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FEBRUARY

1991 JOURNAL OF THE AUSTRALIAN WATER AND WASTEWATER ASSOCIATION


Official Journal

water

ISSN 0310-0367

Volume 18, No. 6, February 1991

AUSTRALIAN WATER AND WASTEWATER ASSOCIATION

My Point of View ............................................... 3

Commissioning Procedures for New Water Pipelines L. S. Burn and T. J. Richards ....... ............. 32

Association News President's Message ................................... 5 It Seems to Me ............................................ 5

BATEA and Secondary Treatment: Hardwood Pulp Mills can be Environmentally Safe ......... 36 Two Relevant Publications ............................. 38

Land and Water Resources Research and Development Corporation .........................._. .... 10

Blockage of Piggery Effluent Pipes a Magneto-Hydrodynamic Solution ............... 39

IAWPRC News .................................................. 12

Milli-screening in Aquaculture - Use of Disc Filters ....................................................... 40

CONTENTS

Industry News .................................................. 12 The British Water Industry - November 1990 John Court .................................................. 15 Developments in Wastewater Management for Intensive Rural Industries K. H. Bowmer, P. Laut and E. A. Swinton .............................................. 17

Conference Calendar ...................................... 42 Book Reviews

43

Plant, Products and Equipment ..................... 44

OUR COVER For eight years a major manufacturer of polyethylene has successfu/Jy utilised all its wastewater for irrigation of pasture. A neighbouring plant has recently commenced irrigation of a large tree plantation. Story page 22 Photo courtesy of Commercial Polymers Pfy Ltd.

Zero Discharge from Chemical Plants E. A. Swinton .............................................. 22 Microbiological Quality of Drinking Water a Review of the Major Urban Systems K. Power and L. Nagy ................................ 24 Working with Lobby Groups ........................... 29

NITTE CHANGE OF ADDRESS OF AWWA FEDERAL SECRETARIAT Postal Address: PO Box 388, ARTARMON NSW 2064 Telephone: (02) 413 1288 (no change), Facsimile: (02) 413 1047

FEDERAL SECRETARIAT Telephone (02) 413 1288 Facsimile (02) 413 1047 Office Manager - Margaret Bates

FEDERAL PRESIDENT Peter Norman Telephone (08) 226 2249

EXECUTIVE DIRECTOR Peter Hughes Telephone (02) 413 1288 Facsimile (02) 941 726

FEDERAL SECRETARY Greg Cawston Telephone (042) 29 0236

FEDERAL TREASURER John Molloy Telephone (03) 615 5991

BRANCH SECRETARIES Canberra , ACT Peter Cox PO Box 306, Woden 2606 (062) 498 522

New South Wales David Hope, PO Box 460, Chatswood 2057 (02) 269 5212

Victoria John Park Cl- Water Training Centre. PO Box 409, Werribee 3030 (03) 741 5844

Queensland Don Mackay, PO Box 412, West End 4101 (07) 840 4844

South Australia Rob Townsend , Cl- State Water Laboratories. E&WS Private Mail Bag , Sa lisbury 5108 (08) 259 0244

EDITORIAL CORRESPONDENCE E.A. Swinton, 4 Pleasant View Crescent, Glen Waverley 3150 Ofllce Phone and Autotax (03) 560 4752 Home (03) 560 9306

Western Australia Steve Gibson CMPS, 200 Adelaide Terrace Perth 6000 (09) 325 9366

Tasmania Annette Nichol GPO Box 503E Hoba rt 7001 (002) 28 2757

ADVERTISING Ann Sykes·Smlth Applta, . 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 348 1206

PRODUCTION EDITOR J. Grainger,

Northern Territory Lindsay Monteith PO Box 351 Darwin 0801 (089) 81 5922

Applta, 191 Royal Parade, Parkville 3052 (03) 347 2377 Fax (03) 348 1206

WATER February 1991 I


THE BRITISH WATER INDUSTRY-NOVEMBER 1990 by John COURT Chief, Water and Chemicals Division, State Pollution Control Commission.

SUMMARY Mr R. Wilson, Managing Director of the Water Board Sydney, and Mr J. Court, Chief, Water and Chemicals Division, SPCC NSW visited Britain between 2 and 16 November 1990 as part of a trade mission, organised and funded by the British Government. This article summarises their impressions, and provides a comparison with the Australian scene.

CHANGES IN THE BRITISH WATER INDUSTRY The management of water in Britain is at an interesting and critical phase of development. Until 1988 all-purpose water authorities took responsibility for all aspects of water. They managed the resource, supplied water and collected and treated sewage for householders, industry, commerce and government. They issued the licences (called 'consents') for both abstraction of water and discharge of effluents to rivers, estuaries and the ocean. In environmental terms they were both 'poacher' and 'gamekeeper', an arrangement which was seen to have failed environmentally. Also, despite the anticipated efficiencies of gathering of all functions into single large agencies in the seventies, they were seen to have been inefficient financially. This arrangement has been changed. Ten public limited companies (pie's) have been formed from the all-purpose water authorities to manage the water supply and sewerage functions. Their shares are listed on the stock exchange and their financial performance is reflected accordingly. The 'City' is already judging the pie's depending on the direction of their individual development. In addition to the 10 major pie's there are a further 27 water companies which have traditionally supplied water to certain major cities. There are thus some 37 private organisations in England and Wales (the 'revolution' has still to come in Scotland and Northern Ireland) which are in the business of supplying water and sewerage services. Should one or more fail it is probable that others would move in to take over their functions, thus preserving public service.

REGULATION The structure developed to induce competition in an inherent monopoly is interesting. The British Government has established a strong, three-pronged regulatory framework as follows: (1) price and service-the Office of Water Services, (2) drinking water - the Drinking Water Inspectorate, (3) environment- the National Rivers Authority. Price and Service The Director General (DO) of Water Services, supported by the Office of Water Services (Ofwat), has the challenging task of regulating the prices the pie's can charge, so that they adequately manage their assets in the long term, and also of monitoring the level of service to customers. The DO sets the annual price increase for each pie, being the retail price index + K, where K (a factor varying between 3 and 70Jo for the 10 pie's) allows for the necessary investment and service to improve all aspects of performance. This represents an investment of $A65 billion over ten years! It also represents a substantial price rise to the water consumer and user of sewerage services. Water Quality The Drinking Water Inspectorate (DWI) ensures that quality of supply is maintained . It ensures that EEC directives for drinking water are met. Environment The National Rivers Authority (NRA), separated out from the former water authorities, regulates general environmental performance and water resource management. It grants the consents to the pie's and monitors most aspects of the water environment, including compliance with some EEC directives. It also manages catchments including those of reservoirs. This national experiment will be watched closely. It is noticeable that the pie's tend to be smaller than Australian water and sewage

authorities and the NRA bigger than our environmental agencies and water resource managers taken together. (The NRA has 6500 staff for England.) Of course there are real physical differences in the water situation in Australia and the UK which account for some of this difference.

SOME FEATURES OF THE 'REVOLUTION' Privatisation The focus of both the pie's and the corresponding regional offices of the NRA seems to have sharpened considerably since their separation. The pie's have concentrated on the business activity of water supply and sewage treatment against a set of criteria which had been substantially defined at flotation, but which are still subject to some development, noticeably as a result of new EEC directives such as that prohibiting sludge disposal to the sea . Their debts were written off by the Government at flotation and they were given a cash injection. Against this they need to make heavy investments in infra-structure modernisation and upgrading to meet environmental and service demands . Some have diversified into operations such as solid waste management and heavy engineering, although the share market has not necessarily smiled on these 'noncore' ventures. They are not under political control, the three regulatory bodies above providing the constraints within which they must pay a dividend and remain viable. The pie's are thrusting towards universal metering (at present only 240Jo ), but there is resistance from public interest groups which see it as being regressive for lower socio-economic groups. There is also concern that the pie's may become intent solely on satisfying the regulators, Ofwat, the DWI and the NRA, and so lose sight of their customers. Water Pollution Control The NRA is going through a review of all consent conditions, including those of pie's, and developi,ng a compliance policy under guidelines developed by a committee headed by David Kinnersley, the author of "Troubled Waters" and already known to some in Australia. The essence of the review is to bring the consent conditions in line with achievable reality on an annual statistical basis and to provide a basis for legal action on a single sample . These never-to-be-exceeded maxima (set at multiples of two or three times the 950Jole values) are a point of some contention and the pie's have all appealed against them. Our '3-day geometric means' set at the 980Jole level seem to achieve the same effect in a fairer way. The environmental performance of the previous all-purpose authorities had not been good. Some pie plants still have consents which would be considered quite relaxed by our requirements for secondary treatment. A noticeable tension has developed between the pie and the local region of the NRA, although in most cases the people concerned were former colleagues. The NRA has begun to prosecute the pie's, thus underscoring the arms-length relationship. There is little sharing of data, perhaps most starkly illustrated in Yorkshire where both the pie and the NRA are proceeding to develop separate telemetered monitoring systems with the same contractor, since the tendering operation had been commenced before separation. The NRA is also reviewing the method by which it classifies waters, generally adopting the two-component "beneficial use/ criteria" method, a variant of which is currently proposed for Australia and NSW. However, they do not appear to be proposing the same degree of public consultation and involvement at the catchment level as in Australia. Their review is prompted by the five-yearly review of all rivers being undertaken in 1990. The simplistic four-level classification system (like the old NSW system) used in the 1985 review is now seen to be inadequate. A significant difference from Australia is the apparent lack of a practical "non-degradation policy" and a reliance on technologybased effluent standards (BA TEA in our terms and BATNEEC in theirs) only in the case of the 23 "red-list" toxic substances specified by the EEC. A significant development will be the WATER February 1991

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introduction of an integrated system of pollution control involving Her Majesty's Inspectorate of Pollution (HMIP), targetting the 23 "red-list" compounds. A further significant difference between the NRA and Australian environmental and water management authorities is the amount of monitoring the former undertakes. Their knowledge of their water quality is generally an order of magnitude better than ours. The NRA regularly monitors all rivers and lakes and undertakes most effluent monitoring. This makes them a powerful monitoring and assessment force, backed by laboratory resources, electronic data management and telemetery.

THE ENVIRONMENTAL 'CLIMATE' Their water quality problems are rather different to those in Australia. They have combined sewer overflows, occasional serious oxygen depletion, rapidly flowing and cooler rivers and smaller upland water reservoirs than us. Their problems are oxygen 'sag' and fish kills, with algal blooms and eutrophication important in storage catchments and lakes, but less so in rivers. They probably have toxic contamination like us, but seem not to have looked very hard yet, especially for organochlorines, etc. Like us they have faecal pollution of beaches with lots of raw or screened sewage discharges still, despite what we hear about clean-ups! They appear to have a nutrient/ eutrophication problem, but largely confined to their reservoirs and lakes (blue-greens) but not in their rivers which tend to be relatively fast-flowing and colder than ours. Consequently nutrient removal at sewage treatment works, a priority area in Australia, is not one of their'notable skills. However, this may change as they move to reduce ammonia discharges from sewage treatment works, thus removing a source of inhibition to aquatic growth in rivers. They may then experience more algal blooms, a phenomenon which could be exacerbated if their summer temperatures continue to rise due to the 'Greenhouse' effect. Sludge disposal is a problem in Britain with the EEC banning of sea disposal and tough new restrictions on application to land. Most major methods are being actively developed: composting, land application, drying and land fill and incineration. Yorkshire Water has recently built two incinerators which can meet the tough new German emission standards for toxics and dioxins, another is approved and a further is planned. (One is in an industrial area of Sheffield.) Wessex and Thames Water are working on land application and composting systems. The message seems to be that it is unwise to rely on one method and a mix depending on circumstances will often be warranted. Fears and perceptions rather than real scientific evidence of risk appear to have had a major impact on the land-application and incineration routes in Europe .

THE POLITICAL "CLIMATE" The political environment is quite different from that in Australia. They have a single strong national government which basically runs the environment, but the EEC issues directives which they have to observe and which are giving them lots of trouble. (The Dutch, Scandinavians and Germans keep pushing through high standards in Brussels). We have seven major governments under a weaker Federal system, at least as regards the environment, which has hither to resulted in greater uncertainty in our actions at the national level. Their administrative structures for catchment management do not appear to be well developed. Public involvement seems minimal and the emphasis is on the physical skills of modelling and prediction. While we should be able to use the latter in Australia we may be able to offer our broader catchment management skills when we have them a stage further developed. One real advantage they do have in this area, however, is the existence of integrated responsibility for catchment management in the hands of one organisation, the NRA.

TECHNOLOGY TRANSFER The visit offered, not only the prospect of attracting to Australia relevant environmental, engineering and financial services to supplement our shortfall, but also the opportunity to see the British water industry at a critical phase of its development. The prospect of identifying opportunities for Australian firms in the UK was not forgotten . There is a need for major development and investment in water treatment as the EEC drinking water directives have their effect. The Australian processes of Sirofloc and Memtec have already made some inroads into the British market. 16

WATER February 1991

The strength of skill and industry related to water in Britain appears to be in water transport ani't' treatment, wastewater treatment, monitoring, electronic data management, scientific understanding, modelling and sewage 'by-product' reuse and disposal. However, their abilities may need some translation in application to an Australian situation because of both differences in geography and hydrology and in scale.

CONCLUSIONS The privatised British water industry could provide some interesting pointers for the Australian industry. Strong and comprehensive regulation is an essential component of privatisation if public interest and competition are to be maintained. Privatised British water supply and sewage authorities tend to be smaller on a head-for-head basis than their Australian counterparts while the environmental regulators/ resource managers are larger. In the water sphere integration of environmental and resource management is better, with the NRA controlling abstaction, discharge, catchment management and flood control. Integration across other pollution spheres tends to be simpler in Australia. Urban privatisation in Australia would be difficult because of the smaller size of our urbanised industry and because of the weaker regulatory capacity. Both limitations are due to the 'economy-ofscale' effect. Products, skills and services available as part of the British water industry could supplement the shortfall in Australia. However, Australian conditions would generally require some modification for British applications . There may be limited opportunities for Australians to do business with Britain. Environmental pressures in Britain have also risen noticeably in recent years, but often for different reasons than in Australia and finding different social expressions. Public participation does not appear to be the feature in the UK that it does in Australia and North America.

EDITOR'S NOTE: It is interesting to read this report in conjunction with the paper by Jack Jeffry in the June 1988 issue of water which foreshadowed some of these changes. '

LETTER TO J'HE EDITOR From Dr A.J. Priestley, Elsternwick, Vic. Bravo to Peter Hughes and his well-articulated discussion on environmental issues and the public perception of his column "It Seems to Me", Water, December, 1990. To my mind, the issues he raises are critical to this country's future well being and should be an important concern of the Association. At present both Federal and State governments are swimming in a sea of uncertainty when it comes to environmental issues. They are desperately looking for balanced and informed advice but, because virtually no politician has a technical background, they are unable to critically evaluate any advice they do receive. The possibilities for inappropriate decision making are thus large! Can the AWWA play any constructive role in preventing inappropriate decisions and helping to educate the general public on water related issues? In my view, if the Association is to have any wider relevance than simply serving the professional needs of its members then it should make some attempts to make its views heard in a wider forum. The Association could well be condemned to irrelevance if it stood idly by while politicians made far reaching and expensive decisions based on a simple knee-jerk reaction to public opinion. Having stated the above, I can see considerable difficulties in forming a representative Association view. Whilst we have amongst our ranks most professional working in the water field, they are all extremely busy with their own affairs and may not have the time to commit to such a major undertaking. Public education is also a formidable task, especially when the main information source for the public, the media, is more interested in sensationalism than education. However, the gravity of the situation is such that I believe the Association should give serious consideration to entering the field of public advice and education. Perhaps this topic could be debated in the columns of Water and even discussed at an after hours session of the Federal Conference.


Developments in Wastewater Management for Intensive Rural Industries A Review by K.H. BOWMER, P. LAUT and E.A. SWIN10N SUMMARY This review summarises the broad characteristics of wastewaters arising from present and projected intensive rural industries and the problems of environmentally satisfactory disposal. Current and developing treatment methods are summarised and required areas of research and investigation suggested.

INTRODUCTION This review has drawn primarily on one section of a Report, dated August 1990, "Waste Management in Intensive Rural Industries in Australia", commissioned by the Department of Primary Industries and Energy, and prepared by CSIRO Division of Water Resources with input on legislation from an officer of DPIE. · The objectives of that Report were to review current practices and identify those likely to degrade water and land resources, to review legislation, to summarise research and identify likely applications, and finally to recommend a range of options to maintain soil and water resources. The Report in full details many relevant statistics, strategies, and recommendations and is available in limited numbers from the Department of Primary Industries and Energy, Water Branch. A series of referenced essays will be published by CSIRO in their Water Resources Series. Large-scale intensive rural industries, with the exception of dairy processing and wine making, have played a relatively small role in Australian agriculture until the last 20 years. In the last ten years in particular, however, there has been a considerable development of large-scale production in the poultry, beef feedlot and piggery industries, as well as some re-location of agricultural processing activities, including abattoirs, meat processing, tannery and wool scouring plants closer to the livestock production regions. Processing of other products such as wood pulp, cereal and sugar processing is similarly situated in rural regions, often with limited or over-stressed water resources. Beef feedlotting has oscillated considerably since the first trials in the mid 1960s, but with the introduction of AUSMEAT registration in 1987, and Japanese involvement, it is likely that over a million head will be turned off such lots in coming years. This is only a small percentage of the total grass-fed industry, but it is highly concentrated and often involves its own meat processing facility. Piggeries have decreased in number, but have become more and more concentrated. Non-metropolitan abattoirs, meat processing, dairy processing and canneries are all significant contributors to surface and groundwater contamination, and forest product processing plants, including pulp mills, are almost universally located in rural areas. Some state water agencies are finding it necessary to impose stricter waste management controls. It is stressed that most waste treatment methods discussed here are currently in operation. However, it is often impossible, with present knowledge and data, to predict the consequences of these activities at particular sites and regions. The research and investigations suggested are to improve both the efficiency of these treatments and future management of all the resources involved.

REVIEW OF WASTE CONTAMINANTS Major constituents The seven major contaminants from waste and wastewater are organic load measured as biochemical oxygen demand (BOD), nitrogen (N), phosphorus (P), microorganisms (pathogens), salt, sludge and heavy metals. The relative importance of each of these varies with the nature of the effluent. All rural industry wastes, except irrigation wastewaters, contain substantial BOD, and N and P are important components. Salts are a problem in some irrigation waste waters and occur in animal excrement and blood, or as a result of using local waters which have a significant salt content for washing down or in processing. Organic residues such as sludge

Kath Bowmer is a - Senior Principal Research Scientist and leader of the 'pollution and conservation of surface water' program in CSJRO Division of Water Resources, Griffith Laboratory. She gained a BScfrom Nottingham University, UK in 1966, majoring in soil chemistry, plant physiology and environmental physics; and a PhD in 1969. She joined CSJRO Division of Irrigation Research in 1970.

