Microbial power generation device and microbial power generation method

Abstract

To provide a microbial power generation device and a microbial power generation method that suppress bicarbonate deposition in a cathode chamber.SOLUTION: A microbial power generation device includes an anode chamber to which raw water holding microorganisms and containing organic matter serving as an electron donor is supplied, and a cathode chamber separated from the anode chamber by a non-conductive nanoporous or subnanoporous membrane that is ion permeable and to which an oxygen-containing gas is supplied as an electron acceptor, and the microbial power generation device is provided with a circulation flow path that circulates a portion of the anode chamber effluent water and supplies it to the anode chamber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a microbial power generation device and a microbial power generation method, and more particularly to a microbial power generation device and a microbial power generation method that extract, as electrical energy, the reducing power obtained when organic matter is oxidatively decomposed by microorganisms. [Background technology]

[0002] The microbial power generation device comprises an anode chamber to which raw water containing organic matter that holds microorganisms and acts as an electron donor is supplied, and a cathode chamber that is separated from the anode chamber by a non-conductive nanoporous or subnanoporous membrane that is ion-permeable and to which an oxygen-containing gas is supplied as an electron acceptor (Patent Documents 1 and 2).

[0003] Patent Document 1 describes the use of a membrane, such as an RO membrane or an NF membrane, with a pore size of 10 nm or less or a divalent valence rejection of 50% or more, as the diaphragm separating the anode chamber and the cathode chamber. By using such a diaphragm, it is possible to obtain a high amount of electricity by suppressing the permeation of impurities to the cathode while preventing an increase in proton transfer resistance.

[0004] Patent Document 2 describes the introduction of carbon dioxide gas into the oxygen-containing gas supplied to the cathode chamber in an amount of 0.1 to 20% relative to the oxygen. By adding carbon dioxide gas in this way, the pH of the cathode chamber, which becomes highly alkaline, is neutralized, and the flow of Na from the anode chamber to the cathode chamber is prevented. + , K. + This will promote the movement of people and improve power generation efficiency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2019-504446 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-108778 Summary of the Invention [Problem to be solved by the invention]

[0006] When a gas containing CO2 is passed through the cathode chamber, bicarbonates with relatively low solubility, such as NaHCO3 and KHCO3, may precipitate in the cathode chamber and block the flow path of the oxygen-containing gas.

[0007] An object of the present invention is to provide a microbial power generation device and a microbial power generation method in which the precipitation of bicarbonate in the cathode chamber is suppressed. [Means for solving the problem]

[0008] The gist of the present invention is as follows.

[0009] [1] An anode chamber to which raw water containing organic matter that supports microorganisms and acts as an electron donor is supplied; A microbial power generation device comprising a cathode chamber separated from the anode chamber by an ion-permeable non-conductive nanoporous or sub-nanoporous membrane and supplied with an oxygen-containing gas as an electron acceptor, A microbial power generation device characterized by having a circulation flow path that circulates a portion of the anode chamber effluent water and supplies it to the anode chamber.

[0010] [2] A microbial power generation apparatus as described in [1], which has a raw water supply means for supplying raw water to the circulation flow path and a pH adjustment means for adjusting the pH of the inflow water to the anode chamber.

[0011] [3] A microbial power generation device according to any one of [1] to [3], which is provided with an inorganic carbon concentration adjusting means for adjusting the inorganic carbon concentration of the inflow water to the anode chamber to 100 to 2,000 mg / L.

[0012] [4] The inorganic carbon concentration adjusting means controls at least one of the flow rate of the anode chamber outflow water circulation flow path and the raw water supply amount.

[0013] [5] A microbial power generation device comprising an anode chamber to which raw water containing microorganisms and organic matter as electron donors is supplied, and a cathode chamber separated from the anode chamber by an ion-permeable non-conductive nanoporous or subnanoporous membrane to which an oxygen-containing gas as an electron acceptor is supplied, A microbial power generation device characterized by having an addition means for adding at least one of carbonate and bicarbonate to raw water.

[0014] [6] A microbial power generation device comprising an anode chamber to which raw water containing microorganisms and organic matter as electron donors is supplied, and a cathode chamber separated from the anode chamber by an ion-permeable non-conductive nanoporous or subnanoporous membrane to which an oxygen-containing gas as an electron acceptor is supplied, A microbial power generation method characterized in that the inorganic carbon concentration of the inflow water to the anode chamber is set to 100 to 2,000 mg / L.

