Cr (VI) heavy polluted site in-situ detoxification method based on biogas residue

Abstract

The invention provides a Cr (VI) heavy polluted soil in-situ restoration method. According to the method, firstly, a chemical reduction agent is injected into soil in situ; high-concentration Cr (VI) is subjected to primary reduction, so that the high-concentration hexavalent Cr cannot generate a toxic effect on the subsequent microorganism ecologic microbial inoculum; then, biogas residue, a carbon source and sulphate are prepared into the ecologic microbial inoculum to be injected into the Cr-containing soil in situ in a pressurizing way; by adopting a special maintenance mode, a large-scale reduction buffer belt containing sulphate reduction bacteria and sulfides is formed in the underground soil of a site; and the Cr (VI) is continuously and effectively reduced. The method has the advantages that the hexavalent Cr can be effectively reduced, and meanwhile, the cost is reduced.

Description

technical field [0001] The invention provides a method for in-situ remediation of heavily polluted Cr(VI)-contaminated soil. Firstly, a chemical reducing agent is injected into the soil in situ, and then biogas residue, carbon source and sulfate are formulated into medicaments and injected in situ under pressure. In the chromium-containing soil, a special maintenance method is adopted to form a large-scale reduction buffer zone containing sulfate-reducing bacteria and sulfide in the underground soil of the site to continuously and effectively reduce hexavalent chromium. The method can efficiently reduce hexavalent chromium while saving costs, and belongs to the field of environmental protection. Background technique [0002] Chromium and its compounds are commonly used basic raw materials in metallurgy, metal processing, electroplating, tanning, paint, pigment and other industries. During the production process of the above industries, a large amount of chromium-containing w...

AI Technical Summary

Problems solved by technology

At present, the mainstream technology of chromium-containing soil is to use ferrous sulfate to reduce hexavalent chromium, but the pH of ferrous sulfate is too low, it is corrosive, and it is easy to be oxidized and deactivated in the air. Therefore, the reduction of hexavalent chromium can only be short-term, not long-term reduction

In order to effectively treat chromium-containing soil, it is often necessary to add excessive ferrous sulfate, which is likely to cause secondary pollution of sulfate radicals

Patent No. 201410101586.0 introduces a method of using ferrous sulfate to repair Cr(VI)-containing sites in situ. Since ferrous is easy to oxidize and fail in the air, this method uses low pH citric acid to inhibit its oxidation and increase the penetration of ferrous , but correspondingly increases the cost, and makes the soil acidified, and still brings secondary pollution of sulfate

Patent No. 201310642919.6 introduces a method of using organic waste to repair Cr(VI)-containing sites in situ. This is a low-cost method for disposing of hexavalent chromium soil, but this method is easy to cause bacterial contamination through natural infiltration. Closure at a certain section of the soil, resulting in the failure of the bacterial solution to be transported and the organic matter and dissolved hexavalent chromium solution entering the groundwater, causing secondary pollution of the groundwater

[0003] Generally speaking, for sites polluted with high concentration of hexavalent chromium, it is difficult to fully restore traditional chemical reagents, while microbial reducing bacteria agents are easily killed by high concentration of hexavalent chromium and lose their effect