In-situ purification integrated device for VOCs in underground water and application method

Abstract

The invention discloses an in-situ purification integrated device for VOCs in underground water and an application method, and relates to the technical field of in-situ remediation of soil and underground water. The device comprises an in-situ gas stripping-aeration-medicament adding integrated pneumatic pump, an underground water extraction well, a medicament adding pipe, a ground medicament adding device, a pneumatic pump access pipe, a ground tail gas treatment device, a fan and a gas phase extraction device. The in-situ gas stripping-aeration-medicament adding integrated pneumatic pump is connected with the ground tail gas treatment device, so that the tail gas is recycled in the system, the high dependence on a tail gas treatment process is reduced, the equipment operation maintenance and detection cost is reduced, the tail gas is circulated in the system, the tail gas is prevented from being directly discharged to the outside, and the environment pollution is reduced. The potential pollution risk to the surrounding environment is greatly reduced, the environment-friendly underground water purification process is achieved, and the probability of occurrence of environmental problems and related environmental events caused by tail gas emission is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ remediation of soil and groundwater, and in particular to an integrated device for in-situ purification of VOCs in groundwater and an application method thereof. Background Art

[0002] When faced with underground aquifers polluted by organic matter, especially those polluted by volatile organic pollutants (VOCs) such as petroleum hydrocarbons, chlorinated hydrocarbons, and benzene, groundwater extraction treatment and groundwater aeration treatment technologies in situ treatment technologies are widely used due to their significant treatment effects and economic advantages.

[0003] The groundwater extraction and treatment technology arranges groundwater extraction wells in the target aquifer, uses water pumps to extract contaminated groundwater to the ground, and then uses various treatment technologies to purify it before use or re-introducing it into the ground. Among them, the air blowing + activated carbon adsorption process is widely used in the sewage treatment process after extraction in the groundwater extraction and treatment process. For example, patent CN118652016B discloses a contaminated groundwater extraction and treatment equipment and treatment process, and its treatment equipment includes a base and an extraction component, a stripping and deodorization component and an electrocatalytic oxidation component arranged on the base. The extraction component is responsible for extracting the sewage gathered in the underground well into the inside of the stripping and deodorization component. The stripping and deodorization component converts the odor pollutants in the sewage into the gas phase and discharges it from the equipment. The electrocatalytic oxidation component oxidizes and decomposes pollutants such as benzene, carbon tetrachloride, chlorobenzene, chloroform, 4-chlorodiphenyl ether in the sewage into small molecules, so that the pollutants are discharged from the equipment, thereby realizing the extraction and treatment of contaminated groundwater. The equipment structure of this invention is reasonably designed, which can effectively remove odorous substances in sewage and prevent groundwater pollution from further deteriorating the surrounding environment. At the same time, it uses electrocatalytic oxidation components to oxidize and decompose specific pollutants, thereby improving the safety of sewage discharge.

[0004] As an in-situ remediation technology for organic pollution in soil and groundwater, groundwater aeration technology injects pressurized air below the saturated aquifer to convert organic pollutants into volatile pollutants through interphase mass transfer (dissolution, volatilization, desorption, biodegradation, etc.), and migrates to the aeration zone with the airflow, and then is collected by other pumping devices to the surface gas treatment equipment. The early groundwater aeration technology required a certain number of pumping wells to be arranged in the aeration zone above the saturated layer to collect and treat the organic vapor generated by groundwater aeration, and its application scenarios were greatly limited by formation conditions. In order to improve adaptability, an in-well aeration method was developed after improvement, that is, after the groundwater flows into the well and is blown off and aerated in the well, the volatilized vapor is extracted by a negative pressure fan and enters the tail gas treatment device on the ground for treatment, and the initially purified groundwater is further transferred with the groundwater around the well through concentration gradient and other effects. For example, invention patent CN109047302B discloses an in-situ aeration remediation method for VOCs-contaminated groundwater in low permeability areas. Based on the surfactant-enhanced aeration remediation method, the method uses point-adjustable hydraulic fracturing technology to perform multi-point hydraulic fracturing on the low permeability contaminated area, generating a large number of artificial cracks in the area. At the same time, the pressure solution used for fracturing is a surfactant solution, which enhances the gas permeability of the low permeability contaminated area and the desorption capacity of pollutants from fine-grained soil, effectively solving the problem that low permeability contaminated areas are difficult to repair. It is based on traditional groundwater aeration and adopts hydraulic fracturing technology to coordinate with the strengthening effect of surfactants to enhance the desorption of pollutants in low permeability formations and improve the treatment effect.

