A system and method for ex-situ remediation of landfill coupled contaminated soil

Abstract

The present application relates to the technical field of environmental pollution remediation, and particularly relates to a garbage landfill coupled with contaminated soil remote remediation system and method. The method comprises the following steps: deep layer sampling and soil sample characteristic classification are performed on the remote remediation contaminated soil heap to obtain remote remediation soil samples corresponding to different pollution types; purified biogas is used as a heat source to perform organic pollution desorption and conversion and solidification and stabilization coupled remediation, and a solidification and stabilization remediated heavy metal-containing soil sample is generated; chemical environmental impact assessment analysis and cyclic remediation treatment are performed on the solidification and stabilization remediated heavy metal-containing soil sample to generate a soil sample after organic pollution and heavy metal remediation; fly ash landfill reuse is performed on the soil sample after organic pollution and heavy metal remediation to generate a remote fly ash landfill reuse soil after remediation. The present application can combine garbage landfill resources and remote contaminated soil remediation to realize corresponding soil cyclic reuse.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution remediation technology, and in particular to a system and method for off-site remediation of contaminated soil coupled with landfill. Background Technology

[0002] Regarding the resource utilization of landfills, biogas produced by landfills is often simply burned or directly emitted, wasting energy and polluting the atmosphere. Meanwhile, the treatment of solid waste such as fly ash from landfills also faces challenges. Fly ash contains large amounts of heavy metals and other harmful substances, posing a risk of heavy metal leakage when landfilled, thus threatening soil and groundwater environments. However, traditional methods for remediating contaminated soil at other sites, such as the topsoil method, require large quantities of high-quality soil resources and incur high transportation costs. While chemical remediation methods can reduce soil pollutant concentrations to some extent, they introduce new chemicals, causing secondary pollution, making it difficult to achieve the recycling of both soil remediation and landfill resources. Summary of the Invention

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

[0004] To achieve the above objectives, a method for off-site remediation of contaminated soil coupled with landfill remediation includes the following steps:

[0005] Step S1: Conduct deep stratified sampling of the contaminated soil pile corresponding to the off-site remediation in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; classify 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, containing heavy metals, and containing both organic pollutants and heavy metals.

[0006] Step S2: Obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

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

[0008] Step S4: Based on the soil samples from the landfill that have undergone organic pollution and heavy metal remediation, fly ash is reused in the landfill to generate remediated off-site fly ash landfill reuse soil.

[0009] Furthermore, step S1 includes the following steps:

[0010] Step S11: By performing deep stratified sampling on the corresponding off-site remediation contaminated soil pile within the landfill disposal center, a soil sample is taken every 0.5 meters and the corresponding sampling location and depth are marked to obtain off-site remediation contaminated soil samples corresponding to different depth layers.

[0011] Step S12: Detect the heavy metal content of soil samples from off-site remediation at different depth levels to obtain the heavy metal content of different types of soil at each depth level.

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

[0013] Step S14: Based on the content of heavy metals in soil at different depth levels and the types of organic pollutants in soil at different depth levels, classify the soil samples for off-site remediation of contaminated soil samples to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

[0014] Furthermore, the soil heavy metal content corresponding to different types mentioned in step S12 specifically includes the heavy metal content of lead, mercury, and gypsum.

[0015] Furthermore, step S2 includes the following steps:

[0016] Step S21: By setting up biogas collection wells in the landfill and using 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, remove hydrogen sulfide and moisture impurities from the biogas, and improve the purity of the biogas. The purified biogas is then transported through pipelines to the contaminated soil remediation area as a biogas heat source during the remediation process.

[0018] Step S23: Based on the biogas heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

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

[0020] Step S231: By studying the energy release corresponding to the biogas heat source during combustion, the combustion heat value corresponding to the biogas heat source is measured by a combustion heat measuring instrument, and the combustion temperature curve corresponding to the biogas heat source is plotted based on the combustion heat value.

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

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

[0023] Step S234: Based on the controlled temperature range, the organic pollutants in the off-site remediation soil samples containing organic pollutants corresponding to different pollution types are desorbed and transformed to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

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

[0025] Based on a well-controlled temperature range, organic pollutants were desorbed from soil samples containing organic pollutants in off-site remediation samples corresponding to different pollution types using a remediation reactor. Ultrasonic waves of corresponding frequencies were applied in the remediation reactor based on the temperature range, and the cavitation effect and mechanical vibration of the ultrasonic waves were used to destroy the adsorption force between soil particles and organic pollutants, so as to obtain soil samples after organic pollutant desorption.

[0026] Soil samples after desorption of organic pollutants are transferred to the corresponding aerobic environment in the remediation reactor, and the desorbed organic pollutants in the soil samples are oxidized and decomposed by adding corresponding metal oxide catalysts. The corresponding organic pollutants are rapidly and thoroughly decomposed into harmless carbon dioxide and water in the aerobic environment, and the soil samples after oxidative decomposition of organic pollutants are obtained.

[0027] By analyzing soil samples after the oxidative decomposition of organic pollutants, the residual amount of organic pollutants and the contents of decomposition products carbon dioxide, water and incomplete decomposition intermediates in the gas were obtained. At the same time, the concentration of organic pollutants in the initial soil sample was obtained. 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 incomplete decomposition intermediates in the gas, the organic pollutant removal rate was calculated using the organic pollutant removal rate calculation formula to obtain the organic pollutant removal rate of the soil sample.

[0028] Obtain the temperature, pressure, and biogas consumption rate corresponding to the repair reactor, and analyze the operating efficiency of the repair reactor based on the temperature, pressure, and biogas consumption rate.

[0029] Based on the organic pollutant removal rate of soil samples and the corresponding operating efficiency of the remediation reactor, the organic pollutant removal of soil samples after organic pollution oxidation and decomposition is optimized and adjusted. Soil samples with incomplete organic pollution removal are identified by comparing the organic pollutant removal rate with the preset removal threshold. Based on the operating efficiency of the remediation reactor, the soil samples with incomplete organic pollution removal are optimized and adjusted to enhance the desorption and catalytic reaction conditions of the remediation reactor, thereby generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0030] Furthermore, the formula for calculating the organic pollution removal rate is as follows:

[0031]

[0032] In the formula, R is the removal rate of organic pollutants in the soil sample, T is the total removal time, t is a time variable parameter, C(t) is the residual amount of organic pollutants at time t, and m c m represents the content of carbon dioxide, a decomposition product, in the gas. h P represents the content of water, a decomposition product in the gas, and n represents the total amount of incompletely decomposed intermediate products in the gas. i β represents the content of the i-th incompletely decomposed intermediate product. i Ci represents the relative molecular mass of the i-th incompletely decomposed intermediate product, and C0 represents the concentration of organic pollutants in the initial soil sample.

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

[0034] Step S31: Solidification and stabilization coupled remediation is carried out on off-site remediation soil samples containing heavy metals and after organic pollution remediation. Solidification agent and stabilizer are added to the corresponding soil samples, and the solidification agent and stabilizer are fully mixed with the soil samples by a mixing device. Under certain temperature and humidity conditions, the solidification agent reacts chemically with the corresponding heavy metals in the soil samples to form stable compounds. At the same time, the stabilizer forms chelates with the corresponding heavy metal ions. The corresponding compounds and chelates are removed to generate solidified and stabilized soil samples containing heavy metals.

