AWWA ACE61845

In 2002, the U.S. Environmental Protection Agency (USEPA) lowered the maximum contaminant level (MCL) for arsenic in drinking water from 50 µg/L to 10 µg/L , and the new MCL will be enforced in 2006. The World Health Organization (WHO), the European Union, and several countries recently lowered the recommended or required arsenic limit to 10 µg/L. Because of the lower MCL, potable water suppliers have an increased need for arsenic removal processes suitable for treating water sources with low ambient arsenic concentrations (10 to 50 µg/L). Arsenic can be removed from surface and groundwater supplies by iron or alum coagulation with filtration, reduced Fe/Mn oxidation systems, and lime softening. Anion-exchange resin and activated alumina packed-bed systems are traditionally used for wellhead or point of entry groundwater treatment systems. In recent years, several iron-based adsorbents have been developed that require less chemical pretreatment and/or have longer operational life than anion exchange resins or activated alumina. Bench-scale comparisons of porous and non-porous iron, sulfur-modified iron, and activated alumina adsorbents for arsenic removal suggest a large number of newly developed adsorbents may be economically feasible in achieving the new arsenic MCL. Overall, media taking advantage of the strong affinity between arsenic and iron will lead to good treatment strategies. The paper presents several examples of potential benefits of iron-enriched granular activated carbon (GAC) over commercially available arsenic media. Includes 30 references, table, figures.