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Method for cooperatively treating hexavalent chromium in contaminated soil through biogas residues and ferrous sulfate

A ferrous sulfate and polluted soil technology, applied in the restoration of polluted soil, etc., can solve the problems of unsuitable large-scale disposal of chromium-containing soil, corrosiveness, secondary pollution of sulfate, etc., to avoid unsustainable pollution of six Valence chromium is reduced, natural tolerance is strong, and the effect of avoiding secondary pollution

Inactive Publication Date: 2016-10-26
QINGDAO TECHNOLOGICAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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

[0016] (1) Mix biogas residue, carbon source solution and sodium sulfate 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%, organic carbon The mass ratio of sulfate / sulfate (calculated as SO4) is 10:1, and the mixed solution undergoes a biochemical reaction for 1 day to obtain chromium soil remediation agent;

[0017] (2) Excavate the chromium-containing site soil, crush the site soil to less than 10mm in particle size, and then mix it with the medicament and ferrous sulfate described in step (1), in a mixing ratio of ferrous sulfate, chromium-containing soil and medicament. The mass ratio is 0.05:1:0.5, and then add an appropriate amount of water for maintenance. During the maintenance, the soil moisture content is kept at 5-80%. After 15 days of maintenance, the hexavalent chromium content in the soil is reduced from 2400mg / kg to 3mg / kg, and the restoration is up to s...

Embodiment 2

[0019] (1) Mix biogas residue, carbon source solution and sodium sulfate according to a certain ratio, control the dry biogas residue content of the mixed solution to be 5-15%, solid content 5-15%, organic carbon content 5-15%, organic carbon The mass ratio of sulfate / sulfate (calculated as SO4) is 10:1, and the mixed solution undergoes a biochemical reaction for 1 day to obtain chromium soil remediation agent;

[0020] (2) Excavate the chromium-containing site soil, crush the site soil to less than 10mm in particle size, and then mix it with the medicament and ferrous sulfate described in step (1), in a mixing ratio of ferrous sulfate, chromium-containing soil and medicament. The mass ratio is 0.2:1:0.4, and then an appropriate amount of water is added for maintenance. During the maintenance period, the soil moisture content is maintained at 80%. After 15 days of maintenance, the hexavalent chromium content in the soil is reduced from 15400mg / kg to 4mg / kg, and the restoration ...

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Abstract

The invention provides a method for cooperatively treating hexavalent chromium in contaminated soil through biogas residues and ferrous sulfate. The biogas residues, a carbon source and the ferrous sulfate are mixed and prepared into a mixed agent used for treating chromium-contained soil. In the process, sulfate reducing bacteria in the biogas residues are used for reducing sulfate in the ferrous sulfate to generate sulfide, secondary contamination of the sulfate is avoided while the hexavalent chromium is reduced more effectively, and the sulfate reducing bacteria in the biogas residues and used for reducing the hexavalent chromium can be increased in a large scale.

Description

technical field [0001] The invention provides a method for synergistically treating hexavalent chromium in polluted soil by utilizing biogas residue and ferrous sulfate. The biogas residue, carbon source and ferrous sulfate are mixed to prepare a mixed agent for treating chromium-containing soil. During the process, the sulfate-reducing bacteria in the biogas residue reduce the sulfate in the ferrous sulfate to generate sulfide. While reducing the hexavalent chromium more effectively, the secondary pollution of the sulfate is avoided, and it 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....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08B09C1/10
CPCB09C1/08B09C1/10
Inventor 张大磊李健孙箫
Owner QINGDAO TECHNOLOGICAL UNIVERSITY
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