A method and system for the remediation of a landfill

Abstract

The application provides a landfill treatment method and system, wherein the method comprises the following steps: arranging a well group on a landfill, the well group comprising a plurality of repair wells and a plurality of extraction wells, the repair wells and the extraction wells being used in pairs; establishing an aerobic aeration, liquid phase and gas phase extraction system connected with the repair wells and the extraction wells; formulating a landfill treatment plan according to detected parameters and corresponding indexes of the landfill, and treating the landfill by using the aerobic aeration, liquid phase and gas phase extraction system. The application adopts the aeration aerobic technology to accelerate the degradation of the stockpiled garbage, extracts and processes the landfill gas and the leachate, and samples and detects the soil and the underground water and injects the medicine for repair, so that the overall treatment of the landfill is realized. The technical scheme is not only suitable for the in-situ treatment of the stockpiled garbage without excavation and without leaving the site, but also suitable for the stabilization pretreatment of the stockpiled garbage in the ex-situ treatment.

Description

Technical Field

[0001] This invention relates generally to the field of waste treatment technology, mainly to landfill remediation technology, specifically a landfill remediation method and system. Background Technology

[0002] The development of landfill in my country has generally gone through five stages: decentralized pit and trench filling, centralized dumping, simple landfilling, quasi-sanitary landfilling, and sanitary landfilling. Early landfilling primarily consisted of the first four stages. Early landfills were informal, lacking bottom impermeability measures, biogas collection and treatment systems within the landfill, and proper sealing at the top. During the degradation process, large amounts of landfill gas are released haphazardly, posing safety hazards and containing various greenhouse gases. Rainfall disperses these harmful substances into surrounding surface water, underlying soil, and groundwater.

[0003] In the remediation of informal landfills, it is necessary to dispose of existing waste and leachate. An investigation and assessment are required to determine whether and to what extent the site's soil and groundwater are contaminated. Based on the actual conditions of the landfill, its planned use, and the sensitivity of the surrounding environment, and depending on whether the existing waste has been removed from the site, remediation can be divided into in-situ and ex-situ remediation. In-situ remediation primarily uses aerobic technology to accelerate the degradation of existing waste, collects and disposes of the landfill gas generated during degradation, and strengthens rainwater drainage, covering, and greening of the surface layer of existing waste to prevent pollution from spreading to groundwater and surface water. Ex-situ remediation mainly involves stabilizing, excavating, screening, and removing the existing waste for resource recovery. Leachate is generally treated using an extraction-treatment process. Currently, the aerobic aeration degradation in in-situ remediation and the waste stabilization and leachate extraction-treatment stages in ex-situ remediation are usually carried out independently, making seamless integration impossible. The resulting degradation liquid becomes new leachate, which is difficult to extract and effectively treat, becoming a new source of pollution and causing secondary pollution to the soil and groundwater at the bottom of the landfill. Meanwhile, during the long-term degradation process of existing waste, a large amount of degradation liquid seeps into the ground, forming leachate that spreads into the groundwater. Although the leachate is extracted, the degradation rate of the polluted groundwater is slow due to factors such as lack of oxygen, resulting in a serious rebound of polluted groundwater exceeding the standard and difficulty in achieving natural decay and compliance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to propose a method and system for the treatment of landfills, which can achieve comprehensive treatment of landfills. It is applicable not only to in-situ treatment of existing waste without excavation or removal, but also to stabilization pretreatment for ex-situ treatment of existing waste after excavation and removal.

[0005] The technical solution of the present invention is as follows:

[0006] This invention first provides a method for the remediation of landfills, comprising the following steps:

[0007] A well network is arranged on the landfill. Based on at least one of the following parameters of the landfill waste: biodegradability and organic matter content of the landfill waste, composition and content of landfill gas, composition and content of leachate, composition and content of soil and groundwater, and a three-dimensional model of the landfill, a well network including multiple remediation wells and multiple extraction wells is rationally arranged on the landfill. The remediation wells and extraction wells are used in pairs. The remediation wells are used to provide the aeration, water supply and nutrients required for the degradation of landfill waste, and serve as sampling ports for groundwater quality samples. The extraction wells are used as extraction channels for leachate and landfill gas, and can also be selectively used as channels for injecting agents to remediate soil and groundwater and for replenishing water and nutrients.

[0008] An aerobic aeration, liquid phase, and gas phase extraction system is established, connected to the remediation well and the extraction well. The aerobic aeration, liquid phase, and gas phase extraction system includes a blower, a moisture and nutrient preparation device, a landfill gas extraction device, and a leachate extraction device. The blower is connected to the remediation well and has an inlet connected to the moisture and nutrient preparation device. The landfill gas extraction device and the leachate extraction device are connected to the extraction well.

