Microbial fuel cell, and method for manufacturing microbial fuel cell anode

Abstract

To provide a microbial fuel cell and a method for manufacturing a microbial fuel cell anode capable of reducing anode weight, while suppressing delay in electron transfer speed at the anode in a microbial fuel cell in which microorganisms are carried on the anode.SOLUTION: A microbial fuel cell includes a negative electrode vessel and a positive electrode vessel separated by a separating membrane, and the anode is composed of a plastic member having a first metal film. Microorganisms are carried on the anode. A method for manufacturing a microbial fuel cell anode electrode includes: a first metal film formation step for forming a first metal film on a plastic member by electroless plating; and a microbial carrying step for carrying microorganisms on the first metal film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a microbial fuel cell and a method for manufacturing an anode of a microbial fuel cell.

Background Art

[0002] In recent years, the development of microbial fuel cells has been underway. A microbial fuel cell is a device that uses microorganisms to convert organic substances contained in wastewater or the like into electrical energy. For example, a microbial fuel cell has been proposed in which microorganisms are attached to an anode composed of graphite or a metal such as titanium or stainless steel, and the microorganisms oxidize organic substances to generate electrons (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when graphite is used for the anode, there is a problem that the electron transfer rate in the carbon constituting the graphite is slow. On the other hand, when the anode is made of metal, the electron transfer rate becomes fast, but the weight increases. When using organic substances contained in wastewater or the like, that is, when utilizing a microbial fuel cell in a wastewater treatment facility, for example, in a utilization method in which a wastewater treatment tank is used as a negative electrode tank and an anode is immersed therein, in order to increase the power generation efficiency, the anode becomes extremely large according to the size of the wastewater treatment tank. In such a case, if the anode is made of metal, its weight also becomes large, and there is a problem that a large amount of cost is required for, for example, maintenance work and various handling.

[0005] The present disclosure has been made in view of the above circumstances, and in a microbial fuel cell in which microorganisms are supported on an anode, it is a main object to provide a microbial fuel cell capable of suppressing a decrease in the electron transfer rate at the anode and reducing the weight of the anode, and a method for manufacturing the anode of the microbial fuel cell.

Means for Solving the Problems

[0006] The microbial fuel cell of the present disclosure has a negative electrode tank and a positive electrode tank via a diaphragm, and the anode is composed of a plastic member having a first metal film, and microorganisms are supported on the anode.

[0007] In the microbial fuel cell of the present disclosure, a second metal film containing at least one of zinc, manganese, cobalt, or copper may be provided on the first metal film.

[0008] In the microbial fuel cell of the present disclosure, the first metal film may contain nickel.

[0009] In the microbial fuel cell of the present disclosure, the plastic member may be any of a plastic non-woven fabric, plastic mesh fibers, porous plastic, a plastic molded product having an uneven structure, and a plastic molded product having through holes.

[0010] The microbial fuel cell of the present disclosure has a negative electrode solution containing ammonia in the negative electrode tank, and nitrifying bacteria may be supported as the microorganisms.

[0011] The microbial fuel cell of the present disclosure has a negative electrode solution containing an organic substance in the negative electrode tank, and microorganisms that oxidize the organic substance to generate electrons may be supported as the microorganisms.

[0012] In the microbial fuel cell of the present disclosure, the microorganisms that oxidize the organic substance to generate electrons may be Shewanella bacteria or Geobacter bacteria.

[0013] In the microbial fuel cell of the present disclosure, a microbial carrier carrying anammox bacteria may be immersed in the negative electrode solution.

[0014] The method for manufacturing an anode of a microbial fuel cell of the present disclosure includes a first metal film forming step in which a first metal film is formed on a plastic member by electroless plating, and a microbial loading step in which microorganisms are loaded on the first metal film, and the microorganisms are nitrifying bacteria or microorganisms that oxidize organic substances to generate electrons.

[0015] The method for manufacturing an anode of a microbial fuel cell of the present disclosure includes a first metal film forming step in which a first metal film is formed on a plastic member by electroless plating, a second metal film forming step in which a second metal film containing at least one of zinc, manganese, cobalt, or copper is formed on the first metal film by electrolytic plating, and a microbial loading step in which microorganisms are loaded on the second metal film, and the microorganisms may be nitrifying bacteria or microorganisms that oxidize organic substances to generate electrons.

[0016] In the method for manufacturing an anode of a microbial fuel cell of the present disclosure, the plastic member may be any one of a plastic nonwoven fabric, plastic mesh fiber, porous plastic, a plastic molded product having an uneven structure, or a plastic molded product having through holes.

[0017] In the method for manufacturing an anode of a microbial fuel cell of the present disclosure, the first metal film may contain nickel.

[0018] In the method for manufacturing an anode of a microbial fuel cell of the present disclosure, the microorganisms that oxidize organic substances to generate electrons may be Shewanella bacteria or Geobacter bacteria.

Advantages of the Invention

[0019] According to the present disclosure, there can be provided a microbial fuel cell in which microorganisms are supported on an anode, and a method for manufacturing the anode of the microbial fuel cell, capable of suppressing a decrease in the electron transfer rate at the anode while reducing the weight of the anode.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings and the like. However, the present disclosure can be implemented in many different aspects and is not to be construed as limited to the description of the embodiments exemplified below. Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is merely an example and does not limit the interpretation of the present disclosure. Further, in this specification and each drawing, the same reference numerals may be assigned to the same elements as those described above with respect to the previously presented drawings, and detailed descriptions may be omitted as appropriate.

