Cement-Based Solidification/Stabilization of High Concentration Chromium-Contaminated Soil

In this paper, contaminated soil collected from chromium waste landfill has been investigated, and the cement-based solidification/stabilization (S/S) of the chromium-contaminated soil was also discussed by single-factor and orthogonal experiments. The cement can effectively solidify Cr in soil, and this can be classified into three stages: slow improvement, accelerated improvement, and technically stable limit. It is technically and economically feasible when the proportion of cement is 30%-40%. Cr(VI) dissolution can be further reduced through adding up appropriate stabilizer in the cement briquette. The results of orthogonal experiments indicate that cement proportion is the most important factor of Cr S/S, then the ratio of stabilizer, and the kind of stabilizer is the least important. In analyzing the factors of cement-based S/S of the polluted soil, the optimum parameters are as follows: the ratio of cement to soil is 35% and that of FeSO4 (stabilizer) is 2.5%. Moreover, the ultimate leaching concentration of Cr(VI) is 0.89 mg/I and curing rate is 98.27%.