A pile-building device for ex-situ cleaning of contaminated soil

Abstract

The present invention provides a pile-building device for ex-situ cleaning of contaminated soil, comprising a plurality of vertically arranged support columns and a plurality of horizontally arranged permeability-enhancing layers, wherein the plurality of said permeability-enhancing layers are arranged in upper and lower positions, forming a pyramid shape as a whole, and the plurality of said support columns pass through the insertion holes provided in the permeability-enhancing layers, and the support columns and the permeability-enhancing layers are located in the pile body formed by the pile-building of the contaminated soil; the support columns are cylindrical, and a plurality of water-permeable holes are arranged on the side walls of the support columns; the permeability-enhancing layers comprise a top layer and a bottom layer, and the top layer and the bottom layer are both mesh structures, and the top layer and the bottom layer are separated to form a sandwich structure. This pile-building device for ex-situ cleaning of contaminated soil has high permeability of the contaminated soil and high efficiency of elution transmission, and effectively solves the problems of inadequate elution of the contaminated soil and accumulation and agglomeration of the eluted soil; it is an assembled pile-building device, which can be reused, and based on the characteristics of the equipment, it can be combined with other repair processes for composite repair and treatment.

Description

Technical Field

[0001] The invention relates to the technical field of soil pollution remediation, and in particular to a pile-building device for ex-situ cleaning of contaminated soil. Background Art

[0002] In recent years, soil and groundwater pollution problems have become increasingly prominent. Heavy metal and organic pollution remediation has become a common research hotspot at home and abroad, driving the application of soil remediation technology and the industrialization of green remediation. Over the past 20 years, my country has been rapidly narrowing the gap with advanced countries in remediation technology, equipment and large-scale application.

[0003] Among them, pile-building and leaching have attracted attention due to their simple operation, low cost, and suitability for large-scale soil pollution treatment. Studies have shown that pile-building and leaching have lower costs and larger treatment volumes, but they still face the technical difficulty of increasing the infiltration of contaminated soil. The pile-building and leaching technology first requires the contaminated soil to be piled up according to certain requirements. This patent mainly improves the pile-building method and its structural schematic diagram, overcomes the shortcomings of the prior art, solves the problem of low permeability of contaminated soil, and further improves the efficiency of pile-building and leaching.

[0004] At present, among the technologies for ex situ soil cleaning and remediation, heap leaching has been confirmed by many scholars to be simple to operate, low cost, and suitable for large-scale soil pollution treatment. Studies have shown that although column leaching has a better leaching effect, heap leaching has faster leaching kinetics, low cost, and large processing volume. Therefore, heap leaching has attracted much attention for the remediation of contaminated soil.

[0005] Gui Dawei et al. provided a contaminated soil pile circulation elution remediation device, in which the soil pile is arranged in the form of a soil pile trough, that is, an anti-seepage membrane is laid on the surrounding walls, and the cross-section is an inverted trapezoidal shape, which means that the pit is larger at the top and smaller at the bottom. It can be a trapezoidal trough or a funnel-shaped or other suitable form, and the inner wall can be in the form of a natural slope. The top of the soil pile trough refers to the top of the pit opening.

[0006] Zhang Ruzhuang et al. mentioned a contaminated soil heap extraction-injection combined remediation device, which includes a water collecting pipe, extraction pump, injection pump and reagent container set in the contaminated soil, and extracts and injects soil leaching liquid into the contaminated soil pile to achieve the purpose of efficient soil leaching and pollutant removal, and reduce the investment in leaching equipment. At present, most of the domestic heap construction methods focus on the overall design of the remediation process, and there are few detailed reports on the design based on the soil heap itself.

[0007] Heap building technology is widely used in the mining industry, including multiple heaps, multi-layer heaps, slope heaps, hoisting heaps, blasting heap building and other methods. Due to the nature of the minerals, the heap has good permeability, which is conducive to leaching operations. It can also reduce the pressure per unit area or loosen the surface of the heap, which is conducive to leaching. In the practice of heap building of contaminated soil, due to the differences in the properties of the contaminated soil and the different permeabilities, the transmission efficiency of the leaching liquid after heap building is low. Therefore, it is necessary to design a soil heaping method for the contaminated soil. Summary of the invention

[0008] In view of this, the present invention aims to overcome the defects existing in the above-mentioned prior art and provide a pile-building device for ex situ cleaning of contaminated soil, which mainly solves the problems of low permeability of contaminated soil and low transmission efficiency of eluent.