[0022] In this specification, when expressing the mode of arranging one member on another member, if simply denoted as "on" or "under", unless otherwise specified, it includes both the case of arranging another member directly above or below so as to be in contact with a certain member, and the case of arranging another member above or below a certain member with yet another member in between. Also, in this specification, when expressing the mode of arranging one member on the surface of another member, if simply denoted as "on the surface", unless otherwise specified, it includes both the case of arranging another member directly above or below so as to be in contact with a certain member, and the case of arranging another member above or below a certain member with yet another member in between.

[0023] Hereinafter, the microbial fuel cell and the method for manufacturing the anode of the microbial fuel cell according to the present disclosure will be described in detail.

[0024] <Microbial fuel cell> The microbial fuel cell of the present disclosure is mainly characterized by the anode, and the other components can be the same as those of known microbial fuel cells.

[0025] FIG. 1 is a schematic diagram showing an example of the microbial fuel cell of the present disclosure. As shown in FIG. 1, the microbial fuel cell 1 has a negative electrode tank 12 and a positive electrode tank 13 with a separator 11 interposed therebetween. A negative electrode solution 15 is contained in the negative electrode tank 12, and the anode 21 is immersed in the negative electrode solution 15. A positive electrode solution 16 is contained in the positive electrode tank 13, and the cathode 22 is immersed in the positive electrode solution 16. The anode 21 and the cathode 22 are electrically connected via an external circuit 23.

[0026] In the microbial fuel cell 1, microorganisms 51 are supported on the anode 21. The microorganisms 51 decompose ammonia or organic substances contained in the negative electrode solution 15, and the electrons generated during this process move from the anode 21 to the cathode 22 via the external circuit 23. Electrical energy corresponding to the product of the potential difference between the anode 21 and the cathode 22 and the current flowing through the external circuit 23 is obtained in the external circuit 23. Hydrogen ions generated by the reaction at the anode 21 enter the positive electrode tank 13 from the negative electrode tank 12 through the diaphragm 11, and these hydrogen ions react with electrons and oxygen at the cathode 22 to generate water.

[0027] In the microbial fuel cell 1 shown in FIG. 1, a form having one negative electrode tank 12 and one positive electrode tank 13 with one diaphragm 11 interposed therebetween is illustrated, but the form of the microbial fuel cell of the present disclosure is not limited thereto. For example, a form in which a plurality of negative electrode tanks 12 and a plurality of positive electrode tanks 13 are alternately arranged via a plurality of diaphragms 11 may be used.

[0028] Also, in the microbial fuel cell 1 shown in FIG. 1, a form in which one anode 21 is immersed in the negative electrode solution 15 of the negative electrode tank 12 is illustrated, but the form of the microbial fuel cell of the present disclosure is not limited thereto. For example, a form in which a plurality of anodes 21 are immersed in the negative electrode solution 15 of the negative electrode tank 12 may be used. The same applies to the cathode 22 immersed in the positive electrode solution 16 of the positive electrode tank 13.

[0029] As described above, the microbial fuel cell of the present disclosure is mainly characterized by the anode, and other configurations can be the same as those of known microbial fuel cells. Hereinafter, the anode used in the microbial fuel cell of the present disclosure will be described in detail.

[0030] <Anode> (First Embodiment) FIG. 2 is a schematic cross-sectional view showing a configuration example of the anode of the microbial fuel cell of the present disclosure. More specifically, FIG. 2 is a schematic cross-sectional view showing a configuration example of the first embodiment of the anode of the microbial fuel cell of the present disclosure.

[0031] As shown in FIG. 2, the anode 21A has a first metal film 41 on a substrate 31, and microorganisms 51 are supported on the first metal film 41. In the anode 21A, the form of supporting the microorganisms 51 is a form in which the microorganisms 51 are attached and fixed on the first metal film 41.

[0032] The anode 21A shown in FIG. 2 has a first metal film 41 on a substrate 31. Therefore, even when the substrate 31 is made of a non-conductive material or a material with low conductivity, since the first metal film 41 has conductivity, the electrons generated by the action of the supported microorganisms 51 can be carried by the first metal film 41.

[0033] And since the first metal film 41 is made of metal, the electron transfer rate is fast. That is, when using graphite as the anode, there was a problem that the electron transfer rate in the carbon that constitutes graphite was slow. However, in the anode 21A, since it has the first metal film 41, it is possible to suppress the decrease in the electron transfer rate.

[0034] Also, in the anode 21A, by making the substrate 31 made of a material lighter than metal, that is, by making the density of the substrate 31 smaller than the density of metal, the weight of the anode 21A can be reduced. Examples of the material constituting the substrate 31 include plastic members.

[0035] Note that the anode 21A shown in FIG. 2 has a first metal film 41 on both sides of the substrate 31, and microorganisms 51 are respectively supported on each first metal film 41. However, the anode of the present disclosure is not limited to this.

[0036] For example, the anode of the present disclosure may be in a form having a first metal film 41 only on one side of the base material 31, with microorganisms 51 supported on the first metal film 41. Further, the anode of the present disclosure may be in a form having a first metal film 41 only on one side of the base material 31, with microorganisms 51 supported on the first metal film 41, and also with microorganisms 51 supported on the other side of the base material 31 (the side without the first metal film 41).

