JP2020119763A - Electrode unit and liquid processing system - Google Patents

Abstract

To provide an electrode unit capable of easily being taken out from an electrolyte and a liquid processing system using the electrode unit.SOLUTION: An electrode unit 10 includes multiple hollow electrodes 20 enclosing at least a part of a hollow part 21 where oxygen exists, each of which has a positive electrode 41 provided so as to come into contact with oxygen existing in the hollow part 21. Positive electrodes 41 of the hollow electrodes 20 are electrically connected to each other. The electrode unit 10 is configured to be deformed. A liquid processing system 50 includes the electrode unit 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode unit and a liquid processing system.

In recent years, microbial fuel cells that generate electricity using biomass have been attracting attention as sustainable energy. The microbial fuel cell is a wastewater treatment device that converts chemical energy of organic substances contained in domestic wastewater and industrial wastewater into electric energy and oxidatively decomposes and treats the organic substances. Further, the microbial fuel cell has the characteristics that the generation of sludge is small and the energy consumption is small.

The microbial fuel cell has a negative electrode supporting microorganisms and a positive electrode in contact with a gas phase containing oxygen and an electrolytic solution (wastewater). Then, while supplying an electrolytic solution containing an organic substance and the like to the negative electrode, a gas containing oxygen is supplied to the positive electrode. The negative electrode and the positive electrode are connected to each other via a load circuit to form a closed circuit. At the negative electrode, hydrogen ions and electrons are generated from the electrolytic solution by the catalytic action of microorganisms. Then, the generated hydrogen ions move to the positive electrode via the electrolytic solution, and the electrons move to the positive electrode via the load circuit. Hydrogen ions and electrons transferred from the negative electrode combine with oxygen in the positive electrode and are consumed as water. At that time, the microbial fuel cell recovers the electric energy flowing in the closed circuit.

By the way, when the operating time of the microbial fuel cell becomes long, the adhered substances attached to the positive electrode and the negative electrode tend to increase due to the growth of biofilm and the accumulation of scale. If such deposits increase on the surfaces of the positive electrode and the negative electrode, the chemical reaction on the positive electrode and the negative electrode may be hindered, and the electrical energy recovery efficiency and the quality of treated water may deteriorate.

Here, Patent Document 1 describes a microbial fuel cell in which a deteriorated diaphragm and/or a positive electrode can be replaced without reducing energy recovery efficiency. The microbial fuel cell described in Patent Document 1 is equipped with a negative electrode that is immersed in an organic substrate to carry anaerobic microorganisms. In addition, the microbial fuel cell is an organic substrate that is enclosed with an electrolytic solution in a closed hollow cassette having an outer shell and an inlet/outlet hole, at least a part of which is formed of an ion-permeable diaphragm, or is bound to the inside of the diaphragm of the cassette. It has a positive electrode that plugs into it. Then, the microbial fuel cell takes out electricity through a circuit that electrically connects the negative electrode and the positive electrode while supplying oxygen into the cassette through the inlet/outlet hole.

Japanese Patent No. 5164511

According to the microbial fuel cell described in Patent Document 1, the deteriorated diaphragm and/or the positive electrode can be replaced without reducing the energy recovery efficiency. However, in the microbial fuel cell, an electrode having a size of several meters may be used in order to improve the purification efficiency of the electrolytic solution. However, when such a large electrode is used, a space larger than the size of the electrode is required on the liquid surface of the electrolytic solution in order to pull up the electrode from the electrolytic solution. When installing a large microbial fuel cell in a building having a roof, the cost for securing such a space becomes a burden. Further, in order to pull up the large electrode from the electrolytic solution as described above, it is necessary to prepare a device larger than the electrode.

The present invention has been made in view of such problems of the conventional art. An object of the present invention is to provide an electrode unit that can be easily taken out from an electrolytic solution and a liquid processing system using the electrode unit.

In order to solve the above problems, the electrode unit according to the first aspect of the present invention is provided so as to surround at least a part of the hollow portion in which oxygen exists, and to be in contact with oxygen existing in the hollow portion. And a plurality of hollow electrodes having a positive electrode. The positive electrodes of each hollow electrode are electrically connected to each other. The electrode unit is configured to deform.

In order to solve the above problems, a liquid treatment system according to a second aspect of the present invention includes an electrode unit and an electrolytic solution tank that stores an electrolytic solution containing an organic substance. Each hollow electrode further comprises a negative electrode carrying microorganisms and electrically connected to the positive electrode. Then, each hollow electrode is in contact with the electrolytic solution.

According to the present disclosure, it is possible to provide an electrode unit that can be easily taken out from an electrolytic solution and a liquid processing system using the electrode unit.

It is a perspective view which shows roughly an example of the electrode unit which concerns on 1st embodiment. It is sectional drawing which followed the AA line in FIG. It is sectional drawing which followed the BB line in FIG. It is a perspective view which shows roughly an example of the electrode unit which concerns on 2nd embodiment. It is a perspective view which shows roughly an example of the electrode unit which concerns on 3rd embodiment. It is a perspective view which shows roughly an example of the liquid treatment system which concerns on 1st embodiment. FIG. 9 is a cross-sectional view taken along the line C-C in FIG. 8. It is a top view which shows schematically an example of the liquid treatment system which concerns on 2nd embodiment. It is a top view which shows roughly the mode that an electrode unit is folded in an electrolyte solution tank. It is sectional drawing which shows schematically a mode that the folded electrode unit is taken out from an electrolyte solution tank.

Hereinafter, the electrode unit and the liquid processing system according to this embodiment will be described in detail. It should be noted that the dimensional ratios in the drawings are exaggerated for convenience of description, and may differ from the actual ratios.

<Electrode unit>
The electrode unit 10 will be described in detail using the electrode units 10A to 10C according to the first embodiment to the third embodiment.

[First embodiment]
First, the electrode unit 10A according to the first embodiment will be described with reference to FIGS. As shown in FIG. 1, the electrode unit 10A according to this embodiment includes a plurality of hollow electrodes 20.

Among the plurality of hollow electrodes 20, adjacent hollow electrodes 20 are connected to each other by a connecting portion 30, and the hollow electrodes 20 are connected in a line. The connecting portion 30 connects one end of one hollow electrode 20 and one end of the other hollow electrode 20 among the adjacent hollow electrodes 20, and is configured to bend. Then, as will be described later, the electrode unit 10A is configured to be deformed.

