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Volume 29 No 8 December 2002 Journal of the Australian Water Association

Editorial Board F R Bishop , Chairm an 13 N Anderson, l"l.. Considine, W J D u lfcr, G Finke, G Finlayson, G A H o lder, B Labza, M Muntisov, P Nadebaum, J D Park er, J Rissm an, F R.oddick, G R. yan, S Gray

CONTENTS

•, W ater is a refereed journal. This symbol indicates that a paper has been refereed.

Submissions

OPINION

Instructio n s for authors can be found on page 3 of this journal. Submissions accepted at: www.awa.asn.au/publications/

2

Managing Editor

Membership • The Nub; WaterAid in the International Year of Fresh Water; Aquaphemera; National Priorities; Our Point of View • Biomonitoring: Not Just a Financial Decision; The Salinity Rap

Peter Stirling

News and Supervising Editor

ASSOCIATION ACTIVITIES

Brian McRae

9

AW A Technical Director Tel: (02) 94 13 1288 Fax: (02) 9413 I 047 Email: b111crae@awa.asn.au

Including AIWA and WEF Reports

PROFESSIONAL DEVELOPMENT

Technical Editor

13

EA (Bob) Swin ton 4 Pleasant View Crcs, Wheelers Hill Vic 3150 Tel/Fax (03) 9560 4752

NEWS BYTES

Email: bswinton@bigpond.net.au

14

Water Production Hallmark Editions PO l3ox 84, Hampton, Vic 3188 Level I, 99 Bay Street, l3righcon, Vic 3186 Tel (03) 9530 8900 Fax (03) 9530 89 11 Email: hallmark@halledit.com.au

Graphic design: Mitzi Mann

18

National Sales Manager: Brian Rault Tel (03) 9530 8900 Fax (03) 9530 891 J Mobile 0411 354 050

is published eight times a year in the months of February, March, May, June, August, September, November and December.

Australian Water Association PO Box 388, Artannon, NSW 1570 Tel +6129413 1288 Fax: (02) 94 13 1047 Email: info@awa.asn .au Al3N 78 096 035 773

Federal President Barry Norman

Executive Director C hris D avis

AWA

ifj

AUSTRA LI AN WATER ASSOCIATION

Australian Water Association (A WA) assumes no responsibility for opinions o r statements of facts expressed by contributors or advertisers.

Editorials do not necessarily represent official AWA policy. Advertisements are included as an information service to readers and are reviewed before publication co ensure relevance co the water environment and objectives of AW A. All material in Warer is copyright and should nor be reproduced wholly or in part without the written permission of the Managing Editor.

Subscriptions Water is sent to all AWA members eight rimes a year. It is also available via subscription.

The Future of Water; ABS Water Account; Pine Water National Safety Award

CONFERENCE REPORTS 20

Water (ISSN 0310 · 0367)

Featuring selected highlights from the AWA email News

CROSSCURRENT

Water Advertising

Email: brault@halledit.com.au

Details of courses, classes and other upcoming water events

Emergency Management Workshop for Utilities, C Davis Hazard Analysis and Critical Control Point (HACCP) Workshop, M Stevens Report on ISAR4, P Dillon

SPECIAL FEATURE CRC FOR FRESHWATER ECOLOGY 25

KEEPING A FOCUS ON FRESHWATER ECOLOGY An overview of the research program. G Jones

29

PROTECTING AUSTRALIA'S RIVERS: URBAN AND INLAND Urban land-use effects: Assessment of inland river condition.

A Milligan, C Wa lsh, R Norris, P Liston. I Lawrence

33

USING ECOLOGICAL KNOWLEDGE TO UNDERPIN RIVER REHABILITATION How flows affect ecology: The importance of 'debris'.

P Collingha m, S Bunn, G Quinn,

38

THE IMPORTANCE OF BIODIVERSITY Assessment and understanding, then conservation. A Kot lash

WASTEWATER 40

•, BIOSOLIDS TO LAND: INTERNATIONAL REGULATIONS - PART 1 A survey of regulations for inorganic and organic contaminants.

47

H Reid

" OPTIMISING BIOLOGICAL NUTRIENT REMOVAL On-line nutrient instrumentation can achieve better effluent at lower cost. P Mossc

Visit the Austrahan Water As oc1at1on

HOME PAGE and access news. calendars, bookshop and over 100 pages of information at

OUR COVER: A dry spell i11 tl,e Barmal,-Millell'a Forest 011 rl,e River Murray. Tl,e ivork of the CR Cfor Fresl,111ater Ecology is sl,ou1i11g l,0111, e11e11 111ith little 111ater, Australia's 111etla11rfs a11rf rivers can be /,ea/thy. Photo by A11drew Tatuell.

WATER DECEMBER 2002

1

FROM

THE

PRESIDENT

MEMBERSHIP - THE NUB After decades of gratifying growth, AWA hit a plateau recently, which saw membership, having surpassed 4,000, fall back below that number. Various reasons have been advanced to explain that loss of impetus, and many are plausible, but the fact is, we depend on membership numbers for credibility, for revenue and for economies of scale. For all those reasons, w e could not afford to take this lying down.

An internal report was prepared, then put to external consultants for review.

Some straightforward advice was received, th e core message from which was - get_ out and sell membership much better than you have been doing. Clearly, we'd fallen into the trap of servicing current members well and hoping that word-of-mouth would bring fresh members in. That do es happen, but not fast enough to replace the members lost through down-sizing, changes in career path or retirement.

With the blessing of both the AWA Board members and, most importantly, Bran ch Presid e nts, a dete r mined membership sales campaign has been launched. Key to that is new staffer

Barry Norman

Michael Seller (no , we didn't change his name!) who will be doing the selling.

Current members have no doubt realised that their subscriptions are supporting the range of AW A activities, which benefit everyone in the water industry - so spreading membership shares the burden.

Success ,,,,.,,,,8 Partnership 1,

JWP / Advanced Water Treatment

As well as actively selling membership we will all be reminding members and non- members about the benefits of membership, which are probably taken fo r granted. AWA publishes the b est water journal, operates the best conferences and trade exhibitions, mounts the best web site and distributes the most effective weekly e-mail newsletter. As well, our Bookshop carries the w idest range of water titles and we offer the most cost-effective professional development opportunities.

All that, for little more than $100 per year is, in the jargon of marketing, a great value proposition, but we have to point that out. Of course, if members point that out to their friends and colleagues, the selling process will be more effective, the networking wi ll improve, and ou r influence will expand. So, Michael Seller's friendly presence will be felt around Australia as the growth campaign unfolds.

Co mpl eme ntin g our r enewed membership growth strategy will be a greater emphasis on special interest groups (S IGs), where members can network with people w hose interests align closely with their own. The idea is that the industry knowledge, the expertise and the passion will co me fro m th e SIG members, especially the convenors, w hile staff will pro vide the necessary administrative suppor t to make things h appe n .

Participants won't be w riting minutes or licking stamps, so they'll be free to tackle the big-picture stuff.

We believe that the combinatio n of local, branch activities, plus national services, mixed in with access to special interest groups, will be a winner.

Barry Norman

/ Biolog ical Nutrient Removal

water

/ Plant Auditing & Optimisation / Water Recycling / Infrastructure Planning & Modelling / Asset Solutions / Stra tegic Planning & Developer Charges

FUTURE MAJOR FEATURES Pumping, Pipelines, Instrumentation Deadline for papers November 29th Articles January 3rd

March

Fo r information , please co ntact : Selwyn Mcfaul in Brisba ne on

07 3244 9600 (s. mcfa ul@jwp.com.au) Gidi Azar in Syd ney on

02 9460 1855 (g.azar@jwp.com .au )

May Environmental Planning, Wastewater Treatment Deadline for papers January 3rd Articles February 28th

George Roufos in Melbourne on

03 9521 2922 (g .roufos@jwp.com .au)

John Wilson and Partnersâ&#x20AC;˘ www.jwp.com.au 2

WATER DECEMBER 2002

June Biosolids Deadline for papers February 28th Articles April 4th

CRC

FOR

FRESHWATER

ECOLOGY

COOPERATIVE RESEARCH CEr--.. TRE FOR

FRESHWATER ECOLOGY

KEEPING A FOCUS ON FRESHWATER ECOLOGY G Jones Knowledge is essential The C ooperative R esearch Centre fo r Fres hwater Ecolo gy (CR C FE) set o ut nine years ago to help improve the health o f Australi a's ri vers. In this tas k w e are beginning to be successful. Through ou r n ineteen research and industry-partners, and o ur researc h an d know led geexchange teams, we are seeing awareness raised at all levels o f go ve rnment and throughout the rural co mm uni ty . In spi te of severe drought, environmental flows are being planned and in some cases impl em ented in rivers that have been regulated by dammi ng o r d iversio ns. T he need to ensure ecological health in rivers and streams, upland and lowland, is now widely accepted.

B ut the work of restoring river health is just beginning. River managers and the comm unity across Australia are w illing, bu t they ne ed detailed q uanti tative knowledge as w ell as predictive tools for evaluating scenarios, at both small scale and at catchment and landscape scale. This is where the CRC FE continues to fo cus its efforts.

Kno wledge transfer - we prefer to see it as knowledge exchange between scientists and stakeholders - is central to our mission. W ith knowledge exchange staff now in Goo ndiwindi, Mildu ra, Sydney, M elbourne and C anberra , w e are linking our growing knowledge base with existing information regionally and in capital cities across the eastern states. By synthesising and delivering useful knowledge, we are helpi n g address the problems faced by industty and society w hen managing freshwater health. M inisters, agencies, the m edia and the community seek our advice on many existing issues, and we are in a special position to look ahead to the future of water reso urces and their health.

In its d riv e to p ro du ce u se ful knowledge, the C RCFE has a research po rtfolio that conta ins a mixture of long- term integrated field and labo ratory projects addressing strategic priorities, and short- tern, projects addressing im m ediate needs and kno wledge gaps. Several large m ulti -disc ipli na1y proj ects currencly form the co re o f the C RCFE 's researc h portfo lio . Probably on ly in a C ooperative R esearch C entre context can geomorp hologists fro m C anberra wo rk w ith invertebrate ecologists from Brisbane, fish ecologists from Mildura and chemists from M elbo urne on the same proj ect.

Th e C R.C FE r es ear ch po r t fo lio addresses five key natio nal issues: • the effects o f regulation o f ou r river systems, and the pressure fo r develop ment of currently unregulated water reso urces; • the serio us degradation of many of our urban and ru ral aquatic systems and the lack of knowledge abo ut ho w to rehabil itate them;

• the loss of ecosystems and bio diversity; • the lack o f d etailed informati on about the con ditio n (or health) of Australia's aquatic eco systems; • the lac k of fund am ental sc ientifi c u nderstanding of th e fun ct io ning o f Australian inland aquatic ecosystems, and how human actio ns affect bio logical commu nities and ecosystem processes.

Ou r research is managed throu gh fo ur research programs: A . Flow- related Ecological P rocesses (P rogram Leader: Assoc iate Professo r Geny Quinn , M o nash University) B . R e storation Ecology (Pro gra m Leader: Professor Stuart Bunn, Griffit h U niversity) C. Conse rvatio n Ecol ogy (Program Leader: Dr M argaret Brock, NSW Dept o f Land and W ater C onserva tion) D. Water Quali ty and Ecological Assessm ent (Program Leader: Assoc iate Professor R ichard N o rris, University of C anberra).

Flow-related ecological processes

Professor Gary Jones is the Chief Exec11ti11c ef the Cooperati11e Research Cellfref or Fresh111ater Ecology, a11d Prefessor of Freshwater Scie11ces at the U11i11ersity of Ca11berra .

H ow d o es flo w affec t ecological processes in rivers and their flo odplains?

Australia's rivers and wetlands occupy a huge diversity o f geograp hic and climatic co nditions, including the coastal frin ge and inland, summer and winter rainfall regions, and tem perate and arid zone systems. The flo w patterns in many of these systems are amo ng the m ost u npredictable in th e world, but regulation has resulted in many changes to their spatial and tempo ral patterns of flow. Al though we know that total flo ws in many regulated systems are reduced and seasonal flow patterns are often reversed or evened o ut, o ur u nderstanding of these effe cts of regula tio n o n rive r ecosystems is still limited.

WATER DECEMBER 2002

25

CRC

FOR

FRESHWATER

ECOLOGY PH OTO: ANTHONY SCOTT

On 22 November 2002, the Hume Dam was about 17% full. The CRCFE is devising principles for managing the ecology of water bodies during drought and will release them early in 2003.

Therefore w e are ex amining selected ecological p rocesses in river channels and their floodp lains and wetlands. Also we are continuing flow manipulation experiments in upland and lowland rivers, often interacting w ith the en vironmental flow allocation processes occurring in Victoria, N SW and Queensland.

As a result, the program is quantifying relati o nships betwee n different water release regimes and effects on target species or communiti es chosen to represent potential 'response' groups. T hese response groups are not only bio ta (e .g. fish, invert e bra t es, rip ari a n a nd fl oo dplain vegetation), but also ecological processes (e.g. fluxes of carbon and nutrients, nutri en t spiralling) and foo d web dynamics. The program is also challenging the traditio nal wisdom. that the floodplain is the m ain source o f carbon and bio ta fo r lowland rivers. In-c hannel processes and habitats (for fish recruitment, for instance) in the Murray, Ovens and Broken rivers seem to be much m ore impo rtant than previously tho ught.

w ill be resilient to natural disturbances.

C ase studies are being established with relevant managem ent groups as adaptive stream rehabilitatio n experiments. For exampl e, in a rece nt exp eriment in Vi ctoria, stru ctures made from red gum ha ve been installed on degraded streambeds, changing th e bed topograp hy by ge nerating scour p ools immediately downstream, as predi cted. T he structures themselves have been rapidly colonised by both algae and invertebrates, and native fish have shown a strong positive response.

R esults like these encourage us in our aim, namely that river restoration practice will become an important part o f total catchment m anagement.

T ypical qu es tion s aske d in th e restoration ecology program , then , are th ese: â&#x20AC;˘ Is it true that if you rebuild or rec reate physical habitat (the fo cus of much river

restoratio n actio n) then organisms will return and ecological co nditio n w ill improve' â&#x20AC;˘ Can aquatic plants and animals recolonise disturbed sites? Can they disperse from the refuge areas they o ccupy now , if any, and ho w fa r can they move' â&#x20AC;˘ Is it possible to resto re key ecosystem processes (such as primary production , nutrient cycling) without completely restoring all elem ents of the original biological cou1nmnities' Conservation ecology

Loss of biodiversity continues to be one of our mo st seri o us en v iro nmen tal concerns. Wh ether w e look at wetlands or salt marshes, mangroves or bushland , inland rivers or estuaries, the same story emerges. Degradation of habitat, the major source of bio diversity loss, is continuing at an alarming rate.

Restoration ecolog y

The recent Land and Water R esources Audit has painted a grim picture of the condition of our stream s and rivers.

Millio ns of dollars are being spent on restoration. Unfortunately, little of the past restoration effort has had a strong scientific base, an d few attempts have been made to measu re resulting enviro nmental b en e fits. Th e R es torati on Ecology Program of th e CRCFE is building our unde rstanding about th e ecological processes that underpin stream rehabilitation, so that disturbed stream ecosystems can be more easily restored , and so they 26

WATER DECEMBER 2002

The Cooper Creek floodplain becomes a slow-moving wetland during a flood.

