Heavy metal pollution site remediation device and method based on wind-solar-electricity cooperation

Abstract

The invention discloses a heavy metal contaminated site remediation device and method based on wind-light-electricity cooperation. The device comprises a wind-light complementary power supply system, a high-selectivity oxygen-permeable liquid-blocking composite membrane, an anti-seepage membrane, an anode electrode, a cathode electrode, a power source and a stirring device. The method comprises the steps of water solution injection, electrochemical reaction and supernate purification. A wind-solar complementary power supply system is introduced, an electrode-pollution medium micro-interface reaction system is formed in a pollution site, an electrochemical oxidation process is induced through an external electric field, and distribution of oxygen in medium pores and migration and diffusion of pollutants are enhanced in combination with a stirring device; therefore, multiple repair mechanisms such as electrochemical oxidation, oxygen weathering and local acidification are synergistically realized, and conversion and removal of heavy metals from a stable binding state to a transferable ion state are effectively promoted. The method has the advantages of being green, efficient, intelligent, controllable, high in environmental adaptability and the like, and is particularly suitable for repairing heavy metal polluted sites in remote or power-grid-free areas.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental remediation, and specifically relates to a heavy metal contaminated site remediation device and method based on wind and solar power synergy. Background Art

[0002] With the acceleration of industrialization, mining, smelting emissions, and the storage and leakage of hazardous solid waste (such as heavy metal-containing slag, sludge, and tailings) are becoming increasingly prominent, leading to a growing number of heavy metal-contaminated sites. The strong retention and non-degradability of heavy metals make them easily migrate and spread through the site-groundwater system, posing ecological and health risks.

[0003] At present, hydrometallurgical technology can achieve heavy metal dissolution through chemical leaching. For example, patent CN202011609695.5 discloses "a device and method for treating hydrometallurgical heavy metal wastewater". By introducing leaching agents such as acid, alkali, and complexing agent, heavy metals are promoted to react with H +Alternatively, complexing agents can undergo ion exchange reactions, or redox reactions can convert insoluble heavy metal oxidation states into soluble ions. Targeted removal can be achieved by adjusting parameters. However, these technologies suffer from high reagent consumption (5L-10L of extractant per ton of soil), a high risk of residual contamination (with reagent penetration rates less than 30%), and high energy consumption (20kWh-50kWh per ton of soil / solid waste treated). This makes long-term stable operation particularly challenging in remote sites without power grid coverage. Traditional electrokinetic remediation technologies use an external electric field to drive the targeted migration of heavy metals within the site, achieving enrichment and removal. This offers advantages in treatment depth and efficiency. For example, patent CN201621448607.7 discloses a "device for electrokinetic remediation of heavy metal-contaminated soil." This device uses a DC power supply connected to a pair of electrodes, each located in two wells within the contaminated area. The lower sides of the dissolution tank are connected to the electrode wells via a water pump, while the upper sides are connected to two auxiliary wells via a water pump. Under the action of the electric field, heavy metals migrate directionally toward the electrode area and are effectively removed by cleaning the electrodes and discharging the enriched liquid from the dissolution tank. However, this method still has problems such as high reagent consumption (5L-10L of leaching agent is required for each ton of soil or hazardous waste), high risk of residual pollution (the reagent penetration rate is less than 30%), and high energy consumption (20kWh-50kWh of electricity is consumed for each ton of soil / hazardous waste treatment). Long-term stable operation is difficult to achieve, especially in remote sites or hazardous waste dumps without power grid coverage. In addition, traditional electric remediation technology drives the directional migration of heavy metal ions in the contaminated medium through an external electric field, combines polar enrichment with liquid phase discharge to achieve pollutant removal, and has good treatment depth and migration control capabilities. For example, patent CN201621448607.7 discloses "an electric remediation device for heavy metal contaminated soil", which uses a DC power supply to connect a pair of electrode rods, which are respectively set in two water wells in the contaminated area, and is supplemented by a dissolution tank and a water pump circulation system to achieve liquid transmission and heavy metal enrichment. However, this type of technology still has the problem of being highly dependent on external power sources. When used in the wild or at historical hazardous solid waste sites, it is often difficult to promote due to the difficulty of wiring, poor system flexibility, and high operating costs (wiring costs can account for more than 40% of the total system cost).

