An in-situ remediation system for organic contaminated groundwater and a remediation method thereof

Abstract

The application discloses an in-situ remediation system for organic contaminated groundwater and a remediation method thereof, and relates to the technical field of groundwater pollution remediation. The system comprises a circulating well main well unit, which comprises a monitoring well with a plurality of holes in the wall, and a water pumping pipe and a water injection pipe arranged in the monitoring well. A sealing unit is arranged in the monitoring well and can seal or unseal the inside of the monitoring well. The water injection pipe is located above the sealing unit, and the water pumping pipe penetrates through the sealing unit. An electro-Fenton reaction unit is arranged above the sealing unit and can generate hydrogen peroxide. A power driving unit can drive the sealing unit to move up and down through the water pumping pipe. The remediation method based on the system can complete the sealing and unsealing of the well, and further realize the purpose of freely adjusting the position of the upper and lower screen sections of the well and the proportion of the screen section and the actual section. The electro-Fenton reaction unit realizes the in-situ sufficient generation of oxidizing agents through electrochemical reaction, and realizes the efficient oxidation and removal of organic pollutants in the groundwater through the coupling with the circulating well technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of groundwater pollution remediation, in particular to an in-situ remediation system for organic contaminated groundwater and a remediation method thereof. BACKGROUND

[0002] Groundwater is one of the main sources of drinking water, agricultural and industrial water, and is a valuable water resource for human beings. With the acceleration of industrialization, the quality of groundwater has inevitably been threatened by human activities. The investigation results of groundwater organic pollution show that the groundwater in most areas is contaminated by organic matter, among which the detection rate of chlorinated aliphatic hydrocarbons such as chloroform, tetrachloroethylene, 1,2-dichloroethane, 1,2-dichloropropane, carbon tetrachloride and trichloroethylene is relatively high, and the main components exceeding the standard are carbon tetrachloride, benzene, chloroform, 1,2-dichloroethane and trichloroethylene. Organic pollution has become one of the main pollution problems of groundwater, and how to scientifically carry out the remediation of organic contaminated groundwater is one of the research hotspots of groundwater governance in China.

[0003] In-situ chemical oxidation technology is favored in the research of organic contaminated site remediation due to its economic efficiency, small disturbance to the underground environment and other advantages. The main principle is to deliver chemical oxidants to the contaminated aquifer, and the contact reaction between the chemical oxidants and the pollutants makes the pollutants transform into small molecular substances harmless to the environment. As a common oxidizing agent, hydrogen peroxide (H2O2) is often applied in in-situ chemical oxidation process due to its high activation efficiency, green and non-secondary pollution advantages. H2O2 activated by divalent iron ions will generate hydroxyl radicals with strong oxidizing properties, which can transform pollutants into small molecular compounds with less harm or no toxicity after contact reaction. Although in-situ chemical oxidation technology based on H2O2 has been applied in actual site remediation, there is still a big gap between the expected remediation effect. As the most widely used oxidizing agent, H2O2 has high demand for oxidizing agents due to the changes of permeability and biogeochemical conditions in certain specific areas during its delivery to the underground, which leads to the increase of non-specific loss of oxidizing agents, the inability of the agents to simultaneously distribute in large quantities in the contaminated aquifer, the difficulty of mixing, contacting and reacting with pollutants, the serious reduction of pollutant removal efficiency and the waste of agents. At the same time, due to the slow flow of groundwater, the transmission efficiency of the agents in the aquifer is low, which limits the scope of remediation; part of the agents injected into the underground environment will also react with the organic matter attached to the medium, resulting in the loss of remediation agents and the difficulty of controlling and remediation of the pollution plume.

[0004] Therefore, how to enhance the conduction ability of the agents in the aquifer, continuously deliver sufficient remediation agents to the contaminated aquifer, improve the utilization rate of the agents, reduce secondary environmental problems and achieve efficient and green remediation is the key to in-situ remediation of groundwater pollution.

