Three-dimensional well group structure for in-situ remediation of underground water and application method

Abstract

The invention discloses a three-dimensional well group structure for in-situ remediation of underground water and an application method, and relates to the technical field of underground water remediation, the well group structure comprises an air compressor, a PLC controller, an agent adding device, an underground water well and an underground water pump. According to the well group structure and the application method, the groundwater remediation efficiency and effect are greatly improved, a unique crossed 3D hydraulic circulation mode is adopted, small hydraulic circulation is formed in the wells, large hydraulic circulation is formed between the well groups, the small hydraulic circulation is nested in the large hydraulic circulation, and the underground water remediation efficiency and effect are greatly improved. Hydraulic transmission in the horizontal direction and hydraulic spring layer transmission between an upper layer and a lower layer exist in a large cycle, so that agent diffusion is more uniform and wider, the effective covering radius can be enlarged, the covering range of a traditional single well is far beyond, the number requirement of well groups is greatly reduced, and the construction and operation and maintenance cost is reduced; the method is suitable for repairing pollution of buildings in gas stations, chemical industry enterprises, chemical industry park roads and other complex scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater restoration, and in particular to a three-dimensional well group structure and an application method for in-situ restoration of groundwater. Background Art

[0002] In modern society, groundwater is an important component of water resources, and its quality protection and restoration are receiving increasing attention. Groundwater aquifers are vulnerable to various pollutants, causing their water quality to deteriorate, seriously threatening the ecological environment and human health. Traditional groundwater remediation technology mainly uses high groundwater well injection technology to repair groundwater pollution. The groundwater well injection technology is used to inject chemicals into the underground aquifer to repair the groundwater layer.

[0003] Traditional groundwater remediation technology has many limitations when facing aquifer pollution. Taking the common groundwater well injection technology as an example, the injection wells are closely spaced, and the diffusion of the agent is only under the influence of concentration and water level pressure difference in the well. The diffusion effect is poor, the speed is slow and the distribution is uneven. The agent diffusion radius of a single well is extremely limited, usually only 3-5 meters. As a result, in order to achieve effective remediation in larger polluted areas, a large number of wells have to be densely built, which undoubtedly greatly increases the remediation cost and engineering complexity.

[0004] Especially in the scene of chemical enterprises in production, due to the restrictions of buildings and complex underground pipeline layout, when the aquifer under the building is polluted, it is difficult to add reagents to this area. Traditional technology cannot ensure that the reagents are effectively diffused to the core area of ​​pollution and cannot fully play the role of repair, causing the groundwater repair work in such special areas to fall into difficulties and it is difficult to achieve the expected repair goals, which seriously restricts the progress and effect of groundwater pollution control. Therefore, it is necessary to propose a three-dimensional well group structure and application method for in-situ groundwater repair to solve the problems in the existing technology. Summary of the invention

[0005] The purpose of the present invention is to make up for the shortcomings of the prior art and to provide a three-dimensional well group structure and application method for in-situ groundwater remediation, which can pump water from the lower layer to the upper layer, pump water from the upper layer to the lower layer, and realize three-dimensional circulation between the well pipe itself and the adjacent well pipes, so that the reagent and the groundwater are fully mixed and contacted, thereby achieving efficient removal of organic pollutants in the groundwater and improving the remediation effect of the groundwater.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a three-dimensional well group structure for in-situ groundwater remediation, the well group structure comprising an air compressor, a PLC controller, a reagent dosing device, a groundwater well and a groundwater pump;

[0007] The groundwater well is a special stainless steel well pipe, which is composed of two layers, an inner layer of 304 stainless steel with slits, and an outer layer of a stainless steel wire mesh structure. The middle of the two layers is filled with crushed stones and quartz sand with a particle size of 2-3mm. The whole well pipe is a permeable structure. The well pipe has an intermediate blocker in the middle position, which divides the well pipe into two parts, the upper and lower parts, and the middle is a watertight structure;

[0008] The groundwater pump includes a pump body, which is suspended in a groundwater well by a steel wire rope. A feed port is provided at the bottom end of the pump body, and the feed port is immersed in the groundwater. A water outlet pipe is provided on the outer surface of the pump body, and the end of the water outlet pipe away from the pump body passes through an intermediate baffle and extends to the other side of the intermediate baffle. A chemical dosing pipe is provided on the outer surface of the pump body, and the top of the chemical dosing pipe is connected to a chemical dosing device. An air inlet pipe and an air outlet pipe are fixedly connected to the upper surface of the pump body, and the tops of the air inlet pipe and the air outlet pipe are both connected to an air compressor. Solenoid valves are installed inside the air inlet pipe and the air outlet pipe, and the solenoid valves are connected to a PLC controller through wires.

[0009] Furthermore, the slit width of the inner layer of the groundwater well is 0.5-1.5mm, the slits are evenly distributed and the distance between adjacent slits is 5-10mm, the mesh size of the stainless steel wire mesh structure outside the groundwater well is 1-3mm, and the intermediate barrier is made of rubber and has a thickness of 5-10mm.

[0010] Furthermore, the drug-dosing pipe is made of polyvinyl chloride and has an inner diameter of 3-5 mm, and a sealing gasket made of rubber is provided at the connection between the drug-dosing pipe and the pump body.

