JP2011065875A - Microorganism power generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-efficiency microorganism power generation device with a microorganism retention volume augmented and an adverse effect of oxygen alleviated and capable of restraining methane fermentation, in a microorganism fuel cell having a cylindrical structure. <P>SOLUTION: A plurality of cylindrical bodies 3 each made of a cylindrical cathode material 1 and an ion-transmitting non-conductive film 2 are arrayed in parallel with intervals in a casing 5. An anode material 4 each is filled between the cylindrical bodies 3. Microorganisms are carried by the anode materials 4. As water containing organic matters is passed to the anode materials 4 and gas containing oxygen such as air is circulated in inner holes 6 of the cathode materials 1, microorganism power generation is carried out. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a microbial power generation apparatus that extracts, as electrical energy, a reducing power obtained when an organic substance is oxidatively decomposed into microorganisms, and in particular, a cylindrical positive electrode material, an ionic non-conductive film surrounding the positive electrode material, The present invention relates to a microbial power generation device having a negative electrode material arranged around the outer periphery of an ionic non-conductive film.

  In microbial power generation that generates electricity by extracting electrical energy obtained when microorganisms assimilate organic matter, microorganisms, organic matter assimilated by microorganisms, and, if necessary, electron transfer media ( Electronic mediator) coexist. The electron mediator enters the microorganism, receives the electrons generated by the microorganisms oxidizing the organic matter, and passes them to the negative electrode. The negative electrode is electrically connected to the positive electrode via an external resistance (load), and the electrons transferred to the negative electrode move to the positive electrode via the external resistance (load) and are transferred to the electron acceptor in contact with the positive electrode. A current flows between the positive electrode and the negative electrode due to such movement of electrons.

  As one form of the microbial power generation device, a power generation device comprising a cylindrical body in which the outer periphery of a cylindrical cathode made of graphite (cathode) is surrounded by an electrolyte membrane and a cylindrical anode made of graphite is provided on the outer periphery of the electrolyte membrane. Is described in Patent Document 1 (paragraph 0060, FIG. 1).

  In Patent Document 1, paragraph 0061 and FIG. 1, it is described that a plurality of such cylindrical bodies are arranged in the reaction container with a space between each other. It is described that a substrate is supplied to a space between them and air is circulated through an inner hole of a cylindrical body.

JP 2005-317520 A

  As in the microbial power generation apparatus of paragraph 0064 of Patent Document 1, the microbial power generation apparatus in which the cylindrical bodies are arranged with a space (space) between them and the substrate is circulated between the cylindrical bodies. Since the space portion does not hold microorganisms, the amount of microorganisms held per anode unit volume is small. In addition, high activity cannot be expected because of the influence of oxygen permeating from the cathode.

  An object of the present invention is to provide a microbial power generation apparatus capable of increasing the amount of microorganisms retained in a microbial fuel cell having a cylindrical structure. Moreover, this invention aims at providing the highly efficient microbial power generation device which can reduce the influence of oxygen and can suppress methane fermentation in the one aspect | mode.

  According to another aspect of the present invention, there is provided a microbial power generation apparatus comprising: a cylindrical positive electrode material; and a cylindrical body comprising an ion-permeable non-conductive film surrounding the positive electrode material, wherein a plurality of cylindrical bodies are spaced apart from each other in the casing. It is arrange | positioned by this, The porous negative electrode material which can osmose | permeate an organic substance containing liquid is filled between these cylindrical bodies and between a cylindrical body and a casing, It is characterized by the above-mentioned.

  The microorganism power generation apparatus according to claim 2 is characterized in that, in claim 1, the distance between the outer peripheral surfaces of adjacent cylindrical bodies adjacent to each other is 5 to 100 mm.

  According to a third aspect of the present invention, there is provided the microbial power generation apparatus according to the first or second aspect, wherein an oxygen reduction catalyst is supported on an inner peripheral side of the ion permeable non-conductive film.

  The microbial power generation apparatus according to claim 4 is the casing according to any one of claims 1 to 3, wherein a plurality of cylindrical elements formed by enclosing an outer periphery of the cylindrical body with graphite felt are brought into close contact with each other, and the casing It is characterized by being housed inside.

