An in-situ chemical oxidation remediation system and method for contaminated soil

Abstract

The application discloses an in-situ chemical oxidation remediation system and method for contaminated soil, and belongs to the technical field of contaminated soil remediation. The system comprises a wet screening grading unit, a grading differential leaching unit and a leaching waste liquid recycling dispensing unit. The wet screening grading unit screens the excavated soil into three particle size grades of gravel, sand and powder clay; the grading differential leaching unit adopts different leaching agents and leaching processes for differential treatment of different particle size soils; the leaching waste liquid recycling dispensing unit directly converts the leaching waste liquid into a composite oxidation slurry mother liquor for in-situ chemical oxidation after precipitation and microfiltration treatment, and the composite oxidation slurry mother liquor is injected into unexcavated deep contaminated areas through an injection drilling machine, and secondary oxidation degradation is carried out by using the residual H2O2 in the waste liquid to activate the persulfate to generate sulfate radicals. The system realizes one-time treatment of composite pollution and zero external transportation of leaching waste liquid, and the reagent cost is saved by more than 37% compared with a brand-new fresh reagent scheme.

Description

Technical Field

[0001] This invention belongs to the field of contaminated soil remediation technology, specifically relating to a graded leaching coupled in-situ chemical oxidation remediation system and method suitable for complex contaminated sites where heavy metals and organic pollutants coexist. Background Technology

[0002] With the acceleration of industrialization, a large number of industrial sites have developed serious soil pollution problems. Among these polluted sites, the phenomenon of compound pollution, where heavy metals and organic pollutants coexist, is particularly prominent. For example, heavy metals such as arsenic, cadmium, and lead coexist with organic pollutants such as polycyclic aromatic hydrocarbons and total petroleum hydrocarbons, posing a great challenge to soil remediation.

[0003] Currently, remediation technologies for complex contaminated soils mainly include chemical oxidation and leaching. However, each technology has significant limitations: chemical oxidation is almost ineffective against heavy metal pollutants and can only degrade organic pollutants; while leaching can remove heavy metals and some organic matter simultaneously, its removal rate for large molecular organic pollutants such as polycyclic aromatic hydrocarbons is low, especially for organic pollutants bound to fine soil particles.

[0004] In addition, existing leaching technologies have the following problems: First, the cost of leaching waste liquid disposal is high. Most existing leaching waste liquid needs to be transported to professional institutions for disposal, which not only increases economic costs but also brings a large carbon emission footprint. Second, the graded treatment is insufficient. The occurrence forms of pollutants in coarse particles (gravel, sand) and fine particles (silt, clay) are significantly different. A uniform leaching method not only leads to waste of reagents but also reduces remediation efficiency.

[0005] Therefore, there is an urgent need to develop a composite contaminated soil remediation system and method that can simultaneously and efficiently remove heavy metals and organic pollutants, enable in-situ reuse of leaching wastewater, and reduce remediation costs. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides an in-situ chemical oxidation remediation system and method for contaminated soil. Through a coupled process of "graded treatment + in-situ reuse of waste liquid", it achieves one-time treatment of complex pollution and directly converts the leaching waste liquid into in-situ oxidizing agent mother liquor, achieving the goal of zero waste liquid transportation.

[0007] The technical solution of the present invention is as follows: On one hand, the present invention provides an in-situ chemical oxidation remediation system for contaminated soil, comprising: The wet screening and grading unit is used to screen the excavated contaminated soil into soil particles of multiple particle size grades according to their particle size. The graded and differentiated leaching unit is connected to the wet screening and grading unit, and includes at least two leaching treatment sections. Each leaching treatment section corresponds to a soil particle size class, and each leaching treatment section uses a leaching agent and leaching process corresponding to that particle size class. The leaching waste liquid recycling and dosing unit is connected to the graded differentiated leaching unit. It is used to collect the leaching waste liquid generated by the graded differentiated leaching unit, and after the leaching waste liquid is subjected to sedimentation and microfiltration treatment, an oxidizing agent is added to the filtrate to prepare a composite oxidized slurry. The leaching waste liquid recycling and dosing unit is also connected to an injection drilling machine. The composite oxidation slurry is injected into the unexcavated deep contaminated soil through the injection drilling machine. The oxidizing agent is activated in situ by the activator remaining in the leaching waste liquid, and the generated free radicals oxidize and degrade the organic pollutants.