[0005] However, although the above inventions have improved the application effects of groundwater extraction + aeration and groundwater in-situ aeration technology in the field of groundwater remediation to a certain extent, they all have the problem of qualified exhaust gas emissions. In the above remediation process, the exhaust gas treatment device cannot realize the internal circulation of the gas system, and the polluted gas needs to be discharged after being treated by the exhaust gas treatment device. This requires that the exhaust gas must meet the relevant emission standards before it can be discharged in compliance with the standards, which puts forward higher requirements on the exhaust gas treatment process and increases the cost of equipment operation, maintenance and testing. Therefore, it is necessary to propose an integrated device and application method for in-situ purification of VOCs in groundwater to solve the problems in the prior art. Summary of the invention

[0006] The purpose of the present invention is to make up for the shortcomings of the prior art and to provide an integrated device for in-situ purification of VOCs in groundwater and an application method, which can realize the recycling of tail gas, reduce the high dependence on tail gas treatment technology, reduce the equipment operation and maintenance and detection costs, avoid direct discharge of tail gas to the outside, and greatly reduce the potential pollution risk to the surrounding environment.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: an integrated device for in-situ purification of VOCs in groundwater, the device comprising an integrated pneumatic pump for in-situ gas lift-aeration-drug dosing, a groundwater extraction well, a drug dosing pipe, a ground drug dosing device, a pneumatic pump access pipe, a ground tail gas treatment device, a fan and a gas phase extraction device, the in-situ gas lift-aeration-drug dosing integrated pneumatic pump is gas driven, and its air inlet end is connected to the fan through a pipeline, the fan is connected to the ground tail gas treatment device through a pipeline, and is used to receive the treated tail gas as a power source, one end of the drug dosing pipe is connected to the ground drug dosing device, and the other end of the drug dosing pipe is connected to the in-situ gas lift-aeration-drug dosing device. The agent dosing integrated pneumatic pump is connected, the agent dosing acceleration rate is controlled by the opening and closing size of the electromagnetic valve in the ground agent dosing device, and the control signal of the electromagnetic valve is generated and transmitted by a computer program, the pneumatic pump access pipe is connected to the in-situ air lift-aeration-agent dosing integrated pneumatic pump, the pneumatic pump access pipe is connected to the high-temperature air source, and the pneumatic pump access pipe is provided with a flow regulating valve, the ground tail gas treatment device is connected to each extraction well pipe through a pipeline, an activated carbon adsorption tank is provided inside, the activated carbon adsorption tank is filled with columnar activated carbon, and the particle size is 3-5mm, and the gas treated by it can be pressurized and heated by a fan and then pumped back into the in-situ air lift-aeration-agent dosing integrated pneumatic pump.

[0008] Furthermore, an air access end is provided at the bottom end of the in-situ air lift-aeration-agent dosing integrated pneumatic pump, and a negative pressure suction section, a throat gradient section and a high-pressure jet mixing section are sequentially provided inside the in-situ air lift-aeration-agent dosing integrated pneumatic pump from bottom to top; a liquid phase suction port is provided on the outer surface of the in-situ air lift-aeration-agent dosing integrated pneumatic pump, and the liquid phase suction port is communicated with the negative pressure suction section; a pipeline connector 1 is installed at the left end of the in-situ air lift-aeration-agent dosing integrated pneumatic pump, and the pipeline connector 1 is connected to the agent dosing pipe; a pipeline connector 2 is installed at the bottom end of the air access end, and the pipeline connector 2 is connected to the pneumatic pump access pipe; a one-way valve is provided inside the pipeline connector 1, and the one-way valve allows the agent to flow into the mixing chamber in one direction, so as to prevent the gas-liquid mixture in the mixing chamber from flowing back to the agent dosing pipe.

[0009] Furthermore, the groundwater extraction well is a double-layer special stainless steel well pipe, the inner layer is a 304 stainless steel slit pipe, the slits are spirally distributed and the slit width is 0.1-0.5mm, and the outer layer is a stainless steel wire mesh structure. The two layers are filled with gravel and quartz sand with a particle size of 2-3mm. An intermediate barrier is provided in the middle position of the groundwater extraction well, which divides the well pipe into two parts, the upper and lower parts, the intermediate barrier is made of rubber and fits tightly to the inner wall of the well pipe, the integrated pneumatic pump is installed in the lower layer of the well pipe, and a filter is provided on the upper layer of the groundwater extraction well. The filter is made of stainless steel and has a mesh diameter of 0.1-0.5mm, and the filter is connected to the gas phase extraction device 8 through a pipeline.

