Chromium-contaminated soil remediation method

Abstract

The invention discloses a chromium-contaminated soil remediation method, belonging to the technical field of environment engineering. The method comprises the following steps of: dissolving out hexavalent chromium in the chromium-contaminated soil, separating the soil from water, treating trivalent chromium-contaminated soil, treating hexavalent chromium sewage and treating filter residue; the dissolution efficiency of the hexavalent chromium in the chromium-contaminated soil can be improved by the KH2PO4 solution; the trivalent chromium-contaminated soil is treated by biochar made of municipal sludge, so that waste reclamation and secondary utilization of the contaminated soil can be realized; Na2S2O5 can be added into the hexavalent chromium sewage and is used for adjusting the reaction environment, so that the efficiency of converting hexavalent chromium into trivalent chromium can be improved; a flocculating agent is used for accelerating the precipitation and concentration of the trivalent chromium; the filtered water can be used as flushing water for recycling, so that the method is economical and environment-friendly; and a curing stabilization method is used for treating the filter residue, so that the chromium in the filter residue is passivated, and the national environmental standard requirements can be reached. According to the method, the hexavalent chromium and the trivalent chromium are respectively treated, and the solid and the solution are respectively treated, so that the treatment efficiency is improved, the treatment effect is guaranteed, and the method has the characteristics of being free from secondary pollution, low in cost, high in resource utilization rate, etc.

Description

technical field [0001] The invention discloses a method for repairing chromium-contaminated soil, which belongs to the technical field of environmental engineering. Background technique [0002] At present, nearly 20 million hectares of arable land are polluted by heavy metals such as chromium, cadmium, arsenic, and lead in my country. It is estimated that 12 million tons of grains are polluted by soil every year, causing direct economic losses of more than 20 billion yuan. With the acceleration of urbanization and industrialization, more and more land is polluted by heavy metals, the strategic layout of cities has been readjusted, and a large number of heavy metal legacy sites are in urgent need of treatment. According to statistics, there are about 5 million tons of chromium slag left in my country, most of which have not been treated, causing huge hidden dangers to the environment. Soil heavy metal pollution is concealed, lagging and long-term. Heavy metals enter plants ...

AI Technical Summary

Problems solved by technology

[0004] At present, the remediation technologies for composite chromium-contaminated soil mainly include microbial removal, chemical methods (pharmaceutical washing, thermal decomposition, etc.), physical methods (electric current makes charged ions migrate, etc.) and planting plants. A large number of methods are still in the laboratory research stage. , on-site implementation is difficult, and at the same time, the existing chromium-contaminated soil treatment technology is relatively backward, resulting in low efficiency, high cost, secondary pollution and environmental risks of chromium-contaminated soil restoration