Water Journal November 2002 by australianwater

New Release from Haestad Press

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Volume 29 No 7 November 2002 Journal of the Australian Wat er Association

Editorial Board F R B isho p, C hairman B N Anderson, R Considine, W J Dulfer , G Finke, G Finlayson, G A H older, B Labza, M Muntisov. P Nadebaum, J D Parker, J Rissman, F R oddick, G Ryan, S Gray

CONTENTS

', Water is a refereed journal. T h is sylllbol indicates that a paper has been refereed.

Submissions Instructions for authors can be found at the back of chis journal. Submissions accepted at: www.awa.asn.au / publications/

Managing Editor

OPINION 2

No Silver Bullets; Aquaphemera; People Power; e·Submission Pilot; How Much Water Is Enough? Barry Sanders; Not My Point of View, Steve Barnett

ASSOCIATION ACTIVITIES

P eter Stirling

News and Supervising Editor

PROFESSIONAL DEVELOPMENT

B rian McR ae A WA Tec hnical Director Tel: (02) 9-l I 3 1288 Fax: (02) 94 I 3 I 047 Email: bmcrac@awa.asn.au

Technical Editor EA (Bob ) Swinto n -l Pleasant View Cres, Wheelers Hill Vic 3150 Tel/ Fax (03) 9560 -1752 Email: bswinton@ bigpond.net.au

Including AIWA and WEF Reports Details of courses, classes and other upcoming water events

NEWS BYTES 14

Featuring selected highlights from the AWA email News

CROSSCURRENT 18

Water Production

Recycling Sewage Sludge the American Way; Metals in Drinking Water from New Housing Estates in the Sydney Area; Australian Exporters • A Vital Minority in a World of Opportunity

Hallmark Editio n s PO 13ox 8-l, Halllpton, Vic 3188 Level I, 99 Bay Street, Brighton, Vic 3186 Tel (03) 9530 8900 Fax (03) 9530 891 I Email: halllllark@ h alledit.com.au Graphic d esig n: Mitzi Man n

CONFERENCE REPORTS

Water Advertising

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Natio nal Sales M a nager: Bria n Rault Tel (03) 9530 8900 Fax (03) 9530 891 1 Mobile 0411 354 050 E mail: brault@halledit.com.au

Water (ISSN 0310 - 0367) is published eight times a year in the months of February, March, May, June, August , September, Novem ber and December.

33 37

Federal President Barry Norman

Executive Director

AUSTRALIAN WATER ASSOCIATION

Chris Davis

Australian Water Association (A WA) assumes no responsibility for opinions or statements of fa cts expressed by contributors or advertisers. Editorials do not necessarily represen t official AWA policy. Advertisements are included as an information service to readers and are reviewed before publication to ensure relevance to th e water environment and objectives of AWA. All material in Wnrer is copyright and should not be reproduced wholly or in part without the written permission of the Managing Editor.

Subscriptions Warer is sent to aU AW A members eight times a year. It is also available via subscription.

Visit the Australian Water f HOME PAGE Association and access news, calendars, bookshop and over 100 pages of Information at lit

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•, CATCHMENT MANAGEMENT • THE FIRST BARRIER The pragmatic and political approach used by Ballarat, Victoria.

R Ford

•, BEATING THE BLUES - RESEARCH INTO BLUE WATER IN COPPER PLUMBING Copper corrosion is no simple matter. R O'Ha llora n, R Taylor, F Smi th, N Goodman, M Critchley

Australian Water Association PO Box 388, Artarmon, NSW 1570 T el +6 1 2 9413 1288 Fax: (02) 9413 1047 Email: info@awa .asn .au A "\V/'A ABN 78 096 035 773 1-li. W •

The Thiess River Prizes. Australian: the Merri Creek Management Committee, A Foley International: the Mekong River Commission, J Kristensen The River Symposium, Rosenberg Forum, Water Sensitive Urban Design

TECHNICAL NOTE: CORROSION CONTROL IN COOLING SYSTEMS ONDEO·Nalco solve a problem. s Powe ll

SPECIAL FEATURE ODOUR CONTROL 44

" ODOUR CONTROL AT A WASTEWATER TREATMENT PLANT IN TASMANIA Attention to detail pays off. R van Oorschot, C Fre nch, R M illhouse, J Hingston

TEMPORAL AND SPATIAL VARIABILITY IN ODOUR EMISSIONS A daily sample for odour assessment is virtually useless. M Go ldstone, C Gwyn ne, N Turner

WASTEWATER 51

"'- THE BIOWIN MODEL: RECALIBRATION FOR N-REMOVAL: PART 2 The revised parameters are calibrated on a full-sized plant. D W de Haas a nd MC Wentzel

BIOSOLIDS MANAGEMENT IN ENGLAND AND FRANCE Auseful report on a wide range of facilities. D Stevens, J Kelly, C Liston, D Oemcke

BUSINESS 62 ~ ROBUST SEPARATION OF INTERESTS Adiscussion paper on where shall we go with water rights. M

D Young, J C McColl

OUR COVER: Good catchment 111a11age111e11t is the first line of defe11ce in protecti11g water quality. See article on. page 33. Photo by co11rtesy of Melbourne Water, WATER NOVEMBER 2002

FROM

THE

PRESIDENT

NO SILVER BULLETS Suddenly, perhaps thanks to the current drought, water has become headline sexy, attracting the attention of some high profile businessmen and celebrities. Some, like Richard Pratt, have been taking an interest for some time, whereas others seem newly enthused. The esta bli shment of th e Farmhand Foundation, chaired by Bob Mansfield and underwritten by a group o f prominent businessmen, is an interesting development, geared to providing some em ergency relief for the bush, as well as fundin g research. Of course, there may also be other agendas. Some of the public pronouncements that have been made suggest a simplistic view of our water situation - we need to drought-proof Australia. I fear it's not possible to ' drought-proof Australia as such and that the collateral damage resultin g fr om a misguided attempt would be substantial. Some of the intuitively attractive so lutions that are put forward are: • More dams - we have at least 433 large dams in Australia already, plus more than

Barry Norman

a million smaller ones. T heir impact on rivers and on ru noff patterns is largely responsible for the sorry state of our major rivers today. At the very least, future dams should be built o ff-stream, to obviate some of the major impacts on stream

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WATER NOVEMBER 2002

flow, water temperatures and ecology. In any case, good dam sites have largely been exploited, so the remaining ones are eith er vety remote or not ve1y attractive . Approach with extreme caution. • T ransfer water from the wet north to th e dry south , or generally, from coastal to inland rivers - proponents hold up the work of C Y O'Connor. Again, the impact of major interbasin transfers can be vety negative. O'Connor's legacy is a vibrant m ining town at Kalgoorlie, but the cost per m egalitre is substantial and no farming enterprise could earn enough to support that infrastructure and energy bill. It is intuitively appealing and technically feasible to move water vast distances, but it 's not a sustainable solution, except for very high value uses. • Compensate the farme rs - a sympathetic response, but why are fa rmers somehow different from other enterprises that suffer bad times? In fact, intelligent, informed farmers make a good fist of conducting their operations in varied rainfall conditions. Any support should be aimed at educating and equipping more fa rms to plan and design their operations to be intrinsically durable, rather than propping up those w ho have been unable to cope and who will be in trouble the next time the rains don 't come. • Find the m agic answer - there is none , since coping with Australia's famously fickle climate requires a basket of skills, including long-range weather forecasting, more efficient water use, farm planning, better water allocation methods, and so on. The silver bullet doesn't exist, so the sooner all the stakeholders attend to the whole basket of issues su rrounding farming and water, the sooner individual enterprises will become more robust in the face of drought. Australia does need to give careful consideration to dealing with water, and these are some of the directions that will add value for us all: 1. Sore out property rights in water so farmers and financiers have confidence in the value of water rights and so that people can trade effectively to make the best use of water 2. Provide som e form of structural adjustment to ease the transition for those irrigators whose fo rebears were established on small farms by previous governments w hen the vagaries of irrigated agriculture weren't well understood.

Continued over page

WATER

CATCHMENT MANAGEMENT THE FIRST BARRIER

R Ford Summary This p aper was pre pared as notes fo r a CRC for W ater Quality and Treatme nt workshop on th e revised Austra lian Drinking W ater Guid elin es . It dea ls with managing the first barrie r for protecting wa ter quality - the catchment. It is based o n the pragmatic actions taken by the BaUarat water supply organisatio n, Central Highlands W ater, over the past 15 yea rs to protect th e quality o f wate r harvested fro m th e ca tchme nts. Th ese are located in rural zo nes, but are subject to pressures to de ve lop ho bby farms and ruralres ide n ces since Ballarat is a m e re o ne-ho ur drive from the capi tal city, M elbourne.

Why bother? The Au strali a n Drinkin g W a te r Guide lin es advoca te a multi- barri er approac h to the managem en t of drinking water quality . Th e fi rst barrier in vo lves man aging th e initial raw water source. This will in volve: • th e ca tc hm ent area, fo r a su rfac e suppl y; • the aquifer intake area, fo r an unde rgro und so urce o r spring supply; o r • the area immedi ately above th e in take, w he re water is abstracted from a major ri ver. Th e communities we se rve ha ve demonstrated that any risk to th e safe ty of th eir water supply is unacceptable. T his has been made very clear by th e increasing perception that bottl ed water is safer or healthier than tap wa ter, by th e volum e of water quality regulati on being appli ed overseas and th e reaction to the 1998 Sydney incident with the State Pre m.i er appearing on natio nal television promising the Sydney consume rs that " heads will roll", w hich they did. T he message is clear. Any barrier ca n and probab ly w ill fail at som e time durin g its ope rating life. Providing multiple barri ers, m.inimizing pollution of the raw water and monitoring th e perfo rmance of the protective systems redu ces the chan ce of a quality failure. M inimizing poll ution of the raw water also reduces th e co mplexity and lifetime cost of water trea tment processes and in the event of a system failure, the resultant consequences and rem edial ac tio n.

C atc hm e nt manage me nt consists of a numbe r of activities. C entral Highlands Wate r (CHW) and its predecessors have been active in m anaging the in habited surface catch ments that supply Ba!Jarat fo r about 140 years. W e are sti ll learnin g. Th e basic principl es th at have bee n su ccessful are: • know your catc hment; • understand and influence the poli cies o f the othe r government agen cies; • unde rstand th e local land- use plannin g process and influe nce planning strategy and decisions; • ide ntify and wo rk w ith the loca l landowners; • ide ntify and suppo rt alli es; • rec ognise threats and act to head the m o ff; • man age the politics; • maintain close liaison with th e local m edia. C HW operates 17 surface reservoirs and 4 bore fi elds supplying towns in the Ballarat regi on of central Victoria. The largest ca tchment supplies th e Ballarat system and is also a maj or bulk source fo r Barwon Wate r's supply system into the city of Geelong. The Ballarat catch ments are located abo ut 20km east of th e city and are tra versed by th e Western Freeway to M elbourne, 70km to the east, and a major commuter rail line. T he area is rural with

mi xed farmin g o n good volcanic soils. To man age these catchm ents th ere is a tea m o f: • one seni or catc hm ent manage r w ho, as part o f his duties, has respo nsibility for policy development, liaison with councils, g ov e rnm e nt a gen c ies, ca t c hm e n t m a na ge m e nt a uthoriti es a nd lo ca l go vernme nt pl ann ers; • two technica l o ffi cers (who also have respon sibility fo r man agin g all th e Authority's land) The re are also o th er staff in th e H ead w orks Division who ca n be ca ll ed on fo r ass istance, advice and backup su ppo rt: These comprise: • th ree engineers (wh ose role is primari ly h y drol ogy, dam. sa fe t y, r ese r vo n m anagem ent with minimal catchme nt m anageme nt responsibility); • fou r fi eld staff (whose primary role is o n site m ainte nan ce, surveillan ce and operations of rese rvoirs and channels) .

Know your catchment T o unde rstand the catch ments C HW: • arranges fo r low altitude air p hotos flown abo u t e very 7 years im media tely after heavy rain in late spring w hen the gro und is saturated. This highli gh ts swamps, drains and minor watercou rses. These photos have been digitised, rectified and coordinated and are stored in a GIS . The photos can be overlai n with contours, cadastre, road nam es an d m uni cipal

WATER NOVEMBER 2002

WATER

property r efe ren ce numb e rs. T his additional information is available from the state mapping authority in digital form; • formall y in spects th e ca tc h m e nts annually to identify and check on the high-risk areas. Potential pollution sources such as dairies, a timber preserving plant, storm drain outle ts fro m urban areas are identifi ed and listed for regular inspection. Th e Western Freeway has a large storm drain which parallels the freeway picking up runoff from inl et pits in the ce ntre median. The o utfall locations of this drain are also recorded and inspec ted; • keeps records of house construction activity and total numb er of allotments. T his in fo nnation has been valuable in planning-appeal hea rings to demonstrate the rate of in cremental development in the catc hment over the past 25 years. T he Authority is also a "Referral Authority" under the municipal planning schem e which requires that details of all development applications with in its catch ments or aquifer intake areas be referred for consent; • instalied £low gauging stations on all major sub-catchments to improve the un derstandi n g of t h e catc hm ent hyd ro logy . Th ese h ave sin ce b ee n equipped with data loggers. Their maintenan ce, downloadin g and processin g is co ntracted out to the organisation responsible for the state gauging network. This provides assurance that th e quality of data recorded is consistent with that obtained across the state . D ata fro m these gauges identifies the areas contributing the most run-off and hence the areas that shou ld be targeted to manage diffuse pollution . Data loggers are also plann ed for installation on a nu mber of observation bores at bore fie lds where groundwater is abstracted for urban use . A number of weath er stations, recording da ily rainfall and evaporation , are also operated. These are gradua lly bein g automated and radiotelemetry installed.

Understand and influence the policy of other agencies Nobody will look after your interests like you will. While there are other gove rnm e nt age n c i es a nd l oca l government with health and en vironmental responsibilities C HW views its our core busin ess as protection of public health. The Authority therefore takes every opportunity to be represented on any comn1.ittee or steering group that has an intluence on catchment p olicy or water quality. Staff are encouraged to attend meetings of all stakeholders ranging from state governmen t and local government 34

WATER NOVEMBER 2002

do w n to landcare and water-watch groups. This helps to ga th er information on em erging issues and the direction of these organisations and provide an opportunity fo r in put w hile they are still fo rm ulati ng their strategies. In Vi ct oria th e key do cum ent s im pac tin g on catchm ents are: • T he Pla1111i11g and E1111iro11111e11t A ct • Catch111e11t a11d Laud Protectio11 Act • f1Vater Act • State Planning Policy • Loca l planning Po licy and adopted strategies • State En vironm ental Protection Policy (Waters of Vi ctoria) • Vari ous Industry Codes of Practice • Mini ster ial Dire ctio n s & Guidelines(issued under various Acts) • R egional Catchment M an agement Stra t eg ies (prepared b y r eg ional Catchment Management Authorities) • Code ofPractice fo r on site waste-water disposal (The septic tank code) • Local wastewater man agement plans • Local stormwa ter m anagement plans Most of these documents sp ecifically refer to the need for extra care or increased restrictions for the protection of domestic water supply ca tchm ents. Many of these requirem ents were included because of the initiative of CHW representatives . Being actively involved in the preparation and review of these documents has paid off significantly as the consistency of the policy documents and managem ent plans has prevented a number of development proposals proceeding w hich would have been difficult to control otherwise. It has also built up contacts with the other agencies and encouraged

the m co contac t water suppl y auth o rities for comment w hen considerin g and changes to policy or legislation. Duty officers, responsible for managing incomin g calls that relate to se rvice difficulties have all attended a basic course in emergen cy m anage m ent run by th e regional state emergency services. As well as updating their em ergency management skills, th is has also bu ilt up useful contacts with poli ce, fi re, municipal and council em ergen cy staff and reinforced with them the location and im portance to public hea lth of the loca l ca tchments, storage dams and aquifer inta ke areas.

