JP2020099853A - Liquid treatment system - Google Patents

Abstract

To provide a liquid treatment system capable of suppressing a reduction of electric energy recovery efficiency and a big reduction of treating water quality accompanying a long period operation.SOLUTION: The liquid treatment system 1 includes an electrolyte tank 70 for storing an electrolyte 60 containing an organic substance, an anode 30 contacting the electrolyte 60 and carrying a microbe, and a cathode 20 contacting a gas phase G and electrically connected to the anode 30. The liquid treatment system 1 includes a measurement part 80 for measuring an accumulated extent of a sludge in the electrolyte tank 70, and a transfer part 90 for transferring the sludge accumulated in the electrolyte tank 70 from the electrolyte tank 70. The liquid treatment system 1 includes a control part 100 for controlling the transfer part 90 so as to transfer the sludge from the electrolyte tank 70 on the basis of a measured result measured by the measurement part 80.SELECTED DRAWING: Figure 2

Description

The present invention relates to liquid treatment systems.

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 form a closed circuit by connecting to each other via a load 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.

As the microbial fuel cell as described above, the microbial fuel cell described in Patent Document 1 is known. 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.

The microbial fuel cell described in Patent Document 1 replaces the deteriorated diaphragm and/or the positive electrode without lowering the energy recovery efficiency. However, when treating wastewater with microorganisms, sludge derived from microorganisms may be generated.

On the other hand, Patent Document 2 describes a method for treating sludge return water. In the method for treating sludge return water described in Patent Document 2, when the organic matter in the sludge return water is removed by using it as a fuel source for the microbial fuel cell, it is contained in oxygen gas or air on the positive electrode side of the microbial fuel cell. Oxygen and nitrifying bacteria are introduced. Then, the solution treated by the microbial fuel cell is subjected to nitrogen gas release and removal in a denitrification tank, and then a coagulant is added to the solution for solid-liquid separation along with phosphorus removal in the coagulation sedimentation tank.

Japanese Patent No. 5164511 Japanese Patent No. 4610977

However, even with the method described in Patent Document 2, when the microbial fuel cell is operated for a long period of time, sludge accumulates at the bottom of the electrolytic solution tank and the electrode is buried. There is a risk of deterioration of treated water quality. Further, since the amount of accumulated sludge depends on various conditions, it is required to effectively remove sludge according to the amount of accumulated sludge.

The present invention has been made in view of the problems of the related art. An object of the present invention is to provide a liquid treatment system capable of suppressing a decrease in electric energy recovery efficiency and a great decrease in treated water quality due to long-term operation.

In order to solve the above problems, a liquid treatment system according to an aspect of the present invention is an electrolytic solution tank that stores an electrolytic solution containing an organic substance, a negative electrode that is in contact with the electrolytic solution and carries microorganisms, and a gas phase. A positive electrode in contact with and electrically connected to the negative electrode. The liquid treatment system includes a measuring unit that measures the degree of sludge accumulation in the electrolytic solution tank, and a transfer unit that transfers the sludge accumulated in the electrolytic solution tank from the electrolytic solution tank. The liquid treatment system includes a control unit that controls the transfer unit to transfer the sludge from the electrolytic solution tank based on the measurement result measured by the measurement unit.

According to the present disclosure, it is possible to provide a liquid treatment system capable of suppressing a decrease in electric energy recovery efficiency and a large decrease in treated water quality due to long-term operation.

It is a perspective view which shows roughly an example of the liquid processing system which concerns on this embodiment. It is sectional drawing which followed the AA line in FIG. It is an exploded perspective view showing an example of an electrode unit in a liquid treatment system. It is a perspective view which shows schematically another example of the liquid processing system which concerns on this embodiment. It is sectional drawing which followed the BB line in FIG. It is sectional drawing which shows another example of the liquid processing system which concerns on this embodiment schematically. It is a flowchart which shows an example of the transfer method of sludge.

Hereinafter, 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 explanation and may differ from the actual ratios.

