Reactor for enhancing anaerobic digestion methane production capacity by adopting biogas reflux combined with microbial electrolysis cell (MEC)

Abstract

The invention relates to a reactor for enhancing anaerobic digestion methane production capacity by adopting biogas reflux combined with a microbial electrolysis cell (MEC). The reactor comprises the MEC and a biogas reflux system. The biogas backflow system comprises a secondary biogas separation tank, a methane collection tank and a carbon dioxide collection tank; the microbial electrolytic tank comprises a biological anode plate and a biological cathode plate which are connected in series by two vertically arranged leads, and can strengthen microorganisms, treatment load and stability; and the microbial electrolysis cell is connected with the biogas separation tank through a gas pump and a biogas collection pipe. Compared with the prior art, the anaerobic digestion system of the biogas reflux combined microbial electrolysis cell can relieve acidification and provide a mild environment suitable for microbial growth; marsh gas can be separated and purified, so that the marsh gas is upgraded and purified, and the application of the marsh gas as renewable energy instead of fossil fuel is promoted; biomass energy is recycled to the maximum extent, carbon emission is reduced, and the ecological environment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of anaerobic digestion treatment, and in particular to a reactor which adopts biogas reflux combined with a microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion. Background Art

[0002] Biomass organic solid waste refers to organic solid waste derived from organisms (mainly plants, animals and microorganisms), which has the characteristics of high organic matter content, strong biodegradability and large differences in water content. At present, my country's biomass organic solid waste production is huge, among which the production of food waste is considerable. There are various ways to treat biomass organic solid waste, including landfill, incineration, composting and anaerobic digestion. Although there are various treatment methods, there are still some shortcomings. The harmless treatment technology needs to be improved and the resource technology should also be continuously developed.

[0003] Anaerobic digestion (AD) is a process in which microorganisms decompose organic matter. It can convert complex organic compounds into biogas mainly composed of 50-80% methane and 15-50% carbon dioxide. It is economically and technically feasible in treating biomass organic solid waste and has been widely used in recent years. However, the carbon dioxide emitted will increase greenhouse gas emissions, thereby aggravating the greenhouse effect and having adverse effects on human health and the ecological environment. In addition, the calorific value of the biogas produced is low because it contains not only methane, but also carbon dioxide and other impurities, which limits its application as a renewable energy source to replace fossil fuels.

[0004] Microbial electrolysis cells can combine electroactive microorganisms with electrochemical stimulation to complete carbon dioxide electromethanation on the bioanode through electroactive microorganisms, thereby reducing carbon dioxide emissions and achieving in-situ biogas purification. However, there are few studies on the efficient methanation of biomass organic solid waste by microbial electrolysis cells combined with biogas reflux. Therefore, further research should be conducted to improve the above problems, convert more carbon dioxide into methane, reduce carbon dioxide emissions, and alleviate the greenhouse effect; separate and purify biogas to upgrade and purify it; and establish a robust anaerobic digestion system with high buffering capacity to efficiently treat various organic wastes. Summary of the invention

[0005] The purpose of the present invention is to improve the above problems and provide a reactor that uses biogas reflux combined with a microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion, which is used to treat organic solid waste with a high organic load and separate and purify the generated biogas.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The purpose of the present invention is to protect the structure of a reactor that uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion. The reactor that uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion includes a microbial electrolysis cell (MEC) and a biogas reflow system; the microbial electrolysis cell (MEC) and the biogas reflow system are connected by an air pump.

[0008] The microbial electrolysis cell comprises a biological anode plate and a biological cathode plate, wherein the biological anode plate and the biological cathode plate are connected in series by two vertically arranged wires; wherein the two vertically arranged wires are respectively connected to the positive electrode and the negative electrode of a voltage-stabilized DC power supply.

[0009] The voltage-stabilized DC power supply provides electric energy to the microbial electrolysis cell through the conductor assembly, thereby driving the microbial electrolysis cell to enrich electroactive microorganisms, thereby enhancing the anaerobic digestion load and system stability.

[0010] The biogas reflux system includes a secondary biogas separation tank, a methane collection tank and a carbon dioxide collection tank; the secondary biogas separation tank can achieve a more efficient separation effect, so that the methane purity in the separated biogas is higher; the carbon dioxide collection tank is connected to the biogas separation tank through a conduit, and the carbon dioxide separation tank is used to avoid low carbon dioxide concentration in the biogas separation tank, so that the enriched carbon dioxide can be better refluxed to the microbial electrolysis cell through an air pump; the methane collection tank is connected to the biogas separation tank through a conduit for storing methane with higher purity.

