A device and method for enhancing the rate and purity of methanogenesis by electrofermentation

Abstract

The application discloses a device and method for improving the rate and purity of methanogenesis by electrofermentation, and belongs to the technical field of energy and environment. The device integrates the designs of a biological fermentation reactor, an electrochemical workstation and a tubular electrolytic cell. By implementing a precise dynamic potential regulation strategy, the biological fermentation reaction system is optimized, the rate and purity of methanogenesis by electrofermentation are improved, and the ability of the system to treat high-concentration organic wastewater is enhanced. The device connects the anode and cathode of the tubular electrolytic cell to the connecting posts of the counter electrode and working electrode of the electrochemical workstation, respectively, and realizes the accuracy of potential measurement through a reference electrode. With the intelligent control of a computer, the potential of the biological fermentation reactor is dynamically adjusted, the degradation capacity of the system for organic wastewater is effectively improved, especially for high-COD-value wastewater, and the methanation process is accelerated, so that the reaction cycle is significantly shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy environment, in particular to a device and method for improving the methane production rate and purity of electric fermentation. BACKGROUND

[0002] Anaerobic digestion technology can convert organic matter in wastewater into biogas, thereby realizing the resource utilization of wastewater. However, in the face of the increasingly serious problem of high-concentration organic wastewater in water pollution, the traditional anaerobic digestion process encounters many challenges in treating such wastewater, including the inhibitory effect of intermediate metabolites (such as the accumulation of volatile fatty acids), slow reaction start, poor adaptability to low-temperature environment, and fluctuation of system stability, etc. These problems are often difficult to fundamentally solve by simply optimizing the parameters of the traditional process.

[0003] In recent years, the innovative integration of anaerobic digestion and electrochemical technology has derived electric fermentation technology, which opens up a new era for the treatment of high-concentration organic wastewater and efficient resource recovery, and is expected to significantly alleviate many bottlenecks in the traditional anaerobic digestion process. Electric fermentation technology not only improves the content of methane in biogas, but also accelerates the hydrolysis and acidification process, effectively reduces the inhibitory effect of volatile fatty acid accumulation on the methanogenesis process, and enhances the overall anaerobic digestion efficiency, providing a more stable and efficient solution for wastewater treatment and energy recovery.

[0004] In the research and practice of electric fermentation technology, constant potential or constant current is usually used to supply gas in situ to realize the conversion of CO2 in biogas to methane, thereby improving the purity and yield of biogas. However, the volume content of CO2 in the biogas produced by anaerobic digestion is dynamically changing and gradually decreasing. Using constant potential or constant current control, there are often problems of insufficient or excessive hydrogen supply. Insufficient hydrogen supply cannot fully convert CO2 to methane. Excessive hydrogen supply not only causes energy waste, but also

[0005] inhibits hydrolysis and acidification, thereby inhibiting methane production.

[0006] Therefore, establishing in-situ detection of CO2 in anaerobic fermentation biogas and dynamically adjusting the potential or current of the electrode of the electric fermentation system according to the dynamic change of the CO2 content in the biogas can achieve appropriate supply of electrolytic hydrogen, which can better realize in-situ purification of biogas and improve the methanogenesis rate. However, there is still a lack of such electric fermentation device and control method. SUMMARY

[0007] The purpose of the present application is to provide a device and method for improving the methane production rate and purity of electric fermentation, to overcome the problem of insufficient or excessive hydrogen supply in the prior art using constant potential or constant current control.

[0008] The application solves the above technical problems through the following technical solutions:

[0009] The device for improving the rate and purity of methanogenesis in electrofermentation comprises a biological fermentation reactor, a stirring device, a tubular electrolytic cell, a reference electrode, a first gas buffer bottle, a carbon dioxide sensor, an electrochemical workstation, and a gas collection device.

[0010] The biological fermentation reactor comprises an inner cavity and a top cover, and the stirring device, the tubular electrolytic cell, and the reference electrode are arranged in the inner cavity and pass through the top cover. The tubular electrolytic cell comprises, from the inside to the outside, an anode, a cation exchange membrane, and a cathode. The top cover of the biological fermentation reactor is provided with a first gas outlet, and the first gas outlet is sequentially connected to the first gas buffer bottle, the carbon dioxide sensor, and the gas collection device. The carbon dioxide sensor is further connected to the electrochemical workstation through a computer.

