluxes usually means a decrease in selectivity. This type of analysis does not yet seem to have been applied to desalination using PV, where polymer selection would appear to be related to that for dehydration of organic liquids, so that hydrophilic polymers are still preferred. Some of the polymer modifications suggested are the incorporation of inorganic additives, crossli nking the polymers, blending a mixture of polymers, and the use of copolymers and polymer graft systems.

Cellulosic Membranes Membranes have been made from plant cell ulose of thickness 30±5 µm, and also bacterial cellulose obtained from Acetobacter xylinum, wh ich had th icknesses of 40 and 240 µm (Kutznetsov et al., 2007). PV at 40°C on a 4% salt solution gave complete salt retention at fluxes of 0.9 to 6 Um 2 h, as detailed in Table 2. Wood based membranes had lower permeabilities, the lowest being for the less hydrophi lic cellulose diacetate. Cotton derived cellulose swells more and has a higher flux , especially when swollen in water before use. Composite membranes made by depositing a thin layer (0.1-0.5 µm) of cellulose diacetate on a microporous polytetrafluoroethylene membrane that is used for MD had a flux of 4.1 to 5.1 Um2 h. This was t he same order of flux as was obtained by MD with the original membrane, although levels 10 times that are now possible with modern MD membranes (Soito et al. , 2007). Supporting membranes of the smallest pore size were preferred.

Sulphonated Polyethylene Membranes The PV performance in desalination with hollow fibre cation exchanger membranes

78 JUNE 201o water

Table 2. Fluxes for PV desalination of 4% NaCl at 40°C with 100% salt retention (Kutznetsov et al., 2007).

Membrane Material

Cellulose diacetate (wood) Wood cellulose Cotton cellulose Cotton cellulose, activated* Bacterial cellulose Cellulose diacetate composite on MD membranet

Flow Rate, L/ m2h

0.91 1.7 4.6 6.7 - > 6.1 1.9 4.1 , 5.1

• By contact in water before the application of the driving force

t After saponification of the cellulose diacetate based on sulphonated polyethylene (PE) is reported (Karin et al., 1996). The fibres had diameters of 400-1800 µm, a wall thickness of 50-180 µm and a charge density of 0.6-1.2 meq/g. The feed was 0-176 g/L, and the flux obtained was 0.8-3.3 Um 2 h when the inlet brine temperature was 25-65°C. An ai r sweep f low of 0-6 mis was employed. The optimal specifications were fibres of diameter 1200 µm and wall thickness 100 µm, with a charge density of - 1.0 meq/g. The highest flux of 3.3 Um 2 h was achieved when t he feed temperature was 60°C. There was some decrease in fl ux when t he feed concentration became very high, with values for the 176 g/L feed being 85% of that for tap water (Korngold and Korin, 1993). This was ascribed to a reduction in the swelling of the membrane at the higher salt level. Anion exchange versions of the hollow fibre PE membranes have been made by sulphochlorination, amination, followed by quaternisation of the amino groups (Korngold et al. , 1996). Using them in a recycled air sweep PV system, t he water flux was 1.5-3.0 Um2 h when the water temperature was 45-65°C. The calculated energy requirement for water and air pumping a pilot plant of capacity 6.3 Uh with 4 m2 of membranes was - 2 kWh/m 2 when the feed water temperature was 60°C. There was a significant decrease in f lux when thicker-walled fibres were used, from 2.3 Um 2h for 70 µm thickness to 0.5 Um 2 h for 170 µm thickness. The fl ux was fou nd to be similar to that for MD with a commercial microporous hydrophobic hollow fibre polypropylene membrane (Celgard 2500), which had a wall thickness of only 25 µm. This was because of the th inner walls of the MD membrane and the higher diffusion coefficient for the vapour (porous MD format) compared to t hat of t he liquid

re f e r ee d paper

(dense PV format) . Diffusion of liquid water through the continuous pathway of water shells around charged groups is claimed to be faster than diffusion through clusters of free wat er in the membrane (Cabasso et al., 1985).

Polyether Amide Membranes A polyet her amide membrane made from E-caprolactam and a mixture of poly(ethylene oxide) and poly(propylene oxide} is the subject of an Akzo patent (Van Andel, 2001). The membrane is reported to be effective in solar powered desalination for irrigation purposes. The membrane was in the form of a 40 µm thick film extruded onto a supporting layer t hat formed an irrigation mat. Raising the feed water temperature to 60-80°C by simulated solar heating for 12 h per day yielded an average 0.25 Um 2 h. In dry areas with many sunny days (> 300 per year) t his should produce 1000-1300 Um 2 y. It is generally thought that effective irrigation requires - 500 Um 2 y. The membrane was claimed to be exceptional ly resistant to the aggressive combination of sea water and heat in the long-term. A tubular config uration of a non-porous polyether amide membrane of 40 µm thickness has been used in a solar driven PV process to desalinate untreated seawater and wastewater from oil production (Zwijnenberg, et al., 2005). The flux was low at - 0.2 Um 2 h over a 9 h day, but was independent of the feed concentration and severe fouling.

Polyether Ester Membranes Polyether ester membranes made by DuPont have been tested in hollow fibre and corrugated sheet modes for PV reclamation of contaminated water for the purpose of crop irrigat ion (QuifionesBolafios et al., 2005). The membrane polymer was a hydrophilic t hermoplast ic elastomer that is claimed to have good chemical resistance and high mechanical strength. A DuPont patent exists that reports polyether ester elastomers made up of a poly(trimethylene-ethylene ether) ester soft segment and an alkylene ester hard segment (Su nkara, 2005) . The model contaminants present in the test water included borate, selenates, and 0.3-30 g/L sodi um chloride. The hollow fibre system gave the best results. The highest flux of 0.15 Um 2 h was for a 3.25.2 g/ L salt feed at 29°C. This decreased to 0.10 Um 2 h at 22°c. Increasing the salt concentrat ion also decreased the flux slightly. The water flux increased linearly with the feed pressu re.

technical features

refereed paper

desalination & membrane technology

Silica Membranes Silica membranes have been made on a alumina su bstrates using tetraethylorthosilicat e and various amounts of an ABA triblock copolymer made from poly(ethylene glycol) and poly(propylene glycol), which was used as a template (Ladewig et al., 2010). Calcining under vacuum carbonised the tem plate and t rapped it w ithin the membrane matrix. Synthetic seawater was desalinated at a fl ux of 3. 7 Um2 h with 98.5 % salt rejection at room temperature and a driving force of 100 kPa.

Unidentified Commercial Membrane Fluxes as high as 38 Um2 h are reported to have been ac hieved with a sea water feed and a temperature of 100°C. At 90°C the flux was 31 Um 2 h, and at 80°C it was 26 Um2 h, all at a f low rate of 40 U h (Honda et al., 1998). The fluxes were lower at lower flow rates. The type of membrane employed is not clear; a vacuum of 2.6 kPa was utilised.

Summary and Conclusions An overall view of the PV desalination results reported so far is given in Table 3. By far t he best outcome is with the unknown commercial membrane, followed by the c ellulose, si lica, ionic PE and the various polyether membranes. Very high feed temperatures were used in the case of the unidentified commercial membrane. This and the work on two of the other membranes shows that t emperat ure is a cruc ial parameter, the benefit of which is attributed to the in crease in diffusivity and reduction in flow viscosity that occurs on heat ing. Mechanical energy in the form of extra applied pressure or vacuum can likewise be called upon to enhance the fl ux. The thickness of the membrane is another vital factor: the active layer should be as thin as possible. The inherent permeability of the membrane polymer is sim ilarly important. The main parameters for better water f lux are therefore: • Higher feed water temperature • Inc reased pressure/vacu um • Low membrane thickness • Improved membrane permeability Hence expend itu re on thermal energy wi ll improve the water flux. Cheaper t hermal sources that could be exploited are solar, geothermal and industrial waste heat. A more rigorous comparison

Table 3. Summary of PV desalination data available. Membrane Polymer

Feed Cone., g/L

Temp.,

Flux, Um2h

Reference

Cotton cellulose

6.1

Kutznetsov et al.,

Cellulose diacetate on MD membrane

0.5-1 .5

4.1-5.1

2007

Sulphonated PE, cation exchanger

0-176

25-65

100

Air Sweep

0.8-3.3

Korin et al., 1996

Ouaternised PE, anion exchanger

0-176 35 35

45-65 60 60

50-180 70 170

Air Sweep

1.5-3.0 2.3 0.5

Korngold et al., 1996

Polyether amide

Solar, 60-80

Air Sweep

0.25

Van Andel, 2001

Polyether amide

Solar, 46-82

Air Sweep

0.2

Zwijnenberg, et al., 2005

Polyether ester

3.2-5.2 9.9-18 20-30

Solar, 22-29

160

Air Sweep

0.15 0.13 0.12

Ouinones-Bolanos et al. , 2005

1-10

100

3.7

Ladewig et al., 2010

2.6 2.6 2.6

38 31 26

Honda et al., 1998

·c

Silica

Commercial, unidentified

35 35 35

100 90 80

Membrane Pressure, Thickness, kPa 11m

needs to be made with MD, whic h with its porous membrane structure could be pred icted t o have a higher fl ux than is achievable with dense PV membranes, with their in evitably slower diffusion paths, and with the liquid diffusion in PV being slower than the vapour diffusion in MD. A potential advantage for PV membranes is the greater physical integrity of their dense membrane structure over that of a porous MD membrane.

The Authors

Dr Brian Bolto, Dr Manh Hoang and Zongli Xie (email: brian.bolto@csiro.au ; manh.hoang@csiro.au; zongli.xie@csiro.au) work for CSIRO Materials Science and Engineering, Clayton, Victoria (postal address: Pri vate Bag 33, Clayton MDC, Vic 3169).

References Baker, R. W. (2004). Pervaporation. Membrane Technology and Applications, 2nd Ed. , Wiley, New York, pp. 355-392 . Bo/to, B. A., Tran, T. and Hoang, M . (2007). Membrane distillation - a low energy desalting technique? Wafer 34(4), 59-62. Cabasso, I., Korngold, E. and Liu, Z-Z. (1985). On the separat ion of alcohol/ water mixtures by polyethylene ion exchange membranes. Polym. Sci.: Polym. Letters 23, 577-581 . Gryta, M. (2002). Concent ration of NaCl solution by membrane distillation integrated with crystallization. Sep. Sci. Technol. 37, 35353558.

Honda, M ., Shiba, N. , Kuramoto, Y., M arushita, K. and Okada, M. (1998). Seawater desalination on pervaporation process. Nippon Kagakkai Koen Yokoshu 75, 36. Korngold, E. and Kerin, E. (1993). Air sweep water pervaporation with hollow fiber membranes. Desalination 91, 187- 197. Korngold, E., Korin, E. and Ladizhensky, I. (1996). Water desalination by pervaporation with hollow fiber membranes. Desalination 107, 121-129 . Kerin, E., Ladizhensky, I. and Korngold, E. (1996). Hydrophilic hollow fibre membran es for water desalination by the pervaporation method. Chem. Eng. Proc. 35, 451 -457. Kuznetsov, Y. P. , Kruchinina, E. V., Baklagina, Y . G., Khripunov, A. K. and Tulupova , Y. G. (2007). Deep desalination of water by evaporation through polymeric membranes . Russ. J. Appl. Chem. 80, 790-798 . Ladewig, B. P., Tan, Y. H. and Diniz da Costa, J . C. (2010). Preparation, characterisation and performance of templated silica m embranes in non-osmotic desalination. Water Research, submitted. Quii\ones-Bolar'ios, E. , Zhou, H. , Soundararajan, R. and Otten, L. (2005). Water and solute transport in pervaporation hydrop hilic membranes to reclaim contaminat ed water for micro-irrigation . J. Membrane Sci . 252, 19-28. Staudt- Bickel, C. and Lichtenthaler, R . N. (1994) . Pervaporation thermodynamic properties and selection of membrane polymers. Polymer Sci. 36, 1628-1648. Sunkara, H. B. (2005). Polyether ester elastomers comprising a poly(trimethylene-eth ylene et her) ester soft segment and an alkylene ester hard segment. US Patent 6,905,765. Tun, C. M., Fane, A.G ., Matheickal, J . T. and Sheikholeslami, R. (2005). Membr ane distillation crystallization of concentrated salts - flux and crystal formation. J. Membrane Sci. 257, 144-155. Van Andel, E. (2001 ). Pervaporation d evice and irrigation mat. US Patent 6,679,991. Zw ijnenberg, H. J., Keeps, G. H. and Wessling, M. (2005). Solar driven membrane pervaporation for desalination process. J. Membrane Sci. 250, 235-246.

water J UN E 2010 79

desalination & membrane technology

THERMO-IONIC DESALINATION DRIVEN BY SOLAR OR WASTE HEAT B Sparrow, J Zoshi 0.060

Abstract A novel proof-tested desalination system is presented. It harn esses low grade heat or solar energy to provide concentrated brine as the driving force. A 1,000 Uday pilot plant has been constructed in Vancouver, Canada and is currently operating on harbour seawater with chemical-free pre-treatment. Applying the small but measurable voltage differences between concentrated brine and more dilute salt solut ions, through a series of cel ls each fitted with cation and anion membranes, has enabled seawater to be reduced to potable concentration. The electrical energy is secondary and reduced to that necessary to pump the streams through the low-pressure PVC network, of the order of 1 kWh per kl. Provided inexpensive evaporation facil ities can be provided, the process can be more economic than reverse osmosis. Thus the technology could offer a low impact desalination sol ution for dry regions in Austral ia.

Introduction The authors present a patent-pend ing and proof-test ed thermo-ionic desalinat ion process. Solar or low temperature energy is used to evaporate water from brine, producing a concentrated sol ution . There is a chemical energy d ifference between a concentrated salt solution and a dilute solution which is expressed as a voltage difference. This voltage is applied to an adjacent cell fitted with cation and anion membranes, driving sodi um ions one way and ch loride ions the opposite way, thus reduc ing the salt co ncentration in that cell. By applying a series of such cells it has proved possible t o reduce seawater to potable concentration. The bulk of the pipework and vessels can be low cost PVC. A 1,000 U day pilot plant has been constructed in Vancouver, Canada and is currently operating on harbour seawater with chemical free pre-treatment, prod ucing potable water. The plant can be tuned to various saltwater concentrations, including the potential for a zero liquid discharge that enables salt harvest ing.

Theory The important variab le in a concentration gradient system is the change in net chemical energy which may be modelled both in terms of osmotic pressu re or galvanic potential, which represents Gibbs free energy (P itzer et al. 1984). This is a summary prepared by the Editor of the paper presented by Sparrow at Ozwater10 (#035). A demonstration rig, packed in a suitcase, was operated for a number of interested delegates.

JUNE 201 o

water

.,>.. ~

0.040 0.020

]

0.000 C ~:, -0.020

0V)

-0.040

-iii~ -0.060 l!!

~ 0 -0.080 -0.100 NaCl Mass Fraction

Figure 1. Galvanic potential of NaCl (aq) referenced to 3.5% salt mass. Ion exchange processes are more suited to galvanic potential, or the voltage difference between solutions. Figure 1 shows the voltage difference between two solutions of aqueous sodium chloride: a first reference solution of 3.5% salt mass fraction representing seawater and depicted by the curve; and a second solut ion at various concentrations depicted along the x-axis. Aqueous sodium chloride data is far more abundant than data on sea salt, and sufficient to provide the general model of concentration gradient energy disclosed. The voltages in Figure 1 were calcu lated using activity coefficient data for NaCl (aq) (Hammer et al. 1972) . Figure 1 shows that -0.09 volts is established between a freshwater sol ution (y-intercept) and a solution at 3.5% salt, or 0.035 mass fraction (x-intercept). This voltage needs to be overcome to drive salt ions from a solution approaching potable concent ration to a solution at seawater concentration of 3.5% . It also shows that the chemical energy difference between a solution at 3.5% and concentrate at 18% is 0.04 volts. The desalting device combines multiple diluentconcentrate compartments in an additive fashion, analogous to batteries in series, producing an additive voltage. For example three concent rat e-di luent compartments each prod ucing 0.04 volts collectively produce a net 0.12 volts. This voltage is sufficient t o drive salt out of a product sol ution compartment at -0.09 volts. An external voltage is not necessary to move the ions, instead this voltage is produced through concentrat ion gradients. The various compartments are separated by ion bridges that are permeable to only positive or negative ions. These have been fabricated from polystyrene fil ms which have been functionalised, somewhat simi lar t o electrodialysis membranes, but more efficient. They are stacked and so t hat positive ions transfer from the concentrat e to t he diluent through a positive ion bridge while negatives transfer in the opposite direction. The product compartment completes the circuit, with positive and negative

A novel concept undergoing scale-up from pilot plant.

technical features

desalination & membrane technology ions transferring from it to a diluent compartment under the applied "drive voltage". The concentrate's concentration decreases and diluent increases while desalting the product. Optimisation of the concentration gradients and compartment numbers requi res more detailed discussion not within the scope of this paper. It is noted that sodium and chloride ions are discussed but the ion bridges also transfer multivalent ions such as calcium, magnesium, and sulphates.