[0035] Step S32: Conduct chemical environmental impact assessment analysis on the soil samples containing heavy metals after solidification and stabilization remediation, so as to use chemical analysis to determine the residual amounts of corresponding organic pollutants and heavy metals in the soil samples, and to determine whether the corresponding soil remediation targets have been achieved, so as to obtain the environmental impact assessment results of the remediated soil samples.

[0036] 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, then the corresponding soil samples containing heavy metals are identified as soil samples that have completed the remediation of organic pollution and heavy metals. If the environmental impact assessment results of the remediated soil samples have not reached the corresponding soil remediation target, then the corresponding soil samples containing heavy metals will undergo cyclic organic pollution desorption and solidification stabilization remediation treatment again until the corresponding soil remediation target is reached, and soil samples that have completed the remediation of organic pollution and heavy metals will be generated.

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

[0038] Step S41: By co-processing the corresponding fly ash in the landfill with soil samples that have completed organic pollution and heavy metal remediation, an appropriate amount of solidifying agent and additives are added to the fly ash and mixed with the soil samples that have completed organic pollution and heavy metal remediation in a certain proportion, and the corresponding solidified fly ash blocks are prepared by pressure molding equipment to obtain the remediated soil solidified fly ash blocks.

[0039] Step S42: The remediated solidified fly ash blocks are transported to the corresponding fly ash landfill area within the landfill. The solidified fly ash blocks are used as the porous soil corresponding to the fly ash layer and the corresponding cover soil in the middle for fly ash landfill reuse. The corresponding pores are used to fill and compact the solidified fly ash blocks to form the corresponding porous soil. The corresponding unit thickness of the fly ash landfill design is sufficient to meet the mid-term coverage of the geomembrane of the pile body and to form the corresponding cover soil, thus generating the remediated off-site fly ash landfill reuse soil.

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

[0041] The contaminated soil sample classification module is used to perform deep stratified sampling of contaminated soil piles corresponding to off-site remediation within the disposal center of the landfill to obtain contaminated soil samples for off-site remediation at different depth levels; and to classify the soil sample characteristics of the contaminated soil samples for off-site remediation at different depth levels to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

[0042] The organic pollution desorption and remediation module is used to obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, it desorbs and transforms organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types, thereby generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0043] The heavy metal and environmental impact assessment (EIA) cyclic remediation module is used to perform solidification and stabilization coupled remediation on off-site remediation soil samples containing heavy metals that have already undergone organic pollution remediation, to generate solidified and stabilized heavy metal-containing soil samples; chemical EIA analysis is performed on the solidified and stabilized heavy metal-containing soil samples to obtain the EIA results of the remediated soil samples; based on the EIA results of the remediated soil samples, the solidified and stabilized heavy metal-containing soil samples are subjected to cyclic remediation treatment, thereby generating soil samples that have completed organic pollution and heavy metal remediation.

[0044] The fly ash landfill reuse module is used to reuse fly ash from soil samples that have undergone organic pollution and heavy metal remediation at landfill sites, thereby generating remediated fly ash landfill reuse soil at other locations.

[0045] The beneficial effects of this invention are:

[0046] 1. The landfill-coupled off-site remediation method for contaminated soil proposed in this invention has the following advantages over existing technologies: by conducting deep stratified sampling within the landfill treatment center to obtain soil samples at different depths, the hierarchical characteristics of the contaminated soil can be understood. This sampling method can accurately capture the soil pollution at different depths, making subsequent remediation measures 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 mechanisms of different pollutants, providing an important basis for the design of subsequent remediation schemes. Secondly, the purified biogas from landfills can be used as a heat source for the desorption and transformation remediation of soil containing organic pollutants. Biogas, as a natural gas, is rich in combustible gases such as methane and has a good calorific value, providing an efficient heat source for the desorption of organic pollutants. Through heating, organic pollutants can be desorbed from soil particles and, under certain conditions, transformed into harmless substances or decomposed through biodegradation. This process not only effectively removes organic pollutants from the soil but also makes full use of the corresponding biogas resources within the landfill, avoiding the use of chemical reagents and reducing 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, while heavy metal pollution in the soil is relatively isolated, laying the foundation for subsequent heavy metal remediation. Then, by applying solidification and stabilization technology to the remediation of soil containing heavy metals, the aim is to immobilize heavy metal elements in the soil through physicochemical means, reduce their mobility and bioavailability, and prevent secondary pollution of the environment by heavy metal pollutants. Solidification and 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-toxicity and low-solubility state. After the remediation is completed, a chemical environmental impact assessment is conducted to ensure that the remediation effect meets environmental safety standards. Through this series of measures, effective remediation of soil containing heavy metal pollution can be achieved, and the remediated soil can be ensured to meet environmental protection requirements. If the chemical environmental impact assessment results do not meet the standards, further cyclical remediation treatment can be applied to ensure the safety of the remediated soil. This greatly improves the sustainability and environmental friendliness of soil remediation.Finally, the remediated soil is further utilized through fly ash landfill reuse to achieve resource recovery. Fly ash landfill reuse not only effectively reduces the environmental impact of waste but also transforms waste into useful resources. By combining the remediated soil with fly ash, the soil can be further stabilized and solidified. Furthermore, the action of certain mineral components in the fly ash can further promote the immobilization of heavy metals and improve the soil structure. In this process, the addition of fly ash provides additional mineral components, improves the physical and chemical properties of the soil, and further enhances its stability and usability. Through fly ash landfill reuse, the remediated soil resources can be reused to the greatest extent, avoiding secondary pollution from waste and providing a new way out for landfill waste disposal. This ensures that the remediated soil can be effectively recycled between landfill resources and landfill resources, thereby achieving the harmless and resource-based treatment of off-site remediated soil.

[0047] 2. The landfill-coupled contaminated soil off-site remediation system proposed in this invention is composed of a contaminated soil sample classification module, an organic pollutant desorption remediation module, a heavy metal and environmental impact assessment recycling remediation module, and a fly ash landfill reuse module. It can realize the off-site remediation method for any landfill-coupled contaminated soil as described in this invention. It is used to coordinate the operation between the computer programs running on each module to realize the off-site remediation method for landfill-coupled contaminated soil. 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 off-site remediation process for landfill-coupled contaminated soil, thereby simplifying the operation process of the landfill-coupled contaminated soil off-site remediation system. Attached Figure Description

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

[0049] Figure 1 This is a schematic diagram of the steps of the landfill-coupled off-site remediation method for contaminated soil according to the present invention;

[0050] Figure 2 for Figure 1 A detailed flowchart of step S1;

[0051] Figure 3 for Figure 1 A detailed flowchart of step S2. Detailed Implementation

[0052] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

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

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

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

[0057] Step S2: Obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

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

[0059] Step S4: Based on the soil samples from the landfill that have undergone organic pollution and heavy metal remediation, fly ash is reused in the landfill to generate remediated off-site fly ash landfill reuse soil.

[0060] In the embodiments of this invention, please refer to Figure 1 The diagram shown is a flowchart illustrating the steps of the landfill-coupled contaminated soil off-site remediation method of the present invention. In this example, the landfill-coupled contaminated soil off-site remediation method includes the following steps:

[0061] Step S1: Conduct deep stratified sampling of the contaminated soil pile corresponding to the off-site remediation in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; classify 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, containing heavy metals, and containing both organic pollutants and heavy metals.