The connecting portion 30 may be configured to be deformable, and may have, for example, a bending structure such as a hinge, or may be a sheet or the like made of a flexible material. When the connecting portion 30 has a bending structure such as a hinge, the connecting portion 30 may be made of a material such as metal, resin and ceramics. When the connection part 30 is a sheet made of a flexible material, the material is at least one resin selected from the group consisting of silicone, vinyl chloride, polyolefin and elastomer, and a film-shaped metal. And the like. Further, the communication part 35 described later may have a role as the connection part 30 that connects the hollow electrodes 20 adjacent to each other.

FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, showing a cross section in the direction Y. As shown in FIG. 2, each hollow electrode 20 has a hollow portion 21, a side wall portion 22, and a pair of electrode bonded bodies 40 that are arranged to face each other with the hollow portion 21 interposed therebetween. The peripheral edge of the side wall 22 connects the peripheral edge of the one electrode assembly 40 and the peripheral edge of the other electrode assembly 40. The hollow portion 21 is surrounded by the pair of electrode joint bodies 40 and the side wall portion 22 which are arranged to face each other. In addition, in the present embodiment, an example in which the hollow electrode 20 includes a pair of electrode bonded bodies 40 has been described, but each hollow electrode 20 does not need to include a plurality of electrode bonded bodies 40, and at least one electrode It suffices if the bonded body 40 is provided. Therefore, of the pair of electrode bonded bodies 40, one electrode bonded body 40 may be formed of a simple plate-shaped member.

The hollow portion 21 of each hollow electrode 20 contains oxygen. The hollow portions 21 of each hollow electrode 20 are communicated with each other through the communication portion 35, and oxygen contained in each hollow portion 21 is configured to be able to pass back and forth. The communication part 35 is a pipe having a cavity inside, and an opening part of the side wall part 22 of one hollow electrode 20 and an opening part of the side wall part 22 of the other hollow electrode 20 among the adjacent hollow electrodes 20. Are connected. The communication part 35 is connected to substantially the center of the side wall part 22 in the thickness direction X of the electrode assembly 40, and is configured to bend.

The material forming the communication portion 35 is preferably formed of a flexible material so as to bend between the adjacent hollow electrodes 20. The material forming the communication portion 35 is not particularly limited, but may be, for example, at least one resin selected from the group consisting of silicone, vinyl chloride, polyolefin and elastomer. Since the positive electrodes 41 of the hollow electrodes 20 are electrically connected to each other, the communication part 35 itself may be a conductive material. In this case, the communication part 35 may be made of a flexible metal.

Each hollow portion 21 may have a gas phase containing oxygen. The air supplied to the hollow portion 21 may be supplied via the communication portion 35, or may be directly supplied without passing through the communication portion 35. When air is supplied to the hollow portion 21 via the communication portion 35, the plurality of hollow electrodes 20 may be immersed in an electrolytic solution to open one end of the communication portion 35 to the outside air, or to the communication portion 35 from the outside by a pump. Air may be forcibly supplied. When the electrode unit 10A includes the communication portion 35, air can be supplied to the hollow portion 21 through the communication portion 35, and thus even if all the hollow electrodes 20 are arranged below the liquid surface of the electrolytic solution. Good.

When air is directly supplied to the hollow portion 21 without passing through the communication portion 35, for example, by removing the side wall portion 22 on the front side of FIG. Each hollow portion 21 may be configured by opening one end of the above to the outside air. When such an electrode unit 10A is immersed in an electrolytic solution, the electrode unit 10A is arranged so that one end of each hollow electrode 20 on the open side is on the liquid surface of the electrolytic solution, and the open side of each hollow electrode 20 is arranged. It may be dipped in the electrolytic solution so that the closed side opposite to is facing the bottom surface of the electrolytic solution tank. In this case, since the hollow portion 21 of each hollow electrode 20 is open to the outside air, the electrode unit 10A may not have the communication portion 35.

The hollow portion 21 may be formed only of a space containing oxygen, but in order to prevent the hollow electrode 20 from being crushed by the water pressure of the electrolytic solution or the like, a buffer member may be provided in the hollow portion 21. This is because even if the electrode unit 10A is immersed in the electrolytic solution and a high water pressure is applied to the surface of each hollow electrode 20, it is possible to prevent the hollow electrode 20 from being crushed by the pressure from the inside by the buffer member.

The material of the member constituting the cushioning member is not particularly limited, but for example, at least one selected from the group consisting of resin, metal, glass and carbon material can be used. As the resin, at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, polyvinyl chloride and polycarbonate can be used. At least one of stainless steel and aluminum can be used as the metal.

The shape of the member forming the buffer member is not particularly limited, but it is preferable that the buffer member is formed of a flat plate having a plurality of pores so that oxygen can be efficiently supplied to the positive electrode 41. Further, the buffer member may be composed of a mesh structure having a plurality of pores. The plurality of pores may be formed at a constant pitch. The cushioning member may have, for example, a structure in which a part of a flat plate largely penetrates.

As shown in FIG. 1, each hollow electrode 20 is in the shape of a rectangular prism such as a trapezoidal prism. As shown in FIG. 2, the upper bottom of the trapezoid on the short side and the lower bottom of the long side are constituted by the electrode assembly 40, and each hollow electrode 20 is connected in a cross-sectional view in the direction Y. It extends in the direction Z. In each hollow electrode 20, the length in the direction Y is longer than the length in the directions X and Z, and the length in the direction Z is longer than the length in the direction X. 1 and 2, the direction X is a direction perpendicular to the connection direction Z and is the thickness direction of each electrode assembly 40. The direction Y is a direction perpendicular to each of the directions X and Z, and is the height direction of the trapezoidal pillar when the trapezoid is the bottom surface. Further, the size and shape of each hollow electrode 20 can be arbitrarily changed depending on the size of the liquid treatment system, desired purification performance, and the like.