[0005] Improving the transport capacity of the pharmaceutical agent in the aquifer is the key problem to improve the efficiency of groundwater pollution remediation. Groundwater circulation well remediation technology originated in Germany and emerged in the United States. This technology can achieve three-dimensional hydraulic circulation of groundwater around the well through water power control or air power control, which is beneficial to the effective control of groundwater pollution plume. In the past three decades, the circulation well remediation technology has been applied to the remediation and treatment of many groundwater pollution sites in the United States, Germany and other countries, and the technical feasibility has been proved. Compared with the traditional "pumping-treatment" remediation technology, the recognized advantage of the circulation well technology is that it does not need to pump water from the underground, and has less impact on the regional groundwater level and water quantity. The circulation well generally contains two or more numbers of screen sections. The water level difference formed inside and outside the well during the process of groundwater pumping and injection of screen sections can be used as the three-dimensional circulation power of groundwater, and an elliptical groundwater flow field with vertical distribution is generated, which enhances the vertical flushing capacity of the aquifer, especially for low permeability strata. During the operation of the circulation well, the position of the upper and lower screen sections of the circulation well and the proportion of the screen section and the solid section affect the hydraulic circulation range and efficiency of the circulation well. However, since the packer of the circulation well is generally fixed, the position of the upper and lower screen sections and the proportion of the screen section and the solid section are also fixed, and a circulation well can only be used for remediation of specific stratum structure, and cannot realize the reuse of the circulation well for various stratum conditions. During the construction of the circulation well, due to the many accessories and complex assembly process, the cost of the well is very high, in addition, professional mechanical equipment is needed for disassembly, which consumes a lot of manpower and material resources.

[0006] Therefore, a low-cost circulation well with flexible assembly, convenient sealing / dismantling and free adjustment of the position of the upper and lower screen sections and the proportion of the screen section and the solid section is designed, which can realize efficient utilization of the circulation well and remediation of different stratum conditions aquifer.

[0007] A Chinese patent with publication number CN114458224A discloses an in-well packer for a groundwater circulation well and a method for using the same. The in-well packer includes a central pipe, a packing assembly, and a driving assembly. The packing assembly is arranged on the central pipe, and at least part of the packing assembly is movable relative to the central pipe. The driving assembly is connected with the packing assembly and can drive part of the packing assembly to move relative to the central pipe. When the packing assembly moves relative to the central pipe, the packing assembly can deform to change the cross-sectional area. The packing assembly contacts and separates from the inner wall of the circulation well based on the change in the cross-sectional area to complete the setting and unsetting processes. The method includes arranging the in-well packer between a pumping pipe and a water injection pipe, arranging an upper screen pipe and a lower screen pipe on the outer pipe of the circulation well corresponding to the depth of the pipe orifice of the pumping pipe and the water injection pipe, respectively, and controlling the driving assembly to drive part of the packing assembly to move relative to the central pipe and expand the cross-sectional area to set the circulation well. However, the in-well packer designed in this patent has a complex structure and a large number of accessories, resulting in high production cost.

[0008] Another key to improving remediation efficiency is to continuously deliver a sufficient amount of remediation agent to the contaminated aquifer and improve the utilization rate of the agent. H2O2, as a multifunctional green oxidant, has been widely used in the remediation of various types of contaminated sites. Currently, most of the H2O2 synthesized in industry is produced by the indirect anthraquinone method, which has high energy consumption, complex steps, and a high risk of concentrated H2O2 solution during storage and transportation. The principle of in-situ electrochemical H2O2 production technology is to generate H2O2 in situ by two-electron reduction of oxygen at the cathode. Subsequently, divalent iron ions in the aquifer are activated to generate strong oxidizing hydroxyl radicals to oxidize and degrade organic pollutants. In-situ electrochemical H2O2 production technology can efficiently and quickly produce sufficient H2O2, not only continuously providing remediation agents, but also having green and economic advantages, thus attracting much attention.

[0009] A Chinese patent with publication number 217350882U discloses a groundwater circulation well combined with a chemical oxidation in-situ remediation system. The system includes a groundwater circulation well system and a chemical oxidation in-situ remediation system. The in-situ chemical remediation system includes a group of injection wells formed by multiple in-situ remediation wells. The in-situ remediation well includes an injection well and a dosing pipe arranged in the injection well. The dosing pipe is connected with a chemical tank arranged on the ground. The injection well is arranged upstream of the circulation well and downstream of the circulation well, respectively.

