Steel shell composite reaction structure for in-situ permeation remediation of underground sewage in solid waste landfill site

Abstract

The application discloses a kind of steel shell composite reaction structures for solid waste landfill underground sewage in-situ permeation repair, including concrete water-stop base layer (9) in water-permeable layer and impermeable layer separation line (10) below, steel shell composite reaction structure frame installed on concrete water-stop base layer (9) above construction, concrete sealing cover (2), guide wall (11);Steel shell composite reaction structure frame is surrounded by sewage treatment filling material upper cover plate (3), sewage inflow surface profile steel side plate (4), clean water outflow surface profile steel side plate (4'), front side plate, rear side plate and sewage treatment filling material lower bottom plate (8) jointly form steel shell composite reaction cavity, sewage treatment filling material (1) is loaded in the steel shell composite reaction cavity.The leachate generated by the solid waste accumulated in the garbage landfill and degraded by the environment is repaired and treated by the application, which has the advantages of shorter construction period, lower maintenance cost after completion, reusable equipment and significant comprehensive benefits.

Description

Technical Field

[0001] This invention belongs to the field of engineering technology for in-situ infiltration remediation of underground sewage, specifically relating to a reaction structure for in-situ infiltration remediation of underground sewage. It is suitable for remediating leachate generated by environmental degradation of solid waste accumulated in landfills, and can also be used for remediating underground sewage caused by the infiltration of livestock and poultry breeding waste, leakage of wastewater storage facilities constructed in the early stages without proper standards, etc. Background Technology

[0002] With the acceleration of industrialization and the continuous expansion of urban population and land use, groundwater pollution has become an environmental problem that urgently needs to be solved in my country and even globally. Currently, the factors causing groundwater pollution are complex and diverse, covering multiple sectors including industry, agriculture, and daily life: In industry, early-built industrial wastewater storage facilities, due to non-standard design, have resulted in missing or damaged anti-seepage barriers on workshop floors or the bottom of underground storage tanks, leading to pollutant leakage; in agriculture, excessive use of chemical fertilizers and pesticides, and the seepage of manure and urine from large-scale livestock and poultry farms, have overburdened the self-purification capacity of farmland groundwater; in daily life, disconnected pipe connections in old residential areas cause direct discharge of sewage, further exacerbating the severe situation of groundwater pollution.

[0003] Currently, underground wastewater remediation and treatment technologies are mainly divided into two categories: wastewater extraction and treatment technologies and permeable reactive barrier technologies, but both have significant limitations.

[0004] One approach is wastewater extraction and treatment technology. This technology involves deploying pumping wells above the contaminated area to extract underground wastewater to the surface. After purification through processes such as adsorption, filtration, chemical oxidation, or biological treatment, the treated water is reinjected into the ground. However, the remediation costs and timelines for this technology increase exponentially with the expansion of the contaminated area, making it difficult to achieve long-term remediation of large areas of groundwater. Furthermore, the construction process requires large-scale site excavation, severely disrupting the surrounding ecological environment, imposing stringent construction conditions, and resulting in low overall feasibility.

[0005] Second is the in-situ remediation technology, specifically the reactive barrier. As an in-situ remediation technique, this method involves driving in temporary steel partitions to form a retaining frame, filling in reactive materials, and then removing the partitions. The natural flow of groundwater allows for contact degradation of pollutants with the reactive materials. However, in practice, three major drawbacks have been exposed: ① The reactive layer is prone to clogging and failure: After removing the partitions, mud from the surrounding soil flows into the reactive layer with the groundwater. Within approximately six months, the surface of the reactive material is completely covered by mud, reducing its permeability by more than 70%, drastically decreasing remediation efficiency; ② High maintenance costs: After the reactive material fails, the foundation pit needs to be excavated again for replacement. The cost of a single replacement accounts for 40% of the initial investment, and the excavation process is highly susceptible to pollution spread; ③ Risk of secondary pollution: The failed reactive material is mixed with the soil and difficult to separate. Residual heavy metals or organic pollutants may seep back into the groundwater, causing irreversible secondary pollution.

