Oxidation active zone repairing system and method for organic pollution of underground water

Abstract

The invention provides an oxidation active zone remediation system and method for underground water organic pollution. The remediation system comprises a plurality of injection wells and monitoring wells which are arranged at the downstream of an underground water pollution plume; the injection wells are distributed in rows at equal intervals in the direction perpendicular to the underground water flow field, the adjacent injection wells in the same row are distributed at equal intervals, and the injection wells in the adjacent rows are distributed in a staggered mode. The monitoring wells are arranged at upstream and downstream positions of an oxidation active zone formed by the injection wells; the injection well is of a double-well structure and comprises an inner well and an outer well. The inner well and the outer well are slotted floral tubes, a repairing agent is injected into the inner well, and the space between the inner well and the outer well is filled with a slow-release repairing material; and the outer side of the outer well is provided with a well wall formed by filling quartz sand filter materials, sodium bentonite particles and anti-seepage cement paste from bottom to top. According to the remediation system, through the reasonable structural design and application of the remediation agent and the slow-release remediation material, an oxidation activity reaction zone can be rapidly established, underground water pollution diffusion is efficiently blocked, and rapid and effective remediation of underground water is achieved.

Description

Technical Field

[0001] This invention belongs to the field of groundwater remediation technology, and in particular relates to an oxidative active zone remediation system and method for organic pollution in groundwater. Background Technology

[0002] Existing groundwater remediation technologies often suffer from drawbacks such as long remediation cycles, high costs, and limited effectiveness, making them ineffective in responding to emergency pollution events and complex pollution scenarios. Therefore, there is an urgent need for a new method that can efficiently address groundwater remediation in cases of sudden environmental pollution and heavily polluted sites, rapidly preventing the spread of groundwater contamination and achieving fast and effective remediation of groundwater in such areas. Summary of the Invention

[0003] In view of this, in order to solve the above-mentioned technical problems, the present invention proposes an oxidative active zone remediation system and method for groundwater organic pollution. Through reasonable structural design and the application of efficient remediation agents and slow-release remediation materials, an oxidative active reaction zone can be quickly established, effectively blocking the spread of groundwater pollution and achieving rapid and effective remediation of groundwater.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] This invention provides an oxidative reactive zone remediation system for organic pollution in groundwater, comprising multiple injection wells and monitoring wells located downstream of a groundwater pollution plume; the multiple injection wells are arranged in rows at equal intervals perpendicular to the groundwater flow direction, adjacent injection wells in the same row are equidistant from each other, and the injection wells in adjacent rows are staggered to form an oxidative reactive zone; the multiple monitoring wells are located upstream and downstream of the oxidative reactive zone formed by the multiple injection wells;

[0006] The injection well is a dual-well structure, including an inner well and an outer well, with the bottom of the injection well sealed. Both the inner and outer wells are slotted pipes. The inner well is injected with a remediation agent to reduce the concentration of pollutants and decrease the range of pollution diffusion in an emergency. The space between the inner and outer wells is filled with slow-release remediation material for the adsorption and slow-release oxidation of pollutants. The outer well is surrounded by a well wall composed of quartz sand filter media, sodium bentonite particles, and impermeable cement slurry, filled from bottom to top.

[0007] In some preferred embodiments of the present invention for the remediation system of oxidative active zone for organic pollution in groundwater, the well spacing of the injection wells is 0.5-1.5m.

[0008] In some preferred embodiments of the present invention for the remediation system of oxidative active zone for organic pollution in groundwater, the inner diameter of the inner well is 40 cm, the inner diameter of the outer well is 140 cm, the slotted portion of the inner well and the outer well is located in the aquifer, allowing groundwater to enter the well, and the remaining portion is a solid pipe structure.

[0009] In some preferred embodiments of the present invention for an oxidative active zone remediation system for organic pollution in groundwater, the quartz sand filter media is filled to a height of 0.3-0.8m above the external well slot, the sodium bentonite particles are filled to a height of 0.8-1.2m, and the impermeable cement slurry is prepared by mixing bentonite and cement.

[0010] In some preferred embodiments of the present invention for the remediation system of oxidative active zone for organic pollution in groundwater, the remediation agent is an aqueous solution comprising 10%-35% sodium persulfate, 5%-25% activator, and 5%-30% stabilizer by mass concentration; the slow-release remediation material comprises slow-release potassium persulfate particles and adsorbent material.