[0004] Based on this, the present invention proposes a heavy metal contaminated site remediation device and method based on wind and solar power synergy. Summary of the Invention

[0005] In order to solve the above technical problems, the first purpose of the present invention is to provide a heavy metal contaminated site remediation device based on wind and solar power synergy, which uses electric field drive to replace the input of chemical leaching agents, introduces in situ electrochemical reactions in the contaminated site, and constructs an "electrode-contaminated medium" micro-interface system to achieve efficient conversion of stable heavy metals into soluble states; its core mechanisms include: direct oxidation (activating mineral lattices to release heavy metals), indirect oxidation (using highly active oxygen species such as ·OH), O2 weathering (O2 reacts with bound heavy metals to promote oxidative dissolution), and anode acid production to synergistically break the adsorption and complexation restrictions, improve desorption and migration efficiency, and synergistically break the boundaries of heavy metal adsorption and complexation, thereby improving desorption and migration efficiency.

[0006] The second object of the present invention is to provide a repair method for a heavy metal contaminated site repair device based on the synergy of wind and solar power.

[0007] The first object of the present invention is achieved as follows: it includes a wind-solar hybrid power supply system, a highly selective oxygen-permeable and liquid-resistant composite membrane, an anti-seepage membrane, an anode electrode, a cathode electrode, a power supply and a stirring device. A repair groove is excavated in the polluted area, and the side walls of the repair groove are paved with a highly selective oxygen-permeable and liquid-resistant composite membrane, and the bottom of the repair groove is paved with an anti-seepage membrane. The highly selective oxygen-permeable and liquid-resistant composite membrane and the anti-seepage membrane play a role in preventing pollutants from diffusing outward. The anode electrode is arranged in a surrounding manner in the repair groove, and the cathode electrode is arranged vertically in the repair groove, and the cathode electrode is located in the center of the area formed by the anode electrode. The anode electrode is electrically connected to the positive electrode of the power supply outside the repair groove, and the cathode electrode is electrically connected to the negative electrode of the power supply. A stirring device is provided in the repair groove, and the repair groove is backfilled with a homogenized polluted medium (such as soil or hazardous waste). The power supply and the stirring device are respectively electrically connected to the wind-solar hybrid power supply system. The device integrates wind-solar energy supply, electrode reaction, stirring enhancement, pollution isolation and recycling, and has the advantages of simple structure, efficient operation and strong adaptability. It is suitable for on-site continuous treatment and engineering application promotion of heavy metal contaminated sites.

[0008] This invention proposes an in-situ electrochemical reaction system driven by a wind-solar hybrid power supply system, replacing traditional chemical input. By constructing an "electrode-contaminated medium" micro-interface, it leverages the synergistic effects of electrooxidation (such as direct oxidation of heavy metal ions at the anode), O2 weathering (O2 reacts with soil colloid-bound heavy metals), and acidification (electrolysis of water to generate H⁺ to break adsorption), achieving efficient conversion of heavy metals from a stable to a soluble state. Compared to existing technologies, this invention eliminates the need for external power sources and chemical reagents, offering significant advantages in low-carbon, intelligent, and in-situ remediation. It is particularly suitable for the sustainable remediation of heavy metal-contaminated sites in remote areas.

[0009] Among them, the wind-solar complementary power supply system is a common wind and solar energy coordinated power supply system in this field, which usually includes wind turbines, solar panels, control modules and other components to realize the collection, regulation, storage and intelligent distribution of wind / solar energy; wind turbines and solar panels are deployed at the polluted site, and the control module uniformly integrates, stores and allocates wind and solar energy resources, and intelligently judges and switches the power supply mode according to the real-time wind speed and light intensity: when the wind speed is sufficient or the sunshine is strong, the system gives priority to using wind and solar energy to power power units such as power supplies and stirring devices; when the wind energy or light is insufficient, the energy storage unit outputs electricity to ensure the continuous and stable operation of the repair system.

