Permeable reactive barrier system and method for underground water pollution prevention and control

Abstract

The invention relates to a permeable reactive barrier system for groundwater pollution prevention and control and a use method, belongs to the technical field of groundwater pollution prevention and control, and provides the permeable reactive barrier system for groundwater pollution prevention and control in order to solve the problems that filler is inconvenient to replace and the effluent quality cannot be directly observed in an existing PRB device. Comprising a maintenance chamber, a monitoring sampling chamber and a v-shaped reaction wall, the v-shaped reaction wall is buried underground, the two ends of the v-shaped reaction wall extend out of the ground and are used for in-situ remediation of polluted underground water, and the maintenance chamber and the monitoring sampling chamber are arranged at the two ends of the V-shaped reaction wall in a surrounding mode respectively. According to the permeable reactive barrier system for underground water pollution prevention and control, the effluent quality of the V-shaped reactive barrier can be observed conveniently, the reaction filler device can be replaced in time, it is ensured that effluent meets the requirement, and meanwhile the reaction filler device can be replaced rapidly and conveniently without excavation.

Description

Technical Field

[0001] This invention belongs to the field of groundwater pollution prevention and control technology, specifically relating to a permeable reactive barrier system and method for groundwater pollution prevention and control. Background Technology

[0002] Permeable reactive walls (PRBs) are a passive treatment technology for in-situ remediation of groundwater pollution. The basic principle is to install a wall composed of reactive fillers along the path of the pollutant plume. As groundwater flows through, pollutants are removed through adsorption, sedimentation, oxidation-reduction, or biodegradation. Traditional PRBs often use diaphragm walls, completely buried underground. Once the filler becomes saturated or ineffective, the above-ground soil must be excavated for replacement, resulting in large-scale, time-consuming, and costly projects. Furthermore, the internal reaction state of the wall cannot be directly observed, hindering operation, maintenance, and effectiveness evaluation.

[0003] Commonly used PRB (Plasma Recycling) devices typically consist of a reaction tank, a packing layer, an influent system, and an effluent system. The tank is rectangular or trapezoidal in shape and entirely buried underground. The packing layer fills the tank and is generally designed for single-use or long-term operation. The inlet and outlet are located on opposite sides of the reaction tank, perpendicular to or at an angle to the groundwater flow direction. When the packing becomes saturated or its reactivity decreases, replacement requires complete excavation, resulting in high construction intensity, long cycles, and high costs, leading to maintenance difficulties. During operation, because the entire PRB device is underground, the reaction process cannot be directly observed, making it difficult to assess the remediation effect and packing condition in real time. Furthermore, its rigid structure makes it difficult to adapt to changes in different hydrogeological conditions and pollutant types, limiting its applicability.

[0004] Therefore, there is an urgent need to design a permeable reactive barrier system and method for groundwater pollution prevention and control to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a permeable reactive barrier system and method for groundwater pollution control, comprising a maintenance room and a monitoring and sampling room. The system is characterized by including a V-shaped reactive barrier, buried underground with both ends extending above ground level, for in-situ remediation of contaminated groundwater. The maintenance room and monitoring and sampling room are respectively located at both ends of the V-shaped reactive barrier. This invention's permeable reactive barrier system facilitates the observation of the effluent quality from the V-shaped reactive barrier, allows for timely replacement of the reactive packing device, ensures the effluent meets requirements, and enables rapid and convenient replacement of the reactive packing device without requiring full commissioning.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A permeable reactive barrier system for groundwater pollution control includes a maintenance room and a monitoring and sampling room. The system is characterized by further including a V-shaped reactive barrier, which is buried underground with both ends extending above ground level for in-situ remediation of contaminated groundwater. The maintenance room and the monitoring and sampling room are respectively located at both ends of the V-shaped reactive barrier.

[0008] Preferably, the tank body 1 and tank body 2, which are interconnected and have a V-shaped structure, and the reaction packing device are arranged in a V-shape. The tank body 1 and tank body 2 are buried underground and their ends extend above the ground. The maintenance room and the monitoring and sampling room are respectively surrounded at the ends of the tank body 1 and tank body 2. Water permeable holes are provided on the tank body 1.

[0009] Preferably, the reaction packing device includes reaction packing, a mesh sleeve, and a medium strip pull head, wherein the reaction packing is horizontally arranged inside the mesh sleeve, and the medium strip pull head is arranged at the upper end of the mesh sleeve.