[0009] Develop and implement a remediation plan for the landfill; formulate a remediation plan based on the parameters and corresponding indicators of the landfill waste, and then treat the landfill using the aerobic aeration, liquid phase, and gas phase extraction system according to the remediation plan; specifically, this includes: using the blower to aerate the landfill waste layer through the remediation well; using the landfill gas extraction device to extract landfill gas from the landfill waste layer through the extraction well; using the leachate extraction device to extract leachate from the landfill waste layer through the extraction well; activating the water and nutrient preparation equipment connected to the remediation well and sending it into the landfill waste layer through the blower until the landfill waste degrades to meet national standards.

[0010] Optionally, the process of developing and implementing a remediation plan for the landfill also includes:

[0011] After the landfill waste in the landfill has degraded to the national standard and the leachate has been extracted, the composition and content of the soil and groundwater are tested to determine whether they meet the national standard. If they do not meet the standard, the necessary remediation agents are injected through the extraction well. The agents react with the soil and groundwater through the migration of groundwater. Groundwater at different depths is periodically sampled, and the testing, judgment, and injection are repeated until the composition and content of the soil and groundwater meet the national standard.

[0012] Optionally, the process of arranging the well cluster on the landfill may further include the following steps:

[0013] Landfill site survey; obtaining at least one of the following parameters of landfill waste by drilling and sampling at the landfill site: biodegradability and organic matter content of landfill waste, composition and content of landfill gas, composition and content of leachate or composition and content of soil and groundwater; detecting or calculating at least one of the following values ​​of landfill site: thickness of topsoil covering the waste, thickness of landfill waste layer or leachate depth, and constructing a three-dimensional model of the landfill site based on the values.

[0014] Optionally, after formulating and implementing the remediation plan for the landfill, the process further includes:

[0015] Post-construction operation and monitoring: After the landfill waste has degraded and stabilized to meet national standards, if excavation and removal are not carried out for on-site remediation, the remediation well will be used as a groundwater monitoring and sampling channel, and the extraction well will be used as a landfill gas monitoring channel. The status of the landfill waste will be monitored in the long term based on the parameters and indicators of the landfill gas and the groundwater. If the parameters exceed the standards, at least one of the following will be restarted for remediation: aerobic aeration, leachate extraction, or injection of soil and groundwater remediation agents.

[0016] Optionally, the arrangement of well clusters on the landfill specifically includes:

[0017] The remediation wells and extraction wells are arranged at polygonal grid intervals. The positions of each remediation well and extraction well can be adjusted according to the degradation degree of landfill waste and the actual site conditions. The depth of the remediation well is greater than the depth of the extraction well. The bottom of the remediation well extends into the groundwater and is more than 1m away from the bottom of the landfill waste layer. The well wall is made of perforated steel pipe or PVC pipe with a diameter of 10-50cm. The bottom of the extraction well is flush with the bottom of the landfill waste layer. The well wall is made of perforated PVC pipe with a diameter of 10-50cm.

[0018] Optionally, the aerobic aeration, liquid-phase, and gas-phase extraction system connected to the repair well and the extraction well specifically includes:

[0019] The aeration equipment includes an aeration blower and an aeration pipe, the aeration pipe being installed inside the remediation well. The aeration equipment is used to aerate the landfill layer through the aeration pipe, and excess aeration gas and degradation gas are extracted by a landfill gas extraction device and discharged after purification treatment to meet standards. The landfill gas extraction device includes a purification box composed of adsorption material, an extraction blower, and a landfill gas extraction pipe, the landfill gas extraction pipe being installed inside the extraction well. The leachate extraction device includes a leachate extraction pump. The system includes a leachate extraction pipe connected to a leachate extraction pump and leachate treatment equipment. The leachate extraction pipe is located inside the extraction well. The leachate extracted by the leachate extraction pump enters the leachate treatment equipment for treatment. The leachate treatment equipment includes an equalization tank and water treatment equipment. The water and nutrient solution mixing equipment includes a water and nutrient solution mixing tank, which is connected to the blower equipment. The remediation well is also equipped with a groundwater sampling pump and a groundwater sampling conduit.

[0020] Optionally, the formulation and implementation of the landfill remediation plan specifically includes:

[0021] Analyze the proportion of methane in the landfill gas, and adjust the frequency and volume of aerobic aeration in the blower according to the proportion of methane.

[0022] The aerobic degradation progress of landfill waste is determined based on the methane ratio change pattern. When the preset degradation progress is reached, the moisture and nutrient mixing equipment is activated. The aeration generated by the blower equipment sends the moisture and nutrients into the landfill waste layer to accelerate aerobic degradation.

[0023] Start the leachate extraction pump to extract the leachate. The extraction rate should match the rate of leachate produced by aerobic degradation to avoid extracting groundwater, thereby increasing the amount of leachate that can be treated.

[0024] Based on the content of characteristic gases in the landfill gas and in accordance with the requirements of the aerobic microbial environment, the landfill gas extraction equipment is started in a timely manner. After the biodegradability of landfill waste, methane content, and landfill settling degree meet the requirements of national standards, the landfill gas extraction equipment is stopped. At this time, the leachate extraction equipment continues to work until all the leachate is extracted and then the leachate extraction equipment is stopped.