[0015] [7] The microbial power generation method according to [6], wherein the inorganic carbon concentration is adjusted by adding at least one of carbonate and bicarbonate to the raw water.

[0016] [8] The microbial power generation method according to [6], wherein a portion of the anode chamber effluent water is circulated and supplied to the anode chamber.

[0017] [9] The microbial power generation method according to [8], wherein the anode chamber effluent water circulating in the anode chamber is mixed with raw water, and the pH of the mixed water is adjusted to 6 to 9. [Effects of the Invention]

[0018] In one aspect of the present invention, a nanoporous or subnanoporous membrane with low air permeability and a pore size of 0.2 to 10 nm is used as the diaphragm of the microbial power generation device, and carbonate and / or bicarbonate are added to the raw water so that the inorganic carbon concentration of the inflow water to the anode chamber is 100 to 2,000 mg / L. When carbonate and / or bicarbonate are dissolved in water, bicarbonate ions (HCO3 - ), carbonate ions (CO3 2-), and non-ionic, undissociated carbonic acid (H2CO3) are produced. The undissociated carbonic acid (H2CO3) passes through the diaphragm and moves from the anode chamber to the cathode chamber. In the highly alkaline cathode chamber, the carbonic acid dissociates and the resulting hydrogen ions (H + ) causes the pH in the cathode chamber to decrease.

[0019] The anode chamber effluent (treated water) contains inorganic carbon (IC) derived from CO2 produced by the decomposition of organic matter in the anode chamber. In one embodiment of the present invention, instead of adding carbonate and / or bicarbonate to the raw water, a portion of the anode chamber effluent is circulated to the anode chamber. This increases the inorganic carbon concentration (IC concentration) in the anode chamber, and undissociated carbonic acid (H2CO3) permeates the diaphragm and moves from the anode chamber to the cathode chamber, lowering the pH in the cathode chamber.

[0020] According to the present invention, the pH in the cathode chamber can be lowered without introducing carbon dioxide gas into the cathode chamber, and a high amount of power generation can be stably obtained for a long period of time. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a microbial power generation device according to the first embodiment. [Figure 2] A schematic cross-sectional view showing an example of a microbial power generation device related to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] [First embodiment] FIG. 1 is a schematic cross-sectional view showing an example of a microbial power generation device according to a first embodiment of the present invention.

[0024] The interior of the tank body 1 is divided into a cathode chamber 3 and an anode chamber 4 by a diaphragm (a non-conductive nanoporous or subnanoporous membrane with ion permeability) 2. The nanoporous or subnanoporous membrane that constitutes the diaphragm 2 is preferably a semipermeable membrane with a pore size of 0.2 to 10 nm, such as an RO membrane, NF membrane, or forward osmosis membrane. The thickness of the membrane is preferably about 20 to 500 μm, and is particularly preferably about 50 to 200 μm in order to reduce ion migration resistance while maintaining sufficient strength.

[0025] A positive electrode 5 is disposed in the cathode chamber 3 so as to be in contact with the diaphragm 2. The positive electrode 5 is preferably a plate-shaped positive electrode made of a conductive material (graphite, titanium, stainless steel, etc.). The positive electrode 5 preferably supports an oxygen reduction catalyst such as platinum, for example, by using graphite felt as a substrate. The conductive material in the cathode chamber 3 is preferably water-repellent to prevent its surface from becoming covered with water, which would reduce the oxygen supply rate. A spacer is preferably inserted into the cathode chamber 3, and the positive electrode 5 is pressed against the diaphragm 2 to ensure close contact.

[0026] An oxygen-containing gas such as air is introduced into the cathode chamber 3 through the gas inlet 7, and exhaust gas flows out from the gas outlet 8 through the exhaust pipe 25.

[0027] An anode 6 made of a conductive porous material is placed in the anode chamber 4. This anode 6 is in contact with the diaphragm 2 directly or via one or two layers of a microbial membrane. The anode is preferably a three-dimensional filler made of a conductive material (graphite, titanium, stainless steel, etc.), and is placed throughout the anode chamber.

[0028] The negative electrode is preferably a porous body with a large surface area, many voids, and water permeability so that it can retain many microorganisms.Specific examples include a sheet of a conductive material with at least a roughened surface, or a porous conductor made of a conductive material in the form of felt or other porous sheets (e.g., graphite felt, foamed titanium, foamed stainless steel, etc.).

[0029] Microorganisms are supported on the negative electrode 6 made of a porous material. Anode solution is introduced into the anode chamber 4 through an inlet 4a, and treated water is discharged through an outlet 4b. The inside of the anode chamber 4 is made anaerobic.