Understanding and influencing local planning decisions Th is is probably the most important aspect of catchment managem ent. Local planning laws will determine w hat type of developmen t and activit ies are permitted to occur in the catchment. If inappropriate development is permjtted this can negate all the effort and resources put into on-ground works. State Planni ng Policy and Local Planning Policy drive Local Planning Laws. T hese policy documents include statem ents abo ut the importance of the quantity and quality of water harvested for protection of public health and the need co protect and enhance water quality and protect the quantity available . In Victoria local councils do not manage the water supply system. Local councils however are responsible for planning, including approval of development within catchments (except the M elbou rne catc hments w hich are a sp ecial unique case) . In the past these decisions were being made withou t reference to, or often in disregard of, water

WATER

authority advice. Where local government is not responsible for t he water supply it often has a different objective to the water authority. In so m e cases its prim ary aim was si mply the development of the municipality in o rder to increase their rate base. D rinking wate r quality was seen as so m eth ing that can easily be fixed by the water authority bui lding a bigger, bette r an d m o re sophisticated treatment plant. A strategy that C H W found was success fu l in reversin g th is mind -set invo lved a two-phase approach . Firstly, forma lly objecting to development proposals that were inappropriate and requ iring special conditions to protect water qua li ty to those permitted (such as significa nt se tbacks from stream s) . To achi eve this it was initially necessary to inspect council's plann ing perm it register regularly and be prepared to ca rry an objection to the state app eal tribun al. To support the objectio ns data co llected o n numbers of existing undevelo ped lo ts and rate of hou si ng development was in valu able. l n most hearings the tribu nal uph eld C H W's o bjection and directed the develo pment not proceed or be am ended.

Th e seco nd approac h i nvo lved lobbying the local State Parliamentary M e mbers and the Minister responsible for planni ng to alte r the local planni ng legislati o n to m ake all water authorities " R eferral Auth orities" under the Plan ning Act. This was eve ntually achi eved in 1992 and resu lted in all development appl ications i n "Spec ial Wate r S u p pl y Catchments" being forma lly referred to water authorities. C H W has made sure all of its catchments are gazetted as "S pecial W ater Supply Catchme nts" . " R efe rral" powers permit the authority to veto an y plann ing permit appli cation o r imp ose cond itio ns. T he normal abil ity to appea l to a pl ann ing tribun al remains, w hich requires that th e Au thority must act reasonab ly and be prepared to justi fy an y refusal. Loe.i i planning zones and planning ove rl ays in Victoria includ e spec ifi c objectives. For pl a nning zo n es and ove rl ays that include a d o m es t i c catchment, these objectives should include statem ents regarding t he mainte nance of the qu antity of wate r ava ilable and improvement of t he qu ality of wa ter in the local rivers and stream s.

Th e recent plan ni ng schemes also include detai led ite ms that plann e rs sh all " have rega rd to " when cons id eri ng planning consent appl ications. Th ese include specific requirements for distances to streams, density of housing, prohibition o f in tensive animal industri es and discourage m e nt of inappropri ate deve lopme nt. Such directions provide useful justification for planners to refuse in appropriate developm en t in domestic catchm ents or to support th e im position of appropriate cond itions. All on-site wastewater disposal syste ms install ed withi n C H W 's catc hments si nce 1991. are subj ect to a plannin g agreem e nt that th ey w ill be inspe cted annu ally by a q ualified Environmental H ealth Officer at the landowne r's cost. T he owner is also required to register the existence of this agreem e nt on th e property title prior to any construction work commencing. As w e ll as providing regular inspections of wastewater disposal systems th is provides an e ffec ti ve m ec h a ni sm to advise prospective pu rc hasers that th e pro perty they are co nsidering is w ithin a domestic water sup pl y catc h m e nt and as a

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WATER landowner they wi ll have spec ific obligations to protect water quality. lt is important to understand how the pla nning system works and to be able to use it to protect the quantity an d quali ty of water harvested.

Working with local landowners Genu ine farmers have an affinity with the land and are interested in preserving the soils. H obby fa rmers, in general, work in towns and see their property only as a week-end retreat with the fam ily. Stock is held fo r pleasure with limited regard for the capacity of th e land to support it, as additi onal food can easily be purchased from the local produce store. C HW sees it to be in its interest, therefore, to encourage broad acre agriculture rather than small rural- residential subdivisions . La ndca re and school Water Watch groups are encouraged. Seed fu nds have been provided to help establish groups and oth er assistance such as air photos, maps and advice is freely given. C HW staff also try to atten d as many loca l group meetings as possible as these are a good so urce of information o n activity occurring within the catchment. To assist the protection of streams , the cost of fe ncing material and tree stock is reimbursed to landowners who fence off streams and othe r sensitive areas . Expressions of interest for financing such works are caUed twice a year. To date abou t 40km of streams have been fe nced and buffer zones p lanted and off-stream stock water points constru cted. Assistance is also provided to groups seeking funding for sim ilar works from state govern ment. T his assistance ranges from h elp to complete the appl ication form through to the water auth ority being a fu ll partn er in th e project and contributing reso urces. To e n co urag e i mprov ed management of fertilizers and reduce the am.ount of topsoil enteri ng streams a demonstration farm managed by the loca l fa nners has been established on C H W land T he local fa rm comm.unity decide w hat will be trialed and a gauging and sampli ng station is located downstrea m of the site to demonstrate the effect of the various management p ractices. This ha s significa ntl y improved the relationships between the wate r authority and the fa rming community, especially when they see the authority is prepared to finance projects that benefit them. 36

WATER NOVEMBER 2002

Identify and support allies Management of open catchments involves a range of activities, some of wh ich w ill be less detrimental to water quality than others. Identification and assistance from agencies and landowners that support beneficial activities can be effective in preventing inappropriate development. In particular state and local policies aimed at the pro tection of agricu ltural land have been successfully used to prevent su bdivision and hobby farm development. On a number of occasions the pla nning tribunal has pointed out that agricu ltural land in close proximity to urban areas should be protected for its own value notwithstand ing the fact that it li es w ithin a water supply catchment or that the cmrent owner has been unable to obtain an economic retu rn. Field natura list and conservation groups can be very supportive where a water authority demonstrates strong conservation valu es. School "Water Watch" groups can also be valuable in assisting the monitoring of streams for pollution . C HW provides simpl e measuring kits for school groups and assist w ith technical support and identification of worthwhile projects.

Recognise threats and head them off Mainta ini ng good contacts with cou ncil planning officers, politicians and lan dow n ers is o ften effect ive in providing initial advice of proposed developmen t activities or encouraging proponents to ni.ake contact with the water authority at an ea rly stage before expectatio ns are raised. A difficult problem is the increased pressure for rural/residential type development in water catchment areas. T he impact of each individual house is minor and therefore difficult to argue against. H owever the cumul ative im.pact of development over time due to increased human activity in the catchm.ent, additional septic systems, increased storm run off, additional traffi c and c onstructio n activity all add up eventuaJly to a serious impact on water quality. Data on house construction rates and water quality changes has been useful in convincing planning bodies of the long term threat to water quality of incremental development. C H W has created an expectation that landowners and developers are unlikely to obtain permission for rural/residential subdivision, additional houses or and industrial developmen t in the Ballarat catchments. This has enco uraged co uncil planners to direct inquires into

other areas o f the ir mu nicipal district. Counc illors are now gene rall y supportive of the authority's actions in attempting to keep the loca l water supply as " pure" as possible.

Manage the politics Politicians don't like surprises. Keep them well-briefed on activities in the catchment and warn them of impending issues. In particular make sure that decisions or actions likely to be controversial are well documented, consistent and in line with policy. Where possible have clea r policy docu m ents that have been adopted by the Board of the authority with all the implications explain ed to Board members, the local politicians an d councillors.

Maintain close contacts with the media Newspapers and TV stations are always looking for a sto1y. Celebrate the completion of water qual ity projects, such as completion of a Landcare project or construction of a wetland and invite the m edi a. T hes e ac ti viti es support local groups by showing public appreciation for their efforts as we ll as b uilding bridges with the media. A number of possible in cidents have been success fu lly managed due to good relatio ns with local reporters wh o sought comment from the authority well b efore their deadlines.

Conclusion Managing domestic water supply catchm en ts is not easy and every situation w ill be differe nt. What has worked for C H W may not be suitable in a different area or u nder different circumstances. The most important factor is to appoi nt som ebody from within the organisation to champion the catchment an d establish good contacts with the other stakeholders. Changing perceptions takes a long tim e but it is critical that decisions be consistent and fai r and have regard to the long-term obj ective of protection of public health.

The Author Bob Ford was the Engineer-in-Chief for the fo rmer Ballarat Water Board and is currently a senior manager in Central Highlands Water. He has been involved in the water industry for the past 26 years, and has been a strong advocate for catc h men t protectio n. Email rford@c hw .net .au.

WATER

BEATING THE BLUES RESEARCH INTO BLUE WATER IN COPPER PLUMBING R O'Halloran, R Taylor, F Smith, N Goodman, M Critchley Abstract Blue water is a consequence of the corrosio n o f copper plum bing tubes w h e re inso lu b le p arti cu la tes a re released into drinking w ate r. This results in a charac teristic blue- gree n d isco lo uration in w ater su ppli es, wh ich prese nts bo th aesthetic and pu bli c h ealth conce rns. CS IR O M anu fac turi n g & Infras tru cture T ec hno logy has been und ertaking research into various aspects of copper corrosion. T h is paper hi g hligh ts significant areas of CS IRO research into blue w ater.

res u lts fr o m ge n e ra l co rrosi on resulting in the dissolutio n of solu ble copp er ions into water.

Introduction The corrosion of copper plum bing tubes used in drinking wa ter distri butio n is primarily responsibl e fo r the Plate 1 . Blue and clear water - a comparison. prese n ce o f co pp e r in do m es ti c supplies. T hree distinct types of copper corrosion have been identi fied , each th e gene ral co rrosion of copper w ith th e movement of pli mmily insoluble corrosio n type distinguishable by its moLp hology and products fro m pipe surfaces into water. th e associ a te d w a te r e n v ironm e n t Th is c a u ses a b lu e - g r ee n cl o u d y (Edwards el al. 1994). Pittin g corrosion is co lou ratio n and hence is known as blue localised, characterised by deep na1Tow pits w ater (P late 1). C u prosolven cy also in tube surfaces. Blue water resu lts fro m

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Cuprosolvency o ccurs main ly in areas receiving hard wate r with h igh buffe ri n g ca p ac iti es in c ludin g Ade laide drinki ng water supplies. Blue wate r conditions are m o re likely to occur in so ft w aters fo und i n the Eastern sta tes o f Au stralia. Co pp er is a n essentia l tra ce ele me nt for hu mans, although the consumption o f high con cent ratio ns can have ad ve rse h ea lth conse qu ences. Copper has bee n reported to induce nausea, vomjting, d iarrhoea and stomach cramps with ac ute exposu re thro ugh drinking w ate r (K nobeloch et al. 1998). T he toxicity of copper through the consum ption of water also occurs indepe ndently o f its soluble and insoluble proportio n s (P izarro el al. 200 1). In additio n to its toxici ty, coppe r in drinking water causes aesthetic problems. The m ost obvio u s indi catio ns of contamj natio n are th e cloudy appearance o f blue w ater, and o f

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blue stains on bathroom fittings resulting from th e deposition of soluble copper as a soap scum. Showering in wa ters containing high copper concentrations can also cause a green tint to blonde hair (Fisher 1999) . Copper is often detected by a metallic, bitter taste in water. The Austral ian National H ealth and Medical Research Council guideline fo r copper in drinking water is l mg/L based on aesthetic considerations (NHMRC 1996). The health guideline value for copper in drinking water is 2 mg/L (N HMRC 1996). Blue water generally occu rs as a random phenomenon , with only certa in areas of distribution systems affected. T h.is may be as extreme as one house in a street solely experiencing problems, despite both affected and unaffected areas receiving the same water supply. The corrosion of copper is usually attributabl e to the chemical composition of drinking water (Edwards et al. 1994). The sporadic nature of blue water conditions has provoked intense research into its cause. The assessment of conditions promoting blue water

CS !RO has investigated numerous cases of copper corrosion involving blue water in M elbourne hospitals, private residences, co mmercial buildings and even CS IR O laboratories. In many instances, blue water was found to be associated with water in which the pH had become raised through contact with cement linings on ductile iron water mains. Blue water was also common in supplies containing a negligible amount of free chlorine. Many of the affected tubes contained surface residues that possibly resulted from the lubricants used in tube manufacturing. Such films had been associated with pitting corrosion of copper in localised regions with specific water chemistries for over 40 years (Cornwell et al. 1973), but they had not previously been linked to blu e water. CSIRO research into blue water has involved field monitoring and laboratory investigations of corrosion and its remediation . Fo r the fi el d monitoring investigations, specially designed test facilities containing copper tubes were incorporated into robust enclosures in drinking water supplies either prone to blue water or with no history of copper corrosi on problems. T hese faciliti es analysed th e water conti nuously, providing data on variations in water quality, particularly p H and chlorine. The results of field monitoring showed that blue water tended to occur under conditions oflow free chlorine residual and high 38

WATER NOVEMBER 2002

Plate 2. CSIRO laboratory rigs for investigating blue water cond itions.

pH (Taylor et al. 1998) that often occur at the ends of long distribution systems. In the laboratory investigations, a computer-controlled water mixing plant was constructed and connected to an automated test rig comprising approximately 200 copper tubes of different comm ercially available types (Plate 2) . These copper tubes were exposed to waters in which suspected key parameters in blue water (tube type, pH , chlorine level and water alkalinity) were vari ed. The performance of these tubes was evaluated over an extended period of time by periodically (usually weekly) changing the water in each tube and analysing it for copper. The laboratory investigations demonstrated that dosing with bicarbonate (using lime and carbon dioxide) reduced the occurrence of blue water (Taylor et al. 2001). Bicarbonate dosing increases the alkalinity or buffering capacity of water, increasing its resistance to pH changes . However, bicarbonate dosing caused substantial blue-green deposits on the internal tube surfaces. This indicated that corrosion was still occurring but surface corrosion products were not released into the bulk phase. Blue water was also controlled in the laboratory rig by chlorination or ch.loramination at concentrations of 0.2 mg/ L (Taylor et al. 2001). The presence of free chlorine also decreased the underlying corrosion rate . Regular exposure to chlorinated water was necessary for the control of corrosion to remain effective. T he laboratory investigations indicated that certain copper tubes were more prone to corrosion and the release of corrosion products (Taylor et al. 2001). Further examination revealed higher amounts of

carbo naceous material on the interior surfaces of these tubes, which apparencly resulted from thermal decomposition of drawing lubricants during the annealing process. Wit h long term expos ure , however, hard-drawn tubes which were not su bject to an nea ling also started to produce significant amounts of blue water, possibly due to the gradual removal of a protective layer of residual drawing lubricant. The results also indicated that elevated water pH (up to but less than about pH 10) was a major factor contributing to blue water formation in the absence of residual chlorine or ch loramine. This was not expected as increasing water pH has previo usly been shown t o decrease its corrosiveness (Berghult et al. 2001). In the case of blue water from copper corrosion, this beneficial effect of high pH is observed onl y in the presence of residual chlorine. Microbial influences in blue water The reduction of blue water and su rface corrosion by the addition of chlorin e suggests potential microbial involvement in the initiation of blue water. Although copper is traditionally considered antimi crobial, the survival of microorganisms in its presence is well documented (Lin and O lse n 1995; Critchley et al. 2001). Previous work has strongly implicated the involvement of microorganisms in the corrosion of copper in both hot and cold water systems (Arens et al. 1995). Microorganisms have also been associated with the occurrence of cuprosolvency in Adelaide drinking water supplies (Critchley et al. 2001). T est rigs were constructed to enable long-term corrosion trials under sterile

WATER

wa te r by mi cro sc opy also conditions. The rigs comprised show s a stron g mi c rob ial 25 L polycarbonate containers c ompo s ition (P la t e 3) . and were vented using 0.22 ~m1 R esearch into the mi crob ial filters. Duplicate 1 m len gths of sign ifi cance in blu e wa te r ne w annealed coppe r tubes co ndition s is c u r r e nt l y previously associated w ith blue w a t e r f o rm a tion w e r e co ntinuing in asso c iation with th e D e partr:n e nt of connected to each rig. The rigs Envir o nm e nt a l H e a l th , were fill ed with water, adjusted Flinders Un iversi ty . co pH 9.5 and sterilised by autoclaving. Sterile rigs fill ed Strategies for the with non-steril e w aters were remediation of blue water also used in th e experime nts. A number of re 111edial treatThe rigs re mained stagnant and me nts have been proposed to were aerated wee kly with 0.20 trea t outbreaks of blue wate r ~Lm filt ered air. Water contained in copper plumbing system s w ithin the co ppe r tubes was (W ells 2000). Some treatPlate 3. Epifluorescent micrograph of a co rroding copper collected weekly usin g aseptic me nts, suc h as the use of hot tube after acridine orange staining (100 0X). The ye llow and t ec hnique. Sampl es w e r e water or the app lica tion o f analysed for total copper usin g orange rods are bacteria. food- grade biocides, are based atomic absorption spectrometry o n redu cing microbial ac tivity and assessed for sterility thou gh products extrac ted from copp er tubes considered conducive to blue water he tero trophic plate cou nts. experie n cing corrosio n , blu e water was (Webster 2001). Other treatm.ents rely on initiated. J ar tests on sections of sterile The results showed th at steril e copper removing corrosion products using w eak copper tu bing imme rsed in sterile water t ube s fill ed w ith non- ste ril e water acid solutions. However, these treatments also showed that the addition of blue produ ced high levels of copper release have demo nstrated ineffective in the long water significantly increased the amount (O 'H alloran and Smith 2002). This was term. of visible corrosion products (O ' Halloran not observed if th e water was sterile. A proj ect funded by the Water Se1vices However, if sterile water was seeded with and Smith 2002), also lending support co Association of Australia and the Copper the microbial theo1y. Examination of blue a small amou nt of biofilm and corrosion

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Black MAX is manufactured in SN8 (nominal stiffness 8000 N/ m.m) in nominal diameters ranging from DN225mm up to 600mm with a range of standard fittings . Black MAX, is the alternative to traditional rigid pipe materials, ensuring optimum performance , longer service life and low cost. For further information contact lplex Pipelines Technical Marketing Group. Brisbane Mr Peter Klouda Phone 07 3267 9944 Fax 07 3267 1511 Sydney Mr Peter Nixey Phone 02 9879 9971 Fax 02 9879 4632 All other states Mr Michael Lancuba Phone 03 9469 0326 Fax 03 9462 1540 Alternatively visit our website www.iplex.com.au.