As shown in FIG. 1, the liquid treatment system 1 according to the present embodiment includes an electrode unit 10 having a negative electrode 30 supporting microorganisms and a positive electrode 20 electrically connected to the negative electrode 30. Further, the liquid processing system 1 includes an electrolytic solution tank 70 that accommodates an electrolytic solution 60 containing an organic substance, and that is further arranged so that the electrode unit 10 is immersed in the electrolytic solution 60.

[Electrode unit]
As shown in FIGS. 1 to 3, the electrode unit 10 includes an electrode assembly 55 having a positive electrode 20, a negative electrode 30, and an ion transfer layer 25. In the electrode unit 10, the positive electrode 20 is arranged so as to contact one surface 25a of the ion transfer layer 25, and the negative electrode 30 is arranged so as to contact the surface 25b of the ion transfer layer 25 opposite to the surface 25a. ing.

As shown in FIG. 3, the electrode assembly 55 is laminated and fixed to the spacer member 40. The spacer member 40 is a U-shaped frame member that extends along the outer periphery of the surface 20 a of the positive electrode 20, and has an open top. That is, the spacer member 40 is a frame member in which the bottom surfaces of the two first columnar members 41 are connected by the second columnar member 42. Then, as shown in FIG. 2, the side surface 43 of the spacer member 40 is joined to the outer peripheral portion of the surface 20 a of the positive electrode 20, and the side surface 44 opposite to the side surface 43 is the outer peripheral portion of the surface 50 a of the plate member 50. It is joined with.

As shown in FIGS. 1 and 2, the electrode unit 10 formed by laminating the electrode assembly 55, the spacer member 40, and the plate member 50 has an electrolytic solution tank so that a gas phase G communicating with the atmosphere is formed. It is arranged inside 70. The electrolytic solution 60, which is waste water, is held inside the electrolytic solution tank 70, and the gas diffusion layer 22, the negative electrode 30, and the ion transfer layer 25 of the positive electrode 20 are immersed in the electrolytic solution 60.

As will be described later, the positive electrode 20 includes a water-repellent layer 21 having water repellency, and the plate member 50 is made of a flat plate material that does not allow the electrolytic solution 60 to pass therethrough. Therefore, the electrolytic solution 60 held inside the electrolytic solution tank 70 is separated from the internal space formed by the electrode assembly 55, the spacer member 40, and the plate member 50, and the internal space becomes the gas phase G. There is. In the liquid processing system 1, the gas phase G is opened to the outside air, or the gas phase G is supplied with air from the outside by, for example, a pump. Furthermore, the positive electrode 20 and the negative electrode 30 are electrically connected to an external circuit (not shown).

(Positive electrode)
As shown in FIG. 2, the positive electrode 20 according to the present embodiment is composed of a gas diffusion electrode including a water repellent layer 21 and a gas diffusion layer 22 that is stacked so as to contact the water repellent layer 21. The gas diffusion layer 22 of the positive electrode 20 is in contact with the ion transfer layer 25, and the water repellent layer 21 is exposed on the gas phase G side. By using such a thin plate-shaped gas diffusion electrode, it becomes possible to easily supply oxygen in the gas phase G to the catalyst in the positive electrode 20.

<Water repellent layer>
The water repellent layer 21 of the positive electrode 20 is a layer having both water repellency and oxygen permeability. The water-repellent layer 21 is configured to allow the movement of oxygen from the gas phase G to the liquid phase while favorably separating the gas phase G and the liquid phase in the electrochemical system in the electrode unit 10. That is, the water-repellent layer 21 allows oxygen in the vapor phase G to permeate and move to the gas diffusion layer 22, while suppressing the movement of the electrolytic solution 60 to the vapor phase G side. The term “separation” as used herein means to physically cut off.