[0011] Furthermore, a piston is sealingly slidably disposed inside the pump body, and a spring is installed on the bottom surface of the piston.

[0012] Furthermore, a hollow limit ring is installed on the inner wall of the feed port, the upper surface of the hollow limit ring is connected to the bottom end of the spring, a sphere is arranged inside the hollow limit ring, and the sphere is sealed with the inner wall of the feed port when it is located at the bottom of the hollow limit ring.

[0013] An application method of a three-dimensional well group structure for in-situ groundwater remediation, the method comprising the following steps:

[0014] S1. Well group construction and equipment installation: Determine the location and number of groundwater wells based on the characteristics, scope and hydrogeological conditions of the groundwater pollution area, plan the layout to ensure comprehensive coverage and efficient treatment of the pollution area, and strictly control the verticality error within ±0.5° when digging wells. The diameter should be adapted to the well pipe specifications and meet the construction standards;

[0015] S2. System debugging and parameter setting: Check the appearance of the equipment, component connections, and electrical systems in detail. Set the opening and closing time of the solenoid valve of the reagent dosing device and the opening and closing time of the electronic valve of the underground water pump according to the pollution degree, pollutant characteristics, and treatment goals. When trying to pump water and dosing, if the water pump is unstable, fine-tune the opening time of the electronic valve at the air inlet every 0.5 seconds until it is stable, so that the pumping pressure fluctuation range is within ±0.1MPa and the reagent flow error is within ±5%;

[0016] S3. Groundwater circulation and purification treatment:

[0017] S301: Start the air compressor. The groundwater pumps of one group of groundwater wells pump the lower layer water to the upper layer, and the other group pumps the upper layer water to the lower layer. Each pump accurately doses the medicine through the medicine dosing pipe at the set rate. The medicine and groundwater are mixed in the groundwater pump. In the same group of groundwater wells, the groundwater circulates in the upper and lower layers due to the water permeation of the well pipe and the flow direction of the inlet and outlet water. Due to the changes in water level and water pressure, after the lower layer water is pumped into the upper layer, part of it diffuses to the surrounding through the upper layer permeation part, and part of it enters the pump for circulation. The upper layer water flows down to the lower layer and circulates in a similar way, forming a small hydraulic circulation in the well;

[0018] S302. Between the two groups of groundwater wells, pumping up and discharging down and pumping down and discharging up are coordinated to build a large hydraulic cycle based on the water level difference, water flow inertia and pumping power. The water discharged from the groundwater wells with pumping down and discharging up will flow horizontally to the water absorption area of ​​the groundwater wells with pumping up and discharging down, and will carry the reagent to penetrate the stratum on the way. Part of the groundwater enters the lower layer of the groundwater wells with pumping down and is then pumped up for circulation. The water discharged from the lower layer of the groundwater wells with pumping up and discharging down will flow back to the water absorption area of ​​the groundwater wells with pumping down and discharging down along the reverse horizontal flow, and will penetrate the surrounding strata through the permeable structure. Part of the groundwater enters the upper layer and is pumped up for circulation again. In this process, the large cycle is nested in the small cycle, and the horizontal water flow carries the reagent to diffuse horizontally. The upper and lower layers are alternately pumped and discharged to realize hydraulic jump layer transmission, forming a cross 3D hydraulic connection, so that the reagent is evenly diffused in the rock and soil gap between the two wells, fully reacting with the pollutants to purify the groundwater.

[0019] S303. In response to special remediation technology requirements, for catalytic oxidation technology, oxidizing agents are injected into one group of groundwater wells, and catalytic agents are injected into another group of groundwater wells. The injection rate is controlled so that the two are mixed in the circulating water flow between the two groups of wells at a ratio of 1:0.5-1:2 to ensure efficient reaction within a short period of time after the agents come into contact, and fully exert the catalytic oxidation effect to degrade pollutants. For the treatment of chlorinated hydrocarbons using oxidation + reduction technology, reducing agents are first injected into one group of groundwater wells for dechlorination biological reduction treatment. The treatment time is set to 12-48 hours based on the pollution concentration. After that, oxygen-rich clean water is injected into the groundwater wells for cleaning for 6-12 hours to increase the redox point. Then, slow-release oxidizing agents are injected from another group of groundwater wells for oxidation treatment. The release rate of slow-release oxidizing agents is controlled at 0.01-0.1 g / hour·cubic meter based on the amount of remaining pollutants and formation characteristics. The remediation efficiency is improved by optimizing the injection sequence and rate of the agents. Based on water quality monitoring and water pump operating conditions, the PID algorithm is used to fine-tune the electronic valve switch of the groundwater pump in a timely manner to maintain stable and efficient operation.

[0020] S4. Water quality monitoring and system optimization: Collect water samples regularly to measure pollutant concentration, acidity, alkali, dissolved oxygen, and conductivity indicators, optimize the system based on the results, and adjust after analyzing the reasons when pollution does not meet the standards. If the reagent is not good, try replacing it with a small dose first, and observe the water quality for 1-2 days to determine whether to replace it completely. When replacing, reset the injection acceleration rate. If abnormal water flow affects the diffusion and circulation of the reagent, fine-tune the pump extraction frequency, and continuously monitor and optimize until the water quality meets the standards to ensure the repair effect and the efficient and stable well group structure.

