Investigation of a Novel Approach for Arsenic Removal from Water Using Modified Rhyolite

Abstract

Arsenic ranks twentieth among the most abundant elements in the earths crust. Arsenic has been identified as a human carcinogen. Arsenic in groundwater has become a huge concern globally and in the United States. USEPA proposed the final arsenic rule, which lowered the arsenic standard from 50 ppb to 10 ppb and requires the community water systems to comply with the new standard before January, 2006. Modified rhyolite, the proposed novel adsorbent could reduce arsenic in water from 300 ppb to concentrations below 10 ppb in 6 minutes. This novel medium had very a high removal capacity for As(V). The removal of As(V) was slightly dependent on pH in the range 5 - 9. The arsenic removal process follows second order kinetics. The presence of competing ions had no effect on arsenic removal efficiency by the medium. The practical application of this medium was assessed by multiple cycles of sorption and desorption. TCLP analysis done to check the leaching potential of the medium proved to be favorable and hence this medium could be safely disposed in non-hazardous waste landfills. A column study was conducted and the operating capacity of the column was compared with batch operation. Engineering applications of this novel media are discussed.