Landfill pit bottom treatment process

Abstract

The invention relates to the technical field of environmental protection engineering, and discloses a landfill pit bottom treatment process which comprises the following steps: preparing for three-dimensional environment modeling, scanning pit bottom sludge by utilizing an intelligent sensing execution subsystem, and generating a three-dimensional digital terrain model; intelligent self-adaptive desilting is conducted, the real-time sludge concentration in the pumping process is collected in real time and compared with the preset target concentration to obtain a control error, and operation parameters of the intelligent sensing execution subsystem are adjusted according to the control error; after residual materials at the pit bottom are cleaned, multi-point sampling is conducted on the pit bottom, and whether the warehouse cleaning work is qualified or not is judged according to the content of organic matter in the sample. According to the invention, through three-dimensional modeling and closed-loop control, precision and efficiency optimization of desilting operation are realized; meanwhile, a quantitative acceptance standard based on the organic matter content is introduced, an objective basis is provided for warehouse cleaning quality, and the problems that a traditional process is low in efficiency and the acceptance standard is subjective are solved.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering technology, and in particular to a landfill pit bottom treatment process. Background Technology

[0002] With urban development and increasingly stringent environmental protection requirements, the closure and remediation of some early-built municipal solid waste landfills has become a necessary step. A key step in this process is the removal and treatment of the long-accumulated mixture of stale waste and leachate at the bottom of the landfills.

[0003] Current reservoir cleaning operations largely rely on surface excavation equipment or simple underwater pumping equipment, making it impossible for operators to accurately determine the sludge accumulation pattern and obstacle distribution in the underwater membrane-covered area. This results in the operation being largely blind or semi-blind, leading to low dredging efficiency and the risk of equipment collisions or damage to the membrane.

[0004] Furthermore, during the pumping dredging process, there is often a lack of real-time monitoring and effective control methods for the sludge concentration of the pumping medium. This makes it difficult for the pumping system to remain stable within the optimal operating range, easily leading to energy waste due to excessively low concentration or pipeline blockage due to excessively high concentration, thus affecting the continuity and economy of the overall operation.

[0005] In the final acceptance stage of the cleanup work, current practices often rely on experience-based visual judgment, lacking objective and quantitative evaluation standards. This makes it difficult to guarantee the quality of cleanup, which may lead to pollutant residues and leave hidden dangers for the subsequent safe use of the site. Summary of the Invention

[0006] The purpose of this invention is to provide a landfill pit bottom treatment process that solves the problems of existing landfill cleaning processes that rely heavily on manual experience, resulting in low work efficiency, difficulty in accurately controlling the dredging process, high environmental safety risks, unstable dredging quality, and subjective acceptance standards.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A landfill pit bottom treatment process includes the following steps:

[0009] S100: Preparation and 3D Environment Modeling. Before the dredging operation begins, an intelligent sensing and execution subsystem deployed below the liquid surface of the landfill to be treated is used to perform an environmental scan. The intelligent sensing and execution subsystem is equipped with a multi-beam sonar detector, which moves along a preset gridded path to collect elevation data of the bottom of the pit and generates a 3D digital terrain model of the sludge at the bottom of the pit based on the data.

[0010] S200: Intelligent Adaptive Dredging. The intelligent sensing and execution subsystem travels along the planned path and pumps and cleans the sludge at the bottom of the pit using its onboard dredging execution module. In this step, a sludge concentration sensor installed on the pumping pipeline collects real-time sludge concentration data during the pumping process and compares this real-time sludge concentration with a preset target concentration to obtain the control error. Based on this control error, the system dynamically adjusts the operating parameters of the intelligent sensing and execution subsystem to achieve stable and optimized dredging efficiency.

[0011] S300: Final Cleaning and Acceptance. After completing the main dredging operations, the HDPE film is removed, and the remaining sludge and solid waste at the bottom of the pit are cleaned up in conjunction with the cleaning. After the cleaning work is completed, multiple points are sampled from the cleaned bottom of the pit. The organic matter content in the samples is tested to quantitatively assess the completion of the cleaning work, and the cleaning work is judged as qualified based on the test results.