[0037] Here, if it is in a form where each of the two sides of the base material 31 has a first metal film 41, and microorganisms 51 are respectively supported on each of the first metal films 41, like the anode 21A shown in FIG. 2, electrical energy can be extracted more efficiently. That is, if it is in a form where each of the two sides of the base material 31 has a first metal film 41, and microorganisms 51 are respectively supported on each of the first metal films 41, more microorganisms 51 can be supported than in a form where the microorganisms 51 are supported only on one side of the base material 31. Further, since the electrons generated by the action of the microorganisms 51 supported on both sides of the base material 31 are carried by the first metal films 41 on both sides of the base material 31, electrical energy can be extracted more efficiently than in a form where the first metal film 41 is supported only on one side of the base material 31.

[0038] (Second Embodiment) FIG. 3 is a schematic cross-sectional view showing another configuration example of the anode of the microbial fuel cell of the present disclosure. More specifically, FIG. 3 is a schematic cross-sectional view showing a configuration example of the second embodiment of the anode of the microbial fuel cell of the present disclosure.

[0039] The anode 21B shown in FIG. 3 has a first metal film 41 on a substrate 31, has a second metal film 42 on the first metal film 41, and has microorganisms 51 supported on the second metal film 42. In the anode 21B, the form of supporting the microorganisms 51 is a form in which the microorganisms 51 are attached and fixed on the second metal film 42. That is, the configuration of the anode 21B shown in FIG. 3 corresponds to a configuration having a second metal film 42 between the first metal film 41 and the microorganisms 51 of the anode 21A shown in FIG. 2.

[0040] The anode 21B shown in FIG. 3 has a first metal film 41 on a substrate 31 and has a second metal film 42 on the first metal film 41. Therefore, even when the substrate 31 is made of a material having no conductivity or a material having low conductivity, since the first metal film 41 and the second metal film 42 have conductivity, electrons generated by the action of the supported microorganisms 51 can be carried by the first metal film 41 and the second metal film 42.

[0041] And since the first metal film 41 and the second metal film 42 are made of metal, the electron transfer rate is fast. That is, when graphite is used for the anode, there is a problem that the electron transfer rate in the carbon constituting the graphite is slow. However, in the anode 21B, since it has the first metal film 41 and the second metal film 42, it is possible to suppress the decrease in the electron transfer rate.

[0042] Also, in the anode 21B, by making the substrate 31 made of a material lighter than metal, that is, by making the density of the substrate 31 smaller than the density of metal, the weight of the anode 21B can be reduced. Examples of the material constituting the substrate 31 include plastic members.

[0043] In addition, by including a metal that promotes the growth of the microorganisms 51 in the second metal film 42, it becomes possible to suppress the decrease in the microorganisms 51 supported on the anode 21B, and it becomes possible to maintain the generation of electrical energy by the microbial fuel cell including the anode 21B for a long period of time.

[0044] The second metal film 42 contains at least one of zinc, manganese, cobalt, or copper as the metal. And, for example, the microorganism 51 has the ability to decompose ammonia. Examples of such a microorganism 51 include nitrifying bacteria. Also, for example, the microorganism 51 has the ability to oxidize organic matter to generate electrons. Examples of such a microorganism 51 include Shewanella bacteria or Geobacter bacteria. Geobacter bacteria are a type of iron-reducing bacteria that obtain energy by reducing iron(III) ions to oxidize acetic acid to carbon dioxide. Geobacter bacteria are Gram-negative anaerobic bacilli with flagella and belong to the family Geobacteraceae. The reference species is Geobacter metallireducens. Subspecies include G. sulfurreducens, G. bremensis, and G. metallireducens.

[0045] It is known that microorganisms such as the above-mentioned nitrifying bacteria grow in an environment where zinc, manganese, cobalt, or copper is present. Among them, the presence of zinc is preferable. Therefore, if at least one of zinc, manganese, cobalt, or copper is included in the layer constituting the surface on which the microorganism 51 is supported (the second metal film 42 in the anode 21B shown in FIG. 3), the microorganism 51 is likely to grow. Therefore, the anode 21B having the above configuration can suppress the decrease in the supported microorganism 51 and enable the generation of electrical energy to be maintained for a long period.

[0046] Also, when adding heavy metals such as zinc to the liquid, there is a problem that if the liquid containing the added zinc etc. flows out, it will contribute to pollution. However, as in the present disclosure, if zinc etc. is immobilized as a metal film on the anode, the above problem can also be solved.

[0047] Note that the anode 21B shown in FIG. 3 has a first metal film 41 on each of the two sides of the base material 31, a second metal film 42 on each of the first metal films 41, and microorganisms 51 are carried on each of the second metal films 42. However, the anode of the microbial fuel cell of the present disclosure is not limited to this.

[0048] For example, the anode of the microbial fuel cell of the present disclosure may have a first metal film 41 only on one side of the base material 31, a second metal film 42 on the first metal film 41, and microorganisms 51 are carried on the second metal film 42. Further, the anode of the microbial fuel cell of the present disclosure may have a first metal film 41 only on one side of the base material 31, a second metal film 42 on the first metal film 41, microorganisms 51 are carried on the second metal film 42, and microorganisms 51 are also carried on the other side of the base material 31 (the side without the first metal film 41 and the second metal film 42).