Dr Kathleen Bowmer

Peter Laut is a Senior Principal Research Scientist in the CSIRO Division of Water Resources. He is a member of the resource management systems group. He has a BA Hons 1 and PhD in geography and joined the then Division of Land Research in 1973. His major research interest has been in computer based land evaluation techniques for a wide range of land uses including, rural industry waste disposal. Dr Peter Laut

Bob Swinton was a Principal Research Scientist in the CSJRO Division of Chemicals and Polymers, Water Technology Group, until his retirement. He is now active as a consultant in water/ wastewater treatment as well as being the Honorary Editor of "Water". are a major element of most waste sources, particularly from abattoirs, but are minimal in dairy factories where recovery of whey is practised; they occur as a separatable form (leather dust and hair) in tanneries; heavy metals are only imp&rtant as contaminants from piggeries and perhaps from tanneries. Other constituents Contaminants which may be important in specific industry effluents include: • Sulfate, which in anaerobic acid conditions can release toxic and odorous hydrogen sulfide. • Coloured, slowly-degrading organic compounds such as humic and fulvic acids which can react with chlorine during disinfection processes to produce toxic bi-products. • Boron, at concentrations which are toxic to crops in some irrigation waters. • Cadmium from phosphate fertilisers used in intensive agriculture and horticulture. • Bleaching compounds, detergents and chlorinated lignin products in pulp mill effluents. • Insecticides and anti-parasitic compounds.

GOVERNMENT GUIDELINES FOR EFFLUENT DISPOSAL Scientists and administrators associated with the management of intensive rural industry wastes have a clear appreciation of the implications of uncontrolled or poorly managed distribution of wastes on surface and groundwaters. Most states have published guidelines for waste management for at least piggeries and beef cattle feedlots and have legislation for the protection of water resources. The best of these guidelines demonstrate the calculations required to determine satisfactory loading rates for land disposal or lagoons. It is left to the individual industry operator to decide on the mix of techniques or methods to be used. However, whilst many guidelines indicate acceptable levels for each pollutant few suggest how these levels should be monitored nor by whom they should be monitored. In practice, it appears that most industry operators fail to understand the significance of poor waste management and try to WATER February 1991

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deny responsibility for the obvious consequences of past poor performance.

RECYCLING AND WASTE MINISATION It should be emphasised that for long-term economic reasons most rural industry wastes should be regarded as potential resources for subsequent use either into other commercial products, or for replacing fertilisers used in their production systems, with the potential for the water to be used for irrigation. Up to the present, rural industry waste management has tended to be considered a problem of disposal, with little or no treatfnent, to the immediate environment with little consideration of the long-term costs to other resources, especially water resources. Government policies which call for the allocation of these external costs back to industry will encourage the development of safer and more effective systems of waste management, but they are also likely to involve additional costs. There rs potential for at least some of these costs to be recouped by re-use in one form or another. Modification of processing techniques to minimise waste is potentially an important means of improving effluent quality in rural manufacturing activities such as tanneries and wool-scouring plants. Considerable progress has been made in both these industries ¡by the CSIRO Division of Wool Technology through more effective removal of hair from hides and more efficient use of detergents in wool scouring (SIROLIME and SIROSCOUR).

METHODS OF EFFLUENT DISPOSA.L Discharge to a water course

Unless the effluent has been treated to a very high degree, as discussed in later sections, this is a method to be avoided, particularly for the inland regions. However, the use of lagoons followed perhaps by a constructed wetland, may provide an environmentally satisfactory method for upgrading the effluent to the degree required. Application of effluents to the soil

In suitable locations, irrigation of effluent (and spreading of manure) is the most desirable method of waste treatment, especially where groundwaters are deep or can be maintained beneath the bottom of the root zone, i.e. more than 2 m deep. Advantages include the opportunity for recovery of resources, maintenance of soil structure and fertility by recycling of organic matter and reduced costs compared with conventional or advanced treatment methods. Site selection: The choice of location is central to the successful land application of effluents if surface and groundwaters are to be adequately protected from pollution. Site selection and waste management are especially important both in areas of highly permeable soils with rising groundwater tables or in areas of heavy clay. In the permeable soils nitrogen and phosphorus rapidly move below the root zone, where these nutrients should be taken up, to the groundwater. Where groundwaters come to the surface, or reach surface waters as in the Peel-Harvey estuary, the potential for toxic algal bloom development in surface waters is high. On the other hand, clays can become waterlogged and create noxious surface ponds especially where the BOD of the effluent is high. The widespread use of flood, spray and trickle irrigation by Australian rural industries reflects its economic attractiveness. However, there is a need to maintain high levels of design in relation to site or environmental factors, and day to day management. The essence of successful irrigation in relation to groundwater protection is application at rates which enable evaporation and evapotranspiration to cope with nearly all the waste water and for the plants to use the available nutrients. Developments: While general guidelines on suitable soil type and effluent loading are available there is no logical approach to assessing the vulnerability of groundwater to pollution, which depends on the complex interaction of various factors of soil, geology and aquifer depth. A simplified regional groundwater hazard prediction system, DRASTIC, adapted from the US EPA has been used to map potential groundwater pollution hazard in the Swan Coastal Plain (WA). The same technique will be used in northern New South Wales and should be readily adaptable to map regional groundwater hazard and to predict the effects of intensive rural industries, to assess vulnerable aquifers and to select the safest sites for rural industry development. Irrigation scheduling: For sustained irrigation the application of water (including wastewaters) must be balanced with evapotranspiration. It requires a small net downward movement of water 18

WATER February 1991

(the leaching fraction) to keep soil salts be~w the crop root zone. Unfortunately, even with efficient irrigation scheduling, these salts and any associated nitrates may reach the groundwater or move laterally to depressions in the landscape. Sustained production can only be maintained in the long-term by careful management of water, salt and nutrients. Developments: Irrigation scheduling methods have been developed to maintain water balance in irrigation areas (ET FLUX and WATSAL, South Australian Department of Agriculture), and management of selected crops, e.g. wheat (SIRAGCROP: CSIRO Divisions of Water Resources and Plant Industry), pine trees (CSIRO Division of Forestry) and different eucalypt species (Department of Conservation and Environment, Victoria). In Australia these methods have been applied largely to crops in existing irrigation areas, using irrigation supply and drainage waters. Extension to include effluents from intensiye rural industries, and application to other crops such as lucerne, woodlots and hardwood forests is now needed. Use of neutron probe technology to trace water movement in the profile has been available for many years, but this agronomic technique is not yet being applied to waste management in intensive rural industries. 'Trickle irrigation methods for trees shrubs and vines on sandier soils is not new, but may require adaptation for most wastewaters because of problems of blockage by solids and algal growth. The use of seepage trenches rather than flood or spray irrigation usually requires a fairly flat topography to ensure even spreading. For undulating or hilly landscapes, optimal siting of seepage trenches for sewage disposal has been successfully demonstrated near Canberra using topographic analysis of the terrain (TOPOG, CSIRO Division of Water Resources), and this has potential application for any intensive rural industry sited in such landscapes. Nutrient application: This must be balanced by crop uptake and harvest if nutrient hotspots and groundwater pollution are to be avoided. However there have been few integrated water and nutrient studies. Several woodlots have been established to dispose of irrigation water drainage or winery effluent in the Mildura area, but most are unmonitored . Developments: An exception is the work .of the Department of Agriculture, South Australia, at Loxton where cannery effluent is being used to irrigate eucalypt species. CSIRO Division of Forestry has studied nutrient balance of pines irrigated with nutrientenriched water near Canberra. In South Australia, municipal sewage effluent from Bolivar is being used in recently-established trials on hardwoods. Uptake of nutrients by seven tree crops treated with municipal sewage was investigated in Wodonga by the Department of Conservation and Environment, Victoria, and the AlburyWodonga Development Corporation. Woodlot disposal is being investigated by the NSW PWD at Branxton and at Wagga Wagga. A collaborative project between the NSW Public Works Department and the CSIRO Division of Forestry to use abattoir effluent on woodlots is underway at Blainey. All these studies give useful background information, but demonstrations and nutrient balance studies are required for crops and trees in different climates and soils irrigated specifically with rural industry effluent. This will require expertise from a variety of disciplines including agronomy, crop nutrition, forestry, soil science, irrigation engineering, groundwater hydrology, and aquatic ecology. More research is required into the transport and biological effects of organic forms of phosphorus. The fate of inorganic phosphorus for fertilisers has been well studied, and it is well known that adsorption onto clays and precipitation as insoluble iron phosphates will capture most of the phosphorus at the soil surface. However, organic forms of phosphorus from sewage and rural industry effluent may more readily run-off or leach to groundwater. Inorganic -phosphorus might also be solubilised from soil and sediments in the anaerobic conditions created by application of effluents with a high biochemical oxygen demand. Salt management: This is a special problem which needs new research. While the continued application of sodium-dominant effluents to land usually results in loss of soil structure and fertility, the different cation balance of some effluents may be a redeeming feature. For example, winery and piggery effluents are highly saline but are enriched with potassium. Potassium is exchanged on soil clays in preference to other cations, keeping the clay flocculated and maintaining good soil structure and permeability. The effects of sodium and low pH on clay soils can of course be counteracted by addition of calcium compounds.


Developments-. Gypsum and lime slotting is being used by CSIRO Division of Water Resources and Gerard Cassegrain & Co. Pty Ltd of Port Macquarie for incorporation of lime into acid vineyard soils. The use of mole drains under stabilised gypsum slots is to be investigated on heavy poorly-drained soils near Griffith, New South Wales. Gypsum and lime slotting methods may be useful for draining heavier soils, incorporation of slurries or solid manure, and use of the soil for rapid filtration and disinfection, but the methods are as yet untested for treatment of rural industry effluents and waste.

METHODS OF EFFLUENT TREATMENT Most rural industry effluents require some form of treatment before they can be disharged. Excessive biochemical oxygen demand must be removed before land application or storage in oxidation ponds to avoid odours produced by sulphur compounds and fermentation products. Clarification may be required for spray or trickle irrigation, though not for flood or trench irrigation. Treatment to a high degree which may have to include significant reduction of N and P is necessary before discharge to a water course. Lagoons Oxidation lagoons are traditionally very effective for slow reduction in BOD and pathogens in low-strength effluents. If adequate suitable land is available, a series of unstirred lagoons can be based on proven designs. If land cost is too significant, the design of floating aerators is also a well-established technology. For high strength effluents, aeration of the initial stage becomes uneconomic, and a series of anaerobic, facultative and aerobic lagoons can be adopted. Anaerobic lagoons efficiently remove BOD by microbiological generation of carbon dioxide and methane but they can be difficult to start up, and require a degree of biological expertise which is unlikely to be available in all rural industry enterprises especially those of small-scale. However, well-designed ponds, once established, require very little operational maintenance or skill, beyond that required to maintain the effluent load within design limits, and particularly to avoid overloading and toxic materials. Developments: The University of Melbourne Department of Microbiology and CSIRO Division of Chemicals and Polymers have expertise on relevant microbial physiology. The huge lagoon systems at Werribee, which treat Melbourne sewage, are well-established and the know-how could be transferred to rural industry managers or consultants. Research is currently in progress to enhance the nitrogen removal capability of such lagoons. The origin of odour, and its control in anaerobic ponds by selective aeration of the surface of the pond is being studied at the University of New South Wales Centre for Wastewater Treatment, and is also being applied by the Melbourne Board to the Werribee lagoons. Anaerobic Digesters The slowly-mixed anaerobic digester is, of course, used to reduce BOD and stabilise many high strength wastes, producing a sludge with potential for soil improvement, and an effluent which is often suitable for direct irrigation, which can certainly be further treated by oxidative techniques, and which may be acceptable by the local municipal treatment plant. Developments: A recent cost-effective variant is the replacement of steel tanks and gas holders by a huge flexible bag such as is being operated at McCains potato processing plant at Ballarat. More advanced systems for anaerobic treatment of high strength wastes utilise continuous digesters, with either fixed films or suspended beds to maintain the required population of anaerobic biomass. This is an imported proprietary technology which seems to have good potential. The microbiology is being further explored by the CSIRO Division of Chemicals and Polymers, the process control by the University of Queensland, Department of Chemical Engineering, and a few installations are already being operated by some larger food industry enterprises. Conventional Sewage plants Conventional activated sludge or trickling filter treatment systems used for municipal sewage reduce BOD effectively but do not normally remove N and P to low levels. Consequently for the treatment of intensive rural industry wastes they would have to constitute the first stage only of a hybrid system which would finish with land disposal (spray irrigation), or passage through constructed wetlands prior to discharge to surface water or water re-use.

Developments-. Conventional sewage treatment can be augmented by chemical precipitation to remove phosptorus, but this requires the constant supply of either lime, alum or iron salts. Advanced treatment processes Advanced treatment processes require slightly higher levels of capital investment, but demand a much higher level of operational skills. They offer decided cost advantages for removal of BOD, N and P. Thus they have considerable potential for all intensive rural industries especially those located in near-urban environments. It seems likely that the scale of operations of feedlots and piggeries will continue to increase and the cost of land acquisition and waste transport may eventually require abandonment of land disposal methods in favour of a range of advanced treatment processes. Advanced biological treatment for nitrogen removal involves an aerobic stage to convert the ammonia and other nitrogen compounds to nitrates, followed by a reducing stage where the nitrate is converted to nitrogen gas. A variant is to alternate the aerobic and anaerobic conditions in the one tank by switching the aeration on and off. Termed the AAA process this was developed by CSIRO Division of Chemicals and Polymers and is being applied successfully for sewage treatment in Melbourne. Biological removal of phosphorus requires a more complex series of anaerobic, anoxic and aerobic regimes, with controlled recycle streams, but it is now being applied at a number of municipal plants in inland areas, some of which rely on the input of a waste stream from local food processing plants to modify the characteristics of the wastewater to enhance phosphorus removal. The seasonality of some plants can however, be a deterrent to such integrated systems. The CSIRO Division of Chemicals and Polymers have a continuing interest in this system, together with many consultants and University departments. Advanced methods are also being investigated for treatment of sludge, and urban runoff water. Most of these methods are theoretically applicable to rural industry wastes, but will be far more expensive than current methods of land irrigation. However, non-availability or cost of suitable land, increased monitoring of soil and water qualit,Y, and the imposition of large 'pollution bonds' may reduce the cost difference in the future. Such highly efficient advanced treatment plants could promote regional and local concentration of, intensive rural industries by making available large scale central plants for treatment of their wastes, together with the collateral domestic sewage, with the potential for recycling phosphorus and organic matter. Wetlands, natural and constructed

Low-rate systems So far, wetlands have been investigated mainly for treatment of treated municipal sewage and urban runoff. These can be dealt with in so-called 'low rate' systems which are large artificial marshes and ponds with sediments and free water, with value as a habitat for wetland birds. A manual of operation for such systems has been produced recently by Professor Peter Cullen and others of the University of Canberra for the ACT Administration Interim Territory Planning Authority. Full scale systems are being tried in Canberra and by the Sydney Water Board in the Blue Mountains.

High-rate constructed wetlands These include the surface-flow 'reed-bed' systems developed in Europe with varying success, and being investigated at Frankston, Victoria, by the Chisholm Campus of Monash University. Most, however, are based on lined pits containing gravel in which emergent aquatic plants are grown. Many groups have worked on 'trench-style' systems but although they yield a clear effluent, and remove BOD in much the same way as a trickling filter, they do not appear to be efficient in removing nitrogen, and have very little effect on phosphorus. Vertical flow systems have been patented by CSIRO Division of Water Resources, which ensure that the flow passes through the root zone of the growing plants. They reduce BOD, N and P to fairly low levels, and may effectively remove bacteria and pathogens. The initial CSIRO tests were conducted on a small scale. Large scale demonstration and trial systems for municipal sewage have been built at Coffs Harbour Uoint CSIRO and Gerard Cassegrain Pty.Ltd.) and Wagga Wagga. Units suitable for single households are being tested at several locations around the country. WATER February 1991

19


Intensive rural industries and industry consultants have shown considerable interest in high-rate constructed wetland research and a constructed wetland is being built to treat part of the effluent from a piggery near Forbes. The volume of gravel required to treat each equivalent person (EP) is about 3-4 m 3 , making this method expensive for effluents of high biochemical oxygen demand. However, by coupling constructed wetlands with anaerobic ponds or digestors to lower initial BODs, constructed wetlands could be effective as part of a hybrid effluent treatment system for some intensive rural industries. For example, low BOD abattoir effluents would be more suitable for this type of treatment than wastewater from piggeries and feedlots. AWRAC has provided partnership funds to the Murray-Darling Freshwater Research Centre and the CSIRO Division of Water Resources for strategic research designed to understand and optimise system performance-that is the chemical, microbiological and plant processes controlling nutrient removal and oxygenation in constructed wetlands. However, both strategic and demonstration work is required, and a major difficulty is a current lack of capital to build large scale operational systems. Only when such systems have been constructed and their capabilities proven in a variety of physical environments .will rural industry enterprises risk investment in them. Module-style construction may allow treatment of a proportion of the effluent from an enterprise for demonstration and test purposes. Further modules could then be added as performance is proven, or to . increase performance if it proves to be inadequate, or to accommodate growth of the industry.

