Removal of natural organic matter at the Gunbower water treatment plant in northern Victoria, Australia

Abstract

Advanced treatment processes are vital if organic matter is to be removed from water as efficiently as possible. To produce high quality water that has low concentrations of natural organic matter (NOM), the Gunbower water treatment plant (WTP) in northern Victoria, Australia has implemented a number of processes including magnetic ion exchange (MIEX), coagulation, clarifier, ultrafiltration (UF), and granular activated carbon (GAC) filtration. This research evaluated the efficiencies of these processes in removing NOM employing various analytical methods, namely liquid chromatography–organic carbon detector (LC–OCD) and three-dimensional fluorescence excitation emission matrix (3D-FEEM). In addition, the fouling potential of source water and treated water was assessed using a modified fouling index with ultrafiltration (MFI-UF). Biological stability was also tested using a modified assimilable organic carbon (AOC) detection method. The combination of MIEX, clarifier, coagulation, UF membrane, and GAC filtration resulted in dissolved organic carbon (DOC) being removed (from 6.01 to 0.47 mg/L). Furthermore 3D-FEEM analysis revealed that these treatment processes reduced humic and fulvic-like organics. AOC and MFI-UF decreased from 79.94 μg-C glucose equivalents/L and 46,350 s/L2 in the source water to 4.06 μg-C glucose equivalents/L and 2,057 s/L2 in the treated water, respectively.