Combined structure for sewage in-situ osmotic reaction treatment under thick impermeable layer

Abstract

The invention discloses a combined structure for sewage in-situ permeable reaction treatment under a thick impervious layer. The combined structure comprises a plain concrete bottom layer (13) and a reaction trough, wherein the plain concrete bottom layer (13) is laid at the bottom of a foundation pit after the foundation pit is excavated, and the reaction trough is constructed on the plain concrete bottom layer (13) and filled with a water treatment reaction material (1). A water incoming direction filter layer (4) is arranged on the left side of the water incoming surface structure (2), and a water draining direction inverted filter layer (5) is arranged on the lower part of the right side of the water draining surface structure (3); the incoming water surface structure (2) and the drainage surface structure (3) respectively penetrate through the upper impermeable layer (m) and the middle permeable layer (n) from top to bottom and extend into the lower impermeable layer (k); and a filter bag (7) is arranged on the outer side of a water inlet of the water inlet pipe (6). According to the method, sewage purification treatment is achieved in situ, land resources are saved, the influence on the environment is reduced, pumping, transportation, treatment station treatment and later-period management operation of underground sewage are not needed, operation and maintenance are easy and convenient, the cost is low, investment is small, and benefits are good.

Description

Technical Field

[0001] This invention belongs to the field of groundwater pollution control engineering technology, specifically involving a combined structure for in-situ infiltration reaction treatment of underground sewage. It is particularly suitable for pollution control when groundwater flows are polluted, or when solid waste contains underground leachate or underground sewage flows due to rainwater leaching. It is especially applicable to the in-situ treatment of sewage under thick impermeable layers caused by leachate from garbage dumps, tailings ponds, and spoil heaps. It can also be used for the treatment of dam-type sewage in polluted streams on the surface. Background Technology

[0002] In real-world production and daily life, various pollutants are continuously generated. Despite the strict treatment measures taken by enterprises, it is still difficult to completely prevent trace (or large) pollutants from entering the soil and seeping into groundwater, thus impacting the environment through groundwater flow.

[0003] In typical scenarios, such as when a solid waste landfill foundation has a layered structure of "impermeable layer-permeable layer-impermeable layer," landfill leachate may seep down through localized defects in the upper impermeable system, entering the intermediate permeable layer (such as a sand layer or a fractured zone) to form a horizontal migration channel, and ultimately penetrating the weak areas of the lower impermeable layer to contaminate deep groundwater. Under these geological conditions, traditional vertical barrier technologies are insufficient to completely cut off the diffusion path of the contamination plume.

[0004] At the same time, historical environmental problems cannot be ignored, such as landfills, mine spoil heaps, tailings ponds, and certain solid waste landfills. Although pollution control projects have been implemented in these sites, some defects may still exist, leading to leachate leakage into the soil and contaminating groundwater.

[0005] Traditional methods for treating contaminated groundwater mainly involve collecting and transporting it to wastewater treatment plants via pipelines, or setting up on-site collection ponds for off-site treatment. For situations involving large contaminated areas and large volumes of water, these methods significantly increase the wastewater treatment load and operating costs.

[0006] Current reactive permeable walls (PRB) technology typically involves temporary steel plate support, excavation of a trench, filling with reactive material, and then removing the steel plates. Groundwater is purified as it flows through the reactive material. However, this technology has significant drawbacks:

[0007] (1) Poor geological adaptability: When the reactive material comes into direct contact with the permeable soil, it is easily encapsulated by mud or blocked by impurities. In the "upper-permeable-lower" impermeable layer structure, it is more prone to short-flow due to changes in hydraulic gradient.

[0008] (2) High maintenance costs: After the reactive materials fail, they need to be repeatedly excavated and replaced. For seepage problems that last for decades or even hundreds of years, such periodic engineering is neither economical nor sustainable.

[0009] (3) Depth limitation: When the thickness of the impermeable layer exceeds 10m or the depth of the groundwater flow layer is large, the excavation construction of conventional PRB will face technical and economic bottlenecks.

