In-situ groundwater heavy metal pollution remediation device

Abstract

The utility model discloses an in-situ groundwater heavy metal pollution remediation device. Comprising two permeable reactive barriers arranged at intervals in the groundwater pollution plume runoff direction. A filling cavity is formed between the two permeable reactive barriers, and filling materials are arranged in the filling cavity. According to the utility model, a double-unit permeable reactive barrier is adopted to carry out an in-situ remediation method, the first unit is filled with a zeolite and volcanic rock composite filter material to adsorb and capture heavy metal pollutants, and the second unit is filled with an active charcoal composite filler to further efficiently adsorb residual heavy metals. In addition, a plant planting zone is constructed for planting heavy metal hyperaccumulation herbaceous plants, pollutants such as heavy metal in underground water are thoroughly removed through the absorption and stabilization effect of plants, and the underground water is purified. The device adopts stable, economic, efficient and safe active filler to adsorb and remove heavy metals in underground water, and has the advantages of efficient restoration, strong applicability, ecological environmental protection and the like.

Description

Technical Field

[0001] The utility model relates to an in-situ groundwater heavy metal pollution repair device, belonging to the technical field of groundwater pollution repair. Background Art

[0002] With the acceleration of industrialization, heavy metal pollution in soil and groundwater is becoming increasingly serious, threatening human health and ecological security, and hindering sustainable green economic development. The sources of heavy metal pollution in soil are complex, such as atmospheric deposition, industrial wastewater, solid waste, and irrational use of pesticides and fertilizers. Heavy metal pollution has the characteristics of variable forms, high toxicity, and bioaccumulation, which can directly harm human health and the ecological environment through the food chain. It can be seen that the remediation of heavy metal pollution in soil and groundwater is imminent.

[0003] Groundwater pollution remediation is divided into in-situ remediation and ex-situ remediation. Permeable reactive wall (PRB) technology is an emerging in-situ technology for groundwater pollution remediation. Permeable reactive wall is a continuous wall filled with permeable reactive media installed in the underground aquifer to intercept groundwater pollution plumes. The wall is perpendicular to the flow direction of groundwater. When the pollution plume passes through the wall under the action of natural hydraulic gradient, the pollutants are precipitated, adsorbed, oxidized and reduced, and biodegraded in the wall and converted into environmentally acceptable substances, thereby reducing the concentration of groundwater pollutants and achieving the removal of pollutants.

[0004] The selection of permeable reaction wall medium materials is the key to the groundwater remediation effect. The medium includes zero-valent iron, zeolite, clay, activated carbon and carbon sources that enhance microbial activity. Biochar adsorption materials have the characteristics of large specific surface area, high porosity, simple preparation and low price, and have great potential in the field of heavy metal pollution remediation. The existing permeable reaction wall is generally formed by excavating a large area of ​​reaction wall trenches, filling the trenches with adsorption materials to form an active material wall to intercept pollutant plumes, and heavy metals are precipitated and adsorbed in the material wall to be removed, thereby achieving groundwater purification. As the operating time goes by, the reaction material filled in the wall is gradually blocked by the reaction products, the reaction capacity reaches saturation, the removal rate decreases, the wall fails, and due to the large filling volume of the reaction material, the material replacement is difficult. Therefore, it is urgent to optimize and improve the existing permeable reaction wall to solve the above technical problems. Utility Model Content

[0005] In response to the above problems, the present application provides an in-situ groundwater heavy metal pollution remediation device, which is based on the synergistic effect of high-efficiency adsorption-plant enhanced remediation, and continuously remediates groundwater heavy metal pollutants in situ through a permeable reaction wall. The pollutants can be completely removed, and the filler can be regenerated and reused. It has the advantages of simple construction, low installation cost, easy replacement of fillers, efficient remediation, strong applicability, small disturbance of groundwater flow field, and ecological protection.

[0006] To achieve the above-mentioned purpose, the in-situ groundwater heavy metal pollution remediation device of the utility model comprises two permeable reaction walls arranged at intervals along the runoff direction of the groundwater pollution plume; a filling cavity is formed between the two permeable reaction walls, and a filling material is arranged in the filling cavity.

[0007] Furthermore, a grid is arranged in the filling cavity, and the grid divides the filling cavity into a first unit and a second unit along the runoff direction of the groundwater pollution plume; a first filling material is arranged in the first unit, and a second filling material is arranged in the second unit.

