Water Journal May - June 1996 by australianwater

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AUSTRALIAN WATER & WASTEWATER ASSOCIATION

Volume 23, No 3 May/June 1996

Editorial Board

ÂˇcoNTENTS

F R Bishop, Chairman

ASSOCIATION NEWS From the Federal President From the Executive Director

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B N Anderson, G Cawston, M R Chapman P Draayers, W J Dulfer, G A Holder M Muntisov, P Nadebaum,J D Parker AJ Priestley,] Rissman

Advertising & Administration

MY POINT OF VIEW Building a Strong Australian Water Industry

Tony Wright ÂˇWASTEWATER FEATURE - CRC FOR WASTE MANAGEMENT & POLLUTION CONTROL Overview of CRC for Waste Management & Pollution Control

Features Editor 8

I Fergus Advanced Wastewater Management

J Keller MEDLI - Bringing Effluent Irrigation Design Into the 21st Century

R Davis, E Gardner Membrane Technology for Wastewater Reuse

A WDay Advanced Constructed Wetlands: An Ecotechnology Option for Today

HJ Bavor Modelling Aerobic Denitrification

E von Munch, J Keller, P Lant WATER Biological Iron and Manganese Removal: an Untapped Potential

I Cameron Granular Activated Carbon Pilot Plant Studies

ARBN 054 253 066

Federal President

Executive Director

Mark Pascoe

Chris Davis

I Bergman ENVIRONMENT 39

NJ Schofiel.d, PE Davies Environmental Auditing of Wastewater Treatment Plants

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Networking the German and Australian Water Industries

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OUR COVER Australian Environmental Technolof!j for a Cleaner Worl.d The CRC for Waste Management and Pollution Control Limited, Australia 's leading environmental research and development organisation, is devoted to finding commercially viable solutions to major environmental challenges that impact on the quality of air, water, soils and landscapes.

Australian Water & Wastewater Association assumes no responsibility for opinions or statements of facts expressed by contributors or advertisers and editorials do not necessarily represent the official policy of the organisation. Display and classified advertisements are included as an informational service to readers and are reviewed by the Editor before publication to ensure their relevance to the water environment and to the objectives of the Association. All material in Water is copyright and should not be reproduced wholly or in part without the written permission of the E4itor.

Subscriptions Water is sent to all members of the AWWA as one of the privileges of membership. Non members can obtain Water on subscription at an annual subscription rate of $35 (surface mail).

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CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL

OVERVIEW OF CRC FOR WASTE MANAGEMENT & POLLUTION CONTROL I Fergus

This feature outlines the activities of this CRC in the area of wastewater. It describes in detail four of the projects which are at the stage of commercialisation. The authors of these reports can be contacted through Ian Fergus at CRC for Waste Management and Pollution Control Ltd, University ofNSW Ph (02) 385 5774 Fax (02) 662 1971. The Cooperative Research Centres (CRC) Program is a brave experiment by the Federal Government, launched in May 1990 to solve the problems of poor links between research and development, and business opportunities, as well as providing a new way of managing and supporting research. The Program has established 62 centres of excellence in fields as diverse as information technology, agriculture, medical science, mining, energy and the environment. Over the seven years until they become self-funding, the CRCs have a collective budget of $2. 7 billion, with 310/o coming from the Federal Government, 140/o from industry and the rest from universities, publicly funded laboratories and state government departments. The CRC program emphasises the importance of developing an international competitive environmental management industry. The CRCs are now an established element of Australia's culture. Since over one quarter of the program's investment comes from the Australian taxpayer, you should be interested to learn about the outcomes from the CRC for Waste Management and Pollution Control Ltd. With 15 member organisations including world ranked corporations, leading Australian research institutions and major government departments and a budget of $50 million, the CRC is a powerhouse of skills, expertise and relevant experience devoted to the task of developing viable solutions to major environmental problems that impact on the quality of air, water, soils and landscapes. The CRC's research programs are focused to address the following issues: waste reduction and minimisation; sewage treatment and water quality; contaminated site remediation; instrumentation and monitoring; the disposal of waste from intensive rural industries; onsite treatment of liquid waste; safe disposal of liquid wastes as solids; control of odours 8

and atmospheric emissions; social ecology of waste management; improved design and control of waste treatment operations; solid waste disposal. A broad cross section of the Australian environment industry is represented through the members of the CRC. It is the most commercially oriented of the 12 environment CRCs and operates as an incorporated company owned by its members.

Research Program Projects managed in the Wastewater Research Program include: advanced constructed wetlands for nutrient removal from wastewater; compact wastewater treatment plants; membrane systems for wastewater re-use; on-line monitoring of industrial pollutants; automatic analysers for phosphate and algal biomass; treatment of waste streams from intensive rural industries; novel conducting membranes for treating industrial effluents; optimal management of water treatment plant residuals; design and control of biological wastewater treatment plants.

Where We Are At Now entering its fifth year the CRC is about to launch several innovative wastewater management/environmental technologies. Four of the products generated from the research program to be introduced to the market during 1996 are: Project 2.1. Advanced Constructed

Wetlands Technology in Pollution Control: Integrated Nutrient Removal/ Pollutant Management. Over the past three years, the CRC has invested around $3.0m to generate operational data and an understanding of system performance on advanced constructed wetland technology for sewage polishing applications. A new company,

Australian Constructed Wetlands Technology , is being formed by CRC members NSW Department of Land & Water Conservation and the University of

Western Sydney, to exploit this technology development. Project 2.5. Membrane Systems for Wastewater Re-use. This project involves

the development of membrane-based processes for the treatment of sewage to produce water for re-use up to potable quality standard. A unique combination of experience within the CRC has been brought together involving Memtec, UNESCO Centre for Membrane Science and Technology (UNSW) and NSW Public Works and Services. Memtec will commercialise the outcomes of this re;earch. This project is focussed on production of quality water for local needs by extracting and treating sewage from the nearest sewer. Simplicity of operation of the principal process avoids the need for secondary treatment. Independent technical review by world recognised experts concluded that this novel technology development is unique and offers several major advantages and significant potential benefits to the wastewater community. Extensive pilot plant operation has demonstrated that the screening/microfiltration system is effective in achieving the feedwater quality to suit reverse osmosis {RO) final stage treatment. This CRC is proceeding to Stage 2, incorporating RO and will complete this research phase late 1996. Project 5.1 - Management of Waste Streams Usi,ng Land Irrigation. MEDLI®

{Model for Effluent Disposal using Land Irrigation) is a computerised model for the management of effluent disposal, developed jointly by the CRC and the Queensland Department of Primary Industry with funding support from the Land and Water Resources Research and Development Corporation, the Urban Water Association of Australia and the Pig Research and Development Corporation. Initially MEDLI® will be applied to effluent disposal from intensive rural industries and sewage treatment plants. MEDLI®is in the final Beta testing phase. WATER MAY/ JUNE 1996

Project 10.1. Improved Design & Control of Waste Treatment Operation.

This project, led by the Queensland Node of the CRC, part of the Department of Chemical Engineering at the U:niversity of Queensland has been operating since 1992. The CRC has invested $3 million in this large R&D project to be completed by mid 1996. This research team has developed a strong expert base in wastewater treatment ponds, biological nutrient removal (BNR) activated sludge plant, high rate anaerobic treatment operations, microbiology of wastewater treatment systems. The research team has been appointed to lead a IR&D Board project to demonstrate the modelling and simulation of BNR systems, in collaboration with Sydney Water Corporation, NSW Âˇ Department of Land and Water Conservation and Water Studies Centre of Monash University. The wastewater activities in the Queensland Node of the CRC will soon be integrated into a new Advanced Wastewater Management (AWM) Centre. The AWM will further strengthen the expertise and knowhow of the R&D team. Products generated by this research project will be commercialised during 1996. Detailed information on the above research projects is featured in the articles that follow this overview.

WATER MAY/ JUNE 1996

Interactive Linkages The Cooperative Research Centres Water Forum initiated in 1995 is a group of CRCs with a common interest in water related issues. The five CRCs in this Forum are CRC for Waste Management and Pollution Control, CRC for Catchment Hydrology, CRC for Freshwater Ecology, CRC for Soil and Land Management, CRC for Water Quality and Treatment. The Forum will explore areas of joint research and international activities and will provide a platform from which members may contribute to the political and community debate regarding water and environment management issues. Environment Management. The CRC has began to commercialise its outcomes through both its members and other suitable partners. This challenging task is enhanced by the CRC's links with the Department of Industry, Science and Technology, the Environment Management Industry Association of Australia and their joint initiative, the Environment Industry Development Network (EIDN). The EIDN is administered by the CRC and it is funded by $4.5 million over four years from DIST's Auslndustry Program. The main mission of the EIDN is capability building, consortia formation, project facilitation and project financing to accelerate the development of an internationally competitive industry. Some key industry problems the

EIDN aims to overcome are: the small size of Australian firms, lack of prime contractor capability, access to leading edge and export markets and commercialisation of innovative technologies. EIDN is based at the CRC's central office in Sydney and also has offices in Brisbane and Canberra.

How to Get Involved? The CRC system has changed the approach of Australian researchers so that stronger links are being developed with research users, particularly industry. Our CRC is keep to interact more effectively with small to medium sized enterprises (SMEs) in the water management industry. We are is currently formulating a strategy to ensure access by SMEs to our research and training activities eg. the use of our CRC for demonstration sites, sponsorship of postgraduate students and assistance of SME employees to work in our CRC on a temporary secondment basis. The author would welcome approaches from SMEs interested in collaboration in these areas.

Author Ian Fergus has a wide background in water and wastewater engineering and membrane technology involving both applied research and commercial application. He is Program Manager, Water and Wastewater, for the CRC for Waste Management and Pollution Control.

CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL

ADVANCED WASTEWATER MANAGEMENT j Keller The Queensland Node of the CRC for Waste Management and Pollution Control, situated in The University of Queensland, has been operating since Âˇ 1992. A large project on "Improved Design and Control of Biological Wastewater Treatment Plants" (Project 10.1) has been the main activity in the water sector of the Node since then. This R&D project has developed a strong expert base in a wide range of wastewater treatment aspects such as wastewater treatment ponds, biological Nutrient Removal (BNR) activated sludge plants, high-rate anaerobic treatment operations, and microbiology of wastewater treatment systems. In all these areas, the focus of the research work is on the effective and successful integration of existing expertise in the areas of process engineering, information technology and environmental microbiology. The University of Queensland, and in particular the two Departments involved, has a strong background in these fields. The R&D challenges posed in modem wastewater treatment processes require expertise in all of these areas as the technologies and the operational possibilities are becoming increasingly more advanced but also more complex. This development is not much different from past experience in various process industries where at some stage effective improvement and optimisation is dependent on the utilisation of a wide range of skills and experience. Based on this overall strategy, a large project team was established early in 1992 to address challenges in the four areas listed above. In that sense, this project is significantly different from most other CRC WMPC projects in that it is involved in four different research fields which are quite separate but all are related to and certainly benefit from each other. The team includes three principal researchers (at academic or postdoctoral level), eight postgraduate students, an administrator and a number of academics with part-time involvement. The central location of the whole project team in The University of Queensland has proved to be a major benefit to the project. Direct day-to-day interaction between the 10

researchers in various fields and of different backgrounds is strongly encouraged. This is the key element in achieving effective cross-disciplinary collaboration. The research focus, the outcomes to date and the future direction are summarised in the following sections. These are, necessarily, quite short and somewhat superficial, but detailed scientific and technical papers have been published in the past in Water (Lant and Steffens, 1995, Pollard et al, 1995, Bond et a~ 1994) and a number of international journals. One further example (von Munch et a~ 1996) is included in this current issue. All of these publications are available from the CRC WMPC Queensland Node.

and utilisation of what is one of the most economical form of wastewater treatment. The team has developed a radically new approach to pond design by using Computational Fluid Dynamics (CFD) to simulate the flow pattern in the pond. Because the technique is based on the fundamental mass, impulse and energy balances it enables, for the first time, the prediction of effects caused by pond shape, inlet/ outlet structures, aerators and baffles on the flow behaviour in the pond. This method offers significant benefits both for upgrades of existing ponds and the design of new ones. Based on the improved understanding of the hydrodynamics in a pond, existing knowledge , of the biological wastewater treatment principles allows the development of a more efficient design and operational strategy for ponds. A pilot study aimed at improving the nutrient removal performance of aerated ponds treating industrial wastewater is underway in collaboration with the Meat Research Corporation. We have made good progress to date and are currently validating the models with actual data from ponds. Nevertheless, a range of issues will need to be addressed further in the future. These will include fundamental aspects such as the detailed verification of three-dimensional CFD models but also more practical problems related to the selection and characterisation of aerators in the overall design process.

Activated Sludge Treatment

Project 70. 7 - Drilling to check ifgroundwater is contaminated by nearby wastewater treatment pond

Clever Ponds The objective of this research work is to improve the hydrodynamics {flow pattern) in ponds and the nutrient removal capacity of these wastewater treatment systems. These are seen as two major opportunities in the further development

The research in this area focuses on operational aspects of these treatment plants based on a process engineering perspective. This strategyÂˇ has been chosen for two main reasons. Firstly, in most process industries significant improvements can be achieved with optimisation of the operational conditions including process control, particularly with systems that have widely varying input streams as is certainly the case in most wastewater treatment facilities. Secondly, the industry seems to be strong in design expertise but relatively weak in operational skills and knowledge. WATER MAY/JUNE 1996

The aim of the research team (and an increasing number of operators) is to achieve improved effluent quality control at minimal capital and operating costs. This will lead to increased treatment capacity for new or existing plants. The main focus of this work has been on Biological Nutrient Removal processes as they are becoming more popular but also put significant demands on the operator skills. Furthermore, while the process is successfully applied in a number of full scale plants, the fundamental understanding is still quite limited. The collaboration between microbiologists and process engineers has already achieved significant progress and will be even more valuable in the future . The research work incorporates modelling and simulation of BNR systems, .controller development and investigations on prefermentation systems. Further development, demonstration and commercialisation of these technologies is underway as part of a recently commenced, $2.4m IR&D Board project in collaboration with Sydney Water Corporation, NSW Department of Land and Water Conservation and The Water Studies Centre (Monash University). This project has the potential to generate an international reputation for the team as the research is on a par with the leading countries in wastewater treatment technologies.

Anaerobic Treatment The use of (high-rate) anaerobic treatment systems has gained increasing popularity for a wide range of industries such as breweries, canneries, food processing. It is of particular interest to companies currently discharging to sewer and facing increasing trade waste discharge costs. The separate treatment of a major organic load source before discharge to the sewer can be an economically favourable alternative to increasing the capacity of an existing plant. The treatment is very effective for the removal of high concentrations of carbonaceous substrate (COD , BOD). Early problems with process stability have been overcome and minimizing operating costs is now the main objective. Advanced process design and operation, as has been developed by the research team, utilises model-based optimisers to continuously monitor the plant load and performance and adjust the operating parameters accordingly. This on-line optimisation development is particularly suitable for industries with large daily variations in wastewater flow and load and can reduce total operating costs significantly. A process optimisation system is currently being implemented on a full-scale plant to demonstrate the benefits of this novel approach. In the future , the solubilisation of particulates will be studied in more detail. WATER MAY/JUNE 1996

The current work has shown a distinct need for such research as it is relevant to a wide range of treatment systems from high-rate anaerobic reactors to sludge digestors and prefermenters. The effective collaboration in a multi-disciplinary team will again be crucial for successful progress and outcomes in this R&D area.

Microbiology We are well aware of the important role of microbial activity in biological treatment systems, and the examples above show the benefits achieved in utilising knowledge available in this area. A strong research group has been established over the duration of this CRC WMPC project and their aim is to develop a better understanding of the fundamentals in biological wastewater treatment. This will have major benefits for the development of better designs and operating strategies leading to an overall improvement in the performance of biological treatment systems. The team is using the latest scientific tools and equipment to take a large step forward in the knowledge available for such complex microbial communities as a Biological Nutrient Removal activated sludge. The focus is mainly on the nitrogen and phosphorus removing organisms as well as sludge bulking and foaming filaments. In parallel, the in-situ measurement of bacterial growth rates offers exciting opportunities in current R&D activities. The significance of the leading edge work undertaken in this field has already been recognised by the industry here in Australia. Three AWW A awards in the last two years (Best Paper Presented at an AWWA Conference 1994/ 5, Best Paper by Queensland Branch Members 1995 and Best Poster Presentation at 16th Federal Convention, Sydney, 1995) are a proud testimony of this recognition. This strong reputation will be further enhanced by the recent decision to attract a world leading researcher for a CRC WMPC Postdoctoral Fellowship position to our research team.

The Advanced Wastewater Management Centre In parallel to this large CRC WMPC project, the team has gained significant experience from work on other projects and services related to biological wastewater treatment. These range from academic research projects to collaborative (contract) R&D and specialist consulting assignments. The level of expertise acquired in virtually all biological wastewater treatment systems makes this CRC WMPC Node unique in the wastewater R&D field in Australia. Furthermore, the Node has expanded its focus to broader aspects of wastewater management including wastewater minimisation at source, recycling and beneficial reuse.

The CRC WMPC Board has recognised the potential of the expertise and the project team and has therefore approved the establishment of the first Strategic Research Cluster in the CRC. The aim of these clusters is to maintain and further develop expertise and knowledge in strategic R&D areas of importance to the CRC members and the environment industry in general. The wastewater activities in the Queensland Node of the CRC WMPC are now integrated into the Advanced Wastewater Management Centre at the same location. The establishment of this Centre of Excellence, to which The University of Queensland and the involved Departments have contributed significantly, will further strengthen the expertise and knowhow of the R&D team. It will also expand the activities into related areas, thereby covering an even broader range of wastewater management needs. The major objective of this new Centre is to undertake quality R&D work for a range of customers. This is already underway and projects have been performed with (semi-)government research organisations (eg. ARC, IR&D, CRC's); industrial R&D bodies (eg. Meat Research Corporation, Sugar Research and Development Corporation); local councils and public organisations (eg Brisbane City Council, Sydney Water Corporation); industrial companies such as abattoirs, canneries, breweries, food and mineral processing, refineries, sugar mills, fisheries, etc.; process and equipment suppliers; consultants. Our aim is to balance research activities, critical to maintain a high level of expertise, with directly applied research and development tasks that are identifying and fulfilling the needs and demands of the industry. This is only possible in a dedicated research team with a wide range of expertise, effective collaboration and suitable infrastructure. We have achieved most of this in the last three years and we will continue to build on it.

