AWWA MTC50242

This paper describes two assessment methods for UF type of membranes for large-scale applications. The combination of those two methods results in quite clear and unambiguous answers to the question what membranes are of interest for long-term testing. With the first method, called dead-end filtration, information is generated on the suitability of the membrane and on the combination of the membrane material, the module hydraulics and assembly. With this method the evolution of TMP is monitored upon filtration cycles of 20 minutes with raw water at a flux rate of 120 l/h.m[2], alternated with backwash cycles with permeate of 40 seconds at 1.2 bar negative TMP. The second method, called cross-flow filtration, give information on the suitability of the membrane material. This is being done by the measurement of the absolute value of the so-called "plateau fluxes" in cross-flow mode at 0.2 m/s linear velocity. For this purpose raw water concentrates are being used. Three "open" UF type of membranes, all three in hollow fiber configuration were assessed with these two methods of which two membranes were in the 8 inch pressure vessel concept. The third membrane module was a pressure vessel-less concept. The suitability of these three membrane types was evaluated as a pretreatment for two surface waters. Includes 6 references, tables, figures.