Peak pump performance with Grundfos Sarlin SMART TRIM. Smart Trim will save you both money in maintenance and in energy costs . That's because the unique Smart Trim facility on Grundfos Sarlin submersibles enables you to make axial impeller adjustments quickly and conveniently on site. • no wear rings to replace • no costly bench work • no replacement pumps to rent If you want to keep your pumps running efficiently, simply and cost effectively throughout their lives, Smart Trim is your answer.
~ ~ ?'?'
GRUNDFOS®~~ CA DI 1 ..1 DI IIUIDC -..-na.11 .. lrVIYllr~
Volume 28 No 5 July 2001
Journal of the Australian Water Assoc iation
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Water (ISSN 0310 - 0367)
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[ ~l NITROGEN REMOVAL FROM FOOD PROCESSING EFFLUENTS W G C Raper, J M Green
Asimple method for dealing with abattoir and other food wastes 39
[ -..i VERMICULTURE FOR SEWAGE AND WATER TREATMENT SLUDGES S Komarowsk i
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~,., LIME CRYSTALLISATION SOFTENING, NEERABUP, W.A. N Herbert, G va n Houweligen, S Sibma
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OUR COVER: The cover image 111as produced using 'FISH' technolog y during research at the University of Queensland on. biological phosphorus removal. It shows glycogen-acwmulating orga11is111s as yellow-colo11red clusters and individual cells in sludge from a full -scale Biological Nutrient Removal (BNR) plant. These bacteria do not remove phosphorus but can directly compete with phosphorus-accumulating organisms. Photo: G. Crocetti, UQ.
INTEGRATION HOLDS THE KEY I was pleased to be able to attend the American Water Works Association Confe rence in Washington, DC, last month - a 14,000-person extravaganza with a lot happening. My networking commitment to colleagues and affiliates kept me out of many confere nce sessions, but I was able to sit in on a joint AWWAIW A session on integrated water resource management. Another term for that co u ld well be sustai n abl e water management, since the overriding goal is to deliver a good environmental outcome w ithout sacrificing prosperity and quality of life. Speakers at the session came from the USA, Australia and the World Bank and there were many interesting points made, but one that resonated very strongly with me was that a key to achieving sustainability is relationships; between regulators and managers, between the commu nity and the implementers, and between different regulato r and manager groups. T he point was made by Alan Vicory, CEO of O R SANCO (O hio R iver Sanitary Conunission), an organisation with a long h istory of forging productive partnerships with other organisations. H e should know. The need for effective relationships is just as cogent, if not more so, in Australia, given our three-tiered government and strongly parochial culture. The recent Infrastructure Reportcard, produced by GHD for the Institution of Engineers Australia and a diverse set of industry associations, including ours, and released earlier this month, points to the raft of different legislative and regulatory instruments that complicates water management. If we take Alan Vico1y's point, though, we should look to see how we can utilise existing legislation and technology, but work smarter to get results. T hat's clearly a tall order, but the prize is worth the effort. We have already begun, at the association end, to assemble an effective, collaborative force, through the Australian Water Indusuy Forum, so we will use that medium to reach the other stakeholders and start the dialogue about reaching integration. Happiness Is ...
Radio National ran an interesting program on Sunday 1 J uly, abo u t happiness and how it relates to the economy and to people's behaviour. The hour-long expose covered a lot of ground, but it threw into sharp relief the question of people's need for a sense of comm unity, 2
WATER JULY 2001
to add meaning to their lives. O ne thesis was that wealth is only relevant by com parison - a un iform improvement in national wealth elevates the neighbours too, so yo ur improvement is not discemable. No doubt the old adage about money not buying happiness, but making you comfortable in your misery, could be trotted out at this juncture, but what the researchers were saying, in effect, is that happiness has m any dimensions, among which is the sense of belonging to a community. Associations like AW A offer a sense of community, and that has always been a stro ng plank in associations' success, but a factor to consider here is that the younger generation, Generation X in marketing jargon, is notorious for not being a joining generation . We Baby Boomers seem to join up willingly and to have many affiliations, whereas Gen X does not, its members consume and participate, but are slow to join organisations. If AW A and its sister associations are going to continue to serve the comm unity, we have to find a way around this, since we cannot afford to have a cohort of ageing people form the core membership. Obviously, we do have some yo unger members and I believe we must engage them more effectively, to ensure that m embership is a rich experience and that they, in tum, recruit colleagues and friends. Although advertising may have some merit, m ost people who join associations do so thanks to word-of-mouth recom m endations, or arising out of some active participation w hich gives them the prod to fo rmalise a relationship.
Overall, AWA, like every association, is a community of people sharing a common purpose. If we can make that purpose crystal clear, and enable most of our current members to achieve it, then we will crack Gen X and go from strength to strength. We have some plans in the pipeline already, including a new, national prize for undergraduates, but we need much more to become really attractive. We'll soon be reviewing individu al membership packages, to see if there are opportunities to tweak them for special needs. J ust one possibility is to create ememberships - for people who have no physical contact with AW A, but who make use o f web-based and e-mail services, and perhaps the Bookshop. That could suit people overseas, or people too remote to be able to take part in normal, branch activities. The range of options is limited only by our imagination. If you have any ideas, please send them to me, because fres h perspectives often add a great deal of value. Just drop a note to our Artannon address, or to me on firstname.lastname@example.org Barry Norman
water Contributions Wanted T he Water j ournal welcomes t he subm ission of papers equivalent to 3,000- 5,000 words (all owing for graphics) relating to all areas of the water cycle and water business to be published in the journal. Topical stories of up to 2,000 words may also be accepted. In the first instance, email a draft copy to the Technical Editor, Bob Swinton (email email@example.com). Following his assessment of suitability, he will table the paper at a monthly Jo u rna l Committee meeting where, if appropriate, it will be assigned to referees. Their comments w ill be passed back to the principal author. If accepted and after any comments have been dealt with, the fi nal paper can be emailed with the text in MS Word but with high resolution graphics (300 dpi tiff, jpg or eps files - Zip disks or CDROMs can be accepted) in separate files (N.B. graphics embedded in Word files can not be used) or hard copy photos and graphics suitable for scanning by the publisher can be mailed to 4 Pleasant View Cres, W heelers Hill, Vic 3150.
An LCA carried out by CRC WMPC 2000 for th e manufacturer of th e InSink-Erator kitchen sink food waste processo rs (FWP) in th e eas tern metropobtan region ofSydney, compared the FWP, with its impact on the sewage syst em, with alternative waste disposal methods - home com postin g, centralised composting, and landfill. The sewage stu dy examined th e impact on the Waverley-Bondi sewerage area, with its many multi-unit dwell ings. It fou nd that the re would be an insignificant impact on the hydraubc load, and, up to 15% market penetration, no signifi cant effect on operation of the Bondi STP . In terms of environmen tal impact only home composting rated ahead of the FWP. This ou tcome will enable the company to debate environm.ental aspects of its product o n a scientific basis. The full report is available at http: / / www. cr cwmpc . com. au/Pu bli ca ti ons/Food W asteDisposalReport/ FoodWasteDisposa lReport.pdf L CA's ability to assist companies to achi eve cheaper and cleaner production co nies about because LCA points to factors in the production process such as hig h energy usage, high consumption of raw mate1;als, or the production of a high volume of waste products, that are indi ca tors of a less than optimum production process. Wh ile the LCA methodology curre ntl y is primarily used as a tool fo r strategic decision making, it is only a matter of time until most large co1npanies will find it necessary to consider the total environmental impact of their produ cts over their en tire lifecycle. In an increasingly green world, compa nies would be foolish to introduce a n e w product that has obvious detrimental consequences for the environment because of the backlas h this would attract from consumer groups. Equally, th ere is an advantage in being able to demonstrate the green credentials of a product - some people are willing to pay a little more for somethin g which can be shown to be more environmentally friendly that a rival product. 111
soon send some of its solid waste several hundred kilometres to Woodlawn near Goulburn is one indication of what may lie ahead. To alleviate their waste problems, both islands will depend on a change of attitude by their communities to the management of waste. The change has already been effected on Lord H owe where CRC WMPC assisted th e procu rement of an integrated waste management system. Important components in the development of the Lord H owe strategy included a waste audit carried out by i ndependent cons u ltant AP ri n ce Consulting that identified purchasing patterns and waste-generating behaviour, and comm un ity co nsultat ion that confirmed that the island conmmnity, the administration, visitors and mainland suppliers would support a strategy that redu ced waste through avo idance, reuse and recycling initiatives. The result is that previous solid waste disposa l methods, such as bu rnin g and landfill, have been minimised. Green
waste, paper, cardboard and food waste including meat are sent to a Vertical Composting Unit that is producing qua lity co mpost. The unit is fu lly enclosed, weather proof, vermin proof, simple to operate and produ ces no leachate. Sewage sludge is handled in a biocycle treatment plant. On Norfolk Island, the CRC together with APrince Consulting, has prepared a waste management strategy that is currently being considered by the island 's admini stration. Like Lord Howe, a resident survey on Norfolk Island has shown a wi llingness to change waste management practices, and it is likely that that community will see similar changes to these effected on Lord H owe in the near future. Th e will ingness of these two special communities to take ownersh ip of their waste management problems, and support new approaches, is an important straw in the wind for the many local government authorities on the mainland that will face similar problems in the years ahead.
The times are a' changin' Lord Howe and Norfolk Islands are a microcosm of the problems facing local government authorities around Australia, and the solutions adopted by the islanders co uld be a lesson for many mainland Australian communities. While the lack of suitable landfill sites is more acute on the islands, this problem w ill also co nfront many mainland com.munities. The fact that Sydney will WATER JULY 2001
Life Cycle Assessment of Biosolids Processing Options S Lundie, G Peters In a joint report of the CR C for Waste M anagement and Pollution Control and Sydney Water Corporation (Peters G., Lundie S. (2000) "Life Cycle Assessment ofBiosolids Processing Options" Sydney Water/CRCWMPC) , different options for biosolids handling were compared using the enviro nmental life cycle assessment method. The basis of this assessment is the expected quantity of biosolids captured at Sydney Water's three largest sewage treatment plants under full primary treatment in the year 2021. Two key comparisons are made: a co mparison of configurations (decentralised and centralised systems) and a comparison of tech nologies (th ermal drying and lime amendment). T he environmental issues addressed are energy consumption, contribution to global warming (climate cha nge) and potential toxic effects in hu mans. The latter is calculated on the basis of a new multi media fate model under development. The centralised system under study would consume an insignificant additional amount of energy compared with the current decentralised system. This is a consequence of the choice of drying and pelletising technology (supplementing biogas with some petrochemical methane) in the centralised system instead of lime amendment, which is used in the decentralised system. As the energy required to pump biosolids between plants is relatively insignificant, a centralised system using the same stabilisation technologies as the decentralised system has approximately the same impacts. The global warming and human toxicity potentials of the different options do not differ significantly. In contrast to the assessment of centra li sa ti o n , t h e assess m e nt of technology choices fo r North H ead Sewage Treatment Plant (STP) showed significant differences between the options. T he possibili ty of using 100% endogenous biogas in the drying option for North H ead STP allows a 68% redu ction in energy consumption and a 45% reduction in g reen hou se gas emissions relative to the lime amendment option. Selection of th is drying option would result in. a 23% irn.provement in human toxicity potential compared with the lime amendment option at North Head STP. 32
WATER JULY 2001
The choice of biosolids processing technology is more significant than the choice of centralised or decentralised systems. This has been shown for both the decis ion bet ween d ryi n g and lime amendment, and also the choice of whether or not to install biogas-fuelled cogeneration equipment.