[0008] Furthermore, the permeable reaction wall has a built-in steel frame, the steel frame is covered with a permeable geotextile, and the wall permeability coefficient is 2 to 6 times higher than the permeability coefficient of the nearby aquifer.

[0009] Furthermore, the distance between the two permeable reaction walls is 2 to 6 m.

[0010] Furthermore, the first filling material is a composite filter material of zeolite and volcanic rock, with a particle size of 2 to 8 mm.

[0011] Furthermore, the second filling material is an activated biochar composite filler, and the filler is spherical porous particles with a particle size of 2 to 3 mm.

[0012] Furthermore, gabion cages are provided in both the first unit and the second unit; and the filling material is provided in the gabion cages.

[0013] Furthermore, the size of the gabion cage is 0.5m*0.5m*0.8m, the mesh diameter is less than 15mm, and a permeable geotextile is arranged around the inside of the gabion cage.

[0014] This application has the following advantages:

[0015] (1) For the remediation of heavy metal pollution in groundwater, a double-unit permeable reaction wall in-situ remediation method is disclosed. The first unit is filled with zeolite and volcanic rock composite filter material to adsorb and capture heavy metal pollutants, and the second unit is filled with activated biochar composite filler to further efficiently adsorb residual heavy metals. In addition, a plant planting belt is constructed to plant heavy metal hyperaccumulator herbaceous plants. Through the absorption and stabilization effect of the plants, heavy metals and other pollutants in the groundwater are completely removed to purify the groundwater. The utility model adopts stable, economical, efficient and safe active fillers to adsorb and remove heavy metals in groundwater, and has the advantages of efficient remediation, strong applicability, and ecological protection.

[0016] (2) The reaction wall is composed of a steel frame, and the reaction unit is placed in the two walls. The reaction unit is of moderate size and is covered with a permeable geotextile on all sides. The geotextile is filled with active materials and then sealed to prevent the filling materials from loosening and losing. After the reaction unit is filled on the ground, it is lifted by a lifting equipment and placed in the reaction wall. The utility model overcomes the problems of the construction of traditional permeable reaction walls, which require large-scale excavation, difficulty in replacing reaction materials, difficulty in operation and management, and high costs.

[0017] (3) The device has large filler porosity and good permeability, which results in little disturbance to the groundwater flow field, effectively ensuring the activity of the filler and avoiding blockage of the reaction wall, allowing the pollution plume to flow smoothly through the reaction zone, thus achieving efficient and lasting removal of heavy metals in groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional view of a groundwater remediation device according to an embodiment of the present application;

[0019] Figure 2 Schematic diagram of a reaction unit in a reaction wall according to an embodiment of the present application.

[0020] In the figure: 1. Permeable reaction wall; 2. Grid; 3-1. First unit; 3-2. Second unit; 4. Reaction unit; 41. Purification filter material; 42. Activated biochar composite filler; 43. Hook; 5. Plant planting belt. DETAILED DESCRIPTION

[0021] The embodiments of the utility model are described in detail below with reference to the accompanying drawings.

[0022] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Example 1

[0026] from Figure 1 It can be seen that the in-situ groundwater heavy metal pollution remediation device of this embodiment includes two permeable reaction walls 1 spaced apart along the runoff direction of the groundwater pollution plume, a grid 2 between the two walls, and filling materials.

[0027] The permeable reaction wall adopts a double-unit form, including a first unit 3-1 and a second unit 3-2 arranged in sequence along the seepage direction of the pollution plume. The first unit is filled with a purification filter material 41, which is a composite filter material of zeolite and volcanic rock with a particle size of 2 to 8 mm. The second unit is filled with an activated biochar composite filler 42, which is a spherical porous particle with a particle size of 2 to 3 mm. The composition includes 50% to 65% bentonite-modified biochar, 5% to 10% zero-valent iron, 10% to 20% plastic clay, and 15% to 20% high permeability raw materials. Specifically, the bentonite-modified biochar is made by mixing bentonite and biochar and then pyrolyzing them. The particle size of the bentonite is 0.05 to 0.1 mm, the mass ratio of bentonite to biochar is 1:6 to 20, the pyrolysis temperature is 400 to 800 ° C, and the pyrolysis time is 30 to 60 minutes.