[0011] The electrochemical workstation comprises a counter electrode terminal, a working electrode terminal, and a reference electrode terminal. The counter electrode terminal is connected to the anode of the tubular electrolytic cell, the working electrode terminal is connected to the cathode of the tubular electrolytic cell, and the reference electrode terminal is connected to the reference electrode. The electrochemical workstation is used for dynamically regulating and controlling the input cathode potential of the biological fermentation reactor.

[0012] The device for improving the rate and purity of methanogenesis in electrofermentation further comprises a gas circulation device, which comprises a circulating gas pump, a second gas buffer bottle, and a micro-nano aerator. The top cover of the biological fermentation reactor is provided with a gas inlet and a second gas outlet, and the gas circulation device is sequentially connected to the second gas buffer bottle, the circulating gas pump, the gas inlet, and the micro-nano aerator through the second gas outlet.

[0013] Further, the device for improving the rate and purity of methanogenesis in electrofermentation further comprises a pH electrode arranged in the inner cavity of the biological fermentation reactor, which is used for monitoring the pH value of the liquid in the biological fermentation reactor.

[0014] Further, the anode of the tubular electrolytic cell is a cylindrical titanium mesh, and the cathode is a cylindrical stainless steel mesh.

[0015] Further, the reference electrode is an Ag / AgCl electrode, and the built-in solution of the reference electrode is a saturated potassium chloride solution.

[0016] Further, the biological fermentation reactor is a CSTR reactor or a gas-lift bubble column.

[0017] A method for improving the rate and purity of methanogenesis in electrofermentation is provided, which uses any of the above devices to improve the rate and purity of methanogenesis in electrofermentation.

[0018] Further, the method comprises the following steps:

[0019] Step one, inoculate anaerobic sludge bacteria into a biogas fermentation reactor containing organic wastewater, start the stirring device, and generate biogas through anaerobic digestion, wherein the biogas includes methane and carbon dioxide, and the pH value in the biogas fermentation reactor is maintained at 6.5-8 during the anaerobic digestion process;

[0020] Step two, detect the volume content of carbon dioxide in the biogas through a carbon dioxide sensor, convert the volume content of carbon dioxide into an electrical signal through a computer and transmit it to an electrochemical workstation, and collect the biogas through a gas collection device;

[0021] Step three, according to the dynamic potential regulation strategy, regulate the input cathode potential through the electrochemical workstation to improve the methanogenic rate and purity of electrofermentation.

[0022] Further, in step three, the dynamic potential regulation strategy is:

[0023] When the volume content of carbon dioxide is greater than 30%, set the input cathode potential to -1.6V through the electrochemical workstation; when the volume content of carbon dioxide is between 20% and 30%, set the input cathode potential to -1.5V through the electrochemical workstation; when the volume content of carbon dioxide is between 15% and 20%, set the input cathode potential to -1.4V through the electrochemical workstation; when the volume content of carbon dioxide is between 10% and 15%, set the input cathode potential to -1.3V through the electrochemical workstation; when the volume content of carbon dioxide is between 5% and 10%, set the input cathode potential to -1.2V through the electrochemical workstation; and when the volume content of carbon dioxide is between 0 and 5%, set the input cathode potential to -1.0V through the electrochemical workstation.

[0024] Further, the organic wastewater is potato starch industrial wastewater.

[0025] Further, the anaerobic sludge bacteria are hydrogenotrophic methanogens and acetoclastic methanogens, the inoculation rate of the anaerobic sludge bacteria is 15%, and the mass ratio of the hydrogenotrophic methanogens to the acetoclastic methanogens is 1:1.

[0026] Compared with the prior art, the positive progress effect of the present application is that:

[0027] The device for improving the methane production rate and purity of electric fermentation disclosed in the application skillfully combines the designs of a biological fermentation reactor, an electrochemical workstation and a tubular electrolytic cell, optimizes the biological fermentation reaction system by implementing a precise dynamic potential regulation strategy, and not only improves the methane production rate and purity of electric fermentation, but also enhances the ability of the system to handle high-concentration organic wastewater. In the device, the counter electrode terminal and the working electrode terminal of the electrochemical workstation are connected to the anode and the cathode of the tubular electrolytic cell respectively, and the accuracy of potential measurement is realized through the reference electrode. With the intelligent control of the computer, the input cathode potential of the biological fermentation reactor is dynamically adjusted, which effectively improves the degradation ability of the system to organic wastewater, especially for high-COD (chemical oxygen demand) value wastewater, and at the same time, accelerates the methanation process and significantly shortens the reaction cycle.

