In-situ remediation method for urban river and lake pollution sediment based on electroosmosis volume reduction-ecological cap sealing

Abstract

This invention discloses an in-situ remediation method for polluted urban river and lake sediments based on electroosmotic volume reduction and ecological capping. The method includes the following steps: S1: Constructing a cofferdam in the urban river or lake to be remediated, draining the water covering the area to be remediated, and allowing it to air dry naturally until the sediment moisture content is below 98%; S2: Inserting an electroosmotic volume reduction device into the area to be remediated to achieve rapid drainage of pore water and reduction of pollutants; S3: After the sediment moisture content in the area to be remediated is below 80%, removing the electroosmotic volume reduction device and laying an ecological capping device on the sediment; S4: After the in-situ ecological capping device is laid, gradually restoring the river or lake water level to its normal level. This in-situ remediation method for polluted urban river and lake sediments based on electroosmotic volume reduction and ecological capping can effectively solidify and reduce the volume of sediments, reduce the release of nitrogen and phosphorus nutrients from the sediments, and achieve long-term treatment of endogenous pollution.

Description

Technical Field

[0001] This invention relates to the technical field of polluted sediment remediation, specifically to an in-situ remediation method for polluted urban river and lake sediments based on electroosmotic volume reduction and ecological capping. Background Technology

[0002] In recent years, with the rapid advancement of urbanization and the dramatic increase in regional socio-economic development and population, a considerable portion of pollutants in urban rivers and lakes have accumulated in the bottom sediment through sedimentation or particulate adsorption, forming endogenous pollution and posing a continuous threat to the water environment of urban rivers and lakes. This has become an important issue that urgently needs to be addressed in current water environment management.

[0003] Currently, the main methods for treating endogenous pollution in urban rivers and lakes include ex-situ remediation and in-situ treatment. Ex-situ remediation involves dredging, dewatering, and disposal of bottom sediment. During dredging, disturbance to the sediment is inevitable, easily leading to secondary pollution and resulting in low dredging efficiency. According to industry engineering economic calculations, the estimated cost of sludge dredging and ex-situ disposal generally accounts for about 40% of the total investment in comprehensive water body treatment projects. On the other hand, in engineering practice, since urban rivers and lakes are often located in densely built-up areas, ex-situ dredging of bottom sediment not only has a significant environmental impact but also faces difficulties in coordinating surrounding sites for sediment dewatering and disposal. Therefore, there is an urgent need to develop efficient, stable, and sustainable in-situ remediation technologies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide an in-situ remediation method for polluted urban river and lake sediments based on electroosmotic volume reduction and ecological capping. This method can effectively solidify and reduce the volume of sediments, reduce the release of nitrogen and phosphorus nutrients in the sediments, and achieve long-term treatment of endogenous pollution.

[0005] To achieve the above objectives, the present invention provides an in-situ remediation method for polluted urban river and lake sediments based on electroosmotic volume reduction and ecological capping, comprising the following steps:

[0006] S1: Construct a cofferdam in the urban river or lake to be repaired, drain the water covering the area to be repaired, and allow it to dry naturally until the moisture content of the bottom mud in the area to be repaired is below 98%.

[0007] S2: Insert an electroosmotic volume reduction device into the area to be repaired to achieve rapid discharge of pore water from the sediment and reduction of pollutants.

[0008] S3: After the moisture content of the bottom sediment in the area to be restored is lower than 80%, pull out the electroosmotic volume reduction device and lay an ecological cap sealing device in the bottom sediment of the area to be restored.

[0009] S4: After the in-situ ecological cap sealing device is installed, the river and lake water levels will be gradually restored to normal levels, and the water level rise will not exceed 1m within 24 hours.

[0010] In a preferred embodiment, the electroosmotic capacity reduction device includes a solar panel, a controller, a battery, a protective cover, copper wires, an anode electrode plate, and a cathode electrode plate.