References Lant P, Steffens M (1995} Status of ICA in the Australian Wastewater Industry, Water 22 (4), 32-33 Pollard P C, Keller J, Blackall L L, Ashbolt N J, Greenfield, P F (1995). Direct Measurement of Bacterial Growth in Activated Sludge. Water 22(4), 34-37. Bond P L, Blackall L L, Keller J (1994). Phosphate-Removing Microbes - New Insights on Their Ecology. Water 21(6), 17-20. von Munch E, Keller J, Lant P (1996). Modelling of aerobic dfil!itrification in sequencing batch reactors. Water.

Author DrJurg Keller is project leader ofProject 10. 1 Improved Control & Operation of Biological Wastewater Treatment Systems. 11

CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL

MEDLI - BRINGING EFFLUENT IRRIGATION DESIGN INTO THE 21 ST CENTURY R Davis*, E Gardner* Introduction There is increasing community and government concern about the degradation of Australian inland waters and marine resources, motivated in part by the occurrence of major algal blooms in the Darling River in 1991/1992, and various freshwater impoundments since then. In a survey of nutrient sources entering the Murray Darling system, Gutteridge, Haskins and Davey (1992) identified sewage treatment plants as a major source of N and P (about 25% of total load) in low flow periods. They went on to say that wastes from feedlots and piggeries in the Murray Darling Basin had the nutrient generating capacity of up to 5,000,000 people, but cautioned there was no evidence these nutrients (and reactive organic matter) were actually entering the river system. Any point source of waste is a focus of attention by regulatory authorities, and intensive rural industries and STP's have probably had more than their fair share over the last few years. In most Australian states, there is a requirement under planning legislation to submit an EIS before any new development can be built, and usually licensing requirements are imposed on operational practices once the enterprises are in production. The absence of a mutually agreed set of assessment tools has, on occasions, caused some angst between developers, their environmental consultants and regulatory authorities. However, the intensive rural industries (e.g. feedlots, piggeries, tanneries, abattoirs, poultry farms etc) have not been passive bystanders whilst concern on their environmental sustainability has grown in the community and government. A number of workshops were sponsored by the Pig R&D Corporation (Anon 1992a), the Meat Industry Research Corporation (Lake 1992) and the Dairy R&D Corporation (Anon 1992b). The workshops usually identified land disposal of effluent as the most critical environmental issue facing the industry. Strong support was also expressed for "scientifically justifiable, site specific environmental regulations including land disposal" (Lake 1992). The Federal Government, via its agency the DPIE, commissioned a study into waste management practices by 12

intensive rural industries in Australia. Bowmer and Laut (1992) then reported on current practices, the research underway, and identified as high priority the development of a decision support system on effluent disposal to integrate current knowledge to assist "individual industry managers as well as regulatory and catchment management authorities". The intensive rural industries also responded to these recommendations by sponsoring various research/ collation projects to package existing information on waste generation and disposal practices. Examples are the Effluent at Work book by the PRDC {Kruger et al, 1995), the Irrigators Guide for Abattoir Operators (by MRC) as well as water balance/irrigation models for sewage treatment plants (Anderson and Ruge 1994) and generic industries (e .g. NSW Environmental Protection Authority NSW 1995).

Project Structure The CRC for Waste Management and Pollution Control Ltd and the Queensland Department of Primary Industries initially responded separately to these industry demands, but both had a similar vision - the development of a user-friendly interactive computer model which integrated waste production with a climate-driven irrigation water balance model, which dovetailed into plant growth, nutrient cycling and soil salinity balance modules. Both organisations envisaged a model that could be used by the designers of effluent disposal/reuse sites, and the government agencies that assessed these designs. If both sides of a development proposal could agree on a common assessment methodology, then the inevitably robust discussions could concentrate on parameter values etc, rather than the calculating methods/ algorithms used. Such a change would maximise the chances of a win/win situation occurring for those developments which produce lots of biological sourced wastes in environmentally sensitive areas. It was planned that users would be able to describe different reuse area designs, whilst the model would keep water, nutrient and salt balances on a daily time step over a sufficiently long time period (e.g. 100 years) for the long

term consequences of the disposal activities to be assessed.~ Because of the similarity of the projects, in mid 1993 the CRC and QDPI decided to combine their efforts into a systems model called MEDLI - Model for Effluent Disposal using Land Irrigation. The QDPI effort was financially supported by LWRRDC, UWRAA and Pig RDC.

Design Principles The CRC-QDPI team made five basic design decisions at the time of joining forces. Firstly, the model should be capable of modelling the effluent stream from its production in an enterprise through to the disposal area. In feedlots and piggeries, this policy allowed the effects of diets, cleaning protocols and effluent recycling to be explicitly considered in predicting the waste stream volume/ composition. Insufficient information was available for predicting waste stream characteristics from abattoirs at that time. A subsequent MRC sponsored waste audit of representative beef abattoirs may allow this omission to be remedied in a later version of MEDLI. The second was that the model should be able to predict the fate of the following parameters: water, phosphorus, nitrogen, soluble salts, volatile solids, pathogens. These are the main parameters of interest to managers and regulators, but for certain industries (such as tanneries) other parameters such as chromium may need to be added. We also found out that predicting the transport and source of pathogens was trickier than first thought, and thus it is not included in the first version of the model. A third design decision was that the model should be flexible enough to b e used for a range of intensive rural industries with the initial emphasis on: • Piggeries, •Cattle Feedlots, • Abattoirs, • Sewage Treatment Plants,• Dairy Sheds. We expect that as industry experience in MED LI grows, the , model will be adapted for other intensive rural industries such as tanneries, wool scours and • CRC for Waste Management and Pollution Control Ltd t Resource Management Institute, Queensland Department of Primary Industries

WATER MAY/JUNE 1996

food processing plants. Our fourth design decision was to use existing algorithms wherever possible because most have been extensively tested, and there is a considerable base of knowledge available on their use. Finally it was important for the model to cater for users with different levels of experience. Consequently MEDLI has a user-friendly interface to input, edit and display model outcomes, with a simple expert system to warn against improbable combinations of parameter values. We have also allowed for default values for diet, soil, and treatment pond parameters etc to be selected by the inexpert user, in the Enterprise Design section of the model. For an advanced user, editing and input of site specific data is catered for in the Technical Design section. This ensures that the user of the Âˇmodel has maximum control over what data is entered and how it is used in the calculations.

ments if one or more values are outside the usual ranges. The model manager ensures that the components are called in the correct sequence and that the data are transmitted correctly from one component to the next. Each component model can produce a number of output variables of interest to the designers and regulators of effluent disposal schemes. For example, the pond components can predict the frequency of over-topping, the leakage to groundwater, the change in soil nutrient concentrations, etc. The user can select which of these outputs are to be graphed. In addition to graphical output, there is an extensive text summary report that provides ready checking on input parameters, mass balances and average (or yearly) output parameters such as nitrate leaching, irrigation application and frequency/ volume of pond overtopping, to name but a few.

MEDLI Design

Testing

The final design of the MEDLI software is shown in Figure 1. There are 12 component modules, each describing a part of the effluent production and disposal process. Table 1 gives the algorithms used at present. We intend to add other algorithms to let the user choose a particular algorithm for a particular component, as well as add other modules (e.g. pathogens). The user interface runs under the Windows 3.1 operating system on PC computers. One set of menus allows the user to describe the design of an intensive rural industry. The type of industry (abattoir, piggery, etc), the size of the operation, the number and size of effluent ponds, the size of the disposal area, etc would all be entered in these menus. Another set of menus allows the user to enter the technical parameter values required for the algorithms. The composition of the animal rations, the expected animal weight gain, the composition of the waste stream, the hydraulic characteristics of their soils, the growth characteristics of the crops would all be entered in these menus. Where possible, MEDLI supplies default values for these parameters but it is the user's responsibility to ensure that appropriate values have been selected. The expert system helps the user select the values of the technical parameters. A set of rules has been supplied by those experienced in modelling to describe the usual range of parameter values. These rules are conditional, in that the expected range of one parameter can be dependent upon the values of other parameters. After entering proposed parameter values, the user can ask MEDLI to comment on whether there is anything unusual in these values. The expert system will supply a list of com-

Rigorous testing of models is usually a prerequisite before they are released for general use. To adopt a similar policy for a complex model such as MEDLI would have been prohibitively expensive and probably not feasible with the data currently available. As an alternative, the MEDLI team developed a four prong attack on the validation issue. Firstly, all the algorithms

WATER MAY/JUNE 1996

were checked independently of the code developers, to ensure the code reflected the documented algorithms. Algorithm checking also involved some test bedding to ensure changing input values affected outputs in the same direction and magnitude as that expected from the code (e.g. larger Curve Numbers and smaller soil water deficits generate more runoff). Secondly MEDLI was put through the hoops by Beta testers, composed of people from government agencies (in Queensland and New South Wales) responsible for checking the effluent disposal designs for intensive rural industries proposals. Thirdly MEDLI was tested by a small number of commercial environmental consultants on real world design tasks to compare answers from MEDLI with those from their normal design tool kits (e.g. tables, spreadsheets, published precedent and personal experience). Finally, MEDLI is being checked against results from a LWRRDC funded, purpose designed experiment in South Australia (the Braun project), where piggery effluent was applied to a sandy soil, growing potatoes. The minimum check of any model output is the common sense test - are the outputs in accord with the results expected from the users experience and insight? This requires of course that assessment of MED LI output must be done by an experienced effluent dispasal designer/asses-

USER INTERFACE

EXPERT SYSTEM

MODEL MANAGER

Wet weather

Lagoon chemistry

Waste

estimation

Lagoon salt balance

Rainfall-runoff

sto rage Âˇ irrigation area balance

Root zone

N and P

Inorganic

N cycl ing and

Groundwater

salinity balance

up1akc

P sink

lc:iching

transport and

dilution

Figure 1 Structure of the MEDIJ program

Table 1 Component Models and their algorithms used in MEDIJ Model Component

Algorithm

Waste estimation Primary treatment Lagoon chemistry Lagoon salt balance Rainfall-runoff Storage-irrigation water balance Root zone salinity balance Plant growth

Mass balance algorithms and DAMP (Barth, 198.5) Proportioning algorithm Casey (1992) Mass balance algorithm SCS Curve Number (Knisel, 1980) PERFECT (Littleboy et al, 1992) SALF (Shaw and Thorburn, 1985) GRASP (McKeon et al 1990) and EPIC (Sliarpley and Williams 1990) EPIC (Sharpley and Williams 1990) Freundlich isotherm HSPF Gohanson et al., 1984) CERES MAIZE Gones and Kiniry 1986) and HSPF Gohanson et al, 1984) Dillon (1989)

Nutrient uptake Inorganic P sink N cycling and leaching Groundwater transport and dilution

sor. This is being done in cooperation with agency and consultant staff. The MEDLI model is well documented, and allows a wide variety of "what if' questions to be answered quickly, which should lead to innovative, cost effective and environmentally sustainable design. Nevertheless when MEDLI is released for general use, it is likely that problems will emerge, and requirements will arise, that were never anticipated by the MEDLI developers. The model developers will be there to support MEDLI's commercialising partner to ensure these problems and requirements are fixed promptly!! Where can I get it? The CRCQDPI developers of MEDLI have signed a licensing agreement with the well known Australian hydrologic software company WP Software Pty Ltd to market and support MEDLI. It is anticipated MEDLI will be released in the spring of 1996.

References Anderson, J M and Ruge, T . (1994) Effluent Reuse: Land and Wet Weather Storage Requirements. Urban Water Research Association of Australia. Technical Report No. 80. Anon (1992a). Waste Management Workshop. Gazebo Hotel, Sydney, October 1992. Pig Research and Development Corporation, Barton, ACT. Anon (1992b). Managing Dairy Shed Wastes. Vol 1. Proceedings of a Workshop, Dairy

Research and Development Corporation, Melbourne. Barth C L (1985). Livestock Waste Characteristics - a New Approach. PP 286294. In Agricultural Waste Utilisation and Management', Proceedings of the Fifth International Symposium on Livestock Wastes. American Society of Agricultural Engineers, St.Joseph, Michigan. Bowmer K, Laut P (1992). Research Areas Pertinent to Intensive Rural Industry Waste Management. Divisional Report 92/ 4. CSIRO Division of Water Resources, Canberra. Casey K D (1992). A Computer Model to Evaluate the Design of Anaerobic Lagoons for Pig Wastes. Unpublished Masters Thesis. Clemson University, North Carolina, USA. Dillon P J (1989). An Analytical Model of Contaminant Transport from Diffuse Sources in Saturated Porous Media. Water Resources Research 25(6), 1208-1218. Kruger I, Taylor G, Ferrier M (eds) (1995) Effluent at Work. - Australian Pig Housing Series. NSW Agriculture. Environmental Protection Authority (NSW) (1995). The utilisation of treated effluent by irrigation - draft environmental guidelines for industry. Gutteridge, Haskins and Davey (1992). An Investigation of Nutrient Pollution in the Murray-Darling River System. MurrayDarling Basin Commission, Canberra. Johanson RC, Inhoff,J C, Kittle] C, Donigan A S (1984). Hydrological Simulation Program - FORTRAN - HSPF. Users manual for release 8.0. USEPA, Athens, Georgia. Jones C A , Kiniry J R (ed.) (1986). CERESMaize. A simulation model of maize

growth and development. Texas A&M Univ. Press, College Station, TX. Knisel, W.G. (Ed) (1980). CREAMS: A Field Scale Model for Chemicals, Runoff and Erosion from Agricultural Management Systems. Soil Conservation Research Report 26, US Department of Agriculture. Lake M (1992). Abattoirs, Feedlots and Tanneries. R&D Priorities in Waste Management. Environmental Technology Committee Research Report No. 2. QDPI, Brisbane. Littleboy M, Silburn D M, Freebairn D M, Woodruff D R, Hammer G L, Leslie J K (1992). Impact of Soil Erosion on Productivity in Cropping Systems. Australian journal of Soil Research. 30, 757788. McKean et al., (1990). Northern Australian savanna-management for pastoral production.] Biogeography, 17, pp.355-372. Sharpley A N, Williams J R (eds.) . (1990). EPIC-Erosion/ Productivity Impact Calculator: 1. Model Documentation. U.S. Department of Agriculture Technical Bulletin No. 1768. 235 pp. Shaw RJ, Thorburn P J (1985) Prediction of Leaching Fraction from Soil Properties, Irrigation Water and Rainfall. Irrigation Science, 6, 73-83.

Authors Dr Richard Davis is Senior Principal Research Scientist, Rivers and Wetlands Program, in the CSIRO Division of Water Resources. Ted Gardner is Principal Scientist in the Resource Management Institute of the Department ofNatura'[ Resources, Qjleensl,and.

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WATER MAY/JUNE 1996

CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL .

MEMBRANE TECHNOLOGY FOR WASTEWATER REUSE A WDay'; of water mining processes that cover the full range of the cost versus treated water quality spectrum will provide the water industry with the opportunity to optimise the potential benefits of the water mining concept.

Abstract The CRC for Waste Management and Pollution Control's Project 2.5 Membranes for Waste Water Reuse, is developing a range of water mining processes to reclaim water at the users' site using the nearest sewer as the raw water source. The project is scheduled to have proven a novel, purely physical process that produces near potable quality water direct from the sewer by September 1996. Preliminary data indicates that BOD's and TOC's of the order of 1 mg/ L are achievable together with total nitrogen and total phosphorus levels of less than 5.0 mg/ L and less than 0.lmg/ L respectively. The development of a complete range

High Quality Reuse Water The largest application for membranes in waste water reuse is for the production of very high quality recycled water for either indirect potable or industrial use, the feed source being treated sewage effluent. The application began 20 years ago with the commissioning of Water Factory 21 at Orange County Water District in California USA. Water Factory 21

Table 1. Reclaimed Water quality at various process points Raw sewage

After Screening "Pilot scale"

After RO "Pilot scale" "Bench scale" After CMF

Suspended Solids average mglL

380

126.2

1.5

BOD5 average mglL

NIA NIA NIA NIA NIA

234.1

94.2

102.8

44.4

0.7

50.1

44.2

2.8

40.4

39.4

2.2

11.2

9. 1

0.05

TOC average mglL TKN average mglL NH4 average mglL Total P average mglL

reclaims secondary treated sewage to meet US drinking water standards using lime clarification, sand filtration and reverse osmosis. Reverse osmosis is a membrane process that physically removes dissolved substances from water. Notably this includes a good deal of the dissolved organic carbon as well as the majority of the soluble ionic species. The cost of this technology has been significantly reduced over the last eight years by the replacement of the lime clarification and sand filtration steps with microfiltration pretre3;tment. The lower cost is achieved through higher productivity in the reverse osmosis system, reduced consumption of chemicals and reduced disposal/recycle costs for the lime sludge. Additional savings have been demonstrated because the microfiltration pretreatment has allowed the use of the more recently developed and cost effective Thin Film Composite "TFC" reverse osmosis membranes. These TFC membranes operate at 700/o less pressure than the cellulose acetate "CA" membranes that have been traditionally used in waste water applications. They also eliminate the need to dose acid to reduce pH which is required to control hydrolysis of cellulose acetate membranes. MacCormick and Johnson (1996) summarises trial data relating to the various processes described above.

