AWWA WQTC60554

The objective of this project was to investigate the impact of the interaction between water quality, pretreatment processes, pretreatment chemicals, membrane materials and membrane configurations on the membrane performance. This project was implemented in three phases: bench-, pilot-, and full-scale studies. The primary focus of the bench-scale testing was to examine membrane fouling mechanisms by specific fractions of constituents in natural water using several source waters, membrane materials, and membrane configurations. The constituents in raw water were fractionated by prefiltration to remove materials larger than 1 µm, 100 kDa and 10 kDa. The effect of various pretreatment chemicals, pretreatment processes on each fraction, and the subsequent effect on membrane performance, were then assessed. Membrane performance was determined by measuring flux decline during constant-pressure filtration using bench-scale membrane filtration equipment. Water quality before and after pretreatment was also determined. The goal of the pilot-scale tests was to investigate membrane performance using the same pretreatment conditions of the bench-scale study. Pilot testing was conducted on three different water sources: Atlanta Fulton County Water Treatment Plant (AFCWTP) in Georgia with Chattahoochee River water; CIRSEE, Le Pecq, France, with Seine River water; and, North Clackamas County Water Commission (NCCWC) Plant in Oregon City, Oregon with Clackamas River water. These tests provided the opportunity to compare performance of different membrane configurations (submerged vs. pressurized), membrane materials (polyvinylidene fluoride, polysulfone, and cellulose acetate), and pretreatment processes (i.e. coagulation, flocculation, sedimentation and so on). Each test was performed under controlled condition close to the full scale operating procedures. The membrane flux data was collected as the indicator of the performance. The primary focus of the evaluation of full-scale facilities was to provide insight on operational and design issues that were impacted by membrane pretreatment through investigating the interaction between water quality, pretreatment chemicals, pretreatment processes, membrane materials and configurations. Operational and water quality data of several worldwide membrane treatment plants with pretreatment were investigated in this project. For each plant, the long-term water quality, membrane flux, chemical cleaning, and pretreatment chemical data were analyzed to conclude the trend of the membrane performance. Includes tables, figures.