JP6547998B2 - Microbial fuel cell and power generation method in wet mud including mud sand - Google Patents

Description

  The present invention relates to a microbial fuel cell that generates electricity using microorganisms. In particular, the present invention relates to a microbial fuel cell that generates electricity using microorganisms present in wet mud.

  A microbial fuel cell is a fuel cell that catalytically uses microorganisms to convert some of the energy available on the biodegradable substrate into electricity. A microbial fuel cell is a fuel cell that generates electricity by reducing oxygen with the other electrode (cathode electrode) using electrons generated by decomposing organic matter in one electrode (anode electrode). By taking out electrons from the metabolic reaction of decomposition of organic matter to an external circuit, it is possible to extract electric energy from the chemical energy of the organic matter catalyzed by the microorganism.

  Conventionally, as a microbial fuel cell, a fuel cell using an anode electrode carrying a microorganism (see, for example, Patent Document 1), a first tank containing a microorganism that decomposes an organic substance, and the proton-permeable membrane A fuel cell (for example, refer to Patent Documents 2 and 3) or the like which has a configuration in which a second tank adjacent to the first tank and an electrode are provided in each tank has been reported.

Unexamined-Japanese-Patent No. 2013-239292 JP 2012-142250 A JP, 2013-84597, A

  In conventional microbial batteries, it is necessary to purge inert gas under an anaerobic atmosphere in order to maintain an anaerobic atmosphere in the anode (oxidation reaction electrode) tank in any structure. In addition, there is a problem that the output decreases when oxygen is mixed in the anode tank. In addition, in order to obtain a high output, a specific current-producing bacterium (a typical strain of the genus Schwanella or Diobacter) is immobilized on the electrode, or a raw material containing an organic matter to be a fuel to make it suitable for power generation. Since it is necessary to add water to make a suspension, it is the actual situation that the cost is increased.

On the other hand, since there exist applications that do not require a high output (for example, power generation with organic substance processing), a microbial battery with a simple apparatus configuration and low cost has been desired.
Under such circumstances, an object of the present invention is to provide a microbial fuel cell that generates electricity by utilizing microorganisms present in wet mud.

  MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research in order to solve the said subject, this inventor discovered that the following invention corresponded to the said objective, and came to this invention.

That is, the present invention relates to the following inventions.
<1> A microbial fuel cell comprising an anode electrode and a cathode electrode electrically connected to the anode electrode, for producing electricity in wet mud containing mud sand , wherein the wet mud containing mud sand is a mudflat, The anode electrode is disposed inside a wet mud containing a microorganism that decomposes organic matter to produce electrons, and a partition is provided around the anode electrode to prevent polishing of the anode by the mud, and the wet mud contains The electrons produced by the microorganism are collected by the anode electrode, and the cathode electrode is placed in an external oxygen-containing atmosphere (except that the anode electrode is fixed to the partition) , the cathode by the electrons . A microbial fuel cell that generates electricity by reducing oxygen at an electrode.
<2> The microbial fuel cell according to <1>, wherein the partition for suppressing polishing of the anode by the mud sand is a partition of a cylindrical plastic whose upper and lower ends are open.
<3> A power generation method in wet mud containing mud sand using a microbial fuel cell, wherein the wet mud containing mud sand is a mudflat, and the microbial fuel cell is electrically connected to an anode electrode and the anode electrode. And the anode electrode is provided with a partition for preventing the polishing of the anode by the mud sand in the inside of the wet mud containing the microorganism which decomposes the organic matter and produces electrons. The cathode electrode is disposed in an external oxygen-containing atmosphere, and electrons generated by microorganisms contained in the wet mud are anode electrodes (except in the embodiment where the anode electrode is fixed to the partition). Power generation method to generate electricity by reducing oxygen at the cathode electrode with the electrons.
The electric power generation method as described in <3> whose partition for suppressing grinding | polishing of the anode by the <4> mud sand is a partition of the cylindrical plastic which the upper end and the lower end opened.

  According to the microbial fuel cell of the present invention, power can be generated by taking out the electrons generated by the decomposition of the microorganisms contained in the wet mud to the organic substance in the wet mud to the external circuit. At the same time, anaerobic soil contamination can be decomposed by microorganisms in the same manner as aerobic decomposition to promote purification.

