CN103286120A - Microwave electric soil in-situ restoration device and restoration method - Google Patents

Abstract

The invention discloses a microwave electric soil in-situ restoration device and a restoration method, and belongs to the technical field of in-situ restoration for soil pollutions. The device consists of an electrode system, a microwave heating system and an underground water circulation system and comprises a negative electrode well (1) and the like, wherein a negative electrode (3) is arranged in the negative electrode well (1). A microwave absorption material is buried into the soil; a closed gas collection shed is constructed; a pH monitoring device and a temperature sensor are arranged in the closed gas collection shed; part of organic pollutants and heavy metals in the soil are treated; underground water is pumped out and then injected into the soil to increase the migration speed of live particles and accelerate the soil heating process; volatile organic compounds are recycled; distilled water is injected into the underground water; non-volatile and non-degradable organic pollutants and residual heavy metals are treated by a high-temperature microwave soil thermal restoration technology. The technical equipment is compact in structure, easy to operate and high in reliability and has high popularization potential home and abroad and in particular has a wide application prospect to composite soil pollutions with the heavy metals and the organic compounds.

Description

A microwave electrodynamic soil in-situ restoration device and restoration method

technical field

The invention relates to a microwave electric soil in-situ repair device and a repair method, belonging to the technical field of in-situ repair of soil pollution.

Background technique

With the process of industrialization, urbanization and modern agriculturalization in our country, soil pollution is becoming more and more serious, and it gradually manifests as compound pollution of various pollutants. In particular, heavy metal pollution and highly toxic and persistent organic pollution are the most prominent. They mainly come from abandoned factories and mines, sewage irrigation areas, domestic garbage, industrial waste, and the extensive use of pesticides and fertilizers. Investigations and studies have shown that heavy metal pollution such as cadmium, arsenic, and lead in my country has caused huge economic losses. On the other hand, organic pollution has become a current research hotspot due to its persistent, highly toxic, accumulative, and fluid characteristics, combined with the concealment, long-term, and irreversible characteristics of heavy metal pollution. In short, heavy metals and organic pollutants not only change the physical and chemical characteristics of the soil, leading to soil degradation, crop yield and quality reduction, but also pollute surface water and groundwater through runoff and leaching, deteriorating the hydrological environment, and may cause pollution through direct contact, food chain and other ways to endanger human life and health. Therefore, it is imminent to solve the remediation problem of this kind of compound polluted soil.

Currently, contaminated soil remediation technologies mainly include physical engineering remediation, steam extraction and bioremediation. Among them, although steam extraction can effectively treat gas-phase pollutants, other methods can only be used to treat liquid-phase and residual-phase pollutants, resulting in complex treatment systems and high treatment costs. Phytoremediation is the use of direct or indirect absorption, assimilation, and degradation of plants to restore contaminated soil, but the treatment cycle is long and no obvious effect can be achieved in a short time. Although the microbial degradation method is relatively simple to operate and has no pollution, specific microorganisms only degrade specific types of chemical substances. In addition, microbial activity is also greatly affected by changes in temperature and other environmental conditions, which greatly limits the scope of application of microbial degradation methods. It can be seen that each method has its pertinence, advantages and disadvantages of the remediation object. In fact, it is precisely because of the pertinence or singleness of this remediation that it has no application value when dealing with complex pollution. To overcome this limitation, a combined repair technique was developed.

