Incineration plant landfill leachate treatment system based on ecological technology

Abstract

The utility model provides an incineration plant landfill leachate treatment system based on an ecological technology, which belongs to the technical field of landfill leachate treatment and resource utilization, and comprises a water supply system, a percolation tank system and a CW-MFC system formed by coupling an artificial wetland system and a microbial fuel cell system, water pipes are arranged among the water supply system, the percolation tank system and the CW-MFC system, and each water pipe is provided with a peristaltic pump. The landfill leachate treatment system combining the percolation tank system and the constructed wetland microbial fuel cell system is constructed; high-concentration pollutants are degraded and a large amount of suspended matters are removed by utilizing a filler with a high specific surface area in the percolation tank and microorganisms colonized on a substrate, so that effluent enters a constructed wetland microbial fuel cell system, and the residual pollutants difficult to degrade are purified; graded degradation and full utilization of different pollutants by each system are fully exerted, and energy substances are recycled in an electric energy mode.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of treating garbage leachate and resource utilization thereof, and specifically is an incineration plant garbage leachate treatment system based on ecological technology. Background Art

[0002] A waste incineration plant, also known as a waste-to-energy plant, is a facility that generates electricity by incinerating domestic waste. The waste is burned at high temperatures, converting chemical energy into heat energy to generate electricity. This method not only reduces the volume of waste but also recycles energy. Leachate is a secondary pollutant generated during the landfill or stacking process. It is characterized by high concentrations of organic matter, ammonia nitrogen, and, in special cases, high levels of heavy metals and salt, as well as difficulty in treatment. If leachate is discharged without treatment, it will not only damage the soil, pollute water bodies, and endanger human health, but will also result in a waste of C, N, and precious metal resources.

[0003] Commonly used methods for treating landfill leachate at home and abroad include physical, chemical, biological, and ecological treatment methods. Physical methods such as ultrafiltration, nanofiltration, DO, and DTRO offer high desalination rates and good effluent quality, but are susceptible to membrane fouling and damage, are costly, and exhibit rapid flux attenuation. Chemical methods such as electrochemical oxidation and Fenton oxidation are highly efficient but are significantly affected by pH and prone to secondary contamination. Biological methods such as SBR and MBR combined processes are highly efficient, but require sludge acclimation and the microorganisms are significantly affected by temperature. Constructed wetlands are the preferred ecological technology. Constructed wetlands offer advantages such as low investment, low cost, and easy management. Coupling CW with microbial fuel cell technology can effectively remove heavy metals and difficult-to-degrade organic compounds such as humic acid, fulvic acid, and bisphenol A. Compared to using CW alone, this coupled technology can increase decontamination efficiency by approximately 10%. However, CW-MFC coupled systems have not been used for landfill leachate treatment.

[0004] Microbial fuel cells (MFCs), as an emerging method for pollutant removal and power generation, have gradually become a hot topic of concern for researchers at home and abroad in terms of low-energy wastewater treatment, and have received widespread attention and research. Their principle is that electrochemically active bacteria obtain electrons by decomposing organic matter in wastewater during metabolism. The electrons are transferred to the MFC anode through various transfers and then to the MFC cathode with the help of an external circuit, thus realizing a completely closed electrical circuit.

[0005] The constructed wetland (CW) system has the natural characteristics of deep anaerobicity and surface aerobicity, which can meet the anode and cathode environmental conditions required by MFC technology. By fully utilizing the respective advantages of the two technologies, a CW-MFC coupled wastewater treatment technology has been formed. Landfill leachate is a type of wastewater with a high concentration of organic and inorganic components containing a large amount of suspended matter, and its COD concentration can be as high as tens of thousands.

[0006] Prior art, such as patent publication number CN110143720 A, discloses a constructed wetland microbial fuel cell device for efficiently treating nitrogen-containing wastewater. The constructed wetland matrix utilizes a variety of media fillers, with coconut shell activated carbon and stainless steel mesh serving as the anode and cathode, and ceramsite as the matrix filler, to enhance denitrification and improve power generation. However, its shortcomings include a complex chamber setup, numerous management steps, and a small filler particle size that easily clogs, preventing multiple uses. Chinese patent applications with patent numbers CN201810269612.9, CN202010689621.0, and CN202210903221.4, respectively, describe several differently constructed constructed wetland microbial fuel cell devices for wastewater treatment. While all achieve the goal of simultaneously degrading pollutants and generating bioelectricity, their wastewater purification and power generation performance remain suboptimal.