[0028] Further, the device for improving the methane production rate and purity of electric fermentation disclosed in the application adopts a tubular electrolytic cell as the core component, and the internal structure is carefully arranged by a cylindrical titanium mesh anode, a cation exchange membrane and a cylindrical stainless steel mesh cathode. Not only does it effectively prevent the formation of biological membranes and accelerate the reaction start-up speed, but also it reduces the operating cost by selecting economical and efficient electrode materials. In addition, the device also integrates a gas circulation system, which uses a micro-nano aeration head to realize secondary fermentation of the gas, further improving the fermentation efficiency and methane yield.

[0029] The application also discloses a method for improving the methane production rate and purity of electric fermentation, based on the dynamic potential regulation technology of real-time carbon dioxide content monitoring. By intelligently adjusting the input cathode potential or current through the electrochemical workstation, fine control of the input cathode potential of the biological fermentation reactor is realized, avoiding the problem of intermediate metabolite inhibition caused by excessively high hydrogen partial pressure in the traditional constant potential mode, and also solving the problem of insufficient electron supply and difficulty in effectively fixing carbon dioxide in biogas at low potential. At the same time, the pH value in the biological fermentation reactor is maintained in the range of 6.5 to 8, which not only provides an ideal living environment for methanogens, but also promotes the forward progress of the acid production process, thereby comprehensively improving the methane generation efficiency and purity. Experimental data show that the method can directly handle organic wastewater with a COD (chemical oxygen demand) value of up to 12000 mg·L⁻¹, and at the same time, the methanation process is significantly accelerated, and the reaction cycle is greatly shortened, fully verifying the excellent performance of the application in improving the methane production rate and purity of electric fermentation. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the application. The schematic embodiments of the application and their descriptions are used to explain the application, and do not constitute an improper limitation on the application.

[0031] Figure 1 is a schematic diagram of the device of the application;

[0032] Wherein: 1-biological fermentation reactor; 2-tubular electrolytic cell; 3-reference electrode; 4-micro-nano aeration head; 5-stirring device; 6-circulating gas pump; 7-1 first gas buffer bottle; 7-2 second gas buffer bottle; 8-electrochemical workstation; 9-carbon dioxide sensor; 10-computer; 11-gas collection device. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0035] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0036] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is used, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0037] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0038] In the description of the embodiments of the present application, it also needs to be explained that, unless otherwise explicitly specified and limited, if the terms of “setting”, “installing”, “connecting”, “connecting” appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected, or can be mechanically connected, or can be electrically connected, or can be directly connected, or indirectly connected through an intermediate medium, or can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] The present application will be further described in detail below in combination with the drawings, which are an explanation of the present application rather than a limitation.

[0040] Embodiment one

[0041] Reference Figure 1 A device for improving the rate and purity of methanogenesis by electrofermentation, comprising a biological fermentation reactor 1, a stirring device 5, a tubular electrolytic cell 2, a reference electrode 3, a first gas buffer bottle 7-1, a carbon dioxide sensor 9, an electrochemical workstation 8 and a gas collection device 11;

[0042] The biological fermentation reactor 1 comprises an inner cavity and a top cover, and the stirring device 5, the tubular electrolytic cell 2 and the reference electrode 3 are arranged in the inner cavity and pass through the top cover. The tubular electrolytic cell 2 comprises, from the inside to the outside, an anode, a cation exchange membrane and a cathode. The top cover of the biological fermentation reactor 1 is provided with a first gas outlet, and the first gas outlet is connected to the first gas buffer bottle 7-1, the carbon dioxide sensor 9 and the gas collection device 11 in sequence. The carbon dioxide sensor 9 is further connected to the electrochemical workstation 8 through the computer 10;

