Method for comprehensive treatment of domestic waste landfill

Abstract

The present application relates to the technical field of domestic waste treatment, and provides a comprehensive treatment method for domestic waste landfill site, which respectively treats the waste pile and leachate of the waste landfill site, transports the water produced by the partial treatment of the leachate of the waste to an ultrafiltration system for self-cleaning of the ultrafiltration system, injects the water produced by the treatment of the leachate of the waste into the waste pile, and degrades the organic matter content in the pile by using the oxidizability of the water. The present application realizes the fast, energy-saving, secondary pollution-free and continuous and effective comprehensive treatment of the domestic waste landfill site.

Description

Technical Field

[0001] This invention relates to the field of municipal solid waste treatment technology, and in particular to a method for the comprehensive remediation of municipal solid waste landfills. Background Technology

[0002] Landfills occupy valuable land resources, and over time, the decomposition of landfill materials produces highly polluting leachate, which contaminates surface water and groundwater. Therefore, comprehensive remediation of landfills is necessary.

[0003] Currently, landfill remediation technologies mainly include: stormwater management, soil covering, vegetation cover, isolation and seepage prevention, excavation and screening, incineration, anaerobic fermentation, and aerobic stabilization. Among these, the treatment of landfill leachate primarily utilizes a combination of biological and membrane treatment technologies. Stormwater management can effectively reduce the increase of leachate in landfills caused by rainwater, but it cannot prevent leachate generated from the degradation of waste itself. Soil covering and vegetation cover technologies only visually improve the appearance of landfills, but landfill gas and leachate still pollute the surrounding atmosphere, soil, surface water, and groundwater. Isolation and seepage prevention technologies involve constructing barrier walls or reactive barriers around the landfill. To a certain extent, these barriers can contain waste and leachate, preventing leachate from migrating outward and reducing the risk of pollution to the external environment. However, leachate can slowly diffuse downwards through the barrier walls, or geological changes can damage the barrier walls, both of which can cause leachate pollution of the surrounding environment. Excavation, screening, and incineration technologies can remove pollution sources in one step, but they are costly and prone to secondary pollution during waste transfer. In-situ anaerobic fermentation technology has low energy consumption and can turn waste into valuable resources, producing methane energy. However, the in-situ anaerobic fermentation process is too long, and in practical engineering applications, it is difficult to effectively collect methane gas, easily causing air pollution. Poor management can also lead to fires or even explosions. Aerobic stabilization technology can rapidly decompose biodegradable organic matter in waste without producing methane, and the processing speed is fast, but it requires high-powered aeration and extraction fans, resulting in high energy consumption. In the treatment of landfill leachate, concentrated liquid generally uses technologies such as reinjection, evaporation crystallization, submerged combustion evaporation, and electro-oxidation. Currently, some regions have explicitly prohibited the reinjection of concentrate; evaporation crystallization technology is prone to forming dirt on the equipment surface during application, which reduces heat transfer efficiency and increases energy consumption; submerged combustion evaporation treatment technology requires laying gas pipelines or obtaining gas from nearby sources, making the technology difficult to implement and costly; electro-oxidation treatment technology directly forms strong oxidizing products in the concentrate to directly oxidize pollutants such as COD and ammonia nitrogen that are difficult to degrade, but its effluent has high oxidizing properties, and direct entry into sewage treatment plants may damage the biological system.

[0004] As can be seen from the above analysis, implementing a single treatment technology is difficult to achieve effective treatment of landfills or the treatment cost is extremely high. Therefore, a comprehensive landfill remediation technology that is fast, energy-saving, free of secondary pollution, low-cost, and sustainable is an inevitable requirement for landfill remediation. Summary of the Invention

[0005] The purpose of this invention is to provide a comprehensive treatment method for municipal solid waste landfills, so as to achieve rapid, energy-saving, pollution-free, and continuously effective comprehensive treatment of municipal solid waste landfills.