[0010] Furthermore, the thickness of the intermediate barrier is 5-10cm, and annular sealing grooves are provided on the upper and lower surfaces thereof respectively, and sealing rings are installed in the sealing grooves. The thickness of the filter is 10-15cm, and the filter is made of multiple layers of stainless steel wire mesh, and the mesh diameter of each layer of wire mesh gradually decreases from close to the inside of the well pipe to the outside.

[0011] Furthermore, an anti-corrosion protective layer is provided on the outside of the groundwater extraction well, and the anti-corrosion protective layer is an epoxy resin coating with a thickness of 0.5-1.5 mm.

[0012] An application method of an integrated device for in-situ purification of VOCs in groundwater, the method comprising the following steps:

[0013] Start the fan and gas phase extraction device to extract the volatilized polluted gas in the groundwater to the surface tail gas treatment device. The treated tail gas is pressurized and heated by the fan and then transported to the in-situ gas extraction-aeration-agent dosing integrated pneumatic pump as a power source. At the same time, the automatic pressure replenishment device of the fan extraction pipeline extracts ambient air at startup, automatically closes after the air volume is balanced, and starts the tail gas internal circulation. During the stage of extracting ambient air, the fan speed is 1000-1500rpm. When switched to the tail gas internal circulation, the fan speed is adjusted to 800-1200rpm;

[0014] High-pressure gas enters the pneumatic pump to generate negative pressure, and the groundwater in the lower layer of the groundwater extraction well is extracted to the upper layer through the air extraction pipe. The groundwater is mixed with the gas at high speed in the pump body and then ejected from the nozzle at high speed to achieve aeration in the well. At the same time, the filter on the upper layer of the well pipe intercepts water vapor, and the pollutants are volatilized and extracted by the exhaust device and then enter the tail gas treatment device for circulation treatment. The water circulates under gravity and slightly positive pressure. During the aeration process in the well, the gas flow rate of the pneumatic pump is adjusted to make the rising flow rate of the water in the well 1-3m / s;

[0015] According to the repair needs, the repair agent is prepared in the ground agent dosing device, and the agent dosing acceleration rate is adjusted by controlling the opening and closing size of the solenoid valve. The agent dosing can be carried out simultaneously with aeration, that is, the agent is injected into the pneumatic pump through the dosing pipe under the action of negative pressure, mixed with groundwater and air, and then sprayed out and seeped back into the original formation under the action of hydraulic and air pressure to achieve agent dosing and mixing. When carried out simultaneously, the ratio of the agent flow rate in the agent dosing pipe to the gas flow rate in the pneumatic pump is 1:5-1:10. It can also be carried out separately, that is, the valve between the exhaust device and the pneumatic pump is closed, and the fan draws ambient air into the well to lift the groundwater and the agent pump to the upper screen pipe section, and then quickly discharges it under pressure to accelerate the agent dosing. When carried out separately, the flow rate of ambient air drawn by the fan is 1.2-1.5 times the gas flow rate during normal exhaust gas circulation.

[0016] Furthermore, when aeration is carried out in the well, the amount of high-temperature air introduced is controlled by adjusting the flow regulating valve on the pneumatic pump access pipe to maintain the aeration temperature at 30-50°C and the temperature of the introduced high-temperature air at 100-200°C. During the circulation process, the groundwater stays in the aquifer for 2-5 hours after each aeration and circulation treatment, and after each circulation treatment, the VOCs concentration in the groundwater is detected. When the concentration drops below the set threshold, the purification treatment of the area is stopped.

[0017] Furthermore, during the process of adding the agent alone, when the agent is an oxidizing agent, the agent completes at least 1-2 cycles in the rock formation around the circulation well to ensure that the agent is added evenly and in sufficient quantity. When the agent is a reducing agent, an appropriate amount of acid regulator is added to the groundwater extraction well before addition to adjust the groundwater pH value to 3-5 to improve the reduction reaction efficiency. During the entire application process, the activated carbon adsorption tank in the ground exhaust treatment device is regularly regenerated with a regeneration cycle of 1-3 months and a regeneration method of hot air purging with a hot air temperature of 120-150°C and a purging time of 2-4 hours.

[0018] Furthermore, before starting the device, the strata around the groundwater extraction well are pretreated, including the injection of a cleaning agent. The cleaning agent uses a surfactant solution with a concentration of 0.5%-2%. During the application process, the groundwater level changes are monitored in real time, and the operating parameters of the fan and pneumatic pump are adjusted according to the water level changes. During the agent addition process, the appropriate agent type and addition sequence are selected according to the water quality and pollutant composition of the groundwater. When the water contains multiple VOCs pollutants, special agents for the main pollutants are added first, and then auxiliary agents are added.

