School of Environmental and Safety Engineering,Changzhou University
Chromium slag and chromium-containing wastewater produced by some industrial and mining enterprises in our country often cause serious chromium pollution in soil due to poor management. It is urgent to seek low-cost remediation technology for chromium-contaminated soil. In this study, a technique of dissolving dissolved organic matter (DOM) extract from rice straw to elute chromium contaminated soil was proposed. Through laboratory simulation experiments, the effects of solid-liquid ratio, leaching time, leaching times and other factors on the elution effect of total chromium and hexavalent chromium in soil were investigated by oscillating leaching method, and the morphological changes of chromium before and after leaching and the continuous passivation ability of residual hexavalent chromium in soil after leaching were discussed. The results showed that DOM extract from rice straw decomposed for 35 days had the best effect of eluting chromium in soil and was determined as the best eluent. The solid-liquid ratio is 1:15, leaching for 4 h/ time, and leaching for 2 times is the best leaching process condition. Under this condition, the total chromium content in soil is eluted by 47.79% and 85.92%, and the hexavalent chromium content is reduced by 51.76% and 95.09%, respectively. DOM extract is weakly alkaline and contains a large number of carboxyl, hydroxyl and phenolic substances. It has good elution effect on chromium in water soluble, weak acid extracted and residue state, effectively reduces the environmental risk of soil, and can continuously passivate the residual hexavalent chromium in the leached soil.