[0006] The technical solution adopted in this invention is to treat the landfill waste pile and leachate separately, including the following steps:

[0007] Remediation of garbage dumps:

[0008] (1) Clear and shape the pile body. Design according to the original terrain of the pile body, shape the pile body into a gentle slope and compact it.

[0009] (2) Well construction: Design the location, depth and density of wells based on the content of degradable organic matter in the pile body, and construct gas injection wells, gas extraction wells, leachate reinjection wells, leachate extraction wells, gas monitoring wells, comprehensive monitoring wells and supporting gas injection and extraction fan equipment.

[0010] (3) Cover with clay. Use clay to evenly cover the shaped pile to form a clay layer and compact it. The compacted clay layer should be no less than 50cm. After compaction, the terrain should still retain the slope after shaping. This layer serves as a clay protection layer under the membrane to prevent the garbage layer from puncturing the membrane.

[0011] (4) Construct rainwater drainage ditches. Based on the shape of the pile, construct rainwater drainage ditches on the lower slope of the pile to collect rainwater.

[0012] (5) Covering the clay layer with a geomembrane to prevent rainwater from seeping into the pile body. Covering the geomembrane with a geosynthetic drainage net to guide the seeping rainwater to the rainwater drainage ditch.

[0013] (6) Cover with planting soil. Use planting soil to cover the geotextile drainage net. The covering thickness should not be less than 50cm. It does not need to be compacted. It is used for planting grass and other green plants with underdeveloped root systems.

[0014] (7) Normal operation: including gas injection / extraction, temperature and humidity monitoring inside the reactor, methane monitoring, oxygen monitoring, sulfur dioxide monitoring, leachate reinjection to maintain appropriate humidity inside the reactor, leachate drainage to maintain a low water level inside the reactor, exhaust gas treatment, etc.

[0015] Landfill leachate treatment:

[0016] (1) The leachate in the pile body is collected and discharged into the leachate conditioning tank for homogenization and sedimentation treatment. Depending on the water quality, if the leachate has extremely poor biodegradability, a Fenton oxidation tank is set up to perform Fenton treatment at a lower cost to improve the biodegradability of the leachate and allow it to flocculate and settle before entering the next stage.

[0017] (2) A surface water sampler is used to extract surface leachate from the equalization tank / Fenton oxidation tank and send it to the biochemical system for biochemical treatment.

[0018] (3) After biochemical treatment, it enters the membrane treatment system for further processing. The membrane treatment system includes ultrafiltration system, nanofiltration system and reverse osmosis system.

[0019] (4) The concentrate produced by reverse osmosis is treated by electro-oxidation technology. Part of the electro-oxidation permeate is sent to the ultrafiltration system for self-cleaning of the ultrafiltration system, and part of the electro-oxidation permeate is injected into the landfill. The oxidizing properties of the electro-oxidation permeate are used to degrade the organic matter content in the landfill. The remaining reverse osmosis permeate and electro-oxidation permeate are discharged after treatment to meet the standards.

[0020] Specifically, the geomembrane used in step (5) of the treatment of the waste pile is an HDPE geomembrane.

[0021] Furthermore, the membrane of the nanofiltration system used in the landfill leachate treatment step (3) is also made of oxidation-resistant material, and in the landfill leachate treatment step (4), part of the electro-oxidation water is transported to the ultrafiltration system and nanofiltration system for system self-cleaning.

[0022] The beneficial effects of this invention are:

[0023] (1) A portion of the electro-oxidation permeate from the treatment of landfill leachate is transported to the ultrafiltration system cleaning tank (including submersible and tubular ultrafiltration systems) for self-cleaning of the ultrafiltration system. After treating the concentrate with electro-oxidation technology, the permeate is clean and clear, and contains hypochlorite ions, free hydroxyl groups, etc., which have strong oxidizing properties. Generally, ultrafiltration membranes (referring to PVDF, PTFE, etc.) have antioxidant properties. When ultrafiltration membranes filter leachate, organic pollution is easily generated. Using oxidizing cleaning solutions to clean the ultrafiltration membrane can quickly restore the membrane flux, save operating costs, save water resources, and increase the permeate production rate. If the reverse osmosis of the nanofiltration system is made of oxidation-resistant materials, the electro-oxidation permeate can also be reused for cleaning.