It is a conceptual diagram of the microbial fuel cell of the present invention. It is a figure which shows the manufacturing method of an example of the electrode which can be used for the microbial fuel cell of this invention. It is a conceptual diagram which shows an example of the suitable embodiment of the microbial fuel cell of this invention. It is a power generation result using the wet mud collected at Ariake Sea Tidal Flat. It is the result of the power generation test (power generation amount) in Ariake Sea Tidal Flat. It is the result of the power generation test (change over time) in Ariake Sea Tidal Flat. It is the result of power generation in a tidal flat near Surabaya city, Indonesia. It is the result of the power generation test using various kinds of wet mud.

  Hereinafter, the present invention will be described in detail with reference to examples and the like, but the present invention is not limited to the following examples and the like, and can be implemented with various modifications without departing from the scope of the present invention.

  The microbial fuel cell of the present invention is a microbial fuel cell comprising an anode electrode and a cathode electrode electrically connected to the anode electrode, wherein the anode electrode is a wet type containing microorganisms that decompose organic matter to produce electrons. The microbial fuel cell is disposed inside the mud, and the electrons produced by the microorganisms contained in the wet mud are collected at the anode electrode, and the electrons are used to reduce oxygen at the cathode electrode to generate electricity. FIG. 1 shows a schematic view of the microbial battery of the present invention.

The metabolic reaction for energy acquisition of microorganisms consists of a large number of redox reactions involving the flow of electrons from an electron donor to an electron acceptor. By taking out electrons from the metabolic reaction of decomposition of the organic matter of the microorganism to the external circuit, it is possible to extract electric energy from the chemical energy of the organic matter catalyzed by the microorganism.
A feature of the microbial fuel cell of the present invention is to use microorganisms originally contained in wet mud as a catalyst and to use organic substances contained in wet mud as a fuel. That is, unlike the conventional microbial fuel cell, there is no need to immobilize the microorganism on the anode electrode or to supply the organic substance as the fuel.
The microbial fuel cell of the present invention can generate power with a simple configuration in which the anode electrode is disposed inside the target wet mud, and the cathode electrode electrically connected to the anode electrode is disposed under the oxidizing atmosphere. Therefore, it can be used as a low cost power generation system.
In addition, since the wet mud has low oxygen permeability, and the inside is necessarily in an anaerobic atmosphere, there is no need to artificially change the atmosphere of the anode electrode anaerobically.

In the microbial fuel cell of the present invention, it is speculated that the microorganism originally contained in the wet mud makes it possible to decompose the organic matter in the anaerobic environment in a mechanism similar to the oxidative decomposition of the organic matter by the aerobic microorganism.
The reason why aerobic microorganisms require oxygen is the same as the reason why humans need oxygen, and it is necessary to consume the electrons generated when acquiring energy by oxidation of organic matter for oxygen reduction. It is because there is. That is, if an environment capable of discarding electrons generated by metabolism outside the body is prepared, it is possible to promote the decomposition of the organic matter in the mud by the symbiosis of the aerobic microorganism and the anaerobic microorganism.
In the microbial fuel cell of the present invention, 1) the microorganism oxidizes and decomposes the organic matter, 2) the electron generated in the oxidation process is collected by the anode electrode, and 3) the cathode electrode arranged in the environment where oxygen exists. Guide 4) to reduce oxygen and consume electrons. In this way, power generation and purification of wet mud can proceed simultaneously.

Microorganisms inhabit all sources of nutrient sources. Microorganisms that live by clearing severe conditions such as low temperature, high temperature, high pressure, low pressure, acidity and alkalinity are superior in environmental adaptability. In the case of wet mud, microorganisms suitable for the environment of the wet mud are inhabited by obtaining a nutrient source from the mud.
The microbial fuel cell of the present invention can extract electric energy from the chemical energy of the organic matter catalyzed by the microorganism by taking out electrons to the external circuit from the metabolic reaction of the organic matter decomposition of the microorganism. Furthermore, at the same time, it is also possible to promote the decomposition and the purification by the microorganisms in the same manner as the aerobic mechanism, in the anaerobic soil.

  The "wet mud" in the present invention means a mud containing water having a degree of ion conductivity and containing an organic matter serving as a nutrient for microorganisms. That is, even "wet mud" that is sterilized and free of microorganisms is excluded from the "wet mud" in the present invention.

