A method and device for aerobic stabilization of landfills in various scenarios

Abstract

The present invention provides a method and device for aerobic stabilization of landfills in various scenarios, including step S1, dividing the landfill area into several blocks, determining the size range of each area, the pipe diameter, opening size and burial depth of the gas extraction pipeline, the size and connection method of each level of connecting pipelines, and the monitoring indicators of each area; step S2, for areas with a landfill age of no more than 2 years, only injecting air; for areas with a landfill age of 2-5 years, injecting air and ozone; for areas with a landfill age of more than 5 years, injecting air and aerobic bacteria; step S3, after a period of reaction, using forced air extraction to extract the landfill gas from each area; and through a monitoring and control device arranged on a secondary air extraction pipeline, real-time monitoring of characteristic pollutants in the pipeline; step S4, connecting the exhaust fan to the tail gas treatment equipment, and discharging the gas after the gas treatment meets the standards. The present invention realizes the refinement of landfill management and the reduction of costs.

Description

Technical Field

[0001] The present invention relates to the technical field of landfills, and in particular to a method and a device for aerobic stabilization of landfills applicable to various scenarios. Background Art

[0002] Landfill technology has been the mainstream technology for domestic waste disposal in the past few decades. Landfills are affected by factors such as regional climate conditions and waste composition. Without artificial regulation, traditional landfills generally take 30-50 years to become completely stable after closure. During the long degradation cycle, on the one hand, landfills will continue to produce pollutants such as leachate and landfill gas, which require long-term and continuous post-maintenance to eliminate their impact on the surrounding environment; on the other hand, landfills will also form a long-term land occupation effect, wasting land resources and damaging the image of urban and rural environments.

[0003] Domestic and foreign domestic waste landfill management technologies mainly include in-situ closure, screening and comprehensive utilization, relocation and aerobic stabilization. Among the four technologies, screening and comprehensive utilization and relocation have higher costs and are suitable for areas with small garbage stocks, sufficient financial funds and high-density land use; while in-situ closure and aerobic stabilization have lower costs and are very suitable for areas with large garbage stocks and low-density land use. Compared with in-situ closure, aerobic stabilization has the advantages of short degradation time, less leachate production and low greenhouse gas emissions.

[0004] Most of the existing landfill designs and implementation plans only consider simplifying the landfill as a whole, without further in-depth exploration in the direction of homogenization. They only consider the integrity of the landfill, and ignore the fact that the landfill, as a long-term garbage receiving carrier, changes with time, economy, and different types of landfill materials when laying out the pipeline. Therefore, in the actual construction process, especially in the management of large landfills, the method of taking the landfill as a whole cannot effectively meet the increasingly sophisticated needs, and often results in different orders of stabilization progress in different areas under the same conditions.

[0005] In view of this, the present invention proposes a method and device for aerobic stabilization of landfills applicable to various scenarios. Summary of the invention

[0006] The present invention provides a method and device for aerobic stabilization of landfills applicable to various scenarios, so as to solve the excavation risk caused by insufficient aerobic stabilization and the problem of simply aerobic ventilation of the landfill in the prior art instead of detailed design according to time and place.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A method for aerobic stabilization of landfills applicable to a variety of scenarios, including:

[0009] Step S1, dividing the landfill area into several blocks, determining the size of each block, the diameter of the gas extraction pipeline, the size of the opening and the burial depth, the size and connection method of the connecting pipelines at all levels, and the monitoring indicators of each block;

[0010] Step S2: For areas where the landfill age is less than 2 years, only air is injected; for areas where the landfill age is 2-5 years, air and ozone are injected; for areas where the landfill age is more than 5 years, air and aerobic bacteria are injected;

[0011] Step S3, after a period of reaction, the landfill gas in each area is extracted by forced extraction of the pile; and the characteristic pollutants in the pipeline are monitored in real time by a monitoring and control device arranged on the secondary extraction pipeline;

[0012] Step S4: the exhaust fan is connected to the tail gas treatment equipment, and the gas is discharged after being treated to meet the standards.

[0013] Optionally, in step S2, for areas with a landfill age of no more than 2 years, the monitoring indicators are oxygen and carbon dioxide. When the oxygen concentration is less than 15 vol%, air is injected; when the carbon dioxide concentration is higher than 10 vol%, air is extracted.

