Refuse landfill coupling contaminated soil remote remediation system and method

Abstract

The invention relates to the technical field of environmental pollution remediation, in particular to a refuse landfill coupling contaminated soil remote remediation system and method. The method comprises the following steps: carrying out deep stratified sampling and soil sample characteristic classification on a remotely repaired polluted soil heap to obtain remotely repaired soil samples corresponding to different pollution types; purified biogas is obtained to serve as a heat source for organic pollution desorption and conversion and solidification and stabilization coupling remediation, and a soil sample containing heavy metal after solidification and stabilization remediation is generated; carrying out chemical environmental assessment analysis and cyclic remediation treatment on the soil sample containing the heavy metals after solidification and stabilization remediation to generate a soil sample after organic pollution and heavy metal remediation; and carrying out fly ash landfill and reutilization on the soil sample subjected to organic pollution and heavy metal remediation to generate the remedied remote fly ash landfill and reutilization soil. Refuse landfill resources and remote polluted soil remediation can be combined to realize corresponding soil recycling.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental pollution remediation, and particularly to a landfill-coupled off-site remediation system and method for contaminated soil. Background Art

[0002] In terms of the resource utilization of landfills, the biogas generated in landfills is usually simply burned or directly discharged, which not only wastes energy but also pollutes the atmospheric environment. At the same time, the treatment of solid wastes such as fly ash in landfills also faces challenges. Fly ash contains a large amount of harmful substances such as heavy metals. Landfilling it poses a risk of heavy metal leakage and threatens the soil and groundwater environment. However, in the off-site remediation of contaminated soil by traditional contaminated soil remediation methods, common remediation methods such as soil replacement method require a large amount of high-quality soil resources and have high transportation costs. Although chemical remediation methods can reduce the concentration of soil pollutants to a certain extent, they will introduce new chemical substances and cause secondary pollution, making it difficult to achieve the circular reuse of both soil remediation and landfill resources. Summary of the Invention

[0003] Based on this, it is necessary for the present invention to provide a landfill-coupled off-site remediation system and method for contaminated soil to solve at least one of the above technical problems.

[0004] To achieve the above object, an off-site remediation method for landfill-coupled contaminated soil includes the following steps:

[0005] Step S1: Deeply stratified sampling is carried out on the corresponding off-site remediation contaminated soil piles in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; the soil sample characteristics of the off-site remediation contaminated soil samples corresponding to different depth levels are classified to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, heavy metals, and both organic pollution and heavy metals.

[0006] Step S2: The corresponding purified biogas is obtained from the landfill and used as a heat source, and based on the heat source, organic pollution desorption and conversion are carried out on the off-site remediation soil samples containing organic pollutants in the off-site remediation soil samples corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0007] Step S3: Perform solidification / stabilization coupling remediation on the off-site remediated soil samples containing heavy metals after the organic pollution has been remediated, to generate solidification / stabilization remediated heavy metal-containing soil samples; conduct chemical environmental impact assessment analysis on the solidification / stabilization remediated heavy metal-containing soil samples, to obtain the environmental impact assessment results of the remediated soil samples; based on the environmental impact assessment results of the remediated soil samples, perform cyclic remediation treatment on the solidification / stabilization remediated heavy metal-containing soil samples, to generate soil samples after the organic pollution and heavy metals have been remediated.

[0008] Step S4: Based on the landfill, perform fly ash landfill reuse on the soil samples after the organic pollution and heavy metals have been remediated, to generate remediated off-site fly ash landfill reused soil.

[0009] Further, Step S1 includes the following steps:

[0010] Step S11: Conduct deep stratified sampling on the corresponding off-site remediated polluted soil piles in the disposal center of the landfill, to sample a soil sample every 0.5 meters and mark the corresponding sampling location and depth, to obtain off-site remediated polluted soil samples corresponding to different depth levels.

[0011] Step S12: Detect the heavy metal content of the off-site remediated polluted soil samples corresponding to each different depth level, to obtain the soil heavy metal content corresponding to different types at each depth level.

[0012] Step S13: Analyze the types of organic pollutants in the off-site remediated polluted soil samples corresponding to each different depth level, to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons therein, to obtain the types of soil organic pollutants corresponding to each depth level.

[0013] Step S14: Classify the soil sample characteristics of the corresponding off-site remediated polluted soil samples based on the soil heavy metal content corresponding to different types at each depth level and the types of soil organic pollutants corresponding to each depth level, to obtain off-site remediated soil samples corresponding to different pollution types, including off-site remediated soil samples containing organic pollutants, containing heavy metals, and containing both organic pollution and heavy metals.

[0014] Further, the soil heavy metal content corresponding to different types in Step S12 specifically includes the heavy metal content corresponding to types such as lead, mercury, and cadmium.

[0015] Further, Step S2 includes the following steps:

[0016] Step S21: Set up biogas collection wells in the landfill, and use pipelines to transport the biogas collected in the biogas collection wells to the biogas purification device.

[0017] Step S22: Use a biogas purification device to purify the collected biogas, so as to purify and remove the corresponding hydrogen sulfide and moisture impurities in the biogas, and improve the purity of the biogas, so as to obtain the corresponding purified biogas and transport it to the contaminated soil remediation area through a pipeline as the corresponding biogas heat source during the remediation process;

[0018] Step S23: Based on the biogas heat source, perform organic pollution desorption and transformation on the soil samples for off-site remediation containing organic pollutants in the soil samples for off-site remediation corresponding to different pollution types, and generate soil samples for off-site remediation that contain heavy metals and have completed organic pollution remediation.

[0019] Furthermore, step S23 includes the following steps:

[0020] Step S231: By studying the energy release during the combustion of the biogas heat source, measure the calorific value of the biogas heat source through a combustion calorimeter, and draw the combustion temperature curve of the biogas heat source according to the calorific value;

[0021] Step S232: Based on the combustion temperature curve of the biogas heat source, perform combustion efficiency statistics on the biogas heat source to obtain the combustion efficiency of the biogas heat source;

[0022] Step S233: Place the soil samples for off-site remediation containing organic pollutants in the soil samples for off-site remediation corresponding to different pollution types in the corresponding repair reactor in the landfill, and control the biogas intake and combustion intensity in the repair reactor based on the combustion efficiency of the biogas heat source, so that the soil temperature in the repair reactor is within the temperature range suitable for organic pollutant desorption, specifically 100 - 300 °C;

[0023] Step S234: Based on the controlled temperature range and using the repair reactor, perform organic pollution desorption and transformation on the soil samples for off-site remediation containing organic pollutants in the soil samples for off-site remediation corresponding to different pollution types, and generate soil samples for off-site remediation that contain heavy metals and have completed organic pollution remediation.

[0024] Furthermore, step S234 includes the following steps:

[0025] Based on the controlled temperature range and using the repair reactor, perform organic pollution desorption on the soil samples for off-site remediation containing organic pollutants in the soil samples for off-site remediation corresponding to different pollution types, apply ultrasonic waves with a corresponding frequency in the repair reactor based on the temperature range, and use the cavitation effect and mechanical vibration effect of the ultrasonic waves to destroy the adsorption force between the soil particles and the organic pollutants, so as to obtain the soil samples after organic pollutant desorption;

[0026] Transfer the soil sample after desorbing organic pollutants to the corresponding aerobic environment in the remediation reactor, and oxidize and decompose the desorbed organic pollutants in the soil sample by adding the corresponding metal oxide catalyst, so as to quickly and thoroughly decompose and transform the corresponding organic pollutants into harmless carbon dioxide and water substances in the aerobic environment, and obtain the soil sample after the organic pollution is oxidized and decomposed;

[0027] Obtain the corresponding residual amount of organic pollutants and the contents of decomposition products carbon dioxide, water and incompletely decomposed intermediate products in the gas through the soil sample after the organic pollution is oxidized and decomposed. At the same time, obtain the concentration of organic pollutants in the initial soil sample, and based on the concentration of organic pollutants in the initial soil sample, the residual amount of organic pollutants and the contents of decomposition products carbon dioxide, water and incompletely decomposed intermediate products in the gas, use the organic pollution removal rate calculation formula to perform quantitative calculation on the soil sample after the organic pollution is oxidized and decomposed, so as to obtain the organic pollution removal rate of the soil sample;

[0028] Obtain the temperature, pressure and biogas consumption rate of the remediation reactor, and analyze the operating efficiency of the remediation reactor according to the temperature, pressure and biogas consumption rate;

[0029] Based on the organic pollution removal rate of the soil sample and the operating efficiency of the remediation reactor, optimize and adjust the organic pollution removal of the soil sample after the organic pollution is oxidized and decomposed, so as to judge the soil sample with incomplete organic pollution removal according to the comparison between the preset removal threshold and the organic pollution removal rate of the soil sample, and based on the operating efficiency of the remediation reactor, optimize and adjust the soil sample with incomplete organic pollution removal, so as to strengthen the desorption and catalytic reaction conditions of the remediation reactor, and generate the off-site remediation soil sample containing heavy metals and with the organic pollution repaired.