[0010] Therefore, it is particularly important to develop a sustainable, efficient, and long-term operational underground wastewater in-situ treatment facility suitable for deep impermeable strata (especially in the presence of multi-layered hydrogeological structures). The combined structure proposed in this invention effectively addresses the aforementioned technical challenges through the synergistic effect of modular reaction units and a hydraulic control system. Summary of the Invention

[0011] The purpose of this invention is to address various unreasonable shortcomings in current underground sewage treatment methods and to provide a combined structure for in-situ infiltration reaction treatment of sewage under thick impermeable layers that can achieve full-section seepage prevention treatment within the height range of underground sewage, with low investment, simple post-management and operation, low cost, and high efficiency. While ensuring that the direction and environment of groundwater flow are not changed, the sewage is treated in a process similar to natural flow. This not only saves land resources and reduces environmental impact, but also eliminates the need for underground sewage extraction, transportation, and treatment at treatment plants.

[0012] To achieve the above-mentioned objectives of this invention, the combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer is implemented using the following technical solution:

[0013] This invention discloses a combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer. It includes a foundation pit excavated at the narrowest point of the groundwater flow downstream of a landfill, followed by a plain concrete base layer laid at the bottom of the pit. A reaction tank, containing water treatment reaction materials, is constructed and filled on top of the plain concrete base layer. The reaction tank is a groove-shaped structure composed of an incoming water surface structure, a drainage surface structure, and a base plate of the tank structure. The incoming water surface structure faces the direction of the groundwater flow, while the drainage surface structure is parallel to and opposite the incoming water surface structure. The base plate of the tank structure is located above the plain concrete base layer. A filter layer is provided on the left side of the incoming water surface structure, and a reverse filter layer is provided on the lower right side of the drainage surface structure. The reverse filter layer prevents groundwater or debris from flowing back into the water treatment reaction materials through the drainage pipe, thus protecting the water treatment reaction materials. The incoming water surface structure and the drainage surface structure pass through the upper impermeable layer and the middle permeable layer from top to bottom, respectively, and extend into the lower impermeable layer. The reaction tank is located in an impermeable layer. Inlet pipes are embedded in rows on the upper left side of the reaction tank, within the reinforcing steel of the incoming water surface structure. The inlet of the inlet pipe is located in the filter layer in the direction of incoming water, and the outlet is located inside the reaction tank, facilitating the infiltration of wastewater from underground into the water treatment reaction material for purification. Drainage pipes are embedded in rows on the lower right side of the reaction tank, within the reinforcing steel of the drainage surface structure. The inlet of the drainage pipe is located inside the reaction tank, and the outlet is located in the reverse filter layer in the direction of drainage, allowing the infiltrated wastewater to flow underground after purification by the water treatment reaction material. Filter packs are arranged outside the inlet of the inlet pipes to further filter the underground wastewater before it enters the water treatment reaction material, ensuring that small particles do not enter the water treatment reaction material. The water treatment reaction material is stored in bags, packages, or cages within the reaction tank to treat the infiltrated wastewater.

[0014] Preferably, a filter material sealing plate is provided on the top of the filter layer in the direction of incoming water, and a filter material sealing plate is provided on the top of the reverse filter layer in the direction of outgoing water, for sealing the filter layer and reverse filter layer to prevent the upper soil from entering the filter layer and reverse filter layer.

[0015] Preferably, a horizontal impermeable layer is provided on the surface of the filter material sealing plate on the left side of the water inlet structure to prevent rainwater or surface water from entering the filter layer in the direction of water inlet; the surface of the impermeable layer on the upper right side of the drainage structure is a natural ground soil layer, which is used to repair the ground and plant turf for greening after compaction.

[0016] Preferably, a waterproof cover plate for water treatment reaction material is installed on the upper part of the reaction tank.

[0017] Preferably, the height H1 of the water inlet structure and the drainage structure extending into the lower impermeable layer is greater than 1000mm.

[0018] Preferably, the filter material built into the inlet water filter layer is coarse sand with a particle size of 10-40 mm, and the thickness b of the inlet water filter layer is not less than 1000 mm; the filter material built into the outlet water filter layer is coarse sand + medium-coarse stone, with the coarse sand particle size of 10-40 mm, the medium-coarse stone particle size of 30-50 mm, and the thickness c of the outlet water filter layer is not less than 600 mm.

[0019] Preferably, the inlet pipe is located at H6 below the top of the water inlet structure, where H6 is not less than 1200mm. At the same time, based on the elevation of the groundwater, it is ensured that the groundwater can flow into the water treatment reaction material. The filter bag is wrapped with coarse sand using geotextile. The coarse sand used is gravel with a particle size greater than 0.10mm, of which particles with a particle size greater than 0.50mm account for more than 50% of the total weight.

