Optimisation of conventional water treatment processes in Adelaide, South Australia

Supplying drinking water in metropolitan Adelaide to meet contractual and Australian Drinking Water Guidelines is a challenge as source waters contain high concentrations of natural organic matter (NOM) that often exceed 10 mg/L dissolved organic carbon (DOC). The US EPA indicates that enhanced coagulation is the best available technology to control DOC in drinking water treatment plants. United Water has used enhanced coagulation at Metropolitan Adelaide WTPs since 1997 to improve water quality in the distribution system. NOM reduction has led to treated water with a lower chlorine demand allowing a greater residual penetration enabling improved bacteriological compliance. Disinfection by-product formation has also been controlled within the distribution system. Pathogen treatment barriers to remove Cryptosporidium and Giardia have been strengthened by adopting improved filter pre-treatment, enhanced coagulation and filter pre-chlorination to reduce particle breakthrough at all suitable WTPs.