[0010] Preferably, the reaction filler includes zero-valent iron composite material, activated carbon, zeolite, and bimetallic supported composite material.

[0011] Preferably, the monitoring sampling chamber also includes a sampling pipe, one end of which is connected to the tank body two, and a detection device is installed at the other end of the sampling pipe.

[0012] The second objective of this invention is to provide a method for in-situ remediation of contaminated groundwater, the method being based on a permeable reactive barrier system for groundwater pollution prevention, the method comprising:

[0013] The V-shaped reactive wall is buried in the downstream path of the contamination plume, so that tank 1, which contains the reactive packing device, is located downstream and tank 2 is located upstream.

[0014] A maintenance room is built at the upper end of the tank, a monitoring and sampling room is built at the upper end of the tank, and sampling pipelines are installed in the monitoring and sampling room.

[0015] During use, in the maintenance room, the saturated reaction packing device is pulled out from one end of the tank and replaced with a new reaction packing.

[0016] The beneficial effects of this invention are: This invention discloses a permeable reactive barrier system and method for groundwater pollution prevention and control. Compared with the prior art, the improvement of this invention lies in:

[0017] (1) This invention is designed with a “V-shaped reaction wall + top opening + reaction packing device with pull head”. The V-shaped reaction wall provides an inclined extraction path for the reaction packing device with pull head, and the V-shaped reaction wall has the function of guiding and converging water flow; the top opening and maintenance room provide a direct operating channel; the design of the reaction packing device with pull head allows the packing to be taken out and put in as a whole and quickly, like a “drawer”. The combination of these three features fundamentally avoids large-scale ground excavation, eliminates the need for large machinery excavation, and significantly reduces manpower, time and economic costs.

[0018] (2) The present invention provides a stable and convenient access point for water quality monitoring instruments through an independently set monitoring and sampling room and built-in sampling pipeline, making it possible to quantitatively evaluate the treatment effect. It overcomes the shortcomings of traditional underground PRB which is "invisible", realizes real-time and convenient monitoring of effluent water quality, and makes the operation effect quantifiable and evaluable, providing a scientific basis for optimizing operation and timely maintenance.

[0019] (3) The reaction packing device with pull head of the present invention allows for flexible replacement of different reaction packings inside according to different pollutants, so that the reaction wall of the present invention can cope with a variety of pollution scenarios and improve the adaptability of the reaction wall of the present invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the groundwater pollution prevention and control permeable reactive barrier system of the present invention in use;

[0021] Figure 2 This is a schematic diagram of the V-shaped groove structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the mesh sleeve structure of the present invention;

[0023] Among them: 1. V-shaped groove; 101. Groove one; 102. Groove two; 103. Water permeable hole; 2. Mesh sleeve; 201. Sealing cover; 202. Medium pull head. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are used for...

[0025] This invention is described, but should not be used to limit its scope.

[0026] Example:

[0027] See attached document Figure 1-3The permeable reactive barrier system for groundwater pollution control shown includes a V-shaped reactive barrier, a maintenance chamber, and a monitoring and sampling chamber. The V-shaped reactive barrier is buried underground with two ends extending above ground for in-situ remediation of contaminated groundwater. The maintenance chamber is located above ground and enclosed at one end of the V-shaped reactive barrier for replacing the filler material inside the V-shaped reactive barrier. The monitoring and sampling chamber is located above ground and enclosed at the other end of the V-shaped reactive barrier for testing the treated groundwater.

[0028] In this embodiment, the V-shaped reactive wall includes two interconnected tanks, 101 and 102, in a V-shape, and a reactive packing device. Tanks 101 and 102 are deeply buried underground in a V-shape, with their ends extending above ground. A maintenance chamber is provided around the end of tank 101 extending above ground, and a monitoring and sampling chamber is provided around the end of tank 102 extending above ground. The reactive packing device is movably disposed within the cavity of tank 101. The materials of tanks 101 and 102 in the V-shape are preferably stainless steel, environmentally friendly nylon plastic, or integrally molded plastic. The V-shaped reactive wall is used for in-situ remediation of contaminated groundwater. Tanks 101 also have several permeable holes 103 to facilitate water flow.