[0043] The electrochemical workstation 8 comprises a counter electrode terminal, a working electrode terminal and a reference electrode terminal. The counter electrode terminal is connected to the anode of the tubular electrolytic cell 2, the working electrode terminal is connected to the cathode of the tubular electrolytic cell 2, and the reference electrode terminal is connected to the reference electrode 3, which is used to dynamically control the input cathode potential of the biological fermentation reactor 1;

[0044] The device for improving the rate and purity of methanogenesis by electrofermentation further comprises a gas circulation device, which comprises a circulating gas pump 6, a second gas buffer bottle 7-2 and a micro-nano aerator 4. The top cover of the biological fermentation reactor 1 is provided with a gas inlet and a second gas outlet, and the gas circulation device is connected to the second gas buffer bottle 7-2, the circulating gas pump 6, the gas inlet and the micro-nano aerator 4 in sequence through the second gas outlet. The device further comprises a pH control system, which comprises a pH electrode arranged in the inner cavity of the biological fermentation reactor 1 and used to monitor the pH value of the liquid in the biological fermentation reactor 1. The liquid is organic wastewater inoculated with anaerobic sludge bacteria in the biological fermentation reactor 1.

[0045] The tubular electrolytic cell 2 has a cylindrical titanium mesh as an anode and a cylindrical stainless steel mesh as a cathode; the reference electrode 3 is an Ag / AgCl electrode, and the built-in solution of the reference electrode 3 is a saturated potassium chloride solution; and the biological fermentation reactor 1 is a CSTR reactor or a gas-lift bubble column.

[0046] A method for improving the rate and purity of electric fermentation to produce methane, comprising the following steps:

[0047] Step one, inoculate anaerobic sludge strains into the biological fermentation reactor 1 containing organic wastewater, start the stirring device 5, and generate biogas through anaerobic digestion, wherein the biogas includes methane and carbon dioxide, and the pH value in the biological fermentation reactor 1 is maintained at 6.5-8 during the anaerobic digestion process;

[0048] Step two, detect the volume content of carbon dioxide in the biogas through the carbon dioxide sensor 9, and convert the volume content of carbon dioxide into an electrical signal through the computer 10 and transmit it to the electrochemical workstation 8;

[0049] Step three, according to the dynamic potential regulation strategy, regulate the input cathode potential through the electrochemical workstation 8 to improve the rate and purity of electric fermentation to produce methane.

[0050] In step three, the dynamic potential regulation strategy is:

[0051] When the volume content of carbon dioxide is greater than 30%, set the input cathode potential to -1.6 V through the electrochemical workstation 8; when the volume content of carbon dioxide is between 20% and 30%, set the input cathode potential to -1.5 V through the electrochemical workstation 8; when the volume content of carbon dioxide is between 15% and 20%, set the input cathode potential to -1.4 V through the electrochemical workstation 8; when the volume content of carbon dioxide is between 10% and 15%, set the input cathode potential to -1.3 V through the electrochemical workstation 8; when the volume content of carbon dioxide is between 5% and 10%, set the input cathode potential to -1.2 V through the electrochemical workstation 8; and when the volume content of carbon dioxide is between 0 and 5%, set the input cathode potential to -1.0 V through the electrochemical workstation 8.

[0052] The organic wastewater is potato starch industrial wastewater, the inoculation rate of the anaerobic sludge strains is 15%, the anaerobic sludge strains are hydrogenotrophic methanogens and acetoclastic methanogens, and the mass ratio of the hydrogenotrophic methanogens to the acetoclastic methanogens is 1:1.