Key issues in improving the environmental profile of biosolids handling are the use ofbiogas fuel, avoidance of coalsourced electrical energy, minimisation of trucking distances and raising the solids content of captured biosolids products to be transported.
What is Life Cycle Assessment (LCA)? T he main characteristics of LCA are: • LCA studies different optio ns for the supply of a given product or service. It thus links changes in products in the econo m y to imp ac t s o n th e environmen t. • L C A follo ws a cradle- to-grave approach: processes connected with the fun c tion, from the extrac tion of resources until the final disposal of waste, are considered. This cradle-to-grave approach may induce companies to look beyond their gates, or induce stakeholders to detect unexp ected side effects of their strategies. • LC A is comprehensive with respect to the environmental interventions and environmental issues considered. In principle, all environmental issues or
problems, connected with the function, are specified as resulting from extraction , emissions and other physical interventions. The obvio us strong point ofLCA is its comprehensiveness: the inclusion of the total chain from cradle-to-grave, and of all environmental problems involved. This provides a comparison of the different ways of fulfilling a p articular function and supports environmental decision-making. Much effort has been and is being put into the development of the LCA methodology and the establishment of LC A software and databases. LC A is currently being standardised within the ISO framework (ISO series 14040).
Recycling of product
This chart compares the energy consumption of an environmentally-friendly product (product 1) with an 'ordinary' product (product 2). Product 1 consumes 30MJ of energy over its life from manufacture to disposal while product 2 consumes 42 MJ. For product 1, material production and assembly is more energy intensive, while energy used in transportation is less than product 2. The major differences between the products are in t he energy used to operate t hem over their working lives and in recycling, or re-use, of the materials from which they are made. Energy used in operating the product s is the most significant factor in energy consumption.
Assisting Small and Medium Enterprises The CRC for Waste Management and Pollution Control (CRC WMPC) has assisted a number of small to medium enterprises (SM.Es) during its current term by providing technology application advice, testing of prototypes and assistance with identifying market applications. In some cases CRC members have been contracted directly to do specific R&D for such com.panies. In each case the CRC assistance has been focussed on areas that are aligned with its core objectives and that will add va lu e to its own existi ng technology developments. Compani es that the CR C has assisted include: • Australian Filtrati on Services - later to become Filtra Limited valued at more than $12111, • Dolornatrix Pty Ltd - now looking to become an ASX listed compa ny, • Australian Glass Processing Company Pty Ltd for which C RC WMPC secured a major START gran t , altho u gh th e company elected to use other 111.eans to fina nce its pla ns, and • Australian W etlands - spun off from C R C WMPC through a ma nagement buyout. The C R.C's assistance has largely been through negotiating with members to supply support services, undertaki ng specific testing, providing linkages into market sectors and, by working with companjes, providing strategic development advice. Fi ltra is an example of this continued involvement and support. T he company's foun ders established Filtra in December 1999 fo llowing several years of investment in, and development of, new technologies. The focus of these technologies is the provision of liquid/solid separation solutions in the water industry and particularly in th e sewage treatment industry.
CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL LIMITED
The CRC for Waste Management and Pollution Control's (CR C WMPC) obj ective is to contribute positively to the economic, social and environmental well being of Australia through focussing its research expertise to provide solutions for the environmental industry . Among th e CRC's members are p ublic utilities
Wet weather flow handling device The Fi ltra wet weather flow handling device (WWFHD) keeps the biomass in the reactor and red uces the load on the secondary clarifier. Th is allows a higher throughput of fully treated flow during wet weather. Effluent= 4.5 - 6+ x ADWF Sewage/wet weather input = 4.5 - 6+ x ADWF FL7000
.,.411--- Return reduced Conventional plant for 50, 000 people, 3 x ADWF - $1 3.5 mil lion. Filtra WWFHD adds 5 - 8% to ca pital cost.
C R C WMPC helped in the early days by evaluating some tec hn ologies and providing contacts that have been invaluable to the company in fu rthering its developm ent. T he CRC's ongoing association with Filtra enables the company to check its development plans in wider context than wou ld normally be avai lable to a start-up SME. Filtra's objective is to make a significant improvement in the capital and operating costs, and environmental outcomes of companies and industri es where settling tank technologies are currently used for separati on of solids from water. T he Fil tra team has developed a value proposition for the sewage treatment industry based on an innovative process change. The new, patented technology that underlies the process change allows the decoupling of solids and liquid transport within the treatment process train. Filtra is currently developing som e exciting products, which are of interest to major utilities both in Australia and overseas. These products include the: and regulato1y bodies as well as a number of indust1y partners, three universities and th e CSIRO. The Chai1111an of the C R C WMPC is Ian Kiernan. The Federal Government contributes about 25% of the CR C's income. Contact details: Dr David Garman CRC for WMPC Ltd VaJJentine Annex H22 U niversity of NSW 2052 Tel 02 9385 4886 Fax 02 96621971 email: crcwmp c@ unsw.edu .au website: www.crcwmpc.com.au
• Sa mple-Conditioning Device (FL1000) , • Wet W eather Flow H andli ng Device (WW FH D)/Ca p acity Augme n tatio n Device (CAD), (FL2000 and FL7000 for small and large plants respecti vely) and • Filtra Clarifi er (FL9000) . Filtra's main product line, including the FL2000 and FL7000, is based on interposing a device between the reactor and the clarifier that: • returns a more concentrated R eturn Activated Sludge to the reactor, and • provides a feed to the clarifier with a lower solids concentra tion. FL2000 and FL7000 will be launched this year, along with FLl000, a sampleconditioning device that is a "beacon product" fo r the Filtra technology. It wiU enable sa mples virtually free of solids to taken from waste water treatment plants (WWTP) for analytical or operational p urposes. The low acquisition and maintenance cost of the FLlO00 offers many advantages over conventional systems. The FL2000, FL7000 and FL9000 are the main products with which Filtra will target deve l oped wor ld market s conm1.encing in 2002. R esearch indicates that capacity is being installed at an estimated annual growth rate of better than 4- 5%. These products wil.l sign ificantly change the operations of WWTPs with cost savings in many areas of operation, and will allow upgrades to be deferred. Filtra expects them to lead to many other innovative developments to, and applicati ons for, plant operations. The products being developed by Filtra will also have wide application in other industties including potable water, pulp and paper, food and beverages as wel.l as dai1y and mini ng. WATER JULY 2001
SIMPLE PROCESS FOR NITROGEN REMOVAL FROM FOOD PROCESSING EFFLUENTS W G C Raper, J M Green Abstract Food processing wastewaters often contain high levels of nutrients, particularly nitrogen. Conventionally, anaerobic ponds are used to purify these wastewaters, giving cost-effective removal of BOD but little nutrient removal. D isposal of the resulting effluents by irrigation, as presently practised, usually exceeds sustainable nitrogen application rates. Conventional BNR tech nology can readily remove nutrients from such effluents, either alone or in combination with anaerobic ponds but a large amount of sludge is produced which poses environmental and economic problems. We have show n that recycling the sludge to the anaerobic ponds can be com.bined with the initial BOD removal to provide an effluent which can then be optimised for BOD:N ratio, so that a subsequent sequencing batch reactor operates well for nitrifi.cation/denitrification. T his paper describes the design and performance of two plants; a demonstration plant installed at a typical sized meatworks in Gippsland, Victoria, and a full-scale plant for treatment of combined domestic sewage and effluent from a large meatworks at Longford, Tasmania. It was demonstrated that 98% ofBOD and up to 95% N removal may be attained. Phosphorus can readily be removed w ith alum when required, although in neither case (for different reasons), has this been required as yet. Three ot h er similar plants are presently in course of construction or commissioning in Australia.
Key words : N utr ient removal, nitro ge n , effluent, anaerobic, food processing, sequencing batch reactor.
Introduction Typical country meatworks effluents contain 1,000-4,000 mg/L BOD, 200-400 mg/L TKN and 20-50 mg/L P. When discharged to country town sewers, they frequently account for 50-75% of the nutrient and BOD load. Consequently 34
WATER JU LY 2001
A. Conventional activated sludge treatment and sludge disposal Aerated pond Influent
-............. Sludge to composting etc
Centrifuge or belt press
B. Influent and sludge treatment in one anaerobic pond Alum for P removal if required
Cyclic aerobic pond Treated effluent
Influent Waste sludge Influent by-pass
Figure 1a. Convent iona l, Figure 1b. Pro posed treatment meth ods
treatment on site and disposal by irrigation is encouraged . However, there are problems. T h e nutrient removal process described in this paper was initially developed in response to the need of a meatworks in Gippsland to improve the quality of 250 kL/ d of treated effluent being discharged to land by spray irrigation. Previously, the BOD and suspended solids had been reduced in an anaerobic lagoon and the effluent thus treated was stored in holding lagoons prior to irrigation to pasture grazed by cattle. Ammonia as N (NHrN) was 300 mg/L which created N application rates of about 750 kg/Ha. This excessive rate had adverse effects on the pasture. Thus, reduction of N to safe levels became required. Several key issues emerged whil e considering the application of conven-
tional technology to treatment of effluent from typical sized meatworks: Co n ventiona l act ivated sludge treatment of raw meatworks effluent (as shown in Figure la), will achieve good nutrient removal due to the high BOD:N ratio but with high sludge production and aeration costs. The disposal of sludge from activated sludge processes by conventional means, such as dewatering by centrifugation or belt filtration poses maj or economic problems for small-scale operations due to capital, maintenance and operating costs. The sludge may be disposed of by spreading on land , but little is to be gained by this approach - substantially aU the N originally present in the effluent has simply been transferred into the sludge. Thus the mass of N to be irrigated remains similar, so the land area requ ired for disposal is not reduced.
D isposal of the sludge to an anaerobic pond is a more attractive option but amm onia wou ld be regenerated to a significant extent D ir ec t appl i cation of B NR. technology to anaerobic pond eilluent will result in poor N removal due to its low BOD:N ratio
Background In the activated sludge process N is removed b y syn th es is of bacterial biomass during aerobic removal of BOD . In the case of municipal sewage, nitrogen levels are too high for removal of more than 20-30% by this route, so fo r nitrogen removal application of th e nitrification and denitrification process is essential. In the case of meatworks wastewater, w hile there is normaJJy sufficie nt BOD present to remove the majority of N by syn thesis, two disadvantages are involved - the large amount of aeration power consurn.ed and the am o unt of sludge wh ich is prod uced (pe rhaps ten ti m es that produced by anaerob ic removal of BOD).
