CN115228918A - Soil extractant and method for repairing heavy metal contaminated soil by using same - Google Patents

Soil extractant and method for repairing heavy metal contaminated soil by using same Download PDF

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CN115228918A
CN115228918A CN202210909285.5A CN202210909285A CN115228918A CN 115228918 A CN115228918 A CN 115228918A CN 202210909285 A CN202210909285 A CN 202210909285A CN 115228918 A CN115228918 A CN 115228918A
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soil
extractant
solution
water
heavy metal
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陈浩
李梦云
刘宏瑞
汪越
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Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
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Wuhan Surveying Geotechnical Research Institute Co Ltd of MCC
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/08—Reclamation of contaminated soil chemically
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B79/00—Methods for working soil
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
    • A01B79/00—Methods for working soil
    • A01B79/02—Methods for working soil combined with other agricultural processing, e.g. fertilising, planting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/10—Reclamation of contaminated soil microbiologically, biologically or by using enzymes
    • B09C1/105—Reclamation of contaminated soil microbiologically, biologically or by using enzymes using fungi or plants

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  • Engineering & Computer Science (AREA)
  • Soil Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
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  • Environmental Sciences (AREA)
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  • Molecular Biology (AREA)
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Abstract

The invention provides a soil extractant and a method for repairing heavy metal contaminated soil by using the same. The soil extraction agent is composed of HCL solution and CaCl 2 Solution, DTPA solution and water-soluble allyl isothiocyanate solution. The repairing method of the invention dilutes the polluted soil, reduces the concentration of heavy metals in the soil, simultaneously adjusts the water content in the soil, adds the soil extractant into the diluted soil, fully mixes, stands, leaches with clear water, then adds the soil conditioner and stirs evenly, finally adds animals, utilizes the soil to make use of the soilAnimals absorb heavy metals, meanwhile, the plants and the microorganisms are used for combined remediation, and the plants and the symbiotic microorganism system thereof are used for combined remediation of the improved soil. The soil remediation agent can effectively remove harmful substances in soil, has a good soil remediation effect, reduces the remediation period, reduces the remediation cost, and has a wide application prospect.

Description

Soil extractant and method for repairing heavy metal contaminated soil by using same
Technical Field
The application relates to a soil remediation technology, in particular to a soil extractant and a method for remediating heavy metal contaminated soil by using the same.
Background
Soil is a main natural resource on which human beings rely for survival, and is also an important component of the human ecological environment. With the pollution of industrial cities, the use of agricultural chemicals, the development of mineral resources and the like, the heavy metal pollution of soil is increasingly serious. The soil heavy metal pollution refers to pollution caused by metals or compounds thereof with the specific gravity of more than 5 in the soil environment, the cultivated land area polluted by heavy metals such As Cd, cr, as, pb and the like in China is nearly 2000 ten thousand, and when the concentration of the heavy metals exceeds a limit value, the heavy metals bring great harm to living organisms, hinder the exertion of basic metabolic functions, and change the active structure of biomolecules to cause organism variation.
Because the heavy metal pollutants have poor mobility and long residence time in the soil, can not be degraded by microorganisms, can finally influence the health of human beings through media such as water, plants and the like, and seriously threatens the life safety of the human beings, measures are taken to repair the heavy metal polluted soil, and the land damaged by pollution is very necessary to reclaim and mine. The existing method for repairing the contaminated soil is very difficult to repair, the soil repairing effect is not obvious, harmful substances in the soil cannot be removed, the economic investment is huge, the technology is also very difficult, the repairing period is long, and the development of the method for repairing the heavy metal contaminated soil is especially necessary on the basis.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a soil extracting agent and a method for repairing heavy metal contaminated soil by using the same.
In order to achieve the above object, the present invention provides a soil extractant, characterized in that: the soil extractant is 0.1-0.2mol/LHCL solution, 0.1-0.2mol/L CaCl 2 The solution, 0.04-0.06mol/L DTPA solution and 0.8-1.5mol/L water-soluble allyl isothiocyanate solution are mixed according to the mass ratio of 2.5-3.5: 1.5-2.5: 1.5-2.5: 0.5-1.5, and stirring and mixing uniformly at room temperature to form a mixed solvent after the components are fully dissolved.