[0009] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0010] A pile-building device for ex-situ cleaning of contaminated soil, comprising a plurality of vertically arranged support columns and a plurality of horizontally arranged permeability-enhancing layers, wherein the plurality of permeability-enhancing layers are arranged in upper and lower positions to form a pyramid shape as a whole, and the plurality of support columns pass through insertion holes provided in the permeability-enhancing layers, and the support columns and the permeability-enhancing layers are located in a pile body formed by the contaminated soil pile-building;

[0011] The support column is a cylindrical column, and a plurality of water-permeable holes are arranged on the side wall of the support column. The permeability enhancement layer includes a top layer and a bottom layer, and both the top layer and the bottom layer are mesh structures, and the top layer and the bottom layer are separated to form a sandwich structure.

[0012] Furthermore, the support column comprises a main support column and a plurality of side support columns, the main support column is located at the center of the pile body, and the plurality of side support columns are located around the pile body and are evenly distributed along the center of the pile body.

[0013] Furthermore, the support column and the permeability-enhancing layer are both filled with fillers for permeability-enhancing.

[0014] Furthermore, the filler includes but is not limited to one or more of quartz sand, permeable stone or pebbles;

[0015] Furthermore, several kinds of adsorptive materials and / or several kinds of solidifying / stabilizing pharmaceutical materials are added into the filler.

[0016] Furthermore, end caps are fixedly mounted on the top and bottom ends of the support column.

[0017] Furthermore, a baffle is provided at the edge of the bottom layer of the permeability enhancement layer, the baffle is a mesh structure, the baffle is rotatably connected to the bottom layer through a hinge structure, and a second plug plate is vertically fixed to the side of the baffle away from the bottom layer;

[0018] A plurality of first plug plates are extended outward from the top layer of the permeation enhancement layer. Opposite through holes are provided on the first and second plug plates. The baffle plates are fixed in position by inserted screws.

[0019] A pile-building method for ex-situ cleaning of contaminated soil comprises the following steps:

[0020] S1: Arrange the support columns according to the insertion positions of the permeability enhancement layer. The main support column is located at the center of the soil pile, and 8 side support columns are distributed around the main support column according to the five-point method;

[0021] S2: Lay the first layer of contaminated soil, with the pile height reaching about 0.6m and the bottom of the pile being a square of 10m×10m;

[0022] S3: Setting up the bottom stainless steel mesh of the permeability enhancement layer, the through holes of the permeability enhancement layer are moved horizontally downward through the support column until it is laid flat on the soil pile;

[0023] S4: Spread a filler of a certain specification on the bottom layer, set up the top stainless steel mesh of the permeability-enhancing layer, and close the side opening of the permeability-enhancing layer by a baffle, so that the filling material is sealed in the two layers of steel mesh;

[0024] S5: According to steps S2 to S4, the contaminated soil is piled up to a height of about 0.6 m, and then a permeability enhancement layer is added;

[0025] S6: Continue to lay the contaminated soil, with a pile height of 0.5m. The top of the pile is a small square of 3m×3m. The pile of contaminated soil is completed. The completed pile is in the shape of a square semi-pyramid.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The pile-building device for ex-situ cleaning of contaminated soil has high permeability of the contaminated soil and high elution transmission efficiency, which effectively solves the problems of inadequate elution of the contaminated soil and accumulation and agglomeration of the elution.

[0028] (2) The heap-building device used for ex-situ cleaning of contaminated soil is an assembled heap-building device that can be reused and can be combined with other remediation processes for composite remediation and treatment based on the characteristics of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 This is a schematic diagram of the overall structure of a pile-building device for ex-situ cleaning of contaminated soil according to the present invention;

[0031] Figure 2 This is a schematic diagram of a top view of the structure of a pile-building device for ex-situ cleaning of contaminated soil according to the present invention;

[0032] Figure 3 It is a schematic side view of the structure of a pile-building device for ex-situ cleaning of contaminated soil according to the present invention;

[0033] Figure 4 This is a schematic diagram of the main support column structure of a pile-building device for ex-situ cleaning of contaminated soil according to the present invention;

[0034] Figure 5 This is a schematic diagram of the structure of the side support column of a pile-building device for ex-situ cleaning of contaminated soil according to the present invention;

[0035] Figure 6 The present invention is a schematic diagram of a baffle structure of a pile-building device for ex-situ cleaning of contaminated soil.

[0036] Description of reference numerals:

[0037] 1-contaminated soil; 2-first permeability enhancement layer; 3-second permeability enhancement layer; 4-side support column; 5-main support column; 6-filler; 71-top layer; 711-first plug plate; 72-bottom layer; 73-baffle; 731-second plug plate; 74-screw; 741-nut; 8-water permeable hole. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0040] 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected 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 by specific circumstances.