[0021] Furthermore, in the steps of well group construction and equipment installation, a 0.3-0.5 meter thick gravel filter layer is first laid at the bottom of the wellbore, and then the groundwater well pipe is vertically and slowly placed therein, and a groundwater pump is installed in the groundwater well pipe and securely suspended with a wire rope. The feed port is immersed in the water at an appropriate depth, and the air inlet pipe, air outlet pipe, chemical dosing pipe, air compressor, chemical dosing device and ground PLC controller are tightly connected. All interfaces are tightly sealed, and 10-20 mm stainless steel corrugated pipes are used for the air inlet and outlet pipes. The well pipe and the wellbore wall are reinforced with 5-10 cm bentonite.

[0022] Furthermore, in the horizontal water flow transfer of the large hydraulic circulation between the two groups of groundwater wells, the influence of water flow on the diffusion of the agent is taken into consideration, and the ratio of the pumping and drainage rates of the two wells is adjusted. When the water flow rate is low, the pumping rate of the upper well and the lower well is appropriately reduced, and the pumping rate of the lower well is increased. The horizontal hydraulic gradient between the two wells is maintained within the range of 0.005-0.01 m / m to ensure that the agent can overcome the water flow resistance in the horizontal direction and fully diffuse to the area 20-30 meters away from the well.

[0023] Furthermore, in the hydraulic jump layer transmission link between the upper and lower layers, it is optimized according to the lithological characteristics of different formations. In the sandy aquifer, its porosity is conducive to the rapid penetration of water flow and reagents, and the extraction frequency is set to once every 4-6 hours. In the silty clay aquifer, the porosity is small and the hydraulic conductivity is low, and the extraction frequency is adjusted to once every 8-10 hours. During the extraction process, the extraction power is increased by 10%-15% in stages, so that the reagent can effectively break through the formation resistance and realize jump layer transmission. In the case of jump layer, if the concentration of the upper layer reagent is 30%-50% higher than that of the lower layer, the extraction parameters are automatically adjusted to slow down the upper layer pumping and speed up the lower layer pumping by 10%-20%. The balanced concentration promotes the two-way uniform diffusion of the reagent and enhances the 3D hydraulic connection repair efficiency.

[0024] Compared with the prior art, the three-dimensional well group structure and application method for in-situ groundwater remediation have the following beneficial effects:

[0025] The well group structure and application method of the present invention greatly improve the efficiency and effect of groundwater remediation. By adopting a unique cross 3D hydraulic circulation mode, not only a small hydraulic circulation is formed in the well itself, but also a large hydraulic circulation is formed between the well groups. In this way, a small hydraulic circulation is nested in the large hydraulic circulation. The large circulation has both horizontal hydraulic transmission and hydraulic jump layer transmission between the upper and lower layers, which makes the agent diffusion more uniform and extensive, and can expand the effective coverage radius, far exceeding the coverage range of traditional single wells, greatly reducing the demand for the number of well groups, and reducing construction and operation and maintenance costs. It is suitable for pollution remediation of buildings and structures in complex scenarios such as gas stations, chemical companies in production, and chemical park roads.

[0026] 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

[0027] 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.

[0028] Figure 1 It is a schematic diagram of the application of a three-dimensional well group structure for in-situ restoration of groundwater;

[0029] Figure 2 It is a three-dimensional structural diagram of a groundwater pump;

[0030] Figure 3This is a schematic diagram of the internal structure of a groundwater pump;

[0031] Figure 4 for Figure 3 Schematic diagram of the local structure.

[0032] 1. Air compressor; 2. PLC controller; 3. Chemical dosing device; 4. Groundwater well; 401. Intermediate barrier; 5. Groundwater pump; 501. Pump body; 502. Feed inlet; 503. Water outlet pipe; 504. Chemical dosing pipe; 505. Wire rope; 506. Air inlet pipe; 507. Air outlet pipe; 508. Piston; 509. Spring; 510. Hollow limit ring; 511. Ball. DETAILED DESCRIPTION

[0033] 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.

[0034] Example 1: Remediation of groundwater pollution in small factory areas

[0035] Application scenario description

[0036] Due to long-term chemical production activities, the underground soil and aquifers in the small factory area have been seriously polluted. The polluted area is about 5,000 square meters, located below the production workshop and storage area, with a depth ranging from 5 meters to 15 meters below the surface. The pollutants include organic chemical raw material residues (such as benzene concentrations as high as 5 mg / L, phenol concentrations of about 3 mg / L), heavy metal ions (lead concentrations of 0.2 mg / L, cadmium concentrations of 0.05 mg / L) and petroleum substances (petroleum hydrocarbon content of about 8 mg / L). The degree of pollution is uneven, and the concentration of pollutants in some areas is several times higher than the environmental standard. The surrounding buildings are densely populated and the underground pipelines are crisscrossed. Traditional remediation technology is difficult to implement due to site restrictions. Not only is the cost of remediation high (the estimated cost of traditional remediation is more than 5 million yuan), but it is also easy to cause long-term interference to production operations. There is an urgent need for efficient and accurate remediation solutions with little site disturbance to ensure groundwater quality, reduce environmental risks, and ensure the continuous compliance of the factory production and the surrounding ecological safety.