MANAGEMENT AND CONTROL Monitoring methods Cheap, reliable intelligent monitoring methods and data communication systems need to be developed for effective catchment management. • Overseas and Australian experience has shown that uncontrolled releases of effluents can pose substantial local and regional threats to ground and surface water qualities. • There is insufficient understanding of the processes linking land use and water quality to mathematically model and predict the effects of effluent releases. • Without the development of new labour-saving measurement and communication systems the costs of monitoring will be prohibitive, both to state agencies and to rural industry developers. Monitoring methods include collection of data on nutrient loads and concentrations and other water quality parameters such as salinity, temperature and oxygen. New sensors are being developed by the Chisholm Campus of Monash University, the University of Canberra and CSIRO Division of Water Resources. CSIRO has also developed remotely controlled satellite-linked data collection and transfer. Since many regulating and monitoring authorities have an interest in this technology (e.g. the Engineering and Water Supply Department of South Australia who have an AWRAC partnership project with CSIRO Division of Water Resources), there may be a possibility of syndicated funding for further development for intensive rural industry. Nutrient sensors still require considerable research development. Potentially 'dirty' effluents may also pose some special analytical problems in sensor development. Stable isotopic tracers may also be useful to trace pollutants. CSIRO Division of Water Resources with NSW Department of Water Resources and The Murray Darling Basin Commission is currently investigating the prospects for separating different phosphorus sources (fertiliser, sewage and natural rock phosphorus) in river water. The use of organic biomarkers such as coprostanol, a tracer in sewage, is well developed overseas, and could be used in Australia to investigate the impact and travel time of a sewage discharge downstream in a river. Further research is necessary to extend this method to identify specific rural industry effluents entering surface water or groundwater on the basis of, say, the digestion products of the animals' characteristic food source. The appropriate technology (gas chromatography-mass spectrometry) is becoming more readily available in major laboratories. Regional resources management and response of the aquatic environment If a policy of limited discharge is adopted, whether for intensive rural industry, flushing of salt from the landscape, or discharge to rivers of treated sewage, then an understanding .of the response 20

WATER February 1991

of the aquatic environment is critical. This includes both basic research into ecosystem and habitat performance as well as the development of methods to establish acceptable levels of key water quality parameters in streams, catchments and groundwater resources that receive discharge of wastewaters. Processes of nutrient cycling in surface waters, and prediction of algal blooms is being studied by many groups. Notably these include the University of Canberra, Chisholm Campus of Monash University, Murdoch University, The University of Western Australia, The Murray-Darling Freshwater Research Centre and the CSIRO Division of Water Resources. Most of the research is strategic and investigates processes occurring 'in-stream'. The specific effects of sewage or rural industry discharge on water quality appears to have been largely neglected . One exception is a series of studies on sewage effects on alpine streams by the University of Canberra. A valuable knowledge base is being built up by the MurrayDarling Freshwater Research Centre at Albury-Wodonga on the limnological interactions of billabongs and rivers, nutrient cycling processes, and the role of turbidity and suspended particles in changing the biological availability of phosphorus. The production of tastes, odours and toxins by blue-green algae (cyanobacteria) is being investigated at CSIRO Division of Water Resources, the University of New England, and the State Water Laboratory, South Australia. There are important ecological, aesthetic, public and animal health implications of algal blooms now occurring in many of Australia's inland and coastal waters. This basic understanding of aquatic ecosystems needs to be improved and extended, otherwise small and incremental additions of nutrients to surface water might lead to complete disruption of aquatic ecosystems and catastrophic toxic algal blooms. Decision support systems If 'no discharge' policies are to be maintained monitoring and active supervision will be required on a site, near-site and regional basis. If 'limited discharge' policies are allowed a more complex administrative capacity will be required as ~ell. Acceptable levels of stream and groundwater quality will have to be determined for catchments and sub catchments. Whichever of these discharge policies is applied, there is a clear need for supervisory systems, monitoring and data communicatio~ tools (see above). These will be required to operate at both local site-specific and regional scales, to help individual and regional resource managers maintain acceptable levels of land and water quality. There is also a need for the development of computer-based decision support systems to allow managers to utilise this information rationally and in accordance with government policies. Decision support systems are potentially useful to determine: • The optimum siting of intensive rural industry activities. • The consequences of adding new operations within a catchment on downstream water quality. • The effects of improving waste management procedures in older operations. • The best choice of treatment options for a given industry-site combination. Use of these computer-based systems is already being developed to aid catchment management in the Onkaparinga (South Australia) and Peel Harvey (Western Australia) catchments. CSIRO Divisions of Water Resources and Soils both contribute to this research area. These decision aids would be useful to individual industry managers as well as to regulatory and catchment monitoring authorities. Appropriate research leadership and computer systems are already available, or are close to being developed, but more human resources and research support will be required to extend these tools to rural industry problems. It may well be that when these external costs of waste management are taken into account, locations for low level waste management operations will be limited to a few favoured regions where climate, soils, topography and drainage are capable of absorbing the pollutants. On the other hand, advanced waste management techniques would contain these costs internally and provide greater freedom of location.

RECOMMENDATIONS Further research or development is required in a number of interrelated areas:


• assessing the most appropriate waste disposal sites for new industries · • economic and environmental analysis of all of the options for waste management. A manual or guide for choice of location and waste system requirements containing principles of operation should be available for developers and consultants. • concentration of industries, allowing economy of scale, and permitting more sophisticated cooperative waste management strategies. and prospects for mixing effluents to obtain a better balance for land application or other treatment. • investigation of new or improved methods of treatment or recycling. • development of cheaper, more reliable monitoring methods involving satellite communication, development of sensors and availability of data to the individual rural industry manager. The use of biomarkers and isotopic tracing should be developed for purposes of regulation and more accurate assessment of pollution sources. • methods for ameliorating existing problems are available but need further development and field testing. • basic research in aquatic ecology and habitat conservation must continue.

CONCLUSIONS Australia has a good base of research skills relevant to waste management in rural industries. These include irrigation, forestry, soils, limnology, hydrology, chemical engineering and computerbased management systems. Such knowledge and facilities could contribute to the development of sustainable intensive rural industries and associated communities by improving waste management and recovery of resources. However, most of the research skills are scattered, and are not specifically applied to rural industries. At present advanced processes are mainly used in municipal sewage treatment. Application of effluents to land is preferred where high volumes of concentrated effluent are produced, as in feedlots and piggeries. More sophisticated treatment processes may be appropriate for closely controlled industries such as wineries, food processing and tanneries. In the past land application has often been regarded as a cheap option for disposal of intensive rural industry wastes. In the future, adequate environmental safeguards, monitoring costs and application of large pollution bonds may make irrigation and land application of wastes more expensive and sophisticated. It is likely that only a small proportion of the extra costs will be recaptured by recycling of water resources or sale of reclaimed nutrients and organic matter.

Research Groups Relevant to Wastewater Disposal from Intensive Rural Industries A brief summary of projects relevant to the problems follows. It is divided into five groups, to demonstrate applicability to various forms of waste management. Note that some projects overlap into more than one group. CSIRO, Various Divisions Group A-Generic research related to land disposal Crop-water balance Evaluation of regional groundwater hazard Forest uptake of nutrients Groundwater distribution modelling Gypsum slotting and land filtration In situ monitoring Irrigation scheduling Nutrient balance Soils capacity to absorb heavy metals Soils classification Soils drainage, nutrient movement TOPOG Use of organisms to disperse animal faeces

Group B- Generic research related to constructed wetlands Nutrient removal and wastewater treatment in constructed wetlands (high rate systems) Design, development and commercialisation

Group C-Strategic research for high BOD waste treatment Physiology of methanogenesis to reduce BOD Processes in constructed wetlands Design and development of constructed wetlands Advanced treatment processes

Group D- Strategic research for improving land use/water quality relationships Decision support systems Gypsum slotting In situ monitoring Identification of pollutant sources using isotopes Use of biomarkers Movement of effluent and salts through the soil Soils capacity to absorb heavy metals Soils classification for waste management TOPOG Biological remediation of high -nitrate groundwater Limnology and aquatic ecology

Group E-Research into novel methods of treatment Gypsum slotting and land filtration Improving the quality of tanning effluents Increasing the effectiveness of wool scouring

Physiology of microbes for nutrient removal Nutrient removal in constructed wetlands Development and commercialisation of constructed wetlands Advanced treatment processes

Short list of non-CSIRO Research and Development Groups This short-list is not comprehensive. It is intended to give an indication of the scope of research and development, and its spread across agencies and higher education establishments. Group A- Generic research related to land disposal Crop water balance Neutron Probe Consultants Pty Ltd, Narrabri Departments of Agriculture in each State - University of Melbourne, School of Agriculture and Forestry (water use by trees) Evaluation of regional groundwater hazard University of New South Wales, Centre for Groundwater Management and Hydrogeology (for pesticides) Forest uptake of nutrients Forest Science Consultancy, Weston NSW South Australian Department of Agriculture at Loxton (boron rich drainage water, industry waste) Engineering and Water Supply Department South Australia (sewage) Wodonga City Council (sewage, industry waste) In situ monitoring - Monash University, Chisholm Campus - University of Canberra Soils capacity to absorb heavy metals - NSW Department of Agriculture (sewage sludge)

Group B- Generic research related to constructed wetlands Low rate wetlands - University of Canberra (for urban runoff)

High rate wetlands Sydney Water Board Byron Shire Council; Public Works Dept, NSW, and others Monash University, Chisholm Centre for Stream Ecology Murdoch University University of Western Sydney, Richmond Campus

Group C-Stra.tegic research for high BOD Waste treatment Physiology of microbes - University of Melbourne, Dept of Microbiology Surface aeration of anaerobic ponds for odour control - University of NSW Centre for Wastewater Treatment Characterisation and control of odour University of NSW-Fibre Science and Technology

Group D- Improvement of land use/ water quality relationship Limnology and aquatic ecology State Water Authorities University of Canberra Monash University, Chisholm Centre of Stream Ecology Murdoch University University of Western Australia University of New England Nutrient cycling and prediction of algal blooms Victoria, Rural Water Commission South Australia, Engineering and Water Supply Dept. (use of organisms as indicators of pollution)

Group E-Novel methods of treatment Physiology of microbes for nutrient removal Advanced Treatment Processes (BNR) Monash University Latrobe University, Bendigo College - Various Consultant Groups.

WATER February 1991

21


Zero Discharge From Chemical Plants A Report by Bob Swinton In collaboration with: LINDSAY REX (Exxon Chemical Aust. Ltd), JIM CLEMENTS and KATE McKIE (Commercial Polymers Pty Ltd), ANDREW LIPKEWYCZ (Dow Chemical Aust. Ltd) .

Mr. Geoffrey Norris, Australian General Manager, explains the long-term interests of Dow Chemical Company in the community and the environment. Also on the platform: Mr. Noel Williams, Dow Australia O!lerations Director, with Mrs. Hawke and Mrs. Kirner.

SUMMARY For 30-40 years the major chemical companies of the Altona complex, Victoria, have operated on-site treatment plants and discharged their treated effluents, under EPA licence, to a creek which flows into Port Phillip Bay. The majority of these companies are now connected to new sewers so that their treated effluents now flow to the Werribee treatment system. However, two companies have elected to discharge their treated effluent to adjacent blocks of land, thus putting zero discharge into effect. A third company supplies a proportion of its effluent to a local golf course.

INTRODUCTION In the 1950s the commissioning of the expanded petroleum refinery, Petroleum Refineries (Aust) Ltd (PRA), in Altona, Victoria, some ten kilometres to the southwest of the city of Melbourne, was followed by the development of the Altona Chemical Complex. This is tJ-\e largest production centre for petrochemicals, synthetic rubbers and plastics in Australia. It comprises seven companies, operating independently, but sharing raw materials and services. In the initial stages, the wastewaters and contaminated run-off from the refinery and the seven companies were treated by on-site facilities and then discharged under license from the Board of Works to Kororoit Creek, a small tidal creek which discharged into an arm of Port Phillip Bay. With the advent of increased concern for the environment and the formation of the Victorian Environmental Protection Authority in 1970, these discharges became subject to EPA licence and monitoring. Although the water quality of the effluents generally met requirements there was evidence of further damage to the biota of the creek, which was already polluted as a result of upstream urban development. The EPA also instituted the policy of reducing and, if possible, eliminating even treated industrial discharges to creeks and the Bay, favouring the use of the Board of Works sewer system.

SEWER CONNECTIONS Discussions between the companies and the government authorities commenced, and these have culminated in the connection of most of the companies of the Altona complex to the Western Outfall Sewer, which flows to the Melbourne Board's treatment system at Werribee. In 1988, BASF Australia Ltd constructed a l km long outfall, to cope with less than 5 L/ s, which connected with a Board reticulation sewer serving various factories to the north of the Complex, but the capacity of that system was far less than was needed for the remainder of the Complex companies. In 1990 a shared private main, about l km long, connected the outfalls of the on-site pre-treatment systems of four companies to a new Board rising main, (2.5 km long, 300 mm nominal diameter, constructed in HOBAS). The total cost, shared between the Board and the connected companies, Altona Petrochemical Company Ltd (APC), Australian Synthetic Rubber Company Ltd (ASR), BF Goodrich Chemical Ltd (BFG), and Hoechst Australia Ltd (HAL), was around $1.5M. Current approximate estimates for inflows are: APC 40 Lis, ASR 15 Lis, BFG 15 Lis, HAL 15 Lis. The oil refinery, PRA, has successfully operated a system of onsite treatment and final outfall to Kororoit Creek since its inception. The treatment consists of oil separation, dissolved air flotation, and large aerated lagoons. Effluent and stormwater holding ponds manage peak flows and high strength wastes. Phenolic wastes, for example, are diverted to pondage for biological degradation using specific mutant bacteria. In March 1991, however, PRA will connect to another new Board sewer, with a maximum discharge rate of 80 L/s. With these and the land disposal developments outlined below, discharge of water from the Complex to Kororoit Creek through the old effluent system will only be used for rare peak storm 22

WATER February 1991

A two-year project by Dow Australia to achieve zero discharge of all wastewater by means of an irrigated tree plantation was officially opened by Mrs. Hazel Hawke, Patron of Greening Australia, in November 1990. Mrs. Hawke unveiled a bronze plaque, then joined Mrs. Kirner, Premier of Victoria, in ceremonially planting a pair of native trees. The ceremony was attended by members of both the city and the local community, including scores of Altona school children who will be those who will appreciate the trees when they are fully grown. conditions. Discharges to the Board sewer must conform with the Board's Trade Waste policies and charges which encourage on-site pretreatment of industrial wastes.

RE-USE The Board and the EPA also encourage re-use of wastewaters. One of the Complex companies had long supplied a portion of its effluent to irrigate the local golf club, and during the discussion period two companies with relatively small wastewater flows elected, instead of sewer connection, to go for ]anti disposal of their total effluent, that is, to go for zero discharge.

LAND DISPOSAL ,

The recent inauguration of the urban tree plantation by Dow Chemical Aust. Ltd for the whole of their wastewater is the latest development (see box), but this had been preceded by a partial reuse scheme by Altona Petrochemical Company Ltd in 1981, and a zero discharge system developed by Commercial Polymers, in 1983, (when it was known as Union Carbide Aust. Ltd). Altona Petrochemical Company Ltd

Since the 1970s, APC have supplied the Kooringal Golf Course at Altona with recycled water by a 5.7 km pipeline, 90 mm diameter, with a capacity of 2.8 Lis. In 1990, APC and the Golf Club upgraded the pipeline to 100/150 mm diameter with a larger pump to give a capacity of 15 Lis. The water is stored in a dam on the course. It is the product of the on-site treatment system at APC and has an average salinity of around 600 mg/ L. It is especially useful in the summer months, and the estimated average consumption for about 25 ha of fairways, greens and tree planting irrigation is about 8 L/ s. Although not a major portion of the total flow from APC it represents a very satisfactory and useful water conservation activity which benefits the local community, and reduces the hydraulic load to the Board of Works system. Commercial Polymers Pty Ltd

In 1983, this company decided to implement a land disposal system rather than install tertiary treatment prior to discharge to the creek, or wait, and pay, for connection to the Board of Works' sewer. (McKie, Clements & Gaskell, ¡ 1990) The plant produces polyethylene only, and the wastewater is of relatively high quality. An active water conservation program ensured a relatively low volume and there was 37 ha of suitable land adjacent to the plant owned by the company. About 6 to 7 L/ s of wastewater from the manufacturing process is balanced in a 24 hour retention tank, mixed with septic waste from the domestic system, and treated in oxidation channels, fitted with rotary aerators. After clarification, the effluent is chlorinated.


Approximately 700/o of the effluent is then used for plant cooling, as makeup to the cooling towers. It was found by the experience of the first three years' operation that the effluent should be filtered before addition to the cooling circuit. Three-layer mixed-media filters reduce TSS (which is mainly organic) from 10-25 mg/ L down to 4 mg/ L. A side-stream filter is also used. Run-off from the winter rains accumulated in the storage dam is also used as makeup. Treated effluent not used for cooling is disposed of to land. In 1989, this accounted for an average of 2.7 L/ s. A 50 ML storage dam, covering about 5 ha (ie 1 m average depth) holds both treated . plant effluent and irrigation site run-off, (the design was based on the 90th percentile of the rainfall for the area). The dam, which is landscaped and has been named Lake Clements, carries a wide variety of bird species, and is being trialstocked with perch. Due to evaporation, the dam water is more saline than the original plant effluent. Table 1 compares samples taken in early 1990, (i.e. during summer) The lower N and P values are probably due to uptake by algae and macrophytes. Table 1. Compol Wastewater Quality Parameter

BOD

ss

E .Coli per 100 mL

TDS Nitrate TKN

TP Na Ca Mg SA Ratio

Dam Return*

Treated Effluent*

5 19 30

16 10

620 1.4 2.0 0.5 169 13 16

7.4

Dow Chemical Australia Ltd

This company produces polystyrene latex and polyester resins. When the plant was established in 1959, Dow also purchased a 52 ha site, across the road from the plant, and retained it as horse agistment until the present. When the company made the decision to opt for zero discharge rather than sewer connection, it decided to develop the urban forest concept, using a sophisticated system of irrigation control to manage a plantation of more than 50 000 native trees. Process effluents, boiler condensate, domestic septic effluent and site run-off are combined and treated in the existing on-site biological treatment plant and finally chlorinated. Currently a flow of 150 ML/a, or 5 Lis, is pumped across the road to a 65 ML storage dam, which has been constructed with raised earth embankments. Perimeter drains intercept all site run-off and feed to a 15 ML dam, which has been scooped out at the lowest part of the site, the water being pumped back to the main dam. This combined capacity buffers the balance of natural rainfall, plant effluent and the estimated requirement for irrigation of the trees, (Figure 1). Currently some 42 000 trees have been planted in the main plantation, over 24 ha. A further 8000 trees are planted in boundary strips, totalling 4 ha. The remaining 20 ha are still in grass.

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20

7 3.4

Irrigation The site characteristics have been outlined by Healey (1984). The soil is predominantly basaltic and the average rainfall is 597 mm per annum. The effluent water has a low salinity of around 250 mg / L, with an SAR generally less than 2.5, thus presenting no problem. The loading rates for all significant parameters, including heavy metals, are well within the recommended maxima. Initially 5.6 ha were fitted with 12 sprinklers of capacity 1 Lis with sprays along the walls of the holding dam to establish grass stabilisation. Later, a 5 ha flood irrigation system was established as a back-up. Currently a total of 93 sprinklers is in use. Another header waters an urban forest which now has over 3000 trees of several varieties. The forest serves to reduce spray drift and provide a pleasant visual barrier. Apart from the trees, the irrigation is to about 25 ha of grass, which is currently being grazed by a flock of 150-200 sheep. Soil and water quality The soil is monitored twice yearly,and compared with unirrigated soil. There have been no significant differences in pH or TKN. Zinc and chromium are in the same ranges as urban Melbourne background levels, well below contaminated site criteria. The fish are also being monitored for heavy metals. The only metal of significance is mercury, which, at 0.33 mg/ kg, is less than the NHMRC standard of 0.5 mg/kg, and is comparable with that in fish from the Goulburn River and the Gippsland Lakes. Economics The system of zero discharge has been in operation since 1983 and has proved to be economically beneficial as well as environmentally desirable. Apart from the capital value of the vacant land, the holding dam and irrigation works are estimated to have a present value of about $190 000 and operating costs are probably around $15 000 p.a. There is even a small net return on the agistment of livestock (in 1989 this was $6000). This is to be contrasted with the the company's likely share of the $1.5M capital cost of the new sewer, together with the Board charges for this volume of effluent, which would be around $160 000 p.a. However, the scheme has only been made feasible by the program of water conservation in the plant, together with the ability to reuse effluent in the cooling system. These together have reduced the volume of wastewater requiring land disposal to an annual average of less than 3 L/s.

