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Novel contaminated soil hexavalent chromium detoxification method based on biogas residues

A technology for polluted soil and hexavalent chromium, which is applied in the restoration of polluted soil and other directions, can solve the problems of unsuitable large-scale disposal of chromium-containing soil, corrosiveness, secondary pollution of sulfate, etc. Oxidation, strong natural tolerance, the effect of avoiding secondary pollution

Inactive Publication Date: 2016-09-21
QINGDAO TECHNOLOGICAL UNIVERSITY
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  • Summary
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AI Technical Summary

Problems solved by technology

Although this method can restore chromium-containing soil, it consumes a lot of electricity and takes a long time to treat, so it is not suitable for large-scale disposal of chromium-containing soil.
However, the chemical reagents such as ferrous iron or sulfide used in the current in-situ repair method also have the problem of secondary pollution, and are easily oxidized by the environment to cause functional failure.
Patent No. 201310642919.6 introduces a method for in-situ restoration of Cr(VI)-containing sites using organic waste, which is a low-cost way to dispose of hexavalent chromium soils, but this method can only be used for soils with a natural anti-seepage layer at the bottom , otherwise it will accelerate the penetration of hexavalent chromium into the ground, resulting in the diffusion of hexavalent chromium
[0003] At present, the mainstream process of chromium-containing soil is still to use ferrous sulfate to reduce hexavalent chromium, but the pH of ferrous sulfate is too low, it is corrosive, and it is easy to be oxidized and deactivated in the air. , so the reduction of hexavalent chromium can only be short-term, not long-term reduction
In order to effectively treat chromium-containing soil, it is often necessary to add excessive ferrous sulfate, which is likely to cause secondary pollution of sulfate radicals
Patent No. 201410101586.0 introduces a method of using ferrous sulfate to repair Cr(VI)-containing sites in situ. Since ferrous is easy to oxidize and fail in the air, this method uses low pH citric acid to inhibit its oxidation and increase the penetration of ferrous , but correspondingly increases the cost, and makes the soil acidified, and still brings secondary pollution of sulfate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] (1) Mix ferrous sulfate, biogas residue and carbon source solution according to a certain ratio, control the content of dry biogas residue in the mixed solution to be 0.1-5%, solid content 0.5-5%, organic carbon content 0.5-5%, sulfuric acid The mass ratio of salt (in SO4) / organic carbon is 0.2: 1, and the solution after mixing is reacted for 1 day to obtain chromium soil remediation agent;

[0019] (2) Excavate the chromium-containing site soil, crush it to less than 5mm, then mix it with the agent described in step (1), and the mixing ratio is that the mass ratio of the chromium-containing soil to the agent is 1:(0.4-0.5), and then place it Closed storage in the yard;

[0020] (3) During the storage period, spray water on the surface of the site every 5 days. The average spraying amount of the site is equivalent to 60-80mm of rainfall. Natural rainfall can replace artificial spraying. After 2 times of water spraying, the soil The content of hexavalent chromium is les...

Embodiment 2

[0022] (1) Mix biogas residue, sodium sulfate and carbon source solution according to a certain ratio, control the content of dry biogas residue in the mixed solution to be 10-20%, solid content 10-25%, organic carbon content 10-25%, sulfate (Recorded in SO4) / organic carbon mass ratio is (0-1): 1, and the mixed solution is reacted for 0-5 days to obtain chromium soil remediation agent;

[0023] (2) Excavate the soil of the chromium-containing site, crush it to less than 5mm, then mix it with the agent described in step (1), the mixing ratio is 1:0.3 by mass ratio of the chromium-containing soil to the agent, and then place it in the storage yard for sealing stockpile;

[0024] (3) During the storage period, spray water on the surface of the site every 8 days. The average spraying amount of the site is equivalent to the rainfall of 20-100mm. Natural rainfall can replace artificial spraying. After 3 times of water spraying, the soil The content of hexavalent chromium is less th...

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Abstract

The invention discloses a novel method for treating Cr(VI) contaminated soil. Biogas residues, a carbon source and ferrous sulfate are prepared into a medicament to be applied to chromium-containing soil; and then a special curing mode is adopted. The method can reduce hexavalent chromium at low cost and at high efficiency, and prevents secondary pollution of the sulfate and the biogas residues.

Description

technical field [0001] The present invention provides a new method for treating Cr(VI) polluted soil. Biogas residue, carbon source and ferrous sulfate are formulated into medicaments and applied to chromium-containing soil, and then a special maintenance method is adopted to efficiently reduce hexavalent chromium , while avoiding the secondary pollution of sulfate, which belongs to 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. On the other hand, how to remediate chromium-containing soil has always been a difficult problem in the environmental protection circle. Although there are many disposal ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/10B09C1/08
CPCB09C1/105B09C1/08
Inventor 张大磊李瑞栋王欣玉
Owner QINGDAO TECHNOLOGICAL UNIVERSITY
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