The invention also provides a method for repairing heavy metal contaminated soil by using the soil extractant, which is characterized by comprising the following specific steps:
(1) Diluting the polluted soil: irrigating and diluting the polluted soil by using clear water, and adjusting the water content in the soil to be 5-8%;
(2) Preparing a soil extractant: preparing HCL into HCL solution with volume concentration of 0.1-0.2 mol/L; adding CaCl 2 Is prepared into CaCl with the volume concentration of 0.1-0.2mol/L 2 A solution; preparing DTPA into a DTPA solution with the volume concentration of 0.04-0.06 mol/L; preparing water-soluble allyl isothiocyanate into a water-soluble allyl isothiocyanate solution with the volume concentration of 0.8-1.5 mol/L; then adding the prepared HCL solution and CaCl 2 The solution, the DTPA solution and the water-soluble allyl isothiocyanate solution are mixed according to the mass ratio of 2.5-3.5: 1.5-2.5: 1.5-2.5: mixing at the ratio of 0.5-1.5, stirring uniformly at room temperature to fully dissolve the components, and storing in a plastic container for later use;
(3) Pretreatment: adding the soil extractant prepared in the step (2) into the soil diluted in the step (1), wherein the addition amount of the soil extractant is as follows: adding 20-25mL of soil extractant into every 1g of soil; mixing the soil extractant with the contaminated soil, standing for 20-30h, then leaching with clear water again to remove the residual soil extractant, and controlling the water content in the soil to be 4-7%;
(4) Adding a modifier into the pretreated soil, and stirring the soil and the modifier by excavating equipment, wherein the modifier comprises one or more of lime, organic fertilizer, epoxy resin silicon-containing curing agent, phosphate and biochar;
(5) Animals are added into the improved soil, and the animals in the soil are used for absorbing heavy metals, so that the content of the heavy metals in the polluted soil is reduced; the animals comprise one or two of earthworm and spider;
(6) Repairing by combining plants and microorganisms: finally, plants are planted in the sudden season, and the improved soil is repaired by combining the plants and the symbiotic microorganisms thereof.
The invention has the following excellent technical scheme: and (4) adding the soil extractant into the polluted soil in the step (3) for three times, wherein 1/3 of the soil extractant is added each time, and stirring the soil and the soil extractant by using excavating equipment after the soil extractant is added each time so as to uniformly mix the soil and the soil extractant.
The invention has the following excellent technical scheme: and (4) the residual extracting agent removed in the step (3) is cleaned by spraying clean water, the cleaning water liquid is combined with the pollutants extracted from the soil, and the pollutants adsorbed or fixed on the soil particles are desorbed and removed by desorption and dissolution of the cleaning water.
The invention has the advantages that: the plant in the step (6) is cruciferous plant, and comprises one or more of ciliate desert grass, ryegrass, indian mustard, sedum alfredii hance, leek grass, swertia macrophylla, pokeberry, viola baoshanensis, cardamine hupingshanensis, thalasia repens and vetiver grass.
The invention has the following excellent technical scheme: in the step (6), the microorganisms comprise any one or a combination of a plurality of polyphosphate, sulfur-containing protein, algae, cyanobacteria, sulfate reducing bacteria and gram positive bacteria, and the metabolism of the microorganisms is utilized to enrich heavy metal carbohydrate substances and absorb and oxidize heavy metal substances in the soil, so that the ecological environment of the soil is restored.