[0012] In one specific implementation, after generating the three-dimensional digital terrain model, step S100 further includes analyzing the model to plan a dredging path. Specifically, the system analyzes the terrain gradient data in the three-dimensional digital terrain model to identify areas with abnormal terrain slopes and marks them as suspected obstacle areas. Subsequently, using the A* algorithm, with the three-dimensional digital terrain model as a map, a global dredging path is planned from the starting point to the target point, avoiding all identified suspected obstacle areas. This path is then sent to the control system to guide the intelligent perception and execution subsystem to perform the dredging operation.

[0013] In one specific implementation, the adjustment of the operating parameters based on the control error in step S200 is achieved through a PID control algorithm. This algorithm uses the difference between the real-time sludge concentration and the target concentration, i.e., the control error, as the control error. As input, an adjustment instruction is calculated and generated. This instruction is used to adjust one or more operational parameters. These parameters may include the traction speed of the intelligent sensing and execution subsystem, the rotational speed of its mounted cutterhead, and the high-pressure water flow rate for auxiliary dredging. The control relationship can be expressed by the following formula:

[0014] ;

[0015] in: In order to be in Adjustment instructions generated in real time; In order to be in Timing control error, ,in For the target concentration, Real-time sludge concentration; is the proportionality coefficient; is the integral coefficient; is the differential coefficient.

[0016] In a specific embodiment, to ensure environmental safety during the operation, the process further includes dynamic maintenance of the HDPE film. During the execution of step S200, the cumulative decrease value of the mud level in the reservoir is continuously monitored through the water level gauge in the reservoir area. When the cumulative decrease value reaches a preset maintenance threshold (such as half of the film lap width), the dredging operation is suspended, and the circumferential elongation operation of the HDPE film is performed to compensate for the change in film tension caused by the decrease in mud level. At the same time, the automatic submersible pump arranged on the surface of the HDPE film is used to drain the accumulated water on the film due to reasons such as rainfall. The automatic submersible pump is内置 with a liquid level sensor, and when the detected water depth exceeds the preset safety depth value, the drainage is automatically started to prevent the film from being damaged due to excessive local pressure.

[0017] In a specific embodiment, before uncovering the film in step S300, it includes a step of treating the gas under the film. The forced replacement of the gas under the HDPE film is carried out through a fan in the enclosed space under the HDPE film, and the original high-concentration odor gas and potential combustible gas are抽出 and导入 into a mobile odor scrubbing tower for treatment until the gas concentration drops below the safety standard. Subsequently, the HDPE film is uncovered in a step-by-step and zoned manner, and a deodorizing fog cannon is started to blow air at the upwind edge of the film uncovering operation area to form an air curtain to dilute and replace the residual gas dissipated due to disturbance.

[0018] In a specific embodiment, for the step of cleaning the residual materials at the bottom of the pit, a long-arm excavator with a flexible scraper is used in cooperation with a high-pressure water gun for operation, and the residual sludge and solid waste in areas such as the corners and toe slopes at the bottom of the pit are冲洗,汇集 and集中挖除.

[0019] In a specific embodiment, the quantitative acceptance step is specifically: sampling points are arranged at the bottom of the pit after cleaning by using the seven-point sampling method. The sampling points include the four corner points, the center point, and the midpoints of the two diagonals at the bottom of the pit. The collected samples are sent for inspection. When the detection results of the organic matter content of the samples at all seven sampling points are not higher than the preset acceptance threshold (such as 5%), it is determined that the reservoir cleaning work is qualified.

[0020] In summary, the present invention includes at least one of the following beneficial technical effects:

[0021] 1. This invention automates and refines dredging operations by constructing a three-dimensional digital terrain model of the pit bottom before dredging and using this model to identify obstacles and plan the overall dredging path. This avoids the risks of blind operation and equipment collisions caused by unclear underwater conditions in traditional processes, thus improving operational efficiency and safety.

[0022] 2. This invention introduces closed-loop feedback control based on real-time sludge concentration during the dredging process. The system dynamically adjusts operating parameters according to the deviation between the concentration and the target value, ensuring that the pumping system can continuously operate within the high-efficiency range. This not only avoids pipe blockage caused by excessively high concentration or ineffective pumping caused by excessively low concentration, but also effectively reduces the energy consumption per unit volume of dredging.