CRC

FOR

The Conservation E cology Program is busy defini ng freshwater biodiversity. The program is addressing the qu estio ns: What do we have left? W hat can we do? ln Queensla nd , the Dryland R efugia proj ect is exam ining fragmentation and connec tivity of dryland ecosystems. In other wo rds, are waterholes effective as refugia for aquatic organisms in dryland river catchm ents? Large integrated data sets are now bei ng processed co answer th is qu estion.

A long-term bi odiversity mon itoring progra m is being set up for the Sydney Catchment Authority, to (a) measu re and assess fish, macroinvertebrate and riparian vegetatio n biodiversity; (b) identify locations of high conservation value based on their bi odi versity characteristics; and (c) m onjcor and assess biodiversity changes o ver ti me. In the rice-grow ing areas of so uth ern NSW and n orthern Vi ctoria, the relati onship between rice-farm ing and bio di versity is b eing stud ied at farm and regional scal es, and a new stu dy on cotton ring-tan ks is soon to commence (s p o n sor e d b y th e Co tt o n R ese ar c h a nd D e v elo p m e n t C orporation) in no rthern NSW.

FRESHWATER

ECOLOGY

co identi fy th e b est m ethod fo r eac h situ ation . T herefor e, several biological assessm e nt m e th od s are now be ing compared in situations of salin ity and sedimenta t ion g ra d ie nts, in th r ee geographi ca l regio ns. T h e se nsiti vities of b io logica l m eth ods in de tecting th e effects of different im pacts have not been thoroughly explored before.

A U SR IV AS and oth er b io logic al assessm ent methods dep end o n reference sites against w hich co assess th e condition of test sites. Som etim es, th e co mparison is hampered because appropriate reference sites canno t be fo und in regions that have been sign ificantly mo difi ed , incl uding

urban areas. T herefo re the Water Quality and Eco logica l Assess m en t rese arc h program has recently develo ped a new approach, using sites protected by good managen1ent practices co defi ne reference condition.

Past and future

So fa r, this overview has described only so m e of o u r curren t an d rece n tl y completed work. Over the last nine years, m uch has been ac hieved. T he C RCFE , under Professor Peter C ullen, had brought together partners from water agencies and industry during those critica l years in Australi a's fr es hwater histo ry. N o w,

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Water quality and ecological assessment O ur fourth program investigates water quality , in large urban and other in lan d areas. On the u rban front, the program is investigating processes that degrade urban s tr eams along a ru ral - u rb a n gradi ent, with p arti cular fo cus o n scormwater drainage infrastructure.

T h e r es u lti n g re lat i on ship s b etwee n ind icators o f condition and drainage conn ection provid e a lin k to the emerging field of w ater- sensitive urban design .

In both u rban and rural areas, river-managem ent agen cies are moving towards management for the sa ke o f river health, and th erefore they increasingly turn co biological assessm ent m ethods for m easurin g the effectiveness of their actions. T he CR..C FE has been pivotal in the development and adoption o f rapid techniques for biological assessm ent, p articula rly AU SR IVAS und e r the National R iver H ealth P rogra m .

H owever, it is not enough to have developed a m ethod and had it accepted . A p o werful cool like AUSR IVAS also n eeds testing in comparison with other techniques,

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CRC

FOR

h aving le d the C R..CFE s in ce its beginning, Peter has retired .

As the new C hief Exec utive, I ha ve asked th e CR..C FE to think about how w e do research, not just w hat we work o n. W e are en couraging ou r researchers to think at th e landscape scale and to d eve lop ca pabi liti es in ec ol o gi cal predictio n and in evaluating management scenarios. These tactical goals will be key drivers of the CR..C FE's research portfo lio fro m 2003 to 2006.

Ou r new thrusts are apparent in th e new research portfo li o th at will soon com.e inco force .

The Flow- related Eco logy program will be making m easurements during planned (' regulated') and natural flow events, and continuing in-channel manipulations of h ydraulic habitat in several rivers. Th e m easurem ents will provide data for developing quantitative empirical and m echanistic relationships betwee n flow regim.e, habitat and ecological response, at a range of spatial scales.

Statistical analyses of new and existing data wilJ test for quantitative relationships between flow, habitat and biotic response.

This program will have formal links with the C R C for C atchment H ydrology.

FRESHWATER

ECOLOGY

The R estoration Ecology group will be evaluating methods fo r rehab ilitatin g ri vers. The group will set up experiments to examin e the ecological constraints to successfu l river rehabilita tion proj ects and develop novel process-based techn iqu es fo r mo nitori ng ecosystem recovery.

T he group pla ns to loo k fo r large- co m e dium -scale gene ti c c onn ecti vity between river and floodplain plant and animal po pulations. N atural patterns of conn ecti vity found may guide restoration managem ent plans. P redicti ve ecologica l mo delling will also be a fo cus of this grou p, to simu late respo nses to distu rbances and potential management actions, and co optimise resou rce investment outcomes.

The Conservation program will be asking the question: H ow do aqua tic co mmunities respond to rising salinity ?

Initially, they will exam ine w etland biodiversity and ecological processes in saline situatio ns of varying intensity, analysing small-scale exp erimental manipulations and disturbed fi eld sites.

The stru cture and ecological pressures that influence or control aquatic biodiversity, in a water- body, catch ment or basin need to be identified. The group will be looking for the impacts of human

distu rbances on large-scale bi odiversity patterns, and m easuri ng the conse rvation value of individual water b odies fro m seve ral perspec tives.

C onservation Ecology is also th e program that w ill be responsible for modelling and predi ctin g the sprea d and establishment of potential in vasive aquatic pests, based o n fun ctional characteri sti cs and groupin gs.

Th e fo urth pro gram , E co logica l Assessment and Water Quality, will build a framework fo r assessin g aqu atic ecology and water qua lity with relatio n to descriptio ns o f habitat. W o rk on al ternative approaches to ' reference' condition in rivers will continue .

In urban areas, this program group, formally linked with a project in the C RC for Catchm ent Hydrology, w ill be expanding th e relationship betwee n stormwater flo w and urban stream hea lth, testing a number of climatic or geographic zo nes.

In short, interesting new areas of work, challenging scales of thinking, and a developing capacity for ecological predicti on should be the hallmark of the CRCFE in the coming seaso ns.

CRCFE feature continued after Waterworks

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WATER DECEMBER 2002

CRC

FOR

FRESHWATER

ECOLOGY

PROTECTING AUSTRALIA'S RIVERS: URBAN AND INLAND Ecological Integrity

A Milligan, C Walsh, R Norris, P Liston, I Lawrence . 'tJ and suspended sediments to urban

As countries around the worl d grapp le w ith the poor conditio ns of their rivers and lakes, th e researc h o f the Coopera ti ve Research Centre fo r Freshwater Ecology (CRCFE) is helping to imp rove them. Th e CRCFE has been a main player in developing and assess in g m e th ods fo r measuring the condition of lakes and rivers . In pa rticu la r, the CR CFE has also met the chaUenge o f controlling urban sto rmwater pollutants that affect the ecological Ginninderra Creek, Canberra, downstream of the integrity of downstream waters. wall: the health and ecological values of urban E co logical in tegrity ca n be waterways can be maintained by upstream flow defi ned as the capacity co support attenuation and interception of pollutants. and maintain a balanced, integrated, adaptive biological system having runoff are recognised as m ajor contamithe fu ll range of elements and processes nants co receivin g water quality in urban expected in the lakes or streams of a region. areas. Sewage treatm ent technology is now If managers of a ri ver system can maintain well advanced in developed parts of the eco logical integrity in their rivers and world. It is poss ible to drink the treated streams, then they are almost certain to water emerging from a sewage treatment ensure that the widest possible range of uses plant in, say, Canberra, alth ough so me and amenities is supported. This is the aim aspects of the effect of trea ted sewage on for aquatic systems in Australia and around the ecology of receiving streams are not the world, but few fit the description. well understood.

Part 1. Urban waterways In urban areas with large numbers of people and large areas of impervio us surfaces, the ecological integrity of streams is often poor. Urban areas are m ajor sources o f contaminants that degrade receiving waters, whether fresh or estuarine. Sewage (and industrial efiluents) and stormwater

Stormwater runo ff has less predictable composition than treated sewage. Until the 1970s, when sewage p ollution began to com e und er co ntrol in urban areas, scormwater pollution was not recognised as a threat to streams. Yet stormwater regularly contributes nitrogen, p hosphorus, heavy m etals and other toxica nts, COD

drains, streams, lakes and coastal waters.

A d ra in age system designed co mjnimjse flood risks by efficientl y trans portin g wate r from th e catch ment is one of two main c haracteristics com mon to -urban ised areas in the developed countries of the world. T he other characteristic is imperviousness. In hydrological terms, an efficient drainage system carries stormwater and its poll utants quickl y and dam directly from impervio us roads, roofs, carparks and paths in to urban stream s. Imperviousness is the proportion of a catchment that is covered by impervious surfaces (roads, paths, roofs). In large urban areas in the north ern hem isphere, impervio usness is blamed for degrada tion of receiving waters. As a rul e of thumb, workers there expect the quality of receiving waters to be poor if 10% or m ore of their catchmen t is impervious.

In recent work, C hris Walsh and cowo rkers from Monash University, a resea rch partner in the C R C FE, have develo ped a preliminary measure of ' dr a in age co nn ec tion'. Dra i nage connection is defi ned as the proportion of impervious areas in a catchment that is directly connected to a stream by a stormwater pipe or sealed drain. Walsh 's team fo und that drainage connection is at

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least as important as imperviousness in explaining patterns of stream degradation .

T he team used a variety of biological assessm ent m eth ods to compare the i1n p acts o f imperviousness, drainage connection, density of septic tanks, and density of unsealed roads on the health of sn1all stream s in the D andeno ng R anges on the eastern fringe of M elbourne.

Attributes assessed included th e composition of macroinvertebrate and diatom (microscopic algae) assemblages, abundance of algae on the stream bottom and con centrati o n s of n utrients (such as nitrogen and phosphorus).

Impervious areas and roads were map ped using GIS so ftware, geocoded according to land parcel data, and checked against digital aerial orthophotography.

Storm water drains were tracked from Council and water authority data, and their li nkages t o imperv ious are as we r e identified. Catchments were o utlined from topographic maps and stormwater pipe data. Septic tank data came from the ru ral shire office concerned. Sixteen catchments of varying urban density were chosen for study, with the main criterion for selection being that land use in the catchm ent be pri marily either urban or forest.

Catchment imperviousness was calculated as the proportion of total impervious area t o catc h ment ar ea. Draina ge co n nectio n was cal culated as t h e proportion of connected im pervious area to total impervious area in a catchment.

U nse al ed road area was assessed in proportion to catchment area. Septic tank density was the number of tanks per km 2 in each catchment.

Across the study area, imperviousness was positively correlated with connection and negatively correlated with unsealed road density; these three factors broadly defined urban density. Subcatchments with 1-10% imperviousness varied widely in their degree of connection .

Differences b etween str eams in macroinvertebrate and diatom assemblage composition, algal biomass and baseflow phosphorus concentrations were all broadly explained by urban density. H owever, in most cases, the effect of d rainage connection independently explained more variation in tllese biological attributes than did imperviousness. Catchments of 5-10% imperviousness with more than 25% of the ir i m p e rvious su r faces d i rec tl y connected to streams by pipes, showed strong shifts in sp ecies presen t. Such stream s had less than half the sensitive mayfly, stonefly and caddisfly fami lies fou nd in catchments with no urbanisation.

N one of the streams with more than 25%

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connection supported an enda ngered shri mp-lik e sp eci es, Austrogamma rus australis, fo und commonly in streams of the study area w ith fewe r stormwater pipes.

Furthermore, p hospho rus concen tra tions and densities of algae growing in the highly connected streams were much greater than in non-urbanised streams.

T he measure of drainage connection used in this study, while being a strong predictor of stream condition, is somewhat simplisti c. H owever it encapsulates a major elemen t of major storm water treatment approaches, almost all of w hich reduce connection between the catchment and the stream by allowing water to infiltrate into the grou nd or by retaining water in wetlands for treat1nent. Further research is planned to develop co nnection as a catchment-scale indicator by incorporating the disconnecting effects of sto rmwater treatment measures, such as grassed swales, bio-retention systems, wetlands and ponds.

From this work it is hoped that catchment planners wi ll be able to predict the effects of different urban designs on the ecological condition of streams.

Key in-stream processes An important CRCFE research contribution to urban water management has been the understanding of the key instream physical, chemical and biological response processes on an ecosystem and pressure (stressor) basis, including the facto rs (such as flow, pH) that n1ay modify th ese p rocesses . T h is researc h h as highlighted the central role of biota (including microbes) in mediating the transformation of nutrients and organic material discharged to waterways, and the role of habitat and flow in determining the structure and composition of biota.

As a result, u rban land use and management practices can now be linked to water quality and ecological ou tcomes.

Equally, the understanding enables urban waterway ecosystem options (streams, lakes, ponds, wetlands) and values to be designed and built. They have implications for the sustainability of catchment land use and management.

The CRCFE research has established four pre-requisites to restoration of urban stream health: • restoration of the geomorphology and physical habitat (including macro-plants); • restoration of flow regimes and disturbance patterns (environmental flows); • reduction in water pollution stressor loads to sustainable levels; • re-establishment of lost species, w here local recolonisation sources no longer exist.

T he revised Water Quality Management

Guidelines for Fresh and Marine Waters

(ANZECC/ ARM CANZ 2000) identify the 11 majo r issues threatening ecological health or water use. In the case of no npoin t sources of pollutants (such as urban storm water), the effects o n the receiving waters are 'indirect response processes'.

T hat is, the load of sedimented organ ic material creates reducing conditions, transformi ng sedim ented nutrients and toxicants into bio- available forms.

Other factors, such as suspended solids loads, flow and detention time, temperature and wind mixing may be important modifiers of these response processes .

The biota associated with the processing of discharged material are the same biota responsible for the ecosystem fu nctio ning of the receiving water, and are reflected in measurem ent o f lake or stream health .

Principles guiding sustainable urban development A set of guiding principles is emerging from this growing understanding of water quality and ecological processes, adaptive management based approaches, and urban water bala n ce based research. T h e principles also build on the National Water Quality Ma11ageme11t Strategy planning fra m ework fo r catch ment and stakeholder partnerships.

In princ iple, susta inable u rban development needs to: • be catchmen t-based; • be a partnership, between com munity, industry and gove rn ment; • be knowledge-based, li nking catchment management practice and waterway values; • be an integrated 'water in the landscape' based design (using total water cycle (TWC) or water-sensitive urban developmen t (WSUD)); • capture multi-functiona l benefi ts of urban elements (waterways, wetlands, ro ads); • conserve water, by reduction, recycling and restoration; • use performance assessment and an adaptive review of strategy.

The TWC-based ma n ageme n t comprises the integr ated u se and management of urban water (rainwater, wastewater, groundwater, mains supply) across the landscape to secure a range of social, economic and en viro n mental benefits. The WSUD foc us is prim arily on residential block arrangem ents (at- source), whi ch enhance on- si te deten t io n (rainwater tanks, infiltration trenches, swales, porous pavements) and conservation o f water (rainwater tanks, wate r efficient appliances, recycling of water) .

W hen these two are integrated together, the result is a holistic landscape-based approach to urban water managemen t.

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Im proved in format ion on optio ns for integrated m easures fo r residents, planners, water managers and consultants is the key to this approach.

These approaches can accrue significant water quality benefi ts because one-in-threem o n t h to o n e-i n - two -year averagereturn- interval storm events make up 70% to 90% of an nual average export of storm water and pollutants. As well, if infiltration, retention and recycli ng, and detention (reduced dra inage con nection) can displace the need for sto rmwater pipes, there can be major cost savin gs. Other major benefits are the restoration of soil and groundwater water balance, and the restoration of environmental flows in local urban strea ms.