[0010] Preferably, the highly selective oxygen-permeable and liquid-resistant composite membrane is a unidirectional multi-layer composite structure, which allows internal and external gases to flow and blocks the internal liquid and ions from flowing outward, including an inner layer, a middle layer and an outer layer. It should be noted that the inner layer is in contact with the contaminated medium in the repair tank, while the outer layer is in contact with the side wall of the repair tank; the inner layer is a nanofiltration membrane, a reverse osmosis membrane or a functionalized polyamide membrane, and the inner layer is used to selectively filter ions and particles. The middle layer is a polytetrafluoroethylene membrane (PTFE), a polyvinylidene fluoride membrane (PVDF) or a high-density polyethylene membrane (HDPE), and the middle layer plays an anti-seepage and chemical stabilization role. The outer layer is a polypropylene mesh, polyester fiber cloth or non-woven fabric. The outer layer is a supporting structure to enhance the overall mechanical strength and durability.

[0011] Preferably, the anode electrode is a hollow cylindrical structure, and its material is titanium sheet (Ti), titanium-based multi-metal oxide coating (such as RuO2, IrO2, Ta2O5), carbon-based material (such as graphite carbon felt, carbon nanotubes, graphene), conductive polymer (such as polypyrrole, polyaniline) or alloy material.

[0012] Preferably, the cathode electrode is made of titanium, stainless steel, carbon-based materials (graphite, carbon nanotubes), nickel, conductive polymers (such as polypyrrole, polyaniline) or alloy materials (such as nickel alloy, iron-titanium alloy, and oxide-coated aluminum).

[0013] Preferably, the power supply power is 50W~200W, and the output voltage is 3V~24V.

[0014] Preferably, the distance between the anode electrode and the cathode electrode is 0.1m~0.3m.

[0015] Preferably, the stirring device includes a stirring drive, a stirring shaft, and a stirring impeller. The stirring drive is located above the repair tank, the power output of the stirring drive is connected to the stirring shaft, and the end of the stirring shaft is connected to the stirring impeller. The cathode electrode is a tubular structure, the stirring shaft passes through the cathode electrode and does not contact the cathode electrode, and the stirring impeller is located in the area between the lower end of the cathode electrode and the anti-seepage membrane.

[0016] Among them, the length of the stirring shaft of the stirring device can be flexibly selected according to needs, the stirring shaft and the stirring driver are detachably connected, and the stirring shaft and the stirring impeller are also detachably connected. According to the depth of the repair medium or the reaction requirements, the stirring shaft of the required length and the stirring impeller of the required size can be flexibly replaced to adjust the stirring depth and stirring range.

[0017] Preferably, it also includes a liquid circulation device, which includes a water storage tank, a water inlet pipe, a water outlet pipe, an inlet pump, and an outlet pump. The water storage tank is arranged outside the repair tank, and the inlet pump is arranged in the water storage tank. One end of the inlet pipe is connected to the inlet end of the inlet pump, and the other end is located in the repair tank and above the contaminated medium. One end of the outlet pipe is located at the bottom of the water storage tank, and the other end is located in the repair tank and above the contaminated medium. The outlet pipe is provided with an outlet pump.

[0018] The second object of the present invention is achieved by comprising the following steps: S1. Inject aqueous solution into the repair tank to improve the conductivity of the system and accelerate the electrochemical reaction rate. The injection volume is 5 to 6 times the volume of the backfilled contaminated medium; S2. Turn on the power supply and the stirring device. The stirring device stirs the contaminated medium to promote the uniform distribution of pollutants and oxygen in the medium and enhance the reaction efficiency with the electrodes. The anode electrode, the cathode electrode and the contaminated medium form an "electrode-contaminated medium" micro-interface structure, an electrochemical reaction occurs, and the heavy metals are converted from a stable binding state to a mobile ionic state; S3. The supernatant produced in the repair tank is discharged and purified and then sent back to the repair tank.

[0019] Among them, the purification of the supernatant can be carried out by chemical precipitation, ion exchange, membrane separation, electrodeposition, electrocoagulation and bioadsorption technologies to effectively remove and recover heavy metal ions in the supernatant; according to the specific pollution type and ion characteristics, a single or combined treatment method can be selected; the treated supernatant is returned to the repair tank after meeting the safety concentration requirements, realizing the recycling of water resources and further improving the economy and sustainability of the repair system.