[0008] A further technical solution is that the wet screening and grading unit includes a vibrating screen and multiple discharge ports connected to the vibrating screen. The multiple discharge ports are respectively for outputting gravel with a particle size greater than 2 mm, sand with a particle size of 0.075 mm to 2 mm, and powder with a particle size less than 0.075 mm.

[0009] A further technical solution is that the graded differentiated rinsing unit includes a sand rinsing section corresponding to the sand grains. The sand rinsing section uses a composite rinsing agent, which includes citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L, with a liquid-to-solid ratio of 3:1 and an oscillation time of 25 to 35 min.

[0010] A further technical solution is that the graded differentiated rinsing unit includes a powder rinsing section corresponding to the powder viscous material. The powder viscous rinsing section uses an enhancing rinsing agent, which includes EDTA at a concentration of 0.2 mol / L, SDS at a concentration of 0.15 mol / L, and H2O2 at a concentration of 0.2 mol / L. It is also supplemented by a flotation enhancement device, which includes a microbubble generator, a stirring mechanism, and a slag scraping mechanism.

[0011] A further technical solution is that the leaching waste liquid reuse and dosing unit includes: A sedimentation tank is used to receive the rinsing waste liquid and perform sedimentation and separation. A microfiltration device, connected to the sedimentation tank, is used for microfiltration treatment of the leaching waste liquid after sedimentation; A reagent dosing device, connected to the microfiltration device, is used to add sodium persulfate and calcium peroxide sustained-release tablets to the microfiltration filtrate to prepare the composite oxidizing slurry.

[0012] In a further technical solution, the amount of sodium persulfate added is 3% to 5% of the mass of the filtrate, and the calcium peroxide slow-release tablets are used to continuously release H2O2 in the composite oxidation slurry to maintain the continuity of the oxidation reaction.

[0013] On the other hand, the present invention provides an in-situ chemical oxidation remediation method for contaminated soil, comprising the following steps: S1. Wet screening and grading: The excavated contaminated soil is screened by a vibrating screen into gravel with a particle size greater than 2mm, sand with a particle size of 0.075mm to 2mm, and silt with a particle size less than 0.075mm. S2. Differentiated rinsing by grade: The gravel is directly backfilled after being washed with high-pressure water jet to remove surface contaminants; the sand is rinsed with a composite rinsing agent; the powder is rinsed with an enhanced rinsing agent supplemented by flotation strengthening. S3. Reuse of leaching waste liquid for chemical preparation: Collect the leaching waste liquid generated in step S2, and after sedimentation separation and microfiltration, add sodium persulfate and calcium peroxide sustained-release tablets to the filtrate to prepare a composite oxidizing slurry. S4. In-situ chemical oxidation: The composite oxidation slurry is injected into the unexcavated deep contaminated area through an injection drilling machine. The residual H2O2 in the leaching waste liquid is used to activate sodium persulfate to generate sulfate free radicals, which are then used to oxidize and degrade organic pollutants in the deep contaminated soil in situ.

[0014] In a further technical solution, in step S2, the rinsing treatment of the sand particles uses a composite rinsing agent that is a mixed solution of citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L, with a liquid-to-solid ratio of 3:1, and reacts for 25 to 35 minutes under shaking conditions.

[0015] In a further technical solution, step S3, the step of reusing the rinsing waste liquid for chemical preparation specifically includes: Sedimentation separation: The rinsing waste liquid is placed in a sedimentation tank and allowed to settle to remove suspended solids; Microfiltration: The supernatant after precipitation is filtered through a microfiltration membrane to remove fine particles; Addition of reagents: Add sodium persulfate at a mass of 3% to 5% of the filtrate after microfiltration, and add calcium peroxide sustained-release tablets. Stir well to obtain the composite oxidizing slurry.