Much of Australia's urban water infrastru cture is now reach ing the end of its eco nomic life. T his ageing in frastructu re could be replaced by new infrastructu re arrangements, based on total urban watercy cl e-based managemen t , that y ield substantia l economic, social and en vironm ental benefits to the co mm unity.

Increasingly, urban commu nities are taking decisio ns affecting urban sustainabiJity and strea m values. Many communities are adopting designed wetlands and storm water ponds to reduce drainage connectivity.

Suc h an approa ch can al so yield a range of other benefits: open space and amenity, recreatio nal values, po lluti on co ntrol, flow attenuation and drainage management, water su pply, conserva tion and education. Welldesigned wetlands can capture alJ of these social, econom.ic and environmental benefits.

Only through processes en hancing open communication, sharing of knowledge and development of trust, can the ideas and capacity for change be harnessed.

Part 2. Assessment of inland river condition Away from large urban areas, catchment disturbance is mainly implicated as a ca use of deteriorated water quality and reduced ecological integrity. Part of the problem is similar to that in urban areas - contam.ination by excess nu trients, whether from faecal matter or from fertiliser and surface soils. As well, where vegetation cover has been lost on the riverbank and in the catchment, instream habitats are being degraded by sediment that washes into streams during erosio n. H ydrological change, imposed w hen the river flow is artificially reduced by storage o r pumping, upsets the natu ral sequences and seasonal functions of the river and its biota.

T he CRCFE, together with CSIRO Land and Water, last year completed a national assessm ent of river condition as part of the National Land and Water Resources Audit (NLWRA; see www.nlwra.gov.au) . The assessment was a huge achi evement, because not only were new methods chosen, so the

ECOLOGY

assessment could be consistent across a whole continent, but also it was completed in little more tha n a single yea r. A fo ll ow-up assessm ent within the M u rray-Darling Basin is reported in the Sn apshot of the i\ll11rrayDarling Basin River Condition.

T he S11apshot, and the Australian audit, was based on the premise that ecologicaJ integrity, as assessed by th e aquatic biota, is the fundamental m easure of river co ndition. Biota are usually the end point of environmental disturbances an d pollution, so they are the primary indi cators of disturbance, the more so because society places high value on som e ri ver biota, such as fish, fro gs, turtl es, yabbies.

A C RCFE research tea m led by Richard N orris of the University o f Ca nb erra, devised a model of river condition, based on m odels also used in the Snowy Ri ver and the Victorian Index of Stream Condition. Pu t simply, the model 'says' that the condition of the biota depends on the condition of their habitat, and the condi tio n of thei r habitat depe nds on catchm ent conditio n.

The Snapshot reported the condition of in dividual reaches and of 23 river va ll eys in the Murray-Da rling Basin , based on data for individual organisms, habitats and catchments.

For each river reach, the S1tapshot presents an assessment of th e condi tion of the bi ota, and of the biological response to environmental pressures ('drivers'). It do es that via five indices: a biota index, a catchment disturbance index, a n utrient and suspended sediment load index, a hyd rological disturbance index and a habitat index. Special attentio n was given to seven hydrological zones defined by the Murray-Darli ng Basin Commi ssio n along th e M urray, fro m Dartmo uth Dam downwards.

Assessment of ecological condition is based on an estimate of how fa r rivers have changed from 'natu ral condition' . To calculate the biota index, a set of reference sites, defined as minimally disturbed, was adopted. In som e cases, the reference co ndition was only available as a model, often of conditions t h ought to hav e preva iled p re-1 750 .

R eference conditions are as near to natural or desirable as it is possible to achieve in each district.

The indices representing environment conditions described the effects of: â&#x20AC;˘ land use (catchment disturbance index, derived from existing governmen t land surface data); â&#x20AC;˘ suspended sediment and nutrients (nutrient and suspended sediment load index, derived from modelled NLWRA data for N , P and sediment); â&#x20AC;˘ total and seasonal flow volumes, their variability and periodicity (hydrological disturbance index, derived from hydrologicaJ stations across the Murray- Darling Basin);

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• bedload, vegetation and connectivity (habitat index, derived from modelled bedloads, and data fo r land cover and connectivity, integrated using the standard Euclidean distance).

T he team grouped the environn,ent indices into four bands : largely un modified , moderately modified, substantially m odified and severely modified. The biota index was also reported in bands: reference condition, significantly impaired, severely impaired and extremely impaired.

T he assessmen t wou ld not have been possible without the use of data that had already been collected fo r particular purposes within each state or territory, though only data that p rovided consistent basin-wide coverage were used.

Few data were cons istently available about fish or vegetation (despite their high value to society) , so the biota index was derived only fro m data on macro invertebrates, gathered using the AU SRIVAS meth od (see www.a usrivas.canberra. edu .au).

Groups of reaches with com mon problems were identified using multivariate statistics.

T he find ings can be summ arised succinctly. In 40% of river length assessed

FRESHWATER

in the M urray-Darl ing Basin, the populations of biota were significantly poorer than expected. In 10% of assessed river length , the damage was worse, with fewe r than 50% of the expected m acroinvertcbrate grou ps present. Environ mental conditions were found to be degraded in some way in over 95% of the river lengths assessed, most commonly by catchment d isturbance and/or loads of n utrients and suspended sediment. The hydrology of over half the reaches assessed had been m odi fi ed, particularly im media t ely downstream of dams and in lowland reaches used to supply irrigation .

Which method to use?

Assessment of river condition, whether in urban or other areas, is now ongoing and widespread in A ustralia. T he assessm ent teams need methods that are cost effective and can be integrated into monitoring programs. Can any o ne set of methods produce accu rate data in all the degraded situations that may be encountered? Im portant ecological stresses that have been identified include nu trient enrichment, increasing salinity, pesticides, sediment loading, water extraction, flow regulation, loss of riparian vegetation,

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effluent discharge, introduced species, and habitat degradation.

At fi rst, w hen reliable methods were needed for early assessments of water quality, macro invertebrates were seen as offering the greatest potential as indicators.

H owever, the existing n1acroinvertebrate methods are in need of rigoro us testing, compari ng their use w ith other potential methods. Further, they do not address all aspects of freshwater ecosystems.

Monitoring agencies still fi nd themselves using physical and chem ica l methods to meet thei r legal obligations . Biological tec hn iques still need integration into monitoring programs to provide useful o utputs for managers.

Th erefore, P ete r Li ston of Environment AC T , a CR C FE partner, working w ith Ri chard Norris, has begun testing the sensitivity and accuracy of a range of biological assessment methods, including m acroinvertebrates used in AUSRIVAS, diatoms, fish, macrophytes, carbon and nitrogen isotopes and benthic metabolism.

International implications Water quality is being measured by nations all over the world as international environment obligations and expectations come into force. AUSRI VAS, and the methods fr om which it was derived (RlVPACS), is being used fo r assessments in several countries, taking its place al on gside other me thods develo ped overseas, such as IBI (in USA), R IVPACS (in UK) and BEAS T (in Canada).

Likewise, the CRC FE understanding of nutrient-sediment interactions is being called into use in other countries, as the move to rehabilitate urban waters gathers momentun, .

The li nks between research groups and transfer of knowledge that are a natural part of the Cooperative Research Centres program in Australia could be said to be now benefi ting h umankind in general.

The Authors Ann Milligan is Communications Manager at the CRC for Freshwater Ecology (CRC FE) in Canberra; Dr Chris Walsh is a Project Leader at the CRCFE, based at Monash University in Melbourne; Associate Professor Richa rd Norris is Program Leader of the Water Quality and Ecological Assessment Program, based at the University of Canberra; Peter Liston is a member of Environmen t ACT and the CRCFE in Canberra; Ian Lawrence is an Honorary R esearch Fellow of the C R C FE, based in Canberra.

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USING ECOLOGICAL KNOWLEDGE TO UNDERPIN RIVER REHABILITATION P Cottingham, S Bunn, G Quinn Introduction of Vannote and co ll eagues, the 0 In- strea m producti on flo od- pu lse co ncept (FPC) of M ill ions of do llars are spent â&#x20AC;˘ T errestrial ca rb on -0 River carb on J unk an d co-wo rkers, and th e each year on trying to improve ri veri ne produ ctivity m odel th e condition of our waterv-1ays.

(R PM) of T horp & D elo n g.

However , the scientific u nde rEach m odel places a differe nt pin ni ng of chis work has been emphasis o n aspects such as the li mited and there have been few sources Down stream tra nspo rt of ca rb o n Im portant o f carbon that drive reports on t h e eco lo g ica l prod ucti vity and th e role of R ipa rian Inputs Impo rta nt b e n e fit s of rehabi l it at io n flo ods (Figure 1) . Th e R CC measures when implem ented. (a) River Continuum Concept (RCC) places em phasis on terrestrial This makes it di fficult to learn carbon and nutrients that enter and pass on know ledge that w ill w ate r w ays as a res u l t o f assist others who are also trying Emphasis 11 on lower fl o od -plain procesao u pstream processes. T he other Upper catchm ent likel y to be sa me as RCC to rehabilitate degraded systems two mod els differ from th e or protec t ri ve rs in go od R CC in their view of th e con dition . It also makes it drive rs o f ecological processes d ifficult to develop a predictive in the lo wland reac hes ofla rge capacity that ca n help us make rivers. Fo r exa mpl e, the FP C in fo rmed decisions on rehabilemp hasises th e importan ce of i t a ti on . T h e C R C fo r (b) Flood- Pulse Concept (FPC) l a t e ra l r iver- fl oo dp la in Freshwa ter Ecology (CR C FE) exchanges fo r large ri ve rs and is p lay in g a v ital rol e in proposes chat riverin e fo od providing t h e eco l o g ica l Emph 11l1 11 on local proce11es webs are more depend ent o n knowledge that is needed to Upper ca tc hment like ly t o be same u RCC productio n deri ved fro m th e u nderpin and gu ide practi cal floodplain than o n organ ic r es to ra tio n m easu re s. Th e m atter transported fro m tribuCRC FE h as tw o r es ear ch taries upstrea m. T h e RPM programs th at aim to improve highlights th e impo rtance o f our understandi ng of esse ntial lo cal in-stream production to ecologica l processes that will (c) Riverine Productivity Model (RPM) lowland rivers (phytoplankton, assist in rehabili tation and the b e n thic algae , and ot h e r recove ry o f disturb ed rive r Figure 1. Contemporary models of large river ecology. aquati c plants) and , to a lesser sys tem s. T he ' Flow- Related Reprinted from Moreton Bay and Catchment (I.R. Tibbetts, N.J. Hall extent, direct inputs of organic Ecological Processes' program is & W.D. Dennison, eds, 1998). Marine Botany Group, Centre for matter from the adj ace nt investigati ng the relati o nship Marine Studies, The University of Queensland. riparian zone . T h is model between flo w and ecolo gical suggests that the o th er two processes in rivers and their the u nderl ying so urces of degradation models o flarge river ecosystems underesflo odplains. The 'R estoratio n Ecology' (stresso rs) and are likely to succeed. For timate the role of in-stream production and program focuses on constraints to recovety example, reintroducing wood as habitat for over-emphasise the relative importance o f o f d istu rbed sys te m s, incl u din g th e fish is unl ikely to su cceed if wa ter quality terres tri al organi c m atter from bo th protection or reintroduction of habitat is degraded or th e river dries up du e to headwater streams (R C C) and floodplai ns featu res, and recolo nisation p rocesses . excessive water extractio n.

(FPC) .

River ecologists o ften co nsider three Conceptual Models of River Function CR C FE investigatio ns of ecological co n temp o rary models of large ri ve r fun ction ing at th ree sites alo ng the River An understanding o f basic ecological processes is imp ortant if we are to ecology, each o f which assu mes that ri ver Murray (the Lowland Rivers Project, with p rio ritise and im plem ent rehabilitatio n ecosystems are driven by ' b ottom up ' sites located near Albury, Barm ah fo rest m easures that have a high likelihood of processes (processes su ch as primary and n ear H attah- Kulkyne N ational Park) success. If we understand river ecology and productivity and n utrient cycling, which have found that phyto plankton played a how this has been affected by human in turn make resources available fo r major role in river productivity at each site. activity we can be co nfident that any organisms higher up the foo d chain). These Bacterial commu nities also contributed to rehabilitation measures we adopt address are the river co ntinuum co ncept (R CC) p ro d uc tiv ity in th e Ri ve r Murra y, WATER DEC EMBER 2002

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suggesting that microbial processing of carbon and other nutrients is also important. Other interesting fi ndings were that water releases from H ume dam near Albmy reduced productivity (possibly due to lower than natural temperature), and that macrophyte production was also an important sou rce of riverine productivity at the Barmah site . The results suggest that neither the RCC n~r the FPC is easily applied to Australian rivers neither predict the dominance of phytoplankton in lowland rivers. Phytoplankton productivity in th e River Murray was higher than expec ted, probably because flow regulation in the river provides conditions more conducive to algal growth than would have occu rred naturally (e.g. presence of weir pools with warm, nutrient rich water in summerautunm; reduced connection between the river channel and its floodplain, which reduces th e avai lability of floodplain carbon and heterotrophic production).

The RPM does predict that in-stream and riparian production are important components of riverine function and, along with results from the Lowland Rivers project, suggests that the protection or rehabilitation of aquatic macrophytes and 1ipa1ian zones are important management considerations. However, the RPM does not consider the effects of floods on processes such as productivity and nutrient cycling, and so does not provide a complete picture of how Australian rivers function.

Unfortunately there were no large floods of the River Murray to coincide with the Lowland Rivers project, and this aspect

AGAL

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of rive r functio nin g cou ld not be explored.

In contrast to the River Murray, benthic algae have been found to play a major rol e in driving the productivity of waterhol es in arid areas of Australia, such as within the Cooper C reek system. The turbidity of waterholes can mean that high levels of production are confined to the shallow margins of waterholes (the ' ring around the bathtub effect'). These highly productive shallow margins are easily disturbed and their loss would have implications for other biota in the food chain associated with the waterholes. Actions to protect or rehabilitate waterholes include the prevention of rapid drawdown (which exposes the highly productive benthic algae), control of stock access to reduce trampling and pugging, and carp control.

This work supports the findings of the Lowland Rivers project that the FPC has been over-emphasised for Australian nvers.

adapted. However, in many instances our ability to predict the ecological response of river systems to changes to the natural flow regime or the reinstatement of flow as part of environmental flow packages is not very specific.

The C R C FE has been conducting a unique £low manipulation experiment in the Campaspe River in central -west Victoria. The project aims to provide environmental flows in the Campaspe River below Lake E ppalock outside the irrigation season using altered storage operation, and to investigate patterns in fish and 1nacroinvertebrate comnwnities befo re and after the fl ow cha nge.

Conditions in the Campaspe River will then be compared with those in the nearby Broken River to help identify causal links between ecological responses and flow cha nges. The £low manipulation (release of 25% of inflows) is planned when storage in Lake Eppalock reaches 64% capacity during May-October. This project has collected a remarkable set of Linkages Between Flow and before-manipulation data, partly due to Ecological Response the extended dry spell in central Victoria Recent reviews have highlighted that that has meant that the modified environ the flow regime and ecology oflarge 1ivers mental flow regime remains mostly are inextricably linked . If elements of a undelivered. However, the project has still river's flo w regi me are changed an greatly improved our understanding of ecological response is likely. For example lowland river ecology. For example, capturing flows in dams and diversion of investigations have shown that most fish water for irrigation and domestic in winter rainfall lowland rivers spawn consumption can reduce the volume of each year despite large variations in the water available for inundating floodplains timing of flow and temperature patterns. and their associated wetlands, or change Juvenile fish were found to prefer the seasonal pattern of flooding and d1ying sheltered habitat (e.g. backwaters) that are to which native flora and fau na are also abundant in food sources such as

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zooplankto n. This wo rk has led to the development o f th e 'low flo w recruitment hypothesis' that suggests that low flows play an important role in fish recruitm ent.