As shown in FIGS. 1 and 2, the upper bottom electrode assemblies 40 and the lower bottom electrode assemblies 40 are aligned in a straight line when the electrode unit 10A is not bent. That is, of the pair of electrode assemblies 40 in each hollow electrode 20, the electrode assembly 40 having the smaller area on the upper bottom side is arranged in the same direction side of the electrode unit 10A and the one having the larger area on the lower bottom side. The electrode bonded body 40 is arranged on the other side of the electrode unit 10A. Then, in the state where the electrode unit 10A is not bent, in the adjacent hollow electrodes 20, the distance between the electrode assemblies 40 having a smaller area is larger than the distance between the electrode assemblies 40 having a larger area. ing.

The connecting portion 30 connects the corners of the hollow electrodes 20 adjacent to each other, and is configured to bend as described above. Since each hollow electrode 20 has an acute angle, the adjacent hollow electrodes 20 are easily bent at a predetermined angle from the acute angle side of the hollow electrodes 20 toward the obtuse angle side. The predetermined angle can be appropriately determined depending on the acute angle and the obtuse angle of the hollow electrode 20.

Therefore, as shown in FIG. 1, the electrode unit 10A is configured to be deformed. Specifically, the electrode unit 10A is configured to bend between the adjacent hollow electrodes 20 among the plurality of hollow electrodes 20. More specifically, the electrode unit 10A is configured to be bent in the same direction between adjacent hollow electrodes 20 among the plurality of hollow electrodes 20, and to be wound into a roll shape.

Therefore, since the electrode unit 10A can be pulled up from the electrolytic solution while being wound into a roll, a space larger than the size of the electrode unit 10A is not required on the liquid surface of the electrolytic solution. Further, since the electrode unit 10A can be pulled up from the electrolytic solution while being wound into a roll, it is less necessary to prepare a large device for pulling up the electrode unit 10A from the electrolytic solution even when the electrode unit 10A is made large. Therefore, the electrode unit 10A can be easily taken out from the electrolytic solution.

In the present embodiment, an example in which the hollow electrode 20 is a trapezoidal column has been described, but for example, if the connecting portion 30 and the communication portion 35 are long and the adjacent hollow electrodes 20 are sufficiently open, the electrode unit 10A. Is configured to be rolled up. Therefore, the shape of the hollow electrode 20 is not particularly limited, and may be a quadrangular prism such as a substantially rectangular parallelepiped or an ellipsoid.

Further, the number of hollow electrodes 20 in the electrode unit 10A can be arbitrarily changed depending on the size of the liquid processing system in which the electrode unit 10A is used, the desired purification performance, and the like. Therefore, the number of hollow electrodes 20 in the electrode unit 10A may be two or more, three or more, or five or more. The number of hollow electrodes 20 in the electrode unit 10A is not particularly limited, but may be 100 or less, 50 or less, or 10 or less.

Next, the electrode assembly 40 will be described. FIG. 3 is a sectional view taken along the line BB in FIG. As shown in FIG. 3, the electrode assembly 40 includes a positive electrode 41, an ion transfer layer 42, and a negative electrode 43. The positive electrode 41 is arranged in contact with one surface of the ion transfer layer 42, and the negative electrode 43 is arranged in contact with the other surface of the ion transfer layer 42.

(Positive electrode)
As shown in FIG. 3, the hollow electrode 20 has a positive electrode 41 surrounding at least a part of the hollow portion 21 in which oxygen exists and provided so as to come into contact with oxygen existing in the hollow portion 21. There is. The positive electrode 41 is composed of a gas diffusion electrode having a water repellent layer 44 and a gas diffusion layer 45 which is stacked so as to contact the water repellent layer 44. Then, the gas diffusion layer 45 of the positive electrode 41 is in contact with the ion transfer layer 42, and the water repellent layer 44 is exposed on the hollow portion 21 side. By using such a thin plate-shaped gas diffusion electrode, it becomes possible to easily supply oxygen in the hollow portion 21 to the catalyst in the positive electrode 41.

(Water repellent layer)
The water repellent layer 44 of the positive electrode 41 is a layer having both water repellency and oxygen permeability. The water-repellent layer 44 is configured to allow the movement of oxygen from the hollow portion 21 toward the liquid phase while favorably separating the gas phase and the liquid phase in the electrochemical system. That is, the water-repellent layer 44 allows oxygen in the hollow portion 21 to permeate and move to the gas diffusion layer 45, while suppressing movement of the electrolytic solution to the hollow portion 21 side. The term “separation” as used herein means to physically cut off. Further, the liquid phase mentioned here is a liquid phase such as an electrolytic solution.

The water-repellent layer 44 is in contact with the hollow portion 21 in which oxygen exists and diffuses oxygen in the hollow portion 21. The water repellent layer 44 supplies oxygen to the gas diffusion layer 45 substantially uniformly. Therefore, the water repellent layer 44 is preferably a porous body so that the oxygen can be diffused. Since the water-repellent layer 44 has water repellency, it is possible to prevent the pores of the porous body from being clogged with dew condensation or the like, and reducing the oxygen diffusivity. Further, since the electrolytic solution is unlikely to soak into the water-repellent layer 44, oxygen can be efficiently circulated from the surface of the water-repellent layer 44 that contacts the hollow portion 21 to the surface that faces the gas diffusion layer 45. Become.

The water repellent layer 44 is preferably formed in a sheet shape. The material forming the water-repellent layer 44 is not particularly limited as long as it is water-repellent and can diffuse oxygen in the hollow portion 21. Examples of the material forming the water repellent layer 44 include polyethylene, polypropylene, polybutadiene, nylon, polytetrafluoroethylene (PTFE), ethyl cellulose, poly-4-methylpentene-1, butyl rubber and polydimethylsiloxane (PDMS). At least one selected from the group can be used. Since these materials easily form a porous body and have high water repellency, it is possible to suppress clogging of pores and improve gas diffusivity. The water-repellent layer 44 preferably has a plurality of through holes penetrating in the stacking direction X of the water-repellent layer 44 and the gas diffusion layer 45.

As the water repellent layer 44, for example, a waterproof and moisture permeable sheet can be used. As the waterproof and moisture-permeable sheet, for example, Serpore (registered trademark) manufactured by Sekisui Chemical Co., Ltd. and Breathlon (registered trademark) manufactured by Nitoms Co., Ltd. can be used.

The water-repellent layer 44 may be subjected to water-repellent treatment using a water-repellent agent, if necessary, in order to enhance water repellency. Specifically, water repellency may be improved by attaching a water repellent agent such as polytetrafluoroethylene to the porous body forming the water repellent layer 44.