Laboratory studies in Queensland S ubraman iam et al. (1994) demonstra ted that a subsequen t conventional seq u e ncing batc h r eactor (S BR) treatment could achieve alJ-biologicaJ N & P removal from the eilluent o f a 3 day HR.T anaerobic pond treating m eatworks eilluent. The COD/TKN rati o was always > 10. Less success was ac hi eved w ith 6 day anaerobi c HRT , where the COD/TKN ratio was <7. M ost meatworks anaerobic pon ds are designed with 15 - 30 days H R T and pro duce eilluents with COD/TKN around 2. A n attractive alternative could be to combi ne the processes of nitrifi cation/ deni trification with sludge digestio n in an anaerobi c pond. . R ecycling the sludge to the existing conventional ana erobic lagoon would be simple and eco n omic. More than sufficient BOD is available from meatworks wastewater for den itrifica tion of the N pro duced in suc h a pond by anaerobic di gestion of sludge. H owever, sufficient BOD must remain available for denitrification in the subsequent SBR and the req uired amount is not normally present in anaerobic pond eill uent. Thus there exis t ed an opportunity to optimally blend untreated meatworks wastewater wit h the anaerobic pond eill uent(s), as indicated in Figure 1b, to provide sufficient BOD for den itri fication without involving excessive power consu mp tion
Table 1 . Laboratory Results Parameter (Units - mg/ L)
Influent After 3 weeks
Effluent After 4 weeks
After 3 months
Oxidised N Total P NH3-N
for aerobic BOD rem oval. It remained to be proved that raw meatworks wastewater wo uld provide a source of BOD suitable for efficient denitrification.
Results from laboratory trials R aper and Green (1995) described the laboratory expe riments fo r the process discussed in this paper. Th e experiments were condu cted on the basis of the configuration shown in Figure 1b, and produced the followin g results (Table l). T he superficial influent residence ti me in the anaerobic "pond" was 30 days, as was th e sludge age in the SBR. Th e SBR. hydraul ic residence time
(HR.T) was 5 days, and it was aerated automaticaJJy for 12 hours overn ight each day. O n wee k-day mornings, sludge wasting, settling and decanting of treated eflluent was done manually. The SBR was refilled w ith 1:1 meatworks eilluent and anaerobic "pond" eilluent. Th e cal culated volume of meatworks eilluent together with the wasted sludge from the SBR was then added to th e anae robic "pond". Th e SBR was allowed to stand with out ae ration for a total of 12 hours foJJ owed by th e next aeration cycle. T o sim ulate meatworks operation, no additi ons were done over the weekend, bu t the SBR. cycle co ntinu ed to be 12 hours aeration fo llowed by 12 hours withou t aeration.
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Table 2. Performance obtained by the Gippsland SBR Component
Total Nitrogen (TN)
250 mg/ L
10-20 mg/ L
<20 mg/ L
<20 mg/ L
Phosphoru s Colour
60-80 Pt Co
From the results of this work, CSIRO was granted a patent (Raper & Green 1994). Its firs t claim reads as follows. "A process for removal of co111po1111ds of 11itroge11 a11d co111po1111ds of pl,ospl,orus from an ~fll11e11t l,a1Jing a BODITKN ratio of less than 3 whicl, co111prises tl,e steps of
(a) s11bjecti11g the eff/11e11t to a11 aerobic/ a11oxic bacterial treatment i11 a 11ia1111er k11011m to re111011e N & P, to prod11ce a treated liquor for discharge a11d a sl11dge or bio111ass; (b) tra11s.ferri11g tl,e sl11dge or bio11iass prod11ced to an a11aerobic en11iro11111eut a11d allowi11g tl,e sludge to settle w/1ile bei11g stabilised by a11aerobic actio11 (c) ret11rning tl,e s11pemata11t liq11orfi'o111 step (b) to step (a)."
Based on the results of the laboratory experiments, the fi rst full-scale plant was constructed at a Gippsland meatworks . T he success of this plant led to the upgrading of a much larger plant at Longford, Tasmania.
Gippsland Plant Design The Gippsland plant, which was constructed on these principles, has operated successfully since November 1995. As predicted, it was fou nd that: • Capital and power consumption were minimised. • D ay to day sludge handling was eliminated. • N is discharged to the atmosphere as harmless nitrogen gas. • After 3 months retention in the irrigation storage, TN had dropped to approximately 5 mg/L. The effiuent from the anaerobic lagoon was consistently of the following composition: BOD 300 mg/L, SS 300 mg/L, Total N 300 mg/L (mostly as N H 3-N) Total P 36 mg/L. T herefore, the following initial assumptions fo r the design of the SBR were made: • Total N and P entering the SBR would remain unchanged. • Some improvement in the effluent performance of the anaerobic lagoon as 36
WATER JULY 2001
measured by BOD and SS co uld be anticipated because of reduced flows caused by effiuent by-passed directly to the SBR. • Aerators for the SBR would operate 12 hours per day after a commissioning period . The total estimated N entering the SBR=75 kg/day. Therefore oxygen requireme n t (Hartley1985) for nitrification is 4.6x75 = 345 kg/day. For 12 hours aeration per day , the required aer a tion ra t e = 28 .75 kg/aeration hour. • T herefore, two 15 kW fl oating aerators were chosen. Green et al. (1997) describe the design of the SBR in detail. A summary is presented here. T he SBR was designed to reflect the successful laboratory tri als. That is: • five days liquid residence time (5 x 250 kL/day = 1250 kL volume). • twelve ho urs aeration per day. • thirty days sludge age . • approximately 50% of raw effluent bypassed the anaerobic pond into the SBR . The design challenge was to convert these process parameters into a simple but reliable automatic process which settled and decanted treated effiuent between the hours of 3 .00 am and 7.00 am each morning following a day's meatworks operations. A natural clay lagoon, 4 metres deep, was chosen fo r the SBR . T he banks were lined with 90% shade cloth as a protection against erosion from the surface aerators. Sludge transfer to the anaerobic lagoon was via a Mono™ pump with a capacity of 25,000 L/hr. To maintain a sludge age of 30 days (nominally 20 working days in a 28-day period) about 60,000 L/day of mixed liquor is transferred to the anaerobic lagoon on each production day. A magnetic flow meter was install ed to measure and record the sludge transfer volum.e . A siphon is used to decant the treated e ffl uent after settling. For
T his findi ng suggests that river discharge and/ or reuse w ithin the m eatworks is a real possibility for the future. Obviously, a very th o rou gh microbiological investigatio n o ver an exte nded exp erimental period will be required to establish the safe ty of any suc h reuse
Table 3. Irrigation wat er analysis Ammonia Phosphate as P Total Kjeldahl N
0.1 mg/ L 16 mg/ L 1 mg/ L
sim.plicity, this is a fi..'-'.ed level system. T he siphon is broken after decant is complete so that sludge does not enter th e d ecant sys te m during the next aeratio n cycle. The siphon is primed after the one- hour settling pe riod by a diap hragm type slud ge pump. For ease of adjustm ent, the SBR cycles of ae ration , sludge transfer, settin g and decanting are co ntrolled by time clocks.
Commissioning and operation of the Gippsland plant Two facilities, w hich were considered desirable, w ere not m ade available: o n1in e di ss ol ve d o xyge n ( D O) instrum entatio n fo r control of aeration and variable speed control of aerators. Thus it was not possible to mo nito r DO on a regular basis to m in imise aerato r po we r consump tion. H oweve r, this enabled us to de mo nstrate successful o p e ratio n without dissolved oxygen m o nitoring and control. Coban (1996) describ es th e co m m issio n ing of th e pl ant in d e tail. In sun1.mary, commission ing commen ced o n 4 Au gust 1995 with the SBR. fi lled with efflu ent from the existing anaerobic lag oo n. T he aerators w ere operated fo r lO h ours per day (4.00 pm to 2 .00 am). It w as hoped that no seed sludge from an existing activated sludge plant wo uld be necessa ry. Seed sludge may have accelerated the developme nt of nitrification/ denitrification but the decision to avoid seeding w as made for the foll owing reasons: â&#x20AC;˘ external sludge would be contaminated w ith domestic and other industrial trade wastes. â&#x20AC;˘ to prove that seed sludge w ould not b e r equired in future plants. A maj or foamin g problem occurred during the first three w eeks bu t it subsided and has not re-occurred. This is c ommon durin g the start-up of an ac tivated sludge plant (Gan czarczyk 1983). A delay o f two w eeks w as also cau sed by m echanical failure of one ae r a tor. Sludge wasting w as not implem e nted. By 27 O ctober 1995, sludge settling was excellent (the sludge volume index was 133 mL/ g) . Until 10 November 1995 the ammonia level ren1.ained unacceptable . The aeration pe riod w as then increased from 10 ho urs
4 mg/ L <10 mg/ L 16 orgs/ 100 ml.
BOD E Coli
per day to 19 hours (7.00 am to 2.00 am). On no n- production days the operating hours were 7.00 am to 2.00 am w ith one aerator. Within one week nitrificati o n comme n ce d and was su bs ta ntia lly complete by 30 N ovember. During D e ce mber , slud ge was ting to th e anae robic lagoon w as comm enced and the aeration cycle was optimised to minimise total N in the treated efflu ent, produ cing effluent containin g 12 mg/L N H 3/N , 9 mg/L oxidised N and 24 mg/L PO 4- P. Phospha te leve ls m e t th e EPA irrigation requirements without chernical addition , while BOD and N were lo wer than licen ce requirem e nts by a fac tor o f four! Commission ing was no w completed. T he plant has coped welJ w ith periodic interrupti o ns of abo ut a w eek to produ ction. Temporary failure o f one aerator affected performance, but th e plant recovered qu ickly after fu ll aerator capacity was restored . The plant has operated extre mely satisfactorily with minimal attenti on be ing requi red. T he average of the first six month s o pe ra ti ng results a ft e r commiss io nin g is given in T able 2. Because the local rainfall pattern prevents irriga tion w ith trea ted efflu ent for about eight months of the yea r, an irrigation storage reservo ir w ith a capacity of a p p r ox imat e l y 5 0 ML h as b ee n co nstru cted. A sam ple taken fro m it in September 1996 gave th e analytical results summarised in Table 3. For comparison th e freshwa ter da m at th e meatw orks, fed fro m the nearby river contained 650 E Coli organisms per 100 mL in April. T his river water (after alum treatment and chlorinatio n) is routinely used for potable and process w ater in the m eatworks. Laboratory treatme nt of water from the storage lagoon w ith alum gave a pro du ct co ntaining < 0 .5 m g/ L phosphate as P. N o pH adj ustme nt was re quired , due to the alkalinity p resent.
Longford plant background A large meatwo rks w ith a rendering plant discharged up to 1.5 M L/d o f unt reate d e ffl ue nt to th e Lo ngford sew age treatme nt plant. T he muni cipal dry weather sewage flow is up to 1.2 ML/ d. T he comb ined efflu ents were t reated in an aerate d lagoon (Lagoon 1 o f volume 15 ML), fitted with six 18.5 kW surface aerators. T h e system was overloaded and a further tw o aerators had bee n install ed in th e first 27 ML downstream lagoon (Lagoon 2) to reduce odour generatio n . Fo ur other algal lagoons totalJing 87 ML were connected in series to treat the efflu ent from Lagoon 2. T he final efflu ent w as seasonally variable, efflu ent ammonia reaching 5070 mg/L in winte r when algal activity is low er. Furthermore, th e future discharge licence would limit ammonia to less than 3 mg/L. Plant loadings are given in Table 4. A decisio n had been taken previo usly to install a covered ana erobic lagoon co treat the meatw orks e fflu ent . It w as the n decided co co mbine the anaerobi cally treated m eat:works efflue nt with the town sewage for treatment in an SBR. similar to that built in Gippsland (described abo ve). T w o furth e r aerato rs w e re p urc hased , bringing the total to ten . T he covered anaerobic lagoon (CAL) w as sized at 10 ML, lin ed and covered w ith a H DPE m embrane connected to a Oare fo r destru ction o f m ethane and odour.