Amongst other co nsideratio ns, protectin g river channel backwaters as important habitat fo r zooplankcon and j uve nile fish sh o uld b e a fea ture o f op era ti o n al management or rehabilitation plans fo r regulated lo wland ri vers.

Large floods can turn rivers in arid areas (e.g . Cooper Creek) into vase, slowmoving wetlands, triggering be nthi c and p e lagic alga l p ro du ct io n ac ross t h e inundated flo o dplain . T his bo om of p rodu ction o n the flo odplain is usually follo wed by a proli fe ratio n of aqu atic invertebrates, w hi ch in turn prov ide food for other fa una suc h as fis h . Studies of C o oper C reek have found that fish species get mu ch o f their fo od fro m aquatic sources, not te rrestrial sources as mi ght be expected if the Flo od Pu lse Co ncept held tru e. Algal prod uctio n is suspected to be a maj or drive r o f the fo o d web on th e fl o odplai n. Whatever the ultimate carbo n source, however, production o n inundated floodp lains un d oubtedly has a massive influ ence on aquatic and terrestrial fo od

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webs at local and possibly eve n landscape scales. Altering the frequency, duration and area o f inundation of large flood e ve nts is likely to have a marked influ e nce o n the produ cti vity of a dry land river.

Reintroducing Habitat Complexity in Degraded Streams A key assumption of many ri ve r and riparian resto ration acti viti es is that if you re build or recreate habitat the n o rganism s will return and ecological condition w ill improve. This implies chat recovery of d egraded strea ms and rivers is largely constrain ed by th e ava ilability o f suitable habitat. H owever, successful river rehabilitation will also depe nd o n th e ability o f organ isms to reac h any new habi tat via dispe rsal. Physical restoratio n o f ri ver habita ts is unli kely to be successfu l if ecological reco very is constrained by th e inability o f aquatic planes and animals to reco lon ise disturbed sites. T o be able co predict how quickly disturbed syste ms will recover, we need co kno w ho w aqu ati c orga nisms disperse (i.e. w hat m echan isms th ey use) and how fa r can they m o ve.

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accumulates w here upl and screams (with high stream po wer) change co lowland screams of low power. This is evide nt in strea m s draining the Stra chbogie Ra n ges in central Victo ria, wh ere slugs o f sand occupy large sectio ns of wate rways su ch as C reighton 's and Castl e C ree ks (th e G rani te Cree ks area). P revious research by C RCFE and the C R C fo r Ca tchme nt H ydrology has led co a good understanding of th e histo ry and ge omo rpholo gical co nditi ons of these strea ms, and their fish and in vertebrate co mmunities. Th e fish fa una in sa nd-slug affected areas is now mu ch altered. Th e typical lowland fish co mmunity that we wo uld normall y expect in the area prior co degradation (e.g. comprising Macquarie perc h, gudgeons, sm elt, p ygmy perch) has been large ly re placed by mo untain galaxias and , in places, river blackfish , two species chat are be tter adapted to the shall ower and faste r flo wing wate r in th e sand affected areas.

E ven sites w ith highe r sp ecies dive rsity were considered co be degraded, given the low population numbers present. W ork by th e C R C for Catc hment H ydrology has found that the sand slugs in th e Granite C reeks, which extend for 15-20 km , are

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CR C

FOR

FRESHWATER

ECOLOGY

While it is too early to tell if the now virtually stationary, and that human intervention will be required to mitigate reintroduction o f wood has lasting impacts on the abundance and diversity of native their effects in both the short and long term. fish sp ecies, the fact that fish are using the wood structu res as habitat is a positive Wood structures (red-gum railway result. T he study has also emphasised the sleepers) were added to the streams at effects of drought on the distribution and Creighton's Creek (a perennial stream) abu ndance of river fa una. C astle Creek and Castle Creek (an intermitten tly flowing stream) in autumn 2001 to ¡ dries out completely du ring sum mer through much of the sand-affected length. determine whether reintroducing physical R esults suggest that species such as features resulted in increased hydraulic galaxiids are able co respond to this drying diversity, increased fish and invertebrate by migrating up or downstream into pools species diversity and abundance , and chat serve as refugia. It appears that most whether there arc distinct assembly rules other species (in cluding river blackfish, in the developm ent of ecological commupygmy perch and gudgeons) are unable nities on and around th e structures. to move over these long distances, and Sleepers were laid perpendi cular to the therefore are absent from much of Castle ba nk and rais ed sl ightly from the Creek. streambed, the positi on considered to be most effective in the fo rmation of scour Wo od has also bee n su ccessfu ll y reintrodu ced into sections of the River pools. A to tal of 18 sites across the two Murra y b e tween Yarrawo n ga and streams were studied du ring the experTocumwal. D e-snagging of ou r river iment, including three single sleeper, three systems has been recogn ised as a major multiple sleeper and three control (i.e. no treatment) sites in each stream. There have ca use of habitat loss and the consequ ent decline of native fish populations. Large been three surveys of stream fauna (fish logs (snags) are often a key form of strucand macroinvertebrates) and two geomortural habitat in lowland ri vers and have phological surveys of the study sites since been demonstrated to be criti cal habitat the wood stru ctures were placed. for both Murray cod and the endangered Th e wood stru ctures were rapidly trou t cod. T he feasibi li ty, methods and colonised by both algae and invertebrates environmental benefits of returning snags following their introduction, altho ugh are being tested in three 10 km reaches with notable differences in the strength of the River Murray between Yarrawonga of colonisation between the peren nial and Tocumwal. Large snags have been Creighton's Creek and the intermittent reinstated in th e study reac hes and the Castle Creek. Th ere has been limited resp onse o f fish populations (particularly formation of scour pools downstream of Murray cod and the endangered trout the stru ctures, presumably due to the lack cod) monitored. In addition co confirming of floods since the structures were introchat species such as Murray cod w ill use duced. T here has been a general infilling reintrod uced snags as habitat, the project of other natural sco ur pools in the area has improved our understanding of over the study period , which suggests that habitat preferences of native fish and high flows are an important factor in the assisted in the development of a decision creation and ¡maintenance of hydraulic support system to help identify locations diversity within the creeks. where the reintrodu ction of snags will Fish populations in Creighton's Creek have the greatest ecological benefit while also responded quickly, w ith rive r m1111m1si ng coses. blackfish and galaxiids almost doubling in T he lessons learnt from replacing abundance at the treatment sites. It is w ood in rivers in the Granite Creeks, the thought that the stru ctures, along with River Murray and elsewhere in Australia debris that accumulates around th em, have highlighted three major p oints: provide cover and protection for these 1. Wood plays an essenti al ecological species. Changes in the intermittent role in many river systems and should not Castle Creek have been less pronounced, be removed. We should move away from presumably due to the prevailing drought. considering wood such as fallen logs as San1pling in summer of isolated pools in 'debris', which suggests that it of no use Castle Creek and in other intermittent or importance. streams nearby has revealed that such pools may act as refugia as th ey can contain 2 . The density of snags in ri vers is a funct ion of trees in the riparian zone . dense populations of fis h, predominantly native species. It is hoped that these areas P rotectio n of the ripa rian zone is important if we are co ensure there is a of refuge will allow the rapid colonisation future source of wood for rehabilitation. of the creek once flow increases again.

36

WATER DECEMBER 2002

3 . Wood on floodplains also plays an important ecolo gical role and shoul d not be removed.

Not all rehab ilita tion projects are successful in improving ecologica l condi tions. For example, experim.ental rock riffies were placed in six small urban strea ms in 1995. M acroin ve rteb rate comn1unities were monitored both before and after the riffies were installed. The macroinvercebrace communities were considered degraded prior to installation of the rock riffies and have rema in ed in that cond ition ever since. This is stron g evidence that catchment-scale factors, such as stormwa ter pollution, can limit instream commu nity deve lopment in this case.

Evaluating the Success of Rehabilitation Projects R iver managers make considerable investments in rehabili tation activities, such as revegecacing riparian zones to increase biodiversity, providing en vironmental flows co meet the needs of aquatic plan ts and animals, or reintroducing wood to rivers to provide habitat for native fish. T he benefits of such activities wil l b e m ax i mised if their effectiveness is assessed and the lessons learnt used to support decision -ma king in the future and communicated to others dealing with similar issues. Unfortunately there are few reports of the ecological outcomes of rehabilitation projects in Australia . Al l too o ften the monitoring component of rehabilitation projects is ignored, o r only considered once the re h abilitation activity h as been comm enced, m aking it difficult to determine if any ecological change was due to the rehabilitation activity or some other factor. Designing and implementing a select number of well-resourced studies co confi rm the potential benefits of various rehabilitation techniques will ensure chat large-scale investments are well placed. Fewer, large-scale investiga tions are likely to provide more information and learning than a larger number of poorly resourced m on itoring programs.

The Authors Peter Cottingham is a Knowledge Broker - a m ember of the knowledge exchange team - fo r the C R C for Freshwater Ecology, based in M elbourne.

Professor Stuart Bunn is Program Leader of the Restoration Eco logy P rogram , based at Griffith University, Queensland. Associate Professor Gerry Quinn is P rogram Leader of the Flowrelated Ecological Processes Program, based at M onash U niversity, M elbourne .

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AWA

CRC

FOR

FRESHWATER

ECOLOGY

THE IMPORTANCE OF BIODIVERSITY A Kotlash Biodiversity is one of those terms coined to try to capture the meaning of a complex concept. It is most often used to describe the diversity (or variety) of living things (plants, animals and microorganisms), usually in terms of species richness.

People often think of biodiversity as the number of different species living in an area and that the higher the number the better. Others think of the conservation of endangered species, and take the view that their conservation constitu tes good biodiversity management. But it is not always appropriate to aim fo r high species richness/number, or to maintain recognised endangered species, without at least a fundamental understanding of the structure and function of the ecosystems in which they live.

T he diversity of species must be appropriate for the type of system, its location, the time of year, and so on (for example, healthy native species reprod ucing from an adequate gene pool) . In the case of endangered species, good managem ent can only be planned if the ecology of the species is known and understood and acted on in ways that create sustainable solutions. In the words of Peter Cullen: ' Focusing our conservation efforts on severely threatened organisms, and developing expensive recovery plans that may not work, could mean Australia has the best-documented extinctions in the world'.

We must do better than this, we must manage our biodiversity with the knowledge we have.

Species richness and iconic species may well be the endpoint on which we focus, but for the purposes of managing biodiversity, the other facets of diversity are often the most important operationally.

They p rovide a perspective on the ecosystems that we need so that we can conserve and restore biodiversity now and for future generations.

Biodiversity can be considered at a range of scales, from genes and species to populations and communities. Inextricably linked to these scales of biodiversity is the diversity of the habitats and landscapes (structural diversity) in w hich organisms

38

WATER DECEMBER 2002

Snags (branches lodged in waterways) offer a diversity of habitats for aquatic biota.

live and the diversity of the functional processes on which t h ey depend (functional diversity) .

In broad terms, aquatic structural diversity, which is also referred to as ecosystem diversity, is represented by the range of inland aquatic systems such as: • streams and rivers; • billabongs, backwaters, lakes and impoundments; • floodplains, swamps and other wetlands, both permanent and ephemeral; • inland saline systems; • mound springs, caves and groundwater.

Inland waterways are made up of an assortment ofliving, once-living and nonliving structural elements, water being the most obvious non-living one. T here are geomorphic elements such as channels, bars and islands and living elements such as riparian vegetation and aquatic plants.

Animals, too, can fo rm structural elements within an aquatic system; for example by playing hosts to a wide variety of parasitic organisms. Snags (that is, once-living trees and branches that fall into and lodge in our waterways) are a good example of a structural element of an aquatic system.

Adding to the complex structural make-up of our aquatic systems is that they change character, over time and from place to place, with resultant changes in biodiversity. This can happen as a result

of a disturbance. Disturbance may be natural o r human-induced or combinations of the two. A good illustration of a natural disturbance is the episodic floods that extend over vast floodplains of rivers in Australia. For much of the time these rivers exist as networks of ephemeral channels and tu rbid waterholes. As water floods and recedes these systems change, often dramatically over space and time.

In some areas weirs and levees change these natural processes of flooding and drying.

T he form of a river changes continuously along its length, from its source to the end of its catchment, effectively varying over space and time. Changes in structural make-up are also evident across a river channel; for instance w here there are different water depths, flows and types of substrate and small-scale structural elements such as snags. Snags provide habitat for a w ide variety of aquatic plants and animals at various stages of their life cycles. Snags modify the flow conditions of a river and help shape its bed and banks.

T he natural breakdown of snags causes alterations in their character and position, illustrating how structural elements change over time and from place to place.

Natural change during the development of ecological communities is a good example offunctional diversity. We can use riparian vegetation to explore this

