Application of microbial electrochemical coupling anaerobic reaction enhanced biological methane synthesis in carbon neutralization

Abstract

The invention discloses application of microbial electrochemical coupling anaerobic reaction enhanced biological methane synthesis in carbon neutralization. A microbial electrolysis cell is composed of an anode chamber, a cathode chamber and a proton exchange membrane, the anode chamber and the cathode chamber are connected through the proton exchange membrane, and a mixed solution of sewage, ionic liquid and a first methanogenic microbial solution serves as a substrate in the anode chamber. In the cathode chamber, a mixed solution of a culture medium, an ionic liquid and a second methanogenic microorganism solution serves as a substrate, under the action of an external power supply, sewage is degraded in the anode chamber to generate electrons and H < + >, the H < + > enters the cathode chamber through a proton exchange membrane, and CO2 is converted into methane under the action of microorganisms in the cathode chamber; the first ionic liquid or the second ionic liquid is amino acid anionic ionic liquid. The microbial electrolysis cell provided by the invention is convenient to operate and maintain and small in occupied area.

Description

Technical field:

[0001] The present invention relates to the technical field of biofuel cells, and in particular to the application of microbial electrochemical coupling anaerobic reaction to enhance biomethane synthesis in carbon neutrality. Background technology:

[0002] Environmental safety issues are the focus of global attention at present. The greenhouse effect is one of the problems that need to be solved urgently. CO2, as the main greenhouse gas, can also be regarded as a valuable "C" resource. Focusing on the recovery and utilization of CO2, by establishing an efficient artificial carbon cycle, changing the development mode of energy, and accelerating the development of renewable energy alternative technologies, it will help to solve environmental and energy problems at the same time, thereby achieving green and sustainable development in the new era. Microbial electrolysis cell (MEC) is an emerging bioelectrocatalytic technology that can reduce CO2 to produce high value-added chemicals such as acetic acid and methane under mild conditions such as normal temperature and pressure. Among them, due to the high calorific value of methane and its easy collection, the application technology is mature and extensive, so CO2 bioelectromethanization is regarded as a more ideal artificial carbon neutralization method. However, the cathode of this technology is more commonly used, but the anode has not been well utilized, resulting in energy waste. At the same time, this technology still has many problems to overcome, such as low methane yield, slow biofilm formation resulting in a long MEC startup time, and unclear molecular mechanism of interfacial electron transfer. Ionic liquids are widely used in carbon capture, but they are mostly used in traditional fuel cells and have not yet been used in combination with microorganisms. Summary of the invention:

[0003] In order to overcome the above-mentioned problems existing in the prior art, the present invention provides an application of microbial electrochemical coupling anaerobic reaction to enhance biomethane synthesis in carbon neutrality. The present invention designs a methanogenic microbial electrolysis cell that can simultaneously utilize the cathode and anode, and adds ionic liquid with affinity to microorganisms to increase the methane production rate.

[0004] The present invention provides a microbial electrolysis cell, which is composed of an anode chamber, a cathode chamber and an exchange membrane. The anode chamber and the cathode chamber are connected by a proton exchange membrane. The anode chamber uses a mixed solution of sewage, a first ionic liquid and a first methanogenic microbial solution as a substrate, and the cathode chamber uses a mixed solution of a culture medium, a second ionic liquid and a second methanogenic microbial solution as a substrate. Under the action of an external power supply, the sewage is degraded in the anode chamber to generate electrons and H + , H + The carbon dioxide enters the cathode chamber through the proton exchange membrane, and is converted into methane by the microorganisms in the cathode chamber; the first ionic liquid or the second ionic liquid is an amino acid anion ionic liquid. The exchange membrane proposed in the present invention is a proton exchange membrane or an ion exchange membrane.

[0005] Preferably, the amino acid anionic ionic liquid is tetraethylammonium glycine, and its structural diagram is as shown in Figure 1 As shown, the concentration of the first ionic liquid in the substrate of the anode chamber is 8-12 mmol / L, and the concentration of the second ionic liquid in the substrate of the cathode chamber is 8-12 mmol / L. Further preferably, the concentration of the first ionic liquid in the substrate of the anode chamber is 10 mmol / L, and the concentration of the second ionic liquid in the substrate of the cathode chamber is 10 mmol / L.