[0010] The utility model discloses in view of the defects of prior art, utilize the characteristics that groundwater circulation well forms a conical repair area with the circulation well as the center finally along with aeration time extension, set up chemical oxidizing reagent injection well group in the repair area, improve the repair efficiency, expand the site use condition of combined repair simultaneously, provide new technical thought for engineering application. But the repair system designed in this patent needs to add repair reagent additionally, and the complex reagent batching is easy to produce environmental negative effect, and is forced to consume under the action of side reaction after entering aquifer, and it is difficult to guarantee the effective mass transfer of reagent and the efficient removal of pollutants.

[0011] The existing circulation well technology for contaminated site remediation at least has the following deficiencies: the packer of the circulation well is generally fixed, resulting in fixed positions of the upper and lower screen sections of the circulation well and a fixed ratio of the screen section to the solid section, so that a set of circulation well device can only be used for remediation of specific stratum structures and cannot be reused for various stratum conditions. SUMMARY

[0012] The purpose of the present application is to provide an in-situ remediation system for organic contaminated groundwater and a remediation method thereof to solve the problems of the prior art, and the sealing unit can adjust its position in the well to freely adjust the positions of the upper and lower screen sections and the ratio of the screen section to the solid section.

[0013] To achieve the above purpose, the present application provides the following solutions:

[0014] The present application provides an in-situ remediation system for organic contaminated groundwater, which can realize low-cost assembly of the circulation well, flexible regulation of the well structure can meet the needs of different geological conditions, and can effectively solve the problems of large injection reagent demand, low utilization rate and poor reagent transmission capacity of traditional in-situ chemical oxidation remediation technology. The structure comprises a circulation well main well unit, which comprises a monitoring well with perforations on the pipe wall from above the groundwater level line to the top, and a pumping pipe and a water injection pipe are arranged in the monitoring well; a sealing unit is arranged in the monitoring well, which can seal or unseal the inside of the monitoring well, the water injection pipe is located above the sealing unit, and the pumping pipe is fixedly sealed through the sealing unit; an electro-Fenton reaction unit is arranged above the sealing unit, which can generate hydrogen peroxide; and a power drive unit can drive the sealing unit to move up and down through the pumping pipe.

[0015] Optionally, the sealing unit comprises an internally hollow rubber ball, the rubber ball is respectively connected with a nitrogen gas filling pump and a nitrogen gas exhaust pump through pipelines, a control valve is arranged on the pipeline, the nitrogen gas exhaust pump, the nitrogen gas filling pump and the control valve are respectively connected with a control end, the rubber ball has good physical and chemical stability, is resistant to acid and alkali corrosion, is resistant to high pressure and has good deformation capacity, the cross-sectional area of the rubber ball is reduced when the nitrogen gas exhaust pump is operated, the cross-sectional area of the rubber ball is increased when the nitrogen gas filling pump is operated, and the sealing effect is achieved.

[0016] Optionally, a pressure sensor is arranged on the rubber ball and connected with the control end.

[0017] Optionally, the electro-Fenton reaction unit comprises a flexible electrode fixing plate, the flexible electrode fixing plate is closely attached to the outer surface of the rubber ball, a cathode and an anode are respectively arranged on the flexible electrode fixing plate, the cathode and the anode are respectively connected with a power supply, the anode is selected from functional electrodes with good oxygen evolution, and the cathode is selected from electrodes with excellent performance for producing H2O2.

[0018] Optionally, a water pumping pipe is fixedly and sealingly penetrated through the rubber ball, a water pumping pump is arranged at the top of the water pumping pipe, the water pumping pipe is connected with the electric power driving unit, so that the water pumping pipe and the rubber ball can be simultaneously moved up and down relative to the well, and a water injection pipe is connected with a water injection pump at the top.

