Remediation method of chromium-contaminated soil

Abstract

The invention discloses a remediation method of chromium-contaminated soil. The method comprises the following steps: (1), detecting the chromium contamination condition of soil, and determining a concentration distribution rule of hexavalent chromium in the chromium-contaminated soil; (2), with the soil layer depth with the hexavalent chromium transverse concentration distribution of 800-1300mg/kg as a boundary, distinguishing severe chromium-polluted soil from mild chromium-polluted risky soil; (3), stripping the severe chromium-contaminated soil, performing ex-situ remediation on the severechromium-contaminated soil, and performing in-situ remediation on the risky soil; (4), backfilling the remediated severely chromium-contaminated soil onto the remediated risky soil, adding humic acid, performing plowing, and planting plants capable of enriching chromium; (5), regularly harvesting, removing and reseeding plants capable of enriching chromium, and detecting the total chromium content above the boundary for at least 6 months; and (6), determining that the concentration of hexavalent chromium on the surface soil of the chromium-contaminated soil meets the restoration target concentration, and if the detection result is unstable, repeating the (5) until the detection concentration reaches the standard.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to a method for remediating chromium-contaminated soil. Background technique [0002] With the advancement of industrialization, the environmental problems generated in the process of economic development have gradually attracted people's attention. In recent years, the heavy metal pollution of the atmosphere, water and soil environment and its treatment and restoration have gradually become the focus of people's attention. Among them, due to the complex composition of pollutants in the soil, the difficulty of treatment, and the high cost, the treatment and restoration of heavy metal pollution in soil is currently a hot and difficult point in the research of heavy metal pollution restoration. [0003] Soil heavy metal pollution refers to the phenomenon that the accumulation of heavy metals in the soil due to natural activities or human activities is significantly hi...

AI Technical Summary

Problems solved by technology

However, these reducing agents may be washed away by rainwater in southern weather conditions, which will affect the repair effect, so other processes are needed, which increases the complexity and operation difficulty of the repair process

[0006] Chromium salt-contaminated sites usually show that the upper layer is a mixture of chromium slag and polluted soil. The concentration of hexavalent chromium is high and the pH is high. As the depth deepens, the concentration and pH of hexavalent chromium gradually decrease until The risk is lower than the acceptable risk level of the human body. The existing methods do not distinguish the soil properties, and uniformly adopt the same repair method, which not only wastes materials, is time-consuming and laborious, and the repair effect is not ideal. There is no long-term tracking and monitoring, and the repair effect cannot be guaranteed for a long time. The problem of stability, that is, after trivalent chromium forms chromium hydroxide precipitates or organic complexes, without long-term and multiple follow-up monitoring, it is impossible to determine whether the concentration of hexavalent chromium is within the design requirements. Dissolution, re-oxidation and other problems, the long-term stability of the repair effect cannot be guaranteed; at the same time, in the face of the serious problems of hexavalent chromium pollution and the urgent requirements of the national environmental protection policy, repair methods, repair agents and repair equipment should be considered It has the possibility of large-scale implementation, or has passed the test of large-scale construction. It should have corresponding theoretical research data and detailed engineering implementation parameters to guide the promotion and application. Most of the above-mentioned studies do not have this feature.