The water-repellent layer 21 is in contact with the gas phase G containing oxygen and diffuses oxygen in the gas phase G. In the configuration shown in FIG. 2, the water repellent layer 21 supplies oxygen to the gas diffusion layer 22 substantially uniformly. Therefore, the water repellent layer 21 is preferably a porous body so that the oxygen can be diffused. Since the water-repellent layer 21 has water repellency, it is possible to prevent the pores of the porous body from being clogged due to dew condensation or the like to reduce the oxygen diffusivity. Further, since the electrolytic solution 60 is unlikely to soak into the water repellent layer 21, oxygen can be efficiently circulated from the surface of the water repellent layer 21 that contacts the gas phase G to the surface that faces the gas diffusion layer 22. Becomes

The water repellent layer 21 is preferably formed in a sheet shape. The material forming the water repellent layer 21 is not particularly limited as long as it has water repellency and can diffuse oxygen in the gas phase G. Examples of the material forming the water-repellent layer 21 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 21 preferably has a plurality of through holes penetrating in the stacking direction X of the water repellent layer 21 and the gas diffusion layer 22.

As the water repellent layer 21, for example, a waterproof 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 21 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 21.

<Gas diffusion layer>
The gas diffusion layer 22 in the positive electrode 20 preferably includes a porous conductive material and a catalyst carried by the conductive material. The gas diffusion layer 22 may be composed of a porous catalyst having conductivity. By providing such a gas diffusion layer 22 on the positive electrode 20, it becomes possible to conduct electrons generated by a local cell reaction, which will be described later, between the catalyst and the external circuit. That is, as will be described later, the gas diffusion layer 22 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 22, so that the catalyst can advance the oxygen reduction reaction by oxygen, hydrogen ions and electrons.

In the positive electrode 20, it is preferable that oxygen permeates the water repellent layer 21 and the gas diffusion layer 22 and is supplied to the catalyst in order to ensure stable performance. Therefore, it is preferable that the gas diffusion layer 22 is a porous body having a large number of pores through which oxygen permeates, from the surface facing the water repellent layer 21 to the surface opposite thereto. In addition, the shape of the gas diffusion layer 22 is particularly preferably a three-dimensional mesh shape. Such a mesh shape makes it possible to impart high oxygen permeability and conductivity to the gas diffusion layer 22.

In the positive electrode 20, in order to efficiently supply oxygen to the gas diffusion layer 22, the water repellent layer 21 is preferably bonded to the gas diffusion layer 22 with an adhesive. Thereby, the diffused oxygen is directly supplied to the gas diffusion layer 22, and the oxygen reduction reaction can be efficiently performed. From the viewpoint of ensuring the adhesiveness between the water repellent layer 21 and the gas diffusion layer 22, the adhesive is preferably provided on at least part of the water repellent layer 21 and the gas diffusion layer 22. However, from the viewpoint of enhancing the adhesiveness between the water repellent layer 21 and the gas diffusion layer 22 and stably supplying oxygen to the gas diffusion layer 22 for a long period of time, the adhesive is the water repellent layer 21 and the gas diffusion layer 22. It is more preferable that it is provided on the entire surface between 22 and 22.

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 22 of the positive electrode 20 in this embodiment will be described in more detail. As described above, the gas diffusion layer 22 can be configured to include the porous conductive material and the catalyst carried by the conductive material.

The conductive material in the gas diffusion layer 22 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 22 is a platinum-based catalyst, a carbon-based catalyst using iron or cobalt, a transition metal oxide-based catalyst such as partially oxidized tantalum carbonitride (TaCNO) and zirconium carbonitride (ZrCNO), tungsten. Alternatively, a carbide-based catalyst using molybdenum, activated carbon or the like can be used.

The catalyst in the gas diffusion layer 22 is preferably a carbon-based material doped with metal atoms. The metal atom is not particularly limited, but titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, hafnium, tantalum, tungsten, rhenium, osmium, iridium. It is preferably an atom of at least one metal selected from the group consisting of platinum and gold. In this case, the carbon-based material exhibits excellent performance, particularly as a catalyst for promoting the oxygen reduction reaction. The amount of metal atoms contained in the carbon-based material may be appropriately set so that the carbon-based material has excellent catalytic performance.