[0062] In this embodiment of the invention, deep stratified sampling is conducted on contaminated soil piles for off-site remediation at the landfill disposal center. A professional soil sampling drill equipped with a 5 cm diameter drill bit is used to accurately drill into the soil pile. Samples are taken sequentially from the surface to the depth at 0.5 m intervals. After each sample is collected, the sampling location and depth are clearly marked with a label. The samples are then properly placed in sealed containers to prevent contamination and moisture loss. After sampling, these samples are classified according to their characteristics. Atomic absorption spectrometry is 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. Based on the test results, the samples are divided into three categories of off-site remediation soil samples with different pollution types: those containing organic pollutants, those containing heavy metals, and those containing both organic pollutants and heavy metals.

[0063] Step S2: Obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

[0064] In this embodiment of the invention, the 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, ultimately yielding purified biogas. This purified biogas is then introduced into a remediation reactor as a heat source to treat soil samples containing organic pollutants for off-site remediation. In the remediation reactor, the combustion intensity is controlled by adjusting the biogas intake, maintaining the reactor temperature within a suitable range of 100-300°C. At this temperature, the thermal motion of organic pollutant molecules intensifies, weakening the adsorption force between them and soil particles, thus causing desorption. Simultaneously, the catalyst and oxygen within the reactor promote the oxidative decomposition of the desorbed organic pollutants, converting them into carbon dioxide and water, ultimately generating off-site remediation soil samples containing heavy metals and showing signs of organic pollution remediation.

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

[0066] In this embodiment of the invention, a solidification and stabilization coupled remediation process is performed on off-site remediation soil samples containing heavy metals and which have undergone organic pollution remediation. 10% cement is added to the soil sample as a solidifying agent, and 5% sodium diethyldithiocarbamate is added as a stabilizer. The samples are thoroughly mixed using a stirring device, and then placed in a constant temperature and humidity curing chamber at 25°C and 60% humidity for 7 days. During this period, the solidifying agent reacts chemically with the heavy metals to form stable compounds; the stabilizer forms chelates with the heavy metal ions. After 7 days, the residual amounts of organic pollutants and heavy metals are detected using chemical analysis instruments, and a chemical environmental impact assessment is conducted. If the remediation target is not met, the organic pollution desorption and solidification stabilization remediation process is repeated until the target is met, ultimately generating a soil sample that has undergone organic pollution and heavy metal remediation.

[0067] Step S4: Based on the soil samples from the landfill that have undergone organic pollution and heavy metal remediation, fly ash is reused in the landfill to generate remediated off-site fly ash landfill reuse soil.

[0068] In this embodiment of the invention, based on the planning of the landfill, soil samples that have been remediated for organic pollution and heavy metals are used for fly ash landfill reuse. In the fly ash landfill area, the location of the porous soil in the fly ash layer is first determined, and the soil samples are filled into the pores. A vibratory roller is used to compact the soil at a speed of 5 kilometers per hour and a pressure of 2 tons to form porous soil. For the cover soil, soil samples are laid according to the design requirements to form a 0.5-meter-thick layered structure. After being leveled with a grader, the soil is compacted at a speed of 4 kilometers per hour and a pressure of 3 tons to meet the mid-term coverage requirements of the geomembrane of the pile. Finally, the remediated fly ash landfill reuse soil is generated.

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

[0070] Step S11: By performing deep stratified sampling on the corresponding off-site remediation contaminated soil pile within the landfill disposal center, a soil sample is taken every 0.5 meters and the corresponding sampling location and depth are marked to obtain off-site remediation contaminated soil samples corresponding to different depth layers.

[0071] Step S12: Detect the heavy metal content of soil samples from off-site remediation at different depth levels to obtain the heavy metal content of different types of soil at each depth level.

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

[0073] Step S14: Based on the content of heavy metals in soil at different depth levels and the types of organic pollutants in soil at different depth levels, classify the soil samples for off-site remediation of contaminated soil samples to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

[0074] As an embodiment of the present invention, reference Figure 2 As shown, Figure 1 A detailed flowchart of step S1 is shown below. In this embodiment, step S1 includes the following steps:

[0075] Step S11: By performing deep stratified sampling on the corresponding off-site remediation contaminated soil pile within the landfill disposal center, a soil sample is taken every 0.5 meters and the corresponding sampling location and depth are marked to obtain off-site remediation contaminated soil samples corresponding to different depth layers.

[0076] In this embodiment of the invention, deep stratified sampling is conducted on contaminated soil piles for off-site remediation at the landfill disposal center. A specialized soil sampling drill with a 5-centimeter diameter bit is used to precisely extract samples from the soil pile. Samples are taken at 0.5-meter intervals, and each sample is immediately labeled with its location and depth. The sampling process strictly follows a sequence from shallow to deep to ensure the representativeness and accuracy of the samples. For example, sampling is performed at different locations such as the edge and center of the pile to comprehensively obtain soil conditions from different areas. The collected soil samples are placed in specialized sealed containers to prevent external contamination and moisture loss, ultimately yielding off-site remediation soil samples corresponding to different depth levels.

[0077] Step S12: Detect the heavy metal content of soil samples from off-site remediation at different depth levels to obtain the heavy metal content of different types of soil at each depth level.

[0078] In this embodiment of the invention, heavy metal content was detected in off-site remediation soil samples corresponding to different depths. An atomic absorption spectrometer was used to determine the content of heavy metals such as lead, mercury, and cadmium in the samples. First, the soil samples were pretreated by using aqua regia to dissolve the heavy metal elements. Then, the digested solution was injected into the atomic absorption spectrometer. The instrument irradiated the solution with light of a specific wavelength and accurately calculated the content of different types of heavy metals such as lead, mercury, and cadmium based on the degree of light absorption by the heavy metal elements. During the detection process, standard substances were used for calibration after every 10 samples to ensure the accuracy of the results. After a series of detection operations, the heavy metal content of different types of soil at each depth was finally obtained.

[0079] Step S13: Analyze the types of organic pollutants in the off-site remediation soil samples corresponding to different depth levels, in order to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons, and obtain the types of soil organic pollutants corresponding to each depth level.

[0080] In this embodiment of the invention, organic pollutant types are analyzed in off-site remediation soil samples corresponding to different depths using gas chromatography-mass spectrometry (GC-MS). First, the soil sample is mixed with an organic solvent, and then the organic pollutants are dissolved in the solvent using ultrasonic extraction. The extract is then injected into the GC-MS instrument. The GC section separates different organic pollutants based on their partition coefficients between the stationary and mobile phases, while the mass spectrometry section performs qualitative analysis based on the mass and structural information of the organic pollutant molecules. This method focuses on analyzing organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons in the samples. Through detailed analysis, the types of organic pollutants in the soil corresponding to each depth level are finally obtained.

[0081] Step S14: Based on the content of heavy metals in soil at different depth levels and the types of organic pollutants in soil at different depth levels, classify the soil samples for off-site remediation of contaminated soil samples to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

[0082] In this embodiment of the invention, soil samples for off-site remediation are classified based on the content of different types of heavy metals and organic pollutants at each depth level. If a sample contains organic pollutants such as polycyclic aromatic hydrocarbons and petroleum hydrocarbons but not heavy metals such as lead, mercury, and cadmium, it is classified as an off-site remediation soil sample containing organic pollutants. If a sample contains only heavy metals such as lead, mercury, and cadmium but not organic pollutants, it is classified as an off-site remediation soil sample containing heavy metals. If a sample contains both organic pollutants and heavy metals, 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 content corresponding to different types mentioned in step S12 specifically includes the heavy metal content of lead, mercury, and gypsum.