[0011] The remediation agent is a suspension with a solid content of 1%–5%, which can be determined according to the actual pollution situation.

[0012] Potassium persulfate sustained-release reagent's main component is potassium persulfate, which has strong oxidizing properties. Its decomposition produces sulfate free radicals (SO4). - It uses active substances such as · to degrade organic pollutants in groundwater. Due to its low solubility in water, it can play a slow-release role.

[0013] In some preferred embodiments of the present invention for the remediation system of oxidative active zone for organic pollution in groundwater, the activator is ferrous sulfide, and the stabilizer is phosphate or EDTA; the potassium persulfate slow-release particles are prepared by mixing potassium persulfate, cement, quartz sand and water in a mass ratio of 1:1:1:1, and the diameter of the potassium persulfate slow-release particles is 20-80 mm; the adsorbent is activated carbon and / or nano-zero valent iron material, the activated carbon particle size is 0.2-0.5 mm, and the nano-zero valent iron material particle size is 10-100 nm.

[0014] Sodium persulfate is relatively stable at room temperature. Through activation by transition metal ions such as iron ions, it can react rapidly with organic pollutants in groundwater, with a fast rate and high efficiency.

[0015] The main purpose of the surfactant is to activate the oxidizing power of potassium persulfate and sodium persulfate;

[0016] Stabilizers are mainly used to improve the stability and durability of suspensions, thereby extending their reaction time in groundwater.

[0017] In some preferred embodiments of the present invention for an oxidative active zone remediation system for organic pollution in groundwater, the inner wall of the outer well is provided with axially spaced tracks at equal intervals along the circumference. The top of each track is provided with a positioning plate extending outward from the top of the area between the inner and outer wells, and the positioning plate has a positioning hole. An annular packing base is provided at the bottom of the area between the inner and outer wells. The outer wall of the packing base is provided with a slider that matches the tracks and can slide along them. The slider has a second positioning plate, which has a second positioning hole and a lifting rope extending to the top of the area between the inner and outer wells. A removable sealing cap is provided at the top of the area between the inner and outer wells. The slow-release remediation material is filled above the packing base.

[0018] The track, positioning plate one, packing base, positioning plate two, and sealing cover are all made of corrosion-resistant and high-strength materials. The packing base is used to support the slow-release repair material. When the slow-release repair material needs to be replaced, open the sealing cover, pull the lifting rope upwards, and the packing base slides upwards along the track, causing the slow-release repair material to move upwards as a whole. The slow-release repair material is pushed out from the area between the inner and outer wells until positioning plate two extends and corresponds to positioning plate one. Positioning hole two and positioning hole two are concentric. Insert positioning pins into positioning holes one and two to fix the position of the packing base. After cleaning and maintaining the packing base, remove the positioning pins, pull the lifting rope, and slowly lower the packing base downwards while filling it with slow-release repair material until the packing base falls to the bottom of the area between the inner and outer wells and is filled with the required amount of slow-release repair material. Cover with the sealing cover to complete the replacement of the slow-release repair material.

[0019] In some preferred embodiments of the present invention for an oxidative active zone remediation system for organic pollution in groundwater, a removable grid compartment with an annular cross-section is provided in the area between the inner well and the outer well, and the grid compartment is filled with the slow-release remediation material; a removable sealing cap is provided on the top of the area between the inner well and the outer well.

[0020] The mesh chamber is made of a corrosion-resistant material with a certain degree of toughness and strength. The gaps in the mesh chamber are smaller than the diameter of the slow-release repair material. The mesh chamber is used to hold the slow-release repair material. When the slow-release repair material needs to be replaced, open the sealing cap, take out the mesh chamber along with the slow-release repair material, and after replacing the slow-release repair material in the mesh chamber, slowly place the mesh chamber into the area between the inner and outer wells, and close the sealing cap to complete the replacement of the slow-release repair material.

[0021] Another aspect of the present invention provides a method for remediating the oxidative active zone of organic pollution in groundwater, comprising the following steps:

[0022] S1. Conduct an investigation of the contaminated site to identify the distribution of pollution sources, the depth and extent of pollution, and determine the types and concentrations of pollutants.