[0016] In a further technical solution, in step S4, the concentration of the residual H2O2 is 0.05 to 0.10 mol / L. The H2O2 activates sodium persulfate in situ in the contaminated soil to generate sulfate free radicals. The sulfate free radicals degrade polycyclic aromatic hydrocarbons and total petroleum hydrocarbon organic pollutants through oxidation, so that the total removal rate of organic pollutants in the contaminated soil reaches more than 85%.

[0017] The beneficial effects of this invention include: (1) High heavy metal removal rate: Through graded differentiated rinsing, the removal rate of heavy metals such as arsenic and cadmium can reach more than 85%; (2) High total organic matter removal rate: Through the coupling process of rinsing and in-situ chemical oxidation, the total removal rate of polycyclic aromatic hydrocarbons can reach more than 85%; (3) High recycling rate of rinsing waste liquid: The recycling rate of rinsing waste liquid can reach more than 80%, achieving zero external transportation of waste liquid; (4) Significantly reduced drug costs: Compared with the all-fresh drug solution, drug costs are reduced by more than 37%. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0019] Figure 1 This is a remediation data diagram of a complexly contaminated site according to an exemplary embodiment 1 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] This invention provides an in-situ chemical oxidation remediation system and method for contaminated soil. The core idea is to classify the contaminated soil according to particle size and then perform differentiated leaching treatment. The waste liquid generated from leaching is directly converted into a mother liquor for in-situ chemical oxidation. This mother liquor is then injected into the unexcavated deep contaminated area through an injection drilling rig for secondary oxidation and degradation, thereby achieving one-time remediation of complex contaminated soil and zero external transportation of waste liquid.

[0022] An in-situ chemical oxidation remediation system for contaminated soil, comprising: The wet screening and grading unit is used to screen the excavated contaminated soil into soil particles of multiple particle size grades according to their particle size. The graded and differentiated leaching unit is connected to the wet screening and grading unit, and includes at least two leaching treatment sections. Each leaching treatment section corresponds to a soil particle size class, and each leaching treatment section uses a leaching agent and leaching process corresponding to that particle size class. The rinsing waste liquid recycling and dosing unit is connected to the graded differentiated rinsing unit. It is used to collect the rinsing waste liquid generated by the graded differentiated rinsing unit, and after the rinsing waste liquid is subjected to sedimentation and microfiltration treatment, an oxidizing agent is added to the filtrate to prepare a composite oxidized slurry. The leaching waste liquid recycling and dosing unit is also connected to an injection drilling rig. The composite oxidation slurry is injected into the unexcavated deep contaminated soil through the injection drilling rig. The activator remaining in the leaching waste liquid is used to activate the oxidizing agent in situ, and the generated free radicals oxidize and degrade the organic pollutants.

[0023] Preferably, the wet screening and grading unit includes a vibrating screen and multiple discharge ports connected to the vibrating screen. The multiple discharge ports are respectively for outputting gravel with a particle size greater than 2 mm, sand with a particle size of 0.075 mm to 2 mm, and powder with a particle size less than 0.075 mm.

[0024] Preferably, the graded differentiated rinsing unit includes a sand rinsing section corresponding to the sand grains. The sand rinsing section uses a composite rinsing agent, which includes citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L. The liquid-to-solid ratio is 3:1, and the shaking time is 25 to 35 min.

[0025] Preferably, the graded differentiated rinsing unit includes a powder rinsing section corresponding to the powder viscous material. The powder viscous material rinsing section uses an enhancing rinsing agent, which includes EDTA at a concentration of 0.2 mol / L, SDS at a concentration of 0.15 mol / L, and H2O2 at a concentration of 0.2 mol / L. It is also supplemented by a flotation enhancement device, which includes a microbubble generator, a stirring mechanism, and a slag scraping mechanism.