[0030] Further, the specific formula for the organic pollution removal rate is:

[0031]

[0032] In the formula, R is the organic pollution removal rate of the soil sample, T is the total duration of the removal time, t is the time variable parameter, C(t) is the residual amount of organic pollutants at time t, m c is the content corresponding to carbon dioxide, the decomposition product in the gas, m h is the content corresponding to water, the decomposition product in the gas, n is the total number of incompletely decomposed intermediate products in the gas, P i is the content corresponding to the i-th incompletely decomposed intermediate product, β i is the relative molecular mass corresponding to the i-th incompletely decomposed intermediate product, C 0 is the concentration of organic pollutants in the initial soil sample.

[0033] Further, step S3 includes the following steps:

[0034] Step S31: Perform solidification-stabilization coupling remediation on the off-site remediation soil sample containing heavy metals after the organic pollution has been remediated, add a solidifying agent and a stabilizing agent to the corresponding soil sample, and fully mix the solidifying agent, the stabilizing agent and the soil sample through a stirring and mixing device. Under certain temperature and humidity conditions, the solidifying agent reacts chemically with the corresponding heavy metals in the soil sample to form stable compounds, while the stabilizing agent forms chelates with the corresponding heavy metal ions, and the corresponding compounds and chelates are removed to generate a heavy metal-containing soil sample after solidification-stabilization remediation;

[0035] Step S32: Conduct a chemical environmental impact assessment analysis on the heavy metal-containing soil sample after solidification-stabilization remediation to chemically analyze the residual amounts of the corresponding organic pollutants and heavy metals in the soil sample, and determine whether the corresponding soil remediation target is reached to obtain the environmental impact assessment result of the remediated soil sample;

[0036] Step S33: Compare and judge the environmental impact assessment result of the remediated soil sample. If the environmental impact assessment result of the remediated soil sample has reached the corresponding soil remediation target, determine the corresponding heavy metal-containing soil sample as the soil sample after the organic pollution and heavy metal remediation have been completed; if the environmental impact assessment result of the remediated soil sample has not reached the corresponding soil remediation target, re-perform the cyclic organic pollution desorption and solidification-stabilization remediation treatment on the corresponding heavy metal-containing soil sample until the corresponding soil remediation target has been reached, and generate the soil sample after the organic pollution and heavy metal remediation have been completed.

[0037] Further, step S4 includes the following steps:

[0038] Step S41: Perform co-solidification treatment on the corresponding fly ash in the landfill with the soil sample after the organic pollution and heavy metal remediation have been completed, add an appropriate amount of solidifying agent and additive to the fly ash and mix it with the soil sample after the organic pollution and heavy metal remediation have been completed in a certain proportion, and prepare the corresponding solidified fly ash block through a pressure forming device to obtain the soil-solidified fly ash block after remediation;

[0039] Step S42: Transport the soil-solidified fly ash block after remediation to the corresponding fly ash landfill area in the landfill, and use the soil-solidified fly ash block as the pore soil corresponding to the fly ash layer and the intermediate corresponding covering soil for fly ash landfill reuse, use the corresponding pores to fill and compact the soil-solidified fly ash block to form the corresponding pore soil, and through the designed unit thickness of the fly ash landfill to meet the mid-term covering of the landfill geomembrane and level and compact it to form the corresponding covering soil, and generate the remediated off-site fly ash landfill reused soil.

[0040] Furthermore, the present invention also provides a landfill-coupled off-site remediation system for contaminated soil, which is used to implement the landfill-coupled off-site remediation method for contaminated soil as described above. The landfill-coupled off-site remediation system for contaminated soil includes:

[0041] A contaminated soil sample classification module, which is used to perform depth stratified sampling on the corresponding off-site remediation contaminated soil heap in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; classify the characteristics of the off-site remediation contaminated soil samples corresponding to different depth levels, so as to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, heavy metals, and those containing both organic pollution and heavy metals;

[0042] An organic pollution desorption and remediation module, which is used to obtain the corresponding purified biogas from the landfill as a heat source, and based on the heat source, perform organic pollution desorption and conversion on the off-site remediation soil samples containing organic pollutants among the off-site remediation soil samples corresponding to different pollution types, so as to generate off-site remediation soil samples that contain heavy metals and have completed organic pollution remediation;

[0043] A heavy metal and environmental impact assessment cyclic remediation module, which is used to perform solidification and stabilization coupling remediation on the off-site remediation soil samples that contain heavy metals and have completed organic pollution remediation to generate solidification and stabilization repaired heavy metal-containing soil samples; perform chemical environmental impact assessment analysis on the solidification and stabilization repaired heavy metal-containing soil samples to obtain the environmental impact assessment results of the repaired soil samples; based on the environmental impact assessment results of the repaired soil samples, perform cyclic remediation treatment on the solidification and stabilization repaired heavy metal-containing soil samples, so as to generate soil samples that have completed organic pollution and heavy metal remediation;

[0044] A fly ash landfill and reuse module, which is used to perform fly ash landfill and reuse on the soil samples that have completed organic pollution and heavy metal remediation based on the landfill, so as to generate off-site fly ash landfill and reused soil after remediation.

[0045] Advantages of the present invention:

[0046] 1. Compared with the prior art, the beneficial effect of the method for coupling and off-site remediation of contaminated soil in a landfill proposed by the present invention lies in obtaining soil samples at different depths through deep stratified sampling within the disposal center of the landfill, thereby understanding the hierarchical characteristics of the contaminated soil. This sampling method can accurately capture the soil pollution conditions at different depths, enabling subsequent remediation measures to be more targeted. When classifying soil samples, they are divided according to the type of pollution, including soil containing organic pollutants, soil containing heavy metals, and soil containing both organic pollutants and heavy metals. This classification method helps to deeply understand the interaction and influence mechanism of different pollutants, providing an important basis for the design of subsequent remediation plans. Secondly, the purified biogas in the landfill is used as a heat source to desorb and transform the soil containing organic pollutants. As a natural gas, biogas is rich in combustible gases such as methane and has good calorific value, which can provide an efficient heat source for the desorption of organic pollutants. Through heat treatment, organic pollutants can be promoted to desorb from soil particles and be transformed into harmless substances or accelerated decomposition through biodegradation under certain conditions. This process can not only effectively remove organic pollutants in the soil but also make full use of the corresponding biogas resources in the landfill, avoid using chemical reagents, and reduce secondary pollution generated during the remediation process. In addition, the high efficiency of the heat source remediation method can significantly improve the remediation speed and shorten the remediation cycle. After this treatment, organic pollutants in the soil are effectively removed, and heavy metal pollution in the soil is relatively isolated, laying a foundation for subsequent heavy metal remediation. Then, by applying the solidification / stabilization technology to the remediation of soil containing heavy metals, the aim is to immobilize heavy metal elements in the soil through physical and chemical means, reduce their mobility and bioavailability, and prevent secondary pollution of heavy metal pollutants to the environment. The solidification / stabilization remediation can not only reduce the concentration of heavy metals in the soil but also change the chemical form of heavy metals to make them in a low-toxic and low-solubility state. After the remediation is completed, chemical environmental impact assessment analysis is carried out to ensure that the remediation effect meets the environmental safety standards. Through this series of measures, effective remediation of soil contaminated with heavy metals can be achieved, and the remediated soil can meet environmental protection requirements. If the chemical environmental impact assessment results do not meet the standards, further cyclic remediation treatment can be applied to ensure the safety of the remediated soil, thus greatly enhancing the sustainability and environmental friendliness of soil remediation.Finally, the repaired soil is further utilized through the landfill reuse of fly ash to achieve the purpose of resource treatment. The landfill reuse of fly ash can not only effectively reduce the impact of waste on the environment, but also convert waste into useful resources. By combining the repaired soil with fly ash, it can not only further stabilize and solidify the repaired soil, but also, through the action of certain mineral components in fly ash, further promote the immobilization of heavy metals in the soil and the improvement of soil structure. In this process, the addition of fly ash can provide additional mineral components, improve the physical and chemical properties of the soil, and further enhance its stability and usability. Through the landfill reuse of fly ash, the repaired soil resources can be reused to the greatest extent, avoiding secondary pollution of waste, and providing a new way for the treatment of waste in landfills, ensuring that the repaired soil can be effectively recycled between the landfill and resources, thereby realizing the harmless and resource treatment of the soil repaired in different places.

[0047] 2. The landfill-coupled contaminated soil off-site repair system proposed by the present invention is generally composed of a contaminated soil sample classification module, an organic pollution desorption and repair module, a heavy metal and environmental assessment cycle repair module, and a fly ash landfill reuse module, and can implement any of the landfill-coupled contaminated soil off-site repair methods described in the present invention. The operation between computer programs running on each module is used to implement the landfill-coupled contaminated soil off-site repair method. The internal structure of the system cooperates with each other, which can greatly reduce repetitive work and manpower input, and can quickly and effectively provide a more accurate and efficient landfill-coupled contaminated soil off-site repair process, thereby simplifying the operation process of the landfill-coupled contaminated soil off-site repair system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0049] Figure 1 It is a schematic flow chart of the steps of the landfill-coupled contaminated soil off-site repair method of the present invention;

[0050] Figure 2 For Figure 1 a detailed schematic flow chart of step S1 in

[0051] Figure 3 For Figure 1 a detailed schematic flow chart of step S2 in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The technical method of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0053] In addition, the accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor methods and / or microcontroller methods.

[0054] It should be understood that although the terms "first", "second", etc. may be used here to describe each unit, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, the first unit can be called the second unit, and similarly the second unit can be called the first unit. The term "and / or" used here includes any and all combinations of one or more of the listed related items.