[0020] Preferably, the aqueous solution in step S1 is a 0.01 mol / L to 0.1 mol / L sodium sulfate or sodium chloride solution, which is used to improve the conductivity of the system, thereby enhancing the electrolyte effect and promoting the passage of current through the contaminated medium.

[0021] Compared with the prior art, the present invention has the following technical effects: 1. The present invention constructs an "electrode-contaminated medium" micro-interface reaction system consisting of a surrounding anode electrode and a central cathode electrode, and cooperates with a stirring device to achieve uniform distribution of pollutants in the pore fluid and sufficient contact with the electrode surface, thereby accelerating the reaction rate. This helps to overcome the problems of slow heavy metal migration and insufficient reaction contact in traditional in-situ remediation, improve remediation efficiency and applicability, and is particularly suitable for treating pollution containing highly mobile heavy metals such as Cd, Pb, and Zn. 2. This invention introduces a wind-solar hybrid power supply system that eliminates the need for external power supplies, water sources, or large-scale construction equipment. The entire system can be quickly deployed and activated on-site, making it suitable for historically contaminated sites with a lack of infrastructure, inconvenient transportation, or abandoned. The invention fully utilizes wind and solar energy resources to ensure a continuous and stable remediation process, effectively enhancing the green nature and operational reliability of the device. Combined with an in-situ reaction system, it avoids large-scale soil excavation and transportation, significantly reducing project costs and construction disturbances. It has strong on-site adaptability and deployment flexibility, making it suitable for promotion and application in various types of contaminated sites. 3. The present invention incorporates a highly selective oxygen-permeable and liquid-resistant composite membrane that allows only gas and heat to pass through while blocking liquids and metal ions. This structure effectively prevents "gas explosions" caused by gas or heat generated by electrolytic reactions accumulating in the tank during the repair process, ensuring system operation safety and soil stability. Furthermore, the highly selective oxygen-permeable and liquid-resistant composite membrane prevents electrolyte solution from leaking out of the repair tank, reducing disturbances to the surrounding environment and improving the controllability and environmental friendliness of the repair process. 4. The present invention is also provided with a liquid recycling device. The supernatant collected in the water storage tank is subsequently purified and can be sent back to the water storage tank and then back to the repair tank, thereby realizing the recycling of water resources and achieving the coordinated unity of pollution control and full utilization of resources. It has good environmental friendliness and engineering promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the device of the present invention; Figure 2 Schematic diagram of the top view of the anode electrode and the cathode electrode; Figure 3 Schematic diagram of the process of the present invention; In the figure: 1-wind-solar hybrid power supply system, 2-highly selective oxygen-permeable and liquid-resistant composite membrane, 3-anti-seepage membrane, 4-anode electrode, 5-cathode electrode, 6-power supply, 7-polluted medium, 801-stirring drive, 802-stirring shaft, 803-stirring impeller, 901-water storage tank, 902-water inlet pipe, 903-water outlet pipe. DETAILED DESCRIPTION