[0037] The professional exploration team used high-precision geological drilling equipment to analyze the geological structure and determine the characteristics and distribution of each layer of rock and soil. For example, the upper layer is silty clay, 3-5 meters thick, with a permeability coefficient of about 1×10-5cm / s; the middle sand layer is 6-8 meters thick, with a permeability coefficient of 5×10-3cm / s; the lower layer of clay rock is 4-6 meters thick, with a permeability coefficient of 1×10-7cm / s. With the help of advanced groundwater flow velocity and direction meters, the water flow velocity was accurately measured in the range of 0.05-0.15m / d and the flow direction was northeast. Water samples were collected at multiple points and analyzed by laboratory inductively coupled plasma mass spectrometer (ICP-MS), gas chromatography-mass spectrometry (GC-MS) and other precision instruments to accurately grasp key information such as pollutant types and concentration distribution. Based on this, taking into account the surrounding buildings, underground pipelines and water flow characteristics, 8 groundwater wells were carefully designed to be arranged in a circular shape at reasonable locations around the polluted area. The spacing between wells was optimized to 20-30 meters based on hydrogeological parameters and pollution distribution, laying a solid foundation for subsequent precise remediation.

[0038] The drilling equipment is selected strictly according to the plan, and the wellbore is accurately excavated to a depth suitable for the wellbore. The verticality is strictly controlled within ±0.5° with advanced total stations and inclinometers, and the diameter meets the wellbore specifications. The special double-layer stainless steel wellbore is slowly placed into the hole, and a 0.4-meter-thick gravel filter layer with a particle size of 3-5mm is laid on the bottom. The groundwater pump 5 is accurately installed on the upper layer of the wellbore, and it is firmly suspended with a high-strength corrosion-resistant steel wire rope 505, and the feed port is accurately determined to be 2-3 meters below the groundwater level. High-quality fluororubber sealing materials are used in each connection link to ensure that the air inlet pipe 506, the air outlet pipe 507, and the chemical dosing pipe are tightly connected without leakage, and the air compressor 1, the chemical dosing device 3 and the ground PLC controller 2 are seamlessly connected. Professional monitoring throughout the process ensures that the verticality of the wellbore meets the standards accurately.

[0039] The technicians comprehensively inspected and maintained the equipment. Based on the preliminary exploration and treatment objectives, and integrating theoretical calculations with practical experience, they scientifically set the opening and closing range of the electromagnetic valve of the reagent dosing device 3 to 25%-35%, and the injection acceleration rate to 5-10L / h according to the pollutant concentration. In the PLC controller 2, they accurately planned the switching time range of the electronic valves at the air inlet and outlet of the groundwater pump 5 (the air inlet is opened for 4-5 seconds and closed for 9-11 seconds; the air outlet is opened for 7-8 seconds and closed for 11-12 seconds). They conducted trial pumping and trial dosing, and closely observed the pumping pressure, flow stability and accuracy of the reagent dosing flow with high-precision pressure sensors and electromagnetic flowmeters. If the pumping pressure fluctuation exceeded ±0.1MPa or the reagent flow error exceeded ±5%, the switching time of the electronic valve at the air inlet was fine-tuned according to the feedback data, with an adjustment accuracy of 0.1 seconds each time. After repeated optimization, the system was ensured to run smoothly and the reagent dosage and water flow dynamic balance were accurately regulated.

[0040] Start the air compressor 1, and the groundwater pumps 5 of one group of wells will extract the lower layer water to the upper layer for discharge according to the program, and the other group will do the opposite. After each pump accurately doses the medicine, the medicine and groundwater are immediately mixed in the pump. In the same group of wells, the groundwater is guided to circulate in the upper and lower layers by the permeable structure of the well pipe and the water flow. Taking the upper layer well as an example, after the lower layer water is pumped up to the upper layer by the pump, part of it will be tortuously diffused through the permeable structure of the upper layer, fully contacting with the surrounding rock and soil, and promoting the mixing of the medicine; part of it will flow back and recirculate to form a stable small hydraulic cycle. When the upper layer water flows down to the lower layer, it will be mixed twice near the pump suction port to enhance the repair efficiency. Specifically, the inner layer of the well pipe 304 stainless steel slit (slit width 1mm, spacing 8mm) cooperates with the outer layer of stainless steel wire mesh (mesh 2mm) and the middle 2-3mm crushed stone quartz sand layer to guide the water flow to be turbulent, so that the medicine is dispersed more evenly and the contact probability with pollutants is increased.

[0041] The two groups of wells cooperate to build a large hydraulic cycle. The water from the upper well flows horizontally to the water absorption area of ​​the lower well. The agent seeps into the stratum along the way, and part of the water enters the lower layer for circulation. The upper layer of the lower well flows back through the permeable structure and seeps into the surrounding strata before entering the lower layer for further pumping. In this process, the large cycle nests the small cycle. The horizontal water flow carries the agent to diffuse up to 20-30 meters. The upper and lower layers are alternately pumped and drained to achieve hydraulic jump layer transmission, forming a cross 3D hydraulic connection, ensuring that the agent is evenly dispersed in the gaps between rocks and soil, and deeply purifying groundwater. In the case of areas with faster water flow in the sand layer, the extraction and drainage rate is fine-tuned according to the water flow velocity monitoring data to maintain the uniformity of agent concentration and circulation stability. In the silty clay layer, pulse pressure is used to assist the agent to penetrate the stratum and enhance the repair effect.