C

40

'~

OCT

SEP

"°"

7

DEC

Iii Tree requirement

Figure 1. Balance of rainfall, effluent and irrigation requirement

Distribution System The 24 forest blocks are each mol}itored by a soil moisture probe. The information is fed to a computer which is programmed with the requirements of the trees, and when irrigation is needed, twin multi-stage pumps are switched on, forcing water through two sand filters and into 3 km of PVC mains and submains, then via one of 24 solenoid valves into the requisite block. A total of 100 km of polythene tubing feeds the water to the drippers alongside each tree. The computer turns off the flow after a pre-programmed shift of, say, one or two hours. The computer control system parameters include: irrigation schedule, total application, soil moisture status, valve pressures, pump pressure, filter differential, current operating status and fault reports, and logging of primary flow, (instantaneous and accumulated), and the balance storage level. Monitoring program As well as the dam water (Table 2), the soil chemistry, and leaf tissue analyses are being checked. As well, 5 major and 12 minor bores have been sunk to monitor groundwater level, quality and flow. Nutrient additions such as nitrogen and potassium will be required from time to time. Table 2. Dow Waste Water Quality Parameter

BOD

ss

E Coli per 100 mL

TDS TKN

TP Na Ca Mg SA Ratio

Treated Effluent*

6 14

< 20 560 1.9 0.6 220 15

8 12

• mg/ L unless oth erwise indicated .

continued on page 42 WATER February 1991

23


Microbiological Quality of Drinking Water A Review of the Major Urban Systems by K. POWER and L.A. NAGY ABSTRACT A variety of microbiological methods and standards is in use within Australia for designating drinking water quality. A review is provided of microbiological water quality within the country's main urban drinking water distribution systems, which supply water to 65-70% of the Australian population. Results are presented in terms of the different microbiological methods, and water quality standards in operation within the n~ne member agencies of the Major Urban Water Research Association.

Kaye Power, B.Sc. (Hons) was the project officer on the Urban Water Research Association bacterial regrowth in water distribution systems study. She is currently engaged in a Ph.D. studies at the University of N.S.W. on the same topic.

ABBREVIATIONS APHA American Public Health Association CFU/mL Colony forming unit per millilitre Heterotrophic plate count HPC Most probable number MPN NHMRC National Health and Medical Research Council Australian Water Research Council AWRC Standards Association of Australia SAA Standard plate count SPC World Health Organisation WHO

Laslo A. Nagy, B.Sc. (Hons) and Ph.D., is a director of Aquatech Pty. Ltd. He has published several papers in the fields of Microbiology, and water management. For the past ten years he has worked on various aspects of drinking water quality and microbial regrowth in drinking water distribution systems.

INTRODUCTION Microbiological drinking water quality has been defined in terms of a number of characteristics, which have generally been expressed as numbers of total coliforms, faecal coliforms, Escherichia coli, and/or heterotrophic bacteria, in a given volume of water. Although there is wide agreement on the general descriptions of microbiological water quality, the specifics of the definition tend to vary a great deal. Even within the Australian water industry, there are a number of methods and techniques in use for the analysis of total coliforms, faecal coliforms, E. coli, and heterotrophic bacteria (APHA, 1975, 1980, 1985 & 1989; Report 71, 1969 & 1987; SAA 1981a & b; WHO 1984a & b) . A uniform method and standard has not been adopted for the whole country, partly because a single approach has not been considered universally satisfactory. Operators of different distribution systems have selected and in some cases modified methods and standards to suit their particular water type, distribution system, environmental conditions, cost structures and technical demands (Power and Nagy, 1989). As"part of a wider project commissioned by the Major Urban Water Research Association, a study was undertaken to summarise microbiological methods, standards and water quality within the nine member agencies of the Association [ie Brisbane City Council, Hunter Water Board, Water Board (Sydney), ACT Electricity and Water, Melbourne Board of Works, Hobart Regional Water Board, Engineering and Water Supply (SA), Water Authority WA, and NT Power and Water Authority]. Because of the high urbanized nature of Australia, these nine agencies provide water to 65-70% of the nation's population. The results of this study are presented below in terms of the different distribution systems, microbiological methods, and water quality standards within the member agencies of the Major Urban Water Research Association. The Brisbane City Council

The Brisbane City Council supplies water to the cities of Brisbane, Ipswich, Logan, as well as parts of the city of Redcliffe and the shires of Albert, Beaudesert, Caboolture, Moreton and Pine Rivers, serving a total population of 1.3 million people. Within the system there are three major storage dams (Wivenhoe, Somerset and North Pine) in relatively buffered catchments. Water from the Brisbane River catchment travels to the Mt. Crosby Weir and is subsequently pumped to the two Mt. Crosby treatment plants, one of which provides conventional treatment (with flocculation, sedimentation, rapid sand filtration and chloramination), whereas the other plant operates by dissolved air flotation . Additional treatment plants at North Pine and Enoggera Dams ensure the entire supply is treated. All service reservoirs are 24

WATER February 1991

roofed to prevent contamination and algal growth, which otherwise would occur in the warm temperatures and sunny conditions of Brisbane. The Brisbane City Council processes about 15 000 bacteriological samples per year from approximately 220 sites throughout the distribution system. Total coliforms are enumerated using LESEndo agar and membrane filtration. The samples are pre-enriched for 1.5h on lauryl tryptose broth and finally incubated at 35째C for 24h. Presumptive coliforms are confirmed in EC broth at 35째C for 48h, positive cultures are then transfered to fresh EC broth and incubated at 44.5 째C for 24h to confirm for faecal coliforms. HPC are incubated at 35째C for 48h using plate count agar. All procedures used are based on standard methods (APHA, 1985). The water quality guidelines followed by the Brisbane City Council are the same as the WHO (1984) shown in Table 1. An internal guideline of < 100 CFU/mL is also placed on HPC bacteria and samples above this level are viewed as suspect due to possible coliform supression. The microbiological compliance levels for 1986-88 in terms of the WHO (1984) guidelines can be seen in Table 2a. This table shows the high compliance level of the Brisbane City Council water supply for total and faecal coliforms, and indicates that Brisbane will have little difficulty in meeting the NHMRC, AWRC (1987) guideline levels. Furthermore for the two years indicated, greater than 99% of samples contained no faecal coliforms. The extensive treatment the Brisbane water supply undergoes, together with subsequent chloramination and reservoir maintenance, results in relatively high microbiological water quality. Hunter Water Board

The Hunter Water Board serves reticulated water to 400 000 people in the Newcastle area. Most of the water is supplied from two surface sources (Chichester and Grahamstown) which undergo full treatment, while the remainder is supplied from groundwater sources. Though most of the reticulation reservoirs are covered, a number of large uncovered storages are also present. During 1986, chlorination was replaced by chloramination in an attempt to increase and maintain chlorine residuals. After several months it became obvious that this disinfection method was inappropriate for the system, (due to an increase in HPC levels), and a return to chlorination followed.


Table 1: Water Quality guidelines used by the nine member water authorities Indicator

NHMRC, AWRC (1980) E. coli Coliforms

E. coli Coliforms NHMRC, AWRC (1987) 1 Faecal coliforms Coliforms REPORT 71 (1982) E. coli Coliforms

WHO (1984) Faecal coliforms Coliforms

Guideline Value

90% of all samples should not contain levels in excess of 2 E. co/i/ lOOmL 90% of all samples should not contain levels in excess of 20 coliforms/ lOOmL LONG TERM OBJECTIVES No sample should contain any faecal coliforms in lO0mL. 95% of samples should not contain any coliforms in lO0mL. No sample should contain any faecal coliforms in lOOmL. 95% of samples should not contain any coliforms in lO0mL. Up to 10 coliforms may be occasionally accepted No sample should have any E. coli detectable in lOOmL No sample should have more than 3 coliforms in lO0mL 95% of samples should contain no coliforms. No sample should contain any faecal coliforms in lO0mL 95 0Jo of samples should not contain any coliforms in lOOmL 3 coliforms in lOOmL in occasional but not consecutive samples.

I. Coliform indi cator compliance section 3.6 included in guidel in es for certain systems (NHMRC , AWRC 1987) wh ere for annual reporting purposes adequate performance is achieved if 900/o o f samples have no more than 20 coliforms/ lOOmL.

The distribution system is sampled for several microbiological parameters, using procedures based on standard methods (APHA, 1985). These microbiological parameters include total coliforms and faecal coliforms using membrane filtration onto M-Endo and MFC broth. HPC are incubated at 37°C for 48h using tryptone glucose extract agar. The guidelines followed for monitoring the Hunter District reticulation system are the NHMRC, AWRC (1980) long term objectives (Table 1). Total coliforms, faecal coliforms and HPC results are grouped together to produce one microbiological indicator. The percentage of samples meeting this standard can be seen in Table 2b. The Hunter Water Board's goal is to increase the percentage of water samples meeting the NHMRC, AWRC (1987) quality guidelines to 97% by 1993. The Water Board (Sydney, Illawarra and Blue Mountains) The Water Board supplies water to about 3.4 million consumers in the Sydney metropolitan area, as well as to a number of nearby towns, areas on the South Coast and in the Blue Mountains. The Board operates six major storage dams. The largest of these, Warragamba Dam, gravitates water to Prospect Reservoir, a large shallow lake (50 000 ML) in the outer western suburbs of Sydney, before distribution to the metropolitan area. The reticulation system contains 261 service reservoirs with about 19 000 km of mains. Nearly all service reservoirs are roofed, to reduce contamination from atmospheric and avian sources, although the two large balance reservoirs (437 and 799 ML) at Potts Hill are not. Chloramination and fluoridation are carried out on water leaving Prospect Reservoir with three large chloramination plants located on the outlets of this reservoir. Three booster chlorination plants are also located at Potts Hill and at five service reservoirs within the system . Two more proposed plants are awaiting approval and construction. Water is gravitated from Prospect Reservoir to Pipe Head where a proportion is fine-screened before being transferred to Ryde Pumping Station or gravitated to Potts Hill. From Ryde Pumping Station water is supplied to most areas north of the harbour, while Potts Hill supplies most areas south of the harbour. A complex system of interconnecting large trunk mains gravitates water from Potts Hill towards the city, supplying the low lying areas along the way and providing suction water for a number of pumping stations. Water entering the main metropolitan system must pass through Prospect Reservoir with a large proportion moving on to the two Potts Hill reservoirs. All three of these reservoirs are uncovered, and they contribute large amounts of algae and other suspended matter, thereby altering the quality of the bulk water.

Problems with coliform infestation, during late 1976, resulted in extensive swabbing programs. In 1986, f~rther efforts to control this problem saw chlorination replaced with chloramination in some areas of Sydney and the planned installation of additional chlorination plants at strategic points along the system. This has resulted in chlorine residuals at 60-70% of consumer taps as compared with only 10-15% before the change to chloramination. Approximately 18 000 reticulation samples are processed per year. These samples are from 719 reticulation points (garden taps), 216 service reservoirs and 50 head works sites. Total and faecal coliforms are measured using membrane filtration, onto M-Endo and M-FC broth respectively. Procedures and incubation times follow standard methods (APHA, 1980). HPC use the pour plate technique and R2A agar, at two incubation times and temperatures of 35 °C for 48h and 20 °c for 7 days. The water quality guidelines followed b the Water Board are the same as the NHMRC, AWRC (1980) levels (Table 1). However, it is the Water Board's aim in the future to meet the NHMRC, AWRC (1987) guidelines. No formal internal guidelines are set for HPC bacteria. The compliance levels to these guidelines can be seen in Figure 1. The percentage compliance for total coliforms over the last three years has not been far above 90% , for either the 1980 or the 1987 NHMRC, AWRC guideline values. The percentage compliance for faecal coliforms is generally above 98% . The high faecal coliform compliance levels along with the higher more frequent levels of total coliforms isolated, indicates regrowth rather than a contamination event. Previous results published by Ireland et al., (1983) indicated that Sydney did have significant coliform regrowth within some areas of the distribution system. The extent of this regrowth has diminished as a result of remedial activities in recent years.

Table 2: Microbiological water quality compliance levels. (a) Brisbane City Council, 1986-1988. 0/o samples with "Jo samples with 0/o samples with OJo samples with total coli forms 0-3 total coliforms < 3 total coliforms faecal coliforms

1986- 87 1987-88

.

/ IOOmL

/ IOOmL

/ IOOmL

/ IOOmL

98.82 98.43

0.97 1.22

0.21 0.35

0.26 0.26

(b) Hunter Water Bo,rd, 1986-1988. OJo of samples meeting microbiological indicators

87 91

1986-87 1987-88

(c) A.CT. Electricity and Water, 1986-88. OJo samples with 0 faecal coliforms / IOOmL

1986- 87 1987-88

OJo samples with

< 3 total coliforms / IOOmL

99.6 99.9

98.4 95.4

(d) Hobart Regional Water Board, 1985-88. 0/o of samples with

< 20 total coliforms/ lOOmL 1985- 86 1986-87 1987- 88

98 98 .5 97

(e) Water Authority of Western Australia, 1985-88.

1985-86 1986- 87 1987-88

% of samples with total coliforms < 10 CF U/ IOOmL

OJo of samples with 0 E. co/i/ lOOmL

99.64

99.97

100

100

99.93

99.88

(f) N.T. Power and Water Authority, 1986-88.

1986- 87 1987-88

0/o samples with < 2 E. co/i/ lOOmL and < 20 total coliforms/ lOOmL

% samples with 0 E.co/i/ lOOmL and 0 total coliforms/ lOOmL

98 98

85 75.4

WATER February 1991

25


Ea IJ

~

100

"

40

<20 TC/lOOmL

<10 TC/lOOmL <2 FC/lOOmL .

l: a'

~ 20

cl:

0

1985-86

Fig. 1 -

1986-87 Year

1987-88

Microbiological water quality compliance levels, The Water Board (N.S.W.), 1985-88.

ACT Electricity and Water

Canberra's water supply serves a population of 294 000 including Queanbeyan, which represents the largest inland concentration of people in Australia. Water is collected in the Corin/ Bendora catchment south-west of the city, and in the Googong catchment in the south-east. Water from the Corin/Bendora catchment receives chlorination, fluoridation and pH correction at the Mt Stromlo Water Treatment Plant, while full treatment is given to water from the Googong catchment at the Googong Water Treatment Plant. From these treatment plants water is passed into an interconnecting network of reticulation mains and some 42 service reservoirs. Reticulation mains are usually cement lined cast or ductile iron, with a minimum diameter of 100 mm. Service reservoirs are all roofed and protected from the entry of birds and wildlife. The reticulation system, including mains directly off storage reservoirs, are regularly monitored, three times per week with approximately six sites per sampling run, while the water treatment plants are monitored daily. However, no samples are collected at consumers taps. Samples are processed using the techniques in standard methods (APHA,1985). Tests conducted include total and faecal coliforms using membrane filtration onto membrane lauryl sulfate agar (MLSA) at 35°C and M-FC agar at 44.5°C as well as HPC bacteria using plate count agar at 35°C for 48h. Table 2c shows the compliance levels of Canberra's water supply to the NHMRC, AWRC (1987) guidelines (Table 1). No formal guideline is set for HPC bacterial levels. The microbiological quality of Canberra's drinking water is relatively high. This is probably the result of high water quality from the Corin/Bendora catchments and full treatment of water from the Googong catchment. Other factors include new reticulation mains with a minimum of dead-ends and covered service reservoirs. However it must be noted that reticulation points (eg. garden taps, dead ends) are not sampled on a regular basis, and the absence of such sites probably raises compliance levels above values that would be otherwise expected. Melbourne Board Of Works

The Melbourne Board of Works supplies potable water to approximately 2._5 millon people spread over about 600 sq km, in and around the city of Melbourne. The system comprises 10 major storage reservoirs, 15 000km of water mains, some 100 service reservoirs, 22 chlorination plants and 1 chloramination plant. Some parts of the system were constructed as long ago as the 1850s but most of the present system was constructed in the last 25 years. Virtually all the old unlined mains in the system have been replaced or cement lined (Sheedy and Greer, 1987). Some 900Jo of the water supply originates in protected mountain catchments, and this supply does not receive any treatment apart from coarse screening and disinfection . All the mountain catchments except one (the Thompson catchment) are strictly reserved for water supply purposes and public access is restricted. The remainder of the supply originates in inhabited rural catchments and when this supply is required it receives comprehensive treatment at the Winneke (450 ML/ day) treatment plant before entering the distribution system. In 1986 chloramination was introduced on a trial basis, in the Mt. Dandenong Ridge and Monbulk supply zone, but the rest of the system uses chlorination. In an endeavour to achieve better water quality the Board of Works has implemented a program to cover all ser.vice reservoirs 26

WATER February 1991

and tanks. It is anticipated that by 1992-93 this program will be complete. The percentage of total area covered has increased from 340Jo in 1984-85 to 650Jo in 1987 . Approximately 9000 bacteriological samples are processed per year from 775 sample sites (13 head works 162 within the distribution system and 600 at customer taps). U~ until September, 1988 samples were tested for total coliforms, E. coli and HPC bacteria; after this date routine analysis for E. coli was discontinued in favour of faecal coliforms. The methods employed are based on a combination of those described in WHO (1984) and Report 71 (1982). Both faecal and total coliforms are enumerated using either membrane filtration or the multiple tube method. Membrane filtration for both faecal and total coliforms uses MLSA incubated at 30_ 0 c for 4h followed by 14h at 44 °C and 37°C respectively. Mul~1lpe tube method analysis utilizes minerals-modified glutamate med1_um at_ 37°~ _for 24-48h, tubes producing acid and gas are confirmed m bnlhant green lactose bile brot h at 44°C and 37°C. HPC levels are enumerated using yeast extract agar and incubated at 37°C for 48h (HPC at 22°C was discontinued in late 1985). The water quality guidelines (for day to day operational purposes) employed by the Board of Works were based on the NHMRC AWRC (1980) up to July 1988, when these were replaced by th~ NHMRC, AWRC (1987) guidelines (Table 1). No guideline is placed on HPC bacteria, however an informal guideline is set at 1000 HPC/mL. Compliance levels of samples to these guidelines can be seen in Figure 2. As shown by the figure, over the previous three years the percentage of samples with < 2 E. coli has been above the 900Jo compliance level (as well as above 95 OJo ). Total coliform levels have also been above this 900Jo value but only marginally above 950Jo. The high numbers of total coliform levels often found in the Board of Works water alongside the low or infrequent E. coli numbers suggests that the coliforms are from an environmental rather than faecal source. With the present coliform levels the Board of Works m~y ex_perience difficulty in meeting the NHMRC, AWRC (1987) guideline of zero faecal co liforms/lO0mL and zero total coliforms/lO0mL in 950Jo of samples, but will meet the annual reporting levels of section 3.6 (Tobie 1). The Board of Works feels that because of its'protected catchments and long reservoir retention times, chlorination provides adequate treatment, even though this may allow the entry of some bacteria and nutrients into the distribution system. -(

