Remediation of As-contaminated Soil Using Magnetite and Bottom Ash

BACKGROUND: Mining activities, smelter discharges, and sludges are the major sources of heavy metal contamination to soils. The objective of this study was to determine the efficiency of magnetite and bottom ash derived from coal ash in remediating As-contaminated soil. METHODS AND RESULTS: An incubation experiment was conducted for 10 weeks. Magnetite and bottom ash at different rates and ratios were applied to each plastic bottle repacked with 1,000 g of dried As-contaminated soil. After 3-weeks of incubation, the concentrations of available As were measured by using Mehlich-3, SBET, and sequential extraction methods. All of the subjected soil amendments resulted in significant decreases in available As concentration compared to the controls. The addition of magnetite at the highest rate was the best to stabilize As in the soils; however, the values of As concentration varied with the extraction methods. CONCLUSION(S): To ensure the stabilization accuracy of heavy metals in soil, both single and sequential extractions are recommended. The magnetite derived from fly coal ash can also be applicable as a heavy metal stabilizer for the As-contaminated soil.