[0007] Combining a microbial fuel cell (MFC) system with a constructed wetland (CW) system—known as a CW-MFC system—for treating landfill leachate not only degrades pollutants but also generates biomass electricity and reduces greenhouse gas emissions. This, to a certain extent, alleviates the world's increasingly tight energy situation while significantly reducing the infrastructure and treatment costs of using MFC systems alone for wastewater treatment. In summary, the coupling of constructed wetlands and MFCs has undergone considerable research and development, with fruitful results. However, research on the practical application of CW-MFC in treating wastewater containing large amounts of suspended solids and high concentrations of organic and inorganic components is scarce. Constructed wetlands are composed of fillers, plants, and microorganisms. Excessive suspended solids can not only clog the fillers, thus compromising system operation, but also damage plant roots, causing plant wilt and death due to high concentrations of organic matter or heavy metals. Therefore, CW-MFC systems cannot be used directly to treat high-concentration wastewater containing large amounts of suspended solids. Research suggests that surface percolation tanks can remove suspended solids simultaneously with pollutants. Furthermore, percolation tank technology is an ecological approach, eliminating the high costs and management overheads and generating no secondary waste.

[0008] Based on this, we need to develop a leachate treatment system that combines a filtration tank system with a CW-MFC system to treat high-concentration wastewater containing a large amount of suspended matter, and generate electricity while degrading pollutants. This application has important theoretical and practical significance for the treatment and resource utilization of high-concentration wastewater containing a large amount of suspended matter. Utility Model Content

[0009] The technical solution of the present invention addresses the technical problem that the existing technical solutions are too single, and provides a solution that is significantly different from the existing technology. Specifically, the present invention mainly provides an incineration plant leachate treatment system based on ecological technology to solve the technical problem proposed in the above background technology that the existing artificial wetland microbial fuel cell system cannot be directly used to treat actual wastewater with high concentration and a large amount of suspended matter.

[0010] The technical solution adopted by the utility model to solve the above technical problems is:

[0011] An incineration plant leachate treatment system based on ecological technology includes a water supply system, a percolation tank system, a constructed wetland system, and a microbial fuel cell system coupled to form a CW-MFC system. Water pipes are arranged between the water supply system, the percolation tank system, and the CW-MFC system, and each of the water pipes is provided with a peristaltic pump.

[0012] Furthermore, the water supply system includes a water storage tank, in which landfill leachate is arranged.

[0013] Furthermore, the infiltration tank system includes an organic glass column barrel, in which a first matrix with microbial colonization on the surface is arranged. The first matrix includes a gravel layer, a biochar layer, a quartz sand layer and an overlying water layer distributed in sequence from bottom to top.

[0014] Furthermore, the CW-MFC system includes a polypropylene barrel, which is provided with a second matrix for microbial colonization, plants, inoculation tubes, electrodes, an adjustable resistance box, a single-core copper wire and a paperless recorder, and the adjustable resistance box and the paperless recorder are connected in parallel to the outside of the polypropylene barrel by a single-core copper wire, and a water outlet is provided on one side of the bottom of the polypropylene barrel.

[0015] Furthermore, the plant is water hyacinth.

[0016] Furthermore, the second matrix includes a gravel layer 2, a filler layer, a fine sand layer, and an overlying water layer distributed from bottom to top. The filler layer is composed of an activated carbon layer or a sponge iron layer, and the bottom end of the inoculation tube with open ends is located in the filler layer, and the top end extends out of the overlying water layer 2.

[0017] Furthermore, the bottom of the organic glass column barrel and the water storage tank are both provided with a sample outlet, and the sample outlet is connected to one end of the corresponding water pipe.

[0018] Furthermore, the electrode includes an anode carbon felt and a cathode carbon felt, wherein the anode carbon felt is located in the filler layer and the cathode carbon felt is located at the gas-liquid interface of the overlying water layer 2, and both the anode carbon felt and the cathode carbon felt are annular carbon felt structures.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The utility model constructs a landfill leachate treatment system that combines a percolation tank system with a constructed wetland microbial fuel cell system. After the landfill leachate enters the percolation tank system, the effluent after treatment in the percolation tank enters the CW-MFC system. This avoids the problems of landfill leachate directly entering the CW-MFC system, which may clog the filler, and the high concentration of organic matter or heavy metals that damage plant roots, causing them to wither and die, and have toxic effects on microorganisms.