[0006] To address the aforementioned issues, patent number CN121517000A discloses an in-situ remediation method for organic composite polluted groundwater based on micro-nano iron-based materials. This invention employs a reduction-oxidation chain reaction system, which can efficiently degrade composite pollutants such as halogenated hydrocarbons and benzene compounds. However, the composite reaction zone relies on uniform well placement and does not consider the heterogeneity of the site's hydrogeology, easily leading to remediation blind zones in complex strata; the micro-nano iron-based materials are prone to aggregation and have poor dispersibility during groundwater flow, resulting in a limited effective coverage area of ​​the reaction zone; furthermore, the amount of material added is difficult to control precisely, easily causing secondary pollution or waste of reagents.

[0007] Existing technologies generally suffer from drawbacks such as long construction cycles, significant ecological disturbance, poor durability, inability to recycle treated wastewater, and high operation and maintenance costs. Therefore, there is an urgent need to develop a prefabricated construction technology that offers low operation and maintenance costs and long-term stability for groundwater pollution treatment, in order to achieve long-term, efficient, and in-situ remediation of underground wastewater. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing underground wastewater remediation technologies, such as long construction cycles, significant ecological disturbance, weak durability, and difficulty in reuse, by providing a steel-shell composite reactive structure for in-situ permeable remediation of underground wastewater in solid waste landfill sites. This structure eliminates the need for extracting and transporting underground wastewater, as well as constructing centralized treatment plants. It achieves in-situ remediation while maintaining the original groundwater flow direction and hydrological environment, featuring low investment and simple operation and maintenance. Furthermore, it supports modular construction, resulting in short construction periods, low maintenance costs, and reusable equipment, leading to significant overall benefits.

[0009] To achieve the above-mentioned objectives of this invention, the steel-shell composite reactive structure for in-situ infiltration remediation of underground wastewater in solid waste landfills adopts the following technical solution:

[0010] This invention relates to a steel-shell composite reactive structure for in-situ permeable remediation of underground wastewater in solid waste landfills. The structure comprises a concrete waterproofing base layer installed by curtain grouting on the rock portion below the dividing line between the permeable and impermeable layers; a steel-shell composite reactive structure frame constructed and installed on top of the concrete waterproofing base layer; a concrete sealing cap; and a guide wall. The concrete waterproofing base layer has a groove-shaped structure, with both sides extending upwards through the dividing line between the permeable and impermeable layers. The concrete sealing cap is located above the steel-shell composite reactive structure frame. The guide wall is inverted L-shape, with its left and right sides forming bottomless concave structures. The upper parts of the concrete sealing cap and the steel-shell composite reactive structure frame are located within the concave structures formed by the guide wall. The guide wall is used to determine the axial position and thickness of the steel-shell composite reactive structure frame, and the guide wall and concrete sealing cap ultimately enclose the upper part of the steel-shell composite reactive structure frame. The grooved concrete waterproof base layer is used to seal the crack channels in the lower impermeable layer and ensure that the concrete waterproof base layer completely wraps the lower part of the steel shell composite reactive structure frame, ensuring that underground sewage cannot bypass it. It forces all underground sewage to flow through the sewage inflow surface steel side plate, and then chemically repairs it through the sewage treatment filling material. Finally, the purified water flows out through the surface steel side plate and meets the water standards, thereby achieving complete interception and efficient purification of pollutants in underground sewage.