[0019] Compared with the prior art, the integrated device for in-situ purification of VOCs in groundwater and its application method have the following beneficial effects:

[0020] 1. The present invention connects the in-situ gas lift-aeration-agent dosing integrated pneumatic pump with the ground exhaust gas treatment device, so that the exhaust gas purified by the exhaust gas treatment device is pressurized and heated by the fan and then pumped back into the pneumatic pump as a power source, thereby realizing the recycling of exhaust gas in the system, reducing the high dependence on the exhaust gas treatment process, thereby reducing the equipment operation, maintenance and testing costs. Since the exhaust gas circulates inside the system, it avoids directly discharging the exhaust gas to the outside, greatly reducing the potential pollution risk to the surrounding environment, realizing a more environmentally friendly groundwater purification process, meeting environmental protection requirements, and reducing the probability of environmental problems and related environmental events caused by exhaust gas emissions.

[0021] 2. The agent dosing pipe of the present invention is connected to the ground agent dosing device, so that during the repair process, the dosage of the agent can be accurately adjusted according to the actual conditions such as the degree of groundwater pollution and the characteristics of the aquifer to achieve precise repair. The agent addition can be carried out simultaneously with aeration. At this time, the agent is mixed with groundwater and air in the pipeline and then sprayed. Under the dual effects of hydraulic and air pressure, the agent is added and mixed under the action of hydraulic circulation. It can also be carried out separately. The fan draws ambient air into the well to pump the groundwater and the agent to the upper screen section and then quickly discharge it, thereby accelerating the agent addition process. This diversified addition mode can be flexibly selected according to actual repair needs, realizing the synergistic effect of aeration flushing and oxidation / reduction / microorganism treatment methods, and can provide more comprehensive and effective groundwater purification solutions for different pollution scenarios and repair goals.

[0022] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a schematic diagram of the overall structure of the integrated device for in-situ purification of VOCs in groundwater;

[0025] Figure 2 This is a schematic diagram of the structure of an in-situ air lift-aeration-drug dosing integrated pneumatic pump.

[0026] In the figure: 1. In-situ gas lift-aeration-drug dosing integrated pneumatic pump; 101. Air access end; 102. Negative pressure suction section; 103. Throat gradient section; 104. High-pressure jet mixing section; 105. Liquid phase suction port; 106. Pipeline connector 1; 107. Pipeline connector 2; 2. Groundwater extraction well; 201. Intermediate barrier; 202. Filter; 3. Drug dosing pipe; 4. Ground drug dosing device; 5. Pneumatic pump access pipe; 6. Ground exhaust gas treatment device; 7. Fan; 8. Gas phase extraction device. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1: Pumping aeration of groundwater

[0029] First, the device for in-situ purification of VOCs in groundwater is carefully assembled. The groundwater extraction well 2 uses a customized stainless steel double-layer well pipe. The slits of the internal 304 stainless steel slit pipe are carefully designed spirals, the width is strictly adjusted to 0.3mm, the slit spacing is accurately set to 8mm, the length is determined to be 10cm, and the adjacent slits are staggered at 45 degrees to ensure that groundwater can enter the extraction pipe efficiently and evenly. The external stainless steel wire mesh structure is tightly wrapped, and the middle of the two layers is filled with quartz sand with a particle size of 2.5mm that has been strictly screened and cleaned, which effectively prevents impurities from mixing into the groundwater. In order to improve the treatment effect, the middle barrier 201 is made of 5mm thick high-quality rubber material, which fits tightly with the inner wall of the well pipe. The annular sealing grooves on the upper and lower surfaces are installed with high-elasticity rubber sealing rings with a Shore hardness of 55 degrees to ensure the impermeability of the middle barrier 201 and perfectly separate the upper and lower parts of the well pipe. The upper filter 202 is made of 5mm thick stainless steel multi-layer wire mesh, and the mesh apertures are 0.5mm, 0.3mm, and 0.1mm from the inside to the outside, forming an effective aperture gradient, which can maximize the retention of high-speed sprayed water vapor and prevent water vapor from entering the exhaust treatment system.