[0030] The liquid in the anode chamber 4 is circulated via the outlet 12 , the circulation pipe 10 ( 10 a , 10 b ), the circulation pump 11 and the inlet 9 .

[0031] A discharge pipe for discharging a portion of the treated water (water anaerobically treated in the anode chamber 4) to the outside of the system branches off from the circulation pipe 10a.

[0032] A raw water supply pipe 16 is connected to the circulation pipe 10b so as to add raw water to the circulation water, and a raw water supply pump 17 is provided on the raw water supply pipe 16.

[0033] Further, downstream of the connection point of raw water supply pipe 16 (toward inlet 9), circulation pipe 10b is provided with a pH meter 14 for measuring the pH of the mixed water of raw water and return circulating water, an inorganic carbon concentration meter (IC concentration meter) 15, and is also connected to alkali addition means 13 such as an aqueous sodium hydroxide solution, which adds alkali as needed so that the pH of this mixed water is 6 to 9. This mixed water of circulating water and raw water is introduced into anode chamber 4. It is preferable that the inside of anode chamber 4 is kept in a state close to a completely mixed state. In addition, when measuring inorganic carbon concentration using the inorganic carbon concentration meter 15, it is common to add acid to lower the pH, make all carbon dioxide undissociated, then volatilize it by bubbling N2, and measure the amount of volatilized carbon.

[0034] The detection signal from inorganic carbon concentration meter 15 is input to controller 18, which controls the amount of circulating water by circulation pump 11 and the amount of raw water supplied by pump 17 so that the inorganic carbon concentration detected by inorganic carbon concentration meter 15 is 100 to 2000 mg / L, preferably 400 to 1000 mg / L. Specifically, if the detected concentration is below the lower threshold, the output of circulation pump 11 is increased, and if the detected concentration is still below the lower threshold, the output of raw water supply pump 17 is decreased. Conversely, if the detected concentration is above the upper threshold, the output of circulation pump 11 is decreased, and if the detected concentration is still above the upper threshold, the output of raw water supply pump 17 is increased. Generally, if the amount of circulating water is increased, the inorganic carbon concentration detected by inorganic carbon concentration meter 15 increases, and if the amount of raw water supply is increased, the detected inorganic carbon concentration decreases.

[0035] Condensed water generated in the cathode chamber 3 is discharged from a condensed water outlet (not shown).

[0036] Due to the electromotive force generated between the positive electrode 5 and the negative electrode 6, a current flows through the external resistor 21 via the lead wires 20 and 22.

[0037] By passing an oxygen-containing gas such as air, oxygen-enriched air, or pure oxygen through the cathode chamber 3 and circulating the liquid in the anode chamber 4 while supplying raw water, the following occurs in the anode chamber 4: (Organic matter)+H2O→CO2+H + +e - The reaction proceeds as follows. - flows through the negative electrode 6, the lead wire 22, the external resistor 21, and the lead wire 20 to the positive electrode 5.

[0038] In the anode chamber 4, CO2 is produced by a decomposition reaction of organic matter and water by microorganisms, which causes the pH to decrease. Therefore, alkali is added to the circulating water so that the detected pH by the pH meter 14 is preferably 6 to 9.

[0039] In the cathode chamber 3, the positive electrode 5 O2+4H + +4e - →2H2O During this reaction, cations move from the anode chamber 4 through the diaphragm 2 to the positive electrode 5 so that the anode chamber 4 and the cathode chamber 3 are kept electrically neutral. The solution in the anode chamber 4, whose pH is adjusted to 6 to 9, is usually + Compared to the concentration, Na from raw water and pH adjuster + YaK + Concentration is 10 3 ~10 5 Cathode chamber 3 contains Na because it is twice as high. + YaK + The condensed water produced by the condensation of HO produced in the positive electrode reaction contains K that has permeated the cation-permeable membrane of the diaphragm 2. + ,Na + However, since the inorganic carbon concentration in the anode chamber 4 is high at 100 to 2000 mg / L, undissociated carbonic acid (H2CO3) passes through the diaphragm 2 and moves to the cathode chamber 3 by concentration diffusion, and the pH of the condensed water decreases due to the neutralization action of this carbonic acid. As a result, Na + ,K + This promotes the movement of heat and improves power generation efficiency.

[0040] The microorganisms in the anode chamber 4 and the organic matter in the raw water that serves as the electron donor are not particularly limited.