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Dev elopment Centre is curren tl y und e rway to dev e lop a ch e m ica l treatment to effectively remove corrosion products and ca rbonaceous films from copper tubes. Th is treatment would ultimately be follo wed by surface passivation to create a tube that resists both genera l corrosion as well as the release of corrosion products. Conclusions Blue water is a complex p henomenon w hi ch ca uses significant problems in drinking water. CS IR O research aims to understand the factors contribu ting to blue water in order to prevent its occurrence as well as to develop and implement methods for the remediation of corroding plumbin g systems. Acknowledgements The work on copper corrosion has been supported over a sign ificant period by the International Copper Association, th e Cop p er D eve lopment Centre (Australia), Kembl a Copper and Crane En fi e Id Me t a Is, Hunt er Water Corporation, City West Water and Water Services Association of Australia.

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The Authors Dr Roger O'Halloran and Dr Russell Taylor are Prin cipal R esearch Scien tists in Corrosion and Electrochemistry, and have been undertaking research into blue water and copper corrosion fo r more than 10 yea rs. Nigel Goodman is an Experimental Scientist in the same area, and Fiona Smith is a Tech nical Offi cer in Mi crotec hno logy . Dr Michelle Critchley has recently joined the group as a Post Doctoral Fellow in vestigating mi cro bial aspects of co rrosion and electroc h emi cal biosensors. Co n tact roger.ohalloran@csiro.au, russell. taylor@ csiro .au, michelle.critchley@csiro.au References Arens P, Tschcwitski G J , Wollman M, Fol lncr Hand Jacobi H ( l995) Indicators for microbiologically induced corrosion of copper pipes in a cold water plumbing system . Ze111ralblntr j,,er l-lygieue 1111d U111welt111edi.::-i11. 196(5) : 444-454.

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Pumptech Tasmania Pty Ltd Graeme Von Essen 0429 436 400 Grant Petterwood 0427 436 400 Shop I/ 330 Hobart Rood Youngtown TAS 7249 Postal: P.O. Box 67 Kings Meadows TAS 7249 Phone: 03 6343 6400 Fax: 03 6343 6700 e-mail: pvepumptech@ozemoil.com.ou

Aguapro Australia Pty Ltd Environmental Monogement Elodia Perez 0418 817 177 198 Victoria Rd Rozelle, tlSW 2039 Phone: 02 9818 5921 Fax: 02 9810 1421 e-mail: aguopro@idx.com.ou

Berghu lt B , Elfstro111 Broo A. and H edberg T (200 l ) C o rrosion control m easu res in Sweden and the effect o f successio n order. Minter Srie11re n11d Tec/1110/ogy: Wnrcr S11pply. 1 (3) : 4 7-58. Cornwell FJ, Wilds111it h G and Gilbert PT (1973) Pitting corrosion in copper tubes in cold water service. Brit isl, Corrosio11 Jo11ninl. 8: 202-209. Critchley M M , Cromar N. , McClure N & Fallowfield HJ (200 I) Biofil111 accumulation in cold water copper plumbing systems and significance for microbiologically infl uenced corrosion.Jo11n,a/ ,ifApplied Microbioh\~Y (91): 1-6. Edwards M, Ferguson J F and l"l..eiber S H ( 1994) The pitting corrosion of copper. Jo111·11nl A111ericn11 Wn rer vf/orks Assorintio11. 86(7): 7490 . Fisher A. A ( 1999) Green hair: Causes and managem ent. C11ris. 63 (6) : 3 17-3 18. Knobeloch L, Schubert C, Hayes J , Clark J, Fitzgerald C, et nl. (1998) Gastrointestinal upsets and new copper plumbing - is there a connection? Wisco11si11 Medicnljo11ninf. 97(1): 49-53 . Lin C and O lson l3 H (1995) Occurrence of coplike copper resistance genes among bacteria isolated from a water distribution system. Cn11ndin11 J()l1n,nl of J\llicrobiology. 41 (7) : 642646. NHMRC (1996) C11ideli11es j,1r dri11ki11g 111nrer q11nliry i11 A11srrnlia. National Health and medical R esearch Council and Agriculture and R esearch Management Council of Aust ralia and N ew Zealand, Aust ralian Water Resources Council. O'H alloran R and S/'nith F (2002) " Investigation of the role ofmicrobially influenced corrosion on 'blue water' copper COJTOSion in Australian potable waters : Stage 2 extension". Co11fide11rinl Co11s11/rn11ry R..eporr Clv/S T- C-C2001-39, September 2002 . Pi zarro F, O livares M, Araya M , Gidi V and U auy R (2001) Gast rointestinal effects associated with soluble and insoluble copper in drinking water. E1111iro11111e11tal Hen/ti, Perspectives. 109(9) : 949-952. Taylor R , O' Halloran R, Smith F, Goodman N and Jaeger H (1998) "Strategy fo r the prevention of blue-green water from the corrosi on of cop per in soft waters". Confidential Consultancy R eport CMST-CC-98-21, June 1998. T aylor R , O'Halloran R, Smith F, Go odman N and Jaeger H (2001) "The effectiveness of bicarbonate dosing as a preventive I remedy for copper corrosion". CSIR..0 Co ,if,deurin/ Report CMST-C-C- 2000-28, January 2001. Webster B (2001) "Copper Corrosion Problems, R&D and Solutions". Presentation af Water and Copper Industry Technical Workshop co n vene d jointly by the Cop p er Development Centre (CDC) and the Water Services Association of Australia CWSAA), Sydney, 3 October 2001. Wells D B (2000) "Review Of R em edial Treatments For Copper Corrosion ByProduct R elease (Blue Water), Pitting And Cuprosolvency". Report N o 79056.01 for Wnter Ser,,ices Associatio11 of Australin.

WATER

TECHNICAL NOTE: CORROSION CONTROL IN COOLING SYSTEMS S Powell Abstract

ONDEO Nalco claims to have established a new benchmark for cooling system corrosion inhibition in the postchromate era. The Problem

120 Coll ins Street is a high profile 52 storey office building in the Melbourne C BD built in the 1980s. Th e 15,000 litre air conditioning condenser water circu it is located on the 52nd level and consists of two hydraulically linked coolin g towers. Until July 1997 chromate-based inhibitors were used with excellen t resul ts against the key performance indi cator bu t were replaced du e to e n viro nme ntal and O H &S concerns (chromate is carcinogeni c) . Th e key performance indicato r is the pitting rate, w hich must not exceed 20 mi l per year (mpy), as measu red on mi ld steel coupo ns and verified and crossc hec k ed by co rrato r t ec hn ology. Chromate based corrosion inhibitors showed pitting rates of 8- 10 mpy until replaced and had been recognised as the industry standard . Zinc phosphate based inhibitors were introduced in the second half of 1997 and within four months the pitting rate had reached 20 mpy. Within another four m onths this had reached unacceptable levels and remedial action had to be taken. The Solution

ONDEO Nalco was appo inted to manage the building's open recirculating cooling water systems (as well as its hot water heating and its chilled water closed system s). They conducted an extensive analytical testing program to determine the cause. Results suggested that soluble copper in

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Stephen Powell monitoring the water treatment program on-site at 1.20 Collins Street, Melbourne.

the make- up water was responsible. M elbou rne water is well known for its low hardness and superior dri n kin g quality bu t not for its aggression to cop per. Protection of copper and copper alloys in conde nser water circuits is well documented. Consequently water has previously been treated by the inclusion of azoles in inh ibitor formulati ons. However, the exposure of make-up water to the copper risers delivering water from street level to level 52 pro vided incoming soluble copper levels of 180 parts per billion in the cooling towers make-up. This was then concentrated to levels typically 5-8 times higher. T his cop per then electroplated as a visible copp er film fo rmatio n on mild steel components which ca used the resultant galvan ic corrosion attack. M anagem ent of the soluble copper was required and initially TT-tolytriazole in combination with a zinc phosphate based inhibitor was considered suitable to generate an ex t re m ely effec ti ve m echanism to co ntrol the excess soluble copper throughout the system.

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The initial ONDEO Nalco chemical treatment program consisted of a multi fu nctional zinc/p hosphate co rrosio n in hibitor w ith a sodium h ypochlorite oxidising biocide supplemented by a no noxidising biocide. M an ual additions of TT and zinc phosphate were made. Th e pitting rate immediately fe ll and for a short period m et requirements. H owever it then fluctuated at two to fou r times allowable levels. T he cause was the strong alkalinity of TT and the strong acidity o f zinc phosphate. T he manual additio ns had created a temporary loss of pH contro l that had a deleterious effect on the entire water chem istry control. To remedy the situ ation, peristalti c pumps and timers were installed and the requ ired qu antities of TT and zinc phosphate were injected over set time intervals. Corrosion mon ito ring over four consecutive quarters now showed mild steel pitti ng to be lower than the previous chromate based inhibitor levels. The manipulation of w ater treatment chemicals in this case has set n ew standards for practical co rrosio n control that are superior to those ach ieved with chromates. This project has also established that high solubl e copper bearing make-up waters can be efficiently treated and that oxidising biocides, especially chlorine, do no t pose a threat to asset protection if correctly monitored and controlled. The Author Stephen Powell, a chemical engineer, is Victorian acco un t m anager for ONDEO- Nalco. Phone (02) 9316 3000 e m a il spowe ll@ondeo-nalco .co m . Website: www.ondeo-nalco.com.au

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ODOUR CONTROL AT A WASTEWATER TREATMENT PLANT IN TASMANIA R van Oorschot, C French, R Millhouse, J Hingston Abstract The R osny W astewater Treatment Plant (WWTP) is located on the foreshore of Kangaroo Bay on the eastern shore o f th e D erw ent Ri ver in H obart. It services the dom estic population ofRosny and the surrounding suburbs. T he plant itself is loca ted on th e lower shores of R o sny Hi ll within 100 111 o f residences situated further up the hill. A prevaili ng onshore breeze carries any odo urs produced at the plan t towards the nearest residences. T he current odo ur control method at th e R osny WWTP co mprises: 1. inj ec ting liquid oxygen into the rising mains at three pu mp statio ns servicing the plant; 2. enclosing odorous processes at the plant and capturing any odours produced; and 3. treating th e fo ul air in two bio logical odour contro l towe rs (b ioto wers). This paper descri bes the odour control system in place at the R osny plant, operat iona l e xp e r ie n ces and prob l e m s encou ntered , and th e proposed strategy to further improve th e odou r con trol system at the plant. Key words: O do ur control, biological odour control tower, biotower.

Introduction The R osny WWTP was upgraded between 1990 and l 995 to produce a secondary treated eilluent for discharge to Kangaroo Bay. The upgrade involved the installation of a uickling filter solids contact process (10.2 M L/d design ADWF) and collection and treatment of m ost of the malod o rou s gases prod uce d in the treatmen t process. A simplified outline of the process is shown in Figure 1. As part of th e upgrade, an odo ur control strategy was implem ented to collect and treat most of the malodorous gases produ ced in the treatm ent process . T here were only a fe w com plai nts fro m th e neighbo u rin g residents aft er the up grade . H owever, th e nu m be r of co mplaints has sin ce rise n, particularly o ver the summer o f 2000-200 1.

WATER NOVEMBER 2002

The Rosny WWTP

mains is no t being met by the current oxygen inj ec tion system . W o rks now completed by C larence City Council have sign ifi ca ntl y im pro ve d t he oxyge n inj ection system. T he maj ority of the wo rk co n ce rn e d i mpro v in g t h e monitoring and control system from man ual to rem ote control. The R osny WWTP currently has tw o biological odo ur control cowers. O ne bio to wer was designed to treat odours fro m the digestors and sludge dewatering building. T he second and main biotower

An investiga tion was conducted to exam in e the current od o u r co ntro l strategy at the plant and recommend steps to opti m ise th e current system and augment the o do ur treatment capacity of the plant to incorpo rate p roposed new works.

Existing odour control Liquid o>--yge n inj ectio n is carried o ut at three pump stations servicing the Rosny WWTP . An assessment showed that the oxygen demand in the associated rising

Screening

Trickling

Re-acra1ion/ Solid, Coninc1

Filler

Tank

Disinfcc11on & Ocean Discharge

RAS

WAS

Sludge Dc-grin ing Thickening

Secondary Clarifi er,,

Anaerob ic

Digc,11011

WAS - Waste Activated Sludge RAS - Retu rn Activat ed Sludge

Figure 1. Existing Treat ment Process at Rosny WWTP

Dcwalcring

Oll-,itc Di,po,al

ODOUR

was designed to treat foul air from th e inJet and screenings room, th e flow equ alisation tank, the trickling fi lter, th e re-aerati on and solids contac t tank and the waste ac tivated sludge thicke ning roo m. T he results of an odo ur su rvey and Ausplu me modelling showed that the biotower trea ting o dours fro m the di gescors an d diges ted sludge dewatering building was in fact a major source of o dours and a complete replacem ent o f th is syste m was sc heduled to be carried out at th e tim e of the in vestiga ti o n. Furth er works are plan ne d at the plant, includi ng a new grit rem oval fac ility (GRF) pri or to the inle t screening facility and an upgrade to the sludge handling and treatment facility. O ptions considered fo r the sludge handling upgrade include de watering fo ll owed by lim e dosin g, co mposting, incineration o r disposal co land fill. C urrently abo ut 14 000 111 3 / h of fo ul air is trea ted in the main bi ological odour co ntro l towe r. T h is is estimated to in crease to up to 24 000 111 3 / h , due to additio nal fo ul air from the proposed grit rem oval fac ili ty and sludge treatme nt fac ility.

Odour management strategy T here are two c ritical elem ents to successfu l odou r manage ment at th e Rosny WWTP , nam ely: 1. optim isatio n of the curre nt syste m; and 2. upgradi ng th e c urrent system to incorporate the proposed w orks at the plant. A detail ed revie w o f th e o perati on o f th e plant revea led a num ber of ste ps to optimise the curren t odour control system. T hese includ ed: • rebal ancing the air extractio n system to the main odo ur control tower, i. e. e nsurin g th at eac h zone is properl y vented according to th e design rates;

CONTROL

• providing p H monicorin g and control of the recirculating eillue nt at the main o dour control tower; • connecting minor odo ur sources to the main odour co ntrol cowe r; • repairin g odour du ctwork leaks and plugging gaps; • seal ing doors and installing airlocks w he re possible; and • optimising the oxygen inj ection system. Another impo rtant aspect of the op timisa tion process was repair of th e smalle r odour co ntrol tower, whi ch was planrled •( fo r by Coun cil. In addition to the optim.isation of the current odour treatment syste m , th e fo llowing issues required co nsidera ti o n: • th e performance o f th e existin g odo ur control system o n ce o ptimised - furth er treatme nt o r modifica tions co the odour

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-~«' Figure 2. Ausplume Modelling - 2 Odour Units

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CONTROL

Optimhc OCT nnd /\,,c,s l'crlormnncc • Including po,,iblc Odour Survey nnd Modelling

Con,lrucl Ocdlcntcd Combined O dour T rentmcnl fo r grit rc movnl plunt ond sludge lrcolmenl plont

Trcatmenl Option, include; • Soil/Compo,1 Biofillcr • Biologicnl Odour Tower Ac1in11cd C11rbon • Chemical Scrubbing Cope, be1wecn $0.JM and S0.6M

Con,trucl ~llnor Alteration 10 OCT NO

Option, • Lncrcn,c l'.xl1 Velocity • Augment St,1ck Length

Con,lrnct Ceutroll,cd Odour T reatment Fnclllty - Provide II Second (l'olMlinal Odou Control ~'oclllty, c~.

