AWWA ACE95071

Recent epidemiological studies on the carcinogenicity of arsenic have raised concern over the levels of arsenic in drinking water. As a result, the US Environmental Protection Agency is now considering a decrease in the current maximum contaminant level (MCL) for arsenic in drinking water from 50 ug/L to a level between 20 and 0.5 ug/L. Treatment of drinking water for arsenic removal will be required should a more stringent standard be adopted. Hence, it is imperative that the effectiveness of available technologies for arsenic removal be assessed. Among the technologies applicable to arsenic removal are enhanced coagulation and membrane processes such as reverse osmosis (RO) and nanofiltration (NF). This paper investigates the effects of chemical composition and operating conditions on arsenic removal by membrane processes in both synthetic waters and source waters. Synthetic waters consist of arsenic and one or more co-occurring in organic solutes. Colorado River water (CRW) and State Project water (SPW) supplied by Metropolitan Water District of Southern California are used as representative source waters.