[0011] The lower part of the solar panel is equipped with a controller and a storage battery. The protective cover is located outside the controller and the storage battery. The solar panel is used to charge the storage battery, and the controller is used to control the solar panel to charge the storage battery. The storage battery is connected to the anode electrode plate and the cathode electrode plate respectively through copper wires.

[0012] In a preferred embodiment, the electroosmotic capacity reduction device further includes a supporting vertical rod, a connecting horizontal rod, and fixing plates. The top of the supporting vertical rod is connected to the solar panel, and the bottom of the supporting vertical rod is fixedly connected to the middle of the connecting horizontal rod. The fixing plates are respectively pasted onto the anode electrode plate and the cathode electrode plate, and the two ends of the connecting horizontal rod are respectively inserted into the fixing plates located on the anode electrode plate and the cathode electrode plate.

[0013] In a preferred embodiment, the copper wires are located inside the supporting vertical rod and the connecting horizontal rod; there are two copper wires, one side of which is connected to the positive and negative terminals of the battery respectively, and the other side passes through the supporting vertical rod, the connecting horizontal rod and the fixing plate in sequence and is connected to the anode electrode plate and the cathode electrode plate respectively.

[0014] In a preferred embodiment, both the anode electrode plate and the cathode electrode plate include a grid composite electrode, and the surface of the grid composite electrode is coated with a ruthenium-iridium anti-oxidation layer;

[0015] The mesh composite electrode is prepared by the following method: First, weigh the following raw materials according to the following weight proportions: 50-60 parts polyethylene, 10-20 parts polypropylene, 28-35 parts conductive graphite, 7-15 parts carbon black, and 5-10 parts anti-aging agent, and place them in a ceramic container; then, heat the above raw materials in an oven to 180-200 degrees Celsius and grind them for 15-20 minutes to ensure thorough mixing; finally, pour the thoroughly ground raw materials into a ceramic mold and cool them down by water to obtain the mesh composite electrode.

[0016] In a preferred embodiment, the thickness of the mesh composite electrode is 3-5 mm, and the diameter of the mesh holes in the mesh composite electrode is 10-15 mm; the depth to which the anode electrode plate and the cathode electrode plate are inserted into the sediment of the area to be repaired is the same as the thickness of the contaminated layer of the sediment of the area to be repaired.

[0017] In a preferred embodiment, the electroosmotic volume reduction device further includes a guide plate, and a V-shaped guide groove is formed between the guide plate and the cathode electrode plate. The included angle of the V-shaped guide groove is 30°-45°. Geotextile filter cloth is laid in the V-shaped guide groove and fixed by nylon strips. The inner wall of the V-shaped guide groove and the outer wall of the guide plate are both coated with an insulating paint layer.

[0018] In a preferred embodiment, the ecological cap sealing device includes a gabion net, hanging rings, a loading frame, hooks, natural coarse river sand, non-woven fabric wrapping, planting soil, and submerged plants; the hanging rings are positioned above the gabion net and fixedly connected thereto, and the loading frame is positioned below the gabion net and fixedly connected thereto by hooks.

[0019] The loading frame is filled with natural coarse river sand, the particle size of which is smaller than the aperture of the loading frame; the non-woven fabric wrapping is filled with planting soil, the non-woven fabric wrapping is placed inside the gabion mesh, and submerged plants are planted on the planting soil.

[0020] In a preferred embodiment, the planting soil comprises the following components by weight percentage: 50%-60% garden soil, 20%-35% peat moss, and 20%-25% river sand.

[0021] In a preferred embodiment, the nonwoven fabric wrapping is provided with a plurality of openings for planting submerged plants, with a spacing of 5-10 cm and a diameter of 1-2 cm; the submerged plants are planted on the planting soil, and the submerged plants extend upward through the openings on the nonwoven fabric wrapping and the mesh on the surface of the gabion net.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Firstly, this invention uses solar power for electroosmotic volume reduction and remediation of contaminated sediment, and the electroosmotic volume reduction device can be reused, allowing for rapid construction and operation, thus significantly reducing the cost of contaminated sediment treatment.