[0042] For complex organic pollutants, if catalytic oxidation technology is required, one group of wells will inject oxidizing agents (hydrogen peroxide concentration 10%-15% solution, injection acceleration rate 3-5L / h), and the other group will inject catalytic agents (iron-based catalyst concentration 0.5-1g / L, injection acceleration rate 2-3L / h). The rate is precisely controlled so that the two are mixed in the circulating water flow between the two wells at a ratio of 1:0.8. For example, when treating pollution containing benzene series, the oxidizing and catalytic agents react rapidly in the rock pores and groundwater driven by water flow. Degrading benzene series into harmless substances, the reaction rate is increased by 60% compared with the traditional single agent injection. When treating chlorinated hydrocarbons, first inject a reducing agent (zero-valent iron dosage 10-15g / L, lasting 24 hours) into a group of wells for dechlorination biological reduction, then inject oxygen-rich water (dissolved oxygen content 8-10mg / L, flow rate 8-10L / h) for cleaning for 8 hours to improve the redox point, and finally inject a slow-release oxidizing agent (potassium permanganate slow-release granules, release rate 0.05g / h·m 3 ) Oxidation treatment, regulating the release rate according to the characteristics of the formation, and continuous purification.

[0043] Water samples are collected regularly from extraction wells, and professional equipment is used to accurately test indicators such as pollutant concentration, pH, and dissolved oxygen. After three months of operation, if local purification does not meet the standards, the reasons are deeply analyzed, such as abnormal water flow or failure of the agent, and the pump extraction frequency is adjusted or the adapter agent is replaced, the injection rate is reset, and continuous monitoring and optimization are carried out. After system repair, the concentration of groundwater pollutants is greatly reduced, the concentration of benzene series is reduced to below 0.1mg / L, phenolic substances are below 0.05mg / L, heavy metal lead content is within 0.01mg / L, cadmium content is below 0.002mg / L, and petroleum hydrocarbon content reaches 0.5mg / L standard. The water quality meets the industrial reuse standard, saving 800,000 yuan in water costs each year, reducing the risk of fines for pollution emissions by 1.2 million yuan, reducing the hidden dangers of soil pollution spread, protecting the surrounding ecology, and improving the environmental reputation of the factory, which helps to expand the market and sustainable development.

[0044] Example 2: Local groundwater pollution control in residential areas

[0045] A professional environmental monitoring team entered the residential area and used precision geophysical detection equipment and geological drilling technology to accurately determine the boundaries and depth range of the polluted area. The depth is approximately 8 to 12 meters below the surface, covering an area of ​​3,000 square meters, located under the community's green space and some residential buildings.

[0046] With the help of advanced water quality analysis instruments, water samples were comprehensively tested and the pollutants were identified as nitrogen and phosphorus nutrients (ammonia nitrogen concentration 2 mg / L, total phosphorus 0.5 mg / L), trace organic detergents (anionic surfactant content 0.3 mg / L) and heavy metals infiltrated from surrounding industrial activities (such as lead concentration 0.08 mg / L, cadmium concentration 0.02 mg / L) produced by the leakage of domestic sewage. Combined with the residential building layout, underground pipe network map and groundwater hydrological model, 6 groundwater wells were scientifically planned to be set up around the polluted area and at key nodes inside. The layout is in a grid shape, taking into account both the restoration effect and the principle of minimal interference with residents' lives, to ensure comprehensive and effective control and recycling treatment of polluted water bodies.

[0047] Low-noise, small-volume professional drilling equipment is used for construction. The wellbore diameter and verticality are strictly controlled. Special double-layer stainless steel well pipes are placed in order. A 0.35-meter-thick gravel filter layer with a particle size of 4-6mm is laid at the bottom to prevent the formation from blocking the well pipe. The groundwater pump 5 is accurately installed in the well pipe, and it is reliably suspended with a high-strength, corrosion-resistant steel wire rope 505. The feed port is accurately adjusted to the appropriate water level depth to ensure smooth and stable water extraction. The air inlet pipe 506, the air outlet pipe 507, and the chemical dosing pipe are carefully connected. Food-grade silicone sealing gaskets are used to ensure airtightness and watertightness at the connection. The air compressor 1, the chemical dosing device 3 and the ground PLC controller 2 are seamlessly connected. The verticality of the well pipe is monitored by a laser guide throughout the construction process to stabilize its error within ±0.5° to ensure stable and efficient operation of the system.

[0048] The technicians followed a strict process to comprehensively test the electrical performance, mechanical structural integrity and component connection reliability of the equipment. Based on the characteristics of pollutants and environmental standards, they used the intelligent algorithm model to preliminarily set the opening and closing cycle of the electromagnetic valve of the reagent dosing device 3 to 5 minutes on and 10 minutes off, and the flow parameter to 3-6L / h; the switching time logic of the electronic valve of the groundwater pump 5 was 3.5-4.5 seconds on and 8.5-9.5 seconds off at the air inlet, and 6.5-7.5 seconds on and 9.5-10.5 seconds off at the air outlet. The test pumping and dosing program was started, and the system dynamics were monitored in real time with high-precision pressure sensors and electromagnetic flowmeters. If the pumping pressure fluctuation exceeded ±0.1MPa or the reagent flow error exceeded ±5%, the switching time of the electronic valve at the air inlet was fine-tuned according to the feedback data, with an adjustment accuracy of 0.1 seconds each time. After repeated optimization, the system was ensured to operate smoothly and accurately control the reagent dosage and water flow dynamic balance.