[0019] Optionally, the electric power driving unit comprises a driving device, the driving device is connected with a driving rope, and the driving rope is connected with the upper part of the water injection pipe after passing through a fixed pulley.

[0020] The rubber ball is placed in the main well unit of the circulating well, the rubber ball is inflated and deflated and is provided with a pressure sensor on the surface, the rubber ball is connected with a nitrogen gas filling pump and a nitrogen gas exhaust pump through air pipes, a telescopic water pumping pipe is penetrated through the rubber ball and is in good sealing, an electric driving device can drive the telescopic water pumping pipe to move the rubber ball relative to the well, the nitrogen gas filling pump and the nitrogen gas exhaust pump are flexibly started and stopped to realize the contraction and expansion of the rubber ball, the sealing and unsealing of the well are completed, and the position of the screen section on the well and the proportion of the screen section and the real section are freely adjusted. The electro-Fenton reaction unit realizes the in-situ sufficient generation of oxidizing agents through electrochemical reactions, and realizes the efficient oxidation and removal of organic pollutants in underground water through the coupling with the circulating well technology.

[0021] The application further provides an in-situ remediation method for organic contaminated underground water, comprising the following steps:

[0022] S1, according to the investigation data of the contaminated site, the removal process of the pollutants is analyzed combined with model simulation, and a point layout scheme of the circulating well main well unit is determined;

[0023] S2, determine the point layout monitoring well, the monitoring well inside the rubber ball, suction pipe, water injection pipe, the upper part of the rubber ball is provided with an electric Fenton reaction unit;

[0024] S3, start the nitrogen gas charging pump to inflate the rubber ball until the monitoring well is sealed;

[0025] S4, start the water pump and water injection pump simultaneously to pump and inject water into the well, when the monitoring well hydraulic cycle is started, the power supply is started at the same time to power the cathode and anode, realizing the cycle capture and synchronous oxidation removal of organic pollutants in groundwater;

[0026] S5, interval setting time, sampling and detecting the content of pollutants from the monitoring well near the pollution source, analyzing the spatial variation law of the pollution plume with time, until the pollution plume range is reduced and the pollution risk is reduced to an acceptable set degree to complete the repair.

[0027] The present application has the following technical effects compared with the prior art:

[0028] The organic contaminated groundwater in-situ remediation system of the present application is flexible in assembly, convenient and accurate in sealing / dismantling, can freely adjust the position of the upper and lower screen sections and the ratio of the screen section to the solid section of the circulating well, can realize the repair of various contaminated aquifers, and can reduce the construction cost of the circulating well. The present application innovatively couples the electric Fenton, a high-level oxidation technology that can efficiently degrade organic pollutants, with the traditional circulating well technology, realizes the cycle capture and synchronous efficient oxidation removal of organic pollutants in groundwater. The present application can continuously generate sufficient H2O2 in-situ through electrochemical reaction, avoids the problems of excessive demand for reagents, limited reagent utilization rate and easy secondary environmental pollution in traditional in-situ chemical oxidation technology, and meets the safe and green repair concept. The H2O2 generated by the electric reduction reaction in the present application can be better transmitted in the aquifer through the hydraulic circulation of the circulating well, solving the problem of mass transfer difficulty of traditional in-situ chemical oxidation reagents in the aquifer. In the repair method provided by the present application, the trivalent iron ions generated after the activation of H2O2 by divalent iron ions can enter the inner well under the action of hydraulic circulation, and are reduced to divalent iron ions under the action of cathode, and are recycled and participate in the activation of H2O2 again, realizing the continuous continuation of the repair process. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1A schematic diagram of the principle of the organic contaminated groundwater in-situ remediation system of the present application is shown in the figure.

[0031] Figure 2 A schematic diagram of the arrangement of the cathode and the anode of the present application is shown in the figure.

