Are Membranes a Viable Technology to Produce Drinking Water? Results of a Microfiltration Pilot Study

A membrane pilot study was conducted at the Surface Water Treatment Plant in Monroe, Georgia between November 23, 1999 and March 12, 2000. During the pilot study, a microfiltration pilot unit was rented from Memcor, Inc., a division of US Filter. This unit treated 20 to 21 gallons per minute (gpm) of raw water from Monroe’s raw water pump station that is located on the Alcovy River. The membrane selected to conduct the pilot study was tolerant of oxidizing agents (e.g., chlorine or chlorine dioxide), which were required to control iron and manganese. In summary of the pilot study, the microfiltration unit was able to treat raw water directly from the Alcovy River (i.e., direct filtration) without incidence of any potential violation of drinking water regulations on a full-scale basis. Effluent turbidity averaged 0.038 NTU throughout the study, which is well below the filtered effluent turbidity level of 0.3 NTU being imposed by the USEPA as part of the new Interim Enhanced Surface Water Treatment Rule (IESWTR). Based on effluent turbidity levels, membrane pore size (approximately 0.1 microns), and bacteriological test results, microfiltration also appears to offer effective protection against Cryptosporidium and Giardia cysts (i.e., pathogens)