Permeable reactive barrier circulation system for groundwater remediation

Abstract

The application discloses a permeable reaction wall circulating system for groundwater pollution remediation, which comprises a permeable reaction wall, a temporary sealing structure, a mechanical replacement device and a control system. When the performance monitoring unit in the permeable reaction unit of the permeable reaction wall detects that the performance of the reaction medium decays to a preset threshold, an output signal is sent to the control system and a central control room, a maintenance operator enters a maintenance operation room, a rolling barrier membrane unit is started, the whole reaction wall section is sealed, a lifting device is started to lift the permeable reaction unit to a replacement height, the permeable reaction unit is placed on a horizontal slide rail, is translated to a replacement position and is locked, the reaction medium is replaced, the permeable reaction unit is unlocked, the mechanical replacement device is started to reversely move the permeable reaction unit to the wall groove for resetting, and finally the barrier membrane is rolled up. The permeable reaction wall can be recycled and replaced quickly, the maintenance process is simplified, the remediation efficiency is improved, and long-term stable operation can be ensured.

Description

Technical Field

[0001] This invention relates to the field of groundwater pollution remediation technology, and in particular to a permeable reactive wall circulation system for groundwater pollution remediation. Background Technology

[0002] With the acceleration of industrialization and urbanization, groundwater is increasingly contaminated by heavy metals, organic matter, and other harmful pollutants, posing a potential threat to the ecological environment and human health. To achieve in-situ groundwater remediation, permeable reactive barrier (PRB) technology has been widely used in groundwater remediation projects because it can passively retain groundwater and utilize active materials to degrade or remove pollutants.

[0003] However, existing PRBs generally suffer from the following problems during long-term operation: First, it is inconvenient to replace the active material after it is consumed, usually requiring large-scale excavation or shutdown, resulting in high operating costs and low efficiency; Second, a single type of reaction layer is difficult to meet the removal needs of multiple pollutants, and the remediation effect is unstable; Third, the lack of a recycling mechanism leads to low material utilization, making it difficult to meet the needs of large-scale, long-term groundwater treatment.

[0004] Therefore, there is an urgent need for a permeable reactive wall technology that can enable the recycling of permeable reactive walls, simplify the replacement process, and simultaneously improve repair efficiency and stability, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] This invention provides a permeable reactive barrier circulation system for groundwater pollution remediation to solve the technical problems existing in the prior art. This system can realize the recycling and rapid replacement of permeable reactive barriers, which simplifies the maintenance process, improves the remediation efficiency, and ensures long-term stable operation.

[0006] The technical solution adopted by this invention to solve the technical problems existing in the prior art is: a permeable reactive wall circulation system for groundwater pollution remediation. This system includes a permeable reactive wall, a temporary sealing structure, a mechanical replacement device, and a control system. The permeable reactive wall is installed in a wall groove in the middle of a fixed wall, with an underground maintenance and operation room located above it. The permeable reactive wall has multiple load-bearing columns, and multiple vertically sealed permeable reactive units are installed between two adjacent load-bearing columns. The permeable reactive units are slidably and sealed to the load-bearing columns, and each permeable reactive unit has a fixing frame. A non-biological permeable reaction layer is fixedly connected to the upstream side of the fixed frame, and a biological permeable reaction layer is fixedly connected to the downstream side. Replaceable reaction media and their performance monitoring units are provided inside both the non-biological permeable reaction layer and the biological permeable reaction layer. The mechanical replacement device includes a circulating track and a conveying device. The circulating track includes a vertical track located inside the two load-bearing columns and two horizontal tracks connected to the two vertical tracks. The two horizontal tracks are located on the top surface of the fixed wall, perpendicular to the upper opening of the wall groove. Replacement positions are provided at the ends of the two horizontal tracks away from the upper opening of the wall groove. The unit is equipped with a positioning structure and a locking structure; the conveying device includes a lifting device, a translation device, and a horizontal rotation device. The lifting device is mounted on the load-bearing column, the translation device is located near the horizontal slide rail, and the horizontal rotation device is located in the changing operation chamber for switching the position of the permeation reaction unit between the vertical slide rail and the horizontal slide rail; the temporary sealing structure adopts a rollable barrier membrane unit, which is located upstream of the permeation reaction unit and installed on the load-bearing column; when the performance monitoring unit detects that the performance of the reaction medium has degraded to a preset threshold, it outputs a signal to the control system. In the central control room, the control system issues an alarm signal and automatically or manually triggers the replacement process: First, the roll-up barrier membrane unit is started, and the barrier membrane is lowered to seal the entire cross-section of the reaction wall. Then, the lifting device is started to raise the permeable reaction unit to the replacement height. The horizontal rotation device is used to place it on the horizontal slide rail, and the translation device is started to transport it to the replacement position and lock it. Maintenance personnel replace the reaction media in the non-biological permeable reaction layer and the biological permeable reaction layer. Then, the permeable reaction unit is unlocked, and the mechanical replacement device is started to move the permeable reaction unit in the reverse direction to reset it in the wall groove. Finally, the barrier membrane is rolled up, and the permeable reaction wall resumes operation.

