A double-layer permeable reactive wall system for repairing chromium-contaminated groundwater

Abstract

The invention relates to a double-layer permeable reactive barrier system for repairing chromium-polluted underground water. The double-layer permeable reactive barrier system comprises a reduction reaction barrier and an adsorption reaction barrier behind the reduction reaction barrier, wherein the space between the reduction reaction barrier and the adsorption reaction barrier is 2.5-5m, the bottom ends of the reduction reaction barrier and the adsorption reaction barrier stretch into an impervious bed by at least 0.60-0.8m, and the tops of the reduction reaction barrier and the adsorption reaction barrier are 0.4-0.5m higher than the maximum water level of the underground water. When the double-layer permeable reactive barrier system is used, the polluted stream sequentially flows through the reduction reaction barrier and the reduction reaction barrier; when flowing through the system, the chromium-polluted underground water firstly flows through the reduction reaction barrier to generate a reduction reaction with zero-valent iron powder to convert hexavalent chromium into trivalent chromium, and organic matters in straw can be taken as electron donors to accelerate the reduction of the hexavalent chromium; a biomass adsorbent has a huge surface area, the residual pollutants can be strongly adsorbed by the adsorption reaction barrier, so that the problems that a reductant is washed away, reduction products are diluted and washed away, the reduction of the hexavalent chromium cannot be realized when the utilization of the reductant is saturated, and the like are solved, and the chromium pollution in the underground water is economically and efficiently removed.

Description

technical field [0001] The invention belongs to the field of groundwater environmental pollution prevention and control, and in particular relates to a double-layer permeable reaction wall system for repairing chromium-contaminated groundwater. Background technique [0002] The toxicity of chromium mainly comes from hexavalent chromium, which is listed as one of the eight most harmful chemical substances to the human body, one of the three internationally recognized carcinogenic metals, and one of the 129 key pollutants recognized by the US EPA one. [0003] The remediation of chromium-contaminated groundwater usually adopts the extraction-surface chemical treatment method, but there are disadvantages such as high cost, long cycle, high energy consumption, and easy to cause secondary pollution on the ground. In recent years, zero-valent iron PRB technology has rapidly emerged due to its advantages of low energy consumption and no secondary pollution. In this process, an exc...

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Problems solved by technology

[0003] The restoration of chromium-contaminated groundwater usually adopts extraction-surface chemical treatment, but there are disadvantages such as high cost, long cycle, high energy consumption, and easy to cause secondary pollution on the ground.

In recent years, the zero-valent iron PRB technology has rapidly emerged due to its advantages of low energy consumption and no secondary pollution. In this process, an excessive amount of reducing agent is required, so the reducing agent will be washed away during actual use. , The reduction product is diluted and washed away, the reducing agent is saturated, etc.