Rapid urbanisation has significantly increased the impervious surface along with increase in pollutants such as nutrients (nitrogen, phosphorus), sediments, oil, and hydrocarbon in stormwater. Their removal is important as they adversely affect the aquatic ecosystem and the environment. Thus, this study evaluated the performance of various adsorbent materials (red gum mulch, pine mulch, flyash, oyster shell, sawdust, clay, sand, zeolite, dolomite, alum and lime sludges) for the removal of phosphorus from synthetic stormwater. Among them, alum and lime sludges appeared to be the most effective in removing phosphorus. Further analysis showed that alum and lime sludges remove 99 and 90% phosphorus within 60 minutes from the synthetic stormwater. Therefore, this study demonstrates that the lime and alum sludges could be highly useful as a sustainable and cheap filter media for stormwater treatment systems that are enriched in phosphorus.

Maintaining longer lasting disinfectant residual in a distribution system is highly important to prevent microbial re-growth and hence to deliver safe drinking water. However, various factors such as microbes present in bulk water, sediment, or attached to pipe wall and biofilms accelerates the chloramine decay. Among them, biofilms are a major factor in accelerating chloramine decay as they provide a habitat for the microbes. Thus, this study investigates the effect of biofilms in terms of chloramine decay in the distribution system. Biofilms were grown under various chloramine residuals and different ages of biofilms were investigated by subjecting them to batch tests. Experimental results repeatedly showed that chloramine decay due to biofilms is independent of its growth condition, particularly for different chloramine residuals.

Nitrite, produced by ammonia oxidizing bacteria (AOB), was traditionally thought to be the only cause of microbiologically mediated decay of chloramine. The development and application of microbial decay factor method and bacterial community studies, for the first time have revealed many other factors such as soluble microbial products (SMPs) and bacteria other than AOB mediating the decay of chloramine.

Chloramine is used as a secondary disinfectant in water distributions system (WDS). However, nitrification is a major concern involved in the chloraminated WDS as it leads to the accelerated decay of chloramines. After the onset of nitrification, breakpoint chlorination followed by rechlorination is generally practiced in WDS to reinstate chloramine residuals in the WDS. In this study, two different control strategies re-chlorination and breakpoint chlorination followed rechloramination were applied on the severely nitrified water collected from the laboratory-scale reactor system. Results showed that breakpoint chlorination followed by rechloramination is highly stable as the chloramine residual was maintained up to 300 hours and is highly effective than rechlorination alone as it could maintain residue only up to 50 hours even with repeated re-dosing.