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A combined method for repairing heavy metal-contaminated soil

A technology of combined restoration of contaminated soil, applied in the restoration of contaminated soil, etc., can solve the problems of low phytoremediation efficiency, difficulty in mud-water separation, incomplete passivation, etc., and achieve the effects of preventing reactivation, reducing costs, and reducing content

Active Publication Date: 2020-07-21
NANJING UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, soil leaching restoration is mainly used in the restoration of industrial sites. For large-scale contaminated farmland restoration, soil leaching restoration requires a large amount of engineering and difficult separation of mud and water.
The invention aims to solve the problem of high-efficiency restoration of large-scale polluted farmland, and innovatively combines in-situ leaching, deep fixation, and phytoremediation to solve the problems of high cost of leaching, incomplete passivation, and low phytoremediation efficiency. question

Method used

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  • A combined method for repairing heavy metal-contaminated soil
  • A combined method for repairing heavy metal-contaminated soil
  • A combined method for repairing heavy metal-contaminated soil

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Embodiment 1

[0026] The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. Example 1 In situ leaching of heavy metal contaminated soil - deep fixation

[0027] Table 1 Basic properties of soil

[0028]

[0029] The restoration project of this embodiment is located in a polluted farmland in Yixing, Jiangsu Province. The farmland soil belongs to yellow-brown soil and is acidic. The soil properties are shown in Table 1. The cadmium content is 6.32 mg / kg, which exceeds my country's "Soil Environmental Quality Standard" (GB15618-1995) More than ten times the secondary standard, which seriously threatens the local ecological environment and human health.

[0030] In this embodiment, the soil in-situ leaching-deep fixation steps are as follows:

[0031] 1. After leveling the polluted farmland, compact the field ridges around them, and the height of the field ridges is 15cm;

[0032] 2. D...

Embodiment 2

[0044] Embodiment 2 Soil Organic Fertilizer Improvement-Phytoremediation of Heavy Metal Contaminated Soil

[0045] In Example 1, ferric chloride (group 3) was applied according to 2% of the dry weight of the plowed layer soil, and the removal rate of heavy metals in the soil was the best, but the soil acidification and nutrient loss were the most serious. This example will improve and phytoremediate the soil. The operation steps are as follows:

[0046] 1. After rinsing, apply commercially available organic fertilizers on the soil surface, and the application amount is 1% of the dry weight of the soil in the cultivated layer (the specific application ratio can also refer to the instructions of the organic fertilizers), and rotary tillage and mixing.

[0047] 2. Select 0.5-1.5cm thick weeping willow branches, remove the twigs, and cut them into cuttings about 15cm long. During the preparation of willow cuttings, minimize the wound area.

[0048] 3. Plant weeping willow in the...

Embodiment 3

[0055] Example 3 Liu 785 remediation of heavy metal Cd polluted soil

[0056] This example is located in a park in Changshu City, Jiangsu Province. The soil is dredging sludge at the bottom of the lake. The Cd concentration in the soil is 0.93 mg / kg, which exceeds the maximum allowable content of pollutant cadmium in farmland soil in my country's second-level soil environmental quality standard. 0.6mg / kg, it will cause great harm to agricultural production and human health, so the soil in this area needs to be repaired urgently. The steps of this embodiment are as follows:

[0057] 1. After leveling the soil, dig a 50-60cm deep trench with a width of 5-10cm and a distance of 0.5m-1m;

[0058] 2. Apply lime in the deep ditch, according to 2% of the dry soil weight of the cultivated layer (soil within 0-20cm from the surface soil), about 4.8kg / m 2 , and then backfill the contaminated soil;

[0059] 3. Evenly apply the eluting agent ferric chloride on the soil surface, and the ...

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Abstract

The invention discloses a method for remediating soil contaminated by heavy metals such as cadmium by combining in-situ leaching, deep-layer fixing and phyto-extracting. According to the method, the heavy metals are leached into a deep layer along with a leaching solution through the in-situ leaching in a surface layer and are fixed in the deep layer, then willow with the heavy metal accumulation function is planted after organic fertilizer is applied, and therefore the residual heavy metals can be further removed, and the soil function can be restored; the heavy metals in a plough layer are leached to the deep layer, the absorption of crops to the heavy metals is reduced, the heavy metals which are leached to the deep layer are fixed, underground water is not polluted, and therefore the residual heavy metals can be further removed through phytoremediation, and the soil function can be restored; an iron-containing compound used in the method does not destroy the soil structure and can serve as a rice field soil conditioner; and compared with the phytoremediation, the method has the advantage that the remediation efficiency can be improved, and compared with leaching remediation, the method has the advantage that the steps of excavating, stirring, separating and the like can be omitted. The invention provides the remediation method. The remediation method has the advantages of being short in time, low in cost and high in efficiency and having a wide application prospect in the field of remediation of a large-scale farmland contaminated by the heavy metals.

Description

technical field [0001] The invention relates to the field of soil heavy metal pollution control, in particular to a combined method of in-situ leaching-deep fixation-phytoremediation of heavy metal polluted soil. Background technique [0002] In the past few decades, due to the development of mineral processing and smelting industry and the lack of environmental protection laws and environmental awareness, a large area of ​​soil in my country has been polluted by heavy metals (such as cadmium, mercury, arsenic, copper, lead, chromium, zinc, etc.), " The National Soil Pollution Survey Bulletin shows that 16.1% of my country's soil is polluted, and 19.4% of cultivated land is polluted, among which cadmium pollution is the most prominent, with an exceeding rate of 7%. Heavy metals are not biodegradable and highly toxic, and are easy to accumulate in crops and enter the food chain, causing food production reduction and endangering human health. However, the conflict between peop...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B09C1/00B09C1/02
CPCB09C1/02B09C1/105B09C2101/00
Inventor 郭红岩王国兵艾弗逊张庆泉杜文超王保松何旭东尹颖
Owner NANJING UNIV
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