铬污染场地渣土混合物的化学还原修复

针对目前铬污染场地表层重污染铬渣混土难处理的问题，选用河南义马某铬盐厂铬渣堆场表层渣土混合物为研究对象，在分析其理化特性的基础上，研究CaS4、FeSO4·7H2O和葡萄糖3种还原药剂对Cr(VI) 的还原效率，通过改变药剂投加量、反应体系pH、反应时间等条件，优化修复工艺参数。结果表明，3种还原药剂对渣土混合物的最佳还原效率大小为CaS4(98.50%)>FeSO4·7H2O(72.21%)>葡萄糖(51.45%)。CaS4还原修复渣土混合物的最优工艺参数为：药剂投加量为还原反应理论当量的2倍，体系pH在3～9，反应时间0.5 h。

Chemical reduction remediation of chromium residue and soil mixture from a chromium-contaminated site

It’s difficult to safely treat the chromium residue and soil mixture at chromium-contaminated sites. In this study, the chromium residue and soil mixture of a chrome salt plant in Yima city, Henan province was taken as remediation object. On the basis of analyzing the physicochemical properties of the mixture, the effects of doses of three reducing agents, such as CaS4, FeSO4·7H2O and glucose, pH and time of reaction system on the reduction rate of Cr(VI) were studied, then these operational parameters were optimized. Results showed that the order of the optimum reduction efficiencies by these three reducing agents was CaS4 (98.5%) >FeSO4·7H2O (72.2%) > glucose (51.5%). The optimal process parameters for the reduction and remediation of the residue and soil mixture by CaS4 were following: CaS4 dosage of 2 times the theoretical equivalent of the reduction reaction, pH = 3~9, and 0.5 h reaction time.