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

[0085] Step S21: By setting up biogas collection wells in the landfill and using pipelines to transport the biogas collected in the biogas collection wells to the biogas purification device;

[0086] Step S22: Use a biogas purification device to purify the collected biogas, remove hydrogen sulfide and moisture impurities from the biogas, and improve the purity of the biogas. The purified biogas is then transported through pipelines to the contaminated soil remediation area as a biogas heat source during the remediation process.

[0087] Step S23: Based on the biogas heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

[0088] As an embodiment of the present invention, reference Figure 3 As shown, Figure 1 A detailed flowchart of step S2 is shown below. In this embodiment, step S2 includes the following steps:

[0089] Step S21: By setting up biogas collection wells in the landfill and using pipelines to transport the biogas collected in the biogas collection wells to the biogas purification device;

[0090] In this embodiment of the invention, multiple biogas collection wells are rationally planned and set up in the landfill. Based on the area of ​​the landfill and the distribution of waste, the layout follows the standard of one biogas collection well per 50 square meters. The biogas collection wells are made of corrosion-resistant high-strength plastic, with 5 mm diameter air inlets evenly distributed on their walls to ensure that biogas can smoothly enter the well. A sealing cover is installed on the top of each biogas collection well to prevent external air from entering. The biogas collection wells are connected by polyethylene pipes with a diameter of 10 cm, and then uniformly transported to the biogas purification device. The pipes are connected by heat fusion to ensure a tight connection and prevent biogas leakage. Gas flow meters and pressure sensors are installed on the pipes to monitor the flow and pressure of biogas in real time, providing data support for subsequent operations.

[0091] Step S22: Use a biogas purification device to purify the collected biogas, remove hydrogen sulfide and moisture impurities from the biogas, and improve the purity of the biogas. The purified biogas is then transported through pipelines to the contaminated soil remediation area as a biogas heat source during the remediation process.

[0092] In this embodiment of the invention, after biogas enters the biogas purification device, it first passes through a desulfurization tower to remove hydrogen sulfide. The desulfurization tower is filled with iron oxide desulfurizing agent. The biogas flows through the desulfurization tower at a flow rate of 50 cubic meters per hour. Under the action of the desulfurizing agent, hydrogen sulfide reacts chemically with iron oxide to generate iron sulfide precipitate, thereby achieving the removal of hydrogen sulfide. Next, the biogas enters a dryer to remove moisture and impurities. The dryer is filled with silica gel desiccant. The biogas stays in the dryer for 10 minutes, and the silica gel desiccant adsorbs the moisture in the biogas, reducing the water content of the biogas to below 1%. After desulfurization and drying, the purity of the biogas is significantly improved. The purified biogas is tested by a gas analyzer to ensure that its purity reaches more than 90%. The purified biogas is transported through pipelines to the contaminated soil remediation area as a biogas heat source in the remediation process.

[0093] Step S23: Based on the biogas heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

[0094] In this embodiment of the invention, soil samples containing organic pollutants from different pollution types are placed in the remediation reactor of the contaminated soil remediation area. The purified biogas is then transported to the burner of the remediation reactor via pipeline. The burner uses a premixed combustion method to ensure that the biogas can be fully combusted. By adjusting the valve opening of the burner, the biogas intake is controlled, thereby regulating the combustion intensity. A temperature sensor is installed inside the remediation reactor to monitor the soil temperature in real time. When the soil temperature is below 100℃, the biogas intake is increased to enhance the combustion intensity and raise the soil temperature. When the soil temperature is above 300℃, the biogas intake is reduced to decrease the combustion intensity and lower the soil temperature, ensuring that the soil temperature remains stable within the range of 100-300℃. Within this temperature range, the thermal motion of organic pollutant molecules intensifies, and the adsorption force between them and soil particles weakens, causing them to desorb from the surface of soil particles. Simultaneously, using the catalyst and oxygen inside the remediation reactor, the desorbed organic pollutants undergo an oxidative decomposition reaction, transforming into harmless carbon dioxide and water. After a period of treatment, the organic pollutants are fully desorbed and transformed, ultimately generating off-site remediation soil samples containing heavy metals and showing signs of organic pollution remediation.

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

[0096] Step S231: By studying the energy release corresponding to the biogas heat source during combustion, the combustion heat value corresponding to the biogas heat source is measured by a combustion heat measuring instrument, and the combustion temperature curve corresponding to the biogas heat source is plotted based on the combustion heat value.

[0097] In this embodiment of the invention, the calorific value of a biogas heat source is measured in a laboratory environment using a professional calorific value analyzer. First, a certain amount of biogas heat source is precisely injected into the reaction vessel of the calorific value analyzer. This reaction vessel has good insulation performance, which can minimize heat loss. The instrument is started, allowing the biogas heat source to burn fully in a pure oxygen environment. The heat released during combustion is accurately captured and recorded by the analyzer. Through repeated measurements, the average value is taken to ensure the accuracy of the data. Based on the measured calorific value data, a combustion temperature curve corresponding to the biogas heat source is plotted using graphing software, with combustion time as the x-axis and combustion temperature as the y-axis. This curve can intuitively show the temperature change of the biogas heat source over time during combustion, providing an important basis for subsequent analysis.

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

[0099] In this embodiment of the invention, the combustion efficiency of the biogas heat source is statistically analyzed based on the plotted biogas heat source combustion temperature curve. First, the stage in the curve that reaches the highest combustion temperature is determined. This stage represents the moment when the biogas heat source burns most completely. By analyzing the rising and falling trends of the curve, the time period in which heat is effectively released during combustion is calculated. The heat released during this time period is compared with the heat that the biogas heat source can theoretically release when completely combusted. The theoretical heat of complete combustion can be accurately calculated based on the chemical composition and chemical reaction equation of biogas. Through this comparison, the combustion efficiency of the biogas heat source is obtained. For example, if the heat released during the effective combustion time period accounts for 80% of the theoretical heat of complete combustion, then the combustion efficiency of the biogas heat source is 80%.

[0100] Step S233: Place the soil samples containing organic pollutants from the off-site remediation soil samples corresponding to different pollution types into the corresponding remediation reactor in the landfill, and control the biogas intake and combustion intensity in the remediation reactor based on the combustion efficiency of the biogas heat source, so that the soil temperature in the remediation reactor is within the appropriate temperature range for organic pollutant desorption, specifically 100-300℃.

[0101] In this embodiment of the invention, soil samples containing organic pollutants from different pollution types are accurately placed in a remediation reactor within a landfill. Based on the previously obtained biogas heat source combustion efficiency, the biogas intake and combustion intensity within the remediation reactor are precisely controlled. When the combustion efficiency is high, the biogas intake is appropriately reduced to avoid excessive soil temperature due to excessive heat. When the combustion efficiency is low, the biogas intake is increased to enhance the combustion intensity and ensure sufficient heat supply. The soil temperature is monitored in real time by a temperature sensor installed within the remediation 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 based on the feedback data, so that the soil temperature within the remediation reactor is stabilized within the suitable temperature range of 100-300℃ for organic pollutant desorption.