Hobart Regional Water Board

The Hobart Regional Water Board supplies water to four metropolitan municipalities and water districts as well as wayside consumers of five rural municipalities with a combined total of 200 000 people. Raw water is supplied from catchment and mountain storage reservoirs (all of which are surrounded by protected catchments) and the Derwent River. The Derwent River supplies 700Jo of the total average water demand. Catchment and mountain storage reservoir water supplies undergo chlorination and fluoridation. The Derwent River supply is fully treated ~t the Bryn Estyn treatment plant. From three large storage re_servoirs located at Box Hill, the water is gravitated to the metropolitan area of Greater Hobart by means of two pipelines (39 km and 27 km in length) . During summer some bypass of the treatment plant is necessary to meet demand requirements. In this situation when treatment is at full capacity up to 500Jo of the water

~ §"

rzl B

100

<20 TC/1 OOmL <2 E.coli/lOOmL

80

;=I

§

60

~ is

40

~

20

i::

~

0

Fig. 2 -

1985-86

1986-87 year

1987-88

Microbiological water quality compliance levels, Board of Works (Melbourne), 1985-88.


receives chlorination only. It is, however, shandied with fully treated water. The reticulation system is monitore.d weekly at approximate!)'. 30-40 sampling sites all situated at or before service reservoirs. Samples are analysed for total and faecal coliforms using membrane filtration onto MLSA with a 4h resuscitation period at 30°C, followed by incubation for 14h at 35°C and 44.5°C respectively. HPC are not analysed. Table 2d shows compliance of Hobart's water to the NHMRC, AWRC (1980) long term objectives (Table 1), which used to be the water quality criteria employed by the board. This has since been replaced by the NHMRC, AWRC (1987) guidelines. Hobart Regional Water Board appears to have water of high microbial quality. This is probably due to the high quality of raw water and the level of treatment provided. However it must be noted that points beyond reticulation reservoirs are not sampled on a regular basis, and the absence of such sites probably raises compliance levels above values that would be otherwise expected. Engineering and Water Supply Department of South Australia The Metropolitan Adelaide system is supplied from several reservoirs in the Mt. Lofty Ranges and augmented from the River Murray. The water is disinfected at each source by chlorination (commenced 1955) and is progressively being filtered (since 1977). At present four water treatment plants provide filtered water to appproximately 400Jo of Adelaide's 900 000 consumers, chiefly in the northern and eastern suburbs. A filtration plant at Happy Valley (recently commissioned) with another proposed for the Myponga supply will result in over 900Jo of Adelaide being provided with a filtered water supply. The progressive introduction of water treatment led to significant improvements in the physical and microbiological quality of the water. The system is regularly monitored for water quality characteristics (microbiological, physical and chemical) to determine the acceptability of the supply for drinking purposes. Approximately 3 500 samples are collected from points after treatment, service tanks and distribution locations (including consumer taps) for analysis of total and faecal coliforms. Chlorine residuals are examined more frequently to check satisfactory addition of disinfectant, particularily after disinfection points. Monitoring techniques used are based on standard methods (APHA, 1985) and methods recommended by the Standards Association of Australia (1981a & b). In the case of microbiological analyses, membrane filtration techniques are generally employed. Total coliforms and faecal coliforms are enumerated using two-stage techniques. Enumeration of total coliforms is undertaken by enriching for coliforms with lauryl tryptose broth for 2h at 35°C fo llowed by incubation on LES-Endo agar (35 °C/22h). Faecal coliforms are enumerated by incubating the membrane on a modified m-FC agar at 30°C for 4h followed by approximately 16h selective growth at 44.5°C. Some supplies are also analysed for colony counts at 20°C (for 72h) and 35 °C (for 24h) using plate count agar. The microbiological results indicate the acceptability of the supply for drinking purposes and, if quality deteriorates, are used to assess the need for remedial action. This may include adjustment of chlorine dose rates and/or local chlorination of service tanks. Collated microbiological data for several years of operation have been used to develop levels of service for achievable quality at consumers' taps, currently these exist for filtered and unfiltered water. In filtered water total coliforms should be absent (in lO0mL) in 800Jo of routine samples, and the count in the remaining samples should not exceed 10/ lO0mL, while faecal coliforms should be absent in (lO0mL) in 950Jo of routine samples, and the count in the remaining samples should not exceed 10/ lOOmL. In unfiltered water coli forms should be absent (in lO0mL) in 600Jo of routine samples, and the count in the remaining samples should not exceed 20/lO0mL. Faecal coliforms should be absent (in lOOmL) in 90% of routine samples and the count in the remaining samples should not exceed 2/lO0mL. The levels of service also provide a basis for the annual performance assessment of each system. The long term targets for microbiological quality of the Adelaide supply were the WHO (1984) guidelines but are currently the NHMRC, AWRC (1987) guidelines (Table 1). The adoption of levels of service is a first step in a staged program for the achievement of the long term objectives. The percentage of samples with zero coliforms in Adelaide supplies can be seen in figure 3.

~

100

~

80

8

60

~

40

;.:; c..

• 0

1986-87 1987-88

8 £3

C:

§ ~

20 0

Fig. 3 -

Microbiological water quality comJ>Iiance levels, S.A. Engineering and Water Supply, 1986-88.

The microbiological quality of water immediately after treatment is generally good but this may deteriorate through the reticulation system as indicated by occasional isolation of coliforms. Increases in bacterial numbers are generally attributed to the effect of service reservoirs. However, in recent years the quality of stored water has improved as the result of the repair or replacement of reservoir roofs. The microbiological quality of water in the Myponga system also improved during 1987-88 due to chloramination of the supply. Disinfection of the supply has since been returned to chlorination. Water Authority of Western Australia The Water Authority of Western Australia supplies water to the city of Perth servicing approximately 1 million people. Raw water is obtained from protected surface water catchments located in the Darling Ranges and from ground water supplies situated below the Swan Coastal Plain. Water from catchments, which has negligible colour and turbidity, receives only screening and chlorination, while groundwater is given conventional treatment involving coagulation, sedimentation, rapid sand filtration and chlorination at four major treatment plants (Wanneroo, Mirrabooka, G\1/elup and Jandakot). The water supply system uses service reservoirs for immediate storage. A program to roof all the service reservoirs is in progress, and in the interim, outlet chlorination is operated at those which are unroofed (Burke et al., 1984; Neil, 1987). Routine analysis is carried out by the State Heath Laboratories using methods based on those recommened in Report 71 (1969) . Enumeration of E. coli and total coliforms is by membrane filtration with Enriched Teepol broth modified to contain 0.20Jo Teepol, incubated for 6h at 25°C followed by 18h at 44.5°C and 35°C respectively. HPC are analysed using a modification of Tri phenyl Tetrazolium Chloride in Heart Infusion Broth, incubated at 22°C for 96h and 35°C for 24h. Water quality guidelines followed by the Water Authority of W.A'. are the same as the NHMRC, AWRC (1980) guidelines with reference to the long term objectives (Table 1). Tobie 2e shows that Perth can readily meet the desired water quality criteria both in terms of the NHMRC, AWRC (1980) long term objectives as well as the current NHMRC, AWRC (1987) guidelines, and does not appear to have any significant bacterial regrowth problems. The high microbiological quality of Perth drinking water can be attributed to high quality of the source waters, both surface and groundwater, adequate disinfection where required and the continuing efforts to cover unroofed reservoirs. N.T. Power And Water Authority Darwin, with a population of 70 000 people, obtains its drinking water from the Darwin River Dam which has a fully protected catchment. All water entering the distribution system is chlorinated at McMinns Reservoir to a free chlorine residual of 1 mg/L. The reticulation system contains within it 22 covered reservoirs of which 20 are continously in use. Rising mains and reservoirs are sampled once a week, but reticulation pipes and consumer taps within the distribution system are generally not monitored . Samples are analysised using techniques based on standard methods (APHA, 1985). Total coliforms and E. coli are measured using m-Endo media at 37°C for 24h and m-FC broth at 44.5°C respectively. HPC bacteria are also measured at 37°C for 24h using SPC agar, but 20°C 7 day plates are not determined as these are not relevant to water temperatures within Darwin. WATER February 1991

27


The water quality guidelines followed are based on the E. coli level in the NHMRC, AWRC (1980) water quality guidelines, (Table 1). Investigation levels are set at greater than 20 total coliforms/lO0mL and greater than 2 E coli/lO0mL. Compliance· of samples to guidelines can be seen in Table 2f. For bulk water entering the distribution system after chlorination there is 100% compliance with the zero E. coli/lO0mL, zero coliforms/lO0mL guidelines. Due to the relatively high water temperatures (generally above 28°C), the Darwin system does experience bacterial regrowth in terms of total coliforms but generally not in terms of E. coli. Because of this the N.T. Power and Water Authority may experience some difficulty in meeting the NHMRC, AWRC (1987) guidelines particularly with respect to sample points beyond reticulation reservoirs.

DISCUSSION The water quality compliance data supplied by the nine authorities shows considerable variation in the calculation and expression of compliance. Some authorities use WHO (1984), where others use NHMRC, AWRC (1980), although an increasing number (about half or more) use NHMRC, AWRC (1987). · The adoption of a uniform set of standards by all nine water authorities (as well as by other water agencies throughout Australia) is probably desirable. The framework of NHMRC has been able to provide standards specifically formulated for Australian conditions, and it appears that NHMRC, AWRC (1987), or its successor (Wade, 1991), will become the uniform set of guidelines adopted by Australian water authorities. Compliance levels were relatively different in the nine systems investigated. These differences may have been due to a number of real and/or artificial factors. Some of the real factors no doubt inciuded differences in raw water quality, level of treatment, disinfection practices, and distribution system maintenance. One of the artificial factors may have been the different compliance definitions used by the different authorities. The use of a uniform set of compliance calculations, as discussed above, will improve the validity of future comparisons between the nine authorities. Other differences may have been due to the sample locations used, and their distances into the distribution system. Some authorities used a mixture of sites including customer taps, whereas others only used bulk distribution lines or points relatively close to the treatment plant. Future drinking water guidelines (Wade, 1991), may need to address this issue in more detail, and specify the mix of sites to be used. Ideally, the majority of sampling sites should be well within the distribution system, and close to or at customer taps. Interestingly, the variety of microbiological methods used by the nine authorities probably was not responsible for differences in compliance. In a comparison of coliform methods used by the nine authorities, Power and Nagy (1989), found recovery rates to be relatively similar between the main methods, most of which were APHA (1975, 1980, 1985, and 1989). These results suggested that most authorities would readily be able to switch to a uniform set of methods, without a significant loss of historical comparability. Once again, this issue may be addressed in more detail in future Australian guidelines.

member water authorities, the Brisbane City Council, Hunter Water Board, Water Board (NSW), ACT Electricit~ and Water, Board of Works (Melbourne), Hobart Regional Water Board, Engineering and Water Supply (SA), WA Water Authority, and NT Power and Water Authority, for their permission to publish this work and the appropriate contact officers for their cooperation in providing information on each system.

REFERENCES AMERICAN PUBLIC HEALTH ASSOCIATION (1 975). Standard methods for the examination of water and wastewater, 14th ed. American Public Health Association, Washington D.C. AMERICAN PUBLIC HEALTH ASSOCIATION (1980). Standard methods for the examination of water and wastewater, 15th ed. American Public Hea lth Association, Washington DC. AMERICAN PUBLIC HEALTH ASSOCIATION (1985). Standard methods for the examination of water and wastewater, 16th ed. American Public Health Association, Washington D.C. AMERICAN PUBLIC HEALTH ASSOCIATION (1989~ Standard methods for the examination of. water and wastewater, 17th ed. American Public Health Association , Washington D.C . BACTERIOLOGICAL EXAMINATION OF WATER SUPPLIES (1969). Reports on public health and medical subj ects, no. 71. London, England: BACTERIOLOGICAL EXAMINATION OF WATER SUPPLIES (1982). Reports on Public Health and Medical Subjects, no. 71. Methods for the examination of waters and associated materials. London, England: BURKE, V. , ROBINSON, J., GRACEY, M., PETERSON, D. and PARTRIDGE, K. (1984). Isolation of Aeromonas hydrophila from a metropolitan water supply: Seasonal correlation with clinical isolates. Appl. Environ. Microbial. 48: 361-366. IRELAND, R.W., COOPER, B.W. and BOWEN, L.D. (1983). A review of Sydney's experience with bacterial contamination in the reticulation system. Fed. Convent. Aust. Water and Waste Water Assoc. 62: 1-9. NEIL, J. (1987). A microbiological study of the Perth water supply 1985- 1987. University of Technology W.A. NHMRC, AWRC (1980). Desirable quality for drinking water in Australia. National Health and Medical Research Council, Australian Government Publishing Service, Canberra. NHMRC, AWRC {1987). Guidelines for drinking water quality in Australia. National Health and Medical Research Council, Australian Water Resources Council, Australian Government Publishing Service, Canberra. POWER, K. and NAGY, L.A. (1989) . Bacterial regrowth in water supplies . Urban Water research Association of Australia, Research report no. 4. SHEEDY, B.J. and GREER, J.H. {1987). Quality assurance program for Melbourne's water supply 12th Federal A.W.W.A. Convention, pp 352-359. STANDARDS ASSOCIATION OF AUSTRALIA (1981 a). Microbiological examination of water for dairy purposes . Examination of water for coli forms by membrane filtration, AS.095.4. 1. 5. STANDARDS ASSOCIATION OF AUSTRALIA (1981b). Microbio logical examination of water for dairy purposes. Examination of water for Escherichia coli by membrane filtration, AS.1095.4.1.6. • WADE, A. (1991). Australian drinking water guidelines in prospect and retrospect. Proc. Federal Convention, Australian Water and Wastewater Association, Perth. WHO (1984a) World Health Organisation. Guidelines for drinking water quality, Volume 1: Recommendations. WHO (1984b) World Health Organisation. Gljidelines for drinking water quality, Volume 2: Health criteria and other supporting material.

CONCLUSIONS Microbiological compliance standards varied between the nine members of the Major Urban Water Reserch Association, although an increasing majority were using NHMRC, AWRC (1987). It would be desirable to have a uniform set of guidelines for the whole of Australia, and it appears that NHMRC, AWRC (1987), or its successor, will be adopted by most water authorities in the country. Differences in compliance levels between the nine authorities may have been due to a number of real factors such as differences in raw water quality, treatment processes, disinfection practices, and distribution system maintenance, as well as a number of artificial factors such as methods for calculating compliance, and choice of monitoring points.

ACKOWLEDGEMENTS This review was part of a study on bacterial regrowth within water distribution systems conducted by the Water Board's (Sydney) Scientific Services and funded by the Urban Water Research Association of Australia. The authors would like to thank the nine 28

WATER February 1991

NOfE CHANGE OF ADDRESS OF AWWA FEDERAL SECRETARIAT Location: 1st Floor, 76 Hampden Rd, ARTARMON SYDNEY Postal Address: PO Box 388, ARTARMON NSW 2064 Telephone: (02) 413 1288 (no change), Facsimile: (02) 413 1047


Working with Lobby Groups A report compiled by one of the syndicates at the Australian Management College, Mt. Eliza in October 1990 and edited by Bob Swinton. SUMMARY The syndicate defined the problem and suggested a number of strategies to improve communication so that decision making for the benefit of the comunity could be less fraught with emotion.

Environmental: to engage in management practices that conserve resources and improve the environment. Political: to have decisions made in the best long-term interests of the community.

INTRODUCTION

THE ISSUES

At the most fundamental level, both lobby groups and water management authorities desire to: â&#x20AC;˘ protect our resources â&#x20AC;˘ enhance our environment â&#x20AC;˘ ensure our future. Consequently, they should be working to a similar end with similar goals, similar visions and sharing similar values with respect to our water resources. To a casual observer, however, there would seem to be little commonality, due to the sometimes extreme positions adopted by both parties. This situation needs to be corrected. On the part of the water authorities, one aspect of succesful management must therefore be to work with lobby groups in a way that meets the needs of the community and of the water industry. If tackled skilfully, this could limit the growth of potentially damaging elements of some lobby groups.

The key strategic issues facing the water industry at present were defined as: Political: Legislation, power, fear, concern, media attitude, environmental lobbies, apathy of the silent majority, leading to polarisation and conflict, which tends to negate rational decisions. Quality~ Of product, of service standards, of lifestyle. Environmental: quality, restoration, conservation of 'nature', versus public health needs. Costs: sustainable use of resources, demand management, asset management and replacement, public versus private ownership.

WBBYGROUPS Lobby groups form in response to specific issues, and, at least in their early life, focus only on those issues. Over time, however, the focus may shift and means may become ends. For example, a lobby group may decide to tackle broader issues, may amalgamate with other groups, reorganise and perhaps become a political party, as has happened both in Europe and in Australia. However, it is essential that the decision makers, (the politicians), and their formal advisers, (the management of the water authorities), view lobby groups as a useful and essential part of the democratic society. They are the catalyst which can assist in keeping resource use under continuing review, and perhaps give some assurance that the decisions which must be made reflect values of the wider community, not purely industry- or engineering-driven values. If authorities respond sympathetically, effectively and skilfully to a lobby group it should remain focussed on the original issue, and not become a frustrated protest group.

THE COMMUNITY The vague notion that the community consists of the public at large, i.e. the silent majority, is misleading. In practice, the community with which the water authorities are concerned can be categorised as follows : Government- Local, State, Federal Councillors, Aldermen, Ministers Political parties Businesses Industry Associations Media, print and electronic Lobby Groups, single issue, local or national Community Groups, broad issues Conservation Societies, local and national Other Government Departments/Authorities Residents Educational institutions and finally, the public at large.

OBJECTIVES OF THE AUTHORITIES These are seen to be: Business: to provide an assured and healthy water supply and waste disposal system. Quality: to meet statutory requirements for services and to be responsive to customers' needs . Cost: to ensure that services represent the best value for the customers' and taxpayers' money.