M icrofiltration

Water from Untreated Sewage

Reverse Osmosis

Raw sewage

CMF backwash to sewer

from sewer

main

Sewer extraction

Backwash to sewer

::=~~========~~:::J Potable Near quality water RO concentrate return to sewer

Sewer Main

Figure 1 Simplified flow schematic ofPilot Plant at South Windror, NSW WATER MAY/JUNE 1996

Water mining is a recent development where water is reclaimed at the users' site using the nearest sewer as the raw water supply. Unreclaimed waste is returned to the sewer to be treated at the conventional treatment works. This concept allows the reclamation process and distribution systems to be optimised together to give the lowest total cost. Barnett and Howe (1994) report on a water mining plant that has been operated by ACT Electricity and Water â&#x20AC;˘ Memtec Limited, Locked Mail Bag 1. Windsor NSW 2756 15

Corporation in Canberra for the last 12 months. Project 2.5 (Membranes for Waste Water Reuse) at the CRC for Waste Management and Pollution Control is developing treatment technologies that are optimised for water mining rather than for conventional waste water treatment. The project's overall scope includes a number of processes that cover the full range of the cost versus treated water quality spectrum.

Indirect Potable Reuse and Boiler Feed Water To date the focus has been on the development of a novel process that uses a double membrane barrier to produce near potable quality water from raw . sewage. Water of this quality is required for some industrial applications (such as boiler feed water) and for indirect potable reuse. Figure 1 is a simplified flow schematic of the purely physical process that is being piloted at South Windsor in North West Sydney. The first two stages of the 100 tpd pilot plant (screening and microfiltration) were commissioned in July 1995 and have operated reliably for over eight months. The third stage {reverse osmosis) has been successfully operated at bench scale for three months from December 1995. The pilot scale reverse osmosis

stage will be commissioned by June 1996. Table 1 summarises the performance of the screen and microfiltration systems over a period of eight months based on between 10 and 50 samples. The data provided for "After RO" refers to bench scale data obtained from the best performing TFC reverse osmosis membrane tested over a one month period based on 4 samples. At the time of writing the screening and CMF systems have operated successfully with stable effluent quality for more than eight months. Whilst the pilot scale reverse osmosis system has not yet been commissioned the bench scale results are encouraging and indicate that proof of process will be achieved by September 1996.

Non Potable Urban Water Reuse and Industrial Cooling Towers Non potable urban water reuse and industrial reuse for cooling towers do not require near potable quality water. Water quality suitable for these reuse applications could be obtained using biological treatment for carbon removal, rather than RO. It is proposed that the next major milestone will be the development of a process that adds a biological stage to the screening and rnicrofiltration stages to produce a low BOD effluent that is clarified and disinfected. Phosphorus removal

One Day International Symposium

Water Reuse for the Community and Industry Latest Developments and Future Directions

August 1st, 1996 This one day Meeting brings together International and Australian experts to discuss the latest developments in Water Reuse. Topics will include: • Strategic Directions - presented by the Environmental Industry Development Network (EIDN) • Community Consultation and Water Reuse • Overviews of Water Reuse in California and Australia • Advanced Membrane Technology in Water Reuse • Water Reuse in the Process and Mineral Industries • Reuse of Treated Municipal Effluent The Meeting would be of interest to those in Local Government, the Water Industry, Process and Mineral Industries, and Environmental Management.

Registration Fee: $300 (includes Proceedings and refreshments) Venue: University of New South Wales (Kensington Campus) For details contact: Prof. A.G. Fane UNESCO Centre for Membrane Science and Technology FAX: (02) 385 5054 16

can be achieved by the addition of ferric salts for applications such as cooling tower water or for non potable urban water reuse where there is a large distribution network.

Irrigation Irrigation applications where there is no need for treated water storage or large distribution networks could be serviced by the simplest and least expensive water mining process which is screening followed by rnicrofiltration. This process has been proven and the effluent quality is summarised in the second column of Table 1.

Conclusion Membrane systems have been proven as reliable unit operations in waste water reclamation. Recent developments of double membrane processes have led to significant cost reductions in this most traditional application of membranes to waste water recovery. The recent development of the water mining concept allows the reclamation process and distribution systems to be optimised together to give the lowest total cost. Within the water mining context, membranes offer operational advantages over conventional wastewater treatment technologies. For example they provide easier odour control, reduced space requirements, reliable intermittent operation and are easy to automate. Project 2.5 'Membranes for Waste Water reuse' is focused on the significant opportunity to optimise water reclamation technologies to meet the specific requirements of water mining. The purely physical process to produce near potable quality water that is described in the text is a good example of this optimisation. It should be possible to provide a range of optimised processes that cover the full spectrum of the cost versus treated water quality spectrum by combining screening and CMF with othertechnologies. For example reverse osmosis, biological removal of soluble BOD or ferric dosing for phosphorus removal can be added to meet specific water quality objectives.

References MacCormick A B and Johnson W T, Tandem Membrane Treatment of Secondary Sewage Approaches The Current Price of Potable Water, to be presented at WaterTECH, Darling Harbour, Sydney, 27 - 28 May 1996. Barnett K E and Howe D C, Water Mining in the ACT, AWWA Recycled Water Seminar, Newcastle, May 1994.

Author Tony Day of Memtec Limited is Project Leader of CRC Project 2.5: Membrane Systems for Wastewater Reuse. WATER MAY/JUNE 1996

(~ CRC FOR WASTE MANAGEMENT AND POLLUTION CONTROL

ADVANCED CONSTRUCTED WETLANDS: AN ECOTECHNOLOGY OPTION FOR TODAY HJ Bavor* Constructed Wetland Technology: The utilisation of constructed wet• provide the CRC with a competitive Integrated Nutrient Removal/ Pollution lands for waste management and pollucommercial advantage in the design, conManagement" as part of the CRC Sewage tion control serves as an exemplar in the struction and operation of constructed and Water Quality Program. wetlands for pollution control. development of ecotechnology in the CRC Partners who were involved in CRC Project 2.1 was launched in July emerging era of ecologically responsible 1992. The objectives of the project were to : direct participation in the research prowaste management and pollution control. • refine and optimise CWS's for wasteDuring the past decade, numerous gram are set out below: constructed wetlands have been installed water treatment, through the effective • University of Western Sydney, integration of physico-chemical and bio- Hawkesbury (UWSH) and tested for treatment of waste-water and the amelioration of • University of New South Wales water pollution arising from non-point sources. • University of Queensland • Commonwealth Scientific Studies of these systems & Industrial Research have clearly demonstrated Organisation - Division of that they can reduce the Water Resources (CSIRO) concentrations of organic • Public Works Department matter, suspended solids ofNSW and indicator bacteria by > Department of Water 90%, while requiring relaResources NSW* tively little maintenance. (* Now Department of Constructed wetlands are Land & Water Conseralso being increasingly vation NSW) used for polishing of Sydney Water already treated wastewaAustralian Nuclear ter, as an adjunct to conScience & Technology ventional and advanced Organisation effluent treatment technologies. The Project research While it is clear that was centred at the Water wetlands can be used for Research Laboratory, nutrient reduction and polUWSH, with field activities lution control, empirically focussed at the UWSH derived, reliable perforExperimental Wetlands mance and design criteria Facility. have not been available to The CRC directed confidently implement the research and development technology. Further, verification data for assessment Project 2.1 Wetlands demomtration at Australian Centre of Excellence of towards three products, by regulatory authorities is Advanced Comtructed Wetlands at University of Western Sydney - Hawkesbury specifically identified for commercial markets not often available for involving domestic sewage effluent treatregional applications. In recognition of logical processes. ment: , the need for this technology infrastruc- • provide a centre of excellence in conProduct 1 - 'Package' Constructed sultancy for the establishment and continture, cost savings/ economic potential and the valuable ecological attributes of uing operation of wetland systems for polWetland Systems A compact, low cost, easy to operate, lution control. constructed wetlands technology, the • provide a centre of excellence in wet- • Water Research Laboratory, University of partners of the CRC for Waste Management and Pollution Control land technology for the basis of PhD Western Sydney, Hawkesbury, Richmond, training and post-doctoral research. Limited funded Project 2.1, "Advanced NSW 2753 WATER MAY/JUNE 1996

4.50 Phosphorus concentration at wetland exit 4.00 3.50 3.00 2.50 2.00 1.50 1.00 - - -- --------:•=---- - - - -- - - - - - = - - - - - - - - - M a x .\ _,~ 0.50 a 0.00 30/6/92 1/7/91 1/7/90 1/7/94

Total P-

mg/I

I • ••

•

• • •

.-·....•-,,,"' .. ...~~-cDate

Figure 1 Phosphorus concentration at the outlet of the Byron Bay Constructed Wetland System, receiving input loadings of 3 to 5 mg

Plm2/yr. Note the maximum license limit of 1. 0 mg!L. Peak concentrations monitored in 199 7 and 1992 were associated with upstream treatment plant malfanction total treatment vertical flow wetland package ready for marketing to a wide range of commercial users. Product designs for units ranging in size from single household to 500 person systems have previously been successfully demonstrated at Byron Bay, Coffs Harbour and a number of additional sites. Utilisation of Team developed package system formats has been incorporated into new design formats which have been successfully utilised to treat primary settled sewage to phosphorus concentrations of <1 mg L- 1 and disinfection to <100 faecal coliforms per 100 ml.

Product 2 - Custom Designed LargeScale Constructed Wetland Systems Design/Performance Criteria A suite of empirically based design and performance criteria for site specific design and operation of large-scale (5 0-20,000 EP}, free water surface, constructed wetland systems for domestic sewage effluent polishing. Design criteria, establishment/ operation strategies and performance estimation expertise have been developed to the extent that the Wetlands Team is considered to be an international leader in the field.

Product 3 - SWAMPM - Simulated Wetland Analysis and Modelling Program A computer based decision support system for the evaluation and design of constructed wetland systems for domestic sewage effluent polishing. SWAMP is envisaged to be marketed initially as part of a consultancy service, with development to a licensing stage. The Program has been developed in modules which enable an experienced operator to assess and confidently select from a range of design options· with respect to nutrient removal performance and preliminary water balance. The package is able to be used to support Product 2 activities, and options for co-development and/or licensing are being consid18

ered. Current research has indicated that in managed CWS's, phosphorus loadings in the order of <3 - 5 g/m2/ yr have been successfully used as a 'sustainable' input loading (Bavor and Andel, 1994; Roser and Bavor, 1994}. This loading may be achieved on either an input P concentration or hydraulic loading basis. However, recent work by Mann and Bavor, 1993, has suggested that increasing the retention time of the effluent (via reduced hydraulic loading} may result in increased P removal for a given mass loading of orthophosphate. Removal efficiencies of 60 - 90+% have been noted in monitored systems which have been receiving well-treated effluent (with P concentrations of 1.0 mg/ L or lower} for more than 4 years (Soukup et al., 1994; Patruno and Russell, 1994; and Bavor and Andel, 1994}. Constructed wetland performance has been firmly substantiated in effluent polishing situations summarised in a database reported by Knight (1994} . Mean phosphorus input levels of 1-2 mg/ L were reduced to output levels of 0.005 to 0.3 mg/ L at mass loadings of around 3 to 4 g P/m2/ yr for effluent input loadings of around 190 m 3/ ha/d (ranging from 6 to 2,740 m3/ha/d}. Performance of the Byron Bay Constructed Wetland System falls within this range, with specific managed sectors of the system giving reduction of inlet P concentrations of 1 mg/ L down to 0.06mg/ L, at mass loadings of 11 g P/m2/ yr and effluent loadings of around 300 m3/ha/d. It has been established that constructed wetlands technology is now entering a phase in its development where it can provide reliable water and wastewater treatment in a wide range of circumstances. Process modelling is established to enable reliable algorithms to estimate a system's ability to remove major pollutants, assuming a range of design specifi-

cations. Constructed wetlands are now a viable option for utilisation in a wide range of water management situations, as an ecotechnology solution in urban, rural and industrial applications.

Acknowledgements As well as funding from the CRCWMPC, support from the Byron Shire Council and the NSW Department of Public Works is also gratefully acknowledged.

References Bavor, HJ Andel, E F {1994) Nutrient removal and disinfection performance in the Byron Bay Constructed Wetland System. Water Sci. Tech. 29(4):201-208. Knight R L {1994). Treatment wetlands Water Environ. Technol. database . 6(2) :31-33. Mann RA, Bavor, HJ {1993). Phosphorus removal in constructed wetlands using gravel and industrial waste substrata. Water Sci. Tech. 27(1)107-11 3. Patruno] and Russell]. {1994). Natural wetland polishing effluent discharging effluent to Wooloweyah Lagoon. In: Bavor HJ and Mitchell D (Eds.) Water Sci. Tech Wetland Systems in Water Pollution Control, 29(4): 185-192. Roser DJ Bavor HJ (1994). SWAMP*: A computerised decision support system for employing constructed wetlands in the biological removal of nutrients and other water pollutants. BNR2 Conference Albury October 4-6. Soukup A Williams RJ Cattell F CR Krogh M H (1994). Function of a coastal wetland as an efficient remover of nutrients from sewage effluent: a case study. In: Bavor H J and Mitchell D (Eds. ) Water Sci Tech Wetland Systems in Water Pollution Control, 29(4) :295-304.t

Author Professor John Bavor is Director of the Water Research Laboratory at the University of Western Sydney, Hawkesbury. He is the Project Leader for CRC Project 2. 7. WATER MAY/ JUNE 1996

WASTEWATER

MODELLING AEROBIC DENITRIFICATION E van Munch\ J Keller, P Lant Abstract The issue of aerobic denitrification, or simultaneous nitrification and denitrification, has become the focus of much debate at several recent Australian wastewater treatment conferences and workshops. It is not our intention in this paper to add to the debate, but rather to provide a means of mathematically describing this phenomenon. We do not claim to have an explanation of aerobic denitrification, but merely to be able to explain the observations. We are hopeful that this will prove useful for all users of dynamic simulators of BNR processes. Aerobic denitrification has been observed by many researchers and wastewater treatment plant operators. This paper describes a modification to the IAWQ Model No . 1, that enables this model to account for the phenomenon of aerobic denitrification in activated sludge systems. It is proposed to decouple the rate equations for aerobic and anoxic growth of heterotrophs by introducing a new parameter, KA . An experimental technique to identify this parameter is presented. The modified model is then applied to a sequencing batch reactor system.

Key Words

tinguish between true aerobic denitrification and denitrification due to anoxic regions within the floe (V. Schulthess et al, 1994). It is therefore unclear whether aerobic denitrification occurs on the basis of a biological phenomenon (Robertson, 1994) or a physical phenomenon (diffusional limitations of the oxygen flux into the floe). The model for aerobic denitrification described in this paper does not attempt to explain why aerobic denitrification occurs, that is whether it is a physical or biological phenomenon. It merely enables a description of the effect of aerobic denitrification on bulk liquid concentrations. The Activated Sludge Model No. 1 (Henze et al., 1987 a, b) is a dynamic mathematical model for the design and operation of biological carbon and nitrogen removal activated sludge systems. This model is now widely accepted and employed in the wastewater treatment industry. However, the anoxic growth part of the model deserves further study, especially the effect of dissolved oxygen (Patry and Chapman, 1989). This is the focus of the present paper. The aim of this modelling study was to model the phenomenon of aerobic denitrification via the IAWQ Model No. 1 with minimal increase in complexity.

Aerobic denitrification, simultaneous nitrification and denitrification, SBR.

Model Description And Modification

Introduction

The Model No. 1 describes substrate limitation and inhibition via the concept of "switching functions", which "switch process rate equations on and off' as environmental conditions change. These functions were chosen more for their mathematical convenience than conformity to any fundamental rate laws. Processes that only occur during aerobic conditions, such as aerobic growth of heterotrophs, are "switched on" by a switching function of the form: (Eq.l)

The phenomenon of aerobic denitrification (or simultaneous nitrification and denitrification) has been described by a number of authors (Moriyama et al., 1990; Masuda etal., 1991; Kokufuta etal., 1988; Halling-Soerensen and Hjuler, 1992; Kugelman et al , 1991 ; Ho, 1994; von Mi.inch et al., 1995). All of these authors observed a smaller rate of production of NOx under aerobic conditions from the oxidation of ammonium than would be expected from nitrification alone. The heterogeneous nature of activated sludge systems makes it difficult to dis-

On the other hand, processes that occur only when dissolved oxygen is absent, e.g. anoxic growth of heterotrophs, are 'turned on' by a switching function of the form:

(Eq.2)

This switching function represents the inhibition of anoxic growth by the presence of oxygen. In the Activated Sludge Model No. 1, the switching function constant K0 H is the same for aerobic growth as for anoxic growth, so that as aerobic growth declines, anoxic growth increases. However, there is no biological or physical justification why the switching function constant for anoxic growth should be the same as for aerobic growth. As there is experimental evidence that aerobic denitrification does occur it is necessary to increase the rate of de~itrification under aerobic conditions. Conventionally, the rate of anoxic growth of heterotrophs is written as follows (Henze et al. 1987 a):

(Eq. 3)

Where p represents the process rate (mg/ lid) . Three options are available to increase this rate, ~: Increasing the oxygen half-saturation coefficient for heterotrophs Ka H> the anoxic correction factor T\ ' or the maximum specific growth rate ol heterotrophs 11__ rtt,max â&#x20AC;˘ Higher values for the latter two parameters would increase the rate of denitrification at any given DO concentration'. There is no experimental or theoretical justification why the rate of denitrification should be increased at zero DO concentration in a â&#x20AC;˘ Department of Chemical Engineering, University of Queensland, St. Lucia, QJd 4072

WATER MAY/JUNE 1996

system that displays aerobic denitrification. A more feasible option would be to increase K 0 H" This, however, would simultaneously reduce the rate of aerobic ~owth of heterotrophs according to Eq. (4).

denitrifiers will also be increased. The model would therefore predict higher substrate utilisation rates. This might lead to the necessity to reduce the correction factor '11 . Validation data with respect to substratl utilisation rates is difficult to obtain and this is not investigated further here.