The Pilot Plant Flow Diagram The flow diagram of the pilot plant is shown in Figure 2. Process make-up water (mmake-up) from the saltwater source is first treated by filtration and then split to feed the product and diluent circuits. The product water (m p,) flows through fou r desalting devices in series, being desalted partially in each device. Concentrate (me,) and diluent (md,) flow t hrough the devices in parallel, providing concentration gradient energy to desalt the product. A portion of the diluent (md is circulated to the concentrate circuit to replace salt lost during passage through the desalting devices. The diluent transferred to the concentrate passes throug h evaporators to remove the water and maintain the concentrate's concentration. Some spent diluent is cycled back to the diluent storage tank (md4) to reduce the amount of make-up water requi red and increase recovery. In this example, a portion of the diluent is discharged to the saltwater source (mdischarge) to prevent salt accumulation and maintain a low diluent concentration. Th is discharge concentration can be tuned higher or lower.

Note, the water leaving the system as evaporate is not captured. This makes the evaporation system simpler and less costly than air humidification/ dehumidification technology. For example, an open pond, spray pond, natural draft tower, or forced draft tower may be used - with successively decreasing footpri nt but increasing energy requirements. Ponds would serve a dual function as both a solar energy capture device and evaporator. Not shown in Figure 2, higher concentrations can be achieved through counter-current series passage of diluent and concentrate through the desalting devices. Such operation improves recovery rates, enables salt harvesting, and would be beneficial for inland applications.

Pilot Plant Description The 1,000 Uday pilot plant operates on seawater in Vancouver, Canada. Its intake and outfall consist of slotted 4 cm PVC pipes laid on the seabed with concrete saddles. Suction pressure is provided by a deep-well injection pump. Pretreatment at 8 Umin is achieved through slow sand filtration. No chemicals or anti-sealants have been used in the desalination plant to date. The desalination plant itself is made from low cost and low pressure schedule 40 PVC pipework. Operat ing pressures are 20-40 kPa with circulation via centrifugal pumps ranging in capac ity from 4 Umin to 20 Umin. A National Instruments cRio Nl-9073 controller and H-bridge set are used to control the process and vary pump speed and process pressure. Temperatures are measured with RTDs, pressures via pressure transducers, flows via magnetic flow meters, and

\ I /

,11

r r

Ppump hydraulic= _p â&#x20AC;˘ 0 / _ _p = differential pressure (Pa) Q = flow rate (m 3/sec) _ = pump efficiency

These results predict a net system electrical energy consumption of 42 watts, translating to 1 kWh/ kl production inclusive of pre-treatment. In addition to the desalination plant, the authors built and tested a fully automated evaporative spray pond measuring 10 x 13.5 metres. At the time of writing the device was desalinating seawater to potable salt standard in batch mode at a pressure of 20 kPa and net ionic efficiency of 70%. Ionic efficiency is defined as the ratio of measured to predicted current based on galvanic potential analysis - vo ltages and resistances.

Conclusion Initial test resu lts and economic assessments show that the technology may competitively desalt seawater or brackish water in dry regions. The ability to use a first desalination plant's waste brine as a concentrate source is compelling. The technology is less suited for urban environments, unless waste heat is available to conduct evaporation . In sum, this technology holds the potential to produce lower cost and lower impact desalinated water on the Australian conti nent.

The authors acknowledge the support of BC Hydro', Powertech Laboratories, Okanagan Research and Innovation Centre, the BC Clean Energy Fund , Canada's National Research Council, and Sustainable Development Technology Canada.

Evaporative Device , 11

Desalination rate is measured both as a change in product concentration with time as well as ionic current passed by the desalting device. Pressures both upstream and downstream of the pumps (_P) are measured in order to calculate input hydraulic energy using the following equation:

Acknowledgments

Q: Heat P: Power

\ I /

concentrations via 0-20,0-200, and 0-400 mS/cm conductivity sensors.

\ii

The Authors

Concentrate Circuit

Desalinated Product

m -

Diluent to replenish lost salt from concentrate: m"

Figure 2. Simplified process flow diagram with mass and energy balance state points.

Benjamin Sparrow graduated B.Eng (M ech) from Alberta.and is the inventor of the concept. He has formed Saltworks Technologies Inc. www.Saltworkstech. com, ben.sparrow@saltworkstech.com. Joshua Zohi is President of the company.

water JUNE 2010 a1

p::;

agricultural use

refereed paper

AMERICA'S FASCINATION WITH AUSTRALIA'S NATIONAL WATER INITIATIVE J McKay Introduction

Colloquium at Berkeley for the Water Resources Center Archives on 10 January 2009. Many people in the US are interested in Australia's approach to implementation of ESD and wanted more details.

I was blessed in 2008- 2009 to be awarded a Senior Fulbright fellowsh ip on the topic of comparative water policies and laws. I was based at Boalt School of Law and American University in Washington DC and worked on the political questions doctrine in US jurisprudence and its analogy in Australia. I also studied Human rights law and Californian legal cases. The experience was really refreshing as some of the best teachers exist in these two law schools. The research work concerned the limits between political questions (decided by Ministers) and legal questions (decided by the Courts) and how international agreements have norms wh ich influence national decisions. There are some issues that superior court judges have considered to be political questions and so feel that they cannot review a decision. There are precedents in Australia that suggest that, where a Minister has the discretion in a particular case by reference to the interests of the general public, then in such political field questions, the discretion may be exercised free of procedural constraints1. There are High Court and NSW2 decisions in support of this proposition . I am interested in how both the domestic and international laws now play out together in relation to the relatively fuzzy concept of Ecological ly Sustainable Development (ESD) and the national interest as required in our new Water Act 2007 Cth. 3 ESD obligations are set out in that Act as: 1. decision-making processes shou ld effectively integrate both long-term and short-term economic, environmental, social and equitable considerations;

2. if there are threats of serious or irreversible environmental damage, lack of full scientific certainty sho uld not be used as a reason for postponing measures to prevent environmental degradation;

82 JUNE 201o water

3. the principle of inter-generational equity-that the present generation should ensure that the health, biodiversity and productivity of the environment is maintained or enhanced for the benefit of future generations;

4. the conservation of biodiversity 4 and ecological integrity should be a fundamental consideration in decisionmaking; and

5. improved valuation, pricing and incentive mechanisms should be promoted These issues are difficult and centre around fairness and justice for all species and present and future generations. This object and litigation around similar expressions of it in state acts and other federal acts is the stuff of the new millennium .

Lectures and Seminars As part of my Fulbright, I was asked to give an address at the quarterly

Comparmg ware, policies and laws.

Over 90 people attended the lecture including senior students (who were writing a paper for their Masters on Australia water policy regime). several wat er policy officials, legislators (staffers from Sacramento) and water utility managers and academics from Engineering, Law and the Public Policy school. The seminar covered the processes leading up to the present water reforms. The audience was most interested in how the Water Act 2007 came to be adopted and to hear about implementation issues. They were interested in community responses to policy instruments such as water allocation plans and changes to water allocation regimes, water meters, catchment levies, new water sources such as reclaimed water and water markets. I was able to draw on research from the NWI , many universities, CSIRO, CRCs Water Quality and Treatment and Irrigation Futures, legal cases and consultant reports to tell the story. This Colloquium provoked a huge amount of interest in the water resources professionals in California and legislators and I was asked to repeat it in UC Sacramento and the California Assembly's Select Committee on Regional Approaches to Addressing the State's Water Crisis, Olympia, Salt Lake City, Congress in DC ( through Austrade) the World Bank and at the University of Arizona Udall School of Public policy. These talks took place over several months in 2009. Finally, in February 2010 I was invited to the American Bar Association water law meeting in San Diego and in June 2010 in San Francisco at the conference organised by UC Davis Toward Sustainable Groundwater in Agriculture - linking science and policy. The visits were sponsored not only by Fulbright Foundation but by Alf Brandt,

echnical features

agricultural use

refereed paper

Principal Consultant, Office of Assembly member Jose Solorio, State Capitol Sacramento and the Resources Legacy Fund, UC and others, especially University of South Australia School of Commerce. The meetings also extended to major water law firms in several states. Further details are available at http://www. unisa.edu.au/ waterpolicylaw/ news/201 0.asp and also in the Whittier Daily News-3/6/ 10 as "California looks to Australia for lessons on water management". http://www. whittierdailynews. com/ news/ ci_14526188

Water Epochs in Australia I gave a potted version with several key photos, illustrations, cartoons and poems of the five epochs in Australian wat er policy. There are several aspects to Austral ia's water policy and law regime and these can be seen as five policy epochs between 1788 and 2010. The prefederation epoch was characterised by water as an economic development device with scant political considerat ion of the environment consequences. The second epoch commenced with Australian Federation in 1901, but did little to alter the colony's (now t he states) power over water. The stat es did create administrative allocation systems for surface and groundwater, repealing the riparian doctrine. In addition. the interpretation of the Constitution by the courts and cond itional federal grants to t he states by the Commonwealth (i.e. the Federal Government), pursuant to section 96 of the Constitution, did give t he Commonwealth some influence over state water policy during t his period. Since t he

1970s, there has been community demand for sustainability in water and land use decisions. The third epoch, wh ich commenc ed in the early 1980s, was chiefly characterised by an expanded interpretation of Commonwealth legislative power by the courts, allowing the Commonwealth to legislate in some areas of water management. There was also increased commu nity activism. The fourth phase commenced with two waves of federal reforms in 1994 and 2004. The earliest reforms introduced requirements of ecologically sustainable development (ESD) and competition into water suppliers and also separat ed land from water to create water markets. The later wave was influenced by regional delivery models and t he Commonwealth provided stricter guidelines to the states reinforcing the first reforms. There have been state level court decisions enforcing t he water plans and reducing water allocations to farmers in favou r of the environment. The final phase, commencing in 2007, reflects a different balance. The use of political deal-making (where states are required to refer power over water to the Commonwealth) and the expansion of federal constit utional powers through generous judicial interpretation have allowed t he federal government to creat e the agenda over water management in the states in the Murray-Darling Basin. The legal architecture of the final stage is t he Water Act 2007. This Act requires the accreditation or adoption of state "Water Plans in the Murray-Darling Basin". Further, Commonwealth gave federal funding directly to 56 state-founded regional bodies, and these bodies agreed

to regional delivery of Federal initiatives. These recent reforms appear to affirm the general drift towards centralism in water regu lation in Australia. The American audiences gasped at t he referral of power and many saw t hat process as a solution to the fragmentation of water law in California and Arizona. They were keen to hear of t he factors, social, political, cultural , legal economic and environmental (the drought) that all played a role in the policy transition toward ESD. I would like to describe some of the questions and issues raised by the audiences.

Similarities and Differences Whilst the US shares a simi larity with Australia in that we are both Federations, the nuances above and the legal meaning of the different pow ers mean that the pathways of these democracies has diverged in relation to water. The most important difference is that the Prior Appropriat ion doctrine exists in the Western states of t he US. It has no parallel here. This mining type, allocat ion process, "first in first served" system, creates property rights in water and whilst this can be manipulated to achieve sustainable water allocations this is inhibited by the need to provide compensation for changes. Another point of divergence is that in California and many other States, groundwater use is not metered. When explaining t he pathway to our present Water Act t he gasps in t he audience were on these points: 1. The universality of metering and t he penalties exacted for overuse. I did

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water JUNE 2010 83

agricultural use couple this with the story about the Dethridge w heels and their level in inaccuracy and the replacement by flumes, as in Coleambally for example. I also showed several photos of meters. 2. The water planning processes and reductions in water allocated w ith the move toward shares of the consumptive pool for all users. I used cases such as Harvey & Anor v Minister Administering the Water Management Act 2000 5 , which related to groundwater in New South Wales and Elandes almond industry on groundwater in South Australia In Harvey the Minister created a water plan which altered the way water was allocated to over 1,000 farmers in the Murrumbidgee River. To achieve sustainabil ity, the volume of water was reduced to 52% of the previous level. The plan used one method to reduce, but the Minister altered the method to achieve the reduction. Harvey illustrates the practical issues with implementing a water allocation plan which changes water allocation rules. The fi rst method chosen was across t he board and whilst this did achieve an allocation of water w ithin sustainable limits, it was politically unpopular Hence, the Minister in the p ublic interest changed the method (to reflect past use) and this caused different winners and losers. The case means that the macro public interest will over- weigh individual considerations. The American audience were fascinated by this case.

I talked about other changes which were made without compensation: for example, judges in all the Australian states have upheld the decision-making processes of ministers who have: • reduced water allocations under plans6, • made it mandatory to hold a licence to store water in a dam, • restricted the amount held in a dam after 30 years of unimpeded use 7, • capped water use in a region 8 and • strictly enforced time periods set out in water plans for making applications for water9. The keenest interest was on the transition in policy. I continued with the Harvey case. The region was the Murrumbidgee River w hich is at the heart of the most irrigated and productive land in Australia. The o ld Act, the Water Act 1912, had an explicit policy of over-use but this fell out of favour in the light of ESD principles in 1992. The judge described the evolution of policy in NSW in these terms:

84 JUNE 201o water

refereed paper

Under the regime of the Water Act 1912 entitlements under licences within the lower Murrumbidgee area reached 512.409ML per year (according to the Murrumbidgee Groundwater Assistance Model developed by the relevant NSW Government Department). This resulted from the policy of controlled depletion of groundwater directed at addressing salinity and maximising regional economic benefits from groundwater. By the mid 1990s concerns emerged about the environmental impacts of groundwater depletion and the long-term viability of groundwater resources. In August 1997, the NSW Government released a policy document directed towards achieving sustainable use of groundwater. This led to a moratorium being placed on the grant of new licences within the area on 1O September 1997. In April 1998 the Murrumbidgee groundwater system was identified as at risk by reason of resource overallocation. By August 1999 the moratorium imposed in 1997 became an embargo on new licence applications. 10 Hence, the new scheme under the WMA11 was designed to ensure sustainability and the relevant government department decided after much scientific work to reduce the allocations by 52% across t he board based on entitlements under the old act. The reductions were advertised to the community and initially an across the board reduction was approved by t he Minister. This type of method had been used in South Australia 12 and in other places. Eventually, and with considerable reference to the desires of the thenFederal Minister 13 , the NSW Minister made a new plan which included reference in the reduction formula to be based on historical extractions of groundwater. The case concerned complaints by Harvey and Tubbo that the amendment order completely changed the basis for the allocation of reduced entitlements to licence holders. The judge had to decide on that issue and issues of procedural fairness and t he public interest. Here the two plaintiffs wou ld lose more water if historical factors were considered rat her than the across the board reduction in allocations. 14 The Judge fou nd t hat the breadth of t he Act and the ESD objects did authorise such a change in the public interest and that, in such cases, to allow individuals to be heard would creat e an infinite regression of individual cases all of which could affect water allocations: [E]very time the Minister accepted one person's submission it would be

potentially adverse to every other person with an interest in the same water source because the interests are interlinked and potentially competing. This "would be unworkable, because it would lead to an infinite regression of counter-disputation". 15 It would also be incapable of achieving the statutory objective of "the sustainable and integrated management of the water sources of the State for the benefit of both present and future generations. 16 3 . The lack of compensation for reductions in water allocations as above. 4. The creation of water plans in each state which must be consistent with various instruments of policy 17 and have due regard to matters when formulating water plan including the socio economic impacts of the proposals_1 a Such plans which provide for water sharing must have these core provisions: 19 • t he establishment of environmental water rules, • the identification of requ irements for water within the area or from the water source to satisfy basic landholder rights, • t he identification of req uirements for water for extraction under access licences, • the establishment of access licence dealing rules for the area or water source, and • t he establishment of a bu lk access regime for the extraction of water under access licences, having regard to these ru les and requ irements. The user now gets an access licence and a share component to a specified share in a water source (the share component) 20 and a right to take water as specified (the extraction component).