[0041] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments:

[0042] like Figure 1-Figure 6 As shown, a pile-building device for ex-situ cleaning of contaminated soil comprises a support column and a permeability enhancement layer, wherein the support column and the permeability enhancement layer are both located in a pile body formed by the pile-building of the contaminated soil 1;

[0043] The support column is a cylindrical column made of stainless steel plate material, filled with filler 6, the side wall of the support column is covered with water-permeable holes 8, and the top and bottom ends of the support column are screwed with end caps;

[0044] For ease of assembly, the permeability enhancement layer includes a top layer 71 and a bottom layer 72, both of which are made of stainless steel mesh. The stainless steel mesh is generally less than 10 meshes according to the particle size of the soil used for the pile. The top layer 71 and the bottom layer 72 are separated to form a sandwich structure. The thickness of the permeability enhancement layer sandwich is 15 cm. The top layer 71 and the bottom layer 72 are filled with filler 6.

[0045] The filler 6 includes but is not limited to one or more of quartz sand, permeable stone or pebbles, which are used to increase the permeability of the pile, and several adsorbent materials such as biochar, activated carbon, etc. can be added to the filler 6 to adsorb harmful substances, and several solidifying / stabilizing agent materials such as sepiolite, calcium carbonate, magnesium-based mineral materials, etc. can also be added to increase the additional function of the permeability layer;

[0046] The supporting columns include 1 main supporting column 5 and 8 side supporting columns 4. The main supporting column 5 is a circular tube with an outer diameter of 150 cm, an inner diameter of 145 cm, and a height of 2 m. The main supporting column 5 is located at the center of the pile; the side supporting columns are circular tubes with an outer diameter of 100 cm, an inner diameter of 95 cm, and a height of 1.6 m. The 8 side supporting columns 4 are located around the pile and evenly distributed along the center of the pile.

[0047] The permeability enhancing layer comprises a first permeability enhancing layer 2 and a second permeability enhancing layer 3. The permeability enhancing layer is arranged horizontally, and the first permeability enhancing layer 2 is located above the second permeability enhancing layer 3. To facilitate the pile building, the size of the first permeability enhancing layer 2 is smaller than that of the second permeability enhancing layer 3, and the sizes of the first permeability enhancing layer 2 and the second permeability enhancing layer 3 match the size of the piled soil. In some embodiments, the size of the first permeability enhancing layer 2 is 5m×5m, and the size of the second permeability enhancing layer 3 is 8m×8m. The support column passes through the plug hole provided in the permeability enhancing layer, and the sizes of the support column and the plug hole match, so that the support column supports the permeability enhancing layer and prevents the permeability enhancing layer from tilting.

[0048] In order to prevent the filler 6 from falling, a baffle 73 is provided at the edge of the bottom layer 72 of the permeation layer. The baffle 73 is a stainless steel mesh. The baffle 73 is rotatably connected to the bottom layer 72 through a hinge structure. A second plug plate 731 is vertically fixed to the side of the baffle 73 away from the bottom layer 72.

[0049] A plurality of first plug plates 711 are extended outward from the top layer 71 of the permeability enhancement layer. The baffle plate 73 is rotated toward the top plate until the two are perpendicular. The through holes on the first plug plate 711 and the second plug plate 731 are opposite to each other. Screws 74 are inserted into the through holes to fix the position of the baffle plate 73.

[0050] The main functions of the infiltration layer and support column are to improve the permeability of contaminated soil, promote the mass transfer of elution agents, and improve elution efficiency.

[0051] A pile-building method for ex-situ cleaning of contaminated soil comprises the following steps:

[0052] S1: Arrange the support columns according to the insertion positions of the permeability-enhancing layer, with the main support column 5 located at the center of the soil pile, and 8 side support columns 4 distributed around the main support column 5 according to the five-point method;

[0053] During the construction process, at the designated repair site, precise measurement and positioning were carried out using instruments such as theodolite, level, 50m and 30m measuring tapes, and 10kg tensioners in accordance with the Engineering Surveying Specification (GB50026-2007) and design requirements;

[0054] S2: Lay the first layer of contaminated soil 1, with a height of about 0.6m and a bottom of the soil pile in a square of 10m×10m;

[0055] S3: Setting up the bottom 72 stainless steel mesh of the permeability enhancement layer, the through holes of the permeability enhancement layer are moved horizontally downward through the support column until it is laid flat on the soil pile;

