Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil

A chromium-contaminated soil and countercurrent washing technology is applied in the field of contaminated soil remediation and treatment, which can solve the problems of large water consumption, incomplete removal of hexavalent chromium, heavy water treatment burden, etc., to reduce water consumption, avoid incomplete removal, and operate easy effect

Inactive Publication Date: 2010-05-19
CHINESE RES ACAD OF ENVIRONMENTAL SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Ex-situ cleaning technology can completely separate and remove hexavalent chromium from the soil, and the repaired soil can be backfilled and reused, especially suitable for situations with poor permeability and short disposal cycle, but the repair process requires large water consumption and water treatment burden Heavy, poor control of the washing process can easily lead to incomplete removal of hexavalent chromium

Method used

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  • Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil
  • Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil
  • Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Take the polluted soil around the chromium slag dump of a chromium salt chemical plant in Haibei, Qinghai as an example. The chemical plant produces sodium alum (Na 2 Cr 2 o 7 2(H 2 O)) about 4,000 tons, 48,000 cubic meters of chromium slag have been accumulated and simply piled up. The simple stacking of chromium slag has seriously polluted the soil and groundwater around the chemical plant. The soil used in this example is sandy loam, the total chromium content in the soil is 443.69 mg / kg, and the hexavalent chromium content is 151.18 mg / kg.

[0025] Proceed as follows:

[0026] (1) Air-dry the soil sample, remove large rocks, tree roots, paper and other substances;

[0027] (2) Take 50g of soil, use the waste water from the secondary washing to carry out the primary washing according to the liquid-solid ratio of 10:1, shake at room temperature (20°C) for 40min, and dry the soil naturally after solid-liquid separation;

[0028] (3) Take 30 g of the soil after the...

Embodiment 2

[0034] Take the polluted soil around the chromium slag dump of a chromium salt chemical plant in Huangzhong, Qinghai as an example. The soil of the site belongs to silty loam. The total chromium content in the soil is 2348.01mg / kg, and the hexavalent chromium content is 1418.41mg / kg.

[0035] Proceed as follows:

[0036] (1) Air-dry the soil sample, remove large rocks, tree roots, paper and other substances;

[0037] (2) Take 50g of soil, use the waste water from the secondary washing to carry out the primary washing according to the liquid-solid ratio of 10:1, shake at room temperature (20°C) for 40min, and dry the soil naturally after solid-liquid separation;

[0038] (3) Take 30 g of the soil after the first-level washing, and carry out the second-level washing with clean water that has been treated up to the standard at a liquid-solid ratio of 10:1, shake at room temperature (20° C.) for 40 minutes, and separate the solid and liquid;

[0039] (4) Take 20g of the soil aft...

Embodiment 3

[0044] Taking the polluted soil around the chromium slag dump of a chromium salt chemical plant in Qingdao as an example, the soil sample belongs to cohesive loam. The total chromium content in the sample was 3025.01mg / kg, and the hexavalent chromium content was 1388.41mg / kg.

[0045] Proceed as follows:

[0046] (1) Air-dry the soil sample, remove large rocks, tree roots, paper and other substances;

[0047] (2) Take 50g of soil, use the waste water from the secondary washing to carry out the primary washing according to the liquid-solid ratio of 10:1, shake at room temperature (20°C) for 40min, and dry the soil naturally after solid-liquid separation;

[0048](3) Take 30 g of the soil after the first-level washing, and carry out the second-level washing with clean water that has been treated up to the standard at a liquid-solid ratio of 10:1, shake at room temperature (20° C.) for 40 minutes, and separate the solid and liquid;

[0049] (4) Take 20g of the soil after second...

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Abstract

The invention relates to a two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil, comprising the following steps of: (1) pouring polluted soil into fist-stage washing equipment, stirring and washing the soil with a liquid-to-solid ratio of 10:1 and then carrying out solid-liquid separation; filling separated waste water into a water treatment system, and pouring dewatered soil into second-stage washing equipment; (2) using clearing water which is treated by the water treatment system and reaches the standard as the water of the second-stage washing equipment, stirring and washing the dewatered soil with a liquid-to-solid ratio of 10:1 and then carrying out solid-liquid separation; sending separated washing liquid to the first-stage washing equipment for recycling; (3) adding FeSO4 to the soil after second-stage washing to carry out stabilization treatment, wherein the addition quantity of the FeSO4 is 1-5 percent of the soil to further reduce the content of Cr6 in the soil and reduce the pH to 6-9 meanwhile; and (4) directly backfilling the stabilized soil. The invention has the advantages of thorough elimination of hexavalent chromium pollution, low price and easy obtain of medicaments, environmental security, use function recovery of restored soil, and the like.

Description

technical field [0001] The invention belongs to the technical field of remediation and treatment of polluted soil, and in particular relates to a combined remediation method of two-stage countercurrent ectopic washing and agent stabilization for chromium-contaminated soil. Background technique [0002] The chromium slag produced by the chromium salt industry and the chromium alloy industry has caused serious pollution to the environment, so many chromium salt enterprises were forced to stop production. As of 2006, my country has accumulated more than 6 million tons of chromium slag in history, and closed about 50 chromium salt enterprises. The simple stacking of chromium slag and the long-term production of chromium salt enterprises have caused serious pollution to the surrounding soil and groundwater. Cr in the surface soil of some sites 6+ The content is as high as 6000mg / kg, Cr in groundwater 6+ The concentration reaches 400mg / L, which far exceeds the 0.05mg / L required ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08
Inventor 王兴润王琪张厚坚颜湘华刘雪
Owner CHINESE RES ACAD OF ENVIRONMENTAL SCI
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