AWWA ACE63027

This slide presentation outlines natural organic matter (NOM) membrane fouling and its removal to reduce disinfection byproduct formation. Major types of NOM are outlined along with the three primary means used to control fouling in low pressure membrane filtration. Three case studies are outlined that consisted of pilot evaluations at three locations designed to test various techniques for the control of membrane fouling and the reduction of byproduct formation in membrane filtration systems. Because of the high solids loading, only outside-in flow configurations were piloted. The three case studies were located in Abilene, Wichita Falls, and Sherman, Texas. The first case study in Abilene, Texas focused on evaluating color and total organic carbon (TOC) removal without clarification. The outcome demonstrated that both systems met organic removal goals using direct filtration (no clarifier), and high doses of coagulant did not significantly improve performance over moderate dosages. The second case study in Wichita Falls focused on comparing coagulation and coagulation/sedimentation. The outcome demonstrated that high solids and organic levels in the Wichita Falls water source required flocculation AND clarification prior to the low pressure membranes, chemical wash appeared to improve performance, and solids and organic loadings were still problematic for one supplier. The third case in Sherman, Texas focused on comparing coagulation and chemical washing. The outcome demonstrated that both fouling management approaches were successful in achieving the required 30-day CIP interval, and chemical wash provided better economics. Pilot process flow diagrams are given for each case study, along with pilot results and cost evaluations. Includes tables, figures.