5. The buy-back schemes, where state government s and the federal government are using the water markets to buy back water from farmers for environmental purposes. The impact of such buy back on communities and also the impact of government purchasers on t he prices and the fairness of the markets.

6. The urban demand reduction schemes and limits on watering gardens.

7. The referral of power under arrangements in the constit ution in section 51 (37) in four States to support the Water Act 2007. How did th is work? and the mechanisms involved (statebased legislation mirroring each other).

technical features

• '

agricultural use

ref e reed pap er

10 Harvey & Anor v Minister Administering the Water Management Act 2000; Tubbo Pty Ltd &

8. The powers in the Water Act 2007 to review state water plans in the MurrayDarling Basi n region and its objects to manage water in t he national Interest, and to implement relevant international agreements. How were these going to work? For this I used the cartoon (Figure 1) which summarises the issues.

The Author

Summary

Citations

The processes that have led to the making of the transition to an ESD policy and the interaction with the legal system (which have upheld these) were of great interest to t he American audiences. The questions and comments revealed to me that many in their governments are seeing t he need for a peaceful change to the existing regi mes and t heir heavy path dependency on old rules. We have fou nd this in current research wit h Aust ralian irrigat ors and policy makers21 who can see t hat the implementation of ESD is essential, although difficult. All political governance issues are a quest to find t he balance between short and long term gains for the economy, t he ecology and societies and with regard to freshwater allocat ion Australia is in the vanguard , in showing a t ransition process toward ESD.

1 State of South Australia v O'Shea [1987] HCA 39; (1987) 163 CLR 378 at 411 ).

Jennifer M cKay is Professor of Business Law and Director of the Centre for Comparative Water Policies and Laws, University of South Australia. jennifer.mckay@unisa.edu.au.

2 Minister for Local Government v South Sydney City Council (2002) 55 NSWLR 381 at [18]), 3 The Water Act 2007 defines "measures" to include also strategies, plans and programs. 4 "Biodiversity" means the variability among living organisms from all sources (including terrestrial, marine and aquatic ecosystems and the ecological complexes of which they are a part) and includes: (a) diversity within species and between species; and (b) diversity of ecosystems 5 Harvey & Anor v Minister Administering the Water Management Act 2000; Tubbo Pty Ltd & Ors v Minister Administering the Water Management Act 2000 [2008] NSWLEC 165 (18 June 2008), New South Wales Land and Environment Court 6 Rowe v Lindner and Ors [2007] SASC 189 7 Ashworth v Victoria [2003] VSC 194 8 Bates v Minister for Environment and Conservation 2006 SAERD 24 9 Miehe/more v Minister for Environment and Conservation 2004 SASC 415

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Ors v Minister Administering the Water Management Act 2000 [2008] NSWLEC 165 (1 8 June 2008), New South Wales Land and Environment Court. per Jagot J 11 And previous legislation 12 Elandes v Minister 13 Minister Turnbull under the Howard government 14 Harvey applicants forwarded an email to the attention of the Minister protesting the unfairness of the history of extraction policy and urging a return to the across-the-board cuts policy. 15 Minister for Local Government v South Sydney City Council (2002) 55 NSWLR 381 16 In Harvey per J 17 SWMOP plan is the outcome of political processes at a very high level. For example, the State Water Management Outcomes Plan sets the over-arching policy context, targets and strategic outcomes for the management of the State's water sources having regard to the broadest possible considerations of environmental, social and economic issues, as well as inter-governmental agreements and international agreements to which the government of the Commonwealth is a party (sections 6(2) and (3)). Per Jagot J 18 Section 18 of the WMA 2000 19 Sections 20(1)) of the WMA 2000 20 Section 56 of the WMA 2000 21 Picturing Water use and justice in rural Australia,2010 McKay, Keremane and Gray CRC Irrigation Futures.

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agricultural use

refereed paper

IMPACT OF IMPROVED RECYCLED WATER QUALITY ON A SYDNEY IRRIGATION SCHEME J T Aiken, C Derry, R Attwater Abstract Treated effluent has been used for irrigation, including for some food crops, by the Hawkesbury Water Recycling Scheme at the University of Western Sydney, Hawkesbury Campus, for some years. In recent years the STP concerned was upgraded from trickling filter to IDAL. The impact of improved effluent was compared with previous observations, in all, over a four year period. Monitoring of water quality in on-site storages suggest ed that recycled water impoundments should be regarded not merely as storage buffers but as a continuation of the treatment train in wh ich improvement or deterioration of water quality can occur with time, under the action of physical, chemical and biological factors and is an important area requiring further research. End-user interests also need to be studied with agriculturalists preferring high nutrient irrigation water and environmental and health managers preferring low nutrient levels.

Introduction The Hawkesbury Water Recyc ling Scheme (HWRS), situated at the Hawkesbury Campus of the University of Western Sydney on the urban-rural fringe of the Sydney Metropolitan Area, receives treated effluent from Sydney Wat er's Richmond STP. The water flows into a network of open storage impoundments from which it is pumped to sports fields, lawns, experimental fru it and vegetable crops, and pasture for cattle, sheep, fallow deer and horses. On average, about 1.5 ML per day of recycled water is supplied through an agreement based on a 30 -year partnership between UWS and SWC. Treated environmental flows are discharged into Rickaby's Creek, a tributary of Sydney's main river system, the Hawkesbury Nepean (Booth et al. 2003). Up to late 2005 the supply was essentially secondary, involving a

8 6 JUNE 2010 wat er

Richmond STP c~treated effluent supply from stabilisation ponds)

-------Âˇ

CPI

----

First storage dam (110 ML capacity)

CP2

Second storage dam (88 ML capacity)

Food crop irrigation area

Figure 1. Components and control points (CPn) in the water recycling system. trickling f ilter (TF) process with pond stabilisation. In response to the agein g and overloaded nature of the plant preliminary health-risk assessment was carried out by the University to monitor changes in effluent quality in terms of a limited range of parameters measured at sequential control points in the reticulation. Following the assessment a multiple-barrier approach for managing water quality and human exposure was put in place to reduce direct and indirect exposure risk, the methodology and results of which have been published elsewhere (Derry et al. 2006, Attwater et al. 2006). In 2005 Sydney water carried out extensive alterations to the STP,

Storage of recycled water is part of the treatment train.

replacing the old TF process by intermittently decanted aerated lagoon (IDAL) process with tertiary treatment involving sand filtration and chlorination/ dechlorination. The process was designed with a high capacity to anticipate population increase in Sydney's rapidly growing North Western sector, and high wet-weather flow events. The literature shows that IDAL treatment has an impressive ability to remove nitrogen from effluent by a process of nitrification/denitrification in a carbon- rich environment, resulting in the harmless discharge of nitrogen gas to the atmosphere (Weiner and Matthews 2003). Potential for IDAL process optimisation under relevant local cond itions has been described (Rajanayagam et al. 1999). Commissioning of the unit enabled reduction of health risk in terms of crop irrigation and direct human exposure, and simultaneously reduced the risk of eutrophication which had in the past been responsible for blooms of algae and, occasionally, toxin-producing Microcystis ("blue-green algae") (Derry et al. 2003). In addit ion the removal of chlorine prevented the formation of possibly-teratogenic disinfection by-products (Hrudey 2009). Following the preliminary health-risk assessment in 2005 using the limited range of parameters mentioned in the abstract, data collection conti nued for a further two years yielding four years of data for equal periods before and after the STP upgrade. During this data collection period the mean annual throughput remained relatively constant owing to unchanging irrigation demand during a time of almost continuous drought. The paper discusses the changes in effluent quality observed with passage through the Scheme's storage dams both before and after the introduction of IDAL process/tertiary treatment, with implications for open dam storage of high and low quality effluents in general.

technical features

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agricultural use

refereed paper

Method

Table 1. Received effluent quality before and after the STP upgrade.

Monitoring points were fitted proximate to control points in the supply line leading to the horticulture precinct where experimental food crops demanding high quality water were under irrigation (Figure 1). These coincided with valved or pumped critical control points, allowing for cessation of supply should a water quality problem be identified. The indicated dams are basin- shaped, claywalled open impoundments with a maximum depth of about 4.5 m, which have been in use for about 30 years with minimal maintenance. They offer good opportunities for sunlight exposure and aeration through wavelet action, and minimal wall erosion has been noted. It was estimated that there was a mean retention time of about 73 days in the first dam and 58 days in the second. A minimal set of seven parameters (FC, TP, TN, BOD 5, pH and SS) relevant to performance, health and ecological impact was selected for sampling. Samples were analysed by the Environmental Health Laboratory of the University of Western Sydney in compliance with standard methods (APHA 2005), field collection being consistent for method, day and time. Quality control involved submission of random samples to an external NATA accredited laboratory. Transient indicators pH and EC were monitored on-site using a monthly-calibrated YeoKai 611 ® water quality analyser.

Parameter

FC TP

STP effluent quality from TF process (median value)

STP effluent quality after IDAL upgrade (median value)

Action-threshold value for most critical irrigation use (salad-crop irrigation)

240 cfu 100 mL· 1

0 cfu 100 mL·1

10 cfu 100 mL·1

8.62 mg

L·1

0.02 mg L·1

2 mg L·1

32.0 mg

L·1

15 mg L·1

BODs pH

13.0 mg L·1

2.0 mg L·1

20 mg L·1

7.8

7.7

6.0- 9.0

SS (TSS)

15.5 mg L·1

2.0 mg L·1

30.0 mg L· 1

0.973 dS m· 1

0.930 dS m·1

1.6 dS m· 1

4.1 mg

Table 2. Changes in TF effluent quality prior to upgrade, with dam storage alone. Parameter

FC TP

STP effluent quality before dam storage (median value)

STP effluent quality after dam storage (median value)

Action-threshold value for most critical irrigation use (salad-crop irrigation)

240 cfu 100 mL·1

14.0 cfu 100 mL·1

10 cfu 100 mL·1

8.62 mg

L· 1

32.0 mg

L· 1

B00 5

13.0 mg L· 1

SS (TSS)

4.25 mg

L·1

2 mg L·1

6.05 mg

L· 1

15 mg L·1

4.1 mg L·1

20 mg L· 1

7.8

8.5

6.0 - 9.0

15.5 mg L· 1

6.0 mg L·1

30.0 mg L· 1

0.973 dS cm·1

0.837 dS cm·1

1.6 dS m· 1

Non-parametry of the data was determined and relevant tests applied to for significance in terms of the assumed statistical level (p=0.05), followed by boxand-whisker plotting using the same statistical application (SPSS®).

Results and Discussion STP effluent quality changes following IDAL upgrade

effluent received by the Scheme occurred as shown in Table 1.

TF effluent quality changes with storage , prior to upgrade Storage of the original TF effluent in the Scheme's dams resulted in some improvement in median values for all parameters, with TN, an important indicator of eutrophication potential, removed to the point of com pliance with the action-threshold limit. A 1 log (90 %) removal of FC also occurred, approaching the limit for the most critical irrigation use, salad crop irrigation (Table 2).

Median values were calcu lated and Following the commissioning of the compared to the intervention action!DAL-process unit, significant threshold values adopted for the Scheme improvements in median quality for as shown in Table 1. In the absence of integrated agricultural and health action-threshold values for irrigation reuse schemes in . CP1 Australia a consolidated set of 0 CP2 values was established based on Q CP3 local and international guidelines 3 and publications ..J (ANZECC/ARMCANZ 2000; E 0 0 ARMCANZ/ANZECC/ NHMRC ..... 2000; Asano 1998; DEC NSW <.> 2004; EPA Victoria 1993; C> 0 Lazarova, Bahri 2005; NSW ..J u RWCC 1993; USEPA 1992; WHO LL. 1989). This ensured that the experimental production of fruit and vegetables in the horticulture precinct complied with standards 0 for safe salad crop production After Upgrade Before Upgrade relevant to an equivalent commercial setting. Issues Figure 2. FC (log) by control point, before and after upgrade. associated with intervention (Note: in this semi-log graph the y-axis zero point indicates the values in Australia will be arithmetic zero). discussed in a later paper.

Stored water quality changes by parameter While median values for FC suggested low health risk, relatively high inter-quartile and total ranges showed that there were times when FC "peaks" occurred , suggesting a corresponding increased risk of pathogen passage through the system. For ti mely risk identification and intervention, including communication with st akeholders, a relatively high frequency of routine monitori ng (weekly) was thus req uired (Attwater, Derry 2005; Derry, Attwater 2006).

water JUNE 2010 8 7

agricultural use

ref ereed paper

. CP1 I!) CP2 QCP3

22 20 '18

CP1

Q CP3

E] CP2

40 35

t14

...J

t- 10

8 6

"6, E 25

E 12

20 15 10

2 + - - - - - t - - - - - - - - i~:t----t----1

B efore Upgrade L

After Upgrade

Before Upgrade

Stage of Treatment

Figure 3. TP by control point, before and after upgrade.

Faecal coliform The Australian Water Quality Guidelines establish an action-threshold val ue of 1O CFU (t hermotolerants) per 100 ml in irrigation waters used for salad-crop irrigation via direct application, such as overhead irrigation (ANZECC/ARMCANZ 2000). At the time of the study WHO recommended a far less stringent standard (1000 CFU/100 ml). The lower value was, however, adopted to account for the observed wide inter-quartile and total ranges in the local effluent (WHO 1989). Median values (horizontals within each coloured box) indicated a better-then 1 log reduction with passage of the TF effluent through the Campus system. The wide inter-quartile and total ranges, however, showed that there were times when a "pathogen spike" cou ld pass th rough the reticulation suggesting the accepted practice of using median 11 values for smal l potable supplies to be inadequate for biologically active effluents 10 (NHMRC 2004). Following risk assessment, surface micro-jet irrigation was replaced by subsoi l irrigation which introduced a 10-15 cm soil barrier. 70 cm barriers are known t o achieve 2 - 3 log reductions (99.9% removal) of FC (Kadam et al. 2008). While the IDAL upgrade resulted in the supply of a very high quality, stable effluent, FC increase occurred

88 JUNE 2010 water

After Upgrade

Stage of Treatment

Figure 4. TN by control point, before and after upgrade.

with passage th rough the Scheme 's dams. This was possibly due to flocks of birds, including duck, introducing faecal matter to the dams (Graczyk et al 2008). The possibility of natural increases in FC was unlikely but is undergoing further research.

Total phosphorus, total nitrogen and pH Following the upgrade the nitrogen and phosphorus content of t he effluent was considerably reduced (Figures 3 and 4). This had positive implications for irrigation runoff which might enter the Hawkesbury Nepean River contributing to eutrophication (Asano 1998). The graded removal of phosphate from the TF effluent with passage through the dams, and subseq uent addition of phosphate to the IDAL effluent in the same dams is of interest suggesting that

phosphate precipitated from the old effluent might have been stored in sediments to be later released on contact with the softer IDAL effluent. This led to the persistence of algal blooms in the final dam, despite the upgrade. It was found that pH increase was a useful indicator for anticipating this bloom in irrigation use and odour control (Weiner, Matthews 2003). While simi lar decrease in TN oc curred with passage of the TF effluent, a corresponding increase with subsequent passage of t he IDAL effluent was not observed. This suggests that w hile phosphates were removed from the old effluent by sedimentation, nitrates were probably removed by nitrification/ denitrificat ion in the presence of excess dissolved carbon. An interesting paradox was associated with the improvement of effluent through IDAL process to result in very low nutrient levels. One pasture manager had est imated a saving of about $10,000 per .CP1 [J CP2 annum in fertiliser costs when Q CP3 using the old, high nutrient effluent. Health and ecological ad vantages of a low nutrient water supply may have, however, offset th is disadvantage suggesting a need for triple bottom line assessment of agricultural irrigation reuse schemes.

Biochemical oxygen demand, suspended solids and electrical conductivity

Before Upgrade

After Upgrade

St age of Treatment

Figure 5. pH by control point, before and after upgrade.

