Changes in the regulatory requirements and the forthcoming Disinfectant/Disinfection By-Products (D/DBP) Rule will require that drinking water treatment facilities be operated to achieve maximum removals of particles and disinfectant tolerant microorganisms as well as natural organic matter (NOM). For drinking water production, the use of membrane filtration processes such as microfiltration and ultrafiltration (MF/UF) alone to satisfy the turbidity, particle and microorganism removal a requirement of the surface water treatment regulation (SWTR) is not enough. MF/UF treatment processes can achieve only nominal (10 percent) removal of disinfection by-products (DBP) precursors (James, et al., 1995). On the other hand, too fast fouling can make the filtration processes more difficult to carry on. To solve these problems, many authors have been interested in installing coagulation pretreatment before membrane filtration to improve membrane performance. However, previous studies reported conflicting results. Some supported the effectiveness of coagulation pretreatment, while others contended that coagulation aggravated membrane performance. This research aims to identify the effects of coagulation pretreatment on membrane filtration through a pilot study using PVDF membrane in combination with analyzing the rationale of coagulation. Another objective of this research was to evaluate the different impacts on membrane performance of using different membrane modules (the submerged module and pressured module). The results showed that coagulation pretreatment greatly improved the membrane performance, extending the filtration time as well as reducing the permeated organic level, and that the submerged module is much more efficient than the pressured module.

The first object of this study is to confirm the feasibility of sustainable flux in a dead-end mode. The second object is to identify the performance of the MF system operating under sustainable flux and simultaneously using the sustainable flux as a control parameter to evaluate the effects of pre-coagulation via comparing the different operating conditions such as various ranges of the coagulant dose, various pH of the raw water, and comparing the effects of online coagulation with conventional coagulation conditions that with sedimentation. According to the experimental results, the feasibility of sustainable flux in dead-end microfiltration (DEMF) was confirmed. In addition, it was observed that the pH control was the most effective method to improve membrane performance compared with other strategies such as pre-coagulation, and sedimentation in case the raw water with preexistent high concentration metal ions. Relative long-term experiments also confirmed the feasibility of the sustainable flux and showed the importance of backwash to improve the membrane performance.