Biological nutrient removal sewage treatment plants release biologically assimilated phosphorous from anaerobically digested sludge. When this sludge is dewatered, a phosphate rich supernatant is obtained. The current industry practice of diverting the supernatant to the head of the works significantly increases the phosphorous loading on the treatment process.

EGL operate the Redcliffe City Council WWTP, and use hydrated lime (Ca(OH)2) to treat phosphate via an existing lime slurry system. EGL have been looking at alternatives to the use of lime as it represents an OH&S hazard and the dosing process had become operationally inefficient and costly to maintain.

This paper reports on the work that Virotec Global Solutions have undertaken with EGL to develop a formulation to treat phosphates, achieving a removal rate of 99.84% (from 500 mg/L to 0.8 mg/L).

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Riverina Water operate a number of Bores for potable water use varying in output from 1litre per second to 150litres per second and varying in age from mid 1960 to current date.

As these bore start to age a decision has got to be made what is to be done with an ageing bore.  This paper is based on some field experiences that Riverina Water has come across.

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Googong reservoir is Canberra’s largest water storage dam, however regular blue green algae blooms make water treatment more difficult in summer. In summer 06/07 low dam levels in Canberra’s alternative catchment meant that Googong water was required for town supply. This paper discusses the strategies which were used to allow extraction from the reservoir.

Dosing with powdered activated carbon was critical for final water quality. A variety of operation and maintenance issues were associated with the high PAC consumption rates of around 50kg/hour. Destratifying mixers were installed in the reservoir during summer 06/07 as a long term algal management technique. They had an immediate effect on reservoir stratification, helping to resolve problems with anoxic water and dissolved manganese.

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A 5-year trial to supply tertiary treated sewerage effluent from a primarily domestic Sewerage Treatment Works to a nearby urban area was proposed in conjunction with NSW Department of Energy, Utilities and Sustainability (DEUS).

The trial was to be based on the newly released “NSW Guidelines for Urban & Residential Use of Reclaimed Water”.The reclaimed water was supplied to 10 of 2.23 Ha rural residential properties and 75 normal residential properties. The trial has since been converted to a permanent effluent supply to the properties connected.

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In the year 2000, the upgrade of the Mittagong Regional Sewerage scheme took place under a design and construct contract. This was a $40 million project which included the design, construction, commissioning and process proving of a new treatment plant at Braemar with a capacity of 14,000 EP.  It also included the provision of sewer to the northern villages of the shire which entailed the laying of approximately 80 kilometres of pipeline including trunk mains, gravity mains and rising mains.  A total of 15 new pump stations were constructed.  The project also included the decommissioning and demolition of the existing trickling filter plant.

In conjunction with the project some upgrades of the existing reticulation systems and pump stations were carried out.  Installations of PLC control and telemetry systems were provided to all pump stations and the plant.

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Demand Management and Leakage Detection are in vogue due to the extreme pressures on our water resources from drought, population growth and ageing infrastructure. The majority of water suppliers have implemented Demand Management strategies including water restrictions, pressure management and active leakage detection.

This paper discusses a simplified operational method for monitoring water loss and targeting resources effectively. How much water am I really losing from my infrastructure and where am I losing it? When I start actively looking for leakage?  Is my leakage costing me more than the cost of finding and repairing it?

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To comply with our Health Department requirements, Tweed Shire Council staff routinely collect samples from up to 25 sites in the reticulation network, including at the 3 water treatment plants.

In the past, the storage of sample bottles and the equipment used in the sampling process was not very good.  Often they were thrown into the back of the ute in an esky and this may have had an impact on our sample results.

This paper describes the improvements made to our sample collection and storage procedure for the Tweed Shire Council Water Unit.

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Saving energy techniques are very much a part of every day life. Water and waste water applications are no exception.

The use of variable speed drives is becoming more and more accepted and used throughout the water and waste water industry and is becoming a very effective and efficient way of maximizing the pump efficiency, providing energy savings as well as complete motor and system related protection.

This paper describes the energy saving concept behind the use of variable speed drives in water and waste water pumping applications and considerations that should be taken when designing and incorporating variable speed drives into your water and waste water application.

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Temora’s Sewerage Treatment Plant was constructed and commissioned around 1930. The plant has given good reliable service over the last 70 years with only minor improvements to the works being implemented over these years. Over recent years however there has been a marked deterioration in the condition of the works and in conjunction with increasing requirement to comply with OH & S & Workcover regulations, and with further reporting required from EPA for licensing, it became imperative that Council address the situation.

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Dubbo City Council’s John Gilbert WTP recently underwent an upgrade from 30 ML/d to 80 ML/d. Treatment at the new plant comprises of aeration; PAC dosing; coagulation; softening; clarification; recarbonation; filtration; disinfection; and fluoridation. The project involved significant construction works, while parts of the existing plant were retained and others refurbished for alternate use. The need for continued water supply to the city of Dubbo posed technical and logistical challenges, with HAZOP studies, design and site meetings used to aid in problem solving. John Gilbert WTP is now the largest water softening plant in NSW.

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The upgrade works for the Spring Creek Dam at Orange NSW was carried out between Jan 2006 and March 2007.