The microbial fuel cell of the present invention does not need to control the state of wet mud, and does not require a closed cell structure as in conventional microbial fuel cells, so it can be an open cell type cell. Therefore, the microbial fuel cell of the present invention can be applied not only to sludge treatment facilities but also to outdoor mud (animal excrement, sludge deposits from aquaculture farmland, mud flats, riverbed sludge, sludge from the bottom of dams) It is.
In addition, since the microbial fuel cell of the present invention may have a minimum configuration such as an anode electrode and a cathode electrode, power generation and purification can be performed at low cost. Although the amount of power generation varies depending on the condition of the wet mud, any type of wet mud can be generated in principle.

In the microbial fuel cell of the present invention, a microorganism having an extracellular electron transfer ability, which inhabits in the wet mud in which the anode electrode is disposed, is used as it is. That is, since the microorganism originally inhabiting wet mud is used as a catalyst for the microbial fuel cell, the cost of the microorganism is also unnecessary.
The microorganism in the wet mud to be used may be any microorganism having an extracellular electron transfer ability that decomposes the organic matter and releases electrons directly or indirectly to the anode electrode. Any of bacteria, microaerobic bacteria and oxygen-resistant bacteria can be used.

  Hereinafter, the anode electrode and the cathode electrode in the microbial fuel cell of the present invention will be described in detail. In addition, when it is not necessary to distinguish an anode electrode and a cathode electrode, these may be collectively called an "electrode."

As the anode electrode, one similar to the anode electrode in conventionally known microbial fuel cells can be used in principle.
On the other hand, an anode electrode is arrange | positioned inside the wet mud containing the microorganisms which decompose | disassemble organic substance and produce an electron, and collect | recovers the electron which generate | occur | produces by decomposition | disassembly of the organic substance by microorganisms. Therefore, the anode electrode is required to have durability in the environment inside the wet mud as well as electron conductivity. Therefore, a suitable electrode may be appropriately selected in consideration of the environment of the wet mud in which the anode electrode is embedded, the target power generation output, the power generation period, the cost of the electrode, and the like.

For example, a carbon-based electrode, platinum, a non-corrosive metal of titanium, or the like can be used as the anode electrode. It is preferable that the electrode has a large surface area per unit weight so that the electrons generated by the decomposition of the organic matter by the microorganism can be recovered with high efficiency.
Conductive fine particles may be supported on a substrate electrode as an anode electrode, and the transfer of electrons from microorganisms to the anode electrode can be promoted by having the conductive fine particles.

  FIG. 2 shows a method of manufacturing an electrode as an example suitable as an anode electrode. The said anode electrode makes titanium with high corrosion resistance the current collection base electrode, porous carbon powder is fixed to this by pressure heating, and it is used as an electrode. The carbon-based electrode immobilized by pressure heating has high electron conductivity and a large surface area, and thus is excellent in electrode performance. Moreover, since titanium and carbon which comprise the said electrode are excellent in chemical stability, it does not elute also under the environment of damp mud, and its environmental load is also small. Carbon also has the advantage of being highly compatible with microorganisms.

In addition, as described above, the microbial fuel cell of the present invention utilizes the microorganisms originally contained in the wet mud to recover the electrons generated by the decomposition of the organic matter contained in the wet mud by the anode electrode to generate electricity. One of the features is that it is possible to use a non-modified electrode on which microorganisms are not immobilized, but a modified electrode may be used in order to further enhance the functionality (for example, output and durability) of the electrode.
As such a modified electrode, for example, an electrode on which a microorganism different from the microorganism contained in wet mud is immobilized, an electrode on which a mediator is immobilized, and the like can be mentioned.

In the wet mud, the position at which the anode electrode is disposed may in principle be a potential difference with the cathode electrode, as long as the oxygen concentration is lower than the atmosphere in which the cathode electrode is disposed. However, in order to obtain a practical voltage (for example, -0.5 V) of a single cell structure (one pair of an anode electrode and a cathode electrode), the anode electrode needs to be in an anaerobic atmosphere. . In the mud, oxygen is difficult to permeate, and oxygen is consumed by microorganisms near the surface layer of the wet mud. Therefore, oxygen does not reach a few cm below the wet mud, which is a substantial anaerobic atmosphere. Although it depends on the condition of the wet mud, it is usually about 5 cm to become a substantial anaerobic atmosphere.
In addition, even at a depth where oxygen does not diffuse as it is and it does not become an anaerobic atmosphere, oxygen is bubbled by inert gas or oxygen non-permeable film is attached to the surface of wet mud, If the concentration is reduced, power generation at a practical voltage (for example, -0.5 V) is possible.
In addition, when the electrode is polished by mud sand such as a tidal flat, by installing a partition with a cylindrical thing around the anode electrode, the movement of the mud sand on the side is suppressed to suppress the polishing of the anode electrode. Is possible.