[0024] Secondly, the present invention forms an in-situ capping device by filling a steel gabion with natural coarse river sand, planting soil and submerged plants, which can be quickly and conveniently laid on the bottom of the lake with little construction difficulty and environmental impact; at the same time, it can be quickly removed after the treatment is completed without affecting the lake's regulation and storage function.

[0025] Third, the microbial inactivation effect caused by the electric field during the electroosmosis process of this invention is reversible, and the metabolic level of microorganisms in the sediment recovers significantly during the capping stage. Furthermore, the capping materials selected in this invention are all relatively stable, clean sand and gravel, with very low dissolution and release rates under long-term capping, resulting in minimal impact on the pH of the overlying water and offering environmentally friendly advantages. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the electroosmotic volume reduction device of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the fixing piece of the present invention;

[0028] Figure 3 This is a schematic diagram of the V-shaped flow channel of the present invention;

[0029] Figure 4 This is a schematic diagram of the gabion mesh structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the loading frame of the present invention;

[0031] Figure 6 This is a schematic diagram of the connection between the loading frame and the gabion mesh of the present invention;

[0032] Figure 7 This is a schematic cross-sectional view of the construction of the ecological cap sealing device of the present invention;

[0033] Figure 8 This is a graph showing the changes in TN and TP content in the sediment to be remediated during the electroosmosis process according to an embodiment of the present invention.

[0034] In the diagram, 1. Solar panel; 2. Controller; 3. Battery; 4. Protective cover; 5. Supporting vertical rod; 6. Connecting horizontal rod; 7. Fixing plate; 8. Copper wire; 9. Anode electrode plate; 10. Cathode electrode plate; 11. Guide plate; 12. Geotextile filter cloth; 13. Steel gabion mesh; 14. Steel lifting ring; 15. Loading frame; 16. Hook; 17. Natural coarse river sand; 18. Planting soil; 19. Non-woven fabric; 20. Submerged plants; 21. Ruthenium-iridium anti-oxidation layer; 22. Insulating varnish layer. Detailed Implementation

[0035] The following examples illustrate the implementation of the present invention in detail, but they do not constitute a limitation on the invention and are merely illustrative. Furthermore, the advantages of the present invention will become clearer and easier to understand by explaining them.

[0036] The present invention discloses an in-situ remediation method for polluted sediment in urban rivers and lakes based on electroosmosis volume reduction and ecological capping, comprising the following steps:

[0037] S1: Construct a cofferdam in the urban river or lake to be repaired, drain the water covering the area to be repaired, and allow it to dry naturally until the moisture content of the bottom mud in the area to be repaired is below 98%.

[0038] S2: Insert an electroosmotic volume reduction device into the area to be repaired to achieve rapid discharge of pore water from the sediment and reduction of pollutants.

[0039] S3: After the moisture content of the bottom sediment in the area to be restored is lower than 80%, pull out the electroosmotic volume reduction device and seal the bottom sediment surface with an ecological cap.

[0040] S4: After the in-situ ecological cap sealing device is installed, gradually restore the river and lake water level to the normal level, and the water level rise should not exceed 1m within 24 hours.

[0041] This invention applies a constant voltage electric field to the sediment in the remediation area, draining free water and weakly bound water from the sediment, reducing its moisture content, and improving the sediment solidification and volume reduction effect. During the electroosmotic volume reduction process, dissolved pollutants in the pore water migrate, and strong oxidizing properties are generated at the anode, which is beneficial for the oxidation and removal of sulfides and macromolecular humic acids in the sediment, while low-polymerization-degree protein-like organic matter can flow out with the electroosmotic water. To control the secondary release of pollutants from the electroosmotic sediment, a capping material is applied to the upper layer of the sediment to separate the contaminated sediment from the water body, slowing down the release of pollutants into the overlying water. During the capping process, the release of organic matter is significantly reduced, and the released organic matter is a low-polymerization-degree protein-like substance that is easily biodegradable and can eventually be decomposed by biomineralization through long-term natural reactions.