The HCL solvent in the soil extractant is used for extracting heavy metals in an exchange state and a use state, has the characteristics of wide application range and good application range, can maintain the pH of soil, reflects the pH in the soil and the dissolving power and characteristics of heavy metals in a natural state, is convenient for comparative analysis of extraction results, but has difficulty in result analysis due to small contents of the heavy metals in the exchange state and the use state during extraction of the HCL solvent, and is also unfavorable for analysis results due to high content and high background value of different heavy metals in the salt extractant, so that CaCl is added 2 DTPA and water-soluble allyl isothiocyanate, caCl 2 Can be helpful for extracting heavy metals such as cadmium, zinc, lead and the like, can also be used as an extractant of heavy metals in soil with different properties, and can be used in a wider application range; DTPA has stronger chelating ability, can extract some heavy metal ions which can not be utilized by plants, and water-soluble allyl isothiocyanate can strengthen the exchange ability of each heavy metal ion, is beneficial to release, further crushes soil particles, dissociates heavy metals, and improves the extraction rate. The soil extracting agent is added into the polluted soil in two to three times, the soil is stirred by excavating equipment every time of adding, and the mixture is uniformly mixed and then stands for 20 to 30 hours, so that related ions or molecules in the soil can be effectively extracted and separated, and the original composition and chemical properties in the soil are not changed. The residual extractant is cleaned by spraying clean water, the cleaning water liquid is combined with the pollutants extracted from the soil, and the pollutants adsorbed or fixed on the soil particles are desorbed and removed by the desorption and dissolution of the cleaning water.
The modifier comprises one or more of lime, organic fertilizer, epoxy resin silicon-containing curing agent, phosphate and biochar, wherein the lime can be used for modifying acid soil and can adjust the pH value of the acid soil; in the oxidation process of the organic fertilizer, certain heavy metals can form sulfide precipitates, the buffering capacity of soil is improved, and the toxicity of the metals is reduced; the epoxy resin silicon-containing curing agent can be directly cemented on the surface of soil particles in a soil body, reacts with clay minerals to generate gelled substances, and can also protect vegetation growth; the phosphate can make lead, iron, manganese, chromium, zinc, cadmium and other metals form insoluble phosphate; the biochar has a large specific surface area, high porosity and rich surface functional groups, can remove heavy metal ions and organic pollutants in soil, meanwhile, retains and enriches a large amount of nutrients such as N, P, K, ca and the like in biomass, and can improve soil fertility and promote plant growth as a soil conditioner.
The animals comprise earthworms and spiders, the heavy metal pollutants in the soil are absorbed by utilizing the growth characteristics of the earthworms and the spiders, the earthworms have good tolerance capability, the spiders have excellent absorption capability, the soil environment is purified by the enrichment of metals and the absorption of the animals, the heavy metal pollutants in the soil are transformed and enriched by utilizing the soil animals and microorganisms in the soil animals in the growth, the propagation and other activities of the soil polluted by the heavy metals, and finally the heavy metals in the soil are reduced by collecting and treating the soil animals, so that the effect of treating the polluted soil is achieved. In addition, soil animals are adopted to convert the form or enrichment of the heavy metals, so that organic matters in the soil can be decomposed and converted into organic acid, the heavy metals in the soil are passivated and lose toxicity, and the soil fertility is improved to a certain extent.
The plant of the invention adopts cruciferae plants, and comprises various combinations of ciliate desert-grass, ryegrass, indian mustard, sedum alfredii hance, leek, large-leaf swertia herb, pokeberry root, viola baoshanensis, cardamine hupingshanensis, thalathus serpyllum and vetiver grass. Through plant extraction, plant volatilization and plant stabilization, heavy metals in soil are extracted, enriched and carried to the parts which can be harvested at the roots of the plants and the branch parts on the plant ground or volatilized into the atmosphere, the rhizosphere environment is changed, the roots of the plants are used for filtering, absorbing and enriching the heavy metals, and the mobility of the heavy metals in the soil environment is reduced. The microorganisms comprise various combinations of polyphosphate, sulfur-containing protein, algae, cyanobacteria, sulfate reducing bacteria and gram positive bacteria, the metabolism of the microorganisms is utilized to reduce the toxicity of heavy metal pollutants in the soil, and the microorganisms can enrich the saccharides of the heavy metals and absorb and oxidize and reduce the heavy metal substances in the soil in the metabolic activity process, so that the aim of restoring the ecological environment of the soil is fulfilled.