[0102] Step S234: Based on the controlled temperature range, the organic pollutants in the off-site remediation soil samples containing organic pollutants corresponding to different pollution types are desorbed and transformed to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

[0103] In this embodiment of the invention, after the soil temperature in the remediation reactor is stabilized within a controlled temperature range of 100-300℃, the organic pollutant desorption and transformation of the off-site remediation soil sample containing organic pollutants is initiated. Within this temperature range, the thermal motion of organic pollutant molecules intensifies, and the adsorption force between them and soil particles weakens, thereby desorbing them from the surface of the soil particles. Simultaneously, utilizing the specific catalytic environment and chemical reaction conditions within the remediation reactor, the desorbed organic pollutants undergo transformation reactions. For example, some organic pollutants undergo oxidative decomposition reactions under the action of high temperature and catalysts, transforming into harmless carbon dioxide and water. After a period of treatment, the organic pollutants are fully desorbed and transformed, ultimately generating an off-site remediation soil sample containing heavy metals and having completed organic pollution remediation.

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

[0105] Based on a well-controlled temperature range, organic pollutants were desorbed from soil samples containing organic pollutants in off-site remediation samples corresponding to different pollution types using a remediation reactor. Ultrasonic waves of corresponding frequencies were applied in the remediation reactor based on the temperature range, and the cavitation effect and mechanical vibration of the ultrasonic waves were used to destroy the adsorption force between soil particles and organic pollutants, so as to obtain soil samples after organic pollutant desorption.

[0106] In this embodiment of the invention, by precisely controlling the temperature range to 30-50 degrees Celsius, a suitable environment is provided for subsequent organic pollutant desorption. This ensures that the organic pollutants in the soil have a certain level of activity while avoiding unnecessary energy waste or adverse effects on soil structure due to excessively high temperatures. Soil samples containing organic pollutants of different pollution types are placed in the remediation reactor, and an ultrasonic generator is activated with its frequency set to 20 kHz. Inside the remediation reactor, ultrasonic waves propagate continuously, and their cavitation effect causes the formation of tiny bubbles in the liquid. These bubbles rapidly collapse after growing to a certain extent, instantly 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 together destroy the adsorption force between the soil particles and organic pollutants. After 2 hours of continuous treatment, the organic pollutants are successfully desorbed from the soil particles, and finally, a soil sample after organic pollutant desorption is obtained.

[0107] Preferably, the soil sample after desorption of organic pollutants 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 as to rapidly and thoroughly decompose the corresponding organic pollutants into harmless carbon dioxide and water in the aerobic environment, and obtain the soil sample after oxidative decomposition of organic pollutants.

[0108] In this embodiment of the invention, soil samples desorbed from organic pollutants are transferred to an aerobic environment within a remediation reactor via a specialized conveying device. In this environment, manganese dioxide is added as a metal oxide catalyst via a precise feeding device, with the addition amount strictly controlled at 3% of the soil sample mass. Under aerobic conditions, the manganese dioxide catalyst plays a crucial role; its surface active sites adsorb the desorbed organic pollutants and oxygen molecules, promoting a chemical reaction. Over the next 3 hours, the organic pollutants react fully with oxygen under the action of the catalyst, their molecular structure is gradually destroyed and oxidized, ultimately transforming the organic pollutants rapidly and completely into harmless carbon dioxide and water, thus obtaining a soil sample after the oxidative decomposition of organic pollution.

[0109] Preferably, the residual amount of organic pollutants and the contents of decomposition products carbon dioxide, water and incomplete decomposition intermediates in the gas are obtained by detecting the soil sample after the organic pollution oxidation and decomposition. At the same time, the concentration of organic pollutants in the initial soil sample is obtained. 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 incomplete decomposition intermediates in the gas, the organic pollution removal rate is calculated by using the organic pollution removal rate calculation formula to quantify the removal of organic pollutants in the soil sample after the organic pollution oxidation and decomposition, so as to obtain the organic pollutant removal rate of the soil sample.

[0110] In this embodiment of the invention, soil samples after oxidative decomposition of organic pollutants are analyzed using various chemical analysis instruments. Gas chromatography-mass spectrometry (GC-MS) is used to analyze the soil samples, accurately determining the residual amount of organic pollutants. An infrared gas analyzer is used to detect the gas composition, obtaining the content of decomposition products carbon dioxide, water, and incompletely decomposed intermediate products. Simultaneously, when processing the initial soil sample, a spectrophotometer is used to determine the concentration of organic pollutants. These key data are then substituted into a system that includes the total removal time, time variable parameters, residual organic pollutants, the content of carbon dioxide (a decomposition product) in the gas, and the content of decomposition products in the gas. The content of the product water, the content of the incompletely decomposed intermediate products, the relative molecular mass of the incompletely decomposed intermediate products, the concentration of organic pollutants in the initial soil sample, and related parameters constitute a suitable formula for calculating the organic pollution removal rate. After accurate calculation, the organic pollutant removal rate of the soil sample is obtained, thereby quantifying the removal effect of organic pollution. In addition, this formula for calculating the organic pollution removal rate can also use any removal rate calculation method in the field to replace the removal quantification calculation process, such as removal rate = (initial concentration - residual amount) / initial concentration × 100%, and is not limited to this formula for calculating the organic pollution removal rate.

[0111] Preferably, the temperature, pressure, and biogas consumption rate of the repair reactor are obtained, and the operating efficiency of the repair reactor is analyzed based on the temperature, pressure, and biogas consumption rate.

[0112] In this embodiment of the invention, during the operation of the repair reactor, a temperature sensor monitors the internal temperature in real time, a pressure sensor continuously measures the pressure, and a gas flow meter accurately measures the biogas consumption rate. These sensors transmit the acquired temperature, pressure, and biogas consumption rate data to a data analysis system via a data transmission line. In the data analysis system, the relationship between temperature, pressure, and reaction rate is analyzed using established mathematical models and reaction kinetic principles. For example, increased temperature accelerates the reaction rate, but excessively high temperatures can lead to catalyst deactivation. The influence of pressure on reaction equilibrium and the correlation between biogas consumption rate and reaction progress are also analyzed. Based on these analysis results, the operating efficiency of the repair reactor is comprehensively evaluated to determine whether the reaction is sufficient and whether energy utilization is efficient. Finally, the operating efficiency of the repair reactor is obtained, i.e., operating efficiency = temperature × (biogas consumption efficiency / pressure).

[0113] Preferably, the organic pollutant removal of soil samples after organic pollution oxidation and decomposition is optimized and adjusted based on the organic pollutant removal rate of soil samples and the corresponding operating efficiency of the remediation reactor. Soil samples with incomplete organic pollution removal are identified by comparing the organic pollutant removal rate of soil samples with the preset removal threshold. The soil samples with incomplete organic pollution removal are then optimized and adjusted based on the operating efficiency of the remediation reactor to enhance the desorption and catalytic reaction conditions of the remediation reactor, thereby generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0114] In this embodiment of the invention, the calculated removal rate of organic pollutants in the soil sample is compared with a preset removal threshold (set to 90%). If the removal rate is lower than 90%, the soil sample is determined to have incomplete organic pollution removal. Based on the operational efficiency analysis results of the remediation reactor, if it is found that the low temperature affects the reaction rate, the temperature is increased to 50-60 degrees Celsius using a heating device to accelerate the desorption and decomposition reaction of organic pollutants. If the pressure is insufficient, the pressure is appropriately increased using a pressurization device to promote the reaction in a direction conducive to the decomposition of organic pollutants. If the biogas consumption rate is unreasonable, the feed rate is adjusted to make the reaction system reach a better operating state. By strengthening the desorption and catalytic reaction conditions corresponding to the remediation reactor, the soil sample with incomplete organic pollution removal is reprocessed until a satisfactory removal effect is achieved, ultimately generating an off-site remediation soil sample containing heavy metals and having completed organic pollution remediation.