As a result of progressive failure of the central concrete core wall the full capacity of the dam could not be fully utilised; the works were necessary to restore the dam to it’s original holding capacity of 4,500ML.

The project involved five main aspects of work; refurbishment of the 2km access road, building the main dam and a minor saddle dam, refurbishment of the intake works and construction of a new pump station.

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Wastewater from the Morisett, Bonnells Bay and Dora Creek areas is directed to the Dora Creek Wastewater Treatment Plant (WWTP) for treatment.  The treatment process includes two Intermittent Decant Extended Aeration (IDEA) tanks and a treated water storage lagoon.  The plant has Licence requirements of pH 6.5 to 8.5, BOD 30mg/L and TSS 20mg/L with the majority of the final treated effluent being used in cooling towers by the Eraring Power Station.

The plant has a history of operational problems which have proven hard to remedy using conventional wastewater treatment practices. This paper describes the problems encountered and the types of operational changes trialled and implemented in an effort to combat them, as well as discussing the results achieved over the past 4 years.

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East Gippsland Water participated in a joint venture project with Gale Pacific, CSIRO and SuperSpan which explored the overall benefits of covering water supply storages with shadecloth as an alternative to replacement with covered tanks, solid covers or floating covers.  The project ran from 2004 to 2006 with four storages (two raw water and two clear / treated water) monitored for one year uncovered and one year covered.  Two control storages (raw and treated) were monitored for two years uncovered.  At the end of the study it was shown that the incidence of algal blooms was dramatically reduced.  Water fowl and wind-borne organic materials were less likely to enter the water storages.  Aquatic plants could longer grow at the bottom of the storages, reducing maintenance costs.  Evaporation rates were reduced by approximately 90%.  This drop in evaporation loss is highly significant and, in circumstances where alternative water supplies are not available, potentially valuable.  The improved water quality and reduced risk of algal blooms and other contamination provided by the covers offers a valuable enhancement in security of water supply.

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Clarence Colliery is a coal mine that is located in the Blue Mountains North West of Sydney. New stringent effluent conditions were imposed on the Plant, as a key initiative improving the water quality discharge.

The existing 10 ML/d water treatment plant at Clarence Colliery was augmented to treat 25 ML/d of water from the mine. Waters from underground mining works as well as water in the Leachate Pond contained elevated levels of iron and manganese. Before this water could be discharge to the Wollangambee River, it had be treated to acceptable levels through the Clarence Colliery Water Treatment Plant.

The purpose of this project was to remove iron and manganese levels so as to consistently meet the discharge water quality requirements. Clarence Colliery decided that the most effective long-term solution was to use an experienced water company to take responsibility for the scheme including the design and construction of the upgrade as well as maintaining the operations of the facility for 2 years with the option of continuing the term for a further 3-5 years.

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A number (12) of powdered activated carbons (PAC) were jar tested in natural raw water containing a commercial spike of MIB and geosmin and their performance for reducing these compounds was evaluated. The PACs tested came from a variety of suppliers, raw materials, activation methods and countries including steam activated coal, wood and coconut; and chemically activated wood. Each of the carbons (except Acticarb PS1300) had the same iodine number (a measure of adsorption capacity) and were analysed under the same conditions including a 15 minute contact time.

Of these carbons the Australian steam activated coal carbons, Acticarb PS1000 and PS1300 had the best removal efficiencies. The Acticarb PS1300 was the only carbon with a higher iodine number, however this increase in adsorptive capacity for iodine was not proportional to the increase in adsorption for MIB and geosmin. For all of the PACs tested, the geosmin was more easily reduced than the MIB. Contact time, raw water character and PAC character all influenced the PAC’s ability to reduce MIB and geosmin.

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Investigation of future water supply sources for the ACT identified the need to pump water from the Murrumbidgee River and in May 2007 ActewAGL commenced the abstraction of raw water from the Murrumbidgee River for the first time.

The water quality of the new catchment had a major impact on the water treatment processes and operations at Mt Stromlo Water Treatment Plant. Plant performance assessment was based on the US EPA LT2ESWTR system and to date the plant has met all turbidity targets, producing safe drinking water.

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The Beenleigh WRF was retrofitted as part of a capacity upgrade in 1999 from Extended Aeration Oxidation Ditchs to a Bio-Denipho Process and has had inconsistent nitrogen control over several years since the upgrade of the plant, which has lead to several licence breaches.

The reason for the upgrade was to increase the plants hydraulic capacity and further reduce final effluent nitrogen levels. The plant serves a population of approx 60,000 and approximately 20% of the plant inflow comes from an industrial catchment covering industries such as a brewery, dog food manufacturer and paper recycling plants etc.

The plants upgrade was delivered via a short term “Design, Build, Operate” (DBO) project delivery method, giving the contractor 3 years operational control after construction completion, main reason for choosing this method of delivery for this upgrade was that if you have the design, construction and commissioning all undertaken by one party you would be in a better position to ensure the plant delivers what it was designed to do.

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Collingullie is a small rural village located 20km’s west of Wagga Wagga in southern NSW. The village has a population of approximately 200. Water is supplied from 2 bores situated near the Murrumbidgee River. Prior to the plant upgrade the only treatment was aeration and chlorination using gas.

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