Study on the Stabilization and Long-term Effect of Chromium Contaminated Soil Using Homemade Reagent KTWDJ-1

To verify the applicability of homemade sulfide-based stabilizers（ KTWDJ-1） in remediation of Cr⁶⁺ contaminated soil,stabilization tests were carried out based on the contaminated site of a chromate factory,and compared with calcium polysulfide（ CPS） and sodium sulfide（ Na₂S）. The effect of sulfide-based stabilizers on reduction and stabilization of Cr⁶⁺ contaminated soil was summarized. The results showed that KTWDJ-1 had the best effect on Cr⁶⁺ reduction. When the proportion of KTWDJ-1 was 3%,the Cr⁶⁺ leaching concentration was reduced from 128. 5 mg/L to 0. 05 mg/L,and the reduction efficiency was as high as 99. 96%. However,under the same conditions,the reduction efficiency of CPS and Na₂S to Cr⁶⁺ was 99. 04% and 85. 52%,respectively. As the proportion of sulfide-based stabilizers addition increased,the concentration Cr⁶⁺ leaching continued to decrease.The fraction change of iron and manganese oxides increased significantly in soil stabilized by KTWDJ-1,and the change of exchangeable content of Cr in soil stabilized by sulfide-based stabilizers was the main reason for the change of Cr leaching concentration. In addition,three sulfide-based stabilizers,KTWDJ-1 showed relatively good long-term stability,after repeated leaching of acid water could still maintain a stable and low leaching concentration. Finally,the engineering optimal parameters of KTWDJ-1 were explored. In the stabilization process,the water content of soil should be controlled at about 30%,the p H of soil adjusted to about 9,and the curing time is guaranteed for more than 5 days. The stabilization effect of contaminated soil Cr⁶⁺ would reach the best.