[0049] Start the air compressor 1, and one group of underground water pumps 5 in the well will efficiently extract the lower layer of groundwater and discharge it to the upper layer after mixing with the reagents, while the other group will operate in the opposite direction. In the same group of wells, groundwater is driven by the permeable structure of the well pipe and the water level difference, and circulates stably between the upper and lower layers. To illustrate this, after the lower layer of water is pumped up to the upper layer by the pump, part of the water is evenly diffused through the stainless steel wire mesh on the outer layer of the well pipe and the middle filling medium, and fully interacts with the surrounding soil and groundwater through diffusion and infiltration, thereby improving the dispersion and reaction probability of the reagents; part of the water flows back to the pump body for recycling, forming local turbulence in the pump to enhance the mixing of the reagents, and constructing an efficient small hydraulic circulation system. Specifically, the inner and outer layer structures of the well pipe and the filling of crushed stone quartz sand cause the water flow to alternate between laminar flow and turbulent flow, enhancing the diffusion effect of the reagents and improving the repair efficiency.

[0050] The two groups of wells work together to build a powerful hydraulic circulation network by taking advantage of the water level gradient, water flow inertia and pumping power difference. The water discharged from the upper well carries the reagent and flows horizontally and radially to the water absorption area of ​​the upper well, interacting with the depth of the formations with different permeability characteristics along the way. Some water enters the lower layer of the upper well to participate in the circulation; the upper layer of the upper well drains symmetrically backflows to the upper layer of the lower well, and then enters the lower layer for circulation after penetrating the surrounding formations through the permeable structure, achieving effective horizontal diffusion to 20-30 meters and hydraulic jump layer transmission driven alternately between the upper and lower layers, forming a cross 3D hydraulic connection, driving the reagent to deeply purify the polluted water in the rock and soil pores between the two wells, and degrading the concentration of pollutants. In case of local high permeability areas in sandy soil layers, the pumping rate is adjusted to maintain the horizontal hydraulic gradient at 0.008m / m to ensure uniform diffusion of the reagent; in low permeability clay layers, increasing the pulse pumping period promotes the penetration of the reagent into the formation and improves the repair effect.

[0051] In view of the heavy metal and organic composite pollution, the chemical precipitation-redox synergistic technology is adopted. Chelating agent (ethylenediaminetetraacetic acid disodium concentration 2-3g / L, injection rate 4-6L / h) and reducing agent (sodium sulfite concentration 5-8g / L, injection rate 3-5L / h) are injected into one group of wells to precipitate heavy metal ions and partially reduce high-valent metals to low-valent and easily precipitated states; another group of wells are injected with Fenton reagent-type strong oxidant (hydrogen peroxide concentration 8%-12%, ferrous sulfate concentration 2-3g / L, mixed and added at a volume ratio of 5:1, at a rate of 4-6L / h), and the oxidizing agent and the reducing agent are controlled to be mixed in the circulating water flow at a ratio of 2.5:1. For example, in treating lead-cadmium-organic chlorine complex pollution, chelating agents capture lead and cadmium into precipitates, reducing agents reduce part of the high-valent chromium to precipitate, and Fenton reagents produce strong oxidizing free radicals to degrade organic chlorine. After multiple rounds of cycles, the concentration of pollutants is greatly reduced, and the ammonia nitrogen concentration is reduced to below 0.2 mg / L, the total phosphorus to within 0.05 mg / L, the anionic surfactant content to below 0.03 mg / L, the heavy metal lead content to within 0.005 mg / L, and the cadmium content to below 0.001 mg / L, thereby improving the water quality to above the second level of the drinking water source water quality standard to ensure the safety of residents' water use.

[0052] Collect well water samples regularly according to the specifications, and analyze all indicators with high-precision equipment such as inductively coupled plasma mass spectrometer (ICP-MS) and gas chromatography-mass spectrometry (GC-MS). If monitoring finds that the local water quality fluctuates and does not meet the standards, quickly trace the source and investigate. If the uneven distribution of the reagents is caused by uneven formation permeability, fine-tune the frequency of the well water pump in the corresponding area, increase or decrease the extraction volume by 10%-20% to improve the water flow field; if the reagent precipitation blocks the formation pores, pulse inject an appropriate amount of acid cleaning agent (hydrochloric acid concentration 0.5%-1%, injection volume 1-2L) to dredge, restart the cycle and repair; if microbial growth affects the repair, add antibacterial agents (chlorine dioxide concentration 0.2-0.3mg / L, addition amount 0.5-1L / h) to control the bacterial flora, and continuously optimize the system dynamically to ensure that the groundwater is stable and meets the standards, restore ecological functions, and improve the quality of the residential environment and the health and well-being of residents.

