Polluted site vertical barrier management and control structure and method based on combination of electrophoresis and microorganisms

Abstract

The invention discloses a vertical blocking management and control structure and method for a contaminated site through combination of electrophoresis and microorganisms, and relates to the technical field of soil and underground water remediation management and control. An anti-oxidation graphite electrode is inserted into the boundary of a to-be-managed and controlled area of a polluted site to serve as an anode, a microbial bacterial solution and a cementing solution are injected at the same time, an open-screen steel pipe parallel to the anti-oxidation graphite electrode in a staggered mode is inserted into the managed and controlled area to serve as a cathode, and the adjacent anode and cathode are connected with a direct-current power source through a cable to form a plurality of electrode pairs. Under the action of electrophoresis, clay particles with negative charges and other colloidal particles in soil around the boundary of the site move towards the anode, and along with point cementation among soil particles at the anode and continuous deposition of calcium carbonate under the induction of microorganisms, a vertical barrier wall is finally formed. Colloidal particles in the soil are promoted to be cemented through electrophoresis and microorganisms to form a vertical barrier for risk management and control of a polluted site, and the method has the remarkable advantages of being low in building material dependency degree, small in construction disturbance, easy to maintain in the later period and the like.

Description

Technical Field

[0001] The present invention relates to a vertical barrier control structure and method for a contaminated site using electrophoresis combined with microorganisms, and belongs to the technical field of soil and groundwater remediation and control. Background Art

[0002] Vertical barrier technology is one of the important and effective measures for risk control of contaminated sites. It seals pollutants in a specific area by establishing physical barriers, or changes the direction of groundwater flow to avoid impact on surrounding sensitive targets.

[0003] However, current underground vertical barrier walls, typically slurry walls, grouting walls, sheet pile walls, mixing pile walls, and geomembrane walls, suffer from drawbacks such as high reliance on building materials and difficulty maintaining them after damage, resulting in poor long-term effectiveness. Furthermore, construction methods such as slurry walls and geomembrane walls often involve site excavation and backfilling, while sheet pile walls require dynamic compaction. These vertical barrier wall construction methods significantly disrupt the site, making them difficult to apply to risk management in production areas.

[0004] Inserting electrodes into contaminated soil and groundwater areas and applying direct current to them creates an electrokinetic effect, a promising remediation technology. However, previous applications of electrokinetic remediation have primarily focused on contaminants being concentrated in the electrode area through electrodialysis and electromigration, followed by removal through other physical and chemical techniques, while ignoring electrophoresis. Electrophoresis involves the movement of charged colloidal particles in the soil, including fine soil particles, humus, and microbial cells, from the cathode to the anode under the influence of a direct current field. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a vertical barrier control structure and method for contaminated sites by electrophoresis combined with microorganisms. Electrophoresis combined with microorganisms promotes the aggregation and cementation of clay particles in the soil inside the site, and microbial-induced mineralization forms an underground vertical barrier for risk control of contaminated sites. It has the significant advantages of low dependence on building materials, small construction disturbance, and easy maintenance in the later stage.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions: On the one hand, the present invention provides a vertical barrier control structure for contaminated sites using electrophoresis combined with microorganisms, comprising an antioxidant graphite electrode and an open-screen steel pipe, wherein the antioxidant graphite electrode is inserted at the boundary of the area to be vertically isolated and controlled, and the open-screen steel pipe is staggered and inserted in the area to be vertically isolated and controlled parallel to the antioxidant graphite electrode, and microbial liquid and cementing liquid are injected into the antioxidant graphite electrode; The oxidation-resistant graphite electrode serves as an anode, the open-screen steel pipe serves as a cathode, and adjacent anodes and cathodes are connected to a DC power supply via cables to form a plurality of electrode pairs.

[0007] Furthermore, the antioxidant graphite electrode includes a plurality of graphite bodies arranged in sequence from top to bottom, an insulating rubber pad is provided between adjacent graphite bodies, the surface of the graphite body is coated with an antioxidant, and a cable connected to a DC power supply is provided in the middle, and an injection hole is opened on the graphite body, and the injection hole is used to inject microbial liquid and binder liquid.