The repair principle of the invention is as follows: firstly, diluting and pretreating polluted soil, adding a soil extracting agent into the soil polluted by heavy metals, and combining the soil extracting agent with the heavy metals to convert part of the heavy metals into liquid state so as to reduce the concentration of the heavy metals in the soil; after the residual extractant is removed, the modifier is added, so that the metal fixation is improved, and the migration and bioavailability of the metal in the environment are reduced; finally, the heavy metal pollutants in the soil are absorbed through combined restoration of animals, plants and microorganisms, organic matters in the soil can be decomposed and converted into organic acid, the heavy metals in the soil lose toxicity, the animals have strong tolerance and enrichment capacity to the heavy metals, the heavy metals in the soil can be enriched by methods which are difficult to realize, root systems of the plants provide proper nutritional conditions for the microorganisms, the maintenance of the number and activity of the microorganisms in severe environments is guaranteed, the microorganisms activate the heavy metals, and the absorption of the plants is promoted. In addition, the earthworms, spiders and other animals can directly enrich heavy metals, and the penetration activities of the earthworms, the spiders and other animals in the soil can play a role in catalyzing, so that the earthworms, the plants and the microorganisms around the earthworms and the microorganisms can cooperatively enrich the heavy metals, the transfer speed of the microorganisms to the polluted soil is accelerated, and the soil restoration effect of the microorganisms is promoted.
The method can improve the soil environment, avoid the residue of harmful substances, effectively remove the harmful substances in the soil, ensure that the soil is repaired more thoroughly, has good repairing effect, short repairing period, reduced repairing cost, restored soil economic value, and wide application prospect, and can be used in a state of reducing the cost of repairing the soil.
Drawings
FIG. 1 is a repair flow diagram of the present invention.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Referring to fig. 1, the process flow of the present invention is as follows:
(1) Diluting the contaminated soil: irrigating and diluting by using clear water, reducing the concentration of heavy metals in the soil, and simultaneously adjusting the water content in the soil to 5-8%;
(2) Pretreatment: adding a soil extractant into the diluted soil, fully mixing, standing, then rinsing with clean water again, and removing the residual extractant;
(3) Adding a modifier into the pretreated soil, and stirring the soil and the modifier by using excavating equipment;
(4) Animals are added into the improved soil, and the animals in the soil are used for absorbing heavy metals, so that the content of the heavy metals in the polluted soil is reduced;
(4) Repairing by combining plants and microorganisms: planting plants, and repairing the improved soil by combining the plants and the symbiotic microorganism system thereof.
In the embodiment of the invention, the soil extractant adopts HCL and CaCl 2 The preparation method of the mixed solvent of DTPA and water-soluble allyl isothiocyanate comprises the following steps: preparing HCL into HCL solution with volume concentration of 0.1-0.2mol/L, caCl 2 Is prepared into CaCl with the volume concentration of 0.1-0.2mol/L 2 Preparing a solution, namely preparing diethylenetriamine pentaacetic acid (DTPA) into a DTPA solution with the volume concentration of 0.04-0.06mol/L, preparing water-soluble allyl isothiocyanate into a water-soluble allyl isothiocyanate solution with the volume concentration of 0.8-1.5mol/L, and then preparing the prepared HCL solution with the volume concentration of 0.1-0.2mol/L and CaCl with the volume concentration of 0.1-0.2mol/L 2 The solution, 0.04-0.06mol/L DTPA solution and 0.8-1.5mol/L water-soluble allyl isothiocyanate solution are mixed according to the mass ratio of 3:2:2:1, stirring and uniformly mixing at room temperature to form a mixed solvent after the mixed solvent is fully dissolved, and storing the mixed solvent in a plastic container for later use.