[0055] To achieve the above object, please refer to Figures 1 to 3 , the present invention provides a method for off-site remediation of contaminated soil coupled with a landfill, and the method includes the following steps:

[0056] Step S1: Conduct in-depth stratified sampling on the corresponding off-site remediation contaminated soil piles in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; classify the characteristics of the off-site remediation contaminated soil samples corresponding to different depth levels to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, heavy metals, and those containing both organic pollution and heavy metals.

[0057] Step S2: Obtain the corresponding purified biogas from the landfill as a heat source, and based on the heat source, perform organic pollution desorption and conversion on the off-site remediation soil samples containing organic pollutants among the off-site remediation soil samples corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0058] Step S3: Perform solidification-stabilization coupled remediation on the off-site remediated soil samples containing heavy metals that have completed organic pollution remediation to generate heavy metal-containing soil samples after solidification-stabilization remediation; conduct chemical environmental impact assessment analysis on the heavy metal-containing soil samples after solidification-stabilization remediation to obtain the environmental impact assessment results of the remediated soil samples; based on the environmental impact assessment results of the remediated soil samples, perform cyclic remediation treatment on the heavy metal-containing soil samples after solidification-stabilization remediation to generate soil samples that have completed organic pollution and heavy metal remediation.

[0059] Step S4: Based on the landfill, perform fly ash landfill reuse on the soil samples that have completed organic pollution and heavy metal remediation to generate off-site fly ash landfill reused soil after remediation.

[0060] In the embodiment of the present invention, please refer to Figure 1 As shown in the figure, it is a schematic flow chart of the steps of the method for coupling off-site remediation of polluted soil in a landfill in the present invention. In this example, the method for coupling off-site remediation of polluted soil in the landfill includes the following steps:

[0061] Step S1: Conduct in-depth stratified sampling on the corresponding off-site remediated polluted soil heap in the disposal center of the landfill to obtain off-site remediated polluted soil samples corresponding to different depth levels; classify the characteristics of the off-site remediated polluted soil samples corresponding to different depth levels to obtain off-site remediated soil samples corresponding to different pollution types, including off-site remediated soil samples containing organic pollutants, heavy metals, and both organic pollution and heavy metals.

[0062] In the embodiment of the present invention, through the disposal center of the landfill, in-depth stratified sampling is carried out on the off-site remediated polluted soil heap. A professional soil sampling drill is selected, which is equipped with a drill bit with a diameter of 5 cm and can accurately drill into the soil heap. Starting from the surface of the soil heap at intervals of 0.5 m, samples are drilled from shallow to deep in sequence. For each sample collected, the sampling location and depth are clearly marked with a label immediately, and then the sample is properly placed in a sealed container to prevent pollution and moisture loss. After sampling, the characteristics of these samples are classified. Atomic absorption spectrometers are used to detect heavy metals such as lead, mercury, and cadmium; gas chromatography-mass spectrometry is used to analyze organic pollutants such as polycyclic aromatic hydrocarbons and petroleum hydrocarbons. According to the detection results, the samples are divided into three different pollution types of off-site remediated soil samples: those containing organic pollutants, those containing heavy metals, and those containing both organic pollution and heavy metals.

[0063] Step S2: Obtain the corresponding purified biogas from the landfill as a heat source, and based on the heat source, perform organic pollution desorption and conversion on the off-site remediated soil samples containing organic pollutants among the off-site remediated soil samples corresponding to different pollution types to generate off-site remediated soil samples containing heavy metals that have completed organic pollution remediation.

[0064] In an embodiment of the present invention, a landfill uses a biogas collection system to transport the collected biogas to a purification device. Inside the purification device, the biogas first passes through a desulfurization tower to remove hydrogen sulfide, and then through a dryer to remove moisture and impurities, finally obtaining purified biogas. The purified biogas is introduced into a remediation reactor as a heat source for treating off-site remediated soil samples containing organic pollutants. In the remediation reactor, the combustion intensity is controlled by adjusting the biogas intake to maintain the temperature inside the reactor within a suitable range of 100 - 300 °C. At this temperature, the thermal motion of organic pollutant molecules intensifies, and the adsorption force between them and soil particles weakens, thus desorbing. Meanwhile, using the catalyst and oxygen inside the reactor, the desorbed organic pollutants are promoted to oxidize and decompose, converting into carbon dioxide and water, and finally generating off-site remediated soil samples containing heavy metals and having completed organic pollution remediation.

[0065] Step S3: Perform solidification - stabilization coupling remediation on the off - site remediated soil samples containing heavy metals and having completed organic pollution remediation to generate solidification - stabilization remediated heavy - metal - containing soil samples; conduct chemical environmental impact assessment analysis on the solidification - stabilization remediated heavy - metal - containing soil samples to obtain the environmental impact assessment results of the remediated soil samples; based on the environmental impact assessment results of the remediated soil samples, perform cyclic remediation treatment on the solidification - stabilization remediated heavy - metal - containing soil samples to generate soil samples that have completed organic pollution and heavy - metal remediation.

[0066] In an embodiment of the present invention, for off - site remediated soil samples containing heavy metals and having completed organic pollution remediation, solidification - stabilization coupling remediation is carried out. 10% cement is added as a solidifying agent and 5% sodium diethyldithiocarbamate is added as a stabilizing agent to the soil samples, and they are fully mixed using a stirring device. Subsequently, the mixed samples are placed in a constant - temperature and constant - humidity curing box and cured for 7 days under the conditions of 25 °C and 60% humidity. During this period, the solidifying agent reacts chemically with heavy metals to form stable compounds; the stabilizing agent forms chelates with heavy - metal ions. After 7 days, the residual amounts of organic pollutants and heavy metals are detected by chemical analysis instruments, and chemical environmental impact assessment analysis is carried out. If the repair target is not reached, organic pollution desorption and solidification - stabilization remediation are carried out again until the standard is met, and finally soil samples that have completed organic pollution and heavy - metal remediation are generated.

[0067] Step S4: Based on the landfill, perform fly - ash landfill reuse on the soil samples that have completed organic pollution and heavy - metal remediation to generate off - site fly - ash landfill - reused soil after remediation.

[0068] In an embodiment of the present invention, based on the planning of the landfill, soil samples after the remediation of organic pollution and heavy metals are used for the landfill reuse of fly ash. In the fly ash landfill special zone, first, determine the position of the pore soil in the fly ash layer, fill the soil samples into the pores, and use a vibratory roller to compact at a speed of 5 kilometers per hour and a pressure of 2 tons to form pore soil. For the cover soil, lay the soil samples according to the design requirements to form a layered structure with a thickness of 0.5 meters. After leveling with a grader, compact at a speed of 4 kilometers per hour and a pressure of 3 tons to meet the mid-term covering requirements of the landfill geomembrane, and finally generate the remediated off-site fly ash landfill reused soil.

[0069] Further, step S1 includes the following steps:

[0070] Step S11: Conduct deep stratified sampling on the corresponding off-site remediated polluted soil heap in the disposal center of the landfill, sample a soil sample every 0.5 meters and mark the corresponding sampling location and depth to obtain off-site remediated polluted soil samples corresponding to different depth levels;

[0071] Step S12: Detect the heavy metal content of the off-site remediated polluted soil samples corresponding to different depth levels to obtain the soil heavy metal content corresponding to different types at each depth level;

[0072] Step S13: Analyze the types of organic pollutants in the off-site remediated polluted soil samples corresponding to different depth levels to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons in them, and obtain the types of soil organic pollutants corresponding to each depth level;

[0073] Step S14: Classify the soil sample characteristics of the corresponding off-site remediated polluted soil samples based on the soil heavy metal content corresponding to different types at each depth level and the types of soil organic pollutants corresponding to each depth level to obtain off-site remediated soil samples corresponding to different pollution types, including off-site remediated soil samples containing organic pollutants, containing heavy metals, and containing both organic pollution and heavy metals.

[0074] As an embodiment of the present invention, refer to Figure 2 shown in Figure 1 is a detailed step flow diagram of step S1 in

[0075] Step S11: Conduct deep stratified sampling on the corresponding off-site remediated polluted soil heap in the disposal center of the landfill, sample a soil sample every 0.5 meters and mark the corresponding sampling location and depth to obtain off-site remediated polluted soil samples corresponding to different depth levels;

[0076] In an embodiment of the present invention, at the disposal center of a landfill, in-situ remediation of contaminated soil piles from other locations is carried out with in-depth stratified sampling. By using a professional soil sampling drill with a drill bit diameter of 5 cm, samples can be accurately taken from the soil piles. Sampling is carried out at intervals of 0.5 m. For each sample taken, the corresponding sampling location and depth information are immediately labeled with tags. During the sampling process, the order from shallow to deep is strictly followed to ensure the representativeness and accuracy of the samples. For example, sampling operations are carried out at different positions such as the edge and center of the pile to comprehensively obtain the soil conditions in different areas. The collected soil samples are placed in special sealed containers to prevent the samples from being contaminated by the outside world and losing moisture. Finally, in-situ remediation of contaminated soil samples corresponding to different depth levels are obtained.