It is preferable that the carbon-based material is further doped with at least one non-metal atom selected from the group consisting of nitrogen, boron, sulfur and phosphorus. The amount of non-metal atoms doped in the carbon-based material may be appropriately set so that the carbon-based material has excellent catalytic performance.

The carbon-based material is based on a carbon source material such as graphite and amorphous carbon, and the carbon source material is doped with a metal atom and one or more non-metal atoms selected from nitrogen, boron, sulfur and phosphorus. It can be obtained.

The combination of metal atoms and non-metal atoms doped in the carbon-based material is appropriately selected. In particular, it is preferable that the non-metal atom contains nitrogen and the metal atom contains iron. In this case, the carbon-based material can have a particularly excellent catalytic activity. The non-metal atom may be only nitrogen, and the metal atom may be only iron.

The non-metal atom may include nitrogen and the metal atom may include at least one of cobalt and manganese. Also in this case, the carbon-based material can have a particularly excellent catalytic activity. The non-metal atom may be nitrogen only. Further, the metal atom may be only cobalt, only manganese, or only cobalt and manganese.

The shape of the carbon-based material is not particularly limited. For example, the carbon-based material may have a particle shape or a sheet shape. The size of the carbon-based material having a sheet shape is not particularly limited, and the carbon-based material may have a minute size, for example. The carbonaceous material having a sheet shape may be porous. The sheet-shaped and porous carbon-based material preferably has, for example, a woven cloth shape, a non-woven cloth shape, or the like. Such a carbon-based material can form the gas diffusion layer 22 without a conductive material.

The carbon-based material configured as the catalyst in the gas diffusion layer 22 can be prepared as follows. First, a mixture containing a non-metal compound containing at least one non-metal selected from the group consisting of nitrogen, boron, sulfur and phosphorus, a metal compound, and a carbon source material is prepared. Then, this mixture is heated at a temperature of 800° C. or higher and 1000° C. or lower for 45 seconds or more and less than 600 seconds. As a result, it is possible to obtain a carbon-based material configured as a catalyst.

Here, as the carbon source material, for example, graphite or amorphous carbon can be used as described above. Furthermore, the metal compound is not particularly limited as long as it is a compound containing a metal atom capable of coordinatively bonding with a non-metal atom doped in the carbon source material. Examples of the metal compound include inorganic metal salts such as metal chlorides, nitrates, sulfates, bromides, iodides, and fluorides, organic metal salts such as acetates, hydrates of inorganic metal salts, and organic metal salts. It is possible to use at least one selected from the group consisting of hydrates of For example, when graphite is doped with iron, the metal compound preferably contains iron(III) chloride. When the graphite is doped with cobalt, the metal compound preferably contains cobalt chloride. When the carbon source material is doped with manganese, the metal compound preferably contains manganese acetate. The amount of the metal compound used is preferably determined, for example, so that the ratio of the metal atom in the metal compound to the carbon source material is in the range of 5 to 30% by mass, and further, this ratio is 5 to 20% by mass. More preferably, it is determined to be within the range.

As described above, the non-metal compound is preferably at least one non-metal compound selected from the group consisting of nitrogen, boron, sulfur and phosphorus. Examples of the nonmetallic compound include pentaethylenehexamine, ethylenediamine, tetraethylenepentamine, triethylenetetramine, octylboronic acid, 1,2-bis(diethylphosphinoethane), triphenyl phosphite, and benzyl disulfide. At least one compound selected from the group consisting of can be used. The amount of the non-metal compound used is appropriately set according to the amount of the non-metal atom doped into the carbon source material. The amount of the non-metal compound used is preferably determined such that the molar ratio of the metal atom in the metal compound to the non-metal atom in the non-metal compound is in the range of 1:1 to 1:2. , 1:1.5 to 1:1.8 is more preferably determined.

