Organic matter removal and disinfection byproduct management in South East Queensland's drinking water

Abstract

Over the past several decades, much research has been carried out to understand and control the formation of disinfection byproducts (DBPs) of potential human health concern in drinking water. The majority of these studies have taken place in continental climates of North America and Europe, with less work investigating waters in tropical and subtropical climates. This study evaluated the occurrence, precursors and formation potentials of a range of DBPs across nine water treatment plants (WTPs) in South East Queensland, Australia. Average total organic nitrogen concentrations in raw and final waters were 0.35 and 0.15 mg N/L, respectively, and total organic carbon levels were 9.2 and 3.7 mg C/L in raw and final waters, respectively. DBP formation potential was lower on average in final waters of advanced compared to conventional WTPs, demonstrating the effectiveness of ozone/biological activated carbon (BAC) treatment at removing DBP precursors. While ozone on its own increased the formation potentials of chloral hydrate, halonitromethanes, and haloketones when followed by chlorination or chloramination, subsequent BAC treatment reduced the potential to produce these DBPs, except for tribromonitromethane. DBPs measured in the finished water leaving the WTPs were all below the Australian Drinking Water Guideline levels.