[0049] Here, in the form where, like the anode 21B shown in FIG. 3, there is a first metal film 41 on each of the two sides of the base material 31, a second metal film 42 on each of the first metal films 41, and microorganisms 51 are carried on each of the second metal films 42, more microorganisms 51 can be carried than in the form where microorganisms 51 are carried only on one side of the base material 31. Further, since the electrons generated by the action of the microorganisms 51 carried on both sides of the base material 31 are carried by the first metal film 41 and the second metal film 42 on both sides of the base material 31, electrical energy can be extracted more efficiently than in the form where the first metal film 41 and the second metal film 42 are carried only on one side of the base material 31.

[0050] Hereinafter, each element constituting the anode 21 (anode 21A, anode 21B) will be described.

[0051] (Base material) In the anode 21 (the anode 21A shown in FIG. 2 and the anode 21B shown in FIG. 3), since it has at least the first metal film 41 on the base material 31, even when the base material 31 is made of a material having no conductivity or a material having low conductivity, the anode 21 can function as an electrode.

[0052] The base material 31 is composed of a plastic member. By configuring the base material 31 with a plastic member having a lower density than that of metal, the weight of the anode 21 can be reduced. Examples of the plastic member constituting the base material 31 include any one of a plastic non-woven fabric, plastic mesh fiber, porous plastic, a plastic molded product having an uneven structure, and a plastic molded product having a through-hole. The base material 31 preferably has a large surface area per unit weight so that more microorganisms can be supported.

[0053] (The first metal film) The first metal film 41 is a film provided on the base material 31. As a method for forming the first metal film 41 on the base material 31, an electroless plating method can be preferably used. As the material constituting the first metal film 41, in the case of the anode 21A shown in FIG. 2, any material that can conduct electricity as an anode and can adhere and fix the microorganisms 51 can be used. In the case of the anode 21B shown in FIG. 3, any material that can function as a seed layer when the second metal film 42 is formed by an electrolytic plating method can be used. Preferably, a material containing nickel can be cited as the material constituting the first metal film 41.

[0054] The first metal film 41 may have a single-layer structure or a multi-layer structure. For example, the first metal film 41 may have a two-layer structure in which a lower layer film containing copper is first formed on the base material 31, and then an upper layer film containing nickel is formed thereon. By forming the lower layer film having copper, the conductivity can be increased, and accordingly, the upper layer film can be made thinner. As a result, even if it has a two-layer structure, it is possible to reduce the film thickness of the first metal film 41. As a method for forming the lower layer film and the upper layer film, an electroless plating method can be used for both.

[0055] The film thickness of the first metal film 41 only needs to be such that in the case of the anode 21A shown in FIG. 2, it can conduct electricity as an anode and can adhere and fix the microorganisms 51. In the case of the anode 21B shown in FIG. 3, it only needs to be able to function as a seed layer when the second metal film 42 is formed by an electrolytic plating method. On the other hand, if the film thickness of the first metal film 41 is unnecessarily large, there is a risk of increasing the cost. Also, if the film thickness is unnecessarily large, the first metal film 41 may fill the holes and irregularities of the base material 31, resulting in a decrease in the amount of microorganisms that can be supported.

[0056] In the case of the anode 21A shown in FIG. 2, the film thickness of the first metal film 41 can be, for example, 0.1 μm or more and 20 μm or less, preferably 0.2 μm or more and 10 μm or less. If the film thickness of the first metal film 41 is 0.1 μm or more, it can conduct electricity as an anode and can adhere and fix the microorganisms 51. If the film thickness of the first metal film 41 is 20 μm or less, problems such as from the perspective of cost do not particularly occur. Also, if the film thickness of the first metal film 41 is 20 μm or less, it is possible to suppress the first metal film 41 from filling the holes and irregularities of the base material 31.

[0057] Also, regarding the film thickness of the first metal film 41, in the case of the anode 21B shown in FIG. 3, for example, it can be 0.1 μm or more and 15 μm or less, preferably 0.2 μm or more and 7 μm or less. If the film thickness of the first metal film 41 is 0.1 μm or more, it can function as a seed layer when forming the second metal film 42 by electrolytic plating. If the film thickness of the first metal film 41 is 15 μm or less, problems such as from the perspective of cost do not particularly occur. Also, if the film thickness of the first metal film 41 is 15 μm or less, it is possible to suppress the first metal film 41 from filling the holes and unevenness of the base material 31.

[0058] The film thickness of the above-mentioned first metal film 41 is obtained by a method of identifying the layer constituting the first metal film 41 with a laser microscope from the cross-section of a test piece (10 mm × 10 mm in plan view) cut out from the anode 21 and measuring its thickness.

[0059] (Second metal film) The second metal film 42 contains at least one of zinc, manganese, cobalt, or copper as a metal. As described above, it is known that microorganisms such as nitrifying bacteria grow in an environment where zinc, manganese, cobalt, or copper is present. Among them, the presence of zinc is preferable. Therefore, if at least one of zinc, manganese, cobalt, or copper is contained in the layer constituting the surface on which the microorganisms 51 are supported (the second metal film 42 in the anode 21B shown in FIG. 3), the microorganisms 51 are likely to grow. Therefore, the anode 21B having the above configuration can suppress the decrease of the supported microorganisms 51 and can maintain the generation of electrical energy for a long period. As a method for forming the second metal film 42, an electrolytic plating method is preferably used.