[0042] like Figure 1 As shown, the electroosmotic capacity reduction device includes a solar panel 1, a controller 2, a battery 3, a protective cover 4, a supporting vertical rod 5, a connecting horizontal rod 6, a fixing plate 7, copper wires 8, an anode electrode plate 9, a cathode electrode plate 10, a flow guide plate 11, and a geotextile filter cloth 12. The controller 2 and the battery 3 are located at the lower part of the solar panel 1, and the protective cover 4 is located outside the controller 2 and the battery 3. The solar panel 1 is used to charge the battery 3, and the controller 2 is used to control the solar panel 1 to charge the battery 3. The battery 3 is connected to the anode electrode plate 9 and the cathode electrode plate 10 respectively through the copper wires 8. The top of the supporting vertical rod 5 is connected to the solar panel 1, and the bottom of the supporting vertical rod 5 is fixedly connected to the middle of the connecting horizontal rod 6. Fixing plates 7 are respectively attached to the anode electrode plate 9 and the cathode electrode plate 10. Both ends of the connecting horizontal rod 6 are inserted into the fixing plates 7 located on the anode electrode plate 9 and the cathode electrode plate 10, respectively. Copper wires 8 are located within the supporting vertical rod 5 and the connecting horizontal rod 6. There are two copper wires 8; one side of each copper wire 8 is connected to the positive and negative terminals of the battery 3, respectively, and the other side passes through the supporting vertical rod 5, the connecting horizontal rod 6, and the fixing plates 7, respectively, and connects to the anode electrode plate 9 and the cathode electrode plate 10. A V-shaped guide groove is formed between the guide plate 11 and the cathode electrode plate 10, with an included angle of 30°-45°.

[0043] In this embodiment, the solar panel 1 consists of 60 photovoltaic modules arranged in a 6*10 grid, with dimensions of 1.65m*0.991m, used to charge the battery 3; the controller 2 is a constant current integrated controller with a nominal voltage of 24V, used to control the charging process of the solar panel 1 to the battery 3, protecting the battery 3 from overcharging or over-discharging; the battery 3 is a ternary lithium battery with an operating voltage of 20-24V, connected to the anode electrode plate 9 and the cathode electrode plate 10 respectively through copper wires 8 to form an electric field to realize the bottom mud Rapid drainage of mesoporous water and reduction of dissolved pollutants; the protective cover 4 is a stainless steel cuboid box, fixed to the bottom of the solar panel 1 with bolts, used to house the controller 2 and the battery 3; the supporting vertical rod 5 is a galvanized steel pipe with an inner diameter of 3-5cm and a wall thickness of 1-2mm, the top of which is connected to the protective cover with bolts, and the bottom is welded to the middle of the connecting horizontal rod 6; the supporting vertical rod 5 is 1-1.5m long; the connecting horizontal rod 6 is also a galvanized steel pipe with a length of 1.2-1.5m; fixing plates 7 are inserted at both ends of the connecting horizontal rod 6;

[0044] like Figure 2 As shown, the fixing plate 7 is made of polyethylene and is glued to the anode electrode plate 9 and the cathode electrode plate 10 respectively with strong adhesive to ensure that the connecting crossbar 6 is insulated from the anode electrode plate 9 and the cathode electrode plate 10. The position and height of the connecting crossbar 6 and the fixing plate 7 can be adjusted according to the depth of the anode electrode plate 9 and the cathode electrode plate 10 inserted into the bottom mud. There are two copper wires 8. One side is connected to the positive and negative terminals of the storage battery 3, and the other side passes through the supporting vertical rod 5 and the connecting crossbar 6 and the fixing plate 7 and is connected to the anode electrode plate 9 and the cathode electrode plate 10 respectively.