[0030] Start the fan 7 and the gas phase extraction device 8. The initial speed of the fan 7 is set to 1200rpm. The polluted gas volatilized in the groundwater is extracted to the ground tail gas treatment device 6. The activated carbon adsorption tank in the ground tail gas treatment device 6 starts to work efficiently and strongly adsorbs and purifies the polluted gas. The filling particle size of the activated carbon adsorption tank is 4mm and has been specially activated and treated, with a specific surface area of ​​1200m 2 / g columnar activated carbon and a gas distribution plate is provided at the bottom. The vent holes are 3mm in diameter and arranged in a regular triangle. At the same time, the automatic pressure replenishment device of the fan 7 extraction pipeline extracts ambient air. When the system air volume passes through the installation on the pipeline, the accuracy is ±5m 3 After the air volume sensor monitors that the air volume reaches a balance, the ambient air extraction is automatically turned off, the speed of the fan 7 is adjusted to 1000rpm, and the exhaust gas internal circulation is started.

[0031] The exhaust gas treated by the ground exhaust treatment device 6 is pressurized to 0.3MPa by the booster fan 7, heated to 80°C, and then transported to the in-situ air lift-aeration-agent dosing integrated pneumatic pump 1. The high-pressure gas enters the pneumatic pump to generate negative pressure, and the groundwater in the lower layer of the groundwater extraction well 2 is extracted to the upper layer through the air lift extraction pipe. By adjusting the gas flow regulating valve of the pneumatic pump, the rising flow rate of the water in the well is accurately maintained at 1.5m / s.

[0032] The filter screen 202 on the upper layer of the well pipe intercepts the high-speed sprayed water vapor to prevent it from being sucked into the ground tail gas treatment device 6 by the gas phase extraction device 8. After the pollutants are volatilized, the air is pumped at a rate of 8m 3 / min, and the vacuum degree can reach -0.085MPa. The water is sucked away by an efficient vacuum pump into the exhaust gas treatment device for re-circulation treatment. Under the action of gravity and micro-positive pressure, the water seeps out from the upper screen pipe, migrates downward under the action of gravity, and enters the lower screen pipe under the action of water head, forming a stable cycle. The micro-positive pressure is monitored by a pressure sensor with an accuracy of ±0.01MPa set on the upper layer of the well pipe. In this process, the groundwater stays in the aquifer for 3 hours after each aeration and circulation treatment, so as to fully carry out mass transfer and pollutant removal. At the same time, multiple temperature sensors and water quality monitoring points with an accuracy of ±0.5℃ are set at different depths of the aquifer to monitor the temperature and water quality changes in real time, so as to adjust the operating parameters in time and accurately.

[0033] During operation, the groundwater level changes are accurately monitored in real time by installing a water level sensor with an accuracy of ±0.05m in the well. If the water level drops by more than 0.5m, the power of the fan 7 and the pneumatic pump is appropriately reduced to prevent excessive extraction of groundwater. At the same time, the VOCs concentration in the groundwater is regularly detected every 2 hours by gas chromatography to observe the purification effect. If the purification effect is found to be unsatisfactory, the gas flow rate, aeration temperature and other parameters of the pneumatic pump can be further optimized. For example, by adjusting the air intake pressure of the pneumatic pump to vary finely between 0.2-0.4MPa, or adjusting the aeration temperature to accurately adjust between 70-90℃, it is ensured that the groundwater purification reaches the expected goal. In addition, the connection status of each component of the device is checked every quarter, such as pressure testing the pipe joints to check the sealing performance, and checking the operating stability of the pneumatic pump every month to promptly discover and solve potential problems.

[0034] Through the above-mentioned precise device design and strict operation control, efficient groundwater aeration purification is achieved. The exhaust gas internal circulation system effectively reduces the operating cost and avoids the pollution of the environment by exhaust gas emissions. The stable groundwater circulation and optimized aeration process enable the VOCs in the aquifer to be continuously reduced, thus improving the groundwater quality. Accurate monitoring and adjustment measures ensure the stable operation of the system and extend the service life of the equipment, providing a reliable and cost-effective solution for in-situ groundwater purification.

[0035] Example 2: Adding reagents while aerating to achieve coordinated use of multiple technologies

[0036] According to the pollution situation of groundwater, choose appropriate remediation agent. When the main pollutant in the water is benzene, prepare an appropriate amount of potassium permanganate as an oxidizing agent and add it to the agent storage tank of the ground agent dosing device 4. The agent storage tank is made of stainless steel, and the inner wall is coated with high-quality anti-corrosion coating to prevent the agent from corroding the tank body. The storage tank is equipped with an agitator, and the agitator speed can be adjusted between 50-100rpm to ensure the uniformity of the agent. The metering pump in the ground agent dosing device 4 uses a high-precision metering pump with a flow accuracy of ±1%. It is connected to the agent storage tank and the agent dosing pipe 3, and the inlet of the agent dosing pipe 3 in the integrated pneumatic pump is located at the bottom of the gas and liquid mixing chamber. The stainless steel one-way valve and the polytetrafluoroethylene inclined baffle at the inlet form an anti-backflow structure that has been installed. The one-way valve has good sealing performance and the baffle surface is smooth to prevent the mixture from flowing back.