[0060] The film thickness of the second metal film 42 only needs to be a thickness that can conduct electricity as an anode and can adhere and fix the microorganisms 51. On the other hand, if the film thickness is unnecessarily large, there is a risk of increasing the cost. Also, if the film thickness is unnecessarily large, the second metal film 42 may fill the holes and unevenness of the base material 31, and there is also a risk that the amount of microorganisms that can be supported will decrease.

[0061] The film thickness of the second metal film 42 can be, for example, 0.1 μm or more and 50 μm or less, preferably 0.2 μm or more and 20 μm or less. If the film thickness of the second metal film 42 is 0.1 μm or more, electricity can flow as an anode, and the microorganisms 51 can be adhered and fixed. If the film thickness of the second metal film 42 is 50 μm or less, there will be no particular problem in terms of cost or the like. Further, if the film thickness of the second metal film 42 is 50 μm or less, it is possible to suppress the second metal film 42 from filling the holes and unevenness of the base material 31.

[0062] The film thickness of the second metal film 42 described above is obtained by a method of identifying the layer constituting the second metal film 42 with a laser microscope from the cross section of a test piece (10 mm × 10 mm in plan view) cut out from the anode 21 and measuring its thickness.

[0063] (Microorganisms) The microorganisms 51 supported on the anode 21 react with substances contained in the negative electrode solution in a microbial fuel cell to generate electrons. In the microbial fuel cell of the present disclosure, the microorganisms 51 supported on the anode 21 can be the same as those in known microbial fuel cells.

[0064] In the microbial fuel cell 1 shown in FIG. 1, when the substance contained in the negative electrode solution 15 is ammonia, the microorganisms 51 include microorganisms that change ammonia to nitrous acid. Examples of the microorganisms that change ammonia to nitrous acid include nitrifying bacteria. Further, when the substance contained in the negative electrode solution 15 is an organic substance, the microorganisms 51 include microorganisms that oxidize the organic substance to generate electrons. Examples of the microorganisms that oxidize the organic substance to generate electrons include Shewanella bacteria or Geobacter bacteria.

[0065] <Modified example of microbial fuel cell> In the microbial fuel cell of the present disclosure, when the substance contained in the negative electrode solution 15 is ammonia, a microbial carrier carrying anammox bacteria may be immersed in the negative electrode solution 15. When nitrifying bacteria containing ammonia-oxidizing bacteria are supported on the anode 21, a microbial carrier carrying anammox bacteria is immersed in the negative electrode solution 15, and wastewater containing ammonia is supplied to the negative electrode tank 12, electric energy can be extracted from the ammonia contained in this wastewater for power generation, and the reaction of denitrifying the ammonia in the wastewater can be carried out simultaneously. The reaction of denitrifying the ammonia in the wastewater is carried out by ammonia-oxidizing bacteria converting ammonia nitrogen (NH4-N) into nitrite nitrogen (NO2-N), and anammox bacteria removing nitrogen by utilizing the anammox reaction.

[0066] As the ammonia-oxidizing bacteria, any bacteria that can convert ammonia nitrogen (NH4-N) into nitrite nitrogen (NO2-N) can be used. For example, bacteria belonging to the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, Nitrosovibrio, etc. can be used. For example, the ammonia-oxidizing bacteria can be obtained from activated sludge recovered from conventional wastewater treatment facilities.

[0067] As the anammox bacteria, any bacteria that can perform the anammox reaction can be used. For example, Candidatus Brocadia, Candidatus Kuenenia, Candidatus Jettenia, Candidatus Anammoxoglobus, Candidatus Scalindua, Candidatus Anammoximicrobium, etc. can be used. For example, the anammox bacteria can be obtained from activated sludge recovered from conventional wastewater treatment facilities.

[0068] <Method for manufacturing anode of microbial fuel cell> Next, a method for manufacturing the anode of the microbial fuel cell of the present disclosure will be described. FIG. 4 is a diagram showing an example of the method for manufacturing the anode of the microbial fuel cell of the present disclosure. More specifically, FIG. 4 is a diagram showing an example of the method for manufacturing the anode 21A shown in FIG. 2. Further, FIG. 5 is a diagram showing another example of the method for manufacturing the anode of the microbial fuel cell of the present disclosure. More specifically, FIG. 5 is a diagram showing an example of the method for manufacturing the anode 21B shown in FIG. 3.

[0069] First, the method for manufacturing the anode shown in FIG. 4 will be described. In the method for manufacturing the anode shown in FIG. 4, first, as shown in FIG. 4(a), a base material 31 is prepared, and then, as shown in FIG. 4(b), a first metal film 41 is formed on the base material 31 (first metal film forming step).

[0070] As a method for forming the first metal film 41 on the base material 31, an electroless plating method can be preferably used. As a material constituting the first metal film 41, a material containing nickel can be preferably cited.

[0071] Thereafter, as shown in FIG. 4(c), microorganisms 51 are supported on the first metal film 41 (microorganism supporting step). As a supporting method, a method in which the laminate 61 (the laminate in which the first metal film 41 is formed on the base material 31) shown in FIG. 4(b) is immersed in a liquid containing the microorganisms 51 is preferably used. By this immersion, the microorganisms 51 are adhered and fixed on the first metal film 41. In the anode 21A, the form of supporting the microorganisms 51 is a form in which the microorganisms 51 are adhered and fixed on the first metal film 41. The laminate that becomes the anode 21A after the microorganisms 51 are supported may have the liquid contained therein appropriately removed by a treatment such as suction filtration.