[0023] S2. Multiple injection wells are installed downstream of the groundwater pollution plume, arranged in rows at equal intervals perpendicular to the groundwater flow field. Simultaneously, multiple monitoring wells are installed upstream and downstream of the oxidation active zone formed by the multiple injection wells. The injection wells are of a dual-well structure, including an inner well and an outer well, with the bottom sealed. Both the inner and outer wells are slotted pipes. The outer well is fitted with a well wall composed of quartz sand filter material, sodium bentonite particles, and impermeable cement slurry, filled from bottom to top.

[0024] S3. Fill the area between the inner and outer wells with slow-release remediation material, and slowly inject the prepared remediation agent into the inner well to form an oxidation-active reaction zone, ensuring uniform and efficient blocking of groundwater diffusion throughout the contaminated area; the slow-release remediation material includes potassium persulfate slow-release particles and adsorbent material; the remediation agent is an aqueous solution, including sodium persulfate with a mass concentration of 10%-35%, activator 5%-25%, and stabilizer 5%-30%;

[0025] S4. Regularly monitor groundwater quality, observe changes in pollutant concentrations, and adjust the dosage and frequency of remediation materials and agents based on monitoring results until the remediation target is achieved.

[0026] In some preferred embodiments of the present invention for the remediation of the oxidative active zone of organic pollution in groundwater, in step S2, the well spacing of the injection wells is 0.5-1.5m; the inner diameter of the inner well is 40cm, the inner diameter of the outer well is 140cm, the slotted portions of the inner and outer wells are located in the aquifer, and the remaining portions are solid pipe structures; quartz sand filter material is filled to a height of 0.3-0.8m above the slotted portion of the outer well, the filling height of sodium bentonite particles is 0.8-1.2m, and the impermeable cement slurry is prepared by mixing bentonite and cement.

[0027] In some preferred embodiments of the present invention for the remediation of the oxidative active zone of organic pollution in groundwater, in step S3, the potassium persulfate slow-release particles are prepared by mixing potassium persulfate, cement, quartz sand and water in a mass ratio of 1:1:1:1, and the diameter of the potassium persulfate slow-release particles is 20-80 mm; the adsorbent is activated carbon and / or nano-zero ferrous material, the activated carbon particle size is 0.2-0.5 mm, and the nano-zero ferrous material particle size is 10-100 nm; the activator is ferrous sulfide, and the stabilizer is phosphate or EDTA.

[0028] Compared with existing technologies, the oxidative active zone remediation system and method for organic pollution in groundwater described in this invention have the following advantages:

[0029] (1) The oxidation active zone remediation system and method described in this invention, through reasonable structural design and the application of efficient remediation agents and slow-release remediation materials, can quickly establish an oxidation active reaction zone. The remediation agent is injected into the well, and the groundwater pollutants diffuse to the oxidation active reaction zone with the natural flow of groundwater. The remediation agent quickly and accurately reduces the concentration of pollutants exceeding the standard and slows down ecological damage. The slow-release remediation material efficiently adsorbs and fixes pollutants, and the slow-release effect can release potassium persulfate in a long-term and stable manner, achieving a long-term operating mechanism. Ultimately, it can effectively block the spread of groundwater pollution and achieve the purpose of rapid and effective remediation of groundwater.

[0030] (2) The remediation agents and slow-release remediation materials in the oxidative active zone remediation system and method of the present invention are simple to prepare and easy to use, and can quickly block the spread of groundwater pollution; they couple multiple remediation technologies such as chemical reduction and physical adsorption, and have a significant remediation effect on groundwater polluted by organic substances such as chlorinated hydrocarbons and benzene series compounds; they are highly adaptable, and the layout of injection wells and the amount of remediation agents and slow-release remediation materials can be adjusted according to the actual pollution situation; all selected materials meet environmental protection requirements, and no secondary pollution is generated during the remediation process;

[0031] (3) In the oxidation active zone repair system of the present invention, after the slow-release repair material is deactivated, it can be flexibly replaced by the set track, positioning plate one, filler base, positioning plate two, pull rope or grid compartment, which makes it more adaptable. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the layout of the oxidative active zone remediation system for organic pollution in groundwater as described in Embodiment 1 of the present invention;

[0033] Figure 2 This is a partial distribution diagram of the injection wells described in Embodiment 1 of the present invention;

[0034] Figure 3 This is a schematic diagram of the injection well structure described in Embodiment 1 of the present invention;

[0035] Figure 4 This is a partial structural diagram of the injection well described in Embodiment 2 of the present invention;

[0036] Figure 5 This is a top view of the internal structure of the injection well described in Embodiment 2 of the present invention;

[0037] Figure 6 This is a schematic diagram of the injection well structure described in Embodiment 3 of the present invention.