[0008] Furthermore, a control switch is provided on the cable connecting the graphite body and the DC power supply, and the control switch is used to control the on and off of the graphite body at different depths and the DC power supply.

[0009] Furthermore, the diameter of the graphite body ranges from 20 to 30 mm, and the length ranges from 80 to 100 cm, the diameter of the sieve steel pipe ranges from 20 to 40 mm, and the length of the sieve steel pipe is the same as that of the oxidation-resistant graphite electrode.

[0010] Furthermore, the intervals between adjacent open-screen steel pipes, adjacent anti-oxidation graphite electrodes, and between the open-screen steel pipes and the anti-oxidation graphite electrodes are all 1 to 1.5 m, and the open-screen steel pipes and the anti-oxidation graphite electrodes are arranged in parallel and staggered manner.

[0011] On the other hand, the present invention also provides a method for vertically isolating and controlling a contaminated site by electrophoresis combined with microorganisms, which is implemented by the vertically isolating and controlling structure for a contaminated site by electrophoresis combined with microorganisms as described above, comprising: Determine the boundaries of the area to be vertically isolated and controlled; Multiple oxidation-resistant graphite electrodes are evenly inserted at the boundaries of the area to be vertically isolated and controlled; Staggered screen steel pipes are inserted in the vertical isolation control area parallel to the oxidation-resistant graphite electrode; Injecting microbial liquid and cementing liquid through the injection hole of the antioxidant graphite electrode; The oxidation-resistant graphite electrode is used as the anode, the open screen steel pipe is used as the cathode, and the adjacent anodes and cathodes are connected to the DC power supply through cables to form multiple pairs of electrodes; Real-time groundwater pH monitoring of the vertical barrier control area and permeability coefficient monitoring of the soil boundary of each antioxidant graphite electrode area; When the pH value of groundwater is lower than 5 or higher than 9, the contaminated groundwater is extracted by electroosmosis into the open-screen steel pipe; When the permeability coefficient of the soil at the set depth in the vertical barrier control area reaches the set threshold, the connection between the graphite body at that depth and the DC power supply is disconnected by controlling the switch; When the permeability coefficient of the soil at all set depths in the vertical barrier control area reaches the set threshold, the power is turned off, the cables are removed, the anti-oxidation graphite electrodes and the screened steel pipes are unplugged, and the remaining holes are sealed.

[0012] Furthermore, it also includes adding acid-base regulating liquid into the open screen steel pipe to maintain the environmental pH value of the area to be vertically isolated and controlled to be neutral, and the acid-base regulating liquid is a diluted solution of hydrochloric acid and sodium hydroxide.

[0013] Furthermore, the sealing operation includes: The in-situ soil and sodium-modified calcium-based bentonite were mixed in a mass ratio of 3:1 to obtain filling soil material; Fill the holes left after the electrodes are pulled out with filling soil in layers, and compact them layer by layer until the holes are sealed.

[0014] Furthermore, the microbial culture liquid is any one of the microbial culture liquids capable of producing urease; And / or, the binder fluid is a mixed aqueous solution of urea and calcium chloride, wherein the concentrations of urea and calcium chloride are both 1-2 mol / L.