[0011] The steel shell composite reaction structure frame is composed of a sewage treatment filling material upper cover plate, sewage inflow surface steel side plate, clean water outflow surface steel side plate, front side plate, rear side plate, horizontal support square steel pipe, vertical support square steel pipe, and sewage treatment filling material lower base plate to form a modular structure. The sewage inflow surface steel side plate and the clean water outflow surface steel side plate are arranged symmetrically on the left and right. The sewage treatment filling material lower base plate, sewage inflow surface steel side plate, clean water outflow surface steel side plate, front side plate, rear side plate, and sewage treatment filling material lower base plate together form a steel shell composite reaction cavity, in which sewage treatment filling material is installed. The sewage inflow side steel plate, as the water-facing surface, first contacts the underground sewage that has not been physically screened, while the clean water outflow side steel plate, as the back water surface, discharges the qualified water that has undergone physical and chemical reaction treatment. The horizontal and vertical support square steel pipes are located inside the steel shell composite reaction structure frame to ensure that the rigidity, stability, and load-bearing capacity of the entire frame meet the requirements. The upper cover plate of the sewage treatment filling material is located at the junction of the steel shell composite reaction structure frame and the concrete sealing cover, and the lower bottom plate of the sewage treatment filling material is located at the lower end of the steel shell composite reaction structure frame. The surface of the steel side plate on the sewage inflow side is provided with inflow holes, and the surface of the steel side plate on the clean water outflow side is provided with outflow holes. The arrangement of the inflow holes and outflow holes adopts a checkerboard pattern, with an opening ratio of 4.5~5%, a hole diameter of 20~24mm, and a hole spacing controlled at 80~90mm. Both the inflow holes and outflow holes adopt a conical shape that is narrow on the outside and wide on the inside. The hole diameter of the inflow hole is smaller than that of the outflow hole. Its function is to utilize fluid dynamics theory so that when underground sewage and mud particles enter the inflow hole, due to the large internal space of the steel shell composite reaction structure, the underground sewage and mud particles, after being repaired and treated by the sewage treatment filling material, can easily flow out from the outflow hole with the water flow.

[0012] The steel-shell composite reactive structure frame is made of ordinary Q235B steel or higher strength material, and its surface is coated with a special anti-corrosion coating to increase its corrosion resistance and extend its service life. The anti-corrosion coating is composed of epoxy zinc-rich resin, epoxy micaceous iron oxide, and polyurethane. The wastewater treatment filling material includes a mixture of activated carbon, zeolite, and sponge iron filler, with a volume ratio of activated carbon to zeolite of (2~2.5):1. This wastewater treatment filling material can remove heavy metal pollutants such as arsenic, lead, chromium, nickel, and ammonia nitrogen from underground wastewater. Due to the diverse internal components of underground wastewater, other decontamination materials can be flexibly selected according to actual needs. If the underground wastewater contains high concentrations of organic pollutants, sponge iron material can be added to the existing material, utilizing its high specific surface area and strong reducing properties to accelerate the removal of high-concentration organic pollutants and precipitate heavy metal ions.

[0013] For underground wastewater with high heavy metal content, manganese sand can be added for combined use. The mass ratio of activated carbon, zeolite, sponge iron, and manganese sand is: (activated carbon + zeolite):(sponge iron + manganese sand) = (2~4):1, and the mass ratio of sponge iron to manganese sand is 1:(3~6). This process efficiently removes iron, manganese, and some heavy metal ions through catalytic oxidation. Flexible selection of decontamination materials is necessary to adapt to the treatment needs of underground wastewater with different pollution types and levels, thereby improving the remediation effect.

[0014] Preferably, the guide wall has a thickness of not less than 200mm and a height of not less than 1.2m. The horizontal opening spacing of the guide wall is 10-20mm larger than the corresponding width of the steel shell composite reactive structure frame to facilitate the installation of the steel shell composite reactive structure frame. The guide wall is internally reinforced with steel bars, the diameter of which is not less than 12mm. The purpose of the guide wall is to provide precise positioning before the construction of the main steel shell composite reactive structure, ensuring that the trenching machine can excavate according to the design requirements. It also facilitates the prefabricated construction and installation of the main steel shell composite reactive structure.

[0015] Preferably, the thickness of the steel side plate for the sewage inflow surface and the steel side plate for the clean water outflow surface is 7-15mm; the thickness of the bottom plate of the sewage treatment filling material is 7-15mm; and the groove depth of the concrete waterstop base layer is 5-8m.