In the gas diffusion layer 22, 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 30 according to the present embodiment has a function of supporting microorganisms described later, and further has a function of generating hydrogen ions and electrons from at least one of the organic substance and the nitrogen-containing compound in the electrolytic solution 60 by the catalytic action of the microorganisms. Therefore, the negative electrode 30 is not particularly limited as long as it has a configuration that causes such a function.

The negative electrode 30 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 30, hydrogen ions generated by a local cell reaction described later easily move toward the positive electrode 20, and the rate of the oxygen reduction reaction is increased. It is possible to raise it. From the viewpoint of improving ion permeability, the conductor sheet of the negative electrode 30 has a continuous space (void) in the stacking direction X of the positive electrode 20, the ion transfer layer 25, and the negative electrode 30, 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 30, for example, at least one selected from the group consisting of aluminum, copper, stainless steel, conductive metals such as nickel and titanium, 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 30. In addition, it is preferable that the negative electrode 30 contains graphite, and that the graphene layers in the graphite are arranged along the plane of the positive electrode 20, the ion transfer layer 25, and the negative electrode 30 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 30 are easily conducted to the external circuit, and the efficiency of the battery reaction can be further improved.

The microorganisms supported on the negative electrode 30 are not particularly limited as long as they are microorganisms that decompose an organic substance or a nitrogen-containing compound in the electrolytic solution 60 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 the organic substances in the electrolytic solution 60. 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 30 are anaerobic microorganisms, it is preferable to keep the periphery of the negative electrode 30 in an anaerobic atmosphere in order to enhance the activity of the anaerobic microorganisms. Further, the anaerobic microorganisms retained on the negative electrode 30 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 in the negative electrode 30 by stacking and fixing the biofilm containing the microorganisms on the negative electrode 30. Specifically, a biofilm containing microorganisms may be fixed to the surfaces 30a and 30b of the negative electrode 30 that are in direct contact with the electrolytic solution 60. 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 30 without depending on the biofilm. The microorganisms may be retained not only on the surface of the negative electrode 30 but also inside.

The negative electrode 30 may be modified with, for example, an electron transfer mediator molecule. Alternatively, the electrolytic solution 60 in the electrolytic solution tank 70 may include electron transfer mediator molecules. As a result, electron transfer from the microorganisms to the negative electrode 30 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 60, the mediator molecule acts as the final electron acceptor for metabolism, and transfers the received electron to the negative electrode 30. As a result, it becomes possible to increase the rate of oxidative decomposition of the organic substance in the electrolytic solution 60. 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.

(Ion transfer layer)
The electrode unit 10 may be provided between the positive electrode 20 and the negative electrode 30, and may further include an ion transfer layer 25 having proton permeability. Then, as shown in FIGS. 1 and 2, the negative electrode 30 is separated from the positive electrode 20 via the ion transfer layer 25. The ion transfer layer 25 has a function of transmitting hydrogen ions generated in the negative electrode 30 and moving the hydrogen ions to the positive electrode 20 side.

As the ion transfer layer 25, 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 25, a porous film having pores through which hydrogen ions can permeate may be used. That is, the ion transfer layer 25 may be a sheet having a space (void) for hydrogen ions to move from the negative electrode 30 to the positive electrode 20. Therefore, the ion transfer layer 25 preferably includes at least one selected from the group consisting of a porous sheet, a woven sheet and a non-woven sheet. Further, the ion transfer layer 25 can use at least one selected from the group consisting of a glass fiber membrane, a synthetic fiber membrane, and a plastic non-woven fabric, and may be a laminate formed by laminating a plurality of these. Since such a porous sheet has many pores inside, hydrogen ions can easily move. The pore size of the ion transfer layer 25 is not particularly limited as long as hydrogen ions can move from the negative electrode 30 to the positive electrode 20.