[0038] Figure 7 This diagram illustrates the pollution removal rate after treating chlorinated hydrocarbon-contaminated groundwater using the oxidative active zone remediation method for organic pollution in groundwater as described in this invention.

[0039] Figure Labels

[0040] 1-Injection well, 2-Monitoring well, 3-Inner well, 4-Outer well, 5-Slow-release repair material, 6-Quartz sand filter media, 7-Sodium bentonite particles, 8-Imperile cement slurry, 9-Well wall, 10-Railway, 11-Positioning plate one, 12-Positioning hole one, 13-Filling base, 14-Slider, 15-Positioning plate two, 16-Positioning hole two, 17-Lifting rope, 18-Sealing cap, 19-Grid compartment. Detailed Implementation

[0041] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0042] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0043] Example 1

[0044] like Figures 1 to 3 As shown, an oxidative reactive zone remediation system for groundwater organic pollution includes multiple injection wells 1 and monitoring wells 2 located downstream of the groundwater pollution plume; the multiple injection wells 1 are arranged in rows at equal intervals perpendicular to the groundwater flow field direction, with adjacent injection wells 1 in the same row being equidistant from each other, and the well spacing between injection wells 1 is 0.5-1.5m; the injection wells 1 in adjacent rows are staggered to form an oxidative reactive zone; the multiple monitoring wells 2 are located upstream and downstream of the oxidative reactive zone formed by the multiple injection wells 1.

[0045] Injection well 1 is a dual-well structure, including inner well 3 and outer well 4. The bottom of injection well 1 is sealed. Both inner well 3 and outer well 4 are slotted pipes. The inner diameter of inner well 3 is 40cm and the inner diameter of outer well 4 is 140cm. The slotted parts of inner well 3 and outer well 4 are located in the aquifer, and the rest are solid pipe structures.

[0046] A repair agent is injected into inner well 3. The repair agent is an aqueous solution containing 25% sodium persulfate, 15% ferrous sulfide, and 20% phosphate. A slow-release repair material 5 is filled between inner well 3 and outer well 4. Slow-release repair material 5 includes potassium persulfate slow-release particles and adsorbent material. The potassium persulfate slow-release particles are prepared by mixing potassium persulfate, cement, quartz sand, and water in a mass ratio of 1:1:1:1, and the diameter of the potassium persulfate slow-release particles is 20-80 mm. The adsorbent material consists of activated carbon and nano-zero-valent iron material. The activated carbon particle size is 0.2-0.5 mm, and the nano-zero-valent iron material particle size is 10-100 nm.

[0047] The outer side of the outer well 4 is provided with a well wall 9 consisting of quartz sand filter material 6, sodium bentonite particles 7, and anti-seepage cement slurry 8, which are filled from bottom to top. The quartz sand filter material 6 is filled to 0.5m above the cut part of the outer well 4, the sodium bentonite particles 7 are filled to a height of 1m, and the anti-seepage cement slurry 8 is prepared by mixing bentonite and cement.

[0048] Example 2

[0049] like Figure 4 and 5 As shown, based on Embodiment 1, the difference from Embodiment 1 is that, along the circumferential direction, there are axially spaced tracks 10 on the inner wall of the outer well 4. The top of the track 11 is provided with a positioning plate 11 extending outward from the top of the area between the inner well 3 and the outer well 4. The positioning plate 11 is provided with a positioning hole 12. An annular packing base 13 is provided at the bottom of the area between the inner well 3 and the outer well 4. The outer wall of the packing base 13 is provided with a slider 14 that matches the track 10 and can slide along the track. The slider 14 is provided with a positioning plate 15. The positioning plate 15 is provided with a positioning hole 16 and a lifting rope 17 that can extend to the top of the area between the inner well 3 and the outer well 4. A removable sealing cap 18 is provided at the top of the area between the inner well 3 and the outer well 4. The slow-release repair material 5 is filled above the packing base 13.