[0016] To prevent the guide wall from being squeezed inward, round wooden supports are installed at the upper and lower parts of the inner side of the guide wall.

[0017] In practical applications, the length of the guide wall can be set differently depending on the actual construction conditions. The entire guide wall can be divided into multiple construction sections, with each section having a length of 10 to 15 meters. The joints of each guide wall section can be staggered and overlapped.

[0018] The working principle of the steel-shell composite reaction structure for in-situ infiltration remediation of underground wastewater in solid waste landfill sites is as follows: Underground wastewater flows towards the steel-shell composite reaction structure along the natural flow direction of groundwater. It undergoes physical filtration through the wastewater inflow surface steel side plates, which intercept large solid particles such as soil, sand, and debris mixed in the underground wastewater, thus performing preliminary physical treatment. Subsequently, the underground wastewater entering through the inflow holes undergoes chemical purification through wastewater treatment filling materials. These materials contain a mixture of activated carbon, zeolite, and sponge iron, and other decontamination materials such as manganese sand can be flexibly selected according to actual needs. Finally, the treated water flows out of the steel-shell composite reaction structure through the outflow holes of the purified water outflow surface steel side plates, achieving the function of in-situ infiltration remediation of underground wastewater.

[0019] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0020] (1) Short construction period and fast construction speed. This invention uses prefabricated steel plates and steel pipes for on-site assembly construction, which brings all the time-consuming processes such as pouring and curing of traditional concrete reactive walls to the factory in advance. Only the steel plates and steel pipes need to be welded together on site, avoiding the long construction period of pouring and curing concrete grooves (reactive walls) in the traditional method. The construction cycle can be shortened by more than 50% compared with the traditional method. At the same time, this invention can quickly solve and suppress sudden underground sewage leakage, quickly build an underground sewage interception barrier, and prevent the pollution from spreading further.

[0021] (2) Minimal ecological disturbance and strong site adaptability. During construction, because the thickness of the steel plate is much thinner than that of traditional concrete reactive walls, the amount of earthwork excavation is reduced compared to concrete reactive walls, thus reducing soil disturbance and lowering labor and construction costs. This also effectively reduces the adverse impact on the ecological environment and groundwater environment. Experimental studies show that compared to the structural requirements of traditional concrete reactive walls, which are often several meters thick, the thickness of the steel side plate of this invention is only 7-15mm, reducing earthwork excavation by 70% and significantly reducing the disturbance to the original underground soil structure and hydrological environment during construction. At the same time, the entire construction process does not require large-scale removal of excavated soil or the use of large heavy construction equipment, maximizing the protection of the surrounding vegetation and soil microbial communities, making it particularly suitable for groundwater remediation projects in ecologically sensitive areas.

[0022] (3) Good stability and strong durability. Traditional concrete reactive walls are affected by groundwater and soil corrosion and uneven soil settlement, and will develop problems such as cracking and leakage within 3-5 years, with repair efficiency decreasing year by year; while the present invention adopts a combination scheme of Q235B steel + "epoxy zinc-rich + epoxy micaceous iron + polyurethane" three-layer anti-corrosion coating, which improves the corrosion resistance by more than 4 times and the design service life can reach 30 years. At the same time, the rigid structure of the steel frame can resist the extrusion deformation of the underground soil layer, completely solving the pain points of traditional reactive walls that are easy to clog and easy to fail, and improving the long-term operational stability by more than 80%.

[0023] (4) Modular construction and recyclability. The steel-shell composite reaction structure can be flexibly adjusted in size according to the hydrogeological conditions of the contaminated site, the range of the pollution plume, and the type of pollutants: the length of a single structure can be freely combined between 10 and 15m, and the filling material of the reaction chamber can be precisely selected according to the type of pollutants (e.g., activated carbon + zeolite combination is suitable for heavy metal pollution, and sponge iron + manganese sand combination is suitable for high-concentration organic pollution). After the project is completed, the steel components can be completely disassembled and recycled. After surface anti-corrosion repair, they can be reused in other sites. The material recycling rate is over 90%, which greatly reduces long-term operation and maintenance costs.