[0023] The present invention is further described below with reference to the embodiments and drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0024] Example 1 As attached Figure 1~Figure 2 As shown, the heavy metal contaminated site remediation device based on wind and photovoltaic synergy in this embodiment includes a wind and photovoltaic complementary power supply system 1, a highly selective oxygen permeable liquid barrier composite membrane 2, an anti-seepage membrane 3, an anode electrode 4, a cathode electrode 5, a power supply 6 and a stirring device. A 1m×1m×4m (length, width and height) remediation groove is excavated in the contaminated area. A highly selective oxygen permeable liquid barrier composite membrane 2 with a thickness of 0.1m is laid on the side wall of the remediation groove. The highly selective oxygen permeable liquid barrier composite membrane 2 is a unidirectional multi-layer composite structure, including an inner layer, a middle layer and an outer layer. The inner layer is a nanofiltration membrane, the middle layer is a polytetrafluoroethylene membrane, and the outer layer is a polypropylene mesh. An anti-seepage membrane 3 is laid on the bottom of the remediation groove. The anti-seepage membrane 3 adopts an anti-seepage geotextile with a thickness of 5mm. The anode electrode 4 is arranged around the remediation groove. The electrode 4 is a hollow cylindrical structure with a diameter of 0.7m and is made of graphite carbon felt. The cathode electrode 5 is vertically arranged in the repair tank, and the cathode electrode 5 is located in the center of the area surrounded by the anode electrode 4. The cathode electrode 5 is a hollow stainless steel tube with a diameter of 0.1m. The anode electrode 4 is electrically connected to the positive pole of the power supply 6 outside the repair tank, and the cathode electrode 5 is electrically connected to the negative pole of the power supply 6. The power supply 6 is a DC regulated power supply with a power of 150W. An electric stirring device with a rated power of 100W is provided in the repair tank. The repair tank is backfilled with a homogenized contaminated medium 7. The power supply 6 and the stirring device are respectively electrically connected to the wind-solar complementary power supply system 1. The wind-solar complementary power supply system 1 has a wind power generation rated power of 1kW and a total power of 500Wp for the solar panel.

[0025] Example 2 The heavy metal contaminated site remediation device based on wind and solar power synergy in this embodiment is based on Example 1, and differs from Example 1 in that: the stirring device includes a stirring driver 801, a stirring shaft 802, and a stirring impeller 803. The stirring driver 801 is located above the remediation tank. The power output portion of the stirring driver 801 is connected to the stirring shaft 802. The stirring shaft 802 has a diameter of 0.07 m. The end of the stirring shaft 802 is connected to the stirring impeller 803, which is a multi-blade stirring impeller. The cathode electrode 5 is a tubular structure. The stirring shaft 802 passes through the cathode electrode 5 without contacting the cathode electrode 5. The stirring impeller 803 is located in the area between the lower end of the cathode electrode 5 and the anti-seepage membrane 3. The wind-solar complementary power supply system 1 has a wind power rating of 500 W, a total power of 400 Wp for the solar panel, a remediation tank with dimensions of 1 m×1 m×3 m (length, width, and height), a 4 mm thick anti-seepage geotextile, a 0.6 m diameter anode electrode 4 made of titanium, and a power supply 6 with a power of 130 W.

[0026] Example 3 The heavy metal contaminated site remediation device based on wind and photovoltaic synergy of this embodiment is based on Example 2, and is different from Example 2 in that it also includes a liquid recycling device, which includes a water storage tank 901, a water inlet pipe 902, a water outlet pipe 903, an inlet pump, and an outlet pump. The water storage tank 901 is arranged outside the repair tank, and the water inlet pump is arranged in the water storage tank 901. The water inlet pump is used to pump the supernatant in the repair tank into the water storage tank 901. One end of the water inlet pipe 902 is connected to the water inlet pipe 903. The water inlet end of the water pump is connected, and the other end is located in the repair tank and above the contaminated medium 7. One end of the outlet pipe 903 is located at the bottom of the water storage tank 901, and the other end is located in the repair tank and above the contaminated medium 7. The outlet pipe 903 is provided with an outlet pump, which is used to pump the treated liquid in the water storage tank 901 back to the repair tank; after the water storage tank 901 collects a certain amount of supernatant, the supernatant is taken out and purified, and then sent back to the water storage tank 901 after treatment, and then sent back to the repair tank by the outlet pump.

