Project Number # 1064
Project Leader: Chris Chow
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Background and Relevance
The primary goal of drinking water quality managers is to ensure the supply of safe drinking water to all customers. Maintenance of disinfectant residuals within suitable ranges throughout a distribution system is a key requirement to achieve this goal. Chlorine is the most widely used disinfectant in Australia, with advantages including low cost and a broad range of effectiveness. In addition, chlorine is capable of maintaining an adequate residual for microbial control over moderate time periods. However, because of its ability to produce odours, the concentrations of chlorine, and particularly the variability of these concentrations are one of the most frequent causes of customer complaints. Conditions in Australia also make control of chlorine residual difficult with problems arising from high levels of natural organic matter (creating a high chlorine demand), seasonal variation in flow demands, and varying water temperatures. Chloramine is often used as an alternative disinfectant to chlorine in longer distribution systems, to provide a slower disinfectant decay rate. Without the use of chloramines in these systems, unreasonably high chlorine doses would be required to achieve effective disinfectant residuals. However, management of chloramination requires more control, as the chemistry is more complex; poor management of this process can result in serious water quality issues in the distribution system.
Despite efforts in recent years, with many disinfection management strategies developed and reported, disinfection residual management still remains a complex optimisation problem and is a challenging task for operators. The aim of this project was to provide water quality managers with the best available information and tools to assist them in achieving practical and improved disinfection system outcomes. This project drew together information from literature, including previous results from CRCWQ&T and recent operational trials from utilities to provide guidance to enable water authorities to adopt disinfection residual management strategies that best meet their customers’ requirements. A disinfection management guidance manual was produced, along with a literature review and a suite of factsheet. The project team also developed a training package for utilities that can be delivered upon request.