[0024] (2) The highly oxidizing electro-oxidation water from the treatment of landfill leachate is injected into the landfill. The oxidizing properties of the water are used to degrade the organic matter content in the landfill. After the landfill is sealed and covered, the aerobic accelerated stabilization process is not adopted. The electro-oxidation water can be returned to the landfill or even the electro-oxidation treatment technology can be used to generate highly oxidizing electro-oxidation water for circulation and injection into the landfill to oxidize the organic matter in the landfill, thereby achieving the effect of quickly stabilizing the landfill. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process flow for the comprehensive remediation method for municipal solid waste landfills provided by the present invention. Detailed Implementation

[0026] To make the objectives, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] like Figure 1 As shown, in a specific embodiment of the comprehensive remediation method for municipal solid waste landfills provided by the present invention, the landfill's waste pile and leachate are remediated separately, including the following steps:

[0028] Remediation of garbage dumps:

[0029] (1) Clear and shape the pile body. Design according to the original terrain of the pile body, shape the pile body into a gentle slope and compact it.

[0030] (2) Well construction: Design the location, depth and density of wells based on the content of degradable organic matter in the pile body, and construct gas injection wells, gas extraction wells, leachate reinjection wells, leachate extraction wells, gas monitoring wells, comprehensive monitoring wells and supporting gas injection and extraction fan equipment.

[0031] (3) Cover with clay. Use clay to evenly cover the shaped pile to form a clay layer and compact it. The compacted clay layer should be no less than 50cm. After compaction, the terrain should still retain the slope after shaping. This layer serves as a clay protection layer under the membrane to prevent the garbage layer from puncturing the membrane.

[0032] (4) Construct rainwater drainage ditches. Based on the shape of the pile, construct rainwater drainage ditches on the lower slope of the pile to collect rainwater.

[0033] (5) Covering the clay layer with HDPE geomembrane to prevent rainwater from seeping into the pile body. Cover the HDPE geomembrane with geotextile drainage net to guide the seeping rainwater to the rainwater drainage ditch.

[0034] (6) Cover with planting soil. Use planting soil to cover the geotextile drainage net. The covering thickness should not be less than 50cm. It does not need to be compacted. It is used for planting grass and other green plants with underdeveloped root systems.

[0035] (7) Normal operation: including gas injection / extraction, temperature and humidity monitoring inside the reactor, methane monitoring, oxygen monitoring, sulfur dioxide monitoring, leachate reinjection to maintain appropriate humidity inside the reactor, leachate drainage to maintain a low water level inside the reactor, exhaust gas treatment, etc.

[0036] Landfill leachate treatment:

[0037] (1) The leachate in the pile body is collected and discharged into the leachate conditioning tank for homogenization and sedimentation treatment. Depending on the water quality, if the leachate has extremely poor biodegradability, a Fenton oxidation tank is set up to perform Fenton treatment at a lower cost to improve the biodegradability of the leachate and allow it to flocculate and settle before entering the next stage.

[0038] (2) A surface water sampler is used to extract surface leachate from the equalization tank / Fenton oxidation tank and send it to the biochemical system for biochemical treatment.

[0039] (3) After biochemical treatment, it enters the membrane treatment system for further processing. The membrane treatment system includes ultrafiltration system, nanofiltration system and reverse osmosis system.

[0040] (4) The concentrate produced by reverse osmosis is treated by electro-oxidation technology. Part of the electro-oxidation permeate is sent to the ultrafiltration system for self-cleaning of the ultrafiltration system, and part of the electro-oxidation permeate is injected into the landfill. The oxidizing properties of the electro-oxidation permeate are used to degrade the organic matter content in the landfill. The remaining reverse osmosis permeate and electro-oxidation permeate are discharged after treatment to meet the standards.