[0011] Preferably, the secondary biogas separation tank comprises a carbon dioxide separation mixed matrix membrane, and a carbon dioxide-philic zeolite is added to the membrane to allow more carbon dioxide to pass through the membrane into the enricher, thereby achieving efficient separation of carbon dioxide and methane in biogas.

[0012] Furthermore, the microbial electrolysis cell and the biogas separation tank are connected by an air pump, a biogas collection pipe and a conduit. The biogas collection pipe is used to collect the biogas generated by the microbial electrolysis cell and transmit it to the biogas reflow system; the air pump is used to recycle the carbon dioxide separated by the biogas separation tank and enriched by the carbon dioxide collection tank into the microbial electrolysis cell.

[0013] Furthermore, the microbial electrolysis cell also includes a reactor tank, a stirring motor, and a stirring paddle; the stirring paddle runs through the reactor tank; and the output end of the stirring motor is connected to the stirring paddle to drive the stirring paddle to rotate.

[0014] Furthermore, the microbial electrolysis cell also includes a feed inlet, a discharge port, and a biogas collection pipe; the feed inlet, the discharge port, and the biogas collection pipe are all arranged on the reactor tank body.

[0015] Furthermore, the discharge port is located on one side of the bioanode plate.

[0016] Furthermore, the external DC power supply voltage is 0.4V-1.0V.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) Anaerobic digestion in microbial electrolysis cells can provide additional energy for microbial metabolism by applying external voltage, accelerate the decomposition of organic matter and the generation of methane, and thus improve energy recovery efficiency. In addition, the application of power changes the living environment and metabolic pathways of microorganisms, allowing microorganisms to more effectively attack and decompose complex organic molecular structures, improve the degradation efficiency and treatment effect of organic solid waste, and expand the types and scope of organic waste that can be treated.

[0019] 2) The biogas reflow system can allow the carbon dioxide in the biogas to re-participate in the anaerobic digestion process, providing more carbon sources for methanogens, thereby promoting the growth and metabolism of methanogens and increasing the production of biogas; it can play a certain buffering role on the pH value of the anaerobic digestion system; and the reflowed biogas will produce bubbles when entering the anaerobic digestion reactor. These bubbles can drive the flow of digestive fluid during the rising process, thereby promoting the mixing of materials and making the contact between the substrate and microorganisms more complete, which is beneficial to improving the degradation efficiency of organic matter and accelerating the reaction rate of anaerobic digestion.

[0020] 3) Gas recirculation realizes the resource reuse of carbon dioxide and other components in biogas, reduces the emission of greenhouse gases such as carbon dioxide, and has positive significance for environmental protection; the methane in biogas is upgraded in situ, and methane with higher purity can be used as a clean energy to replace fossil fuels, which is environmentally friendly; at the same time, it also improves the resource utilization efficiency and economic benefits of the entire anaerobic digestion system, which meets the requirements of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a reactor that uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion in an embodiment.

[0022] The numbers in the figure show:

[0023] 1. Stirring motor; 2. Feed inlet; 3. Stirring paddle; 4. Bioanode plate; 5. Biocathode plate; 6. Discharge port; 7. Biogas collection pipe; 8. Air pump; 9. Carbon dioxide collection tank; 10. First biogas separation tank; 11. Second biogas separation tank; 12. Carbon dioxide separation mixed matrix membrane; 13. Methane collection tank; 14. Regulated DC power supply. DETAILED DESCRIPTION

[0024] Features such as component models, material names, connection structures, control methods, etc. that are not clearly stated in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0025] As attached Figure 1 As shown, a reactor that uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methanogenic capacity of anaerobic digestion includes a microbial electrolysis cell (MEC) and a biogas reflow system, which are connected via an air pump 8 and a biogas collection pipe 7.

[0026] As attached Figure 1 As shown, the microbial electrolysis cell (MEC) includes a biological anode plate 4 and a biological cathode plate 5 connected in series by two vertically arranged wires, wherein the wires are respectively connected to the positive and negative electrodes of a regulated DC power supply 14, and the regulated DC power supply provides electrical energy to the microbial electrolysis cell through the wire assembly, thereby driving the microbial electrolysis cell to enrich electroactive microorganisms, enhance the anaerobic digestion load and system stability.

[0027] As attached Figure 1 As shown, the reaction tank body of the microbial electrolysis cell (MEC) is connected to the feed port 2, which is used for feeding; the stirring motor 1 runs through the reaction tank body and is connected to the stirring paddle 3 to stir the mixed matrix, thereby enhancing material transfer, promoting gas diffusion, improving microbial distribution, and improving reaction efficiency and stability; the discharge port 6 is connected to the reaction tank body to collect the reaction products.