[0020] Preferably, the height of the drain pipe from the boundary line between the middle permeable layer and the lower impermeable layer is 250-350 mm.

[0021] Preferably, the thickness of the water inlet surface structure and the water outlet surface structure is not less than 300mm.

[0022] Furthermore, the spacing between the inlet pipes is 1700–2300 mm, arranged in a row along the length; the spacing between the outlet pipes is 1700–2300 mm, arranged in a row along the length; the height of the filter layer in the water inflow direction is H1 (height of the reactant material entering the lower impermeable layer) + H3 (thickness of the middle permeable layer) + H4 (thickness of the upper impermeable layer); the height of the reverse filter layer in the drainage direction is H7 (height of the reactant material entering the lower impermeable layer) + H3 (thickness of the middle permeable layer) above the boundary line between the middle permeable layer and the upper impermeable layer, where H7 is greater than 500 mm; the mass ratio of coarse sand to medium-coarse stone in the filter material built into the reverse filter layer in the drainage direction is (0.8–1.1):1.

[0023] This invention presents a combined structure for in-situ infiltration reaction treatment of wastewater under thick impermeable layers. By employing the above technical solutions and through the innovative design of "natural hydraulic drive + in-situ reaction barrier," it achieves efficient, low-cost, and sustainable treatment of underground wastewater. This solves the problems of high energy consumption, complex management, and secondary pollution associated with traditional methods, and has broad application prospects in contaminated site remediation and groundwater protection. Specifically, it is reflected in:

[0024] (1) High efficiency and energy saving, low operating cost. Wastewater purification is carried out by utilizing the natural flow of groundwater, without the need for additional power equipment (such as water pumps, aeration devices, etc.), saving electricity consumption and operation and maintenance costs; the reaction material adopts modular packaging (bag / cage packaging), and when replacing it, only the old packing material needs to be removed and the new packing material needs to be added, without the need for excavation and construction, which greatly reduces labor and maintenance costs.

[0025] (2) Environmentally friendly and ecologically compatible. It does not change the direction of groundwater flow or the structure of aquifers, avoiding the groundwater funnel or stratum subsidence problems that may be caused by traditional pumping treatment; the amount of earthwork excavation during construction is small, reducing the disturbance to the surrounding ecological environment, and it is particularly suitable for groundwater remediation in ecologically sensitive areas or urban built-up areas.

[0026] (3) Long-term stability and strong sustainability. Dual filtration (inlet filter layer + outlet filter layer) effectively prevents sludge accumulation, extends the service life of the reaction materials, and reduces the frequency of replacement; the used reaction materials can be centrally recycled and treated to avoid secondary pollution and meet the environmental protection requirements of green and low carbon.

[0027] (4) Flexible and easy to promote. The types of reaction materials (such as activated carbon, zero-valent iron, biological filler, etc.) can be adjusted according to the degree of pollution, and it is suitable for the simultaneous removal of multiple pollutants (COD, ammonia nitrogen, heavy metals, etc.); the modular design supports multiple sets of parallel operation, and the treatment capacity can be expanded as needed, making it suitable for contaminated sites of different sizes.

[0028] (5) Significant economic benefits. The construction cost is only 1 / 5 to 1 / 3 of that of traditional sewage treatment plants, and there is no need for long-term pumping and transportation, reducing the overall operation and maintenance cost by more than 60%; it saves land resources and is especially suitable for space-constrained areas (such as industrial sites, landfills, tailings ponds, spoil heaps, etc.), with a high rate of return on investment. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of a combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer according to the present invention.

[0030] The attached diagram is labeled as follows: 1-Water treatment reaction material; 2-Incoming water surface structure; 3-Drainage surface structure; 4-Incoming water direction filter layer; 5-Drainage direction reverse filter layer; 6-Inlet pipe; 6'-Drainage pipe; 7-Filter bag; 8-Filter material sealing plate; 8'-Reverse filter material sealing plate; 9-Horizontal impermeable layer structure; 10-Natural ground soil layer (i.e., planting soil layer); 11-Water treatment reaction material waterproof cover plate; 12-Base plate of material tank structure; 13-Plain concrete bottom layer; 14-Operating space; 15-Boundary line between the intermediate permeable layer and the lower impermeable layer; 15'-Boundary line between the intermediate permeable layer and the upper impermeable layer; 16-Underground sewage flow direction; m-Upper impermeable layer; n-Intermediate permeable layer; k-Lower impermeable layer.