[0025] Based on the sampling and analysis results of soil and groundwater, when remediation is required, the soil and groundwater remediation agent is injected into the soil and groundwater through the leachate extraction pipe.

[0026] Another embodiment of the present invention provides a landfill remediation system, the in-situ remediation system including a plurality of remediation wells and a plurality of extraction wells installed on the landfill, the remediation wells and the extraction wells being used in pairs, and an aerobic aeration, liquid phase and gas phase extraction system connected to the remediation wells and the extraction wells;

[0027] The aerobic aeration, liquid phase and gas phase extraction system includes a blower, a moisture and nutrient preparation device, a landfill gas extraction device, and a leachate extraction device. The blower is connected to the remediation well and is equipped with an inlet connected to the moisture and nutrient preparation device. The landfill gas extraction device and the leachate extraction device are connected to the extraction well.

[0028] The blower is used to supply air into the landfill layer in the landfill, so that the landfill layer can achieve aerobic degradation.

[0029] The landfill gas extraction device is used to extract landfill gas from the landfill waste layer.

[0030] The leachate extraction device is used to extract leachate from the landfill layer.

[0031] Optionally, the aeration equipment includes an aeration blower and an aeration pipe connected to each other, the aeration pipe being installed inside the remediation well; the landfill gas extraction equipment includes a purification box composed of adsorbent material, an extraction blower, and a landfill gas extraction pipe connected to each other, the landfill gas extraction pipe being installed inside the extraction well; the leachate extraction equipment includes a leachate extraction pump, a leachate extraction pipe, and a leachate treatment device connected to each other, the leachate extraction pipe being installed inside the extraction well, the leachate extracted by the leachate extraction pump entering the leachate treatment device for treatment, the leachate treatment device including an equalization tank and water treatment equipment; the moisture and nutrient solution mixing equipment includes a moisture and nutrient solution mixing tank, the moisture and nutrient solution mixing tank being connected to the aeration equipment; a groundwater sampling pump and a groundwater sampling conduit are also installed on the remediation well.

[0032] Optionally, the remediation wells and the extraction wells are arranged in pairs according to a polygonal grid, and the positions of each remediation well and the extraction well can be adjusted according to the degradation degree of landfill waste and the actual site conditions; the bottom of the remediation well extends into the groundwater, more than 1m away from the bottom of the landfill waste layer, and the well wall is made of perforated steel pipe or PVC pipe with a diameter of 10-50cm; the bottom of the extraction well is flush with the bottom of the landfill waste layer, and the well wall is made of perforated PVC pipe with a diameter of 10-50cm.

[0033] The advantages of this invention over the prior art are:

[0034] During the landfill treatment process, aeration equipment was used to achieve aerobic treatment of landfill waste, thereby accelerating the degradation of existing waste; landfill gas and leachate in the landfill were extracted and treated to further purify the landfill waste; and soil and groundwater were sampled, tested, and treated with chemicals to prevent landfill waste from polluting the soil and groundwater, thus achieving comprehensive treatment of the landfill.

[0035] Furthermore, the above-mentioned technical solutions of the present invention are not only applicable to in-situ remediation of existing waste without excavation or removal, but also to stabilization pretreatment for ex-situ remediation of existing waste after excavation and removal. They have strong applicability and have achieved significant beneficial effects and overall benefits. Attached Figure Description

[0036] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0037] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0038] Figure 1 This is a schematic flowchart of a landfill remediation method according to one embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure of a landfill remediation system according to one embodiment of the present invention.

[0040] Symbols in the diagram: 1. Landfill site plan; 2. Groundwater level; 3. Overlying soil layer; 4. Landfill layer; 5. Landfill layer soaked in groundwater (leachate layer); 6. Groundwater layer; 7. Remediation well; 8. Extraction well; 9. Leachate treatment equipment; 10. Leachate extraction pump; 11. Landfill gas extraction equipment; 12. Aeration blower; 13. Water and nutrient solution mixing tank; 14. Groundwater sampling pump; 15. Groundwater sampling conduit; 16. Aeration pipe; 17. Landfill gas extraction pipe; 18. Leachate extraction pipe. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0042] It should be understood that the terms "comprising / including," "consisting of," or any other variations are intended to cover non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements includes not only those elements but may also include, where necessary, other elements not expressly listed, or elements inherent to such a product, apparatus, process, or method. Without further limitation, an element defined by the phrases "comprising / including," "consisting of," does not exclude the presence of additional identical elements in the product, apparatus, process, or method that includes said element.

[0043] It should also be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device, component or structure referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of the present invention.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] The technical concept of this invention includes: addressing the problems in the background art, the embodiments of this invention employ the in-situ construction of remediation wells and extraction wells at landfills to aerate the landfill interior, add air, moisture, and nutrients to promote the degradation of existing waste, and centrally collect, treat, and utilize the gases generated during degradation; determine the degree of degradation of existing waste based on the degradation gas component indicators, extract leachate through the extraction well channels and selectively reinject it, and enhance the treatment effect through the synergistic degradation effect of microorganisms and aerobic processes in the leachate; sample and evaluate the bottom soil and groundwater of the landfill, and inject remediation agents through the remediation wells or extraction wells to remediate the soil and groundwater in situ. The above processes work together synergistically to achieve comprehensive treatment of landfills.