Electrokinetic technology is an emerging soil in-situ remediation technology. This technology can effectively remove organic and inorganic pollutants in soil, especially heavy metals. It has strong controllability, good treatment effect, easy installation and operation, less manpower consumption, less exposure to toxic substances, high economic benefits and no damage to the original Natural environment and other advantages, so as to protect the original ecological environment to the greatest extent while carrying out environmental restoration. In recent years, there have been many small test research reports at home and abroad, and there are also a small number of pilot test and engineering application examples. In view of the low efficiency of this method for the treatment of organic matter, we introduced the heat treatment method with high restoration efficiency as another core content of this joint restoration technology. Considering the operability, simplicity, economy, and forward-looking of the joint restoration system And without disturbing the existing electric restoration, the microwave heating method is a reasonable choice. In recent years, microwave technology, as a new contaminated soil remediation technology, has attracted widespread attention. Microwave is used for soil remediation, not only can deal with volatile and semi-volatile organic compounds, such as halogenated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, etc., but also non-volatile substances such as heavy metals. Microwave heating can heat the inside and outside of the heated substance together, the heating is extremely fast, and the heat loss is small and the thermal efficiency is high. It has high efficiency, quickness, flexible operation, small impact on the environment, wide application range and selective heating when thermally remediating polluted soil, and can separate and recover some useful components. At present, some people have done research on microwave remediation of organic solvents, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and heavy metals in soil, and the treatment effect is good. However, most of the research focuses on the ex-situ remediation of contaminated soil by microwave, focusing on the experimental research on the effect and mechanism of remediation of contaminated soil, without discussing the systematic and industrialization of remediation technology. Therefore, in view of the fact that the above two methods can deal with heavy metals and organic pollutants, and the focus of their treatment objects is complementary, they can complement each other and be applied to soil in-situ joint restoration.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the existing electrodynamic restoration and soil thermal restoration technologies, combine and strengthen the two, and propose a microwave electrodynamic soil in-situ treatment technology, which uses electrodynamic restoration and microwave heating combined restoration technology in the early stage For some organic pollutants and heavy metals in the soil, high-temperature microwave soil thermal remediation technology is used in the later stage to deal with organic pollutants and residual heavy metals that are difficult to volatilize and degrade. It has the advantages of short repair time, good repair effect, can deal with heavy metal and organic compound-contaminated soil, and the process is simple and easy to operate.

A microwave electric soil in-situ restoration device is composed of three parts: an electrode system, a microwave heating system, and a groundwater circulation system.

1. The electrode system consists of anode and cathode electrode wells composed of graphite distributed at both ends of the treated soil area, and the electrodes are filled with electrolyte.

2. The microwave heating system consists of a gas-gathering shed installed above the treated soil area, a microwave radiator, and microwave-absorbing materials buried in the soil.

3. The groundwater circulation treatment system consists of pumping wells, water injection wells and vacuum pumps distributed around the treated soil area.

A microwave electrokinetic soil repair method in situ, the method steps are:

1) Start the centrifugal pump to pump out an appropriate amount of groundwater and slowly inject it into the soil layer of the treated soil to maintain a certain amount of water in the soil.

2) Start the power supply system and turn on the electric power repair system. Positively charged ions (especially heavy metal ions) present in the soil move towards the cathode, enriching the area near the cathode; negatively charged ions move towards the anode, enriching the area near the anode , to achieve the purpose of removing pollutants in the soil. At the same time, the pH monitoring system installed in the electrode well is turned on to monitor the pH change of the electrode solution, so as to add acid or alkali to the electrode solution to adjust the pH.

3) At the same time, turn on the microwave radiator above the soil to radiate the microwave into the depth of the soil, and the soil is slowly heated to a certain temperature. At this time, microwave heating and electrodynamic restoration are carried out simultaneously. Because there are microwave absorbing materials buried in the soil in advance, and the soil also contains a certain amount of water injected from the groundwater, the microwave is absorbed faster and better, and the soil is heated evenly and rapidly. At the same time, the temperature monitoring device buried in the soil is turned on to monitor the temperature rise of the soil.

4) When the soil temperature is around 100°C, the volatile organic compounds and semi-volatile organic compounds in the soil begin to mix with water vapor and be volatilized out of the soil, and the mixed gas moves upwards and enters from the gas collection port installed in the gas collection shed and the connecting pipes Multistage distillation unit. The organic matter is recycled through multi-stage distillation, and the fractionated water is reinjected into the groundwater through connecting pipes to maintain the hydraulic balance of the groundwater.

5) When the temperature in the soil is higher than 200°C, stop the electrodynamic repair system and continue to irradiate the soil with microwaves to make the soil continue to heat up. Pollutants, especially organic matter and heavy metal ions, entered the interlayer of soil clay mineral lattice and were fixed, and were further wrapped by vitrified soil, and finally fixed in the soil.