[0006] Preferably, the volume ratio of sewage to the first methanogenic microbial solution in the substrate of the anode chamber is 8-12:1, and the volume ratio of culture medium to the second methanogenic microbial solution in the substrate of the cathode chamber is 8-12:1. The methanogenic microorganisms in the cathode chamber and the anode chamber are hydrogenophilic methanogens, which refer to methanogens that can use H2 and / or CO2 as nutrition. The hydrogenophilic methanogens are domesticated and incubated by the microbial electrolysis cell system proposed by the present invention.

[0007] The culture medium includes organic nitrogen source yeast and peptone, combined with the removal of COD carbon concentration, preferably C / N is maintained above 10, the pH value of the culture medium solution is 8.0±0.2, and a final concentration of 100mM di-glycine dipeptide is used as a buffer salt in the culture medium solution; the culture medium solution needs to be deoxygenated and sterilized before being placed in the cathode chamber. In the present invention, the deoxygenation and sterilization process is preferably to aerate the culture medium solution under high-purity nitrogen for 30 minutes, and then sterilize it in a high-pressure steam autoclave at 121°C for 20 minutes.

[0008] Preferably, the first methanogenic microbial solution or the second methanogenic microbial solution is obtained by domestication in a sewage-combined electrolytic cell, specifically by the following steps: the anode chamber and the cathode chamber are connected by an exchange membrane, a mixed solution of sewage, culture medium, a third ionic liquid and the first anaerobic sludge is used as a substrate in the anode chamber, carbon dioxide is used as the only carbon source in the cathode chamber, and the fourth ionic liquid and the second anaerobic sludge are used as substrates, and the microorganisms are domesticated under the action of an external power supply until a stable efficiency is reached to obtain a hydrogenophilic methanogenic microbial solution.

[0009] More preferably, the volume fraction of the first anaerobic sludge in the substrate of the anode chamber is 8%-12%, and the voltage of the external power supply is -0.6 V. Still more preferably, the volume fraction of the first anaerobic sludge in the substrate of the anode chamber is 10%.

[0010] Further preferably, the third ionic liquid or the fourth ionic liquid is an amino acid anion type ionic liquid, the concentration of the third ionic liquid in the substrate of the anode chamber is 8-12 mmol / L, and the concentration of the fourth ionic liquid in the substrate of the cathode chamber is 8-12 mmol / L. Still further preferably, the concentration of the third ionic liquid in the substrate of the anode chamber is 10 mmol / L, and the concentration of the fourth ionic liquid in the substrate of the cathode chamber is 10 mmol / L.

[0011] Preferably, the voltage of the external power supply is -0.6V.

[0012] Preferably, the anode is carbon cloth and the cathode is a carbon brush.

[0013] Preferably, the domestic sewage is wastewater in which COD needs to be degraded, that is, the concentration of COD in the domestic sewage exceeds 1000 mg / L.

[0014] The present invention also protects the application of microbial electrochemical coupling anaerobic reaction to enhance biomethane synthesis in carbon neutrality, with carbon cloth as anode and carbon brush as cathode, the cathode and anode are connected by an exchange membrane, the anode uses sewage, a first methanogenic microbial solution and a solution containing a first ionic liquid as substrates; the cathode uses a culture medium, a second methanogenic microbial solution and a solution containing a second ionic liquid as substrates, CO2 is the only carbon source for the cathode, and under the action of an external power supply, the anode degrades sewage to generate electrons and H + , H + The CO2 enters the cathode through the exchange membrane and is converted into methane under the action of cathode microorganisms.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The present invention makes full use of the anode chamber and cathode chamber of the double-chamber electrolytic cell, and does not cause energy waste compared to the traditional double-chamber microbial electrolytic cell.

[0017] 2. The present invention effectively improves the methane production and COD degradation rate of the microbial electrolysis cell system by adding ionic liquid.

[0018] 3. The microbial electrolysis cell proposed by the present invention is easy to operate and maintain and occupies a small area. Description of the drawings:

[0019] Figure 1 is the structural formula of the ionic liquid of Example 1;

[0020] Figure 2 This is a schematic diagram of the structure of the microbial electrolysis cell proposed by the present invention;

[0021] Explanation of the accompanying reference numerals: 1. microbial electrolysis cell; 2. carbon cloth; 3. proton exchange membrane; 4. electrochemical workstation; 5. air outlet hose; 6. gas chromatograph; 7. carbon brush; 8. methanogenic microbial solution; 9. feed port; 10. air inlet. Specific implementation method:

[0022] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0023] Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the experimental materials and reagents herein are conventional commercial products in the art. The exchange membrane proposed in the present invention is a proton exchange membrane or an ion exchange membrane, and the preferred exchange membrane in the following embodiments is a proton exchange membrane.