The cathode electrode is electrically connected to the anode electrode, and the electrons supplied from the anode electrode through an external circuit reduce oxygen to generate water. The cathode electrode is disposed in a solution in which oxygen is present or at a gas-liquid interface.
As the cathode electrode, for example, a carbon-based electrode, platinum, a non-corrosive metal of titanium, or the like can be used. It is preferable that the electrode has a large electrode surface area per unit weight so that the electrons generated by the decomposition of the organic matter by the microorganism can be collected with high efficiency.
In order to increase the number of reaction sites for oxygen reduction, the cathode electrode is preferably a large area electrode. Moreover, in order to raise the catalytic activity of oxygen reduction, the electrode by which metal catalyst microparticles | fine-particles (for example, platinum microparticles | fine-particles and palladium microparticles | fine-particles) were carry | supported is mentioned as one of the suitable electrodes.

  One of the preferable embodiments of the microbial fuel cell of the present invention is a constitution in which a cathode electrode is disposed in an oxygen-containing atmosphere outside the wet mud. As a typical configuration, as shown in FIG. 1, the anode electrode is disposed inside the wet mud, and the cathode electrode is placed in contact with the surface of the wet mud. Thus, power generation can be performed while decomposing the organic matter in the wet mud and purifying the wet mud with a very simple configuration of the anode electrode, the cathode electrode, and the conducting wire connecting the both electrodes.

  Further, in the microbial fuel cell of the present invention, when generating power more efficiently, the oxygen concentration difference between the anode electrode and the cathode electrode is increased, and the distance between the anode electrode and the cathode electrode is shortened to reduce resistance. It is preferable to adopt the configuration.

As one aspect of the microbial fuel cell of the present invention having such a configuration, a microbial fuel cell having a cell configuration schematically shown in FIG. 3 can be mentioned.
The microbial fuel cell shown in FIG. 3 comprises, in addition to the anode electrode and the cathode electrode, a diaphragm (separator) for preventing the anode electrode and the cathode electrode from coming in contact with each other and a double tube container which is impermeable to gas. Among the double tubular containers, an inner tubular container stores an electrolyte solution (for example, a NaCl solution), in which a cathode electrode is disposed. In addition, the outer tube-shaped container is designed to allow the flow of the inert gas, and the inert gas can be supplied as needed.

In FIG. 3, the anode electrode and the cathode electrode are disposed in the wet mud via the separator, and the cathode electrode is disposed in the electrolyte solution (NaCl solution) in the container. The separator is configured to selectively transmit protons (H ⁺ ) such as cation exchange membranes, and examples thereof include Nafion membranes used as separators for hydrogen fuel cells and the like. Other examples include aramid non-woven paper and Japanese paper, which can be expected to move protons quickly even with some oxygen permeable membranes. In order to further reduce the electrical resistance, it is preferable to dispose the anode electrode and the cathode electrode in contact with the separator.
As shown in FIG. 3, the inner tubular container in which the cathode electrode is disposed is open, and oxygen in air is dissolved and supplied. Note that oxygen may be forcibly supplied to the electrolyte solution by bubbling.

  Further, as described above, the outer tubular container is designed to allow the inert gas to flow, and oxygen can be prevented from being supplied from the surface of the wet mud to the inside of the wet mud. Therefore, even if the anode electrode is disposed at a depth (for example, less than 5 cm) of the wet mud where the oxygen diffuses from the wet mud surface and the anaerobic atmosphere does not occur, the inert gas flows through the anaerobic atmosphere. Power generation at a practical voltage (for example, .about.0.5 V).

  As described above, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. In particular, in the embodiment disclosed this time, matters not explicitly disclosed, such as operating conditions and conditions, various parameters, dimensions of components, weights, volumes, etc., deviate from the range normally practiced by those skilled in the art. And those skilled in the art will employ values that can easily be envisioned.

