AWWA SP250169

Ultra-low pressure membrane processes [nanofiltration (NF) and ultrafiltration (UF)] were evaluated on a bench-scale level for their ability to remove naturally-occurring organic matter (NOM) from three geographically-distinct surface waters located in the eastern U.S. Total organic compound (TOC) levels in the waters ranged from 5 mg/L to over 50 mg/L, and trihalomethane formation potential (THMFP) concentrations from 400 ug/L to greater than 2,000 ug/L. Four NF types and one UF type [having three different molecular weight (MWC) cutoff values] were operated at flux rates of 7.5 to 11 gallons per square foot per day (gfd). The NF membranes and the lowest MWC UF membrane were capable of reducing THMFP to less than 60 ug/L and TOC levels by more than 90 percent. Although the removal efficiency of the NF membranes were similar, the specific productivity (gfd/psi) varied significantly.