<Gas diffusion layer>
The gas diffusion layer 45 in the positive electrode 41 preferably includes a porous conductive material and a catalyst carried by the conductive material. The gas diffusion layer 45 may be made of a porous and electrically conductive catalyst. Since the positive electrode 41 includes such a gas diffusion layer 45, electrons generated by a local cell reaction described later can be conducted between the catalyst and the external circuit. That is, as will be described later, the gas diffusion layer 45 carries a catalyst, and the catalyst is an oxygen reduction catalyst. Then, the electrons move from the external circuit to the catalyst through the gas diffusion layer 45, whereby the oxygen reduction reaction by oxygen, hydrogen ions and electrons can be advanced by the catalyst.

In the positive electrode 41, in order to ensure stable performance, it is preferable that oxygen permeates the water repellent layer 44 and the gas diffusion layer 45 efficiently and is supplied to the catalyst. Therefore, it is preferable that the gas diffusion layer 45 is a porous body having a large number of pores through which oxygen permeates from the surface facing the water repellent layer 44 to the surface on the opposite side. Further, the shape of the gas diffusion layer 45 is particularly preferably a three-dimensional mesh shape. With such a mesh shape, it is possible to impart high oxygen permeability and conductivity to the gas diffusion layer 45.

In the positive electrode 41, in order to efficiently supply oxygen to the gas diffusion layer 45, the water repellent layer 44 is preferably bonded to the gas diffusion layer 45 via an adhesive. Thereby, the diffused oxygen is directly supplied to the gas diffusion layer 45, and the oxygen reduction reaction can be efficiently performed. From the viewpoint of ensuring the adhesiveness between the water repellent layer 44 and the gas diffusion layer 45, the adhesive is preferably provided on at least part of the water repellent layer 44 and the gas diffusion layer 45. However, from the viewpoint of enhancing the adhesiveness between the water repellent layer 44 and the gas diffusion layer 45 and stably supplying oxygen to the gas diffusion layer 45 for a long period of time, the adhesive is the water repellent layer 44 and the gas diffusion layer. It is more preferable that it is provided on the entire surface between 45 and 45.

The adhesive preferably has oxygen permeability and contains at least one selected from the group consisting of polymethylmethacrylate, methacrylic acid-styrene copolymer, styrene-butadiene rubber, butyl rubber, nitrile rubber, chloroprene rubber and silicone. A resin can be used.

Here, the gas diffusion layer 45 of the positive electrode 41 in the present embodiment will be described in more detail. As described above, the gas diffusion layer 45 can be configured to include a porous conductive material and a catalyst carried by the conductive material.

The conductive material in the gas diffusion layer 45 can be composed of, for example, one or more materials selected from the group consisting of carbon-based substances, conductive polymers, semiconductors and metals. Here, the carbon-based substance means a substance containing carbon as a constituent component. Examples of carbon-based materials include carbon powders such as graphite, activated carbon, carbon black, Vulcan (registered trademark) XC-72R, acetylene black, furnace black, and denka black, graphite felt, carbon wool, carbon woven cloth, and the like. Examples thereof include carbon fibers, carbon plates, carbon paper, carbon disks, carbon cloth, carbon foil, and carbon-based materials obtained by compression-molding carbon particles. In addition, examples of the carbon-based material also include fine-structured materials such as carbon nanotubes, carbon nanohorns, and carbon nanoclusters.

The conductive polymer is a general term for polymer compounds having conductivity. Examples of the conductive polymer include aniline, aminophenol, diaminophenol, pyrrole, thiophene, paraphenylene, fluorene, furan, acetylene or a single monomer having a derivative thereof as a constituent unit or a polymer of two or more kinds of monomers. Can be mentioned. Specifically, examples of the conductive polymer include polyaniline, polyaminophenol, polydiaminophenol, polypyrrole, polythiophene, polyparaphenylene, polyfluorene, polyfuran, and polyacetylene. Examples of the conductive material made of metal include a stainless mesh. In consideration of availability, cost, corrosion resistance, durability, etc., the conductive material is preferably a carbon-based substance.

The shape of the conductive material is preferably a powder shape or a fiber shape. Moreover, the conductive material may be supported by a support. The support means a member which has rigidity itself and can give a certain shape to the gas diffusion electrode. The support may be an insulator or a conductor. When the support is an insulator, examples of the support include glass, plastic, synthetic rubber, ceramics, water-resistant or water-repellent treated paper, plant pieces such as wood pieces, bone pieces, animal pieces such as shells, and the like. .. Examples of the support having a porous structure include porous ceramics, porous plastics and sponges. When the support is a conductor, examples of the support include carbon papers, carbon fibers, carbon-based substances such as carbon rods, metals, and conductive polymers.

The catalyst in the gas diffusion layer 45 is not particularly limited, but preferably contains platinum. The catalyst may also include carbon particles doped with at least one non-metal atom and metal atom. The atoms doped in the carbon particles are not particularly limited. The non-metal atom is preferably at least one atom selected from the group consisting of nitrogen, boron, sulfur and phosphorus, for example. The metal atom is preferably at least one atom selected from the group consisting of manganese, iron, cobalt and copper.

In the gas diffusion layer 45, the catalyst may be bound to the conductive material using a binder. That is, the catalyst may be supported on the surface of the conductive material and inside the pores by using a binder. This can prevent the catalyst from being desorbed from the conductive material and deteriorating the oxygen reduction property. As the binder, it is preferable to use at least one selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride (PVDF), and ethylene-propylene-diene copolymer (EPDM). It is also preferable to use NAFION (registered trademark) as the binder.

(Negative electrode)
The negative electrode 43 according to the present embodiment has a function of supporting microorganisms, which will be described later, and further generating hydrogen ions and electrons from the organic substance in the electrolytic solution by the catalytic action of the microorganisms. Therefore, the negative electrode 43 is not particularly limited as long as it has a configuration that causes such a function.