[0077] Step S12: Detect the heavy metal content of the in-situ remediation of contaminated soil samples corresponding to each different depth level to obtain the soil heavy metal content corresponding to different types at each depth level;

[0078] In an embodiment of the present invention, for the in-situ remediation of contaminated soil samples corresponding to each different depth level, heavy metal content detection is carried out. An atomic absorption spectrometer is used to determine the heavy metal content such as lead, mercury, and cadmium in the samples. First, the soil samples are pretreated by using the method of aqua regia digestion to dissolve the heavy metal elements in the samples. Then, the digested solution is injected into the atomic absorption spectrometer. The instrument irradiates the solution with light of a specific wavelength, and according to the absorption degree of the heavy metal elements to the light, the content of different types of heavy metals such as lead, mercury, and cadmium is accurately calculated. During the detection process, every 10 samples are calibrated with standard substances to ensure the accuracy of the detection results. After a series of detection operations, the soil heavy metal content corresponding to different types at each depth level is finally obtained.

[0079] Step S13: Analyze the types of organic pollutants in the in-situ remediation of contaminated soil samples corresponding to each different depth level to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons in them, and obtain the types of soil organic pollutants corresponding to each depth level;

[0080] In the embodiment of the present invention, by analyzing the types of organic pollutants in the off-site remediation contaminated soil samples corresponding to different depth levels, using a gas chromatography-mass spectrometry (GC-MS) instrument for analysis. First, the soil samples are mixed with an organic solvent, and through ultrasonic extraction, the organic pollutants in the soil are dissolved into the organic solvent. Then, the extract is injected into the GC-MS instrument. The gas chromatography part separates different organic pollutants according to the different distribution coefficients of the organic pollutants between the stationary phase and the mobile phase, and the mass spectrometry part conducts qualitative analysis on them based on the mass and structural information of the organic pollutant molecules. Through this method, organic pollutants such as polycyclic aromatic hydrocarbons and petroleum hydrocarbons in the samples are analyzed emphatically. After detailed analysis, the types of soil organic pollutants corresponding to each depth level are finally obtained.

[0081] Step S14: Classify the corresponding off-site remediation contaminated soil samples based on the soil heavy metal contents corresponding to different types at each depth level and the types of soil organic pollutants corresponding to each depth level to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, heavy metals, and both organic pollutants and heavy metals.

[0082] In the embodiment of the present invention, based on the soil heavy metal contents corresponding to different types at each depth level and the types of soil organic pollutants corresponding to each depth level, the corresponding off-site remediation contaminated soil samples are classified for soil sample characteristics. If polycyclic aromatic hydrocarbons, petroleum hydrocarbons and other organic pollutants are detected in the sample but heavy metals such as lead, mercury, and cadmium are not detected, it is classified as an off-site remediation soil sample containing organic pollutants; if only heavy metals such as lead, mercury, and cadmium are detected in the sample and no organic pollutants are detected, it is classified as an off-site remediation soil sample containing heavy metals; if both organic pollutants and heavy metals are detected in the sample, it is classified as an off-site remediation soil sample containing both organic pollutants and heavy metals. Through this classification method, off-site remediation soil samples corresponding to different pollution types are finally obtained.

[0083] Furthermore, the soil heavy metal contents corresponding to different types in step S12 specifically include the heavy metal contents corresponding to types of lead, mercury, and cadmium.

[0084] Furthermore, step S2 includes the following steps:

[0085] Step S21: Set up biogas collection wells in the landfill and use pipelines to transport the biogas collected in the biogas collection wells to the biogas purification device.

[0086] Step S22: purifying the collected biogas using a biogas purification device to purify and remove the corresponding hydrogen sulfide and water impurities in the biogas, and improve the corresponding purity of the biogas, so as to obtain the corresponding purified biogas and simultaneously transport it to the contaminated soil remediation area through a pipeline as the corresponding biogas heat source in the remediation process;

[0087] Step S23: Based on the biogas heat source, the ex situ remediation soil samples containing organic pollutants in the ex situ remediation soil samples corresponding to different pollution types are subjected to organic pollution desorption and transformation, so as to generate ex situ remediation soil samples containing heavy metals and after the organic pollution remediation is completed.

[0088] As an embodiment of the present invention, refer to Figure 3 As shown, Figure 1 Detailed step flow diagram of step S2 in the embodiment, step S2 includes the following steps:

[0089] Step S21: a biogas collection well is set up in the landfill, and the biogas collected in the biogas collection well is transported to the biogas purification device through a pipeline;

[0090] In an embodiment of the present invention, a plurality of biogas collection wells are rationally planned and arranged in a landfill, and are laid out according to the area of ​​the landfill and the distribution of garbage, with one biogas collection well being arranged for every 50 square meters. The biogas collection wells are made of corrosion-resistant high-strength plastic, and air inlet holes with a diameter of 5 mm are evenly distributed on the well wall to ensure that biogas can smoothly enter the well. A sealing cover is installed on the top of each biogas collection well to prevent the entry of external air. A polyethylene pipe with a diameter of 10 cm is used to connect the biogas collection wells, and then the pipes are uniformly transported to a biogas purification device. The pipes are connected by hot-melt connection to ensure a tight connection and prevent biogas leakage. A gas flow meter and a pressure sensor are installed on the pipe to monitor the flow and pressure of biogas in real time to provide data support for subsequent operations.

[0091] Step S22: purifying the collected biogas using a biogas purification device to purify and remove the corresponding hydrogen sulfide and water impurities in the biogas, and improve the corresponding purity of the biogas, so as to obtain the corresponding purified biogas and simultaneously transport it to the contaminated soil remediation area through a pipeline as the corresponding biogas heat source in the remediation process;

[0092] In the embodiment of the present invention, after biogas enters the biogas purification device, hydrogen sulfide is first removed through a desulfurization tower filled with iron oxide desulfurizer. The biogas passes through the desulfurization tower at a flow rate of 50 cubic meters per hour. Under the action of the desulfurizer, hydrogen sulfide reacts chemically with iron oxide to form iron sulfide precipitate, thus achieving the removal of hydrogen sulfide. Then, the biogas enters a dryer to remove moisture impurities. The dryer is filled with silica gel desiccant. The biogas stays in the dryer for 10 minutes. The silica gel desiccant adsorbs the moisture in the biogas, reducing the water content of the biogas to less than 1%. After desulfurization and drying treatment, the purity of the biogas is significantly improved. The purified biogas is detected by a gas analyzer to ensure that its purity reaches more than 90%. The purified biogas is transported through a pipeline to the contaminated soil remediation area and used as the biogas heat source during the remediation process.

[0093] Step S23: Based on the biogas heat source, perform organic pollution desorption and conversion on the soil samples for off-site remediation containing organic pollutants in the soil samples for off-site remediation corresponding to different pollution types, to generate soil samples for off-site remediation containing heavy metals and having completed organic pollution remediation.

[0094] In the embodiment of the present invention, by placing the soil samples for off-site remediation containing organic pollutants in different pollution types in the remediation reactor in the contaminated soil remediation area, and using a pipeline to transport the purified biogas to the burner in the remediation reactor. The burner adopts a premixed combustion method to ensure that the biogas can burn fully. By adjusting the valve opening of the burner, the intake volume of the biogas is controlled, thereby adjusting the combustion intensity. A temperature sensor is installed in the remediation reactor to monitor the soil temperature in real time. When the soil temperature is lower than 100 °C, the intake volume of the biogas is increased to increase the combustion intensity and raise the soil temperature. When the soil temperature is higher than 300 °C, the intake volume of the biogas is reduced to lower the combustion intensity and lower the soil temperature, ensuring that the soil temperature is stable within the range of 100 - 300 °C. Within this temperature range, the thermal motion of organic pollutant molecules intensifies, and the adsorption force between them and soil particles weakens, so they desorb from the surface of soil particles. At the same time, using the catalyst and oxygen in the remediation reactor, the desorbed organic pollutants undergo oxidation decomposition reactions and are converted into harmless carbon dioxide and water. After a period of treatment, the organic pollutants are fully desorbed and converted, and finally soil samples for off-site remediation containing heavy metals and having completed organic pollution remediation are generated.

[0095] Further, step S23 includes the following steps:

[0096] Step S231: By studying the energy release corresponding to the biogas heat source during combustion, measure the combustion calorific value corresponding to the biogas heat source through a combustion calorimeter, and draw a combustion temperature curve corresponding to the biogas heat source according to the combustion calorific value;

[0097] In the embodiment of the present invention, in a laboratory environment, a professional calorimeter is used to measure the calorific value of the biogas heat source. First, a certain amount of the biogas heat source is accurately injected into the reaction vessel of the calorimeter. This reaction vessel has good heat insulation performance, which can minimize heat loss to the greatest extent. The instrument is started to allow the biogas heat source to burn fully in a pure oxygen environment. The heat released during the combustion process will be accurately captured and recorded by the calorimeter. Through multiple repeated measurements, the average value is taken to ensure the accuracy of the data. According to the measured calorific value data, with the combustion time as the abscissa and the combustion temperature as the ordinate, a combustion temperature curve corresponding to the biogas heat source is drawn using drawing software. This curve can intuitively show the change of the temperature of the biogas heat source with time during the combustion process, providing an important basis for subsequent analysis.

