Combined leaching-stabilization rehabilitation method for soil contaminated by chromium residue

Abstract

The invention discloses a combined leaching-stabilization rehabilitation method for soil contaminated by chromium residue. The method specifically comprises the following steps: remediation preparation, specifically, a leachate guide drainage structure is constructed, and the soil contaminated by the chromium residue is dredged, transported, broken, screened and piled; leaching remediation, specifically, a leaching agent is evenly distributed on the surface of a soil heap, the leaching agent separates chromium contaminants in the soil from top to bottom, a discharge port of the leachate is opened and the leachate is collected to a detoxification tank, hexavalent chromium is reduced and trivalent chromium is precipitated, and supernatant is used for circulating spray; and stabilization rehabilitation, specifically, the discharge port of the leachate is closed, stabilizer solution is added to a leaching tank until the soil is submerged, and the chromium contaminants remaining in the stabilized soil are soaked and stabilized by the stabilizer. By means of the combined leaching-stabilization rehabilitation method for the soil contaminated by the chromium residue, the leaching process and the stabilization process are organically combined, first, the total amount of the contaminants in the soil contaminated by chromium residue is reduced by spraying the leaching agent, and then theresidual contaminants are further removed by soaking the stabilizer, so that the amount of stabilizer addition is greatly reduced, and the environmental risk of the soil contaminated by the chromium residue is effectively eliminated.

Description

technical field [0001] The invention relates to the technical field of soil pollution treatment, in particular to a leaching-stabilization combined restoration method for soil polluted by chromium slag. Background technique [0002] Chromium salt is one of the main series products of inorganic chemical industry. It is widely used in chemical industry, metallurgy, prevention and machinery and other industries. About 15% of the products in my country's national economy are related to chromium salt. The traditional method of chromium salt production mainly adopts high-temperature roasting-water immersion-multi-stage evaporation crystallization process, the extraction rate of chromium salt is only about 75%, and 2.5-3.0t of chromium residue is discharged for every 1t of chromium salt product produced. 1.0%~3.0% water-soluble Na2CrO contained in chromium slag 4 and 1.0% to 1.5% acid-soluble CaCrO 4 It is the main component of environmental pollution. With the in-depth implemen...

AI Technical Summary

Problems solved by technology

The reducing agent is sprayed on the surface of the soil mound in the same way in the later stage of rinsing: on the one hand, in the process of spraying the compound bacterial solution in the early stage, it is easy to form a dominant flow channel in the soil mound, which leads to the contact between the reducing agent sprayed in the later stage and the pollutants in the soil The efficiency is low; on the other hand, the reducing agent flows through the surface of the polluted soil from top to bottom, and the residence time is short, so it is difficult to reach the time required for the reaction between the reducing agent and the hexavalent chromium in the soil

The amount of reducing agent is greatly increased, and the reduction of hexavalent chromium remaining in the soil is not complete

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