[0031] Wherein: A - width of the reaction tank; B - width of the bottom plate of the tank structure; a - thickness of both sides of the reaction tank (i.e., thickness of the inlet water surface structure 2 and the drainage surface structure 3); b - thickness of the filter layer in the inlet water direction; c - thickness of the reverse filter layer in the drainage direction; e - width of the waterproof cover plate of the water treatment reaction material; H1 - height of the reaction material entering the lower impermeable layer; H2 - thickness of the bottom plate of the tank structure; H3 - thickness of the middle permeable layer (i.e., underground sewage layer); H4 - thickness of the upper impermeable layer; H5 - thickness of the natural ground soil layer (i.e., planting soil layer); H6 - distance between the inlet pipe and the top of the inlet water surface structure; H7 - height of the reverse filter layer in the drainage direction above the boundary line between the middle permeable layer and the upper impermeable layer. Detailed Implementation

[0032] To describe the present invention more clearly and completely, the following detailed description, in conjunction with the accompanying drawings and embodiments, provides a combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] Depend on Figure 1The cross-sectional view of the combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer of the present invention shows that the combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer of the present invention adopts an in-situ infiltration reaction wall. It includes a plain concrete base layer 13 laid at the bottom of the pit after excavation at the narrowest point of the groundwater flow downstream of the landfill, and a reaction tank filled with water treatment reaction material 1 on the plain concrete base layer 13. The reaction tank is a groove-shaped structure composed of a water inlet surface structure 2, a drainage surface structure 3, and a bottom plate 12 of the tank structure. The thickness of the water inlet surface structure 2 and the drainage surface structure 3 is not less than 300mm, wherein the water inlet surface structure 2 faces the groundwater. The water flow direction is set at 16. The drainage surface structure 3 and the incoming water surface structure 2 are parallel and opposite to each other. The bottom plate 12 of the material tank structure is located on top of the plain concrete bottom layer 13. A waterproof cover plate 11 for water treatment reaction material is installed on the upper part of the reaction material tank. A filter layer 4 for incoming water direction is provided on the left side of the incoming water surface structure 2. A reverse filter layer 5 for drainage direction is provided on the lower right side of the drainage surface structure 3. A filter material sealing plate 8 is provided on the top of the filter layer 4 for incoming water direction. A reverse filter material sealing plate 8' is provided on the top of the reverse filter layer 5 for drainage direction. The incoming water surface structure 2 and the drainage surface structure 3 pass through the upper impermeable layer m and the middle permeable layer n from top to bottom and penetrate into the lower impermeable layer k to a height H1. The diameter of the inlet pipe 6 is greater than 1000 mm; the inlet pipe 6 is located on the upper left side of the reaction tank and is embedded in a row on the reinforcing bars of the incoming water surface structure 2. The inlet of the inlet pipe 6 is located in the filter layer 4 in the direction of incoming water, and the outlet of the inlet pipe 6 is located inside the reaction tank; the outlet pipe 6' is located on the lower right side of the reaction tank and is embedded in a row on the reinforcing bars of the drainage surface structure 3. The inlet of the outlet pipe 6' is located inside the reaction tank, and the outlet of the outlet pipe 6' is located in the reverse filter layer 5 in the direction of drainage; a filter bag 7 is arranged outside the inlet of the inlet pipe 6. The water treatment reaction material 1 is stored in the reaction tank in bags, packages, or cages to treat the seeping wastewater. The diameter of the reinforcing bars of the incoming water surface structure 2 and the drainage surface structure 3 is not less than 16 mm, and the spacing is not greater than 200 mm. In this embodiment, the water treatment reaction material 1 is "zeolite + activated carbon". The main targets of treatment include pollutants such as arsenic, lead, chromium, nickel and ammonia nitrogen. Other adsorption and removal materials can also be added depending on the composition of pollutants in the wastewater.