[0041] The organic matter is not particularly limited as long as it can be decomposed by microorganisms, and examples thereof include water-soluble organic matter, organic fine particles that disperse in water, etc. The raw water containing this organic matter may be organic wastewater such as sewage or wastewater from food factories.

[0042] Raw water containing organic matter and preferably microbial nutrients is supplied to the anode chamber after adjusting the pH of the solution to 6 to 9, more preferably 6.5 to 7.5, which is suitable for the growth of electricity-generating bacteria and increases the concentration of undissociated carbonate, and then electrons and protons are generated by the microbial reaction. The temperature condition of the anode chamber is room temperature to medium-high temperature, specifically about 20 to 60°C, and particularly preferably about 25 to 45°C.

[0043] The negative electrode solution is a solution that can support microorganisms or cells and has a composition necessary for power generation. For example, when generating power through a respiratory system, the negative electrode solution can be a medium containing the energy source and nutrients necessary for respiratory metabolism, such as bouillon medium, M9 medium, L medium, Malt Extract, MY medium, or a nitrifying bacteria selective medium. Organic waste such as sewage, organic industrial wastewater, or food waste can also be used.

[0044] The negative electrode solution may contain a phosphate buffer, if necessary.

[0045] [Second embodiment] FIG. 2 shows an example of a microbial power generation device according to the second embodiment.

[0046] In this embodiment, the circulation pipe 10 and the circulation pump 11 are omitted, and instead, a treated water outflow pipe 10A is connected to an outlet 12.

[0047] Furthermore, a raw water supply pipe 16 is directly connected to the inlet 9, and the raw water supply pump 17, pH meter 14, inorganic carbon concentration meter 15, and alkali addition means 13 are provided in this pipe 16. Furthermore, in this embodiment, carbonate or bicarbonate addition means 19 is connected to this pipe 16. In this embodiment, the carbonate or bicarbonate addition means is provided between the raw water supply pump 17 and the alkali addition means 13, but is not limited to this.

[0048] The detection signal from the inorganic carbon concentration meter 15 is input to a controller 18, which controls the raw water supply pump 17 and the chemical injection pump (not shown) of the carbonate or bicarbonate adding means 19 so that the concentration detected by the inorganic carbon concentration meter 15 is 100 to 2000 mg / L, preferably 400 to 1000 mg / L. Specifically, if the detected concentration is below the lower threshold, the output of the chemical injection pump is increased, and if the detected concentration is still below the lower threshold, the output of the raw water supply pump 17 is decreased. Conversely, if the detected concentration is above the upper threshold, the output of the chemical injection pump is decreased, and if the detected concentration is still above the upper threshold, the output of the raw water supply pump 17 is increased. Sodium salts, potassium salts, and ammonium salts are suitable as carbonates or bicarbonates.

[0049] The other configurations of the microbial power generation apparatus of the second embodiment are the same as those of the microbial power generation apparatus of the first embodiment, and in Figure 2, the same reference numerals as in Figure 1 indicate the same parts. [Example]

[0050] Comparative Examples and Examples will be described below.

[0051] [Comparative Example 1] The microbial power generation device shown in Figure 2 was configured as follows.

[0052] An anode chamber (volume 175 mL) 4 measuring 25 cm in length, 7 cm in width, and 1 cm in thickness was filled with 1 cm thick graphite felt to form a negative electrode 6. A cathode chamber 3 was formed between this anode chamber 4 and an RO membrane (ES-20 manufactured by Nitto Denko) as a diaphragm 2. The cathode chamber 3 measured 25 cm in length, 7 cm in width, and 0.5 cm in thickness (volume 87.5 mL). A gas diffusion electrode was placed in the cathode chamber 3 as a positive electrode. A 0.4 cm thick polyethylene lattice-shaped molded body was filled in the cathode chamber 3 to ensure close contact between the positive electrode and the support layer side of the RO membrane. The gas diffusion electrode was formed by filling one side of 160 μm thick carbon paper treated with water repellency by PTFE with a solution of Pt-loaded carbon black (Pt content 50 wt%) dispersed in Nafion® solution at a concentration of 0.5 mg-Pt / cm. 2 The coating was applied so that the thickness was as follows: and the coating was dried at 130°C.

[0053] Stainless steel wires were attached to the graphite felt anode and the carbon paper cathode with conductive paste to form lead wires 20 and 22, respectively, and connected across an external resistor 21. The external resistance at start-up was set to 100 Ω, and the resistance was gradually reduced according to the power generation output. The device was placed in a room controlled at 35°C.