[0046] according to Figure 1As shown, one embodiment of the present invention provides a method for the treatment of landfills, comprising the following steps:

[0047] Step 1: Arrange a well group on the landfill. Based on at least one of the following parameters of the landfill waste: biodegradability and organic matter content of the landfill waste, composition and content of landfill gas, composition and content of leachate, composition and content of soil and groundwater, and a three-dimensional model of the landfill, arrange a well group including multiple remediation wells 7 and multiple extraction wells 8 on the landfill. The remediation wells 7 and extraction wells 8 are used in pairs. The remediation wells 7 are used to provide the aeration gas, moisture and nutrients required for the degradation of landfill waste, and serve as sampling ports for groundwater quality samples. The extraction wells 8 are used as extraction channels for leachate and landfill gas, and can also be selectively used as channels for injecting agents to remediate soil and groundwater, and channels for replenishing moisture and nutrients.

[0048] Step 2: Establish an aerobic aeration, liquid phase, and gas phase extraction system connected to the remediation well and the extraction well; the aerobic aeration, liquid phase, and gas phase extraction system includes a blower, a moisture and nutrient preparation device, a landfill gas extraction device, and a leachate extraction device, wherein the blower is connected to the remediation well 7, and the blower is equipped with an inlet connected to the moisture and nutrient preparation device; the landfill gas extraction device and the leachate extraction device are connected to the extraction well 8.

[0049] Step 3: Develop and implement a remediation plan for the landfill. Based on the parameters and relevant indicators of the landfill waste, develop a remediation plan, and then treat the landfill using the aerobic aeration, liquid-phase, and gas-phase extraction system. Specifically, this includes: using the blower to aerate the landfill waste layer 4 through the remediation well 7; using the landfill gas extraction device to extract landfill gas from the landfill waste layer through the extraction well; and using the leachate extraction device to extract leachate from the landfill waste layer through the extraction well. Activate the water and nutrient supply equipment connected to the remediation well and introduce it into the landfill waste layer through the blower until the landfill waste degrades to meet national standards. These national standards include the "Technical Requirements for the Utilization of Stabilized Sites of Municipal Solid Waste Landfills," but stricter emission or remediation standards can also be implemented to achieve better environmental protection.

[0050] The above embodiments, by setting up repair wells, extraction wells, and supporting aerobic aeration, liquid phase, and gas phase extraction systems, with each device in the aerobic aeration, liquid phase, and gas phase extraction systems working together synergistically, not only achieve the detection of landfill waste, but also the comprehensive treatment of landfill waste. Moreover, it is applicable not only to in-situ treatment but also to ex-situ treatment, with a wide range of application scenarios, thus achieving significant beneficial effects and overall benefits.

[0051] Furthermore, step 3 also includes:

[0052] After the landfill waste in the landfill has degraded to the national standard and the leachate has been extracted, the composition and content of the soil and groundwater are tested to determine whether they meet the national standard. If they do not, the necessary remediation agents are injected through the extraction well 8. Through the migration and movement of groundwater, the agents come into contact with and react with the soil and groundwater. Groundwater at different depths is periodically sampled, and repeated testing, judgment, and injection are performed until the composition and content of the soil and groundwater meet the national standard. That is, step 3 also includes the treatment process for soil and groundwater.

[0053] In one or more specific implementations, the following steps are included before step 1:

[0054] Step 0, Landfill Survey; This involves drilling and sampling at the landfill to obtain at least one of the following parameters of the landfill waste: biodegradability and organic matter content, landfill gas composition and content, leachate composition and content, or soil and groundwater composition and content; detecting or calculating at least one of the following values ​​for the landfill: topsoil thickness, landfill waste layer thickness, or leachate depth; and constructing a three-dimensional model of the landfill based on these values. Of course, the parameters and values ​​described above are not limited to the examples above; the measurement or acquisition of other relevant parameters and values ​​is within the scope of this embodiment.

[0055] By sampling, statistics, and testing, we can accurately obtain various parameters and three-dimensional models of landfills. Obtaining relevant parameters, indicators, and three-dimensional models of landfill waste is essential for better layout of well clusters and for developing more suitable treatment plans that take into account the overall benefits.

[0056] In one implementation, step 3 is followed by:

[0057] Step 4, Post-construction Operation and Monitoring: After the landfill waste has degraded and stabilized to meet national standards, if excavation and removal are not carried out for on-site remediation, the remediation well 7 will be used as a groundwater monitoring and sampling channel, and the extraction well 8 will be used as a landfill gas monitoring channel. The status of the landfill waste will be monitored long-term based on the parameters and indicators of the landfill gas and the groundwater. If the parameters exceed the standards, at least one of the following will be restarted for remediation: aerobic aeration, leachate extraction, or soil and groundwater remediation agent injection.