BOD 5 , SS and EC (Figures 6-8) are frequently used to provide basic information on general operating performance and

technical features

....

agricultural use

refereed paper

105 ~

--------------~

100 g5

...J

85 80 75 70 05

. CP1 O CP2 O CP3

55 50 46

55 50

45 40 ...J

0) eo

ii,'

1:n 35

(/)

~ 25 20

25 20 15 10

.CP1 fil:) CP2 O cP3

~--'+------ - - --------'

10 5

0 ,5 _ _ , _ - - - . . - - --

0 - - - - ~ ~- -- '

Before Upgrade

After Upgrade

,9 -' ~

Before Upgrade

Stage of Treatment

Figure 6. B0D 5 by control point, before and after upgrade.

threats in sewage treatment and storage systems (APHA 2005). BOD results for both TF and !DAL effluents were within the action-th reshold emphasising the limitations of using this indicator alone. In the relatively low-BOD TF effluent, t he storage dams still exhibited some capacity for removal for BOD. Increase in BOD seen in the very stable !DAL effluent again suggests the introduction of extrinsic organ ic poll ution. Some removal of SS by physical settlement was taking place in the relatively turbid old effluent, but increases again occurred with passage of the new effluent through the same storage dams, possibly from sediment leaching with biomass increase or bird life contamination. Results for EC were consistently low, as expected from a non-industrial effluent. This also confirmed that t he clay dam walls were relatively intact and an effective barrier to 2.0 soil salinity which is known to occur in the regi on (Bowler 1.8 1976). 1.6

Figure 7. SS by control point, before and after upgrade.

t o improve low quality effluent to the point where it met some recycli ng req uirement s, high quality effluent conversely underwent degradation when introduced into the same impoundments. This probably involved leaching of phosphates from old sediments and the addition of nutrient faecal matter f rom bird life, with accompanying algal growth. The study suggested that basic operation and safety of recycled water storages can be monitored using a few well-established water industry indicators at a limited number of control points. Median data often accepted for smallscale potable impoundments are, however, inadequate for stored effluent and the analysis of measures of spread for all parameters is indicated. To detect short-term indicator excursions

Conclusions The research showed that recycled wat er impoundments should be regarded not merely as buffer storages, but as a conti nuation of the treatment trai n in which improvement or deteriorat ion of water quality can occur with time, under the action of physical, chemical and biological factors. While storage in t he Scheme's dams had capacity

E 1.4-

vi u 1.2 -0

1.00.8 0.6-

After Upgrade

Stage of Treatment

â&#x20AC;˘4$

,-99

Before Upgrade

After Upgrade

Stage of Treatment

Figure 8. EC by control point, before and after upgrade.

suggesting opportunities for pathogen transm ission t hrough systems, frequent monitoring is needed, again pointing to t he need for small, economical indicator sets with potential for local analysis. Health risk management associated with quality fluctuat ions in low quality effluent should be based on a multiplebarrier approach including the ability to divert water at strategic control points in the reticulation for reflux or additional stabilisation in buffer storage. Measures such as soil-irrigation barriers also need consideration. Ultimately food production hygiene and human exposure limitat ion wi ll rely on good risk communication with stakeholders to provide effective information feedback systems. While the study focused on surveillance (ongoing, routine monitoring), special monitoring is req uired if xenoestrogens, pesticides, heavy metals and . CP1 other persistent pollutants are O CP2 to be detected and controlled O CP3 in water intended for food-crop irrigation or for direct addition to water supplies (Echols et al. 2009). Specific bacterial, viral or protozoa! monitoring is also needed where epidemiology suggests that local waterborne infections may exist. Other areas requi ring special monitoring are algal b looms and their causes, odour problems, leaching of substances from sedi ments, nitrification-den itrification opportunities, and potential for wildlife contamination.

water JUNE 201o 89

agricultural use End-user interests also need to be studied with agricu ltu ralists preferring high nutrient irrigation water and environmental and health managers preferring low nutrient levels. Removal of health indicators such as FC and Enterococci to a zero point is, however, unjustified and a range of intervention action-threshold limits shou ld be established with a view to matching recycled water purity, and hence cost, to intended use. Wh ile guidelines have recently been produced dealing with t he direct addition of treated effluent to drinking water su pplies (EPHC 2008), irrigation is likely to remain an important option, with foodcrop irrigation allowing the water to reach its highest economic potential. Optimising the use of accessible treated effluent and stormwater resources will depend largely on t he capacity of recycling schemes to safely store water, particularly largely untapped wet weather flows. In this regard the changes occurring in recycled water quality with storage remains an important area req uiring further research.

refereed paper

The Authors

At the time of the study Dr Jane Aiken was a field technical officer for t he Hawkesbury Water Recycling Scheme, University of Western Sydney. Currently she is environmental team leader with Bilfinger Berg er Services (Australia) Pty Ltd, and a private consu ltant specialising in soil science.

Chris Derry is Principal Researcher and Health Risk Analyst with CRC Irrigation Futures and WHO Collaborating Centre for Environmental Health Development, University of Western Sydney, specialising in safe water recycling and food crop irrigation. Email: c.derry@ uws.ed u.au (corresponding author).

Acknowledgments The authors wish to thank Capital Works and Facilities and t he Enviro nmental Health Laboratory, UWS for sampling and analysis, and the Sydney Water Corporation for the provision of STP data.

Water Advertising To reach the decisionmakers in the water field, you should consider advertising in Water Journal, the official journal of the 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

90 JUNE 2010 water

Dr Roger Attwater is Senior Manager, Environment and Risk Management, with Capital Works and Facilities, University of Western Sydney. His background and interests focus on the integrated management and sustainabi lity of environmental assets.

References ANZECC/ARMCANZ, Australian and New Zealand Environment and Conservation Council/ Agriculture and Resource Management Council of Australia and New Zealand, 2000. Australian and New Zealand guidelines for fresh and marine water quality book 4, ANZECC, Canberra. ARMCANZ/ANZECC/NHMRC, Agriculture and Resource Management Council of Australia and New Zealand/Australian and New Zealand Management and Conservation Council/National Health and Medical Research Council, 2000. Guidelines for sewerage Systems: Use of Reclaimed Water, ANZECC, Canberra. APHA, American Public Health Association, 2005. Standard Methods for the Examination of Water and Wastewater, APHA, Washington, DC. Asano, T. (Ed.), 1998. Wastewater Reclamation and Reuse, Water Quality Management Library Vo l. 10, Technomic, Lancaster, Pennsylvania. Attwater, R., Aiken, J., Beveridge, G., Booth, C.A., Derry, C., Shams, R. and Stewart, J ., 2006. An adaptive systems toolkit for managing the Hawkesbury water recycling scheme. Desalination, 188, 21-30.

Attwater, R., Derry, C. , 2005. Engaging communities of practice for risk communication in the Hawkesbury Water Recycling Scheme. Action Research, 3, 193209. Booth, C.A., Attwater, R., Derry, C. and Simmons, B., 2003. The Hawkesbury Water Reuse Scheme, Water, 5, 28-30. Bowler, J.M., 1976. Aridity in Australia: age, origins and expression in aeolian landforms and sediments. Earth-ScienceReviews, 12: 179-310. DEC NSW, Department of Environment and Conservation (New South Wales), 2004. Environmental Guidelines: Use of Effluent by Irrigation, DECC, Sydney. Derry, C. , Attwater, R. and Boot h, S., 2006. Rapid health risk assessment of effluent irrigation on an Australian university campus. International Journal of Hygiene and Environmental Health, 209, 159-171. Derry, C. and Attwater, R. , 2006. Risk perception and communication relating to effluent irrigation on a University campus, Water, 33, 57-62. Derry, C., Booth, S. and Att wat er, R., 2003. A Risk Management Approach to Sustainable Water Reuse. Environ. Health, 3, 78-86. Echols, K.R., Meadows, J.C., Orazio, C.E.. 2009. Pollution of Aquatic Ecosystems: Hydrocarbons, Synt hetic Organics, Radionuclides, Heavy Metals, Acids, and Thermal Pollution, Encyclopedia of Inland Waters, Elsevier, New York. EPA Victoria, Environment Protection Authority (Victoria), 1993. Guidelines for environmental management: use of reclaimed water. Publication 464.2 as amended, EPA Victoria, Melbourne. EPHC, Environment Protection and Heritage Council, 2008. Managing Health and Environmental Risks (Phase 2): Augmentation of Drinking Water Supplies, EPHC, Canberra. Graczyk, T.K., Majewska, A.C., Schwab, K.J ., 2008. The role of birds in dissemination of human waterborne enteropathogens, Trends in Parasitology, 24, 55-59. Hrudey, S.E., 2009. Ch lorination disinfection byproducts, publ ic health risk tradeoffs and me, Water Research, 43, 2057-2092. Kadam, A.M., Oza G.H., Nemade, P.O., Shankar, H.S., 2008. Pathogen removal from municipal wastewater in constructed soil filter, Ecological Engineering, 33, 37-44. Lazarova, V. and Bahri A., 2005. Water Reuse for Irrigation: Agriculture, Lands, and Turf Grass. CRC Press, New York. NHMRC, National Health and Medical Research Council, 2004. Australian Drinking Water Guidelines, NHMRC , Canberra. NSW RWCC, New South Wales Recycled Water Coordination Committee, 1993. NSW Guidelines for Urban and Residential Use of Reclaimed Water, NSWRWCC, Sydney. Rajanayagam, C.D., Nguyen, T., Sinanovic, Y. and Walker, J.W. , 1999. Identification of the potential capacity of an intermittently decanted aerated lagoon (I DAL) through process optimisation, Wat. Sci. Tech., 39, 135-142. USEPA, United States Environmental Protect ion Agency, 1992. Guidelines for Water Reuse, Report EPN625/R-04/108, Cincinnati. Weiner, R.F. and Matthews, R.A., 2003. Environmental Engineering, ButterworthHeinemann, Amsterdam. WHO, World Health Organisation, 1989. Health guidelines tor the use of wastewater in agriculture and aquaculture. TR 778, WHO, Geneva.

technical features

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refereed pape r

BIOSOLIDS IN A REAL FARM SITUATION W Rajendram, A Surapaneni, G Lester-Smith Abstract This paper examines the outcomes of a study which tracked the impact of biosol ids application on soil, plant and feed (silage/ hay/grain). Whi lst such studies have been mainly limited to experimental plots in the past, an attempt was made to undertake t he study under a "real farm management regime".

Biosolids were applied at t he rate of 98 dry tonnes/ha t o cover around 7.9 ha of farm land. A 5 m buffer was observed which was used as a "control study" area. Triticale was planted in both biosolids t reated and control areas. Soil, herbage and grain samples were analysed and results from the analyses suggest that:

Biosolids Quality The Gisborne RWP biosolids are C2, due to elevated copper and zinc concentrations. C2 biosolids are suitable for a range of beneficial uses, including agricultural use.

• Contaminant build up in the soil due to biosolids applicat ion was negligible; • Nutrient (P and K) build up in the soil due to biosolids application was significant;

The purpose of t he study is to assess the positive impacts of t he ongoing farm application of biosolids generated from Western Water's Recycled Water Plants in order to build confidence among the farming commu nity. Whi lst there are numerous st udies of this nature worldwide including Australia (e.g. DPI 2007, McLaughli n et a/. 2008), such studies under real farmi ng situations (paddock scale) are limited.

..L

Figure 1. Map of the Study Site.

• Nutrient (N, P, Kand S) bu ild up in the herbage due to biosolids application was sig nificant; • Concentrations of most metals in the herbage in the biosolids treated areas appeared to be considerably lower than that grown in the "control study" area. The results provide increased confidence to the end-user of the benefits of biosolids application.

Introduction Western Water's Gisborne Recycled Water Plant (Gisborne RWP) is a tertiary t reatment plant t hat collects and treats around 1 ML per day of sewage from the township of Gisborne. The tertiary treatment process consists of an act ivated sl udge process with chemical precipitation of phosphorus. Waste Activated Sludge (WAS) is collected in a sludge lagoon and the lagoon is de-

This paper was presented at the AWA Biosolids Speciality Conference, May 2010.

sludged every six to eight months. The sludge is t hen dried on a sludge drying bed and transported to another Western Waters recycled water plant facility located at Romsey. At the Romsey facility (near the Macedon Ranges), the sl udge is generally turned mechanically unt il a solid content of 70% is achieved. At this stage the product is referred to as biosolids. Western Water has been applying biosolids generated from its Gisborne RWP on two farms (known as "Trethellen" and "Red Hill of Macedon") comprising in total around 125 ha area, located at Woodend in Victoria (Figure 1). The farms consist of a number of individual paddocks defined by fencing . The biosolids application is undertaken under an Environment Improvement Plan (EIP) approved by the Victorian Environment Protection Authority (EPA). In order to get an understanding of the benefits and potential adverse impacts of the biosolids, it was decided to undertake an analysis of soil and crop (herbage, si lage, grain and straw) subsequent to the application of biosolids.

The Gisborne biosolids used in this study have been digested in sl udge lagoons and discharged to drying beds. Subsequently they are then stockpiled for two years. The treatment process does not meet recognised T1 or T2 t reatment processes, therefore a T3 grading was targeted. Testing for E.coli showed that the biosolids readily meet T3 microbiological criteria specified in the Victorian EPA guidelines. As a C2/T3 product, the Gisborne biosolids are suitable for land application for agriculture including sheep grazing or human food crops that are processed or cooked before consumption (e.g. cereal crops, oil seeds). Risk management practices include 30 day post-application wit hholding period for grazing and crop harvesting and preferably incorporation of the biosolids (e.g. by ploughing).

Biosolids Application "T?'' paddock at the Trethellen farm (Figure 1) was chosen for application of biosolids in 2009. Biosolids samples and soi l samples from "T?'' paddock were

>ma1yses u, uo n

nutrients and contaminants in the feed produced. water JUNE 2010

agricultural use

re fe ree d pa p er

analysed and an appl ication rate was calculated as per the nutrient loading application rate (NLAR), a contaminant limiting application rate (CLAR) and cadm ium loading rate. NLAR is the site-specific rate at which biosolids can be applied to land without exceeding t he annual crop/pasture nutrient requirement. Contaminant and nutrient concentrations of biosolids appl ied to paddock "T?'' is provided in Table 1. As per EPA Guidelines it was determined as a C2 quality. As discussed previously t he biosolids had a treatment grade of T3 . The CLAR was calculated for each contaminant in t he biosolids. This determined the rate at which biosolids application wil l achieve the Receiving Soil Contaminant Limit (RSCL) set by t he Victorian EPA to protect human health, the envi ronment and food safety. To ensure t hat biosolids applicatio n does not result in significant accum ulation of cadmium in the soil, t he biosolids guidelines impose a maximum cadmi um loading limit of 150 g/ha/5 years. Relevant soi l data prior to biosolids application is shown in Table 2. On 23 April 2009, the b iosolids from Gisborne RWP were applied t o the "T?'' paddock. A 5 m w ide buffer was observed around t he paddock as per the Victorian EPA Guidelines. Triticale (rust resistant Yakuri variety) was used as the test crop. Triticale is a cross variety between wheat (Triticum species) and rye (Secale spec ies) and is used in livestock diets as an energy source. Its major strengt h is its versatility for use as silage, hay, grain and straw. The crop was planted on 14 May 2009 in both biosolids treated and on the buffer (control) area. Biosolids were spread using a mechanical spreader. The biosolids were applied at a rate of 97.7 dry tonnes per hectare (123 product tonnes/ha) based on NLAR. After app lication to t he surface of the soil , the biosolids were incorporated into the soil.

Sampling Program A sampling program (Table 3) was undertaken in close consu ltation w ith the property owner. Two sample poi nts were selected at the buffer strip located in the north and west of "T?'' designated as the "control study" area. Four sample points were selected from the biosolids applied area designated t he " treated study" area. The points were recorded with GPS for future sampli ng. For consistency, the same locations were used for soil and herbage sampl ing. Soil samples were collected at bot h topsoil (0-10 cm) and subsoil (10- 45 cm) depths. Soil and herbage samples were collected on 10 August 2009 from the control study area and t he biosolids treat ed area. In total 12 soil and 6 herbage samples were coll ected. On 5 November 2009, part of the crop at one of the sampl ing points in the designated as control st udy area was harvested for producing silage (see Table 3). On 11 November 2009, part of the crop at one of the sampling points in the designated biosolids treated area (Site 1) was harvested for hay. The rest of t he crop was left to produce grain (see Table 3). Silage samples were collected on 20 January 2010. Grain samples were collected by t he property owner o n 15 January 2010 at the t ime of harvest. Straw and soi l samples were also co llected on 20 January 2010 following grain harvest. For consistency, it was ensured that hay, silage and grain samples were collected from areas

Table 2. Soil tests prior to the application of biosolids. Soil test

Paddock "T7" 0-1 Ocm depth 10-45 cm depth

Salinity EC1,5

Table 1. Properties of biosolids used in paddock "T7".