Commissioning of the Longford plant The C AL commissioning proceeded steadily afte r it was seeded w ith digester sludge. After 3 months operation approximately 65% o f the in fl u ent BOD w as being removed - the d ilu ent containing approximately 700 mg/L BOD . C on cern about odo ur generation in Lagoon 2 caused the SBR. to be started
Table 4. Maximum Influent Concent rations and Loadings at Longford Source Sewage Meatworks
BOD (mg/ L)
BOD Load (kg/ d)
Total N (mg/ L)
Total N Load (kg/ d)
Total P (mg/ L)
Total P Load (kg/ d)
WATER JULY 2001
60 50 40 ..J
Cl 30 E
+ Ammonia N
-.,..1--•.-., •-,,...:-' •
--- - ---
Figure 2. Longford SBR Effluent, July 99 - June 00
utilising only 8 aerators. Theoretically, this was insufficient for adequate mixing, but p revious operating experience with the aerated lagoon suggested otherwise. After th e de c anting sys t e m was completed (April 12, 1999), no sludge was wasted from the SBR for a further 45 days. Over this period, ammonia N dropped to about 2 mg/ L. Mixed liquor w ithdrawal then commenced at 500 kL/ d to achieve a sludge age of 30 d. M easured DO in the system grea tly exceeded 2 mg/L, so one further aerator was turned off to save power. T he result was catastrophi c because DO rose even further and efiluent ammonia rose very rapidly. M easurement of SS during the aeration stage suggested that the majority of the sludge was not being resuspended during the aerati on period. The plant performance recovered rapidly after the eighth aerator was tu rned on again. This demonstrated the need to maintain adequate power input for mixing. Efflue nt ammonia from the SBR has been between 0-3 mg/ L ever since (Figure 2). When all meatworks effiuent is directed to the CAL, oxidised N varies in a consistent fas hio n from 15mg/L on Monday rising to 30 mg/L by the end of the week. By-passing around the CAL, when optimised, reduced oxidised N to 5 - 10 mg/L (Figure 2) . Ammonia levels in Lagoon 6 (the plant effiuent) remained of concern for the remainder of the winter. Ammonia levels in Lagoon 6 started to drop rapidly in early summer (mid-Novemb er), presumably caused by increased algal activity. Total inorganic N remained below 3 mg/ L for four months, but both oxidised N and ammonia then rose and remained at about 5 and 10 mg/L respectively until the end ofJuly. It appears that ammonia is liberated from sludge stored in the lagoons, but is removed by algal activity during summer. Sludge wasted from the SBR will be returned to the CAL (as at Gippsland) when funds 38
WATER JULY 2001
permit. The improved condition of the lagoons has attracted over 65 species of birds to the lagoons.
New installations A treatment plant similar to the Gippsland plant is presently undergoing commissioning at C ranbourne Victoria , a large plant is being commissioned at Innisfail, Queensland and construction is about to commence at Ararat on a plant similar to the Gippsland Plant.
Conclusions Conversion of existing lagoon systems to SBR operation is a simple and economic upgrade for reduction of N disc harges. W e have shown in two fullscale plants that anaerobic treatment of the raw eff1u ent from meatworks, together with waste sludge from the SBR can achieve highly efficient removal of BOD and N in the downstream SBR, influent levels of 150 - 250 mg/L N being reduced by approximately 95%. Furthermore, sludge production, sludge handling and power consumption were minimised. Treatment of the effiuent with alum is straightfo rward and effective showing that river discharge and/ or reuse within the meatworks is a real possibility fo r the future. We are confident that other food manufacturing effluents (which also contain high levels of BOD and N) such as those from dairies, mil k processing, piggeries and feed lots would be equally amenable to treatment by such a process.
Acknowledgements Thanks are du e and tendered to Ms M. Kelly for h er contribution to the laboratory program and to M s. M . Caban for monitoring the commissioning of the Gippsland Plant. The Longford CAL was designed by GHD Pty Ltd. Special thanks are expressed to the management and operating staff of Longford plant for their support before during and after commissioning of that plant.
The Authors Bill Raper worked in CSIRO D ivision of Molecular Science and was an early proponent ofBNR, organising the first and second BNR Confere nces in Australia in Ballarat and Albury. Now retired, he is a consultant, specialising in nutrient removal process design. Wildern Consul ting Group, 8 D avies Street, Brighton E ast Vic 3187, Australia. (email: wildern@mira .net). John Green worked in the meat industry as a plant engineer and consultant and at CSIRO Meat R esearch Laboratories. He is now specialising in environment solutions for the meat and allied industries. Greeneng Pty Ltd, 12 Angle R oad, Balwyn Vic 3103, Australia. (email: greeneng@ mira.net).
References Coban M . (1996) . 'Sequencing Batch Reactor for R emoval of Nitrogen from Abattoir Wastewaters'. Minor Thesis for the degree of Master of Environmental Engineering, University of Melbourne. Ganczarczyk J (1983). Activated Sludge Process: Theory and Practice, Marcel Dekker, N ew York , USA Green J M, R aper W G C and Coban M. (1997) . Simple Process for Nutrient R emoval fro m Food Processing Effluents. Proceedings of the Australian Water and Wastewater Association 17th Federal Convention, Melbourne Australia. Hartley K J 1988. Operating the Activated Sludge Process. Gutteridge Haskins & Davey Pty. Ltd. Brisbane , Australia. R aper W G C and Green J M (1994) . 'Removal o f nutrients from effluents'. Australian Patent 701363 . R aper W G C. and Green J M, (1995). 'Low Capital Process for Removal of N from Abattoir Wastewater'. Proceerungs, Meat 95 Conference, Gold Coast, September, pp ll a-1 to lla-4. Subramaniam K, Greenfield PF, Ho KM.Johns MR and Keller J (1994). Efficient biological nutrient removal in high strength wastewater using combined anaerobic-sequencing batch reactor treatment. Water Sc ience & Technology 30 (6) 315-321
VERMICULTURE FOR SEWAGE AND WATER TREATMENT SLUDGES S Komarowski Abstract
approximately 6000 1113 of sludge had been stockpiled . Like many other local councils, T he operations at the vermiR edland W ater (R W ) faces the culture facility in Cleveland are chaDenging issue o f the disposal o f described in detail in Vermitec h in c r e asing vol u m es o f sludges (1998) and Lotzof (1999) . In ge n e rated from their sewage and summary, the operations comprise: wate r treatment plan ts. 1. Sludge is collected at each STP I n 1997, on advice from consulin waste collection bins. It is tan t s, R W selected a vermjcultu re weighed and transpo rted to the pro cess to treat 250m3 / w eek o f worm farm by truck sew age and water treatm.ent sludge 2. T he sludges are tested, 1nixed and (plus stoc kpi led material). Th e Figure 1. Verm iculture facility at Clevel and showing blended. Bulking and deodorising res ulti ng vermiculture facility (or raised worm beds and s hade cover structure. agent is added ' worm fa rm') is owned and operated by V ermitech P/ L on a R W site 3 . Machines feed and spread the for the sewage sludge from the facilities and bas been in operation for 3 years. conditioned sludges to the p rocessing beds invo lved either sto ckpiling stabilised Ve rrnicul ture pro cessing saves o ver on a daily basis (anaerobica!Jy d igested) dewatered solids 13,0 0 0111 3 of landfill space per year. 4 . C omp u te r co ntroll e d w ate ring o n site at one of the ST Ps or landfilling R esults to date show that vermiculture maintains optimum moisture levels in the unstabilised (extended aeration) solids at reduces path ogens present in the sludge beds a landfill. to safe levels (ful filling N ew So uth 5. After 80 days, the castings produ ct is In 1997 R W issued a tender for th e Wales Enviro nmental Protectio n Agen cy harvested from the base of th e beds 3 disposal of 250111 /week of sludge from Gu i d elines for "A Grade Stabilisation 6. T he castings product is dried, screened, the sewage plants and water treatment C ri t eria for Sl udge ") . H eavy m etal tested and bagged fo r sale or sold in bulk plant. The tender requi red that the co n ce ntrati o n s re m.ain esse nti all y selected system remove and process The verm iculture principle works by u nc h anged , w hich bas n ot be en a sludge on a continuo us basis. Three types the w orms ingesting the sludge and problem since R W does no t treat heavy of processes were considered: composting, co nve rting a p ortio n of the o rganic in dustry. Volume and volatile solids m aterial in to w orm bio mass and respili111e stabilisa tio n and ver111iculture. red u ctio n is achieved throu gh organi c Following evaluation by co nsultants, ration prod ucts. T he worms expel th e decomposition and a decrease in m oisture rema ining stabilised matter as discrete vermi cu lture was selected as th e m ost con t ent. suitable system. m aterial (worm castings) which ca n be T h is paper p resents a bac kgrou nd to used as a soil conditioner. T he p rocess The Selected Process Âˇ the selection of the ve rmicultu re process results in a sign ifica nt redu ction in fo r R W , a d escriptio n of the process, a Vermiculture volume: fro m 1 m 3 wet sludge (-80% su n~rnary o f results and performance of m o istu re) to approximately 0.5 m 3 Th e vermiculture facility is designed, the facility to date - from a lo cal product (- 30% moisture) . owned and operated by Sydney-based government perspec tive. co mpany Vermitech P / L on a R W site. T he R W treatm ent plants provide Keywords: Sewage sludge, vermiover 200 wet tonnes of sludge per week The term of the co ntract betw ee n culture, earthworms, sludge re-use Vermitech and R W was initially for 2 fo r the w orms (plus stockpiled m aterial). years from J une 1997 and was later T he ve rmi cultu re process produ ces Introduction extended. When the verrniculture facility around 7,000 tonnes of worm castings per R edland Water (R W ) is situated 30 was commissioned in 1997 it w as one o f year. T o date the worm castings produ ct km. east of Brisbane, Quee nsland, o n has been used o n vineyards, vegetable the largest earthworm based sewage Mor eton Bay, and serves a populati on of co nversion operations in the world. production , golf courses and cotton o ve r 100,000. R W operates fiv e sewage crops as a soil conditioner and fe rtiliser T rial w orm beds were initially set up treatment plants (STP) and one w ater replacem ent, with results showing signifon site with the different sludges. It took trea t m ent plant that produces alu m icant increases in yield and growth. 12 m onths to establish the 14 worm beds sludg e. Like most local gove rnments, fo r required to treat the fu ll-scale quantities In 1995 R W investigated the feasibility of sludge being produ ced by RW. U ntil sludge m anagem ent R W considers itself of a centralised facility to handle waste this time, sludge continued to be stockas a product produ cer rather than a piled on site. B y the time the contract for sludge from its STPs and water treatment marketer. Vermitech undertakes the sale plant. At the time, managem ent practices the vermiculture faci lity was issued , and marketing of the final product. WATER JULY 2001
Table 1. Sludge Production and Solids Content of RW Treatment Plants for 99/00. STP name
Current capacity (EP)
Treatment process and sludge processing
Biological nutrient removal (BNR), belt filter press
BNR, anaerobic digestion, DAF, centrifuge
Trickling filter, anaerobic digestion , belt filter press
Package aeration plant
Biological N and chemical P removal, belt filter press
Biological N removal , anaerobic digestion, belt filter press
80 (ML/ d)2
Water t reatment plant, centrifuge
Point Lookout Mt Cotton
1 2 3 4
Sludge production Sludge production Sollds content Sludge production (wet tonnes/yr) (kg/EP/yr) (TS%) ( dry kg/EP /yr)
Weighted average for all sludge. Capacity is based on ML/ d water produced. Sludge is stockpiled on site and transported to the worm farm. In addition 3,000 tonnes of stockpiled material were processed at t he worm farm in 99/ 00.