[0058] Post-treatment operation and monitoring are also crucial aspects of landfill remediation, ensuring the integrity of the remediation process and making it truly effective.

[0059] Specifically, step 1 includes:

[0060] The remediation wells 7 and the extraction wells 8 are arranged at polygonal grid intervals, for example, the grid can be composed of 20×20m squares. The positions of each remediation well and extraction well can be adjusted according to the degradation degree of landfill waste and the actual site conditions. The depth of the remediation well is greater than the depth of the extraction well. The bottom of the remediation well extends into the groundwater and is more than 1m away from the bottom of the landfill waste layer 4, preferably more than 2m. The well wall is made of perforated steel pipe or PVC pipe, and the diameter of the perforated steel pipe or PVC pipe is preferably 10-50cm. The bottom of the extraction well is flush with the bottom of the landfill waste layer. The well wall is made of perforated PVC pipe, and the diameter of the PVC pipe is preferably 10-50cm, but other numerical ranges are also possible.

[0061] The depth of the repair well and the extraction well can be selected according to the actual conditions of the landfill, and other corrosion-resistant and high-strength materials can be selected for the well wall pipes. No specific restrictions are made here.

[0062] Specifically, the aerobic aeration, liquid phase, and gas phase extraction system in step 2 can be configured as follows:

[0063] The aeration equipment includes an aeration blower 12 and an aeration pipe 16, which is installed in the remediation well 7. The aeration equipment is used to aerate the landfill layer through the aeration pipe, and excess aeration gas and degradation gas are extracted by the landfill gas extraction equipment and discharged after purification treatment to meet standards. The landfill gas extraction equipment 11 includes a purification box composed of adsorbent material, an extraction blower, and a landfill gas extraction pipe 17, which is partially installed in the extraction well 8. The leachate extraction equipment includes a leachate extraction pump 10 and a leachate extraction device connected to the leachate extraction pump. The system includes a leachate extraction pipe 18 and a leachate treatment device 9. The leachate extraction pipe 18 is installed inside the extraction well 8. The leachate extracted by the leachate extraction pump 10 enters the leachate treatment device 9 for treatment. The leachate treatment device 9 includes an equalization tank and water treatment equipment (not shown in the figure). The water and nutrient solution mixing equipment includes a water and nutrient solution mixing tank 13, which is connected to the blower. The remediation well 7 is also equipped with a groundwater sampling pump 14 and a groundwater sampling conduit 15 for sampling groundwater for testing and analysis. The groundwater sampling pump is preferably a peristaltic pump to ensure sampling.

[0064] Of course, in order to achieve sampling and testing, landfill gas, leachate, soil and groundwater sampling probes can be installed in the repair well or extraction well as needed.

[0065] In one embodiment, step 3 specifically includes the following process:

[0066] Analyze the proportion of methane in the landfill gas, and adjust the frequency and volume of aerobic aeration in the blower according to the proportion of methane.

[0067] The aerobic degradation progress of landfill waste is determined based on the methane ratio change pattern. When the preset degradation progress is reached, the moisture and nutrient mixing equipment is activated. The aeration generated by the blower equipment sends the moisture and nutrients into the landfill waste layer to accelerate aerobic degradation.

[0068] Start the leachate extraction pump 10 to extract the leachate. The extraction rate is matched with the leachate rate generated by aerobic degradation to avoid extracting groundwater, thereby increasing the amount of leachate that can be treated.

[0069] Based on the content of characteristic gases in the landfill gas and in accordance with the requirements of the aerobic microbial environment, the landfill gas extraction equipment 11 is started in a timely manner. After the biodegradability of landfill waste, methane content, and landfill settling degree meet the requirements of national standards, the landfill gas extraction equipment 11 is stopped. At this time, the leachate extraction equipment continues to work until all the leachate is extracted and then the leachate extraction equipment is stopped.

[0070] Based on the sampling and analysis results of soil and groundwater, when remediation is required, the soil and groundwater remediation agent is injected into the soil and groundwater through the leachate extraction pipe 18.

[0071] See Figure 2 Another embodiment of the present invention provides a landfill remediation system, the in-situ remediation system including a plurality of remediation wells 7 and a plurality of extraction wells 8 disposed on the landfill, the remediation wells 7 and the extraction wells 8 being used in pairs, and an aerobic aeration, liquid phase and gas phase extraction system connected to the remediation wells and the extraction wells.

[0072] The aerobic aeration, liquid phase and gas phase extraction system includes a blower, a moisture and nutrient preparation device, a landfill gas extraction device 11, and a leachate extraction device. The blower is connected to the remediation well 7, and the blower is equipped with an inlet connected to the moisture and nutrient preparation device. The landfill gas extraction device 11 and the leachate extraction device are connected to the extraction well 8.