[0098] Step S232: Based on the combustion temperature curve corresponding to the biogas heat source, conduct a combustion efficiency statistics on the biogas heat source to obtain the combustion efficiency corresponding to the biogas heat source;

[0099] In the embodiment of the present invention, by based on the drawn combustion temperature curve of the biogas heat source, the combustion efficiency of the biogas heat source is statistically analyzed. First, determine the stage in the curve where the highest combustion temperature is reached. This stage represents the moment when the biogas heat source burns most fully. By analyzing the rising and falling trends of the curve, calculate the time period during which heat is effectively released during the combustion process. Compare the heat released during this time period with the heat that can be released theoretically when the biogas heat source burns completely. The theoretically complete combustion heat can be accurately calculated according to the chemical composition of the biogas and the chemical reaction equation. Through this comparison, the combustion efficiency corresponding to the biogas heat source is obtained. For example, if the heat released during the effective combustion time period accounts for 80% of the theoretically complete combustion heat, then the combustion efficiency of this biogas heat source is 80%.

[0100] Step S233: Place the soil samples for ex-situ remediation containing organic pollutants in the corresponding remediation reactors in the landfill for different pollution types, and control the corresponding biogas intake and combustion intensity in the remediation reactors based on the combustion efficiency corresponding to the biogas heat source, so that the soil temperature in the remediation reactors is within the temperature range suitable for the desorption of organic pollutants, specifically 100 - 300 °C;

[0101] In the embodiment of the present invention, by accurately placing the off-site repaired soil samples containing organic pollutants in different pollution types into the repair reactor in the landfill, according to the previously obtained combustion efficiency of the biogas heat source, the biogas intake volume and combustion intensity in the repair reactor are precisely controlled. When the combustion efficiency is high, the biogas intake volume is appropriately reduced to avoid excessive soil temperature caused by too much heat. When the combustion efficiency is low, the biogas intake volume is increased to improve the combustion intensity to ensure sufficient heat supply. The soil temperature is monitored in real time by the temperature sensor installed in the repair reactor, and the monitoring data is fed back to the control system. The control system automatically adjusts the opening of the biogas intake valve and the power of the burner according to the feedback data, so that the soil temperature in the repair reactor is stabilized within the suitable temperature range of 100-300°C for the desorption of organic pollutants.

[0102] Step S234: Based on the controlled temperature range and using the repair reactor, perform organic pollution desorption and conversion on the off-site repaired soil samples containing organic pollutants in the off-site repaired soil samples corresponding to different pollution types, and generate off-site repaired soil samples containing heavy metals and having completed organic pollution repair.

[0103] In the embodiment of the present invention, after the soil temperature in the repair reactor is stabilized within the controlled temperature range of 100-300°C, the off-site repaired soil samples containing organic pollutants are started to be subjected to organic pollution desorption and conversion. Within this temperature range, the thermal motion of organic pollutant molecules intensifies, and the adsorption force between them and soil particles weakens, so that they are desorbed from the surface of soil particles. At the same time, using the specific catalytic environment and chemical reaction conditions in the repair reactor, the desorbed organic pollutants undergo conversion reactions. For example, some organic pollutants will undergo oxidation decomposition reactions under the action of high temperature and catalysts and be converted into harmless carbon dioxide and water. After a period of treatment, the organic pollutants are fully desorbed and converted, and finally off-site repaired soil samples containing heavy metals and having completed organic pollution repair are generated.

[0104] Further, step S234 includes the following steps:

[0105] Based on the controlled temperature range and using the repair reactor, perform organic pollution desorption on the off-site repaired soil samples containing organic pollutants in the off-site repaired soil samples corresponding to different pollution types, apply ultrasonic waves with corresponding frequencies in the repair reactor based on the temperature range, and use the cavitation effect and mechanical vibration effect corresponding to the ultrasonic waves to break the adsorption force between soil particles and organic pollutants, so as to obtain soil samples after organic pollutant desorption;

[0106] In the embodiment of the present invention, by precisely controlling the temperature range within 30 - 50 degrees Celsius, this temperature range can provide a suitable environment for the subsequent desorption of organic pollutants. It not only ensures a certain activity of the organic pollutants in the soil but also avoids unnecessary energy waste caused by excessive temperature or adverse effects on the soil structure. Soil samples from different contaminated sites containing organic pollutants are placed in a repair reactor, and an ultrasonic generator is started with its frequency set to 20 kHz. In the repair reactor, the ultrasonic waves continuously propagate, and their cavitation effect causes tiny bubbles to form in the liquid. These bubbles rapidly collapse after growing to a certain extent, instantaneously generating an extreme environment of local high temperature and high pressure. At the same time, the mechanical vibration of the ultrasonic waves continuously acts on the soil particles and organic pollutants. These two effects jointly destroy the adsorption force between the soil particles and the organic pollutants. After 2 hours of continuous treatment, the organic pollutants are successfully desorbed from the soil particles, and finally, a soil sample after desorption of organic pollutants is obtained.

[0107] Preferably, the soil sample after desorption of organic pollutants is transferred to the corresponding aerobic environment in the repair reactor, and the desorbed organic pollutants in the soil sample are oxidized and decomposed by adding the corresponding metal oxide catalyst, so as to rapidly and completely decompose and transform the corresponding organic pollutants into harmless carbon dioxide and water substances in the aerobic environment, and a soil sample after oxidation and decomposition of organic pollution is obtained;

[0108] In the embodiment of the present invention, the soil sample after desorption of organic pollutants is transferred to the aerobic environment in the repair reactor through a special conveying device. In this environment, manganese dioxide is added as a metal oxide catalyst through a precise feeding device, and the addition amount is strictly controlled at 3% of the mass of the soil sample. Under aerobic conditions, the manganese dioxide catalyst plays a key role. The active sites on its surface can adsorb the desorbed organic pollutants and oxygen molecules, promoting them to undergo chemical reactions. Within the next 3 hours, the organic pollutants fully react with oxygen under the action of the catalyst, and their molecular structure is gradually destroyed and oxidized and decomposed. Finally, the organic pollutants are rapidly and completely transformed into harmless carbon dioxide and water substances, thereby obtaining a soil sample after oxidation and decomposition of organic pollution.

[0109] Preferably, the residual amount of the corresponding organic pollutants and the contents of the decomposition products carbon dioxide, water, and incompletely decomposed intermediate products in the gas are obtained by detecting the soil sample after oxidation and decomposition of organic pollution. At the same time, the concentration of organic pollutants in the initial soil sample is obtained, and based on the concentration of organic pollutants in the initial soil sample, the residual amount of organic pollutants, and the contents of the decomposition products carbon dioxide, water, and incompletely decomposed intermediate products in the gas, the removal quantification calculation of the soil sample after oxidation and decomposition of organic pollution is carried out using the organic pollution removal rate calculation formula to obtain the organic pollutant removal rate of the soil sample;

[0110] In the embodiment of the present invention, for the soil sample after the organic pollution is oxidized and decomposed, a variety of chemical analysis instruments are used for detection. The gas chromatography-mass spectrometry is used to analyze the soil sample, and the residual amount of organic pollutants in it can be accurately determined. The infrared gas analyzer is used to detect the gas components to obtain the contents of the decomposition products carbon dioxide, water and the incompletely decomposed intermediate products. At the same time, when processing the initial soil sample, the spectrophotometer is used to determine the concentration of organic pollutants in it. These key data are substituted into a suitable organic pollution removal rate calculation formula composed of the total duration of the removal time, the time variable parameter, the residual amount of organic pollutants, the content of the decomposition product carbon dioxide in the gas, the content of the decomposition product water in the gas, the content of the incompletely decomposed intermediate product, the relative molecular mass of the incompletely decomposed intermediate product, the concentration of organic pollutants in the initial soil sample and related parameters for calculation. After accurate calculation, the organic pollution removal rate of the soil sample is obtained to quantify the removal effect of organic pollution. In addition, the organic pollution removal rate calculation formula can also use any removal rate calculation method in the field to replace the process of removal quantification calculation. For example, the removal rate = (initial concentration - residual amount) / initial concentration × 100%, and it is not limited to this organic pollution removal rate calculation formula.

[0111] Preferably, the temperature, pressure and biogas consumption rate corresponding to the repair reactor are obtained, and the operating efficiency corresponding to the repair reactor is analyzed according to the temperature, pressure and biogas consumption rate;

[0112] In the embodiment of the present invention, during the operation of the repair reactor, the internal temperature is monitored in real time by a temperature sensor, the pressure is continuously measured by a pressure sensor, and the biogas consumption rate is accurately measured by a gas flowmeter. The temperature, pressure and biogas consumption rate data obtained by these sensors are transmitted to the data analysis system through a data transmission line. In the data analysis system, through the established mathematical model and reaction kinetics principle, the relationship between temperature, pressure and reaction rate is analyzed. For example, an increase in temperature will accelerate the reaction rate, but too high a temperature will cause the catalyst to deactivate. At the same time, the influence of pressure on the reaction equilibrium and the correlation between the biogas consumption rate and the reaction process are analyzed. According to these analysis results, the operating efficiency corresponding to the repair reactor is comprehensively evaluated to judge whether the reaction is sufficient and whether the energy utilization is efficient, etc. Finally, the operating efficiency corresponding to the repair reactor is obtained, that is, the operating efficiency = temperature × (biogas consumption efficiency / pressure).