Air from the Rosny WWTP Is tested for odour

control system may be required if it is fo u nd to contribu te to th e odour problems; • ap p ro p riate odour trea t men t technologies - e.g. activated carbon, chemical scrubbing, increasing the exit velocity, ozonation, etc.; and • odour treatment configurations - i.e. consideration of one central unit versus a number of local units. In all, ten odour treatment upgrade configurations were identified to augment the odour treatment capacity of the plant to incorporate the proposed new works. For each odour treatment upgrade configu ration , a number of trea t ment technologies were applicable, resulting in over 100 possible configurations. Based on estimated costs and the treatment capacity of various treatment tec h nologies, the most appropriate upgrade options depending on the performance of the existing odour control system are: • a second odour control unit to treat all air leaving the existing odour control system once optimised; • minor augmentation to the existing odour control system once optimised to improve dispersion, in conjunction with a separate odour control facility to treat foul air from the proposed grit removal facility and sludge handling facility; or

WATER NOVEMBER 200 2

Treatment Option, Chcmicul Sc111hhlng • Soil/Compo,t Blofiltcr • Aelivoted Cnrhon Cnpcx between ~0.5M nnd SIM

OCT - Odour COl\ltol

Figure 3. Decisi on Flow Diagram

• a separate odour control facility to treat foul air from the proposed grit removal facility and upgraded sludge handling facility, with no augmentation to the existing system once optimised. The net present cost for these options is between $0.6 million and $1.6 million. T he selection of the most appropriate configuration and treatment option can be made once: 1. the current odour control system has been optimised and assessed; and 2. treatability testing is being considered fo r the most promising treatment technologies. Figure 3 illustrates a decision flow diagram for the odour control strategy for the Rosny WWTP. T hroughout the development of the odour control strategy C larence City Council has regularly convened open community meetings. These meetings also involved representatives of government and provided a good forum for community feed back.

Conclualon The odour control strategy for the Romy WWTP was developed based on

traditional methods, involving assessment of problems and review of options. Over 100 options were assessed. T he strategy is still in a developmental phase. This paper repo rted on the initial investigative stage and outlined the general strategy for Council to implement a sound odour control strategy. The next phases of work w ill involve : 1. optimisation of the existing odour control system; 2. assessment and review of the optimised system; and 3. selection and design of the preferred odour control option.

The Authors Dr Robbert van Oorschot, is Manager Wastewater Treatment and Chris French is a Process Engineer, both at GHD Pty Ltd, Melbourne, email: rob bert_van_oorscho t @ghd.com.au Phone: 03 9278 2226 . Ri c hard MIiihouse, is Business Unit Officer Waste Management and John Hingston is Manager Asset Quality at Clarence City Council, Tasmania.

ODOUR CONTROL

TEMPORAL AND SPATIAL VARIABILITY IN ODOUR EMISSIONS M Goldstone, C Gwynne, N Turner Summary An investigatio n into the specific sources and diurnal variation of odo ur emissions explains why collection of single samples fo r olfactometty is unlikely to give a true estimate of odour emissions.

Introduction O ver th e course o f the last two years, GHD and W ater C orporation have been working to characterise odou r emissio ns from tw o o f their large wastewater treatment plants in W estern Australia. At the beginning of the study, th e accuracy of dynamic ol fac to m etry as a m ea ns of assessing o dour levels w as routinely being called into question because apparentl y duplicate sampl es we re returning significantly different odour levels as measured in o dour units. Anyone who routin ely w orks in the wastewater sector will be aware that many water quality parameters vaty regularly throughout the day, week o r year. It seem ed reasonable that a signifi cant amount o f the variability of repo rted odour values co uld be du e to a similar variability in odour emission rates.

Figure 1. Wind Tunnel and Instrumentation at the head of the Primary Sedimentation Tanks.

The wind tu nn el itself was instrumented fo r flow, pressure and temperature so that th ese could be controlled in the final calculations.

interstate and enabling a more rapid assessment of odours. All olfactometty and sampling for olfactometty _was undertaken according to the th en Draft Australian Standard 99306. Analysis M easurem ent of a large number of Olfactometry was undertaken by the olfa ctometty samples is not a particularly Odo ur Unit laborato ty in Perth, thereby cheap prospect and therefore continuous Sampling Methodology obviating the need for flying samples gas em1ss1on analysis was seen as an In order to test this a w ind tunnel altern ati v e m ean s of a ssess ing was constru cted with the intention of variability. collec ting odour and gas emissio ns on Continuous gas m easurem ent of a continuo us or sem.i continu ous basis. m et h an e and Oxidise d Gas eous Th e wind tunnel was design ed in Sulphur C ompounds (OGSC) was lin e with principles establish ed at the undertaken instrumentation supplied University o f New South Wales Qiang by E cotech. et al. , 1995) . Th e wind tunnel is M ethane was m easured using an designed with the intention of passing H oriba APHA detector which is based zero carrier air through with a velocity o n c ontinuou s flam e i o nisa ti o n o f 3111/ sec. In order to achieve this on dete ction (FID ) and c apable of a continuous basis, "zero air" was measunng to 0.1 parts p er million ge nerated by drawing atmosph eric air (ppb). through a si gnifi ca nt quantity of activated carbon. The air flo w was O GS C was m easure d using a achieved using a modified high volume monitor labs UV flu orescen ce sulphur sampler supplied by Ecotech. T eflon dioxide detector retrofitted with a sample lines w ere th en conn ected to th ermal converter that can oxidise reduced sulphur compo unds such as the outlet of the wind tunnel and these fed sample through to the instruhydrogen sulphide. T echnically it is not possible at any instant to d etermine if m e ntatio n and od o ur sampling Figure 2. Instrumentation used for conti nuous gas measurement. the instrument is measuring oxidised equipment. WATER NOVEMBER 2002

ODOUR

or reduced sulphur compounds. H owever, by turning off the converter on occasions it was possible to determine that readings fell to zero, indicating that most of the sulphur being measured was derived from reduced sulphu r compo unds oxidised by the converter. The converter temperature was set to ensure optimal conversion of hydrogen sulphide and therefore for the purposes of this program it was reasonable to assume that hydrogen sulphide was the major component of the reading. Plant Description

A further issue that we have found with many reported odour studies is the lack of reported site-specific data. In the absence of a clear und erstanding of how the plant operates it is difficult to see how an appropriate assessment of odour emissions can be undertaken . Beenyup WWTP is a typical conventional treatment plant, which treats approximately 90ML/ day of wastewater from Perth's northern suburbs. Wastewater enters the plant via three dedicated sewers that combine at the head of the plant. Raw wastewater dosing includes sodium hydroxide for pH control and chlorine for odour control. The inlet works are largely covered fr om the point of sewer combination to the screenings room, however, significant sewer gas fugitives have been noted from gaps in covers and sa mpling and viewing ports. Odours from the eastern half of covered areas are collected and treated by passing through a soil bed. Wastewater is screened before entering grit tanks. Screenings are collected by screw conveyer and collected in an open hopper prior to disposal. All screenings equipment is housed in the naturally ventilated screenings bu ilding. Grit tanks are uncovered. There is a combination of aerated and un-aerated tanks. Wastewate r goes to the primary sedime ntation tanks in a seri es of uncovered turbulent inlet channels. A variety of return liquor streams (primarily filtrate from the sludge filter belt presses) is returned into the process at these channels. Primary effiuent flows from the primary sedimentation tanks via covered but unventilated channels to the primary effiuent distribution channel, prior to secondary treatment. Primary sludge is collected at the head of the primary sedimentation tanks by surface and bottom scrapers. Skimmings from the surface and primary sludge are conveyed to the sludge digesters. There are three secondary treatment modules currently in operation, which are

WATER NOVEMBER 2002

~~--,~.-----r--,--.--~-,Be_e_,,n~y_u~p_W _W ~ T_P,..l_n_,fl_o_w-,-----r_~~--,-.-----r-~-.---,

200_0

160.0

1.0.0

.Iii

--J.--~-__ 1' __ 1' __

- -1- -

-~-~-- · --~--~-~-- ~-- ~--~-__ , _ _ J __ __ L __ L _J __ J __ L __ L

~ 120.0

JI:

I I t I I I I I I I I I - - 1- - -1 - - ~ - - L - - L- - -1- - ~ - - 1- - - L- - -1- - -1 - - ,.i -

111<>0

CONTROL

100-0

11<>0

,--T-- r - - r -,--,--r-

+-- ... --1-- - - 1 - - 4 - -

,. L,. _ _, _ _

--~--1--~-- 4--~--~ --1--4--+--•--

.J __

--L--• --~--J--L--~--1 --J--i--L-I ! I I I I I I I I t l I I I I I --,-- ,-- I --, --1 - ,-- t--, -- 1 --.-- I -- --,I - -,- !/-- ,--1 --1I --1I-- .-t -- , --

I I

20.0

0.0

, -~~,-,- -~~I~ : : :

1•

+--+--+--+--+--+--+--+--..--+---;..---,....-..--+---;--+---;--+--+--+--+--+--+--,

Sun

- - Wed

Tue

Mon

- Sat

--Fri

--Thu

Figure 3 Beenyup WWTP diurnal inflow rates. 1.0 ..--,--,--.--,--.--,---,--,---,----,,--"'T"'---,~"'T"'--,--,---,--,-~ - . . . . - ~ - - , --,---, 0.9

o.e

--:--1--~--~-~--f--~- ~--1--~-~--1--f--:--1--t--~-~--t--~--:-- t --

o.o +-.....-'-.;.. ' -.;.. ' -.;.. ' -.;.. ' -;... ' -;... ' -;... ' -;... ' ---.'. ..--'1...-...;'. ..-...'. ..-..;'-..;'- . . ;'8

'-..;.'---'----<

.... '-

.... ' - . . ; '.-

....

Hour

Zone A DO --Zone B DO - - Zone C DO

Figure 4. Beenyup WWTP dissolved oxygen levels .

•. t ...

Beenyup Fitter Belt Press Feed Flow I I I 1 I __ l __ _j __ l __ l __ 1__

0.1

i S::.. o.& ..,a: :3 o.• :I

.. .. ..,"'

if .ii Ill

I I l __ 1__ ..J _ _ .I.. __ L I

l I I I I I I __ I __ I __ I _ I __ J I

- _ 1__

I I 1 ..J __ -- L

- -1- -~-- + - - ~--1--~!

- , - - -~

--L _J_ _.., _ I

I l l __ l

I I I I I __ 1 __ 1 __ I I

L- J _ - J_ -L- -L-

~-- ~--~-~--1--~ --~I

I _ _ I __

I I I I 1 __ 1 __ 1 __ I

J __ I

.l __ L--L--1- I

-~--~-~-- ~- - ~--~ - -,--

- - ,- - , - - -r-- - r - - ,- - -,

0.3

--,--7-- r -- 1- -1--

0.2

__ 1__ J __

.1.. __ L I I

__ ,_ I

(

I-

FBP1

- - - ~ --L--L_J __ .l - - L - -L -..J--~--L-

LI I

-~--·--~--~-~--4--~--~-~--4- -~-- ~-~--

0.1 0,0"1

Figure 5. Beenyup WWTP filter belt press feed flow. Qrll Tonk OxldlHd G1110u1 Sulphur Compound• ond Odour Eml11lon1 o...

~----------------------------,-,soo Aeration Failures

0.-10

I! I

0.:1$ 0,:,0

O.H 0.20

0.11 0.10

,ooo

•

I 500

0.00

'--------~--'=-----22,Mt.y-01

0,00 i - - - - - - - " - - - ~""",e....u...._~..... 11•Mly-01 00~ 1l'•Ml-,..01 00,00 1H41)'·01 00~ 10•MIY,01 00:00

20·Ml.y•01 00:00

ai.t~lY·01 00:00

0000

1- oosc • = I Figure 6 Beenyup WWTP: Oxidised gaseous sulfur com pounds and olfactometry results .

ODOUR

CONTROL

all conventional uncovered co occur when c hlorine was Primary Sedlmenta!lon Tank. Inlet activated slu dge tanks being do se d to th e Average Hourly Oxidised Gaseous Sulphur Em issions , 0.025 cons isting of an initia l wastewater. It h as not been mechanically mixed anoxic possible to find out why th is ''° Ji 0.020 zone fol lowed by an !·' ·-,, happened. ,_ aerated zone . As shown in Figure 8 the -----, ' 0.015 Mixed liqu or from the I aerobic zone of the ' activated sludge tanks flows Wastewater T reatment plant ~ to uncovered secondary also fo llows similar trends to ~ se dim e n ta ti on tanks J 0005 the primary se dimentation thro u gh mi xed liquor 20 channels (two uncovered, tanks. H oweve r, emissions one covered). C larified a re alm ost an orde r o f 0 1 2 3 4 5 6 7 IS 9 10 11 12 13 1' 15 16 17 18 1'il 20 21 22 23 seconda r y effluen t is magn itude lower than from ChloriM OH · May 2001 -··-Chioflne 0n - NcN2001 · · · · · Ct*wlne On· Oct 2000 conveyed co an ocean wuiew11.,. Fiow the primary sedim en tation - - - Cnlome 0oMtg outfall. tanks. Sludge is digested in five Figure 7. Beenyup WWTP: Hourly OGSC emissions from the Primary Figure 9 demonstra tes covered, heated anaerobi c Sedimentation Tank, effect of chlorine dosing. another key variable in terms sludge digesters . Waste Activated Sludge is of variatio n in emissions. to fol low th e trend for wastewater flo ws ch ickened using dissolved air flotation Samples for methane, OGSC and olfacinto the plant. T his means that odour prior co sludge digesti on. Digested sludge cometry were taken along th e length of e missio ns va1y by over an order of is thicke n ed using polymer and dried in the aeration tanksshowed th.at e mission magnitude throughout the day . fil ter belt presses in the sludge handling rates are mu ch higher at the h ead of the building. le is then stored in a hopper prior To some extent these em issions are aeration tank, presumably due co strippi ng to bei ng disposed off-site. modified by th e degree of chlori nation of odours by th e air bubbles in the first that occurred (Figure 6, dotted lin e) . Gas from the digesters is coll ected in H owever , the highest emissions appear a low-pressure gas holder and either used few metres of the tank . co heat th e sludge or directed to a gas flare. Odour is con trolled in the sludge handling bu ildi ng by potassiu m permanganate dosin g and use of odour maski ng scents. T he room contain ing the filte r belt presses is ventilated by a .large ce iling fa n , Technical & Scientific an open grating around th e hopper and Equipment several windows.

I ..,.

Operating Conditions

T ypica l flow rates into the plant are shown In Figure 3 They indicate a ten fold variability between peak and low flow co nditions To some extent dissolved Oll.')'gen levels in the seconda1y aeration tanks reflect this flow, as shown in Figure 4 .. Lowest levels of dissolved oxygen are seen in Zone A, th e zone directly down stream of the anox1c zones. Operation of the fil ter belt presses occurred during between four o'clock in the morning and up co eight o'clock in the evening as shown in Figure 5. These m aterials were trucked to landfill.

Results Results of OGSC (mainly H 2S) and odour emissions from the grit tank were highly variabl e. Figure 6 shows emissions from the aerated section of the grit tank and it can be seen how much the OGSC emissions change when aeration did not occur. Olfactometry measu rements were generally in line with OGSC emissions. Typical emissions of OGSC from the prima1y sedimentation tanks can be seen

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Achieve ppb to ppt sensitivity, so fast you won't have to wait around for results. Ideal for online or onsite screening.

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ODOUR

CONTROL

Auoblc Zone - Chlorlne On

Aerobic Zone • Front

Aver1g, Hourly OxldlMd G1Hou1 Sulphur Emlstlon1

Aver1ge Em1Hlon1

0.008 0.007

iJ ...,,

120

0.000

,.,

M1 :Z

f !i

120

• 100

0.010

. If

o.oo,

"h'l Is l '·"" " f 0,000

II ...., o.oo,

0.001

0,001

s , a • , , -

Cl'llofll'rtOtl•Mt.yto0 1

....,a ,,

,,,, ,a ,,,, ,,~ a,

Figure 8. Beenyu p WWTP: Hourly OGSC emissions from the front aerobic zone, effect of chlorine dosing.

O dou r emissi ons at wastewa t er trea tment plants vary considerably with time and somewhat in line with the inlet flow rate. Some sou rces were very variable (eg. anoxic zone, grit tanks) and we believe that this short term variation should be smoothed by taki ng odour samples ove r a thirty minute period.

....,

•

Collecti on of single odour samples at_ one time of the day is likely to produce results that are unrepresentative of the true emission rates from any single point in the plant. Even if olfactometry samples are taken in controlled conditions and transferred to a high standard laboratory, much of the variation in olfacto metry results may

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WATER NOVEMBER 2002

. .

