A joint restoration method for chromium-contaminated soil

Abstract

A chromium pollution soil combined remediation method includes the steps that the concentration and the content of chromium and the optimum moisture content in chromium pollution soil are determined;a calcium polysulfide solution is selected, the chromium pollution soil and the calcium polysulfide solution are mixed and stirred according to a molar ratio of 2:1-3:1, and mixed material is added with water to maintain the optimum moisture content until the chromium of the chromium pollution soil is reduced from sexavalence to trivalence; coal ash is selected to compose zeolite, the amount of admixture is 10%-15%, the zeolite and the chromium pollution soil are mixed and stirred, mixed material is added with water to maintain the optimum moisture content until the steady absorption of the chromium of the chromium pollution soil is completed; and cement is selected, the amount of admixture is 5%-10% or 15%-20%, the cement is mixed and stirred with the chromium pollution soil, mixed material is added with water to maintain the optimum moisture content, and curing period is maintained for 7-28 days until the solidification of the chromium pollution soil is completed. The chromium pollution soil combined remediation method has the characteristics of good remediation effect, good long-term stability of the remediation effect, no secondary pollution, lower remediation cost and remediation mode reclamation.

Description

technical field [0001] The invention belongs to the technical field of environmental geotechnical engineering, and in particular relates to a combined restoration method of chromium-contaminated soil. Background technique [0002] In various industrial production fields, heavy metal chromium and its compounds are widely used as raw materials, and a large amount of chromium-contaminated soil has been produced in the long-term production process. The rate has reached 1.1%. [0003] Chromium in nature mainly occurs in the valence states of trivalent chromium and hexavalent chromium at the same time, and the toxicity of hexavalent chromium can reach more than 100 times that of trivalent chromium. Hexavalent chromium is one of the three internationally recognized carcinogenic metals. It is also one of the 129 key pollutants recognized by the US EPA. [0004] Chromium-contaminated sites are extremely toxic, concealed, persistent, complex and irreversible, which will not only end...

AI Technical Summary

Problems solved by technology

However, in the application process of the curing stabilization method, it is necessary to simply use cement as the main material for curing. However, due to the poor acid resistance of cement, it will be difficult to effectively inhibit the leaching of acid-soluble chromium after it is used as the main material for curing. For this reason, it is necessary to use Compound preparations are used to improve the above situation, but the existing compound preparations have unsatisfactory curing effects when dealing with high-content chromium-contaminated soils, and the addition of chemicals is relatively large, resulting in expensive repair costs and easy to cause environmental pollution

In addition, the existing solidification and stabilization technology for chromium-contaminated soil is still relatively outdated, which leads to low repair efficiency of chromium-contaminated soil, and the long-term stability of the repair effect is poor, and there is a serious risk of secondary pollution of the environment

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