Environmental Requirements of Facility
C leveland is designed to treat up to 350 t/wk.
An I n teg r ated Envi r o n menta l M anagement System was prepared for the vermicu lture fac ili ty as part o f the licensing requirements of the regulato1y authority (Queensland Environmental Protection Agency). Enviro nmental man agem ent practices for the faci lity include: • B unding of the entire worm farm with a fi rst flush basin to reduce runoff T he sludge stockp iles are located inside bund walls to eliminate runoff to nearby waterways and ru noff from the site is collected in a collectio n pond. • The worm beds are covered by a shade cloth structure, w hich helps to control the processing environm ent by reducing the temperature, w ind and rain and keeping out birds. • T he sludge stockpiles are managed to minimise odour generation. M anagen1ent procedures include no m edium term stockpiling of biological nutrient removal slu dges and minim isation of movement of stockpiles during NE winds (the site's nearest neighbours live 500 m SW).
Testing Procedures Quantities
The tender and contract fo r the sludge management facility was based on limited sampling of the R W sl udges . Q uantities p roduced fro m the STPs were estim ated as 250 wet tonnes per week and sampli ng was conducted fo r solids content, heavy metals and pesticides. Approximately 230 t/wk of sludge is n ow being treated . The facility at 40
WATER JULY 2001
T he cu rrent sampling regime consists of monthly co mposite sampl es fro m each STP which aids in tracing any contamination to the source. As well as rou ti ne solids con tent, the samples are tested fo r heavy metals: arsenic, cadmium, chrom.ium, lead, selenium, zinc, mercu1y, copper and nickel. All samples are kept for - 3 months to permit reanalysis in case results require verification. As we ll as routine total so li ds measu re1nent, additional testing of the slu dges was conducted for BOD, pH , chlo ride, sodium and sul phide conce ntrations. T his was undertaken to observe potential effects of dosing fe rric chloride to the sewage on the sludge quality. Fenic chloride has been dosed at one pump station fo r odo ur con trol since 1999 and to date no adverse effects o n sludge quality have been observed. Sludge Results
T he table below lists the treatment plants that R W operates, their capacity and treatm ent process and the annual sludge quantities an d solids content produced. Moisture Content
The variation in moisture content o f th e R W sludge is related to the different processing equipm ent at the plants. Table 1 shows tha t, except for Victoria Po int STP, the plants with digesters yield sludge with a higher TS%. Quantity Produced
Comparing Thorneside STP (BNR plane without digestion) and Capalaba STP
(BNR plan t with digestion) shows how digestion significantly reduces the quantity of wet sludge produced per person . F i g u re 2 s h ows t h e m ont hl y prod uctio n of sludge and the plant flow fro m Capalaba STP since 1997. Sixm o nthl y ave rages (dashed lin es) are imposed onto the data. T here appears to be no seasonal variati on in the quantity of slu dge produ ced. The quantity produced fro m Capalaba STP increased significan tly d uring 1999. Dming this period the upgraded plant was being commissioned and the flow to the plant was increasing. The sludge quantity also increased during 2000. During this period the BNR process was being optimised b ut the flow to the plant was not increasin g. The T S% o f the sludge increased during this period which is an indication that more solids were produced and the treatment process becam e m ore efficient. Fro m the data obtained to date fo r the R W plants, it appears that the main factor that causes a variation in sludge quantity produced is w hen the treatm ent process is significantly changed, eg when a pla nt is upgraded. T his w ill be investigated further when the next plant is upgraded in 2002. Type of Sludge
The sludges are blended and fed to the worms according to the p roductio n ratios in Table 1. The worms accept the blended mixture well (Verm.itech, 2001a). Vermitech is cu rrently u ndergoing trials using unblended sludge from the d.ifferent R W sou rces to investigate the worm's preference.
The sludge from the BNR plants (particula rl y if undigested) needs to be fed relatively soon after arrival to the worm farm to avoid developing anaerobic condi tions and generating odour. I This can be countered by increasing the addition of f deodorising agents or forced aera tion. I f the sl udge becomes anaero bi c, the worms display a tendency to slow down their processing rate. Figure 2. Prod uction of Sludge from Capalaba STP since Potential odour generSeptember 1997. ation from the BNR sludge is an important ongoing issue Victoria Point and are likely to result from as population contin ues to grow and corrosion of water pipes and galvanised in creasing amou nts are produced as R W roofs. T he higher zinc concentration in plants are upgraded to BNR processes. C leveland is thought to be a result of food Figure 3 shows the sludge quantity sup plements in the poultry farming produced each financ ial year and the industries in the area. T he sludges from proportion that is from BNR processes. C leveland STP are Grade C based on the Cu rrently more than 50% of the total resu lts of 3 analytes (copper, zinc and slu dges produced are BNR and this w.ill selenium) and Victoria Point sludge are increase when C leveland STP is upgraded Grade C based on one (selenium) wh ich in 2002. may be attri buted to the use o f antiAlum sludge is produced as a bydandruff shampoos. Even in ca tchm ents product from the Capalaba Water with low industty such as Victoria Point, Treatment Plant .. When blended with the the levels of some metals result in B or other sludges, it has not caused problems C Grade classification of the sludge. to the vermicu lture process (Verm itech,
Product Results Pathogens
Th e results to date on the R W sludge show that when } worms ingest the organic " I material they significan tl y I Th e product reduce pathogens. "f from the R W sludge is A Grade based on pathoge n stabilisation (see Table 3 for the Guideline values). R esults from a 2 year project in Florida, USA, also fo u nd vermicomposti ng to be e ffectiv e in reducing pathogen levels in sludge to C lass A requirements (US E PA standards) (Eastman, 1999a, 19996). During commissioning of the vermiculture facility more than 40 tests of the en d product fo r enteroviruses and helminth ova were undertaken for the EPA to verify the process. All test results were negative. Every 6 months the product is tested for enteroviruses and helminth ova and none have been detected to date. Contaminants ( Heavy Metals, Organochlorides, PCBs)
Table 4 shows the average heavy metal concentrations in the worm castings produ ct from 11 February 1999 to 30 (2001a). It is considered unlikely that the May 2000. Based o n the NSW EPA Testing Procedures for Product worms would find straight alum sludge Gui delines the product is usually low in The testing of the end product (worm palatable due to its low organic content, heavy metals and conforms to B Grade. castings) is undertaken by Vermitech . As however, Skene and Oades (1995) found Any product that is C Grade is diluted a requirement of the environmental that the worms survived and multiplied with B Grade product or inert material licence, the produ ct is tested for parasite in straight alu m sludge. Alum sludge has until it is B Grade. No C Grade material remova l, nutrients and contaminants a high iron and silica conten t which is is allowed to leave site. including heavy metals, organochlorides, beneficial w hen the end product is The reduction in heavy metal concenPCBs and microbiological organisms applied to soil, as these compounds are trations achieved by vermiculture such as salmonella, e-coli and f-coliforms. co nsidered to be plant nutri ents. processing ofRW sludge can be seen by The product is only released when th e comparin g the concentrations in Table 2 met and contingency allowed levels are Heavy Metal Concentrations (RW sludge) and Table 4 (wo rmcastings procedures are in place to deal with nonT he industrial input to the RW product). Some reduction of heavy metal conforming material. treatment plants is relatively concentrations is attributed low although the Cleveland to dilution through the condiro, - - - - - - - - - - - -- -- - - - - - - - - â&#x20AC;˘ca t c hm ent has poultry, tioning agents that are added. electroplating and minor Additionally, the combination ,2000 autornotive indust1y present. o f sludges from different ,0000 treatment plants provides a Table 2 compares the buffer effect on the heavy heavy metal concentrations metal concentrations, as sludge in slu dges from Cleveland ! from multiple STPs ca n (som e industry) and Victoria =f display different concentraPoint (no industry) with the f tions fo r a particular analyte. 20 NSW Environmental Protection Agency (EPA) The value of verrruculture 2000 Guidelines. The industrial as a heavy m etal purifier is still load to the STPs is not in the research phase (Lotzof, direc tly reflected in the 1999). There is no evidence ""'" heavy m etal concentrations from the results ofRW sludge shown in Table 2. The zinc and product that significant Figure 3. Total Sludge Produced by Redland Water and and copper concentrations reduction in heavy metals Percentage BNR Sludge (97 /98 data from September 1997, are similar for Cleveland and 00/01 data up to 31 December 2000) . concentration occurs.
WATER JULY 2001
Table 2 . Comparison of Heavy Metals Concentrations in Sludge from Cleveland STP (some industry) and Victoria Point STP (no industry) (averages from 1 April 1999 to 1 March 2000) with NSW EPA Guideline Values (NSW EPA, 1997). The shaded va lues show B or C Grade concentrations.
