Though there are many technologies that are commercially available for the disinfection of drinking water, chlorination with different forms of chlorine is still the most widely used form of disinfection throughout the world. One of the main reasons for this is the ability of chlorine to persist in distribution networks, so as to provide a barrier to potential ingress of pathogenic microorganisms into the distribution network. However, maintaining sufficient residual chlorine in distribution networks is a common challenge faced by water suppliers. Chlorine decays in the network, mainly due to the presence of organic material, water age and temperature. This paper outlines investigation work undertaken to improve the chlorine residual in one of Coliban Water’s water distribution systems, namely the Castlemaine Water Supply System.

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Membrane bio-reactor (MBR) technology is a relatively recent and maturing wastewater treatment technology in Australia and New Zealand. As such literature on actual operational experiences with full scale MBR plants in Australasia and how these experiences may be translated into design and operational improvements is somewhat limited.

This paper discusses the operational experiences and the lessons learnt regarding operating full-scale flat sheet MBR municipal wastewater treatment plants. In particular the discoveries made when the first three of these types of treatment plants installed in New Zealand (at Tirau, Turangi and Te Aroha) have been drained down for routine membrane cleaning, membrane inspection, and damaged membrane replacement over the first 8 years of operation.

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The Ouyen Water Treatment Plant, first commissioned in May 2000, utilised high pressure type Polypropylene microfiltration membranes. These membranes reached the end of their life and were replaced in October 2007 with new technology membrane material PVdF which requires significantly less amounts of air and air pressure to perform the backwash (down from 600 kPa to 35 kPa). The PVdF membranes were expected to last for 7 to 11 years however needed to be replaced in October 2013 after 6 years.

In preparation for the membrane replacement GWMWater carried out a detailed review of the plant set up to identify the reasons behind their early failure. The initial assessment identified a limited ability of the inline screen filter to remove sharp items as a major cause for membrane rupture. GWMWater therefore initiated investigations into installing a better pre-filtration system.

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Assessment of source water pathogen contamination is the first step to quantitative microbial risk assessment of drinking water. It is well known that outbreaks of disease caused from drinking water have occurred as a result of extreme events, such as heavy rainfall, which lead to high loads of pathogens washed into the source water.

North East Water conducted a project to determine the level of microbial risk in a degraded catchment. Due to extensive cattle, dairy, and sheep farming as well as the presence of septic treatment systems, the King River was selected for this assessment. In September 2013, sampling was conducted immediately after a rain event at the raw water offtakes of Whitfield, Moyhu and Oxley Water Treatment Plants (WTP). The monitoring program included the selected pathogens Cryptosporidium, Giardia, Campylobacter, Enterovirus, Norovirus, faecal indicators (E. coli, and, total coliforms) as well as physico-chemical characteristics.

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Water Infrastructure Group has been using smart technology in the operations of a number of water and wastewater facilities. This has demonstrated significant benefits for reducing costs, improving reliability and improving operational efficiency with real time of data analysis and reporting.

This paper will examine a number of real world examples which have been applied at:

• Barwon Water Biosolids Management Facility Energy Management System
• Onsite utilisation of iPads and tablets for recording and reporting data, and improving operator efficiency at Water Infrastructure Group operations sites
• Utilising cameras to monitor sites, increase site reliability and reducing frequency of site visits at Water Infrastructure Group operations sites

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Historically, Goulburn Valley Water (GV Water) has carried out maintenance of the water reticulation systems based on time, the availability of resources – operators and air scour unit; and/or the number of complaints received to improve water quality within the distribution network.

GV Water in partnership with Veolia Water commenced the first of three case studies using the Aquadiag service.

• Case Study 1 – Rushworth Township – Sediment Re-Suspension Index
• Case Study 2 – Shepparton to Tallygaroopna system – Free Chlorine
• Case Study 3 – Marysville comparing flushing, air scouring and ice pigging

These case studies have proven to be extremely successful and it is proposed to use the Aquadiag service system as a base for the mains cleaning in all 54 townships within GV Water.

