A construction method for in-situ injection of environmentally friendly chemicals to remediate polluted sites

Abstract

The invention discloses a construction method for injecting environmental-friendly agentia and repairing a contaminated site in situ. The construction method comprises the steps that small experiments are carried out; a vertical separating wall is built; the ground of a region to be repaired is covered with a compacted clay layer; injection construction points are positioned, and construction equipment is moved to the construction points; a waste molasses and acetic bacteria mixed solution is injected; the construction points are subjected to hole sealing; the construction equipment is moved; the compacted clay layer is paved with a seepage-proofing geomembrane, and the seepage-proofing geomembrane is connected with the separating wall; a sample is taken from the region to be repaired so that the pH value and redox potential can be detected; a micrometer iron powder and xanthan gum mixed solution is injected; the construction points are subjected to hole sealing; the construction equipment is moved; and the ground of the region to be repaired is covered with the seepage-proofing geomembrane. By means of the construction method, the effective action distance of the agentia can be remarkably increased, the reduction efficiency of contaminants in soil and underwater is improved, the pH value of a reaction system can be effectively balanced, and high-efficiency reduction repairing of the contaminants in the soil and the underwater can be achieved.

Description

technical field [0001] The invention belongs to the technical fields of civil engineering and environmental geotechnical engineering, and specifically relates to a construction method for in-situ injection of environment-friendly medicaments to repair polluted sites. Background technique [0002] Due to the rapid development of industrial agriculture, hexavalent chromium or chlorine-containing organic compounds that can be degraded by reduction are ubiquitous in reality. Among them, hexavalent chromium Cr(VI) is oxidizing, can strongly corrode and destroy organisms, is one of the three internationally recognized carcinogenic metals, and is listed as one of the eight most harmful chemical substances to the human body. One of the hazardous pollutants identified by the Environmental Protection Agency EPA. China has also listed chromium-containing waste as "hazardous waste". A large amount of hexavalent chromium (Cr(VI)) dissolves, loses, and seeps into the surface with rainwa...

AI Technical Summary

Problems solved by technology

[0003] Currently, the remediation technologies for sites contaminated by hexavalent chromium or chlorine-containing organic compounds include in-situ and ex-situ remediation technologies, but both have limitations to varying degrees, which are not conducive to large-scale promotion and use.

Among them, due to the need to move soil and extract groundwater for ex-situ restoration, the workload of earthwork is relatively large, and the degree of damage to the rock-soil environment is large, and the polluted soil excavated or extracted groundwater requires secondary treatment to remove pollutants, and the process is complicated. , the cost is high, and a variety of construction equipment is required, so it is only suitable for the remediation of small-area contaminated sites

However, the current in-situ restoration also has the following problems: (1) Cement solidification / stabilization technology Adding cement to the site soil makes the contaminated soil form a stable solidified body, and then seals hexavalent chromium in an inert matrix , reducing the ability of chromium in the soil to migrate to the surrounding environment, but it does not change the form of hexavalent chromium, and there is a hidden danger of re-pollution in the solidified contaminated soil in a complex environment; at the same time, the high alkalinity of cement solidified will change the soil and The acid-base balance of the water body has adverse effects on surrounding organisms; the soil strength after remediation is high, which is not conducive to subsequent sampling testing and earthwork excavation operations; in addition, cement solidification / stabilization technology has poor treatment effect on groundwater contaminated by hexavalent chromium

This technology uses a large amount of chemicals, and the acid-base environment is single, and the pH of the site soil and groundwater cannot be effectively restored after restoration; and it is easy to cause changes in the physical and chemical properties of soil minerals, and it is not suitable for strata with low permeability coefficients such as clay and silt; in addition The ferrous sulfate (FeSO 4 ), sodium metabisulfite (Na 2 S 2 o 5 ), ferrous chloride (FeCl 2 ) and other reducing agents contain a large amount of corrosive anions, which will cause secondary pollution to the soil and groundwater, and the safety of cement, steel bars and other structures in dangerous underground projects

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