The main aim of the project for R W has been achieved. T hat is, to establish a sludge manage m ent fac ility so that landfilling could discontinue. Processing NSW EPA Guideline Values Cleveland Average Victoria Pt Average Heavy the sludge by vermicultu re is saving over (mg/ kg) Cone. (mg/ kg) Metal Cone. (mg/ kg) 13,000111 3 of landfill space per year. Grade A Grade B Grade C A major advan tage of vermicultu re processing is that it is a recognised 20 20 20 5.8 5.7 Arsenic en viron m entally sound tec h no logy 20 5 3 2.9 2 .7 Cadmiu m (http:/ /www. u nep.or.ip/maestro/). In 250 500 100 29 24 Chromium addition, the local community sees the 420 150 42 30 150 Lead worm faci l ity as e n v iro nm enta ll y 50 8.5 5 8 11 Selenium sustainable. R W is achieving 100% 2000 349 100 375 Copper 436 sludge reuse to fo rm a valuable biosolids 270 22 60 125 29 product and believes it has a sustainable Nickel solids m anagement practice. 200 700 2500 641 Zinc 955 1 4 15 ln su m mary: 2.5 Mercury 3.4 • the vermicu lture facility is o perated by Vermitech and provides employment processing fee is higher, if the TS% is T esting results fo r PCBs in the product opportunities for several m embers of the higher then the fee is lower. To date, the to date have indicated no detectable levels. local community TS% of the supplied sludge has been Organochlorides have been detected at • the faci lity cost $3.2 m illion (in 1997) slightly lower resulting in a vaiiation being very low levels (A Grade level) . in construction and commissioning costs paid by RW. Accor di ng t o t h e N SW E PA • the facility covers 1. 5 hectares of land There is also a varia tion in the Gu idelines the wormcastings produced • the facility is built to process up to 300 processing fee w hen the sludge quali ty is fro m the R W sludge qualifies for usage wet to nne/ week of sewage and water C Grade. [f one analyte in the sludge fro m in/on pub li c con tact sites, urban treatment sludge (including stockpiled an STP is high then the sludge is classified landscaping and agriculture. m aterial) as C Grade. This occurs freque n tly but Costs of Vermiculture • the average solids conten t of the slu dge is compensated for by dilution with sludge Processing is 17% (when stockpiled material is not from another STP w hich is low in that included) analyte . R W leases the lan d of the worm fa rm • - 150 tonne/week o f worm castings is site to Vermi tech w hich owns the worm produced fa rm and cover the operational expenses including T he main issue associated Table 3. NSW EPA Guidelines for "A Grade Stabilisation Criteria transport of the sludge to the with the project , from R W 's for Sludge" (NSW EPA, 1997).1 worm farm, any chemical poi nt of view, b as been additions, staff, licence fees, pote n tial odo u r concerns Pathogen Stabilisation Guideline Value testing and analytical costs associated with the storage of Indicators and m a i nte n a n ce . the u ndigested B NR sludge. < 1 plaque form ing unit per 4 g total solids Enteric viruses M anagem ent practices at the T ransportation is the largest < 1 ova per 4 g total solids Helminth ova cos t to Ve rm i t ec h sewage treatm ent plants and < 100 most probable no. per g E coli ( V e rmi tec h , 200 1a ). the vermiculture faci lity have < 100 most probable no. per g Faecal col iforms Electricity and water use at mi nimise d a n y odo ur th e worm fa rm is paid by problems. not detected/ 50 g of f inal product Salmonell a sp RW. Othe r env ir onmental R W pays a per/tonneissues relating to the facility Table 4. Average Heavy Metal Concentration in Wormcasti ngs based fee to Vermitecb for that required att ent io n , Product (Vermitech , 2000) from 11 February 1999 to 30 May processing and disposal of the particu larly during the initial 2000. sludge. The processing fee is stages of the project, include com petitive when compared Concentration (mg/ kg dry weight of sample)1 contairu11ent and collection of Heavy Metal to the Council's previous storm water runoff from the 4.7 Arsenic la n dfillin g costs of $50site and the management of 2.1 Cadmium $60/tonne. large volum es of the stock24 Chromi um piled sludge. T he processing fee is based 39 Lead on a total solids (T S%) and From Vemu tech's point of 7.1 Selenium h eavy metals concentration view, the marketing of the Copper 189 of the sludge as specified in product has been a the orig i nal tender challenging issue. The sale of Nickel 17 document. Any variatio n of th e produ ct has required 504 Zinc solids content greater than sound scien t i fi c res ul ts 1.2 Mercury 20% attracts a variation rate. i nc lu d in g ev i dence of 1 Arithmetic mean values, where BLOD (below level of detection) If the T S% is lower than nutrient values and crop trials readings are recorded as the LOD. LOD for Cd is 2 mg/kg. originally specified, then the as support.
WATER JULY 2001
WASTE The results to date indicate that worm processing reduces pathogens in the sludge to safe levels. However, heavy metal concentrations remain essentially unchanged, A variation of the processing fee has been paid by R W as a result of the solids content and metals concentration of som.e of the sludge. There has been much interest in the operation and performance of the vermiculture facility. As a result Vermitech and R W undertake a number of public open days (every ""' 6 months), and tours are conducted of the facility for school children, the public and professionals from Australia and overseas.
The Future At the time of writing, the contract between R W and Vermitech had been renewed for another 2 years. Vermitech continues to invest significant dollars in research and development for beneficial reuse of the vermicast product produced by the process - Bioverm. It is in R W's interest to keep TS% of the sludge as high as possible as R W pays Vern~itech based on dry weight. R W will be assessing its sludge handling processes at the STPs to maximise the TS% content of the produced sludge. Minimisation of odour associated with the sludge processing is an important ongoing issue as population continues to grow and increasing amount~ are produced as R W plants are upgraded to BNR. To date, one factor that has been a disincentive to biosolids reuse in Queensland is the application of suitable Guidelines that encourage such re-use. Guidelines in Australia relating to biosolids reuse vary from state to state. Currently the only regulatory framework in Australia is the NSW EPA Guidelines and these are one of the strictest standards for the use ofbiosolids sludge worldwide 01ermitech, 2001 b). Ongoing economic development of biosolids reuse needs to continue, including research into use for local conditions. Education and marketing to reposition attitudes to regard biosolids as a valuable resource and not a waste is para111ount The return of nutrients to the soil to continue the nutrient cycle should be encouraged.
Redland worm farm performance and for his valuable input. For more information relating to the worm farm operation contact Vermitech, 55-73 Oxford St, Darlinghurst, NSW, Australia 2010. Website www.vermitech.com
The Author Dr. Sonja Komarowski was Operations Engineer Sewerage with Redland Water for three years and was involved in the contract administration, commissioning, data collection and reporting for the worm farm. She is currently undertaking a Post Doctoral research position at the Institut National des Sciences AppliquCes in Toulouse, France in biological nutrient removal from wastewater.
References Eastman B. R., (1999a) Achieving Pathogen Stabilization Using Vennicomposting. Biocycle, 62 - 64, November 1999. Eastman B. R., (1999b) Vermiculture's Effectiveness as an Alternative to Standard USEPA Class A Stabilization Methodologies.
WEFTEC '99. New Orleans, LA, 9264 9435. LotzofM., (1999) Very Large Scale Venniculture in Biosolids Beneficiation. l,Vlwt's New i11 Waste A,Ja11ageme11t, Dec/Jan 98 - 99, 22- 26. NSW EPA (1997) NSW EPA Environmental Guidelines Use and Disposal of Biosolids Product. Environmental Protection Authority ofNSW, October 1997. Skene T. M. and Oades J. M., (1995) Water Treatment Sludge - A Resource, Not a Waste. Water, May/June 1995, pg 41. V crmitech ( 1998) Successful Biosolids Beneficiation with Vcrmitech's Large-Scale Commercial Vcrmiculture Facility in Redlands. Waste Disposal a11d Water Ma11agemellf i11 Australia, 25 (5), Sept/Oct 1998. Vermitech (2000) Rcdland - BioVerm Average Analysis June 2000. Vermitech Factshcet, 2 pages. Vermitech (2001a) Correspondence with Vermitech. Vcrmitcch (20016) Rcdland - Description of Quality Management and Control System at Vermitecb's Redland Site. Vermitech Factsheet, 2 pages. (http://www.unep.or.ip/maestro/) Internet site Maestro Directory for Environmentally Sustainable Technology, 2001.
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Acknowledgements The author acknowledges Karsten Eisenaecher of Vermitech P IL for supplying technical data relating to the WATER JULY 2001
LIME CRYSTALLISATION SOFTENING OF GROUNDWATER: NEERABUP, W.A. N Herbert, G van Houwelingen, S Sibma Abstract A Lime Crystallisation (also known as Pellet Softening) process has been implem ented at the recently constru cted Neerabup Groundwater Treatment Plant (GWTP) in W estern Australia to redu ce hardness and TDS. T he plant has a maximum treatment capacity of 120 ML/d and a production yield of 33 GL/yr. The plant was constructed in two stages; Stage 1 (an iron ren1oval plant) consisted of pre-chlorination, filtration, flu osilicic acid dosing, a clear water pu1np station and residuals handling, whilst Stage 2 introduced aeration, softening, carbon
dioxide dosing (pH correction) and ferric sulphate dosing - chlorine dosing was converted to post filter. Water Corporation tendered Stage 2 as a Design and Construct project. The winning bid of Bo vis Lend Lease, GHD and D H V Water BV (a major Dutch engineering consultancy) delivered, in close co nsu ltation wi th th e Water Corporation, an innovative design that con1prised; improved control of upward spray aeration, the option to by-pass part of the fl.ow around the pellet reactors, a highly automated, but, f:lexible co ntrol system , and construction of the pellet reactors in concrete.
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WATER JULY 2001
Keywords: Lim e Crystallisation, Pellet Softening, Hardness, Neerabup
Introduction Lin1e Crystallisation chemically, is essentially the sam e as conventi onal softening, but, employs a fluidised bed reactor containing a graded seed n,aterial to signi fica ntly improve reaction kinetics and the form of the reaction by-products (by- p rod u c t calcium car bonate i s produ ced in a pellet fo rm rather than as sludge cake) . Figure 1 illustrates the operation of the flu idised bed reactor. Water flows upward through the fluidised bed. D epending on the water quality either li me, caustic soda or soda ash can be dosed . The ch emicals are dosed at the bottom o f the reactor and mixed intensively with the w ater using specially designed nozzles, in the presence of seed material (garnet) and pellets. Due to the pH change and high concentration of lime, the solubility product of calcium ca rbonate is exceeded and calci u m carbonate crystallises on the surface of the seed m aterial and pellets. As the water travels upward through the f:luidised bed the supersa turation reduces and the crystallisatio n rate slows down. The efiluent of the reactor is still slightly supers aturated w ith calcium carbonate and contains suspended calcium carbonate th at has p rec ipitated on suspended matter in the raw water or on particles present in the chem icals. The supersaturation can be removed by dosing an acid - carbon dioxide is used at N eerabup. Remaining suspended calcium carbonate carry-over can be removed by conventio nal filtration . As a result of the precipitation process the pellets grow and their sedimentation velocity increases. This process reduces the specific su rface available for crystallization near the bottom of the reactor and will result in a reduction of the reactor effi ciency. Pellets are discharged to maintain a high reactor efficiency and to prevent problems with sedimentation of the large pellets on the bottom o r overflow of the seed material from the top
