Restoration process for polluted soil containing hexavalent chromium

Abstract

The invention discloses a restoration process for polluted soil containing hexavalent chromium. The restoration process is applicable to coarse grained soil. The restoration process comprises the following steps that 1, the polluted soil is subjected to grain diameter grading treatment and dehydrated, and polluted soil grain mud with the grain diameter smaller than or equal to 1 mm is finally obtained; 2, polluted soil grain mud with the grain diameter smaller than or equal to 1 mm is subjected to an acidizing reduction reaction, and the hexavalent chromium is reduced to be trivalent chromium; and 3, an alkaline reagent is added for adjusting the mud containing the trivalent chromium to be alkaline, filter pressing and dehydration are carried out, and a mud cake obtained after dehydration is recycled. The polluted soil is subjected to reduction grain diameter grading treatment at first to enable pollutant to be transferred to fine grained mud with the grain diameter smaller than 1 mm, then, chemical reduction medicament is added, chemical medicament is greatly saved, the trivalent chromium is recycled, soil environment risks are eliminated, and meanwhile certain economic benefits are obtained. Meanwhile, according to the restoration process, water is adopted for reduction screening, the restoration cost is reduced, and secondary pollution to the environment is small.

Description

Technical field [0001] The invention relates to the field of contaminated soil remediation, in particular to a process for remediating contaminated soil containing hexavalent chromium. Background technique [0002] Chromium in the soil mainly exists in the form of trivalent chromium and hexavalent chromium. The existence of chromium determines the chemical behavior and biological toxicity of chromium in the soil. Hexavalent chromium mainly exists in the form of anions in the soil and is not easily adsorbed by the soil, so it has a strong migration ability in the soil. Hexavalent chromium is an inhaled and swallowed toxicant. After skin contact, it may cause allergies or skin cancer. It may also cause genetic damage and have a long period of harm to the environment. At the same time, hexavalent chromium is easily absorbed by the human body and can enter the human body through the digestive tract, respiratory tract and skin and mucous membranes. [0003] At present, the commonly us...

AI Technical Summary

Problems solved by technology

Hexavalent chromium is an inhalation and ingestion toxicant, which may cause allergies or skin cancer after skin contact, and may also cause genetic damage, and has a long cycle of harm to the environment

[0003] At present, the commonly used remediation techniques for hexavalent chromium-contaminated soil include chemical reduction, soil leaching, and microbial remediation. The reduction of chromium-contaminated soil requires the use of a large amount of chemical reducing agent, which is costly; while soil leaching often involves the treatment of eluent and the reprocessing of mud cake after leaching, the process is cumbersome and the treatment is not thorough; The period of microbial remediation is longer, and it is suitable for the situation where the concentration of hexavalent chromium is low, which brings inconvenience to the treatment

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