Analyte

Mean Concentration

pH(CaCl2)

Units

dS/m

0.28

0.07

4.6

5.2

Arsenic (As)

mg/kg

2.5

Sodicity

Cadmium (Cd)

mg/kg

0.6

ESP

Chromium (Cr)

mg/kg

Nutrients

Copper (Cu)

mg/kg

124

Bray P

mg/kg

Lead (Pb)

mg/kg

P sorption

mg/kg

Mercury (Hg)

386

mg/kg

0.7

P sorption index

Nickel (Ni)

mg/kg

Exchangeable K

me/1O0g

0.6

Selenium (Se)

mg/kg

2.5

Zinc (Zn)

mg/kg

265

3.2

Aldrin

µg/kg

<0.5

4.4'-DDD

µg/kg

<0.9

4.4'-DDE

µg/kg

<0.10

4.4'-DDT

µg/kg

<0.11

Dieldrin

µg/kg

<0.12

Heptachlor

µg/kg

<0.19

Heptachlor epoxide

µg/kg

<0.20

Hexachlorobenzene (HCB)

µg/kg

<0.21

Total Polychlorinated biphenyls

µg/kg

<0.26

Total Nitrogen as N

mg/kg

5186

Total Phosphorus as P

mg/kg

5765

92 JUNE 201o water

4.9

2.9

Organic matter Organic carbon Heavy metals Arsenic (As)

mg/kg

1.1

Cadmium (Cd)

mg/kg

<0.5

Chromium (Cr)

mg/kg

110

Copper (Cu)

mg/kg

Lead (Pb)

mg/kg

Mercury (Hg)

mg/kg

<0.2

Nickel (Ni)

mg/kg

Selenium (Se)

mg/kg

<0.5

Zinc (Zn)

mg/kg

EC1,5=Electrical conductivity in 1:5 soil:water extract, ESP=Exchangeable sodium percentage

technical features

agricultural use

refereed paper

Table 3. Sampling program undertaken at Paddock "T7" . Sample type

Cut date

Soil - 11 o days after application Soil - 9 months after application Herbage - 90 days after sowing Silage Hay Grain Straw

Sampling date

Control Area Site 1 Site 2

Site 1

Biosolids Treated Area Site 2 Site 3

Site 4

10-Aug-09

5-Nov-09 11-Nov-09 15-Jan-09 15-Jan-09

20-Jan-10 10-Aug-09 20-Jan-10 20-Jan-10 15-Jan-10 20-Jan-10

• Indicates sampling locations previously designated as sampling points. One sample of silage from the control area (Site 1) and one hay sample from the treated area (Site 1) were collected. Four composite samples of grain - consist ing one sample from the control area (Site 2) and samples from three of the designated sampling points in the treated area (Sites 2-4) were collected.

Based on the above aims, analysis of samples was carried out using: • A suite of chemical measurements for determining the build up of contam inants in the soil, herbage, hay, straw and grain; • Soil chemistry from an agric ult ural point of view ; • Nutrient val ue of hay and grain as stock feed material.

Sample numbers were limited due to time and cost constraints. However, the number of samples has been assumed to be reasonable as the soil type and t he topography of t he area is considered fairly uniform in t he paddock "T7''.

Results and Discussion

Table 4 lists the laboratories used for the analysis of biosolids, soil, silage, hay, grain and straw.

The soil prior to applicat ion of biosolids in Paddock "T7'' was non-sali ne, non-sodic and moderately acidic (Table 2). Both

Nutrients and Contaminants in Soil

Study The main purposes of the study were to: • Assess whether the application of biosolids had inc reased t he unwanted contaminants in t he soil; • Det ermine whether t he application of biosolids resu lted in the uptake of any unwanted contaminants in the plants grown in the biosolids treated area including during both the growing and harvesting period;

Table 5. Soil tests 110 days after biosolids application. Soil test

Units

dS/m

Table 4. Laboratories used for analysis.

ESP SAR 1,5 Nutrients Total P Bray-1 P

Sample type

Olsen P

• Assess the potential agronomic benefits of biosolids as a soil additive; • Determine whether applicat ion of biosolids improved feed value and nutrient composition.

Biosolids - pre application Soil - pre application

Soil - 90 days after application Herbage - 90 days after application Silage Hay Grain Straw Soil - Post grain harvest

Laboratory

ALS Laboratory Services National Measurement Institute & Department of Lands Scone Research Centre DPI Werribee 1 DPI Werribee Weston Technologies 2 Weston Technologies Weston Technologies & DPI Werribee Weston Technologies DPI Werribee

1Victorian Department of Primary Industries, Werribee 2Weston Food Laboratories operated by George Weston Foods Pty Ltd, Enfield, New South Wales

10-45 cm depth

Control Area (n=2)

Treated Area (n=4)

Control Area (n=2)

Treated Area (n=4)

0.09

0.07

0.11

5.1 4.3

4.9 4.3

5.3

4.9

4.6

4.3

<1 <1

1298 74 43

615 10

230

550 4 6 73

3.6

3.5

2.2

1.4

<0.3 44 6

<0.3 76

<0.3 104 9 11 0.0

Salinity

EC1,s pH pH(water) pH(CaCl 2) Sodicity

• Assess whet her there was any build up of contaminants in the grain;

0-10 cm depth

<1 mg/kg mg/kg mg/kg mg/kg

Skene K Organic matter Total carbon Heavy metals

570 10 13 115

Arsenic Cadmium Chromium

mg/kg

mg/kg mg/kg

<0.3

Copper Lead Mercury

mg/kg mg/kg mg/kg

Nickel Selenium

mg/kg mg/kg mg/kg

Zinc

8 0.0 10 0.08 13

68 13 10 0.0 12 0.13 26

9 129

9 9 0.1 21 0.13 16

19 0.15 15

SAR 1,5= Sodium Adsorption Ratio in 1:5 soil:water extract

water JUNE 2010 93

agricultural use Table 6. Soil tests 9 months after biosolids application (post grain harvest). Soil test

Units

0-1 O cm depth Control Area (n=2)

Treated Area (n=4)

10-45 cm depth Control Area (n=2)

Treated Area (n=4)

Salinity

EC1,5 pH pH(water)

dS/m

pH(CaCl2) Sodicity ESP

0.07

0.18

0.05

0.11

4.9 4.3

5.2 4.9

5.5 4.7

5.3 4.9

Nutrients

Bray-1 P

mg/kg

Olsen P Skene K

mg/kg mg/kg

9 11 84

57 35 156

3 5 69

10 8 127

available P and potassium levels appear low. Organic carbon is considered high given the soil used for cropping is located in a low rainfall area of Victoria (Peverill et al. 1991 ). All contaminants concentrations were below t he receivi ng soil contam inant limits (RSCLs) for biosolids. Similar results were observed 110 days after biosolids application, with the notable exception of nutrients (Table 5). Phosphorus (total and available forms) and available potassium (Skene K) levels in the treated areas for both top and subsoi l depths increased substant ially compared to the control area. Even nine months after the application of biosolids, available P and K remained notably higher in the treated area (Table 6). The crop to be planted foll owing the Triticale crop at paddock "T7'' is expected to benefit as a result of build up from the biosolids application. Contaminant dat a for the post harvest soils was not available when this paper was prepared. However, it is not expected t hat contaminants wil l increase in the treat ed area.

Nutrients and Contaminants in Herbage, Grain and Straw An increase in nutrient concent rat ion in the herbage (3 months growth crop) grown in the biosolids treated area was noted particularly for N, P, K and S (Table 7). Interestingly, herbage Fe and Al concentrations decreased eight fold in the treated area in comparison with the control area. It is possible that in the biosolids treat ed area in this acidic soil, t he additional P is enabling formation of Fe and Al precipitates, rendering less Fe and Al available to plants. There is no clear evidence of contaminants accumulation in t he herbage in the treat ed area (Table 7). As in the case of herbage, nutrients (N, P, Kand S) in the Triticale grain appeared to be higher in the biosolids treated area compared to the control area (Table 8). Again no discernable differences were observed in contaminants concentration in the grain w ith and without biosolids application (Table 9), except zinc. Cadmium is one of t he few elements in biosolids that can concentrate in cereal crops and reach levels that render the grain unfit for human consumption. To protect human health, a limit of 0.1 mg/ kg has been set in Australia as the maximum limit (ML) for wheat grains in foodstuffs (FSANZ, 2005).

94 JUNE 201o water

refereed paper

Table 7. Herbage Analysis - mineral nutrients and contaminants. Parameter

Units

Control Area

Treated Area Mean

Nitrogen

Phosphorus Potassium Calcium Magnesium Sodium Sulfur

4.3 0.31 2.6 0.28 0.18 0.06 0.33

5.1 0.49 4.1 0.26 0.14 0.02 0.52

Cobalt Boron Molybdenum Manganese

mg/kg

1.3 4.5 0.13

0.3 4.3

Iron Aluminium Arsenic Cadmium Chromium Copper Lead Nickel Selenium Zinc

% %

% % %

mg/kg mg/kg mg/kg mg/kg mg/kg Âľg/kg mg/kg mg/kg mg/kg mg/kg mg/kg Âľg/kg mg/kg

235 3050 2100 179 0.13 6 7 0.95 2.3 28 24

0.14 198 378 255 34 0.06 7 0.15 0.8 15 39

Table 8. Mineral nutrients in Triticale Grain (dry matter basis). Mineral Nutrients

Nitrogen Phosphorus Potassium Calcium Magnesium Sulfur Manganese Iron Cobalt Molybdenum Chloride

Units

Control Area

Treated Area Mean

2.2

2.7

mg/kg

2870 5100 408

4393 5877 417

1130 1550 56 45 0.1 0.12 733

1297 1790 84 63 0.1 0.2 663

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Table 9. Heavy metals in Triticale Grain (dry matter basis). Heavy metals

Units

Control Area

Treated Area Mean

Arsenic Cadmium Chromium

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

<10 <0.03 0.3

<10 0.04 0.6

5 <0.01 0.75 15

5 <0.1 1 23 44

Copper Lead Nickel Selenium Zinc

mg/kg mg/kg

Cadmium concentration in t he grain is shown in Table 9. The results indicate that the human health limit level is not exceeded. Potassium, sulphur and zinc are observed to be higher in the straw grown in biosolids treated area (Table 10).

technical features

Table 10. Mineral nutrient in the Triticale Straw (As Feed). Mineral Nutrients

Units

Control Area

Treated Area Mean

Nitrogen

mg/kg

Phosphorus

mg/kg

Potassium

mg/kg

Calcium

mg/kg

0.4 505 6730 1520 682 603 83 56 8 11 83

0.4 431 12457 1270 487 740 89 47 25 1474

Magnesium

mg/kg

Sulfur

mg/kg

Manganese

mg/kg

Iron

mg/kg

Zinc

mg/kg

Chloride

mg/kg

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Table 11. Feed value attributes and mineral nutrients in the Triticale Silage (As Feed) in the Control Area (Site 1). Parameter Dry matter Metabolizable Energy (ME)

Units

Control Area

32 3 88 20 12 3.5 0.7

MJ/kg

Relative Feed Value (RFV) Neutral Detergent Fibre (NDF)

Acid Detergent Fibre (ADF)

Crude protein

Starch

Ammonia % Crude protein

Ammonia % Total nitrogen

Nitrogen

Phosphorus

mg/kg

Potassium

mg/kg

Calcium

mg/kg

Magnesium

mg/kg

Sulfur

mg/kg

Manganese

mg/kg

Iron

mg/kg

Zinc

mg/kg

Chloride

mg/kg

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6.4 1.7 3150 20200 3340 21 40 2670 252 170 22 7302

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Feed Quality - Hay, Silage, Grain and Straw Inad vertently, the crop in the control area was pac ked for silage prior to t he col lection of hay sample. The hay harvested from treated area w ere not provid ed for silage. T herefore there was no hay sample available from the c ontrol area and no silage sample was avai lab le from the treated area for a com parative assessment. Ho wever, feed tests and m ineral content data for sil age (Table 11) and ha y (Table 12) are still considered usefu l for f uture comparison w ith silage and hay produc ed from the biosolids treated c rops. Feed quality data for the grain is shown in Table 13 . An increase in crude protein and a decrease in starch w as noted in t he grain harvested from the biosolids treated area (Table 13).

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agricultural use

ref e r e ed paper

Table 12. Feed value attributes and mineral nutrients in the Triticale Hay (As Feed) in the biosolids Treated Area (Site 1). Parameter

Units

Treated Area

87 7

Dry matter

MJ/kg

Metabolizable Energy Relative Feed Value Neutral Detergent Fibre

Acid Detergent Fibre

Crude protein

Starch

feedin g in A ust ralia. In t his study, 2% mo re p rotein was o bserved due to b iosolids appl ication compared to the control (Tab le 13). This should be of notable interest to livestock nutritionists. It is considered that lower starch content in t he grain from biosolids treated area is advantageous for ruminants. Starch from cereal grain is hydrolysed rapidly in the rumen, which may adversely affect rumen function and cause su bacute ruminal acidosis (King, 2010). Feed value attributes for the Triticale stalk d id not vary between t he biosolids treated and t he contro l areas (Table 14).

Nitrogen

mg/kg

Phosphorus

mg/kg

Potassium

mg/kg

Calcium

mg/kg

Magnesium

mg/kg

Sulphur

mg/kg

Manganese

mg/kg

Iron

mg/kg

Zinc

mg/kg

Chloride

mg/kg

Feed Value Attribute

Units

Metabolizable Energy (ME)

MJ/kg

11 .2

18.7 3.6 9.7 53.2

Crude protein

Biosolids application increased nutrient concentration in the soi l. The concentrations of contaminants in t he b iosolids app lied soil were below the Receiving Soil Contam inant Limits. Nutrients in herbage and grain under bi osolids treatment increased in com parison with the control. Overall biosolids

Starch

Lysine

Methionine

0.4 0.2

Feed Value Attributes Dry matter Metabolizable Energy (ME)

Units

11.3 17.0 3.1 11.7 48.2 0.4 0.2

Control Area Treated Area Mean

% MJ/kg

91 4.8

Relative Feed Value (RFV) Neutral Detergent Fibre (NDF)

Acknowledgment

Acid Detergent Fibre (ADF)

Crude protein

55 3

The Authors

202 93 32 6272

Table 14. Feed value attributes of Triticale Straw (As Feed).

market for t utu re.

The aut hors w ish to acknowledge the assistance provided by the following personnel in the preparation of t his manuscript: George Croatta and Ron Walsh, both from Department of Primary Ind ust ries (DPI Werribee); Nicole Cooper from Western Water; and Dominic Flanagan from L.V. Rawlinson & Associates, Transpacific Industries Group Ltd.

2130 2900

Control Area Treated Area Mean

Neutral Detergent Fibre (NDF) Acid Detergent Fibre (ADF)

There appears to be a number of benefits of biosolids application on soil, plant and feed. Further studies are needed in order to assess other possible positive impacts of biosolids under "real farming conditions" to establish a solid biosolids

1.8 3280 18200 3200

Table 13. Feed value attributes of Triticale Grain (As Feed).

Conclusions

improved feed grain quality.

90 53 34 3.5

93 4.6 40 81 61 3

Gavin Lester-Smith is the owner of the property "Trethellen" on w hich the trials were conducted.

References DPI (2007) Department of Primary Industries. The National Biosolids Research Program - Victorian Component. Final Report, June 2007. FSANZ (2005) Australia and New Zealand Food Standard Code. Incorporating up to including amendments 80. Food Standards Australia and New Zealand. Anstat. Pty Ltd , Canberra, Australia. King R (2010) Triticale: stock feed guide, In: www.waratahseeds.com.au

W illiam Rajendram is Senior Envi ronmental Engineer w ith Western Water, Sunbury, Vic. email W ill iam .rajend ram@westernwater .com.au. Aravind Surapaneni, Product Quality Scientist w ith South East Water, s upervised the an alyses.