Parameter Identification It is proposed to modify the IA WQ Model No. 1 in such a manner that the oxygen inhibition of anoxic growth is decoupled from the oxygen limitation of aerobic growth, thereby enabling the description of simultaneous nitrification and denitrification. To enable this decoupling, a new switching function constant for aerobic denitrification, KAD' is intro_duced in the process rate expression for the anoxic growth of heterotrophs, p 2. The modified rate equation is shown in Eq. (5):

K,o

JI Hmm · - . ·---,·

+.\ K..- 0 +.\ 0

S,vo X , · !/, RH K,v0 +S.vo

Unlike the oxygen half-saturation constant for heterotrophs K0 H' the new switching function constant KAD can be determined for each system via simple batch experiments with the activated sludge of the system. To do this, denitrification rates (rDenitr_) at different DO concentrations have to be measured. The data obtained is then fitted with a two parameter optimisation routine to the following function : (Eq. 6) =r

AD l'

AD+ •>o

The rate of denitrification can generally be calculated according to Eq. (7):

It should be noted that the introduction of a new parameter KAD will not only have the desired impact on nitrate/nitrite reduction rates but also on the readily biodegradable substrate utilisation rates. If higher denitrification rates occur under non-anoxic conditions, the consumption of the substrate by the (heterotrophic)

Demtr ,mm·

0'"'"

d CNO, -N

=---·----

mgN] [ 1-h

In the case where nitrification occurs simultaneously with denitrification, the production of NOx species from the oxidation of ammonium has to be taken into account. In that case, the rate of denitrification can be calculated according to Eq. (8):

Table 1 Influent characteristics

average std. deviation(%)

TCOD

SCOD

TKN

(mg/I)

NH4-N (mg/I)

HPO,P

(mg/I)

TCOD/TKN (-)

371 14.1

112 5.4

33.1 4.1

6.48

39.2 4.1

9.4 13.2

6.6

5 ~ - - - -- - - - - -- - - - -- - - - - - - - - - ~

DO concentration (mg/I) Figure 1 Influence ofDO concentration on the rate of denitrification {data from v. Munch

et al., 7995) WATER MAY/JUNE 1996

d c NH, - N

d c NO, - N

dc,,.0, - N

rJJ,,..~ = - -d-1 - - --;;;-- - - d-, -

It has to be stressed that this denitrification rate will only be an approximation as it does not take into account the nitrogen consumed for cell synthesis nor the ammonium nitrogen produced from organically bound nitrogen. Estimates of the effect of both processes on the denitrification rate revealed that the rate of denitrification is likely to be under-estimated rather than over-estimated by neglecting both proc sses. However, in order to establish the exact rate of denitrification, a complete nitrogen balance including TKN and possibly nitrogen gas concentration measurements would have to be carried out. As an example, two sets of experimental data are used to obtain estimates for the parameter KAD" The first set of experimental data, shown in Figure 1, is taken from von Miinch et al (1995). Some details of the experiments are provided later in this paper. The value of KAD was found to be 0.46 mg/ I. The data shown in Figure 2 was taken from von Schulthess et al (1994). Those experiments were originally designed to determine the net production of the denitrification intermediates nitric oxide (NO) and nitrous oxide (N20). The biomass was grown in an 8 L gas-tight sequencing batch reactor at a cons'tant temperature of 20°C. The DO concentration in the reactor was varied between Oand 4 mg/ L and spikes of nitrite and nitrate were added at certain time intervals. Denitrification rates were determined from data points when at least 4 or 5 points were found to lie on a straight line. The significant variations in the denitrification rates (especially at zero DO) are probably due to the fact that denitrification kinetics are not the same for denitrification from nitrate and from nitrite. This complication is neglected when determining ~tD as no distinction is made between N0 3- and N0 2· in the model. The estimated KAD value found from these experiments was 0.21 mg/L. It is to be expected that the parameter KAD will vary for different systems depending on the extent of aerobic denitrification occurring (i.e. depending on physical characteristics such as microbial floe sizes or biological characteristics of the system). In either case, KAD would not be expected to change within short to medium-term time frames , such as one month or less. KAD therefore represents a direct measure of the extent of aerobic denitrification for a given system. (

Application of the Modified Model To SBR Systems The model has been used to describe the simultaneous nitrification and denitrification observed in sequencing batch 21

reactor (SBR) systems (von Mi.inch et al., 1995). The experiments were performed in two laboratory scale SBR systems of 12 L working volume in a temperature controlled room at 18-22°C. The SBR reactors were seeded with a grab sample of mixed liquor from the aerobic basin of the Brisbane City Council W acol Sewage Treatment Plant and operated for 139 days. The feed wastewater was also collected from the domestic wastewater treatment plant at W acol. A summary of influent characteristics is given in Table 1. The DO was measured on-line using oxygen probes and regulated by on-off control of the air flow. Each cycle was of 6 hours duration and was composed of the following periods: 20 minutes settling, 10 minutes decanting, 2.5 hours nonmixed/ non-aerated fill and 3 hours DO . controlled aerated react with sludge wastage during the last 10 minutes of the react period. The HRT was 18 hours, sludge age 25 days and average MLVSS concentration in the reactors was 1620 mg/ I. Influent samples were collected once or twice a week and effiuent samples every 2-3 days. When a quasi-steady state could be observed (i.e. repeated cyclic behaviour), cyclic studies were performed with sampling intervals of between 8 and 45 minutes. During the 139 days of operation, an elevated nitrite occurrence was observed in the effiuent of both reactors. The model was implemented in Nimbus, a software package developed by the CAPE Centre, The University of Queensland (Newell and Cameron, 1991) . Apart from the experimentally determined parameters µA ax' Ko A and KAD (von Mi.inch et al, 199:5), the 'default' set of parameters, as described in Henze et al. (1987 a), has been used. The modelling of the cycle of a sequencing batch reactor started at time equals zero with the commencement of the feed period. The reactor had a working volume of 8 L at the beginning of the cycle and was being filled up to 12 L by the end of the feed period. This volume was maintained during the react period until, after 2 hours and 50 minutes of react, a certain (small) amount of reactor volume was wasted (to maintain the SRT). A 20 minutes settling period followed the react period and a final 10 minutes of decant completed the cycle. After incorporating the modified rate equations into the model, the influence of the parameter for aerobic denitrification on the reactor performance becomes apparent (Figure 3). A higher value for KAD results in less inhibition of the heterotrophic denitrifiers by the presence of oxygen. Therefore, the activity of the denitrifiers during the aerated period rises with an increasing KAD value, resulting in more aerobic denitrification, i.e. more simultaneous nitrification and denitrification.

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

- - - -- ·--

<:::'.

'--

-~ u

t;-::::

·.:: ....

·a 11)

-0 4-<

~...

DO concentration (mg/I)

Figure 2 Influence of DO concentration on rate of denitrification (data from v. Schulthess et al., 1994) 12

-~-,

.- ... -·:, \

\ 10 \

~ 5

5 8

c::

·~

i:: <) c:: 0

2 0

cycle time (h)

Figure 3 Influence of model parameter KAD on NO, increase during aerated react period 16

5 C: 0

<.)

C: 0

<.)

0 3.0

3.5

4.0

4.5

5.0

5.5

(1 .0

cycle time (h) 1:,.

NH4-N in SBR I

o NO:--:-N in SBR l

Figure 4 Experimental data vs. model predictions for aerated react period (average DO

concentration was 1.2 mg/L) WATER MAY/JUNE 1996

In Figure 4 the model predictions for the aerated react period are shown for two different values of the parameter KA0 ; namely KAD equalling 0.2 mg/I (the model default value for K0 ) and 0.46 mg/I (the experimentally Âˇ~etermined value) . It can be seen that the correspondence between model calculations and experimental data is very good for KAD equals 0.46 mg/I, whereas a KAD value of 0.2 mg/I would have overestimated the production of NOx-N after the 3 hour react period by about 27 %. The NOx-N data points have been calculated by adding the measured concentrations of NO 2-N and NO 3-N.

Conclusions It was possible to model aerobic denitrification by introducing a simple modification to the IAWQ Model No 1. The new parameter KA can be, and has been, experimentally ifentified. The model may be used to predict more accurately the amount of NOx-N produced in systems that display aerobic denitrification.

Nomenclature cNH 4,N

Concentration of ammonium nitrogen (mg/L) cN 0 2_N Concentration of nitrite nitrogen (mg/ L) cNOJ-N Concentration of nitrate nitrogen (mg/L) KAD Switching function constant for aerobic denitrification (mg/L) KNO Nitrate half-saturation coefficient for heterotrophs (mg/L) K Oxygen half-saturation &~ ~ coefficient of autotrophs (mg/L K0 ,H Oxygen half-saturation coefficient for heterotrophs (mg/L) Kg Half-saturation coefficient for heterotrophs (mg/L) rDenitr. Rate of denitrification (mg/L/h) r Denitr max Maximum rate of denitrification ., (mg/L/h) SNO Nitrate and nitrite nitrogen concentration (mg/L) Dissolved oxygen concentration S0 (mg/ L) S5 Readily biodegradable substrate concentration (mg/L) XB,H Active heterotrophic biomass concentration (mg/L) rt Correction factor for anoxic growth of heterotrophs (-) pI Rate of aerobic growth of heterotrophs (mg/L/ d) Rate of anoxic growth of p2 heterotrophs (mg/Lid) ÂľA,max Maximum specific growth rate of autotrophs (d -1) ~ .max Maximum specific owth rate of heterotrophs (d - ) )

References Halling-Soerensen, B, and Hjuler, H (1992): Simultaneous nitrification and denitrification with an upflow fixed bed reactor applying clinoptilotile as media, Water Treatmen~ 7, p.77-88. H enze, M, Grady Jr, CPL, Guj er, W, Marais, G V R, and Matsuo, T (1987 a): Activated Sludge Model No. 1, IAWQScientific and Technical Report No. 1, IAWQ, London. Henze, M, Grady Jr, C PL, Guj er, W, Marais, G V R., and Matsuo, T (1987 b): A general model for single-sludge wastewater treatment systems, Water Research, 21, (5), p. 505-5 15. Ho, K {1994): Biological nutrient removal in activated sludge processes with low F/M, sludge bulking control, PhD-Thesis, The University of Queensland, Department of Chemical Engineering, Australia. Kokufuta, E, Shimohashi, M, and Nakamura, I. {1988): Simultaneously occurring nitrification and denitrification under oxygen gradi ent by polyelectrolyte complexcoimmobilised Nitrosomonas europaea and Paracoccus denitrificans cells, Biotech. Bioeng., 31, p. 382-384. Kugelman, I J , Spector, M, Harvilla, A, and Parees, D {1991): Aerobic denitrification in activated sludge. In: PA Krenke! {Ed.), Environmental Engineering Special Conference, American Society of Civil Engineers, p. 312-3 18. Masuda, S, Watanabe, Y, and Ishiguro, M (1991): Biofilm properties and simultaneous nitrification and denitrification in aerobic rotating biological contactors, Wat. Sci. Tech., 23, p. 1355- 1363. Moriyama, K, Sato, K, H arada, Y,

Washiyama, K, and Okamoto, K (1990): Simultaneous biological removal of nitrogen and phosphorus using oxic-anaerobicoxic process, Wat. Sci. Tech., 22, (7-8), pp. 61-66. Newell, RB, and Cameron, IT (199 1): NIMBUS Users Manual, The University of Queensland, Queensland, Australia. Patry, G G, and Chapman, D {1989) : Dynamic modelling and expert systems in wastewater engineering. Lewis Publishers, Inc. Robertson, LA {1994): Advanced courses on environmental biotechnology, Delft The University of Technology, Netherlands. von Munch, E, Lant, PA, and Keller,] {1995): Simultaneous nitrification and denitrification in sequencing batch reactors, Water Research, 30 (2) p 277-284. von Schulthess, R, Wild, D, and Gujer, W (1994): Nitric and nitrous oxides from denitrifying activated sludge at low oxygen concentrations, Wat. Sci. Tech., 30, {6), p. 123-132.

Authors Elisabeth von Munch is a Ph.D. student in the Department of Chemical Engineering at The University of Queensland. Dr Paul Lant and Dr Jiirg Keller are lecturers at the Department of Chemical Engineering, The University of Qyeensland. The authors are working in a wastewater treatment project within the CRC for Waste Management and Pollution Control Limited.

Quality Hitachi chain for the harshest wastewater environment LONG LIFE & RELIABLE

Quality

Endorsed

eoo-,,any

Acknowledgements This work was funded by the CRC for Waste Management and Pollution Control Limited, a centre established and under the Australian supported Government's Co-operative Research Centres Program. WATER MAY/ JUNE 1996

WATER

BIOLOGICAL IRON AND MANGANESE REMOVAL: AN UNTAPPED POTENTIAL I Cameron>:Âˇ Abstract Elevated levels of iron and manganese naturally occur in many of the groundwater and surface water supplies which are used for drinking water. About 400/o of water supply schemes in Queensland utilising groundwater experience problems with iron and ~~gai:iese on a regular basis. Water contammg iron and manganese can discolour water and stain plumbing and laundry items. The World Health Organisation (WHO) and the National Health and Medical Research Council (NH&MRC) have both stipulated maximum levels for both iron and manganese in drinking water. In many instances in rural Australia, groundwaters are only chlorinated before being reticulated to consumers. Iron and manganese in these groundwaters often exceed NH&MRC guideline values. Biological iron and manganese removal by a number of techniques, including sand filtration, is a proven technology in Europe which has not s~en much use in Australia to date. There 1s a great potential to improve drinking water quality in rural towns by adapting these simple technologies. A detailed literature search revealed that existing water treatment plants in France, Germany and Finland can provide design and operational information on a wide range of proven biological iron and manganese technologies. Experiments have been reported in Australia on removal by fluidised bed techniques. This paper provides sufficient technical information to allow pilot plant testing of biological iron and manganese removal technologies to be undertaken.

Introduction A problem for many water supplies with dissolved iron and manganese is that growth of bacterial slimes containing iron and manganese oxides in the reticulat10n system results in intermittent sloughin~ of brown or black precipitates. Adaptmg this biological mechanism for the removal of iron and manganese from the water before reticulation, would turn adversity into benefit and provide an elegant solution. Interest in this topic was sparked by the paper by Mouchet (1992), with practicality confirmed by subsequent literature WATER MAY/JUNE 1996

research from a number of European countries including France, Germany, Bulgaria and Finland. Many Queensland towns, and probably others nationwide, would benefit from the use of such biological water treatment techniques. Initially towns with a groundwater source with elevated levels of iron and manganese would be best suited to this technology. Loos (1987) documents problems in Queensland with manganese in drinking water supplies utilising groundwaters or surface waters as a raw water source. Historically, water treatment in Australia has followed the physical/ chemical methods of the United Kingdom and the USA, whereas Europe has chosen biological water treatment techniques. It is of interest to note that the first biological water treatment plant in the United Kingdom was only commissioned in 1992. (Bourgine et a~ 1994). The proximity of the United Kingdom to Europe has not resulted in a speedy transfer of the biological water treatment technology across the English Channel. Biological water treatment techniques have found widespread application in removing the following compounds: iron, manganese, nitrates, synthetic organic compounds (SOCs), ammonia, hydrogen sulfide. A report entitled 'Biological Processes in Drinking Water Treatment' prepared by the DPI (1995) (Queensland Department of Primary Industry, Water Resources) contains a comprehensive summary of available processes to remove the above compounds. Much of the literature reviewed focuses on biological removal of iron and manganese from groundwaters. Biological water treatment by sand filtration could also treat surface waters containing iron and manganese provided adequate clarification occurs upstream of the biological filters. (Filter runs would obviously be shortened for waters high in suspended solids). Direct filtration may be applicable for low turbidity raw waters.

The Problem The Bacteria. The bio-fouling problems associated with iron and manganese bacteria cause aesthetic water quality and hydraulic problems for both urban and

rural water users. The species of iron and manganese bacteria referenced in the literature are as detailed in Table 1. Ghiorse (1984) notes that 'Fe-and Mndepositing bacteria are ubiquitous. They have been detected in samples from almost every compartment of the biosphere where iron hydroxide and ferromanganese oxide deposits are found, .... ' (The paper gives detailed information on the biology of iron and manganese. depositing bacteria.) Not surprisingly, the same species of iron and manganese bacteria detailed in the above overseas papers have been reported in Australia, as listed in Table 2. Recommended Values. NHMRC/ ARMCANZ (1994) recommends maximum values of 0.3 mg/L and 0.1 mg/L for Fe and Mn respectively, based on aesthetic considerations. However, even at concentrations as low as 0.1 mg/L, iron settles out as a rust coloured silt causing bio-fouling that may result in taste, odour and colour problems. At levels above 0.02 mg/L manganese deposits slimes on pipes which may harbour potentially dangerous micro-organisms. The manganese may slough off the pipes as a black precipitate, causing taste, odour and colour problems (Water Resources Commission, Q!.d 1989, Sly et a~ 1989, Dixon et al,

1989).

Biological Technologies Available

Technologies.

