AWWA ACE63229

Following the promulgation of the arsenic rule, many water systems are faced with the need to select a treatment technology to comply with the revised arsenic maximum contaminant level (MCL) of 10.0 µg/L. Adsorption media filters are one of the technologies available to treat water supplies for compliance with the new arsenic MCL and are often selected by small and medium sized groundwater systems to comply with the new drinking water regulations. Although adsorption medias, especially several of the relatively new proprietary medias, are generally very effective at removing arsenic from drinking water, their performance can be significantly impacted by the source water quality. Water quality parameters such as arsenic speciation, pH, concentrations of competing ions, and other source water characteristics can affect the efficiency and capacity of adsorption media for removing arsenic from water. The apparent arsenic removal capacity of any given treatment unit may vary significantly from system to system as a result of source water quality characteristics other than the total arsenic concentration. Therefore, selecting and designing an adsorption media treatment system for arsenic removal requires careful consideration and an evaluation of the effectiveness of adsorption medias considered for each application. Systems that intend to use adsorption media technology must select the most appropriate, both effective and economical, adsorption system and determine the media capacity for their source water in order to properly design the treatment process. Laboratory bench-scale testing followed by pilot-scale studies are traditionally used to evaluate equipment performance, establish design criteria for a full-scale treatment system, and gain regulatory approval for use of new treatment technologies. Water quality data from three adsorption media pilot tests are used here to demonstrate the impacts that source water characteristics, including arsenic speciation, pH, and concentrations of competing ions can have on arsenic adsorption system performance. Utilizing the pilot test data, the impacts of water quality characteristics on system design and operation, including the selection of a treatment process, economic analyses, treatment vessel configuration, chemical usage impacts, and other operational factors are discussed. Includes 2 references, figures.