AWWA MTC64598

This paper presents a study on the development and validation of a laboratory-scale membrane testing protocol to select viable membranes for pilot- and full-scale operation. This selection protocol balanced operational characteristics (such as pressure, flux and potential for fouling) with product water quality and allowed for a pre-selection of potentially viable candidate membranes. Membranes considered for selection were characterized as thin-film composite (TFC) polyamide membranes and included commercially available ULPRO (TFC-ULP, Koch Membrane Systems; XLE, Dow/Filmtec; TMG10, Toray America; RE-BLR, Saehan) and nanofiltration (NF) membrane products (NF-90, NF-270, NF-200 and NF-4040, Dow/Filmtec; TFC-S, Koch Membrane Systems; ESNA1-LF, Hydranautics; MX07, Osmonics; NE-90, Saehan). Three candidate membranes were selected and tested using a 68 L/min (18 gpm) membrane pilot skid that was designed, constructed and operated during this study. The three selected candidate membranes were each tested for at least 1,300 hours on microfiltered feed water at two full-scale facilities. The different feed waters represented non-nitrified microfiltered effluent provided by the West Basin Water Recycling Plant (WBWRP) in El Segundo, CA and nitrified/denitrified microfiltered effluent provided by the Scottsdale Water Campus (SWC), Arizona. Operational performance and rejection of trace organics, nutrients and total organic carbon were monitored during pilot-scale testing and compared to the performance of full-scale trains operating on the same feedwater employing conventional RO membranes (i.e., TFC-HR, Koch Membrane Systems and ESPA2, Hydranautics). During several occasions, challenge tests were conducted at pilot-scale to examine rejection of trace organics during periods of elevated feed concentrations. The best performing ULPRO membrane was also selected for testing over 5,000 hours in a 6.6 m³/min (2.5-mgd) full-scale reverse osmosis (RO) train to further verify findings from pilot-scale and to determine rejection behavior and operating costs under full-scale conditions. The study was assisted through state-of-the-art membrane characterization to describe the fouling character of NF/ULPRO membranes and its role on operation (e.g., flux decline) and rejection. A comprehensive membrane autopsy was performed after each pilot-scale testing period to determine the nature of the observed flux decline and characterize the type and location of fouling. Includes 12 references, tables, figures.