[0073] The blower is used to supply air into the landfill layer in the landfill, enabling aerobic degradation of the landfill layer; the landfill gas extraction device is used to extract the landfill gas from the landfill layer; the leachate extraction device is used to extract the leachate from the landfill layer.

[0074] The aforementioned system, through the installation of repair wells, extraction wells, and supporting aerobic aeration, liquid phase, and gas phase extraction systems, with each piece of equipment within these systems working together synergistically, not only enables the detection of landfill waste but also achieves comprehensive treatment of landfill waste. Furthermore, it is applicable not only to in-situ treatment but also to ex-situ treatment, with a wide range of application scenarios, thus achieving significant beneficial effects and overall benefits.

[0075] In one specific embodiment, the aeration equipment includes an aeration blower 12 and an aeration pipe 16 connected to each other, the aeration pipe 16 being disposed within the remediation well 7; the landfill gas extraction equipment 11 includes a purification box composed of adsorbent material, an extraction blower, and a landfill gas extraction pipe 17 connected to each other, the landfill gas extraction pipe 17 being disposed within the extraction well 8; the leachate extraction equipment includes a leachate extraction pump 10, a leachate extraction pipe 18, and a leachate treatment device 9 connected to each other, the leachate extraction pipe 18 being disposed within the extraction well 8, the leachate extracted by the leachate extraction pump 10 entering the leachate treatment device 9 for treatment, the leachate treatment device 9 including an equalization tank and water treatment equipment; the moisture and nutrient solution mixing equipment includes a moisture and nutrient solution compounding tank 13, the moisture and nutrient solution compounding tank 13 being connected to the aeration equipment; a groundwater sampling pump 14 and a groundwater sampling conduit 15 are also provided on the remediation well.

[0076] In one specific embodiment, the remediation wells and the extraction wells are arranged in pairs according to a polygonal grid, such as a 20×20m grid, and the positions of each remediation well and the extraction well can be adjusted according to the degradation degree of landfill waste and the actual site conditions; the bottom of the remediation well 7 extends into the groundwater, more than 1m away from the bottom of the landfill waste layer 4, and the well wall is made of perforated steel pipe or PVC pipe, the diameter of the perforated steel pipe or PVC pipe is preferably 10-50cm; the bottom of the extraction well 8 is flush with the bottom of the landfill waste layer 4, and the well wall is made of perforated PVC pipe, the diameter of the PVC pipe is preferably 10-50cm.

[0077] The following is a specific embodiment to illustrate the landfill management method and system disclosed in this invention.

[0078] Example

[0079] An informal landfill is located on a riverbank in the urban-rural fringe of a provincial capital. The geological conditions are mainly sand and gravel, with a depth of over 30 meters. No anti-seepage measures were taken when it was first filled in. According to relevant requirements, in-situ remediation is required. Based on the method of this invention, the remediation technical solution and steps are as follows.

[0080] (1) Landfill survey. Through sampling, statistics and tests, the three-dimensional structure of the irregular landfill layer was accurately determined as follows: the average thickness of the top layer of landfill soil is 1 meter, the landfill depth is 3-5 meters, the landfill gas contains methane, hydrogen sulfide and other components, the bottom layer of landfill soil is about 1 meter thick and soaked in groundwater. The investigation found that the biodegradability of the landfill waste is greater than 20%, the groundwater indicators of the landfill soil far exceed the leachate discharge standards, and it belongs to landfill leachate. The chemical oxygen demand, ammonia nitrogen and other indicators of the bottom layer groundwater exceed the relevant groundwater quality standards. A three-dimensional model of landfill soil-landfill waste-leachate was established.

[0081] (2) In-situ treatment and well placement. For example... Figure 2As shown, the remediation well 7 and the extraction well 8 are set at a grid interval of 20 meters × 20 meters, and their positions can be finely adjusted according to the degradation degree of landfill waste and the actual site conditions. The remediation well 7 is 6-8 meters deep and about 15 centimeters in diameter. It passes through the top soil layer 3 of the landfill waste and ensures that it penetrates the landfill waste layer 4 by more than 2 meters. The well wall can be made of perforated steel pipe or PVC pipe. The plastic aeration pipe 16 is connected to the well hole of the landfill layer to aerate the landfill waste layer 4. A water sampling probe is set at the bottom of the well, and groundwater samples are collected through the groundwater sampling pipe 15. The extraction well 8 is 4-6 meters deep and about 15 centimeters in diameter. The depth is level with the bottom of the permeable landfill layer 4. The well wall is protected by perforated PVC pipe. The well has an internal landfill gas extraction pipe 17. The gas collection probe is located in the landfill layer 4 and is above the groundwater level 2. The leachate extraction pipe 18 is located in the groundwater-soaked landfill layer (leachate layer) 5. Groundwater is collected through the water sampling probe. After all the leachate is extracted, the leachate extraction pipe 18 can also be used as a channel for adding remediation agents during soil and groundwater remediation.