[0007] Based on the above solution, the present invention has made the following improvements:

[0008] Both the horizontal slide rail and the vertical slide rail are equipped with rollers inside.

[0009] The lifting device is a winch or a chain lifting mechanism.

[0010] The horizontal rotation device adopts a gantry crane structure or an electric hoist.

[0011] The translation device is any one of the following: rack and pinion drive mechanism, chain traction drive mechanism, synchronous belt servo drive mechanism, and screw transmission mechanism.

[0012] The positioning structure consists of a limiting block and a buffer device.

[0013] The locking structure uses a mechanical pin for locking.

[0014] The locking structure also employs any one of the following: a snap-fit, a hydraulic jack, or a mechanical jaw to achieve secondary fixation.

[0015] The rollable barrier membrane unit uses HDPE membrane or composite geomembrane.

[0016] The non-biological permeable reaction layer is provided with a support structure on the outside, and its interior is filled with an adsorption medium, a chemical precipitation medium, and a redox medium; the bio-permeable reaction layer is provided with a support structure on the outside, and its interior is filled with a biological reaction medium, which includes a biological carrier and a microbial community.

[0017] The advantages and positive effects of this invention are:

[0018] Mechanized cyclic replacement: The use of a mechanical replacement device enables rapid circulation of the permeation reaction unit, avoiding the drawbacks of traditional PRB units that require excavation for replacement, and significantly improving operating efficiency and system continuity.

[0019] Multi-level synergistic remediation: The synergistic effect of the non-biological permeable reactive layer and the bio-permeable reactive layer can simultaneously remove heavy metals, nitrogen and phosphorus pollutants and organic pollutants from groundwater, thereby ensuring the long-term stability and applicability of the remediation effect.

[0020] High efficiency and economy: The system is deployed underground, making full use of underground space without occupying surface space; at the same time, it reduces manual maintenance and material waste, extends the service life of the system, and provides a more efficient, economical and sustainable solution for groundwater pollution remediation.

[0021] In summary, this invention, through the synergistic effect of a mechanized replacement mechanism and a composite reaction layer, achieves rapid replacement of the reaction medium and recycling of the permeable reaction unit. This simplifies the maintenance process, improves remediation efficiency, and ensures long-term stable operation, effectively overcoming the shortcomings of existing technologies. Furthermore, the permeable reactive wall circulation system of this invention is located within underground space, without occupying above-ground space. It overcomes the deficiencies of existing permeable reactive walls used for groundwater pollution remediation, such as difficulty in replacing active materials, low operating efficiency, unstable remediation effects, and insufficient material utilization. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a permeable reactive wall in an embodiment of the present invention;

[0023] A schematic diagram of the overall structure of a permeable reactive wall circulation system for groundwater pollution remediation;

[0024] Figure 2 This is a schematic diagram of the automatic replacement device in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the permeation reaction unit fixing frame in an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the permeation reaction unit in an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the internal structure of the permeation reaction unit in an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of an embodiment of the present invention.

[0029] In the diagram: 1 - load-bearing column, 11 - vertical slide rail, 12 - horizontal slide rail

[0030] 2 - Permeation reaction unit, 21 - Fixture, 22 - Non-biological permeable reaction layer, 23 - Biological permeable reaction layer, 3 - Fixed wall, 4 - Maintenance and operation room. Detailed Implementation

[0031] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0032] Please see Figures 1-6 A permeable reactive wall circulation system for groundwater pollution remediation, comprising a permeable reactive wall, a temporary sealing structure, a mechanical replacement device, and a control system.