The pH automatic monitoring system in step 2) consists of a digital industrial pH meter and a single-channel peristaltic pump. The switch of the peristaltic pump is controlled by the threshold value set on the pH meter. In the process of electrodynamic restoration, once the pH value measured by the pH meter exceeds the set critical value, the connected peristaltic pump starts to work, releasing acid or alkali solution to neutralize the OH- and H+ produced by electrolysis, until The peristaltic pump stops when the pH value measured by the acidity meter returns to the set range.

The microwave absorbing material buried in the soil in step 3) is carbon particles, carbon rods, graphite or magnetic nanoparticles. Since the present invention uses electrodynamic restoration technology, it is not considered to embed microwave absorbing materials such as metal rods in the soil, so as not to affect the electric field distribution and the moving direction of pollutants in electrodynamic restoration.

The temperature monitoring device installed in the soil in step 3) is composed of a temperature sensor and an alarm. When the temperature in the soil exceeds 200°C, an alarm signal will be issued, and the electric restoration device will stop working.

The gas collection shed for collecting gas in step 4) is built around and above the entire treated soil to form a closed space, so that the volatilized organic matter enters the multi-stage distillation device for further processing through the gas collection port.

The advantages of the present invention are:

1) This technology introduces a groundwater circulation device to pump out the groundwater in the treatment area and inject it into the contaminated soil, so as to promote the movement of charged particles in the soil during electrodynamic restoration. Not only that, the water quickly absorbs microwaves and becomes a heat source, which makes the soil heated by microwaves more quickly and evenly. As the volatile organic compounds are evaporated, the water is injected back into the groundwater through multi-stage distillation, maintaining the hydraulic balance of the groundwater.

2) Install the air-gathering shed in the upper space of the treated area to form a closed space above the polluted soil, which isolates the polluted soil from the external environment and reduces the risk of contamination of the external environment. And use the gas collection shed to collect the volatilized organic matter and purify and recycle it, saving resources and not causing waste.

3) Microwave radiation increases the soil temperature, and the increase in soil temperature promotes the migration speed of charged particles in the electric field during electrokinetic restoration, speeding up the electrokinetic restoration process.

4) Compared with the previous technology, the joint enhanced repair technology of electrodynamic repair and microwave radiation has greatly shortened the repair period and has excellent repair effect. The removal rate of organic matter has reached 98%, and the removal rate of heavy metals is also above 90%, which has high environmental and time benefits.

5) The technical equipment has compact structure, simple operation and high reliability, and has good promotion potential at home and abroad, especially for the compound soil pollution of heavy metals and organic matter, which has broad application prospects.

Description of drawings

Figure 1 is a schematic diagram of the structure of a microwave electrokinetic soil in-situ remediation device. Among them, 1-cathode well, 2-anode well, 3-cathode, 4-anode, 5-industrial digital pH meter, 6-peristaltic pump, 7-acid-base tank, 8-DC power supply, 9-microwave generator, 10 -Waveguide, 11-radiator, 12-microwave absorbing material, 13-pumping well, 14-injection well, 15-centrifugal pump, 16-temperature sensor, 17-gathering shed, 18-gathering port, 19-multistage Distillation device, 20-organic matter collection device, 21-water pipeline, 22-conductor, 23-underground water, 24-gas collection pipeline.

Fig. 2 is a flow chart of the microwave electrokinetic soil in-situ remediation method.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples.