[0024] (5) Construction, installation and operation costs are significantly reduced. The cost of traditional extraction treatment technology increases exponentially with the expansion of the pollution range, while the in-situ remediation mode of this invention does not require the construction of a surface treatment station or a pumping and reinjection system, and the initial investment is less than 40% of that of extraction treatment technology. At the same time, since the reaction materials can be replaced as needed and the steel components can be recycled, the annual operation and maintenance cost is only about one-third of that of traditional permeable reactive walls, making it particularly suitable for large-area, long-term groundwater pollution treatment scenarios. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the steel-shell composite reactive structure for in-situ infiltration remediation of underground sewage in solid waste landfills, as described in this invention.

[0026] Figure 2 An assembly diagram of the steel shell composite reactive structure frame module designed for this invention applied in a construction section;

[0027] Figure 3 This is a schematic diagram of the openings in the steel side plate for the sewage inflow surface and the steel side plate for the clean water outflow surface used in this invention.

[0028] Figure 4 The front elevation view of the steel shell composite reactive structure frame designed for this invention;

[0029] Figure 5 This is a side elevation view of the steel shell composite reactive structure frame designed for this invention.

[0030] The attached diagram is labeled as follows: 1-Wastewater treatment filling material; 2-Concrete sealing cover; 3-Upper cover plate of wastewater treatment filling material; 4-Steel side plate of wastewater inflow surface; 4'-Steel side plate of clean water outflow surface; 5-Inflow hole; 5'-Outflow hole; 6-Horizontal support square steel pipe; 7-Vertical support square steel pipe; 8-Lower base plate of wastewater treatment filling material; 9-Concrete water-stop base layer; 10-Separation line between permeable layer and impermeable layer; 11-Guide wall. Detailed Implementation

[0031] The steel-shell composite reactive structure for in-situ permeable remediation of underground wastewater in solid waste landfills will be further described clearly and completely below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Depend on Figure 1 The diagram shown is a cross-sectional view of the steel-shell composite reactive structure for in-situ permeable remediation of underground wastewater in solid waste landfills, as described in this invention, and is combined with... Figure 2 , Figure 3 , Figure 4 , Figure 5 As can be seen, the steel-shell composite reactive structure for in-situ permeable remediation of underground wastewater in solid waste landfills of the present invention is composed of a concrete waterproofing base layer 9 installed by curtain grouting on the rock portion below the permeable and impermeable layer dividing line 10, a steel-shell composite reactive structure frame constructed and installed on the concrete waterproofing base layer 9, a concrete sealing cap 2, and a guide wall 11. The concrete waterproofing base layer 9 is a groove-shaped structure, with both sides of the groove extending upwards through the dividing line 10 between the permeable and impermeable layers. The groove depth of the concrete waterproofing base layer 9 is 5-8m. The concrete sealing cap 2 is located on the steel-shell composite reactive structure frame. The guide wall 11 is in the shape of an inverted L. The left and right sides are respectively arranged in a bottomless concave structure. The upper part of the concrete sealing cover 2 and the steel shell composite reaction structure frame is located in the concave structure formed by the guide wall 11. The guide wall 11 is equipped with steel bars with a diameter of not less than 12mm. The wall thickness of the guide wall 11 is not less than 200mm and the height is not less than 1.2m. The horizontal opening spacing of the guide wall 11 is 10-20mm larger than the corresponding width of the steel shell composite reaction structure frame. The steel shell composite reaction structure frame consists of a sewage treatment filling material upper cover plate 3, sewage inflow surface steel side plate 4, clean water outflow surface steel side plate 4', front side plate, rear side plate, horizontal support square steel pipe 6, vertical support square steel pipe 7 and sewage treatment filling material upper cover plate 3, sewage inflow surface steel side plate 4' ... steel shell composite reaction structure frame 3. The wastewater treatment filling material is composed of a lower base plate 8 and a steel side plate 4 for the sewage inflow surface and a steel side plate 4' for the clean water outflow surface, which are symmetrically arranged on the left and right sides. The thickness of the steel side plate 4 for the sewage inflow surface and the steel side plate 4' for the clean water outflow surface is 7-15mm. The horizontal support square steel pipe 6 and the vertical support square steel pipe 7 are located inside the steel shell composite reaction structure frame. The upper cover plate 3 of the wastewater treatment filling material is located at the junction of the steel shell composite reaction structure frame and the concrete sealing cover 2. The lower base plate 8 of the wastewater treatment filling material is located at the lower end of the steel shell composite reaction structure frame. The thickness of the lower base plate 8 of the wastewater treatment filling material is 7-15mm. The lower base plate 8 of the wastewater treatment filling material and the steel side plate 4' for the sewage inflow surface are symmetrically arranged on the left and right sides. Side plate 4, clean water outflow steel side plate 4', front side plate, rear side plate, and sewage treatment filling material bottom plate 8 together form a steel shell composite reaction chamber, and sewage treatment filling material 1 is installed in the steel shell composite reaction chamber; inflow holes 5 are provided on the surface of sewage inflow steel side plate 4, and outflow holes 5' are provided on the surface of clean water outflow steel side plate 4'. The arrangement of inflow holes 5 and outflow holes 5' is a checkerboard layout, with an opening ratio of 4.5~5%, a hole diameter of 20~24mm, and a hole spacing controlled at 80~90mm. Both inflow holes 5 and outflow holes 5' are tapered holes with a narrow outer diameter and a wide inner diameter. The hole diameter of inflow hole 5 is smaller than that of outflow hole 5'.