STRATEGIC ACTIONS The syndicate discussed the strategies to be utilised by the authorities to try to ensure that interactions with the community, and its lobby groups, resulted in positive responses to these issues. Identity: The true function of the industry and its potential, both in respect of expert knowledge and management capability, need to be established. It is essential that well-known leadership figures be developed . This also applies to the technical and business associations such as the AWWA. This should lead to increased ability to influence opinion leaders and lobby groups, and to neutralising the 'veto' elements. Status: The status in the community of en'gineers and scientists in general needs to be improved, so that their considered statements can be accorded better credibility. Community interest in water issues: This needs to be increased. The 'public relations' effects of adverfising, newsletters, inspections, open days, brochures, public forums and liaison committees will all lead the community to a better focus on the issues of greatest importance. Community priorities need to be placed in perspective. Media Reporting: All-too-frequent mis-reporting and hyperbole must be reduced . This can only be achieved at an industry and authority level by communication specialists with media skills, which acknowledge the specific priorities of reporters and editors. There needs to be pro-active provision of information by print and radio/ TV. Direct mailing to opinion leaders and decision-makers may encourage more factual reporting in the media. Real issues should be brought to the fore, and unnecessary fears lessened. Education: This must be a continuing effort. A better-educated community should lead to discussions and debates based on facts, not emotions. Schools and tertiary institutions (teachers and students), must be the primary long-term target, but the education of the other levels of the 'community' is immediately necessary. Basic environmental processes, public health, treatment processes, costs to the community, balance of risks, as well as information about specific projects, must be continuously addressed. All forms of educational methods are applicable and translations of technical jargon into meaningful terms should be attempted. Within the water industry itself, staff education, or training, should also address community involvement and communication skills. Communication: The informal network within and between authorities needs to be actively fostered on local media/sensitive issues. This could act as an early-warning system, and lead to quicker and more informed responses. Authorities could then move from being largely re-active, as at present, to being pro-active. A formal network is, as always, necessary between (and within) authorities for research/technical/management matters. Restructuring: An examination of most water authorities may well show a profile of dominance by engineers. There is a valid historical WATER February 1991

29


reason for this, but values and attitudes within such organisations may well not represent those of the wider community. However, the current corporate goals of the water industry require a range of skills which most engineering¡or technical personnel are ¡ inhibited from developing, often because their tertiary education has been so specialised. Further education, either formal or informal, is necessary to ensure that whatever the career background of upper management executives their attitudes must lead the organisations to communicate with, understand and be more tolerant of wider values. This may lessen the need for lobbies to exist. Corporatisation: If actively pursued, this could lead to lobby groups having to deal with authorities directly since, in the first instance at least, government/ political intervention would be reduced. This could apply particularly to the community reaction to the application of the true costs and pricing of services. For example, the balance between asset replacement and unnecessarily high treatment costs could be better discussed between customers and corporation without the political component interfering. Community Involvement: This is needed for many issues and on many levels. A truer representation of community opinion should see a better reflection of community values, not just those of the vocal minority groups. For example, the inclusion of input from

a panel of community representatives, in, say, a National Review of Quality Standards, would have the effea of reducing, if not eliminating, the intervention of lobby groups. National Policy Development: If policies on significant issues such as sustainable resource development, demand management, ocean outfalls, etc. could be formed and enunciated on a national basis, it should lead to a broader level of acceptance than if tackled on an authority to authority basis. The reaction of a lobby group to an application at a particular location would then have to be measured against the 'common weal'.

CONCWSIONS The above strategies are aimed at raising the level of community awareness, not at reducing it. However, a better educated community, (which would include the members of the authorities themselves), together with more real facts, and less emotive speculation in media reporting, should lead to an acceptance of lobbying as an intrinsic part of democratic decision making, but with a more balanced influence, rather than the emotional reaction which is the current hallmark of most lobby groups. The overall result should be to place the industry in a position to manage water resources in the best interests of the whole community.

13E SYMPOSIUM INTERNATIONAL SUR LE TRAITEMENT DES EAUX USEES. November 1990, Montreal, CANADA A report by Mitchell Laginestra This Symposium is an annual event organised by the Canadian societies and environment authorities. In 1990, it was held in Montreal, in French speaking Quebec, so that the majority of the papers were in French, with headphone translation to English. Altogether there were 17 papers presented, with another 14 published in the proceedings. The conference was very interesting and provides an opportunity to obtain information on wastewater research and operation outside Australia, USA and UK. The organisers are already planning for next year's conference-so start brushing up on your French! The evening of the first day of the Symposium culminated in a (research) fund raising dinner for "La foundation quebecoise de la reserche sur l'eau". For details of papers, contact Mitchell Laginestra on (02) 976 1421 during business hours. The papers presented included: A computer system to help in operation of facultative Lagoon wastewater treatment (Mr. J. B. Serodes, Laval University, Quebec); St Hyacinthe Wastewater Treatment Plant (Quebec)-design vs operation (Mrs. E. B. Boiselle, La Societe d'experts-conseils Pellemon Inc., Montreal); A pilot study of activated sludge coupled with membrane filters-new technology in wastewater treatment (Mr. P. Cote, Zenon Environmental, Burlington, Ontario); Toxicity assessment of water, sediment and depurated shellfish samples using the Microtox bioassay (Dr. M. M. Lau, Environmental Protection Department, Hong Kong); Agricu ltural utilisation of paper mill sludge in the Niagara area (ms. N . De Lint, Ortech International, Ontario); Incorporation of biological excess phosphorous removal in a general activated sludge model (Mr. P. L. Dold, McMaster University, Ontario); Three year experience with agricultural reuse of municipal sludges in Quebec (Mrs. A. St-Yves, Department of the Environment, Quebec); Pilot Study using the BIO FOR biological filter (which combines physical fi ltration and biological degradation) at Drummondville, Canada (Mr. P. Grulois, Zenon Environnement, Paris, France); Disinfection of wastewater in California (Mr. C. White, consulting engineer, California, USA); Tertiary treatment of sewage-comparison of upflow and downflow granular filters (Mr. M. Laginestra, Water Board, Australia); Novel and rational design approach for comm unity septic tanks (Mr. Y. Barabe, Hydro-Quebec, Montreal). Papers in the proceedings, included: Improvement of treatment of domestic oxidation ponds by polyphagous fishes (Mr. S. A . Khan, SPG College of Science, India); 30

WATER February 1991

Halifax Harbour Clean Up, a research perspective (Mr. H . B. Nicholls, Dept of Fisheries and Oceans, Nova Scotia); Status of Wastewater Generation: economic value and cost of treatment plants in Class 1 cities in India (Mr. R. M. Bhardwaj, Central Pollution Control Board, India). In addition, on the 16th November, the 2nd Canadian workshop on drinking water was held. I did not attend this, but papers are contained in the proceedings. These include: Developing Canadian drinking water quality guidelines; New developments in sedimentation ('trench); Utilisation of membrane filtration to reduce organic material and colour in drinking water (French); Study of the effect of treatment processes on the fate of dissolved organic matter using raw and spiked water (French); Chlorine demand reduction using ozonation and biological activated carbon filtration (French); and The coupling of ozone and hydrogen peroxide: from pilot studies to water treatment plant (French). A poster session included the following: Biological leaching of heavy metals as a sludge detoxification option; Submerged (rotating) biological contactor: operating characteristics; Biofiltration using peat-a promising option for small scale treatment; St. Lawrence River Action Plan for conservation and restoration.

FILTER SAND GRAVEL COAL TO AWWA B100-80 SINCE 1978 FOR PROMPT EXPERT ATTENTION

RIVER SANDS PTY LTD 683 Redland Bay Road, Carbrook, Qld, 4130 Ph (07) 287 6444 Fax (07) 287 6445


COMMISSIONING PROCEDURES FOR NEW WATER PIPELINES By L.S. BURN and T.J. RICHARDS INTRODUCTION Since its introduction to the Australian market in the 1960s, uPVC pressure pipe has gained wide acceptance in water distribution systems, particularly with smaller water boards and in rural applications. Pipes made by the local manufacturers were, until recently, all produced from extrusion formulations incorporating lead-based compounds as stabilisers and lubricants. These formulations are similar to those used in many other parts of the world, with the notable exception of North America where tin-based stabilisers and lubricants have been used. The Australian pressure pipe market underwent a major change in the mid-1980s when it was announced that local manufacture of asbestos cement pressure pipe would cease in 1987. There was considerable competition for the market share originally held by these pipes, and major water supply authorities began to review their pipe material selection policies. An enquiry into the use of uPVC pressure pipe for water supply purposes was conducted by the Natural Resources and Environment Committee (NREC) of the Parliament of Victoria in 1986. One of the most significant points raised by the enquiry involved the "quality" of water supplied through uPVC pipe, and the Committee heard evidence that there was potential under certain circumstances for water supplied from systems containing new uPVC pipes to have unacceptably high lead levels. The Committee was concerned at the lack of a standardised commissioning procedure for new water supply installations and recommended that, irrespective of the type of pipe material used, all new water supply services should be adequately cleaned, flushed and sterilised when first brought into use. Water distributed in uPVC pipes had been shown to have very low lead levels, with most analyses giving results below the detectable level, as discussed by Packham (1971) and the Plastics Institute of Australia (1979) . However, water supplied from newly installed uPVC mains can, under some circumstances, have lead contents exceeding the guideline values recommended by the World Health Organisation (1984), even though the pipes have been manufactured to meet the current national standards which incorporate effect on water requirements clause, as discussed by Packham (1971), Richards (1987) and Burn and Sullivan (1990). Following the NREC enquiry, the Rural Water Commission (RWC) introduced a commissioning procedure for new uPVC reticulation systems which involved quarantine and limited flushing of the system over a 28-day period or maintenance of a minimum continuous flow in the system for 14 days. After further investigation, the recommended commissioning procedure was revised. The new method used continuous flow at relatively low rates (less than 2 water changes/day) for 24 days following connection to the system, with the 28-day limited flushing procedure remaining as an option (Richards 1987). While the use of uPVC pipes by major water authorities has been increasing, concern about the risk of high lead levels in water from new installations and reluctance to adopt commissioning procedures of the type recommended by the RWC (usually on the grounds of water waste or operating costs involved) has caused some water authorities to require that only uPVC pipes made from "no-lead" or "low-lead" formulations be used in their systems. As part of an investigation by Burn and Sullivan (1990), a survey of major water authorities was carried out to determine practices used in commissioning newly installed water mains constructed of both uPVC and other pipe materials. A major aim of the survey was to see how much common ground there was between the commissioning procedures used for different pipe materials (and, indirectly, to see whether the recommendation of the NREC for a common commissioning procedure had been taken up by water authorities). This paper looks as the results of that survey and compares local practice with recommendations from overseas.

THE SURVEY In 1989 a questionnaire was sent to 15 major water authorities throughout Australia. Information was sought regarding 32

WATER February 1991

Stewart Burn is a Senior Experimental Scientist at the CSIRO Division of · Building, Construction and Engineering. He specialises in the durability of plastics building products and is currently chairman of several Standards Australia committees dealing with uPVC pipes and the mechanical testing of plastics.

Stewart Burn

Trevor Richards is a consulting materials engineer specialising in materials for water supply. He left the Rural Water Commission in 1989 to move to a farm in Gippsland where he is Chief Executive and turncock of his own water supply system. He is Chairman of Standards Australia technical committees dealing with both uPVC pipes and polyethylene pipes. Trevor Richards

• methods of commissioning, flushing and disinfecting new water mains, • special commissioning procedures used for mains constructed from uPVC pipes, and • details of additional flushing techniques that the authority had considered or might be prepared to use for particular applications. Replies were received from all but one of the authorities contacted. The responses are sum111arised in Table 1.

DISCUSSION It can be seen from Table I that in the case of uPVC mains, the commissioning procedure recommended by the RWC has been generally adopted and a uniform approach to commissioning has been established. For mains manufactured from other materials there is no uniform approach to commissioning and procedures vary greatly, from what amounts to a quick flush with no guidelines, to a comprehensive flushing and swabbing operation. A similar situation exists when it comes to the disinfection of new mains, where only 8 out of the 14 authorities regularly disinfect all new mains. It is surprising that disinfection is not more widely used because it was an established and common practice in many countries even 40 years ago. Taylor and Whiskin (1951) and more recently Williams (1986), consider that disinfection of new and repaired water mains is essential if bacterial contamination and outbreaks of water-borne diseases are to be avoided. Disinfection can be carried out by procedures such as those recommended by the Metropolitan Water Board (1968), or the American Water Works Association (AmWWA) (1986). In addition to disinfection, Williams (1986) recommended that water mains receive a preliminary flush to remove debris that could hinder the disinfection process. AmWWA recommends a minimum flow velocity of 2.5 ft/ s (0.75 m/s) for this flush to ensure debris removal. However, Elvidge (1982) points out that this velocity is not high enough to suspend and remove particles of 0.2 mm in diameter, a fairly small size for construction debris, and for pipe 100-200 mm in diameter velocities of 1.8-2.6 mi s are required to suspend this particle size. This agrees with the AmWWA who recommend that a flushing velocity as high as 3.6 mi s may be needed to remove sand. Because these velocities can be hard to obtain in larger pipes, swabs or pigs have been used to pre-clean lines and facilitate disinfection. Buelow (1976) points out the need for care during such operations to prevent forcing debris into joint spaces, because the


debris may later be responsible for progressive microbial activity causing degradation of water quality. A similar cleaning procedure is recommended by the National Water Council (1979), who state that mains should be laid as hygienically as possible with all visible debris and dirt being removed either manually or by the use of cleaning pigs, followed by a thorough flush with clean water. Swabbing is recommended by the Major Urban Water and Sewerage Authorities of Australia (1987), who found that where swabbing is carried out, up to 950Jo of mains can be commissioned after the first chlorination. Where swabbing is not practised, only 65-70% of new mains pass the first bacteriological test.

An alternative to swabbing is air soouring. this procedure, as discussed by Elvidge (1982), involves injection of compressed air into the pipeline creating unsteady flow conditions. This reduces the water volumes required to suspend particulate matter and, as discussed by Phey (1987), increases the efficiency with which particles can be removed. Wagner (1988) also investigated pulsed flushing or air scouring and found that complete cleaning of a main containing sand particles 2-4 mm in diameter was achieved with 5 minutes of air scouring at 0.5 mi s, compared with normal flushing, where 30 minutes at 0.6 mi s did not completely clean the main. The use of swabbing or air scouring in Australia is very

TABLE 1 Authorities commissioning procedures Run!W11er Commission

Cil}' of Hobart

Momington Peninsula

Ballarat Water Boanl

Water Board

Victoria

Fngineering and Wau:r Supply IJqx

Melbourne and

Adelaide

Metropolilln Board of Works

Water Authority of WestemAwtralia

YES

YES

YES

YES

YES

YES

YES

~t~~-urcuscd

Most mains are uPVC, thcref~

Main filled and immediately flushed,

Awh for minimum

water is clear with

swabbed and flushed.

ot IS minutea.

No CJtablisbcd procedure for

flushing oontinued

no discoloration.

Main charged and hydrostatieally tested. Then flushed

Mains<82Smm

uPVC procedure as below used.

(!)Disinfected with c:hlorine for minimmi c:l4houn

Main flushed until

m communorung new

mains

other materials.

(2)Main flushed.

until water is clear

pH measured for large diam. cement·

Is there an established flushing technique for commissioning new

maim

and free of sediment.

Mairu>825mm swept and squccgicd

with chlorine

solution until virtually all chlorine exhausted and any sediment removed.

clean .

or wcdcly flushing continued until pH

NO

YES

YES

(to be introduced on mains >22.S mm).

Only in metro. area.

But only for rnairu >225 mm. Mains<225mm currently under review.

lined mains and daily values are nonnal

Disinfection used as a regula~ p~urc when comm.us1c:mng new mains

NO

Additional flushing techniques authority may be prepared to use

Air scouring, swabbing, disinfection.

More cmphuis on velocity of lhe scour flush.

Air scouring, swabbing, disinfection.

Air scoring, swabbing, disinfection.

Is there a special

YES

YES

YES

YES

YES

NO

flushing technique for commissioning new uPVCmains Procedure used in commissioning uPVCrnains

NO

Longer flushing times.

NO As ooly lead-

YES

YES

free or low-lead

uPVC pipe used. Two alternatives:

(!)Main flushed and then following minimum flow oonditions maintained.

DAYl-3: 2 water changes/day.

DAY4-10: 1 water change/day.

DAY 11-17: 0.5 water changes/day. DAY 18-24:

tiil':::!~;wexn':"d

A1perRWC

AsperRWC ti')bi:!i'ri~::d ~;a;:~r;r 4 weeks. Main flushed

~:;:;::a~•,:rr 4 wcclc1. Main flushed for 1 hour mDAYlpriorto ciWings allowed.

fort hourbnDAY 1 priortouppings

allowed.

!i!e~•m.1;:nowed

·~1sallowed after A 14.

,

~~:~~~~::::t'!:?·1

or (2)Altem11ive flush routine: (a)flu shmain, (b)flush again 1 day after filling, (c)flush again I wk after filling , (d)flush again 2 wks after filling, (e)flush again 3 wks after filling, (f)final flush 4 wks after filling . No tappings until after DAY 21.

Hunter District Water Boa.rd

~':'La: District

W•er Rc,ourccs Comm.inion of

W•erBoard Sydney

Public Works NSW

Cil}' of Launcestat

Power and Water

Authority

Queemland Is there an established

fi'>M~"::~~:

procedure not used.

Northern Territory

YES

YES

YES

YES

YES

YES

YES

Mains flushed lDltil all air

Flushed until supply is clear and there has been a complete change of water in main.

Fill pipe with water velocity

<0.05 m/s. Flushing

Main swabbed and

Pipelines cle.-,ed

then flushed ..uil water clean. Main

to satidaction cl superintendent.

Main flushed until water clean. Main disinfected for 24hrs and then

Mainhydrostatically tested then flushed and disinfected.

done by scouring at all low points and dcadends. Mains other than raw water mains disinfected by continuous feed or slug method for 24 hrs and 3 hrs respectively.

disinfected for 24 hn, then flushed until all

:::n~::r

YES

YES

flush~g !Ut:irtlque for c:ommi111001ng new mains ~rtfflt~~-urcused m communomng new mains

Disinfection used as a rcgula~ p~urc when comm1ss1omng new mains

purged.

NO

all mains >200 mm.

YES

YES

YES

YES

YES

YES

ti')bi~~'ri~a:..i"of

ti'>~~w~

But not for raw water mains .

Whatever is neoeuary to achieve desirable quality levels.

Additional flushing techniques Authority may be prepared to use Is there a special flushing technique for commi11ioning new uPVCmains

NO

flushed.

chlorine removed. Microbiological

YES

YES

Airsoouring, swabbing.

YES

NO for pipes manufactured using non-lead-based stabiliser/lubricant ~;;other pipes

Procedure used in ocmmissiooing uPVCrnains

AsperRWC ti)fui~!~~~?of 2 water changes per day maintained for 4 weeks. Main flushed for 1 hour on DAY I prior to

(2\ttf:i;r:,~i; 15 minut~ . Tapping• allowed after DAY 14.

As perRWC except

As per RWC for

monitoring to ensu~ that lead conocntntions are

lead-based 1tabilised pipes.

<O.0S mg/1 iullo allowed.

i;~;!8Ci~s,:rr 4 wks. Main flushed

forlhronDAY 1 prior to tapping, allowed.

~=

arc 50% higher.

~~)c~~w~ ~~ procedure not used .

(2)Repeated flu1h

(2)Samples ween

tedmiquc not used.

for lead analysis at end of each week in the4-wcek flushing period.