[0029] Specifically, the reaction packing device includes reaction packing, a mesh sleeve 2, and a medium strip pull head 202. The reaction packing is placed horizontally inside the mesh sleeve 2, and the medium pull head 202 is fixedly installed at the upper end of the mesh sleeve 2. A sealing cap 201 is provided on the mesh sleeve 2. The length of the mesh sleeve 2 is determined according to the required groundwater depth. The preferred materials are stainless steel metal mesh structure, environmentally friendly nylon plastic, and one-piece molded plastic.

[0030] In use, the mesh sleeve 2 containing the reaction packing is placed into the inner cavity of the tank body 101, with the medium pull head 202 positioned outside the opening at the end of the tank body 101 extending above the ground, facilitating later replacement of the reaction packing inside the mesh sleeve 2. The reaction packing is one or more of zero-valent iron composite material, activated carbon, zeolite, and bimetallic supported composite material; in actual use, one or more of these materials can be used.

[0031] The reaction packing device can be set into other regular shapes such as cylindrical or plate-shaped, as long as it is easy to be extracted and put in as a whole from the end of the tank 101.

[0032] In this embodiment, the maintenance chamber is constructed on one end of the tank body 101. It is a sealed box-like structure that encloses the opening at one end of the tank body 101. A maintenance cover is removably installed on the top of the maintenance chamber, specifically using a sealed overlap to ensure waterproofing and easy opening, facilitating maintenance personnel to enter the maintenance chamber on the ground and replace the reaction packing device through the opening at one end of the tank body 101. When it is necessary to replace the reaction packing device, maintenance personnel can enter the maintenance chamber, use a lifting device to pull the medium strip pull head 202, remove the old mesh sleeve 2 from the tank body 101, and insert the new reaction packing device.

[0033] In this embodiment, the monitoring sampling chamber is located at the other end of the tank body 102, opposite to the maintenance chamber, and encloses one end opening of the tank body 102. A monitoring sampling pipe is installed inside the chamber, which moves through the tank body 102 and is connected to the end of the tank body 102 via a flange for easy installation, disassembly, and sealing. A monitoring sampling port is provided at the end of the sampling pipe, which can be directly connected to water quality monitoring instruments (pH meter, online heavy metal concentration analyzer, etc.) via a flange or quick-release clip, or used for manual water sample collection.

[0034] In this embodiment of the application, the usage process of the groundwater pollution prevention and control permeable reactive barrier system is as follows:

[0035] (1) Installation phase

[0036] A trench was excavated downstream of the pollution plume, and a V-shaped reactive wall equipped with reactive packing was placed inside, positioning tank 2 102 upstream and tank 1 101, which contains the reactive packing device, downstream. Subsequently, an inspection room and a monitoring and sampling room were constructed, with the inspection room enclosing the port of tank 1 101 and the monitoring and sampling room enclosing the port of tank 2 102. The monitoring and sampling pipeline was connected, and the connection node of the monitoring and sampling pipeline was precisely set at the mainstream groundwater layer at the outlet of tank 1 101 (lower part of tank 1 101, at the same height as the core water layer of natural groundwater flow). This location is the main flow channel of the treated groundwater, with no stagnant water areas, ensuring that the water samples flowing into tank 2 102 are all fresh mainstream effluent from tank 1 101 after treatment with reactive packing, thus avoiding water quality deviations caused by sampling water from stagnant or marginal areas from the sampling source.

[0037] Specifically, the inlet of the monitoring sampling pipeline enters from the inner cavity of tank 2 102 and extends to the connection node between tank 1 101 and tank 2 102. The sampling port faces the outflow direction of tank 1 101, adopting a front-flow sampling design, so that the treated groundwater can flow directly into the sampling pipeline under the natural hydraulic gradient, without water flow bypass or buffering process. At the same time, the sampling pipeline adopts a short distance, no bends, and equal diameter design. The pipeline material is selected from smooth 304 stainless steel pipe, which minimizes water flow resistance and controls the transmission time of water sample from the outlet of tank 1 101 to the monitoring sampling port within a few seconds, completely eliminating the transmission lag of water flow in the pipeline.

[0038] A micro-overflow branch is added to the end of the sampling pipe. The end of the branch is connected to the lower part of the second tank 102, which allows the water in the pipe to flow back to the lower cavity of the second tank 102. This ensures that a small amount of water sample is always flowing and flowing back in the sampling pipe, preventing any stagnant water, pollutant sedimentation, or adsorption in the pipe. This ensures that the water sample in the pipe is always the real-time effluent from the first tank 101, avoiding monitoring deviations caused by water sample retention in the pipe or changes in water quality parameters (concentration of heavy metals in groundwater before and after treatment, pH value, etc.).