of t h e reacto r. T h e mg/L) . T he Leederville Table 1. Raw water quality and treated water quality standards, mg/L discharge o f pellets is aguifer is characterised by compensated by dosing low levels of hardness Parameter Raw water Clear water standard seed material. T he ratio ( 120mg/ L) and total pH 7.0 7.0 to 8.2 of th e seed material dose dissolved sol i ds Iron 4 .1 < 0.1 to t he pellet discharge (330mg/L), and, moderManganese determines the size of the <0.04 0.1 ately elevated levels of pell ets. Sodium iro n (2-3mg/L). 88 The Lime CrystallPotassium 5 D ur in g co n ceptual isatio n (also known as planning (1995) , hardness Calcium 76 <40 Pellet Softening) process and TDS data for the Magnesium 12 has been imple men ted at superficial aqu ifer w as Total hardness (as CaC03 ) 239 <150 the recently constructed very limited and very Chloride 157 Neerabup Groundwater variable, b u t, clea rl y Sulphate 10 Treat m ent P l an t ind icated th a t a salt Bicarbonate 235 > 73 (GWTP) i n Wes t ern removal process would A u stra l ia to r e d uce Silica (as Si02 ) 17 need to be in cluded in hard ness and TDS . T h e Total Phosphorus th e tre atm ent p lant . 0.5 pla nt has a maximum Options to shandy the Total Dissolved Solids 634 < 500 treatment capacity of120 water by importing the M L / d and a prod uction higher guali ty water from water fro m two aguifers; the unconfi ned yield of 33 GL/yr. Th e plant recei ves e lsew h e re were invest igate d , but, "superficia l" (limestone) aquifer and th e wa te r fro m 32 bores w hich draw water d iscarded due to the lack of nearby high deeper con fined "Leederville" aquifer. that con tains levels of Total Dissolved guality water - the nearest being su rface From a potable water supply perspective, Solids (TD S) and hardness w hich exceed water which would have to be pumped the superficial aquifer is characterised by the Water Corporation' s adop ted levels m ore than 30km . moderat ely h igh leve ls of hard ness o f service. Li me softe ning in pellet Due to the u rgent need fo r the (280mg/L), an d totaJ dissolved solids (700 reactors is used to reduce the concenso urce to be developed (P erth has been mg/L) , and h igh levels of iron (up to 14 tration of caJcium and bi- carbo nate ions experiencing a prolonged period of low prese nt, thereby also redu cing ra in fa ll), i t was decided to 3.2 m Di 3IDÂ˘tcr the T DS to acceptable levels. A develop the scheme in two typical raw water g uality and the stages. Stage 1 would be a direct clear water g uality standards are fi ltration (iron rem oval) process Softened Water p rese n ted in Ta b le 1. T h e u s i ng t h e hi g h er qua li ty un marked sta ndards do not have Leederville bores, and Stage 2 Reactor in Operation specific li mits as such , except (60- 80 m/hr) would incorporate a salt rem ovaJ w he r e they offe nd consumers. process. This app roach allowed more time to enable drill ing of Project history superficial aguifer investigation A strategic review of Perth's bores to gather additio nal water water use and su pply indicated guality data, and to evaluate salt the n eed for 7 to 8 GL of water reduction processes. to b e developed per year. The Neerabup Groundwater Schem e (33GL yield) was iden tified as being the m ost cost-effective sou rce to be developed. T he Nee rabup Groundwater Scheme consi sts of 32 bores, w hi ch run in a 20km line parallel to the coast, and a centralised water treatm e nt plant located some 30krn no rth west of the Perth city centre. In the short term, most of the water fro m the sch e n1e needs to be exported so uth of Perth - a distance of some 55 km. In the lo ng term, most will be consumed in Perth's north ern suburbs with some su b u rbs receivi n g "pu r e" N eerabup water (ie no t mi xed with any other so urces) . The bores in the scheme's well-field were planned to draw
PeUet Discharge (0.8-1.0llUD)
Figure 1. Reactor Operation and Internal Details
Evaluatio n of salt reduction processes (O'Leary & Herbert, 1999) identifi ed lime softening as being the most cost-effective m eans of achieving the Water Co rpo ration's water q uali ty target. The two lime softenin g processes known , conven ti onal li me clarifi catio n an d lime c1ystallisation were evaluated on a technical and economic basis. Although li me crystallisation was fo u nd to be slightly m ore expensive in terms of capital cost, its operating cost was considered to be lower, due to the difference in disposal costs for pellets and iron / li me sludge cake. Pellets had the potential to be disposed of in cost neutraJ or cost positi ve ways, whereas no WATER JULY 2001
such opportu n ities w ere identifie d fo r iron / lime sludge cake. Opportunities identified w ere the poultry and fe rtiliser industries. In the N etherlands, pellets are used by industry fo r acid neutralisation and as poultry feed. CLEAR WELL An additional benefit, which was not so critical at N eerabup and was not costed, was the sm aller Mllk ofllm. plant fo otprint of th e lime Make up Wah r crystallisation process. T he ability o f the lime crystallisation pro cess to Figure 2. Plant Overview Screen allow rapid flow changes water hardness can be ch ecked w ithin 15 was considered an important factor, as was minutes o f m aking a change to lime dose the responsiveness o f the process to rate - this is of particular signifi cance at operating changes. The N eerabup reactors ramp up given the diffe rent travel times can be ramped up from O to 120 M L/d o f w ater from each of the bo res, and w ithin an hour and a half (40 M L/d per allows us to prevent excessive over, or half an hour), which allows ready recovery undersho ot of the target ha rdness level. fro m power spikes or outages. Th e prim ary limitations on the ramp up tim e Pilot trials and preliminary are the ability of the filters to cope with design the hydraulic sho ck of ramp up, and the As the Water C orporation w as aware amou nt of iron that is stirred up in th e of the fa ctors that co uld affe ct the raw water collec tor m ains. Softened
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WATER JULY 2001
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fo rmation of pellets in the lime crystallisatio n pro cess, it undertook pilot trials to examine po tential interferences. (H owes & Mould, 1999: Mould & H owes, 1999) . T he inte1fe rences of con cern were iron and phosporous, both of w hich CLEAR WATER PUMPING h ave t he p ote n t ial to d i s rup t t h e ca l c ium carbonate crystal matrix and result in "fl uffy" pellets that can break up and lead t o excessive carryove r . SUPPLY TO CUSTOMERS H owever, the results of the trials were very fa vourable and indi cat ed that th e process was very robust for Perth coastal groundwater. Follo win g the pilot trials, Water Corporation contracted a consultant to prepare a conceptual design and to prepare tender docum entation for a detailed design and constru ct contract. In a ddi t io n , t wo W ater C orpo rati o n personn el visited several pellet reactors in the N etherlands and two in the United Kingdom. What w as lea rnt from the visit had a significant impact on the tender do cument , in terms of what infonn ation was requested fro m tenderers, and in what design features were expected to be incorpo rated in any design.
Design and Construct Contract Given the nature of the process to be employed, W ater Corporation was keen to ensure that the designer and constructor sho uld work closely together, and that r espo ns ibili ty for t h e de s ig n and co n stru c ti on sho ul d r est w ith one con trac tor. Water Corporation was also keen to ensu re that the designer shoul d work in partnership with th e constru ctor and see the whole "pictu re" rather than wo rk in g in isol at io n . T h e W ate r Corporation wanted the lessons learnt over th e last 10 to 15 years in the N etherlands to be incorporated into its facili ty and fo r th e designer to place the em phasis o n doing a comprehensive design, rather than a quick design. Operability and maintainability were emphasized by the W ater C orporation in its tender. The tender was won by Bovis Lend Lease, GH D and D H V after extensive pre-contractual m eetings, w hich included a formal , joint operability study. T he contract scope comprised the design, m anufa cture, d elivery, constru ction, testing and commissio ning of upwa rd spray aeration, intennediate pumping, Li m e C rystalli sation, rec arbonation , chemicals dosing and storage facilities and
the integration of the ferro us ions in the calcium 70 9.00 Neerabup stage 1 filtration carbonate crystal lattice of 65 and disinfection plant. 8.50 the pellets which could ~ """\. 60 result in fluffy pellets and The H ead Contract was \\ ,, VI 55 ~ 8.00 -~ an increased carry over of between the Water C .§. , \\ '\.. 50 ::I ·§ Corporation and Bevis Lend suspended matter from \\ 7.50 i 45 ' :ii the pellet reactors. Lease with subsequent backc:l \\ 40 7.00 t o- back co ntra c t s being \ Aeration consists of 35 established between Bo vis upward sp ray aeration 30 6.50 Lend Lease, GHD and D HV. banks. The design ensures Raw Water Aerated Effluent Effluen1 Effluent Effluent Effluent Applied Clearwater Water AoactOf 1 ReaCIOf 2 Reactor 3 Reactor 4 Reactor 5 Water G HD were responsible fo r operatio n of the optimal Channel the design and documennumber of spray nozzles: Location tation of the plant whilst efficien t aerat ion is I-+- Calcium (uf) ....... Calcium (f) pH I DHV were responsible fo r the achieved without wasting process engineering. pumpin g ene rgy. The Figure 3 . Calcium/pH Profile through Plant aerated water flows into a From the outset of the detention tank t h at project the Water Water Corporation was overall pleased Corporation had made it clear that th ey with the way in which the consortium ensures sufficient detention time to oxidise wa nted to adopt a partnering approach to undertook the work. Furthermore, the at least 90% of the iron. The level in the the project and to this end organi sed a Water Corporation was very pleased with tank is used to trim the transfer pumps that Partnering Workshop. Through all phases the working relationship it has had with fee d the reactors. of th e project the partnering philosophy all of the members of the consortium. Four transfer pumps feed the header was foste red and e ncouraged. This pipe to six pellet reactors. T he flow is approach worked well and paid dividends Process design distrib uted over the operating reactors by to aJI parties. Figure l shows a flow diagram of the flow control valves. Li me is dosed in the D u ring th e D esign Phase a Project Neerabup WTP . Water fr om t wo reactors and ga rn et sand from Geraldton D esi gn Office was established with in borefields is transported to the aerator. (300 km North of Perth) is used as seed G H D's offices and personnel from the Dissolved gases are removed from the water material. Product water quality is Water Corporation, Bovis Lend Lease and fe rro us iron is oxidised to the ferric monitored at the top of the reactors. OffTechnical Services Gro up and DHV state. This preven ts incorporatio n of spec water can be discharged by closing the statio ned themselves in this office and were able to assist GHD with the conceptual and ongo ing design . Weekly design m eetings we re held to resolve design issues and mo nitor progress. In the latter phases of construction, BLL appoi nted a spec ialist Commissioni ng Engineer to monitor and understand the o n-site installation of the mec hanical, The Australia- East Timer Community Water Supply and Sanitation Program, planned to commence later this year, will be managed by an experienced elec t rical and controls aspects of the and dynamic Team Leader. This exciting position, based in Dili and working in project. H e developed a commissio nin g partnership with the East Timorese Office of Water Supply Services and programme and, in conj u nction with the wit h the support of NGOs, will be responsible for t he planning and delivery Wate r Co rpo ra tion's Commission in g of improved water supply and sanitation for remote communities in three Coordinator and team, was responsible for districts, Bobonaro, Covalima and Viqueque. This is a unique opportunity to play a leading role in the improvement of the living conditions and public plant commissioning. It shou ld be noted health of rural communities rebuilding their lives in East Timer and in the tha t the Wate r Corporat i o n 's development of national skills in the rural water sector. Com.m issioning Coordinator travelled to the Netherlands to witness, fo r two ACIL Australia Pty Ltd, one of Australia's leading international development wee k s, the co mmissio ning of a new plant companies, is seeking expressions of interest from suita bly qua lified and experienced Team Leaders for this interesting and challenging program. The ther e. DHV returned to si te for process Team Leader will have a background in the water industry and will be able com.m issioning and arranged operator t o demonstrate experience in human resources development. Overseas training by an experienced plant superinexperience and some language skills (Indonesian) will be well regarded. te nde nt from a Dutch water company. A useful featu re included in the contract Full details of this position (Reference OS0394) and other opportunities can be found on our website at www.acil.com.au. For further information, between Water Corporation and BLL, was please contact Mike Gray or Robert Anscombe, or forward your expression that their Comrnission ing Engin eer was of interest to email@example.com. requi red to remain o n site fo r a further three months following commissioning in Te lephone (03) 9819 2877 Fax (03) 9819 42 16 orde r to assist w ith rectifying an y equipment faults and provide support to ACIL Australia the operators. D espite DHV being so distant in the 854 G lenferrie Road Netherlands and the organisation of the International Development Consultants Hawthorn 3 122 and Project Managers VIC consorti um (three compani es) which does affec t communications and relationsh ips,
International Team Leader WATER SECTOR East Timor
WATER JU LY 2001
discharge valve of the reactor whi ch results in water overflowing to the wash water recovery system. Carbon dioxide and ferric sulphate are dosed to the softened water to remove the supersaturation of calcium carbonate and to im.prove the filtrability of the suspended matter. The water then flows to the filters.