[0023] 3. In the final acceptance stage, this invention employs a seven-point sampling method and uses organic matter content as a quantitative acceptance indicator, providing an objective and repeatable basis for judging the completion of the warehouse cleaning work. This overcomes the subjectivity and uncertainty brought about by traditional methods that rely on visual inspection or experience-based judgment, ensuring that the final warehouse cleaning quality meets the preset standards and laying a reliable foundation for subsequent site utilization. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the overall workflow of the present invention;

[0025] Figure 2 This is a detailed flowchart of the intelligent adaptive dredging stage in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the scanning operation of the intelligent perception and execution subsystem for three-dimensional environment modeling in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of a three-dimensional digital terrain model generated based on scanning data in an embodiment of the present invention.

[0028] Among them, 100 is the intelligent sensing and execution subsystem; 110 is the dredging execution module; 120 is the multi-dimensional sensing module; 130 is the underwater precise positioning module; 200 is the shore-based collaborative control subsystem; 210 is the cable traction module; 220 is the central data processing and decision-making module; 300 is the environmental safety assurance subsystem; 310 is the membrane dynamic maintenance module; and 320 is the gas safety control module. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 -Appendix Figure 4 The present invention will be further described in detail below.

[0030] This invention provides a landfill pit bottom treatment process, such as... Figure 1As shown, the landfill pit bottom treatment process includes the following steps:

[0031] S111, Gas Safety Testing: At the selected opening location, gas samples are taken from the enclosed space beneath the HDPE membrane by installing a temporary sampling valve. A portable multi-functional gas detector is used to analyze the concentration of key gases in the sample, including but not limited to methane, hydrogen sulfide, and ammonia. This step aims to confirm that the concentrations of these gases are all below their respective lower explosive limits (LEL) and occupational exposure limits (OEL) to ensure the safety of subsequent opening operations.

[0032] S112, Opening and Synchronous Gas Suppression: After confirming the gas concentration is safe, the membrane-covered opening operation is carried out. In a specific embodiment, this step includes opening a main equipment entrance with a size of approximately 7m × 7m for the subsequent hoisting entry of the intelligent sensing execution subsystem 100; and opening four auxiliary openings with a size of approximately 2m × 2m at the four corners of the landfill pit for the insertion of cables and pipelines of the cable traction module 210. Throughout the opening operation, the gas safety control module 320 in the environmental safety assurance subsystem 300 is continuously operated. Specifically, a deodorizing fog cannon is activated upwind of the opening area to spray a covering spray onto the work area to dilute and degrade any potentially escaping odor. Simultaneously, a layer of deodorizing foaming agent is applied to the liquid surface below the opening area using a foaming machine. This foaming agent forms a dense physical foam layer on the liquid surface to physically block the unorganized escape of dissolved gases from the liquid surface below.

[0033] S113, Equipment hoisting and system connection: After drilling, the intelligent sensing and execution subsystem 100 is smoothly hoisted onto the liquid surface of the landfill pit through the main equipment inlet using onshore lifting equipment. Subsequently, the four traction cables of the cable traction module 210 in the onshore collaborative control subsystem 200 are introduced under the membrane through four auxiliary ports and reliably fixed to the four pre-set connection points on the intelligent sensing and execution subsystem 100. At the same time, the sludge discharge pipeline and high-pressure water inlet pipeline of the dredging execution module 110 are connected to the onshore pump set and water treatment system through auxiliary ports.

[0034] S114, Main Entrance Resealing: After the intelligent sensing and execution subsystem 100 is deployed and connected, the main equipment entrance is immediately resealed to restore the overall airtightness of the landfill pit. This resealing operation uses an HDPE membrane of the same material as the original membrane and employs a dedicated HDPE hot-melt welding machine for hot-melt welding. The welding process, including membrane surface cleaning, grinding, hot-melt welding, and non-destructive testing of the weld seam, is well-known in the field and will not be elaborated further. After this step is completed, the entire system enters standby mode, preparing for subsequent 3D environment modeling.