As described above, the ion transfer layer 25 has a function of transmitting hydrogen ions generated in the negative electrode 30 and moving them to the positive electrode 20 side. Therefore, for example, if the negative electrode 30 and the positive electrode 20 are close to each other without contacting with each other, hydrogen ions can move from the negative electrode 30 to the positive electrode 20. Therefore, in the liquid processing system 1 of this embodiment, the ion transfer layer 25 is not an essential component. However, by providing the ion transfer layer 25, hydrogen ions can be efficiently transferred from the negative electrode 30 to the positive electrode 20, and therefore the ion transfer layer 25 is preferably provided from the viewpoint of improving the output. It should be noted that a gap may be provided between the positive electrode 20 and the ion transfer layer 25, or a gap may be provided between the negative electrode 30 and the ion transfer layer 25.

In the electrode unit 10, the entire upper part of the spacer member 40 is open, but it may be partially open or closed if it is possible to introduce air (oxygen) into the interior. Good.

An external circuit (not shown) is electrically connected to the positive electrode 20 and the negative electrode 30. The catalytic action of the microorganisms carried on the negative electrode 30 decomposes the organic substance in the electrolytic solution 60 to generate electrons. The electrons generated in the negative electrode 30 move to the external circuit, and further move from the external circuit to the positive electrode 20. At this time, the electric energy flowing through the closed circuit can be recovered by the external circuit.

Specifically, for example, when the electrolytic solution 60 contains glucose as an organic substance, carbon dioxide, hydrogen ions and electrons are generated by the following local cell reaction.
· Anode 30 _{(anode): C 6 H 12 O 6} + 6H 2 O → 6CO 2 + 24H + + 24e -
・Positive electrode 20 (cathode): 6O ₂ +24H ⁺ +24e ⁻ →12H ₂ O
In this way, since the organic substance in the electrolytic solution 60 comes into contact with the negative electrode 30 and is oxidatively decomposed, the liquid treatment system 1 recovers the electric energy from the organic substance in the electrolytic solution 60, so that the electrolytic solution 60 is discharged. Can be purified.

In the present embodiment, an example is described in which the electrode unit 10 in which the electrode assembly 55 is laminated and fixed on the spacer member 40 is immersed in the electrolytic solution 60. However, if the liquid treatment system 1 includes the negative electrode 30 that is in contact with the electrolytic solution 60 and carries microorganisms, and the positive electrode 20 that is in contact with the gas phase G and is electrically connected to the negative electrode 30, the liquid processing system 1 is Energy can be recovered and the electrolytic solution 60 can be purified. Therefore, in the liquid treatment system 1 of this embodiment, the spacer member 40 is not an essential component. For example, a part of the positive electrode 20 can be brought into contact with the gas phase G by floating the positive electrode 20 on the water surface 61 of the electrolytic solution 60 and submerging the negative electrode 30 in the electrolytic solution 60. In addition, in such a structure, the positive electrode 20 does not need to include the water-repellent layer 21. Further, the positive electrode 20 is not laminated on the spacer member 40, and in the vertical direction of the positive electrode 20, the lower half is immersed in the electrolytic solution 60, and the upper half is in contact with the gas phase G on the liquid surface 61 of the electrolytic solution 60. May be. Further, the positive electrode 20 constitutes a part of the wall of the electrolytic solution tank 70, one surface 20 a of the positive electrode 20 contacts the gas phase G outside the electrolytic solution tank 70, and the surface 20 a of the positive electrode 20 opposite to the surface 20 a. May be in contact with the electrolytic solution 60.

Further, in the drawings, the positive electrode 20, the negative electrode 30, the ion transfer layer 25, and the plate member 50 in the electrode unit 10 are formed in a rectangular shape. However, these shapes are not particularly limited, and can be arbitrarily changed depending on the size of the liquid treatment system 1, desired purification performance, and the like. Also, the area of each layer can be arbitrarily changed as long as the desired function can be exhibited.

[Electrolyte tank]
The liquid processing system 1 includes an electrolytic solution tank 70 that stores an electrolytic solution 60 containing an organic substance. The electrolytic solution tank 70 has a substantially rectangular parallelepiped shape, and a front wall 73 of the electrolytic solution tank 70 is provided with an inflow portion 71 for supplying the electrolytic solution 60 to the electrolytic solution tank 70. The rear wall 74 of the electrolytic solution tank 70 is provided with an outflow portion 72 for discharging the treated electrolytic solution 60 from the electrolytic solution tank 70.