[0014] Optionally, in step S2, for areas with a landfill age of 2-5 years, the monitoring indicators are methane and malodorous gases, and the malodorous gases include hydrogen sulfide, ammonia, and odor concentration, which can be monitored according to the Emission Standard for Odor Pollutants (GB14554-93).

[0015] Optionally, in step S2, for areas that have been landfilled for more than 5 years, the monitoring indicators include ammonia, trimethylamine, hydrogen sulfide, methyl mercaptan, methyl sulfide, dimethyl disulfide, carbon disulfide, styrene and odor concentrations.

[0016] Optionally, ozone is injected at a mass concentration of 1-3% in step S2; ozone has strong oxidizing properties and does not produce difficult-to-treat byproducts after the reaction; ozone with too high a mass concentration is prone to excessive oxidation, causing the disintegration of the bacterial community and destroying the ecological balance in the landfill; and low-concentration ozone cannot achieve the predetermined oxidation effect. After project testing, ozone has an optimal reaction range at a concentration of 1-3%, and is dynamically adjusted according to the gas concentration; at the same time, the target pollutants removed by ozone are high-molecular organic substances that are difficult to degrade in landfill gas. Such organic substances are difficult to be used by organisms. Ozone cuts off the long chain of high-molecular organic substances through oxidizing groups, and some of them are completely decomposed into carbon dioxide and water, and the remaining part becomes small-molecule organic matter, which is convenient for subsequent biological use. The aerobic bacterial agent is a methane mixed bacteria, including formic acid methanobacterium and nitrosobacteria. The bacterial agent mainly utilizes methane in the landfill, and uses ammonia and hydrogen sulfide as reaction substrates, and has the function of decomposing small-molecule organic matter.

[0017] Optionally, when ozone and aerobic bacteria are injected in step S2, the amount and concentration of the added agent are controlled by the PLC; the aerobic bacteria and ozone can be atomized before injection and then fully mixed with the air in the pipeline. After the ozone is liquefied, it is blown to the landfill by wind, and the dosage is controlled by the PLC. Because the air volume of the fan is much larger than the dosage of the agent, there is no phenomenon of droplets being retained in the pipeline, and the atomized agent can completely enter the landfill together with the air intake of the fan.

[0018] Furthermore, the present invention also provides a device for the above method, comprising:

[0019] Fan system, piping system, reagent preparation system, monitoring and control system and exhaust gas treatment system,

[0020] The fan system includes an air injection fan and an air exhaust fan. The air injection fan sucks in air, compresses it, and pumps it into the garbage pile. The tail gas and non-reactive polluted gas generated after the reaction are extracted by the air exhaust fan.

[0021] The pipeline system includes a gas injection well, a gas extraction well, a primary gas injection pipeline, a primary gas extraction pipeline, a secondary gas injection pipeline, a secondary gas extraction pipeline, a tertiary gas injection pipeline, and a tertiary gas extraction pipeline;

[0022] The reagent preparation system includes an ozone supply device and an aerobic bacteria supply device. The ozone and aerobic bacteria are inserted into the secondary pipes of the corresponding blocks through the corresponding pipelines by the variable frequency dosing pump;

[0023] The monitoring and control system consists of two systems, one located in the secondary exhaust pipeline of each block, and the other located at the exhaust gas treatment outlet;

[0024] The exhaust gas treatment system includes exhaust gas treatment equipment.

[0025] Optionally, the diameter of the gas injection well and the gas extraction well is 400-600mm, using seamless or seamed pipes; the diameter of the first-level gas injection pipeline and the first-level gas extraction pipeline is DN200-400mm; the diameter of the second-level gas injection pipeline and the second-level gas extraction pipeline is DN100-200mm; the diameter of the third-level gas injection pipeline and the third-level gas extraction pipeline is DN32-50mm.