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Nitrification is a known drinking water quality issue in chloraminated systems where ammonia-oxidising bacteria (AOB) feed on free ammonia in drinking water, significantly increasing in number producing nitrite which is then used as food by nitrite-oxidising bacteria (NOB) which converts the nitrite to nitrate. Nitrification is a process which can occur rather rapidly and lead to a complete loss of monochloramine residual. There are also a number of different factors which influence the nitrification process making it a complex issue to understand, control and prevent.

Although nitrification is not an issue with a direct public health impact, it can however, increase water quality risks that may lead to public health concerns. Therefore prevention and early identification of nitrification is critical. This paper will examine examples of nitrification, identification of occurrences of nitrification, and also examples of the implementation of preventative and reactive control measures to manage nitrification in drinking water distribution systems across South Australia and Victoria.

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The overall benefits of disinfection are well established; however a consequential concern is the formation and control of disinfection by-products (DBPs) that may result in adverse health effects. The vast majority of these compounds do not have limit values in the Australian Drinking Water Guidelines (ADWG) and therefore are not monitored by water utilities, regardless of their potential contribution to the risks associated with long term chlorinated water consumption. Therefore, to obtain a better understanding of the impacts of treatment on overall risk, this project measured DBP formation (including THMs and HAAs) and applied a cell-based bioassay. The key components controlling formation of DBPs are natural organic matter (NOM), bromide concentration, chlorine dose, pH and temperature. The most common treatment process utilised to remove NOM is conventional treatment. This project determined the impact of changing water treatment plant operational strategy on disinfection by-product formation.

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Remotely operated vehicles (ROV) are increasingly being used by the Australian utility sector. Rapidly evolving technology means that ROVs are now easier to operate and more cost effective. North East Water has been operating an unmanned aerial vehicle, or drone to conduct aerial inspections of water and wastewater infrastructure since late 2013. The drone transmits live vision wirelessly to the operator and takes high quality photos and continuous high definition video. This allows for quick collection of more useful information that was previously not possible via traditional on-ground inspections.

Aerial inspections of water storages, reservoirs and catchments, water and wastewater treatment facilities and other infrastructure have been performed with excellent results. By entirely removing the operator from hazardous work situations, use of the drone has reduced health and safety risks and in particular, risks associated with working at heights and above water. However, the use of drones introduces new risks which must be considered and mitigated through safe work practices and procedures. This new technology also presents new challenges with privacy and aviation regulations developing alongside the evolution of drones.

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In October of 2013, Goulburn Valley Water (GVW) received a call from a customer complaining that the water had a horrible chemical like taste to it and was undrinkable. Analysis of a drinking water sample taken from the customer’s tap confirmed the presence of high levels of the aromatic hydrocarbons toluene and xylene. Prior to this event GVW had never experienced an issue similar and an extensive investigation was undertaken. As a result the following notice was sent to the customer –

Officers have completed our investigation and the source of the contamination into the potable water service is occurring within the property. Please note that the results indicate that levels of some chemicals in the water sampled at your business are above the Australian Drinking Water Guideline Health Limits. As such, you are advised that this water is not suitable for consumption.

This paper documents the steps taken to locate the source of the contamination.

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The Barwon Water Biosolids Management Facility is the first of its kind in Australia, and the largest in the Southern Hemisphere and has now been operating for 18 months. The innovative, small footprint, fully enclosed thermal drying plant produces T1 Treatment Grade pelletised biosolids that are suitable for reuse as farm fertilizer and soil conditioner that can be safely handled and easily transported immediately after processing.

This paper will discuss the treatment process and the unique challenges involved in operating this Australian-first plant to provide a reliable 24/7 biosolids treatment service, including:
• Embedding operators in the construction and commissioning phase to understand issues and capture knowledge
• Operating a new technology and liaising with the European suppliers
• Effective process for working with contractors during commissioning and operations and transferring knowledge and skills to ongoing operational staff

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ACTEW Water commenced and implemented a valve condition assessment program in 2012-13 using new technology, a Wachs valve exerciser. The following are findings from use of this equipment on ACTEW’s water reticulation network:

• 30-40% of the valves were unusable.
• 4% of the valves were found closed and should have been open.
• Data from the valve exerciser was used to calibrate the hydraulic model.
• Broken and stiff valves were identified for replacement.
• Evidence that the program will significantly reduce the risk of shoulder injuries.