DPI

(1995) documents a wide range of biological water treatment technologies in current use. Table 3 details other papers. The fluidised-bed manganese removal trials being undertaken by Sly et al have resulted in Australian and US patents, with the European patent pending. Successful pilot trials have been undertaken at the Molendindar water treatment plant, Gold Coast, with the assistance of the Urban Water Research Association and the Gold Coast Council. Future research will concentrate on removing manganese from filter backwash waters and sludge supernatant from existing water treatment plants, together with pilot trials for new treatment plants for small communities affected by manganese. â&#x20AC;˘ Maunsell Pty Ltd, 9 Sherwood Rd Toowong,

4066

Treatment Efficiencies. Table 4 shows the range of removal efficiencies of seven biological processes with respect to the removal of TOC, DOC, ammonia, iron, manganese and nitrate. Âˇ Biological iron and manganese removal efficiencies in Table 4 indicate that effective proven technologies are currently available. Raw Water Qualities. Biological water treatment has treated a wide range of raw water qualities successfully to remove iron and manganese, as detailed in Table 5. Treatment Plant Capacities. The literature clearly indicates that biological iron and manganese removal technology is not limited to small treatment plants, as illustrated in Table 6. Design Parameters. For biological processes it is important to create the right environmental conditions for the beneficial processes to occur. For iron and manganese removal, the optimum environmental conditions are well established and documented. The 'windows' which have been documented, relate to parameters of pH and redox

0.7 Fe (OH)3

0.6

0.5

Physlcal-chemlcal oxidation of Iron ~

potential (Eh) to create the ideal environmental conditions for iron and manganese removal. Minear & Keith (1982) provide an explanation of redox potential: 'The redox potential (Eh), a measure of the oxidising power of a system, is a variable of major importance in characterising systems containing elements that exhibit more than one oxidation state. Eh is related to the activity of electrons in the same manner as pH is related to the activ-

ity of protons (H+). Redox is usually measured electrometrically with an electrode pair consisting of an inert metal electrode coupled with a reference electrode .. and is commonly expressed in volts.' Figure 1 details the 'windows' for biological iron removal, and Figure 2 compares those for iron removal and manganese removal. For raw waters containing both iron and manganese, there may be a need to utilise a two step removal process, i.e. iron removal first followed by

Table 1 Iron Bacteria.

Gallionella ferruginea Leptothrix ochracea Toxothrix trichogenes Siderocapsa Crenothrix polyspora Sphaerotilus natans Clonothri.x fa.sea

Czekalla et al {1985), Mouchet {1992) do do Bourgine et al {1994), Mouchet (1992) do Mouchet (1992) Mouchet (1992)

Manganese Bacteria Leptothri.x lopholea Metallogenium Hyphomicrobium Siderocapsa Siderocystis Leptothri.x discophora Arthrobacter Ochrobium Pseudomonas manganoxidans

Czekalla et al (1985) Mouchet {1992) do do do do Bourgine et al (1994) do Hatva (1988) Mouchet (1992)

Table 2 Iron Bacteria in Australia

Gallionella

WRC (1990), Vishwa.nathan & Boettcher (1991), Carruthers pers comm (1995) Viswanathan and Boettcher (1991) Carruthers pers comm. (1995)

0.4

1 w 0.3

Competition

between physlcal-

0.2

chemlcal and blologlcat oxidation

0.1

Crenothri.x Sphaerotilus Leptothrix spira

Manganese Bacteria. in Australia Hyphomicrobium Loos (1987) Pedomicrobium manganicum ACM 3067 Sly et al (1988) Table 3 Available technologies

-0.1

Stability of ferrous Iron

Figure 1 Field of activity of iron bacteria (Source: Mouchet 7992 )

Method In-situ Treatment

Examples

Ground Passage Re-infiltration Overland Runoff

Slow Sand Filtration Rapid Sand Filtration

Biologically Active GAC Submerged Filtration Unsubmerged Filtration Fluidised Bed Fluidised Bed

Pilot Trials Pilot Trials

References Seppanen (1992) do do Seppane~ (1992) Hatva (1988)

Mouchet (1992) Bourgine et al (1992) Peitchev et al (1988) DPI, Water Resources (1995) Hatva {1988) Hatva (1988) Sly et al (1993) Viswanathan & Boettcher (1991)

Table 4 Range of removal efficiencies (%) * In-Situ Process pH

Figure 2. Comparison of the requirements ofFe and Mn bacteria (7-field of bacterial Fe oxidation; 2-field of bacterial Mn oxidation) (Source: Mouchet, 7992) 26

TOC DOC Ammonia Iron Manganese Nitrate

40-70 40-75 80-100 90-100 65-100 70-75

Rapid Sand Filter

5-80 50-100 50- 100 0-100 -

Slow Sand Filter 40 7-70 65-95

50-95 70-95 5-60

BAC Filter

Biological Filter

Fluidised Bed

20-30 10-75 70-95

0-40

5- 10

(

30- 100 40-100 25-100 50-100

20-100 40-100 60-100

â&#x20AC;˘ abstracted from the literature review, DP/, Water Resources (7 995)

WATER MAY/JUNE 1996

manganese removal.

manganese removal than for iron removal filters, as illustrated in Table 9. Note that the colonisation of media and consequent growth of bacterial population depends on temperature and availability of nutrients. With some waters, sufficient nutrients may not be available to encourage bacterial growth and nutrients may need to be added.

Rapid Sand Filtration. Because of

the widespread use and acceptance of rapid sand filters for municipal water treatment in Australia, it is considered that this method offers the greatest potential for conversion to a biological process. For the adaptation ofrapid sand filters for iron and manganese removal, the following design parameters have been gleaned from the overseas literature.

Contrasts

Ripening Periods for Filters.

The following contrasts between biological water treatment and conventional water treatment have been identified: • do not pre-chlorinate prior to biological filter

Due to the biological processes involved, there is a ripening period before filters are operating at their optimum removal efficiency. The ripening period is longer for

Table 5 Q,uality of raw waters treated Fe Mn pH Temp (OC) mg/L mg/L 0.5-0.6 2.5-4.0 6.7-6.8 11 0-0.2 0.5-3.0 7.1-7.5 8-23 0. 75-1.1 6.2-6.5 30-3 1 ~0.03

Plant Saints Hill, UK Unknown Lome, Togo Salo, Finland Hitura, Finland Hitura, Finland 11 Plants, Finland Pilot Plant

12-23 2.46 4.6 (mean) 0.24-10.1 2.6-3.0

0.28-0.67 0.35 0.04 (mean) 0.12-0. 76 0.01

NA NA NA NA 5.2-5.5

NA NA NA NA 17

Hamburg-Baursberg Hamburg · Neugraben Hamburg-Gross Handorf Braunschweig-Bienrode

0.69 1.22 2.4 3.5

0.13 0.13 0.16 0.9

7-7.88 7.6 7.34 6.5

NA NA NA NA

Reference

Bourgine et al (1994) Peitchev, Semov (1988) Mouchet (1992) Seppanen (1992) do do Hatva (1988) Viswanathan & Boettcher (1991) Czekalla et al (1985) do do do

Table 6 Capacity of biological treatment plants Plant

Saints Hill, UK (Fe & Mn) Lome, Togo (Fe) Salo, Finland (Fe) Manonvillier, France (Fe) Varangeville, France (Fe) (Not Detailed) Hochfelden, France (Fe & Mn) Sorgues, France (Mn)

Capacity ML/d 6.5 44

Reference

Bourgine et al (1994) Mouchet (1992) Seppanen (1992) Bourgine et al (1994) Bourgine et al (1994) Mouchet (1992) Mouchet (1992) Mouchet (1992)

1.4 8.4 0.4-44 12 18

r------------------------------1 I I I I

I I I I

~--~

II I

L• '

r-~'-----"'I ~---~ >------<

&-.

Raw water

1-- - - - -

~---- i

II__

II I

_ . ., _- - ' " _ ~

Treated water

I I

TI I I I I I I

10 _ _ _ _ _ _ _ _ _ _ _ _ II

• do not use chlorinated backwash water • separate backwash tank required for filtered water (not chlorinated} • ripening period (as detailed} • need for Redox metering • importance of maintaining pH · Redox 'windows' • reduced chemical costs • reduced costs to treat water as detailed below • coarser sand effective size (E.S.} than conventional rapid sand filters. Figure 3 details a schematic drawing of a pressurised biological iron removal plant. (Source: Mouc.het, 1992}

Advantages The paper of Bourgine et al (1994} offers the following comparison between the Saints Hill biological treatment plant and the nearby Groombridge conventional physical/chemical treatment plant drawing raw water from the same aquifer. The following cost reductions on a cost per ML basis have been calculated for biological treatment: • 15% reduction electricity costs • 93% reduction manpower costs • 96% reduction chemical costs 750/o reduction other costs.

Pilot Plant Studies Pilot plant studies are recommended by a number of authorities in order that plant design and operational parameters are known before a full scale plant is constructed. The following authors detail pilot plant studies: Peitchev et al (1988), Viswanathan & Boettcher (1991 }, Mouchet (1992), Goldgrabe et al (1993}, Sly et al (1993}, Malley Jr et al (1993) , Bourgine et al (1994). It is recommended that pilot studies firstly concentrate on biological iron removal.

Need for a Champion Project As with many new technologies, there is a natural aversion to taking risks with the 'unknown'. It is hoped that further pilot plant testing in Queensland, both in sand filters and in fluidised beds, will help to reduce the risk and increase the confidence in the technology. Following successful pilot plant test· ing, it is hoped that a local government with an existing iron and or manganese problem will be willing to construct Queensland's first biological water treatment plant.

Conclusions 1- Raw water aeration system 2- Alr ln)ector 3-Reclrc ulatlng treated water

4-Reactor 5-Aeratlon system tor filter effluent 6-Nonch lorlnated washwater storage tank 7- Storage tan k tor chlorinated water

&-Chlorine Injection

9-Rawwater 10-Treated water 11- Atr scour

This paper has provided enough information for biological iron and manganese removal from drinking water to be considered feasible. The te\:hnology has a future in Australia to complement the existing technologies.

Acknowledgements Figure 3 Process flow diagram for biological iron removal in a pressuri<-ed pl,ant with

alternative aeration and backwashing designs WATER MAY/JUNE 1996

I acknowledge the support and encouragement offered by Mr H Gibson 27

and Mr P Sherman, officers of the DPI, Rural & Resource Development. The opinions expressed in this paper are those of the author and not necessarily those of the Department of Primary Industries.

References Bourgine F P, Gennery M, Chapman] I, Kerai H, Green] G, Rap RJ, Ellis S, Gaumard C (1994) 'Biological processes at Saints Hill water-treatment plan~ Kent' JIWEM, 8, August pp 379-392 Carruthers R, (1995) Personal Commun-

ication, DPI, Water Resources Czekalla C, Mevius W, Hanert H (1985) Quantitative removal of iron and manganese by microorganisms in rapid sand filters (in-situ investigations). Water Supply 3, Berlin 'B', pp 111-123. Dixon D R, Sly L I, Waite T D, Chiswell B, Batley G E (1989) Manganese removal: A model of cooperative research. Water 15 , 6, pp 32-34. DPI, Water Resources (1995) Scientific Brief, 'Biological Processes in Drinking Water Treatment'. BRF 3/1995, Brisbane Ghiorse WC (1984) Biology of iron and man-

Table 7 Parameters for iron removal Parameter

Example

Sand Type

N.A.

Sand Size eff. size, mm (DIO)

2mm 1.35mm

Mouchet (1992) Mouchet (1992

Loading Rate m/ h

21-34 24-40 2-12

Filter Depth Backwashing

1.4m 36 h cycle or 4 m headloss 48 h cycle 8.5 min include. 1.5 min air, 4 min rinsing 0.2% product water 3-5min include. 20 sec air 40-60 m/h 0.02-0.40/o product water

Bourgine et al (1994) Mouchet (1992) Czekalla et al (1985) Mouchet 1992 Bourgine et al (1994) Mouchet (1992) Mouchet (1992)

Reference

Mouchet (1992) Hasselbarth & Ludemann (1973)

Redox (Eh)

see Figure 1*

Mouchet (1992)

pH Oxygen

6.3-7.8

Bourgine et al (1994)

Pre-treatment

Aeration

N.A. Mouchet (1992)

â&#x20AC;˘ Mouchet comments that 'the upper limits of Eh and pH are less precise and are only critical when pH exceeds about 7.2'

Table 8 Parameters for manganese removal Parameter

Example

Reference

Sand Type

Manganese black sand 900/o Sand: 100/o Catalytic mix Manganese coated sand

Peitchev et al (1988) Bourgine et al (1994) Mouchet (1992)

Sand Size eff. size, mm (DIO)

0.95 1.35

Mouchet (1992) do

Loading Rate m/h

7-9 16-30 5-50 10-40 3.2-13

Peitchev et al (1988) Bourgine et al (1994) Hasselbarth & Ludemann (1973) Mouchet (1992) Czekalla et al (1985)

Filter Depth Backwashing

1.54m With purified non-chlorinated water Clean washwater, 48 h cycle or 4 m headloss

Hasselbarth & Ludemann (1973) Peitchev et al (1988)

Pre-Treatment

Aeration

Peitchev et al (1988)

Redox (Eh)

> 400 mV >200 mV 120-155 mV

Mouchet (1992) Bourgine et al (1994) Peitchev et al (1988)

5.5-8.0 7.1-7.5 4-8 mg/I

Bourgine et al (1994) Bourgine et al (1994) Bourgine et al (1994)

pH Oxygen

Bourgine et al (1994)

Table 9 Ripening periods

Iron

Manganese

2 Weeks 3 months 15 Days

3 months

Bourgine et al (1994) Mouchet (1992) Viswanathan & Boettcher (1991)

ganese-depositing bacteria. Ann. Rev. Microbiol 38, pp 515-550. Goldgrabe J C, Summers R S, Miltner R J (1993) Particle removal and head loss development in biological filters. ]A WWA 85, 12 pp 95-106. Hasselbarth U, Ludemann D (1973) Removal of iron and manganese from groundwater by microorganisms. Water Treatment and Examination 22 (1) pp 62-77. Hatva T (1988) Treatment of groundwater with slow sand filtration. Water Science and Technology 20, No 3, pp 141-147. Loos E T (1987) Experience with manganese in Queensland water supplies. Water 14, 1,pp28-31,37. Âˇ "' Malley J P Jnr , Eighmy T T, Collins M R, Royce J A, Morgan D F (1993) The performance and microbiology of ozoneenhanced biological filtration.JA WWA 85, 12 pp 47-57. Minear R A, Keith L H (1982) 'Water Analysis, Volume 1, Inorganic Species, Part 1'. Academic Press. New York. Mouchet P (1992) From conventional to biological removal of iron and manganese in France -JAWWA, 84, 4, pp 158-167. NHMRC/ ARMCANZ (1994) 'Draft Guidelines for Drinking Water Quality in Government Australia'. Australian Publishing Service. Peitchev T, Semov V (1988) Biotechnology for manganese removal from groundwaters. Water Science and Technology 20, 3, pp 173178. Seppanen HT (1992) - Experiences of biological iron and manganese removal in Finland.JIWEM 6, 3, pp 333-341. Sly L I, Arunpairojana V, Hodgkinson M C, (1988) Pedomicrobium manganicum from drinking water distribution systems with manganese-related 'dirty water' problems. Syst. Appl. Microbial, 11, pp 75-84 Sly L I, Hodgkinson M C, Arunpairojana V (1989) Proc AWWA 13th Federal Convention. pp. 148-151. Sly L I, Arunpairojana V, Dixon D R (1993) Biological removal of manganese from water by immobilised manganese-oxidising bacteria. Water 20, 3. pp 38-40. Viswanathan M N, Boettcher B (1991) Biological remeval of iron from groundwater.]. Wat. Sci Tech 23 . pp 1437-1446. Water Resources Commission, (Q!d) (1989) 'Guidelines for Planning and Design of Urban Water Supply Schemes'. Brisbane Water Resources Commission, (Q!d) (1990). 'Information Bulletin - Iron Bacteria in Water Bores', Brisbane. World Health Organisation, (1984) 'Guidelines for Drinking Water Quality, Volume 1, Recommendations'.

Author Ian Cameron is currently Senior Water and Wastewater Engineer in Maunsell's Brisbane office. JiVhen writing this paper, he was Local Authority Services .Engineer, QJJPJ, Gympie. He has had 73 years of civil engineering experience in Q,ueensland, including consulting, local government and state government. His interests include appropriate technolof!:j for water and sewage treatment, particularly for small rural communities. WATER MAY/JUNE 1996

WATER

TECHNICAL NOTE

GRANULAR ACTIVATED CARBON PILOT PLANT STUDIES G Newcombe, A Collett, M Drikas, B Roberts* Abstract Consumer complaints provoked by musty/earthy odours of 2-methylisoborneol (MIB) and geosmin and concerns about levels of trihalomethanes (THMs) in finished water prompted the Engineering and Water Supply Department to initiate granular activated carbon (GAC) pilot plant trials at the Anstey Hill Water Filtration Plant. Three

coal-based activated carbon filters were established, each with a different empty bed contact time. A range of parameters, including dissolved organic carbon and THMs, were monitored. Inlet water was spiked with MIB and geosrnin 10 months and 18 months after the trial began. Results indicate that the GAC in the filters would need to be replaced or regenerated often to maintain an acceptable

D-prc-filtcr -6 5 minute EBCT A-11 minute EBCf T - 211111i1111tc l'l!C I'

0-+--~---.--..---"T"""-~- -,---,---..---,--~---.---, 400 500 200 300 600 0 100 Days Figure 1 DOC concentration vs days

300 -D-pre-filter -e-6.5 minute EBCT -A-13 minute EBCT -'Y-20 minute EBCT

250 ,-...

::::_ 200 :I.

.!:! ~ 150 C:

"'C: u0 100 ()

::::E :i:: E--

â&#x20AC;˘

0 200 100 0 Figure 2 THM concentration vs days WATER MAY/JUNE 1996

300 Days

400

500

Keywords Tastes and odours; 2-methylisoborneol; geosmin; activated carbon; pilot plant trials.

Introduction The Anstey Hill Water Filtration Plant in Adelaide provides water for approximately 20 percent of the population of the city. Generally it receives its raw water from a pipeline directly from the River Murray. The River Murray, and other rivers feeding the system, are plagued by blooms of cyanobacteria which occasionally result in unpleasant tastes and odours in the finished water. Consumer complaints provoked by musty/earthy odours of 2-methylisoborneol and geosmin and concerns about levels of trihalomethanes (THMs) in finished water prompted the Engineering and Water Supply Department of South Australia to initiate granular activated carbon (GAC) pilot plant trials at the Anstey Hill Water Filtration Plant. Three coal-based activated carbon filters were established, with empty bed contact times (EBCT) of 6.5 minutes, 13 minutes and 20 minutes. The shorter EBCT was investigated as it simulated the approximate contact time if the sand in the conventional filters were replaced with activated carbon - the most attractive option. A range of water quality parameters was monitored over a total test period of more than 2 years.