[0072] In addition, in the method for manufacturing the anode shown in FIG. 4, a manufacturing method is shown in which the first metal film 41 is formed on both surfaces of the base material 31, and the microorganisms 51 are supported on each of the first metal films 41, but the method for manufacturing the anode of the microbial fuel cell of the present disclosure is not limited to this.

[0073] For example, a manufacturing method may be such that the first metal film 41 is formed only on one side of the base material 31, and the microorganism 51 is supported on the first metal film 41. Also, a manufacturing method may be such that the first metal film 41 is formed only on one side of the base material 31, the microorganism 51 is supported on the first metal film 41, and the microorganism 51 is also supported on the other side (the side without the first metal film 41) of the base material 31.

[0074] Here, as in the manufacturing method of the anode shown in FIG. 4, if the first metal film 41 is formed on both sides of the base material 31, and the microorganism 51 is supported on each first metal film 41, more microorganisms 51 can be supported by the anode 21A.

[0075] Next, the manufacturing method of the anode shown in FIG. 5 will be described. In the manufacturing method of the anode shown in FIG. 5, first, as shown in FIG. 5(a), the base material 31 is prepared, and then, as shown in FIG. 5(b), the first metal film 41 is formed on the base material 31 (first metal film forming step).

[0076] As a method for forming the first metal film 41 on the base material 31, electroless plating can be mentioned. As a material constituting the first metal film 41, a material containing nickel can be preferably mentioned.

[0077] Next, as shown in FIG. 5(c), the second metal film 42 is formed on the first metal film 41 (second metal film forming step). The second metal film 42 contains at least one of zinc, manganese, cobalt, or copper as a metal. As a method for forming the second metal film 42 on the first metal film 41, electroplating can be mentioned.

[0078] In the manufacturing method of the anode shown in FIG. 5, since the first metal film 41 is formed on the base material 31 and the first metal film 41 has conductivity, electroplating is preferably used as a method for forming the second metal film 42.

[0079] Thereafter, as shown in FIG. 5(d), microorganisms 51 are supported on the second metal film 42 (microorganism support step). As a method of support, a method in which the laminate 62 shown in FIG. 5(c) (a laminate in which the first metal film 41 is formed on the base material 31 and the second metal film 42 is formed on the first metal film 41) is immersed in a liquid containing the microorganisms 51 is preferably used. By this immersion, the microorganisms 51 are adhered and fixed on the second metal film 42. The form of support of the microorganisms 51 in the anode 21B is a form in which the microorganisms 51 are adhered and fixed on the second metal film 42. The laminate that becomes the anode 21B after the microorganisms 51 are supported may have the contained liquid appropriately removed by treatment such as suction filtration.

[0080] In addition, in the method for manufacturing the anode shown in FIG. 5, a manufacturing method is shown in which the first metal film 41 is formed on both surfaces of the base material 31, the second metal film 42 is formed on each first metal film 41, and the microorganisms 51 are supported on each second metal film 42. However, the method for manufacturing the anode of the microbial fuel cell of the present disclosure is not limited to this.

[0081] For example, a manufacturing method may be used in which the first metal film 41 is formed only on one side of the base material 31, the second metal film 42 is formed on the first metal film 41, and the microorganisms 51 are supported on the second metal film 42. Further, a manufacturing method may be used in which the first metal film 41 is formed only on one side of the base material 31, the second metal film 42 is formed on the first metal film 41, the microorganisms 51 are supported on the second metal film 42, and the microorganisms 51 are also supported on the other side of the base material 31 (the surface having no first metal film 41 and second metal film 42).

[0082] As described above, the microbial fuel cell and the method for manufacturing the anode of the microbial fuel cell according to the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments. The above-described embodiments are examples, and those having substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibiting the same operational effects are included in the technical scope of the present disclosure in any case.

Examples

[0083] Hereinafter, examples and comparative examples will be shown for the embodiments of the present disclosure and described in detail. However, the embodiments of the present disclosure are not limited to these examples. The microbial fuel cell produced in this example is for the purpose of measuring the variation in potential difference over time and is a simple one. For example, silicon, which is an insulating material, is used between the anode and the cathode.

[0084] (Example 1) (Fabrication of Anode) As a base material, a polyester nonwoven fabric cell sheet CS-50 (manufactured by Maeda Kogyo Seni Co., Ltd.) was used, and electroless nickel plating was performed by the following treatment.

[0085] (Catalyst Treatment) The above nonwoven fabric cell sheet was immersed in an aqueous solution containing 0.3 g / L of palladium chloride, 15.0 g / L of stannous chloride, and 200 mL / L of hydrochloric acid at 30 °C for 10 minutes, then washed with water, and then dried in the air at a temperature of 80 °C.

[0086] (Activation Treatment) The nonwoven fabric cell sheet subjected to the above catalyst treatment was rinsed with hydrochloric acid water containing 200 mL / L of hydrochloric acid for 3 minutes.

[0087] (Electroless Plating Treatment) The nonwoven fabric cell sheet subjected to the above activation treatment was immersed in an aqueous solution containing 25 g / L of nickel sulfate, 25 g / L of sodium hypophosphite, and 50 g / L of sodium pyrophosphate at pH 10.5 and 50 °C for 10 minutes, then washed with water, and then dried in the air at a temperature of 80 °C.