[0015] Furthermore, the insertion depth of the screening steel pipe is the design depth of the vertical barrier wall, and the screening steel pipe is screened from 0.5m below the ground to the bottom of the area to be vertically blocked and controlled.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention inserts antioxidant graphite electrodes as anodes at regular intervals at the boundary of the vertical barrier control area, and inserts open-screen steel pipes as cathodes at regular intervals at a certain distance from the boundary and parallel to the anode in the area to be controlled, and injects urease-producing microbial liquid and cementing liquid at the anode; a DC power supply is connected, and negatively charged clay particles and other colloidal particles in the soil around the site boundary move toward the anode under the action of electrophoresis; with the point-to-point cementation between soil particles at the anode and the continuous deposition of calcium carbonate induced by microorganisms, the soil strength continues to increase, and a vertical barrier wall is eventually formed; at the same time, positively charged pollutants will flow toward the cathode along with pore water molecules under the action of electroosmosis, and the pollutants will be extracted and processed through the open-screen steel pipe; and during the construction process, acid-base regulating liquid can be injected to effectively avoid the occurrence of acidic zones caused by long-term electrolysis reactions; The present invention utilizes a method combining electrophoresis with microorganisms, utilizing point bonding between soil particles and continuous deposition of calcium carbonate induced by microorganisms, resulting in a more uniform wall-forming effect. By regulating the layering of graphite anodes, the uniformity of the vertical barrier wall can be improved and the power supply can be cut off in time, thereby reducing energy loss. During the construction process, no large-scale excavation is required, the dependence on building materials is low, and the construction disturbance to the site is small, making it more suitable for risk management and control of production enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a side structural diagram of a vertical barrier control structure for a contaminated site using electrophoresis combined with microorganisms in one embodiment of the present invention; Figure 2 This is a schematic top view of a vertical barrier control structure for a contaminated site using electrophoresis combined with microorganisms in one embodiment of the present invention; Figure 3 for Figure 1 Schematic diagram of the AA surface structure; Figure 4 for Figure 1 Schematic diagram of the BB surface structure; In the figure: 1- open screen steel pipe, 2- anti-oxidation graphite electrode, 3- graphite body, 4- insulating rubber pad, 5- cable, 6- DC power supply, 7- control switch. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Example 1

[0019] like Figure 1 As shown, an embodiment of the present invention provides a vertical barrier control structure for contaminated sites using electrophoresis combined with microorganisms, including an antioxidant graphite electrode 2 and an open-screen steel pipe 1.

[0020] The antioxidant graphite electrodes 2 are evenly inserted at the boundaries of the area to be vertically isolated and controlled. In this embodiment, each antioxidant graphite electrode 2 is spaced 1 to 1.5 meters apart. The antioxidant graphite electrode 2 is composed of multiple graphite bodies 3. The diameter of a single graphite body 3 is 20 to 30 mm and the length is 80 to 100 cm. Adjacent graphite bodies 3 are isolated by insulating rubber pads 4, and antioxidants are coated on the surface of the graphite bodies 3. Figure 3 A cable 5 connected to a DC power supply 6 is provided in the middle of the graphite body 3 , and the cable 5 is used to connect to the DC power supply 6 .

[0021] The graphite body 3 is also provided with injection holes with a diameter of about 3 to 5 mm and arranged vertically at intervals of about 20 cm. Microbial liquid and cementing liquid are injected through the injection holes to diffuse into the soil around the anode, thereby utilizing microorganisms to induce mineralization, promote soil particle cementation, and reduce the soil permeability coefficient.

[0022] In some embodiments, as Figure 4 As shown, the cables 5 connecting the graphite body 3 and the DC power supply 6 are each provided with a control switch 7 , and the on / off of the corresponding graphite body 3 and the DC power supply 6 can be controlled by opening and closing the control switch 7 .

[0023] The open-screen steel pipes 1 are inserted within the control area to be vertically isolated, 1 to 1.5 meters from the boundary, and parallel to the anti-oxidation graphite electrodes 2. Adjacent open-screen steel pipes 1 are also spaced 1 to 1.5 meters apart, and the open-screen steel pipes 1 are arranged parallel to the anti-oxidation graphite electrodes 2, staggered. In this embodiment, the diameter of the open-screen steel pipes 1 is 20 to 40 mm, and the insertion depth is the designed depth of the vertical barrier wall. The open-screen steel pipes 1 are inserted from 0.5 meters below the ground to the bottom of the control area to be vertically isolated.