[0033] The wastewater treatment packing material mainly comprises a mixture of activated carbon and zeolite. In this embodiment, the volume ratio of activated carbon to zeolite is 7:3. This wastewater treatment packing material can remove heavy metal pollutants such as arsenic, lead, chromium, nickel, and ammonia nitrogen from underground wastewater. Due to the diverse internal composition of underground wastewater, other decontamination materials can be flexibly selected according to actual needs. If the underground wastewater contains high concentrations of organic pollutants, sponge iron material can be added to the existing material. Utilizing its high specific surface area and strong reducing properties, it can accelerate the removal of high-concentration organic pollutants and precipitate heavy metal ions. For underground wastewater with high heavy metal content, manganese sand can be added for combined use, efficiently removing iron, manganese, and some heavy metal ions through catalytic oxidation. Flexible selection of decontamination materials is to adapt to the treatment needs of underground wastewater with different pollution types and degrees, thereby improving the remediation effect of underground wastewater.

[0034] Studies have shown that the wastewater treatment filling material can solve the in-situ infiltration remediation of most solid waste landfill sites by the following ratio: the wastewater treatment filling material is composed of activated carbon, zeolite, sponge iron and manganese sand. The volume ratio of activated carbon to zeolite is (2~2.5):1. The mass ratio of activated carbon, zeolite, sponge iron and manganese sand is (activated carbon + zeolite): (sponge iron + manganese sand) = (2~4):1. The mass ratio of sponge iron to manganese sand is 1: (3~6).

