Immobilizing Some Heavy Metals by Mixing Contaminated Soils With Phosphate Admixtures

Soil contamination by heavy metals is a worldwide environmental challenging issue. Due to the industrial activities, a site located in North West of Shiraz (Fars Province, Iran) has the potential to be contaminated by different heavy metals. The objective of this study was to assess the effectiveness of dicalcium phosphate (DCP) and sodium tripolyphosphate (STPP) for immobilizing lead, copper and cadmium in contaminated soils. Leaching column tests performed on the soil without any stabilizing agent demonstrated a uniform leachate of metals in the effluent during the experimental period. After mixing DCP or STTP with the contaminated soils, the release of all three heavy metals through the effluent was ceased. The results further indicated that 0.1-0.2 % by weight of these stabilizers is effective for immobilizing of applied metals through the experimental soil. Penetration of sulfuric acid solution with pH of 5 had no influence on stabilizing efficiency and almost completely the applied heavy metals seem to be immobilized through the soil media.