The plant of the invention adopts cruciferae plants, which comprise any one or a combination of a plurality of ciliate desert-grass, ryegrass, indian mustard, sedum alfredii hance, leek, longleaf swertia herb, pokeberry root, baoshan violet, cardamine hupingshanensis, thalassia repens and vetiver grass. The microorganism in the invention comprises any one or a combination of a plurality of polyphosphate, sulfur-containing protein, algae, cyanobacteria, sulfate reducing bacteria and gram positive bacteria, and the metabolism of the microorganism is utilized to enrich carbohydrate substances of heavy metals and absorb and oxidize heavy metal substances in soil, thereby restoring the ecological environment of the soil.
In order to prove the effect of the soil extractant, the inventor of the invention carries out tests on the concentration ratio of each substance of the extractant, prepares different soil extractants by adjusting substances with different concentrations, and carries out extraction tests on heavy metals in soil by adopting the prepared different soil extractants, wherein the four tests are as follows:
the first test: caCl 2 The concentration of the solution, DTPA solution and water-soluble allyl isothiocyanate solution is not changed (0.15 mol/L CaCl) 2 0.05mol/L DTPA and 1.2mol/L water-soluble allyl isothiocyanate) at different HCL solution concentrations, the test results are shown in table 1:
TABLE 1 extraction ratio of mixed solvent of different HCL solution concentrations to heavy metal in soil
HCL concentration (mol/L) in the Mixed solvent Copper (%) Zinc (%) Lead (%) Cadmium (%) Arsenic (%)
0.08 15 8 11 12 15
0.1 25 23 24 38 31
0.15 27 25 26 40 33
0.2 25 27 25 39 34
0.22 14 11 9 10 12
As can be seen from experiments, the heavy metal extraction rate is higher as the concentration (mol/L) of HCL is higher, when the concentration of HCL reaches 0.15mol/L, the effect is best, and then gradually decreases, and when the concentration of HCL exceeds 0.2mol/L, the effect is worse than 0.1mol/L, so the optimal concentration of HCL in the formula is 0.15mol/L.
And (2) test II: different CaCl under the condition that the concentration of the HCL solution, the DTPA solution and the water-soluble allyl isothiocyanate solution is unchanged (0.15 mol/L HCL, 0.05mol/L DTPA and 1.3mol/L water-soluble allyl isothiocyanate) 2 The effect of the solution concentration on the extraction results are shown in Table 2:
TABLE 2 different CaCl 2 Extraction rate of mixed solvent with solution concentration on soil heavy metal
CaCl in mixed solvent 2 Concentration (mol/L) Copper (%) Zinc (%) Lead (%) Cadmium (%) Arsenic (%)
0.09 7 5 13 8 14
0.1 26 27 29 35 42
0.14 28 23 28 38 39
0.2 27 28 32 34 40
0.21 8 4 15 10 15
Experiments II show that the heavy metal extraction rate is higher as the CaCl2 solution is higher, the effect is best when the concentration of the CaCl2 solution reaches 0.14mol/L, and then the concentration gradually begins to decrease, and the effect ratio is worse than 0.1mol/L when the concentration of the CaCl2 solution exceeds 0.2mol/L, so that the optimal concentration of HCL in the formula is 0.14mol/L.
And (3) test III: HCl solution, caCl 2 The solution and the water-soluble allyl isothiocyanate solution are kept at the same concentration (0.14 mol/L HCL, 0.16mol/L CaCl) 2 And 1mol/L water-soluble allyl isothiocyanate), the effect of different DTPA solution concentrations on the extraction effect, the test results of which are shown in table 3:
TABLE 3 extraction ratio of mixed solvent with different DTPA solution concentrations to heavy metals in soil
Figure BDA0003773547680000081
Figure BDA0003773547680000091
It can be seen through the third experiment that, as the extraction rate of the heavy metal of the DTPA solution is higher and higher, the extraction effect of each heavy metal is poorer when the DTPA solution exceeds 0.06 mol/L.