[0045] Both the anode electrode plate 9 and the cathode electrode plate 10 are 3-5mm thick mesh composite electrodes, with a ruthenium-iridium anti-oxidation layer 21 sprayed on the surface to prevent electrode corrosion during electroosmosis. The composite electrode is prepared by thermoplastic molding of polyethylene, polypropylene, conductive graphite, and carbon black. First, the following raw materials are weighed according to the following parts by weight: 50 parts polyethylene, 10 parts polypropylene, 28 parts conductive graphite, 7 parts carbon black, and 5 parts anti-aging agent, and placed in a ceramic container. Then, the above raw materials are heated to 180 degrees in an oven and ground for 15 minutes to ensure thorough mixing. Finally, the thoroughly ground raw materials are poured into a ceramic mold and cooled by water to obtain the composite electrode.

[0046] The vertical height and horizontal width of the anode electrode plate 9 and the cathode electrode plate 10 are 1m*0.8m; the diameter of the grid holes of the anode electrode plate 9 and the cathode electrode plate 10 is 10-15mm; the depth to which the anode electrode plate 9 and the cathode electrode plate 10 are inserted into the bottom sediment of the area to be remediated is the same as the thickness of the contaminated layer of the bottom sediment of the area to be remediated.

[0047] like Figure 3As shown, the V-shaped guide channel has an angle of 30 degrees and is coplanar with the cathode electrode plate 10; the non-coplanar areas of the V-shaped guide channel and the cathode electrode plate 10 are sprayed with insulating paint to form an insulating paint layer 22. After the electroosmotic water enters the guide channel, it flows into the collection pit; the geotextile filter cloth 12 is laid in the V-shaped guide channel and fixed by nylon strips to prevent bottom mud particles from flowing out during the electroosmosis process; the geotextile filter cloth 12 is 300 mesh;

[0048] like Figure 4 As shown, the ecological cap sealing device includes a gabion mesh 13, lifting rings 14, a loading frame 15, a winch 16, natural coarse river sand 17, non-woven fabric wrapping 18, planting soil 19, and submerged plants 20. The gabion mesh 13 is made of steel, has a square structure, and measures 0.5m * 0.5m * 0.15m, with a mesh diameter of less than 20mm. The lifting rings 14 are also made of steel and are welded to the upper surface of the gabion mesh 13. They are 10cm long, facilitating the lifting of the gabion mesh 13 by lifting equipment.

[0049] like Figure 5 , 6 As shown, the diameter of the natural coarse river sand 17 particles is 3-5mm. Since the diameter of the gabion mesh 13 is larger than the particle diameter of the natural coarse river sand 17, a loading frame 15 made of polyethylene with dimensions of 0.49m*0.49m*0.05m is set inside the gabion mesh 13. The aperture of the loading frame 15 is less than 2mm, which can prevent the natural coarse river sand 17 from escaping outward, thereby improving the storage time and treatment effect of the natural coarse river sand 17. The loading frame 15 is filled with natural coarse river sand 17. Specifically, four hooks 16 are set at the upper end of the loading frame 15 to fix it to the gabion mesh 13, and are respectively arranged at the four right angles of the loading frame 15.

[0050] like Figure 7 As shown, the non-woven fabric wrap 18 is formed by sewing the four sides of non-woven fabric together to prevent the planting soil 19 from spreading when exposed to water. The planar dimensions of the non-woven fabric wrap 18 filled with planting soil 19 are the same as those of the gabion mesh 13. The non-woven fabric wrap 18 is filled with planting soil 19 and pressed onto the surface of natural coarse river sand 17, with a thickness of 0.1m. The planting soil 19 comprises the following components by mass percentage: 50%-60% garden soil, 20-35% peat moss, and 20%-25% river sand. This helps retain the nutrients in the planting soil 19 while increasing its porosity, facilitating the rooting of submerged plants 20.

[0051] Submerged plants 20 are planted on planting soil 19 and pass upwards through pre-drilled openings on the surface of non-woven fabric wrapping 18 and mesh openings on the surface of gabion mesh 13. The non-woven fabric has evenly spaced openings, 5-10 cm apart and 1-2 cm in diameter, for planting the submerged plants 20. The submerged plants 20 are selected from dwarf Vallisneria natans, with a planting density of 60-70 plants / m². 2 .