[0027] Example 4 This example is based on the remediation method for heavy metal-contaminated sites using a wind-solar-electricity synergistic remediation device for wind and solar power, as described in Example 1. To verify the feasibility and effectiveness of the proposed wind-solar-electricity synergistic remediation device and method for heavy metal-contaminated sites, a wasteland was treated as an in-situ remediation test site. The site covers an area of ​​18 square meters and has a contamination depth of 1.2-3.5 meters. Sampling and testing revealed an initial pH of 7.1-8.3, oxidizable Cu concentrations of 140-490 mg / kg, Pb concentrations of 930-1120 mg / kg, and Cd concentrations of 50-210 mg / kg. According to the "Soil Pollution Risk Control Standard for Construction Sites with Soil Environmental Quality (GB36600-2018)", the Cu concentration in the concentrator did not exceed the screening value (2000 mg / kg), the Pb concentration exceeded the control value (400 mg / kg) for Class I land by approximately 2-3 times, and the Cd concentration exceeded the control value (20 mg / kg) for Class I land by approximately 2-10 times, identifying it as a typical area with moderate to severe heavy metal contamination. Demarcate the contaminated area: 1m×1m=1m 2 The scope of the repair is divided into regions, and the equipment is set up 3 days before the start of the repair. The specific implementation process is as follows: S1. Inject 0.01 mol / L sodium sulfate electrolyte solution into the repair tank, the injection volume is 5 times the volume of the backfilled contaminated medium; S2. Turn on the power supply 6 and the stirring device. The initial setting of the power supply working voltage is 10V. On the first day, due to insufficient wind and light resources, the wind-solar complementary power supply system automatically switches to the energy storage power supply mode to drive the stirring device to operate; the stirring frequency is set to 20rpm, and an intermittent working mode of 30min operation and 15min rest is adopted to maintain the homogeneity of the reaction system; the anode electrode 4, the cathode electrode 5 and the polluted medium form an "electrode-polluted medium" micro-interface structure, and an electrochemical reaction occurs; from the second day on, the wind power increases, and the wind-solar complementary power supply system switches to the wind-solar complementary power supply system automatically Switching to wind power supply mode, the stirring device is driven by stable wind power, reducing the load on the energy storage system. Starting from the fourth day, the power supply voltage is increased to 18V to enhance the anodic oxidation effect, increase the rate of O2 release and the acid production reaction of electrolytic water, and further promote the oxidation, dissolution and migration of heavy metals. Starting from the sixth day, to further improve the reaction efficiency, the stirring frequency is adjusted to 30rpm, and the operation mode is changed to 40 minutes of stirring and 10 minutes of rest to enhance O2 distribution and material diffusion rate. The above stirring parameter adjustment is achieved using a dedicated controller for stirring devices commonly used in the field. S3. On the third day of operation, the supernatant produced in the repair tank was collected and the Pb 2+ The concentration is 630mg / kg, Cd 2+ The concentration of Pb and Cd in the supernatant was 90 mg / kg. After the supernatant was treated by precipitation separation and ion exchange, the concentrations of Pb and Cd were reduced to below 0.2 mg / L and 0.05 mg / L respectively, meeting the third level standard of the Integrated Wastewater Discharge Standard (GB8978-1996). The treated liquid was returned to the remediation tank. On the sixth day of operation, the second batch of supernatant produced in the remediation tank was collected and tested for pollutants in the soil. The concentration of Pb was reduced to about 450 mg / kg and the concentration of Cd was reduced to 22 mg / kg. The pollutants were still in the active migration and reaction stage. After the supernatant was treated by precipitation separation and ion exchange, the concentrations of Pb and Cd were reduced to 0.2 mg / L and 0. 05mg / L or less, meeting the third level standard of the "Integrated Sewage Discharge Standard" (GB8978-1996), and the treated liquid was returned to the remediation tank; on the 8th day, samples were taken again and the residual heavy metal concentrations in the supernatant and soil were analyzed. The results showed that Pb dropped to 350mg / kg and Cd dropped to 10mg / kg, and the continuous monitoring change rate was less than 5%, which was in line with the Class I land limit in the "Soil Environmental Quality Construction Land Soil Pollution Risk Screening Standard" (GB36600-2018). The remediation met the standards and the shutdown operation was executed. Finally, the supernatant and the metal sediments enriched in the cathode electrode were recovered and processed to realize the resource utilization of heavy metals, and the remediation process was completed.