And (4) testing: HCl solution, caCl 2 Solution and DTPA solution of no concentrationUnder the condition of change (0.16 mol/L HCL, 0.15mol/L CaCl 2 And 0.05mol/L DTPA), the effect of different water-soluble allyl isothiocyanate solution concentrations on the extraction effect, and the test results are shown in table 4:
table 4 extraction rate of soil heavy metal by mixed solvent of water-soluble allyl isothiocyanate solutions with different concentrations
Figure BDA0003773547680000092
The third experiment shows that the heavy metal extraction rate is higher along with the increasing of different water-soluble allyl isothiocyanate solutions, and the extraction effect on each heavy metal is poorer when different water-soluble allyl isothiocyanate solutions reach 1.6 mol/L.
As can be seen from the above tests, the concentration of the mixed solvent is preferably 0.1-0.2mol/L of HCL and CaCl 2 0.1-0.2mol/L, 0.04-0.06mol/L DTPA and 0.8-1.5mol/L water-soluble allyl isothiocyanate, and the mixed solvent at the concentration can be close to the state of soil per se and has stronger extraction capability.
The method can effectively remove harmful substances in the soil, has good repairing effect, improves the repairing speed and efficiency of the traditional biological soil repairing technology, has short repairing period, reduces repairing cost, and has wide market application prospect; the repairing method of the present invention is further described below with reference to specific examples;
embodiment 1 provides a method for remediating heavy metal contaminated soil, which comprises the following steps:
(1) Irrigating and diluting the polluted soil by using clear water, reducing the concentration of heavy metals in the soil, and simultaneously adjusting the water content in the soil to 5%;
(2) Pretreatment: adding 0.15mol/L HCL and 0.2mol/L CaCl into the diluted soil 2 Fully mixing 0.04mol/L DTPA and 0.8mol/L water-soluble allyl isothiocyanate mixed solvent, standing for 24 hours, then rinsing with clear water again, and removing residual extractant;
(3) Adding a modifier mixed by lime, an organic fertilizer and an epoxy resin silicon-containing curing agent into the pretreated soil, and stirring the soil and the soil modifier by using excavating equipment;
(4) Adding earthworms into the improved soil, and absorbing heavy metal pollutants in the soil by using the earthworms to reduce the content of the heavy metals in the polluted soil;
(5) Repairing by combining plants and microorganisms: planting ciliate desert grass, ryegrass, indian mustard, southeast sedum and Leersia hexandra Swartz, and jointly repairing the improved soil by utilizing the symbiotic polyphosphate, sulfur-containing protein, algae and cyanobacteria microbial systems of plants and the plants.
Embodiment 2 provides a method for remediating heavy metal contaminated soil, which comprises the following specific steps:
(1) Irrigating and diluting the polluted soil by using clear water, reducing the concentration of heavy metals in the soil, and simultaneously adjusting the water content in the soil to 6%;
(2) Adding 0.2mol/L HCL and 0.15mol/L CaCl into the diluted soil 2 Fully mixing 0.05mol/L DTPA and 1.2mol/L water-soluble allyl isothiocyanate mixed solvent, standing for 30 hours, then rinsing with clean water again, and removing residual extractant;
(3) Adding a modifier combined by an epoxy resin silicon-containing curing agent, phosphate and charcoal into the pretreated soil, and stirring the soil and the soil modifier through excavating equipment;
(4) Earthworms and spiders are added into the improved soil, and the heavy metal content of the polluted soil is reduced by utilizing the absorption of the heavy metal by the animals in the soil;
(5) Repairing by combining plants and microorganisms: planting Leersia hexandra, blumea macroloba, pokeberry, viola baphicacanthus, cardamine hupingshanensis, thymus damascena and vetiver grass, and repairing the improved soil by combining with a microorganism system of symbiotic cyanobacteria, sulfate reducing bacteria and gram positive bacteria of the plants.