[0037] According to the steps of the first embodiment, the fan 7, the gas phase extraction device 8 and the ground exhaust gas treatment device 6 are started to make the system enter the exhaust gas internal circulation state, the speed of the fan 7 is stabilized at 1000rpm, and the pneumatic pump is ready to receive the power source to work.

[0038] When the agent and aeration are selected to be carried out simultaneously, the solenoid valve in the agent dosing device is started, and the opening and closing size of the solenoid valve is adjusted according to the computer program setting to make the ratio of the agent flow rate in the agent dosing pipe 3 to the gas flow rate in the pneumatic pump be 1:8. While the fan 7 extracts the polluted gas to the exhaust gas treatment device, the agent is injected into the pneumatic pump through the dosing pipe under the action of negative pressure. In the pneumatic pump, the agent is fully mixed with groundwater and air, and then the mixed gas-liquid mixture is sprayed out from the nozzle at a high speed. The sprayed agent, groundwater and air mixture seeps back to the original stratum under the dual action of hydraulic force and air pressure. Under the action of hydraulic circulation, efficient addition and mixing of the agent are achieved, and aeration treatment is carried out at the same time. In this process, the mixing time of the agent in the groundwater and air is not less than 10 minutes to ensure that the oxidation reaction is fully carried out. At the same time, multiple redox potential sensors with an accuracy of ±10mV are set at different positions to monitor the progress of the redox reaction so as to accurately adjust the agent dosage.

[0039] If the reagent is added separately, the valve between the exhaust device and the pneumatic pump is closed, and the fan 7 is started to extract ambient air. At this time, the speed of the fan 7 is increased to 1300rpm, and the groundwater and the reagent are pumped into the injection well to the upper screen pipe section. Then, under the action of pressure, the mixed reagent and groundwater are quickly discharged from the well pipe to accelerate the reagent addition process. When the reagent is a reducing agent, an appropriate amount of acid regulator is added to the groundwater extraction well 2 before addition, and the pH value change is monitored in real time through a pH sensor with an accuracy of ±0.1pH to ensure that the groundwater pH value is accurately adjusted to 4 to improve the efficiency of the reduction reaction.

[0040] During the coordinated treatment of reagent addition and aeration, the online monitor is continuously used to monitor the changes in VOCs concentration in groundwater, and the changes in reagent concentration and system operating parameters are monitored through chemical analysis. According to the monitoring results, the reagent dosage, aeration intensity and other parameters are adjusted in time to achieve the best purification effect. For example, if it is found that the VOCs concentration in a certain area decreases slowly, the reagent dosage can be appropriately increased or the aeration temperature can be increased. The flow regulating valve on the pneumatic pump access pipe 5 is adjusted to control the access amount of high-pressure steam or high-temperature air to maintain the aeration temperature at 40°C. When high-pressure steam is connected, the steam pressure is 0.3MPa, and when high-temperature air is connected, the air temperature is 150°C.

[0041] Check the sealing performance of the pneumatic pump every six months, check the blockage of the filter 202 every month, and test the adsorption effect of the activated carbon adsorption tank every two months. After the system has been running for a period of time, conduct a comprehensive inspection of all components of the device, and replace worn or failed components in time according to the inspection results to ensure the long-term stable operation of the system and achieve effective purification of groundwater. At the same time, during the whole process, closely observe whether there are abnormal changes in the surrounding environment, such as soil color, odor, etc., to ensure that the system operation is environmentally friendly and does not produce secondary pollution. In addition, conduct long-term tracking monitoring of the treated groundwater to evaluate the durability of the repair effect.

[0042] This embodiment achieves efficient coordination of aeration and chemical treatment through precise control of chemical addition and diversified addition modes. The combined application of multiple chemicals and treatment technologies enhances the ability to handle complex pollution and adapts to a wider range of groundwater pollution scenarios. Strict system monitoring and maintenance measures ensure the long-term stable operation of the system. While effectively purifying groundwater, it is environmentally friendly and has a long-lasting restoration effect, providing a flexible, efficient and sustainable solution for groundwater restoration.