Fig. 1 is a schematic diagram of the device of the present invention, as shown in Fig. 1, a kind of microwave electric soil repairing device in situ, this device comprises electrode system, microwave heating system, underground water circulation system, and concrete parts are as follows: 1-cathode well, 2-anode Well, 3-cathode, 4-anode, 5-industrial digital PH meter, 6-peristaltic pump, 7-acid-base tank, 8-DC power supply, 9-microwave generator, 10-waveguide, 11-radiator, 12- Microwave absorbing material, 13-pumping well, 14-water injection well, 15-centrifugal pump, 16-temperature sensor, 17-gas collection shed, 18-gas collection port, 19-multistage distillation device, 20-organic matter collection device, 21 -Water pipeline, 22-wire, 23-underground water, 24-gas collection pipeline. In the electrode system, the cathode well 1 and the cathode well 2 are placed vertically in the soil respectively, the cathode 3 is placed in the cathode well 1, the anode 4 is placed in the anode well 2, the positive pole of the DC power supply 8 is connected to the anode 4 through a wire 22, The negative pole is connected to the cathode 3, the cathode well 1 and the anode well 2 are connected through a peristaltic pump 6 and an acid-base tank 7, and an industrial digital pH meter 5 is placed in the cathode well 1 and the anode well 2 respectively. The groundwater circulation system includes a pumping well 13 and a water injection well 14 , and the pumping well 13 is connected to a water delivery pipeline 21 through a centrifugal pump 15 to extract polluted water from the groundwater 23 . In the microwave heating system, the microwave generator 9 is connected to the gas collection shed 17, the radiator 11 is connected to the 9 through the waveguide 10, the microwave absorbing material 12 and the temperature sensor 16 are buried in the soil, and the gas collection shed 17 is provided with a collection The gas port 18 is connected to the multi-stage distillation device 19 through the gas collection pipe 24, one end of the multi-stage distillation device is connected to the organic matter collection device 20, and the other end is connected to the water injection well 14 through the water delivery pipe 21 and then enters the groundwater 23.

A microwave electrodynamic soil repairing device and repairing method in situ, as shown in Figure 2, the method,

Pre-processing:

A gas-collecting shed 17 is built within the area of the treated soil, and a gas-collecting port 18 is installed on the top to form a closed space. Loosen the soil, and bury the microwave absorbing material 12 evenly in the soil. Install cathode 3 and anode 4 at both ends of the treated soil area, inject electrolyte, and install pH automatic monitoring device 5-7. Two wells are drilled at both ends of the treated soil to communicate with groundwater, one is a pumping well 13, and the other is connected to a multi-stage distillation device 19 as a water injection well 14, so that the groundwater circulates and maintains hydraulic balance.

The microwave emitting devices 9-11 are uniformly arranged directly above the soil space, so that the microwave can completely cover the treated contaminated soil. A temperature sensor 16 is inserted into the soil to monitor soil temperature changes.

The method steps are:

1. Start the centrifugal pump 15 to pump out an appropriate amount of groundwater from the pumping well 13 and slowly inject it into the soil layer of the treated soil to keep a certain amount of moisture in the soil.

2. Turn on the electrodynamic restoration devices 1-4, 8, 22 and the pH automatic monitoring devices 5-7. Positively charged ions (especially heavy metal ions) present in the soil move towards the cathode, enriching the area near the cathode; negatively charged ions move towards the anode, enriching the area near the anode , to achieve the purpose of removing pollutants in the soil. The industrial digital pH meter 5 in the electrode well 1-2 monitors the pH change of the electrode solution. When the pH meter detects that the pH of the electrolyte exceeds the set critical value, the switch of the single-channel peristaltic pump 6 is activated to allow the acid or alkali in the acid-base tank to flow into the electrode solution to adjust the pH until the pH returns to the set value. Level within the range, the single channel peristaltic pump stops working.

3. Simultaneously open the microwave radiators 9-11 above the soil to radiate microwaves deep into the soil, and the soil is slowly heated to a certain temperature. At this time, microwave heating and electrodynamic restoration are carried out simultaneously. Because there is the microwave absorbing material 12 buried in the soil in advance, and the soil also contains a certain amount of water injected from the groundwater, the microwave is absorbed faster and better, and the soil is heated evenly and rapidly. Simultaneously, the temperature sensor 16 buried in the soil is opened to monitor the temperature rise of the soil.

4. When the soil temperature is around 100°C, the volatile organic compounds and semi-volatile organic compounds in the soil begin to mix with water vapor and be volatilized out of the soil, and the mixed gas moves upwards from the gas collection port 18 installed in the gas collection shed 17 and the connection Line 24 enters multistage distillation unit 19 . The organic matter is recycled into the organic matter collection device 20 through multi-stage distillation, and the fractionated water enters the water injection well 14 through a connecting pipe and is reinjected into the groundwater to maintain the hydraulic balance of the groundwater.