The negative electrode 43 has a structure in which microorganisms are carried on a conductive sheet having conductivity. The conductor sheet preferably comprises at least one selected from the group consisting of a porous conductor sheet, a woven cloth-like conductor sheet and a non-woven cloth-like conductor sheet. Further, the conductor sheet may be a laminated body in which a plurality of sheets are laminated. By using such a sheet having a plurality of pores as the conductor sheet of the negative electrode 43, hydrogen ions generated in a local cell reaction described later easily move toward the positive electrode 41, and the rate of the oxygen reduction reaction is increased. It is possible to raise it. Further, from the viewpoint of improving ion permeability, the conductor sheet of the negative electrode 43 has a continuous space (void) in the stacking direction X of the positive electrode 41, the ion transfer layer 42, and the negative electrode 43, that is, in the thickness direction. It is preferable.

The conductor sheet may be a metal plate having a plurality of through holes penetrating in the thickness direction. Therefore, as the material forming the conductor sheet of the negative electrode 43, for example, at least one selected from the group consisting of aluminum, copper, stainless steel, nickel and titanium, and other conductive metals, and carbon paper and carbon felt is used. be able to.

A graphite sheet may be used as the conductor sheet of the negative electrode 43. In addition, it is preferable that the negative electrode 43 contains graphite, and that the graphene layers in the graphite are arranged along the plane of the positive electrode 41, the ion transfer layer 42, and the negative electrode 43 in the direction YZ perpendicular to the stacking direction X. By arranging the graphene layers in this manner, the conductivity in the direction YZ perpendicular to the stacking direction X is improved rather than the conductivity in the stacking direction X. Therefore, the electrons generated by the local battery reaction of the negative electrode 43 are easily conducted to the external circuit, and the efficiency of the battery reaction can be further improved.

The microorganism carried on the negative electrode 43 is not particularly limited as long as it is a microorganism that decomposes an organic substance in the electrolytic solution described later to generate hydrogen ions and electrons. As such a microorganism, for example, an aerobic microorganism that requires oxygen for growth or an anaerobic microorganism that does not require oxygen for growth can be used, but it is preferable to use an anaerobic microorganism. Anaerobic microorganisms do not require air to oxidize and decompose organic substances in the electrolyte. Therefore, the electric power required to send the air can be significantly reduced. Moreover, since the free energy acquired by the microorganisms is small, the amount of sludge generated can be reduced.

When the microorganisms carried on the negative electrode 43 are anaerobic microorganisms, it is preferable to maintain the anaerobic atmosphere around the negative electrode 43 in order to enhance the activity of the anaerobic microorganisms. Further, the anaerobic microorganisms retained on the negative electrode 43 are preferably, for example, electro-producing bacteria having an extracellular electron transfer mechanism. Specifically, examples of the anaerobic microorganisms include Geobacter genus bacteria, Shewanella genus bacteria, Aeromonas genus bacteria, Geothrix genus bacteria, and Saccharomyces genus bacteria.

The microorganisms may be retained on the negative electrode 43 by stacking and fixing the biofilm containing the microorganisms on the negative electrode 43. Specifically, a biofilm containing microorganisms may be fixed to the surface of the negative electrode 43 that directly contacts the electrolytic solution. In addition, a biofilm generally refers to a three-dimensional structure including a microbial population and an extracellular polymeric substance (EPS) produced by the microbial population. However, the microorganism may be retained on the negative electrode 43 without depending on the biofilm. Further, the microorganisms may be retained not only on the surface of the negative electrode 43 but also inside.

(Ion transfer layer)
The electrode assembly 40 may further include an ion transfer layer 42 that is provided between the positive electrode 41 and the negative electrode 43 and has proton permeability. Then, as shown in FIG. 3, the negative electrode 43 is separated from the positive electrode 41 via the ion transfer layer 42. The ion transfer layer 42 has a function of transmitting hydrogen ions generated in the negative electrode 43 and moving the hydrogen ions to the positive electrode 41 side.

As the ion transfer layer 42, for example, an ion exchange membrane using an ion exchange resin can be used. As the ion exchange resin, for example, NAFION (registered trademark) manufactured by DuPont Co., Ltd., and Flemion (registered trademark) and Selemion (registered trademark) manufactured by Asahi Glass Co., Ltd. can be used.

Further, as the ion transfer layer 42, a porous film having pores through which hydrogen ions can permeate may be used. That is, the ion transfer layer 42 may be a sheet having a space (void) for hydrogen ions to move from the negative electrode 43 to the positive electrode 41. Therefore, the ion transfer layer 42 preferably includes at least one selected from the group consisting of a porous sheet, a woven sheet and a non-woven sheet. Further, as the ion transfer layer 42, at least one selected from the group consisting of a glass fiber membrane, a synthetic fiber membrane, and a plastic non-woven fabric can be used, and a laminated body formed by laminating a plurality of these may be used. Since such a porous sheet has many pores inside, hydrogen ions can easily move. The pore size of the ion transfer layer 42 is not particularly limited as long as hydrogen ions can move from the negative electrode 43 to the positive electrode 41.

As described above, the ion transfer layer 42 has a function of transmitting hydrogen ions generated in the negative electrode 43 and moving the hydrogen ions to the positive electrode 41 side. Therefore, for example, if the negative electrode 43 and the positive electrode 41 are close to each other without coming into contact with each other, hydrogen ions can move from the negative electrode 43 to the positive electrode 41. Therefore, in the electrode unit 10A, the ion transfer layer 42 is not an essential component. However, by providing the ion transfer layer 42, hydrogen ions can be efficiently transferred from the negative electrode 43 to the positive electrode 41. Therefore, it is preferable to provide the ion transfer layer 42 from the viewpoint of improving the output. It should be noted that a gap may be provided between the positive electrode 41 and the ion transfer layer 42, or a gap may be provided between the negative electrode 43 and the ion transfer layer 42. That is, the electrode unit 10A does not necessarily have to include the ion transfer layer 42 and the negative electrode 43, and may include the positive electrode 41 provided so as to come into contact with oxygen existing in the hollow portion 21.

In the electrode unit 10A, the positive electrodes 41 of the hollow electrodes 20 are electrically connected to each other. The method of electrically connecting each positive electrode 41 is not particularly limited. For example, the positive electrodes 41 may be directly connected to each other with a conductive material such as metal. Further, the communication portion 35 itself may be a conductive material, and the positive electrode 41 may be electrically connected via the communication portion 35. Further, the conductor that electrically connects the positive electrode 41 may be routed inside the communication part 35 or may be routed outside the communication part 35.