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

[0116]

[0117] In the formula, R is the removal rate of organic pollutants in the soil sample, T is the total removal time, t is a time variable parameter, C(t) is the residual amount of organic pollutants at time t, and m c m represents the content of carbon dioxide, a decomposition product, in the gas. h P represents the content of water, a decomposition product in the gas, and n represents the total amount of incompletely decomposed intermediate products in the gas. i β represents the content of the i-th incompletely decomposed intermediate product. i Ci represents the relative molecular mass of the i-th incompletely decomposed intermediate product, and C0 represents the concentration of organic pollutants in the initial soil sample.

[0118] This invention, through the use of a specific mathematical model and verification, derives a formula for calculating the organic pollution removal rate. This formula is used to quantify the removal of organic pollutants from soil samples after oxidative decomposition. The formula fully considers the organic pollutant removal rate R, the total removal time T, the time variable parameter t, the residual organic pollutant C(t) at time t, and the content m of the decomposition product carbon dioxide in the gas. c The content m of water, a decomposition product in the gas. h The total quantity 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 corresponding to the i-th incompletely decomposed intermediate product i The initial concentration of organic pollutants C0 in the soil sample was used to establish a functional relationship between the organic pollutant removal rate R of the soil sample and the above parameters. This formula enables the quantitative calculation of organic pollution removal from soil samples after oxidative decomposition. Furthermore, it comprehensively considers the removal of organic pollutants during the remediation process, calculating the removal rate by comparing residual organic pollutant levels at different time points with the initial pollutant concentration, thus reflecting the effectiveness of the remediation. The formula not only considers the removal of organic pollutants but also the content of decomposition products (such as carbon dioxide and water) in the gas, further enhancing the comprehensiveness of the pollution removal rate calculation. Incompletely decomposed intermediate products are also taken into account, helping to more accurately reflect the removal effect during soil remediation and avoiding the omission of certain key pollutant components. By calculating the content of decomposition products and incompletely decomposed intermediate products in the gas, the formula helps analyze how organic pollutants are oxidized and decomposed under aerobic conditions. This process can detect the presence of intermediate products, which is very useful for determining whether further optimization of reaction conditions is needed. By combining the organic pollution removal rate with data such as reactor temperature, pressure, and biogas consumption rate, the calculation formula provides a scientific basis for the operating efficiency of the remediation reactor. Based on this information, reaction conditions during the remediation process can be effectively adjusted and optimized to achieve higher pollution removal results. The application of this formula allows the remediation process to be adjusted in real time based on the removal rate and reactor efficiency. By comparing the preset removal threshold with the actual removal rate, problems of incomplete removal of organic pollutants can be identified and resolved in a timely manner, thereby optimizing the operating conditions of the remediation reactor and ensuring maximum remediation effect.

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

[0120] Step S31: Solidification and stabilization coupled remediation is carried out on off-site remediation soil samples containing heavy metals and after organic pollution remediation. Solidification agent and stabilizer are added to the corresponding soil samples, and the solidification agent and stabilizer are fully mixed with the soil samples by a mixing device. Under certain temperature and humidity conditions, the solidification agent reacts chemically with the corresponding heavy metals in the soil samples to form stable compounds. At the same time, the stabilizer forms chelates with the corresponding heavy metal ions. The corresponding compounds and chelates are removed to generate solidified and stabilized soil samples containing heavy metals.

[0121] In this embodiment of the invention, a certain amount of soil samples containing heavy metals and which have undergone organic pollution remediation are placed in a special mixing container. A solidifying agent (such as cement) is added at 10% of the soil sample weight, and a stabilizer (such as sodium diethyldithiocarbamate) is added at 5% of the soil sample weight. The mixing equipment is started, and the mixing speed is set to 200 revolutions per minute for 30 minutes to ensure thorough mixing of the solidifying agent, stabilizer, and soil sample. The mixed soil sample is then transferred to a constant temperature and humidity curing chamber, with the temperature set at 25 degrees Celsius and the humidity at 60%, and 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 cement react with lead ions in the soil to form a stable calcium leadate compound. Simultaneously, the stabilizer 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 using a filtration device, ultimately yielding a solidified and stabilized soil sample containing heavy metals.

[0122] Step S32: Conduct chemical environmental impact assessment analysis on the soil samples containing heavy metals after solidification and stabilization remediation, so as to use chemical analysis to determine the residual amounts of corresponding organic pollutants and heavy metals in the soil samples, and to determine whether the corresponding soil remediation targets have been achieved, so as to obtain the environmental impact assessment results of the remediated soil samples.

[0123] In this embodiment of the invention, multiple sub-samples, each weighing 100 grams, are randomly selected from the solidified and stabilized soil sample containing heavy metals. Chemical analysis instruments, such as atomic absorption spectrometry and gas chromatography, are used to analyze the residual amounts of organic pollutants and heavy metals in each sub-sample. For heavy metals, the content of heavy metal elements such as lead, mercury, cadmium, and chromium in the soil sample is measured using atomic absorption spectrometry. For organic pollutants, the residual amounts of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides in the soil sample are analyzed using gas chromatography. Based on pre-set soil remediation targets, such as lead content below 50 mg / kg, mercury content below 0.05 mg / kg, and total PAHs below 10 mg / kg, it is determined whether each sub-sample meets the soil remediation target. The analysis results of all sub-samples are summarized to obtain the environmental impact assessment result of the remediated soil sample, determining the average residual amounts of organic pollutants and heavy metals in the entire soil sample and whether the remediation target has been met.

[0124] 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, then the corresponding soil samples containing heavy metals are identified as soil samples that have completed the remediation of organic pollution and heavy metals. If the environmental impact assessment results of the remediated soil samples have not reached the corresponding soil remediation target, then the corresponding soil samples containing heavy metals will undergo cyclic organic pollution desorption and solidification stabilization remediation treatment again until the corresponding soil remediation target is reached, and soil samples that have completed the remediation of organic pollution and heavy metals will be generated.

[0125] In this embodiment of the invention, by comparing the previously obtained environmental impact assessment results of the remediated soil sample with the corresponding soil remediation target, if the environmental impact assessment results of the remediated soil sample show that the residual amounts of organic pollutants and heavy metals in the soil sample have reached the preset soil remediation target, for example, the lead content is 40 mg / kg and the total amount of polycyclic aromatic hydrocarbons is 8 mg / kg, both of which are lower than the target values, then the corresponding heavy metal-containing soil sample is determined as a soil sample that has completed the remediation of organic pollution and heavy metals. If the environmental impact assessment results of the remediated soil sample show that there are residual amounts of organic pollutants or heavy metals in the soil sample... If the soil remediation target is not met, such as a mercury content of 0.1 mg / kg, which is higher than the target value of 0.05 mg / kg, the corresponding soil sample containing heavy metals will undergo organic pollution desorption treatment again. Solvent extraction will be used, with dichloromethane as the extractant, at a ratio of 1:2 between the soil sample and the extractant, for 2 hours. Then, solidification and stabilization remediation treatment will be carried out, and step S31 will be repeated until the residual amounts of organic pollutants and heavy metals in the soil sample reach the corresponding soil remediation target. Finally, a soil sample after organic pollution and heavy metal remediation will be generated.