5. When the temperature in the soil is higher than 200°C, stop the electrodynamic repair system and continue to irradiate the soil with microwaves to make the soil continue to heat up. Pollutants, especially organic matter and heavy metal ions, entered the interlayer of soil clay mineral lattice and were fixed, and were further wrapped by vitrified soil, and finally fixed in the soil.

Example 1:

Select a range of 5m*5m in the polluted soil containing Cd Zn Cu, benzene and acetone around the electroplating factory for treatment. The soil pollution depth is about 1.5m. The microwave absorbing material is evenly buried in this area, and a 5.3*5.3*2.3 gas-collecting shed, using PbO ₂ /Ti electrode as the anode, graphite as the cathode; electrolysis buffer using 0.5mol/L acetic acid-sodium acetate buffer solution with a pH value of 3; constant voltage 15V, the corresponding The electric field strength is 1.5V/cm, and the treatment time is set to 30h. Install a microwave emission device on the gas collection shed, place a temperature sensor in the contaminated area, and start processing. After the electrodynamic repair device is turned on, the positively charged ions in the soil will move to the cathode and concentrate in the area near the cathode, and the negatively charged ions will enrich in the anode area. When the pH exceeds the set critical value, use the acid or alkali in the acid-base tank to adjust the pH; when microwave heating, the volatile organic compounds, semi-volatile organic compounds and water vapor in the soil will volatilize the soil and pass through the air collection shed Enter the distillation unit. When the temperature of the soil exceeds 200° C., turn off the power supply of the electric restoration device and continue microwave heating. After the experiment, the atomic absorption instrument was used to measure the concentration of Cd Zn Cu ions in the soil. The results showed that the average removal rates of these three ions were above 85%. The extraction method was used to measure the content of organic matter. The results showed that the average removal rates of benzene and acetone Up to 90%, and the processing energy consumption is 8Kwh/m ³ .

Example 2

Select a range of 2.5m*3m in the polluted soil containing Ag, Cd, n-hexane, and xylene around the chemical plant for treatment. The soil pollution depth is about 1.2m, and the microwave absorbing material is evenly embedded in this area. A 2.8*3.8*2.3 gas-collecting shed is set above, and graphite plates are used as electrodes for the anode and cathode; citric acid-sodium citrate buffer solution with a pH value of 6 is used as the electrolytic buffer solution; the constant voltage is 2V, and the corresponding electric field strength is 0.2 V/cm, the treatment time is 60h. Install a microwave emission device on the gas collection shed, place a temperature sensor in the contaminated area, and start processing. After the electrodynamic repair device is turned on, the positively charged ions in the soil will move to the cathode and be enriched in the area near the cathode, and the negatively charged ions will move to the anode and be enriched in the area near the anode. When the pH exceeds the set critical value, use the acid or alkali in the acid-base tank to adjust the pH; when microwave heating, the volatile organic compounds, semi-volatile organic compounds and water vapor in the soil will volatilize the soil and pass through the air collection shed Enter the distillation unit. When the temperature of the soil exceeds 200° C., turn off the power supply of the electric restoration device and continue microwave heating. After the experiment, the atomic absorption instrument was used to measure the concentration of Ag and Cd ions in the soil. The results showed that the average removal rate of these two kinds of ions reached more than 88.3%. The removal rate is over 89%, and the treatment energy consumption is 6Kwh/m ³ .