[0039] The monitoring sampling port adopts a flat structure without a water storage cavity. The monitoring instruments in the monitoring room, such as the pH meter and the online heavy metal concentration analyzer, are directly connected to the upper end of the monitoring sampling tube via quick-release clips or flanges. Finally, a hydraulic gradient matching design is carried out to ensure that the water flow state is consistent with the actual effluent. Specifically, to ensure that the connecting channel between Tank 101 and Tank 202 is set with a slight slope consistent with the natural hydraulic gradient of the groundwater (the slope ratio matches the hydraulic gradient of the groundwater in the site), the power of the suction pump in the monitoring sampling room is adjusted according to the depth of the treated groundwater to ensure that the water flow state and water quality parameters of the sampled water are completely consistent with the actual effluent from Tank 101, avoiding sampling deviations caused by external disturbances.

[0040] (2) Operation phase

[0041] Groundwater enters from one side of tank 101 under the natural hydraulic gradient and flows through the reaction packing. Pollutants undergo physical and chemical reactions (adsorption, reduction, precipitation) with the active materials in the reaction packing, thus being fixed or degraded. The purified water flows out from the other side of tank 101. During this process, the effluent quality can be monitored in real time through instruments connected to the sampling pipeline ports or through manual sampling to assess the treatment effect. The treated water samples and data can be continuously or intermittently acquired, enabling "visualization" of the operational status.

[0042] (3) Replacement of reaction packing

[0043] Replacement of the reactive packing material occurs when monitoring data shows a significant decrease in pollutant removal efficiency, indicating that the reactive packing material is approaching saturation. At this point, the maintenance cover of the inspection room is opened, and operators enter. Using a lifting device, the medium strip pull head is secured and pulled upwards to completely remove the failed reactive packing material from tank 101. Subsequently, a prefabricated device containing new reactive packing material is placed into tank 101, restoring it to its original position. The entire process requires no excavation of the surface soil.

[0044] (4) Reset phase

[0045] After the replacement is completed, close the maintenance cover, and the system can continue to operate.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A permeable reactive barrier system for groundwater pollution prevention, comprising a maintenance room and a monitoring and sampling room, characterized in that, It also includes a V-shaped reactive wall, which is buried underground with both ends extending above the ground. It is used for in-situ remediation of contaminated groundwater. The inspection room and the monitoring and sampling room are respectively located at both ends of the V-shaped reactive wall.

2. The permeable reactive barrier system for groundwater pollution prevention according to claim 1, characterized in that, The V-shaped reaction wall includes interconnected tank 101 and tank 2 102 in a V-shape and a reaction packing device. Tank 101 and tank 2 102 are buried underground in a V-shape and their ends extend above the ground. The maintenance room and the monitoring and sampling room are respectively located at the ends of tank 101 and tank 2 102. Water permeable holes (103) are provided on tank 101.

3. The permeable reactive barrier system for groundwater pollution prevention according to claim 2, characterized in that, The reaction packing device includes reaction packing, a mesh sleeve (2) and a medium strip pull head (202), wherein the reaction packing is horizontally arranged inside the mesh sleeve (2) and the medium strip pull head (202) is arranged at the upper end of the mesh sleeve (2).

4. A permeable reactive barrier system for groundwater pollution prevention according to claim 3, characterized in that, The reaction fillers include one or more of the following: zero-valent iron composite materials, activated carbon, zeolite, and bimetallic supported composite materials.

5. A permeable reactive barrier system for groundwater pollution prevention according to claim 2, characterized in that, The monitoring sampling chamber also includes a sampling pipe, one end of which is connected to the tank body 102, and a detection device is installed at the other end of the sampling pipe.

6. A method for in-situ remediation of contaminated groundwater, said method being implemented based on any one of the systems claimed in claims 1-5, characterized in that, The method includes: The V-shaped reactive wall is buried in the downstream path of the contamination plume, so that the tank 101 containing the reactive packing device is located downstream and the tank 202 is located upstream. A maintenance room is built at the upper end of tank 101, and a monitoring and sampling room is built at the upper end of tank 2102. Sampling pipes are installed in the monitoring and sampling room. During use, in the maintenance room, pull out the saturated reaction packing device from port 101 of the tank and replace it with a new reaction packing.

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