[0028] As attached Figure 1 As shown, the biogas collecting pipe 7 is connected to the reaction tank body, and is used to collect the biogas generated on the biological cathode plate 5, and input the biogas into the first biogas separation tank 10 through a conduit. The carbon dioxide separation mixed matrix membrane 12 is inside the biogas separation tank, and is used to separate the carbon dioxide in the biogas. The separated carbon dioxide enters the carbon dioxide collecting tank 9 through the conduit, and the remaining gas enters the second biogas separation tank 11 through the conduit for the second carbon dioxide separation. The separated carbon dioxide also enters the carbon dioxide collecting tank 9, and the purified biogas enters the methane collection tank 13.

[0029] As attached Figure 1 As shown, the carbon dioxide gas enriched in the carbon dioxide collection tank 9 connected to the secondary biogas separation tank is refluxed to the biological cathode plate 5 of the microbial electrolysis cell through the air pump 8 for carbon dioxide methanation.

[0030] The specific working method of the reactor using biogas reflow combined with microbial electrolysis cell (MEC) to enhance the methane production capacity of anaerobic digestion in this technology is as follows:

[0031] First, biomass organic solid waste is introduced into the microbial electrolysis cell through the feed inlet. At the anode, electrochemically active microorganisms convert organic matter into carbon dioxide, protons and electrons through oxidation reactions. Protons reach the cathode through the electrolyte and combine with electrons to produce hydrogen. Methanogens use the electrons at the cathode and the produced hydrogen to reduce carbon dioxide to methane.

[0032] The biogas produced in the microbial electrolysis cell enters the biogas reflux system through the biogas collection pipe, passes through the primary biogas separation tank, and the carbon dioxide enters the carbon dioxide collection tank through the carbon dioxide separation mixed matrix membrane; the remaining gas enters the secondary biogas separation tank through the conduit for further separation, and the separated carbon dioxide also enters the carbon dioxide collection tank. The methane purity in the biogas after separation is higher and enters the methane collection tank.

[0033] The carbon dioxide in the carbon dioxide collection tank flows back to the cathode of the microbial electrolysis cell through an air pump, and the carbon dioxide is reduced to methane on the cathode surface, thereby achieving efficient methanogenesis.

Claims

1. A reactor that uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methanogenic capacity of anaerobic digestion, characterized in that: The reactor adopting biogas reflow combined with microbial electrolysis cell (MEC) to enhance the methanogenic capacity of anaerobic digestion comprises a microbial electrolysis cell (MEC) and a biogas reflow system; The microbial electrolysis cell comprises a biological anode plate (4) and a biological cathode plate (5) connected in series by two vertically arranged wires; The biogas reflow system comprises a secondary biogas separation tank, a methane collection tank (13) and a carbon dioxide collection tank (9); wherein the secondary biogas separation tank comprises a first biogas separation tank (10) and a second biogas separation tank (11); The microbial electrolytic cell (MEC) and the biogas reflow system are connected via an air pump (8) and a biogas collection pipe (7).

2. A reactor for enhancing the methane production capacity of anaerobic digestion by using biogas reflow combined with a microbial electrolysis cell (MEC) according to claim 1, characterized in that: Two vertically arranged wires are respectively connected to the positive electrode and the negative electrode of a voltage-stabilized DC power supply (14), and the power supply voltage is 0.4V-1.0V.

3. A reactor for enhancing the methane production capacity of anaerobic digestion by using biogas reflux combined with a microbial electrolysis cell (MEC) according to claim 1, characterized in that: The second biogas separation tank (11) and the methane collection tank (12) in the biogas reflow system are connected via a conduit; The second biogas separation tank (11) and the carbon dioxide collection tank (9) are connected via a conduit; The first biogas separation tank (10) and the second biogas separation tank (11) are also connected via a conduit.

4. A reactor for enhancing the methane production capacity of anaerobic digestion by using biogas reflow combined with a microbial electrolysis cell (MEC) according to claim 1, characterized in that: The methane and carbon dioxide separation in the biogas separation tank uses a carbon dioxide separation mixed matrix membrane (12).

5. The reactor according to claim 1, which uses biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methanogenic capacity of anaerobic digestion, is characterized in that: The microbial electrolysis cell also includes a reaction tank, a stirring motor (1), and a stirring paddle (3); The stirring blade (3) penetrates the reactor tank; The output end of the stirring motor (1) is connected to the stirring paddle (3).

6. According to claim 5, a reactor using biogas reflow combined with a microbial electrolysis cell (MEC) to enhance the methanogenic capacity of anaerobic digestion, characterized in that: The microbial electrolysis cell further comprises a feed inlet (2), a discharge outlet (6), and a biogas collection pipe (7); The feed port (2), the discharge port (6) and the biogas collection pipe (7) are all arranged on the reactor tank body.

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