[0082] (3) Aerobic aeration and liquid / gas phase extraction system. The aeration device of the remediation well inputs air into the landfill layer 4 through the aeration blower 12, and at the same time adds water and nutrient solution to the air through the water and nutrient solution compounding tank 13; the groundwater sampling pump 14 is connected to the groundwater sampling conduit 15, and a peristaltic pump is generally used to sample the groundwater; the landfill gas extraction equipment 11 mainly includes a purification box composed of adsorption materials such as activated carbon and an extraction blower; the leachate extraction pump 10 is connected to the leachate extraction pipe 18 to extract the leachate, and the extracted leachate enters the leachate treatment equipment 9 for treatment, which includes a regulating tank, water treatment equipment, etc.

[0083] (4) Develop a treatment plan and implement in-situ treatment. After the aerobic aeration and liquid / gas phase extraction system is completed, start the aeration blower 12 to aerate the landfill layer 4. Excess aeration gas and degradation gas are purified and discharged through the landfill gas extraction equipment 11 to meet standards. Analyze the methane content ratio in the landfill gas to adjust the aeration frequency and air volume. Determine the aerobic degradation progress of the landfill waste based on its changing pattern. Start the water and nutrient solution mixing tank 13 in a timely manner to add aeration gas to the landfill layer 4 to accelerate aerobic degradation. At the same time, start the leachate extraction pump 10 to extract the original leachate. It is also necessary to match the aerobic degradation with aeration. The increased leachate extraction rate prevents groundwater contamination and reduces the amount of leachate that needs to be treated. The landfill gas extraction device 11, based on the content of characteristic gases such as methane in the landfill gas and the microbial environment requirements of the aerobic system, activates the exhaust fan in a timely manner. Once the biodegradability, methane content, and settling density of the landfill waste meet the relevant requirements of the national standard "Technical Requirements for the Utilization of Stabilized Sites in Municipal Solid Waste Landfills," the aerobic aeration system is stopped. After the aerobic aeration ends, leachate extraction continues for a period of time after the aerobic aeration ends to ensure complete extraction of leachate.

[0084] (5) Post-construction operation and monitoring. After the aerobic aeration degradation of landfill waste reaches a stable standard, groundwater samples are collected periodically through the groundwater sampling pipe 15 and the groundwater sampling pump 14 to determine whether the groundwater exceeds the standard. Combined with the analysis of landfill gas collected through the landfill gas extraction pipe 17, the degradation status of landfill waste after the aeration is stopped and whether it continues to pollute the groundwater. If there is incomplete degradation or rebound pollution of groundwater, the aerobic aeration equipment and leachate extraction equipment are restarted to accelerate the degradation of landfill waste and extract the newly degraded leachate to avoid polluting the groundwater. If the relevant indicators of groundwater exceed the standard seriously and the natural decay rate is slow, and the test shows that it exceeds the acceptable value, the remediation agent can be added to the bottom layer of the landfill waste through the leachate extraction pipe 18. Through groundwater migration and combination with the bottom soil and groundwater, in-situ remediation is carried out to the target value. Subsequently, groundwater changes were monitored by sampling through the groundwater sampling pipe 15 in the remediation well 7, and the degradation of landfill waste was monitored through the landfill gas extraction pipe 17 in the extraction well 8. The landfill waste was monitored online. If the risk of any link exceeded the acceptable range, the environmental risks of the informal landfill were repaired and controlled through three process approaches: restarting aerobic aeration, leachate extraction, and injection of soil and groundwater remediation agents.