[0054] The raw water (COD) contained ethanol 600 mg / L, yeast extract 100 mg / L, 50 mM phosphate buffer, and ammonium chloride. Cr 1,400 mg / L, pH 7.2) was supplied at 3 mL / min in an upflow manner (HRT 1 hr, COD Cr Tank load 34kg / m 3 / d).

[0055] No carbonate and / or bicarbonate was added to the raw water.

[0056] Prior to the introduction of raw water, the effluent from another microbial power generation device was introduced as an inoculum. Air was supplied to the cathode chamber in a downward flow at a flow rate of 300 mL / min. No negative electrode solution was introduced through the inlet 4a or outlet 4b.

[0057] Average power generation and COD for 10 days from the 10th to 20th day after operation started Cr The average removal rate and the observation results of the operating conditions are shown in Table 1. Table 2 shows the pH of the anode chamber influent (raw water for Comparative Examples 1 to 3 and Example 1, and raw water + circulated water for Examples 2 to 4 in which treated water circulation was performed), the anode chamber effluent (treated water), and the cathode chamber effluent, as well as the IC concentration of the anode chamber influent and effluent on the 10th to 20th days after the start of operation. Note that an InnovOx Lab model manufactured by Veolia was used as the IC concentration meter 15.

[0058] Comparative Example 2 The procedure was the same as in Comparative Example 1, except that 2% of carbon dioxide gas was introduced into the air supplied to the cathode chamber. The results are shown in Tables 1 and 2.

[0059] Comparative Example 3 The procedure was the same as in Comparative Example 1, except that 2.4 g / L of NaCl was added to the raw water. The results are shown in Tables 1 and 2.

[0060] [Example 1] The procedure was the same as in Comparative Example 1, except that 3.5 g / L of NaHCO3 was added to the raw water. The results are shown in Table 1.

[0061] [Example 2] In Comparative Example 1, instead of the pipes 10A and 16, circulation pipes 10 (10a and 10b) and a circulation pump 11 were provided as shown in Figure 1, and pipe 10b was connected to pipe 16. The other configurations were the same as those of Comparative Example 1.

[0062] In this device, as shown in Figure 1, a portion of the water effluent from the anode chamber was circulated at 32 mL / min, mixed with raw water, and then adjusted to pH 7.2 by adding 1 N NaOH before being supplied to the anode chamber. Other operating conditions were the same as in Comparative Example 1. The results are shown in Tables 1 and 2.

[0063] [Example 3] A portion of the anode chamber effluent water was circulated at 32 mL / min, mixed with the raw water, and then adjusted to pH 6.2 by adding 1N NaOH or 1N HCl before being supplied to the anode chamber. Other than this, the procedure was the same as in Example 2. The results are shown in Tables 1 and 2.

[0064] [Example 4] The equipment was configured the same as in Comparative Example 1, but a portion of the anode chamber effluent water was circulated at 32 mL / min, mixed with the raw water, and then adjusted to pH 8.2 by adding 1N NaOH before being supplied to the anode chamber. The rest of the experiment was the same as in Example 2. The results are shown in Tables 1 and 2.

[0065] [Table 1]

[0066] [Table 2]

[0067] [Consideration] In all of Comparative Examples 1 to 3 and Examples 1 to 4, the amount of power generated began to increase 2 to 3 days after the start of operation, and the amount of power generated and removal rate reached their peaks around the 10th day, after which the performance was almost maintained, except for Comparative Example 2. As shown in Table 1, the amount of power generated was 220 W / m in Comparative Examples 1 and 3. 3 , 250W / m 3 In contrast, in Examples 1 to 4, it was 290 to 420 W / m 3 The removal rate was also improved to 58-72%, which was equal to or greater than the 52-60% in Comparative Examples 1 and 3. The amount of power generated was 100-200 W / m in Comparative Examples 1 and 2 for the next three months. 3 In contrast, in Examples 3 and 4, the 3 In Examples 1 and 2, the 3 That was all.

[0068] In Comparative Example 2, the average power generation amount from 10 to 20 days after the start of operation was 430 W / m 3 Although the removal rate was also the highest at 78%, NaHCO3, KHCO3, etc. precipitated on the cathode after about a month, causing blockage and preventing ventilation.