[0026] Optionally, the reagent configuration system is arranged at the outlet of the first-level gas injection pipeline, and each junction of the first-level gas injection pipeline and the second-level gas injection pipeline is connected to the reagent preparation system; the second-level gas injection pipeline is a collection pipeline of the third-level gas injection pipeline, and according to the on-site layout, each vertically arranged gas injection well is connected to a second-level gas injection pipeline; the third-level gas injection pipeline is directly connected to the wellhead of the gas injection well, and the gas is injected from the wellhead and diffused in each layer of the garbage pile.

[0027] Optionally, the monitoring data of the monitoring and control system is fed back to the dosage preparation system and the blower system in real time to realize automatic control of the system.

[0028] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0029] By pumping gas and adding different agents according to the conditions of different landfill blocks, aeration can be avoided in a one-size-fits-all manner, aeration time and fan start-up frequency can be reduced, and electricity costs can be saved; different treatment plans are adopted in different areas, which can achieve different utilization in different areas, and can achieve phased utilization in different areas, accelerating the stabilization time; according to monitoring feedback, different pollutants can be removed through the coordination of different agents, avoiding the conventional aerobic technology that only focuses on organic matter degradation, can only remove simple pollutants in a short time by regulating the gas-liquid redistribution of the garbage pile, and has no significant reduction effect on biodegradable substances (cellulose, lignin). It is convenient for subsequent safer reuse; thus, the landfill management is refined and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a schematic diagram of an aerobic stabilization device for a landfill applicable to various scenarios of the present invention, wherein 1- tail gas treatment equipment, 2- exhaust fan, 3- air injection fan, 4- primary exhaust pipeline, 5- primary injection pipeline, 6- monitoring and control system, 7- reagent preparation system, 8- injection well, 9- exhaust well, 10- tertiary exhaust pipeline, 11- tertiary injection pipeline, 12- secondary injection pipeline, 13- secondary exhaust pipeline. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention divides the landfill area into several blocks, one of which is injected with pure air, one is injected with air + ozone, and one is injected with air + aerobic bacteria. In the area where only air is injected, the landfill time of the pile is short and the thickness of the garbage pile layer is thin. The main monitoring indicators of this section are oxygen and carbon dioxide. When oxygen is less than 15vol%, the air injection fan is turned on; when carbon dioxide is higher than 10vol%, the exhaust fan is turned on. In the area where air + ozone is injected, the landfill age of the landfill is 2-5 years, and the pile is in the methane production stage. Ozone can inhibit the activity of methanogens, and its byproducts ammonia and hydrogen sulfide will also be oxidized, and its stable period (methane production and odorous gas) is lower than expected. The area where air + aerobic bacteria are injected is aimed at landfill blocks with a long landfill age, where easily degradable organic matter has been basically degraded, and where the excavation order is relatively late. After a certain period of ventilation (stable aerobic content of more than 15%), the aerobic bacteria landfill environment is improved.

[0034] like Figure 1 As shown, the present invention provides a device for aerobic stabilization of landfills in various scenarios, including a fan system, a pipeline system, a reagent preparation system, a monitoring and control system, and an exhaust gas treatment system.

[0035] The fan system includes an air injection fan 2 and an air exhaust fan 3. The air injection fan 2 sucks in air through the suction blowing system, compresses it, and pumps it into the garbage pile. The air diffuses in each layer of the pile and participates in the biological reaction in the pile. The tail gas and non-reactive polluted gas generated after the reaction are extracted through the pipeline by the air exhaust fan, and are treated by the tail gas treatment equipment 1 before being discharged in compliance with the emission standards.

[0036] The pipeline system includes an injection well 8, an exhaust well 9, a first-level gas injection pipeline 5, a first-level gas exhaust pipeline 4, a second-level gas injection pipeline 12, a second-level gas exhaust pipeline 13, a third-level gas injection pipeline 11, and a third-level gas exhaust pipeline 10; the diameter of the gas injection well 8 and the exhaust well 9 is 400-600mm, and seamless or seamed pipes are used. The seamed pipes are slit at 1-6m and are wrapped with nylon bags to prevent clogging of the cut seams; the diameter of the first-level gas injection pipeline 5 and the first-level gas exhaust pipeline 4 is DN200-400mm; the diameter of the second-level gas injection pipeline and the second-level gas exhaust pipeline is DN100-200mm; the diameter of the third-level gas injection pipeline and the third-level gas exhaust pipeline is DN32-50mm.