[0024] The oxidation-resistant graphite electrode 2 is used as the anode and the screened steel pipe 1 is used as the cathode. Adjacent oxidation-resistant graphite electrodes 2 and screened steel pipes 1 are connected in series via cables 5 and a DC power supply 6 to form a plurality of electrode pairs. In particular, graphite bodies 3 of different depths in the same oxidation-resistant graphite electrode 2 are connected in parallel. Figure 2 and Figure 4 shown.

[0025] The working principle of this embodiment is: After the electrophoresis-combined microbial vertical barrier control structure for contaminated sites is connected to a DC power supply 6, the negatively charged clay particles and other colloidal particles in the soil around the boundary of the vertical barrier control area migrate toward the anode under the action of electrophoresis. As the soil particles at the anode bond and calcium carbonate induced by microorganisms continue to deposit, the soil strength continues to increase, eventually forming a vertical barrier wall with a more uniform wall effect. At the same time, the positively charged pollutants flow toward the cathode along with the pore water molecules under the action of electroosmosis, and are extracted and processed through the open-screen steel pipe 1. Example 2

[0026] Based on Example 1, this example provides a method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms, which specifically includes the following steps: Clean the surface and determine the boundaries of the area to be vertically isolated and controlled.

[0027] A plurality of anti-oxidation graphite electrodes 2 are evenly inserted at intervals of 1 to 1.5 m at the boundary of the area to be vertically isolated and controlled.

[0028] In the area to be controlled, a screened steel pipe 1 is inserted at a certain distance from the boundary and parallel to the anode at intervals of 1 to 1.5 meters. It should be noted that the screened steel pipe 1 and the antioxidant graphite electrode 2 are arranged in parallel and staggered.

[0029] Microbial liquid and binder liquid are injected into the injection hole of the antioxidant graphite electrode 2. The microbial liquid is any one of the microbial liquids capable of producing urease, such as Bacillus pasteurianus and Bacillus cereus. The binder liquid is a mixture of urea and calcium chloride.

[0030] In this embodiment, the microbial liquid adopts Bacillus cereus (Bacillus cereus, General Microbiology Center of China Culture Collection Administration, CGMCC No. 30815, deposited on May 30, 2024), and the concentrations of urea and calcium chloride in the binder liquid are both 1-2 mol / L.

[0031] The oxidation-resistant graphite electrode 2 is used as the anode, the screened steel pipe 1 is used as the cathode, and the adjacent anodes and cathodes are connected to the DC power supply 6 through the cable 5 to form a plurality of electrode pairs.

[0032] After the DC power supply 6 is turned on, the groundwater pH in the vertical barrier control area is monitored in real time, and the permeability coefficient of the soil at the boundary of each antioxidant graphite electrode 2 is monitored: When the pH value of groundwater is lower than 5 or higher than 9, the contaminated groundwater is extracted from the open screen steel pipe 1 through electroosmosis, and acid-base regulating liquid is added to the open screen steel pipe 1 in time to maintain the groundwater environment neutral.

[0033] In some embodiments, the acid-base adjusting solution is a diluted solution of hydrochloric acid and sodium hydroxide.

[0034] When the permeability of the soil at a set depth in the vertically isolated control area reaches a set threshold, the connection between the graphite body 3 at that depth and the DC power supply 6 is disconnected by controlling the switch 7. In this embodiment, graphite bodies at different depths correspond to set depths.

[0035] When the permeability coefficient of the soil at all set depths in the vertical barrier control area reaches the set threshold, stop the power supply, remove the cable 5, and unplug the screen steel pipe 1 and the antioxidant graphite electrode 2. Mix the in-situ soil with sodium-modified calcium-based bentonite in a mass ratio of 3:1, fill it in layers into the holes left by the electrode extraction, and compact it layer by layer until the holes are sealed. At this point, the construction is completed.

[0036] It should be noted that the removed open screen steel pipe 1 and oxidation-resistant graphite electrode 2 can be reused.

[0037] The vertical barrier control structure for the contaminated site of the electrophoresis combined with microorganisms in this embodiment has a wall permeability coefficient of about 0.1~0.5×10 -8 cm / s, meeting the anti-seepage requirements of vertical barriers for conventional polluted land.