[0050] Example 3

[0051] like Figure 6 As shown, based on Embodiment 1, the difference from Embodiment 1 is that a removable grid compartment 19 with an annular cross-section is provided in the area between the inner well 3 and the outer well 4, and the grid compartment 19 is filled with slow-release repair material 5; a removable sealing cap 18 is provided on the top of the area between the inner well 3 and the outer well 4.

[0052] Example 4

[0053] A site contaminated with halogenated hydrocarbons experienced a sudden environmental incident, resulting in high concentrations of chlorinated hydrocarbon pollutants in the groundwater, primarily including vinyl chloride and 1,2-dichloroethylene. These pollutants are not only difficult to degrade naturally but also pose potential risks of carcinogenicity, teratogenicity, and mutagenicity. To address this issue, the oxidative remediation method for groundwater organic pollution described in this invention is employed, comprising the following steps:

[0054] S1. Conduct an investigation of the contaminated site to identify the distribution of pollution sources, the depth and extent of pollution, and determine the types and concentrations of pollutants.

[0055] S2. Multiple injection wells 1 (injection well structure described in Example 1) are arranged in rows at equal intervals perpendicular to the direction of the groundwater flow field downstream of the groundwater pollution plume. At the same time, multiple monitoring wells 2 are set up upstream and downstream of the oxidation active zone formed by the multiple injection wells 1.

[0056] S3. Fill the area between the inner well 3 and the outer well 4 with the slow-release repair material 5, and slowly inject the prepared repair agent into the inner well 3 to form an oxidation active reaction zone; the slow-release repair material 5 and the repair agent are the slow-release repair material 5 and the repair agent described in Example 1;

[0057] S4. Regularly monitor groundwater quality, observe changes in pollutant concentrations, and adjust the dosage and injection frequency of remediation agents based on monitoring results;

[0058] S5. After a period of remediation, groundwater samples were collected again for water quality analysis to assess the remediation effect. The results showed that the concentration of chlorinated hydrocarbon pollutants was significantly reduced, achieving the remediation target;

[0059] S6. Continue to monitor groundwater over the long term to ensure the stability and durability of the remediation effect.

[0060] After about three months of repair, such as Figure 7 As shown, the concentration of vinyl chloride in the area decreased from a maximum of 4360 μg / L to <1.5 μg / L, and the concentration of 1,2-dichloroethylene decreased from a maximum of 8420 μg / L to <1.2 μg / L, with removal rates of 99.96% and 99.98% respectively, both lower than the Class III standard limit of the "Groundwater Quality Standard" (GB / T14848-2017).

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An oxidative active zone remediation system for organic pollution in groundwater, characterized in that: It includes multiple injection wells and monitoring wells located downstream of the groundwater pollution plume; the multiple injection wells are arranged in rows at equal intervals perpendicular to the groundwater flow field direction, with adjacent injection wells in the same row being equidistant from each other, and the injection wells in adjacent rows being staggered; the multiple monitoring wells are located upstream and downstream of the oxidation activity zone formed by the multiple injection wells. The injection well is a dual-well structure, including an inner well and an outer well, with the bottom of the injection well sealed. Both the inner well and the outer well are slotted pipes. The inner well is injected with a repair agent, and the space between the inner well and the outer well is filled with slow-release repair material. The outer side of the outer well is equipped with a well wall composed of quartz sand filter material, sodium bentonite particles, and impermeable cement slurry, filled from bottom to top.

2. The oxidative active zone remediation system for groundwater organic pollution according to claim 1, characterized in that: The spacing between the injection wells is 0.5-1.5m.

3. The oxidative active zone remediation system for organic pollution in groundwater according to claim 1, characterized in that: The inner diameter of the inner well is 40cm, and the inner diameter of the outer well is 140cm. The slotted portions of the inner and outer wells are located in the aquifer, while the remaining portions are solid pipe structures.

4. The oxidative active zone remediation system for groundwater organic pollution according to claim 1, characterized in that: The quartz sand filter material is filled to a height of 0.3-0.8m above the external well slot, the sodium bentonite particles are filled to a height of 0.8-1.2m, and the impermeable cement slurry is prepared by mixing bentonite and cement.