[0088] (Microorganism support) Next, 10 mL of a microbial agent BFL5800 (manufactured by Meito Kasei Co., Ltd.) containing nitrifying bacteria Nitrosomonas was dissolved in 100 mL of warm water at 30°C and placed in a polypropylene vat. The nonwoven fabric C sheet that had been subjected to the electroless plating treatment described above was immersed in this solution at 30°C for 3 hours to allow microorganisms to adhere. In this way, the anode of the microbial fuel cell of Example 1 was fabricated.

[0089] (Fabrication of microbial fuel cell and measurement of potential difference on day 0) Next, the above anode was suction-filtered with a Buchner funnel having a diameter of 90 mm, immersed in a polypropylene vat containing 100 mL of an aqueous solution containing 40 g / L of glucose, 8 g / L of ammonium sulfate, and 9 g / L of yeast extract, and left at room temperature for 48 hours. Then, the anode was taken out from the polypropylene vat, co-washed with an ammoniacal yeast extract aqueous solution, suction-filtered with a Buchner funnel having a diameter of 90 mm, and immersed in a polypropylene pad containing 100 mL of an ammoniacal yeast extract aqueous solution. On the other hand, as the cathode, a carbon felt SG-250S (manufactured by Osaka Tamashii Co., Ltd.) coated with silicon on one side was prepared, immersed in a polypropylene pad so as to face the above anode through the side of the silicon-coated surface, the above anode and cathode were connected with a conductive cable via an external resistance of 100 Ω, and the potential difference between the anode and cathode was measured. The numerical value of this measurement result is described as the value on day 0 of Example 1 in Table 1 below.

[0090] (Measurement of potential difference on day 2) Thereafter, the above anode was taken out and immersed in a 100 mL aqueous solution containing 40 g / L of glucose, 8 g / L of ammonium sulfate, and 9 g / L of yeast extract in a polypropylene pad, and left at room temperature for 48 hours. Thereafter, the microbial carrier was taken out from the polypropylene pad, co-washed with an ammoniacal yeast extract aqueous solution, then suction-filtered through a Buchner funnel with a diameter of 90 mm, and immersed in a polypropylene pad containing 100 mL of the ammoniacal yeast extract aqueous solution. Next, as the cathode, a carbon felt SG-250S (manufactured by Osaka Tamashiro Co., Ltd.) coated with silicon on one side was prepared again, and the above anode was opposed through the side of the silicon-coated surface, immersed in the polypropylene pad, the anode and the cathode were connected with a conducting cable through an external resistance of 100 Ω, and the potential difference between the anode and the cathode was measured. The potential difference measurement was performed using the same apparatus and the same method as the potential difference measurement on the 0th day above. The numerical values of this measurement result are described as the numerical values on the 2nd day of Example 1 in Table 1 below.

[0091] <Weight measurement from the 4th day to the 10th day> Next, the anode on which the potential difference measurement on the 2nd day above was performed was taken out, and in the same manner as the treatment during the potential difference measurement on the 2nd day, it was immersed in the above aqueous solution containing 40 g / L of glucose, 8 g / L of ammonium sulfate, and 9 g / L of yeast extract and left at room temperature for 48 hours. After co-washing with the ammoniacal yeast extract aqueous solution, it was suction-filtered and immersed in a polypropylene pad containing 100 mL of the ammoniacal yeast extract aqueous solution. The step of connecting the above cathode with a conducting cable through an external resistance of 100 Ω and measuring the potential difference between the anode and the cathode was performed 4 times. The potential difference measurement was performed using the same apparatus and the same method as the potential difference measurement on the 0th day above. The numerical values of these measurement results are described as the numerical values from the 4th day to the 10th day of Example 1 in Table 1 below.

[0092] (Example 2) <Fabrication of anode> As the substrate, a polyester nonwoven fabric Celsheet CS-50 (manufactured by Maeda Kogyo Sen-i Co., Ltd.) was used in the same manner as in Example 1, and electroless nickel plating was performed in the same manner as in Example 1.

[0093] (Electrolytic plating treatment) Next, the non-woven fabric cell sheet subjected to the electroless nickel plating treatment described above was used as the negative electrode, and an aqueous solution containing 200 g / L of zinc sulfate and 30 g / L of ammonium sulfate was placed in an electrolytic cell with a 1 mm-thick zinc plate as the positive electrode. Electrolytic plating treatment was carried out under the conditions of pH 4.0, 40 °C, and a current density of 10 mA / cm 2 for 5 minutes. After that, the non-woven fabric cell sheet subjected to the electrolytic plating treatment was taken out, washed with water, and dried at a temperature of 80 °C in the air.

[0094] (Microorganism loading) Next, in the same manner as in Example 1, 10 mL of the microorganism agent BFL5800 (manufactured by Meito Kasei Co., Ltd.) containing the nitrifying bacterium Nitrosomonas was dissolved in 100 mL of warm water at 30 °C and placed in a polypropylene vat. The non-woven fabric cell sheet subjected to the electrolytic plating treatment described above was immersed in this solution at 30 °C for 3 hours to allow the microorganisms to adhere. In this way, the anode of the microbial fuel cell of Example 2 was fabricated.