96 JUNE 201 o

water

McLaughlin M, Bell M , Nash D, Pritchard D, Whatmuff M, Warne M, Heemsbergen D, Broos K, Barry G, and Penney N. (2008). Benefits of using biosolid nutrients in Australian agriculture - a national perspective. Proceedings of the AWA Biosolids Specialty Conference IV, 11-12 June 2008, Adelaide. (Oral Presentation 04. 14 p.). Peverill, Kl, Margetts, SW, Brown, AJ , Greenhill, NB, and Monro, GR (1991 ) The analytical and interpretative service. (Ag-plus, Melbourne). van Barrneveld R (2001) Triticale - a guide to the use of triticale in livestock feeds. Grain Research and Development Corporation, Canberra, ACT.

technical features

water trading

THE MATURING WATER MARKET IN THE SOUTHERN MURRAY-DARLING BASIN G Egan Abstract In recent years , the southern MurrayDarling Basin (MDB) has faced unprecedented low rainfall and low water availability. This has placed major stresses on those who live in the MDB and depend on wat er for their living. The major water users are irrigat ors and they have entered the water market to use it as part of thei r management program. This is providing opportunities for participants to make their own decisions about when and whether to use water in a given year, and how much capital they wish to dedicate to water assets. The paper outlines t he past history and future direct ions of this growing market.

Nole Rtp(ese~ alion of 1he lnters1ate 'Mlle< Tfading zones ateindic.tr.-e ol'lly.

Soulh Australia

, o.-ao.itM ...

Introduction

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The water market in t he southern MDB has grown over the last twenty years from practical ly nothing to a major contributor to the management of that most valuable asset, water. Originally water rights were t ied to land, with trade generally non-existent. But a growing awareness of the need to better use the water we have and the 1994 intergovernmental agreement to impose a cap on diversions fro m the MDB, prompted t he development of form al market arrangements. Limited trad ing started in the late 1980's, and t he first interstate trade of allocation occurred in 1995 and of entitlement in 1998. In 2004, t he Victorian government proposed unbundling to encourage trade, and the states agreed in the National Water Initiative to undertake various reforms to support market s.

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Figure 1. Interstate Water Trading Zones. The water market is now very significant. The National Water Commission (NWC) reported in its 2008/09 Aust ralian Water Markets report that t he volu me of trade of entitlements in t he southern MDB was 1080 gigalitres (GL) and of allocat ions was 1739 GL. It advised t hat the water market in the southern connected MDB continued to

The market is working well but is still developing.

Sale of Equipment -

grow in 2008- 09 and remains the major water market in Australia. This article reflects on some of t he activities t hat are occurri ng in this market-place, with special refer ence to Victoria. It points to some evide nce of success and also acknowledges areas t hat need improvement. On th is basis the market is characterised as ' mat uring'.

The Scope of the Market The southern MDB is the food basket of Australia. It includes major river systems

2 sets of 3 x 71 kW Floating Aerators used to add oxygen to the treatment process 3 currently dismantled from the Sanora WWTP (dismantled Feb 2008) 3 fully constructed from the Sanora WWTP Purchased: 1984 Used until: February 2008 Tenders close: 4.00pm on Wednesday 21 July 201 0 in the Tender Box located in the foyer at the Tweed Shire Council Civic Centre, Tumbulgum Road, Murwillumbah, New South Wales, 2484. Technical enquiries should be directed to Mr Steven Bray, on phone number 02 6670 2600.

water

JUNE 2010 97

water trading (Murray, Darling, Murrumbidgee, Goulbu rn , and others) that are interconnected and to some extent present interchangeable resources. As such water can generally be traded (with some hydrological restrictions) across vast distances. A map of the southern MOB and its trad ing zones is shown in Figure 1. The water market in the southern MOB is a market in many interrelated products. The primary split is into two products ent itlements (the ongoing rig ht to a share of a water resource) and all ocations (the volume of water made available with in a season to an entitlement). The entitlement market is further split into t he various entitlement products, by State, by valley and by rel iability ranking - examples are Victorian Murray high reliability water shares, or NSW Murrumbidgee general security water access licences. The all ocat ions market is generally not spl it with free t rade generally (although not always) available across the major water systems of the southern MOB.

Why the Market Works As for any market, the water market depends on the fact that different water users have different needs for water and hence value it differently. At a given price, there will be people who see that as a price at wh ich t hey would sell and others who regard it as a price at which to buy. These decisions are driven by the businesses in which individuals are involved and their personal and financial circumstances. While th is is true of any market, the water market has an additional strength in the non-homogeneous nature of the uses to which wat er is put. In Victoria (and it is similar throughout the southern MOB), the uses can be classified into three broad categories. Annual cropping (in Victoria to grow fodder or to fatten sheep or beef) is the most flexible, with t hese people likely to see value in selling their water at low prices. In the middle is t he dairy indust ry - dairy-farmers cannot leave and re-enter the industry easily, but they can buy fodder or grain as a substitute for growing their own food. And at the top are horticulturalists, who cannot feed hay to their trees or vines, and whose assets take many years to replace if they are deprived of water. Within eac h of these rough groupings t here is also a range of business drivers. These cou ld include contract and pricing situations, whet her there is pressure from banks to free up some cash, and indeed pressure simply to gain cash to su rvive

98 JUNE 201o water

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Figure 2. Volume of allocation trade in Northern Victoria. t ill better times. Commodity prices for t heir produce and for replacement inputs (eg. price of hay or grain) also impact on t he pricing decision. Another fou ndation of a good market is t he transparency of market operations and the knowledge of market participants. This again is an area where improvements and growth have occurred. The Victorian water register website (www.waterregister.vic.gov.au) provides information about a variety of market matters, including the volume and reported price of each trade, the overall number and volume of trades of each product, the performance of approval authorities against service standards for approval times, the progress of an individual allocation trade, and trading rules. Other states provide similar information and a new Commonwealth website (www. nati onalwatermarket. gov .au) provides links to relevant information for each state. Market support is provided by water brokers, exchangers and solicitors, whose services are more commonly soug ht now that the market is larger and the value of transactions has grown. The ACCC has provided some valuable brochures for water brokers/exchanges and their customers to outline obligations and rights. But there is still plenty of room for improvement in transparency and provision of good information to market participants. Challenges include further reducing the time taken for approvals, improving the reporting of pricing data, improving understanding of some trade restrictions (for example, trade t hrough the Barmah Choke), educating

participants about some of the inherent complexities of complex products and hydrological realities.

The Market is Operating Well These factors have act ed to provide a growing market for water. For instance the volume of allocation t rade in Victoria has grown at an annual rate of about 13% over the last ten years, as shown in Figure 2. Trade of entitlements is also growing, with 2008/09 volumes in northern Victoria of 238 GL. This component of the market has been strongly influenced over recent years by two quite separate drivers. Firstly, t here was strong demand for entitlements, especially Victorian high reliabil ity, to provide a secure water supply for new greenfield horticultural developments (mainly grapes, almonds and ol ives) in northern Victoria. The main developers were corporate ventures, often using managed investment schemes to obtain capital. Over the last 12 months or so, some of these have fall en on hard times, and new development is not currently occurri ng. Quite coincidentally, t he drop-off in demand from such investors has been replaced by a much bigger buyer - the Commonwealth government, through its Restoring the Balance program. Under this program, $3.1 B is committed to purchasing wat er entitlements in the wider MOB, with the majority of it targeted at the southern MOB. The Commonwealth 's involvement is creating major challenges for t he market, as it is by far the biggest buyer and its buying patterns have a major impact on seller opportunities and price.

technical features

water trading One controversial rule for trade of entit lements is t he 4% annual limit on trade out of irrigation areas. This is subject to litigation brought by South Australian government against the Victorian government, and is therefore not discussed in this article.

Table 1.

Importantly, urban water corporations have also entered t he market in Victoria in order to provide water to their customers, and reduce government intervention t hat wou ld otherwise be needed to ensure that basic human needs could be serviced. Cities and towns t hat are embedded in irrigation areas (such as Shepparton and Mildura) have been involved in the water market for some time, albeit in different ways. Shepparton has, in t he past, often been a sel ler of annual allocat ion as it has an entitlement t hat caters for future growth, while Mildura has been buying to build up its entitlement as it grows.

Cost to move the water

Bendigo and Ballarat are more recent arrivals into the marketplace. The Goldfields Superpipe, completed in 2008, now connects them to the Waranga Western channel in the Goulburn water system and hence they can take delivery of water from the southern interconnected MOB. Both these ci ties are now part icipants in the water market, buyi ng both water entitlements and allocations. These supplement thei r exist ing entitlements that have been savaged by drought, and p rovide a source for future growth in these important regional cities. The market has been essential to allow Bendigo and Ballarat to have secur ity of supply, and yet t heir involvement in the market has been modest in compariso n to t he overall size of the market. Since J uly 2007 , purchases and sales by Cen tral Highlands Water and Caliban Water have made up approximately 3% of approved trades within the Victorian allocation market and approximately 6% of recorded transfers with in the Victorian entit lement market . It is also worth noting that Melbourne is also con nected to the Goulburn water system via another new pipeline (from Yea to Sugarloaf), but Melbourne is not a participant in the water market. Instead its water is part of the savings

Tagged entitlement

Owned entitlement and trades of allocation

Clear ownership of capital asset

Yes

Carryover rights against entitlement

Yes

Access to water at the 'use' location

By order

By trade of allocation

Generally zero, but likely to be similar to trade of allocation

Normal trade application fees

Tag only allowed in an 'always can' direction

Depends on trading rules

Guarantee that water can be moved

produced by invest ment in irrigation infrastruct ure efficiency improvement s.

Interstate Trade of Allocation Interstat e trade of allocation is alive and well with substantial volumes occurring in the southern interconnected MOB. The NWC has reported that there is a strong market in interstate water allocation trade. In 2008-09 , interstate trade accounted for 28% of trading vol umes (calculated by counting only the sellers' side of the transactions). New South Wales was a net exporter of water allocations to Victoria and South Australia (553 GL in total). Victoria exported 30 GL to South Australia, but experienced a net increase in water due to imports from New South Wales. In the 2008/09 year, this was a particularly valuable component of trade. It allowed SA and Victorian users (predom inantly horticultural or dairy indust ries) to do deals with Murrumbidgee cereal growers. The

Murrumbidgee general security allocation level was far from att ractive to them (at 31 % for general security entitlements) as it was insufficient and too late in t he season to support any sort of sizeable crop. But it was a useful amount of water for other users and substantial volumes changed hands. This benefited buyers who were able to preserve permanent plantings, and sellers who had insufficient water to make a crop worthwhi le, but were still able to get some income from the sale of water allocations. This is a good illustrat ion of a market benefiting from the presence of non-homogeneous users.

Interstate 'Interoperability' As illustrated above, interstate trade of allocation is common and wellestablished. However it is administratively more chal lenging t hat an intrastate trade. Both the buyer and seller state have responsibilities during the trade approval process, and the outcome of t he trade has to be recognised in the

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water JUNE 2010 99

water trading registers of both states. The authorities undertaking t hese approval processes have created a strong ethos of cooperation, and t he individuals involved know each other quite well, and work through the routines well. Nevertheless the process requires manual transfer of information between t he two states and can lead to some occasional difficulties. An important initiative currently being implemented by Victo ria, NSW and SA is what is termed 'int erstate interoperability' of water regist ers for allocation trades. Interoperability will eliminate most of the manual interactions between the th ree states. Instead each State's regist er is being amended to send information directly to the relevant other state, and then to act on such transferred informat ion. This wi ll not require trade applican ts to make any changes, but is expected to reduce the workload, minimise errors, and speed up the approval process. Ultimately, the common registry system component of the National Water Market System is expected to incorporate the essentials of this interoperability feature and potentially expand it to cover other t ransactions, such as the ordering of water under a tagged t rade of entitlement.

Tagged Trade of Entitlements Tagged trade of entitlements between valleys and stat es is a relatively new development in the marketplace. Unt il 2007, this sort of trade happened mainly via what was termed 'exchange rate' mechanism by which an entitlement was 'converted (at the relevant exchange rate) from the entitlement held by the seller to the type of entitlement local to the buyer. For instance a Victorian Murray water right was converted into a SA licence. However there was concern, lead init ially by NSW, that t his process could have th ird party effects. The buyer ended up wit h a product different from that given up by the seller. A carefully chosen exchange rat e could fix t hat 'on average' but not for each individual year, and even that depended o n confidence about the reliability and yield of each product for the future. Given t hat it is difficult to predict the future, an alternative process was developed. The buyer could become

1 oo JUNE 201 o water

t he owner of the precise same product and preserve all its features , but could 't ag ' it to be used in the destination valley/State. This new approach is now established, with about 300 Victorian water shares tagged for use in a different valley. But there are sti ll some questions about how it can be best managed, especially for interstate tagging. The number of interstate tags has been very low, and this has been wrong ly labelled in some commentaries as an absence of interstate trade of entitlement. In fact, that is still alive and well , although there is no hard data on its prevalence - suffice it to say t hat a substantial volume of Victorian water shares are owned by people with an address that is outside Victoria. So interstate trade of entitlement is taking a different form, with users purchasing a water entitlement in another state, deciding where and when to use that water and then moving that water by means of an all ocation trade. In fact the advantages of undertaking t he act ual 'tag' are not very substantial, as outlined in Table 1. It is t imely t hat a review be conducted of whether it is a worthwhile process and if so, how it can be made more attractive to the marketplace. It is worth sayi ng, as a post-script, that t he re-emergence of the previous 'exchange rate' model is very unlikely.

Other Markets and Products The above analysis is concentrated on t rade of entitlements and allocat ions in the southern MDB, and this wi ll remain t he most important water market. However there are interesting developments elsewhere and in other prod ucts. Within Victoria t here is market activity in other water systems. In southern Victoria, trade is occurri ng (in small volumes at this stage) in the Thomson/Macalister and Werribee water systems. In a recent development there, trade rules have been amended to allow trade from irrigators in the Thomson/M acalister system to Werribee, using t he Melbourne delivery system as t he transport mechanism. This wi ll necessarily be very limited in volume, but opens the door for Werribee irrigators (more impacted by drought) to take advantage of the different climatic conditions of eastern Victoria.

Since July 2007, limited term transfers (or leases) of water shares have been available in Victoria. This has been taken up by some market participants with about 200 being executed to date. Further promot ion of this capability may be useful. Private organisations are worki ng on options prod ucts of various ki nds to help irrigators to manage risks better. An organisation could use its balance sheet to 'guarantee' a certain minimum volume of water to a customer. Improved carryover arrangements are expanding the time reach of the market. No longer does t he end of an irrigat ion season mean total uncertainty about water avai lability. While new al locations wi ll be totally dependent on storage levels and inflows, individuals can use t he market during one season to set t hemselves up for future seasons. As has been fou nd in other markets, individual ingenuity will come into play to develop products and variations that meet customer needs.

Conclusion The water market in the southern MDB is working well but is still developing. Governments and market participants need to work together to address issues in order to provide water users with flexibility and certai nty to the greatest extent possible. This is good policy in any case, but is particularly important given the enormous water management chal lenges faced by all Australians. Note: The opinions expressed are those of the author and not necessarily those of the Department of Sustainability and Environment.

The Author

Gerry Egan is t he Manager Water Market Development in the Office of Water at t he Department of Sustainability and Environment in Victoria. Prior to joining the water sector, Gerry spent 25 years working in the energy sector in construction, maintenance, market and risk management roles . Gerry.egan@dse.vic.gov.au.

technical features

[1@J

water supply

refereed paper

GEO-ENGINEERING DAMS FOR BOTH GLOBAL COOLING AND WATER CONSERVATION I Edmonds Abstract Implementing a reflective cover on the surface of a dam to reduce evaporation provides two benefits; not only the useable water gained but a significant global cooling effect; the latter effect arising from "gee-engineering" the dam. To quantify both benefits, this paper derives simple expressions for the global temperature cooling effect, dT = -30NAe C and for the additional water yield, Y = AcR m3/ yr. Here A is the area of dam covered , Ae is the Earth's surface area, E is the evaporation mitigation efficiency and R is the evaporation rat e in m/ yr. To illustrate the benefit s for irrigation supply the paper estimates the yield from a cover on the Hume dam and the income from water conserved. For the case of urban water supply it is shown that a cover on the SEQ dams could supply the projected increase in SEQ water yield to 2040 and that, with conservative estimates of cover cost, the increased yield could be provided at a cost significantly lower than t he cost of other water supply options. The global cooli ng effect of the reflective cover can be equated to the cooli ng effect obtained by geosequestration of CO2 â&#x20AC;˘ It is shown that the equivalent gee-sequestration is given by dC = 0.146A ton nes CO2 . In the, currently hypothetical, situation where global cooling by gee-engineering receives the same Carbon Credit as global cooling by CO 2 sequestration the implementation of a reflective dam cover would receive a large one-off Credit. The expressions derived are used to estimate this income. The potential ecological effect of evaporation covers on dams is briefly discussed.