CRC

FOR

FRESHWATER

ECOLOGY

PHOTO: CATHERINE MOORE c o n c e p t . Riparian Biodiversity assessm ent vegetation goes through a and regulation is being number of stages of develaddr esse d t h rou g h a opment - which can take number of projec ts. The years, decades or even Dryland River R efugia cen turies - from bare p r oje c t 1s ex am1n 111g banks sprouting a few qu estions of fragm entation s p ec i es, t o mat ur e a n d c onn ec ti v it y o f communities. The 1ipa1ian ecosystems in C ooper zones of most ri vers are C reek, Warrego R iver and contin ually going through the Border Rivers. It is chi s pro cess to so m e d etermining th e impo rex tent. The b a la n ce tance o f water holes as between rejuvenation and r e fu g i a for aq u ati c terrestrialisation processes organ isms in dry land river sustains the di versity of catchments and identifying these differin g stages in che biophysical pro cesses Macroinvertebrates, such as this waterboatman (about 8 mm across riparian zon es. Since th e th at sustain biodiversity in real life), are near the base of the food chain in freshwater various stages are characand ecosystem h ealth in t e ri se d b y di s t in c t ecosystems. th ese refugia. This proj ect co mmuniti es, sp ec ie s h as pr o duced large understanding o f th e m echan isms by richness is high w here there is a wide integrated data secs now being pro cessed range of riparian communities at different wh ich they act; and co answer these questions. stages. Low diversity may be a natural â&#x20AC;˘ develop responses co these humanDesigning and developin g a long-term situation when viewed at smaller sca les. in du c ed pressures , to monito r the biodiversity monitoring program fo r the o utcom es of those responses, and to W e can also see natu ral ecolo gical Sydney Catchment Authority has also changes in th e progressive colonisa tio n of evaluate the effectiveness of th e responses. added co o ur knowl edge. W e have learnt Th e research program is addressing snags . how to effectively and efficiently m easure th ese a im s thr o ug h two t h e m es : D efini ng threats to biodiversity is the and assess fish, macroinvertebrate and Bi odiversity Assessment and Regulation , fi rst step in conserving fres hwater biota riparian vegetation bio diversity and how and Co nserv in g Biodi ve rsity . Th e and ecosystems. This takes time and is co identify locations of high conservation questions being addressed includ e: What continu ed throughout th e seeps o f the value based o n th eir biodi versity characdo we ha ve left - what of our natura l conservation process. D ecisio ns regarding teristi cs. W e have also gained insights into freshwater biodiversity remains relatively appropriate respo nses o ften need to be how best to m onitor and assess biodiintact, ho w do we m easure it, and ho w m ade imm ediately or very early in the versity changes o ver tim e. is it distributed across the landscape? How c onse rv ation process . An ad aptive A proj ect on Sustainabl e Man agement does the system work - what are th e approa ch , w h er e interve n t io n and factors that regulate biodiversity in natural of On- farm Biodiversity in the riceresearch, including monitoring and evalu and m odified ecosystems? W e are also growing in dustry is contributing to o ur ation , go hand - in- h and to achi eve addressing w hat can w e do . For instan ce, knowledge of the relationship betwee n im proved conserva tion o utcom es, is how ca n we identify key threatening ch is farming system and biodiversity at appropriate fo r the needs of these short processes, manage their impacts, pro tect farm and regional scales . timeframes. An increased understanding biodi versity valu es in natural and partially Co nserving biodiversity is also being of th e prin cipl es of conse rvation ecology degraded systems, and conserve threatened addressed through a number of o cher is v ital to und erpin de cisio n s fo r species and co mmunities? projects. T h e 'Adaptive Managem ent in restoration and th e abatement of th rea ts Progress is b eing made throu gh R estoration E cology' project completed in the longer term . resea rch proj ects and communication of its first phase in 2001 - 2002 by simulating our kn o wl e dge . Th e C RCFE ha s Th e C ooperative R esearch C entre for a cycle of introduction for the re- introexpanded its influ ence in the conse1vacion Freshwa ter E cology (CRCFE), by virtu e duction of trout cod. P hase 2 , w hich wi ll of biodi versity through national and of its strong industry li nkages and its state fo rums. It is participating in discusrefi n e this m odel, loo ks at alternative multi-disciplinary research capacity and sio ns, at nationa l and state level , of the approac hes co monitoring and plann in g knowledge base, is uniquely placed co n eed to conserve bio diversity in all provid e leadership in research and in and will instigate an o n-ground program ecosystem types. The program conttibutes applying the research to co nservin g and for re- introductio n w ith stak eholders. It restoring biodiversity valu es in a range of co these debates both directly, through is about to begin. C onservation biology outcom es of its projects, and indirectly by freshwater ecosystems. and system atics of th e individual species advice co committees. For instance, the The CRC FE's Conservation E colo gy or groups, fo r example mountain galaxias, listing o f 'Alteration of natu ral flow P rogram. aims to: mayflies an d crayfish an d frogs are being regimes of rivers and strea ms and th eir â&#x20AC;˘ assess biodiversity and its distribution in addressed by a number of proj ects. floodplains and wetlands' and ' Clearing of freshwater ecosystems, and to gain insights native vegetatio n ' as Key Threatening The Author into processes chat regulate levels of biodiPro cesses in NSW under the Threatened Amanda Kotlash is a Kno wledge versity at various scales in space and time; Species Co nse rvatio n Act, in 2002, Broker - a member of th e knowledge â&#x20AC;˘ identify threats to biodive rsity, to provides major legislative rec ognitio n of exc hange team - for th e C R C fo r measure their impacts on biodiversity, and threats co aquatic ecosystems and their to u ndertake research leading co a greater Freshwater Ecology, based in Sydn ey . biodiversity .

WATER DECEMBER 2002

39

m

WASTEWATER

BIOSOLIDS TO LAND: INTERNATIONAL REGULATIONS PART 1: CONTAMINANTS

-

H Reid Abstract Although land application ofbiosolids (loosely defined here as appropriately trea ted sewage slu dge) has demonstrated beneficial outcomes and has been a long established and widely adopted activity, the need for management of contaminant and microbiological risks has seen land application practices almost universally subj ect to regulatory oversigh t. T hese regulatory controls are not static and within recent years there have been significant initiatives within the United States, European and Austra lian regu lato ry frameworks. Understanding the potential significa nce of these changes is of obvious impo rta n ce to Au st ralian biosolids managemen t programs.

In July of this year, the National Research Cou ncil in the U nited States (US) finalised their 18-month review of the scientific basis for the regulatory requirements for biosolids in th e United States. Although this review did not find ev iden ce that t h e US regulatory framewo rk was inappropriate, the review did make a number of recommendations for updating the scientific basis for the regulations and the need for greater US Environment Protection Agency (US EPA) oversight ofbiosolids management.

Simultaneously with this activity in the US , the European Commission (EC) began redrafting their sludge management d irective (86/278/EEC). Although the redrafting has not yet progressed to a formal EC wo rking paper, and the process has stalled u ntil 2003/2004, the contaminant limits described in the early drafts have ca used som e concern. T he concerns arose because of the range of contaminants being discussed for potential regulation and the proposed limit values.

In this paper, the regulatory frameworks in the United States and Europe are contrasted with Australian approaches, and the implications of potential changes in regulatory philosophies are discussed.

The information presented has been partially derived from a recent tour of biosolids management in the US and Europe.

40

WATER DECEMBER 2002

The paper foc uses on co ntaminant management, with potential treatment and pathogen issues to be discussed in a subsequent paper. Nutrient issues are not discussed since they are relatively consistently managed an d well understood .

Overview of regulatory programs and land application For the purposes of this paper, biosolids is loosely defined as sewage sludge that has been treated and has sufficiently low levels of contaminants, such that it can be safely used for land application. Sewage sludge with inadequate treatment or excessive conta1nination is not considered suitable for land application and hence is not included within the definition of biosolids. A 'loose' definiti on is used, because the actual definitions of qualitative statements such as 'inadequate treatment' vary amongst regulatory approach es .

United States An nual sewage slu dge production in the United States is approximately 5 .6 million diy tonnes, with around 60% of this produ ction used as soil amendments and/or fertilizers. Landfills or surface disposal accounts fo r nearly 20% of production and 20% is incinerated (NRC, 2002). In the United States, the overarchi ng regulato1y framewo rk for land application is under the Code of Federal Regulations 40 Part 503. This is the socalled 'Part 503 rule', a regu latory framework that was promulgated in 1993. T he key sections of the regulations specify requirem en ts for contaminants, pathogens and measures to avoid attracting vectors (such as rodents) to land application sites. The 503 rule manages potential pathogen risks by combining prescribed treatment technologies and microbiological standards to derive two treatment grades (Class A and B). Potential contaminant risks are managed predominantly via a ceiling limit for contaminants in biosolids and maximum soil loading rates. A specific grade known as exceptional quality (EQ) biosolids is also described, which applies to Class A

treatme n t biosolids that are w ithin prescribed co ntaminant limits. Once a product is con fi rm as an EQ biosolids, it is not under the control of the 503 regulations and can be sold and land applied without restriction (Vesilind and Spinosa, 2001).

In c ontrast to th e requirements typically imposed in Australian biosolids guidelines, the 503 rule appears relatively relaxed, with higher contaminant Jim.its, slightly higher microbiological limits and the regulation not including detailed site management controls or requiring land appli cation permits. How ever, it is important to realise that the US system is multi-tiered. Within a state such as California, State and R egional Water Quality Control Boards are able to impose requirements and permit biosolids land application. Local councils are also able to attached controls, via passing ordinances. In the US, there have been several high profile cases where local councils have passed h ighly restrictive ordinances, such as bans on lan d application of Class B biosolids. While there is a common perception that these bans reflect public health concerns, in reali ty, the bans appear to be driven by political pressu res that are a result of odour and ame nit y impacts (such as t ruck movem ents) associated with large farms contra cted to apply biosolids. There also appears to be some differe ntiation based on the source of the biosolids, with bans on biosolids coming into the counties from large metropolitan centres, but the u se o f locally generated biosolids permitted.

Europe The 15 E uropean M ember States are estimated to have an annual sewage sludge produ ction of 7 million dry tones.

Germany is the leading producer w ith approximately 2.2 million dry tones, followed by the UK, France, Italy and Spain (EC, 2001). At the Europea n Commission level, a number of Directives are either directly relevant to sewage sludge management or have an influence.

However , the key direct i ve i s

WASTEWATER

86/278/EEC 'for the protec tion of the environm ent and in particula r soil, fro m the use of sewage slu dge'.

Li ke the U S, the EC directive manages contamina nt issues through prescribing ceiling limits in bioso li ds. H owever, th e EC directive also includes soil limits, a key difference with the US. An additional and more significant difference is in the limi ts themselves, with the E C directive limits 10-20 ti mes mo re stringen t that typi cally all owed in the U S 503 ru le. T he working redraft o f the EC d irective fu rth er increases the difference between th e two regul ato ry progra ms, with proposals fo r slightly lower limits and additions to th e number of con ta mi nants.

T he EC directive doesn't provid e defi niti ve direction on the man agemen t of pathogens through treatment, providing only quali tative guidance that sludge needs to be treated " ..to reduce its fermentabili ty and the health hazards ... ". Presumably re flecting th is lack of defi ni tive treatment requ ire m ents, the di rective imposes re lative ly strin gent use controls with restrictions and proh ibi ti ons o n vari o us uses . Th e redraft of the directive is more detailed and ali gns closer w ith the US ap p roac h , defining 'advanced' a nd ' conventio nal' treatm ents th at are a co mbination of prescribed treatmen ts and microbiological cri teria.

A fundamental aspect of biosolids managem ent in 'Europe', is that there isn't a uni fied European position and therefore it is impossible to generically discuss 'E uro pea n' manage m en t. EC (2001) notes that there is a diversity of philosophi cal approaches, with at one extrem e the contaminant limits in the N etherlands so stringent that there has been almost no use of biosolids in agriculture since 199 1. Similarly, in Sweden, the Swedish Federation of Farmers recommended against biosolids use in 1999 due to quality concerns with persistent organic contaminants. In contrast, EC, (2001) describes that public opinion in Germany has recently swung in fa vou r of agricultural lan d applicatio n and in t he U K a consortium of retailers, farmers and Government departments developed a safe-sludge-matrix that allows biosolids use o n all cro p s, b ut co u p l ed wit h m anagement controls. While there is ongoing debate about th e practice in countries such as France, there has b een little debate in other cou ntries including Sp ain and Greece.

Table 1 . Biosolids ceiling limits (mg/ kg biosolids dw) for inorganic contaminants in the draft Australian national guideline, the US EPA 503 rule, EC directive (86/ 278/ EEC), the initial redraft of t he revised EC directive. The table also includes the limit values from the Netherlands, as an extreme example of low limits in selected EC member states.

Contaminant Arsen ic Cadmium Chromium Copper Lead Mercury

Australia National

us 503

EC 86/ 278/ EEC

EC redraft 1

Netherlands

rule

60 20 500-3000 2500 420 15

75 89

20-40 1000-1750 750-1200 16-25

5 /2 800/ 600 800/ 600 500/ 200 5/ 2

15 1.25 75 75 100 1.75

300-400

200/ 100

30

2500-4000

2000/1500

300

Molybdenum Nickel Selenium Zinc

2 70 50 2500

4300 840 57 75 420 100 7500

Table notes 1 . Values refer to proposed ceiling limits for medium term (2015) / long term (2025).

to ri es . H oweve r , a draft N atio na l gui de lin e (N atio n al Water Q u ali ty Management Strategy (NWQ M S): Draft Cu irleli11es fo r Se1verage lvfanage111e11t Biosolirls Ma11.ageme11 t) was distribu ted for

public commen t in M ay of this year. In lieu of the National gui deli ne, the most widely referenced guidance appears to be the New Sou th Wales EP A guideline (NSW EPA, 1997) . T his pu blication was

Australia W ithin Australia, regulatory oversight ofbiosolids management is primarily the responsibility of individual states and terri-

WATER DECEMBER 2002

41

WASTEWATER

supported by a relatively intensive Sydney Water funded research program, so it is not surprising that it appears to have formed a basis fo r guidelines in a range of other States, includin g South Australia (DENR, 1996); Tasmania (D PIWE, 1999); and Wes tern Australia (DEP, 2002). A review of the South Australian guideline is currently being undertaken, while Victoria is undertaking final consultation on its guidelin e (Victorian EPA,.

2002).

As illustrated in WSAAfacts (2001), the proportion of sewage sludge production that is beneficially used as biosolids varies between States and the individual water businesses. Amongst the major water businesses, ACTEW Corporation and Sydney Water reported close to 100% biosolids reuse in 2000/2001, SA Water Corporation reported 152% reuse (due to use of existing stockpiles), while the Western Australian Water Corporation and M elbou rne Water Co rporati on reported 70% and 8% reuse respectively.

Inorganic contaminants While the US, Europe and Australia have some conrn1.onalities in the regulato1y framewo rk and the inorganic contaminants

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WATER DECEMBER 2002

selected for regulation, there are also fundamental and very significant differences. With regard to similarities, the focus is on similar inorganic contaminants, with cadmium, copper, lead, mercury, nickel, and zinc regulated in all jurisdictions.

Other inorganic contaminants, namely arsenic, chromium, molybdenum and seleniu m, are less consistently regulated.

An additional commonality between the US, EC and Australian jurisdictions is the use of ceiling limits that restrict the maximum concentrations of inorganic contaminants that are allowed in biosolids.

These regulated inorganic contaminants and the ceiling biosolids limits are described in Table 1.

Although the use of ceiling limits is consistent, the fundamental differences in regulatory approaches become apparent when the ceiling limits are compared. The US limits are relatively permissive, being typically 2-4 times higher than the lim its in the EC directive and the draft National Australian guideline (Table 1). While these differences exist, the differences between the jurisdictions in ceiling values are of somewhat 'academic' interest, since ongoing improvements in sewer input management mean that the majority of

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current sewage sludge production should be comfortably within the relatively stringent Australian and current EC ceiling limits. Nevertheless, ceiling limits implemented by individual EC member states such as the Netherlands, can be so restrictive that only a low percentage of production is within the limits. The extremely low ceiling limits in the Netherlands re flect a philosophy of managing biosolids land application by maintaining inorganic contaminants in the soil at 'background' levels. The approaches elsewhere in Europe, Australia and the US, tend to derive the ceiling limits based on a combination of good practice (ie what should be achievable) and protecting soils from exceeding risk-based limits under nominal application scenarios.

Of considerably greater practical significance for land application are the receiving soil linuts and 'unrestricted grade' limits that have been adopted in the respective jurisdictions. The draft National Au stralian gu ideline, as with most Australian states, establishes a high quality grade (C l ) that is considered to have sufficiently low levels of contaminants that no specific regulatory controls are placed on the product to control contaminant risks i.e. from a contaminant perspective, the use of the product is unrestricted. The philosophy driving the Cl numerical limits is based ·on protection of a scenario where the biosolids product is land applied to the extent it becomes a topsoil repla cement.

Therefore, the Cl limit is analogous to a receiving soil contanunant limit, with the adopted value representing the most stringent receiving soil linut for protection of the environment, human health (nominally a child ingesting biosolids amended soil) and agricultural produce. In Australia, the proposed environmental and human health values are adopted directly from the Nationa l Environment Prote c tion ( Assessment of Site Contamination) Measure (1999), while limits for protection of agricultural produce have been derived on a case-bycase basis for the protection of food standards.

In contrast to the draft Australian national guideline approach of establishing both an 'unrestricted' grade limit and a receiving soil limit, the European Directive only establishes a receiving soil limit. This is, however, coupled to soil pH restrictions and annual loading rates expressed as kg contanunant/ha/day. The US derived risk assessment based soil limits, but hasn't directly regulated on these linuts, using them in conjunction with nonunal application scenarios to derive their unrestricted grade (EQ)

WASTEWATER

limits. As illustrated in T able 2, the US EQ limits and the derived risk based soil limits are typically 10- 20 ti mes more perm issive than the limits imposed in Australia and E urope.