[0052] To investigate the effectiveness of the aforementioned device in treating endogenous pollution in lakes, the method and device of this invention were applied to a closed bay of approximately 1.5 hectares in East Lake, Wuhan City. Changes in total nitrogen (TN) and total phosphorus (TP) content in the sediment and water to be remediated were monitored. TN in the sediment was determined using the semi-micro Kjeldahl method (GB 7173-87), and TP was determined using the SMT method. In the water, TN content was determined using alkaline potassium persulfate digestion ultraviolet spectrophotometry (HJ 636-2012), and total phosphorus content was determined using ammonium molybdate spectrophotometry (GB 11839-89). The curves showing the changes in TN and TP content in the sediment during electroosmosis are shown below. Figure 8 After the electroosmotic volume reduction device of this invention is laid on the lake bottom, the remaining total nitrogen content in the sediment decreases due to the high ammonia nitrogen leaching rate, while the remaining total phosphorus content is relatively high due to the low total phosphorus leaching rate. After the electroosmotic volume reduction process is completed, an ecological capping device is laid on the sediment to be restored, creating a barrier between the sediment and the overlying water, inhibiting the release of phosphorus from the sediment. After the lake water level recovers, the TN and TP content in the overlying water is continuously monitored. After 25 days, the TN and TP content in the overlying water gradually decreases, indicating that the barrier created by the ecological capping device prevents the release of TN and TP from the sediment into the water body.

[0053] In this invention, electroosmotic volume reduction not only effectively reduces the water content in the sediment but also enhances the removal of organic pollutants, particularly reducing the content of dissolved pollutants in the sediment pore water. Simultaneously, to control the secondary release of pollutants from the electroosmotic sediment, an ecological capping device is laid on the upper layer of the sediment, providing an effective barrier without threatening the health of the native ecosystem, thus offering environmentally friendly advantages. Furthermore, the volume of sediment to be remediated decreases during the electroosmotic volume reduction process, and the laying of the ecological capping device does not affect the river or lake's water storage capacity.

[0054] The above are merely specific embodiments of the present invention. It should be noted that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention. All other details not described in detail belong to the prior art.

Claims

1. A method for in-situ remediation of polluted sediment in urban rivers and lakes based on electroosmotic volume reduction and ecological capping, characterized in that: The application relates to a method for repairing a city river or lake. S1: building a cofferdam in the city river or lake to be repaired, draining the overlying water of the area to be repaired, naturally airing until the water content of the bottom mud of the area to be repaired is lower than 98%; S2: inserting an electro-osmosis volume reduction device into the area to be repaired to realize rapid discharge of the pore water of the bottom mud to be repaired and reduction of the pollutants; S3: after the water content of the bottom mud of the area to be repaired is lower than 80%, the electro-osmosis volume reduction device is pulled out, and an ecological cap sealing device is laid on the bottom mud of the area to be repaired; S4: after the ecological cap sealing device is laid in situ, the water level of the river or lake is gradually recovered to the normal water level. The electro-osmosis volume reduction device comprises a solar cell panel (1), a controller (2), a storage battery (3), a protective cover (4), a copper wire (8), an anode electrode plate (9) and a cathode electrode plate (10). The lower portion of the solar cell panel (1) is provided with the controller (2) and the storage battery (3), the protective cover (4) is arranged outside the controller (2) and the storage battery (3), the solar cell panel (1) is used for charging the storage battery (3), and the controller (2) is used for controlling the solar cell panel (1) to charge the storage battery (3); the storage battery (3) is connected with the anode electrode plate (9) and the cathode electrode plate (10) through the copper wire (8). The anode electrode plate (9) and the cathode electrode plate (10) both comprise a grid composite electrode, and the surface of the grid composite electrode is sprayed with a ruthenium-iridium anti-oxidation layer (21). The grid composite electrode is prepared by the following method: firstly, 50-60 parts of polyethylene, 10-20 parts of polypropylene, 28-35 parts of conductive graphite, 7-15 parts of carbon black and 5-10 parts of an anti-aging agent are weighed according to the weight fraction and are put into a ceramic container; then, the above raw materials are heated to 180-200 DEG C in an oven, are ground for 15-20 minutes and are fully mixed; finally, the fully ground raw materials are introduced into a ceramic mold, and the grid composite electrode is obtained after water cooling. The thickness of the grid composite electrode is 3-5 mm, the grid hole diameter of the grid composite electrode is 10-15 mm, the depth of the anode electrode plate (9) and the cathode electrode plate (10) inserted into the bottom mud of the area to be repaired is the same as the thickness of the pollution layer of the bottom mud of the area to be repaired. The electro-osmosis volume reduction device further comprises a guide plate (11), a V-shaped guide groove is formed between the guide plate (11) and the cathode electrode plate (10), the included angle of the V-shaped guide groove is 30 DEG -45 DEG, geotextile (12) is laid in the V-shaped guide groove and is fixed by nylon pull strips, and the inner wall of the V-shaped guide groove and the outer wall of the guide plate are both sprayed with an insulating paint layer (22).