[0041] In another specific embodiment of the present invention, the membrane of the nanofiltration system in the landfill leachate treatment step (3) is also made of oxidation-resistant material, and in the landfill leachate treatment step (4), part of the electro-oxidation produced water is transported to the ultrafiltration system and the nanofiltration system for system self-cleaning.

[0042] The above description sets forth specific details to provide a full understanding of the present invention. Those skilled in the art can make similar improvements without departing from the concept of the present invention. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed.

Claims

1. A comprehensive remediation method for municipal solid waste landfills, comprising separately remediating the waste pile and leachate of the landfill, characterized in that, The following steps are included: Remediation of the waste dump: (1) Clear and shape the pile body. Design according to the original terrain of the pile body, shape the pile body into a gentle slope and compact it. (2) Well construction: Design the location, depth and density of wells based on the content of degradable organic matter in the pile body, and construct gas injection wells, gas extraction wells, leachate reinjection wells, leachate extraction wells, gas monitoring wells, comprehensive monitoring wells and supporting gas injection and extraction fan equipment. (3) Cover with clay. Use clay to evenly cover the shaped pile to form a clay layer and compact it. The compacted clay layer should be no less than 50cm. After compaction, the terrain should still retain the slope after shaping. This layer serves as a clay protection layer under the membrane to prevent the garbage layer from puncturing the membrane. (4) Construct rainwater drainage ditches. Based on the shape of the pile, construct rainwater drainage ditches on the lower slope of the pile to collect rainwater. (5) Covering the clay layer with a geomembrane to prevent rainwater from seeping into the pile body. Covering the geomembrane with a geosynthetic drainage net to guide the seeping rainwater to the rainwater drainage ditch. (6) Cover with planting soil. Use planting soil to cover the geotextile drainage net. The covering thickness should not be less than 50cm. It does not need to be compacted. It is used for planting grassland with underdeveloped root systems. (7) Normal operation: including gas injection / extraction, temperature and humidity monitoring inside the reactor, methane monitoring, oxygen monitoring, sulfur dioxide monitoring, leachate reinjection to maintain appropriate humidity inside the reactor, leachate drainage to maintain a low water level inside the reactor, and exhaust gas treatment; Landfill leachate treatment: (1) The leachate in the pile body is collected and discharged into the leachate conditioning tank for homogenization and sedimentation treatment. Depending on the water quality, if the leachate has extremely poor biodegradability, a Fenton oxidation tank is set up to perform Fenton treatment at a lower cost to improve the biodegradability of the leachate and allow it to flocculate and settle before entering the next stage. (2) A surface water sampler is used to extract surface leachate from the equalization tank / Fenton oxidation tank and send it to the biochemical system for biochemical treatment. (3) After biochemical treatment, it enters the membrane treatment system for further processing. The membrane treatment system includes ultrafiltration system, nanofiltration system and reverse osmosis system. (4) The concentrate produced by reverse osmosis is treated by electro-oxidation technology. Part of the electro-oxidation permeate is sent to the ultrafiltration system for self-cleaning of the ultrafiltration system, and part of the electro-oxidation permeate is injected into the landfill. The oxidizing properties of the electro-oxidation permeate are used to degrade the organic matter content in the landfill. The remaining reverse osmosis permeate and electro-oxidation permeate are discharged after treatment to meet the standards.

2. The method for comprehensive remediation of municipal solid waste landfills as described in claim 1, characterized in that: The geomembrane used in step (5) of the remediation of the waste pile is an HDPE geomembrane.

3. The comprehensive remediation method for municipal solid waste landfills as described in claim 1, characterized in that: In step (3) of the landfill leachate treatment, the membrane of the nanofiltration system is made of oxidation-resistant material. In step (4) of the landfill leachate treatment, part of the electro-oxidation water is transported to the ultrafiltration system and nanofiltration system for system self-cleaning.

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