[0035] In practical engineering applications, before installing the steel-shell composite reactive structure frame, the guide wall 11 needs to be constructed first. The guide wall 11 is inverted L-shape. The excavation within the guide wall 11 area is carried out using mechanical excavation and manual trimming. Then, according to design requirements, reinforcing bars are tied, steel formwork is installed inside the guide wall 11, and concrete is poured. After pouring and formwork removal, round wooden horizontal supports need to be installed inside the guide wall 11, with horizontal and vertical spacing not exceeding 1m. After the guide wall 11 reaches its standard strength, the groove structure for filling the sewage treatment filling material 11 can be constructed. The excavation of the foundation pit and the installation of the steel-shell composite reactive structure both use the skip excavation method. Before construction, the trench is divided into sections according to the individual structure of each module. The verticality of the trench should not exceed 0.5%, and the trench depth should not be less than 100mm of the designed excavation depth. After trenching, secondary cleaning of the hole is required to meet the requirement that the slag thickness should not exceed 50mm. Figure 1-2As shown, when installing steel-shell composite reactive structure modules in a construction section, to ensure overall stability and integrity, module W1 is installed first, followed by modules W2 on both sides of module W1. When installing modules W1 or W2, the sewage inflow steel side plate 4, the clean water outflow steel side plate 4', and the front and rear side plates are first lowered to the design elevation. The verticality of all side plates is checked to ensure it does not exceed 0.5%. The four steel side plates of the steel-shell composite reactive structure frame are then welded and fixed. Afterwards, the concrete waterstop base layer 9 is poured. The concrete waterstop base layer 9 uses curtain grouting, and the underlying rock surface is pre-drilled. Grouting holes are used to inject plain cement grout into the rock fissures through sequential and dense injection holes. Plain cement is also injected into the outer side of the lower end of the steel side plate, so that all the poured plain cement parts share the same concrete waterstop base layer 9. The concrete waterstop base layer 9 is then cleaned and leveled. Subsequently, the sewage treatment filling material bottom plate 8 is installed above the concrete waterstop base layer 9 and welded to the steel side plate, forming the basic framework of the steel shell composite reaction structure. The steel shell composite reaction structure is internally equipped with horizontal support square steel pipes 6, vertical support square steel pipes 7, and sewage treatment filling material 1. To ensure the stability of the steel shell composite reaction structure, such as Figure 4 As shown, horizontal support square steel pipe 6 and vertical support square steel pipe 7 are welded and installed inside.

[0036] The steel-shell composite reactive structure for in-situ infiltration remediation of underground sewage in solid waste landfills has been practically used in an underground sewage treatment project at a landfill in China. After the underground sewage generated by the infiltration of domestic waste was treated by this invention, the main pollutants such as organic pollutants, heavy metals and radioactive substances have all met the emission standards.

[0037] The results of practical engineering applications show that the steel-shell composite reactive structure for in-situ infiltration remediation of underground sewage in solid waste landfills, using the above technical solutions, achieves reasonable and efficient remediation of underground sewage through the concept of in-situ infiltration remediation. It solves problems such as long construction period, large land occupation, and low reuse rate, forming a structure and method for treating underground sewage with a short construction period, low maintenance cost after completion, reusable equipment, and significant comprehensive benefits. It provides a recyclable and long-term effective engineering solution for underground sewage remediation.