[0035] After the equipment deployment is completed, the method step S100 of this embodiment of the invention further includes three-dimensional modeling and obstacle identification of the sub-membrane environment, which may specifically include the following sub-steps:

[0036] S121, Full-field scanning and synchronous acquisition of multi-source data: The central data processing and decision-making module 220 in the shore-based collaborative control subsystem 200, along with the control cable traction module 210, pulls the intelligent sensing and execution subsystem 100 at a preset speed, causing it to move along a preset gridded scanning path on the liquid surface below the membrane. During the movement, multiple sensor modules on the intelligent sensing and execution subsystem 100 work synchronously and acquire data. Specifically, the underwater precise positioning module 130 calculates the three-dimensional position and attitude data of the intelligent sensing and execution subsystem 100 in the global coordinate system in real time. At the same time, the multi-beam sonar detector in the multi-dimensional sensing module 120 emits a fan-shaped acoustic beam towards the bottom of the pit and receives the echo signal. The central data processing and decision-making module 220 timestamps each frame of sonar echo data with the position and attitude data at the time of acquisition of that frame, forming a series of multi-source raw data packets containing spatiotemporal information.

[0037] S122, Point Cloud Data Generation: The central data processing and decision-making module 220 processes the received raw data packets to generate three-dimensional point cloud data describing the morphology of the pit bottom. For time... A frame of data was acquired, in which the multibeam sonar's... The two-way propagation time of each beam is The average speed of sound in water is Then the slant range corresponding to that beam The calculation is as follows:

[0038] ;

[0039] in, It can be determined through on-site measurements or empirical values.

[0040] Combined with the emission angle of the beam in the sonar coordinate system and azimuth The coordinates of the detection point in a coordinate system with the sonar as the origin can be obtained. Then, based on the time provided by the underwater precision positioning module 130... Position matrix and attitude matrix The following coordinate transformation formula converts this point to its coordinates in the global coordinate system. :

[0041] ;

[0042] By repeating the above calculations on all sonar beam data along all scanning paths, a raw point cloud dataset containing a large number of discrete three-dimensional coordinate points can be obtained.

[0043] S123, 3D Digital Terrain Model Construction: The central data processing and decision-making module 220 filters the generated raw point cloud dataset to remove obvious noise points and outliers. Subsequently, a spatial interpolation algorithm is used to grid the filtered point cloud data, thereby generating a continuous 3D digital terrain model (DTM). In one embodiment, the spatial interpolation algorithm can be Kriging interpolation or Triangular Irregular Network (TIN) interpolation. The generated DTM is in the form of a two-dimensional array or function. Storage, in For planar coordinates, This coordinate represents the elevation of the pit bottom. The model visually presents the overall accumulation shape and undulations of the sludge at the bottom of the pit.

[0044] S124, Suspected Obstacle Identification and Marking: After generating the DTM, the central data processing and decision-making module 220 further analyzes the model to identify and mark suspected large obstacles that may pose a risk to dredging operations, such as compacted mud clods and construction waste. The identification method is to calculate the local terrain gradient of each grid point on the DTM. For any grid point... Its topographic gradient It can be approximated using the finite difference method:

[0045] ;

[0046] in, and The grid is in and Spacing in the direction.

[0047] The calculated gradient value is compared with a preset gradient threshold. Compare. If If a point is identified as having a sudden change in terrain slope, it is considered to be a suspected obstacle area. All marked areas together form an obstacle distribution map, which will be used as an avoidance constraint in subsequent path planning steps.

[0048] In step S200, after the three-dimensional digital terrain model is constructed, the central data processing and decision-making module 220 in the shore-based collaborative control subsystem 200 performs global dredging path planning based on the model. This step aims to generate one or more movement paths for the intelligent perception and execution subsystem 100 to follow, with the goal of efficient dredging. Its specific implementation may include the following sub-steps:

[0049] S211, Discretization of the workspace: To facilitate path search, the central data processing and decision module 220 first discretizes the continuous three-dimensional digital terrain model. This is converted into a discretized two-dimensional raster map. The raster map consists of multiple cells, each cell... This corresponds to a rectangular area within an actual landfill pit. For each cell, the system assigns a set of attributes, which include at least: the cell's status on the obstacle distribution map (accessible or inaccessible), and the estimated sludge volume within the cell. The sludge volume can be calculated by multiplying the average sludge thickness corresponding to that cell by the cell area.

