Treatment method of chromium-polluted soil

A technology for chromium-contaminated soil and soil, which is applied in the field of in-situ solidification/stabilization of high-concentration hexavalent chromium-contaminated soil, and can solve problems such as complicated operation, inapplicable emergency repair treatment, and high requirements for treatment coordination

Inactive Publication Date: 2011-11-02
CHINA UNIV OF GEOSCIENCES (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has obvious economic benefits, social benefits and environmental benefits, but for the in-situ emergency treatment and repair of chromium pollution in sudden major environmental pollution accidents, this method has its own limitations in addition

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] The concentration of hexavalent chromium in the soil was calculated based on the concentration of the leach solution to be 7321.92mg / kg. Add ferrous sulfate heptahydrate solution that is 3 times the calculated value of the chemical reaction with Cr(Ⅵ) in the soil to the soil, the water-to-soil mass ratio is 1:1.5, and stir for 5 minutes; add the calcium hydroxide solution after an interval of 24 hours. It was 1:1.5, and stirred again for 5 minutes.

[0046] Test results: After adding calcium hydroxide, after 1d, 5d, 10d, and 20d, the solidification / stabilization rates of hexavalent chromium were 99.98%, 99.78%, 99.81%, and 99.84%, and the concentrations of hexavalent chromium in the soil leachate were 0.13 mg / L, 1.64mg / L, 1.40mg / L, and 1.19mg / L, all of which are lower than the 5mg / L standard for the concentration of hexavalent chromium in the "Identification Standard for Hazardous Waste Leach Toxicity Identification (GB5085.3-2007)".

Embodiment 2

[0048] The concentration of hexavalent chromium in the soil was calculated according to the concentration of the leach solution to be 4286.62mg / kg. Add ferrous sulfate heptahydrate solution that is 3 times the calculated value of the chemical reaction with Cr(Ⅵ) in the soil to the soil, the water-to-soil mass ratio is 1:2, stir for 5 minutes; add the calcium hydroxide solution after an interval of 24 hours. It was 1:1.5, and stirred again for 5 minutes.

[0049] Test results: After adding calcium hydroxide, after 1d, 5d, 10d, and 20d, the solidification / stabilization rates of hexavalent chromium were 99.95%, 99.60%, 99.57%, and 99.59%, and the concentrations of hexavalent chromium in the soil leachate were 0.23 mg / L, 1.71mg / L, 1.84mg / L, and 1.76mg / L, all of which are lower than the 5mg / L standard for hexavalent chromium concentration in the "Identification Standard for Hazardous Waste Leach Toxicity Identification (GB5085.3-2007)".

Embodiment 3

[0051] The hexavalent chromium concentration in the soil was calculated based on the leachate concentration to be 8059.25mg / kg. Add ferrous sulfate heptahydrate solution that is 5 times the calculated value of the chemical reaction with Cr(Ⅵ) in the soil to the soil, the water-to-soil mass ratio is 1:1.5, stir for 10 minutes; add the calcium hydroxide solution after an interval of 24 hours. It was 1:1.5, and stirred again for 10 min.

[0052] Test results: After adding calcium hydroxide, after 1d, 5d, 10d, and 20d, the solidification / stabilization rates of hexavalent chromium were 99.98%, 99.87%, 99.84%, and 99.88%, and the concentrations of hexavalent chromium in the soil leachate were 0.13 mg / L, 1.05mg / L, 1.26mg / L, and 0.97mg / L are all lower than the 5mg / L standard for the concentration of hexavalent chromium in the "Identification Standard for Hazardous Waste Leach Toxicity Identification (GB5085.3-2007)".

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Abstract

The invention discloses a treatment method of chromium-polluted soil, which comprises the following steps of: 1, adding a ferrous iron salt solution in the chromium-polluted soil, uniformly stirring to ensure that a ferrous iron salt reacts with hexavalent chromium in the soil, and reducing the hexavalent chromium in the soil into trivalent chromium; and 2, adding a lime solution in the soil obtained from the step 1, and uniformly stirring to ensure that the trivalent chromium in the soil is converted into chromium hydroxide. The high-concentration chromium-polluted soil is treated by using an in situ curing/stabilizing method, thus the treatment method is rapid and efficient, is simple in operation, and is especially suitable for in situ emergence treatment of chromium pollution accidents caused by paroxysmal heavy environmental contamination events. The curing/stabilizing rate reaches above 99 percent.

Description

technical field [0001] The invention relates to a treatment method for chromium-contaminated soil, in particular to an in-situ solidification / stabilization method for high-concentration hexavalent chromium-contaminated soil. Background technique [0002] Chromium-containing compounds are widely used in metallurgy, electroplating, tanning, metal processing, pigments, paints and other industries, resulting in frequent incidents of sudden high-concentration chromium pollution to the soil, which is harmful to the environment on which people live and human beings. itself poses great danger. [0003] Chromium exists mainly in two forms of Cr(Ⅲ) and Cr(Ⅵ) in the soil environment, among which Cr(Ⅲ) has a small hydroxide solubility product and often exists in the form of insoluble chromium hydroxide in the environment; Cr (Ⅵ) compounds are highly oxidizing and highly toxic, and the World Health Organization has identified Cr(Ⅵ) compounds as carcinogens. At present, there are many t...

Claims

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Application Information

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IPC IPC(8): B09C1/08
Inventor 张焕祯赵茜赵慧敏张莹李飞庞博陈宗英唐敏
Owner CHINA UNIV OF GEOSCIENCES (BEIJING)
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