Th e maj or diffe rences between the U S and the E uropean/ Australian limits reflect th e di ffering basis fo r th e regulatio ns. As a simplistic su mmary, the U S E PA n1.ethodology foc used o n a risk assessm ent approac h , w hereby various algorithms were used to assess potential risks to plants, ani mals co nsuming biosolids ame nd ed soils, childre n ingestin g bi osol ids and consu me rs of plant and meat produ cts.

The U S EPA attempted to account fo r the low er bio-availability of metals in biosolids and bi osolids am ended soils compared to o th er matrixes, and therefore fo cused heavily on 6eld trials. Pot trials using metal sal ts, w hich tend to overestimate bioavailability, were avoided w he re poss ibl e.

Whil e th e philoso p hy dri vin g th e approach has a strong scienti6c basis, the assu m ptions underlying the 503 ru le have been subj ect to signific ant c riticism s fro m autho rs such as McBride (1995; 1998). K ey amongst the concerns of these au thors is: 1) the selec tion o f relati vely resistant plant species for uptake studi es;

Table 2. Soil limits and 'unrestricted grade' biosolids limits for inorganic contaminants (mg/ kg dw) in the draft Australian national guideline, the US EPA 503 rule , EC directive (86/ 278/ EEC), the initial red raft of the revised EC directive.

The table also includes the limit values from the Netherlands , as an extreme example of low limits in selected EC member states.

Contaminant

Australia National1

US 503 rule 2

Arsenic Cadmium

20 1

Chromium

100-400

Copper Lead

100 150-300

Mercury

1

EC 86/278/ EEC3

EC redraft 3

39

1-3

1500 300 17

50-140 50-300 1-1 .5

0.5-1.5 30-100 20 -100

41

70-100 1-1 .5

Molybdenum Nickel

60

4 20

30-75

15-70

Selenium

3 200

36 2800

150-300

60-200

Zinc

Table notes 1 . Australian draft national guideline limits are both the receiving soil limit and the 'unrestricted' grade limit. They are expressed as a range to enable some flexibility in the deve lopment of state specific guidelines.

2. 503 rule limits are t he Exceptional Quality grade limits, wit h the soil limits derived from risk assessment included in brackets.

3. EC limits are linked to soil pH.

2) w hether evidence of short term redu ctions in bioavailability would continue

into the long term; 3) a bias tow ards no nac idic so ils; and 4) issu es such as th e use

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WASTEWATER

of 50% effect levels and geom etric m eans of data , rather than fo cusing o n th e m ost sensitive species.

In contrast to the US EPA algorithm approa ch and a focus on data fro m biosolids fie ld trials, the E C directive and m ember states such as th e UK have fo cused on p rotectio n of th e 1nost se n siti ve c ompon ents of t h e s o il ecosystem , such as microbiological p rocess and pla nts. Lowest o bserved effec t conce ntrations (LOE C) were typically used , som e based on pot trials with meta l salts. Attempts w ere made to account fo r alteratio ns in bi oava ilabili ty in different soils, by linking selected limit values with pH. The inorganic limit values referenced in Australian guidelines tend to reflect this app roach , although research trials in th e 90's supported the develo pment of th e NSW gu ideline . T he protection of food standards, especially cadm.ium , has also bee n a key dri ver w ithin Australia and Eu rope, but wasn't directly taken into account in the U S. The future There are some uncertainties regarding fut u r e d irec ti o n s of in t e rn ati o n al regulatory o versight of biosolids land application, with the early drafts of the EC directive proposing reductions in the current levels (T ables 1 and 2). If un iversally adopted, the phased introdu ctio n o f the ceiling limits and soil limits could significantly reduce the amount of current production that can be utilised . However, it is important to acknowledge that: 1) the limits in the early drafts have not been supported by a transparent 'effects' based assessm ent; and 2) the p roposals have not yet reached a fo rmal draft and spirited discussion would be expected during co nsultation w ith the m ember states. It is also important to note that eve n if a redu ction in metal limits did eventuate, this may not lead to a drive away from the land application managem ent ro ute, since additional p ressures have also been brought onto landfill and incineration disposal options .

T he NRC review of the 503 rule w as not intended to evaluate the appropriateness of the approach used to derive the inorgani c standards and therefore the recommendatio ns neither criticised nor endorsed the current requirem ents. T he r ecom m en d ati o n s did , h owev e r, concluded that risk assessm ent m ethodol og i es had ev ol ve d s in ce t h e development of the 503 rule and suggested that a revised multi-pa th w ay risk assessm ent sho uld be perform ed. As the review noted, this could theoretically result in limits for individual contaminants staying the same, increasing or decreasing.

44

WATER DECEMBER 200 2

Within Australia, there appears to be widespread regulatory support for the p rotectiveness of the lim its p roposed in the N atio nal guideline and reflected in indi vidual state guidelines. Indeed , there have been recent moves to exam.ine potential relaxation of the limits fo r copper and zinc, particularly in relatio n to composted products. However, there have also been co ncerns at potential issues with . cadm iu m M PC exceedences in crops grown on soils followi ng heavy phosphatic fe rtilize r use and exceedences in som e cadmiu m spiked biosolids field trials (M cLaughlin et al. , 2000). As a result of th ese issues, a N atio nal research p rogram coordinated by C SIRO Land and W ater is being developed , targeted at the development of bi oavailability indexes fo r cadmium , copper and zinc. Th is data sho uld ultimately enable mo re effective regulation of these compo u nds, rather than a reliance on measu res such as total metal concentrations.

Organic Contaminants While there are som e similari ties between the EC, US and Austral ian app roac h es to regulatin g ino rga nic contaminants, the approaches to organics are almost devoid of synergisms. Within th e Au stralian guid elines, limits on organochlorine pesticides and polychlori n a t e d b i ph e n yls ar e presc rib e d , principally fo r the pro tectio n o f fo od standards in conjunction wi th cattle grazing. [n contrast, the current EC directive does not include limits on organic contaminants, but there are a variety oflimits for organic contaminants with in m emb er states. As examples, Ge rmany and Austria are the o nly countries to im pose limits on dioxins, D enmark regulates lin ear alkyl benzene sulphonates (LAS), while Sweden is the only co untry to specifically regulate toluene (EC, 2001).

The US explored the risks associated with organic contaminants in the so-called R ound O ne (U S EPA, 1995) and Round T wo assessm ents, completed respectively in the ea rly and mid 1990s. Both assessm en ts started w ith large numb ers of candidate chemicals, with 400 chem icals considered in round 1 and 200 chemicals in round 2. Chemicals were then removed fr om the assessm ent based on sewage sludge analytical data coupled w ith a combinatio n of exclusion rules, screening and fo rmal risk assessm ents. At the completion of the processes, regulatory interve ntion was only co n sidered warranted for the inorganic contaminants

discussed ea rli er and for compo un ds with dioxin-like- activity (NRC, 2002) .

H oweve r , limits fo r d i ox in - li ke c o mp o und s h ave n o t ye t b ee n promulgated within the 503 rule .

The future As with inorganic chemicals, the early drafts o f the EC d irective have caused some concerns regarding the potential impacts of proposed organic limits fo r land application . Limi ts are proposed for a range of o rga nic compo unds, including LAS (2,600 mg/kg biosolids dw) and endocrine disrupti ng chem.icals such as nonyl p henol ethoxylates (NPE) (50 mg/ kg biosobds) and dioxins (100 ng total equi va lency/ kg). While the lim its fo r dioxins w ould no t typically co nstrai n th e use o f European biosolids, if adopted, the limits for compo unds such as LAS and NPE would be likely to exclude a large perce ntage o f anaero bically diges ted sludge. T he likelihood that the directive will ultimately regulate these compo un ds at the proposed levels is uncertain, particularly given that the current drafts of th e directive have not yet en tered a formal consu ltation process. Th e scientific basis of the limits is not transparen t, but given a n umber of rece nt reviews that have suggested relatively low risks associated with o rga nics such as LAS and NPE (eg H ellstrom, 2000; Guardia et al. 2001; Langenkamp and Part, 200 1; W E AO , 2001), sc ientific data may no t have dri ve n t h e i n i t i a l limi t va l u es .

N evertheless, organic co ntaminants in biosolids will remain an impo rtant issue, as il lustrated by the no-grazing recomm endations fro m the fa rm ing association in Sweden, a recommendation attributed to the repo rts o f persisten t organi cs such as polybrominated diph enyl ethers and po lyb rominate d biphenyls in sewage sludge.

Within the U S, th e only curren t proposal to regulate organic chemi cals is for those with dioxin-like-activity . A recently released Notice of D ata availability (U S EPA, 2002) outlines the recent h uman health risk assessm ent process and the conclusio n that current levels of dioxins in sludge pose an extrem ely low risk even under the rela tively hi gh e:xposure scenario considered - a far m family surrounded by biosolids amended fields and consumin g a high prop ortio n o f produce fro m the fields. O n this basis, t h e U S E PA r eq ues te d comme n ts regarding the need or otherwise to specifically regulate dioxins.

Although it therefore appears unlikely that the 503 rule will, in at least the near future, include limits fo r organic contam-

WASTEWATER

inants, the longer term is less certain. Th e NR C rev iew rai sed so m e co n cerns regarding th e process used fo r excl uding organ ics from th e 503 rule . T he NRC concern s prim aril y related to anal ytical methods used to quanti fy selected organics fo r risk assessmen ts, exclusio n ru les used to remove som e contami nants (eg < 10% detection frequ ency) and th at th e assessm ents d idn ' t address some co ntaminants that have more rece ntly b een raised as potential conce rns. As a result, th e NRC recomm ended that the assessm ent process be reviewed and updated.

The direct significance o f alterations in EC and U S biosoli ds regulatory co ntam inant lim its to Au stralian regulatory programs may be li mited. T o an ex tent, international regulato ry limjts will refle ct philosophi ca l, po litical and practical issues and therefore it wi ll be importa nt that the Austra li an regulatory programs exa mine th e underlying scientific basis for the requirem ents, rath er than foc using on the ' magic numbe rs'. T o an exte nt, the ava ilable informati on and recent rev iews do no t suppo rt th e need fo r di rect action on contaminants such as LAS, o r a generic reductio n in inorga nic contamj nant lirnjcs.

N evertheless, it is important that the ongoing research and regulatory initiatives continue to be monitored and interpreted, such as through the formation of an expert working group recen tly discussed at the AW A bi osolids sp ec ialty con fe ren ce (Sydney, July 2002). W here issues relevant to Australian biosoli ds managem e n t are identifi ed , targeted research and investi gative pro gram s th e n need to be im plem e nted. Ensuring sustai nable land application of biosolids will also requ ire o ngoing impro veme nts in se wer inputs, through cl ean e r produ ction and other trad e was te initiatives and t hro ugh targe ti ng of do m es tic an d indu strial che micals that pose risks to biosol ids manage me nt. As an exa mpl e, E C, (200 1) cites redu ctions in biosolids cadm iu m co ncentration , fro m typi cal levels of 3-6 m g/ kg to below 1 mg/ kg, in Eu ropean countries that have implemented domestic and indu stri al cadm iu m source control programs.

Summary Th e int e rn ati o nal r eg u lat o r y approac hes for managem en t of p otential contami nant and pathoge n issues are typically poo rly harmonised and subj ect

to a range of poli ti cal and philosophical drive rs. Proposals in ea rly redrafts of the EC directi ve point to a tighteni ng of their relatively stringent inorganic contamjnant standards. Similarly, the redraft introd uces a range o f organic contaminants for pote nti al regu latio n and associated with p ro pos ed li mits that wo uld res trict quantiti es o f bi osolids able to be land appli ed. H owe ver, the relevance o f the draft lim its is un certain , since the drafts have not undergon e formal consultation with in th e EC and a range of inform ation suggest th e proposals may not be based o n scie ntifi c assessme nt. Although the NRC review o f the U S 503 rul e recom m ended that the risk assessm e nt process be updated , the current relative conse rvatism between th e Australian versus US approaches suggests any U S revisio ns would still be less stri ngent than current Australian li mits.

T he challenge fo r Australian biosolids management will be to monjtor the developme nts in in te rnational regu latory approac hes, but recognising th at policy and political dtivers influence international d ecisions, and the refore fo cusing our atten tio n o n the und erlying science supporting the decisions.

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WASTEWATER

A further paper discussing regulations for control of pathogens wilJ be submitted for a future issue of Water.

References DEP (2002) W estern Australian guidelin es for direct land application of biosolids and bios o l i d s produ c ts . D ep a rt m e nt of Environmental Protection, Water and Rivers Commission, D epartment o f H ealth.

D PIWE ('I 999) Tasmanian Biosolids R euse Guidelines. D epartment of Ptimaiy Indusnies, Water and Environment.

E C (2001) D isposal and recycling routes fo r sewage sludge. European Commission report prepared by Arthur Anderson and SEDE. Guardia M J , H ale R. C , Harvey E . and Mainor T M (2001) Alkylphenol etho;,..')'late degradatio n produc ts in land-applied sewage sludge (Biosolids). E1wiron111eutal Scie11ce mid Technology 35 :4798-4804.

H ellstrom T (2000) Brominated flame retardants (PBDE and PPB) in sludge - a problem? The Swedish Water and Wastewater Association.

April 2000, Report No M 113.

Langenkamp H and Part P (2001) Organic contaminants in sewage sludge for agriculture use. European Commission Joint R esearch Centre, Institute for Environment and Sustainability. O ctober 2001.

McBride MB (1995) Toxic metal accumulation from agricultural use of sludge: are USEP A regulations protective? joumal ef Enviro11111enral Q uality 24: 5-18.

McBride M B ( I 998) Growing food crops o n sludge amended soils: problems with the U .S. Environment Protection Agency m ethod of estimating toxic me tal transfer. E1111iro11111c11tal ToxicoloJ!y a11d C/ie111isrry 17(11) : 2274- 2281.

M cLa ughlin MJ, H amon I~ E, McLaren R G , Spier T W and R ogers S L (2000) Review : A bi oava il ab ilicy - bas e d rati ona le for controlling metal and me talloid co ntamination of agricultu ral land in Australia and New Zealand. A11srrnlim1 Jo11mal ,if Soil R esearch 38:1037-86.

NSW EPA ( 1997) Environmental Guidelines: U se and disposal ofbiosolids p roducts . N ew So uth Wales E n vironment Protec tio n Authority.

NRC (2002) Biosolids applied co land: advancing standards and practices. National R esearch Council. Prepublication copy. National Academy Press, Washington DC. SA EPA (1996) South Australian biosolids guidelines for the safe handling, reuse or disposal of biosolids. South Australian Environment Protection Authority, D epa rtme nt of Environment and Natural l'.tesources.

US EPA (1995) A guide to the biosolids risk assessments for the EPA Part 503 rnle. United States Environmental Protection Agency, Office ofWastewater Management. EPA832B-93-005.

US EPA (2002) Standards for the Use or Disposal of Sewage Sludge; Notice. Federal Register/ Vol 67, No . 113, W ednesday June 12, 2002.

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Vesilind P A and Spinosa L (2001) Productio n and regulations. /i1 Sludge into Biosolids: Processing, Disposal and U tilization. C hapter 1 (Eds Spinosa L and Vesilind PA) !WA Publish ing, Londo n pp 3-18.

Vi ct orian E PA (2 0 02 ) Guidel in e fo r Environ m ental Management: Biosolids land applica ti o n (Oc tobe r Draft). Vi cto rian Environment Protection Authority.