[0026] Preferably, the leaching wastewater reuse preparation unit includes: Sedimentation tanks are used to receive rinsing wastewater and perform sedimentation and separation. A microfiltration device, connected to a sedimentation tank, is used to microfilter the leachate after sedimentation. The reagent dosing device is connected to the microfiltration device and is used to add sodium persulfate and calcium peroxide sustained-release tablets to the filtrate after microfiltration to prepare a composite oxidizing slurry.

[0027] Preferably, the amount of sodium persulfate added is 3% to 5% of the filtrate mass, and the calcium peroxide sustained-release tablets are used to continuously release H2O2 in the composite oxidation slurry to maintain the continuity of the oxidation reaction.

[0028] An in-situ chemical oxidation remediation method for contaminated soil, comprising: S1. Wet screening and grading: The excavated contaminated soil is screened by a vibrating screen into gravel with a particle size greater than 2mm, sand with a particle size of 0.075mm to 2mm, and silt with a particle size less than 0.075mm. S2. Differentiated rinsing by grade: gravel is directly backfilled after being washed with high-pressure water jet to remove surface contaminants; sand is rinsed with a composite rinsing agent; powder is rinsed with an enhanced rinsing agent and flotation strengthening. S3. Reuse of leaching waste liquid for chemical preparation: Collect the leaching waste liquid generated in step S2, and after sedimentation separation and microfiltration, add sodium persulfate and calcium peroxide sustained-release tablets to the filtrate to prepare a composite oxidizing slurry. S4. In-situ chemical oxidation: The composite oxidation slurry is injected into the unexcavated deep contaminated area through an injection drilling rig. The residual H2O2 in the leaching waste liquid activates sodium persulfate to generate sulfate free radicals, which are then used to oxidize and degrade organic pollutants in the deep contaminated soil in situ.

[0029] Preferably, in step S2, the rinsing agent used for rinsing the sand particles is a mixed solution of citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L, with a liquid-to-solid ratio of 3:1, and the reaction is carried out under shaking conditions for 25 to 35 minutes.

[0030] Preferably, in step S3, the step of reusing the rinsing waste liquid for chemical preparation specifically includes: Sedimentation separation: The rinsing waste liquid is placed in a sedimentation tank and allowed to settle to remove suspended solids; Microfiltration: The supernatant after precipitation is filtered through a microfiltration membrane to remove fine particles; Addition of reagents: Add sodium persulfate at a mass of 3% to 5% of the filtrate after microfiltration, and add calcium peroxide sustained-release tablets. Stir well to obtain a composite oxidizing slurry.

[0031] Preferably, in step S4, the residual H2O2 concentration is 0.05 to 0.10 mol / L. H2O2 activates sodium persulfate in situ in the contaminated soil to generate sulfate free radicals. The sulfate free radicals degrade polycyclic aromatic hydrocarbons and total petroleum hydrocarbon organic pollutants through oxidation, so that the total removal rate of organic pollutants in the contaminated soil reaches more than 85%.

[0032] Example 1: Remediation of a chemical plant site contaminated with As-Cd-PAHs The soil at a chemical plant site was found to be contaminated with a combination of heavy metals, including arsenic (As) and cadmium (Cd), and polycyclic aromatic hydrocarbons (PAHs). Testing revealed that the As content in the soil was 120 mg / kg, the Cd content was 15 mg / kg, and the total PAH content was 580 mg / kg, all far exceeding the relevant standard limits.

[0033] The repair process using the system described in this invention involves the following specific steps: Step S1: Wet screening and grading The excavated contaminated soil was screened using a vibrating screen to obtain soil particles in three size categories: gravel with a particle size greater than 2 mm (25% by mass), sand with a particle size of 0.075 mm to 2 mm (45% by mass), and silt with a particle size less than 0.075 mm (30% by mass).