[0038] Comparative Example: This comparative example provides a method for vertical isolation and control of contaminated sites based on electrophoresis, which specifically includes the following steps: Clean the surface and determine the boundaries of the area to be vertically isolated and controlled.

[0039] A plurality of anti-oxidation graphite electrodes 2 are evenly inserted at intervals of 1 to 1.5 m at the boundary of the area to be vertically isolated and controlled.

[0040] In the area to be controlled, a screened steel pipe 1 is inserted at a certain distance from the boundary and parallel to the anode at intervals of 1 to 1.5 meters. It should be noted that the screened steel pipe 1 and the antioxidant graphite electrode 2 are arranged in parallel and staggered.

[0041] The oxidation-resistant graphite electrode 2 is used as the anode, the screened steel pipe 1 is used as the cathode, and the adjacent anodes and cathodes are connected to the DC power supply 6 through the cable 5 to form a plurality of electrode pairs.

[0042] After the DC power supply 6 is turned on, the groundwater pH in the vertical barrier control area is monitored in real time, and the permeability coefficient of the soil at the boundary of each antioxidant graphite electrode 2 is monitored: When the pH value of groundwater is lower than 5 or higher than 9, the contaminated groundwater is extracted from the open screen steel pipe 1 through electroosmosis, and acid-base regulating liquid is added to the open screen steel pipe 1 in time to maintain the groundwater environment neutral.

[0043] When the permeability coefficient of the soil at the set depth in the area to be vertically blocked and controlled reaches a set threshold, the connection between the graphite body 3 at the depth and the DC power supply 6 is disconnected by controlling the switch 7 .

[0044] When the permeability coefficient of the soil at all set depths in the vertical barrier control area reaches the set threshold, stop the power supply, remove the cable 5, and unplug the screen steel pipe 1 and the antioxidant graphite electrode 2. Mix the in-situ soil with sodium-modified calcium-based bentonite in a mass ratio of 3:1, fill it in layers into the holes left by the electrode extraction, and compact it layer by layer until the holes are sealed. At this point, the construction is completed.

[0045] The vertical barrier control structure of the contaminated site in this comparative example has a wall permeability coefficient of about 2~5×10 -8 cm / s, meeting the anti-seepage requirements of vertical barriers for conventional polluted land.

[0046] Comparing Example 2 with the comparative example, the only difference is that in Example 2, microbial liquid and cementing liquid are injected into the injection hole of the antioxidant graphite electrode 2. It can be seen that the injection of microbial liquid and cementing liquid further compacts the soil particles, which is beneficial to improving the anti-seepage effect of the vertical barrier wall formed after the electrophoresis combined with the microbial action.

[0047] The construction method for the later repair and maintenance of the vertical barrier wall formed after the action of electrophoresis combined with microorganisms in the present invention is generally the same as the method during construction. The only difference is that during repair and maintenance, the open screen steel pipe 1 (cathode) and the antioxidant graphite electrode 2 (anode) do not need to be inserted to the designed depth of the barrier wall, but only need to be inserted into the damaged and ineffective area to reach the damage depth. It will not be repeated here.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A vertical barrier control structure for contaminated sites using electrophoresis combined with microorganisms, characterized in that: It includes an anti-oxidation graphite electrode and an open screen steel pipe. The anti-oxidation graphite electrode is inserted at the boundary of the control area to be vertically isolated. The open screen steel pipe is staggered and inserted in the control area to be vertically isolated and parallel to the anti-oxidation graphite electrode. Microbial liquid and cementing liquid are injected into the anti-oxidation graphite electrode. The oxidation-resistant graphite electrode serves as an anode, the open-screen steel pipe serves as a cathode, and adjacent anodes and cathodes are connected to a DC power supply via cables to form a plurality of electrode pairs.