[0028] Example 5 This example is a remediation method for a heavy metal contaminated site remediation device based on wind and solar power synergy, as described in Example 2. To verify the feasibility and effectiveness of the wind and solar power synergy heavy metal contaminated site remediation device and method proposed in this invention, treatment was conducted on a plot of land belonging to an abandoned nonferrous smelter. During the historical smelting process in this area, the storage of lead-containing waste slag and the leakage of nickel-containing waste liquid resulted in significant enrichment of nickel (Ni) and lead (Pb) in the soil, posing a clear environmental risk. After sampling and analysis, the contaminated soil was mainly distributed within a depth range of 0.8-2.5m, with a soil pH of 6.4-7.5, a Ni concentration of 300-560mg / kg, and a Pb concentration of 550-825mg / kg. According to the "Soil Environmental Quality Construction Land Soil Pollution Risk Control Standard (GB36600-2018)", the control values ​​for Ni and Pb for Class I land are 150mg / kg and 400mg / kg, respectively, indicating that this plot is a typical moderate Ni-Pb complex contaminated area. Demarcation of the contaminated site: 1m×1m=1m 2 The scope of the repair is divided into regions, and the equipment is set up 3 days before the start of the repair. The specific implementation process is as follows: S1. Inject 0.05 mol / L sodium chloride solution into the repair tank, the injection volume is 6 times the volume of the backfilled contaminated medium; S2. Turn on the power supply 6 and the stirring device. The power supply operating voltage is initially set to 15V. On the first day, the power provided by wind power generation is preferentially used to drive the stirring driver 801. The stirring frequency is set to 20rpm, and an intermittent mode of 30min operation and 15min rest is adopted to ensure the initial homogeneity of the soil reaction system and the smooth start of the oxidation reaction. The anode electrode 4, the cathode electrode 5 and the polluted medium form an "electrode-polluted medium" micro-interface structure, and an electrochemical reaction occurs. Starting from the third day, the wind speed gradually decreases, and the system determines that the wind speed is insufficient and automatically switches to the "energy storage + photovoltaic" combined power supply mode to maintain the stable operation of the stirring system and electrodes and ensure the continuation of the electrochemical reaction. On the fifth day, the power supply voltage is increased to 18V to enhance the oxidation capacity of the anode area and the acid production reaction rate of electrolysis of water, further promoting the transformation and migration of pollutants. On the seventh day, to maintain O2 distribution and mass transfer efficiency, the system increases the stirring frequency to 30rpm and adjusts the operating mode to 40min stirring and 10min rest. The above stirring parameter adjustment is achieved by a dedicated controller for stirring drivers commonly used in the field. On the fifth day of operation, the supernatant from the remediation tank was collected and sampled for heavy metal concentrations in the contaminated medium. The results showed that the Ni concentration dropped from the initial 310 mg / kg to 185 mg / kg, and the Pb concentration dropped from 700 mg / kg to 520 mg / kg, accompanied by an increase in conductivity, indicating that the pollutants were in an active release and migration stage. After the supernatant was treated by oxidation precipitation + activated carbon adsorption, the Pb and Cd concentrations dropped to below 0.2 mg / L and 0.05 mg / L, respectively, meeting the third level standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996). The treated liquid was returned to the remediation tank. On the seventh day, the system recovered the second batch of supernatant and analyzed the pollutant concentrations at different depths. The results showed that the distribution of Ni (120 mg / kg) and Pb (500 mg / kg) tended to be uniform, the migration completion was improved, and the reaction rate decreased. After the supernatant was treated by oxidation precipitation + activated carbon adsorption, the concentrations of Pb and Cd dropped to below 0.2 mg / L and 0.05 mg / L respectively, reaching the third level standard of the "Integrated Sewage Discharge Standard" (GB8978-1996). The treated liquid was returned to the remediation tank; on the 9th day, the system recovered the third batch of supernatant, and the Ni concentration had dropped to 98.8 mg / kg, and the Pb concentration had dropped to 285 mg / kg. The concentration change rate was less than 5%, reaching the first-class screening value for construction land in the "Soil Environmental Quality Standard" (GB15618-2018). The remediation was determined to have met the standards, and the shutdown operation was automatically executed. The resource recovery process of the supernatant and electrode-enriched metals was entered, and the remediation process was successfully completed.