[0021] The mechanical filtration effect of the infiltration tank, the adsorption effect of the filler, and the transformation effect of microorganisms can only partially degrade pollutants or degrade specific pollutants. Some high-concentration and difficult-to-degrade pollutants cannot be removed well. However, after the water sample treated in the infiltration tank enters the CW-MFC system, the MFC system will produce specific microorganisms such as electrochemically active bacteria, which can treat the pollutants that have not been degraded or are difficult to degrade in the infiltration tank system, thereby achieving graded degradation of pollutants.

[0022] Moreover, this treatment system does not require additional carbon sources, does not require high operating costs and management fees, and does not produce secondary waste. It can not only degrade pollutants, but also generate biomass electricity and reduce greenhouse gas emissions. This can alleviate the increasingly tense energy problems in the world to a certain extent and truly achieve zero emissions and resource utilization of pollutants.

[0023] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the incineration plant leachate treatment system based on ecological technology of the utility model.

[0025] In the figure: 1. Leachate; 2. Water storage tank; 3. Water pipe; 4. Peristaltic pump; 5. Valve; 6. Plexiglas column barrel; 7. Water distribution screen; 8. Overlying water layer 1; 9. Quartz sand layer; 10. Biochar layer; 11. Gravel layer 1; 12. Sample outlet; 13. Water hyacinth; 14. Overlying water layer 2; 15. Fine sand layer; 16. Filling layer; 17. Gravel layer 2; 18. Inoculation tube; 19. Polypropylene drum; 20. Cathode carbon felt; 21. Anode carbon felt; 22. Paperless recorder; 23. Adjustable resistance box; 24. Water outlet; 25. Single-core copper wire. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0027] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used by technicians in the technical field of the present invention. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] Please refer to the attached Figure 1 A system for treating leachate from an incineration plant based on ecological technology includes a CW-MFC system formed by coupling a water supply system, a percolation tank system, an artificial wetland system, and a microbial fuel cell system. Water pipes 3 are arranged between the water supply system, the percolation tank system, and the CW-MFC system, and each of the water pipes 3 is provided with a peristaltic pump 4 and a valve 5.

[0030] The above structure constructs a pretreatment system, namely a percolation tank system and a treatment system of an artificial wetland microbial fuel cell system. By utilizing the filler with a high specific surface area in the percolation tank and the microorganisms colonized on the substrate, high-concentration pollutants are degraded under appropriate hydraulic retention time conditions, while removing a large amount of suspended solids, so that the effluent enters the artificial wetland microbial fuel cell system again to achieve purification of the remaining difficult-to-degrade pollutants. Therefore, this combined process not only overcomes the defects of the existing technology, but also gives full play to the hierarchical degradation and full utilization of different pollutants by each system, and ultimately realizes the recovery of energy substances in the form of electrical energy.

[0031] The water supply system includes a water storage tank 2, wherein the water storage tank 2 is provided with landfill leachate 1, and the leachate tank system includes an organic glass column barrel 6, wherein the organic glass column barrel 6 is provided with a first matrix with microorganisms colonized on the surface, wherein the first matrix includes a gravel layer 11, a biochar layer 10, a quartz sand layer 9, and an overlying water layer 8, which are sequentially distributed from bottom to top. The gravel layer 11 is filled with gravel with a particle size of 9 to 12 mm, the biochar layer 10 is filled with coconut shell biochar with a particle size of 1 to 2 mm, and the quartz sand layer 9 is filled with quartz sand with a particle size of 0.5 to 1 mm. The height of the gravel layer 11 and the overlying water layer 8 are both 5 cm, and the height of the biochar layer 10 and the quartz sand layer 9 are both 20 cm.

