土壤Cr(Ⅵ)稳定化修复材料的野外应用研究

Field application of soil Cr(Ⅵ) stabilized remediation material

以河南某铬渣堆Cr(Ⅵ)污染严重的土壤为研究对象,选取腐殖酸(HA)、多硫化钙(CPS)、FeSO_(4)、Na_(2)S、Na_(2)S_(2)O_(3)、抗坏血酸(VC)6种稳定剂开展Cr(Ⅵ)污染土壤稳定化实验,通过考察土壤及其浸出液中的Cr(Ⅵ)含量和pH在3~28 d内的变化情况,筛选出适合实际场地修复的最佳稳定剂。结果表明:CPS对Cr(Ⅵ)污染土壤的稳定化修复具有良好的效果,极大地降低土壤Cr(Ⅵ)及其浸出液Cr(Ⅵ)含量,但造成了土壤碱性问题;将酸性稳定剂FeSO4和碱性稳定剂CPS按照质量分数3%和2%制成的混合稳定剂(T3稳定剂)作用于Cr(Ⅵ)污染土壤,表现出显著稳定化效果同时几乎不影响土壤pH;将T3稳定剂应用于野外Cr(Ⅵ)污染场地的稳定化修复,修复后的土壤及其浸出液的Cr(Ⅵ)含量均低于相关标准限值。研究显示,该技术可为后期Cr(Ⅵ)污染场地大规模土壤修复应用提供工作方法和技术支撑。

The soil polluted by Cr in a chromium slag pile in Henan Province was selected. The six stabilizers of humic acid(HA),calcium polysulfide(CPS),FeSO_(4)、Na_(2)S、Na_(2)S_(2)O_(3),and ascorbic acid(VC) were used for the stabilization experiment of chromium-polluted soil. By investigating the changes of soil Cr(Ⅵ)and its leaching toxicity concentration and pH in 3-28 days,the best stabilizer suitable for field restoration was screened out. The results show that:CPS has a good effect on stabilizing chromium-contaminated soil,greatly reducing the leaching concentration of hexavalent chromium and content of hexavalent chromium in the soil,but causing the problem of soil alkalinity. A mixed stabilizer(T3 stabilizer)made of acid stabilizers FeSO4and CPS in the proportions of 3% and2% acts on Cr(Ⅵ)contaminated soil,and shows a good stabilization effect,while hardly affecting the pH of the soil. The T3 stabilizer was applied to the stabilized remediation of Cr(Ⅵ)contaminated sites in the field,and the Cr(Ⅵ)concentration of the remedied soil and its leaching solution was lower than the relevant standard limit. Research shows that this technology can provide working methods and technical support for large-scale soil remediation applications on chromium-contaminated sites in the later stage.