[0028] Example 2

[0029] As a further improvement of the above-mentioned embodiment, the above-mentioned permeable reaction wall has a built-in steel skeleton, and the steel skeleton is covered with a permeable geotextile. The steel skeleton is welded vertically and horizontally by multiple stainless steel solid tubes, with a diameter of 12 to 20 mm and a skeleton width of 30 to 50 cm. The permeability coefficient of the permeable geotextile is not less than 5.0*10-5m / s. The depth of the reaction wall is greater than the depth of groundwater pollution by 1m, and the spacing between two adjacent walls is 2 to 6m. The wall separates the area into an upstream water inlet area, a reaction area, and a downstream water outlet area. The permeability coefficient of the wall is 2 to 6 times higher than the permeability coefficient of the nearby aquifer, and increases step by step along the seepage direction of the groundwater pollution plume.

[0030] Example 3

[0031] As a further improvement of the above embodiment, Figure 2As shown, the purification filter material 41 and the activated biochar composite filler 42 are both filled in the reaction unit 4, and the reaction unit frame material is a gabion net, the gabion net cage size is 0.5m*0.5m*0.8m, and the net diameter is less than 15mm. At least two hooks 43 are set at both ends of the gabion net cage, and the vertically adjacent reaction units are connected by hooks in sequence, and the adjacent reaction units are connected in series, so as to keep the reaction units arranged stably, and the height of the reaction unit assembly reaches 0.5m above the groundwater level in the reaction wall. Permeable geotextiles are arranged around the inside of the gabion net cage, and the geotextiles are filled with active materials and then sealed to prevent the filling materials from loosening and losing. The reaction unit 4 can first fill the material on the ground, and then hoist it one by one into the reaction wall through the lifting equipment for layered discharge, so as to complete the full loading of the filler. When the filler is used for a long time, the water quality of the effluent decreases, and a new filler can be replaced.

[0032] Example 4

[0033] As a further improvement of the above embodiment, a plant planting belt 5 is constructed in the downstream water outlet area of ​​the permeable reaction wall. The length of the planting belt is more than 3m longer than the length of the reaction wall. The plant planting belt is planted with heavy metal hyperaccumulator herbaceous plants, including one or more of pointed-leaf dianthus, large-flowered coreopsis, alfalfa, Li's grass, pokeweed, Baoshan viola, cosmos, ryegrass, and centipede grass.

[0034] The groundwater heavy metal pollution plume flows into the first unit of the reaction wall, the purification filter material absorbs and captures a part of the heavy metals, and the polluted water body continues to enter the second unit, and the active filler further efficiently absorbs the residual heavy metals. The polluted water body flows out into the plant planting belt, and the heavy metals and other pollutants in the groundwater are completely removed through the absorption and enrichment of the plants.

[0035] The utility model is described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the utility model. Many other changes and modifications that do not depart from the concept and scope of the utility model should be considered as the protection scope of the utility model.

[0036] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0037] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. An in-situ groundwater heavy metal pollution remediation device, characterized in that: The invention comprises two permeable reaction walls which are arranged at intervals along the runoff direction of the groundwater pollution plume; a filling cavity is formed between the two permeable reaction walls, and a filling material is arranged in the filling cavity.

2. The in-situ groundwater heavy metal pollution remediation device according to claim 1, characterized in that: A grid is arranged in the filling cavity, and the grid divides the filling cavity into a first unit and a second unit along the runoff direction of the groundwater pollution plume; a first filling material is arranged in the first unit, and a second filling material is arranged in the second unit.

3. The in-situ groundwater heavy metal pollution remediation device according to claim 1, characterized in that: The permeable reaction wall has a built-in steel frame, and the steel frame is covered with a permeable geotextile. The permeability coefficient of the wall is 2 to 6 times higher than the permeability coefficient of the nearby aquifer.

4. The in-situ groundwater heavy metal pollution remediation device according to claim 1, characterized in that: The distance between the two permeable reaction walls is 2 to 6 meters.

5. The in-situ groundwater heavy metal pollution remediation device according to claim 2, characterized in that: The first filling material is a composite filter material of zeolite and volcanic rock, with a particle size of 2 to 8 mm.

6. The in-situ groundwater heavy metal pollution remediation device according to claim 2, characterized in that: The second filling material is an activated biochar composite filler, which is a spherical porous particle with a particle size of 2 to 3 mm.

7. The in-situ groundwater heavy metal pollution remediation device according to claim 2, characterized in that: Gabion cages are provided in both the first unit and the second unit; and the filling material is provided in the gabion cages.

8. The in-situ groundwater heavy metal pollution remediation device according to claim 7, characterized in that: The size of the gabion cage is 0.5m*0.5m*0.8m, the mesh diameter is less than 15mm, and a permeable geotextile is arranged around the inside of the gabion cage.

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