[0056] S4: Spread a filler 6 of a certain specification on the bottom layer 72, set up a top layer 71 of the permeation layer with a stainless steel mesh, and close the side opening of the permeation layer with a baffle 73, and seal the filler 6 in the two layers of stainless steel mesh. In order to make the permeation layer form an integrated structure, a nut can be screwed into the lower end of the screw 74;

[0057] S5: According to steps S2 to S4, the contaminated soil 1 is piled up to a height of about 0.6 m, and then a permeability enhancement layer is added;

[0058] S6: Continue to lay the contaminated soil 1, with a pile height of 0.5m. The top of the pile is a small square of 3m×3m. The pile of contaminated soil 1 is completed. The completed pile is in a square semi-pyramid shape.

[0059] The completed soil pile is 2m high. This design parameter is based on the standard of slope stability safety factor in the Technical Code for Building Slope Engineering GB50330-2013 and meets the general working condition safety factor (§=1.35).

[0060] During use, in order to promote the mass transfer of eluting agents and improve the eluting efficiency, according to the process implementation situation, agent spraying pipes can be added to the top of the support column and the side of the infiltration layer, and the agent delivery efficiency can be further improved by spraying the agent into the support column and the infiltration layer; or a blower can be added to aerate the support column and the infiltration layer to increase the dissolved oxygen rate of the contaminated soil 1 and provide oxygen demand for the elution reaction.

[0061] Experimental example:

[0062] The pilot experiment of the patent design process set up a control group and an experimental group. The contaminated soil 1 was taken from a battery factory in Tianjin, and the lead content was as high as 3879 mg / Kg. Except for the different pile structures, the other experimental conditions of the two groups were consistent.

[0063] Among them, the control group contaminated soil 1 has no support column and permeability enhancement layer, and the pile of contaminated soil 1 is in a square semi-pyramid shape, with a bottom of 100cm×100cm square, a top of 30cm×30cm small square, and a pile height of 20cm;

[0064] The experimental group built contaminated soil 1 in layers according to the above-mentioned heap building method. The amount of contaminated soil 1 built was about 100 dm3. The contaminated soil 1 pile was in a square semi-pyramid shape, with a bottom of 100 cm × 100 cm square, a top of 30 cm × 30 cm small square, and a pile height of 20 cm.

[0065] The size of the first permeability enhancement layer 2 for the experiment is 50cm×50cm, and the size of the second permeability enhancement layer 3 for the experiment is 80cm×80cm. The permeability enhancement material inside the first permeability enhancement layer 2 for the experiment is a mixed material of quartz sand and pebbles, which is evenly distributed in the permeability enhancement layer according to a certain ratio; the permeability enhancement material inside the second permeability enhancement layer 3 is quartz sand and biochar, which is evenly distributed in the interlayer of the permeability enhancement layer according to a specific ratio;

[0066] The test support column device is made of PVC material. The main support column 5 is a circular tube with an outer diameter of 1.5 cm, an inner diameter of 1.3 cm, and a height of 20 cm. The tube wall is evenly provided with water-permeable holes 8. The side support is a circular tube with an outer diameter of 1.0 cm, an inner diameter of 0.8 cm, and a height of 15 cm. The tube wall is evenly provided with water-permeable holes 8, which are distributed around the main support column 5 according to the five-point method.

[0067] The support column is filled with quartz sand, a permeability enhancement material, and biochar, an adsorption material, in a ratio of 3:2;

[0068] During the experiment, an anti-seepage pad was set at the bottom of the contaminated soil 1, and a 20L glass dish was configured respectively; after the piles of the control group and the experimental group were built and stabilized, a layer of filter paper was laid on the top of the contaminated soil, and a 0.2 mol / L disodium ethylenediaminetetraacetic acid elution agent was used, which was sprayed on the top of the pile through the same number of spray pipes and a peristaltic pump with the same flow rate. The wetness of the contaminated soil 1 in the pile and the leachate in the glass dish were recorded every two hours, and a certain amount of samples were collected for analysis to test the heavy metal content in the soil and leachate.

[0069] The experimental results show that:

[0070] During the first leaching process, the contaminated soil 1 in the experimental group was infiltrated and penetrated by the leaching liquid within 4 hours, and leachate began to appear in the glass dish. The bottom contaminated soil 1 in the control group was not completely wetted within 4 hours. After spraying for another 2 hours, the bottom contaminated soil 1 began to be infiltrated, and there was no leachate in the bottom glass dish.