[0033] The permeable reactive wall is set in the wall groove in the middle of the fixed wall 3, and a maintenance and operation room 4 located underground is provided above it. The permeable reactive wall has multiple load-bearing columns 11. Between two adjacent load-bearing columns 11, there are multiple permeable reactive units 2 that are sealed and connected vertically. The permeable reactive units 2 are slidably sealed to the load-bearing columns. The permeable reactive units 2 are provided with a fixed frame 21. A non-biological permeable reactive layer 22 is fixed to the upstream side of the fixed frame 21, and a biological permeable reactive layer 23 is fixed to the downstream side. Replaceable reaction media and their performance monitoring units are provided inside both the non-biological permeable reactive layer 22 and the biological permeable reactive layer 23.

[0034] The mechanical replacement device includes a circulating track and a conveying device.

[0035] The circulating slide includes a vertical slide 11 disposed inside the two adjacent load-bearing columns and two horizontal slide rails 12 connected to the two vertical slide rails 11. The two horizontal slide rails 12 are disposed on the top surface of the fixed wall 4 and perpendicular to the upper opening of the wall groove. A replacement position is provided at the end of the two horizontal slide rails 12 away from the upper opening of the wall groove, and a limiting structure and a fixing component are provided at the replacement position.

[0036] The conveying device includes a lifting device, a translation device, and a horizontal rotation device.

[0037] The lifting device is mounted on the load-bearing column, the translation device is located near the horizontal slide rail, and the horizontal rotation device is located in the changing operation room, used for the permeation reaction unit to switch positions between the vertical slide rail and the horizontal slide rail.

[0038] The temporary sealing structure uses a rollable barrier membrane unit, which is located on the upstream side of the permeation reaction unit and installed on the load-bearing column 1.

[0039] When the performance monitoring unit detects that the performance of the reaction medium has degraded to a preset threshold, it outputs a signal to the control system and the central control room. The control system issues an alarm signal and automatically or manually triggers the replacement process: First, the roll-up barrier membrane unit is started, and the barrier membrane is lowered to seal the entire cross-section of the reaction wall. Then, the lifting device is started to raise the permeable reaction unit to the replacement height. Then, the horizontal displacement device is used to place the permeable reaction unit on the horizontal slide rail. The translation device is started to transport it to the replacement position and lock it. The maintenance personnel replace the reaction medium in the non-biological permeable reaction layer and the biological permeable reaction layer. Then, the permeable reaction unit is unlocked, and the mechanical replacement device is started to move the permeable reaction unit in the reverse direction to reset it in the wall groove. Finally, the barrier membrane is rolled up, and the permeable reaction wall resumes operation.

[0040] The replacement process includes measures for forced water shut-off, gas emission, and explosion prevention. The maintenance control room is equipped with safety light curtains, door magnets, emergency stop buttons, and ventilation devices.

[0041] The aforementioned control system has two-way communication capabilities with the remote monitoring platform, enabling it to remotely upload operational data, issue alarms, and receive remote operation commands.

[0042] The aforementioned circulation system achieves fully automated closed-loop management of the permeable reactive barrier from normal operation, performance assessment, water sealing, lifting and repositioning, media replacement, return to sealing, and resumption of operation through multi-parameter online monitoring, automatic criterion triggering, and sequential control. The system collects pressure, flow rate, and water quality indicators in real time and compares them with set thresholds. When it is determined that the media performance has deteriorated or the effluent indicators exceed the standard, the control system lowers the barrier membrane to cut off the water flow, drives the winch to lift the reactive barrier unit to the replacement height, and sends it to the replacement room through gantry transfer and horizontal traction to complete the media replacement. Subsequently, the command unit returns to its original position along the original path and completes the seal confirmation, retracts the barrier membrane, and restores normal water flow. The entire process is equipped with interlock protection and abnormal alarms. In the event of leakage or power failure, the system will immediately stop to maintain a safe state and record operating data. The control logic presents a closed-loop process of "monitoring → assessment → execution → verification → recovery", with status feedback at each stage to ensure the safe and stable operation of the system.

