Monitoring of aquatic macroinvertebrates has become a requirement of Victorian EPA treatment plant licences where point source discharges are released to streams, rivers and lakes. Macroinvertebrates such as mayflies and mudeyes are well known to anglers, are visible to the naked eye and are commonly found in rivers and streams. They are considered to be an excellent and cost-efficient indicator of river health.

Strict EPA protocols exist regarding the minimum effort required by treatment plant operators for in-stream monitoring and these are briefly introduced. These monitoring protocols outline appropriate sampling methodologies, site selection criteria and methods of data analysis such as SIGNAL and AUSRIVAS. Despite such directives it remains critical that studies are specifically designed to determine differences between macroinvertebrate communities upstream and downstream of treatment plants. Examples of such studies are given. The issues associated with the introduction of this new protocol from the project design to implementation and final feedback stage are outlined. The importance of baseline monitoring prior to treatment plant upgrade is also discussed.

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The wastewater treatment plants at Mooroopna and Tatura, operated by Goulburn Valley Water, receive food processing and domestic effluent equivalent to half a million people. The existing anaerobic lagoons at these plants needed upgrading to increase capacity, reduce odours and to improve the final effluent quality. High Rate Anaerobic Lagoon (HRAL) reactors were selected for this upgrade in preference to the more traditional upgrade methods of aeration or construction of additional primary lagoons to reduce organic loading rates.

At Mooroopna, the HRAL reactor has enabled the surface area of anaerobic lagoons to reduce from 39 to 2 Ha and in conjunction with the lagoon covers and a biogas flare, has significantly reduced odours. At Tatura, the odour has been almost completely removed following the covering of the existing 3 primary lagoons and flaring of the collected biogas. The efficiency of COD removal in the Tatura HRAL reactor has far exceeded design parameters and is frequently operating in excess of 90% reduction.

This paper discusses the challenges encountered during commissioning and provides some initial operational observations following the conversion of these plants to HRAL reactors.

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Several issues require careful consideration for the successful installation of membrane liners and/or floating covers to existing open water storage basins. For example: Membrane material type and colour; subgrade treatment for puncture protection and underdrainage; modification of existing inlet, outlet and overflow pipes/structures; maintenance of supplies to consumers during the installation and allowances for future operations and maintenance.

This paper discusses the key issues which require consideration in the implementation of water quality improvement projects using membrane liners and floating covers via the design and construct project delivery mode. Alternative means of addressing the key issues are given by reference to several recent projects.

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Concrete pipes and structures are an integral part of all sewerage systems. They are however susceptible to corrosion which, if not addressed, can ultimately lead to a failure of the system.

Concrete Access/Inspection Chambers are some of the assets where corrosion can occur, however it has also been observed within concrete pipes, sewerage pumping stations and sewerage treatment plants. These assets represent considerable financial investment by those in the water industry and need to be well maintained to obtain maximum operational life.

Since 1995 Barwon Water has employed various techniques to restore corroded Access/Inspection Chambers. This paper discusses the corrosion process and briefly outlines the various products/processes used at Barwon Water to undertake the rehabilitation of Concrete Access/Inspection Chambers.

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A Consultative Committee/Project Monitoring Team was established to assist in the implementation of the proposed sewerage scheme in the township of Koroit. This was not the first time South West Water Authority (SWWA), had used such a committee but a scheme the author was involved in from its inception.

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The Wastewater plant is an Intermittent Decanting Extended Aeration plant, currently servicing the City of Warrnambool and two small townships, along with several large Trade waste Industries. This paper describes the treatment process; the difficulties with dewatering the by-product of the treatment process – biosolids, and the pilot filter belt process we trailed in an attempt to produce a better biosolids.

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Currently there is no requirement under the Australian Drinking Water Guidelines to produce a stable water that is not potentially corrosive to water treatment plant equipment and reticulation systems. This paper discusses the concept of water stability, describes various indices available to gauge the corrosivity of a water and their methods of calculation. An approach is also outlined whereby the stability of water can be determined following a particular treatment regime and how it can then be conditioned to make it less aggressive. Using a worked example, these concepts are illustrated by examining treatment and conditioning of a typical water; the Waranga Channel supply at Rochester, Victoria.

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In early 1994, the newly formed Goulburn Valley Water inherited Tatura’s sewerage reticulation system and wastewater treatment plant (WWTP). The extremely poor condition of the sewerage system, and the insufficient treatment of waste by the WWTP instigated a seven million dollar upgrade.

Before the commissioning of the upgrade in October 1999, emergency discharges to Mosquito Depression were often required due to both insufficient irrigation area and winter storage. The upgrade was aimed at enabling zero discharge from the WWTP through the construction of a winter storage, and increased land for irrigation.

The challenge adopted by the Authority was to provide a long-term means of managing a wastewater load equivalent to a city of 200,000 people, in an environmentally sustainable way. This challenge involved developing treatment technologies appropriate to high strength waste, implementing appropriate trade waste agreements and initiating long-term reclaimed water reuse agreements with farmers adjacent to the waste management facility.

This paper discusses the operational problems experienced, and issues confronted by the Authority in the development and management of long term wastewater re-use practices.