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

[0127] Step S41: By co-processing the corresponding fly ash in the landfill with soil samples that have completed organic pollution and heavy metal remediation, an appropriate amount of solidifying agent and additives are added to the fly ash and mixed with the soil samples that have completed organic pollution and heavy metal remediation in a certain proportion, and the corresponding solidified fly ash blocks are prepared by pressure molding equipment to obtain the remediated soil solidified fly ash blocks.

[0128] In this embodiment of the invention, a certain amount of fly ash is collected from a landfill, and soil samples that have undergone organic pollution and heavy metal remediation are obtained. In a dedicated mixing site, the fly ash and the remediated soil samples are mixed in a predetermined ratio, for example, 100 kg of fly ash is mixed with 50 kg of remediated soil samples. Then, an appropriate amount of curing agent, such as cement, is added to the mixture of fly ash and soil samples at 10% of the weight of fly ash, and an additive, such as activated silica powder, is added at 5% of the weight of fly ash. The mixture is thoroughly stirred using a mixing device to ensure that the curing agent, additives, fly ash, and soil samples are evenly mixed. After the mixture is evenly stirred, it is placed in a pressure molding device with a pressure of 5 MPa and a holding time of 30 minutes. The mixture is then formed into regularly shaped solidified fly ash blocks using the pressure molding device, ultimately obtaining the remediated solidified fly ash blocks.

[0129] Step S42: The remediated solidified fly ash blocks are transported to the corresponding fly ash landfill area within the landfill. The solidified fly ash blocks are used as the porous soil corresponding to the fly ash layer and the corresponding cover soil in the middle for fly ash landfill reuse. The corresponding pores are used to fill and compact the solidified fly ash blocks to form the corresponding porous soil. The corresponding unit thickness of the fly ash landfill design is sufficient to meet the mid-term coverage of the geomembrane of the pile body and to form the corresponding cover soil, thus generating the remediated off-site fly ash landfill reuse soil.

[0130] In this embodiment of the invention, the previously obtained remediated solidified fly ash blocks are transported by transport vehicles to the fly ash landfill area within the landfill. Within the fly ash landfill area, the location of the fly ash layer is first determined. For the corresponding porous soil filling, the solidified fly ash blocks are placed into the pores. Compaction equipment, such as a vibratory roller, is used to compact the solidified fly ash blocks at a speed of 5 km / h and a pressure of 2 tons, ensuring the solidified fly ash blocks tightly fill the pores and form porous soil. The intermediate cover... For the soil component, the unit thickness is determined according to the fly ash landfill design. For example, if the unit thickness is set to 0.5 meters, the soil-stabilized fly ash blocks are laid on the fly ash landfill layer to form a 0.5-meter-thick layered structure. Then, leveling equipment, such as a grader, is used to level the laid soil-stabilized fly ash blocks. Finally, compaction equipment is used to compact the soil at a speed of 4 kilometers per hour and a pressure of 3 tons to meet the requirements of the geomembrane for mid-term coverage of the pile, forming the cover soil. After such operations, the remediated off-site fly ash landfill reuse soil is finally generated.

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

[0132] The contaminated soil sample classification module is used to perform deep stratified sampling of contaminated soil piles corresponding to off-site remediation within the disposal center of the landfill to obtain contaminated soil samples for off-site remediation at different depth levels; and to classify the soil sample characteristics of the contaminated soil samples for off-site remediation at different depth levels to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

[0133] The organic pollution desorption and remediation module is used to obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, it desorbs and transforms organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types, thereby generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation.

[0134] The heavy metal and environmental impact assessment (EIA) cyclic remediation module is used to perform solidification and stabilization coupled remediation on off-site remediation soil samples containing heavy metals that have already undergone organic pollution remediation, to generate solidified and stabilized heavy metal-containing soil samples; chemical EIA analysis is performed on the solidified and stabilized heavy metal-containing soil samples to obtain the EIA results of the remediated soil samples; based on the EIA results of the remediated soil samples, the solidified and stabilized heavy metal-containing soil samples are subjected to cyclic remediation treatment, thereby generating soil samples that have completed organic pollution and heavy metal remediation.

[0135] The fly ash landfill reuse module is used to reuse fly ash from soil samples that have undergone organic pollution and heavy metal remediation at landfill sites, thereby generating remediated fly ash landfill reuse soil at other locations.

[0136] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0137] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for off-site remediation of contaminated soil coupled with landfill, characterized in that, Includes the following steps: Step S1: Conduct deep stratified sampling of the contaminated soil pile corresponding to the off-site remediation in the disposal center of the landfill to obtain off-site remediation contaminated soil samples corresponding to different depth levels; classify 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, containing heavy metals, and containing both organic pollutants and heavy metals. Step S2: Obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, perform organic pollution desorption and transformation on off-site remediation soil samples containing organic pollutants corresponding to different pollution types, generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation; wherein, the organic pollution desorption and transformation includes: Based on a well-controlled temperature range, organic pollutants were desorbed from soil samples containing organic pollutants in off-site remediation samples corresponding to different pollution types using a remediation reactor. Ultrasonic waves of corresponding frequencies were applied in the remediation reactor based on the temperature range, and the cavitation effect and mechanical vibration of the ultrasonic waves were used to destroy the adsorption force between soil particles and organic pollutants, so as to obtain soil samples after organic pollutant desorption. Soil samples after desorption of organic pollutants are transferred to the corresponding aerobic environment in the remediation reactor, and the desorbed organic pollutants in the soil samples are oxidized and decomposed by adding corresponding metal oxide catalysts. The corresponding organic pollutants are rapidly and thoroughly decomposed into harmless carbon dioxide and water in the aerobic environment, and the soil samples after oxidative decomposition of organic pollutants are obtained. By analyzing soil samples after the oxidative decomposition of organic pollutants, the residual amount of organic pollutants and the contents of decomposition products carbon dioxide, water and incomplete decomposition intermediates in the gas were obtained. At the same time, the concentration of organic pollutants in the initial soil sample was obtained. 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 incomplete decomposition intermediates in the gas, the organic pollutant removal rate was calculated using the organic pollutant removal rate calculation formula to obtain the organic pollutant removal rate of the soil sample. Obtain the temperature, pressure, and biogas consumption rate corresponding to the repair reactor, and analyze the operating efficiency of the repair reactor based on 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 organic pollutant removal of soil samples after organic pollution oxidation and decomposition is optimized and adjusted. Based on the preset removal threshold and the organic pollutant removal rate of soil samples, soil samples with incomplete organic pollution removal are identified. Based on the operating efficiency of the remediation reactor, the soil samples with incomplete organic pollution removal are optimized and adjusted to enhance the desorption and catalytic reaction conditions of the remediation reactor, so as to generate off-site remediation soil samples containing heavy metals and having completed organic pollution remediation. Step S3: Perform solidification and stabilization coupled remediation on off-site soil samples containing heavy metals and after organic pollution remediation to generate solidified and stabilized heavy metal-containing soil samples; conduct chemical environmental impact assessment analysis on solidified and stabilized heavy metal-containing soil samples to obtain environmental impact assessment results of remediated soil samples; based on the environmental impact assessment results of remediated soil samples, perform cyclic remediation treatment on solidified and stabilized heavy metal-containing soil samples to generate soil samples after organic pollution and heavy metal remediation. Step S4: Based on the soil samples from the landfill that have undergone organic pollution and heavy metal remediation, fly ash is reused in the landfill to generate remediated off-site fly ash landfill reuse soil.

2. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 1, characterized in that, Step S1 includes the following steps: Step S11: By performing deep stratified sampling on the corresponding off-site remediation contaminated soil pile within the landfill disposal center, a soil sample is taken every 0.5 meters and the corresponding sampling location and depth are marked to obtain off-site remediation contaminated soil samples corresponding to different depth layers. Step S12: Detect the heavy metal content of soil samples from off-site remediation at different depth levels to obtain the heavy metal content of different types of soil at each depth level. Step S13: Analyze the types of organic pollutants in the off-site remediation soil samples corresponding to different depth levels, in order to analyze the corresponding polycyclic aromatic hydrocarbons and petroleum hydrocarbons, and obtain the types of soil organic pollutants corresponding to each depth level. Step S14: Based on the content of heavy metals in soil at different depth levels and the types of organic pollutants in soil at different depth levels, classify the soil samples for off-site remediation of contaminated soil samples to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals.

3. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 2, characterized in that, The soil heavy metal content corresponding to different types mentioned in step S12 specifically includes the heavy metal content of lead, mercury, and gypsum.

4. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 1, characterized in that, Step S2 includes the following steps: Step S21: By setting up biogas collection wells in the landfill and using pipelines to transport the biogas collected in the biogas collection wells to the biogas purification device; Step S22: Use a biogas purification device to purify the collected biogas, remove hydrogen sulfide and moisture impurities from the biogas, and improve the purity of the biogas. The purified biogas is then transported through pipelines to the contaminated soil remediation area as a biogas heat source during the remediation process. Step S23: Based on the biogas heat source, desorb and transform organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

5. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 4, characterized in that, Step S23 includes the following steps: Step S231: By studying the energy release corresponding to the biogas heat source during combustion, the combustion heat value corresponding to the biogas heat source is measured by a combustion heat measuring instrument, and the combustion temperature curve corresponding to the biogas heat source is plotted based on the combustion heat value. Step S232: Based on the combustion temperature curve corresponding to the biogas heat source, perform combustion efficiency statistics on the biogas heat source to obtain the combustion efficiency corresponding to the biogas heat source. Step S233: Place the soil samples containing organic pollutants from the off-site remediation soil samples corresponding to different pollution types into the corresponding remediation reactor in the landfill, and control the biogas intake and combustion intensity in the remediation reactor based on the combustion efficiency of the biogas heat source, so that the soil temperature in the remediation reactor is within the appropriate temperature range for organic pollutant desorption, specifically 100-300℃. Step S234: Based on the controlled temperature range, the organic pollutants in the off-site remediation soil samples containing organic pollutants corresponding to different pollution types are desorbed and transformed to generate off-site remediation soil samples containing heavy metals and after organic pollution remediation.

6. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 1, characterized in that, The formula for calculating the organic pollution removal rate is as follows: ； In the formula, The removal rate of organic pollutants in soil samples. To remove the total duration, For time-varying parameters, In time The amount of organic pollutants remaining at the location This represents the content of carbon dioxide, a decomposition product, in the gas. This represents the content of water, a decomposition product, in the gas. This represents the total amount of incompletely decomposed intermediate products in the gas. For the first The content of incompletely decomposed intermediate products For the first The relative molecular mass of each incompletely decomposed intermediate product This represents the concentration of organic pollutants in the initial soil sample.

7. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 1, characterized in that, Step S3 includes the following steps: Step S31: Solidification and stabilization coupled remediation is carried out on off-site remediation soil samples containing heavy metals and after organic pollution remediation. Solidification agent and stabilizer are added to the corresponding soil samples, and the solidification agent and stabilizer are fully mixed with the soil samples by a mixing device. Under certain temperature and humidity conditions, the solidification agent reacts chemically with the corresponding heavy metals in the soil samples to form stable compounds. At the same time, the stabilizer forms chelates with the corresponding heavy metal ions. The corresponding compounds and chelates are removed to generate solidified and stabilized soil samples containing heavy metals. Step S32: Conduct chemical environmental impact assessment analysis on the soil samples containing heavy metals after solidification and stabilization remediation, so as to use chemical analysis to determine the residual amounts of corresponding organic pollutants and heavy metals in the soil samples, and to determine whether the corresponding soil remediation targets have been achieved, so as to obtain the environmental impact assessment results of the remediated soil samples. 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, then the corresponding soil samples containing heavy metals are identified as soil samples that have completed the remediation of organic pollution and heavy metals. If the environmental impact assessment results of the remediated soil samples have not reached the corresponding soil remediation target, then the corresponding soil samples containing heavy metals will undergo cyclic organic pollution desorption and solidification stabilization remediation treatment again until the corresponding soil remediation target is reached, and soil samples that have completed the remediation of organic pollution and heavy metals will be generated.

8. The method for off-site remediation of contaminated soil coupled with landfill as described in claim 1, characterized in that, Step S4 includes the following steps: Step S41: By co-processing the corresponding fly ash in the landfill with soil samples that have completed organic pollution and heavy metal remediation, an appropriate amount of solidifying agent and additives are added to the fly ash and mixed with the soil samples that have completed organic pollution and heavy metal remediation in a certain proportion, and the corresponding solidified fly ash blocks are prepared by pressure molding equipment to obtain the remediated soil solidified fly ash blocks. Step S42: The remediated solidified fly ash blocks are transported to the corresponding fly ash landfill area within the landfill. The solidified fly ash blocks are used as the porous soil corresponding to the fly ash layer and the corresponding cover soil in the middle for fly ash landfill reuse. The corresponding pores are used to fill and compact the solidified fly ash blocks to form the corresponding porous soil. The corresponding unit thickness of the fly ash landfill design is sufficient to meet the mid-term coverage of the geomembrane of the pile body and to form the corresponding cover soil, thus generating the remediated off-site fly ash landfill reuse soil.

9. A landfill-coupled off-site remediation system for contaminated soil, characterized in that, For implementing the landfill-coupled contaminated soil off-site remediation method as described in claim 1, the landfill-coupled contaminated soil off-site remediation system comprises: The contaminated soil sample classification module is used to perform deep stratified sampling of contaminated soil piles corresponding to off-site remediation within the disposal center of the landfill to obtain contaminated soil samples for off-site remediation at different depth levels; and to classify the soil sample characteristics of the contaminated soil samples for off-site remediation at different depth levels to obtain off-site remediation soil samples corresponding to different pollution types, including off-site remediation soil samples containing organic pollutants, containing heavy metals, and containing both organic pollutants and heavy metals. The organic pollution desorption and remediation module is used to obtain the corresponding purified biogas from the landfill and use it as a heat source. Based on the heat source, it desorbs and transforms organic pollutants in off-site remediation soil samples containing organic pollutants corresponding to different pollution types, thereby generating off-site remediation soil samples containing heavy metals and having completed organic pollution remediation. The heavy metal and environmental impact assessment (EIA) cyclic remediation module is used to perform solidification and stabilization coupled remediation on off-site remediation soil samples containing heavy metals that have already undergone organic pollution remediation, to generate solidified and stabilized heavy metal-containing soil samples; chemical EIA analysis is performed on the solidified and stabilized heavy metal-containing soil samples to obtain the EIA results of the remediated soil samples; based on the EIA results of the remediated soil samples, the solidified and stabilized heavy metal-containing soil samples are subjected to cyclic remediation treatment, thereby generating soil samples that have completed organic pollution and heavy metal remediation. The fly ash landfill reuse module is used to reuse fly ash from soil samples that have undergone organic pollution and heavy metal remediation at landfill sites, thereby generating remediated fly ash landfill reuse soil at other locations.

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