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In 2002, the U.S. Environmental Protection Agency (USEPA) lowered the maximum contaminant level (MCL) for arsenicin drinking water from 50 g/L to 10 g/L , and the new MCL will be enforced in 2006.The World Health Organization (WHO), the European Union, and several countries recently lowered therecommended or required arsenic limit to 10 g/L. Because of the lower MCL, potablewater suppliers have an increased need for arsenic removal processes suitable for treatingwater sources with low ambient arsenic concentrations (10 to 50 g/L). Arsenic can be removed from surface and groundwater supplies by iron or alumcoagulation with filtration, reduced Fe/Mn oxidation systems, and lime softening.Anion-exchange resin and activated alumina packed-bed systems are traditionally usedfor wellhead or point of entry groundwater treatment systems. In recent years,several iron-based adsorbents have been developed that require less chemicalpretreatment and/or have longer operational life than anion exchange resins or activatedalumina. Bench-scale comparisons of porousand non-porous iron, sulfur-modified iron, and activated alumina adsorbents for arsenicremoval suggest a large number of newly developed adsorbents may be economicallyfeasible in achieving the new arsenic MCL. Overall, media taking advantage of the strong affinitybetween 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.

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Edition: Vol. - No. Published: 06/17/2005 Number of Pages: 11File Size: 1 file , 910 KB