5. The oxidative active zone remediation system for groundwater organic pollution according to claim 1, characterized in that: The repair agent is an aqueous solution comprising sodium persulfate at a mass concentration of 10%-35%, an activator at a mass concentration of 5%-25%, and a stabilizer at a mass concentration of 5%-30%; the slow-release repair material comprises potassium persulfate slow-release particles and an adsorbent.

6. The oxidative active zone remediation system for groundwater organic pollution according to claim 5, characterized in that: The activator is ferrous sulfide, and the stabilizer is phosphate or EDTA; the potassium persulfate slow-release particles are prepared by mixing potassium persulfate, cement, quartz sand and water in a mass ratio of 1:1:1:1, and the diameter of the potassium persulfate slow-release particles is 20-80 mm; the adsorbent is activated carbon and / or nano-zero-valent iron material, the activated carbon particle size is 0.2-0.5 mm, and the nano-zero-valent iron material particle size is 10-100 nm.

7. The oxidative active zone remediation system for organic pollution in groundwater according to any one of claims 1 to 6, characterized in that: The inner wall of the outer well is provided with axially spaced tracks at equal intervals along the circumference. The top of the tracks is provided with a positioning plate extending outward from the top of the area between the inner and outer wells. The positioning plate is provided with a positioning hole. The bottom of the area between the inner and outer wells is provided with an annular packing base. The outer wall of the packing base is provided with a slider that matches the tracks and can slide along the tracks. The slider is provided with a positioning plate, which is provided with a positioning hole and a lifting rope that can extend to the top of the area between the inner and outer wells. The top of the area between the inner and outer wells is provided with a removable sealing cap. The slow-release repair material is filled on top of the packing base.

8. The oxidative active zone remediation system for organic pollution in groundwater according to any one of claims 1 to 6, characterized in that: The area between the inner well and the outer well is provided with a removable grid compartment with an annular cross-section, and the grid compartment is filled with the slow-release repair material; the top of the area between the inner well and the outer well is provided with a removable sealing cap.

9. A method for remediating the oxidative active zone of organic pollution in groundwater, characterized in that, Includes the following steps: S1. Conduct an investigation of the contaminated site to identify the distribution of pollution sources, the depth and extent of pollution, and determine the types and concentrations of pollutants. S2. Multiple injection wells are installed downstream of the groundwater pollution plume, arranged in rows at equal intervals perpendicular to the groundwater flow field. Simultaneously, multiple monitoring wells are installed upstream and downstream of the oxidation active zone formed by the multiple injection wells. The injection wells are of a dual-well structure, including an inner well and an outer well, with the bottom sealed. Both the inner and outer wells are slotted pipes. The outer well is fitted with a well wall composed of quartz sand filter material, sodium bentonite particles, and impermeable cement slurry, filled from bottom to top. S3. Fill the area between the inner and outer wells with the slow-release remediation material; slowly inject the prepared remediation agent into the inner well to form an oxidation-active reaction zone; the slow-release remediation material includes potassium persulfate slow-release particles and adsorbent material; the remediation agent is an aqueous solution containing 10%-35% sodium persulfate, 5%-25% activator and 5%-30% stabilizer. S4. Regularly monitor groundwater quality, observe changes in pollutant concentrations, and adjust the dosage and frequency of remediation materials and agents based on monitoring results until the remediation target is achieved.

10. The method for remediation of the oxidative active zone of organic pollution in groundwater according to claim 9, characterized in that: In S2, the spacing between injection wells is 0.5-1.5m; the inner diameter of the inner well is 40cm, and the inner diameter of the outer well is 140cm. The slotted portions of the inner and outer wells are located in the aquifer, while the remaining portions are solid pipe structures. Quartz sand filter material is filled to a height of 0.3-0.8m above the slotted portion of the outer well, and the filling height of sodium bentonite particles is 0.8-1.2m. The impermeable cement slurry is prepared by mixing bentonite and cement. In step S3, the potassium persulfate slow-release particles are prepared by mixing potassium persulfate, cement, quartz sand and water in a mass ratio of 1:1:1:1, and the diameter of the potassium persulfate slow-release particles is 20-80 mm; the adsorbent is activated carbon and / or nano-zero ferrous material, the activated carbon particle size is 0.2-0.5 mm, and the nano-zero ferrous material particle size is 10-100 nm; the activator is ferrous sulfide, and the stabilizer is phosphate or EDTA.

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