[0032] The CW-MFC system includes a polypropylene barrel 19, and the upper ends of the polypropylene barrel 19 and the organic glass column barrel 6 are both provided with a water distribution screen plate 7. The polypropylene barrel 19 is provided with a second matrix for microbial colonization, plants, inoculation tubes 18, electrodes, an adjustable resistance box 23, a single-core copper wire 25 and a paperless recorder 22. The adjustable resistance box 23 and the paperless recorder 22 are connected in parallel to the outside of the polypropylene barrel 19 by the single-core copper wire 25. The adjustable resistance box 23 is 1000 Ω adjustable resistance box, a water outlet 24 is provided on one side of the bottom of the polypropylene barrel 19, the plant is water hyacinth 13, and the water hyacinth 13 is located in the overlying water layer 2 14, the second matrix includes a gravel layer 2 17, a filler layer 16, a fine sand layer 15, and an overlying water layer 2 14, which are distributed from bottom to top, the filler layer 16 is composed of an activated carbon layer or a sponge iron layer, and the bottom end of the inoculation tube 18 with open ends is located in the filler layer 16, and the top extends out of the overlying water layer 2 14, the gravel layer 2 17 is filled with gravel with a particle size of 9 to 12 mm, the filler layer 16 is filled with activated carbon or sponge iron with a particle size of 5 to 10 mm, the fine sand layer 15 is filled with fine sand with a particle size of 0.25 to 0.5 mm, the height of the gravel layer 2 17 is 4 cm, the height of the fine sand layer 15 and the overlying water layer 2 14 are both 3 cm, and the height of the activated carbon or sponge iron is 10 cm;

[0033] The bottom of the organic glass column barrel 6 and the water storage tank 2 are both provided with a sample outlet 12, and the sample outlet 12 is connected to one end of the corresponding water pipe 3. The electrode includes an anode carbon felt 21 and a cathode carbon felt 20. The anode carbon felt 21 is located in the packing layer 16, and the cathode carbon felt 20 is located at the gas-liquid interface of the overlying water layer 2 14. The anode carbon felt 21 and the cathode carbon felt 20 are both annular carbon felt structures. The distance between the anode carbon felt 21 and the cathode carbon felt 20 is 12 cm. The inoculation tube 18 is a transparent silicone hose with an outer diameter of 1.2 cm, an inner diameter of 0.8 cm, and a length of 20 cm.

[0034] The specific operations are as follows:

[0035] Step 1: Build the infiltration tank system and the CW-MFC system with two types of substrates;

[0036] Step 2: The leachate 1 in the water storage tank 2 is transported to the organic glass column barrel 6 along the water pipe 3 through the peristaltic pump 4. The injection volume is about 5.5 L and the HRT is about 45 days. During this period, the CW-MFC system is inoculated with microorganisms. Specifically, the inoculation liquid is obtained from the supernatant of the sludge in the secondary sedimentation tank of a sewage treatment plant in Wuhu after standing. 50 mL of the sludge supernatant is taken into a cylinder bottle, and 1 g of C6H 12 Dissolve O6, 0.15 g NH4Cl, and 0.03 g KH2PO4 in 20 mL of ultrapure water. Mix the solution and add it to a sealed vial. Place it in a constant temperature shaker at 37°C and 120 rpm for 2 days. Inoculate the inoculum through the inoculation tube 18 connected to the anode twice a week. Replace the nutrient solution once a week. When the voltage displayed on the paperless recorder 22 stabilizes, it means that the CW-MFC system has successfully formed a biofilm.

[0037] Step 3: After about 45 days of HRT in the organic glass column barrel 6, the peristaltic pump 4 is turned on to transport the water out of the organic glass column barrel 6 to the polypropylene drum 19 of the CW-MFC system through the peristaltic pump 4, and then passes through the cathode carbon felt 20, the fine sand layer 15, the activated carbon layer or sponge iron layer, the anode carbon felt 21, and the gravel layer 17 in sequence;

[0038] Step 4: After the CW-MFC system has been in operation for approximately 45 days, the effluent is discharged from the outlet 24 at the bottom of the CW-MFC system.

[0039] Step 5: The entire combined process device is placed in a constant temperature indoor laboratory at 25±3°C. The organic glass column barrel 6 of the CW-MFC system is wrapped with black plastic film to prevent algae from growing.

[0040] In Example 1, the infiltration tank is a plexiglass column barrel 6 with a diameter of 21 cm and a height of 60 cm, with an effective volume of approximately 15 L. From top to bottom, it comprises a water distribution sieve plate 7, an overlying water layer 8 (5 cm), a quartz sand layer 9 (20 cm), a biochar layer 10 (20 cm), and a gravel layer 11 (5 cm). The treatment object is the raw liquid in the incineration plant landfill leachate regulating tank. The hydraulic retention time is 45 days. Various pollution indicators are measured every three days. The water effluent from the plexiglass column barrel 6 then enters the CW-MFC system device.