[0032] Reference signs: 1-monitoring well; 2-nitrogen charging pump; 3-nitrogen pumping pump; 4-rubber ball; 5-water injection pipe; 6-water pumping pipe; 7-water injection pump; 8-water pumping pump; 9-fixed pulley; 10-electric power driving device; 11-cathode; 12-anode; 13-flexible electrode fixing plate; 14-power supply; 15-pressure sensor. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0034] The purpose of the present application is to provide an organic contaminated groundwater in-situ remediation system and a remediation method thereof, so as to solve the problems existing in the prior art. The packer unit can adjust its position in the well, thereby achieving the purpose of freely adjusting the position of the screen section on the well and the proportion of the screen section and the solid section.

[0035] In order to make the above-mentioned purposes, characteristics and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The present application provides an organic contaminated groundwater in-situ remediation system, as shown in the figure, which comprises a circulating well main well unit, a packer unit, an electro-Fenton reaction unit and an electric power driving unit. Figure 1 The circulating well main well unit is a monitoring well 1 provided with perforations on the pipe wall from above the groundwater level line to the top, and a water injection pipe 5 and a water pumping pipe 6 are placed in the well, and the water injection pipe 5 and the water pumping pipe 6 are respectively connected with a water injection pump 7 and a water pumping pump 8 outside the well; the distribution range of the perforated pipe of the circulating well main well unit is from above the groundwater level line to the lowest position of the phreatic aquifer bottom plate; the packer unit comprises a rubber ball 4 which is retractable and provided with a pressure sensor 15 on the surface, the retractable water pumping pipe 6 penetrates through the rubber ball 4 and is sealed well, the water injection pipe 5 is located above the rubber ball 4, and the rubber ball 4 is respectively connected with a nitrogen charging pump 2 and a nitrogen pumping pump 3 through a pipeline with a control valve.

[0037] Further preferably, the rubber ball 4 has good physical and chemical stability, is resistant to acid and alkali corrosion, is resistant to high pressure, and has good deformation capacity, and the pressure sensor 15 arranged on the surface of the rubber ball 4 can well detect the pressure change of the rubber ball 4. When the nitrogen air pump 3 is running, the cross-sectional area of the rubber ball 4 is reduced, and the rubber ball 4 plays a role of unsealing. When the nitrogen air pump 2 is running, the cross-sectional area of the rubber ball 4 is increased, and the rubber ball 4 plays a role of sealing.

[0038] The electro-Fenton reaction unit includes a flexible electrode fixing plate 13, a cathode 11, an anode 12, and a power supply 14. The flexible electrode fixing plate 13 is a material with stable properties and is resistant to acid and alkali corrosion, and has good ductility and can be closely attached to the surface of the rubber ball 4 to fix the cathode 11 and the anode 12. In the present application, the position relationship between the flexible electrode fixing plate 13 and the rubber ball 4 is as shown in the figure. Figure 2 In the present application, the electro-Fenton reaction unit preferably further includes a power supply 14 connected to the cathode 11 and the anode 12. The material of the cathode 11 is preferably an electrode with good oxygen reduction capacity. In the present application, the material of the anode 12 is preferably an inert electrode with good oxygen evolution capacity.

[0039] The electric power driving unit includes an electric power driving device 10 and a fixed pulley 9. The driving rope of the electric power driving device 10 is connected to the water pumping pipe 6 through the fixed pulley 9, so that the up and down movement of the water pumping pipe can be realized, and then the rubber ball is moved up and down.

[0040] The working process of the system of the present application is as follows:

[0041] The process of entering the well is as follows: first, the nitrogen air pump 3 is used to pump out the gas in the rubber ball 4, at this time the rubber ball 4 is in a contracted state, and then the electric power driving device is used to drive the water pumping pipe 6 to move the rubber ball to a designated position. The end of the water injection pipe 5 is always located above the rubber ball at a certain distance from the rubber ball.

[0042] The process of sealing is as follows: after the rubber ball 4 is moved to the designated position, the nitrogen air pump 2 is started to charge air into the rubber ball 4 through the air charging pipe, at this time the rubber ball 4 is inflated, the cross-sectional area is gradually increased, the contact area between the rubber ball 4 and the wall of the circulating well is increased, and the pressure sensor 15 arranged on the surface of the rubber ball 4 is used to detect the corresponding pressure and stop charging air, so as to realize the sealing of the well.