The method for restoring the heavy metal contaminated soil provided by the embodiment 3 comprises the following specific steps:
(1) Irrigating and diluting the polluted soil by using clear water, reducing the concentration of heavy metals in the soil, and simultaneously adjusting the water content in the soil to 8%;
(2) Pretreatment: adding 0.1mol/L HCL and 0.1mol/L CaCl into the diluted soil 2 Fully mixing 0.04mol/L DTPA and 0.8mol/L water-soluble allyl isothiocyanate mixed solvent, standing for 20 hours, then rinsing with clear water again, and removing residual extractant;
(3) Adding a modifier mixed by organic fertilizer, epoxy resin silicon-containing curing agent and phosphate into the pretreated soil, and stirring the soil and the soil modifier by excavating equipment;
(4) Earthworms and spiders are added into the improved soil, and the heavy metal content in the polluted soil is reduced by utilizing the absorption of the heavy metal by animals in the soil;
(5) Plant and microorganism combined remediation: planting ciliate desert-grass, ryegrass, indian mustard herb, sedum alfredii hance, leersia hexandra, large-leaf Philippine violet herb, pokeberry root, viola odorata, cardamine hupingshanensis and Thalassia rudata, and jointly repairing the improved soil by utilizing a sulfur-containing protein, algae, cyanobacteria and sulfate reducing bacteria microbial system symbiotic with plants.
The removal rates of heavy metals in soil before and after remediation treatment in the three examples are shown in table 5:
TABLE 5 removal rate of heavy metals after soil remediation in three examples
Mercury Cadmium (Cd) Lead (II) Chromium (III) Arsenic (As) Nickel (II) Manganese oxide
Example 1 96％ 78％ 97％ 86％ 68％ 83％ 83％
Example 2 98％ 73％ 92％ 83％ 73％ 87％ 81％
Example 3 95％ 82％ 95％ 90％ 74％ 85％ 79％
Therefore, the soil remediation technology adopted by the method has high removal effect on mercury, cadmium, lead, chromium, arsenic, nickel, manganese and other heavy metals in the polluted soil, has good soil remediation effect, and can effectively remove harmful substances in the soil.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (6)

1. A soil extractant, which is characterized in that: the soil extractant is HCL solution of 0.1-0.2mol/L and CaCl of 0.1-0.2mol/L 2 The solution, 0.04-0.06mol/L DTPA solution and 0.8-1.5mol/L water-soluble allyl isothiocyanate solution are mixed according to the mass ratio of 2.5-3.5: 1.5-2.5: 1.5-2.5: 0.5-1.5, and stirring and mixing uniformly at room temperature to form a mixed solvent after the components are fully dissolved.
2. The method for repairing the heavy metal contaminated soil by using the soil extraction agent as defined in claim 1 is characterized by comprising the following specific steps:
(1) Diluting the polluted soil: irrigating and diluting the polluted soil by using clear water, and adjusting the water content in the soil to be 5-8%;
(2) Preparing a soil extractant: preparing HCL into HCL solution with volume concentration of 0.1-0.2 mol/L; adding CaCl 2 Is prepared into CaCl with the volume concentration of 0.1-0.2mol/L 2 A solution; preparing DTPA into DTPA solution with volume concentration of 0.04-0.06 mol/L; preparing water-soluble allyl isothiocyanate into a water-soluble allyl isothiocyanate solution with the volume concentration of 0.8-1.5 mol/L; then adding the prepared HCL solution and CaCl 2 The solution, the DTPA solution and the water-soluble allyl isothiocyanate solution are mixed according to the mass ratio of 2.5-3.5: 1.5-2.5: 1.5-2.5: mixing at the ratio of 0.5-1.5, stirring uniformly at room temperature to fully dissolve the components, and storing in a plastic container for later use;
(3) Pretreatment: adding the soil extractant prepared in the step (2) into the soil diluted in the step (1), wherein the addition amount is as follows: adding 20-25mL of soil extractant into every 1g of soil; mixing the soil extractant with the contaminated soil, standing for 20-30h, then rinsing with clean water again to remove the residual soil extractant, and controlling the water content in the soil to be 4-7%;
(4) Adding a modifier into the pretreated soil, and stirring the soil and the modifier by excavating equipment, wherein the modifier comprises one or more of lime, organic fertilizer, epoxy resin silicon-containing curing agent, phosphate and biochar;
(5) Animals are added into the improved soil, and the animals in the soil are used for absorbing heavy metals, so that the content of the heavy metals in the polluted soil is reduced; the animals comprise one or two of earthworm and spider;
(6) Repairing by combining plants and microorganisms: finally, plants are planted in the sudden season, and the improved soil is repaired by combining the plants and the symbiotic microorganisms thereof.