[0043] The preferred option of the above scheme is explained in more detail below:

[0044] See Figure 2 Both the horizontal slide rail 12 and the vertical slide rail 11 are equipped with rollers. To ensure operational reliability and reduce friction, the rollers are supported by wear-resistant bearings, the rolling surfaces are coated with an anti-corrosion coating, and they can be lubricated regularly by an oil cup.

[0045] The lifting device is a winch or chain lifting mechanism, with vertical lifting drive: the rollers in the vertical slide rail 11 roll only in the vertical direction. Driven by a winch or chain lifting mechanism located at the top of the load-bearing column, the winch can be electric or hydraulically driven and equipped with a fall arrestor, upper / lower limit switches, and position sensors to achieve smooth lifting and lowering, and can automatically adjust the speed according to the lifting weight. Horizontal indexing drive: after the permeation reaction unit is lifted to the preset replacement height, it is guided into the horizontal slide rail 12 by a horizontal indexing device. The horizontal indexing device can be a gantry crane structure or an electric hoist installed in the maintenance control room. A horizontal indexing device using a gantry crane structure includes a gantry frame, with transverse guide rails and a slider on the crossbeam of the gantry frame. The slider is connected to the permeation reaction unit and is driven laterally by a motor or hydraulic cylinder, causing the permeation reaction unit to rotate from the vertical slide rail into the horizontal slide rail.

[0046] The translation device can employ any of the following mechanisms: rack and pinion drive, chain traction drive, synchronous belt servo drive, and screw drive. This avoids the slippage problem of traditional friction belt drives and provides greater traction and positioning accuracy. The transmission mechanism is equipped with a motor drive and a reducer, working in conjunction with an encoder for position feedback to achieve precise stopping.

[0047] The rack and pinion drive mechanism consists of a rack fixedly mounted on one side or bottom of a horizontal slide rail, parallel to the rail, providing a linear meshing trajectory; and a gear mounted on the output shaft of a drive motor, which is fixed to the bottom of the permeation reaction unit or the traction trolley. The gear meshes with the rack, and the rotation of the motor enables the permeation reaction unit to move linearly along the horizontal slide rail. Preferably, an encoder is installed at the end of the gear shaft for position feedback and precise stopping. If a chain-driven traction mechanism is used, the chain is laid along one side of the horizontal slide rail and driven by a fixed drive wheel. The permeation reaction unit moves by connecting to the chain via lugs or clamps. If a screw drive mechanism is used, the screw is laid along one side of the horizontal slide rail, and the nut is connected to the permeation reaction unit, driving the unit to move linearly along the horizontal slide rail.

[0048] The principle of synchronous belt servo drive mechanism is similar to that of chain traction drive mechanism, and will not be elaborated here.

[0049] A replacement position is provided at the end of the two horizontal slide rails 12 away from the upper opening of the wall groove. The replacement position is equipped with a positioning structure and a locking structure. The positioning structure can be a limit block plus a buffer device to ensure minimal impact when the permeation reaction unit stops operating. The locking structure uses a mechanical pin to lock the permeation reaction unit and can be used in conjunction with any one of hydraulic or pneumatic latches, hydraulic top blocks, and mechanical claws to achieve secondary fixation, ensuring that the permeation reaction unit does not loosen or shift during stabilization.

[0050] Temporary sealing: A roll-up barrier membrane unit, preferably an HDPE membrane or composite geomembrane, is installed upstream of the permeable reactive barrier. The membrane thickness is 1–3 mm, and the bottom is equipped with a sealing strip and a locking groove to ensure a tight seal. Before replacement, the unit can be automatically lowered or pulled out via its drive mechanism to form a temporary seal, blocking groundwater from continuing to flow through the work area and preventing contaminants from migrating during replacement. Membrane retraction and deployment can be achieved via a motor-driven reel, pneumatic telescopic arm, or spring drum, equipped with end sealing strips and positioning grooves to ensure a tight fit. After replacement, the membrane automatically rewinds or returns to its storage chamber.

[0051] The barrier membrane is preferably positioned within a sealed frame in front of the vertical slide rail, ensuring that it covers the entire cross-section of the reactive barrier when lowered. During lowering, the barrier membrane slides along a pre-set guide groove or lateral guide rail, conforming to the outer side of the vertical guide rail to form a continuous "temporary sealing wall." The width of the membrane should cover the entire cross-section of the permeable reactive barrier, forming a temporary water curtain after lowering to intercept upstream water flow and prevent contaminated water from continuing to pass through during replacement operations.