[0071] In the second leaching, under the protection of the permeability enhancement layer and the support column, the pile structure of the contaminated soil 1 in the experimental group was perfect, without obvious agglomeration deposition, while the contaminated soil 1 in the control group began to have leachate, which was darker in color, and due to the mass transfer path of the leaching liquid in the upper part of the pile, the agglomeration deposition of the contaminated soil 1 was significantly different from the dry cracking area;

[0072] After the third leaching, that is, within the same period of time, the lead removal rate of the contaminated soil 1 in the control group was only 68.75%, while the lead removal rate of the experimental group reached 80.12%.

[0073] The above experimental results indicate that the heap building method of the patent adopted by the experimental group is indeed beneficial to improving the mass transfer efficiency of the eluent, promoting the chelating reaction between the eluent and the contaminated soil 1, and thus improving the cleaning efficiency.

[0074] Note: For the fixed connection methods described in this article, unless otherwise specified, existing fixed connection methods such as threaded connection, welding, and bonding can be used.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pile-building device for ex-situ cleaning of contaminated soil, characterized in that: It comprises a plurality of vertically arranged support columns and a plurality of horizontally arranged permeability enhancement layers, wherein the plurality of permeability enhancement layers are arranged in an upper and lower position to form a pyramid shape as a whole, and the plurality of support columns pass through the insertion holes provided in the permeability enhancement layers, and the support columns and the permeability enhancement layers are located in a pile body formed by the pile of contaminated soil (1); The support column is a cylindrical column, a plurality of water-permeable holes (8) are arranged on the side wall of the support column, the permeability enhancement layer comprises a top layer (71) and a bottom layer (72), the top layer (71) and the bottom layer (72) are both mesh structures, and the top layer (71) and the bottom layer (72) are separated to form a sandwich structure; The support columns include a main support column (5) and a plurality of side support columns (4), wherein the main support column (5) is located at the center of the pile body, and the plurality of side support columns (4) are located around the pile body and are evenly distributed along the center of the pile body; The support column and the permeation-enhancing layer are both filled with fillers (6) for permeation-enhancing.

2. A pile-building device for ex-situ cleaning of contaminated soil according to claim 1, characterized in that: The filler (6) comprises quartz sand, permeable stone or pebbles.

3. A pile-building device for ex-situ cleaning of contaminated soil according to claim 2, characterized in that: Several kinds of adsorbent materials and / or several kinds of solidifying / stabilizing agent materials are added into the filler (6).

4. A pile-building device for ex-situ cleaning of contaminated soil according to claim 1, characterized in that: The top and bottom ends of the support column are both equipped with and fixed with end covers.

5. The pile-building device for ex-situ cleaning of contaminated soil according to claim 1, characterized in that: A baffle (73) is provided at the edge of the bottom layer (72) of the permeation enhancement layer. The baffle (73) is a mesh structure. The baffle (73) and the bottom layer (72) are rotatably connected via a hinge structure. A second plug plate (731) is vertically fixed to the side of the baffle (73) away from the bottom layer (72); The top layer (71) of the permeation enhancement layer is provided with a plurality of first plug plates (711) extending outwards, and the first plug plates (711) and the second plug plates (731) are provided with through holes in opposite positions, and the baffle plates (73) are fixed in position by plugged screws (74).

6. A method for building a pile for ex-situ cleaning of contaminated soil according to claim 5, characterized in that: The steps include: S1: Arrange the support columns according to the insertion hole positions of the permeability enhancement layer, the main support column (5) is located at the center of the soil pile, and the eight side support columns (4) are distributed around the main support column (5) according to the five-point method; S2: Lay the first layer of contaminated soil (1), with a height of 0.6 m and a 10 m x 10 m square at the bottom of the pile; S3: Setting up the bottom layer (72) of the permeability enhancement layer with a stainless steel mesh, wherein the through holes of the permeability enhancement layer are moved horizontally downward through the support column until being laid flat on the soil pile; S4: Spreading a filler (6) of a certain specification on the bottom layer (72), setting up a top layer (71) of a permeability-enhancing layer of stainless steel mesh, and closing the side opening of the permeability-enhancing layer with a baffle (73), so that the filling material is sealed in the two layers of steel mesh; S5: According to steps S2 to S4, the contaminated soil (1) is piled up to 0.6 m, and then a permeability enhancement layer is added; S6: Continue to lay the contaminated soil (1) to a pile height of 0.5m. The top of the pile is a small square of 3m×3m. The pile of contaminated soil (1) is completed. The completed pile is in a square semi-pyramid shape.

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