Results and Discussion

bO C:

removal capacity for the compounds of interest under these::.conditions.

600

Dissolved Organic Carbon. Inlet dissolved organic carbon (DOC) levels averaged around 6 mglÂˇ1 over most of the trial. As expected, the effectiveness of the filter was dependent on the contact time; after less than a month the 6.5 min. EBCT column had reached a plateau for DOC removal, the plateau represented a very low percentage removal. The other two columns took longer to reach their plateaux, however, none ' of the filters showed very efficient removal of DOC (Fig. 1). Trihalomethanes. There are a number of consumer off takes from the *SA Water, Private Mail Bag, Salisbury 5108

• 25 -D-pre-filter -e-ti.5 minute EBCT - • -13 minute EBCT -•-20 minute EBCT

620 C

.g E

c 8 15 C

'~°

0 -+--..----.---,--..-----.--r--..----.---r--..----,,----,---,---,,----.----, 0 2 4 6 8 10 12 16 14

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Figure 3 Comparison of new, used and regenerated carbon for the removal ofMIB, 6.5

minute EBCT (70 months after trial began)

-•-pre-filter (6.5 min contact time) -D-post-filter (6.5 min contact time) --e-pre-filter (13 min contact time) --0-post-filter (13 min contact time)

35 ,...._ 30

Oil 5 _gC 25

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--------·

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"§

• ------------<•-----------·

.,"'0 0

•

0-+---..-----.----,---...-----.----,---...------.---.2.0 0.5 1.0 1.5 0.0 Days

Figure 4 Geosmin removal by filters 7 and 2 (70 months after trial began) 50

•

-•-pre-filter -•-used carbon -•-regenerated carbon -•-new carbon

40 Days

Figure 5 MJB removal by filters 7, 2 and 3 (7 8 months after trial began)

pipeline before it reaches Adelaide. The water must therefore be chlorinated, leading to relatively high trihalomethane (THM) concentrations. The results are shown in Fig. 2. The 6.5 min. EBCT filter shows the classic behaviour of THM adsorption - decrease in inlet concentration leads to desorption (after around 30 days). By halfway through the trial all filters were desorbing THMs although there was a relatively constant inlet concentration. After around 6 months of the trial the column with the highest EBCT was producing the worst quality water, and continued to do o! Tastes and Odours. Unfortunately (fortunately for consumers) there were no serious taste and odour episodes during the extent of the trial. In order to establish the effectiveness of the filters for the removal of tastes and odours the inlet water was spiked with 2-methylisoborneol {MIB) and geosrnin at different stages during the investigation. After 10 months run time, ie. after all filters had reached their plateau values of DOC removal, two carbon samples were removed from filter 1 {6.5 minute EBCT). One sample was regenerated using a chemical method investigated at the Australian Centre for Water Quality Research. Three glass columns were set up, one containing new carbon, one containing used carbon, and the other containing regenerated carbon. Water spiked with MIB was pumped through the columns and the outlet concentration was monitored {Fig. 3). The used carbon still removed a significant percentage of the spiked 2-methylisoborneol {approximately 75%), however, the remaining concentration (4-10 ngl ·1) was still high enough to be detectable, and possibly unpleasant, to a large proportion of the population. Both the new and regenerated carbons reduced the MIB concentrations to acceptable levels over the duration of the column trial. Shortly after this trial the inlet water to pilot plant filters 1 and 2 {EBCT 6.5 and 13 minutes) was spiked with geosmin (Fig. 4). At the inlet concentrations tested, the product water from filter 1 would probably not be acceptable to at least a significant proportion of consumers, and the water from column 2 was very close to the borderline acceptable concentration. The percentage removal of geosmin was 33% and 75% respectively for filters 1 and 2. The difference between MIB (75% removal) and geosmin {33% removal) for the 6.5 minute contact time is unexpected, as geosmin is more effectively removed by activated carbon than MIB. This discrepancy could be attributed to the difficulties involved ' in comparing pilot plant trials with column tests. After the filters had been running for 18 months low levels (3-5 ngl ·1) of natural MIB were present in the inlet water. The outlet concentration was monitored WATER MAY/JUNE 1996

WATER -0-pre-filter - •-6.5 minute EBCT - • - 13rninutcEBCT

20,....._

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'-' C

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---·

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•

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•

- - - - - - -0

•

...

~...

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Days Figure 6 Removal ofgeosmin by filters 7, 2 and 3 (7 8 months after trial began)

and the results are shown in Fig. 5. Over the period of the taste and odour trial no filter removed natural MIB to a significant extent. A spike of 27 ngl ·1 produced better removals for filters 2 and 3, however water from all three filters would not be considered acceptable by consumers. Over the same period geosmin spiked into the inlet water at an average concentration of 17 ngl ·1 was removed to an acceptable level only by filter 3 (20 minute EBCT}; filter 2 would again produce water on the borderline of acceptability (Fig. 6}.

Conclusions Granular activated carbon filters are not a viable option for the control of DOC or THMs at the Anstey Hill Water Filtration Plant. GAC installed for the purpose of removing 2-methylisoborneol and geosmin from treated River Murray water would only be effective for a period of 010 months for empty bed contact times of 6.5 or 13 minutes. Therefore the replacement of sand with GAC in the conventional filters at Anstey Hill Water Filtration Plant will not be considered as a water treatment option. The life of GAC filters with the highest empty bed contact time of 20 minutes is less than 18 months for 2-methylisoborneol removal, however for geosmin removal the life of the filter would be longer than 18 months. A method of chemical regeneration currently under investigation at the Australian Centre for Water Quality Research shows promise for the extension of the life of activated carbon filters.

Authors Gayle Newcombe is a Research Officer at the Australian Water Qyality Centre investiWATER MAY/ JUNE 1996

gating adsorption onto activated carbon. Mary Drikas is Senior Chemist, Water Treatment Unit, A WQ,C. Bruce Roberts is Supervising Engineer, Water Treatment, in the Engineering Services Group of SA Water. At the time the paper was written, Alan Collett was Water Treatment Plant Engineer with SA Water.

The Bunbury Water Board in WA recently completed the Spencer Water Treatment Plant. The 1995 upgrade of the plant is the culmination of the site's development as a source of drinking water for Bunbury. The plant has developed from simply pumping water from bores directly into the mains system, through to the pressure filtration system, chlorination and now the advanced Dynasand filtration system. The object of the upgrade was to increase the output of the filtration system to match the output of the bores with variable speed control of the delivery pumps into the delivery main, reticulation system and remote storages. This has the bonus of reducing energy costs. It has also eliminated the previous losses from backwashing the pressure water filters and discharging wash water via the town drainage system. The major feature of the upgrade is the Dynasand filters. Iron and manganese (at concentrations greater than can be economically removed by normal filters} are effectively removed in the new plant with minimal operator involvement. Project Manager Heath Bennett thanked contractors RCR Engineering and designer Rein Loo for their efforts during the project.

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WATER

STOCKHOLM WATER PRIZE TO IMBERGER West Australian Coup The prestigious Stockholm Water Prize has been awarded to an Australian, Dr Jorg Imberger, Director of the Centre for Water Research in Perth. He was nominated by AWWA, having won the Association's own Peter Hughes Water Award in 1995. Dr Imberger is also the Professor of Environmental Engineering at the University of Western Australia and has excellent teaching credentials in addition to his stature in the field of research.

of endorsement from eminent practitioners around the world. It was impressive to see the calibre of support which was generated and there seems little doubt that this overwhelming evidence of his recognition among peers played a major role in his success with this award. Places where he has made significant contributions include the Venice Lagoon and Lake Biwa in Japan. Previous acknowledgement came Dr Imberger's way in the form of the Onassis

The Prize The Stockholm Water Prize is an elegant Swedish crystal prism trophy, topped by a crystal castle and accompanied by a cash award of US$150,000 and was established in 1990. Âˇ His Majesty, King Carl XVI Gustaf, of Sweden, will hand the prize to Dr Imberger on 8 August at a ceremony during the Stockholm Water Festival. Dr Imberger will join an illustrious list of laureates (see box) and is the first person from the Southern Hemisphere to achieve this honour. The winner was selected by a panel of judges: five drawn from the National Committee for Water Research of the Royal Swedish Academy of Sciences and one each from the International Water Supply Association and the International Association on Water Quality. The news was announced on World Water Day, 22 March.

Dr lmberger's Work Jorg Imberger is pre-eminent in his field of environmental fluid dynamics and has been credited with establishing the new field of Physical Limnology. Part of the protocol by which AWWA nominated Dr Imberger, was providing letters

Dr Jorg Jmberger, recipient of the 1996 Stockholm Water Pri<,& Environment award in 1995, followed by his appointment to a High Level Advisory Board which is consulted by UN Secretary General, Dr Boutros Boutros-Ghali. Dr Imberger was responsible for initiating the first environmental engineering course in Australia and also founded the Department of Environmental Engineering at the University of Western Australia. It is uncommon to find eminent researchers who are equally committed to improving outcomes for students, so Dr Imberger's achievements are all the more noteworthy.

Previous Winners Dr David Schindler, Canada - 1991 Dr Poul Harremoes and his team at the Technical University ofDenmark - 1992 Dr Madhav Chitale, India - 1993 Dr Kubo,Japan - 1994 Water Aid, UK - 7995 DrJorg lmberger, Perth, Australia - 1996

Stockholm Water Festival The Stockholm Water Prize ceremony in August will be a part of the Stockholm Water Festival, a huge affair in which a million Swedes and many international visitors spend a week celebrating summer and water, along the beautiful bridges and waterways of Stockholm. There is always a strong focus on children's activities and their understanding of water issues. Apart from active water sports of many kinds, the festival includes restaurants, stalls, theatre, music and general enjoyment of water and the long summer evenings. Stockholm, a beautiful, ancient city situated on 14 islands, is an environmental success story. Water quality there has improved dramatically in the last few decades, to the point where salmon fishers perch on the city's bridges and kayaking and swimming in the waterways is routine. Much of the credit for this turnaround can be laid at the door of the King of Sweden, HM Carl XVI Gustaf, who is a strong advocate for the environment, and Stockholm Water, the corporatised agency which manages water for the City.

Stockholm Water Symposium The Stockholm Water Symposium takes place at the same time. It is gradually acquiring a reputation as a forum for canvassing the major equity issues which face the water environment around the world. The number of delegates is climbing and a broader cross section is attending. Australia's Professor Peter Cullen has been a long-time supporter of the event and has presented papers. Sydney Water's Paul Broad attended in 1995 and several other Australians have made the trip, including AWW A's Executive Director, Chris Davis.

Interested?

Dr Jmberger in action

Anyone interested in attending the 1996 Stockholm Water Symposium, from 4 to 9 August, should contact AWWA's Federal Office for details, tel (02) 413-1288, fax (02) 413-1047. WATER MAY/JUNE 1996

TECHNICAL NOTE

WATER

REMOVAL OF ALGAL TOXINS USING MEMBRANE TECHNOLOGY M Muntisov \ P Trimboli * Note: This Technical Note is repeated due to typographical errors in the March issue

Abstract The results from pilot testing of membrane technology for the removal of algal toxins from River Murray water are presented. The results show that nanofiltra. tion is capable of removing two common algal toxins.

Introduction The development of treatment methods for the removal of algal toxins from drinking water has been a priority in the · Australian water industry ever since the well-publicised toxic algal bloom occurred . in the Darling River in 1991. Most research has focussed on the use of activated carbons or ozone for treatment. The known molecular structure of the algal toxins Microcystin-LR and N odularin indicate that nanofiltration membrane technology is theoretically capable of removing these toxins from water. A pilot test program was undertaken to determine the effectiveness of nanofiltration membrane technology in removing algal toxins.

pressure of 60 kPa. Nanofiltration was operated with a high recycle rate (7.6 times the inflow), a membrane recovery of 7.7% and an overall recovery of 670/o. Runs were performed both with and without alum dosing. The pilot plant drew water directly from the river at Murray Bridge in South Australia. To test for algal toxin and taste and odour compound removal, microfiltered raw water was spiked with the toxins Microcystin-LR, Nodularin and the algal taste and odour compounds Geosmin and 2-Methylisobomeol (MIB).

Results A summary of the treatment results achieved is presented in Table 1. The results indicate the following: • the raw water has high turbidity, colour and iron levels and has a very high organic content as measured by TOC and THM formation potential (THMFP) • microfiltration without coagulant addition is effective in removing turbidity, iron and manganese but is poor in removing colour, TOC and THMFP • microfiltration with coagulant provides improved colour, TOC and THMFP removal • nanofiltration following microfiltration (without coagulation) achieves excellent colour removal and, more significantly, a very dramatic reduction in TOC and THMFP levels compared to coagulation. The nanofiltration treatment performance in this trial indicates its potential

Pilot Testing The pilot plant was a MEMCOR microfiltration trial unit, followed by a spiral wound nanofiltration unit (Hydranautics PVD 1 membrane). Microfiltration was operated at a normal flux of 120L/m2.hr and a transmembrane Table 1 Treatment ofRiver Murray water Parameter

Turbidity (NTU) Aluminium (mg/L) Iron (mg/L) Manganese (mg/L) Colour (HU) pH (TOC) (mg/ L) (THMFP) (µg/L)

Raw

61 5.0 3.3 0.04 65 6.8 9.6 718

Microfiltered

Nanofiltered (no Coagulant)

No Coagulant

With alum (28 mg/L)

0.09 0.08 0.09 0.01 53 7 8.2 588

0.06 0.03 0.02 0.01 7 6.5 4.2 164

Mycrocystin-LR (µg/L) N odularin (µg/L) Geosmin (ng/L) MIB (ng/L) • detection limit 0.5 µg/L

Algal Toxin Removal Microfiltered River Murray water was spiked with two algal toxins and two algal taste and odour compounds prior to treatment by nanofiltration. The results are shown in Table 2. The key conclusions which can be drawn from these results include: • nanofiltration is capable of removing the algal toxins Microcystin-LR and Nodularin to below detection levels. The detection level for Microcystin-LR is below the range of values being considered as a guideline value Gones et al, 1993) • nanofiltration provided around 500/o removal of the common algal taste and odour compounds geosmin and MIB. The removal rate cmtld be improved by more optimal operating settings on the nanofiltration system. Even so, it is unlikely that nanofiltration will be satisfactory in the removal of geosmin and MIB given that the taste and odour thresholds of these compounds is in the 5 to 10 ng/L range. Therefore, supplementary treatment in addition to nanofiltration would be required for effective algal taste and odour control. The use of powdered activated carbon is an option.

Conclusion The main conclusion from the microfiltration/nanofiltration pilot testing program is that two common algal toxins can be removed from River Murray water by nanofiltration membrane technology.

Acknowledgements 0.06 0.03 0.01 0.01 3

The authors wish to acknowledge the work of Brett Alexander of Memtec Ltd in carrying out the site trial work and the Australian Water Quality Centre in Adelaide which conducted the analyses.

7.1

References

0.5 36

Jones G, Burch M, Falconer I, Craig, K (1993). Cyanobacterial Toxicity, pp 17-32 . Technical Advisory Group Report. Murray Darling Basin Commission. Algal Management Strategy. MDBC, Canberra. Muntisov M (1995). Future Technology for Drinking Water Treatment, AWW A Queensland Regional Conference, Gold C'oast, October 1995.

Table 2 Removal of algal toxins, tastes and odours Parameter

for effective no-chemical treatment. It also has the potentia to produce a biologically stable water which could minimise or even eliminate the need for residual disinfection (Muntisov, 1995).

Spiked ·Microfiltered

Nanofiltered

8.4 8.0 52 38

below detection• below detection• 22 21

• Gutteridge Haskins & Davey, 380 Lonsdale Street, Melbourne, 3000 • Memtec Ltd, Bag 1, Windsor 2756

WATER MAY/JUNE 1996

ENVIRONMENT

MEASURING THE HEALTH OF OUR RIVERS NJ Schofield*, PE Davies*

Abstract The state of river ecological health is a key issue in land and water management. Measurement of physico-chemical parameters alone does not allow an assessment of the biological condition of surface waters. Assessing the health of Australia's rivers requires a nationally consistent, scientifically valid methodology based on standardised comparative sampling of biological communities and/or processes. The application of the river invertebrate prediction and classification scheme (RIVPACS) to Australian conditions, funded under the National River Health Program (NRHP), is a major attempt to develop such an approach. It is based on the concept of comparison of macroinvertebrate community composition between a site and a set of regionally relevant 'least disturbed' reference sites. This is the first time a tool has been developed for monitoring the ecological health of rivers at a local, regional or national scale. Other similar tools are being developed in the NRHP using community data for fish, algae, and macrophytes, as well as for key ecological processes. These tools are specifically aimed at providing managers with information on the effects of land and water management on river ecological condition. The NRHP is set to deliver the capability to perform the first national assessment of river health by mid-1997, though the future of the program depends on Commonwealth funding for four years beyond 1996.

Keywords River health, bioassessment, monitoring, RIVPACS, ecology, macroinvertebrates, water quality, fish, diatoms, phytoplankton

Peacock Creek NSW country's most vital resource: water. The massive outbreak of blue-green algae on the Darling River in 1991 focussed the community's attention on the widespread degradation of our rivers. These concerns have been exacerbated by reports of fish kills, declining native fish populations, toxic algae, infestation by exotic species, restricted recreational access and declining drinking water quality. Underpinning these concerns is the frustration associated with the absence of a clear, accurate picture of the condition of our rivers. The community wants to know: Just how many pristine rivers remain? What is the health of rivers in our developed landscape? (and most importantly) What can be done to protect and restore Australia's remarkable river ecology? These questions can only be answered with a nationally consistent, scientifically based river health assessment methodology.