[Second embodiment]
Next, the electrode unit 10B according to the second embodiment will be described with reference to FIG. The same components as those in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 4, the electrode unit 10B according to this embodiment includes a plurality of hollow electrodes 20. Among the plurality of hollow electrodes 20, adjacent hollow electrodes 20 are connected to each other by a connecting portion 30, and the hollow electrodes 20 are connected in a line. The connecting portion 30 connects one end of one hollow electrode 20 and one end of the other hollow electrode 20 among the adjacent hollow electrodes 20, and is configured to bend. Then, as will be described later, the electrode unit 10B is configured to be deformed.

Each hollow electrode 20 has a hollow portion 21, a side wall portion 22, and a pair of electrode assemblies 40 facing each other with the hollow portion 21 interposed therebetween, as in the first embodiment. The peripheral edge of the side wall 22 connects the peripheral edge of the one electrode assembly 40 and the peripheral edge of the other electrode assembly 40. The hollow portion 21 is surrounded by the pair of electrode joint bodies 40 and the side wall portion 22 which are arranged to face each other.

The hollow portion 21 of each hollow electrode 20 contains oxygen. The hollow portions 21 of each hollow electrode 20 are communicated with each other through the communication portion 35, and oxygen contained in each hollow portion 21 is configured to be able to pass back and forth. The communication part 35 is a pipe having a cavity inside, and an opening part of the side wall part 22 of one hollow electrode 20 and an opening part of the side wall part 22 of the other hollow electrode 20 among the adjacent hollow electrodes 20. Are connected. The communication part 35 is connected to substantially the center of the side wall part 22 in the thickness direction of the electrode assembly 40, and is configured to bend.

As shown in FIG. 4, each hollow electrode 20 has a rectangular parallelepiped strip shape. However, the hollow electrode 20 is not limited to such a shape, and may be a quadrangular prism such as a trapezoidal prism or an ellipsoid.

The connection part 30 and the communication part 35 are respectively connected to substantially the center of the side wall part 22 in the thickness direction of the electrode assembly 40, and are configured to bend as described above. The electrode unit 10B is configured to bend between adjacent hollow electrodes 20 in any direction in the thickness direction of the electrode assembly 40. That is, the electrode unit 10</b>B is configured such that, in the thickness direction of the electrode assembly 40, the surfaces of adjacent hollow electrodes 20 on the same direction side can directly contact and face each other.

Therefore, as shown in FIG. 4, the electrode unit 10B is configured to be deformed. Specifically, the electrode unit 10B is configured to bend between the adjacent hollow electrodes 20 among the plurality of hollow electrodes 20. More specifically, the electrode unit 10B is configured to be alternately folded. The electrode unit 10B is configured to be zigzag-folded, and is alternately bent in a substantially Z shape many times.

Therefore, since the electrode unit 10B can be pulled up from the electrolytic solution while being folded, a space larger than the size of the electrode unit 10B is unnecessary on the liquid surface of the electrolytic solution. Further, since the electrode unit 10B can be pulled up from the electrolytic solution while being folded, it becomes less necessary to prepare a large device for pulling up the electrode unit 10B from the electrolytic solution even when the electrode unit 10B is made large. Therefore, the electrode unit 10B can be easily taken out from the electrolytic solution.

Each hollow electrode 20 may include a fixing portion 23 that is a semi-ring-shaped fastener. The fixed portion 23 is provided on the side wall portions 22 at both ends of each hollow electrode 20, and the region surrounded by the hollow electrode 20 and the fixed portion 23 is an opening. A pull-up rope 24 is fixed to a fixed portion 23 provided on the hollow electrode 20 at one end of the electrode unit 10B, and a pull-up rope 24 is fixed to an opening portion of the fixed portion 23 provided on the other hollow electrodes 20. The rope 24 is passed through. Then, by pulling the end of the pulling rope 24 that is not fixed, the electrode unit 10B can be bent in a zigzag manner, and finally the electrode unit 10B can be deformed into a folded state.

[Third embodiment]
Next, the electrode unit 10C according to the third embodiment will be described with reference to FIG. The same components as those in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 5, the electrode unit 10C according to this embodiment includes a plurality of hollow electrodes 20. The electrode unit 10C has a blind shape and is configured to be deformed.

Each hollow electrode 20 has a hollow portion 21, a side wall portion 22, and a pair of electrode assemblies 40 facing each other with the hollow portion 21 interposed therebetween, as in the first embodiment. The peripheral edge of the side wall 22 connects the peripheral edge of the one electrode assembly 40 and the peripheral edge of the other electrode assembly 40. The hollow portion 21 is surrounded by the pair of electrode joint bodies 40 and the side wall portion 22 which are arranged to face each other.

The hollow portion 21 of each hollow electrode 20 contains oxygen. The hollow portions 21 of each hollow electrode 20 are communicated with each other through the communication portion 35, and oxygen contained in each hollow portion 21 is configured to be able to pass back and forth. The communication part 35 is a pipe having a cavity inside, and is configured to bend. The communication part 35 includes a main pipe 36 and a branch pipe 37 branched from the main pipe 36. The branch pipe 37 connects the opening provided in the side wall 22 of each hollow electrode 20 to the main pipe 36. There is.

Each hollow electrode 20 has a rectangular parallelepiped strip shape having a short side and a long side. The four corners of the hollow electrode 20 are connected by four rotating ropes 25, respectively, and the hollow electrodes 20 are connected in a row at substantially equal intervals. The pair of rotating ropes 25 connected to the long sides of the electrode assembly 40 are interlocked so that the vertical movements thereof coincide with each other. On the other hand, the pair of rotation ropes 25 connected to the short sides of the electrode assembly 40 are interlocked so that the vertical movements thereof move in different directions.

Therefore, as shown in FIG. 5, when the pair of rotating ropes 25 connected to one long side move upward, the pair of rotating ropes 25 connected to the other long side move downward. Move in the direction. Further, the electrode unit 10C is configured such that the long side of each hollow electrode 20 moves in the vertical direction in association with the vertical movement of the pair of rotating ropes 25 connected to the long side. Therefore, in the electrode unit 10C, each hollow electrode 20 is configured to rotate in the same direction. Specifically, each hollow electrode 20 is configured to rotate around the substantially central portion of the pair of rotation ropes 25 connected to the short sides in association with the movement of the rotation rope 25.