[0043] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the same elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An integrated device for in-situ purification of VOCs in groundwater, characterized in that: The device comprises an in-situ air lift-aeration-agent dosing integrated pneumatic pump (1), a groundwater extraction well (2), an agent dosing pipe (3), a ground agent dosing device (4), an air pump access pipe (5), a ground tail gas treatment device (6), a fan (7) and a gas phase extraction device (8). The in-situ air lift-aeration-agent dosing integrated pneumatic pump (1) is gas driven, and its air inlet end is connected to the fan (7) through a pipeline. The fan (7) is connected to the ground tail gas treatment device (6) through a pipeline and is used to receive the treated tail gas as a power source. One end of the agent dosing pipe (3) is connected to the ground agent dosing device (4), and the other end of the agent dosing pipe (3) is connected to the in-situ air lift-aeration-agent dosing integrated pneumatic pump (1). The agent injection rate is controlled by the opening and closing size of the electromagnetic valve in the ground agent injection device (4), and the control signal of the electromagnetic valve is generated and transmitted by a computer program. The pneumatic pump access pipe (5) is connected to the in-situ air lift-aeration-agent injection integrated pneumatic pump (1), and the pneumatic pump access pipe (5) is connected to the high-temperature air source, and a flow regulating valve is provided on the pneumatic pump access pipe (5). The ground tail gas treatment device (6) is connected to each extraction well pipe through a pipeline, and an activated carbon adsorption tank is provided inside the ground tail gas treatment device (6). The activated carbon adsorption tank is filled with columnar activated carbon with a particle size of 3-5 mm, and the gas treated by the activated carbon adsorption tank can be pressurized and heated by a fan (7) and then pumped back into the in-situ air lift-aeration-agent injection integrated pneumatic pump (1).

2. The integrated device for in-situ purification of VOCs in groundwater according to claim 1, characterized in that: The bottom end of the in-situ air lift-aeration-drug dosing integrated pneumatic pump (1) is provided with an air access end (101), the interior of the in-situ air lift-aeration-drug dosing integrated pneumatic pump (1) is provided with a negative pressure suction section (102), a throat gradient section (103) and a high-pressure jet mixing section (104) in sequence from bottom to top, the outer surface of the in-situ air lift-aeration-drug dosing integrated pneumatic pump (1) is provided with a liquid phase suction port (105), and the liquid phase suction port (105) is connected to the negative pressure suction section (102), and the in-situ air lift-aeration-drug dosing integrated pneumatic pump (1) is provided with a liquid phase suction port (105). A pipeline connector 1 (106) is installed at the left end of the aeration-medicament dosing integrated pneumatic pump (1), and the pipeline connector 1 (106) is connected to the reagent dosing pipe (3). A pipeline connector 2 (107) is installed at the bottom end of the air access end (101), and the pipeline connector 2 (107) is connected to the pneumatic pump access pipe (5). A one-way valve is arranged inside the pipeline connector 1 (106), and the one-way valve allows the reagent to flow into the mixing chamber in one direction, so as to prevent the gas-liquid mixture in the mixing chamber from flowing back to the reagent dosing pipe (3).

3. The integrated device for in-situ purification of VOCs in groundwater according to claim 1, characterized in that: The groundwater extraction well (2) is a stainless steel double-layer special well pipe, the inner layer is a 304 stainless steel slotted pipe, the slots are spirally distributed and the slot width is 0.1-0.5 mm, and the outer layer is a stainless steel wire mesh structure. The middle of the two layers is filled with crushed stone and quartz sand with a particle size of 2-3 mm. An intermediate blocker (201) is provided in the middle of the groundwater extraction well (2) to divide the well pipe into upper and lower parts. The intermediate blocker (201) is made of rubber and fits tightly to the inner wall of the well pipe. The integrated pneumatic pump is installed in the lower layer of the well pipe. A filter screen (202) is provided in the upper layer of the groundwater extraction well (2). The filter screen (202) is made of stainless steel and has a mesh size of 0.1-0.5 mm. The filter screen (202) is connected to the gas phase extraction device (8) through a pipeline.

4. The integrated device for in-situ purification of VOCs in groundwater according to claim 3, characterized in that: The thickness of the intermediate barrier (201) is 5-10 cm, and an annular sealing groove is provided on its upper and lower surfaces respectively, and a sealing ring is installed in the sealing groove. The thickness of the filter (202) is 10-15 cm, and the filter (202) is formed by stacking multiple layers of stainless steel wire mesh, and the mesh aperture of each layer of wire mesh gradually decreases from the inside of the well pipe to the outside.

5. The integrated device for in-situ purification of VOCs in groundwater according to claim 1, characterized in that: The outside of the groundwater extraction well (2) is provided with an anti-corrosion protective layer, which is an epoxy resin coating with a thickness of 0.5-1.5 mm.

