AWWA ACE60015

An ongoing AwwaRF Project, Optimization of Membrane Treatment for Direct and Clarified Water Filtration, has been studying the effect of pretreatment chemicals on membrane filtration performance. The primary objective of this research is to develop a unified understanding of the interaction between water quality, pretreatment chemicals, and membrane materials, and to evaluate the difference between membrane performance when studied at the bench and pilot scale. The objective of this paper is to report on the bench-scale component of the project, which is being conducted to accomplish the following: to gain insight on fouling mechanisms of microfiltration and ultrafiltration membranes, with a focus on interactions between water quality parameters, treatment chemicals, and membrane materials; to examine membrane fouling by specific fractions of constituents in natural water, separated by size; to examine the impact of water treatment chemicals and pretreatment processes on membrane fouling by specific size fractions of constituents; to examine the physical and chemical characteristics of membrane foulants in each size fraction using advanced microscopic and spectroscopic techniques; and, to evaluate comparisons between bench, pilot and full-scale performance. This research is important because it will provide a better understanding of the fouling of membranes by natural waters and the ability of various pretreatment strategies to alter the fouling process. This understanding can lead to more widespread and cost-effective use of membrane filtration, which will ultimately lead to a safer water supply. Natural surface water from five sources, which were selected to provide a broad international distribution of water, is being studied in the University of New Mexico (UNM) environmental engineering laboratory. The general experimental approach is as follows: raw and pretreated water are shipped to UNM by a water utility; water is pretreated in the laboratory in a manner consistent with the chemicals and doses used at the full-scale facility; inorganic and organic constituents in water are separated into several fractions by size; fouling by each of the fractionated feed waters is analyzed in membrane filtration tests; and, water quality before and after pretreatment and before and after membrane filtration is characterized through measurement of various inorganic and organic water quality parameters. Includes 2 references, table, figures.