Claims

1. A heavy metal contaminated site remediation device based on wind and solar power synergy, comprising a wind and solar power complementary power supply system (1), a highly selective oxygen permeable liquid barrier composite membrane (2), an anti-seepage membrane (3), an anode electrode (4), a cathode electrode (5), a power supply (6) and a stirring device, characterized in that A repair tank is excavated in the polluted area, a highly selective oxygen-permeable and liquid-resistant composite membrane (2) is laid on the side wall of the repair tank, and an anti-seepage membrane (3) is laid on the bottom of the repair tank. The anode electrode (4) is arranged in a surrounding manner in the repair tank, and the cathode electrode (5) is arranged vertically in the repair tank, and the cathode electrode (5) is located in the center of the area formed by the anode electrode (4). The anode electrode (4) is electrically connected to the positive electrode of the power supply (6) outside the repair tank, and the cathode electrode (5) is electrically connected to the negative electrode of the power supply (6). A stirring device is provided in the repair tank, and the repair tank is backfilled with a homogenized polluted medium (7). The power supply (6) and the stirring device are electrically connected to the wind-solar complementary power supply system (1) respectively.

2. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The highly selective oxygen permeable liquid-resistant composite membrane (2) is a unidirectional multi-layer composite structure, comprising an inner layer, a middle layer and an outer layer, wherein the inner layer is a nanofiltration membrane, a reverse osmosis membrane or a functionalized polyamide membrane, the middle layer is a polytetrafluoroethylene membrane, a polyvinylidene fluoride membrane or a high-density polyethylene membrane, and the outer layer is a polypropylene mesh, a polyester fiber cloth or a non-woven fabric.

3. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The anode electrode (4) is a hollow cylindrical structure, and is made of titanium sheet, titanium-based multi-metal oxide coating, carbon-based material, conductive polymer or alloy material.

4. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The cathode electrode (5) is made of titanium, stainless steel, carbon-based material, nickel, conductive polymer or alloy material.

5. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The power supply (6) has a power of 50W~200W and an output voltage of 3V~24V.

6. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1, 3 or 4, characterized in that The distance between the anode electrode (4) and the cathode electrode (5) is 0.1m to 0.3m.

7. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The stirring device comprises a stirring driver (801), a stirring shaft (802), and a stirring impeller (803), wherein the stirring driver (801) is located above the repair tank, a power output portion of the stirring driver (801) is connected to the stirring shaft (802), and the end of the stirring shaft (802) is connected to the stirring impeller (803), the cathode electrode (5) is a tubular structure, the stirring shaft (802) passes through the cathode electrode (5) and does not contact the cathode electrode (5), and the stirring impeller (803) is located in the area between the lower end of the cathode electrode (5) and the anti-seepage membrane (3).

8. The heavy metal contaminated site remediation device based on wind and solar power synergy according to claim 1 is characterized in that The invention also includes a liquid recycling device, which includes a water storage tank (901), a water inlet pipe (902), a water outlet pipe (903), a water inlet pump, and a water outlet pump. The water storage tank (901) is arranged outside the repair tank, and the water inlet pump is arranged in the water storage tank (901). One end of the water inlet pipe (902) is connected to the water inlet end of the water inlet pump, and the other end is located in the repair tank and above the contaminated medium (7). One end of the water outlet pipe (903) is located at the bottom of the water storage tank (901), and the other end is located in the repair tank and above the contaminated medium (7). The water outlet pipe (903) is provided with a water outlet pump.

9. A method for repairing a heavy metal contaminated site based on the wind-photovoltaic synergy according to any one of claims 1 to 8, characterized in that The following steps are involved: S1. Inject aqueous solution into the repair tank, the injection volume is 5 to 6 times the volume of the backfilled contaminated medium; S2, turning on the power supply (6) and the stirring device, the stirring device stirs the polluted medium, the anode electrode (4), the cathode electrode (5) and the polluted medium form an "electrode-polluted medium" micro-interface structure, and an electrochemical reaction occurs; S3. The supernatant produced in the repair tank is discharged and purified and then sent back to the repair tank.

10. The repair method according to claim 9, characterized in that The aqueous solution in step S1 is a 0.01 mol / L to 0.1 mol / L sodium sulfate or sodium chloride solution.

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