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Thermal decomposition repairing method containing chromium soil

A remediation method and soil technology, applied in the restoration of polluted soil and other directions, can solve the problems of easy generation of leachate, pollute the surrounding environment, unsustainable remediation, etc., and achieve the effect of improving treatment efficiency, short pyrolysis time and remarkable effect.

Inactive Publication Date: 2008-08-27
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is an in-situ remediation technology, but the biggest problem is that it is easy to produce leachate and pollute the surrounding environment. There is a certain saturation capacity for the absorption and enrichment of chromium by plants, so it cannot be repaired continuously, and the toxicity of chromium to plants and secondary secondary pollution problem

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Put the contaminated soil containing chromium 1000ppm (1000mgCr / 1kg soil) into the oven for drying, so that the moisture content of the dried soil is lower than 15%, and the soil is ground to make the soil particle size less than 2mm, and then dehydrated with the sewage treatment plant The sludge is mixed, and the mass ratio of soil to sludge is 1:0.1. The above mixture of soil and sludge is stirred evenly and sent to an electric furnace for pyrolysis at 500°C for 0.1 hour without air.

[0026] Test Results:

[0027] Using the national standard GB5086.2 horizontal shaking method to conduct toxicity leaching experiments on the treated chromium slag, the measured water-soluble chromium content is less than 0.8mg / L, which is lower than the national standard GB5085.3 hazardous waste upper limit of 1.5mg / L.

Embodiment 2

[0029] Contaminated soil containing chromium 1000ppm (1000mgCr / 1kg soil) is sent into an oven for drying, and the moisture content of the dried soil is lower than 15%, and the soil is ground to make the soil particle size less than 2mm, and then mixed with rice husk, The mass ratio of soil to rice husk is 1:0.5. The above mixture of soil and rice husk is stirred evenly and sent to an electric furnace for pyrolysis at 300° C. without air for 0.5 hours.

[0030] Test Results:

[0031] Using the national standard GB5086.2 horizontal shaking method to conduct toxicity leaching experiments on the treated chromium slag, the measured water-soluble chromium content is less than 0.6mg / L, which is lower than the national standard GB5085.3 hazardous waste upper limit of 1.5mg / L.

Embodiment 3

[0033] Contaminated soil containing chromium 5000ppm (5000mgCr / 1kg soil) is sent into an oven for drying, and the moisture content of the dried soil is lower than 15%, and the soil is ground to make the soil particle size less than 2mm, and then mixed with cow dung, The mass ratio of soil to cow dung is 1:0.1. Stir the above mixture of soil and cow dung evenly and send it into an electric furnace for pyrolysis at 800°C for 1.5 hours under the condition of feeding inert gas.

[0034] Test Results:

[0035] Using the national standard GB5086.2 horizontal shaking method to conduct toxicity leaching experiments on the treated chromium slag, the measured water-soluble chromium content is less than 1.0mg / L, which is lower than the national standard GB5085.3 hazardous waste upper limit of 1.5mg / L.

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Abstract

The invention relates to a pyrolysis remediation method of chromium-containing soil, which comprises the following steps of: selecting dewatered sludge or other organic matter of an urban sewage treatment plant as reducer, mixing chromium-containing soil and the organic matter by a certain ratio, feeding into an electrical furnace, and carrying out reductive pyrolysis reaction in reducing atmosphere. The method can detoxicate contaminated soil at high efficiency without destroying the basic structure and the property of the soil, and has the advantages of short pyrolysis time, sufficient utilization of other organic wastes such as the excess sludge of the sewage plant, and significant economical and environmental effects.

Description

technical field [0001] The invention relates to a pyrolysis restoration method for chromium-containing soil, which uses sludge as an additive to reduce hexavalent chromium in the soil through a reducing atmosphere generated by pyrolysis. The invention belongs to the soil remediation technology in the field of environmental protection. Background technique [0002] Chromium and its compounds are commonly used basic raw materials in metallurgy, metal processing, electroplating, tanning, paint, pigment and other industries. During the production process of the above industries, a large amount of chromium-containing waste gas, waste water and waste residue are produced, resulting in serious environmental pollution problems. [0003] The common forms of chromium in the environment are trivalent chromium and hexavalent chromium. Trivalent chromium often exists in the form of insoluble hydroxide in soil, and the concentration of trivalent chromium in the solution is very small, so...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08A62D3/37
Inventor 彭亢晋孙绪顺张大磊孔海南吴德意
Owner SHANGHAI JIAO TONG UNIV
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