[0038] It should be noted that the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," and "top / bottom" 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 steel-shell composite reactive structure for in-situ infiltration remediation of underground wastewater in solid waste landfill sites, characterized in that: It includes a concrete waterproof base layer (9) set by curtain grouting for the rock portion below the dividing line (10) between the permeable and impermeable layers, a steel shell composite reactive structure frame, a concrete sealing cap (2), and a guide wall (11) constructed and installed on the concrete waterproof base layer (9). The concrete waterproof base layer (9) is a groove-shaped structure with both sides of the groove-shaped structure extending upward through the dividing line (10) between the permeable and impermeable layers. The concrete sealing cap (2) is located on the steel shell composite reactive structure frame. The guide wall (11) is in the shape of an "inverted L", with the left and right sides corresponding to form a bottomless concave structure. The upper part of the concrete sealing cap (2) and the steel shell composite reactive structure frame is located within the concave structure formed by the guide wall (11). The steel shell composite reaction structure frame is composed of a sewage treatment filling material upper cover plate (3), sewage inflow surface steel side plate (4), clean water outflow surface steel side plate (4'), front side plate, rear side plate, horizontal support square steel pipe (6), vertical support square steel pipe (7), and sewage treatment filling material lower bottom plate (8) to form a modular structure. The sewage inflow surface steel side plate (4) and clean water outflow surface steel side plate (4') are arranged symmetrically on the left and right. The sewage treatment filling material lower bottom plate (8), sewage inflow surface steel side plate (4), clean water outflow surface steel side plate (4'), front side plate, rear side plate, and sewage treatment filling material lower bottom plate (8) together form a steel shell composite reaction cavity, in which sewage treatment filling material (1) is installed; the horizontal support square steel pipe (6) and vertical support square steel pipe (7) are arranged symmetrically on the left and right. The steel pipe (7) is located inside the steel shell composite reaction structure frame; the upper cover plate (3) of the sewage treatment filling material is located at the junction of the steel shell composite reaction structure frame and the concrete sealing cover (2); the lower bottom plate (8) of the sewage treatment filling material is located at the lower end of the steel shell composite reaction structure frame; the surface of the sewage inflow surface steel side plate (4) is provided with inflow holes (5); the surface of the clean water outflow surface steel side plate (4') is provided with outflow holes (5'); the arrangement of the inflow holes (5) and the outflow holes (5') adopts a checkerboard layout, with an opening rate of 4.5~5%, a hole diameter of 20~24mm, and a hole spacing controlled at 80~90mm; the inflow holes (5) and the outflow holes (5') both adopt a tapered hole shape with a narrow outer diameter and a wide inner diameter; the hole diameter of the inflow hole (5) is smaller than the hole diameter of the outflow hole (5'); The steel-shell composite reactive structure frame is made of ordinary steel Q235B or higher strength material, and its surface is coated with a special anti-corrosion coating. The anti-corrosion coating is composed of epoxy zinc-rich, epoxy micaceous iron and polyurethane. The sewage treatment filling material includes activated carbon, zeolite and sponge iron mixed filler, and the filling volume ratio of activated carbon and zeolite is (2~2.5):

1.

2. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 1, characterized in that: The wastewater treatment filling material also includes manganese sand. The mass ratio of activated carbon, zeolite, sponge iron and manganese sand is: (activated carbon + zeolite): (sponge iron + manganese sand) = (2~4):1, and the mass ratio of sponge iron to manganese sand is 1: (3~6).

3. The steel-shell composite reactive structure for in-situ infiltration remediation of underground wastewater in solid waste landfill sites as described in claim 1, characterized in that: The guide wall (11) has a wall thickness of not less than 200 mm and a height of not less than 1.2 m. The horizontal opening spacing of the guide wall (11) is 10 to 20 mm larger than the corresponding width of the steel shell composite reactive structure frame.

4. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 1, characterized in that: The guide wall (11) is internally reinforced with steel bars, the diameter of which is not less than 12mm.

5. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 1, characterized in that: The thickness of the steel side plate (4) for the sewage inflow surface and the steel side plate (4') for the clean water outflow surface is 7-15mm; the thickness of the bottom plate (8) for the sewage treatment filling material is 7-15mm; and the groove depth of the concrete waterstop base layer (9) is 5-8m.

6. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 2, characterized in that: The guide wall (11) has a wall thickness of not less than 200mm and a height of not less than 1.2m. The horizontal opening spacing of the guide wall (11) is 10-20mm larger than the corresponding width of the steel shell composite reactive structure frame. The guide wall (11) is equipped with steel bars with a diameter of not less than 12mm.

7. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 6, characterized in that: The thickness of the steel side plate (4) for the sewage inflow surface and the steel side plate (4') for the clean water outflow surface is 7-15mm; the thickness of the bottom plate (8) for the sewage treatment filling material is 7-15mm; the groove depth of the concrete water-stop base layer (9) is 5-8m; and round wooden supports are provided on the upper and lower parts of the inner side of the guide wall (11).

8. The steel shell composite reaction structure for solid waste landfill underground sewage in-situ permeation remediation according to claim 7, characterized in that: Based on the actual project conditions and the different length settings of the guide wall (11), the entire guide wall (11) is divided into multiple construction sections, with each section having a construction length of 10~15m. The joints of each guide wall (11) are staggered and overlapping.

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