TRANSFORMATION AND MOBILIZATION OF ARSENIC ADSORBED ON GRANULAR FERRIC HYDROXIDE UNDER BIO-REDUCTIVE CONDITIONS

摘要

Recognizing the potentially serious health concerns because of its toxicity to living organisms, the United States Environmental Protection Agency (U.S. EPA) reduced the allowable maximum contaminant level of arsenic (As) in drinking water to 10 μg/L, thus requiring additional treatment. Among the existing technologies, adsorption of arsenic on iron hydroxide has demonstrated immense promise in maximizing removal capacities. Adsorption onto solid sorbents is favored for small facilities, which comprise most of the impacted utilities (Ghosh et al., 2004). This reduction in arsenic MCL will result in an increased amount of arsenic-bearing solid residues (ABSRs) from water treatment units, which need to either be reused or disposed of as waste in landfills. Landfill disposal of arsenic treatment solid residue can cause desorption of arsenic from the surface of the solid waste and pollute neighboring ground and surface water. Since EPA regulatory and classification protocols incorrectly assess the leaching potential of arsenic from ABSRs to be disposed in landfills (Ghosh et al., 2004; Hooper et al., 1998), it is imperative that the extent of arsenic mobilization from these solid residuals be determined.