[0052] The operation steps for the permeable reaction unit circulation in the maintenance room are as follows: After the permeable reaction unit is transported to the maintenance room, it is first locked with a mechanical pin, and then secured to the guide rail with clips, hydraulic blocks, or mechanical jaws to ensure that it does not shift during replacement. Then, the non-biological permeable reaction layer 22 and the biological permeable reaction layer 23 are opened, the internally filled reaction medium is extracted or poured out, and new medium is added according to process requirements. After replacement, the non-biological permeable reaction layer 22 and the biological permeable reaction layer 23 are resealed, and an airtight / watertight check is performed. Once no leakage is confirmed, the locking of the permeable reaction unit is released, allowing it to run back to its original position along the original path, thus achieving automatic cyclic replacement of the permeable reaction wall.

[0053] The control system uses a PLC and features soft start and variable frequency speed regulation. It can automatically adjust speed and torque during lifting, rotation, and return to prevent impact loads. A redundant braking system is also included, which can automatically brake and maintain the position in case of abnormality or power failure. The barrier membrane deployment and retraction actions are interlocked with the conveyor drive to prevent replacement from starting before complete barrier treatment. Similarly, the unlocking action of the permeation reaction unit in the maintenance operating room is interlocked with the conveyor drive to prevent misoperation.

[0054] See Figure 4 The non-biological permeable reaction layer 22 is externally supported by a support structure, and internally filled with an adsorption medium, a chemical precipitation medium, and a redox medium. The adsorption medium is preferably activated carbon, used to adsorb organic pollutants; the chemical precipitation medium is preferably limestone, used to promote the precipitation of dissolved substances in the water; and the redox medium is preferably zero-valent iron, used to decompose chlorinated organic pollutants. The support structure adopts a mesh structure and fluid channels are provided inside the reaction layer to ensure smooth flow of groundwater and full contact with the reaction medium, thereby improving the pollutant removal efficiency.

[0055] See Figure 5 The biopermeable reaction layer 23 is also externally supported by a structure, which is filled with a bioreaction medium, including a biological carrier and a microbial community. The biological carrier provides a space for microorganisms to attach and grow, while the microbial community is used to degrade organic pollutants. The support structure adopts a mesh structure, which ensures that the water flow is evenly distributed within the reaction layer and in full contact with the reaction medium. Depending on the type of groundwater pollutants, a suitable microbial community can be selected to improve biodegradation efficiency.

[0056] In the optimized design, the non-biological permeable reaction layer 22 and the biological permeable reaction layer 23 work together: the non-biological reaction layer removes organic matter, heavy metals and chlorine-containing pollutants through media such as activated carbon, limestone and zero-valent iron, while the biological reaction layer further purifies the water quality through microbial degradation, thereby effectively avoiding secondary pollution that may be caused by traditional chemical treatment methods.

[0057] When the permeable reactive barrier is in operation, groundwater first flows through the abiotic permeable reactive layer 22. During this process, pollutants are effectively removed sequentially through adsorption, chemical precipitation, and redox reactions. Subsequently, the groundwater enters the biological permeable reactive layer 23, where pollutants are further treated through microbial degradation. In operation, groundwater enters the permeable reactive unit 2 from upstream, first passing through the abiotic permeable reactive layer 22, where adsorption, chemical precipitation, and redox reactions occur sequentially to remove heavy metals and organic pollutants. It then enters the biological permeable reactive layer 23, where residual organic matter is further degraded under the action of microbial communities, achieving deep purification.

[0058] The online monitoring unit tracks pressure difference, water quality indicators and media performance in real time. When it determines that the performance of the reaction layer has degraded to a set threshold, it outputs a signal to the PLC control system, which then issues a replacement command.