The electrolytic solution 60 is continuously supplied into the electrolytic solution tank 70 through the inflow portion 71. Further, as shown in FIGS. 1 and 2, the electrode unit 10 is arranged inside the electrolytic solution tank 70 so as to be immersed in the electrolytic solution 60. Therefore, the electrolytic solution 60 supplied from the inflow section 71 of the electrolytic solution tank 70 flows while contacting the electrode unit 10, and then discharged from the outflow section 72.

[Measuring section]
When the liquid treatment system 1 is operated for a long period of time, sludge accumulates at the bottom of the electrolytic solution tank 70 and the electrodes are buried, so there is a risk that the electric energy recovery efficiency will decrease and the treated water quality will decrease. If such sludge accumulates at the bottom of the electrolytic solution tank 70 and at least one of the positive electrode 20 and the negative electrode 30 is covered with sludge, the electrochemical reaction by the liquid treatment system 1 may be hindered. Therefore, there is a possibility that the efficiency of recovering electric energy and the quality of treated water may deteriorate significantly.

Therefore, in the liquid processing system 1 according to the present embodiment, a measuring unit 80 that measures the degree of accumulation of sludge in the electrolytic solution tank 70 and a transfer that transfers the sludge accumulated in the electrolytic solution tank 70 from the electrolytic solution tank 70. And a section 90. Then, the liquid treatment system 1 includes a control unit 100 that controls the transfer unit 90 so as to transfer the sludge from the electrolytic solution tank 70 based on the measurement result measured by the measurement unit 80, as described later. Therefore, according to the liquid treatment system 1 of the present embodiment, it is possible to suppress a decrease in the electrical energy recovery efficiency and a large decrease in the quality of treated water due to long-term operation.

As described above, the measuring unit 80 measures the degree of sludge accumulation in the electrolytic solution tank 70. The specific measuring method is not particularly limited, but it is preferable that at least one of the negative electrode 30 and the positive electrode 20 is used for the measurement by the measuring unit 80. By using at least one of the negative electrode 30 and the positive electrode 20 included in the liquid treatment system 1, the degree of sludge accumulation can be measured with a simple configuration. That is, the measuring unit 80 may measure the degree of sludge accumulation using only the positive electrode 20 or the negative electrode 30, or may measure the degree of sludge accumulation using the negative electrode 30 and the positive electrode 20. ..

The sludge contains, for example, minute suspended matter contained in the electrolytic solution 60, dead bodies of microorganisms including microorganisms carried on the negative electrode 30, and the like. The degree of accumulation of sludge is, for example, at least one selected from the group consisting of volume, weight and height of accumulated sludge.

As shown in FIG. 2, the measurement unit 80 may use the negative electrode 30 and the positive electrode 20, for example, and measure the potential difference between the negative electrode 30 and the positive electrode 20. When the measuring unit 80 measures the potential difference, the measuring unit 80 may be, for example, a voltmeter. When the degree of accumulation of sludge in the electrolytic solution tank 70 increases and at least one of the positive electrode 20 and the negative electrode 30 is covered with sludge, the chemical reaction in the positive electrode 20 and the negative electrode 30 is suppressed, and the potential difference is small. Tends to become. Therefore, the degree of accumulation of sludge in the electrolytic solution tank 70 can be measured by measuring the potential difference. When the measuring unit 80 measures the potential difference, it is not necessary to install a reference electrode such as a silver-silver chloride electrode as in the case of measuring the potential of the negative electrode 30 or the positive electrode 20 as described below, and the reference electrode There is no need for maintenance. Therefore, the degree of sludge accumulation can be measured with a simple configuration.