[0024] like Figure 2 As shown, the microbial electrolysis cell 1 is composed of an anode chamber, a cathode chamber and a proton exchange membrane 3. The anode chamber and the cathode chamber are connected by the proton exchange membrane 3. The anode chamber uses a mixed solution of sewage, a first ionic liquid and a methanogenic microbial solution 8 as a substrate (i.e., an anolyte), and the anode is placed in the substrate of the anode chamber. The cathode chamber uses a mixed solution of a culture medium, a second ionic liquid and a methanogenic microbial solution 8 as a substrate (i.e., a catholyte), and the cathode is placed in the substrate of the cathode chamber. The anode and the cathode are connected by an electrochemical workstation 4. The sewage, the first ionic liquid and the methanogenic microbial solution enter the anode chamber through the feed port 9, and the culture medium, the second ionic liquid and the methanogenic microbial solution enter the cathode chamber through the feed port of the cathode chamber. Under the action of an external power supply, the sewage is degraded in the anode chamber to generate electrons and H + , H + CO2 enters the cathode chamber through the proton exchange membrane, and passes into the cathode chamber through the air inlet 10. Under the action of microorganisms in the cathode chamber, CO2 is converted into methane, which is discharged through the air outlet hose 5 and detected by the gas chromatograph 6.

[0025] In the following embodiments, preferably, the volume ratio of sewage and methanogenic microbial solution in the substrate of the anode chamber is 8-12:1, and the volume ratio of culture medium and second methanogenic microbial solution in the substrate of the cathode chamber is 8-12:1. Further preferably, the volume ratio of sewage and methanogenic microbial solution in the substrate of the anode chamber is 10:1, and the volume ratio of culture medium and second methanogenic microbial solution in the substrate of the cathode chamber is 10:1.

[0026] In the following embodiments, preferably, the first ionic liquid or the second ionic liquid is an amino acid anion type ionic liquid.

[0027] In the following embodiments, preferably, the carbon cloth 2 is used as the anode and the carbon brush 7 is used as the cathode.

[0028] In the following embodiments, it is preferred that the culture medium includes organic nitrogen source yeast and peptone, combined with the removal of COD carbon concentration, preferably C / N is maintained above 10, the pH value of the culture medium solution is 8.0±0.2, and a final concentration of 100mM di-glycine dipeptide is used as a buffer salt in the culture medium solution; the culture medium solution needs to be deoxygenated and sterilized before being placed in the cathode chamber. In the present invention, the deoxygenation and sterilization process is preferably to aerate the culture medium solution under high-purity nitrogen for 30 minutes, and then sterilize it in a high-pressure steam autoclave at 121°C for 20 minutes.

[0029] The methanogenic microorganisms in the present invention are hydrogenophilic methanogenic bacteria, which are tamed in the sewage treatment environment in the following embodiments in combination with the electrolytic cell proposed in the present invention. The first methanogenic microbial solution or the second methanogenic microbial solution is obtained by taming the sewage in combination with the electrolytic cell, and is specifically obtained by the following steps: the anode chamber and the cathode chamber are connected by an exchange membrane, and the anode chamber uses sewage, culture medium, a third ionic liquid and a mixed solution of the first anaerobic sludge as a substrate, and the cathode chamber uses carbon dioxide as the only carbon source, the fourth ionic liquid and the second anaerobic sludge as substrates. Under the action of an external power supply, the microorganisms are tamed at room temperature until a stable efficiency is reached to obtain a hydrogenophilic methanogenic microbial solution. The culture medium in the anode chamber substrate includes organic nitrogen source yeast and peptone, combined with the removal of COD carbon concentration in sewage, so that C / N is maintained above 10, and the amount of sewage and culture medium added is not specifically limited, as long as the carbon-nitrogen ratio is maintained. The above-mentioned anaerobic sludge is collected from the sewage pool to be treated. The culture medium includes organic nitrogen source yeast and peptone, combined with the removal of COD carbon concentration, preferably C / N is maintained above 10, the pH value of the culture medium solution is 8.0±0.2, and a final concentration of 100mM di-glycine dipeptide is used as a buffer salt in the culture medium solution; the culture medium solution needs to be deoxygenated and sterilized before being placed in the cathode chamber. In the present invention, the deoxygenation and sterilization process is preferably to aerate the culture medium solution under high-purity nitrogen for 30 minutes, and then sterilize it in a high-pressure steam autoclave at 121°C for 20 minutes.