  The microbial power generation device of the present invention includes a plurality of cylindrical bodies formed by surrounding a cylindrical positive electrode material with an ion-permeable non-conductive film, and the negative electrode material between the cylindrical bodies and between the cylindrical body and the casing. Is filled. Therefore, since the space between the cylindrical bodies is filled with the negative electrode material, the amount of microorganisms retained per unit volume in the microorganism power generation apparatus is large.

  In addition, when the distance between the adjacent adjacent cylindrical bodies is about 5 to 100 mm, the power generation efficiency is improved. In other words, oxygen diffuses from the positive electrode material 1 side to the negative electrode material 4 side through the ion permeable non-conductive film. Therefore, if this distance is excessively small, in the negative electrode material 4 near the ion permeable non-conductive film. Power generation efficiency is reduced. On the other hand, if this distance is excessively large, methane fermentation and sulfuric acid reduction are prioritized, and the electron donor (organic substance) is wasted.

(A) A figure is a section perspective view of a microbial power generation device concerning an embodiment, and (b) figure is a BB line sectional view of (a) figure. It is the II-II sectional view taken on the line of FIG. It is sectional drawing which shows the manufacturing method of a cylindrical body. It is sectional drawing which shows the state with which the cylindrical element was stuck and it filled with the case. It is a longitudinal cross-sectional view of the microbial power generation apparatus which concerns on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. As shown in FIGS. 1 and 2, a plurality of cylindrical bodies 3 are arranged in a cylindrical casing 5, and a negative electrode material is provided between the cylindrical bodies 3 and between the cylindrical body 3 and the casing 5. 4 is filled. The cylindrical body 3 is formed by surrounding the outer periphery of the cylindrical positive electrode material 1 with an ion-permeable non-conductive film (cation-permeable film in this embodiment) 2 and is arranged in parallel with a space between each other. Has been. An oxygen reduction catalyst is supported on the inner peripheral surface of the ion permeable non-conductive film 2.

The negative electrode material 4 carries microorganisms. The organic material-containing water is passed through the negative electrode material 4, and oxygen-containing gas such as air is circulated in the inner hole 6 of the positive electrode material 1, whereby microbial power generation is performed. That is, in the negative electrode material 4,
(Organic) + H ₂ O → CO ₂ + H ⁺ + e ⁻
The reaction proceeds. The electrons e ⁻ flow to the positive electrode material 1 through the terminal 30, the external resistor 31, and the terminal 32.

Proton H ⁺ generated by the above reaction moves to the positive electrode material 1 through the ion-permeable non-conductive membrane 2. In the positive electrode material 1,
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O
The reaction proceeds.

  Next, an example of a method for manufacturing the microbial power generation apparatus will be described with reference to FIGS. 3 and 4.

  An ion-permeable non-conductive film 2 is wound around the outer periphery of a cylindrical positive electrode material 1 made of graphite paper, graphite felt or the like to form a cylindrical body 3. The cylindrical body 3 is sandwiched between a pair of sheet-like graphite felts 7 and 7 as shown in FIG. 3 (a), and the graphite felts 7 and 7 are half-circulated around the cylindrical body 3 as shown in FIG. 3 (b). The cylindrical body 3 is surrounded by graphite felts 7 and 7. Both ends of the graphite felts 7 and 7 are overlapped and stitched with a synthetic resin thread 8 such as polyester to form a cylindrical element 9. The required number of cylindrical elements 9 are aligned, the outer periphery is tied up with a string-like body to bring the cylindrical elements 9 into close contact with each other, and then inserted into the casing 5 as shown in FIG. Thereby, the graphite felt 7 of each cylindrical element 9 adheres closely without gap, and the negative electrode material 4 is comprised. In FIG. 4, seven cylindrical elements 9 are aligned, but this number is arbitrary. Usually, it is preferable to align 7 to 1800 cylindrical elements 9, particularly 19 to 169.

  An example of a configuration for passing organic substance-containing water through the negative electrode material 4 and allowing air or the like to flow through the inner hole 6 will be described with reference to FIG. In addition, the casing 5 is arrange | positioned so that the axial center direction of each cylindrical body 3 may become an up-down direction.