[0113] Preferably, based on the removal rate of organic pollutants in the soil sample and the corresponding operating efficiency of the repair reactor, the soil sample after organic pollution oxidation decomposition is optimized and adjusted for organic pollution removal, so as to judge the soil sample with incomplete organic pollution removal according to the comparison between the preset removal threshold and the removal rate of organic pollutants in the soil sample, and optimize and adjust the soil sample with incomplete organic pollution removal based on the corresponding operating efficiency of the repair reactor, so as to strengthen the desorption and catalytic reaction conditions corresponding to the repair reactor, and generate a soil sample for off-site repair that contains heavy metals and has completed organic pollution repair.

[0114] In the embodiment of the present invention, by comparing the calculated removal rate of organic pollutants in the soil sample with the preset removal threshold (set to 90%), if the removal rate is lower than 90%, it is determined that the organic pollution removal of the soil sample is incomplete. According to the analysis result of the corresponding operating efficiency of the repair reactor, if it is found that the low temperature affects the reaction rate, the temperature is increased to 50-60 degrees Celsius through a heating device to accelerate the desorption and decomposition reaction of organic pollutants. If the pressure is insufficient, a pressurization device is used to appropriately increase the pressure to promote the reaction in the direction conducive to the decomposition of organic pollutants. If the biogas consumption rate is unreasonable, the feeding speed is adjusted to make the reaction system reach a better operating state. By strengthening the desorption and catalytic reaction conditions corresponding to the repair reactor, the soil sample with incomplete organic pollution removal is processed again until a satisfactory removal effect is achieved, and finally a soil sample for off-site repair that contains heavy metals and has completed organic pollution repair is generated.

[0115] Furthermore, the specific formula for calculating the organic pollution removal rate is:

[0116]

[0117] In the formula, R is the removal rate of organic pollutants in the soil sample, T is the total duration of the removal time, t is the time variable parameter, C(t) is the residual amount of organic pollutants at time t, m c is the content corresponding to the decomposition product carbon dioxide in the gas, m h is the content corresponding to the decomposition product water in the gas, n is the total number of incompletely decomposed intermediate products in the gas, P i is the content corresponding to the i-th incompletely decomposed intermediate product, β i is the relative molecular mass corresponding to the i-th incompletely decomposed intermediate product, C 0 is the concentration of organic pollutants in the initial soil sample.

[0118] The present invention obtains a calculation formula for the removal rate of organic pollution through the use of a specific mathematical model and verification, which is used to quantitatively calculate the removal of soil samples after the oxidative decomposition of organic pollution. This formula fully considers the removal rate R of organic pollutants in the soil sample, the total duration T of the removal time, the time variable parameter t, the residual amount C(t) of organic pollutants at time t, and the content m of the decomposition product carbon dioxide in the gas c , and the content m of the decomposition product water in the gas h , the total number n of incompletely decomposed intermediate products in the gas, and the content P of the i-th incompletely decomposed intermediate product i , the relative molecular mass β of the i-th incompletely decomposed intermediate product i , the concentration C of organic pollutants in the initial soil sample 0 , and a functional relationship is formed based on the mutual relationship between the removal rate R of organic pollutants in the soil sample and the above parameters This formula can realize the quantitative calculation process of the removal of soil samples after the oxidative decomposition of organic pollution. At the same time, this calculation formula for the removal rate of organic pollution can comprehensively consider the removal of organic pollutants in the soil sample during the remediation process. By comparing the residual amount of organic pollutants at different time points with the initial pollutant concentration, the removal rate can be calculated, reflecting the level of the remediation effect. This formula not only considers the removal of organic pollutants but also involves the content of decomposition products (such as carbon dioxide, water, etc.) in the gas, further improving the comprehensiveness of the calculation of the pollution removal rate. Incompletely decomposed intermediate products are also taken into account, which helps to more accurately reflect the removal effect during the soil remediation process and avoid missing some key pollutant components. By calculating the content of decomposition products and incompletely decomposed intermediate products in the gas, the formula can help analyze how organic pollutants are oxidized and decomposed in an aerobic environment. This process can detect the existing intermediate products, which is very useful for judging whether it is necessary to further optimize the reaction conditions. By combining the removal rate of organic pollution with data such as the temperature, pressure, and biogas consumption rate of the reactor, the calculation formula provides a scientific basis for the operating efficiency of the remediation reactor. Based on this information, the reaction conditions during the remediation process can be effectively adjusted and optimized to achieve a higher pollution removal effect. The application of this formula enables the remediation process to be adjusted in real time according to the removal rate and reactor efficiency. By comparing the preset removal threshold with the actual removal rate, problems of incomplete removal of organic pollution can be detected and solved in a timely manner, thereby optimizing the operating conditions of the remediation reactor to ensure the maximization of the remediation effect

[0119] Further, step S3 includes the following steps:

[0120] Step S31: Perform solidification-stabilization coupling remediation on the off-site remediated soil sample containing heavy metals after organic pollution remediation, add a solidifying agent and a stabilizing agent to the corresponding soil sample, and fully mix the solidifying agent, the stabilizing agent and the soil sample through a stirring and mixing device. Under certain temperature and humidity conditions, the solidifying agent reacts chemically with the corresponding heavy metals in the soil sample to form stable compounds, and at the same time, the stabilizing agent forms chelates with the corresponding heavy metal ions, and the corresponding compounds and chelates are removed to generate a heavy metal-containing soil sample after solidification-stabilization remediation;

[0121] In an embodiment of the present invention, a certain amount of off-site remediated soil sample containing heavy metals after organic pollution remediation is taken and placed in a special stirring container. A solidifying agent (such as cement) is added according to 10% of the weight of the soil sample, and a stabilizing agent (such as sodium diethyldithiocarbamate) is added according to 5% of the weight of the soil sample. The stirring and mixing device is started, the stirring speed is set to 200 revolutions per minute, and stirring is continued for 30 minutes to fully mix the solidifying agent, the stabilizing agent and the soil sample. The mixed soil sample is transferred to a constant temperature and humidity curing box, the temperature is set to 25 degrees Celsius, and the humidity is set to 60%. It is maintained for 7 days. During this process, the solidifying agent reacts chemically with the corresponding heavy metals in the soil sample. For example, calcium ions in the cement react with lead ions in the soil to form a stable calcium leadate compound; at the same time, the stabilizing agent forms chelates with the corresponding heavy metal ions. For example, sodium diethyldithiocarbamate forms a stable copper chelate with copper ions. After 7 days, the formed compounds and chelates are removed from the soil sample through a filtering device, and finally a heavy metal-containing soil sample after solidification-stabilization remediation is obtained.

[0122] Step S32: Perform chemical environmental impact assessment analysis on the heavy metal-containing soil sample after solidification-stabilization remediation, use chemical analysis to determine the residual amounts of the corresponding organic pollutants and heavy metals in the soil sample, and judge whether the corresponding soil remediation target is reached to obtain the environmental impact assessment result of the remediated soil sample;

[0123] In the embodiment of the present invention, multiple sub-samples are randomly selected from the heavy metal-containing soil samples after solidification stabilization repair, with each sub-sample weighing 100 grams. Using chemical analysis instruments, such as atomic absorption spectrometers, gas chromatographs, etc., the residual amounts of organic pollutants and heavy metals in each sub-sample are analyzed. For heavy metals, the contents of heavy metal elements such as lead, mercury, cadmium, and chromium in the soil samples are measured by an atomic absorption spectrometer; for organic pollutants, a gas chromatograph is used to analyze the residual amounts of organic pollutants such as polycyclic aromatic hydrocarbons and organochlorine pesticides in the soil samples. According to the preset soil remediation goals, such as lead content being less than 50 mg / kg, mercury content being less than 0.05 mg / kg, total polycyclic aromatic hydrocarbon content being less than 10 mg / kg, etc., it is judged whether each sub-sample meets the soil remediation goals. The analysis results of all sub-samples are summarized to obtain the environmental impact assessment results of the repaired soil samples, and the average residual amounts of organic pollutants and heavy metals in the entire soil sample and whether the remediation goals are met are determined.

[0124] Step S33: Compare and judge the environmental impact assessment results of the repaired soil samples. If the environmental impact assessment results of the repaired soil samples have met the corresponding soil remediation goals, then the corresponding heavy metal-containing soil samples are determined as the soil samples that have completed the organic pollution and heavy metal remediation; if the environmental impact assessment results of the repaired soil samples have not met the corresponding soil remediation goals, then the corresponding heavy metal-containing soil samples are re-treated by cyclic organic pollution desorption and solidification stabilization repair until the corresponding soil remediation goals are met, and the soil samples that have completed the organic pollution and heavy metal remediation are generated.

[0125] In the embodiment of the present invention, by comparing the previously obtained environmental impact assessment results of the repaired soil samples with the corresponding soil remediation goals, if the environmental impact assessment results of the repaired soil samples show that the residual amounts of organic pollutants and heavy metals in the soil samples have both met the preset soil remediation goals, for example, the lead content is 40 mg / kg and the total polycyclic aromatic hydrocarbon content is 8 mg / kg, both lower than the target values, then the corresponding heavy metal-containing soil samples are determined as the soil samples that have completed the organic pollution and heavy metal remediation. If the environmental impact assessment results of the repaired soil samples show that there are residual amounts of organic pollutants or heavy metals in the soil samples that have not met the soil remediation goals, such as the mercury content is 0.1 mg / kg, higher than the target value of 0.05 mg / kg, then the corresponding heavy metal-containing soil samples are re-treated by organic pollution desorption. The solvent extraction method is used, with dichloromethane as the extraction agent, and extraction is carried out at a ratio of soil sample to extraction agent of 1:2 for 2 hours, and then solidification stabilization repair treatment is carried out. Repeat the operation of step S31 until the residual amounts of organic pollutants and heavy metals in the soil samples meet the corresponding soil remediation goals, and finally the soil samples that have completed the organic pollution and heavy metal remediation are generated.