Introduction Geo-engineering involves increasing the solar reflectance of an area so that more

Potential for offsetting carbon credits against capital cost.

Fig 1A. Modular EMCs comprise a floating framework covered with a reflective fabric. Figure 1B. An image of part of Wivenhoe dam with white rectangles superimposed to represent the appearance of twenty reflective pods, each pod (0.5 km x 0.5 km) comprising 800 EMCs. The twenty pods shown would yield about 10 GL/yr by reducing evaporation. solar energy is reflected back to space and a global cooling effect is obtained (Lenton and Vaughan, 2009). A simple example of gee-engineering is painting a black roof white, (Akbari et al, 2009). Fresh water absorbs 90% of incident solar energy and the reflectance or albedo of fresh water is very low, < 0.1 . As a result a dam surface appears black when viewed from high altitude and is the ideal starting surface to gee-engineer into a reflective surface. If a white cover (albedo - 0.6), is installed over a large water surface a large global cooling effect is obtained due to less solar heat being absorbed by the Earth. This does not imply a significant change in temperature of the reservoir water as less absorption of solar heat is compensated by less cooling by water evaporation. The global cooling can be equated to the global cooling that cou ld be obtained by removing CO2 from the atmosphere, for example by reforestation of farmland. As a resu lt, gee-engineering project s could attract similar Carbon Credits to reforestation projects and could generate a positive economic return . Suspending a cover above a water surface reduces wind speed across the surface and evaporation is reduced by up to 90% (Craig I. et al,. 2005). As the rate of evaporation from Australian dams varies from 1 to 3 m/ yr

(Bureau of Meteorology) depending on latitude, reducing evaporation provides a large increase in water yield. This paper outlines the potential to obtain increased water supply and global cooling and assesses the cost relative to other water supply options.

Evaporation Mitigation Covers (EMC) and Potential Water Savings The purpose of an EMC is to provide a cover above the water surface to reduce air movement over the surface and to reduce absorption of solar energy. Currently available commercial EMCs are designed for implementation on rural water stores typically a few hectares in size. Of the various types of EMC available (Craig et al, 2005) this paper is concerned with the modular type EMC where a reflective fabric or shade cloth is suspended above the water surface on a floating frame. An example of a small (4m x 4m) floating module is shown in Figure 1A. The modular type of EMC illustrated has an efficiency, E, of about 0.9 (Craig et al 2005) i.e. the evaporation loss is reduced by 90%. For application on dams with areas of the order 100 km 2 this type of t echnology would need to be scaled up by a factor of about 1O (- 40 m x 40 m) to cover areas of about 1600 m 2

water

JUNE 2010 101

water supply and the form optimised to reduce wind loading on the module and to utilise fabric economically. Figure 1B shows an image of part of the storage area of Wivenhoe dam . The white rectangles superimposed on the image represent t he appearance of pods of EMC modules floating on the dam; each individual pod (0.5 km x 0.5 km) comprising several hundred individual EMC modules. Cost estimates for the modular type of EMC illustrated in Figure 1A were in the range $1 0/ m 2 - $20/ m2 in 2005, (Craig et al, 2005). However, these estimates were for applications in farm size water storages. It is likely that cost of EMC for application on 100 km 2 storage co uld be reduced by technical development and t he scale of project. The increased annual yield of water is given by Y = AER m3/ yr where A is the covered surface area of the dam, E is t he evaporat ion mitigation efficiency and R is the evaporation rate in m/yr for t he locality.

Agricultural and urban supply: the Hume Dam The Hume Dam, currently at 17% capacity and holding 523 GL, when full holds 3038 GL with a water surface area of 202 km 2. A cover over all the Hume Dam (A= 202 km2, E = 0.9 and R = 1m/ yr) wou ld give an increase in yield of Y = 182 GUyr. The current price of Victorian Goulburn high reliabi lity water is $2,300/Ml (MDBC, 2009) so this additional water would be worth $420M/yr. In addition, should geoengineering projects of t his type be included in any future emission trading scheme (ETS), the project cou ld attract a credit for CO 2 offset worth $600M as indicated below. These fig ures suggest t he commercial benefit of EMC on farm size rural dams could be extended to river basin size dams such as the Hume.

Urban water supply: the South East Queensland (SEQ) situation. Due to the large predicted increase in Aust ralian population in t he next 30 years urban water authorities are examining future water supply options, for example the draft SEQ Water St rategy (2009). Although evaporation mitigation is not currently a significant option within the various Australian water strategies it is useful to examine this option in view of the potential to combine water saving with global cooli ng which is also of future concern. SEQ residential water is supplied mainly from the Somerset, Wivenhoe and North Pine dams. The current system

102 JUNE 201 o

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[ill yield, 440 GUyr, exceeds the current residential consumption of 340 GUyr. However, the residential consumption is expected to increase to 760 GUyr by 2040 (SEQWS, 2009). To provide t hat consumption the yield must increase from 440 GUyr to 760 GUyr, an increase of 320 GUyr over 30 years. The draft SEQ water strategy (Queensland Water Commission, 2009) to provide this increase in yield includes the const ruction of desalination facil ities at Marcoola (73 GI/yr) , Lytton (73 GUyr) and Tugun (36 GUyr) during the next 30 years to provide an additional yield of 182 GU yr by 2040 at a cost of about $28. The strategy envisages the remaining required yield (140 GUyr) to be provided by construction of the Wyaralong dam and raising the Hinze, Borumba and Wivenhoe dams, a further $1 B. The Somerset, Wivenhoe and North Pine dams are located in shal low catchments and have a large surface area to storage ratio. The combined surface area of the existing dams when full is A= 170 km 2 . The evaporation rate, R, in SEQ is approximately 2 m per year (BOM). Th us evaporation loss from t he three dams is about 340 GUyr. This equals the current residential consumption , 340 GUyr, so the dams are losi ng, by evaporation, as much water as is being consumed by residents. Also, the amount cu rrently lost by evaporation, 340 GUyr, exceeds t he projected increase in residential consumption over the next 30 years, 320 GUyr. Evidently, most of the projected increase in consumption to 2040 could be supplied by implementing EMC on the dams.

Global Cooling Effect of Evaporation Mitigation Covers Due to the arid nature of the Australian continent evaporation loss and mitigation has been studied for a long time and there has been significant development of EMC primari ly directed to farm sized reservoirs (Craig et al, 2005). The possibil ity of combi ning t he economic benefit of increased water supply with the environmental benefit of global cooling suggests consideration of EMCs on larger reservoirs. An est imate of the amount of global cooling provided by an EMC can be found from basic climate science. The average temperature, T, of the Earth's surface in a basic two layer greenhouse model (I. G. Model) depends only on the incident solar radiation , S0 , and the average albedo, a , of the Earth 's surface according to T4 = S0 (1 - a)/2o Here T is

refereed paper

in degrees Kelvin, S0 is t he solar constant (1368 W/ m2 ), a is the average albedo of the Earth, (a= 0.3) and o is Boltzmann's constant (5.67x1 o- 8 W/ m2K4). This equation gives T = 303 K which is 5% higher than the actual T, (288 K), indicative of the simple model used. However, the model is sufficient for the present purpose. Differentiating the equation above to find how T changes when a changes by a small amount da we obtain dT = - (T/ 4(1 - a))d a = -1 08da. When a small area, A m2 , of the Earth's surface changes from albedo, aw, to albedo, ap, the average albedo of the Earth changes by da = 0.56(A/Ae)(a p aw) where the Earth's surface area Ae = 5.1x10 14 m2 . The factor 0.56 accounts for the fact that only 56 % of the solar radiation passes through the atmosphere and the clouds to reach the Earths surface. Thus the global cooling obtained is dT = - 108da = -60(A/Ae)(ap - a w). The albedo of t he surface of a freshwater reservoi r is close to 0.1 and the albedo of a weathered white plastic surface is close to 0.6 thus the change in albedo, (ap - a w), can be taken as 0.5 and t he expression simplified to: dT = -30A/Ae K.

(1)

For example if a white EMC was implemented on the Hume dam, (filled area A = 202 km 2), the global cooling obtained would be dT = -11.8x10Âˇ6 K. This appears to be a small global cooling. However, it can be shown to be equivalent to the cooling obtained by a large CO2 sequestration project.

Carbon Credit from Equivalent Carbon Dioxide Sequestration Any global cooli ng obtained by geoengineering can be equated to an equivalent global cooling obtained by removing CO 2 from the atmosphere (CO2 sequestration). As governments are establishing a price or Carbon Credit for global cool ing achieved by CO2 sequestration the same price can, in principle or by government fiat, be applied t o other methods of global cooling . The current mass of CO2 in the at mosphere is C = 3x10 12 tonnes. If this is changed by an amount dC t he resu lting change in global average temperature is given by dT = k.dC/ C where k is a constant central to climate change science. When there is no positive feedback associated with the change in surface temperature it is generally accepted (BOM) that a doubling of CO 2 (dC = C) leads to a temperature increase of 1.2 K. Th us, with

technical features

water supply

refereed paper

no positive feedback, t he equation can be written dT = 1.2dC/ C. With positive or negative feedback the constant k is respectively great er or less t han 1.2. The current IPCC view (SOM) is that positive feedback is dominant and that k is about 4 times larger than 1.2 i.e. k = 4.8. However, for our purposes it is necessary to take the no feedback case in order to compare with the model for albedo change used above as this model does not include feedback . Equating the temperature change due to CO2 sequestration (dT = 1 .2dC/ C) to the temperature change due to implementing an EMC of area, A, (dT = -30A/Ae) and rearranging we obtain dC = -25(A/Ae)C. Subst ituting Ae = 5.1x1014 m 2 and C = 3x10 12 tonnes the expression simplifies to: dC = -0.146A tonnes CO 2

(2)

Some examples of reservoir covers

North Parkes, NSW, 2008: Nylex and Rio Tinto joined forces to produce a product that achieved 95% reduction in evaporation losses.

Akbari et al (2009), using a much less direct method, found dC = -0.128A tonnes when black roofs are painted wh ite so the expression (2) can be regarded as a conservative est imate of CO2 sequestration equivalent.

Carbon credit for geo-engineering the Hume dam As an example, the implementation of an EMC on the Hume dam (A = 202x106 m2) provides global cool ing eq uivalent to the sequestration of dC = 0.146xA = 29.6 M tonnes of CO2 . The projected price of Carbon Credit in the Australian emission t rading scheme (ETS) is A$40 per tonne after 2011 (CO2 Aust ralia Ltd}. Thus the cooling obtained on implementing an EMC on Hume dam could be worth A$1200M.

Carbon credit for geo-engineering the SEQ dams With an combined area of A = 170x106 m 2 the equivalent CO 2 offset dC = - 0.146A = -24.8 M tonnes. At the projected $40/tonne Credit under t he proposed ETS t his geo-engineering project would be worth $1 B.

Could Carbon Credit and increased water income offset EMC investment cost? The Carbon Credit estimates above raise the interest ing question of whether t he continuing income from increased water supply and the one-off Carbon Credit income could offset the invest ment cost of an EMC. In the case of the SEQ dams the com bined dam area is A = 170x106 m2 so the potential increase in yield is Y = AcR = 306 GUyr. This is close to the projected increase in consumption to 2040. Under the draft

Preparing to spread plastic balls: Ivanhoe Reservoir, Los Angeles, 200 ML, 2007. The water needed to be shaded because sunlight with the bromide and chlorine formed the carcinogen bromate. No reduction in evaporation was targetted. SEQ Water Strat egy most of t he increased yield would be supplied by desalination at an operational cost of $1.08/kl. Desalinated water requires no f urther treatment. However, any increase in water from the dams req uires t he conventional treatment costing about $0.20/kl. Thus t he effective value of wat er saved from evaporation is $0.88/kl. The additional 306 GUyr at $0.88/kl is therefore worth $270 M/yr based on offsetting the cost of desalinated water. The potential total area for implementation of EMC is 170x106 m2 . Assuming a price range of $10/m2 - $20/m 2 , as c urrently available for farm dam covers the potential EMC cost is in the range $1.7 B - $3.4B. With t his range of EMC cost and t he possible CO 2 credit, ($1B), the net implementation cost could be between $1. 7 - $1 = $0.7B and $3.4 - $1 = $2.4B. Both figures are

lower than t he projected implementation cost (- $3B) of the draft SEQ water strategy.

Ecological effects of EMC The ecosystems in Australian reservoirs are complex and are affected, mainly, by water temperatu re, salinity, dissolved oxygen, nutrient concentration , bluegreen algae, reservoir water level and inter-relations between these, (Walker, 1985). Therefore an assessment of the effect of covering or partly covering a reservoir with an EMC is complex. A recent CSIRO study reported on the ecological benefits of shade covers for potable water storages (Finn and Barnes, 2007). Some general observations can be made. A suspended, reflective cover that reduces evaporation and maintains water volume in a reservoir will reduce salinity,

water JUNE 201o 103

water supply nutrient concentration, blue-green algae and water level change, the reduct ion of wh ich wo uld normally improve the ecology of a reservoir. The temperature of water in a reservoir is largely determined by the energy balance between solar absorpt ion and evaporation. A reflective cover red uces t he solar energy input and reduces the energy output via evaporation. Thus, depending on the balance, it is expected that a reflective cover wou ld have only a small positive or negative effect on water temperature. This is in contrast to transparent, monolayer type covers that do not decrease solar energy input and can substantially increase wat er Growth of temperature (McJan net et blue- green algae is promoted by the combination of warm water, light penetration and high nutrient levels. This combination is less likely to occur in reservoirs with a reflective cover. Reduction of blue-green algae should red uce episodes of severe oxygen level depletion that occur following blooms of algae. Water evaporation rate and oxygenation rate depend on the concentration gradients at t he water/air interface. The gradients and rates increase with wind flow over the water surface. Thus a system that reduces water evaporation by reducing wind flow will also reduce the oxygen transfer from air to water. As an adequate level of dissolved oxygen (-10mg/L) is critical for a healthy aquat ic ecosystem EMC should not be deployed on the entire surface of a dam. In particular the littoral zone around the dam perimeter where aquatic plants grow and photosynthesize oxygen shou ld remain uncovered as in Figure 1B. Further work is necessary to establish whether the effect of reflective covers on the ecosystems of reservoirs is positive or negative.

an.

Conclusion This paper introd uced the concept of implementing a reflective cover on dams to obtain a global cooling benefit and an increased water yield benefit. Expressions were derived to quantify both benefits. An economic val ue of the increased yield was estimated from current water costs. The global cooling resulting from the reflective cover could be related via a CO2 offset price to a return on investment in the cover. For dams such as the Hume that supplies water to irrigators in t he Murray River Basin the high ongoing income from the increased water supply as well as the potential one-off income from CO2 offset suggests that the implementation of EMC

104 JUNE 201o

water

r e fereed paper

on such large river basin dams shou ld be commercially viable . Due to the high evaporation loss in Queensland implementation of an EMC on t he SEQ dams could provide nearly all the projected increase in residential water supply to 2040. With a conservative range of EMC cost and the potential Carbon Credit for the global cooli ng effect t he implementation cost of an EMC on the three major SEQ dams could be lower than t he implementation cost of desalination plants and new and raised dams. EMCs for farm dams are commercially available but the technology for reduci ng evaporation on large dams is not well developed. However, t he dual benefits of water conservation and global cooling as outlined here suggest further development should be a priority. Consideration should also be given to including geo-engineering projects that reduce global warming directly by reflecti ng sun light and indirectly by reducing electrical energy consu mption within the types of project eligible for Carbon Credits in the proposed Australian ETS.