3. The method for remediating heavy metal contaminated soil using a soil extractant as set forth in claim 2, wherein: and (4) adding the soil extractant into the polluted soil in the step (3) for three times, wherein 1/3 of the soil extractant is added each time, and stirring the soil and the soil extractant by using excavating equipment after the soil extractant is added each time so as to uniformly mix the soil and the soil extractant.
4. The method for remediating heavy metal contaminated soil using a soil extractant as recited in claim 2, wherein: and (4) the residual extracting agent removed in the step (3) is cleaned by spraying clean water, the cleaning water liquid is combined with the pollutants extracted from the soil, and the pollutants adsorbed or fixed on the soil particles are desorbed and removed by desorption and dissolution of the cleaning water.
5. The method for remediating heavy metal contaminated soil using a soil extractant as recited in claim 2, wherein: the plant in the step (6) is a cruciferous plant, and comprises one or more of ciliate desert-grass, ryegrass, indian mustard, sedum alfredii hance, leersia hexandra, bidens macrophylla, phytolacca acinosa, viola odorata, cardamine hupingshanensis, thalassilia damascena and vetiver zizanioides.
6. The method for remediating heavy metal contaminated soil using a soil extractant as set forth in claim 2, wherein: in the step (6), the microorganisms comprise any one or a combination of a plurality of polyphosphate, sulfur-containing protein, algae, cyanobacteria, sulfate reducing bacteria and gram positive bacteria, and the metabolism of the microorganisms is utilized to enrich the carbohydrate substances of the heavy metals, absorb and oxidize and reduce the heavy metal substances in the soil, so as to restore the ecological environment of the soil.
CN202210909285.5A 2022-07-29 2022-07-29 Soil extractant and method for repairing heavy metal contaminated soil by using same Pending CN115228918A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080071130A1 (en) * 2004-09-10 2008-03-20 Hideo Tamura Method Of Cleaning Heavy Metals-Containing Soil
CN108059959A (en) * 2017-12-14 2018-05-22 张松 A kind of heavy metal cadmium arable soil renovation agent and its preparation method and application
CN110899323A (en) * 2019-12-27 2020-03-24 宁土建工(苏州)环境修复科技有限公司 Method for restoring farmland heavy metal contaminated soil by combining chemical leaching and phytoremediation
CN112692045A (en) * 2020-11-30 2021-04-23 四川长虹格润环保科技股份有限公司 Leaching process for repairing high-load metal polluted soil
CN112742858A (en) * 2020-12-17 2021-05-04 苏州市相润土壤修复技术研究院有限公司 Method for repairing soil polluted by heavy metal cadmium

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080071130A1 (en) * 2004-09-10 2008-03-20 Hideo Tamura Method Of Cleaning Heavy Metals-Containing Soil
CN108059959A (en) * 2017-12-14 2018-05-22 张松 A kind of heavy metal cadmium arable soil renovation agent and its preparation method and application
CN110899323A (en) * 2019-12-27 2020-03-24 宁土建工(苏州)环境修复科技有限公司 Method for restoring farmland heavy metal contaminated soil by combining chemical leaching and phytoremediation
CN112692045A (en) * 2020-11-30 2021-04-23 四川长虹格润环保科技股份有限公司 Leaching process for repairing high-load metal polluted soil
CN112742858A (en) * 2020-12-17 2021-05-04 苏州市相润土壤修复技术研究院有限公司 Method for repairing soil polluted by heavy metal cadmium

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