[0059] After the replacement process is initiated, the control system first lowers the roll-up barrier membrane to form a temporary seal, preventing groundwater from continuing to enter the work area. Then, the lifting device is activated, raising the permeation reaction unit along the vertical slide to the replacement height. It is then guided to the horizontal slide rail via a horizontal displacement device, and the translation device is activated to transport the permeation reaction unit to the underground maintenance control room. Inside the control room, the permeation reaction unit is locked in place, the old reaction medium is removed, and new reaction medium is refilled. After compaction and sealing checks are completed, the lock on the permeation reaction unit is released. The permeation reaction unit is then returned along its original path and lowered to the working position, where it is locked again. Once the PLC control system confirms that all permeation reaction units are in place, the barrier membrane is retracted, the permeable reaction wall resumes normal water flow, and the system re-enters the next operating cycle.

[0060] After the media replacement is completed, the permeable reaction unit is put back into operation, and the permeable reactive barrier continues to treat the contaminated groundwater. The cyclic operation and recording system records the replacement time and water quality parameters, and then enters the next cycle, thereby ensuring the continuity and stability of the remediation process.

[0061] The workflow of the above system:

[0062] Step 1: The groundwater undergoes primary purification before entering the permeable reaction unit. It first passes through the non-biological permeable reaction layer, where it sequentially completes adsorption, precipitation, and oxidation-reduction reactions, removing most of the heavy metals and inorganic pollutants.

[0063] Step 2: The deeply purified water continues to enter the biological permeable reaction layer. Under the action of functional microbial communities, residual organic pollutants are further degraded, achieving deep purification and water quality compliance.

[0064] Step 3: The monitoring unit detects differential pressure, water quality and media status in real time. If the performance degradation is detected to the predetermined threshold, a signal is transmitted to the PLC control system. The PLC control system sends a replacement signal and enters the replacement preparation state.

[0065] Step 4: The PLC control system controls the roll-up barrier membrane unit to lower the roll-up barrier membrane to block groundwater. The lifting device is activated to lift the permeation reaction unit along the vertical slide to the replacement height. It is then guided to the replacement position via the horizontal transfer device and compacted. After completing the airtightness / watertightness test and ensuring there is no leakage, the lock of the permeation reaction unit is released.

[0066] Step 5: The osmosis reaction unit is returned along the original path and lowered to the working position, automatically locking and sealing; the barrier membrane is retracted, and normal water flow is restored.

[0067] Step Six: The PLC control system records the replacement event and water quality data, and the system enters the next cycle to maintain the long-term stability and continuity of the groundwater remediation process.

[0068] The aforementioned circulation system employs an active control method, utilizing online monitoring of multiple parameters, automatic criterion triggering, and sequential control to achieve fully automated closed-loop management of the permeable reactive barrier from normal operation, performance assessment, water sealing, raising and lowering, media replacement, return to sealing, and resumption of operation; wherein:

[0069] 1) Monitoring steps: collect water quality parameters in real time, calculate the removal rate, continuously store and perform trend analysis; when the set multiple or the removal rate is lower than the threshold, generate a replacement criterion signal.

[0070] 2) Judgment steps: The PLC control system compares the threshold and trend, and determines whether the performance of the medium has deteriorated to the warning or replacement condition by combining multiple parameter weights. The alarm information and the unit number that needs to be replaced are displayed through the HMI.

[0071] 3) Water sealing step: First, open the bypass valve to maintain the upstream water level, then drive the roller to lower the HDPE barrier membrane along the guide groove to the bottom sealing groove, and press it with the pressure strip to form a temporary water seal. After confirming that the flow rate has dropped to zero, proceed to the lifting and rotating step.

[0072] 4) Lifting and shifting steps: Unlock the unit locking device, start the winch or chain lifting mechanism to lift the reaction unit along the vertical slide to the replacement height, engage the gantry transfer mechanism to guide it into the horizontal slide rail, and drive it to the replacement room through rack and pinion or chain traction, and automatically lock it at the positioning block.

[0073] 5) Media replacement procedure: Open the maintenance door, remove the waste media (vacuum suction or drawer unloading), fill with new adsorption media, chemical precipitation media and biological carrier according to the design, and after compaction, replace the cover plate and conduct airtight / watertight tests to ensure no leakage.

[0074] 6) Return sealing procedure: Release the lock, the reverse drive unit returns to the transfer position along the horizontal slide rail, and then descends to the working position along the vertical slide rail to confirm the seal.