2. The in-situ remediation method of urban river and lake polluted sediment based on electroosmotic volume reduction-ecological cap closure according to claim 1, characterized in that: The electric osmosis capacity reducing device further comprises a supporting vertical rod (5), a connecting horizontal rod (6) and a fixing sheet (7), the top of the supporting vertical rod (5) is connected with the solar cell panel (1), the bottom of the supporting vertical rod (5) is fixedly connected with the middle part of the connecting horizontal rod (6); the fixing sheet (7) is respectively pasted on the anode electrode plate (9) and the cathode electrode plate (10), the two ends of the connecting horizontal rod (6) are respectively inserted into the fixing sheets (7) on the anode electrode plate (9) and the cathode electrode plate (10).

3. The in-situ remediation method of urban river and lake polluted sediment based on electroosmotic volume reduction-ecological cap closure according to claim 2, characterized in that: The copper conductor (8) is located in the supporting vertical rod (5) and the connecting horizontal rod (6); the copper conductor (8) is two, one side of the two copper conductors (8) is connected with the positive and negative poles of the storage battery (3) respectively, and the other side sequentially passes through the supporting vertical rod (5), the connecting horizontal rod (6) and the fixing sheet (7) and is connected with the anode electrode plate (9) and the cathode electrode plate (10) respectively.

4. The in-situ remediation method of urban river and lake polluted sediment based on electroosmotic volume reduction-ecological cap closure according to any one of claims 1-3, characterized in that: The ecological cap sealing device comprises gabion net (13), lifting ring (14), loading frame (15), grappling hook (16), natural coarse river sand (17), non-woven fabric wrapping (18), planting soil (19) and submerged plant (20); the lifting ring (14) is arranged above the gabion net (13) and fixedly connected therewith, and the loading frame (15) is arranged below the gabion net (13) and fixedly connected therewith through the grappling hook (16). The loading frame (15) is filled with the natural coarse river sand (17), and the particle size of the natural coarse river sand (17) is smaller than the pore size of the loading frame (15); the non-woven fabric wrapping (18) is filled with the planting soil (19), and the non-woven fabric wrapping (18) is arranged in the gabion net (13), and the planting soil (19) is planted with the submerged plant (20).

5. The in-situ remediation method of urban river and lake polluted sediment based on electroosmotic volume reduction-ecological cap closure according to claim 4, characterized in that: The planting soil (19) comprises the following components in percentage by mass: 50%-60% garden soil, 20%-35% peat soil and 20%-25% river sand, and the sum of the percentage by mass of the above components is 100%.

6. The in-situ remediation method of urban river and lake polluted sediment based on electroosmotic volume reduction-ecological cap closure according to claim 5, characterized in that: A plurality of holes for planting the submerged plant (20) are arranged on the non-woven fabric wrapping (18), the hole distance is 5-10 cm, and the hole diameter is 1-2 cm; the submerged plant (20) is planted on the planting soil (19), and the submerged plant (20) extends upward through the holes on the non-woven fabric wrapping (18) and the mesh holes on the upper surface of the gabion net (13) in sequence.

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