WEAO (200 1) Fate and significance ofselccred Contaminants in Sewage biosolids applied to agricultmal land through literature review and consultation with stake holder groups. Water Environment Associatio n, report prepared by R V Anderson Associates, M D Webber and SENES Consultants.

WSAA (2001) WSAAfacts -T he Australian Urban W ate r Ind ustry. W ater Se rvices Association of Australia.

Acknowledgements T he author thanks David Gregory of Melbourne Water and D aryl Stevens of CS IRO for comme nts on the draft of th is paper.

The Author Dr Hamish Reid (hami sh.reid@ epa.vic.gov.au) is a Project Manager with the Victorian Environ ment Protection Authority, involved in progra1ns including biosolids and wastewa ter management.

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46

WATER DECEMBER 2002

B

WASTEWATER

OPTIMISING BIOLOGICAL NUTRIENT REMOVAL AT AN INTERMITTENT SEWAGE TREATMENT PLANT: USE OF ON-LINE ANALYSERS PR L Mosse Summary The potential fo r improved bi ological P re moval was investigated in one cell of an Interm ittently D ecanted Extended Aeration (IDEA) plant. O n-li ne analysers (NH 3 , NO_1 and P) were used co provide real ti me data to all ow prompt an alysis of process changes. T he N H 3 analyser was also used co control the plant res ul ting in a sign ifican t red uction in cotal aeration t i me, amm on ia d isc h a rged to the environ ment and a real time response to variable influent loads. The tria l demonstrated that removal of P to 0.5 mg/ L is possible, in an I DEA system , provided sufficient readily ava ilable CO D can be suppli ed.

Table 1. Influent characteristics at the Moe STP. Data is for composite samples for the period 1/ 1/ 2000 until 31/ 10/ 2001. All data was analysed at the plant using Merck analytical kits. Soluble COD (SCOD) was determined after passing the sample th rough a 0.45 µm filter.

Samples

Mean

90th percentile

Alkal inity (mg/ L CaC03 )

32

165

196

Ammonia-N (mg/ L)

75

28

35

COD (mg/ L)

77

425

574

SCOD (mg/L)

78

215

280

Total P (mg/L)

85

7.5

9.9

and chemi cal rem ova l of phosphorous, reflecti ng the general practice in Australia at the time .

The upgrad e was co mplet ed in Occobe r 1996. T he new plant consisted of 3 IDEA cells, 2 anaerobic se lectors, lime dosing fac ilities an d UV disi nfection of the final effiuent. T he lim e dosing was included to prov ide add itiona l alkalinity once iron salt dosing co m menced for P re mova l.

The plant was designed for an average daily flow of 6.5 M L/ d duri ng summ er and 9 ML/d during winter with the capacity to handle peak flows co 17 M L/d using a lagoon bypass system . Influent characteristics are shown in Table 1.

The EPA licence req u irements for the fina l eillu ent are shown in Table 2.

The plant was commissioned and operated with a co nventional l DEA sequence of two hours aeratio n , one hour settle and one ho ur decant. Effiuent quality quickly complied with BOD, SS

and N H 3 limi ts . Ni trogen re moval , however, was not always satisfactory.

R.em oval was enhanced in n1.id 1997 by the in troduction of a den itrifi cation (D N) period after the aeration pe riod Introduction (Wh ite 1999). This period consisted of Modern activated sludge processes short bursts of aeration (0.4 minu tes every ca n be divided into two operationall y 10 minutes) designed to keep the biomass different types, the so-ca lled continu ous in contact wi th the fu ll vo lum e of a n d intermittent processes . In th e liquor. These intervals were established by continuou s process, cond itioned sewage direct observation of th e biomass du ring is passed through separate zones each with the DN period. Eilluent nitrate redu ced dedicated chem ical and physical cond iafter the introducti o n of the DN period tions. In the intermittent process all from a m ean 7.8 mg/ L to a mean of 1.6 treatment occurs in a si ngle reaccor and mg/ L (W hite 1999). reaction conditions are varied over ti me.

T he current timed cycle is typ ically: E nh a nc ed Bi o lo g ica l Phosp h o ru s Aeration 85 minutes, DN 30 m inutes, Removal (EBPR) was originalJy achieved Settle -10 mi nutes and Decant 85 minutes. in continuous process plants. T he interTh e cycle is repeated 6 times per day and mittent process has been used successfull y th ere is no provision co va ry the cycle. to re move nitroge n for so me time, The cell cycles are staggered so that no however unti l relatively recently, it was two celJs discharge concu rrently. thought incapable of EBPR. Several Since commissioning of the plant there m odifications to the i ntermittent has been a substantial amount of research Seq uen cing Ba tch Reaccor (SBR) and work undertaken o n EBPR. Intermittently D ecanted Extended (A WW A 1997 (b) , P ilkington , Aeration (IDEA) processes have Table 2 . EPA Licence req uirements for the Moe STP. N .H . and Bayly, R.C. 199-1). A been trialed to improve P removal. project was in itiated co investigate 90th percentile Median Planning for the upgrade of the whether improved EBPR was BOD (mg/L) 5 10 M oe Sewage T reatment Plant possible in this plant.

(STP) commenced in the early SS (mg/L) 10 15 Facto rs known to inhibit 1990's when there were few E. coli (orgs/100ml) 200 1000 EBPR. include phosphorus removal plants in Total P (mg/L) 0.5 1 • Nitrate (NO3) in the anaerob ic Australia. An inte rmittent IDEA Total N (mg/L) 10 15 phase plant was selected and designed for Ammonia N (mg/L) 2 5 • Low pH the biological removal of nitrogen WATER DECEMBER 2002

47

WASTEWATER

• Low alkalinity • Lo n g sludge age • Dissol ved O xyge n 111 the anaerobic phase • Low R e adi ly A v ailab le C OD (RACOD) • Poor contact of bio mass with influ ent sewage duri ng th e anaerobic phase.

T he proj ect aimed to improve P rem.oval by reducing the impac t of each o f th ese facto rs as fa r as possibl e within the constraints of a functioning full scale plant. T here was also a requirem ent to meet an EPA d eadline fo r co mpliance w ith the discharge li ce nce.

Any proj ect of this nature requires mo n itoring data to evaluate the effect o f process changes on th e effluent quality.

Traditio nally this is collected by field staff analyzing grab samples during normal w orking hours. The number o f samples an d to tal cove rage ou tsid e n o rmal w orking hours can be increased by using auto sampl ers. H owever, data co!Jection is still limi ted by what can reasonably be expected of plant staff and ca n seldo m be sustained beyond a couple of weeks. Online analysers provide a uni que way to gather real time, co nti nu o us data fo r lon g peri ods of time.

Two Bran & Lu ebbe o n line analysers (NH 3 and P) and two STI P o n line analysers (NH 3 and NO 3) 1,vere installed to enabl e collectio n of co ntinuo us data.

Modified Control Philosophy

The fi xed cycle regime of the basic IDEA plant severely impacts on efflu ent quality, energy co nsu mp tion and P rem oval. During daily peak load periods th e aerati o n p erio d is seldom long en o u gh to convert all ammon ia to

10.!50

.

.

i.:•~.r ::.··,:""'· ;___ .,,..->--....:._--~ '"'"- . _ -...,.--TT' ,...~"'

7000

0000 22:2'5:00

""'*2000

Figure 1. Normal IDEA cycle showing high ammonia levels during some decants.

The decant periods can be identified by the periodic decrease in ce ll level. The vertical scale for ammonia is 0 - 14 mg/L. The horizontal scale is 48 hours.

nitrate, resulting in elevated NH 3 in the decant (Figure 1). In contrast during the non-peak flo w periods the aeration cycle is lo nger than necessary and converts all ammonia to nitrate at a time when the incoming C OD may be insu ffic ient to support full denitrification. Ammonia re moval is co mplete well before the end of the aeratio n cycl e under these circumstances (Figure 2) . It is also li kely that during these low flo w periods available COD is effec tively wasted by overae ration. C lea rly th e length of the aeration cycle h as an impac t o n P rem o val by effecting available C OD, Nitrate levels and Dissolved O xygen (DO).

T he basic premise developed was that if the aeration period could be reduced

to a minimu m, C OD co uld be preserved fo r both DN and P rem oval. T o this end the PLC program for one of the cells was m odified to control the aeration period based on the NH 3 levels as m easu red by th e o nli ne analyse r. Aeration was continu ed until the NH 3 level reached an operator defined set point. (A se t point of 1. 5 mg/L was used in th e experim ents reported h ere.) T h e PLC program included an algorithm , based o n cell rise rates, to ensure that the cell did n ot overtop during the long aeratio n cycles associated wi th the morning peak. Thus the program allowed the in flo w to the plant to determine cycle times based on the load of NH 3. The flex ibl e control program was therefor e able to accommodate da ily, wee kly an d seasonal variations. T he flexibl e aeration period 1-4.00

.

, ., ___ ·· --:

__ ....

-',,-

......

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

.

.

'

'

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7000

.....

0.000

Figure 2. Norm al IDEA cycle showing NH 3 remova l is complete before the end of the aeration period during all but the peak daily flows.

48

WATER DECEMBER 2002

Figure 3 . Instrument controlled IDEA cycle showing contro lled and consistently low ammonia levels of all decants. The trends shown here should be contrasted with those shown in Figure 1 . The decant periods can be identified by the periodic decrease in cell level. The vertical scale for ammonia is 0-14 mg/L. The horizontal scale is 48 hours.

WASTEWATER

was followed by a fixed DN, settl e and decant period as described above. The program also included a requirement fo r a minimum aeration period of 10 minutes even if the ammonia level had not risen above the sec point at the completion of any cycle.

Once a minimum NH3 level was reached aeration ceased. The elongated aeration period during the peak load and the shore aeration periods during low load have ensured that NH3 levels in the cell are consistently less than 1.5 mg/L (Figure 3).

Solids Contact

E arly in 19 97, the concept of improving contact between the influent and active biomass to improve P removal was raised (Jurg Keller pers. comm.).Over a period of years this concept was refined and a decision made co incorporate distribution pipe manifolds into the bottom of the three cells. This project w as undert a ken in co njun c t ion wi t h the Cooperative R esearch Centre for Waste Manageme nt and Pollution Control which provided the license for chis UniFed process technology co Gippsland Water. The manifold system consists of four 200mm diameter PVC pipes running longitudinally in the cell. The fa r end of the pipe is reflected to the surface of the cell and remains open to the atmosphere to facilitate cleaning. H oles (35 mm) are drilled at 1.5 m intervals and directed vertically downwards, thereby directing the flow of influent coward the bottom of the cell and then upwards through the biomass Since the installation of the manifold system, the experimental cell has been operated without RAS, thereby adopting the principles of a horizontal selector (J urg Keller, p ers. comm). The brief trials that were carried out suggested no apparent difference in performance of the plant in th e presence or absence of RAS.

Table 3 . Effluent quality before and after the addition of the manifold feed system .

Results are mean and standard deviation {brackets) and number of observations .

Before

After

N-NH3 (mg/ L)

1.8 (1.4) 25

2.1 (1.1) 19

N-N03 (mg/ L)

1.9 (1.2) 25

3.4 (1.2) 19

P-P0 4 (mg/L)

4.7 (0.4) 25

4.1 (1.2) 19

low alkalinity might be inhibitory to both DN and P removal. Lime dosing was initiated to achieve a final pH of between 7.0 and 7.2.

Sludge Age

The plant was originally operated with a Mixed Liquor Susp ended Solids (MLSS) of between 3000 mg/L (summer) and 3600 mg/L (winter). This has been progressively reduced co around 1800 mg/L to try to improve P removal. At 1800 mg/L the sludge age is approximately 21 days.

Results and Discussion Effiuent qu ality from the experimental cell, before and after installation of the manifold system , and p rio r to the implementation of the modified control regime is shown in Table 3. The decant effiuent sampled for the analyses was generally the one occurring after the morning p eak so the results represent performance during p eak daily load conditions. No statistical analyses have been made . Comparison of the results suggests little overall difference in the quality of eilluent after the addition of the manifold feed system. The slightly lower phosphorus may simply reflect the slightly

lower influent P during the period after the installatio n (results not shown).

After the introdu ction of the instrument control system , ammonia levels in the decant were consistently less than or eq ual to 1.5 mg/ L. The data in Table 4 sh ow a comparison of the loads of ammonia discharged to the receiving environ ment during normal control and instrumental control. Significant reduction is evident.

It should be pointed o ut that under the present license the normally controlled plant complies with the licence requirement fo r NH 3; however the plant is clearly ca pabl e of i mproved and consistent effiuent quality.

The table also shows a significant reduction in total aeration time. This reduced ae ra tio n tim e was actually associated with a better quality effiuent.

Over an extended period of time this may translate to reduced blower operational costs.

Phosphorus

Biological P removal requires alternating anaerobic and aerobic periods.

Under anaerobic conditions in the presence of a ca rb on so urce, the Polyphosphate Accumulating Organisms (PAO) consume COD and intracellular glycogen, sy nt h es ise Poly Hydroxy Alkanoaces (PH A) and release phosphate to the surrounding medium. During aerobic conditions the stored PHA is used to replenish glycogen levels and to synthesise polyphosphate by removing phosphate from the surrounding medium.

Under the right co nditions the net uptake of P is greater than the release, leading to enhanced P removal. Figure 4 shows a typical P trend from the on line phosphate analyser. Careful examination of the P trend and the DO trend suggest that the P release is occurring during

Moe STP Cell 2 1'1Mi...O Of I' RUIAM WITM AIAATJ()H

COD Availability

, u oo

,o oa

JOOO

IOOO

Cell Level

In an attempt to increase the supply of COD to the experimental cell the RAS flow has been maintained in the other two cells, thereby directing more of the influent to the experimental cell. pH Cont rol

As a result of the low alkalinity waters in Gippsland, influent to sewage treatment plants also has a low alkalinity (typically 150 to 200 mg / L as CaCO 3).

Consequently the activated sludge process tends to operate at relatively low pH. Prior to the addition of lime, the Moe STP operated at a pH in the range of6.4 to 6.6. It was felt that this low pH and

1000

uoo

,, ..

0000

0000

0000

Figure 4. Trend showing the relative timing of P re lease and upt ake with periods of aeration. The vertical scale for phosphorus is 0 - 10 mg/ L. The horizont al scale is 24 hours.

WATER DECEMBER 2002

49

WASTEWATER

Table 4. A comparison of loads of ammonia discharged to t he receiving environment, and total aeration t ime, before and after introduction of the instrument control. Data in the t able relate to decants occurring over two 48 hour periods.

Instrument Control

Normal Control Cycle

Decant NH 3 mg/ L

Aerate Time mins

Decant Flow L/s

Load g

Cycle

Decant NH 3 mg/ L

Aerate Time mins

Decant Flow L/ s

Load g

1 2 3 4

4.8 3 3 1.3 4 3.2 1.8 1 .8

85 85 85 85 85 85 85 85

70

1673 971 9 71 194

1.8 1.1 1.1 1 .1 0.9 0 .9

118 100 42 25 17 10

0 .9

17

85 60 50 20 20 20 25 100

1 083

1

85 85

65 65 30 25 100 65 60 50 20

1 2

5 6 7 8 9 10 11

0.5 0.5

85 935

aeration rath er than duri ng th e no n aerated periods as expected. This apparent anomaly is an artifact of the system. The phospho rus anal yser sam.ples from a d epth o f around 1 metre, however during most of the se ttle perio d and all of the deca nt period th e sludge is approximately 3 m etres fro111 the surface. P release is occurring in the sludge. Only when aeration co111111 ences and m ixing occ u rs does th e analyser detec t the elevated P . This also means that the degree of release is greater than the trends suggest, since the released P is diluted durin g the mixing with the full cell contents. T hese results clearly demonstrate that biological P release and uptake is occurring in this single tank IDE A syste m using the manifo ld.