  A top plate 11 having an air inlet 12 is attached to the upper end of the casing 5. A partition plate 13 is disposed below the top plate 11, and an air inflow chamber 14 is formed between the top plate 11 and the partition plate 13. An opening 13 a is provided in the partition plate 13, and the upper end of the positive electrode material 1 with the ion permeable non-conductive film 2 of each cylindrical body 3 is inserted into the opening 13 a and fixed by an adhesive or the like.

  A bottom plate 16 having an air outlet 17 is attached to the lower end of the casing 5. A partition plate 18 is disposed above the bottom plate 16, and an air outflow chamber 19 is formed between the bottom plate 16 and the partition plate 18. The partition plate 18 is provided with an opening 18a vertically below the opening 13a, and the lower end of the positive electrode material 1 with the ion-permeable non-conductive film 2 of each cylindrical body 3 is inserted into the opening 18a and bonded. It is fixed with an agent.

  A space 23 is provided between the upper end surface of the negative electrode material 4 and the partition plate 13, and a space 22 is provided between the lower end surface of the negative electrode material 4 and the partition plate 18. The organic substance-containing water is introduced into the space 22 from the liquid inlet 21 provided at the lower part of the casing 5, flows upward so as to penetrate into the negative electrode material 4, and flows through the space 23 at the upper part of the casing 5. It flows out from the outlet 24, and preferably a part thereof is circulated to the liquid inlet 21. The organic substance-containing water may be passed in a downward flow.

  Air flows in the order of the inflow port 12, the air inflow chamber 14, each inner hole 6, the air outflow chamber 19, and the outflow port 17. In addition, about the part exposed to the spaces 22 and 23 among the outer peripheral surfaces of the cylindrical body 3, it is made non-breathable by winding an airtight film (not shown).

  Next, in addition to microorganisms and negative electrode solutions of this microbial power generation apparatus, suitable materials for ion-permeable non-conductive films, negative electrode materials and positive electrode materials will be described.

  Examples of the microorganisms retained in the negative electrode material 4 include, for example, Saccharomyces, Hansenula, Candida, Micrococcus, Staphylococcus, Streptococcus, Leuconostoa, Lactobacillus, Corynebacterium, Arthrobacter, Bacillus, Clostridium, Neisseria, Escherichia, Enterobacter, chromobacterium, Actobacter, Sera Acetobacter, Moraxella, Nitrosomonas, Nitorobacter, Thiobacillus, Gluconobacter, Pseudomonas, Xanthomonas, Vibrio, Comamonas and Proteus (Proteus vulgaris) belonging to each genus, filamentous fungi, yeast, and the like can be mentioned. Sludge containing such microorganisms, for example, activated sludge obtained from biological treatment tanks for treating water containing organic matter such as sewage, sludge from the first sedimentation basin of sewage, anaerobic digested sludge, etc. are supplied to the negative electrode material as seeding The microorganism can be held on the negative electrode material. In order to increase the power generation efficiency, the amount of microorganisms retained in the negative electrode material is preferably high, and for example, the microorganism concentration is preferably 1 to 50 g / L.

  The liquid passed through the negative electrode material 4 contains an organic substance. The organic substance is not particularly limited as long as it can be decomposed by microorganisms. For example, water-soluble organic substances, organic fine particles dispersed in water, and the like are used. This liquid may be organic waste water such as sewage and food factory waste water. The organic substance concentration in the liquid is preferably as high as about 100 to 10,000 mg / L in order to increase the power generation efficiency.

  In this solution, an electron mediator may be contained in order to make it easier to extract electrons from microorganisms or cells. Examples of the electron mediator include compounds having a thionin skeleton such as thionine, dimethyldisulfonated thionine, new methylene blue and toluidine blue-O, and 2-hydroxy-1,4-naphthoquinone such as 2-hydroxy-1,4-naphthoquinone. Examples include compounds having a skeleton, brilliant cresyl blue, garocyanine, resorufin, alizarin brilliant blue, phenothiazinone, phenazine esosulphate, safranin-O, dichlorophenolindophenol, ferrocene, benzoquinone, phthalocyanine, or benzyl viologen and their derivatives. be able to.