[0053] Example two

[0054] In the cathode electro-fermentation system of the biological fermentation reactor 1 with a volume of 1.3 L, the substrate is potato starch industrial wastewater with a COD of 6400 mg / L, the inoculum is anaerobic sludge bacteria, the inoculation rate is 15%, the anaerobic sludge bacteria are hydrogenotrophic methanogens and acetoclastic methanogens, the mass ratio of the hydrogenotrophic methanogens to the acetoclastic methanogens is 1:1, the reaction temperature is 37°, the stirring device 5 is started, biogas is generated through anaerobic digestion, the biogas includes methane and carbon dioxide, and the pH value in the biological fermentation reactor 1 is maintained at 6.5-8 during the anaerobic digestion process; the volume content of carbon dioxide in the biogas is detected by the carbon dioxide sensor 9, the volume content of carbon dioxide is converted into an electrical signal by the computer 10 and transmitted to the electrochemical workstation 8, and the biogas is collected by the gas collection device 11; the dynamic potential regulation strategy is adopted, when the volume content of carbon dioxide is greater than 30%, the input cathode potential is set to -1.6 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 20% and 30%, the input cathode potential is set to -1.5 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 15% and 20%, the input cathode potential is set to -1.4 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 10% and 15%, the input cathode potential is set to -1.3 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 5% and 10%, the input cathode potential is set to -1.2 V by the electrochemical workstation 8; and when the volume content of carbon dioxide is between 0 and 5%, the input cathode potential is set to -1.0 V by the electrochemical workstation 8.

[0055] The final cumulative methane production is 8360 mL, and the fermentation time is only 6 d. The percentage of methane in the first day of fermentation is 35%.

[0056] Comparative Example One

[0057] The difference between Example Two and Comparative Example One is that the -1.2 V constant potential control condition is adopted, the cumulative methane production is 8358 mL, the fermentation time is 20 d, and the percentage of methane in the first day of fermentation is 30%.

[0058] In comparison, the time for producing methane in Example Two is 14 d shorter than that in Comparative Example One, the reaction starts faster, and the initial percentage of methane is higher.

[0059] Example Three

[0060] In the cathode electric fermentation system of the biological fermentation reactor 1 with a volume of 20 L, the substrate is potato starch industrial wastewater with a COD of 12000 mg / L, the inoculum is anaerobic sludge bacteria, the inoculation rate is 15%, the anaerobic sludge bacteria are hydrogenotrophic methanogens and acetoclastic methanogens, the mass ratio of the hydrogenotrophic methanogens to the acetoclastic methanogens is 1:1, the reaction temperature is 37°, the stirring device 5 is started, biogas is generated through anaerobic digestion, the biogas includes methane and carbon dioxide, and the pH value in the biological fermentation reactor 1 is maintained at 6.5-8 during the anaerobic digestion process; the volume content of carbon dioxide in the biogas is detected by the carbon dioxide sensor 9, the volume content of carbon dioxide is converted into an electrical signal by the computer 10 and transmitted to the electrochemical workstation 8, and the biogas is collected by the gas collection device 11; the dynamic potential regulation strategy is adopted, when the volume content of carbon dioxide is greater than 30%, the input cathode potential is set to -1.6 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 20% and 30%, the input cathode potential is set to -1.5 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 15% and 20%, the input cathode potential is set to -1.4 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 10% and 15%, the input cathode potential is set to -1.3 V by the electrochemical workstation 8; when the volume content of carbon dioxide is between 5% and 10%, the input cathode potential is set to -1.2 V by the electrochemical workstation 8; and when the volume content of carbon dioxide is between 0 and 5%, the input cathode potential is set to -1.0 V by the electrochemical workstation 8.

[0061] The final cumulative methane production is 59351 mL, the fermentation time is 12 d, and the methane percentage contents in the first three days before fermentation are 43.03%, 65.45% and 79.33% respectively.

[0062] Comparative Example Two

[0063] The difference between Example Three and Comparative Example Two is that the -1.2 V constant potential control condition is adopted, the cumulative methane production is 58505 mL, and the fermentation time is 25 d. After the start of fermentation, the methane percentage contents in the first three days are 27.81%, 59.59% and 74.20% respectively.

[0064] In comparison, the time for producing methane by the method of Example Three is shortened by 13 d compared with the time for producing methane by the -1.2 V constant potential control of Comparative Example Two, and the methane content in the biogas at the initial stage of the reaction is effectively improved, which is the basis for accelerating the anaerobic digestion reaction rate, and the improvement of the methane content is more obvious under the condition of high COD concentration of the influent.

[0065] The above merely illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the present application.