[0050] S212, Layered Zoning and Target Point Set Generation: According to the zoning and elevation-based dredging strategy of the present invention, the central data processing and decision module 220 analyzes the raster map to achieve layered dredging. This module first identifies the area with the highest sludge elevation in the raster map and designates this area as the current working layer. Subsequently, within this working layer, one or more points with representative elevations are selected as the target point set for the current dredging stage. This strategy ensures priority treatment of the thickest sludge deposits, conforming to the principle of gravity stability.

[0051] S213, Path Search Based on Algorithm A*: After determining the target point of the current operation layer, the central data processing and decision-making module 220 uses a path search algorithm to calculate the optimal path from the current position of the intelligent sensing execution subsystem 100 to the target point. In a specific embodiment, this path search algorithm is Algorithm A*. The A* algorithm uses an evaluation function... To evaluate the quality of nodes on the path, the function is defined as follows:

[0052] ;

[0053] in: This represents a cell node in a raster map; This represents the path from the starting point to the current node. The actual cost of movement. In this embodiment, It can be the geometric length of the path traversed; It is a heuristic function, representing starting from the current node. The estimated travel cost to the target point. In this embodiment, The Manhattan distance or Euclidean distance can be used for calculation.

[0054] During the search process, the A* algorithm avoids all cells marked as impassable in step S211, thus ensuring that the generated path can bypass known large obstacles. Its algorithm implementation is well-known in the field and will not be elaborated upon here.

[0055] S214, Global Path Generation and Output: The central data processing and decision-making module 220 executes steps S212 and S213 iteratively. After the dredging path of one work layer is completed, the system updates the digital terrain model and re-identifies the area with the highest elevation as the new work layer, until the sludge elevation of the entire landfill is below a preset threshold. Connecting all the iteratively generated path segments constitutes a complete global dredging path. The path ultimately becomes a sequence of ordered three-dimensional coordinate points (i.e., waypoints). Stored in the form of, where The path sequence is then passed to the cable traction module 210 as the direct basis for its control of the movement of the intelligent sensing and execution subsystem 100.

[0056] In method step S200 of this embodiment of the invention, when the intelligent sensing execution subsystem 100 moves along the planned global path, the onshore collaborative control subsystem 200 performs real-time adaptive closed-loop control on its operating parameters. This step aims to ensure that the dredging execution module 110 always operates within an efficient and safe working range to cope with local changes in the properties of the sludge at the bottom of the pit. Its specific implementation may include the following sub-steps:

[0057] S221, Real-time acquisition of operation status data: During the dredging operation, the multi-dimensional sensing module 120 of the intelligent sensing execution subsystem 100 uses its integrated online sludge concentration meter to continuously measure the real-time concentration value of the sludge pumped by the dredging execution module 110. The real-time concentration data, along with the timestamp, is sent to the central data processing and decision-making module 220 in the shore-based collaborative control subsystem 200.

[0058] S222, Control Error Calculation: The central data processing and decision-making module 220 has a preset target sludge concentration value. This value falls within an optimal concentration range determined by pumping efficiency and subsequent treatment process requirements. Inside. Module 220 receives real-time concentration values. Then, immediately calculate the control error at the current moment. :

[0059] ;

[0060] This error This reflects the degree and direction of deviation between the actual operational results and the ideal state. If This indicates that the current mud concentration is too low; if This indicates that the current mud concentration is too high.

[0061] S223, Parameter adjustment instruction generation based on PID control algorithm: The central data processing and decision module 220 adopts the proportional-integral-derivative (PID) control algorithm, based on the control error... The adjustment amounts for each operating parameter are calculated. In one specific embodiment, this applies to the traction speed of the cable traction module 210. The cutting speed of the dredging execution module 110 and high-pressure water flow Calculate the control output for each. The control output is based on the traction speed. For example:

[0062] ;

[0063] in: , , These are the proportional, integral, and derivative gain coefficients of the traction speed control loop. These coefficients are preset based on the system debugging results.

[0064] Similarly, the control output for the reamer speed can be calculated. Control output of high-pressure water flow .