Introduction In 1993 the Commonwealth launched an ambitious program to develop scientifically based tools to assess and monitor the health of the nation's rivers. This was in response to growing community concern about the ecological condition of the WATER MAY/ JUNE 1996

What is River Health? The term 'river health' is a useful and widely understood concept However, it is difficult to describe in precise scientific terms. In this paper, river health is taken to mean the degree of similarity to an

unimpacted river of the same type, particularly in terms of its biological diversi ty and ecological functioning. This rather simplistic definition says little of the attributes or behaviour that we might expect of a healthy river but has the advantage of a verifiable, regionally relevant scale against which to measure health. In fact, this is analogous to a general assessment of human health. In Australia, relatively few rivers remain in an unimpacted or pristine state. Most rivers are affected by a number of instream, riparian and catchment modifications or practices. This often results in them being less biologically functional and of lower ecological value than their original states. Important river stresses include nutrient enrichment, increasing salinity, pesticides, sediment loading, water extraction, flow controls, loss of riparian vegetation and effluent discharge.

*Land and Water Resources R&D Corporation, GPO Box 2182, Canberra 2601 #Freshwater Systems, 82 Waimea Avenue, Sandy Bay, Tasmania 7005

Water quality measurement

Why Measure River Health? To understand why we are interested in measuring river health, it is first necessary to appreciate our changing perceptions of the values and appropriate uses of rivers. In the 200 years since European settlement of Australia, the principal uses of rivers have been navigation, drinking water, irrigation water, effluent disposal and recreation. These uses are of high social and economic value. More recently, the environmental movement has stimulated the widespread appreciation of the natural and ecological values of rivers through such concepts as 'wilderness' and 'biodiversity'. This has been (at least partially) more formally encapsulated by Australian governments adopting the principles of ecologically sustainable development (ESD). However, inappropriate land use and instream practices have led to a continued decline in the social, economic and environmental values of our rivers. In the ecological context, rivers in Australia have four major management needs: • protecting and conserving the remaining pristine rivers and pristine river reaches across as many river types as possible • protecting riverine endangered species and ecosystems of high conservation value • applying ESD principles to new developments which might affect rivers • rehabilitating degraded rivers to acceptable levels of river health. One of the first steps in achieving these objectives is to: • provide feedback to river managers, community groups and the community at large on the current and changing status of river health • identify and predict specific impacts and their causes or sources

• identify reaches of high conservation status requiring protection • demonstrate the effectiveness of management actions aimed at improving the quality of rivers.

Assessment Methods Assessing the condition of rivers in Australia has had a long and varied history. It has involved two principal approaches: physio-chemical monitoring and qualitative 'state of the rivers' descriptions. While both approaches have produced some useful results, they have generally failed to provide a consistent and comprehensive assessment of river condition either regionally or nationally, and have said little about the ecological state or environmental quality of rivers. Moreover, they have been unable to reliably assess the impacts of various instream and catchment practices on river ecosystems or provide reliable answers to management questions in a cost-effective way that can also be understood by the community. The preoccupation with chemical water quality has also largely overlooked structural impacts that have led to alterations to river flow regimes, loss of habitat area, loss of habitat diversity, obstructions to passage through streams and riparian degradation (Harris 1995). Current Monitoring. A recent review of water quality monitoring in Australia (EPA 1995) identified about 1800 current water quality monitoring programs costing about $100 million pa. This analysis of monitoring practices led to the following key recommendations: • redistribute funding within programs to emphasise improved planning, design, use of field analyses and reporting of information to the community, at the expense of laboratory analyses • increase collaboration between organi-

sations to reduce duplication and improve information flow • increase analysis and reporting from long-term data sets • increase community involvement. 'State of the Rivers' assessments have been undertaken in Victoria, NSW, Queensland and Western Australia. These assessments each use different methods and are essentially descriptive in nature. They attempt to incorporate a range of variables and components (eg water quality, channel form, riparian condition) and summarise these data into a single assessment of condition. Typically, there is little biological information in such assessments. Some are catchment-based and have the potential to work well with integrated catchment management. However, one of the main problems in these assessments is the lack of a local, regional or national reference against which to judge the results. This does not allow recognition of inherent differences in river form and condition that can occur given differing geomorphology, stream size etc. Bioassessment. The case for using bioassessment techniques to measure river health is principally two-fold: • assessing ecological values requires direct measurements of the system • physico-chemical measurements alone are inadequate for assessing river health, as the processes linking changes in physical and chemical eonditions in rivers and the ecological state are either poorly understood or too complex. They also do not take into account important changes to river habitat and are frequently instantaneous. The integration of regionally referenced physical, chemical and biological measures is needed to provide comprehensive, sensitive assessment of river condition. The biological measures can involve a wide range of groups including

In.stream sampling WATER MAY/JUNE 1996

macroinvertebrates, fish, algae, diatoms, microorganisms and macrophytes. Each group reflects environmental stresses in different ways and can be used to assess river health. They have the potential to .provide an integrated response to a number of stresses as well as measures over different time-scales. Selective responses to particular stresses at the group, ta.xon and species levels can help identify specific sources of stress (eg a particular type of chemical pollution or change in habitat structure). The adoption of biological methods has been slow in Australia, partly reflecting the culture, skills and knowledge bases of Australian water managers. However, their acceptance is improving (Norris and Norris 1995) as a result of improved standardised protocols, more cost-effective, rapid bioassessment techniques, simplified presentation of the results, and the growing demand for direct measures of ecosystem health.

RIVPACS Development Scientific Methodology. Monitoring the time trends of individual river parameters or periodic descriptions of river characteristics are not in thems~lves sufficient to assess and monitor the condition and health of rivers. A methodology is required to measure 'health' against an appropriate, regionally based scale. The only methodology that has attempted, and largely achieved this to date, whether physical, chemical or biological, is RIVPACS, the River Invertebrate Prediction and Classification System.

This approach is based on comparing monitored river sites against reference unimpacted, or least impacted sites. This gives a measure of the degree to which an impacted site retains the biological quality it would have had if undisturbed. It also allows prediction of the biotic community anticipated at a site if it was undisturbed. RIVPACS was developed using macroinvertebrate fauna but the same principles can be applied to other fauna! groups. History of RIVPACS. The development of RIVPACS started at the River Laboratory of the Institute of Freshwater Ecology, UK in 1977. The first project had two objectives: â&#x20AC;˘ to develop a classification of unpolluted running water sites based on macroinvertebrate fauna (seen relevant to the conservation of biological examples of the full ange of river systems in the UK) â&#x20AC;˘ to determine whether the fauna to be expected at an unstressed site could be predicted from physical and chemical features only (seen as the first stage in the new challenge of attempting to develop a prediction system for detecting and assessing environmental impact at stressed sites, Wright 1995). The decision to use macroinvertebrates rather than other faunal groups was based on the moderate richness of the macroinvertebrate fauna throughout the country, the availability of good taxonomic keys and the extensive literature on the response of many ta.xa to a range of pollutants. Biologists in the UK water industry were also highly familiar with

the macroinvertebrate fauna. The project, based on 268 sites on 41 river systems, commenced with a fouryear program to determine the feasibility of a prediction system. During phases two and three (six years) the first version RIVPACS I was developed, based on 370 sites and 61 rivers. By 1989-90, an upgraded RIVPACS II version, based on 438 sites and 80 rivers and incorporating a new classification and prediction system, was completed for operational use in the 1990 UK River Quality Survey. The most recent and advanced version, RIVPACS III, based on 700 sites, was used in the 1995 UK River Quality Survey. Adoption of RIVPACS. In the Prime Minister's Environment Statement, in December 1992, about $7m was allocated to support the development of integrated physical, chemical and biological monitoring of Australia's rivers. The funds were allocated to the Environment Protection Agency (EPA), who divided the funds between State/Territory projects, R&D and a water quality review (EPA 1995). A national call for project proposals was made in March 1993 but this did not provide an adequate framework for a national program. About this time, discussions took place with the Land and Water Resources Research and Development Corporation (LWRRDC), who were also planning to establish a national rivers program. In June the two organisations formally established an agreement to run a joint program, with

National River Health Program

Environmenta Flows

Monitoring River Health

techniques storage management fish

techniques

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effects on biota

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impacts

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flow - algae

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ecological processes exotic biota

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integrating methodologies

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molecular metabolism

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LWRRDC providing the R&D management support. A program management committee was formed with two. members each from LWRRDC, EPA and DEST, to be later joined by two members from the Urban Water Research Association of Australia (UWRAA). The management committee recognised the need for a program framework with clear national objectives and used a workshop organised by the University of Canberra ('Use of Biota to Assess Water Quality', September 1993) to help identify program priorities. A session was devoted to proposals from the states and territories. Presentations on RIVPACS at the workshop led to its subsequent adoption by the management committee as a national framework for river health monitoring. This constituted a change in direction but has subsequently been widely accepted amongst state and territory agencies and the research community. Following the September workshop, the National River Health Program (NRHP) was formed and the management committee appointed a program coordinator with expertise in river assessment. A detailed program (Figure 1) was quickly assembled and the commis_sioning of projects commenced. Details of the program structure, funding, R&D and of RIVPACS can be found at the NRHP world wide web home page at the following address (or URL): http :// www.erin.gov.au/ portfolio/ epa/ nr hp/index.html and is described in NRHP (in press). The philosophy was to develop RIVPACS through the state/ territory monitoring program; to conduct a number of supporting R&D projects to both enhance the RIVPACS methodology and address some specific issues regarding its application to Australian conditions; to conduct projects on the development of alternative but complementary approaches (using similar principles including the essential RIVPACS methodology) for other groups (fish, algae, diatoms, microorganisms, macrophytes) , and provide support for macroinvertebrate taxonomy. The latter is seen as a key hurdle in further developing RIVPACS using macroinvertebrates. Bioassessment Protocols. One of the first tasks of the coordinator was to prepare a manual (NRHP 1994) with a standard bioassessment protocol for use in the program. This was developed with assistance from a technical advisory group and utilises rapid biological assessment (RBA). RBA has the principal benefit of reduced cost (through less time) than traditional, more rigorous quantitative assessment. The main considerations in developing the protocols were: • habitats to be sampled • choosing the reference (least impacted) sites • number and density of reference sites • sampling areas, intensity and frequency 42

• sampling devices, mesh sizes • proportion of sample examined • live pick versus laboratory analysis taxonomic level • quality control and assurance • databases • reference site classification • discriminant analysis • model development and testing • model prediction and outputs • final model evaluation and use. Details of each protocol are given in the bioassessment manual and are being actively refined. Their adoption and careful adherence are essential to the quality and consistency of the RIVPACS models developed. This aspect has been emphasised in the program through internal and external QA/QC programs.

Technical Issues RIVPACS has been successfully applied to the temperate UK but its application to Australian rivers poses a number of specific issues relating to the scale of our continent, range of environments and greater variability in flow regime. Some of these issues are briefly outlined below. Selection of Reference Sites. In Australia, with its extensive land clearance, principally for agriculture, it is not always possible to identify 'pristine' reference sites, particularly for the lowland sections of rivers. Development of RIVPACS in these circumstances requires using the concept of 'least disturbed site selection', that is sites with disturbances judged to be substantially less than the more intense impacts of management interest. The impact on the quality of assessments imposed by this limitation is still to be determined. Site Number and Density. The successful construction of RIVPACS (ie with a good predictive power with low error) requires an adequate number and density of reference sites. The MRHI currently includes over 1400 reference sites across Australia. However, the breadth of coverage desired by some state agencies will at this stage limit the power of the first ('RIVPACS I') models. The potential combination of sets of sites across state/ territory boundaries depends on the desire of states/territories to develop and maintain their own RIVPACS models or to collaborate on joint model development. Recognition of the need to develop regional (within or across state/ territory boundaries) model development is implicit in the current program. Flow Variability. Australian streams are characterised by high flow variability at a range of time scales with most inland streams being ephemeral. In the large semi-arid/arid region, the streams become a series of pools which contract or even dry out during dry periods. The ability to meaningfully sample ephemeral rivers and develop practical models is, at

this stage, highly uncertain. Ecological Stability. The seasonal and inter-annual variability of macroinverte brate communities is largely unknown in Australia and requires careful evaluation of long-term data sets. A lack of stability of these communities will have implications for the sampling requirements and ultimately for the power of the models. Specific R&D is currently being conducted to examine this question.

Complementary Approaches The MRHI is supporting R&D on a number of alternative and novel methods of river health assessment, some of which will utilise RIVPACS principles and others complement RIVPACS. A brief outline of these approaches is given in the following. Assessment Using Fish. Fish community structure can provide potentially powerful tools for assessing aquatic environmental health. Their key attributes in this task are: • sensitivity to most forms of human disturbance • integration of ecosystem processes and impacts due to position at or near the apex of the food chain • ease of identification • longevity, allowing the assessment over large temporal scales • life-history, population and community level information available • acute and chronic impacts detectable • seasonally stable populations, sensitive in recruitment to flow events • particularly effective for macro-environment disturbances • present in small, large and polluted rivers • biological integrity of rivers rapidly evaluated • results easily interpreted by community. In the United States it has been demonstrated that fish can provide a valuable index of river health provided that there is a good database on the species composition and trophic structure in representative basins against which survey data can be compared. The principles of RIVPACS can be applied to fish and this is being studied at present in the UK (Sweeting pers. comm.) and at Griffith University. The latter project, funded under the NRHP, is assessing the feasibility of developing a River Fish Prediction And Classification Scheme (RIFPACS) in Australia. The first stage of the project is to assess the feasibility of developing predictive models relating fish community composition to river habitat and water quality characteristics. Diatoms. Diatoms possess a number of attributes suitable for river quality assessment: • wide, cosmopolitan and abundant distribution • well established taxonomy WATER MAY/JUNE 1996

• very sensitive to changes in water chemistry with many taxa having well defined ecological optima and to.lerances • rapid response time reflecting rapid changes in water quality • not highly habitat-dependent • easily sampled and preserved. In the NRHP two projects are being funded to develop a 'Diatom Prediction and Classification System' (DIPACS) based on similar principles to RIVPACS. Effects of sewage disposal, sediment, salinity and nutrient pollution are being assessed. Phytoplankton. A great variety of phytoplankton methods have been proposed for monitoring rivers. Some of the advantages of phytoplankton are: • an important component of the ecosystem in large rivers • present before and after pollution • directly reflects nutrient pollution better than fauna • different to animals in sensitivity to toxic materials, hence enhancing range of bioassays. The wide range of methods available and the differing extents to which they can be applied without further development means that it is essential to select methods with care. In the NRHP, a phytoplankton bioassessment protocol is being developed for Australian rivers to help improve the effectiveness and consistency of agency monitoring programs. The protocol will include benefits and objectives of phytoplankton assessment and establish a common procedure for sampling, preservation, transport, concentration, identification, counting and data recording. The determination of biomass, as well as methods of analysis and reporting are also being addressed. Use of Microorganisms. Recent advances in aquatic microbial ecology are resulting in the development of a range of new methods, many based on molecular biology techniques, that may lead to another approach to assessing river health. The advantages that microorganisms have over other groups are: • they are present in very large numbers • they grow very rapidly and respond quickly to ecosystem changes • they can be used as direct indicators of sewage and livestock pollution • they can indicate stress by organic chemicals, heavy metals and heat • they are the most diverse biological group and are appropriate as biodiversity indicators of pollution. The NRHP recognises the potential use of microorganisms in river health assessment but believes a considerably improved understanding of key processes, particularly in unimpacted systems, is required before practical, reliable methods can be developed. A review (Hart et WATER MAY/JUNE 1996

al in press) of microbial indicators of river health has been commissioned to provide recommendations on priority research in this area. Use of Macrophytes. In Australia, scientific understanding of the ecology of aquatic macrophytes in rivers has not progressed as well as for the other groups, resulting in reservations about their use as river health indicators. The NRHP has commissioned a project to resolve some of these concerns, specifically interpretation of species absences, role of epiphytes, applicability of the community concept, species presence/abundance variations at different time-scales and species response to water and sediment quality. Community Metabolism. Assessing river health through community metabolism measurement is seen to have two key advantages: • a more direct and holistic 'process-oriented' measure of river health • an early warning of environmental stress (changes in rates of metabolism may occur before compositional changes in the aquatic community). The NRHP has funded research to develop a standardised protocol for routine bioassessment in a range of habitats. The methodology involves measurement of changes of dissolved oxygen in perspex chambers in situ to determine metabolic rates of both production (P) and respiration (R) and hence P/ R ratios from a range of reference and impact sites.

Future Development The future of the National River Health Program is dependent on Commonwealth funding beyond 199596. The program described in this section is based on adequate funding for an addi, tional four years. The principal aim is to conduct Australia's first national river health survey in 1998-99 as a key input to state and national 'State of the Environment' reporting. The benefits of this survey will be a nationally consistent and scientifically based reporting to the community on the ecological state of the nation's rivers. The survey will principally rely on use of RIVPACS-Australia but supplementary information will be provided by limited application of RIFPACS, DIPACS and other promising approaches which will be developed further in the future. The national river health survey information will be presented in an easily understood format for community consideration.The second principal aim is to develop a tool kit of reliable bioassessment methods with sound national protocols and guidelines for their most appropriate uses. Clearly some of these methods (eg microbial) are still in the research domain

and will require on-going investigation of their feasibility and utility. However, by the end of the second funding phase, the more promising tools will be available for use by the water industry. Some of the subsidiary, but equally important aims are to: • have predictive tools like RIVPACS and DIPACS used regularly to assess local impacts and pollution incidents • enable interpretations of the bioassessments of impacted sites in terms of likely causes or sources of river stress • produce a river classification system derived from sample and attribute data to assist riverine floodplain and catchment management • identify rivers, river reaches and sites of high conservation value • integrate RIVPACS with the WaterWatch program to provide river, catchment and land care groups with a scientific tool for managing rivers locally.