[0034] Step S2: Differentiated rinsing based on grade The gravel is washed with high-pressure water jets to remove surface contaminants before being backfilled. The sand particles were leached with a composite leaching agent (0.5 mol / L citric acid + 0.1 mol / L sodium xanthate) at a liquid-to-solid ratio of 3:1 and shaken for 30 min. The powder was treated with a synergistic elution agent (EDTA 0.2mol / L + SDS 0.15mol / L + H2O2 0.2mol / L) and enhanced by flotation.

[0035] The rinsing results are as follows: As removal rate in gravel was 86%, and PAHs removal rate was 86%. The concentration of As in sand particles decreased from 120 mg / kg to 18 mg / kg (removal rate 85%), and the concentration of PAHs decreased from 580 mg / kg to 110 mg / kg (removal rate 81%). As in the powder decreased from 210 mg / kg to 58 mg / kg (removal rate 72%), and PAHs decreased from 890 mg / kg to 260 mg / kg (removal rate 71%).

[0036] Step S3: Reuse of rinsing waste liquid for chemical preparation Collect the waste liquid generated from the washing of sand and powder in step S2 (with a residual H2O2 concentration of about 0.08 mol / L and a pH of about 3.5). After settling in a sedimentation tank to remove suspended solids, filter the liquid through a microfiltration membrane, add sodium persulfate to the filtrate to a concentration of 4% w / w, and add calcium peroxide slow-release tablets to prepare a composite oxidizing slurry.

[0037] Step S4: In-situ chemical oxidation The composite oxidizing slurry prepared in step S3 is injected into the deep contaminated area that has been screened but not yet excavated in step S1 using an injection drilling rig. The residual H2O2 in the waste liquid activates sodium persulfate in situ in the soil to generate sulfate free radicals, which then carry out secondary degradation of PAHs.

[0038] After in-situ oxidation, the residual PAHs in the powder decreased from 260 mg / kg to 68 mg / kg, with a removal rate of 74%, reaching the remediation target value.

[0039] Overall remediation results: Total removal rate of heavy metals (As / Cd) >85%, total removal rate of PAHs (rinsing + oxidation coupling) >85%, rinsing wastewater reuse rate >80%, and chemical cost is 37% lower than that of the all-fresh chemical solution.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description.

[0041] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An in-situ chemical oxidation remediation system for contaminated soil, characterized in that, include: The wet screening and grading unit is used to screen the excavated contaminated soil into soil particles of multiple particle size grades according to their particle size. The graded and differentiated leaching unit is connected to the wet screening and grading unit, and includes at least two leaching treatment sections. Each leaching treatment section corresponds to a soil particle size class, and each leaching treatment section uses a leaching agent and leaching process corresponding to that particle size class. The leaching waste liquid recycling and dosing unit is connected to the graded differentiated leaching unit. It is used to collect the leaching waste liquid generated by the graded differentiated leaching unit, and after the leaching waste liquid is subjected to sedimentation and microfiltration treatment, an oxidizing agent is added to the filtrate to prepare a composite oxidized slurry. The leaching waste liquid recycling and dosing unit is also connected to an injection drilling machine. The composite oxidation slurry is injected into the unexcavated deep contaminated soil through the injection drilling machine. The oxidizing agent is activated in situ by the activator remaining in the leaching waste liquid, and the generated free radicals oxidize and degrade the organic pollutants.

2. The in-situ chemical oxidation remediation system for contaminated soil as described in claim 1, characterized in that, The wet screening and grading unit includes a vibrating screen and multiple discharge ports connected to the vibrating screen. The multiple discharge ports are respectively for outputting gravel with a particle size greater than 2 mm, sand with a particle size of 0.075 mm to 2 mm, and powder with a particle size less than 0.075 mm.

3. The in-situ chemical oxidation remediation system for contaminated soil as described in claim 2, characterized in that, The graded differentiated rinsing unit includes a sand rinsing section corresponding to the sand grains. The sand rinsing section uses a composite rinsing agent, which includes citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L, with a liquid-to-solid ratio of 3:1 and an oscillation time of 25 to 35 min.