Example 3

Select a range of 2m*2m in the polluted soil containing Pb, Cd, phenols, aldehydes, and organic amines around the battery factory for treatment. The soil pollution depth is about 1.0m. Make a basic measurement of the target pollutant content in this area, and then Evenly embed microwave absorbing materials in this area, set up a 2.5*2.5*1.5 gas collection shed above the polluted area, use graphite plates as electrodes for both cathode and anode; use 0.5mol/L electrolytic buffer solution with a pH value of 3 The acetic acid-sodium acetate buffer solution; the constant voltage is 12V, the corresponding electric field strength is 1.2V/cm, and the treatment time is set to 24h. Install a microwave emission device on the gas collection shed, place a temperature sensor in the contaminated area, and start processing. After the electrodynamic repair device is turned on, the positively charged ions in the soil will move to the cathode and concentrate in the area near the cathode, and the negatively charged ions will enrich in the anode area. When the pH exceeds the set critical value, use the acid or alkali in the acid-base tank to adjust the pH; when microwave heating, the volatile organic compounds, semi-volatile organic compounds and water vapor in the soil will volatilize the soil and pass through the air collection shed Enter the distillation unit. When the temperature of the soil exceeds 200° C., turn off the power supply of the electric restoration device and continue microwave heating. After the experiment, the atomic absorption instrument was used to measure the concentration of Pb and Cd ions in the soil. The results showed that the average removal rate of these three ions reached more than 80%. The average removal rate of organic amines is over 85%, and the treatment energy consumption is 7.2Kwh/m ³ .

The invention introduces an underground water circulation device, pumps out the ground water in the treatment area and injects it into the polluted soil, and promotes the movement of charged particles in the soil during electrodynamic restoration. Not only that, the water quickly absorbs microwaves and becomes a heat source, which makes the soil heated by microwaves more quickly and evenly. As the volatile organic compounds are evaporated, the water is injected back into the groundwater through multi-stage distillation, maintaining the hydraulic balance of the groundwater. The air-gathering shed is installed in the upper space of the treated area to form a closed space above the polluted soil, which isolates the polluted soil from the external environment and reduces the risk of contamination of the external environment. And use the gas collection shed to collect the volatilized organic matter and purify and recycle it, saving resources and not causing waste. Microwave radiation increases the soil temperature, and the increase in soil temperature promotes the migration speed of charged particles in the electric field during electrokinetic restoration, speeding up the electrokinetic restoration process. Compared with the previous technology, the joint enhanced repair technology of electrodynamic repair and microwave radiation has greatly shortened the repair period and has excellent repair effect. The removal rate of organic matter has reached 98%, and the removal rate of heavy metals is also above 90%, which has high environmental and time benefits. The device of the invention has the advantages of compact structure, simple operation and high reliability, and has good popularization potential both at home and abroad, especially for compound soil pollution of heavy metals and organic matter, which has broad application prospects.

Claims (6)