[0034] A horizontal impermeable layer structure 9 is provided on the surface of the filter material sealing plate 8 on the left side of the inlet water surface structure 2 and on the surface of the upper impermeable layer m on the right side of the drainage surface structure 3. The horizontal impermeable layer structure 9 provided on the surface of the filter material sealing plate 8 on the left side of the inlet water surface structure 2 extends to the left onto the surface of the upper impermeable layer m on the left side of the inlet water surface structure 2. In the embodiment, horizontal impermeable materials are arranged within a 5-meter range on both sides of the inlet water surface structure 2 and the drainage surface structure 3. The horizontal impermeable materials are rolled up to the top of the sides of the inlet water surface structure 2 and the drainage surface structure 3, and compacted and sealed. The construction of the horizontal impermeable materials refers to the relevant horizontal impermeable construction atlas or structures. A natural ground soil layer 10 is laid on the surface of the horizontal impermeable layer structure 9, compacted, and then planted with turf for landscaping.

[0035] In this embodiment, the filter material built into the inlet water filter layer 4 is coarse sand with a particle size of 10-40 mm, and the thickness b of the inlet water filter layer 4 is not less than 1000 mm; the filter material built into the outlet water filter layer 5 is coarse sand + medium-coarse stone, with the coarse sand particle size of 10-40 mm and the medium-coarse stone particle size of 30-50 mm, the mass ratio of coarse sand to medium-coarse stone is 1:1, and the thickness c of the outlet water filter layer 5 is not less than 600 mm; the inlet pipe 6 is located at H6 below the top of the inlet water surface structure 2, and H6 is not less than 1200 mm; the filter bag 7 is wrapped with geotextile to make coarse sand filter material, with a volume of 450 mm x 250 mm x 250 mm, and the coarse sand used is gravel with a particle size greater than 0.10 mm, of which particles with a particle size greater than 0.5 mm account for more than 50% of the total weight; the outlet pipe 6' is located at a distance from the middle permeable layer and the lower part The height of the impermeable layer boundary line 15 is 300mm; the spacing of the inlet pipes 6 is 2000mm, arranged in a row along the length; the spacing of the drain pipes 6' is 2000mm, arranged in a row along the length; the height of the filter layer 4 in the water inlet direction is the height of the reactant material entering the lower impermeable layer H1 + the thickness of the middle permeable layer H3 + the thickness of the upper impermeable layer H4; the thickness of the reverse filter layer 5 in the drainage direction is c=600mm, and the height is H1+H3+H7, where H7 is greater than 500mm.

[0036] The water inlet structure 2 and the drainage structure 3 have a height of H1+H3+H4+H5+300, are made of C30 concrete, and have a length equal to the entire length of the reaction wall; the bottom plate 12 of the material tank structure has a thickness H2 of not less than 400mm and a width B=A+2a+b+c; the filter material sealing plate 8 has a thickness of 60mm, a width of 1000mm, a length of 1000mm, and a total length of 100 meters; the reverse filter material sealing plate 8' has a thickness of 60mm, a width of 600mm, a length of 1000mm, and a total length of 100 meters. Both the filter material sealing plate 8 and the reverse filter material sealing plate 8' are reinforced with steel bars, 12mm in diameter and spaced 150mm apart; the inlet pipe 6 and the outlet pipe 6' are both made of stainless steel, 150mm in diameter; the outlet pipe 6' is H1+300mm away from the bottom plate 12 of the material tank structure; the water treatment reaction material waterproof cover 11 is a precast trapezoidal concrete component, 60mm high on each side, 100mm high in the middle, and wide (A+2a+2e), with a single piece length of 1000mm and a total length of 100 meters, and the internal steel bars are 14mm in diameter and spaced 150mm apart.

[0037] This invention has been applied in the underground sewage treatment project of the Longhua Municipal Solid Waste Landfill in Dangtu District, Ma'anshan City, Anhui Province. After testing of the groundwater discharged after in-situ purification treatment using this invention, the levels of pollutants such as arsenic, lead, chromium, nickel, and ammonia nitrogen all meet the emission standards.