[0065] S224, Operation Parameter Update and Execution: The central data processing and decision-making module 220 updates the setpoints of the operation parameters based on the calculated control output and generates corresponding instructions to send to the actuator. The new operation parameter values ​​can be determined in the following ways:

[0066] ;

[0067] ;

[0068] ;

[0069] in: , , These are the foundation traction speed, foundation cutter rotation speed, and foundation high-pressure water flow rate for the current path segment. , , The target setpoint for the next control cycle.

[0070] The control logic here is: when the mud concentration is too low ( The system increases traction speed to quickly pass through the area, while appropriately reducing cutter energy consumption and dilution water volume; when the mud concentration is too high ( The system reduces the traction speed to increase the working time at that position, while increasing the cutter speed and high-pressure water flow to enhance the crushing and dilution effect.

[0071] By continuously repeating steps S221 to S224, the system forms a closed-loop control system with sludge concentration as the feedback quantity, enabling the intelligent sensing and execution subsystem 100 to dynamically adapt to the complex and ever-changing working conditions at the bottom of the pit, thereby maintaining the stability and efficiency of the dredging operation.

[0072] During step S200, to ensure the structural integrity of the HDPE membrane during the descent of the mud level in the storage tank, the membrane dynamic maintenance module 310 of the environmental safety assurance subsystem 300 simultaneously performs dynamic maintenance on the membrane. The implementation of this collaborative process may include the following sub-steps:

[0073] S231, Dredging Depth Monitoring and Maintenance Trigger: The onshore collaborative control subsystem 200 estimates and monitors the cumulative decrease in the average sludge level in the reservoir in real time based on the total amount of pumped sludge and the geometry of the landfill pit. When the cumulative decrease value Reaching a preset maintenance threshold When the distance reaches 2.0 meters (for example), the central data processing and decision-making module 220 sends a trigger signal to the film covering dynamic maintenance module 310 to start the film covering extension operation.

[0074] S232, Circumferential Extension of Covering: Upon receiving a trigger signal, the covering dynamic maintenance module 310 guides on-site personnel to perform circumferential extension of the covering, providing additional descent allowance for the covering. To improve the construction efficiency and welding quality of large-area splicing, this operation adopts a "longitudinal-then-transverse" welding sequence. Specifically, workers first splice multiple pre-cut new HDPE membrane sheets along their length (longitudinal) on the shore into a single long strip membrane. Subsequently, this long strip membrane is treated as a unit and welded in one go along its width (transverse) to the edges of the existing covering to be extended around the landfill pit. This welding process uses a dedicated HDPE hot melt welding machine; the specific welding process parameter settings and operating procedures are well-known technologies in the field and will not be elaborated here.

[0075] S233, Automatic Drainage of Water from the Membrane: To prevent excessive stress on the membrane due to water accumulation (e.g., rainwater), the membrane dynamic maintenance module 310 also performs a drainage operation for the water on the membrane. This step involves placing one or more automatic submersible pumps equipped with level sensors at water collection depressions formed on the HDPE membrane surface due to natural settlement. When the level sensor of any pump detects the water depth at its location... Exceeding the preset safe depth value When the water level drops below a preset stop depth, the pump's control unit activates to pump water out of the site. The pump stops operating when the water depth is lowered below another preset stop depth. This process continues throughout the dredging phase to dynamically maintain the membrane load within a safe range.

[0076] When the onshore collaborative control subsystem 200 determines that the main dredging stage, i.e., step S200, has been completed based on preset conditions, such as the intelligent sensing execution subsystem 100 having completed its entire operation path and the pumped sludge concentration remaining below a set lower threshold, the method enters the final sludge cleaning stage S300. This stage first performs gas replacement and membrane removal operations to ensure the safety and environmental friendliness of subsequent operations. Its specific implementation may include the following sub-steps:

[0077] S311, Forced Gas Replacement and Treatment Under the Membrane: Activate the gas safety control module 320 in the environmental safety assurance subsystem 300. In one specific embodiment, this module includes a mobile odor scrubbing tower. Through flexible piping pre-installed on the HDPE membrane, the scrubbing tower forces ventilation into the enclosed space beneath the membrane. In one embodiment, the scrubbing tower's processing airflow is 15,000 to 20,000 cubic meters per hour. The extracted gas is introduced into the scrubbing tower and treated in a secondary chemical scrubbing tank to remove harmful and odorous components such as hydrogen sulfide and ammonia before being discharged in compliance with standards.