1. A microwave electric soil repairing device in situ is characterized in that the device comprises three parts: an electrode system, a microwave heating system, and a groundwater circulation system; The electrode system consists of anodic and cathodic electrode wells composed of graphite distributed at both ends of the soil area to be treated, containing an electrolyte in the electrodes; The microwave heating system includes a gas collection shed installed above the treated soil area, microwave radiators and microwave absorbing materials buried in the soil; The groundwater circulation treatment system consists of pumping wells, water injection wells and vacuum pumps distributed around the treated soil area. the 2. A microwave electric soil in-situ remediation device according to claim 1, characterized in that the device includes a cathode well (1), an anode well (2), a cathode (3), an anode (4), an industrial digital PH meter (5), peristaltic pump (6), acid-base tank (7), DC power supply (8), microwave generator (9), waveguide (10), radiator (11), microwave absorbing material (12), Pumping well (13), water injection well (14), centrifugal pump (15), temperature sensor (16), gas collection shed (17), gas collection port (18), multi-stage distillation device (19), organic matter collection device ( 20), water pipeline (21), wire (22), groundwater (23), gas collection pipeline (24); Build a gas-gathering shed (17) within the area where the soil needs to be treated, and a gas-gathering port (18) is installed on the upper part of the gas-gathering shed (17), forming a closed space; The cathode well (1) and the cathode well (2) are placed vertically in the soil respectively, the cathode (3) is placed in the cathode well (1), the anode (4) is placed in the anode well (2), and the DC power supply (8) The positive pole is connected to the anode (4) through a wire (22), the negative pole of the DC power supply (8) is connected to the cathode (3), and both the cathode well (1) and the anode well (2) pass through the peristaltic pump (6) and the acid-base tank ( 7) Connect, place industrial digital pH meter (5) in cathode well (1) and anode well (2) respectively; Described pumping well (13) is connected with water pipeline (21) by centrifugal pump (15) and extracts polluted water from groundwater (23); The microwave generator (9) is connected to the gas collection shed (17), the radiator (11) is connected to the microwave generator (9) through the waveguide (10), and the microwave absorbing material (12) and the temperature sensor (16) are buried in the soil ), the gas collection port (18) on the gas collection shed (17) is connected to the multi-stage distillation device (19) through the gas collection pipe (24), one end of the multi-stage distillation device (19) is connected to the organic matter collection device (20), and the other One end is connected to the water injection well (14) through the water pipeline (21) and then enters the groundwater (23). the 3. Utilize a kind of microwave electrokinetic soil in-situ remediation method of a kind of microwave electrokinetic soil in-situ remediation device as claimed in claim 2, it is characterized in that, the method step is: 1) Start the centrifugal pump (15) to extract groundwater from the pumping well (13) and slowly inject it into the soil layer of the treated soil to keep moisture in the soil; 2) Turn on the cathode well (1), anode well (2), cathode (3), anode (4), industrial digital pH meter (5), peristaltic pump (6), acid-base tank (7), DC power supply (8 ). Positively charged ions present in the soil, especially heavy metal ions, will move to the cathode and be enriched to the area near the cathode; negatively charged ions will move to the anode and be enriched to the area near the anode to remove the soil The purpose of pollutants in the medium; the industrial digital pH meter (5) in the cathode well (1) and the anode well (2) monitors the pH change of the electrode solution, when the industrial digital pH meter (5) detects that the pH of the electrolyte exceeds the setting When the critical value is reached, start the switch of the single-channel peristaltic pump (6), so that the acid or alkali in the acid-base tank flows into the electrode solution to adjust the pH, until the pH returns to the set range, the single-channel peristaltic pump stops working; 3) Simultaneously turn on the microwave generator (9), waveguide (10) and radiator (11) above the soil to radiate microwaves deep into the soil, and the soil is slowly heated to a certain temperature; at this time, microwave heating and electric power Restoration is carried out at the same time; due to the microwave absorbing material (12) buried in the soil in advance, and the soil also contains water injected from the groundwater, the microwave is absorbed faster and better, so that the soil is heated evenly and rapidly; at the same time open A temperature sensor (16) buried in the soil monitors the temperature rise of the soil; 4) When the soil temperature is around 100°C, the volatile organic compounds and semi-volatile organic compounds in the soil begin to mix with water vapor and be volatilized out of the soil, and the mixed gas moves upward from the gas collection port installed in the gas collection shed (17) ( 18) and the connecting pipeline (24) enters the multi-stage distillation device (19); the organic matter is recycled into the organic matter collection device (20) through multi-stage distillation, and the fractionated water enters the water injection well (14) through the connecting pipe and is reinjected into the groundwater To maintain the hydraulic balance of groundwater; 5) When the temperature in the soil is higher than 200°C, stop the electrodynamic restoration system and continue to irradiate the soil with microwaves to make the soil continue to heat up; pollutants, especially organic matter and heavy metal ions, enter the interlayer of the soil clay mineral lattice and are destroyed. Fixed, and further wrapped in vitrified soil, finally fixed in the soil. the 4. A microwave electrokinetic in-situ repair method for soil according to claim 3, characterized in that the switch of the peristaltic pump is controlled by the critical value set on the industrial digital pH meter (5), during the repair process , once the industrial digital pH meter (5), the measured pH value exceeds the set critical value, the connected peristaltic pump will start to work, releasing acid or alkali solution to neutralize the OH- and H ⁺ produced by electrolysis, The peristaltic pump does not stop until the pH value measured by the acidity meter returns to the set range. 5. A microwave electrokinetic soil in-situ remediation method according to claim 3, characterized in that the microwave absorbing material embedded in the soil is carbon particles, carbon rods, graphite or magnetic nanoparticles. the 6. A microwave electrodynamic soil in-situ restoration method according to claim 3, characterized in that the temperature monitoring device installed in the soil is composed of a temperature sensor and an alarm, and when the temperature in the soil exceeds 200°C An alarm signal will be sent, at this moment the repair device will stop working. the

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