Each hollow electrode 20 may include a fixing portion 23 that is a semi-ring-shaped fastener. The fixed portion 23 is provided on the side wall portions 22 at both ends of each hollow electrode 20, and the region surrounded by the hollow electrode 20 and the fixed portion 23 is an opening. A pull-up rope 24 is fixed to a fixed portion 23 provided on the hollow electrode 20 at one end of the electrode unit 10C, and a pull-up rope 24 is pulled up to the openings of the fixed portions 23 provided on the other hollow electrodes 20. The rope 24 is passed through. Then, by pulling the end portion of the pulling rope 24 that is not fixed, the hollow electrode 20 to which the pulling rope 24 is fixed is pulled toward the hollow electrode 20 to which the pull rope 24 is not fixed. To be Therefore, the electrode unit 10C is in a state where the blind is finally pulled up, the gap between the hollow electrodes 20 is reduced, and the hollow electrodes 20 are stacked.

Therefore, similarly to the first embodiment, the electrode unit 10C is configured to be deformed. Specifically, as shown in FIG. 5, the hollow electrodes 20 are configured to rotate in the same direction, and the relative positions of the hollow electrodes 20 are displaced.

Therefore, since the electrode unit 10C can be pulled up from the electrolytic solution like a blind, a space larger than the size of the electrode unit 10C is not required on the liquid surface of the electrolytic solution. Further, since the electrode unit 10C can be pulled up from the electrolytic solution like a blind, it is less necessary to prepare a large device for pulling up from the electrolytic solution even when the electrode unit 10C is enlarged. Therefore, the electrode unit 10C can be easily taken out from the electrolytic solution.

As described above, the electrode unit 10 has been described using the electrode units 10A to 10C according to the first embodiment to the third embodiment. The electrode unit 10 according to the present embodiment surrounds at least a part of the hollow portion 21 in which oxygen exists, and has a plurality of hollow electrodes having a positive electrode 41 provided so as to come into contact with oxygen existing in the hollow portion 21. 20 is provided. The positive electrodes 41 of each hollow electrode 20 are electrically connected to each other. The electrode unit 10 is configured to be deformed. Therefore, as described above, since the electrode unit 10 can be easily taken out from the electrolytic solution, it is less necessary to prepare a large device for pulling up from the electrolytic solution.

<Liquid treatment system>
Next, the liquid treatment system 50 will be described in detail using the liquid treatment system 50A according to the first embodiment and the liquid treatment system 50B according to the second embodiment. The same components as those in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

[First embodiment]
The liquid processing system 50A according to this embodiment includes an electrode unit 10A. In the electrode unit 10A, as described above, the hollow electrode 20 is provided with the negative electrode 43 supporting the microorganism.

The liquid processing system 50A includes an electrolytic solution tank 51 that stores an electrolytic solution 56 containing an organic substance. The electrolytic solution tank 51 has a substantially rectangular parallelepiped shape, and a front wall 54 of the electrolytic solution tank 51 is provided with an inflow portion 52 for supplying the electrolytic solution 56 to the electrolytic solution tank 51 from the outside. The rear wall 55 of the electrolytic solution tank 51 is provided with an outflow portion 53 for discharging the treated electrolytic solution 56 from the electrolytic solution tank 51 to the outside.

The electrolytic solution 56 is continuously supplied into the electrolytic solution tank 51 through the inflow portion 52. Further, as shown in FIGS. 6 and 7, the electrode unit 10A is immersed in the electrolytic solution 56, and each hollow electrode 20 is in contact with the electrolytic solution 56. Therefore, the electrolytic solution 56 supplied from the inflow section 52 of the electrolytic solution tank 51 flows while contacting each hollow electrode 20, and then discharged from the outflow section 53.

In the present embodiment, the electrolytic solution 56 is waste water. When the electrolytic solution 56 contains, for example, glucose as an organic substance, carbon dioxide, hydrogen ions and electrons are generated by the following local cell reaction.
· Anode 43 _{(anode): C 6 H 12 O 6} + 6H 2 O → 6CO 2 + 24H + + 24e -
- the positive electrode 41 ^{_{(cathode): 6O 2 + 24H + +}} 24e - → 12H 2 O

In each hollow electrode 20, the negative electrode 43 is electrically connected to the positive electrode 41, and the organic substance in the electrolytic solution 56 is decomposed by the catalytic action of the microorganisms carried on the negative electrode 43 to generate electrons. The electrons generated at the negative electrode 43 move to the external circuit, and further move from the external circuit to the positive electrode 41. At this time, the electric energy flowing in the closed circuit is recovered by the external circuit, and the electrolytic solution 56 can also be purified.

The electrolytic solution 56 in the electrolytic solution tank 51 may contain an electron transfer mediator molecule. Alternatively, the electron transfer mediator molecule may modify the negative electrode 43. As a result, electron transfer from the microorganisms to the negative electrode 43 is promoted, and more efficient liquid treatment can be realized.

Specifically, in the metabolic mechanism of microorganisms, electrons are exchanged intracellularly or with the final electron acceptor. When the mediator molecule is introduced into the electrolytic solution 56, the mediator molecule acts as the final electron acceptor of metabolism, and transfers the received electron to the negative electrode 43. As a result, it becomes possible to increase the rate of oxidative decomposition of the organic substance in the electrolytic solution 56. Such an electron transfer mediator molecule is not particularly limited. As the electron transfer mediator molecule, for example, at least one selected from the group consisting of neutral red, anthraquinone-2,6-disulfonic acid (AQDS), thionine, potassium ferricyanide, and methyl viologen can be used.

As shown in FIG. 7, when the liquid processing system 50 is in operation, the plurality of hollow electrodes 20 are arranged in a straight line from the bottom wall 57 of the electrolytic solution tank 51 toward the liquid surface 58 of the electrolytic solution 56. .. The hollow electrode 20 on one end side of the electrode unit 10A is arranged on the bottom wall 57 side of the electrolytic solution tank 51, and the hollow electrode 20 on the other end side is arranged on the liquid level 58 side of the electrolytic solution 56. A part of the hollow electrode 20 on the liquid level 58 side is exposed above the liquid level 58 and is in contact with the gas phase containing oxygen, and the remaining part is immersed in the electrolytic solution 56.