6. The application method of the integrated device for in-situ purification of VOCs in groundwater is characterized by: The method comprises the following steps: The fan (7) and the gas phase extraction device (8) are started to extract the polluted gas volatilized in the groundwater to the surface tail gas treatment device (6). The treated tail gas is pressurized and heated by the fan (7) and then transported to the in-situ gas extraction-aeration-drug dosing integrated pneumatic pump (1) as a power source. At the same time, the automatic pressure replenishment device of the extraction pipeline of the fan (7) extracts ambient air when starting, and automatically closes after the air volume is balanced, and the tail gas internal circulation is started. In the stage of extracting ambient air, the rotation speed of the fan (7) is 1000-1500rpm. When switching to the tail gas internal circulation, the rotation speed of the fan (7) is adjusted to 800-1200rpm; High-pressure gas enters the pneumatic pump to generate negative pressure, and the groundwater in the lower layer of the groundwater extraction well (2) is extracted to the upper layer through the air extraction pipe. The groundwater is mixed with the gas at high speed in the pump body and then ejected at high speed from the nozzle to achieve aeration in the well. At the same time, the filter screen (202) on the upper layer of the well pipe intercepts water vapor, and the pollutants are extracted by the extraction device after volatilization and enter the tail gas treatment device for circulation treatment. The water circulates under gravity and slight positive pressure. During the aeration process in the well, the gas flow rate of the pneumatic pump is adjusted to make the rising flow rate of the water in the well 1-3m / s; According to the repair requirements, the repair agent is prepared in the surface agent dosing device (4), and the agent dosing acceleration rate is adjusted by controlling the opening and closing size of the electromagnetic valve. The agent dosing can be carried out synchronously with aeration, that is, the agent is injected into the pneumatic pump through the dosing pipe under the action of negative pressure, mixed with groundwater and air, and then sprayed out and infiltrated back into the original formation under the action of hydraulic and air pressure to achieve agent dosing and mixing. When the process is carried out synchronously, the ratio of the agent flow rate in the agent dosing pipe (3) to the gas flow rate in the pneumatic pump is 1:5-1:

10. It can also be carried out separately, that is, the valve between the tail gas device and the pneumatic pump is closed, and the fan (7) draws ambient air and injects it into the well to lift the groundwater and the agent pump to the upper screen pipe section and then quickly discharge it under the action of pressure to accelerate the agent dosing. When the process is carried out separately, the flow rate of ambient air drawn by the fan (7) is 1.2-1.5 times the gas flow rate during normal tail gas circulation.

7. The application method of the integrated device for in-situ purification of VOCs in groundwater according to claim 6 is characterized in that: When aeration is performed in the well, the amount of high-temperature air introduced is controlled by adjusting the flow regulating valve on the pneumatic pump access pipe (5) to maintain the aeration temperature at 30-50°C and the temperature of the introduced high-temperature air at 100-200°C. During the circulation process, the groundwater stays in the aquifer for 2-5 hours after each aeration and circulation treatment. After each circulation treatment, the VOCs concentration in the groundwater is detected. When the concentration drops below a set threshold, the purification treatment of the area is stopped.

8. The application method of the integrated device for in-situ purification of VOCs in groundwater according to claim 6, characterized in that: During the process of adding the reagent alone, when the reagent is an oxidizing reagent, the reagent completes at least 1-2 cycles in the rock formation around the circulation well to ensure that the reagent is added evenly and in sufficient quantity. When the reagent is a reducing reagent, an appropriate amount of acid regulator is added to the groundwater extraction well (2) before adding, and the pH value of the groundwater is adjusted to 3-5 to improve the reduction reaction efficiency. During the entire application process, the activated carbon adsorption tank in the ground exhaust gas treatment device (6) is regularly regenerated, and the regeneration cycle is 1-3 months. The regeneration method is hot air purging, the hot air temperature is 120-150°C, and the purging time is 2-4 hours.

9. The application method of the integrated device for in-situ purification of VOCs in groundwater according to claim 6, characterized in that: Before starting the device, the stratum around the groundwater extraction well (2) is pretreated, including injecting a cleaning agent. The cleaning agent uses a surfactant solution with a concentration of 0.5%-2%. During the application process, the groundwater level changes are monitored in real time, and the operating parameters of the fan (7) and the pneumatic pump are adjusted according to the water level changes. During the agent addition process, the appropriate agent type and addition sequence are selected according to the water quality and pollutant composition of the groundwater. When the water contains multiple VOCs pollutants, a special agent for the main pollutants is added first, and then an auxiliary agent is added.

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