[0053] 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. A three-dimensional well group structure for in-situ groundwater remediation, characterized in that: The well group structure comprises an air compressor (1), a PLC controller (2), a reagent dosing device (3), a groundwater well (4) and a groundwater pump (5); The underground water well (4) is a special stainless steel well pipe, which is composed of two layers, an inner layer of 304 stainless steel with slits, and an outer layer of a stainless steel wire mesh structure. The middle of the two layers is filled with crushed stones and quartz sand with a particle size of 2-3 mm. The whole well pipe is a water-permeable structure. The well pipe has an intermediate blocker (401) at the middle position, which divides the well pipe into two parts, the upper and lower parts, and the middle part is a water-impermeable structure. The groundwater pump (5) comprises a pump body (501), the pump body (501) is suspended in a groundwater well (4) by means of a steel wire rope (505), a feed port (502) is arranged at the bottom end of the pump body (501), and the feed port (502) is immersed in groundwater, a water outlet pipe (503) is arranged on the outer surface of the pump body (501), and one end of the water outlet pipe (503) away from the pump body (501) penetrates through the intermediate blocker (401) and extends to the other side of the intermediate blocker (401), and the pump body (501) is provided with a feed port (502) at the bottom end of the pump body (501), and the feed port (502) is immersed in groundwater, and a water outlet pipe (503) is arranged on the outer surface of the pump body (501), and one end of the water outlet pipe (503) away from the pump body (501) penetrates through the intermediate blocker (401) and extends to the other side of the intermediate blocker (401), and the pump body (501) is provided with a feed port (502) at the bottom end of the pump body (501). 01) is provided with a medicine dosing pipe (504) on its outer surface, the top end of the medicine dosing pipe (504) is connected to the medicine dosing device (3), the upper surface of the pump body (501) is fixedly connected with an air inlet pipe (506) and an air outlet pipe (507), and the top end of the air inlet pipe (506) and the top end of the air outlet pipe (507) are both connected to the air compressor (1), and electromagnetic valves are installed inside the air inlet pipe (506) and the air outlet pipe (507), and the electromagnetic valves are connected to the PLC controller (2) through wires.

2. A three-dimensional well group structure for in-situ groundwater remediation according to claim 1, characterized in that: The width of the slits in the inner layer of the groundwater well (4) is 0.5-1.5 mm, the slits are evenly distributed and the distance between adjacent slits is 5-10 mm. The mesh size of the stainless steel wire mesh structure in the outer layer of the groundwater well (4) is 1-3 mm. The intermediate barrier (401) is made of rubber and has a thickness of 5-10 mm.

3. A three-dimensional well group structure and application method for in-situ groundwater remediation according to claim 1, characterized in that: The drug dosing pipe (504) is made of polyvinyl chloride and has an inner diameter of 3-5 mm. A sealing gasket made of rubber is provided at the connection between the drug dosing pipe (504) and the pump body (501).

4. A three-dimensional well group structure and application method for in-situ groundwater remediation according to claim 1, characterized in that: A piston (508) is sealingly slidably disposed inside the pump body (501), and a spring (509) is installed on the bottom surface of the piston (508).

5. A three-dimensional well group structure and application method for in-situ groundwater remediation according to claim 4, characterized in that: A hollow limiting ring (510) is installed on the inner wall of the feed port (502), the upper surface of the hollow limiting ring (510) is connected to the bottom end of the spring (509), a spherical ball (511) is arranged inside the hollow limiting ring (510), and when the spherical ball (511) is located at the bottom of the hollow limiting ring (510), it maintains a seal with the inner wall of the feed port (502).