[0078] S312, Gas Safety Compliance Test: After forced ventilation has been maintained for a period of time and the gas concentration at the scrubbing tower outlet has stabilized and met the standards, gas samples are taken from different locations within the storage chamber through multiple detection holes pre-drilled on the membrane. A portable multi-functional gas detector is used to analyze the sample concentration, and the results are compared with the "Emission Standard of Air Pollutants for Municipal Wastewater Treatment Plants" (DB31 / 982-2016) and relevant operational safety procedures. Only after confirming that all gas indicators within the storage chamber meet the requirements can subsequent membrane removal operations proceed.

[0079] S313, Gradual and Sectional Membrane Removal: The membrane removal operation is carried out gradually and in sections to control the range and intensity of gas escape. In one specific embodiment, the operation begins at one end of the landfill pit, using a cutting device to remove strips of membrane covering 5 to 10 meters wide at a time. Simultaneously with the removal of each strip, deodorizing fog cannons are activated at the edge of the work area to deliver air into the exposed space. This airflow further dilutes and displaces any malodorous gases that may escape from the residual sludge, directing them to the gas safety control module 320 for collection and treatment. This process is repeated until the entire top membrane of the landfill pit is completely removed.

[0080] After the membrane removal operation is completed, step S300 of the method in this embodiment of the invention further includes the coordinated cleaning of residual materials at the bottom of the pit. This step aims to thoroughly remove the sludge and solid waste left after the intelligent adaptive dredging stage, and its specific implementation may include the following sub-steps:

[0081] S321, Washing and Collection of Residual Sludge at Edges and Corners: Using a high-pressure water gun, residual sludge in areas difficult for main dredging equipment to reach, such as the bottom corners and slope toes, is washed away. The hydraulic action generated by this washing operation fluidizes the solidified or attached sludge on the liner surface and, taking advantage of the natural slope of the pit bottom, causes it to collect in the low-lying areas at the bottom of the pit.

[0082] S322, Targeted Cleaning of Solid Waste: Using a long-arm excavator, clean the solid waste at the bottom of the pit. To protect the HDPE liner at the bottom of the pit during the cleaning process, the front end of the bucket of the long-arm excavator is wrapped with or equipped with a flexible scraper made of polymer material (such as polyurethane or high-density polyethylene) to prevent the bucket from directly contacting and scratching the HDPE liner at the bottom of the pit during the scraping operation. The target of the cleaning operation, i.e., the location of the solid waste, can be guided by the 3D model and obstacle distribution map generated in step S124, or it can be located by on-site personnel based on visual observation.

[0083] S323, Coordinated Removal of Sludge and Waste: A long-arm excavator, in conjunction with a high-pressure water jet, removes the sludge washed and collected in low-lying areas in step S321. The removed residual sludge and solid waste cleared in step S322 are loaded onto transport vehicles and transported for disposal. Through this coordinated mechanical and manual operation, comprehensive cleaning of residual materials at the bottom of the pit is achieved.

[0084] After completing the coordinated cleaning of residual materials at the bottom of the pit, step S300 of this embodiment of the invention finally includes quantitative acceptance based on organic matter content to objectively and quantifiably assess the completion of the pit cleaning work. Its specific implementation may include the following sub-steps:

[0085] S331, Multi-point sampling: Sampling is conducted at the bottom of the cleaned landfill pit according to a pre-set sampling plan. In one specific embodiment, a seven-point sampling method is used, with sampling points including the four corner points and the center point at the bottom of the landfill pit, as well as the midpoints of the two diagonals. At each sampling point, samples of residual deposits on the surface of the HDPE liner at the bottom of the pit are collected.

[0086] S332, Determination of Organic Matter Content in Samples: Seven collected samples were sent to the laboratory for determination of their organic matter content. The method used was loss on ignition. Specifically, the samples were dried to constant weight at 105°C, weighed, and then placed in a muffle furnace and ignited at 600°C to constant weight. The organic matter content was determined by calculating the ratio of the mass difference before and after ignition to the mass of the dry sample before ignition. The specific experimental procedures are well-known in the field and will not be described in detail here.