Claims

1. A method of enhancing the rate and purity of methanogenesis from electrofermentation, characterized in that, The device for improving the methane production rate and purity of electric fermentation comprises a biological fermentation reactor (1), a stirring device (5), a tubular electrolytic cell (2), a reference electrode (3), a first gas buffer bottle (7-1), a carbon dioxide sensor (9), an electrochemical workstation (8), and a gas collection device (11). The biological fermentation reactor (1) comprises an inner cavity and a top cover, and the stirring device (5), the tubular electrolytic cell (2), and the reference electrode (3) are arranged in the inner cavity and pass through the top cover. The tubular electrolytic cell (2) comprises, from inside to outside, an anode, a cation exchange membrane, and a cathode. The top cover of the biological fermentation reactor (1) is provided with a first gas outlet, which is sequentially connected to the first gas buffer bottle (7-1), the carbon dioxide sensor (9), and the gas collection device (11). The carbon dioxide sensor (9) is further connected to the electrochemical workstation (8) through a computer (10). The electrochemical workstation (8) comprises a counter electrode terminal, a working electrode terminal, and a reference electrode terminal. The counter electrode terminal is connected to the anode of the tubular electrolytic cell (2), the working electrode terminal is connected to the cathode of the tubular electrolytic cell (2), and the reference electrode terminal is connected to the reference electrode (3), which is used for dynamically regulating the input cathode potential of the biological fermentation reactor (1). The device further comprises a gas circulation device, which comprises a circulating gas pump (6), a second gas buffer bottle (7-2), and a micro-nano aerator (4). The top cover of the biological fermentation reactor (1) is provided with a gas inlet and a second gas outlet. The gas circulation device is sequentially connected to the second gas buffer bottle (7-2), the circulating gas pump (6), the gas inlet, and the micro-nano aerator (4) through the second gas outlet. The method specifically comprises the following steps: Step one, inoculate anaerobic sludge into the biological fermentation reactor (1) containing organic wastewater, start the stirring device (5), and generate biogas through anaerobic digestion, wherein the biogas comprises methane and carbon dioxide, and the pH value in the biological fermentation reactor (1) is maintained at 6.5-8 during the anaerobic digestion process; Step two, detect the volume content of carbon dioxide in the biogas through the carbon dioxide sensor (9), convert the volume content of carbon dioxide into an electrical signal through the computer (10), and deliver the electrical signal to the electrochemical workstation (8), and collect the biogas through the gas collection device (11); Step three, according to the dynamic potential regulation strategy, regulate the input cathode potential through the electrochemical workstation (8) to improve the methane production rate and purity of electric fermentation. In step three, the dynamic potential regulation strategy is: When the volume content of carbon dioxide is greater than 30%, the input cathode potential is set to -1.6V by the electrochemical workstation (8); when the volume content of carbon dioxide is between 20% and 30%, the input cathode potential is set to -1.5V by the electrochemical workstation (8); when the volume content of carbon dioxide is between 15% and 20%, the input cathode potential is set to -1.4V by the electrochemical workstation (8); when the volume content of carbon dioxide is between 10% and 15%, the input cathode potential is set to -1.3V by the electrochemical workstation (8); when the volume content of carbon dioxide is between 5% and 10%, the input cathode potential is set to -1.2V by the electrochemical workstation (8); and when the volume content of carbon dioxide is between 0 and 5%, the input cathode potential is set to -1.0V by the electrochemical workstation (8).

2. A method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, characterized in that, The device for improving the methane production rate and purity of electrofermentation also comprises a pH electrode arranged in the inner cavity of the biological fermentation reactor (1) and used for monitoring the pH value of the liquid in the biological fermentation reactor (1).

3. A method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, characterized in that, The anode of the tubular electrolytic cell (2) is a cylindrical titanium mesh, and the cathode is a cylindrical stainless steel mesh.

4. The method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, wherein, The reference electrode (3) is an Ag / AgCl electrode, and the built-in solution of the reference electrode is a saturated potassium chloride solution.

5. The method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, wherein, The biological fermentation reactor (1) is a CSTR reactor or a gas-lift bubble column.

6. The method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, wherein, The organic wastewater is potato starch industrial wastewater.

7. The method of enhancing the rate and purity of electrically fermented methanogenesis according to claim 1, wherein, The anaerobic sludge strain is hydrogenotrophic methanogen and acetotrophic methanogen, and the inoculation rate of the anaerobic sludge strain is 15%, and the mass ratio of hydrogenotrophic methanogen to acetotrophic methanogen is 1:1.

Images