重金属污染场地原位固化稳定化修复试验研究

Remediation of a heavy metal contaminated site:in-situ solidification and stabilization

以甘肃省某铅锌冶炼厂高浓度铅(Pb)、锌(Zn)和镉(Cd)复合污染场地为对象,开展新型固化剂SPC原位固化稳定化(S/S)技术修复现场试验研究。进行含水率、p H值、浸出毒性和重金属形态分布和动力锥贯入试验,以考察修复前后污染土理化、浸出及强度特性变化,评价SPC原位S/S技术的修复效果,并初步探讨相关机制。试验结果表明SPC原位S/S技术能显著降低污染土含水率,提高其p H值;修复后Pb,Zn和Cd浸出浓度值显著降低,且均能满足相应限值要求;SPC修复能够有效降低土中重金属弱酸提取态含量,并将其转化为残渣态,同时显著提高土层贯入阻力值。提高SPC掺量可进一步增强其对污染土的修复效果。

The in-situ solidification and stabilization（S/S） technique using SPC was implemented to remediate a heavy metal contaminated site nearby a Pb-Zn smelter in Gansu,China. Several series of tests were conducted to examine the water content,soil p H,metal leachability,metal speciation and penetration resistance of untreated soils and stabilized soils. The influence of binder contents on these physical, chemical and mechanical characteristics,as well as the fixation mechanisms of Pb,Zn and Cd by SPC were also investigated. The results show that in-situ S/S using SPC reduces significantly the water contents but raises the p H values of contaminated soils. The leached Pb,Zn and Cd concentrations decrease. The metal leachability satisfies the corresponding criteria for solid waste. The large percentages of Pb,Zn and Cd are transferred from the exchangeable fraction to residual fraction after in-situ S/S using SPC. The penetration resistance of stabilized soil increased with the increasing in the SPC content.