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As part of the Queensland Government’s water reform program, Unitywater began operations on 1 July 2010, which included inheriting a “Design, Build and Operate” contract for the Redcliffe Sewage Treatment Plant (STP). Shortly after taking responsibility for the plant, Unitywater proceeded to calculate the contractor’s fee payments with a significant reduction (in accordance with contractual mechanisms) for regular effluent quality licence exceedances and commenced performance management activities (e.g. audits, condition assessments, requests for Action Plans) in regards to:
• Significant safety and security issues
• Licence compliances issues (odour and effluent quality)
• Maintenance and housekeeping issues (significant deterioration was apparent on structures and mechanical & electrical equipment)

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Water treatment plant (WTP) operators and managers are continuously seeking ways to improve the efficiency of treatment processes to generate cost savings and achieve desired water quality outcomes. Optimisation of the coagulant dosing step at conventional water treatment plants will potentially achieve both of these objectives. Ensuring that the optimum coagulant dose is consistently applied to variable quality raw water will not only result in water quality improvement, but should also generate chemical cost savings where potential overdosing of coagulant is minimized.

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A common theme across many Victorian water businesses in recent years has been the management of disinfection residuals and water quality in drinking water distribution networks. This is particularly notable in areas where chloramination is used as the primary disinfection method. Chloramination is necessary in drinking water networks with:
• low flow demand,
• long detention times, and/or
• high risk of disinfection by-product formation due to source water quality.

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In August 2012 an internal wall partially collapsed in one of the bioreactors at the Warragul WWTP. This paper details Gippsland Water’s initial response to the issue, the planning stages to repair the wall and the execution of the subsequent works. The main difficulties Gippsland Water faced involved high groundwater levels, uncertainties in the extent of the damage and the plant’s capacity to continue producing compliant treated effluent while halving the available bioreactor volume, allowing the bioreactor to be taken offline. The repairs were completed successfully and the plant was able to maintain compliance with the EPA licence for the duration of the works. Built upon the learnings from the original incident, preventative works were completed a year later on the second bioreactor to ensure it would not fail in the same way.

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The River Murray is the major drinking water source for regional South Australia. Treated water produced in these regional areas is transferred in above ground pipes to consumers often located in excess of 100 km from the water treatment plant. To satisfy disinfection requirements, chloramination is practiced as it offers greater stability over chlorine for the long residence times and high temperatures that are encountered. A major challenge for operating a chloraminated distribution system is the prevention of nitrification that can result in the rapid degradation of monochloramine residual. For the first decade of the 21st century drought conditions predominated and generally nitrification events in chloraminated distribution systems were isolated. However drought breaking rains in the Murray Darling Basin in 2010-2012 resulted in two major flood events that caused extreme changes in water quality, and nitrification events subsequently became more widespread. Distribution system water quality monitoring showed that an increase in product water DOC concentration was a key factor in the loss of monochloramine residuals. Also in 3 of 4 WTPs investigated, monochloramine decay tests identified the presence of microbiological monochloramine decay accelerating the overall monochloramine decay rate, increasing the likelihood of nitrification. Overall, combining water quality monitoring and monochloramine decay tests helped identify key factors impacting on nitrification.

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South Waikato District Council, Watermark Business Unit operates and maintains 4 x Wastewater Plants across the district, Tokoroa, Putāruru, Tīrau and Arapuni. All four Plants have differing treatment processes, but similar basic sludge dewatering to conventional drying beds.

With the two bigger Plants of Tokoroa and Putāruru working through renewal of Resource Consents with the Waikato Regional Council there was an opportunity to modernize and centralize our sludge/biosolids dewatering process.

I have now completed 35 years in the field of water and wastewater based at the Tokoroa Wastewater Treatment Plant. I would now like to share what changes and challenges we have made to the liquid stream and the more recent improvements to the sludge/biosolids operation.