  Furthermore, if materials that increase the power generation function of microorganisms, such as antioxidants such as vitamin C, or materials that increase the function of only specific electron transfer systems or substance transfer systems in microorganisms, are dissolved, power can be more efficiently generated. Is preferable.

  The liquid passed through the negative electrode material 4 may contain a phosphate buffer, if necessary.

  The oxygen-containing gas flowing through the inner hole 6 of the positive electrode material 1 is preferably air, but may be pure oxygen, oxygen-enriched air, or the like.

  As the ion permeable non-conductive membrane, a non-conductive ion permeable cation permeable membrane or anion permeable membrane such as an anion permeable membrane or a reverse osmosis membrane can be used. As the ion exchange membrane, a cation exchange membrane having a high proton selectivity or an anion exchange membrane can be suitably used. For example, as the cation exchange membrane, Nafion (registered trademark) manufactured by DuPont Co., Ltd. or a cation exchange membrane manufactured by Astom Co., Ltd. A CMB film or the like can be used. As an anion exchange membrane, an anion exchange membrane made by Astom, an anion electrolyte membrane made by Tokuyama, etc. are suitable. The ion-permeable non-conductive film is preferably thin and strong. Usually, the film thickness is preferably about 30 to 300 μm, particularly about 30 to 200 μm.

  It is preferable that an oxygen reduction catalyst is supported on the positive electrode material 1 side of the ion-permeable nonconductive film 2.

As the oxygen reduction catalyst, in addition to noble metals such as platinum, metal oxides such as manganese dioxide are preferred because they are inexpensive and have good catalytic activity, and the supported amount is 0.01 to 2.0 mg / it is preferable that the cm ^2.

  The negative electrode material is preferably a porous body having a large surface area and a large number of voids and water permeability so that a large number of microorganisms can be retained. Specifically, a conductive material sheet having at least a rough surface or a porous conductor in which the conductive material is formed into a felt-like or other porous sheet is preferable, and specifically, graphite felt is used.

  It is good also as a negative electrode material by laminating | stacking a some sheet-like conductor. In this case, the same kind of conductor sheets may be laminated, or different kinds of conductor sheets (for example, a graphite sheet having a rough surface and a graphite felt) may be laminated.

  When such a porous negative electrode material is brought into contact with the ion-permeable non-conductive film directly or via a microorganism layer, electrons generated by the microbial reaction are transferred to the negative electrode material without using an electron mediator. Thus, an electronic mediator can be dispensed with.

  The distance between the nearest cylindrical bodies 3, that is, the thickness t (FIG. 1 (b)) of the negative electrode material 4 existing between the nearest cylindrical bodies 3, 3 is about 5 to 100 mm, particularly about 10 to 40 mm. preferable. As described above, when the distance is excessively small, the power generation efficiency in the negative electrode material 4 in the vicinity of the ion-permeable non-conductive film is lowered. On the other hand, if this distance is excessively large, methane fermentation and sulfuric acid reduction are prioritized and the electron donor is wasted.

  As the positive electrode material, a material having high conductivity, high corrosion resistance and further having mechanical strength as a conductive base material is preferable, and graphite paper, graphite felt, graphite cloth, stainless steel mesh, titanium mesh, etc. may be used. Of these, graphite base materials such as graphite paper, graphite felt, and graphite cloth are particularly preferable from the viewpoint of durability and ease of processing. These graphite base materials may be those made hydrophobic by a fluororesin such as polytetrafluoroethylene (PTFE).

  If the thickness of the cylindrical positive electrode material, that is, the difference between the radius of the outer diameter and the radius of the inner diameter, is too thick, oxygen permeation becomes poor, and if it is too thin, the required properties such as strength required for the substrate cannot be satisfied. Therefore, it is preferably about 5 to 100 mm, particularly about 10 to 40 mm. The hole diameter (diameter) of the inner hole 6 of the positive electrode material is preferably about 1 to 10 mm, particularly about 2 to 5 mm.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Creation of cylindrical body 3]
A cation exchange membrane (manufactured by DuPont, trade name (registered trademark) “Nafion 112”) was used as the ion-permeable non-conductive membrane. On this cation exchange membrane, a solution in which an oxygen reduction catalyst (Pt + Co made by Tanaka Kikinzoku, supported by KetjenBlackB) is dispersed in a 5% Nafion solution (manufactured by DuPont) is applied to 0.5 mg-Pt / cm ² to form ions. A permeable non-conductive film was obtained.