[0043] Regulation process: when the well structure needs to be adjusted according to the different pollution conditions of the aquifer, first, the gas in the rubber ball 4 is pumped out by the nitrogen gas pump 3, at this time, the contact area of the rubber ball 4 with the wall of the circulation well gradually becomes smaller, the friction force becomes smaller, and the rubber ball 4 is loosened, at this time, the unblocking process of the circulation well is completed. Then, the power driving device 10 is started to drive the pumping pipe 6 to move the rubber ball 4 upward or downward to the specified position through the fixed pulley 9, and the rubber ball 4 is re-sealed, at this time, the adjustment of the position of the upper and lower screen sections of the well is realized. After re-sealing is completed, continue to inflate with the nitrogen gas pump 2, due to the restriction of the well wall, the rubber ball 4 expands upward along the well wall, the length increases continuously in the longitudinal direction, at this time, the adjustment of the length ratio of the screen section and the solid section of the circulation well can be realized.

[0044] The application also provides an in-situ remediation method for organic contaminated groundwater, comprising the following steps:

[0045] S1, according to the investigation data of the contaminated site, the hydrogeological conditions and the pollution characteristics of the site are determined, the distribution of the groundwater pollution plume and the ability of the circulation well to capture pollutants are comprehensively considered, the removal process of the pollutants is simulated and analyzed by using a model, and the point layout scheme of the circulation well is determined to ensure that the influence range of the circulation well can cover the entire pollution plume.

[0046] S2, a monitoring well 1 with a flower hole is determined for point layout, the flower hole section is located above the groundwater level to the lowest position of the phreatic aquifer bottom plate, a rubber ball 4 which can expand and contract by inflating and deflating is placed in the well, a pressure sensor 15 is arranged on the surface of the rubber ball 4, the rubber ball 4 is connected with a nitrogen gas inflating pump 2 and a nitrogen gas pumping pump 3 respectively, a pumping pipe 6 penetrates the rubber ball and is sealed well, the pumping pipe 6 is driven by an electric driving device 10 to drive the rubber ball 4 to move relative to the well, and a water injection pipe 5 is arranged above the rubber ball. The upper part of the rubber ball is a flexible electrode fixing plate 13 for parallel fixing of a cathode 11 and an anode 12, the cathode 11 and the anode 12 are connected with an external power supply 14 through wires.

[0047] S3, after the position of the rubber ball 4 is fixed, the nitrogen gas inflating pump 2 is started to inflate the rubber ball 4, at this time, the rubber ball 4 expands continuously and gradually elongates upward and downward, the inflation is stopped after the corresponding pressure is detected by the pressure sensor 15 arranged on the surface of the rubber ball 4, and the sealing of the circulation well is realized. Similarly, when the nitrogen gas pumping pump 3 pumps out the gas, the rubber ball 4 shrinks continuously and gradually shrinks downward and upward, and the length ratio of the screen section and the solid section of the circulation well is adjusted by the two ways.

[0048] S4, synchronously start the water pump 8 and the water injection pump 7 to pump and inject water into the well, when the circulating well hydraulic circulation is started, the power supply 14 is also started to supply power to the cathode 11 and the anode 12, the oxygen in the underground water reacts with water to generate H2O2 under the catalysis of the cathode 11; H2O2 is well distributed in the aquifer under the action of the circulating well hydraulic circulation, is activated by the divalent iron ions in the aquifer to generate strong oxidizing hydroxyl radicals, and then the oxidation degradation of the organic pollutants is realized; meanwhile, the generated trivalent iron ions enter the well through the hydraulic circulation and are reduced to divalent iron ions at the cathode, realizing circulation, further activating H2O2, continuously oxidizing and degrading pollutants, and realizing the cyclic capture and synchronous oxidation removal of the organic pollutants in the underground water.

[0049] The generated H2O2 can be better diffused in the aquifer under the action of the circulating well hydraulic circulation.