[0038] It should be noted that the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "top / bottom," etc., used in this invention indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the parts or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first" and "second" are also only for the convenience of description and distinction, and therefore should not be construed as limitations on this invention.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer, characterized in that: It includes a plain concrete base layer (13) laid at the bottom of the pit after the foundation pit is excavated at the narrowest point of the groundwater flow downstream of the landfill, and a reaction tank filled with water treatment reaction material (1) constructed on the plain concrete base layer (13). The reaction tank is a groove-shaped structure composed of a water inlet surface structure (2), a drainage surface structure (3), and a bottom plate (12) of the tank structure. The water inlet surface structure (2) is set facing the direction of underground sewage flow (16), and the drainage surface structure (3) is parallel to the water inlet surface structure (2) on the left and right. The bottom plate (12) of the tank structure is located on the plain concrete base layer (13). A water inlet direction filter layer (4) is provided on the left side of the water inlet surface structure (2), and a drainage direction reverse filter layer (5) is provided on the lower right side of the drainage surface structure (3). The water inlet surface structure (2) and the drainage surface structure (3) pass through the upper impermeable layer (m) and the middle permeable layer (n) from top to bottom and penetrate into the lower impermeable layer (k). The inlet pipe (6) is located on the upper left side of the reaction tank and is embedded in a row on the reinforcing bars of the incoming water surface structure (2). The inlet of the inlet pipe (6) is located in the filter layer (4) in the direction of incoming water, and the outlet of the inlet pipe (6) is located in the reaction tank. The drain pipe (6') is located on the lower right side of the reaction tank and is embedded in a row on the reinforcing bars of the drainage surface structure (3). The inlet of the drain pipe (6') is located in the reaction tank, and the outlet of the drain pipe (6') is located in the reverse filter layer (5) in the direction of drainage. A filter bag (7) is arranged outside the inlet of the inlet pipe (6).

2. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 1, characterized in that: A filter material sealing plate (8) is provided on the top of the filter layer (4) in the water inlet direction, and a filter material sealing plate (8') is provided on the top of the filter layer (5) in the water outlet direction.

3. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 2, characterized in that: A horizontal impermeable layer structure (9) is provided on the surface of the filter material sealing plate (8) on the left side of the water inlet structure (2) and on the surface of the upper impermeable layer (m) on the right side of the drainage structure (3); the horizontal impermeable layer structure (9) provided on the surface of the filter material sealing plate (8) on the left side of the water inlet structure (2) extends to the left side of the upper impermeable layer (m) on the left side of the water inlet structure (2); a natural ground soil layer (10) is laid on the surface of the horizontal impermeable layer structure (9).

4. The combined structure for in-situ infiltration reaction treatment of wastewater under a thick impermeable layer as described in claim 1, 2, or 3, characterized in that: A waterproof cover plate (11) for water treatment reaction materials is installed on the upper part of the reaction tank.

5. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 4, characterized in that: The height H1 of the water inlet structure (2) and the drainage structure (3) extending into the lower impermeable layer (k) is greater than 1000mm.

6. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 5, characterized in that: The filter material built into the water inlet filter layer (4) is coarse sand with a particle size of 10-40 mm, and the thickness b of the water inlet filter layer (4) is not less than 1000 mm; the filter material built into the drainage filter layer (5) is coarse sand + medium coarse stone, with the coarse sand particle size of 10-40 mm and the medium coarse stone particle size of 30-50 mm, and the thickness c of the drainage filter layer (5) is not less than 600 mm.

7. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 6, characterized in that: The inlet pipe (6) is located at H6 below the top of the water inlet structure (2), and H6 is not less than 1200mm; the filter bag (7) is wrapped with geotextile and coarse sand. The coarse sand used is gravel with a particle size greater than 0.10mm, of which particles with a particle size greater than 0.50mm account for more than 50% of the total weight.

8. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 7, characterized in that: The distance between the drainage pipe (6´) and the boundary line (15) between the middle permeable layer and the lower impermeable layer is 250-350mm.

9. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 7, characterized in that: The thickness of the water inlet structure (2) and the drainage structure (3) is not less than 300 mm.

10. The combined structure for in-situ infiltration reaction treatment of sewage under a thick impermeable layer as described in claim 9, characterized in that: The spacing of the inlet pipes (6) is 1700-2300mm, arranged in a row along the length; the spacing of the drain pipes (6') is 1700-2300mm, arranged in a row along the length; the height of the inlet filter layer (4) is the height of the reaction material entering the lower impermeable layer H1 + the thickness of the middle permeable layer H3 + the thickness of the upper impermeable layer H4; the height of the drain filter layer (5) is the height of the reaction material entering the lower impermeable layer H1 + the thickness of the middle permeable layer H3 + the height of the drain filter layer above the boundary between the middle permeable layer and the upper impermeable layer H7, where H7 is greater than 500mm; the water treatment reaction material (1) is stored in the reaction tank in bags, packages or cages to treat the seeping sewage; the mass ratio of coarse sand to medium-coarse stone in the filter material built into the drain filter layer (5) is (0.8-1.1):1.

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