The microbial fuel cell of the present invention can also be used, for example, in the following.
(1) Sewage sludge treatment: Auxiliary power source of electric power required for sewage sludge treatment (2) Environment monitor: An environmental sensor using the change of power generation amount depending on the condition of soil. Since it is a self-sustaining type, the generated electricity can be used as a power source of a wireless transmitter, and a wide area environment can be automatically monitored.
(3) Promotion of sludge purification and power generation: By installing an anode electrode on the bottom of the river, dam bottom, aquaculture pond bottom, bottom of the sea, etc., decomposition of organic precipitates in the mud where oxygen does not reach and decomposition is not promoted And get power.
(4) Power generation from sludge after methane fermentation: It has been confirmed that power generation is possible even from sludge after methane fermentation.
(5) Soil remediation: By installing in soil with excess nutrient, it promotes the removal of excess nutrients in the mud that oxygen is difficult to reach.
(6) Power supply of robot: Used as a power source of a small robot.

  EXAMPLES Although an Example is given to the following and this invention is more concretely demonstrated to it, this invention is not limited to these.

Example 1
About 5 mL of wet mud of Ariake Sea Flats was collected in a 50 mL sample bottle, and a power generation test was performed using a microbial fuel cell having a configuration according to FIG. The depth at which the anode electrode was embedded was 1 cm, and the measurement temperature was 20 ° C. The power generation results are shown in FIG. The maximum voltage was 0.32 V, and the maximum power converted to an apparent electrode area of 1 m ² was about 600 mW.

The anode electrode, cathode electrode and separator used are as follows.
(Anode electrode)
A carbon paste prepared by dispersing 0.05 g of kettin black (1300 m ² / g) as porous carbon and 1.5 g of polyvinylidene fluoride as a binder in 30 mL of N-methyl-2-pyrrolidinone, 10 mm After applying on both sides of titanium mesh (100 mesh / inch, thickness 0.1 mm) of × 10 mm, it was used as an electrode by the method shown in FIG. The dry weight excluding the weight of the titanium mesh after application was 5 to 8 mg.
(Cathode electrode)
The cathode electrode was also prepared in the same manner as the anode electrode.
(Separator)
Aramid non-woven paper was used.

(Comparative example)
When heat generation was attempted under the same conditions of the same electrode arrangement and conditions as the above example using wet mud subjected to heat sterilization (twice 90 ° C.), no power was generated at all.
Since no special microorganism is added to the wet mud of the example, it is confirmed that the microorganism originally present in the collected wet mud functions as a catalyst for power generation in the microbial fuel cell of the present invention It was done.

(Example 2)
The following anode and cathode electrodes were installed in Ariake Sea Tidal Flat, and an open cell power generation test was conducted. The results are shown in FIG. The anode electrode was placed at a depth of 25 cm from the surface of the mud mud and kept as it was during the measurement. Moreover, in order to prevent the deterioration due to the polishing of the anode electrode by mud sand, the periphery of the anode electrode was surrounded by a cylindrical plastic with a diameter of about 30 cm (upper and lower vacant state) (FIG. 5, “enclosed”). Moreover, it measured also about the case where there is no enclosure (FIG. 5, "an enclosure nothing"). The cathode electrode was placed in seawater on a tidal flat each time of measurement (measurement about once every two weeks).
At the time of the measurement of FIG. 5, the air temperature was 25.degree. The maximum voltage was about 0.35 V, and the maximum power converted to an apparent electrode area of 1 m ² was 350 to 500 mW.
Also, Fig. 6 shows the time-dependent change of the power from August 2013, together with the outside air temperature, mud temperature, and the weather of the previous day. In addition, a measurement result is a case where the enclosure of an anode electrode is attached. Although the amount of electricity generated decreased as the outside air temperature and mud temperature decreased, it was confirmed that electricity was generated throughout the year. However, it turned out that there are other factors that affect power generation.

The anode electrode and cathode electrode which were used are as follows. The separator was not used.
(Anode electrode)
A carbon paste prepared by dispersing 0.05 g of kettin black (1300 m ² / g) as porous carbon and 1.5 g of polyvinylidene fluoride as a binder in 30 mL of N-methyl-2-pyrrolidinone, 25 mm After applying on both sides of titanium mesh (100 mesh / inch, thickness 0.1 mm) of × 100 mm, an electrode was formed by the method shown in FIG. The dry weight excluding the weight of the applied titanium mesh was 0.13 to 0.20 g.
(Cathode electrode)
The cathode electrode was also prepared in the same manner as the anode electrode.

(Example 3)
The following anode and cathode electrodes were installed in a tidal flat near Surabaya, Indonesia, and an open cell power generation test was conducted. The results are shown in FIG. In addition, the anode electrode was installed in the depth of 25 cm from the mud surface. The cathode electrode was placed in seawater on a tidal flat. The temperature was 29-31 ° C. The maximum voltage was about 0.3 V, and the maximum power converted to an apparent electrode area of 1 m ² was about 600 mW. It turned out that power generation equivalent to the measurement result in Ariake Sea Tidal Flat can be obtained.