  Separately, a carbon cloth made of graphite (New Nippon Technocarbon Co., Ltd. GF-20-P-21E) as a positive electrode material was prepared by water repellent treatment with PTFE (polytetrafluoroethylene). The water repellent treatment was performed by attaching a solution (concentration 20 wt%) of PTFE in xylene to carbon cloth, drying, and baking at 360 ° C. for 10 minutes. The adhesion amount of PTFE is 50 wt%. This carbon cloth was wound around the outer periphery of a mandrel having a diameter of 5 mm. The ion-permeable non-conductive film was wound only once around the outer periphery of the carbon cloth. The winding start and winding end portions of the ion-permeable non-conductive film were bonded with an instantaneous adhesive. Next, the mandrel was pulled out to obtain a cylindrical body 3.

  As shown in FIG. 3, the cylindrical body 3 was sandwiched and surrounded by two graphite felts having a thickness of 5 mm, and the ends of the graphite felt were stitched together with a nylon thread 8 to form a cylindrical element 9. The diameter of the cylindrical element 9 is about 15 mm.

  At both ends of the cylindrical element 9, the cylindrical positive electrode material 1 with the ion permeable non-conductive film 2 protrudes from the end face of the negative electrode material 4 by a length of 5 mm. A silicon sealant was embedded around the protruding portion, and a film was wound to prevent air from flowing into the negative electrode to make it non-breathable.

  The seven cylindrical elements 9 produced in this way were aligned in parallel, and a nylon string was wound around the outer periphery to form a substantially cylindrical shape. This was inserted into a casing 9 made of vinyl chloride having an inner diameter of 50 mm.

  As shown in FIG. 5, a partition plate, a top plate, and a bottom plate were attached to obtain a microbial power generation apparatus. In addition, a stainless steel wire was inserted as a terminal into the positive electrode material 1 and the negative electrode material 4 and connected as shown in FIG. 2 through a resistance of 2Ω.

  A negative electrode solution containing 1000 mg / L of acetic acid, phosphoric acid and ammonia was passed through the negative electrode material 4 while maintaining the pH at 7.5. This negative electrode solution was previously heated to 35 ° C. in a separate water tank, and the liquid heated in this water tank was passed through the negative electrode material 4 at 10 mL / min, and treated water was circulated at 250 mL / min. Thereby, the temperature of the negative electrode chamber was kept at 35 ° C. Prior to passing the negative electrode solution, the effluent of another microbial power generation device was passed as an inoculum.

  A normal temperature air was passed through the inner hole 6 of the positive electrode material 1 at a flow rate of 2 L / min.

As a result, the power generation amount became almost constant 3 days after the start of the flow of the negative electrode solution, and the power generation amount per 1 m ^{3 of} the negative electrode was 1,200 W.

DESCRIPTION OF SYMBOLS 1 Positive electrode material 2 Ion permeable non-conductive film 3 Cylindrical body 4 Negative electrode material 5 Casing 6 Inner hole 7 Carbon felt 8 Yarn 9 Cylindrical element

Claims (4)

A cylindrical body comprising a cylindrical positive electrode material and an ion permeable non-conductive film surrounding the positive electrode material is disposed in the casing with a plurality of gaps therebetween,
A microbial power generation apparatus, wherein a porous negative electrode material into which an organic substance-containing liquid can permeate is filled between the cylindrical bodies and between the cylindrical body and the casing.   In Claim 1, the distance of the outer peripheral surfaces of the adjacent cylindrical body which adjoins is 5-100 mm, The microorganisms power generator characterized by the above-mentioned.   The microbial power generation apparatus according to claim 1 or 2, wherein an oxygen reduction catalyst is supported on an inner peripheral side of the ion permeable non-conductive film.   4. The method according to claim 1, wherein a plurality of cylindrical elements formed by enclosing the outer periphery of the cylindrical body with graphite felt are brought into close contact with each other and accommodated in the casing. Microbial power generator.

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