[0069] As shown in Table 2, the pH of the cathode chamber outflow water was high at 12.5 and 12.8 in Comparative Examples 1 and 3, but it dropped to 10.5 in Comparative Example 2, where carbon dioxide gas was introduced into the cathode chamber. Cr Although this appears to have led to an improvement in the removal rate, it also led to the precipitation of NaHCO3 and KHCO3 in the cathode chamber. In contrast, in Examples 1 to 4, NaHCO3 was added or the treated water was circulated, so that the pH of the water effluent from the cathode chamber was reduced to 10.3 to 11.6 without introducing carbon dioxide into the cathode chamber, and the amount of power generation and COD Cr The removal rate was improved. Also, unlike Comparative Example 2, the carbon dioxide concentration in the cathode chamber did not increase excessively, which is thought to have prevented NaHCO3 and KHCO3 from depositing, allowing stable operation for three months.

[0070] In this way, it was found that the present invention makes it possible to lower the pH in the cathode chamber of a microbial power generation device without introducing carbon dioxide gas into the cathode chamber, thereby enabling a high amount of power to be generated stably over a long period of time. [Explanation of symbols]

[0071] 1 tank body 2 Diaphragm 3. Cathode chamber 4 Anode Chamber 5 Positive electrode 6 negative electrode 10(10a,10b) Circulation piping 10A Treated water outflow pipe 13 Alkali addition method 15 Inorganic carbon concentration meter 16 Raw water supply piping 18 Controller 19 Carbonate or bicarbonate addition means 21 External Resistor

Claims

1. an anode chamber to which raw water containing organic matter that supports microorganisms and acts as an electron donor is supplied; A microbial power generation device comprising a cathode chamber separated from the anode chamber by an ion-permeable non-conductive nanoporous or sub-nanoporous membrane and supplied with an oxygen-containing gas as an electron acceptor, a circulation flow path for circulating a portion of the anode chamber outflow water and supplying it to the anode chamber; a circulation pump provided in the circulation flow path; a raw water supply pipe connected to the circulation flow path; a raw water supply pump provided in the raw water supply pipe; an inorganic carbon concentration meter for measuring the inorganic carbon concentration of the anode chamber inflow water flowing from the circulation flow path into the anode chamber; a controller that controls at least one of the amount of circulating water from the circulation pump and the amount of raw water supplied from the raw water supply pump so that the inorganic carbon concentration detected by the inorganic carbon concentration meter falls within a predetermined range; A microbial power generation device comprising:

2. 2. The microbial power generation device according to claim 1, further comprising a pH adjusting means for adjusting the pH of the inflow water to the anode chamber.

3. The microbial power generation device of claim 1 or 2, wherein the controller adjusts the inorganic carbon concentration of the anode chamber inflow water to 100 to 2,000 mg / L.

4. A microbial power generation device comprising an anode chamber to which raw water containing microorganisms and organic matter acting as electron donors is supplied, and a cathode chamber separated from the anode chamber by an ion-permeable non-conductive nanoporous or subnanoporous membrane to which an oxygen-containing gas acting as an electron acceptor is supplied, A microbial power generation device characterized by having an addition means for adding at least one of carbonate and bicarbonate to raw water so that the inorganic carbon concentration in the anode chamber inflow water is 100 to 2,000 mg / L.

5. A microbial power generation method using a microbial power generation device comprising an anode chamber that holds microorganisms and is supplied with raw water containing organic matter as an electron donor, and a cathode chamber that is separated from the anode chamber by an ion-permeable, non-conductive nanoporous or subnanoporous membrane and is supplied with an oxygen-containing gas as an electron acceptor, A microbial power generation method characterized in that the inorganic carbon concentration of the anode chamber inflow water flowing into the anode chamber is set to 100 to 2,000 mg / L.

6. 6. The microbial power generation method according to claim 5, wherein the inorganic carbon concentration is adjusted by adding at least one of carbonate and bicarbonate to the raw water.

7. 6. The microbial power generation method according to claim 5, wherein a portion of the anode chamber effluent water flowing out from the anode chamber is circulated and supplied to the anode chamber.

8. 8. The microbial power generation method according to claim 7, wherein the anode chamber effluent water circulating in the anode chamber is mixed with raw water to form mixed water, and the pH of the mixed water is adjusted to 6-9.

9. an anode chamber to which raw water containing organic matter that supports microorganisms and acts as an electron donor is supplied; a cathode chamber separated from the anode chamber via an ion-permeable non-conductive nanoporous or sub-nanoporous membrane, to which an oxygen-containing gas is supplied as an electron acceptor; A microbial power generation device comprising: a circulation flow path for circulating a portion of the anode chamber outflow water and supplying it to the anode chamber; adding means for adding at least one of carbonate and bicarbonate to raw water; A microbial power generation device comprising:

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