0 100

Figure 9 . Beenyup WWTP: Gas and odour emi ssi ons along t he aeration tan k (chlorine dosing on ).

••••••••••••••••••••••••••••

L.I ~~~.1~~f'.,_m_~•_I _ _-_ c•_"'"_' °_"_.oo_sc_1mo _·m_21,1_ __,

w»i.w~,iow

Conclusions

0.002

f f Ii

be due to sampling at inappropriate tim.es. Spatial variability across processes was a small part of this study, and these results indicate that great care should be taken when extrapolating em1ss10ns from one location across an entire process. In undertaking this study we also fou nd some evidence of spatial variation in primary sedimentation tanks where odour emissions were higher in the area where most sludge was settling out. Careful assessment of the flow characteristics of any process are important in determining the tru e odour characteristics . T he extent of any study has to be governed by sensible commercial fac tors . T his potential variability in results has to be assessed by considering the cost of undertaking such a stu dy balanced against the costs that might be associated w ith incorrectly sized odour control, inappropriate results being put into the public arena or apparent non-compliance w ith license emissions.

Reference s Jiang, K, Bliss, P and Schulz, T. 1995. The development of a sampling system for determining odor emission rates from areal surfaces : Part I. 'Aerodynamic Performance'. J oumal of the Air & Waste Management Association. 45 . 917 - 22 .

The Aut hors Dr Mark Goldstone an d Christopher Gwynne a r e Environmental Consultants with G H D . email, mgoldstone@ghd .com.au. Nick Turner is Su pe r vis ing E nginee r, Wastewater Treatment at the Water Corporation , Leederville, W.A.

WASTEWATER

CALIBRATION OF THE BIOWIN MODEL FOR N REMOVAL: PART 2, FULL-SCALE STUDY D W de Haas, M C Wentzel Abstract Mathematical models of activated sludge systems are useful tools for both design and operational optimisation of such systems. Kinetic models in particular (e.g. BioWin®, UCT, IAW ASMl, 2, 2d etc.) have found widespread engineering application. H owever these models are complex in that they attempt co simulate simultaneous biological processes (e.g. hydrolysis, growth, death) fo r a number of different groups of organisms. The models contain a large number of parameters, many of which cannot be calibrated by direct measurement in conventional laboratories and require more in-depth research. In a previous paper (Pare 1, published in September 2002 issue of Water), based on the results of a desktop study, we examined differences between two versions of the Bio Win model and the older UCT model. These differences originated from the choice of settings for key parameters that strongly influence denicrificacion rates . T his has direct bearing on the nitrogen (N) removal p red ictions of th e models and has relevance in Australia where man y wastewater treatment plants need co achi eve low effluent total N targets.

WAS (lo

~ - - _,..thickening and an111oblc d~Htlon)

Primary RIW

S edlm en ta b'on

Sawag e

General PurpoH

Recycle

l:Lf..U£lL.. (RAS)

U.- - - - - - - - - ~ - ' Primary lludD• • (to 1n11robtc

AX AE GP Recycle

• •

Anoxlc Aerobic Gtntrtl Pu,pON Rtcr,I• (itcluo, g 1ludg1 dewate,lng liquor• and wuhwater)

d~ntlon)

Figure 1. Simplified process flowsheet for Victoria Point STP, showing the nitrogen remova l activat ed sludge plant.

This paper presents the results of a calibration study for a full-scale Nremoval activated sludge plant in Australia using the Bio Win model. We revised the model calibration, based on our desktop study, and applied it to the full-scale plant. U sing measured diurnal influent, reactor and effluent data, we fo und good agreem e nt between o bse rved and predicted data. The results confirmed that the more recent defau lt settings in Bio Win are more realistic fo r this type of p lant, compared to previous model versions. By means of batch tests with samples from the full-scale plant, we found similar actual denitrification rates to those measured historically in the UCT laboratory for this type of system. WATER NOVEMBER 2002

WASTEWATER

Keywords: Activated sludge, model, BioWin, UCT, ni tr oge n removal, denitrificatio n, full-scale calibration

Introduction The va lue of computer-based models for simulation of activated sludge systems hinges heavily on calibration of the model processes to observations of the underlying biological reactions. Such investigations are usually carried out at a research level. H owever, in several instances, discoveries that led to the original concept designs of such treatment system s were made at full-scal e. By taking observations from full-scale treatment plants and applying process engineering theory (e.g. kinetic model simulations), design ers of such systems are able to gain useful information that increases confidence for futu re designs or optimisatio n of existing systems. In Part 1 (September issue of Water) we demonstrated differences in calibration of processes for denitrification in kinetic activated sludge models, namely BioWin® (from En11irosim, Canada), the older UCT (University of Cape Town) model named UCTOLD (Dold et al., 1991), and the original UCT steady-state theory (WR.C , 1984). We fou nd that after recal ibratio n, newer versions of Bio Win conformed closely to the older UCT model in respect of the so-called K 2 denitrification rate from steady-state theory. In the kinetic mo dels this rate corresponds to the growth rate for heterotrophic organisms utilising slowly biodegradable substrate under anoxic conditions. In this paper we focus on the application of the Bio Win model to a typical fu ll-scale nitrogen removal activated sludge process in Australia. Ou r aim was to test whether the denitri fication rate observed from full-scale data matched the rate predicted by the BioWin model, using the recalibrated settings mainly derived from historical research in th e UCT laboratory.

Table 1. Measured and adopted settled sewage characteristics for Victoria Pt STP Parameter

Unit

Value

Source

266 107

123 17

M M

f na

46 11.6 0 .05 0 .08 0.18 0.21 0. 78

f nu(s) µ A, d·l

0.016 0.52

COD

mg/ l

BOD

mg/l

Total SS

mg/l

Inert SS

mg/l mg/ l as N

TKN TP

mg/ las P

Nitrate

mg/las N

Fraction of Sol. Unbiod. COD relative to Total COD

f us

Fraction of Part. Unbiod. COD relative to Total COD

f up

Fraction of Sol. Biod. COD relative to Total CO D

fbs

Fraction of TKN as ammonia Fraction of TKN as Sol. Unbiod. TKN Max. specific growth rate of autotrophs

examined as an hypothetical test case in the previous study (Part 1) . Furth ermore, all necessary reactor and Oow data (inOow and recycles) for this plant were available from computer-based plant records.

M M M

C M M

Influent and plant characteristics A simplified process Oow sheet for Victoria Point STP is shown in Fig. 1. In order to model the process, it was necessary to characterise the inOuent. Due to the significant impact of the General Purpose (GP) recycle stream (Fig. 1), which contains liquors from an anaerobic digester and sludge dewateting plant, for modelling

purposes attention was mainly focussed on charactetising the settled sewage stream (i.e. after primaty sedimentation). By means of samples taken at two-hour in tervals over three 24h periods, detailed information of the settled sewage characteristics was obtained. Similarly, whi le the settled sewage sa mpl es were be ing co lle cted, profiles of the activated sludge reactors were taken for key process parameters such as soluble ammonia and nitrate concentra tions , mi xed liquor suspended so lids (total and volatile) concentrations, as well as oxygen uptake rate (OUR) . OUR was measured using

Table 2. Plant design and operating data for Victoria Pt STP Unit

Value

Raw sewage flow, average (dry weather)

Ml/d

3,8

Raw sludge flow, average

kl / d

GP recycle flow, average

kl / d

Settled sewage flow, average

Ml /d

39 550 4.3 6.0

Parameter

a-recycle ratio, wrt raw sewage flow s-recycle ratio (RAS). wrt raw sewage flow Anoxic reactor volumes (4 No., vol. each)

kl each

Aerobic reactor volumes (2 No. vol. each)

kl each

Victoria P o int Sewage Treatment Plant (STP) in Redland Shire (approx. 30 km east ofBrisbane) was selected as a case study for full-scale calibration of the BioWin model. The main aim of the study was to m easure actual denitrification rates on the p lant for comparison w ith BioWin model predictions. To do this, the model needed to be set up to simulate the full-scale plant. In this respect, the activated plant at Victoria Point STP was ideal in that it is a Modified Ludzack-Ettinger (MLE) process, with a very simil ar configuration to that

Aerobic reactor No. 1 operating DO

mg/ l

Aerobic reactor No. 2 operating DO Secondary clarifier No. 1, Area

mg/ l m2

Secondary clarifier No. 2, Area

Secondary clarifier No. 1, Volume

WATER NOVEMBER 2002

M= Measured data; C= Calculated data using BioWin and measured input data

Full-scale plant case study

0.1 to 0.3 172 340 519 1352 95 to 114 11 to 14

mg/l

3220

Secondary clarifier No. 2, Volume

Waste activated sludge (WAS) flow

kl/d

Sludge age (Note 1) Operating MlSS (average Aug/ Sep 2001 data)

% MlVSS (average Aug/ Sep 2001 data)

1.5 120 436 2.8 to 3.0

Note 1: Sludge age calculation excludes clarifier volume but includes effluent suspended solids (10 mg/L)

WASTEWATER

AE2 reactOf, 28-29.08.01 & 5·1 1.09.01

20.0 180 160 "0

i i

a o

12.0

100 -

28'8 NH3-N 519NH3 819NH3 11/9NH3

BIOWIN/ UCT ca1ib

• • • BIOWIN v121 dolavlt - - - B1OWIN v11000fault

Model calibration

oo~---d~.'.'._______:.;b::.:::~:::::;:::;=! o·oo 200 .- ·oo 6 :oo s :oo 10-00 1200 14 -00 1&·00 10.00 20:00 22·00 o:oo rtM (hmm)

Figure 2a. Ammonia reactor profile: measured and modelpredicted data AE2 reactor. Data tor 28-29.08.01 & 5-1 1.09.01

20.0 - , - - - - - - - - - - - - - - - - - , GHD/ UCT calibrallon Roa.eiwo sottlor "ON'

180

2818 NOx-N

5/9 N03-N

8.i9N03-N

1 l/9N03· N

160 14.0

; 12ot:,-----t- -- .l=

"------,---------:-:.,--c"-<I

10.0

11/9N02·N

~ 8 .0

-BIOWINJUCT ca.lib, React~e Settlttr OFF

BIOWI N/ UCT cal:b

• • - BIOWIN v121 default

20 0.0

--- - --+-+• f

- - - BIOWIN Yl 10 dola..11

t • t

8 0- -

- ----,

000 2·00 4:00 6 '00 8:00 10:00 12·00 1-4 :00 1600 18·00 20-00 22:00 0:00 rime (h:mm)

Figure 2b. Oxidised N reactor profile: measured and modelpredicted data AE1 reactor, 28-29.08.01 & 5-1 1.09.01

120 -,-- - - - - - - - - - - - - - - - ,

100

Iii 80

grab sa mples of mi xed li quor coll ected every 1 to 2 hours from 0700 to 1900 and read within 15 111.in. of sampling using an O UR meter described by Randall et al. (199 1). In o rder to co nfirm the validity of the data collected fo r m odelling, mass balances for COD and nitrogen were taken around the activated sludge plant. The results gave mass balances (out/in) of95% and 100% respectively for COD and nitroge n. A summa1y of the settled sewage charactetisation is given in Table 1. The plant design and operating data are summarised in Table 2.

27180\.JAI

._ 0

2718 OUR2 28/SOURI 28/8 OURZ

5/90UA1

• 5J9 OUA2 X 8190UAI X

8/90UR2 11/90UA1 11/90UA1 BIOWIN/ UCT eaJ:t1 • - - BIO WIN v121 delauH - - - BIOWIN vl 10 delauh

a ,o 20

'ix

o:oo n>0

4'Cl0

&:oo a·oo

1000 12·00 1• ·00 1&:00

1soo 20·00 22:00 o·oo

lime (htTVTI)

Figure 2c. OUR profile: measured and model-predicted data Vlclona Pl STP MLSS prorne. AE2 reac1or. 28-29.08.01 & s-11 .09.01

•500 - , - - - - - - - - - - - - - - - - - ,

•ooo t--- - - -...L. ~ - -- - - - - - - - - - - - j ! ... • --::- .... . .. . ... :":.\. • . x .... t • x,..X~ ___.

3500

3000 -

- - ~ - - - · · ; · - • • . • •• -··

i 2500 + - - - - --S--'--''-'------------4

~~ t---- - - - - - - - - - 4

•

S.11 MLSS

8/9MLSS 11/9MLSS

28/S MLSS

1500 + - - - - - - - - - - - -- - - - - - <

- B lOWIN/UCT calitl.

1000 -t--- - - - - - - - - - - - - - - - ;

• • • BIOWIN v12 1 deia lJlt - - - BIOWIN vi 10 defaull

500 -t--- - - - - - - - - - -o:oo

--i

2.00 4:00 s·oo s·oo 10:00 1200 1.c:00 1&·00 1s:oo 20:00 22:00 o·oo r me(h·mm)

Figure 2d. M LSS profile: measured and model-predicted data

Th e mod el was cal ibrated by co mparing mod el predictions wi th actual data collected by m eans of diurnal rea ctor profi les for ammon ia, nitrate, OUR and MLSS or MLVSS. Examples of th e observed and model-fitted data are shown in Figures 2a, b & c. It can be seen that a good fit for reactor ammonia was obtained. Fairly good fits fo r nitrate were obtained w ith the de fau lt se ttings of the new version ofBioWin (v. 1.2.1 ). This was not th e case when usin g the defa ult valu es in th e old er Bio Win version (v. 1. 1.0). After refinement to resemble the cal ibration of the U CTOLD model, the BioWin predictions gave an impro ved fit for nitrate (Fig. 26). It is wo rth noting that depending on plant loadin g and operating co nditio ns, the sludge blanket in secondaty clarifi ers may be quickly depleted of oxygen , leading to anoxic conditions and hence d enitrification. Whilst d en itrifi cation in th e seco ndary clarifiers can help to reduce eillu ent nitrate concentrations, it can also lead to deterioration in clarifier solids removal performance due to release of gaseous products of denitrifi cation (e.g. N 2) lead ing to sludge flotation. The operators of Victoria Point STP frequ en tly experienced th is problem and simulations suggested that denitrification reactions in the seco ndary clarifier were significant. In BioWin, the user has th e option of " turning o n" bi ological reactions in the secondary clarifier. For this case, the effect on diurnal nitrate concentrations in the second aerobic rea ctor (feed to clari fie r) is shown in Fig. 26. It was noted that the measured OUR values in the first aerobic reactor dropped lower during off-peak tim es than predicted by the model (Fig 2c). Lower OURs (around 20 mg 0 2 /L. h, which correlated with observed rates) were predicted for the early m o rning before the morning peak in the second aerobic (data not shown). R efinement of model calibration would be necessa1y to ac hieve the correct distribution of O UR between the two aerobic reactors. The fact that the measured and predicted peak OURs corresponded reasonably well added confi dence to th e calibration since oxygen consumption is an important part of the overall COD m ass balance in an activated sludge system. The model prediction of mixed liquor suspended solids (MLSS) was fair but not co mpletely satisfactory (Fig. 2d) . Th e model predicted an average MLSS of 3025 mg/ L, compared with the observed valu e of 3220 mg/ L at the time of this study. The measured ratio of mixed liquor volatile suspended (MLVSS) to MLSS was 0.83, compared to the predicted valu e of0.80. These model predictions of ML VSS were achieved by adjusting the parameter in BioWin that defines the COD :VSS ratio of the particulate solids in the influent. The default value for this parameter in BioWin is 1. 60 mg COD/ mgVSS. We adopted a value of 1.40 for this parameter, which gave good agreement for the overall COD:VSS ratio of the mixed liquor solids (1.42 mg COD / mg VSS predicted; 1.40 m g COD/ mg VSS measured). W e believe that the main reasons fo r differences between predicted and m easured MLSS (or MLVSS) values were limitaWATER NOVEMBER 2002

WASTEWATER

tions arising from working with data from a full-scale plant. Examples of such limitations in this study were: • uncertainty in estimation of the unbiodegradable particulate influent COD fraction ((,p) - we estimated this parameter based on observed soluble and total COD and BOD fractions, readily biodegradable COD estimation using the method of Mamais et al. (1993), and the BOD converter model in BioWin. We believe there are still inherent limitations in this methodology, but no alternative method was available; • uncertainty in estimation of the true sludge age of the system due to factors such as: - scum accumulati on on the aerobic reactors; - possible sampling errors affecting effiuent solids estimation (e.g . time of day when operators apply a water spray on the clarifiers to break up any floating sludge mass, leading t o additional solids loss via the effiuent); and - possible metering errors on the plant (e .g. discrepancy of - 10% between influent and effiuent meters was found; accuracy of WAS meter was not checked).