~;,'bt'/::11owed

WATER February 1991

33


limited, as indicated in Table 1. Only two of the authorities contacted in Australia have established procedures where mains are routinely swabbed as part of the installation procedure and no responding authority uses air scouring routinely although several are currently investigating its use. It is clear from the literature that all new water mains should undergo a procedure which involves • a method of removing all construction debris (high velocity flushing, swabbing and a ir sco uring are suitable) , and • disinfection of the cleaned main. While most Australian water authorities have not used procedures of this type, increasing emphasis on water quality is likely to result in the adoption of improved commissioning procedures in the future. In their investigation of commissioning procedures for new uPVC mains, Burn and Sullivan (1990) included tests of a procedure for lead removal, which could be suitable for commissioning of all new water pipelines. This procedure involved • flushing the main at 2-2.5 mi s for 15 minutes, • allowing water to stand in the main for 15 minutes followed by swabbing with a series of three foam swabs, and · .• disinfection of the main for one hour followed by a further swabbing of the pipeline. (While longer periods would normally be required for proper disinfection, the one-hour disinfection was chosed to match the times used in an earlier laboratory study.) After commissioning, water was left stagnant in the pipeline for 14 days with no services connected, and samples were taken for analysis each day. The lead content of each sample was determined and the results are shown in Figure 1, together with the results obtained in a laboratory study where a pipe sample underwent a pretreatment involving three complete changes of water at 15-minute intervals before being filled with water and allowed to stand for 14 days. Neither the laboratory pretreatment nor the field procedure removed all the extractable lead from the pipes. However, the laboratory results showed that even when water remained stagnant in a pipe for 14 days after the pretreatment, the lead level in the water did not exceed the WHO guideline value of 50 ppb. The results from the field trial were more variable and the WHO guidelines value was slightly exceeded several times during the 14 day stagnant extraction period. Burn and Sullivan (1990) suggest a number of causes, such as the effect of swabbing method, use of chlorine, pH, pipe length and the method of taking samples, which could account for the difference between the laboratory results and the field results. If the need for proper commissioning of all water mains is accepted then commissioning of new mains constructed from leadstablised uPVC pipes should not be very different from the methods used for mains laid in other materials. While the possibility of temporarily high lead levels in water supplied from lead-stabilised uPVC pipes provided the incentive for a review of commissioning procedures, increasing emphasis on water quality will mean that standardised commissioning procedures are likely to be introduced for all new pipelines in the future. Because a procedure which is capable of removing construction debris and disinfecting a main can also significantly reduce the lead levels in water which has been in contact with lead-stabilised uPVC for long periods, it is possible that water authorities will review their policy of specifying "no-lead"

or "low-lead" uPVC pipes once the need for commissioning of all pipelines is recognised.

CONCLUSIONS A survey of Australian water authorities has indicated that whilst all authorities use a common flushing technique for lead-stabilised uPVC pipe to ensure that the lead levels extracted are below WHO guidelines, they do not use a common flushing technique for all types of pipes. Analysis of previous work has indicated that a satisfactory flushing routine should comprise at least a high-velocity flush and a disinfection routine. Laboratory work has shown that if these techniques are combined with a flushing routine comprising three turbulent water changes, then a standard flushing routine could be adopted that is suitable for all pipe types and still ensure that the levels of lead extracted from lead-stabilised uPVC pipes do not exceed the WHO guideline value of 0.05 mg/I at any time during a 14 day post-commissioning extraction.

ACKNOWLEDGEMENTS The authors wish to thank the Australian Lead Development Association for partial funding of this work, the Australian Water Research Advisory Council, also for partial funding of this work, and all water authorities for their participation.

REFERENCES American Water Works Association (1986). AWWA Standard for Disinfecting Water Mains. ANSI/AWWA C651-86. Buelow, R.W. (1976). Disinfection of new water mains. Journal AWWA, 68(6), 283 . Burns, L.S. and Sullivan , A.P. (1990). Commissioning procedures and their effect on lead levels in water from new uPVC reticulation mains . Australian Water Research Advisory Council Research Project P87 /21. Elvidge, A.F. (1982). Air Scouring of Water Mains - A Method of Operation. Water Research Centre, Technical Report TR 179. Major Urban Water and Sewerage Authorities of Australia (1987) . Cleaning and Disinfection Practices for Water Mians. Specialist Workshop No. 21, 9-11 Nove mber, Melbourne. Metropolitan Water Board (1968). The Chlorination of Mains and Service Reservoirs. MWB, New, River Head, Rosebery Ave., London. National Water Council (1979). Water Supply Hygiene: Safeguards in the Operation and Management of Public Waterworks in England and Wales. Occasional Technical Paper Number 2, NWC, London. Natural Resources and Environment Committee (1986). The Use of uPVC Pressure Pipe for Water Supply Purposes in Victoria. Natural Resources and Environment Committee, Parliament of Victoria. Packham, R.F. (1971). The leaching of toxic srabilizers from unplasticized PVC water pipes: Part II -A survey of lead; Section I!. Levels in uPVC distribution systems . Water Treat Exam, 20, 144-51. Phey, B. (1987). Experience with air scouring of water mains. Paper presented at Specialist Workshop No. 21, Cleaning and Disinfection Practices for Water Mains, 9-11 November 1987, Major Urban Water and Sewerage Authorities of Australia, Melbourne. Plastics Institute of Australia (1979). The Lead Content of Potable Water Carried in Unplasticized PVC pipe. Report by the PVC Pipe and Fittings Division. Richards, T.J. (1987). Lead levels in water resulting from contact with uPVC pipe. Australian Water Resources Counci l, Water Technology Committee, Workshop on Pipeline Materials Options, July 1987, Melbourne. Taylor, W.E . and Whiskin, L.C . (1951). The disinfection of water mains after laying and carrying out repairs. J Inst Water Eng,3 ,219-68. Wagner, I. (1988) . Flushing of Drinking Water-Installation Pipes. Result of a research program for DIN 1988/ TRWI, Karlsruhe. Williams, R.C. (1986). Distribution system disinfection. AWWA Conference on Water Ch lorination Principles and Practices, June 22, Number 2008. World Health Organisation (1984). Guidelines for Drinking Water Quality. Volume 1: Recommendations. WHO, Geneva.

8

WHO recommended level

/

ADVERTISING DISCOUNT Members of AWWA are entitled to a 10% discount for advertising placed direct through Appita Headquarters.

YOUR AWWA MEMBERSHIP WORKING FOR YOU!

2

2

4

6

8

10

Extraction Period {days) Fig 1. - Field versus laboratory extraction 34

WATER February 1991

12

14


BATEA and Secondary Treatment Hardwood Pulp Mills can be Environmentally Safe. A report by Bob Swinton. CONTROVERSY The controversy over the environmental effects of both established and proposed pulp mills rages violently in the media, with hidden agendas based on NIMBY and conservation of native forests intruding into the polemics of pollution. There is little doubt that both confusion and fear reign in the minds of many people about the effect of chemicals with such dreadful names as 2,3,7,8 tetrachlorodibenzo-p-dioxin. There is also little doubt that it is economically rather silly for Australia to export millions of tons of woodchips overseas, and then pay premium prices for importing the paper produced. Value-added production is the message for the economic stability of Australia in the future. None-the-less, the preservation of our environment is just as important, and pulp mills all over the world have had a pretty poor history in that respect over the last fifty years. WHAT OF THE NEXT FIFTY YEARS? All these aspects were ventilated at an International Conference ¡ on Bleached Kraft Pulp Mills, held in Melbourne in February. It was organised by CSIRO as part of the launch of the $15M National Pulp Mills Research Program. In December 1989 the Commonwealth Government adopted the Pulp and Paper Industry Package which contained the Guidelines for new bleached eucalypt pulp mibs. The Research Program, which is being managed by CSIRO for the Federal Government, is designed to enhance and further refine the Guidelines to ensure that minimal adverse environmental effect will result from effluent discharges. The Conference was open to the public, with invitations to the environmental lobbies. It enabled researchers, regulators and environmentalists to hear the considered views of sixteen speakers from the real centres of the pulp industry... Sweden, Norway, Finland, Canada and USA ... along with those of twelve speakers from the Australian and New .zealand industry and research groups. The Conference commenced with discussions on the Australian scene, with papers on pulpwood resources, cover~ng natural forests and plantations of eucalypts and softwoods, the differences between eucalypt and softwood, and the present size, scope and profitability of the industry. Currently, Australia produces of the order of 200 000 tonnes per year of bleached kraft pulp, a fraction of the output of the northern countries. Other papers ~onsidere_d the alternatives to the Bleached Kraft process, concludmg that 1t was unlikely that a significantly different process was feasible for the pulping of eucalypts to manufacture high quality paper. However, modifications to the basic process are not only being investigated, but are being put into practice as a means of reducing the amounts of chlorinated compounds produced as by-products. (For readers not familiar with the pulping process, suffice it to say that the wood is debarked, chipped, then cooked with a brew of alkaline chemicals which dissolve most of the lignin, releasing the fibres of cellulose. The fibres are screened off, and washed to some extent. The filtrate, in the kraft process, is evaporated to a tar and then burnt, leaving as ash which is worked up to be recycled as the alkaline brew for subsequent 'cooks'. However, the raw cellulose fibres are not suitable for manufacture of high quality, strong, paper. They must be treated in a multi-stage bleaching process, which typically uses oxygen, chlorine, chlorine dioxide and caustic soda. The residual lignin is oxidised to soluble compounds, some of which are 'chlorinated organics'. The various filtrates and washings from the bleach process constitute the bulk of the effluent to be discharged to the environment). TOXICOLOGY In following the discussions on the toxicology of such effluents, this writer gained the impression that although the toxicity of a large number of the chlorinated compounds is well-authenticated in laboratory trials, using somewhat enhanced dose rates, the actual toxicity of the total effluent in the field is not easy to assess, because of both synergy and antagonism. The most suspect compounds are the chlorinated phenolics, chlorinated dioxins and furans. The lower the lipophilicity, i.e. the lower the level of chlorine substitution, the less likely that there will be bio-accumulation in target species, but it has not been possible to correlate individual concentrations with overall toxicity. Consequently there are moves to utilise bio logical monitoring techniques rather than rely solely on chemistry. REDUCTION IN CHLORINE USE Since the discovery in the 70's that some of these chlorinated compounds were toxic to aquatic species, there h_as been a world 36

WATER February 1991

wide effort by the pulping industry to reduce the amount of elemental chlorine used in the bleach stage. Substitution of a large proportion of the chlorine by chlorine dioxide is the main advance, but other aspects such as elimination of the pentachlorphenol which used to be used to preserve stored logs from fungal attack, optimising the cooking process to remove more lignin without undue damage to the cellulose, less use of defoamers, better interstage washing, the use of oxygen in a pre-bleaching stage, and the conjunctive use of other oxidants such as hydrogen peroxide are all being applied to meet the effluent guidelines which are being enforced by all the countries involved. A recent Australian review of the chemistry involved was published in Chemistry in Australia. (Nielson, Aus 1990) REGULATION Speakers from Scandinavia outlined the progress which has been made in reducing the amounts of such compounds in pulp mill effluents. It is worth remembering that the Swedish pulp industry produces about 4 million tons per year of bleached pulp, (i.e. twenty times that produced in Australia) and discharges its effluents into lakes or into the relatively closed system of the Baltic Sea. Their neighbors, Finland and Norway, operate on much the same scale. The great majority of their pulp is made from softwoods, with high content of toxic resin acids. Once the toxic effects were recognised, the various agencies have worked with the industry to progressively reduce the quantities of chlorinated compounds discharged. In terms of 10Cl (total organic chlorine), the typical Swedish mill in 1970 discharged 5-6 Kg per tonne of pulp; in 1991 this will be reduced to 1.5 Kg, and the long-term objective is a fraction of 1 Kg. At the same time, the measures taken have drastically reduced the amounts of general pollution, in terms of COD and BOD. (It is likely that the overall effects of COD reduction may be more significant than the effect of chlorine reduction) EXTERNAL TREATMENT Such reductions, in all the main producing countries, have been made feasible only by a two-pronged attack. The changes to the mill processes contribute their share, but nearly all mills now also rely on secondary treatment. A number of papers discussed the use of aerated lagoons and activated sludge plants. In Canada, where geography may limit the area of land available even for _activated sludge plants, oxygen plants are beip.g installed, with costs of around $100M for a mill. In consequence, the water discharges from the mill are being stringently controlled, with the various effluent streams being separated. In biological systems, the fate of chlorinated compounds in the anoxic zones of lagoons and in mixed liquor is being measured. For further polishing, particularly for colour removal, investigations are proceeding into physico-chemical treatments. The concept of zero discharge has been tried both in Ontario and Scandinavia, but the build-up of chloride ions in the bleach process has proved to be insurmountable. It is accepted that zero discharge, even with irrigation, is many years away. CONCLUSION The representative of the Swedish EPA, Agneta Melin, quoted estimates for the discharge of 'dioxins' from various sources in Sweden. Whereas in 1987 their huge pulp industry was second only to incineration of domestic waste, by 1993 it will contribute only 8% of the total load, far below the contributions from car exhausts, steel industry and cement manufacture. She categorically stated that 'dioxin' was no longer a significant problem in the Swedish pulp industry. All in all, there is every reason to believe that use of BATEA ... best available technology economically achieveable... for any future Australian mill, both in the pulp mill itself, and in the external treatment systems, will result in no short-term ecological impacts. One purpose of the Research Program is to conduct monitoring of the environment to ensure that any long-term impacts will be detected early enough to allow remedial action to be taken. The high standards of environmental protection set by the Commonwealth Guidelines were praised by the overseas regulatory scientists.

INTERNATIONAL CONFERENCE ON BLEACHED KRAFT PULP MILLS Proceedings at $100 per copy available from C.J. CROSSLAND CSIRO, INRE Project Office P.O. Box 225 Dickson, ACT 2602 Phone (06) 281 8480 Fax (06) 281 8436


TWO RELEVANT PUBLICATIONS Waste Management Technologies-Opportunities fo.r Research and Manufacturing. (Liquid Wastes) A report issued by the Department of Industry, Technology & Commerce, Exploitable Science and Technology Section, and compiled by Brian O'Gallagher, August, 1990. This 112 page review is another of the excellent DITAC series on emerging areas of science and technology, and is linked with the AWWA study on "Commercialisation of Technology for Urban Water Supply and Sewerage Systems" (1990) . A similar review of solid waste management technologies is currently underway. The thrust of the report is the encouragement of Australian companies and research organisations into further development and marketing of their expertise in this field, for applications within Australia and for possible export. Section I is an overview of the scale of generation of wastes in Australia from both domestic and industrial sources, and Section 2 assesses the market potential of the waste management industry. From the variety of figures quoted in the world market is certainly of the order of $100 billion, and, at 7.5% per year, is one of the world's strongest growth industries. In one field alone, the Sydney Water Board has made estimates for the world market in the field of tertiary sewage treatment as $65 billion capital over 20 years, with a projected annual expenditure of $5 .3 billion. For waste management as a whole, a reasonable estimate of the potential export market for Australian companies would be in the region of $6 billion per year within ten years time, of which a significant proportion would be in wastewater technology. Section 3 reviews the established waste management technologies, biological, chemical and physical. Section 4, some 30 pages, is perhaps the most interesting. It summarises Australian capabilities and technological developments, both in science and manufacturing. Appendices 1 and 2 are part of this section: one lists the research organisations involved in this field, with contact names and project description, the other the companies involved in the manufacturing or technological development, in Australia, of liquid waste technology, and those involved in the provision of services, i.e. consultants and contractors. Section 5 international developments. Section 6 discusses the opportunites for research and manufacturing. The legislative and political drive towards environmental improvement is briefly covered, then the opportunities in strategic planning and management for consultants, laboratories, management companies, government authorities and educational institutions. The technological opportunities are outlined in some detail, first by two lists of perceived problems, secondly by a restatement of material from the AWWA study, divided into subsections: chemical technology, waste recovery and recycling, sensors, magnetic separation/floccu lation, membranes, biotechnology, instrumentation and control, information and communications. The summary states: "Australia has the research expertise and manufacturing capability to capitalise on many of the opportunities identified in these areas of technology. However, Australia must be competitive on the world market if it is to reap the benefits of these opportunities. To achieve this level of competitiveness on a broad scale in the field of waste management, greater cooperation between Australia's manufacturers and researchers and better coordination of their efforts is essential. Copies of the Report are available from DITAC. Contact Ms. D. Sharp, 06-276 1229.

A Review: Industrial Wastewater Treatment Technologies The Environmental Protection Authority of Western Australia commissioned Sinclair Knight & Partners to review the latest methods of industrial wastewater treatment, to assist the Authority in its advice to industries, particularly to help make informed judgements on development proposals. The result is not a text book, it is a valuable information base, not just on well-established treatment methods, but on state-ofthe-art technologies which show promise, but are not yet in full operation. It claims to cover the field in layman's language, suitable for reference by professionals not immediately concerned with wastewater treatment and it is fairly successful in that respect. The review is divided into five sections: • Waste minimisation • Established and non-proprietary processes • Non-proprietary state-of-the-art processes • Some processes under development.

Waste Minimisation The basic concepts are discussed, and well illustrated by an ironic example of steps which could be taken to minimise wastes and increase revenue at a fictitious plant (Moocow Products, Algalbloom, on the River Greenslime).

Established and Non-proprietary Processes These range from solids separation, biological treatments (including ponds and aerated lagoons) to chemical additions. They are summarised in 10 pages of basic information outlining the advantages and limitations of each system, followed by a short but useful bibliography.

Non-proprietary Methods of Nutrient Removal Biological nitrogen removal: it is emphasised that removal from domestic wastewater is well established, but very little data is available for industrial wastewaters. Having described the basic chemistry/ biochemistry of nitrification/ denitrification, the review covers the various processes which have been developed: fixed film denitrification, column reactors, fluidised bed reactors, anaerobic rotating discs, recycle of anoxic sludge in activated sludge processes, variants of channel systems, intermittently decanted systems, both channel and deep tank, and arrangements for anoxic zones within the activated sludge system. Advantages and disadvantages of each are discussed. Biological phosphorous removal, chemical precipitation is <!overed first, followed by a brief summary of the biological enhanced phosphorus removal systems which were first developed in South Africa, and are now in operation in Australia. However, it is emphasised that no industrial installations are in operation .

Proprietary State-of-the-Art Processes The section is the major part of the review. SKP contacted as many equipment suppliers as they could to supply details of their processes. Less than half those contacted did so, so it is admitted that the list cannot be regarded as comprehensive, but the information disclosed will be of interest to many professionals who are already familiar with the basics of treatment as summarised in the preceding sections. From the replies, SKP prepared considered summaries of the following aspects: process name, company background, e.g. local developer or importer, and contact names; a full process description, suitable applications and principal advantages, unsuitable applications and major drawbacks, alternative methods, feed quality limits, sensitivity limits, characteristics of waste streams) and disposal options. The current status of the process, such as a list of full-scale installations, or whether it is under development, is then followed by estimates of land requirements, operation and maintenance and cost data. The processes covered are: Golconda IPC, DHV Crystal Pellet Reactor, Memtec CCMF, Campbell Hybractor, Aquatec-Maxcon UASB and Biocarbone, ABJ's ICEAS, SEPA's DAF, SOLVIN Electroflotation, Austep's SIROFLOC, CSIRO's CIX, UV Technology's Disinfection, SEPA's plate separator, QUANTEK and other plate separators, Activated Carbon.