2. The electrophoresis-combined microbial contaminated site vertical barrier control structure according to claim 1 is characterized in that: The antioxidant graphite electrode includes a plurality of graphite bodies arranged in sequence from top to bottom, with insulating rubber pads provided between adjacent graphite bodies, the surface of the graphite body being coated with an antioxidant, and a cable connected to a DC power supply being provided in the middle thereof, and injection holes being provided on the graphite bodies for injecting microbial liquid and binder liquid.

3. The electrophoresis-combined microbial contaminated site vertical barrier control structure according to claim 2 is characterized in that: The cables connecting the graphite body and the DC power supply are each provided with a control switch, and the control switch is used to control the on and off of the graphite body at different depths and the DC power supply.

4. The electrophoresis-combined microbial contaminated site vertical barrier control structure according to claim 2 is characterized in that: The diameter of the graphite body ranges from 20 to 30 mm, and the length ranges from 80 to 100 cm. The diameter of the sieve steel pipe ranges from 20 to 40 mm, and the length of the sieve steel pipe is the same as that of the oxidation-resistant graphite electrode.

5. The electrophoresis combined with microbial contaminated site vertical barrier control structure according to claim 1 is characterized in that: The intervals between adjacent open-screen steel pipes, adjacent anti-oxidation graphite electrodes, and between the open-screen steel pipes and the anti-oxidation graphite electrodes are all 1-1.5 m, and the open-screen steel pipes and the anti-oxidation graphite electrodes are arranged in parallel and staggered manner.

6. A method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms, characterized in that: The method is achieved by the electrophoresis-combined microbial contaminated site vertical barrier control structure according to any one of claims 1 to 5, comprising: Determine the boundaries of the area to be vertically isolated and controlled; Multiple oxidation-resistant graphite electrodes are evenly inserted at the boundaries of the area to be vertically isolated and controlled; Staggered screen steel pipes are inserted in the vertical isolation control area parallel to the oxidation-resistant graphite electrode; Injecting microbial liquid and cementing liquid through the injection hole of the antioxidant graphite electrode; The oxidation-resistant graphite electrode is used as the anode, the open screen steel pipe is used as the cathode, and the adjacent anodes and cathodes are connected to the DC power supply through cables to form multiple pairs of electrodes; Real-time groundwater pH monitoring of the vertical barrier control area and permeability coefficient monitoring of the soil boundary of each antioxidant graphite electrode area; When the pH value of groundwater is lower than 5 or higher than 9, the contaminated groundwater is extracted by electroosmosis into the open-screen steel pipe; When the permeability coefficient of the soil at the set depth in the vertical barrier control area reaches the set threshold, the connection between the graphite body at that depth and the DC power supply is disconnected by controlling the switch; When the permeability coefficient of the soil at all set depths in the vertical barrier control area reaches the set threshold, the power is turned off, the cables are removed, the anti-oxidation graphite electrodes and the screened steel pipes are unplugged, and the remaining holes are sealed.

7. The method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms according to claim 6, characterized in that: It also includes adding acid-base regulating liquid into the open screen steel pipe to maintain the environmental pH value of the area to be vertically isolated and controlled to be neutral, and the acid-base regulating liquid is a diluted solution of hydrochloric acid and sodium hydroxide.

8. The method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms according to claim 6, characterized in that: The sealing operation includes: The in-situ soil and sodium-modified calcium-based bentonite were mixed in a mass ratio of 3:1 to obtain filling soil material; Fill the holes left after the electrodes are pulled out with filling soil in layers, and compact them layer by layer until the holes are sealed.

9. The method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms according to claim 6, characterized in that: The microbial culture liquid is any one of the microbial culture liquids that can produce urease; And / or, the binder fluid is a mixed aqueous solution of urea and calcium chloride, wherein the concentrations of urea and calcium chloride are both 1-2 mol / L.

10. The method for vertical isolation and control of contaminated sites using electrophoresis combined with microorganisms according to claim 6, characterized in that: The insertion depth of the screening steel pipe is the design depth of the vertical barrier wall, and the screening steel pipe is screened from 0.5m below the ground to the bottom of the area to be vertically blocked and controlled.

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