[0126] Further, step S4 includes the following steps:

[0127] Step S41: Through co-flyash solidification treatment of the corresponding fly ash in the landfill and the soil samples after the organic pollution and heavy metal remediation are completed, an appropriate amount of solidifying agent and additive are added to the fly ash and mixed with the soil samples after the organic pollution and heavy metal remediation in a certain proportion, and the corresponding solidified fly ash blocks are prepared by a pressure forming device to obtain the soil solidified fly ash blocks after remediation;

[0128] In the embodiment of the present invention, a certain amount of fly ash is collected from the landfill, and at the same time, the soil samples after the organic pollution and heavy metal remediation are obtained. In a special mixing site, the fly ash and the repaired soil samples are mixed according to a pre-determined proportion. For example, 50 kg of repaired soil samples are paired with every 100 kg of fly ash. Then, an appropriate amount of solidifying agent, such as cement, is added to the mixture of fly ash and soil samples, added at 10% of the fly ash weight, and an additive, such as activated silica powder, is added at 5% of the fly ash weight. The mixture is fully stirred by using a stirring device to make the solidifying agent, additive, fly ash and soil samples evenly mixed. After stirring evenly, the mixture is put into a pressure forming device, the set pressure is 5 MPa, and the pressure holding time is 30 minutes. The mixture is prepared into regular-shaped solidified fly ash blocks by the pressure forming device, and finally the soil solidified fly ash blocks after remediation are obtained.

[0129] Step S42: Transport the soil solidified fly ash blocks after remediation to the corresponding fly ash landfill zone in the landfill, and use the soil solidified fly ash blocks as the pore soil corresponding to the fly ash layer and the intermediate corresponding covering soil for fly ash landfill reuse, so as to use the corresponding pores to fill and compact the soil solidified fly ash blocks to form the corresponding pore soil, and through the designed unit thickness of the fly ash landfill to meet the mid-term covering of the landfill geomembrane and level and compact to form the corresponding covering soil, generating the remediated off-site fly ash landfill reused soil.

[0130] In an embodiment of the present invention, the previously obtained repaired soil solidified fly ash blocks are transported to the fly ash landfill special zone in the landfill by using a transport vehicle. In the fly ash landfill special zone, the position of the fly ash layer is first determined. For the pore soil corresponding to the fly ash layer, the soil solidified fly ash blocks are placed into the pores. A compaction device, such as a vibratory roller, is used to compact the soil solidified fly ash blocks placed in the pores at a traveling speed of 5 kilometers per hour and a pressure of 2 tons, so that the soil solidified fly ash blocks tightly fill the pores to form pore soil. For the intermediate cover soil part, according to the fly ash landfill design, the unit thickness is determined. For example, the unit thickness is set to 0.5 meters. The soil solidified fly ash blocks are laid on the fly ash landfill layer to form a 0.5-meter-thick layered structure. Then, a leveling device, such as a grader, is used to level the laid soil solidified fly ash blocks, and then a compaction device is used to compact them at a traveling speed of 4 kilometers per hour and a pressure of 3 tons to meet the requirements of the mid-term covering of the landfill geomembrane, forming cover soil. Through such operations, finally, the repaired off-site fly ash landfill recycled soil is generated.

[0131] Further, the present invention also provides a landfill coupled contaminated soil off-site remediation system for implementing the landfill coupled contaminated soil off-site remediation method as described above. The landfill coupled contaminated soil off-site remediation system includes:

[0132] A contaminated soil sample classification module for obtaining off-site remediated contaminated soil samples corresponding to different depth levels by performing depth stratified sampling on the off-site remediated contaminated soil heap body corresponding in the disposal center of the landfill; classifying the soil sample characteristics of the off-site remediated contaminated soil samples corresponding to different depth levels to obtain off-site remediated soil samples corresponding to different pollution types, including off-site remediated soil samples containing organic pollutants, heavy metals, and those containing both organic pollution and heavy metals;

[0133] An organic pollution desorption and remediation module for obtaining the corresponding purified biogas in the landfill as a heat source and performing organic pollution desorption and conversion on the off-site remediated soil samples containing organic pollutants among the off-site remediated soil samples corresponding to different pollution types based on the heat source, so as to generate off-site remediated soil samples containing heavy metals and having completed organic pollution remediation;

[0134] A heavy metal and environmental impact assessment cyclic remediation module for performing solidification and stabilization coupled remediation on the off-site remediated soil samples containing heavy metals and having completed organic pollution remediation to generate solidification and stabilization remediated heavy metal-containing soil samples; performing chemical environmental impact assessment analysis on the solidification and stabilization remediated heavy metal-containing soil samples to obtain the environmental impact assessment results of the remediated soil samples; performing cyclic remediation treatment on the solidification and stabilization remediated heavy metal-containing soil samples based on the environmental impact assessment results of the remediated soil samples, so as to generate soil samples having completed organic pollution and heavy metal remediation;

[0135] The fly ash landfill reuse module is used to perform fly ash landfill reuse on soil samples that have completed organic pollution and heavy metal remediation based on a landfill, so as to generate remediated off-site fly ash landfill reused soil.

[0136] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the application document are intended to be embraced within the present invention.

[0137] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features invented herein.

Claims

1. A method for remediating landfill-coupled contaminated soil off-site, characterized in that: The following steps are involved: Step S1: by performing depth stratified sampling on the corresponding ex situ remediation contaminated soil pile in the disposal center of the landfill, to obtain ex situ remediation contaminated soil samples corresponding to different depth levels; classifying the soil sample characteristics of the ex situ remediation contaminated soil samples corresponding to different depth levels, to obtain ex situ remediation soil samples corresponding to different pollution types, including ex situ remediation soil samples containing organic pollutants, containing heavy metals, and containing organic pollution and heavy metals; Step S2: obtaining the corresponding purified biogas from the landfill and using it as a heat source, and based on the heat source, desorbing and transforming the organic pollution in the ex situ remediation soil samples containing organic pollutants in the ex situ remediation soil samples corresponding to different pollution types, to generate ex situ remediation soil samples containing heavy metals and after the organic pollution remediation has been completed; Step S3: performing solidification, stabilization and coupled remediation on the off-site remediation soil sample containing heavy metals and having completed organic pollution remediation to generate a solidified, stabilized and remediated heavy metal-containing soil sample; Conduct chemical environmental impact assessment analysis on the soil samples containing heavy metals after solidification, stabilization and remediation to obtain the environmental impact assessment results of the remediated soil samples; conduct recycling remediation treatment on the soil samples containing heavy metals after solidification, stabilization and remediation based on the environmental impact assessment results of the remediated soil samples to generate soil samples that have completed organic pollution and heavy metal remediation; Step S4: Based on the landfill, fly ash is landfilled and reused on the soil samples that have completed organic pollution and heavy metal remediation, so as to generate remediated off-site fly ash landfill reuse soil.

2. The method for remediation of landfill-coupled contaminated soil off-site according to claim 1, characterized in that: Step S1 includes the following steps: Step S11: by performing depth stratified sampling on the corresponding ex situ remediation contaminated soil pile in the disposal center of the landfill, a soil sample is collected every 0.5 meters and the corresponding sampling location and depth are marked to obtain ex situ remediation contaminated soil samples corresponding to different depth levels; Step S12: testing the heavy metal content of the ex situ remediation contaminated soil samples corresponding to different depth levels to obtain the soil heavy metal content corresponding to different types of soil at different depth levels; Step S13: performing an organic pollutant type analysis on the off-site remediation contaminated soil samples corresponding to different depth levels, so as to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons therein, and obtain the soil organic pollutant types corresponding to each depth level; Step S14: Based on the soil heavy metal content corresponding to different types of each depth level and the types of soil organic pollutants corresponding to each depth level, the corresponding ex situ remediation contaminated soil samples are classified into soil sample characteristics to obtain ex situ remediation soil samples corresponding to different pollution types, including ex situ remediation soil samples containing organic pollutants, heavy metals, and organic pollution and heavy metals.

3. The method for remediation of landfill-coupled contaminated soil off-site according to claim 2, characterized in that: The different types of soil heavy metal contents corresponding to the step S12 specifically include the heavy metal contents of lead, mercury and pickaxe corresponding to the types of heavy metals.

4. The method for remediation of landfill-coupled contaminated soil off-site according to claim 1, characterized in that: Step S2 includes the following steps: Step S21: a biogas collection well is set up in the landfill, and the biogas collected in the biogas collection well is transported to the biogas purification device through a pipeline; Step S22: purifying the collected biogas using a biogas purification device to purify and remove the corresponding hydrogen sulfide and water impurities in the biogas, and improve the corresponding purity of the biogas, so as to obtain the corresponding purified biogas and simultaneously transport it to the contaminated soil remediation area through a pipeline as the corresponding biogas heat source in the remediation process; Step S23: Based on the biogas heat source, the ex situ remediation soil samples containing organic pollutants in the ex situ remediation soil samples corresponding to different pollution types are subjected to organic pollution desorption and transformation, so as to generate ex situ remediation soil samples containing heavy metals and after the organic pollution remediation is completed.