As shown in FIG. 1, the electrode unit 10A is configured to be bent in the same direction between adjacent hollow electrodes 20 of the plurality of hollow electrodes 20 and wound into a roll shape. Therefore, the electrode unit 10</b>A can be easily taken out from the electrolytic solution 56 even if the amount of deposits attached to at least one of the positive electrode 41 and the negative electrode 43 increases due to the growth of biofilm and the accumulation of scale. ..

In addition, in this embodiment, the example in which the electrode unit 10A is used in the liquid processing system 50A has been described. However, the liquid treatment system 50 is not limited to such a form, and for example, the electrode unit 10B or the electrode unit 10C may be used instead of the electrode unit 10A.

[Second embodiment]
Next, a liquid processing system 50B according to the second embodiment will be described with reference to FIGS. The same components as those in the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

The liquid processing system 50B according to this embodiment includes an electrode unit 10B. In the electrode unit 10B, as described above, the hollow electrode 20 is provided with the negative electrode 43 supporting the microorganism. However, in the present embodiment, the side wall portion 22 of each hollow electrode 20 is removed from the above-described electrode unit 10B, and each hollow electrode 20 has an opening 26.

As shown in FIG. 8, the electrode unit 10B is immersed in the electrolytic solution 56, and each hollow electrode 20 is in contact with the electrolytic solution 56. The hollow electrode 20 is arranged so that each opening 26 is exposed on the liquid surface 58 of the electrolytic solution 56, and the hollow portion 21 of the hollow electrode 20 is open to the atmosphere. Therefore, oxygen contained in the atmosphere is supplied to each positive electrode 41 of the electrode unit 10B by natural diffusion.

Next, a method of folding the electrode unit 10B in the liquid processing system 50B according to this embodiment will be described. FIG. 8 shows a state before the electrode unit 10B is folded, and FIG. 9 shows a state where the electrode unit 10B is folded. As shown in FIG. 8, the hollow electrodes 20 are aligned in the direction Y. Then, as shown in FIG. 9, when the electrode unit 10B is folded, the electrode unit 10B is folded in the electrolytic solution 56 to move toward the one wall portion of the electrolytic solution tank 51. That is, in the liquid processing system 50B, the electrode unit 10B is configured to be deformed in the same plane direction Y as the liquid surface 58 of the electrolytic solution 56.

Then, as shown in FIG. 10, since the electrode unit 10B is immersed in the one wall portion of one electrolyte solution tank 51 in a folded state, the electrode unit 10B is tilted in the electrolyte solution tank 51 while the electrolyte solution is tilted. It can be taken out from 56. Therefore, a space larger than the size of the electrode unit 10B is not required on the liquid surface 58 of the electrolytic solution 56. Further, even if the amount of deposits attached to at least one of the positive electrode 41 and the negative electrode 43 increases due to the growth of biofilms and the accumulation of scale, the electrode unit 10B can be easily taken out from the electrolytic solution 56. ..

In addition, in this embodiment, the example in which the electrode unit 10B is used in the liquid processing system 50B has been described. However, the liquid treatment system 50 is not limited to such a form, and for example, the electrode unit 10A may be replaced with an electrode unit 10A or an electrode unit 10C.

As described above, the liquid processing system 50 has been described using the liquid processing system 50A according to the first embodiment and the liquid processing system 50B according to the second embodiment. The liquid processing system 50 according to the present embodiment includes the electrode unit 10 and an electrolytic solution tank 51 that stores an electrolytic solution 56 containing an organic substance. Each hollow electrode 20 further includes a negative electrode 43 that supports microorganisms and is electrically connected to the positive electrode 41. Each hollow electrode 20 is in contact with the electrolytic solution 56.

Each hollow electrode 20 in the electrode unit 10 includes a positive electrode 41 and a negative electrode 43 carrying microorganisms, and each hollow electrode 20 in the electrode unit 10 is in contact with the electrolytic solution 56. Therefore, the organic substance in the electrolytic solution 56 is decomposed by the catalytic action of the microorganisms carried on the negative electrode 43 to generate electrons. The electrons generated at the negative electrode 43 move to the external circuit, and further move from the external circuit to the positive electrode 41. At this time, the electric energy flowing in the closed circuit is recovered by the external circuit, and the electrolytic solution 56 can also be purified.

The liquid processing system 50 according to the present embodiment includes the electrode unit 10 described above. Therefore, even if deposits attached to at least one of the positive electrode 41 and the negative electrode 43 increase due to proliferation of biofilms and accumulation of scale, the electrode unit 10 can be easily taken out from the electrolytic solution 56. .. Since the characteristics of the taken-out electrode unit 10 can be restored by washing or replacement, the maintenance of the electrode unit 10 can be facilitated.

Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications can be made within the scope of the gist of the present embodiment.

10, 10A, 10B, 10C Electrode unit 20 Hollow electrode 21 Hollow part 41 Positive electrode 43 Negative electrode 50, 50A, 50B Liquid treatment system 51 Electrolyte tank 56 Electrolyte 58 58 Liquid level

Claims (7)

Surrounding at least a part of the hollow portion where oxygen is present, and comprising a plurality of hollow electrodes having a positive electrode provided so as to contact oxygen present in the hollow portion,
The positive electrodes of each hollow electrode are electrically connected to each other,
An electrode unit that is configured to deform. The electrode unit according to claim 1, which is configured to bend between adjacent hollow electrodes among the plurality of hollow electrodes. The electrode unit according to claim 2, wherein among the plurality of hollow electrodes, adjacent hollow electrodes are each bent in the same direction and wound into a roll. The electrode unit according to claim 2, wherein the electrode unit is configured to be alternately folded. Each of the hollow electrodes is configured to rotate in the same direction,
The electrode unit according to claim 1, wherein the relative position of each hollow electrode is configured to be displaced. An electrode unit according to any one of claims 1 to 5,
An electrolytic solution tank containing an electrolytic solution containing an organic substance,
Equipped with
Each of the hollow electrodes carries a microorganism and further comprises a negative electrode electrically connected to the positive electrode,
A liquid treatment system, wherein each hollow electrode is in contact with the electrolyte. The liquid processing system according to claim 6, wherein the electrode unit is configured to deform in the same plane direction as the liquid surface of the electrolytic solution.

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