[0087] S333, Acceptance Criteria: The success or failure of the inventory clearance work is determined by a predetermined acceptance threshold. (For example, 5%) is correlated. The organic matter content of the seven samples detected in step S332 is compared with this threshold. The landfill cleaning work is deemed qualified and the adaptive treatment process of the entire landfill bottom is completed only if the test results of all seven sampling points are not higher than the acceptance threshold. If the test result of any sampling point is higher than the threshold, the area represented by that sampling point is deemed not thoroughly cleaned, and the area needs to be reworked and resampled until it is qualified.

Claims

1. A landfill pit bottom treatment process, characterized in that, Includes the following steps: S100: Prepare for 3D environment modeling. Under the HDPE film covering the landfill pit to be treated, use the intelligent sensing execution subsystem to scan the sludge at the bottom of the pit and generate a 3D digital terrain model of the sludge at the bottom of the pit. S200: Intelligent adaptive sludge removal, using the intelligent sensing and execution subsystem to pump and clean the sludge at the bottom of the pit. In this step, the real-time sludge concentration during the pumping process is collected in real time and compared with the preset target concentration to obtain the control error. The operating parameters of the intelligent sensing and execution subsystem are adjusted according to the control error. S300: Final cleaning and acceptance. After the main dredging is completed, the remaining materials at the bottom of the pit are cleaned up, and samples are taken from the cleaned bottom of the pit for testing. The organic matter content in the samples is used to determine whether the cleaning work is qualified.

2. The landfill pit bottom treatment process according to claim 1, characterized in that, Step S100 further includes: Based on the terrain gradient data in the aforementioned 3D digital terrain model, suspected obstacle areas were identified; and The A* algorithm is used to plan a global dredging path that avoids the suspected obstacle area, and the intelligent perception and execution subsystem is controlled to perform dredging operations along the global dredging path.

3. The landfill pit bottom treatment process according to claim 1, characterized in that, The operating parameters include at least one or more of the following: the traction speed of the intelligent sensing and execution subsystem, the cutter rotation speed, and the high-pressure water flow rate.

4. The landfill pit bottom treatment process according to claim 3, characterized in that, The steps for adjusting the operating parameters based on the control error are as follows: A PID control algorithm is used, with the control error as input, to calculate and generate adjustment instructions for adjusting the operating parameters.

5. The landfill pit bottom treatment process according to claim 1, characterized in that, The process also includes: During step S200, when the cumulative decrease in mud level in the reservoir reaches a preset maintenance threshold, a circumferential extension operation is performed on the HDPE membrane.

6. The landfill pit bottom treatment process according to claim 1, characterized in that, The process also includes: During step S200, water accumulated on the membrane is pumped out by an automatic submersible pump arranged on the HDPE membrane surface; when the level sensor of the automatic submersible pump detects that the water depth exceeds a preset safe depth value, the pumping is initiated.

7. The landfill pit bottom treatment process according to claim 2, characterized in that, Step S300 specifically includes: Before removing the HDPE film, the sealed space beneath the HDPE film is forcibly replaced with sub-film gas, and the replaced gas is introduced into a mobile odor scrubbing tower for treatment.

8. The landfill pit bottom treatment process according to claim 7, characterized in that, After the forced replacement of the gas under the membrane is completed, step S300 further includes: The HDPE film is peeled off gradually and in sections, and deodorizing mist cannons are activated at the edge of the film peeling operation area to dilute and replace residual escaping gas.

9. A landfill pit bottom treatment process according to claim 1, characterized in that, The step of cleaning up the residual material at the bottom of the pit specifically includes: Using a long-arm excavator with a flexible scraper in conjunction with a high-pressure water gun, residual sludge and solid waste at the bottom corners of the pit are collected and removed.

10. A landfill pit bottom treatment process according to claim 1, characterized in that, The step of determining whether the warehouse cleaning work is qualified based on the organic matter content in the sample is as follows: A seven-point sampling method was used to take samples from the bottom of the pit; when the organic matter content of the samples from all seven sampling points was not higher than the preset acceptance threshold, the silo cleaning work was deemed qualified.

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