[0030] In the following embodiments, preferably, the volume fraction of the first anaerobic sludge in the substrate of the anode chamber is 8%-12%, and the voltage of the external power supply is -0.6 V. Still more preferably, the volume fraction of the first anaerobic sludge in the substrate of the anode chamber is 10%.

[0031] In the following embodiments, preferably, the third ionic liquid or the fourth ionic liquid is an amino acid anion type ionic liquid, the concentration of the third ionic liquid in the substrate of the anode chamber is 8-12 mmol / L, and the concentration of the fourth ionic liquid in the substrate of the cathode chamber is 8-12 mmol / L. Further preferably, the concentration of the third ionic liquid in the substrate of the anode chamber is 10 mmol / L, and the concentration of the fourth ionic liquid in the substrate of the cathode chamber is 10 mmol / L.

[0032] The present invention preferably inoculates the electrolyte in the cathode chamber with pre-expanded cultured and collected hydrogenophilic methanogens. The present invention has no particular limitation on the process of pre-expanding cultured and collecting hydrogenophilic methanogens, and a process well known to those skilled in the art can be used.

[0033] Embodiment 1:

[0034] The methanogenic microbial solution is obtained by taming the sewage combined with the electrolytic cell, and is specifically obtained by the following steps: the anode chamber and the cathode chamber are connected by a proton exchange membrane, the anode chamber uses sewage, culture medium, 10mmol / L tetraethylammonium glycine and a mixed solution of anaerobic sludge as substrates, and the cathode chamber uses carbon dioxide as the only carbon source, 10mmol / L tetraethylammonium glycine and anaerobic sludge as substrates, and the microorganisms are tamed at room temperature under the action of an external power source until a stable efficiency is reached to obtain a hydrogenophilic methanogenic microbial solution. The culture medium in the anode chamber substrate includes organic nitrogen source yeast and peptone, combined with the removal of COD carbon concentration in sewage, so that C / N is maintained above 10, the pH value of the culture medium solution is 8.0±0.2, and in the culture medium solution, a final concentration of 100mM di-glycine dipeptide is used as a buffer salt; the culture medium solution needs to be deoxygenated and sterilized before being placed in the cathode chamber. The deoxygenation and sterilization process is to aerate the culture medium solution under high-purity nitrogen for 30 minutes, and then sterilize it in a high-pressure steam sterilizer at 121° C. for 20 minutes. In the anode chamber, the volume fraction of the anaerobic sludge in the substrate of the anode chamber is 10%, and the voltage of the external power supply is -0.6V.

[0035] like Figure 1-2 As shown, the anode chamber uses sewage with a COD concentration of 1200 mg / L, the above-prepared methanogenic microbial solution and 10 mmol / L tetraethylammonium glycine as electron transfer enhancement solvents, and the volume ratio of sewage to methanogenic microbial solution in the substrate is 10:1; the cathode chamber uses culture medium, the above-prepared methanogenic microbial solution and 10 mmol / L tetraethylammonium glycine as substrates, and the volume ratio of culture medium to methanogenic microbial solution in the substrate is 10:1, wherein CO2 is the only carbon source for the cathode. Under the action of an external power supply of -0.6 V, the introduced CO2 is converted into methane.

[0036] Comparative Example 1:

[0037] The same as Example 1, except that only the methanogenic microbial solution and sewage were added, and no ionic liquid (tetraethylammonium glycine) was added.

[0038] Comparative Example 2:

[0039] The same as Example 1, except that: no methanogenic microbial solution was added, and only ionic liquid (tetraethylammonium glycine) was added at a concentration of 10 mmol / L.

[0040] The experimental data of Example 1 and Comparative Examples 1-2 are shown in Table 1 below.