[0085] Therefore, those skilled in the art should recognize that although exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can still be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A method of remediating a landfill, characterized by: Includes the following steps: A well network is arranged on the landfill. Based on at least one of the following parameters of the landfill waste: biodegradability and organic matter content of the landfill waste, composition and content of landfill gas, composition and content of leachate, composition and content of soil and groundwater, and a three-dimensional model of the landfill, a well network including multiple remediation wells and multiple extraction wells is rationally arranged on the landfill. The remediation wells and extraction wells are used in pairs. The remediation wells are used to provide aeration and replenish water and nutrients required for the degradation of landfill waste, and serve as sampling ports for groundwater quality samples. The extraction wells are used as extraction channels for leachate and landfill gas, as well as channels for injecting agents to remediate soil and groundwater and for replenishing water and nutrients. An aerobic aeration, liquid phase, and gas phase extraction system is established, connected to the remediation well and the extraction well. The aerobic aeration, liquid phase, and gas phase extraction system includes a blower, a moisture and nutrient preparation device, a landfill gas extraction device, and a leachate extraction device. The blower is connected to the remediation well and has an inlet connected to the moisture and nutrient preparation device. The landfill gas extraction device and the leachate extraction device are connected to the extraction well. Develop and implement a remediation plan for the landfill; based on the parameters and corresponding indicators of the landfill waste, develop a remediation plan, and then treat the landfill using the aerobic aeration, liquid phase, and gas phase extraction system according to the remediation plan; specifically including: using the blower to aerate the landfill waste layer through the remediation well; using the landfill gas extraction device to extract landfill gas from the landfill waste layer through the extraction well; using the leachate extraction device to extract leachate from the landfill waste layer through the extraction well; activating the water and nutrient preparation equipment connected to the remediation well and sending it into the landfill waste layer through the blower until the landfill waste degrades to meet the requirements of national standards; The formulation and implementation of the landfill remediation plan also includes: After the landfill waste in the landfill has degraded to the national standard and the leachate has been extracted, the composition and content of the soil and groundwater are tested to determine whether they meet the national standard. If they do not meet the standard, the necessary remediation agents are injected through the extraction well. The agents react with the soil and groundwater through the migration of groundwater. Groundwater at different depths is periodically sampled, and the testing, judgment, and injection are repeated until the composition and content of the soil and groundwater meet the national standard. The process of arranging well clusters on the landfill also includes the following steps: Landfill site survey; obtaining at least one of the following parameters of landfill waste by drilling and sampling at the landfill site: biodegradability and organic matter content of landfill waste, composition and content of landfill gas, composition and content of leachate or composition and content of soil and groundwater; detecting or calculating at least one of the following values ​​of landfill site: thickness of topsoil covering the waste, thickness of landfill waste layer or leachate depth, and constructing a three-dimensional model of the landfill site based on the values; The process of developing and implementing the landfill remediation plan also includes: Post-construction operation and monitoring: After the landfill waste has degraded and stabilized to meet national standards, if excavation and removal are not carried out for on-site remediation, the remediation well will be used as a groundwater monitoring and sampling channel, and the extraction well will be used as a landfill gas monitoring channel. The status of the landfill waste will be monitored in the long term based on the parameters and indicators of the landfill gas and the groundwater. If the parameters exceed the standards, at least one of the following will be restarted for remediation: aerobic aeration, leachate extraction, or injection of soil and groundwater remediation agents.

2. The governance method of claim 1, wherein, The arrangement of well clusters on the landfill specifically includes: The remediation wells and extraction wells are arranged at polygonal grid intervals. The positions of each remediation well and extraction well can be adjusted according to the degradation degree of landfill waste and the actual site conditions. The depth of the remediation well is greater than the depth of the extraction well. The bottom of the remediation well extends into the groundwater and is more than 1m away from the bottom of the landfill waste layer. The well wall is made of perforated steel pipe or PVC pipe with a diameter of 10-50cm. The bottom of the extraction well is flush with the bottom of the landfill waste layer. The well wall is made of perforated PVC pipe with a diameter of 10-50cm.

3. The governance method of claim 2, wherein, The aerobic aeration, liquid phase, and gas phase extraction system connected to the repair well and the extraction well specifically includes: The aeration equipment includes an aeration blower and an aeration pipe. The aeration pipe is installed inside the remediation well. The aeration equipment is used to aerate the landfill layer through the aeration pipe. Excess aeration and degradation gas are extracted by a landfill gas extraction device and discharged after purification treatment to meet standards. The landfill gas extraction device includes a purification box composed of adsorption material, an extraction blower, and a landfill gas extraction pipe. The landfill gas extraction pipe is installed inside the extraction well. The leachate extraction device includes a leachate extraction pump. The system includes a leachate extraction pipe connected to a leachate extraction pump and leachate treatment equipment. The leachate extraction pipe is located inside the extraction well. The leachate extracted by the leachate extraction pump enters the leachate treatment equipment for treatment. The leachate treatment equipment includes an equalization tank and water treatment equipment. The water and nutrient solution mixing equipment includes a water and nutrient solution mixing tank, which is connected to the blower equipment. The remediation well is also equipped with a groundwater sampling pump and a groundwater sampling conduit.

4. The governance method of claim 3, wherein, The formulation and implementation of the landfill remediation plan specifically includes: Analyze the proportion of methane in the landfill gas, and adjust the frequency and volume of aerobic aeration in the blower according to the proportion of methane. The aerobic degradation progress of landfill waste is determined based on the methane ratio change pattern. When the preset degradation progress is reached, the water and nutrient mixing equipment is activated. The aeration generated by the blower equipment sends water and nutrients into the landfill waste layer to accelerate aerobic degradation. Start the leachate extraction pump to extract the leachate. The extraction rate should match the rate of leachate produced by aerobic degradation to avoid extracting groundwater, thereby increasing the amount of leachate that can be treated. Based on the content of characteristic gases in the landfill gas and in accordance with the requirements of the aerobic microbial environment, the landfill gas extraction equipment is started in a timely manner. After the biodegradability of landfill waste, methane content, and landfill settling degree meet the requirements of national standards, the landfill gas extraction equipment is stopped. At this time, the leachate extraction equipment continues to work until all the leachate is extracted and then the leachate extraction equipment is stopped. Based on the sampling and analysis results of soil and groundwater, when remediation is required, the soil and groundwater remediation agent is injected into the soil and groundwater through the leachate extraction pipe.

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