The Author

Craig I, Green A, Scobie M, and Schmidt E (2005).Controlling evaporation loss from water storages, Final Report. http://www.ncea.org.au/www/Evaporation%20Res ources/Downloads/Contolling%20Evaporation %20Loss%20from%20Water%20Storages%2 0final%20report.pdf Finn N. and Barnes C (2007) The benefits of shade-cloth covers for potable water storages. http://www.csiro.au/files/pdcj.pdf Lenton T.M. and Vaughan N.E. (2009).The radiative forcing potent ial of different climate geo-engineering options. Atmos. Chem. Phys. Discuss. 9, 2559-2608 Idealized Greenhouse Model, Wikipedia. http://en.wikipedia.org/wiki/ldealized_ greenhouse_model McJannet D, Cook F, Knight J and Burn S(2008) Evaporation reduction by monolayers: Overview, modelling and effectiveness. Technical Report 6, Urban Water Security Research Alliance. http://www.urbanwateralliance.org.au/ publications/UWSRA-tr6.pdf Murray Darling Basin Water Entitlements Summary of Prices 2009. http://www.environment.gov.au/water/ policy-programs/entitlement-purchasing/ pubs/market-prices-dec09.pdf South East Queensland Water Strategy Executive Summary 2009. http://www.q wc.qld.gov.au/myfiles/uploads/ seqws-2009/St rategy_20Nov09_Foreword_ ExecSummary.pdf Queensland Water Commission, SEQ Desalination Siting Study Costing 2009. http://www.qwc. qld.gov.au/myfiles/uploads/desal_studies_ nov09/Appendix%20C_Costing%20_Final%20 A.pdf Walker K F (1985). A review of the ecological effect s of river regulation in Australia, Hydrobiofogica 125, 111-129.

Dr Ian Edmonds is a physicist who operates an R&D company (www.solartran.com.au, email ian@solartran.com.au) that develops novel renewable energy systems and sustainable technologies for the building industry. Previous contributions to the water supply problem include "Northern River Water for Australian Cities" , Water, 34(6) 80-82 (2007) and "Reviving a River Basin", Water Engineering Australia, 3(7) 18-20, (2009).

References Akbari H, Menon S, Rosenfeld A. (2009). Global cooling: increasing world-wide urban albedos to offset CO 2. Climatic Change 94 (3-4) 275286 Also available at: http://www.energy.ca.gov/2008publications/ CEC-999-2008-020/CEC-999-2008-020.PDF Bureau of Meteorology- Evapotranspiration map http://www.bom.gov.au/cgi-bin/climate/ cgi_bin_scripts/evapotrans/et_map_script.cgi Bureau of Meteorology: Greenhouse Effect and Climate Change http://www.bom.gov.au/info/ GreenhouseEffectAndClimateChange.pdf CO 2 Australia ltd - CPRS Compliance Options, http://www.co2australia.com.au/index.php? sectionl0=6701 &pageID=6702

Water Advertising To reach the decisionmakers in the water field, you should consider advertising in Water

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technical features

technical note

FLUORIDE TESTING FOR SEEPAGE IDENTIFICATION: BEWARE! G Ruta Abstract On occasion water authorities are asked to invest igate the source of water seepage/accumulations within properties. Historically, fluoride tests of seepage water have been undertaken to assist. The general assumption being t hat, where water fl uoridat ion is practiced, seepages containing f luoride are likely t o be mains water or sewage, and vice versa. However, most test resu lts are inconcl usive in terms of the fluoride levels detect ed . This st udy looks at water/soil interactions with respect to fluoride levels and offers an explanat ion for t he often perplexing fluoride levels found in samples. An extension to current fl uoride test ing of seepages is proposed that may assist in clarifying observations and likely source(s) of seepages.

Introduction City West Water Ltd is t he water authority that manages t he water supply and sewerage distribution systems that provide drinking water and sewerage services to a popu lation of over 800,000 domestic , commercial and industrial users t hroughout central and western Melbourne. Fluoride is added to Melbourne's drinking water in line with Victoria's Health (Fluoridation) Act 1973 and the Code of Practice for fluoridation of drinking water supplies (OHS, 2009) t hat supports the implementation of the Act. Fluoride levels in water supplied to customers throughout City West Water's 580 km 2 licence area have been comprehensively monitored over the years. Data are published in City West Water's Annual Drinking Wat er Quality Reports which can be viewed on website citywestwater.com.au. The average f luoride concentration t hroughout the licence area during 2008/2009 was 0.91 mg/ l (CWW, 2009) . Fluoride occurs nat urally in seawater, fresh water , soil and air, with concentrations in soil ranging up to 300 parts per million (ADWG, 2004). A limited City West Water grab sample program in 2006 (20 samples) revealed sewage f luoride concentrations between 0.5 and 2.7 mg/l (average 1.2 mg/l).

On occasion water authorities are asked to investigate situations where there is an accumulation of water under bui ldings, in basements or in yards. Sometimes this can compromise st ructural integrity. The water authority can be asked to det ermine if the wat er is orig inating/leaking from its (or customers') assets (e.g. from water or sewerage pipes) or if it is from naturally occurring groundwater. Besides active leak detection, water quality testing may be requested to help identify the source (e.g. is it mains water, sewage or groundwater?). Unfortunately water quality testi ng is often of little value , especially if, as in most cases, the accumulated wat er has passed through soil. For example: • chlorine residuals are almost certain to be of no use unless the wat er is pristine and fresh; • low to moderate Escherichia coli counts may incorrectly discount a sewage source if t he water has percolated long distances t hrough soil ; and • presence of nutrients, organic matter and salts may incorrectly discount a potable source, again as a result of percolation through soi l. As a resu lt, suspect seepages have tended to be tested for fluoride with the assumption that, if this conservative parameter is present, or better sti II, if at approximately the same concentrat ion as the local fluoridated mains supply, then a leaking water (or perhaps sewer) pi pe source is virtually certai n. However, years of personal experience of such testing has revealed the presence of fluoride mostly at concentrations lower (and rarely, higher) than in the local mains supply. As a result, many fluoride read ings in the order of 0.2 to 0.5 mg/ l have done little to assist with seepage investigations.

Percolation through soils can have unexpected effects.

With t hese observations in mind, City West Water commissioned a pilot laboratory study to look at the possible influence of soils on the fluoride content of water.

Testing Protocol Soil samples. Two different soi l samples were used. These are described as:

• "Old Soil" - from a mound of spoi l (waste soil) that had been deposited over several years at City West Water's office site. Its origin was excess soil from pipe maintenance works in nature strips. It is likely t hat, as part of the nature strip environment , it had been subject to watering with (fluoridated) mains water. It was described as "sandy with little organic material and drains very well". • "New Soil" - from City West Water 's top soil stock (obtained from a commercial garden supplier) used for restoring works sites in nature strips. It was described as "darker {than the "old soi l") and looks like top soil and contains a very fine silt". W ater samples. Two water samples were used:

• Deionised water {f luoride (F·) <0.1 mg/l ; electrical conductivity (EC) <1 us/cm; pH 4.5) • Mains tap water {fluoride 0.9 mg/l , electrical conductivity 51 us/cm; pH 7.9) Trials. Two trials were undertaken:

• Trial A - passing water samples through a packed column of soil (height 12 cm; diameter 8 cm in a high density polyethylene tube) . Columns were initially wetted with the relevant water (100 ml) and allowed to drain until the column stopped dripping. This was done to ensure that any further (test) volumes added would deliver t he entire added volume back after passing t hrough the column. During daily elutions, 200 ml of new/ fresh water sample was dripped onto the soil colum n (and col lected) over approximately 6 hours. Daily collected samples were centrifuged to remove suspended material, and the supernatant tested for F·, EC and pH.

wat er JUNE 2010

105

technical note Table 1. Trial A, Old Soil/Deionised water.

Table 2. Trial A, Old Soil/Tap water.

Day

F· (mg/L)

EC (us/cm)

Day

<0.1 4.2 4.4 3.9 3.0

<1 51 6 310 226

4.5 7.9

0 2 3 4 5

2.3 2.0

204 173

7. 9 7.9 8.1 7.8

166

7.8

F· (mg/L)

0.9 3.5

1 2

5 6

7.9 8.2 8.1 8.0 8.0 7.9 7.8

567 292 206 194 183 166

4.4 4.1 3.1 2.3 1.9

3 4

EC (us/cm)

Table 3. Trial A, New Soil/Deionised water.

Table 4. Trial A, New Soil/Tap water.

Day

F· (mg/L)

0 1 2 3 4 5

EC (us/cm)

Day

<0.1 <0.1 <0. 1

<1 215 87

4.5 5.0

0 1 2

<0.1 <0.1

30 21 16

<0.1 <0.1

5.9 5.1 5.1

EC (us/cm)

0.9

51 164

7.9 4.9 5.0 5.0 5.1 5.4 5.5

<0.1 <0.1 <0.1 <0.1 <0.1 <0.1

3 4 5 6

5.6 5.5

F· (mg/L)

• Trial B - mixing water samples with so il (to form a slurry) . Two slurry rati os (soil:water) were used: 25: 75, 50:50 (v/v). Slurry samples were kept shaken and daily samples were removed (without replenishing with fresh water) for supernatant analysis (as in Trial A).

88 64 57 51 45

Eluant pH was largely unchanged over the 6 day t rial. Note t hat initial EC and pH differences of the deionised and t ap waters had very little o r no differential impact on their levels in th e eluates. This was not surprising in t he context of the trial. For example, initial EC leve ls were consistent w ith highly pure water (even at 50us/cm) and therefore easily overridden by salt

Results Trial A From Tables 1 and 2, it can be seen that both deionised and t ap water percolating through "Old Soil" did el ute and take-up fluoride (see also Figure 1) and dissolved salts (measured as EC) from the soil.

contributions from t he soils. In relation to pH, negligible differences are consistent with the low buffering capacity of Melbourne's tap water.

5 :J' 4 C)

.........1

§. 3 -

_-.·

'§

::,

u: 0 -

--+-- Deionised water

- - - -- - , - - - - - - - - - - , c - - - - - - - - - l 2

- • - Tap Water

Days

Figure 1. Fluoride in water percolated through "Old Soil".

Ii ·. ·

J C)

.§.. 06 QI

~0 .:

·,

·-

--+-- Deionised water

u. 0.:

-- ----·.

>-,

- ...... - Tap water -

Days

Figure 2. Fluoride in water percolated through "New Soil". 106 JUNE 201o

w ater

For both waters the average fluoride uptake over each of the six days was approximately 3 mg/L. Thus, in each case the 1200 m l of percolated water removed approxi mately 3.6 mg of fluoride from t he 600 m l column of soil. Assum ing a soi l density of say, 1.5 g dry solid/m l , this corresponds to the removal of about 4 mg F·/kg dry soi l. From Tables 3 and 4 it can be seen that the "New Soil" had the opposite effect to the "Old Soil" in that it removed fluoride fro m the tap water (Figure 2). Apart from the apparent absence of f luoride in the "New Soil" being consist ent with its lower (el utable) salt content, EC and pH showed similar patterns as with t he "Old Soil". Wit h respect to t he t ap water, the average fluoride uptake by the "New Soil" over each of the six days was 0.9 mg/L. Thus, t he 1200 ml of percolated tap water contri buted 1.08 mg of f luoride to the 600 m l column of soil. Assum in g a soi l density of say, 1.5 g dry solid/ml , th is corres ponds to t he adsorption of about 1.2 mg F·/kg dry soil.

Trial B From Table 5 and 6 it can be seen that , when combined as a slurry, both deionised and tap waters take up fluoride from t he "Old Soil". Also, t he fluoride concentrat ion in the aqueous phase was constant over the 6 days of the sampl ing program. This indicat es that t he two phases (i.e. t he soil and the aqueous) had reached equi libri um within 1 day. In t he case of deionised water (Tabl e 5), t he equ ilibrium level was lower in the 25:75 slurry (around 1.4 mg/ l ) as compared w ith 50:50 slurry (around 2 mg/l ). This is consistent w ith trial A where t he daily eluate fluoride gain over the first three days around 3 mg/l under circumstances where the dai ly "Old Soil": water ratios were 75:25. Unlike t he deion ised water slurries, both tap water both slurries showed very si milar eq uilibrium levels. This apparent difference between deionised and tap water may require further investigation. In contrast and also similarly to Trial A, the " New Soil" removed fluoride from the (tap) water (Tables 7 and 8). In summary, t he two soil ty pes examined ("Old", "New") exhibited opposite patterns in terms of t heir fluoride content and capacity to either add fluoride to, or remove it fro m water. The "Old Soil" being a fluoride donor whilst the "New Soil" a fluoride

technical features

technical note Table 5. Trial B, Old Soil/Deionised water.

Table 6. Trial B, Old Soil/Tap water.

Day

0 2 3 4 5 6

F· (mg/L) 25:75

F· (mg/L) 50:50

<0.1 1.6 1.3

<0.1 2.2 1.9 2.2

1.4 1.3 1.3 1.3

2.5 2.2 2.1

F· (mg/L) 25:75

F· (mg/L) 50:50

0.9 1.6

0.9 1.9

2 3 4

1.5 1.6 1.6 1.6 1.7

1.5 1.7 1.6

5 6

1.6 1.7

Table 7. Trial B, New Soil/Deionised water.

Table 8. Trial B, New Soil/Tap water.

Day

0 1 2 3 4 5 6

F· (mg/L) 25:75

F· (mg/L) 50:50

<0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

"grabber". This occurred irrespective of whether water was percolated through the soils or present as a slurry.

Concluding Comments It must be noted t hat Part A of this pilot study, which observed percolation (i.e. flow-through conditions), did not consider t he development of steady stat e conditions. In other words, where a lengthy period of seepage elutes all available soi l fluoride content or conversely, saturates the soil's fluoride capacity. Clearly it is untenable to assume that soils have an infinite capacity to either absorb or release fluoride and thus not attain steady state. Attainment of steady state could possibly cause soils to show a change to, or even reversal of, their original behaviour with respect to f luoride water-soi l interactions. Notwithst anding t he non-steady state situation considered in this pi lot study, it is clear that soil can have a dramatic effect on fluoride (and salt) levels in water passing through or in contact wit h the soil. Depending on the soil type and extent of steady state, the effect ranges between addition or removal of fluoride (and salts) from t he water. This has important implications when water f luoride analyses are undertaken as part of investigations trying to determine the source of water seepages or accumulations. It also offers an explanation for the often perplexing wat er f luoride levels found during such investigations. Althoug h fluoride in water is a conservat ive parameter (i.e. levels tend to remai n unchanged), t his is certainly not the case where t here is contact with soil.

F· (mg/L) 25:75

3 4

0.9 <0.1 <0.1 <0.1 <0.1

5 6

<0.1 <0.1

PENSTDCKS & STDPBDARDS

F· (mg/L) 50:50

0.9 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Consideration of this work has potential beneficial ap plication to water seepage situations where all superficial observations (i ncluding fluoride water tests, sound detect ion) are inconclusive in identifying the seepage source. If possible/accessible, obtaining and analysing a soil sample (as in Trial A) from a nearby site not subject to seepage, may assist in interpret ing the seepage water fluoride level and t herefore, providing a better indication of the source prior to invasive excavation works. However, should steady state conditions have been reached at t he seepage site, a comparison with nearby soil would have little or no comparat ive val ue.

Acknowledgment This study was funded by City West Water Ltd. Analytical work was undertaken by EM L Consulting Services, Victoria.

- Modular Structures - Best Practice Designs - Complete System Control - Custom Designed - Reduced OH&S Risks - High Strength, Low Maintenance Design - Manual or Automated - Operational Flexibility

The Author Georges Ruta is Manager Water Quality with City West Water Ltd in Melbourne. Email: gruta@citywestwater.com.au.

References ADWG (2004). Australian Drinking Water Guidelines. National Health and Medical Research Council/ National Resource Management Ministerial Council. www.nhmrc.gov.au. DHS (2009) Code of Practice for fluoridation of drinking water supplies. Department of Human Services, Victoria. Health (Fluoridation) Act 1973. Act No. 8506/ 1973 Victoria. CWW (2009). Drinking Water Quality Annual Report 2009. City West Water Limited, Melbourne Australia. www.citywestwater.com.au.

water JUNE 2010 101

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

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