THE USE OF MEMBRANE FILTRATION IN CONJUNCTION WITH COAGULATION PROCESSES FOR IMPROVED NOM REMOVAL

Changes in regulatory requirements and the forthcoming Disinfectant/Di sinfection By-Products (D/DBP) Rule will require that drinking water t reatment facilities be operated to achieve maximum removals of particl es and disinfectant tolerant microorganisms as well as natural organic matter (NOM). For the conventional water treatment plant, this may re quire balancing coagulation requirements for maximum particle and turb idity removal efficiency, as required by the Surface Water Treatment R ule (SWTR) [1] and Enhanced Surface Water Treatment Rule (WSWTR), with the enhanced coagulation requirements as required by the D/DBP Rule. For drinking water production, the use of membrane filtration processe s such as microfiltration and ultrafiltration (MF/UF) to satisfy the t urbidity, particle and microorganism removal requirements of the SWTR is well established [2,3]. Without pretreatment, MF/UF treatment proce sses can achieve only nominal (-10 percent) removal of disinfection by -products (DBP) precursors [4]. However, these processes can be used i n combination with conventional coagulation chemistry [5] or Powdered Activated Carbon (PAC) [6] to achieve similar removals of NOM. The rol e of MF/UF as a treatment technique will evolve as more information is developed on how to apply the processes to meet current and future wa ter quality objectives.