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Operational performance monitoring (OPM) is defined as a planned sequence of measurements and observations throughout the water supply system to ensure and confirm performance of preventative measures and barriers to contamination (NHMRC, 2011). This is an integral aspect of drinking water quality risk management, as suboptimal conditions that may pose a risk to drinking water safety, are identified early, acted upon and managed in a timely manner to minimise or preferably avoid impacting upon consumers.

With the Safe Drinking Water Regulations 2005 (Vic) due to sunset in July 2015 the Victorian Department of Health is considering the inclusion of OPM in the new regulations and adopting more of a barrier performance approach to safe drinking water assessment. Given this, the OPM practices undertaken by Victorian water businesses will be required to demonstrate that the preventative measures in place and barrier performance is adequate to manage the water quality hazards and risks posed. Crucial to achieving this will be efficient, effective and evaluated OPM practices that support an informed operational decision making process.

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The upgrades at Warracknabeal and St Arnaud Wastewater Treatment Plants (WWTP) has meant an improvement in the quality of re-use water and assisted the relevant plant operators to stay on top of any safety and operational issues. The fully automated systems ensure the operators know exactly when something goes wrong at the plants, meaning they can act quickly to fix any problems and keep the plants running smoothly. The operators say the plants virtually run themselves and just require daily checks and routine maintenance tasks. Extra training provided by GWMWater has been essential in learning how the plant operates and assisted the operators to better understand the electronics and safety.

The upgrade at Warracknabeal in November 2012 and St Arnaud in August 2013 introduced the first Linear Decanters of their type into Australia, which have now been adopted in other wastewater treatment plants across Australia. These Linear Decanters sit on a telescopic tube which moves up and down with the water level, drawing water from underneath the surface avoiding the rubbish that sits on top. The water then goes via a UV process on its way to the final destination, a re-use dam. In Warracknabeal the re-use water is used at the racecourse and golf club, whilst in St Arnaud it goes to Lord Nelson Park recreational facility, which includes both the lawn tennis club and golf course, with everyone enjoying the benefits of better quality water.

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As the eventual asset owner and operator of the fluoridation dosing plant, with the responsibility for all future costs together with the associated WHS, asset and risk management issues Port Macquarie-Hastings Council wanted to ensure that this new facility would not be developed and delivered as a simple “least capital cost” solution.

In this regard Council undertook a rigorous design development process which included site inspections of similar facilities owned and operated by major water utilities including; Brisbane Water, Hunter Water, Sydney Water and several Victorian water authorities. These visits included detailed discussions with plant operators to determine current industry best practice and important issues to be considered in the design, construction, operation, maintenance and repair of a new fluoridation dosing plant.

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The greatest risk to public health from drinking water, are microbial pathogens. To manage this risk, water businesses test drinking water for Escherichia coli to see if there is an indication that the water may be contaminated. However, the absence of this bacterium may not mean the water is free of pathogens. Other microbes that cause illness, such as protozoa and viruses may be present.

To better manage risk from all pathogens, the Australian Drinking Water Guidelines are likely to adopt the Health Based Targets (HBT) approach for microbial risks.  This will allow water businesses to manage microbial risk by assessing appropriate treatment technologies and the critical limits needed to control pathogens in source waters. For Water Treatment Operators it will underpin optimal performance of all barriers in treatment plants under all conditions.

This paper describes two case studies that demonstrate the application of HBT objectives in order to improve the management of microbial hazards in drinking water.

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In February 2013, the Department of Health (the Department) published the Guidelines for validating treatment processes for pathogen reduction – Supporting Class A recycled water schemes in Victoria (the validation guidelines). The validation guidelines were developed for use by Class A recycled water scheme proponents, water treatment technology manufacturers, researchers and regulators. Their main focus is on managing the acute health risks posed by pathogens in recycled water and the guidelines apply to both the design and operation of Class A recycled water schemes. Using a number of case studies, this paper outlines recent experiences of treatment incidents at Class A recycled water plants. Through sharing these experiences, the Department aims to highlight what can go wrong at treatment plants and emphasise on the importance of treatment validation and having appropriate operational and verification monitoring at the treatment plant. This paper will also highlight the importance of understanding treatment processes and having an appropriate control philosophy in place to minimise the microbial hazards in recycled water.

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