4. The in-situ chemical oxidation remediation system for contaminated soil as described in claim 2, characterized in that, The graded differentiated rinsing unit includes a powder rinsing section corresponding to the powder. The powder rinsing section uses an enhancing rinsing agent, which includes EDTA at a concentration of 0.2 mol / L, SDS at a concentration of 0.15 mol / L, and H2O2 at a concentration of 0.2 mol / L. It is also supplemented by a flotation enhancement device, which includes a microbubble generator, a stirring mechanism, and a slag scraping mechanism.

5. The in-situ chemical oxidation remediation system for contaminated soil as described in claim 1, characterized in that, The leaching waste liquid reuse and dosing unit includes: A sedimentation tank is used to receive the rinsing waste liquid and perform sedimentation and separation. A microfiltration device, connected to the sedimentation tank, is used for microfiltration treatment of the leaching waste liquid after sedimentation; A reagent dosing device, connected to the microfiltration device, is used to add sodium persulfate and calcium peroxide sustained-release tablets to the microfiltration filtrate to prepare the composite oxidizing slurry.

6. The in-situ chemical oxidation remediation system for contaminated soil as described in claim 5, characterized in that, The amount of sodium persulfate added is 3% to 5% of the mass of the filtrate, and the calcium peroxide slow-release tablets are used to continuously release H2O2 in the composite oxidation slurry to maintain the continuity of the oxidation reaction.

7. An in-situ chemical oxidation remediation method for contaminated soil, applied to the system as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Wet screening and grading: The excavated contaminated soil is screened by a vibrating screen into gravel with a particle size greater than 2mm, sand with a particle size of 0.075mm to 2mm, and silt with a particle size less than 0.075mm. S2. Differentiated rinsing by grade: The gravel is directly backfilled after being washed with high-pressure water jet to remove surface contaminants; the sand is rinsed with a composite rinsing agent; the powder is rinsed with an enhanced rinsing agent supplemented by flotation strengthening. S3. Reuse of leaching waste liquid for chemical preparation: Collect the leaching waste liquid generated in step S2, and after sedimentation separation and microfiltration, add sodium persulfate and calcium peroxide sustained-release tablets to the filtrate to prepare a composite oxidizing slurry. S4. In-situ chemical oxidation: The composite oxidation slurry is injected into the unexcavated deep contaminated area through an injection drilling machine. The residual H2O2 in the leaching waste liquid is used to activate sodium persulfate to generate sulfate free radicals, which are then used to oxidize and degrade organic pollutants in the deep contaminated soil in situ.

8. The in-situ chemical oxidation remediation method for contaminated soil as described in claim 7, characterized in that, In step S2, the rinsing treatment of the sand particles uses a composite rinsing agent that is a mixed solution of citric acid with a concentration of 0.5 to 1 mol / L and sodium xanthate with a concentration of 0.1 to 0.3 mol / L, with a liquid-to-solid ratio of 3:1, and reacts for 25 to 35 minutes under shaking conditions.

9. The in-situ chemical oxidation remediation method for contaminated soil as described in claim 7, characterized in that, In step S3, the step of reusing the rinsing waste liquid for chemical preparation specifically includes: Sedimentation separation: The rinsing waste liquid is placed in a sedimentation tank and allowed to settle to remove suspended solids; Microfiltration: The supernatant after precipitation is filtered through a microfiltration membrane to remove fine particles; Addition of reagents: Add sodium persulfate at a mass of 3% to 5% of the filtrate after microfiltration, and add calcium peroxide sustained-release tablets. Stir well to obtain the composite oxidizing slurry.

10. The in-situ chemical oxidation remediation method for contaminated soil as described in claim 7, characterized in that, In step S4, the concentration of the residual H2O2 is 0.05 to 0.10 mol / L. The H2O2 activates sodium persulfate in situ in the contaminated soil to generate sulfate free radicals. The sulfate free radicals degrade polycyclic aromatic hydrocarbons and total petroleum hydrocarbon organic pollutants through oxidation, so that the total removal rate of organic pollutants in the contaminated soil reaches more than 85%.

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