Blending operation The plant design allows by-passing th e aeration and reactors with part of the flow. In that operation mode a considerable reduction of chemicals consumption can be achieved. The raw water contains sufficient iron for coagulation and sufficient carbon dioxide for removing th e supersaturation from the reactor effiuent. This removes the need for dosing ca rbon dioxide and ferric sulphate. Additionally considerable savings o ccur in power consumption for the transfer pumps and in li me consumption. This aspect of th e plant is still undergoing evaluation of efficiency and reliability.
Physical design Hydrated powder lim e is transported to the plant by tanker trucks and stored in two silos. Each silo has a lime mixing tank in which a 2% milk of li me is produced. This lime is circulated through a dual ring main system. Distribution over the reactors is achieved by m eans of control valves. Garnet is stored in one silo. Fines are washed out of the garnet before the garnet slurry is dosed into a reactor. Pellets produ ced are pumped as a slurry to two silos and drain ed and stored there. Carbon dioxide and ferric sulphate facilities are present to allow operation of th e plant without the by-pass. When sufficient expe rience has been gained with the blending operation , the need for these dosages will diminish.
Control and Operator Interface Screens T he Neerabup WTP was d esigned as a remo tely operated faci lity. An operator is prese nt durin g the day, but, remotely monitors the plant o utside o f this time via a lap top and modem. T he operator is also able to make changes to process parameters via the lap top. Significant effort was spent on developing the operator interface screens for the plant so as to enhance operator learning, ease of use and display of plant/ process status. Particularly challenging was the development of the screen for controlling plant flow, because of the need for the reactors to control bore operation despite all the variation in bore water quality. 48
WATER JULY 2001
Figure 2 is the plant overview screen and gives an indica tion of the standard of finish and the user frie ndliness of the operator interface screens.
First operating experiences Process commissioning of the plant commenced in J une 2000. The softening performance of the reactors when they were brought into op eration inrn1ediately met theoretical proj ections. Equipment, hydraulic and reactor carryover issues presented the main challenge to commiss10n111g. The major equipment and hydraulic issues experienced were as follows; 1) Air entrainment and vortexing in the reactor softened-water pipes was greater than that anticipated. This led to th e installation of air relief tubes back to the top of the reactors. 2) Failure and over-sensitivity of lime backpressure valves due to the need for them to be excessively throttled. This has been overcome by using smaller size valves and reducers. 3) Excessive use of carbon dioxide due to poor dissolution in the dissolution circuit. This was corrected by th e package supplier, who redu ced the operating pressure of the dissolution circuit (removal o r su bstitution of valves and fittings in the circuit that were consuming head) and increased the contact time p rior to dosing of the softened water. 4) Blinding of the surface of the filters caused by ca rryover from the reactors and milk of lime . This issue has been addressed through the replacement of the previous media with a coarser filtercoal and improvem ent to th e particle sizing of the lime by the lime supplier. 5) Blocking of the entry from lime weighfeeder to milk of lime tank due to bridging of moistened lin1e powder. This bas been resolved by installation of heating tape around the neck of the tank opening Process parameters investigated during commissioning were as follows; 1) R eac tor uptlow rate (alterati on o f residence time in reaction zone) , 2) Pellet discharge size (alteratio n of surface area in reaction zone), 3) Use of different milk of lime concentrations (change in saturation conditions in reacti on zone and reduction of calcium carbonate in milk of lime), 4) Number of lin1e lances in use , 5) Raw water hardness and degree of final soften ing (alters lime dose rate and satu ration conditions).
Figure 3 illustrates a typical water quality profile through the plant du ring the early stages of plant optimisation. T he difference in filte red and unfiltered calcium levels for the reactors is a reflection of the amount of calcium carbonate carryover (precipitate) at the time and the efficiency of the reactors. A 2 to 3mg/L difference is the target. The effect of carbon dioxide dosing can be seen readily in the applied water channel (AWC) filtered calcium results, w hich are 2m g/L higher than those of the filtered calcium results for the reactors. This represents the dissolution o f calcium carbonate micro- flo e and is quite typical of reactor operation.
The Authors Neil Herbert is the Senior C hemical Engineer, Water Treatment, Infrastructure D eve l o pm ent Bra n ch (e m ai l neil. herbert@wa terco rpora tion.com.au) and Sjoerd Sibma is the Operations Superintendent, Groundwater Operations, Water Produc tion Services Branch (email sjoerd.sibma@watercorporation .com.au at th e Wat er Co rpor ati o n , PO B ox Le ederv ille WA 6902. Gerard van Houwelingen is a Senior Water Specialist with DHV Water BV, P. O . Box 484, 3800 AL A m e rsfoort, Th e N et h e rl ands (GA.VanHouwelingen@WA.DHV.NL)
References H owes D . & Moulds, 13. (1999) P ellet softening for sa linity and hardness reduction at Neerabup, Western Australia. IWSA, f,Vater S11pply. 17 (3/ 4), 7-13 Moulds B & Howes D (1999) Lime crystallisation fo r softening water and reducing salinity f,Vater 26 (1) 11 O' Leary B . & H erbe rt N. (1999) D evelopment of water treatment processes for Perth's future groundwater schemes. IWSA, vVarer S11pply. 17 (3/4), 397-404
Other Useful Papers Ammers, N . van; Dijk, J. C. van, Graveland, A. & Nuhn P.A.N.M. 1986 State of the art of Lime C rystallisation. Water Supply 4 A111sterda111, 223-235. Dijk, J.C. van & Wilms, D .A. 1991 Water treatme nt without waste material - fundamentals and state o f the art o f pellet softening. Aqua 40(5), 263-280 Eekeren M .W .M . van, Paassen, J.A.M. van & Merks C.W.A.M. 1994 Improved milk oflime for softening of drinking water - t he answer to the carry-over problem. Aqua 43 (1 ), 1- Âˇ10
Acknowledgments This paper is largely based on a paper " P e ll e t Softeni n g at N eer abup Groundwater Treatment Plant, W estern Australia" presented by H erb ert N, Earl], van Hou we li ngen H ; at t h e IWA Conference, Amsterdam, September 2000.
YOUR COMPLETE GUIDE TO THE FASTCHANGING ENVIRONMENT SECTOR
The Australian Environment Directory Hallmark Editions, publishers of Environment Business newsletter and The Green Guide, have released a significant new reference and resource publication, The Australian Environment Directory. This new 424-page Directory gives a comprehensive overview of the entire environment sector al Federal and State levels, allowing readers to quickly identify which departments, agencies, sections and units have particular responsibilities and roles such as greenhouse abatement, biodiversity and environment protection. Branches and divisions are listed as well as the support programs and funding opportunities they manage, providing a unique insight into the management structure of the departments and agencies. This allows the right contact person to be quickly and easily identified. In each State and Territory Chapter, details are included of programs run by government departments and EPAs. These range from waste minimisation and greenhouse reduction through to air quality, catchment management, land, coastal and marine management. Local Government environmental bodies, and the non-government environmental organisations are described in detail. The major environmental programs in the Federal and State sphere are linked back to the relevant departments and agencies allowing readers to clearly locate the source of the program. Identifying the funding sources available through the range of Federal and State bodies is a key feature of the Directory which includes an index to allow For quick cross referencing. Thoroughly researched by the team which produces the monthly Environment Business newsletter and The Green Guide update service, the Directory is totally up-lo-date and is an invaluable 'who's who' of the environment sector. There are specific chapters of environmental educational facilities at more than 30 universities including science, engineering and environmental management. Research centres and agencies within universities and State Governments are listed in the research section of the Directory, allowing readers to quickly identify the research teams and projects in fields such as water, solid waste management, and alternative energy. More than 700 organisations, research bodies, educational institutions are listed in the Directory. Contact details include address, telephone and fax numbers, email and websites. The Directory will be updated annually. The Australian Environment Directory (ISSN 1443-9360) retails for $90 (includes $8.18 GST). Hallmark Editions is GST registered - ABN 71 592 093 415.
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THE FUTURE OF WATER IS IN OUR HANDS C Porter It's time for the industry to show support for community education about water. Water management in Australia requires an integrated approach from all directions with co-operation between communities, government departments and the water industry. T o achieve our goal of w ater sustainability one of the essential target areas is edu cating the comm unity, be cause an informed community is empowered to contribute to sensible decisions. To date , water educa ti on has generally been confined to demand management. The future success of water sustainability, though, and basic education about water and wastewater management is vital. To be effective, education must meet these criteria: • Be factual and impartial - aimed at enabling people to decide for themselves, • B e entertaining and fun, • Have programs for all learning styles and all levels and ages in the community, • B e provided to existing gro ups in the comnmnity with skill, imagination and enthusiasm, • B e provided well in advance of any consultation on specific issues, and • Be adequately funded . Doesn 't it all seem very daunting? It might, but not so much when you realise that material is already available. AWA has been supporting development of a suite of educational materials to improve community knowledge and understanding of water and wastewater management issues. This material is designed to promote discussion about ways in which water may be used in a more sustainable way. It is now complete, ready fo r printing and we are seeking support to get it out to the community. We All Use W ater contains : 1. A comprehensive 230-page fo lder covering W ater Sources, Catchments, Pathogens, At the Water T reatment 50
WATER JU LY 2001
• • • • • • • • • • • •
Plant, Water at W ork, At the Sewage Treatment Plant, On-site Systems and Eilluent Management; 2. A series of 30 flyers containing condensed information from the fo lder; 3. A colour poster and storybook set about the 'Coetanger River Catchment' that presents different ways that water and wastewater can be managed; 4. A Presenter's Manual including extensive training notes, overheads, PowerPoint presen tations and instructions for interactive resources; and 5. Th e Biolog i ca l Nutrient R e duction Poste r, explaining the reactions w ithin a BNR plant using effective visual techniqu es. Im portant topics covered by We All Use Water are: • W ater Sources • Water Storages • Groundwater • R ainwater tanks • Catchments • E utrophication • Pathogens • Disinfection of W ater • At the Water Treatment Plant • Drinking Water Monitoring
Water Testing Endocrine Disrupters Evaluating Risk Water at Work Wastewater At the Sewage Treatment Plant Star Rating Biological Nutrient R eduction Advanced Treatment Sludge and Biosolids O n-site Systems E ill uent Management J enifer Simpson, in collaboration with an experienced proj ect team, compiled the resources, with money from the Natural H eritage Trust and support from t he Sunshine Coas t Environment Council. This has culminated in a suite of material presenting information in a co mpact, easy-to- read and well- illustrated package and it includes all the tools needed to fill the gap in people's knowledge . With strong industry support, AWA can move on to deliver W e All Use Water for the benefit of all stakeholders. Clare is keen to hear fro m yo ur organisation now. Sponsorship enables AW A to print and promote the resources. Thanks to Burnett Shire Council and the Sydney Catchment Authority for their confirmation of Gold Sponsorship, Patawalonga and Torrens Catchment Water Management Boards for Bronze. Orders for flyers are available and are being collected for the fi rst bulk printing at the end of this month. Coetanger Poster and Storybook se ts are avai lab le from the A WA Bookshop. BN R Posters available from QLD Branch (07) 3397 5644, $95 each (incl. GST & Postage) All queries to Clare Porter, PO Box 388, Artarmon, NSW 1570, Phone (02) 9413 1288, Fax (02) 9413 1047, E-mail: e d u ca tion @a wa. as n. au , l nternet: www.awa.asn.au