Figures 5 and 6 show phospho rus removal d uring periods of normal IDEA control and periods of instrument control.

Decant P during instrument con trol averaged 2 .8 m g/ L (Influ ent P 7-8 mg/ L) (n= 16) compared to an average o f 6.6 mg/L (Influ ent P 8-9 mg/L) (n= 12) during period s of no rmal control.

AlJowing for the diffe rent influent P levels, P removal during the normal control was around 22% w hilst during instrum ent control rem oval was around 63%.

While the increased P rem oval was worthwhile, the process control described above optimised N rem oval but may not have been optimum fo r P remo val. For instance, som e of the aeration cycles are probably too short fo r good P uptake .

This is w ell illustrated in both Figures 4 and 6 where the P level dropped alm ost 50

WATER DECEMBER 2002

498 1594 583 538 249 50 50 7370

20

3 4 5 6 7 8 9 10 11 12 13 14 15

1 1 .1 1.1 1 0.85 0.4 0.1 0.1

50 110 100 30 17 10

10 30 686

396 139 33 18 11 23 300 436 429

60 65 50 20 20 20 25

90 17 5 1 5 2985

Moe STP Cell 2 TIMl"IGOf P Rt'.LE4 8f: WITH AERATION

I Cel l Le\'CI

I

~~~

1000

15 000

'>lit

, occ

noc

,,..

coco

CIOOO

0 000

Figure 5 . P levels in the experi mental IDEA cell during normal control. Influent P during th is period was around 8 to 8.5 mg/L. The decant periods can be identified by the periodic decrease in cell leve l. The vertical scale for phosphorus is 0 - 20 mg/L. The horizontal scale is 48 hours.

Moe STP Cell 2 P LIVl ~I OIJIIIINO INIT,-UMINT COHT,-~ ,000

"'" IOOO

â&#x20AC;˘ 1""10

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-

10IO

1100

Âť11

1000

10.00

Figure 6. P levels in the experimental IDEA cell during instrument control. Influent P during this period was around 7 .5 to 8 mg/ L. The decant periods can be identified by the periodic decrease in cell level. The vertical scale for phosphorus is 0 - 20 mg/L. Th e horizontal scale is 48 hours.

WASTEWATER

proportio nal to the duration of the aeration cycl e.

Th e effect of pH was difficult to quanti fy . On-Lin e data suggested that small drops in pH were assoc iated wi th a rise in effiu e nt P leve ls. T hus initially it ap pea red that P removal was improved with elevation of p H to around 7.1 to 7 .2 in the ce!Js. Careful analysis however sh owed that the inc reased lime dosin g required to achi eve this elevation in pH in th e cells was sufficient to cause the p H in the in flu ent pipeline and selectors to reac h pH 10 for short periods. J ar resti ng revealed that this was sufficient to ca use che mi cal P removal.

With all the process m odifica tions trialed , th e experim en tal IDEA ce ll was ab le to reduce P to approximate ly 2.8 mg/L bur no lower. The plant see med to be RACOD limited at this stage . Aceta te dosing was introduced to the expe1imental ce ll. Doses of acetate of 300 ml/min an d 400 mL/ min were rrialed. Dosing was initially carri ed our for th e entire cyc le; however this was modifi ed so that dosing on ly occurred durin g the no n aerated pe riods. T his was do ne ro limi t wastage of the added KA COD that wo uld occ ur during the aeration pe riod. In this way the total amou nt of acetate dosed cou ld be reduced. The dose is expressed as mL/ m.in rath er than as a con centration sin ce the fi na l conce ntration is dependen t on the in flows. At 400 mL/ mi n approximately 375 litres w e re dosed per day, and at 300 mL/ min 280 litres were dosed per day.

A logical extension of this work wou ld have been to fl ow pace th e dosing to better direct the acetate at appropriate times in the day, however this was no t done du e to th e need to finalise the proj ect.

Figure 7 shows on-line analyser P tre nds for a period of 1 month during which time a number of trials were Lmderraken. Th ese included: 1. Aceti c acid dosed at 400 mL/ mi n.

2. Acetic acid dosed at 300 mL/min 3. No dosing 4. Iron salt dosing at 62 mL/ min.

T he figure shows a dose dependent resp onse with more P removed at th e highe r aceti c acid dose . Once the acetic acid dosing was stopped the P removal reduced dramati ca!Jy in 2 to 3 days and returned to predosing levels within 5 to 6 days (Figure 7) . Figure 7 also shows the effect of iron salt dosing.

Th e trials to date have shown that P removal to 0 .5 mg/ L, or less, is possible in this intermitte nt plant so long as sufficient COD is availabl e (Figure 8). In the

current plant, th is is limited by the fact th at th e influe nt is conti nuously flowing into eac h cell througho ut the compl ete cycle. A better option would be to direct the sam e net flo w co the cell durin g th e a n ae r ob ic p e riod s o nl y, thereby maxim isin g th e RA COD availab le from th e plant in flue nt for P re moval. T his is ind eed part of th e Un iFed process co ncept togethe r with th e feed manifold system. Howe ver, it was not practically feasible to achi eve this modifi cation at th e Mo e plant in th e rime available. Th e impro ved P re mova l capacity during the trials with th e RA C OD addition would suggest ch ar the lac k of RACOD in the anaerobic pe riod was likely to be the major li miting factor in achi evin g optimal P removal.

In a study of bacterial popu lations in full scale EBPR plants in Au stralia, Oeh me n et nl (2002) fo und distinct popu lati ons of Glycoge n Accu mulating Organisms (G AO) and Po lyph osphate Acc um ulatin g Organism s (PAO) . In genera l plants achi eving high levels of EBPR were associated with larger populations of PAO 's. The auth ors measured a number of di fferent parameters whi c h have been used to charac terise PAO and GAO 's. These included P release to ace tate uptake ratios and the proportion of P H A's as po ly hydroxy butyrate (PHB) and poly hydrOA')' valerate (PHV).

O e hm en et nl (2002) included two of the cells from the Moe STP in their study, nam ely the expe rim e ntal ce ll and a normal cell. Th e exp erim e ntal ce ll afte r

Moe STP Cell 2 ACETAnlhTRIAl.9

19 00

3115N

5.0 00

111!19

. ..... ·•·····

.

'-~

~

...

;

.,,.,<,:,.,---- ---::.,;-;-,,:';;.,,----'------,,.:--::.,.:-c.,,-------,,.cc,=-c ,.,e -----.J..L.,,...,J 08Qil/'Jl001

0)(H)'l 001

2!loC8l'20Di

17,CW2001

Figure 7. P trends during a 1 month period. The events recorded in the trend include from left to right: • Acetic Acid dosing at 400ml/ min during settle and decant.

• Acetic Acid dosing at 300ml / min during settle and decant.

• Acetic Acid dosing off.

• PFS (Fe) dosing at 62 ml/min .

The vertical scale for phosphorus is O - 20 mg/ l . The horizontal scale is one month.

MoeSTP Cell 2 ACETATE 006INO 400ml..fmlfl ST"'9LE P

' '

'

········r '

I 1· ..

' '

, : , . . ..

~'"F"'~='F'F~"""'.~,,~~···· 5,0 00

11N

:

;

;

i

.

:~

.

:

:

·-

Figure 8. One week trend showing stable decant P levels during acet ic acid dosing at 400 ml/ min. The decant periods can be identified by the periodic decrease in cell level. The vertical scale for phosphorus is O - 20 mg/ L. The horizontal scale is 120 hours.

WATER DECEMBER 2002

51

WASTEWATER

the introduction of the instrument cycle and dosed acetate showed a higher P release to acetate uptake and a lower glycogen level per MLSS. Therefore these alterations to the operation of the cell must have selected for a change in the micro bial population and resultant improved P removal.

T he plant was converted to iron salt dosing in late 2001 to comply with the requirements of the discharge licence fo r that site. T his was based on a cost analysis which showed dosing with acetic acid to be significantly mo re expensive . A prospect for the future would be to trial high COD industrial wastes to see whether they would support the necessary biological P removal and if so actively seek a source of the waste for use at the plant.

Conclusions On line nutrient analysers have allowed the full investigation of the impact of process changes on efiluent quality in ways

that would have been very difficult using conventional methods.

In conjunction with altered control protocols, made possible by these analysers, we have been able to improve the quality of the efiluent and demonstrate that biological P removal can indeed occur in an IDEA plant provided sufficient RACOD is supplied during the anaerobic period.

Acknowledgements T h e author wishes to thank the operator Paul Keating for his diligent operation of the plant during the upgrades and trials, N ick Stanley for modifying the PLC program, and R ob Dexter, D r J urg Keller, Jenny Mosse and Kay W hite for their critical reviews of the manuscript.

The cooperation of the Gippsland Branch of the Victorian EPA in allowing this study to proceed is gratefully acknowledged.

References Australian Water and Wastewater Association (1997a). BNR plants in Australia. AWWA Artarmon NSW. Australian Water and Wastewater Association (19976). Proceedings ofBNR3 Conference.

Oehmen A, Saunders AM, Blackall LL, Yuan Z and Keller J (2002). The effect of GAO's on anaerobic carbon requirements in full-scale Australian EBPR plants. (In Press) or Paper presented at Enviro 2002.

Pilkington N H and Bayly R C (1994) Proceedings of the second Australian conference on biological nutrient removal from wastewater.

White K (1999) A modification of the IDEA process to improve nitrogen removal. 18th Federal AWWA Convention, Adelaide, April 1999.

The Author Peter Mosse (peter.mosse@ gippswater.com.au) is currently working as an internal consultant in Water and Wastewater Treatment for Gippsland Water and other clients.

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BOOK REVIEWS Farm Dams. Planning, Construction and Mai11te11a11ce by Barry Lewis.

Landlinks P ublication 2002. ISBN 0- 643- 06576-8 $49.95 plus p.& h.

Availab l e AWWA Bookshop.

Email:dwiesner@awa.asn.au T he fi rst thing w hich strikes the reader is the author's style. Barry Lewis uses short simple sentences with a clear sequence of fact and conclusion, a rare occurrence these days. Planning, construction and maintenance are dealt with in a logical fashio n beginning with assessment of water needs.

T his is a sensible, detailed and practical guide for any sensible adu.lt to use to o rganize construction of a farm dam to draw water for a farm ing property and its stock. Th e dam might be co draw from a regularly flo w ing stream or an ephemeral flow o r co contain runoff perhaps in a low-lyin g hollow on th e property. C hap ters cover soil testing, fo undation materials, embankm ent materials in brief but other sections dealing with dam design , construction and mainte nance are full of detail and include check-lists and inspection procedures. There is a good selection of diagrams and drawings with the occasional table.

There is one quibble. It concerns what may have been an oversigh t on the part of the au thor or perhaps a deliberate omission. There is no section dealing wi th rai nfall, cli mate and runoff Th e use of rainfall records, estimates of maximum probable precipitation and their impact on selectio n of the site of the dam, its size and type are not addressed. T he logical place wo uld be under planning. Yet Lewis deals with planning water supplies and water quality, fac tors such as catchm en t yie ld, estimati ng runoff, the affect of various levels of vegetative cover and the issue o f artificial catchments but leaves thi s gap before passi ng to site selecti on whe re o t her iss ues are addressed.

T his criticism must be balanced against approval to the au thor for attempting to flag the testy issue oflegaJ matters. Section (no.10) serves to alert readers to the legal and liability issues that may arise for dam owners. Lack of consistency between the states in simple definitions of w hen and w hat shou ld be classed as a registered , licensed or unlicensed dam and ,vhat constitutes a waterway, a stream or a river suggests that there is much work to be done in redressing opportu nities for unscrupulous claimants. This is made worse by the fact that water tends

to cross state boundaries so what may apply in one state may be at variance w ith an existin g defini tion in the adj acent state. It seems that in the current situation, it is difficult for parties co fu lly insure themselves aga inst liabil ity for dam failu re, acciden ts or overflow w here th e law is lagging.

T he book represents good solid value. It is a useful addition to the bookshelves of those interested in the land as commercial farmers, hobby-ists or just pla in interested scientists of the land.

different laboratories, error sou rces, shortcomings, and numerical criteria values are discussed fo r each m ethod.

C hoosing the stabilisation method best suited to the feedstock, operating conditions, local environmen t and existing treatment trains, and achieving best o utco mes is possible using the data presented in this Report. For those working with residuals and concerned about future issues for b iosolids managem ent by utilities, this Report is a very useful addition to the library shelf.

De11eloping Protocols for B iosolids Stability by MS Switzenbaum, AB

Online Monitoringfor Drinking Water Utilities. Softbound, 400 pages.

Pincince, JF Donovan, E Epstein, Farrell. Published by WERF 2002 as Report on Project 99PU M - 3 . ISBN: 1843396556.

Available AWA bookshop by email bookshop@awa.asn.au In the USA today, th ere is publi c uneasiness wi th the lo ng-accepted process there of land application of biosolids, and their risk to public health. Arising from this need to address an area which is important for wastewater utilities whi ch must deal with biosolids, this R eport addresses the stability of biosolids used for land application and the likely risks th ey pose to health particularly over the longer term as a result o f odour, trace metals, regrowth or recolonisatio n by potential pathogens.

T he fi rst step in examining biosolids stability is to validate test protocols that are commonl y used to assess th e stability of biosolids products, and to define a standard for each test m ethod.

The biosolids-stabilizati on technologies reviewed were aerobic and anaerob ic digestion, alkalin e stabilization, and co mposti n g; the t est ing m eth ods reviewed we re specific oxygen uptake rate, volatile solids reduction, additional vo lati le solids reduction, pH and changes in pH, and carbon dioxide evolution.

As a result of this exercise and subsequen t evaluation of the material, the authors of the report have been able to draw up specific protocols for each testing method and present intrinsic precision data for each protocol. Not surprisingly, variability diffe rs between facilities using each protocol and these are bnked to sampling procedures, feeds tock, the stabilization process, and the intrinsic variabili ty of each testing method. Issues associated w ith va1i ability including differences between results on the same sample from

ISBN 1- 58321 - 183-7. 2002. AWWA Resea r c h Report No. 90829 Available bookshop@awa .asn.au Increasingly stringent dem ands are being placed o n drinking water utilities to produce drinking water of consistently high quality. To ach ieve this aim o n a continu ous basis requires su rveillance and response systems operating on a 24- h our-a- d ay 7-day-week.

Equipm.ent such as online monitors ensure that system integrity is not compromised by variations in raw source water quality, equipment outage, fail ure of the water treatm ent process or operator error.

T he rationale for online mon.icoring versus spot routine check by grabsample has been furth er established by increases in reliability of the equipment, better education of operators on how to identify and respond to events, and more competitors entering the market offeiing improvem ents in sensitivity and decreases in costs.

Online Mo11itori11gfor Dri11ki11g Water Utilities, a new report from AWW ARF presents a strong case for their use.

There is plenty of practical information on the installation, maintenance, and operation of online m onitoring instrum en ts, on data handling, quality assurance, and the intercon nection of instrumentation to control systems.

Other useful chapters give guidance on the preparation of purchasing specifications, co mparisons of operating prin cip l es, a nd informat ion on instrument reliability as well as technical skills required to operate these instrum ents . This report succeeds in explaining how this sophisticated piece of equipment can be properly chosen, installed and used to achieve full value and reliable performance.

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Diane Wiesner A WA snr scientist

WATER DECEMBER 2002

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