5. The method for remediation of landfill-coupled contaminated soil off-site according to claim 4, characterized in that: Step S23 includes the following steps: Step S231: studying the energy release of the biogas heat source during the combustion process to measure the combustion calorific value of the biogas heat source using a combustion calorific value measuring instrument, and drawing a combustion temperature curve corresponding to the biogas heat source according to the combustion calorific value; Step S232: performing combustion efficiency statistics on the biogas heat source based on the combustion temperature curve corresponding to the biogas heat source to obtain the combustion efficiency corresponding to the biogas heat source; Step S233: placing the off-site remediation soil samples containing organic pollutants in the off-site remediation soil samples corresponding to different pollution types in the corresponding remediation reactor in the landfill, and controlling the corresponding biogas intake and combustion intensity in the remediation reactor based on the combustion efficiency corresponding to the biogas heat source, so that the soil temperature in the remediation reactor is in a temperature range suitable for desorption of organic pollutants, specifically 100-300°C; Step S234: Based on the controlled temperature range and using a remediation reactor, the ex situ remediation soil samples containing organic pollutants corresponding to different pollution types are subjected to organic pollution desorption and transformation to generate ex situ remediation soil samples containing heavy metals and after organic pollution remediation has been completed.

6. The method for remediation of landfill-coupled contaminated soil off-site according to claim 5, characterized in that: Step S234 includes the following steps: Based on a controlled temperature range and using a remediation reactor, the ex situ remediation soil samples containing organic pollutants corresponding to different pollution types are subjected to organic pollutant desorption, so that ultrasonic waves of corresponding frequencies are applied in the remediation reactor based on the temperature range, and the cavitation effect and mechanical vibration corresponding to the ultrasonic waves are used to destroy the adsorption force between soil particles and organic pollutants, so as to obtain soil samples after the organic pollutants are desorbed; The soil sample after the organic pollutants are desorbed is transferred to the corresponding aerobic environment in the remediation reactor, and the desorbed organic pollutants in the soil sample are oxidized and decomposed by adding the corresponding metal oxide catalyst, so that the corresponding organic pollutants are quickly and thoroughly decomposed and converted into harmless carbon dioxide and water substances in the aerobic environment, and the soil sample after the organic pollutants are oxidized and decomposed is obtained; By testing the soil samples after the oxidative decomposition of the organic pollution, the corresponding residual amount of organic pollutants and the contents of decomposition products such as carbon dioxide, water and incomplete decomposition intermediate products in the gas are obtained, and at the same time, the concentration of organic pollutants in the initial soil samples is obtained. Based on the concentration of organic pollutants in the initial soil samples, the residual amount of organic pollutants and the contents of decomposition products such as carbon dioxide, water and incomplete decomposition intermediate products in the gas, the organic pollution removal rate calculation formula is used to perform a quantitative calculation of the removal of organic pollutants in the soil samples after the oxidative decomposition of the organic pollution, so as to obtain the organic pollutant removal rate of the soil samples; Obtaining the temperature, pressure and biogas consumption rate corresponding to the repair reactor, and analyzing the operation efficiency corresponding to the repair reactor according to the temperature, pressure and biogas consumption rate; Based on the organic pollutant removal rate of soil samples and the corresponding operating efficiency of the remediation reactor, the soil samples after oxidative decomposition of organic pollution are optimized and adjusted for organic pollution removal, so as to judge the soil samples with incomplete organic pollution removal according to the preset removal threshold and the organic pollutant removal rate of soil samples, and based on the corresponding operating efficiency of the remediation reactor, the soil samples with incomplete organic pollution removal are optimized and adjusted to strengthen the desorption and catalytic reaction conditions corresponding to the remediation reactor, so as to generate ex situ remediation soil samples containing heavy metals and after the organic pollution remediation is completed.

7. The method for remediation of landfill-coupled contaminated soil off-site according to claim 6, characterized in that: The organic pollution removal rate calculation formula is specifically as follows: In the formula, R is the removal rate of organic pollutants in soil samples, T is the total removal time, t is the time variable parameter, C(t) is the residual amount of organic pollutants at time t, m c is the content of carbon dioxide in the gas, m h is the content of water in the gas, n is the total number of incompletely decomposed intermediates in the gas, P i is the content of the i-th incompletely decomposed intermediate product, β i is the relative molecular mass corresponding to the i-th incompletely decomposed intermediate product, and C0 is the concentration of organic pollutants in the initial soil sample.

8. The method for remediation of landfill-coupled contaminated soil off-site according to claim 1, characterized in that: Step S3 includes the following steps: Step S31: Performing solidification, stabilization and coupled remediation on the off-site remediation soil sample containing heavy metals and having completed organic pollution remediation, adding a solidifying agent and a stabilizer to the corresponding soil sample, and fully mixing the solidifying agent, the stabilizer and the soil sample through a stirring and mixing device, and chemically reacting the solidifying agent with the corresponding heavy metal in the soil sample under certain temperature and humidity conditions to form a stable compound, and at the same time, the stabilizer forms a chelate with the corresponding heavy metal ion, and the corresponding compound and chelate are removed to generate a solidified, stabilized and remediated heavy metal-containing soil sample; Step S32: Perform chemical environmental impact assessment analysis on the soil sample containing heavy metals after solidification, stabilization and restoration, so as to use chemical analysis to determine the corresponding residual amounts of organic pollutants and heavy metals in the soil sample, and determine whether the corresponding soil restoration target has been achieved, so as to obtain the environmental impact assessment result of the restored soil sample; Step S33: Compare and judge the environmental impact assessment results of the remediated soil samples. If the environmental impact assessment results of the remediated soil samples have reached the corresponding soil remediation target, the corresponding heavy metal-containing soil samples are determined as soil samples that have completed organic pollution and heavy metal remediation; if the environmental impact assessment results of the remediated soil samples have not reached the corresponding soil remediation target, the corresponding heavy metal-containing soil samples are re-processed with cyclic organic pollution desorption and solidification stabilization remediation until the corresponding soil remediation target is reached, thereby generating soil samples that have completed organic pollution and heavy metal remediation.

9. The method for remediation of landfill-coupled contaminated soil off-site according to claim 1, characterized in that: Step S4 includes the following steps: Step S41: performing fly ash solidification treatment on the corresponding fly ash in the landfill and the soil sample after organic pollution and heavy metal remediation, adding a proper amount of solidifying agent and additives to the fly ash and mixing with the soil sample after organic pollution and heavy metal remediation in a certain proportion, and preparing the corresponding solidified fly ash blocks through pressure molding equipment to obtain the repaired soil solidified fly ash blocks; Step S42: transport the repaired soil-solidified fly ash blocks to the corresponding fly ash landfill area in the landfill, and reuse the soil-solidified fly ash blocks as the porous soil corresponding to the fly ash layer and the corresponding covering soil in the middle for fly ash landfill, so as to fill and compact the soil-solidified fly ash blocks with the corresponding pores to form the corresponding porous soil, and by satisfying the mid-term coverage of the geomembrane in the fly ash landfill design and leveling and compacting to form the corresponding covering soil, the repaired off-site fly ash landfill reuse soil is generated.

10. A landfill-coupled contaminated soil off-site remediation system, characterized in that: Used to perform the landfill-coupled contaminated soil off-site remediation method as claimed in claim 1, the landfill-coupled contaminated soil off-site remediation system comprises: The contaminated soil sample classification module is used to obtain the contaminated soil samples corresponding to different depth levels by performing depth stratified sampling on the corresponding ex situ remediation contaminated soil pile in the disposal center of the landfill; classifying the soil sample characteristics of the ex situ remediation contaminated soil samples corresponding to different depth levels, so as to obtain the ex situ remediation soil samples corresponding to different pollution types, including the ex situ remediation soil samples containing organic pollutants, containing heavy metals, and containing organic pollution and heavy metals; An organic pollution desorption and remediation module is used to obtain the corresponding purified biogas from the landfill and use it as a heat source, and based on the heat source, desorb and transform the organic pollution of the off-site remediation soil samples containing organic pollutants in the off-site remediation soil samples corresponding to different pollution types, thereby generating off-site remediation soil samples containing heavy metals and after the organic pollution remediation has been completed; The heavy metal and environmental assessment cycle remediation module is used to perform solidification and stabilization coupling remediation on off-site remediation soil samples containing heavy metals and having completed organic pollution remediation, so as to generate soil samples containing heavy metals after solidification and stabilization remediation; perform chemical environmental assessment analysis on the soil samples containing heavy metals after solidification and stabilization remediation, so as to obtain the environmental assessment results of the remediated soil samples; and perform cycle remediation treatment on the soil samples containing heavy metals after solidification and stabilization remediation based on the environmental assessment results of the remediated soil samples, so as to generate soil samples that have completed organic pollution and heavy metal remediation; The fly ash landfill reuse module is used to landfill and reuse fly ash from soil samples that have completed organic pollution and heavy metal remediation in landfills, thereby generating remediated off-site fly ash landfill reuse soil.

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