References EPA (1995). Water Qyality Monitoring in Australia. Report prepared for the Environmental Protection Agency by Aquatech Pty Ltd, Feb 1995, 278 pp. Harris,JH (1995). 'The use offish in ecological assessments'. Austj. &ol 20, 65-80. Hart, B T , Ross, J and Veal, D (in press). Microbial Indicators of River Health. LWRRDC Occasional Paper Series. Norris, R H and Norris, K R (1995). 'The Need for Biological Assessment of Water Quality: Australian Perspective' . Aust. J &ol 20, 1-6. NRHP (1994). River Bioassessment Manual: Version 1. Available from LWRRDC, Canberra. NRHP (in press). National River Health Program brochure, LWRRDC. Wright] F (1995). 'Development and Use of a System for Predicting the Macroinvertebrate Fauna in Flowing Waters'. Aust.] &ol 20, 181-197.

Authors Dr Nick Schofield is Program Manager Water Resources, for the Land and Water Resources Research and Development Corporation, a position he has held for three years. Originally gaining a PhD in astrophysics, Nick now has nearly 20 years experience in water resources, undertaking research in catchment hydrology and environmental impacts of mining, forestry and agriculture. He currently manages six national water programs and over 150 projects for L WRRDC. Dr Peter Davies is a researcher and consultant in aquatic environmental issues. Originally trained in chemistry and ecotoxicology, he was subsequently involved in aquatic fauna[ and recreational fzs,_hery management and aquatic environmental research for 12 years. Based in Tasmania, he has coordinated the National River Health Program for L U'RRDC and DEST since late 1993.

ENVIRONMENT

ENVIRONMENTAL AUDITING OF WASTEWATER TREATMENT PLANTS P Nadebaum, P Drew, W Drew·~ Abstract The scope and methodology of wastewater system environmental audits in Australia is discussed, including the role of an Environmental Management Systems review, environmental improvement plans, compliance audits, broader environmental impact audits, and accredited licences. Environmental issues which are difficult to deal with from an auditing perspective are discussed, as well as the experience drawn from a number of such audits. While good compliance with regulatory licence conditions is usually achieved, good compliance with broader policy objectives such as an effective requirement for "no adverse effect" is difficult to show, and introduces potential lia bility. An approach to identifying and prioritising such areas of non-compliance is discussed.

Keywords Auditing, wastewater, environmental, regulation.

Introduction There has been considerable interest in environmental auditing of manufacturing facilities over recent years, and the water industry is now applying the principles to review their water and wastewater treatment operations. Experiences in auditing municipal wastewater treatment plants and systems are discussed; including Melbourne Water's major South Eastern Purification Plant and the Dandenong South Treatment Plant, a regional sewerage system including several wastewater treatment plants in Wagga W agga and several wastewater treatment plants in New South Wales. This paper discusses the issues which apply in carrying out environmental audits of wastewater treatment facilities; it is written from the perspective of the auditor, rather than from the perspective of the owner of the facility.

Scope of Audits The scope of an environmental audit depends on the objectives of the audit. While it would seem to be straightforward and of little variation, often the term

"environmental audit" is used loosely, and in practice there are a great many alternative approaches: • Environmental Audit vs Environmental Management System Audit: an environmental audit usually refers to an audit or review of the operations or current situation with regard to compliance with environmental regulations, or possible environmental effect. Such an audit will also include a review of the management of the facility to confirm that it is adequate and appropriate procedures are in place. An environmental management systems (EMS) audit, on the other hand, is restricted to a review of the management systems, and does not necessarily identify possible adverse environmental effects, or the extent of compliance with environmental regulations. For an EMS audit to be useful it will usually require that an environmental management system is already in place. • Due Diligence: audits carried out for due diligence purposes are the most common form of audit. These have the objective of identifying the most important issues, and especially those which could have a serious impact upon the organisation which is responsible for the facility and has commissioned the audit. If the audit is for sale or pre-purchase purposes, then "important" will usually mean issues that have significant monetary importance. If the audit is for general operational purposes, then "important" can be cast more widely, and will include issues which can have significant adverse environmental effects, or political (eg public outrage) consequences. Environmental audits usually review issues which are regulated under environmental legislation. They usually focus on possible effects on air, water, land and noise. Environmental audits may or may not extend to discharges to sewer; occupational health and safety; dangerous goods including quantitative risk assessment; waste minimisation; asbestos and off-site disposal of waste (solid and liquid). • Compliance audits: some audits are defined narrowly in terms of reviewing only the extent of compliance with licences and current legislation. This may be a valid requirement; however, in the

later sections of this paper it will be evident that this scope has potential to not identify some significant issues. • Environmental Management Plans, and Environmental Improvement Plans : the Victorian EPA has defined several terms closely related to environmental audits: organisations can obtain "accredited licences" (ie an organisation can selfmonitor and avoid requirements for obtaining EPA approval of minor works, and obtain significant reductions in licence fees) if they have in place an Environmental Management System (which has been audited against a recognised standard such as BS7750), an Environmental Audit has been carried out (involving an independent environmental auditor), and an Environmental Improvement Plan . has been prepare? (with involvement of the local commumty) . This body of work is referred to as an environmental management program.

Methodology Quality Assurance. There is no single defined methodology for undertaking environmental audits, and the methodology will usually be adapted to best satisfy the objectives of the audit. It is important that a disciplined, planned approach be undertaken, and the principles of Quality Assurance should be applied. A QA plan should be prepared at the outset, including a work plan. We have found a questionnaire approach to be effective, and having completed a large number of such audits, we are able to draw on some 50 proforma questionnaires which extend to a wide range of facilities and operations within facilities. These proformas outline key questions, and enable the facility operato_r to assemble information prior to the audit team arriving on site. This minimises the time spent on site, and maximises the value of the site visit. A good set of questionnaires can enable the "walk through" audit to be a practical approach, although in practice there is always follow up required to obtain missing information, and to follow up on issues that the walk through identified. The assembly, analysis and presenta*CMPS&F Environmental, 390 St Kilda Road Melbourne Vic 3004

WATER MAY/JUNE 1996

tion of information depends on the desired format of the audit report and the objectives of the audit. We have found that a tabular format based directly on the questionnaires is useful and cost effective for summarising the information, particularly for very large audits (eg of multiple facilities). Ranking. A tabular format is also useful if it is likely that the audit output will be computer manipulated to rank and prioritise the findings. If this is intended, then a ranking algorithm formulated to satisfy the audit objectives will be required. We have developed a number of such algorithms; these are generally based on the measures of frequency (or likelihood of occurrence), and severity or degree of hazard. In some audits the latter measure is expanded to include consideration of two effects: severity of environmental effect, and severity of "public outrage" (or some other such socio-political measure) which may not be directly dependent on the severity of environmental effect. As an example of the outrage factor, consider spillage of a few litres of oil into a stormwater drain, and the drain leading to a beach: this could have a very visible and momentous e_ffect if this were to be a populated inner city bathing beach, whereas in a remote location it may go unnoticed and the "outrage" may be minimal. We have developed and trialed questionnaire systems where the auditor enters the information directly into the computer. In general, we have found this approach to be limited, except perhaps for audits where large numbers of facilities are involved. Direct entry has the danger of mechanising the approach to the extent where it detracts from the auditor's judgement being applied, and useful comment and qualification can be lost. In the case of wastewater treatment facilities, a diverse range of issues and systems need to be addressed, and in our experience this is best done using the questionnaire as a base and a stimulus for the auditor, rather than trying to force all of the information into the format. Degree of Compliance. We have also been requested to provide a definitive comment on the degree of compliance with the licence and environmental policy. While it would seem to be a simple request, it is very difficult in practice. Compliance with specified licence criteria can be reasonably easily measured, and a "percentage compliance" can be estimated. However, in terms of policy requirements (eg as discussed in section 4.3) the situation is not well defined and there is neither the definition of what parameters require to be complied with, nor the measurements which provide a measure of what the situation is with regard to potential impact. Because of this ill-defined situation, we have developed a compliance ranking system which includes estimates of what WATER MAY/JUNE 1996

is known about what has to be complied with, what has been measured to quantify the degree of compliance, and the probable degree of compliance based on the auditor's judgment and the information available. In this way a measure of probable compliance and uncertainty can be obtained. Liability. We are often requested to include some comment regarding "liability", particularly when issues of contaminated land are involved. We are in general very cautious about offering comment on liability and who may be liable, other than perhaps in very general terms and with the qualification that questions of liability require appropriate legal input to resolve. Inclusion of comments regarding liability in audit reports can also be potentially dangerous, should the audit report be later called in evidence during litigation.

Issues Overview. In the following sections specific issues which can arise in undertaking environmental audits of wastewater treatment plants are outlined. We have found these particular issues are not necessarily obvious at the outset, or can be difficult to assess. Often the issues will not lend themselves to an easy conclusion regarding their significance in terms of environmental effect (or perhaps financial liability), or extent of statutory compliance. EMS. Those that are familiar with QA systems will be aware that compliance with standards for such systems is not easy. Many wastewater treatment systems are well operated and managed by engineers, who approach the task from a technical perspective. These operations will not pass an EMS audit, and to do so requires the implementation of an EMS. As such, it is not sensible to request an EMS audit before such a system has been set in place. Nevertheless, a review of management practices can be useful for systems operated on a traditional basis, and can identify where deficiencies may place the operation at risk. Compliance. Facility operators usually think in terms of compliance with licence requirements. However, in our experience an EPA licence will not always address all of the important issues, particularly issues which fall into the general category of 'policy' issues. Licences generally address discharges to air and water; discharges to land and groundwater are not always included in a facility licence. In the case of discharges to water, for example, the licence will often only extend to a subset of well known constituents, such as BOD, COD, TKN, ammonia, P, pH, and selected heavy metals. The facility monitoring program will cover these, and it can be expected to be a simple matter for the auditor to determine whether compliance with these

parameters is achieved. For wastewater treatment plants which receive largely domestic wastewater, such a subset may be sufficient. However, where there is an appreciable industrial wastewater input a wider range of constituents may require consideration. In general, environmental regulatory policy will have the objective of 'no adverse effect', and demonstrating that this has been achieved can be difficult. In the case of effluent discharges, this problem can reduce to the difficult one of setting ocean discharge acceptance criteria. The new Australian and New Zealand Environment and Conservation Council/ Australian Water Resources Council (ANZECC/ AWRC) national water quality criteria can assist in this; however, they are not necessarily complete and there remains the uncertainty in setting speciesdependent No Observable Effect Levels, specifying mixing zones, and levels of protection. By way of example, some of the issues that have arisen in our work include: • Surfadants - are surfactants at acceptable levels, noting that some surfactants have low No Observable Effect Levels, and are not well removed in sewage treatment systems? (This can also apply to some heavy metals). Surfactants can also have indirect exposure effects, via foam on vegetation - but this is not at all well defined. In our, experience, toxicity testing of whole effluent has not indicated that toxicity is a problem; however, indirect effects are not easily dealt with and their significance can only be judged from observation of possible effect. • PAHs - they are ubiquitous substances, and can be present in the wastewater. The more toxic and persistent PAHs (eg benzo(a)pyrene) are difficult to degrade and have very low acceptable ambient water criteria, although they will tend to partition to the sludge phase. Bioaccumulation can also complicate setting the applicable acceptance criteria. In general we have not found PAHs to be a problem, and there is an argument that PAHs after biological treatment, even if not degraded, are strongly adsorbed and are not significantly bioavailable, and no longer exhibit the toxicity generally assigned to them. Test work is being carried out to pursue this in the USA. • Dioxins - is it necessary to monitor for these in the effluent in view of the high cost? If there is or has been a significant industrial input (especially large volume painting operations or operations where preservatives are used), then some checks would be in order. Dioxins will partition to the sludge, and compositing of sludge samples with a varying history within the plant can provide the lowest cost check as to whether dioxins are entering the plant.

• Nutrients, including possible ammonia toxidty. We have found ammonia in 45

some effluents to be at levels which could technically exceed toxicity levels; however, toxicity testing has not indicated that there is a toxicity problem. â&#x20AC;˘ What is the risk of clandestine discharges of toxic trade waste, which practically may not be detected because of their sporadic nature, and are probably not monitored for? A review of the history of operational upsets and the sludge quality can indicate whether this is occurring to a significant extent. In our experience this is generally not a problem. The large dilution available can usually offset any such discharges. â&#x20AC;˘ Chlorination of effluent for disinfection purposes is now generally sought to be avoided; however, where it is practised the formation of chlorinated compounds requires consideration. Plants which we have audited where chlorination has occurred have not had a monitoring program carried out in sufficient depth to reach conclusions regarding the significance of such compounds, although it appears that there has been sufficient dilution in the discharge for the trace levels which have been formed to not be a significant concern. This is an area which requires more investigation. Bioaccumulation testing and biodiversity surveys in the area of the discharge can provide information on possible effects, and can assist the auditor in reaching a conclusion as to whether there are significant effects occurring which may not be evident from the monitoring which is practically able to be carried out. Toxicity testing can be used to obtain a broad measure of whether the effluent may have an adverse effect on ecosystems at the point of discharge; however, selecting the test and the species and the extrapolation to long term chronic effect levels leaves uncertainty. Contaminated Land. Disposal of sludge or treated effluent to land is a common occurrence at waste water treatment plants. Disposal is sometimes only thought of in terms of the final disposal operations; in practice the use of lagoons (which almost always leak) and sludge stockpiling (albeit temporary) on land also constitute disposal to land. Australian sludge disposal guidelines have not been finalised, and disposal of sludge on site may give rise to concentrations of heavy metals which exceed the criteria which are normally specified for land uses (such as residential). Higher concentrations of contaminants such as the heavy metals can be accepted when present in a sludge matrix, because the contaminants are strongly adsorbed and are not bioavailable or toxic as would be the case if the contaminants were present as free chemicals added to the soil. Demonstrating that this is the case can be difficult, and this is an area where the auditor must draw on work which underpins the proposed sludge disposal guide-

lines, and consider carefully the proposed land uses. Consideration must particularly be given to possible future use of the land for sensitive uses, such as agriculture or residential. Often burial of materials on site occurs (such as incineration ash, and grit), and in our experience this may not be specified in a licence. Clearly such areas will be unsuitable for sensitive uses such as residential (eg from a structural point of view) and can give rise to restrictions on the use of the land, or perhaps liability for clean up. Ash may be leachable, and there may be a need for ongoing monitoring. Once again, the issues here largely revolve around the lack of definition of environmental regulatory policy objectives, where the auditor must consider the broader requirements and context of regulatory requirements, in order to provide good advice and an appropriate perspective on the situation which exists with regard to a particular facility. Contaminated Groundwater. In our experience, wastewater treatment systems have a high probability of contributing to groundwater in the area. This occurs through leaking lagoons, overflow ponds, leaking underground pipe systems, and sludge and effluent disposal operations. Large unlined ponds are a potentially major source of infiltration. It is possible that groundwater ingress has not been considered, and monitoring bores will not be in place to provide information on what the situation is. However, while such leakage can occur, it may not be adversely affecting the condition of the groundwater, especially if the leakage occurs from effluent lagoons where the effluent is of relatively good quality. Our Test work at a number of facilities has indicated that the groundwater quality has decreased for some constituents (such as nitrogen compounds) however, it has generally remained within water quality acceptance criteria (eg the ANZECC/ AWRC guidelines) even though significant recharge was occurring. This will be a function of the soil characteristics, the depth of groundwater and the sensitivity of the use, and is not a general conclusion. Contaminants such as heavy metals and adsorptive organics (such as pesticides and dioxins) have been observed to be retained in the sludge layer and are not found in elevated concentrations in the groundwater. In one facility there were some measurements of elevated volatile chlorinated organic constituents; this may have been related to effluent chlorination which was practised for odour control and disinfection; however, there was the possibility it was an analytical artefact and further work was required to resolve the issue. Emissions to Air. Emissions to air, particularly odour, are reasonably easily

dealt with by the auditor, as there will be a complaints file recording problems and the regulatory situation is usually reasonably well defined. Requirements for containing aerosol emissions are less clearly defined, and there are not well established monitoring procedures. In practice, control is usually achieved by maintaining buffer distances, although this becomes more difficult to enforce when treated effluent is being used for irrigation purposes. We have found situations where aerosol drift could be a potential concern, and this is an area where review is necessary. Third Party Use. It is becoming common for products, such as sludge compost or treated effluent, to be used by third parties. In some cases this is via an intermediary, such as a contractor who will produce compost from sludge taken from the facility, and sell the compost. In such situations careful monitoring of the quality of the product or performance of the contractor is necessary, and this is an area where wastewater treatment plant operators may not have the procedures to ensure that this is carried out adequately. An EMS or Quality Assurance procedures can greatly assist in this. By way of example, in one case a contractor was producing compost by the addition of bulking materials to the sludge. In most cases this would be satisfactory; however, the contractor had a ~ource of grease trap waste to dispose of, and was using this as an additive to the compost mixture. This may be satisfactory; however, it was being done without the knowledge of the wastewater treatment plant operator, and if the grease trap waste contained industrial waste there could be problems with the end use which might reflect badly on the wastewater treatment plant operator.

Conclusions Environmental audits are becoming a commonly used tool to review the performance of wastewater treatment plants. They can provide an excellent means of providing assurance that a particular facility is performing in accordance with regulatory requirements, and major operators such as Melbourne Water are now routinely carrying out environmental audits and are implementing quality assurance measures which will provide the necessary assurance that environmental responsibilities are being met. Environmental audits can be a relatively co~plex undertaking, and require considerable knowledge and a good understanding of environmental regulatory and policy issues. In practice it can be difficult for an auditor and a wastewater treatment plant operator to determine whether a particular treatment facility is in compliance; this occurs because environmental policy in Australia is in a process of evolution, and the requirements for environmental protection are not well defined. WATER MAY/JUNE 1996