[0075] 7) Recovery procedure: Retract the barrier membrane, enter the stable operation period and monitor the water quality in real time. If the indicators return to normal, clear the alarm and enter the next cycle.

[0076] The entire process is equipped with interlock protection and abnormal alarms. In the event of abnormalities such as leakage, power failure, or emergency stop triggering, the machine will be stopped immediately, the barrier membrane will be kept in the lowered state, and the operating data will be recorded. The control logic presents a closed-loop process of "monitoring → judgment → execution → verification → recovery". Each link is equipped with status feedback and safety interlocks to ensure the safe and stable operation of the system.

[0077] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A permeable reactive wall circulation system for groundwater pollution remediation, characterized in that, The system includes a permeable reactive barrier, a temporary sealing structure, a mechanical replacement device, and a control system. The permeable reactive wall is set in a wall groove in the middle of the fixed wall, and an underground maintenance and operation room is provided above it. The permeable reactive wall has multiple load-bearing columns, and multiple permeable reactive units with upper and lower sealing are provided between two adjacent load-bearing columns. The permeable reactive units are slidably sealed to the load-bearing columns. The permeable reactive units are equipped with a fixed frame. A non-biological permeable reactive layer is fixed to the upstream side of the fixed frame, and a biological permeable reactive layer is fixed to the downstream side. Replaceable reaction media and their performance monitoring units are provided inside both the non-biological permeable reactive layer and the biological permeable reactive layer. The mechanical replacement device includes a circulating track and a conveying device. The circulating slide includes a vertical slide inside the two load-bearing columns and two horizontal slide rails connected to the two vertical slide rails. The two horizontal slide rails are set on the top surface of the fixed wall and are perpendicular to the top opening of the wall groove. A replacement position is provided at the end of the two horizontal slide rails away from the top opening of the wall groove. A positioning structure and a locking structure are provided at the replacement position. The conveying device includes a lifting device, a translation device, and a horizontal rotation device. The lifting device is installed on the load-bearing column, the translation device is installed near the horizontal slide rail, and the horizontal rotation device is installed in the changing operation room for the permeation reaction unit to switch positions between the vertical slide rail and the horizontal slide rail. The temporary sealing structure adopts a rollable barrier membrane unit, which is set on the upstream side of the permeation reaction unit and installed on the load-bearing column; When the performance monitoring unit detects that the performance of the reaction medium has degraded to a preset threshold, it outputs a signal to the control system and the central control room. The control system issues an alarm signal and automatically or manually triggers the replacement process: First, the roll-up barrier membrane unit is started, and the barrier membrane is lowered to seal the entire cross-section of the reaction wall. Then, the lifting device is started to lift the permeable reaction unit until it is exposed in the wall groove. The horizontal rotation device is used to place it on the horizontal slide rail, and the translation device is started to transport it to the replacement position and lock it. The maintenance personnel replace the reaction medium in the non-biological permeable reaction layer and the biological permeable reaction layer. Then, the permeable reaction unit is unlocked, and the mechanical replacement device is started to move the permeable reaction unit in the reverse direction to reset it in the wall groove. Finally, the barrier membrane is rolled up, and the permeable reaction wall resumes operation.

2. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, Both the horizontal slide rail and the vertical slide rail are equipped with rollers inside.

3. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The lifting device is a winch or a chain lifting mechanism.

4. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The horizontal rotation device adopts a gantry crane structure or an electric hoist.

5. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The translation device is any one of the following: rack and pinion drive mechanism, chain traction drive mechanism, synchronous belt servo drive mechanism, and screw transmission mechanism.

6. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The positioning structure consists of a limiting block and a buffer device.

7. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The locking structure uses a mechanical pin for locking.

8. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 7, characterized in that, The locking structure also employs any one of the following: a snap-fit, a hydraulic jack, or a mechanical jaw to achieve secondary fixation.

9. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The rollable barrier membrane unit uses HDPE membrane or composite geomembrane.

10. The permeable reactive wall circulation system for groundwater pollution remediation according to claim 1, characterized in that, The non-biological permeable reaction layer is provided with a support structure on the outside, and its interior is filled with an adsorption medium, a chemical precipitation medium, and a redox medium; the bio-permeable reaction layer is provided with a support structure on the outside, and its interior is filled with a biological reaction medium, which includes a biological carrier and a microbial community.

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