Batch denltrlflcation tests In ord er to compare actu al and modelled denitrificatio n rates, a series of batch tests was undertaken. M ixed liquor samples (2 L) were w ithdrawn from the second anoxic reactor near the exit point of the first anoxic reactor. T he time of

5/9/01 Temp.= 23 °C 25.0 After nitrate addrtlon; start of denitflfication test /

? g

<> NH3-N, mg/L 15.0

• Nox-N, mg/L

5! z 0

10.0

-*- No2-N, mg/L

+---------"'~--------------!

Before nitrate addition

0.0

--~--------------,.::,,,.-----1- ,.J

0:00

1 :00

2:00

3:00

4:00 5:00 Time (h)

6:00

7:00

8:00

Figure 3 . Typica l denitrificat ion profile during a batch t est at Victoria Pt STP.

sampling was between 1000 and 1100, which corresponded roughly to the time of settled sewage peak load entering the activated sludge plant from the primary sedimentation tank . Model predictions indicated only low concentrations of readily biodegradable (RBCOD ) (<6 mg/L) would be present in the mixed liquor at this time and point of sampling. At the expected initial rapid (K 1) denitrification rate, this small amount ofRBCOD would be depleted within 20 min. of sampling. H ence, the K 2 denitrification rate could be determined from the batch test results fo r these samples in th e period ca. 20 min. after sampling. In fact, in one of the four tests conducted, the higher initial denitrification rate was

observed over th e first 20 min; in the other cases, the short delay in transferring samples from the full-scale reactor to the laboratory appeared to have resulted in depletion of residual RB COD. T he m ixed liquor samples were stirred at room temperature for six to eight hours in a tall glass jar. T he batch test was started by the addition of a 10 mL sodium nitrate solution containing sufficient nitrate to increase the mixed liquor concentration by 20 m g NIL. The stirring rate was set as slow as possible to minimise air entrainment but keeping the solids in suspension. Aliquots of mixed liquor were withdrawn at regular intervals and immediately filte red, firs t through a paper filter followed by a 0.45 µm filter.

Table 3. Comparison of measured and predicted denitrification rates for Victoria Pt STP. Parameter

Reactor denltrlflcatlon rate (mg/L.h), average over 24 h period

Anoxic reactor no. Measured rate + (23.3 to 24.8°C) BloWin predicted rate, 23°C (after recal.) **

5 .7

3.9

UCT steady-state theory, 23°C

BloWln predicted VSS

Predicted heterotroph active mass fraction, mgVASS/ mgVSS

3.4

Not applicable *

BloWln predicted rate** (after recalibration)

Not applicable *

UCTOLD UCT steady-state theory '

2 .9 4.0

2810

2538

0.283

0.073 to 0.081 0.165

0 .098

0.081

0.112

0.084

0.101 ± 0 .025 on 50%IIe (± 30%lle) basis

+ Results of batch tests on four separate days In Sept 2001, sampled st from second snoxic reactor of full-scale plant. * The rate in the first snoxlc reactor Is heavily Influenced by the influent RBC0D and was excluded from this Investigation.

** BIOWIN predictions using v1 .2.1, after recalibration (GHD./ UCT cal/brat/on).

WATER NOVEMBER 2002

2.8

Average specific K2 denltrlflcatlon rate at 20°C (mgN/ mgVASS.d)

Measured rate +

# WRC (1984)

Anoxlc reactor average VSS or VASS (mg/L)

Measured VSS , batch tests

Parameter

3 2.8 to 3.1

13.8

UCTOLD, 23°C

Parameter

Not applicable *

WASTEWATER

The filtered samples were expected while u tilisation B lo Win chart analysed for nitrate, nitrite 22 , - - - - - - - - - - - - - - - - - - - - , - Batch reactor NO3·N of slowly biodegradable o NOx 28108/2001 - 20 and am monia using a substrate occurs. + NOx 5109/200 t ,::! 18 " . . . o NOx 8109/200 t flow-injection analyser • T his study focussed on • NOx 11109/200 1 by Redlan d Water model cal ibratio n for the laboratory (NA T A K 2 denitrification rate. In accred i ted). T h e kinetic models this rate is tem perature of the test lin ked to hydrolysis and ~ 8 • • • · · • • • ••• • · · · • • • • ;A · • O • · • • · • • • • • • · • • • • was m easured (range 23growth processes for : ~ . oo .:..... . 250C). = ~ . : ... : slowly b io d egradabl e z : · · ·e1ciw1~: · A typical deni trifi(complex) substrate (see cation profile is shown in Part 1). T he resul ts of this 10:00 AM 12:00 PM 2:00 PM 4:00 PM Figure 3 . A total of fou r study have illustrated the TIME such tests was conducted. se n sit iv i ty of mo d e l Negligible n itrite Figure 4a. Plot of observed and BioWin-predict ed batch reactor nitrate predictions to changes in profile, before reca libration in this study (BioWin v.1.1.0 settings). formation was fo u nd in key model parameters for all the tests. T he denitrith ese processes. T h e BloWln chart fication rate for each test 22 m odel N removal predic- Baton ruo1or N03·N ....· .. . ... . • NOx 21/08/2001 -10 was calculated by linear tions will similarly be very + NOx a1001aoo 1 ,::! 11 ..', .... ' ..... ' ..... o NOx 8/00/1001 sensitive to changes in regression of th e nitra te z • NOx 1110012001 1:11111 data. The calculated rate k ey pa r ameters (e.g. ,!. 14 was corrected to 20°C anoxic yie l d of IJC 0 11 (acco r di n g to va n heterotrophs, m axi m u m ~ 10 Haandel et al., 1981) specific growth rate) that 0 • assuming a temperature affect the growth processes a coefficient of 1.05 . A for RB CO D . T h ese • 4 compariso n of t h e processes correspond to I observed and mode l the hi gher K 1 denitrifidenitrification rates 10100 AM 11100 PM 1100 PM 4100 PM cation rate in steady-state TIMI observed is given in Table theory, which were not Figure 4b. Plot of observed and BioWin-predicted batch reactor nitrate considered in th is study. 3. Table 3 shows that the profile, after recalibration in this study (GHD/ UCT). Acknowledgements reactor denitrification rate The similariry between the specific T he assistance of Redland W ater measu red in th e batch tests was similar denitri ficatio n rate calculated fro m the with com pletion of this research project to that predicted using Bio Win (v.1.2.1) BioW in resul ts and the "standard" K 2 is gratefu lly acknowledged. In particular, after recalibration to approxim ately the value used in UCT steady-state design the o perators at Victoria Pt ST P and the same basis as the U CT model. Figures 4a theory (WRC, 1984) confirms that the labo ratory staff at R.edland Water are & b show the matc h between observed calibration o f the two approaches was thanked for their enthusiastic assistance. and Bio W in-predicted nitrate profiles fo r equivalent after recalibratio n of BioWin . the batch tests. T he improved match after The Authors recalibration is evident by comparing Conclusions Dr David de Haas is with GH D these figures. T he foll owing conclusions were drawn b ane o ffice), e-mai l ad d ress: (Bris Ass u ming a constant active m ass from this study: ddehaas@gh d. co m .au. Prof Mark fraction (projected fro m the BioWin), and Wentzel is w ith the Dept . of C ivil • Calibration of the Bio Win model to a using the m easured VSS data during the fu ll-scale N removal activated sludge plant E ngineering, U ni versity of Cape Town, batch tests, the specific K 2 denitrification in SE Queensland confirm ed that the South Africa. ra tes were calculated fo r the batch test revised default Bio Win model settings are data. The results were also si milar to the References more appropriate than older versions. specific rates calculated from the recaliDold P L, Wentzel M C, Billing A E, Ekama • Although some problems were still brated model data, and within the 20%ile G A and Marais G v R . (1991) Activated sludge encountered with fitt ing VSS data, batch to 80%ile range of data given by WRC system si1111ilatio11 programs (v. 1. 0). Water tests of the reactor denitrificatio n rate in (1984), based on research in the UCT R esearch Commission, P retoria, South the full-scale plane gave similar results to labora tory (Table 3). T he BioWinAfrica. that from the revised BioW in model. predicted den i trification rate was Mannis D, Jenkins M C and Pitt P (1993) A O nly minor changes to key parameters significantly higher than the measured rapid physical-chemical method for the deterwere required to improve the fit between ni.ination of readily biodegradable COD in values for the second anoxic reactor (and model and measured reactor data. municipal wastewater. Water Res. 27 (1), slightly higher for the third anoxic 195-197. reactor). This is ascribable to the "inter• W hen conducting batch denitrifiRandall E W , Wilkinson A and Ekama G A fe ring" effect of small amounts of residual cation tests, attention needs to be paid to (1991) An instrument for the direct deterRBCOD. As noted previously, some the point and time of sampling in o rder mination of oxygen utilisation rate. Water SA RBCOD is carried over from the first to differen tiate effects caused by the 17 (1), 11-18. anoxic reactor and small amounts are also presence ofRBCOD. In this manner the Van Haandel AC, Ekama G A and Marais GvR generated in the model through fermenobserved (or predicted) denitrification rate (1981) The activated sludge process. Part 3 tation reactions operating at low rates in can be compared to the lower rate (the - Single sludge denitrificacion. Water Res. 15 , the model under anoxic conditions. so- called K2 rate in steady-state theory) 1135-1152.

ti /;· ·L/J~; F> I s···· _. .......

:i·:::: ::::;:::::·~:>:. ::::::::::

------------------.

WATER NOVEMBER 2002

WASTEWATER

BIOSOLIDS MANAGEMENT IN ENGLAND AND FRANCE D Stevens, J Kelly, C Liston , D Oemcke Summary As part of the Australian National Biosolids Research Program a study tour of E ngland and France was organised in early 2002 to review practices and trends in th ose co untries for the ma nagement of biosolids (products containing organic matter from the wastewater treatment process). This is an edited repo rt on the findings.

80000 70000

... ...>,

8. VI C

.2 ~

Introduction Biosolids use in Australian agricul tu re is currently developing at different rates in the various states (Figure 1), with regulatory and environmental pressures directing treatment plants away from unsustainable practices (e .g. sea dumping and stockpiling) towards the development of more beneficial and sustainable options. A study tour to England and France gave the participants an opportun ity to experience, first hand, how biosolids are managed in these countries. The tour formed part of the communication strategy for the Australian National Biosolids R esearch Program, w hi ch has the overall aim of developing a sound scientific approach to assessing and implementing realistic guidelines for agricultural use ofbiosolids, suitable for a w ide range of Australian soils and environmental conditions (see http: / /www.awa.asn. au/ NSIG/bio/index.asp). The tour included an overview of the regulatory components of biosolids (sewage sludge) management in England and France, the logic and science that currently underpins regulation and guidelines and how these guidelines have been developed, how they are implemented, and how this has changed the technology for treatment of biosolids, as well as looking at possible changes to European regulations in the future. A critical aspect that was also studied on the tour was the public p erception of agricultural use of biosolids in relation to scientific assessments of risk. During the tour the group visited a broad range of processing sites, covering: sludge incineration; energy recovery; wet air oxidation; thermal hydrolysis; centrifuging and lime stabilisation ; belt pressing; open composting; enclosed 56

WATER NOVEMBER 2002

60000

<II

oAg Reuse

50000

â&#x20AC;˘ Produced

40000 30000 20000

State

Figure 1. Estimated biosolids production and use in Australian agriculture, on a state-by-state basis. Use greater than production is being achieved in SA due to the availability of a large stockpile of biosolids.

co mposti ng; and land applica tion. The group also visited research sites of Vivendi and Thames Water dealing with enhanced anae r obic digestion a nd th ermal hydrolysis.

environmentally friendly, than incineration or landfilli ng, and political views reflected this. In both countries agricultural application dominated biosolids reuse.

Factors driving options for biosolids management

Environmental

During the tour a broad range of factors were observed to influ ence the management of biosolids. These factors included politic al, environme ntal pressures, regulatory change, changing social attitudes, changing markets, changing economics, and developments in science. Political factors

The tour fo und that ocean dumping of biosolids, once practiced in the UK, has been banned for environmental reasons, and although landfill was currently a cheaper option for disposal ofbiosolids, it was consid ered an u nsustainable practice. Both the UK and French governments viewed agricultural use as the best practical environmental option in most circumstances, however, they also realised that this was not always possible or practical. Environmental groups and the general public tended to perceive agricu1t u r a l u se as better, or more

Landfilling, stockp ili ng, ocean dumping, land application and incineration have previously been considered acceptable routes for disposal ofbiosolids. All these routes are now under pressure due to environmental concerns and social change. For example, during the tour we saw examples w here landfill has become increasingly expensive, stockpiling was no longer considered acceptable, sea dumping was not allowed and land application and incineration was more carefully regulated. Regulations

In all countries visited, guidelines relating to agricultural use of biosolids were continually being reassessed and regulations tightened. All the utilities visited expected a lot more discussion in the future on the application ofbiosolids, greenwaste and other residuals to soils throughout Europe. The current EU directive 86/278/EEC relating to biosoli ds reuse on land regulates: banding and soil limits; withholding periods after use; sampling

WASTEWATER

and analytical recording of the public's h eal th Table 1. Positives and negatives for using biosolids in European requirements; and codes of co nce rns. agriculture. practice for agricultural use T o address and overcome of b iosolids an d waste Positives Negatives m any of these h ea l th ma n agement l icensing concerns, the UK developed Nutrients (N, P, S) Heavy metals regulation. In the future th e Safe Sludge Matrix Transport problem Organic matter metal concentrations will (discussed below), w hich Trace elements Odour be revise d (lower) and initially seem ed to be driven Nutrient release characteristics Soi l compaction during application additional metals added by consumer perceptions (eg. chromium) pa thogen Recycling a valuable resource Timing of production and application and limited scientific under- liquid sludge injected control will be stricter, standing. This has now led - stock pile of cake controls will be placed on to a conservative and precauEnd user perception adsorbable organoha logen tiona r y approach to (organochlorine) managing biosolids appl icompounds (AOX), linear cation to agticultural soil, but â&#x20AC;˘ the use of a prescriptive list of treatment alkylbenzene sulphonates (LAS), Di-(2with a better scien tific u nderstanding. processes was considered inappropriate as e thy he xy l) ph thalate (D E H P ), However, there appears to have been no this will not cover new processes that may nonylphenol ethoxylates (NPE), polynuscientifically established link between evo lve. clear aro matic hydrocarbons (P AH ), biosolids use and the occurrence of polychlori nated bip henyls (PC B), and Social disease through food or water contamidioxins (PCDD) and technical details will In both France and England there is nation, w hen curre nt gu idelines were change. growi ng concern in so me sections of the followed. A dinner presentation by the UK's community abo ut the use ofbiosolids in Department for Environment, Food and Markets agriculture, which is in part due to other, Rural Affairs highhghted several concerns non-biosolids related food scares such as In both France and England , all th e for the future ofbiosolids. These included: bovine spo ngiform enceph al itis (BSE) water au th orities visited co nside red â&#x20AC;˘ m etal limits may be over-stringent; and salmo nell a. Consequently, research agricu ltural use to be an effective opti on work had foc used o n the sanitation sid e for management of bi osolids (Tabl e 1). â&#x20AC;˘ which organic contam.inants need to be of biosolids u se, p rima ri ly as a resul t Pasteu risation or stabili zation with lim e included in the guidelines; and

mace; The force In flow.

WASTEWATER

seemed to be the preferred processes, altho ugh biosolids composting was also popular. In bo th France and E ngland, farmers paid a nom.inal charge for biosolids, as the wa ter companies' view was that if it is provided free of charge, the customer will perceive it as waste. All the water companies visited aimed to encourage recycling of this valuable resource and they recogn ized that repeat business required a quality service. Thames Water provides a o ne- stop shop fo r the fa rmer customer to encourage biosolids use and Vivendi operates long-term regio nal arrangements with growers. The valu e of biosolids was dependent on many factors, and the aim of the water authorities was to ensure that biosolids use was a sustainable practice at the lowest overall cost. Gen erally, after approximately 10 years of marketing and use, demand fo r biosolids w as now stable at approximately 60% for agricultural use in both England and France. T he biggest threat to the market for agricultural use of biosolids seemed to be consumer and supermarket perception. W e understood that limited structured research had been undertaken to assess the public's perception. Economics

As the cost of landfill increases, the option of agricultural use becomes more attractive. For agricultural use, liquid sludge injection appeared cheaper at the sewage treatment plant end of the process, but transport and application costs were high. Such a practice was also higher risk than higher-grade biosolids. Incin eration could be used to provide heat and power, with approximately 1320% of the original solids requiring disposal or further development fo r beneficial markets. Some possible alternativ es fo r d isp osal or use o f th e incineration ash are in cement or fo r use as road bases. In Sw itzerland (extra visit by one author) biosolids were used as fuel for cement kilns and provided energy savings and n o waste (see below). U se in cement kilns may be the most economically viable alternative to agricultural use ofbi osolids, especially for those situations w here highly contaminated biosolids are deemed inappropriate for agricultural use. Participants also saw, at Vivendi Water (France), some research that was assessing the economics of biosolids hydrolysis (d.iscussed below ) being extended to sludge minimisation in activated sludge processes.