[0041] The CW-MFC system with activated carbon as the filler layer 16 is a polypropylene drum 19 with an upper diameter of 21 cm, a lower diameter of 19 cm, and a height of 21 cm. From top to bottom, it contains a water distribution screen plate 7, a cathode carbon felt 20, an overlying water layer 14, a fine sand layer 15, a filler layer 16, an anode carbon felt 21, and a gravel layer 17. The plant is water hyacinth 13, and the adjustable resistance box 23 is 1000 Ω. The treatment object is the effluent from the infiltration pond. The hydraulic retention time is 45 days. The pollution indicators are measured every three days. The monitoring data are shown in Table 1 below.

[0042] Table 1 Removal rates of various pollutants in the CW-MFC system combined process using activated carbon as filler

[0043]

[0044] As shown in Table 1, three months of experimental operation showed that the combined process had a good purification effect on incineration plant leachate, with a pollutant removal efficiency of 73% to 99%. This may be because the activated carbon and biochar have a large specific surface area and high electrical potential, which is conducive to biofilm formation, thereby increasing the biofilm biomass, resulting in high removal efficiency. At the same time, the CW-MFC influent COD provides a carbon source, eliminating the need for an external carbon source, and achieving good power generation. The system has a stable output voltage of approximately 500 mV.

[0045] In Example 2, the filler layer 16 of the CW-MFC system was changed from activated carbon to sponge iron. Other conditions were the same as in Example 1. The monitoring data are shown in Table 2. The removal efficiency of each pollutant was 55% to 99%, and the stable output voltage of the system was about 600 mV.

[0046] Table 2 Removal rates of various pollutants in the sponge iron CW-MFC system combination process

[0047]

[0048] The above description of the present invention is illustrative in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. An incineration plant leachate treatment system based on ecological technology, characterized by , comprising a CW-MFC system formed by coupling a water supply system, a percolation tank system, an artificial wetland system and a microbial fuel cell system, wherein water pipes (3) are provided between the water supply system, the percolation tank system and the CW-MFC system, and a peristaltic pump (4) is provided on each of the water pipes (3).

2. The incineration plant leachate treatment system based on ecological technology according to claim 1 is characterized in that: The water supply system comprises a water storage tank (2), wherein landfill leachate (1) is arranged in the water storage tank (2).

3. The incineration plant leachate treatment system based on ecological technology according to claim 1 is characterized in that: The infiltration tank system includes an organic glass column barrel (6), wherein a first matrix with microorganisms colonizing the surface is arranged in the organic glass column barrel (6), and the first matrix includes a gravel layer (11), a biochar layer (10), a quartz sand layer (9) and an overlying water layer (8) distributed in sequence from bottom to top.

4. The incineration plant leachate treatment system based on ecological technology according to claim 1 is characterized in that: The CW-MFC system includes a polypropylene barrel (19), wherein a second matrix for microbial colonization, plants, an inoculation tube (18), electrodes, an adjustable resistance box (23), a single-core copper wire (25) and a paperless recorder (22) are arranged in the polypropylene barrel (19), and the adjustable resistance box (23) and the paperless recorder (22) are connected in parallel to the outside of the polypropylene barrel (19) by the single-core copper wire (25), and a water outlet (24) is provided on one side of the bottom of the polypropylene barrel (19).

5. The incineration plant leachate treatment system based on ecological technology according to claim 4 is characterized in that: The plant is water hyacinth (13).

6. The incineration plant leachate treatment system based on ecological technology according to claim 4 is characterized in that: The second matrix includes a gravel layer (17), a filler layer (16), a fine sand layer (15), and an overlying water layer (14) which are sequentially distributed from bottom to top. The filler layer (16) is composed of an activated carbon layer or a sponge iron layer. The inoculation tube (18) with both ends open has its bottom end located in the filler layer (16) and its top end extending out of the overlying water layer (14).

7. The incineration plant leachate treatment system based on ecological technology according to claim 3 is characterized in that: The bottoms of the organic glass column barrel (6) and the water storage tank (2) are both provided with sample outlets (12), and the sample outlets (12) are connected to one end of a corresponding water pipe (3).

8. The incineration plant leachate treatment system based on ecological technology according to claim 4 is characterized in that: The electrode comprises an anode carbon felt (21) and a cathode carbon felt (20), wherein the anode carbon felt (21) is located in the filler layer (16), and the cathode carbon felt (20) is located at the gas-liquid interface of the second overlying water layer (14), and both the anode carbon felt (21) and the cathode carbon felt (20) are annular carbon felt structures.

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