Promising Technology This section is an eclectic literature review of novel processes not yet in operation which could have possible applications in the future to various industrial waste streams. Copies of the Report are available for $10 from EPA Environment House, 1 Mount Street, Perth 6000.

38

WATER February 1991


TECHNICAL NOfES:

Blockage of Piggery Effluent PipesA Magneto-Hydrodynamic Solution by Dr. D J LWYD, Technical Director, Dynmag Pty. Ltd. SUMMARY Flat plates of PVC, aluminium and steel were immersed in the flow of effluent from lagoons treating piggery effluent. Struvite crystallised as a scale on all plates. When a magneto-hydrodynamic device (MHD) was operated in the flow ahead of the plates, the rate of scaling decreased over time to virtually zero. Similarly, plates which were already heavily scaled were gradually descaled over some 26 weeks. A pilot plant trial using piggery effluent, but dosing extra quantities of magnesium and ammonium phosphate, demonstrated that the rate of scaling was a function of the strength of the magnetic field.

Trial 3. Two plates each of PVC, aluminium and mild steel were immersed in a tank, 6 m long, 1 m wide and 0.5 m deep, through which was maintained a continuous recycle of piggery effluent for a total of 48 hours. The recycle stream passed through the magnetohydrodynamic device. Extra magnesium sulfate and ammonium phosphate solutions were added continuously to maintain the conditions listed in Table 3. Three runs were operated, each for 48 hours, with the MHD set at zero gauss, 600 gauss and 1200 gauss. The scales deposited on the plates for each 48 hour run were scraped off, dried and weighed. The results are reported as grams of dry scale per square metre of wetted surface per 48 hours, and are summarised in Table 4.

INTRODUCTION Magneto-hydrodynamics involves passing a fluid under turbulent conditions through a strong magnetic field . (Chem Rev, 1989). It has been reported world-wide as a useful method of reducing scale, and indeed, of removing existing scale, from boilers, heat exchangers and water supply piping (Cosgriff, 1989). Useful effects on microorganisms and industrial colloids have also been reported, provided that the equipment is adequately designed for the application. (Lloyd, 1990, Lobley, 1990) In treatment plants for some piggery and other animal house effluents, scaling of effluent pipelines and structures by struvite, magnesium ammonium phosphate, can be a problem. Struvite is formed from the phosphates in the wastes, ammonium ions formed in anaerobic conditions, and magnesium emanating from either the water supply or food additives. It was decided to test the antiscaling effects of a magneto-hydrodynamic device on this type of scale. The device used in this study was a modified version of commercially available Turbomag equipment.

WCATION The piggery chosen for the experiments is operated by Wandalup Farms (Western Australia), a subsidiary of George Weston Foods Ltd. The effluent treatment at the site consists of a strainer for removal of solids, followed by three digestion ponds. The growth of struvite was most noticeable in the surrounds of the third pond and its outlet, which was a concrete channel and well, showing struvite growth commonly 25-50 mm thick.

EXPERIMENTAL PROCEDURE Three trials were operated, on three types of surfaces. Flat plates, 600 mm by 400 mm, were made from PVC, aluminum and mild steel, and these were partially immersed in the concrete outlet well. The MHD was installed upstream of the test channel, the effluent being pumped through the device, and the electromagnet being turned on and off according to the schedule reported for trial No. 2. Trial 1. Three plates were immersed in the channel to a depth of 90 mm, by 400 mm parallel to the direction of flow, and maintained undisturbed for 8 months prior to the commencement of the MHD trials. All plates became heavily encrusted with struvite. The MHD trials were then commenced according to the schedule reported for trial No. 2. The wet weight of the plates and accumulated scale was measured at intervals, and the wet weight of scale reported as kg/ m2 of wetted surface. The MHD trials were continued for 44 weeks. The scale gradually disappeared. Results are summarised in Table I. Trial 2. Three plates were immersed in the channel to a depth of 90 mm, by 400 mm parallel to the direction of flow. The MHD was turned off for the first 7 weeks, then on for 6 weeks, off for 8 weeks, then on for 23 weeks. At approximately two-week intervals the plates were removed, scraped free of scale, and the accumulated scale dried and weighed. The results were reported as rate of growth of dry scale, in grams per square metre of wetted surface per day, and are summarised in Table 2.

RESULTS Trial 1. Table 1. Descaling of surfaces immersed in piggery effluent. Time,

MHD

weeks

Status

PVC

Al

MS

off off on off on on on on on

2500 2500 2500 2500 1400 1100 400 0

heavy scale 2500 2500 2500 2500 1100 400 400 0

3600 4300 5000 5000 2500 700 700 0

32 PWS7 13 21 27 31 35 38 44

Wet scale and occluded organic matter, g/ m2

Table 2. Scale growth on surfaces immersed in piggery effluent Time

MHD

weeks

status

3 5 7 9

Scaling growth rate g dried scale/m2 / day

off on

11

13 15 17

off

PVC

Al

MS

10.7 13 .0 12.4 5.6 5.5 3.8 7.4 6.9

12.9 13 .6 7.5 7.3 4.9 3.6 6.2 5.0

13.9 13.2 10.2 9.6 5.6 2.6 5.7 4.7

4.2 8.1 4.1 4.3 2.6 1.7 1.5 0.8 0.8 0.2 0.1 0.1

3.7 7.9 3.7 5.0 2.9 2.3 2.7 I.I 0.9 0.3 0.1 0.2

3.7 9.7 2.9 7. 1 2.5 2. 1 2.2 1.7 1.3 0.3 0.1 0.2

heavy rain 19 21 23 25 27 29 31 33 35 38 40

on

44

Table 3. Conditions during recirculation trials Volume of tank Circulation rate Plate size (6 off) MgS04 addition (NH4)2S04

3000L 25 L/min 600 x 400 mm 20 mL/min @ 390 g/ L 20 mL/min @ 210 g/ L

Table 4. Scale Growth in recirculation trials MHD Field strength

Scale growth in 48 hr g/ m 2

gauss

PVC

Al

MS

zero 600 1200

5.8 5.4 2.9

8.3 5.4 3.7

10.4 11.2 3.7

WATER February 1991

39


DISCUSSION Nature of scale: Struvite normally forms needle-like crystals 8-10 mm long, which occlude water and ¡organic matter giving them a dark appearance. When the MHD was operating, small crystals, powdery in nature, were formed. In trial 1, the previously deposited scale softened into a mud-like texture before it was stripped off by the flow . In Trial 2, once the MHD had achieved its full potential the material depositing on the plates was organic only. (The very high rainfall experienced during week 18 reduced the concentration of effluent in the ponds which presumably reduced the rate of natural scale growth). During trial 3 the linear flow rates in the tank were below turbulence levels. Some of the material on the plates was only loosely attached, and could have been washed off by higher flowrates, but the trial demonstrates that an adequate magnetic effect is essential. In all the results demonstrate clearly that given time and adequate design parameters, a magneto-hydrodynamic device can change scale from adherent crystal growth to a soft mud. This has been attributed in previous literature addressing calcium scales to the formation of active nuclei and crystallisation in suspension rather than deposition on surfaces. The slow removal of existing scale was also demonstrated. It should be recognised that this study was carried out in the conditions in existence at the particular site. At other sites there may be different conditions, and seasonal variations may also affect the result. However, the body of literature on anti-scaling by MHDs suggests that successful application to struvite scaling is feasible. The benefits extend beyond pipe blockage. If irrigation of such effluents is practised, blockage of nozzles would present a serious problem both for maintenance and for control of application. If recycling of wash waters is practiced, then continuous removal of the struvite would be essential. (Note that solid struvite collected from a settling tank would have value as an excellent fertiliser) The reduction in phosphate concentration in the final effluent may be of value in some circumstances. ACKNOWLEDGEMENTS The author thanks Wandalup Farms and the assistance of Dr Robert Wilson and Mr Mike Irvine. REFERENCES Chem Rev (1989) Vol 89 p 51. COSGRIFF A A (1989) Maintenance Australia & New Zealand Vol 2 (3) p 40 . LLOYD DJ (1990) ibid Vol 3 {I) p 2. LOBLEY J M (1990) Proc Maintenance Management Conference , Sydney, Melbourne, Aug .

EDITOR'S NOTE The subject of the influence of magnetic fields on flowing fluids is beset with controversy. It has been labelled "gadgetry", not sustainable under scientific scrutiny, but nevertheless, there are many reports of its apparent success, particularly for reduction of scaling due to calcium carbonate and sulfate and various phosphate liquors in metal treatment industry, and even for the dissolution of existing scale in heat exchangers and piping. The Technical Note above is a report of trials of a magnetohydrodynamic device for the prevention of scaling by another compound, struvite, in the highly anaerobic (and odorous!) sludges discharged from a piggery. This compound, magnesium ammonium phosphate, also crystallises in municipal anaerobic digesters when sufficient of the three ions is present. It has made its presence felt in digesters treating the phosphorus-enriched sludges from biological phosphorus removal systems, where research suggests that the presence of sufficient magnesium in the activated sludge reactors is essential for the Acinetobacter spp to take up phosphorus (see BNR 1 report, August, 1990). In the subsequent anaerobic digester, the necessary ammonium ions are the normal result of the anaerobic conditions. The Editor must confess that he was hesitant about publishing Dr. Lloyd's report, because of the accusations of 'magic' which have always been levelled at magneto-hydrodynamic devices, which all too frequently in the past have been over-sold. However, he was referred to the paper presented to the 1990 Maintenance Management Conference, August, (Melbourne and Sydney), by J.M. Lobley, the pragmatic Projects Engineer, of SEC Latrobe 40

WATER February 1991

Valley, Victoria. Lobley, in reporting on the success of such a device (not one supplied by Dynamag) in a plant-room air-conditioning heat exchanger, went to the trouble of conducting a literature search on the subject. He unearthed recent papers from reputable University research teams. One presents conclusive data showing that high speed passage of a supersaturated solution through a magnetic field of sufficient strength changes the tendency for calcium carbonate to crystallise not as hard calcite scale, but rather as aragonite, either in suspension, or as a soft deposition . This phenomenon is ascribed to the formation of submicroscopic nuclei in the solution, with active or charged crystal surfaces. Unfortunately, the various papers differ in their explanations, but all call for further research to elucidate the phenomenon, which some say may have much wider implications than anti-scaling. Such wider effects range from effects on micro-organisms, to demonstrated effects on industrial colloids. Dr. Lloyd, who gained his PhD in physical-organic chemistry, ascribes the effects to the absorption of energy which provides sufficient excitation of the atoms and molecules to accelerate chemical reactions, including the dynamics of crystallisation. Whatever the mechanism, it seems that, as yet, not enough is known either to guarantee, or to condemn, such devices on a scientific basis. Whether the pragmatism of engineers can lead to a satisfactory design basis is another matter. Such advances are well-documented in the past, for example, biological enhanced phosphorus removal was developed by the engineers long before a microbiological rationale was suggested.

TECHNICAL NOfES:

Milli-Screening in Aquaculture: Use of Disc Filters by A. Van Huissteden (Technical Manager, Saltas). The 'Saltas' Atlantic Salmon farm, at Wayatinah, Tas., operates a hatchery with the capacity to handle and incubate several million salmonid eggs per year. The hatchery consists of 42 incubators and 42 troughs for the sac-fry, and demands a constant supply of clean filtered water, at 70 L/ s. This water must be almost free of organic matter and suspended solids, which would settle on top of the eggs, thereby reducing the yield of fry. The water source is the Derwent River, which at Wayatinah is subject to flash floods, bringing down large quantities of decomposed organic matter and silt. The TSS can be 200 mg/ L of which 60% is between 55 and 25 microns. For three years the farm sought a system which could reliably screen the water. Rotary self-cleaning screens were tried, but the 'greasy' texture of the deposit blocked these screens within a few minutes. The screens automatically backwashed themselves, but the proportion of backwash to product escalated to uneconomic proportions. Two Arkal 3 inch SPIN-KUN disc filters were then installed for a trial, and proved so successful that a battery of 12 were purchased. The first strainers installed had a nominal aperture of 25 micron, but trials showed that a set with a nominal aperture of 45 micron reduced TSS by 800Jo with very little of the suspended solids being above 25 micron. This has proved to be suitable for the hatchery. The pressure drop is about 10% of the upstream pressure of 250 kPa and the system has operated simply and reliably over a period of two years to date. (SPIN-KUN filters are grooved disc strainers, which possess 15mm of screening depth between the elements, thus providing a high capacity for fine particles before backflush is needed. The difficulties of back flushing such strainers are overcome by a system of reversing the hydraulic pressure to overcome the spring which holds the elements together, and also by injecting the backwash water from the centre of the element at an angle which causes the loosened discs to spin at high speed. After a cleaning cycle of 10-15 seconds, the normal flow pattern is restored and the discs are pressed together again. A range of apertures from 25 micron to 300 micron is available. They are distributed by Koor Irrigation and Filtration Pty Ltd (02) 662 8811, and have been applied world-wide in mines, food processing, chemical plants and agricultural applications) .


(___O_O._fl_'F._'ER_E_'Ni_CE_CA_L_E._'ND._!JIR _ _) For further information please contact AWWA Secretariat P.O. Box 388, Artarmon NSW 2064 Phone: (02) 413 1288 Fax: (02) 413 1047 AUSTRALIA March 17-22 - Perth AWWA Biennial Convention April 7-11 - Hobart . National Conference Institution of Engineers Australia August 18-19 - Cairns Mining and Mineral Processing/ Environment August 25-30 - Hobart Local Government - Management of assets and environment October 2-4 - Perth International Hydrology and Water Resources Symposium October 6-7 - Perth Site Remediation Workshop October 9-11 - Adelaide Engineering Management November 27-28 - Perth Appropriate Waste Management Technologies i992-March - Sydney 4th National Conference on Hazardous Wastes 1992-November - Sydney Constricted Wetlands for Wastewater Treatment

OVERSEAS April 3-5 - Portugal, Lisbon Marine Disposal Systems IAWPRC April 14-17 - USA Houston Computer Specialty Conference American Water Works Association April 15-19 - Spain, Canary Islands, Tenerife, Puerto de la Cruz XXIII International Congress of the lnternation Association of Hydrologists - Aquifer Over exploitation April 15-20 - Malta Desalination & Water Reuse April 22-25 - Belgium, Ostend Environmental Biotechnology April 24-26 - England, Manchester Urban Waterside Regeneration Conference & Exhibition April 30-May 2 - England, Birmingham IWEM 91 International Conference & Exhibition - Water & The Environment May 5-8 - USA, Kansas City, Mo. North America No-Dig '91: Sewerage Rehabilitation. (WPCF) May TBA - South Africa, Johannesburg Water Institute of Southern Africa & 2nd National Water & Wastewater Conference & Exhibition May 12-18 - USA, Texas, Houston 4th International Symposium on Land Subsidence May 12-16 - Brazil, Sao Paulo Sixth International Symposium on Anaerobic Digestion May 13-19 - Morocco, Rabat Vllth World Congress on Water Resources, IWRA May 21-24 - Hungary, Budapest Measurement of Water Quality May 25-31 - Denmark, Copenhagen 18th International Water Supply Congress & Exhibition June 3-6 - USA, New Hampshire, Durham 2nd International Conference on Watermatex 91 IAWPRC June 9-15 - West Germany, Frankfurt ACHEMA '91 June 23-27 - USA Philadelphia ,American Water Works Association Annual Conference August 12-15 - Sweden, Stockholm Water Resources in next century August 26-30 - Czechoslovakia, Prague Design & Operation of Large Wastewater Treatments Plants, IAWPRC September 8- 11 - USA Atlanta Distribution System Symposium, American Water Works Association September 24-26 - Spain, Costa Brava, Castell Platja d'Aro International Symposium on Wastewater Reclamation & Reuse, IAWPRC October 6-10 - Canada, Toronto International Conference on Groundwater Protection November 10- 14 - USA Fla, Orlando Water Quality Technology Conference American Water Works Association

The Association welcome details of conferences and exhibtions for inclusion in the diary pages of Water. Please send all relevant details, including date, venue and contact to: AWWA Secretariat, PO Box 388, Artarmon NSW 2064 Facsimile (02) 413 1047. 42 WATER February 1991

ZERO DISCHARGE FROM CHEMJCAL PLANTS continued from page 23 The Plantations Planted in east-west rows, each block has an initial tree density of 1667 trees per hectare. Saplings are 2 meters apart in rows 3 meters apart. The seedlings were all new season's stock to ensure vigorous establishment. Trees for the main plantation were selected on proven performance in irrigated conditions, performance in basalt soils, and capacity to maintain high evapo-transpiration rates to match the anticipated flow of effluent to be disposed of, so as to prevent undue movement to the groundwater. A mix of species was required to avoid monoculture problems, and there was also a requirement that the trees be aesthetically pleasing, and also have a cropping potential. Ten thousand each of the following species were chosen: Eucalyptus Globulus (Tasmanian Blue Gum) which was tested at the Melbourne Board's Werribee Farm, but is confined to betterdrained areas . Casuarina Cunninghamiana (River She-oak) performed well during the tests, is visually attractive_, and has the advantage of low flammability and toleration of winter inundation. Eucalyptus Grandis (Flooded Gum) performed well, and is highly adaptable. Eucalyptus Botryoides (Swamp Mahogany) can also tolerate inundation. The 8000 trees in the perimeter plantations were chosen primarily for amenity ... or appearance. They comprise Golden Wattle, Coastal Wattle, Drooping She-oak, Scrub She-oak, Hop Bush, Swamp Paperbark, Salt Paperbark and Boobialla. A 20 m firebreak surrounds the plantation, and an annual maintenance plan, combined with the choice of smooth barked species, will reduce the fire risk. Two blocks of the economically valuable Eucalyptus Globulus have been dedicated to an experiment run by the CSIRO Division of Forestry. Thinning will be controlled to select the best trees for particular habitats, and seed from the orchar.d will provide the basis for superior plantings not only in Australia but overseas. Commissioning Zero discharge was achieved in July 1990, with wastewater storage being built up in the new dams. The water demand is low for the saplings, but is compensated for by the high evaporation from the bare soil. As canopy closure is attained, evapotranspiration will take over. Economics The establishment of this plantation is the first in Australia to use wastewater from a chemical manufacturing plant. Dow is incurring an investment of$ l .3M. This cost in the long term will be offset by the avoided charges for sewerage, but the company considers that the intangible benefits of community harmony are also of as much value as an environmentally friendly solution to waste management.

REFERENCES HEALEY M J, CLEMENTS J W, PHILLIPS M J (1985) Proc I Ith Fed. Conv. AWWA, Melb. pp 329- 337. Mc KIE C J, CLEMENTS J W, GASKELL N. (1990) Proc I 8th Australasian Chem Eng Conf. ICE, Auckland.

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Water Journal February 1991  

Water Journal February 1991