WATER NOVEMBER 2002

Table 2 . The safe sludge matrix (Anon 2001). Crop Group

Untreated sludges

Conventionally treated sludges (>99% path kill)

Enhanced treated sludges (>99.9999% path kill)

10 mth

Salads

X - 30mth harv.

harvest

Vegetables

X - 12mth harv.

interval

applies

Fruit

Horticulture

Combi nable and animal feed crops

--1

Grazed crops

X - 3 weeks harv. and no graze

Hay cro ps

Science

In France, there was wide variability in the arrangements and the const"raincs involved in the agricultural use of biosolids. To ensure th e long-te rm sustainability of agricultural use of biosolids the indusny was ve1y conscious that they needed to address both the environmental and consumer perception issues. The French Government and W ater Industry are putting considerable research effo rts into this area e.g. the French Government has allocated $1.6 million annually to agricultural research for biosolids use. The English Government is supporting their preference of using biosolids agriculturally with $2.1 million in government funding for research in the next 3 years. R esearch projects are focusing on risk assess m e nt of pathoge ns, r edu cing contaminant levels in sewage sludge, and pathways of heavy metals in sewage sludge and their effects. The overall aim was to ensure that appropriate controls are put in place to protect the environment and human and animal health. During the tour, we were left with the impression that on-going research will be undertaken to monitor new chemicals of concern, that could potentially be found in biosolids, and their regulatoty requirements determined.

Options for biosolids management viewed on the tour Agricultural Use of Biosolids

The enthusiasm of the French public for recycling was reflected in that approximately 60% of the biosolids produced by Vivendi W at er was b eing used in agriculture, with markets ranging fro m broad acre to intensive horticulture. O ne of the potential barriers for agricultural use of biosolids seemed to be the public perception of the risks ofbiosolids use. Similar enthusiasm fo r recycling was evident in the UK, where approximately 1.1 million tonnes dry solids of sew age

3 weeks harv. and no graze

sludge is produced in the UK annually. Of this, 0 .6 million tonnes (55%) was recycled to agriculture; 0 .17 millio n tonnes (15%) was used for land-fill and land reclamation; 0.2 3 million tonnes (20%) incinerated and 0 .1 million tonnes was n ot defined (10%). The limiting factor for agricultural use ofbiosolids in both countries was usually the nitrogen concentration, and excessive conce ntrations potentially leading to contamination of groundw aters. In the UK a safe sludge matrix (SSM) had been develop ed as a result of a lack of regulatio n fo r pathogens, a concern of the perceived risk and quantification of the actual risk (T able 2) . Even tho ugh the actual risk involved with growing crops , with biosolids was considered vety small, after experiences with BSE and genetically modifi ed food scares, Sainsbury's (a maj o r supermarket chain in the UK) wanted to be able to provide the consumer with a process they and Sainsbury's perceived as safe . Sainsbmy's have accepted the content of the SSM and are supporting the sale of produce grown in soils w here biosolids have been applied. Application of biosolids to land can be by : a) Injection

In the UK, liquid sludges were approximately 5-6% solid when inj ected into the soil. Crops grown using raw sludge were only indust1ial crops, like oil canola (glossy m agazine produ ction , glad wra p) . Digested sludge was usually applied around 2001113 / ha to 260 m 3 / ha on newly treated soil with an 18 months interval of appli cation befo re grow ing food crops (e.g. oilseed rape this year and w heat in the following years). As application was year-round (when not too wet), tractors with tracks were used and heavy tanks of liquid sludge were not carried on the inj ection equipment, but a 400111 long hose connected to a stationaty tank was

WASTEWATER

used to pump biosolids to th e inj ection equipment. b) Aereal spread dried and/ or wet biosolids T erra Ec osystem s, the agriculture reuse company o f Tham es W ater, had 2500 fa rmer custo mers, they treated 15 ,0 00 ha of land annu all y w it h 455,000m 3 o fbiosolids cake and 700,000 111 3 of liquid sludge (5-6% dry solid). Biosolids were usually applied ] yea r in 4, at relatively high application rates. Th e types o f sludge applied depended on th e quality of the biosolid, soil, cartage, topography, etc . The major crops grown in the UK were indust1ial crops (oil seed), cereals and fo dder.

Crops grow n with biosolids in France w ere typically corn and sunflo wers. Biosolids were not used on vines as the wine industry was very sensitive to the m ethod o f grape produ ction (e.g. region, so il type, etc) and they believed the market would not look upon biosolids use fav o urably. H owever, it was acceptable to use biosolids as a pre-planting fertiliser for the establishm ent of a vineyard . R esearch was currently underway to add ress some of the wine consumer perceptions. Both England and France have fairly densely populated agricultural areas where their biosolids are applied. Consequently, o ne of the biggest diffi culties with agricultural use of biosolids has been the odour released , w hen in close proximity to housing, from stockpiling on individual fa rms and during applicatio n. Incineration At Colombe, on the outskirts of Paris, primary sludge and thickened waste activated sludge were fed to centrifu ges, achieving a dewatered sludge cake of approximately 30%T S (total solids). Some of this sludge w as lime treated and used in agriculture, but the majority (approximately 90%) was fed to a fluidised sand-bed incinerator. Ash from the incineration process was recycled in road engin eering and cement production . Exhaust gases were extensively treated to comply with strict emission limits. Part of the energy produced in the incinerator w as recycled in the combustion process to incinerate the sludge w ithout necessitating additional fu el. Until 5 years ago sludge produced at the Beckton and Crossness treatment plants near London was anaerobically digested, dew atered and then dumped at sea, via barges. However, following a decision to ab andon sea dumping, digesters at both plants w ere decommis-

sio n e d an d in cin e r at o rs i nstall ed. C urrently, raw sludge is m ec hanically dewatered prior to incineration , using filter presses at Beckton and cen trifuges at Crossness. Filter pressed sludge from Beckto n was typically in th e ra nge 30 to 32%T S, howeve r t he cen tri fu ges at C rossness pro du ced a slightly thicker sludge (3 1 to 34%T S ) and a more co nsistent produ ct. Fluidised sand- bed incin erato rs were used at both plants and natural gas provided supplementary fuel fo r combustion. Ex haust gases w ere treated to rem ove particulates, dioxins and heavy m etals, and concen trations of carbon dioxide and sulphur dioxide w ere also reduced. E xcess heat from the incineration process was used for on-site power generation, via turbines, and the recovered energy provided approx imately 50% o f th e power de m and for the sewage treatment plant. Incineratio n generates some 13- 20%. of the d1y biosolids w eight as an ash . T his is am enable for use in cement or as a road base. In th e UK and France the developm ent of this use seem ed to be in its infancy and most incineration residuals

were still being transported to landfill. For example, ash fro m the London incinerators was being disposed to a landfill; however, th e plant operators were in the process o f seeki ng approval to recycle it in b1ick making and aggregate p roduction. Cement Production

Several cem ent works in Switzerland used d ried and gran ulated bio solids as a part o f their fue l source and silica input . Altho ugh th ere were diffi culties in using biosolids in the kilning process, th e benefi ts of the biosolid's calo1i fic value and silica content made their use econom.ically attractive. Wet Air Oxidation

The tour visited a large pilot scale sludge trea tment plant at Toulo use (south of France) , using a wet air oxidation process called ATH OS. This plant had been in op eratio n for abou t 1 year. T he ATH O S process pro vid es low-temp oxidation of raw sludge and involved the follow ing stages: • initial thickening of raw sludge to about 4%T S;

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• preheating of th ickened sludge to approximately 235°C and then addition, with oxygen, to a pressurised plug flo w reactor (app rox 50 bar) for between 30 to 120 1ninutes; • cooling of treated sludge and then dewatering; and • treatment of flue gases before release to atmosphere. Outputs from th e process were: • inert sludge that can easily be dewatered to about 55%TS (with out the need for polyelectrolyte) and then disposed to a landfill or used in construction materials or civil works; • exhaust gases that are simple to treat as they contain mostly water, carbon dioxide and nitrogen; and • a liquid that can be recycled to a treatment plant for furthe r biological treatm ent. The process can achieve 50 to 95% COD reduction, 10 to 20% nitrogen reduction and is largely self sufficient from an energy point of view, with external fuel

only required for preheating of the sludge on start up. Compared to incineration: costs were similar; it was more compact; it offered simpler fl ue gas treatm ent; and had lower energy requirements. Thermal Hydrolysis

A large pilot scale thermal hydrolysis plant (CAMBI) was visited at Cherney in the UK. This plant has been in operation for about 3 years and was being used to treat sludges from nearby wastewater plants. The CAMBI process essentially involved the oxidation of sludge under elevated temperatures (typically 160°C) and pressures (7 bar). Under these conditions, pathogens were destroyed and cell structures in the sludge broken down, releasing energy rich compounds, which dissolved in water. Odorous gases are also produced and require treatment before release to the atmosphere. Sludge from this process, w hen fed to an anaerobic digester, readily breaks down, resulting in a high volatile solids

destruction (approx 65%) and significant biogas production (up to 50% more than from conventional anaerobic treatment). The CAMBI process offered several benefits, including: • production of a Class A quality sludge for agricultural use (6 log pathogen reduction); • production of a highly stabilised sludge with significantly increased biogas yields; • ability to treat difficult sludges; • final product easier to dewater; • enhances existing digester capacity; • easy to integrate within existing treatment plants. Thermal hydrolysis was being extended to sludge minimisation in activated sludge processes in research being undertaken at Vivendi Water in France. This developmental work involves applying the techniques of Wet Air Oxidation/ Thermal H ydrolysis to sludge minimisation, rather than sludge treatment, to improve the cost effectiveness of sludge management programs.

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Enhanced Anaerobic Digestion The group also received a presentation on research bei ng undertaken in the UK to investigate and develop en hanced anaerobic sludge digestion p rocesses, such as: (a) Temperarnre Phased Anaerobic Digestion (TPAD) which involved a short duration (2 to 3 days) thermoph ilic digestion phase (55°C), followed by a long duration (abo ut 10 days) m esophi lic digestion stage (35°C). Be nefits of this process we re hi gh volat il e solids destru ction ( up to 65%), high bio-gas yields and high pathogen destruction (approximately 6 log). b) Acid/Gas Phase D igestion which involved a short duration (2 to 3 days) med ium temperature (32°C) digestion phase, co ndu cive to the production of high concentrations of vola tile acids, fo ll owed by a long duration (about 10 days) med i um temperature (35°C) digestion phase, conducive to the formation of methane generati ng bacteria. Benefits of th is process were high volatile sol ids destru ction (up to 60%) and high biogas production. This process achieved about a 2 log pathogen destruction. Composting Two composting facilities were visited, one at Dune (southern France) and the oth e r at Li ttle Marlow Waste Water Treatment Plant in th e UK. The facility at Dun e was an open- air faci lity, located in a rural area and involved use of static piles. Dewatered biosolids ( 15 to 25%TS) were blended with wood c hips, green waste or corn waste and aerated under positive pressure via venti lation pipes beneath the piles. T he fi nal prod uct was sold for agricultural use in co rn and sunflower crops. Th e faci lity at Littl e Marlow was a stati c bay composting facility contained with in a bui lding to redu ce odour impacts on the nearby commun ity. Wood chips were used as the bulking agent and carbon so urce , and the final product was a bagged compost (also mixed with greenwaste compost and coconut husks), marketed to the garden and landscaping industry . The product was seen to have a signifi cant mark etin g advantage over its main com petitors in that it was peat-free and the Safeway supe rmarket chain wants to be peat-free in years to come. Peat-free is a marketing advantage, as peat harvesting for co mpost

is damaging bird habitats and degrading the environment. It is worth noting that it is getting more difficu lt to obtain a composting licence within the UK, owing to concerns assoc iate d with odours an d truck movements. Biosolids as an Energy Source: Heat;Power Generation and Methane Production As noted above, excess heat from the incineration of sl udge ca n be used to produce steam for elec tri city generation. The two largest wastewater plants in London have recentl y been converted to this process. Many treatment plants throughout the world anaerobically digest their sludge, producing methane to generate power via gas engines or turbines. T he increased cost of power and in creased interes t in renewab le ene rgy sou rces is making this approach more attractive to water authorities. Furthermore, processes that improve the efficiency of digestion and provide higher biogas yields, such as CAMB I, TPAD and A/GPD, are also gaini ng interest. D irect use of sludge fo r energy, as in the oil-from-sl udge process, was not encountered.

The future for biosolids use From the peop le and pla ces visited du ring the tour, it seemed that biosolids management in the UK and France was under pressu res from social perceptions, environme ntal responsibilities and regulators . At present, agric ultural use of biosolids was the most popular option for biosolids managem ent, yet the industry and regulators are continually refini ng these options. In so me cases, agricultural use is impractical or impossible, and other optio ns will always be required, especially if con tami nants entering the influent sewage stream cannot be decreased. It is interesting that many of the same pressu res exist in Australia, for example: • transport issues, such as noise and dust and a desire t o minimi se truck movements, • issu es of business, regulato r and public perceptions impacting on the business, • regulations being constantl y tigh tened requiri ng capital improvements and process innovation. Clearly, there were a wide-range of option s avai lab le for b i osoli d s

managem ent and Australia will see significant technological changes in the future in this area, in parallel with increasing land application to meet the requirem ents of regulators and society's desire to recycle, reduce and reuse residuals.

Disclaimer The information supp li ed in this report is a summary of information provided by Vivendi, Thames Water and range of priv ate and gove rn men t emp loyees from Australia, England, France and Switzerland. The authors have written this report in good faith as a summary of their experience on the tour. H owever, this does not necessarily mean they support any process or concept descri bed with in this report.

Acknowledgements T he tou r was coordin ated by ARRIS Pty Ltd and CS IR.O Land and Water, and sponsored by United Water, Vivendi Water and Thames Water.

Reference Anon. 2001. T he Safe Sludge Matrix . Guidelines for the Application of Sewage Sludge to Agricultural Land. British Retail Consortium. Water UK. Agricultural, Development and Advisory Service. www.adas.co. u k/ matrix

The Authors Jim Kelly is a Senior T echn ical Assistant with Adelaide University and c urren tl y spec iali zes in the susta inabl e agricultural use of water reclaimed from sewage treatment works. Dr Daryl Stevens is a Research Scientist for CSIRO Land and Water, base d in Ade laide, an d c urre ntl y specia lizes in providing the science to u nderpi n the sustainable agricultural reuse of by-products from the water treatme nt industry (solid and liquid). Emai l Daryl.Stevens@csiro.au Cliff Liston is the Manager W astewater Operations in the Con tract Operations Group of SA Water. His primaty role is to manage the wastewater trea t ment/ n e t works operatio n s and mainte nance aspects of the Adelaide Water Contract let to U nited Water. Dr Darren Oemcke is the R esearc h and Development Manager at United Water International. He is responsible for a research program that ranges from th e treatment of water and maintenance of q u ality in distribu ti on systems to wastewater treatment and residuals reu se. WATER NOVEMBER 2002

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ROBUST SEPARATION Of INTERESTS M D Young, J C McColl Abstract This paper is presented for the purpose of stimulating discussion on the vexed question of 'water righcs'. It is a search for a generic framework to simplify registration and trading of interests in natural resources. We seek a robust way to define interests in water and other natural resources. To this end, we seek comments and feedback . Comments should be sent to Mike.Young@csiro.au or Jim.McColl@csiro.au. We can be contacted by phone on 08-8303 8665.

We foc us on the notion of"interescs" in natural resources, and obligations associated with use. We search for a generic robust approach to the definition of interests, rights and use obligations that sits comfortably' within an economically efficient trading system. Pricing and charging issues and the question of how to convert from existing systems to the proposed o ne are left for subsequent reports.

Dedication This report is dedicated to five people. • Sir Robert Torrens and Ulrich Hubbe; and • Lord Sherbrook, Robert Lowe and Lord Bramwell. The first two of these people developed the Torrens Title Property Title registration system chat dramatically simplified and improved dealings in land around the world. It was based on a system used in the nineteenth centu ry to register ships in Germany. The Torrens Title Act was passed by the South Australian Parliament in

The second three of these people developed the idea of a limited liability share company. The Companies A ct was passed by the British Parliament in 1862. The practical bottom line solution was si mple - add "Limited" to the end of a Company name. Both ideas established new legal concepts and precedents. Both radically changed the grounds for dispute and dramatically reduced transaction costs. Both are built upon foundation concepts that have stood the test of time. This report begins the search for a new non-controversial way to define and trade interests in water and other natural resources.