[0050] At this time, the divalent iron in the aquifer can effectively activate H2O2 to generate strong oxidizing hydroxyl radicals to oxidize and degrade pollutants, and the generated trivalent iron ions enter the well through the hydraulic circulation and are reduced to divalent iron ions at the cathode to continue to activate H2O2 to generate hydroxyl radicals, realizing the advanced oxidation removal of the pollutants in the well. The purpose of cyclic capture and removal of the pollution plume around the circulating well is achieved.

[0051] S5, after a certain period of time, the content of pollutants is detected by sampling from the monitoring well near the pollution source, and the spatial variation rule of the pollution plume with time is analyzed, until the range of the pollution plume is reduced and the pollution risk is reduced to an acceptable degree, and the repair is completed.

[0052] In the description of the present application, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for description purposes and cannot be understood as indicating or implying relative importance.

[0053] In the present application, specific examples are applied to describe the principles and implementation modes of the present application, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In view of the above, the content of the specification should not be understood as limiting the present application.

Claims

1. An in-situ remediation system for organically contaminated groundwater, characterized in that: The system includes a main well unit for circulation wells, comprising a monitoring well with perforated pipe walls, containing a pumping pipe and an injection pipe; a packer unit located within the monitoring well, capable of sealing or unsealing the interior of the monitoring well, with the injection pipe positioned above the packer unit and the pumping pipe fixedly and sealed through the packer unit; an electro-Fenton reaction unit located above the packer unit, capable of generating hydrogen peroxide; and an electric drive unit capable of moving the packer unit up and down via the pumping pipe, comprising a drive device connected to a drive cable, which passes over a fixed pulley and connects to the upper part of the injection pipe; the packer unit includes hollow rubber balls, which are connected to external pipes. The system is equipped with a nitrogen filling pump and a nitrogen extraction pump. A control valve is installed on the pipeline, and the nitrogen extraction pump, nitrogen filling pump, and control valve are connected to a control terminal. The end of the water injection pipe is always positioned above and at a certain distance from the rubber ball. The electro-Fenton reaction unit includes a flexible electrode fixing plate, which is tightly fitted to the outer surface of the rubber ball. A cathode and an anode are respectively installed on the flexible electrode fixing plate, and the cathode and anode are respectively connected to a power source. By opening and closing the nitrogen filling pump and the extraction pump, the rubber ball contracts and expands, completing the sealing and unsealing of the well, thereby adjusting the positions of the upper and lower screen sections and the ratio of screen sections to solid sections. The electro-Fenton reaction unit achieves in-situ sufficient generation of oxidizing agents through an electrochemical reaction, and through coupling with circulating well technology, it achieves the oxidative removal of organic pollutants in groundwater.

2. The in-situ remediation system for organically polluted groundwater according to claim 1, characterized in that: A pressure sensor is installed on the rubber ball, and the pressure sensor is connected to the control terminal.

3. The in-situ remediation system for organically polluted groundwater according to claim 1, characterized in that: The bottom of the pumping pipe is fixedly sealed through the rubber ball, and a pumping pump is connected to the top of the pumping pipe and a pumping pump is connected to the top of the injection pipe.

4. A method for in-situ remediation of organically polluted groundwater based on the organically polluted groundwater in-situ remediation system according to any one of claims 1 to 3, characterized in that: Includes the following steps: S1. Based on the survey data of the contaminated site and combined with the model simulation analysis of the pollutant removal process, determine the layout scheme of the main well unit of the circulation well. S2, a monitoring well is set up at a determined location. A rubber ball, a pumping pipe, and a water injection pipe are placed inside the monitoring well. An electro-Fenton reaction unit is set on the top of the rubber ball. S3, start the nitrogen inflation pump to inflate the rubber ball until the monitoring well is sealed; S4, simultaneously starts the pumping pump and injection pump to pump and inject water into the well. When the hydraulic circulation of the monitoring well starts, the power supply is simultaneously started to energize the cathode and anode, so as to realize the cyclic capture and synchronous oxidation removal of organic pollutants in the groundwater. S5, at set intervals, samples are taken from monitoring wells near the pollution source and the content of pollutants is detected. The spatial variation of the pollution plume over time is analyzed until the range of the pollution plume decreases and the pollution risk is reduced to a set level, thus completing the remediation.

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