The anode electrode and cathode electrode which were used are as follows. The separator was not used.
(Anode electrode)
A carbon paste prepared by dispersing 0.05 g of kettin black (1300 m ² / g) as porous carbon and 1.5 g of polyvinylidene fluoride as a binder in 30 mL of N-methyl-2-pyrrolidinone, 25 mm After applying on both sides of titanium mesh (100 mesh / inch, thickness 0.1 mm) of × 100 mm, an electrode was formed by the method shown in FIG. The dry weight excluding the weight of the applied titanium mesh was 0.13 to 0.20 g.
(Cathode electrode)
The cathode electrode was also prepared in the same manner as the anode electrode.

(Example 4)
A power generation test was conducted using a microbial fuel cell having a configuration according to FIG. 3 using a model wet mud other than the mud mud of a tidal flat. The results are shown in FIG. As model wet mud, water was also added to soil and excrement of animals and used as mud. The depth at which the anode electrode is embedded is 1 cm, and the measurement temperature is 15 to 20 ° C. As understood from the results of FIG. 8, the mud containing a large amount of organic matter and having a large amount of microorganisms inhabited showed higher power generation. This indicates that the microbial fuel cell of the present invention can be applied to environmental measurement to measure the degree of mud contamination.

The anode electrode, cathode electrode and separator used are as follows.
(Anode electrode)
A carbon paste prepared by dispersing 0.05 g of kettin black (1300 m ² / g) as porous carbon and 1.5 g of polyvinylidene fluoride as a binder in 30 mL of N-methyl-2-pyrrolidinone, 10 mm After applying on both sides of titanium mesh (100 mesh / inch, thickness 0.1 mm) of × 10 mm, it was used as an electrode by the method shown in FIG. The dry weight excluding the weight of the titanium mesh after application was 5 to 8 mg.
(Cathode electrode)
The cathode electrode was also prepared in the same manner as the anode electrode.
(Separator)
Aramid non-woven paper was used

  The microbial fuel cell of the present invention is a low cost power generation device because it can generate electricity using microorganisms present in wet mud without using a microorganism-immobilized electrode, for example, water treatment / environment Field (plant wastewater, sewage sludge, sludge in riverbed and dam bottom, sludge in aquaculture pond bottom and bottom, regional environmental measurement, treatment of livestock excrement, sludge processing in developing countries, biomass, wet mud sprayed from underground) It can be expected to be applied to agriculture field (soil remediation), robot field (energy source), etc.

Claims (4)

What is claimed is: 1. A microbial fuel cell comprising an anode electrode and a cathode electrode electrically connected to the anode electrode, for generating electricity in mud containing mud sand,
The wet mud including the mud sand is a tidal flat,
The anode electrode is disposed inside a wet mud containing a microorganism that decomposes organic matter to produce electrons, and a partition for suppressing polishing of the anode by mud sand is provided around the anode electrode (provided that the anode electrode is not Excluding electrons fixed to the partition). Electrons produced by microorganisms contained in the wet mud are collected by the anode electrode, the cathode electrode is placed in an external oxygen-containing atmosphere, and the electrons are cathode A microbial fuel cell characterized by generating electricity by reducing oxygen at an electrode.   The microbial fuel cell according to claim 1, wherein the partition for suppressing the polishing of the anode by the mud sand is a partition of a cylindrical plastic whose upper and lower ends are open. A method of generating electricity in wet mud containing mud sand using a microbial fuel cell, comprising:
The wet mud including the mud sand is a tidal flat,
The microbial fuel cell comprises an anode electrode and a cathode electrode electrically connected to the anode electrode,
The anode electrode is disposed inside a wet mud containing a microorganism that decomposes organic matter to produce electrons, and a partition for suppressing polishing of the anode by mud sand is provided around the anode electrode (provided that the anode electrode is not Except that the cathode is fixed to the partition) , the cathode electrode is disposed in an external oxygen-containing atmosphere,
An electric power generation method characterized in that electrons generated by microorganisms contained in the wet mud are collected at an anode electrode, and oxygen is reduced at the cathode electrode by the electrons to generate electric power.   The power generation method according to claim 3, wherein the partition for suppressing the polishing of the anode by the mud sand is a partition of a cylindrical plastic whose upper and lower ends are open.