6. An application method of a three-dimensional well group structure for in-situ groundwater remediation, characterized in that: The method comprises the following steps: S1. Well group construction and equipment installation: Determine the location and number of groundwater wells based on the characteristics, scope and hydrogeological conditions of the groundwater pollution area, plan the layout to ensure comprehensive coverage and efficient treatment of the pollution area, and strictly control the verticality error within ±0.5° when digging wells. The diameter should be adapted to the well pipe specifications and meet the construction standards; S2. System debugging and parameter setting: Check the appearance, component connections, and electrical system of the equipment in detail. Set the opening and closing time of the solenoid valve of the reagent dosing device (3) and the opening and closing time of the electronic valve of the underground water pump according to the pollution degree, pollutant characteristics, and treatment objectives. When trying to pump water for dosing, if the water pump is unstable, fine-tune the opening time of the electronic valve at the air inlet every 0.5 seconds until it is stable, so that the pumping pressure fluctuation range is within ±0.1MPa and the reagent flow error is within ±5%; S3. Groundwater circulation and purification treatment: S301: Start the air compressor (1), and the groundwater pumps of one group of groundwater wells (4) pump the lower layer water to the upper layer, and the other group pumps the upper layer water to the lower layer. Each pump accurately injects the medicine through the medicine injection pipe at a set rate. The medicine and groundwater are mixed in the groundwater pump. In the same group of groundwater wells (4), the groundwater circulates in the upper and lower layers due to the water permeation of the well pipe and the flow direction of the inlet and outlet water. Due to the changes in water level and water pressure, after the lower layer water is pumped into the upper layer, part of it diffuses to the surrounding area through the water permeation part of the upper layer, and part of it enters the pump for circulation. After the upper layer water flows down to the lower layer, it circulates in a similar way, forming a small hydraulic circulation in the well; S302, between the two groups of groundwater wells (4), pumping up and discharging down and pumping down and discharging up are coordinated, and a large hydraulic cycle is constructed according to the water level difference, water flow inertia and pumping power. The water discharged from the groundwater well (4) with pumping down and discharging up will flow horizontally to the water absorption area of ​​the groundwater well with pumping up and discharging down, and will carry the reagent to penetrate the stratum on the way. Part of the groundwater will enter the lower layer of the groundwater well (4) with pumping down and discharging up and then be pumped up for circulation. The water discharged from the lower layer of the groundwater well (4) with pumping up and discharging down will flow back to the water absorption area of ​​the groundwater well with pumping down and discharging down along the reverse horizontal flow, and will penetrate the surrounding strata through the permeable structure. Part of the groundwater will enter the upper layer and be pumped up for circulation again. In this process, the large cycle is nested in the small cycle, and the horizontal water flow carries the reagent to diffuse horizontally. The upper and lower layers are alternately pumped and discharged to realize hydraulic jump layer transmission, forming a cross 3D hydraulic connection, so that the reagent is evenly diffused in the rock and soil gap between the two wells, and fully reacts with the pollutants to purify the groundwater. S303. In view of the special remediation technology requirements, for the use of catalytic oxidation technology, an oxidizing agent is injected into one group of groundwater wells (4), and a catalytic agent is injected into another group of groundwater wells (4). The injection rate is controlled so that the two are mixed in the circulating water flow between the two groups of wells at a ratio of 1:0.5-1:2 to ensure that the agents react efficiently within a short period of time after contact, and fully exert the catalytic oxidation effect to degrade pollutants; for the oxidation + reduction technology to treat chlorinated hydrocarbons, a reducing agent is first injected into one group of groundwater wells (4) for dechlorination biological reduction treatment, and the treatment time is 2 hours. The time is set to 12-48 hours according to the pollution concentration, and then oxygen-rich clean water is injected into the groundwater well (4) for cleaning for 6-12 hours to increase the redox point, and then a slow-release oxidizing agent is injected from another group of groundwater wells (4) for oxidation treatment. The release rate of the slow-release oxidizing agent is controlled at 0.01-0.1 g / hour·cubic meter according to the amount of remaining pollutants and the characteristics of the formation. The repair efficiency is improved by optimizing the injection sequence and rate of the agent. According to water quality monitoring and water pump working conditions, the PID algorithm is used to fine-tune the switch of the groundwater pump electronic valve in time to maintain stable and efficient operation; S4. Water quality monitoring and system optimization: Collect water samples regularly to measure pollutant concentration, acidity, alkali, dissolved oxygen, and conductivity indicators, optimize the system based on the results, and adjust after analyzing the reasons when pollution does not meet the standards. If the reagent is not good, try replacing it with a small dose first, and observe the water quality for 1-2 days to determine whether to replace it completely. When replacing, reset the injection acceleration rate. If abnormal water flow affects the diffusion and circulation of the reagent, fine-tune the pump extraction frequency, and continuously monitor and optimize until the water quality meets the standards to ensure the repair effect and the efficient and stable well group structure.

7. The application method of the three-dimensional well group structure for in-situ groundwater remediation according to claim 6 is characterized in that: In the steps of well group construction and equipment installation, a 0.3-0.5 meter thick gravel filter layer is first laid at the bottom of the wellbore, and then the groundwater well (4) pipe is vertically and slowly placed therein, and a groundwater pump is installed in the groundwater well (4) pipe and is securely suspended with a steel wire rope. The feed port is immersed in water at an appropriate depth, and the air inlet pipe, air outlet pipe, chemical dosing pipe, air compressor (1), chemical dosing device (3) and ground PLC controller (2) are tightly connected. All interfaces are tightly sealed, and 10-20 mm stainless steel corrugated pipes are used for the air inlet and outlet pipes. 5-10 cm bentonite is filled on the well pipe and the wellbore wall for reinforcement.

8. The application method of the three-dimensional well group structure for in-situ groundwater remediation according to claim 6, characterized in that: In the horizontal water flow transmission of the large hydraulic circulation between the two groups of groundwater wells (4), the influence of the water flow on the diffusion of the agent is taken into consideration and the ratio of the pumping and drainage rates of the two wells is adjusted. When the water flow rate is low, the pumping rate of the upper well is appropriately reduced and the pumping rate of the lower well is increased to maintain the horizontal hydraulic gradient between the two wells within the range of 0.005-0.01 m / m, so as to ensure that the agent can overcome the water flow resistance in the horizontal direction and fully diffuse to the area 20-30 meters away from the well.

9. The application method of the three-dimensional well group structure for in-situ groundwater remediation according to claim 6, characterized in that: In the hydraulic jump layer transmission link between the upper and lower layers, it is optimized according to the lithological characteristics of different formations. In the sandy aquifer, its porosity is conducive to the rapid penetration of water flow and reagents, and the extraction frequency is set to once every 4-6 hours. In the silty clay aquifer, the porosity is small and the hydraulic conductivity is low. The extraction frequency is adjusted to once every 8-10 hours, and the extraction power is increased by 10%-15% in stages during the extraction process, so that the reagent can effectively break through the formation resistance and realize jump layer transmission. In the case of jump layer, if the concentration of the upper layer reagent is 30%-50% higher than that of the lower layer, the extraction parameters are automatically adjusted to slow down the upper layer pumping and speed up the lower layer pumping by 10%-20%. The balanced concentration promotes the two-way uniform diffusion of the reagent and enhances the 3D hydraulic connection repair efficiency.

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