Two key elements of the COAG reform process are: first, a commitment to separate interests in lan d from interests in water; and second, to improve pricing arrangements. We leave water-pricing considerations, including the effects of inconsistent pricing arrangements on trade, to other reports. Nevertheless, it needs to be recognised that inconsistent pricing arrangements, inconsistent use conditions and inconsistent approaches to enforcement distort trade and discourage econom ically efficient resource use. While the separation of interests in water from interests in land has facilitated the emergence of new markets for water resources, a major debate has been ge nerated about water allocation, river flows, water trading, the environment and compensation. W e note also that the ex isting plethora of water allocation systems have been derived piecemeal over time and have not been built for trading - in effect, trading has been "bolted on" . As a general rule separation enables resources to be used in a more econom.ically efficient manner. The separation of water from land is the first step and to varying degrees is being ac hieved. We pursue the second step - specification of interescs in water into a system that should prove robust and stand the test o f time .

Introduction This report is about the search for an economica lly efficient an d equitable system of defining, allocating, and managing use of natural resources that proves to be robust. Robust in the sense that the fundamental principles and founda tions upon which it is based remains unchanged over time.

A robust system A robust system would need to faci litate : • R esolution of resource allocation between consu mptive use and the environment, among consumptive users, and of issues related to distribution and use; • Secure, economically efficient and low cost trad ing and administration;

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• Assignment of risks making it clear where responsibility lies, under what circumstances compensation is due, and specifying the processes for obtaining redress; • Management of externalities associated with use - the interests of third parties, future generations and the environment - with minimu1n controversy. A robust system also must pass the conventional tests of efficiency and fairness in a changing world. For this to occur, the system must be built on a solid conceptual foundation. In the search for insights as to how to do build a robust system, we have cast our net wide. The search • From the limited liability share company structure we have - interests expressed in proportional terms (shares), the use of accou nting systems to dete rmine how much "profit" is available for use by others and, also, the notion of managing dividends sepa rately from shares. • From the Torrens Title system comes - guaranteed recording of all interests on a register, fo rmal settlement procedures, and irreversibility of ma rket transactions. • From the banking and fi nance system we get - internet debit and cred it accounting systems, exchange rates and associated formal transaction mechanisms. • From other sou rces, we identify - the definition of risks and responsibilities, and the definition of conditions and obligations to third parties. Over time, robust systems are characterised by the use of separate instruments for each distinguishable component. Separation From this search, we observe that separation of the interests into their component parts facilitates the development of more economically efficient management and accounting systems. This provides for adjustment of part of the system without having to deal with the whole system, and reduces transaction costs. Risk management is more economically efficient when each type of risk is defined and assigned separately.

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Definitions of the interest For each dimension of a tradeable resource allocation system that needs to be managed, we propose separation. Essentially, an interest in any common pool resource, like a quantity of water, can be considered as having three key components: • The entitlement - the long-term interest (share) in a varying strea m of p eriodic allocations; • Allocations - a unit of op portunity (usually a volume) as distributed periodically; and • T h e use licence - permission to use all ocations with pre-specified use conditions and obligations to third parties. In a separated system, each component can be managed independently without consideration of w hat is happening to the other component. Entitlements define eq uity among those with interests in the resource, allocations define the periodic quantity that may be extracted from the common pool or sold, and the use licence defi nes the site-specific conditions pertaining to use incl uding limits on the degree co which users, by choice of practice, are allowed to cha nge the en vironment. In areas or systems where use may cause adverse impacts like salinity, the use licence should be expressed in a manner that enables a separate entitl ement/ a!Jocation system to be set up to manage that issue. Si m ilarly, the entitl em en t shou ld be d rafted in a man ner that enabl es chann el congestion to be devolved to a separate entitlement/a!Jocacion system. T he system we summarise applies, with m inor variation, to all water resource systems - regulated and unregu lated , surface and ground . Altho u gh no t expla ined in th is report, we suspect that it is appli cable to many other common pool resources.

• The extent of the area and resource over which risks associated with the entitlement are pooled; • H ow allocative risks are distributed between enti tlement holders and the government; and • The effects ofland use changes on future allocations. Essentially, if both priority and risk are managed at the en titlement level, then trading of allocations can be relatively unconstrained and exposed to market fo rces. Provided, of course, that externalities resulting from the use of the resou rce are managed via a separate use licence. Attention needs to be given co the size of the common pool. Within the pool there is little opportunity for arbitrage. Entitlement conversion from one part of the system to another requires an exchange rate to be sec. At every exchange poin t opportunity for arbitrage is created. ln short, the greater the extent of spatial coverage, the less the opportu nity fo r exchange rate specu lation and market manipulation by those who have access co privileged information . Priority and Reliability

Classically, States have developed high and genera l sec uri ty syste m s. T h e

entitlement embodied in each licence is defined by reference to a volum e and statement abou t the probability that that volume will be delivered. Implicit in the licence is an un-stated assumption that all people who hold the same type ofl icence will receive identical opportunities per unit of volume. W henever there is more than one entitlement class, typically allocations are made in order of priority or preference. Consequen tly, we conclude that th e entitlement should be formally described as a share. P riority relates to the reli ability of the allocati on stream over time. Often discussions foc us on the number of years in a hundred chat periodic allocations will exceed the specified q uantity. U sing the share approach, this would be handled by issuing different classes of entitlemen t shares. If on ly one class of share is issued, then the level of individual risk can be managed through investment or trading. Allocations An allocation is a unit of opportu nity that is known to exist in the common pool. Consisten t w ith trading rules and charges, the unit may be traded. It may also be used

The entitlement T h e m ost valuable comp onent is the entitlement - the long- term interest in a stream of allocations that occur from time to time. Entit l eme nt s are gra n t e d by government. They define the degree of access to the resource that can be expected over time and the nature of changes, if any, chat ca n be expected. In defining the entitlement, five considerations are important: • W hat priority, if any, is given to en titlement holders when the available resource is distributed and how reliable or variable access is likely to be; • T he nature of the periodic allocations to be expected; WATER NOVEMBER 200 2

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Table 1. Assignment of Risk Financial risk incomplet ely specified or shared

Financial risk of change met entirely by ent itlement holder (Adaptive Risk)

Compensation claim may be made against administering agency

Natural variations in periodic allocations (eg. seasonal fluctuations)

Administrative error associated with a t ransaction. An adjustment j udged by the courts to be capricious.

Change in mean ann ual rainfall (eg. effect of cli mate change)

Issuance of new entitlement s once the system is known to be fully allocated.

Revised estimate of the capacity of the resource that are t he result of an adaptive process (eg. improved scient ific knowledge - adaptive management, proper process, relatively small changes over time)

Rapi d and unexpected admin istrative change resu lt ing in a sudden and significant reduction in the va lue of share entitlementsbl_

( Duty of care in managing the interests of all parties )

(Uncertainty)

Catastro phes such as the failure of a dam.

Land-use changeâ&#x20AC;˘l (eg . pastu res replaced by forestry) a) For significant land-use changes, it is possible to require that any negative impacts of land-use change be offset via the purchase and surrender of an entitlement equivalent to the size of the expected impact. Similarly, it is ppssible to allow issuance of entitlement shares when land-use change results in a positive contribution . b) For example, resulting from initial over-commitment and failure to allocate in a precautionary manner.

but only in a way co nsistent with the conditions and th ird party obligations on a use licence. W hen used or at the en d of the p eriod , th e unit o f allocation is extinguished. Under some system s, a co nsiderable proportion of an unused allocation can be carried forward . In other system s,

storage without substantial loss is impossible. Ca reful considera ti on of the incentives associated with the carry fo rward ve rsus partial or total extinguishment issue is necessary. At the start of eac h period, once th e quantity p er entitlem ent to be allocated has been determin ed, w hether derived

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from high or general security entitlem ents, trading can take place by volu me alone. Allocations should be managed like bank accounts with d ebits, credits and balances. By separating trading issues from use issues, trading costs can be kept low . Allocation trades are p ermanent in the sense that, once completed , they can not be undon e. Multipl e trades, including trade back to the original so urce, are possible. Return flows

Although periodic allo cations vary over time , an important question is that of whether the interest to be traded is expressed in "gross" (volume pumped) or " n e t " (volume co n sum e d). Th e difference between gross and net reflec ts the effects that water-use efficiency has on th e vo lume of water returned to the system fo r use by others. This issue is controve rsial in Au stralia but well accepted in the U nited States. If a person pumps 1,000 ML at 50% water use efficien cy, 500 M L returns back to the system for use by others. If the path way is through groundwater the effect can be delayed. U ltimately, if th is 1,000 M L is sold to a highly efficient system (say 90%), an extra 400 ML is removed from the system. One irrigator gains at the expense of all others. Two approa ches are possible, either the su m of gross en titlements shoul d never be al.lowed to exceed the cap or, alternatively, o nly that which has bee n consumed may be traded. R eal gains from tr ad e o cc u r o n ly when th e re is im provement in n et use. If trading in gross entitlements is allowed , in a fu ll y al.loca ted system wh ere tech nical water

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use efficiency is low, the system will in evitably become over allocated as irri gators improve efficiency. This situ ation can be addressed by across-the board proportional reductions in periodic allocations per share or defining and managing the interest and allocations as "net". On the other hand, there are systems where "gross" is close to "net", with little or no return flow. When cost or technology limitations, prevent direct m easu rement of net use eith er an attempt should be made to deem the extent of net use or entitlements should specifically make it clear that as net use increases gross allocati ons wi ll be cut on a one fo r one basis. A reduction in return flows ca n also cause an increase in river salinity (dilution effect) . As indicated earlier, for a robust solution to the allocation problem, it is necessaiy also to manage salinity and other water quality issues separately from the management of volume. Assigning Risk If fully specified, the risk of change in entitlements and allocatio ns needs to be pa rtitioned between the holders and the government.

Summarised below in tabular format is a framework for risk assignment. The table suggests a way to partition risks into those m et by entitlement holders, those w he re compensation claims can be made, and th ose unspecified. Compensation would be payable only when risk turns to reality and only in circumsta nces chat m ig ht, in retrospect, be reasonably described as failure by the admin istrative agency to exercise adequate duty of ca re or diligence in managing the interests of all parties. Compensation or structu ral assistance co uld be payable also in cases when there is a sudden and dramatic change in policy direction. We recognise, however, that opinions va1y on the need and case for compensation. Our point is that, for efficient outcomes, it is necessa1y co specify the position taken in a transparent manner. Registration and trading

The T orrens Title experience clearly shows that by defining legal ownership through a register and guaranteeing its integrity, the risks of fraud and the cost of negotiating a trade are considerably lower. Registration of third-party interests (mortgages) lowers the cost of credit significantly. Licensing of brokers and development of fo rmal settlem ent procedures lowers transaction costs. C lear trading rules including exchange races sho uld b e establish ed . Once executed, a trade is complete.

There should be separate registers for entitlements and accounts for allocations. State of the art accounting systems can be used to record transactions. Electronic trading should be possible for allocations. The Use Licence The holding of entitlements (shares) or even the ho ldin g of a di stributed allocation of themselves provides no permission to use the resource. While either of these components are fully tradeable , co use an allocated resource, a thi rd co mponent is requ ired. This we have labelled earlier - the use licence. Typi cally, a use licence would state conditions of use and obligations to third parties. The total volume of water that may be applied would be stated as an upper limit. For example, a li ce nce may authorise flood irrigation over say, 350 hectares at a specific location. Conditions of use These arise with specific use of an allocati on and should reflect the requirem en ts of a statutory managem ent plan . They may include pu mping linties and drainage disposal requirements, possibly certa in restrictions on pra cti ce, and reporting requ irem ents.

Third-party obligations

Third-party impacts atise from resource use not the action o f holding an entitlement or allocation. T he bottomlin e statement of obligations should indicate the maximum degree of impact on oth ers chat is allowable. For example, it may reserve the righ t to pollu te to the state and indicate that the user may be obliged to rectify damages imposed on others and o r the environment. M anagement planning processes could be used to signal when and to what extent obligations may be allowed to accumulate. To th is end, management plans need to be statutmy instruments that have standing in law. T hi rd party obligations would also be consistent with any district or regional salinity management strategy, and may possibly be met wholly or partly through the use of market based instruments (eg. sa lini ty credits). Legislation A related issue is the need fo r legislation co implem ent a separated right sys tem. Legis lation fa c ilitates and encourages consistency in approach. In som.e states , existing arrangements and reforms underway mean that few amend-

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ments would be necessary to move to the proposed system. In other States significant changes are necessary.

Other critical implem entation issues to be explored centre around questions about:

Implementation issues There are a number of important implementation issues tha t require addressing. Th e most topical of these is the issue of how to define t h e environment's interest so that its effect on the interests of consumptive users is full y understood and accepted. T he environ ment's interest can be defined as being either: • prior to those of consumptive users; or • equ ivalent and, hence, defi ned so that trade b etween envi r onm.ent a nd consumptive use is possible. Under the "prior" model, all risk of change in the expected stream of allocations due to alteration in communiry env ironme ntal valu es is b orn by entitlement holders. Under the "equivalent" model, risk is shifted to society and change, if not executed via a market transaction, would be com p e n sa bl e . Entitlem ent values will be higher under the equivalent model than under the prior model. Careful, examination of these two alternative models and variants of tben-i is necessary. If the environment's interest is managed under the "equivalent" model, very careful consideration bas to be given to th e way periodic allocations would be managed and accounted fo r. Conceptually, it is possible to make a base allocation to the environment under prior rules and then manage the residual under the equivalent model.

Definition, Planning and Management and, in particular: • Identifying the most appropriate spatial extent of each entitlement - a Basin, a catchment, a valley or a reach - with close consideration of the arbitrage and risks har i ng op portuniti es differ e nt arrangements set up; • Determining the pros and cons of having a single entitlement versus one where there are two, three or more classes of shares; • Determining bow the separated system can be linked seamlessly to licences for overland flows, farm dams and unregulated streams; • Determining the most approp riate planning and management structure. Trading and dealing and, in particular: • Determining what charging and pricing arrangements should apply; • Establishing a bank-like trading system for allocations; • D etermining the extent to which interdependent entitlements can be exchanged for one another - surface water for groundwater; • Detennining how to manage simply the return flow or "gross" versus "net" issue; • Determining the nature of periodic allocations, time until extinguishment and ways to define return flows; • Determining whether or not allocations should be managed at the same or a different scale to entitlements.

The interaction between ecosystems, vegetation and groundwater is crucial to the maintenance of environmental health. UTS, in conj unction with the National Centre for Groundwater Management, offers the postgraduate degree Ecology and Groundwater Studies at Masters, Graduate Diploma and Graduate Certifica te levels. The course provides the knowl edge and awareness necessary to maintain the health of our na tural resource systems, particularly the relationship between groundwater and ecology.

WATER NOVEMBER 2002

Conversion : • Determining what principles and processes should be used in the conversion to a separated system; • Determining how to convert the lice nces in any specific area to the new separated system.

Concluding comment While some may disagree, we consider all the above, including the question of how to define and manage environmental flows as second order issues that need to be considered after a robust foundation is in place. Consequently, we perceive that the next steps involve careful exploration and consideration of the separated system proposed in this report followed by a series of reports o n each of the issues listed above: Options for definition of the environment's interest; integrated planning and management of the resource; trading and registration arrangements; use licence specification; and con version principles and processes. Finally, as stated at the start of this report, we seek a robust way to define interests in water and other natural resources. To this end , we seek comments and feedback. This paper is derived from the Executive Summary of a 47 page report, released in September 2002. The full report is available on the following website http: / / www.clw.csiro.au / The trans-disciplinary structure of this new publications/ consultancy /2002/ course bri ngs together science, engineering and management to focus on solutions. Ro bust_Separation.pdf Teaching emphasis is on flexible learning with most subjects ava ilable in distance mode. More information is available by contacting Prof Michael Knight or Dr Brad Murray.

think.change.do. 02 95141984 or 02 951 4 4075 Email: groundwater.management@uts.edu.au Website: http:/ /www.science.uts.edu.au/des/ Environmental_Management_ Masters.html LITS CR ICOS Provider Code 00099F TUT1626

Use licence specification and, in particular: • Determ.ining how to specify third-parry obligations and organising them so that they can be separated from the use licence and, issues like salinity and channel flow capacity, managed in an independent trading environment. • D etermining what needs to be included in a use licence and what is best left in a management plan and how the tvvo should interact; • Determ.ining how use licence conditions can be reviewed and the best processes used to change them.

The Authors Professor Mike Young is Director, and Jim McColl is Visiting Fello w at CS IRO Land and Wa t er, P o li cy and Economic Research Unit, Tel 08-8303.8665. Email Mi ke. Young @cs iro .au or Jim.McColl@csiro.au .