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The concept of risk assessment is one, which is being increasingly used throughout Australia in the management of water supply systems and in the provision of safe and good quality drinking water. A number of the larger water authorities in major metropolitan centres and some rural Victorian and NSW water authorities are pursuing risk assessment as the accepted approach to scientifically evaluate pollutants and to develop protective public policies.

The mechanism by which the risk management process is being undertaken may vary from authority to authority but essentially follows the same principles. This paper describes the elements of a risk management exercise conducted at Goulburn Valley Water in relation to the drinking water supplies, the methodology employed, the water authority response to outcomes and the benefits perceived to have arisen from the approach.

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With all Victorian Water Authorities seeking to reduce costs and improve services more innovative ways are being sought to treat wastewater. Portland Coast Water have constructed a new wastewater treatment plant to serve the City of Portland in Victoria’s south west, designed to have very low operating costs. The plant, with a capacity of 4 ML/d, uses aerated facultative lagoons followed by engineered reed beds to provide a high quality effluent that is currently discharged to the ocean. The 6 ha of scoria filled reed beds are designed to polish the lagoon effluent by further reducing biochemical oxygen demand and suspended solids as well as reducing nutrient levels, particularly phosphorus. The plant has no daily production of bio-solids, is odourless, noiseless and creates no daily trauma for the operator.

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Gippsland Water is using particle counters to monitor and optimise the filtration performance at various water treatment plants. Working closely with the manufacturer of the Heyfield WTP, Gippsland Water used a portable particle counter to monitor the effects of operational changes at the plant. Valve ramping speeds, backwash interval and duration, and plant run times were altered to achieve a significant reduction in filtered water particle counts in the 2-15m size range. Major changes to the initial plant design have been undertaken in light of particle count results. Particle counters are progressively being used at all Gippsland Water WTPs to optimise final water quality.

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New Best Practice Environmental Management Guidelines for Wastewater Irrigation have been prepared for the Victorian EPA. These have focussed on identifying clear performance outcomes that need to be met to achieve sustainable irrigation. The risks that are associated with each potential site are assessed against twelve elements that impact on that sustainability. There are five elements that relate to the wastewater (and operator), wastewater volume, nutrients, salt & sodicity, other toxicants and viability.

The remaining seven relate to the protection of the environment at, or within, influence of the site. These are soil, surface water, groundwater, human & stock health, public amenity, native vegetation and cultural heritage. Practices are identified in the guidelines and change according to the risk level that exists at the site. The guidelines will have a framework for the development of an Environmental Improvement Plan (EIP); some information on the statutory support for the guidelines and a checklist of what needs to be assessed for each irrigation development.

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Food safety plans have incorporated Hazard Analysis Critical Control Point (HACCP) principles for many years now to control the risks of contamination. The main thrust of HACCP systems is to understand the risks associated with the process and start focussing process control away from end-point testing and towards control of the critical operations earlier in the process. The result is production with higher quality assurance and greater opportunity to correct non-conforming product.

This paper describes how HACCP can be applied to public drinking water supplies and demonstrates the way in which Melbourne Water has developed HACCP. It outlines the approaches taken to risk assessment and identification of Critical Control Points and the integration of HACCP within water supply operations.

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Assessment of the microbiological quality of potable waters by water utilities relies on the detection of E.coli and coliforms. In water microbiology, there have been relatively few changes in methods since the inception of water testing. Recent method updates have resulted in significant alteration to the methods as they have incorporated changes to coliform and E.coli definitions. Defined substrate technology describes the technology whereby the presence of microorganisms possessing a particular enzyme may be detected. Colilert is an example of such a test. This paper describes the new generation of tests and their impact on microbiological results. In particular, the impact of the use of Colilert on recent coliform data is discussed.

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Since 1996/1997, the EPA has imposed combined load limits on St Marys, Riverstone and Quakers Hill STP’s. The Quakers Hill share equates to a target of 0.20mg/L phosphorus and 5.2mg/L total nitrogen, with future phosphorus targets anticipated to be as low as 0.03mg/L. To meet these limits continuous optimisation and upgrades are taking place. In 1997, the Production Team stress tested the plant to determine its full potential. This led to an increase in the design capacity of the plant by 30%, to 130 000 e.p. This also delayed and probably saved capital expenditure by $20 million.

The Sydney University Chemical Engineering Department uses six monthly Industrial Placements to provide certain final year students with extended hands on experience. The needs of Sydney University and Quakers Hill STP presented an ideal opportunity to develop a calibrated dynamic model of the IDAL at Quakers Hill STP, to better understand the interrelationships that exist on the plant.

The model has greatly assisted team optimisation projects by accurately quantifying how ammonia, nitrate and COD change as a function of RAS, WAS and aeration intensity. The key benefit is quantifiable outcomes to proposed maintenance, capital works and optimisation changes. Such as improving denitrification, by over 10%, by reducing the air in the selector distribution channel and introducing a stirring phase at the beginning of the settling cycle.

This presentation will summarise the recommendations of the model that the plant team will be investigating, in light of meeting future plant performance targets, overview the plan in place to trial these recommendations and provide results to date.

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