[0041] Table 1 CH4 production and COD degradation rate in different groups

[0042]

[0043] Embodiment 2:

[0044] The same as Example 1, except that the volume ratio of sewage to methanogenic microbial solution in the substrate of the anode chamber is 8:1, the volume ratio of culture medium to methanogenic microbial solution in the substrate of the cathode chamber is 8:1, and the concentration of ionic liquid in the anode chamber and the cathode chamber is 8 mmol / L.

[0045] Embodiment 3:

[0046] The same as Example 1, except that the volume ratio of sewage to methanogenic microbial solution in the substrate of the anode chamber is 12:1, the volume ratio of culture medium to methanogenic microbial solution in the substrate of the cathode chamber is 12:1, and the concentration of ionic liquid in the anode chamber and the cathode chamber is 12 mmol / L.

[0047] The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A microbial electrolysis cell, characterized in that: The invention is composed of an anode chamber, a cathode chamber and an exchange membrane. The anode chamber and the cathode chamber are connected by an exchange membrane. The anode chamber uses a mixed solution of sewage, a first ionic liquid and a first methanogenic microbial solution as a substrate, and the cathode chamber uses a mixed solution of a culture medium, a second ionic liquid and a second methanogenic microbial solution as a substrate. Under the action of an external power supply, the sewage is degraded in the anode chamber to generate electrons and H + , H + It enters the cathode chamber through the proton exchange membrane and converts CO2 into methane under the action of microorganisms in the cathode chamber; the first ionic liquid or the second ionic liquid is an amino acid anion ionic liquid.

2. The microbial electrolysis cell according to claim 1, characterized in that: The amino acid anion type ionic liquid is tetraethylammonium glycine, the concentration of the first ionic liquid in the substrate of the anode chamber is 8-12 mmol / L, and the concentration of the second ionic liquid in the substrate of the cathode chamber is 8-12 mmol / L.

3. The microbial electrolysis cell according to claim 1 or 2, characterized in that: The volume ratio of sewage to the first methanogenic microbial solution in the substrate of the anode chamber is 8-12:1; the volume ratio of culture medium to the second methanogenic microbial solution in the substrate of the cathode chamber is 8-12:

1.

4. The microbial electrolysis cell according to claim 1, characterized in that: The first methanogenic microbial solution or the second methanogenic microbial solution is obtained by the following steps: the anode chamber and the cathode chamber are connected by an exchange membrane, a mixed solution of sewage, culture medium, third ionic liquid and first anaerobic sludge is used as a substrate in the anode chamber, carbon dioxide is used as the only carbon source in the cathode chamber, and the fourth ionic liquid and the second anaerobic sludge are used as substrates, and the microorganisms are domesticated under the action of an external power source until a stable efficiency is reached, thereby obtaining a hydrogenophilic methanogenic microbial solution.

5. The microbial electrolysis cell according to claim 4, characterized in that: The volume fraction of the first anaerobic sludge in the substrate of the anode chamber is 8%-12%, and the voltage of the external power supply is -0.6V.

6. The microbial electrolysis cell according to claim 4, characterized in that: The third ionic liquid or the fourth ionic liquid is an amino acid anion type ionic liquid. The concentration of the third ionic liquid in the substrate of the anode chamber is 8-12 mmol / L, and the concentration of the fourth ionic liquid in the substrate of the cathode chamber is 8-12 mmol / L.

7. The microbial electrolysis cell according to claim 1 or 2, characterized in that: The voltage of the external power supply is -0.6V.

8. The microbial electrolysis cell according to claim 1 or 2, characterized in that: The anode is carbon cloth and the cathode is carbon brush.

9. The microbial electrolysis cell according to claim 1 or 2, characterized in that: Domestic sewage is wastewater that needs to degrade COD.

10. Application of microbial electrochemical coupling anaerobic reaction to enhance biomethane synthesis in carbon neutrality, characterized in that: The carbon cloth is used as the anode and the carbon brush is used as the cathode. The cathode and the anode are connected by an exchange membrane. The anode uses sewage, the first methanogenic microbial solution and a solution containing the first ionic liquid as substrates; the cathode uses culture medium, the second methanogenic microbial solution and a solution containing the second ionic liquid as substrates. CO2 is the only carbon source for the cathode. Under the action of an external power source, the anode degrades sewage to produce electrons and H + , H + The CO2 enters the cathode through the exchange membrane and is converted into methane under the action of cathode microorganisms.

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