[0095] (Fabrication and potential difference measurement of microbial fuel cell) Next, using the anode of Example 2 described above, the potential difference from day 0 to day 10 was measured in the same manner as in Example 1. The numerical values of these measurement results are described as the numerical values from day 0 to day 10 of Example 2 in Table 1 below.

[0096] [Table 1]

[0097] As shown in Table 1, the presence of a potential difference was confirmed continuously from day 0 to day 10 for both Example 1 and Example 2, and it was confirmed that either anode of Example 1 and Example 2 can be utilized as the anode of a microbial fuel cell.

[0098] Here, for both the anodes of Example 1 and Example 2, a polyester nonwoven fabric cell sheet CS-50 (manufactured by Maeda Kogyo Sen’i Co., Ltd.) is used for the base material, and the density of this polyester nonwoven fabric cell sheet CS-50 (manufactured by Maeda Kogyo Sen’i Co., Ltd.) is 0.20 g / cm 3 Since it is, it has a smaller density than commonly known metals (for example, the metal with the smallest density is lithium, and its density is 0.53 g / cm 3 ). That is, for both the anodes of Example 1 and Example 2, the weight can be reduced compared to the anode of a microbial fuel cell composed of metal.

[0099] Also, the anode of Example 1 has a nickel film on the base material, and the anode of Example 2 has a two-layer film composed of a zinc film as the upper layer (or outer layer) and a nickel film as the lower layer (or inner layer) on the base material. Since both the anodes of Example 1 and Example 2 have a metal film, it is possible to suppress the decrease in the electron transfer rate compared to the case where graphite is used for the anode.

[0100] Furthermore, as shown in Table 1, in Example 2 having a zinc film, the potential difference continuously increased from the 0th day to the 10th day, and no decrease in the potential difference was observed during this period. This increase in the potential difference can be presumed to be due to the growth of microorganisms supported on the anode of Example 2.

[0101] That is, in the anode of the microbial fuel cell of the present disclosure having the configuration shown in FIG. 3, by including a metal that promotes the growth of microorganisms 51 in the second metal film 42, it is also possible to suppress the decrease in the microorganisms 51 supported on the anode, and it becomes possible to maintain the generation of electrical energy by the microbial fuel cell provided with the anode for a long period of time.

Explanation of Reference Numerals

[0102] 1 Microbial fuel cell 11 Diaphragm 12 Negative electrode tank 13 Positive electrode tank 15 Negative electrode solution 16 Positive electrode solution 21, 21A, 21B Anode 22 Cathode 23 External circuit 31 Substrate 41 First metal film 42 Second metal film 51 Microorganism 61, 62 Laminate

Claims

1. A microbial fuel cell having a negative electrode chamber and a positive electrode chamber separated by a diaphragm, wherein the anode is composed of a plastic member having a first metal film, and the anode supports microorganisms.

2. The microbial fuel cell according to claim 1, further comprising a second metal film containing at least one of zinc, manganese, cobalt, or copper on the first metal film.

3. The microbial fuel cell according to claim 1 or 2, wherein the first metal film contains nickel.

4. The microbial fuel cell according to claim 1 or 2, wherein the plastic member is any one of a plastic nonwoven fabric, plastic mesh fibers, porous plastic, a plastic molded article having an uneven structure, or a plastic molded article having through holes.

5. The microbial fuel cell according to claim 1 or 2, having a negative electrode solution containing ammonia in the negative electrode chamber, wherein nitrifying bacteria are supported as the microorganisms.

6. The microbial fuel cell according to claim 1 or 2, having a negative electrode solution containing an organic substance in the negative electrode chamber, wherein microorganisms that oxidize the organic substance to generate electrons are supported as the microorganisms.

7. The microbial fuel cell according to claim 6, wherein the microorganisms that oxidize the organic substance to generate electrons are Shewanella bacteria or Geobacter bacteria.

8. The microbial fuel cell according to claim 5, wherein a microbial carrier supporting anammox bacteria is immersed in the negative electrode solution.

9. A method for manufacturing an anode of a microbial fuel cell, comprising: a first metal film forming step of forming a first metal film on a plastic member by electroless plating; and a microorganism supporting step of supporting microorganisms on the first metal film, wherein the microorganisms are nitrifying bacteria or microorganisms that oxidize an organic substance to generate electrons.

10. A method for manufacturing an anode of a microbial fuel cell, comprising: a first metal film forming step of forming a first metal film on a plastic member by electroless plating; a second metal film forming step of forming a second metal film containing at least one of zinc, manganese, cobalt, or copper on the first metal film by electrolytic plating; and a microorganism supporting step of supporting microorganisms on the second metal film, wherein the microorganisms are nitrifying bacteria or microorganisms that oxidize an organic substance to generate electrons.

11. ​ ​ ​ ​ ​ The manufacturing method of the anode of the microbial fuel cell according to claim 9 or claim 10, wherein the plastic member is any one of a plastic nonwoven fabric, plastic mesh fibers, porous plastic, a plastic molded product having an uneven structure, and a plastic molded product having a through hole.

12. The manufacturing method of the anode of the microbial fuel cell according to claim 9 or claim 10, wherein the first metal film contains nickel.

13. The manufacturing method of the anode of the microbial fuel cell according to claim 9 or claim 10, wherein the microorganism that oxidizes the organic substance to generate electrons is Shewanella bacteria or Geobacter bacteria.

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