| The presence of elevated concentrations of natural organic matter (NOM) in raw water sources has presented the challenges for conventional surface water treatment plants to improve disinfectant by product (DBP) precursor removal efficacy. Conventionally used coagulation process produces coagulated residual wastes that must be land filled and may contain high levels of aluminum if alum is used as coagulant. Application of membrane treatment technologies to surface water with high NOM concentrations is often done in the presence of coagulation as upstream pretreatment. Integrated coagulation/UF process is superior in lowering the coagulant dosage which results in the less treatment of sludge and improved removal of NOM and metal aluminum concentration. However, current investigative tools are limited to evaluations conducted at the pilot- and full-scale which can reduce investigative capacity due to associated costs. Standardized bench-scale test apparatus and protocols for conducting membrane evaluation and optimization studies do not currently exist in the industry and could be a significant contribution to advancing process design and operation optimization for membrane systems.; In the immersed membrane ultrafiltration enhanced coagulation (IUEC) process investigated in this laboratory study, coagulation and membrane filtration are conducted in one jar tester which is designed to simulate the pilot-scale system. The OF bench-scale apparatus is compact and capable of operating as an independent system in coagulant pretreatment. The unique design of the ZW-1 membrane modules allows for continuous air injection at variable flow rates within the process tank. The experimental results indicate that air agitation, which is used as the mixing source for flocculation, could help the flocs formation and improve NOM removal. The experiments were performed on three raw water sources which contain comparably low, medium and high NOM levels, respectively. They are collected from three surface water treatment plants located in Hantsport, Dartmouth and Bridgewater, in Nova Scotia.; Therefore, the overall goal of this research was to develop a bench-scale OF apparatus that can be used to assess integrated process designs (e.g., coagulation/UF) under controlled laboratory conditions. This objective was conducted by determining the feasibility of air mixing for the coagulation stage in the hybrid membrane process and optimizing the process conditions based on finished water quality including turbidity, color, UV254, DOC and aluminum residual. The operational variables include coagulant dosage, pH, mixing intensity and hydraulic retention time of flocculation and air scouring during UF filtration. In addition, the other objective of this thesis was to develop a DOC removal model for the integrated coagulation/UF process and to evaluate the significance of membrane mechanical separation in the coagulation/UF process on NOM removal. |
