Sequential Treatment Methodology for Hazardous Solid Waste from Organic Arsenic Industry

摘要

Sequential steps were used to remove aromatic matters and immobilize arsenic constituents of solid waste residue (SWR), a kind of hazardous solid-waste with high concentration of arsenic and aromatic chemicals. Initially, semi-solid Fenton processes were applied to not only remove more than 98% of aromatic chemicals, but also avoid producing excessive water and following waste-water treatment. The optimal pH, the initial Fe(Ⅱ) content and the L/S in SSFP were 3.5, 0.062 mol/kg dry weight (DW) and 1.77, respectively. Then, the oxidized sample was still contaminated with great high content of arsenic and was stabilized with ferric sulfate (FS), magnesium chloride (MC) and calcium hydroxide (CH). The optimal molar ratios for Fe:As, Mg:As and Ca:As were 2:1, 3:1 and 2:1 respectively, and the combination fixation FS+MC+CH was found to be the optimal fixation treatment. The arsenic concentration in TCLP leachate could decrease below 5 mg/L. These steps including SSFP and stabilization were necessary to enhance environmental protection (minimal leachability) and to reduce corresponding environmental risk.