[0037] The reagent preparation system 7 includes an ozone supply device and an aerobic bacteria agent supply device. The ozone and aerobic bacteria agent are inserted into the secondary pipes of the corresponding blocks through the corresponding pipelines by the variable frequency dosing pump. When injecting ozone and aerobic bacteria agents, the amount and concentration of addition are controlled by PLC; the aerobic bacteria agents and ozone can be atomized before injection and then fully mixed with the air in the pipeline.

[0038] The monitoring and control system 6 mainly monitors oxygen, methane, hydrogen sulfide, ammonia, etc. It includes two systems, one is located in the secondary exhaust pipeline of each block, and the system data is fed back to the PLC control system, and the other is located at the exhaust gas treatment outlet to monitor the exhaust gas emission compliance.

[0039] The tail gas treatment system comprises a tail gas treatment device 1, which mainly adopts biological deodorization methods and facilities.

[0040] When the above device is running:

[0041] Based on the preliminary investigation data of the project, a preliminary aerobic stabilization plan was formulated. The plan content includes the size of each area, the diameter of the pipeline for extracting gas, the size of the opening, the burial depth, the size and connection method of the connecting pipelines at all levels, and the monitoring indicators of each area.

[0042] Air is sucked in by the air injection fan, and after being compressed, it moves to the secondary air injection pipeline through the primary air injection pipeline. The secondary air injection pipeline is the main pipeline connecting the landfill, and the reagent preparation system is set at the outlet of the primary air injection pipeline. The concentration and dosage of the reagent preparation system are controlled by PLC, and the output section adopts an automatic concentration regulating pump; before the pipeline inlet, the reagent (ozone or aerobic bacteria agent) is pressurized and atomized, then fully mixed with the air in the pipeline and injected into the landfill.

[0043] The secondary pipeline is connected to several tertiary pipelines, and the tertiary pipeline is directly connected to the wellhead of the gas injection well. The aerobic mixed gas is injected from the wellhead and diffused in each layer of the garbage pile through the pipeline.

[0044] After a period of reaction, the landfill gas in each area is extracted from the pile by forced extraction. The secondary extraction pipelines are equipped with monitoring and control devices to monitor the characteristic pollutants in the pipelines in real time.

[0045] The gas extracted by the exhaust fan cannot be discharged directly. The fan must be connected to exhaust gas treatment equipment and can only be discharged after the treatment meets the standards.

[0046] The monitoring data of the monitoring and control system is fed back to the dosage dispensing system and the fan system, and the system is automatically controlled according to the set control parameters.

[0047] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for aerobic stabilization of landfills applicable to various scenarios, characterized in that: include: Step S1, dividing the landfill area into several blocks, determining the size of each block, the diameter of the gas extraction pipeline, the size of the opening and the burial depth, the size and connection method of the connecting pipelines at all levels, and the monitoring indicators of each block; Step S2: For areas where the landfill age is less than 2 years, only air is injected; for areas where the landfill age is 2-5 years, air and ozone are injected; for areas where the landfill age is more than 5 years, air and aerobic bacteria are injected; Step S3, after a period of reaction, the landfill gas in each area is extracted by forced extraction of the pile; and the characteristic pollutants in the pipeline are monitored in real time by a monitoring and control device arranged on the secondary extraction pipeline; Step S4: the exhaust fan is connected to the tail gas treatment equipment, and the gas is discharged after being treated to meet the standards.

2. The method according to claim 1, characterized in that: In step S2, for areas with a landfill age of no more than 2 years, the monitoring indicators are oxygen and carbon dioxide. When the oxygen concentration is less than 15 vol%, air is injected; when the carbon dioxide concentration is higher than 10 vol%, air is extracted.

3. The method according to claim 1, characterized in that In step S2, ozone with a mass concentration of 1-3% is injected; the aerobic bacterial agent is a methane mixed bacteria of Methanobacterium formicum and Nitrosobacteria.

4. The method according to claim 1, characterized in that: When ozone and aerobic bacteria agent are injected in step S2, the amount and concentration of addition are controlled by PLC; the aerobic bacteria agent and ozone can be atomized before injection and then fully mixed with the air in the pipeline.

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