The measurement unit 80 is not limited to the form shown in FIG. 2 and may have the following forms. The measurement unit 80 may measure the current flowing between the negative electrode 30 and the positive electrode 20, using the negative electrode 30 and the positive electrode 20, for example. The current flowing between the negative electrode 30 and the positive electrode 20 may be the current flowing through the negative electrode 30 or the positive electrode 20. When the measuring unit 80 measures the current, the measuring unit 80 may be, for example, an ammeter. When the degree of accumulation of sludge in the electrolytic solution tank 70 increases and at least one of the positive electrode 20 and the negative electrode 30 is covered with sludge, the chemical reaction in the positive electrode 20 and the negative electrode 30 is suppressed, and the current is small. Tends to become. Therefore, the degree of accumulation of sludge in the electrolytic solution tank 70 can be measured by measuring the current. When the measurement unit 80 measures a current, it is not necessary to install a reference electrode and there is no need for maintenance of the reference electrode as in the case of measuring a potential as described below. Therefore, the degree of sludge accumulation can be measured with a simple configuration.

The measurement unit 80 may measure the potential of the negative electrode 30 or the positive electrode 20 by using the negative electrode 30 or the positive electrode 20, for example. When the measuring unit 80 measures the potential of the negative electrode 30 or the positive electrode 20, the measuring unit 80 may be, for example, an electrometer. The electrometer is equipped with a reference electrode such as a silver-silver chloride electrode. The potential of the negative electrode 30 or the positive electrode 20 is measured by immersing the reference electrode in the electrolytic solution 60 and using the negative electrode 30 or the positive electrode 20 as the working electrode. can do. When the degree of accumulation of sludge in the electrolytic solution tank 70 increases and the positive electrode 20 or the negative electrode 30 is covered with the sludge, the chemical reaction in the positive electrode 20 or the negative electrode 30 is suppressed, and the potential of the negative electrode 30 shifts to the positive. Alternatively, the potential of the positive electrode 20 tends to shift to the negative. Therefore, by measuring the potential of the negative electrode 30 or the positive electrode 20, the degree of accumulation of sludge in the electrolytic solution tank 70 can be measured.

The measurement unit 80 may measure the current flowing between the negative electrode 30 and the positive electrode 20 and the time during which the current flows between the negative electrode 30 and the positive electrode 20, using the negative electrode 30 and the positive electrode 20, for example. .. When the measuring unit 80 measures the current, the measuring unit 80 may be, for example, an ammeter. When the measuring unit 80 measures the time when the current flows, the measuring unit 80 may be, for example, a timer that can measure the time when the current flows. When the degree of accumulation of sludge in the electrolytic solution tank 70 increases and at least one of the positive electrode 20 and the negative electrode 30 is covered with sludge, the chemical reaction in the positive electrode 20 and the negative electrode 30 tends to be suppressed. .. The Coulomb, which is the product of the current and the time, tends to be smaller than before it was covered with sludge. Therefore, the degree of accumulation of sludge in the electrolytic solution tank 70 can be measured by measuring the current and time.

In the liquid processing system 1 according to this embodiment, at least one of the negative electrode 30 and the positive electrode 20 does not necessarily have to be used for the measurement by the measuring unit 80. The measuring unit 80 may measure the elapsed time, for example. The elapsed time is, for example, the operating time of the liquid treatment system 1, the time when the current flows between the negative electrode 30 and the positive electrode 20, or the time after the sludge is transferred from the electrolytic solution tank 70 by the transfer unit 90 described later. And so on. However, from the viewpoint that the measurement unit 80 uses at least one of the negative electrode 30 and the positive electrode 20, it is preferable that the elapsed time is the time during which the current flows between the negative electrode 30 and the positive electrode 20. When the measuring unit 80 measures the elapsed time, the measuring unit 80 may be, for example, a timer. The degree of accumulation of sludge may be predictable to some extent depending on the type of microorganisms, the type and concentration of organic substances contained in the electrolytic solution 60, and the residence time of the electrolytic solution 60. Therefore, the degree of sludge accumulation is measured by a simple method by obtaining the time until the sludge accumulates to a predetermined degree by a preliminary test or the like and comparing the time with the elapsed time measured by the measuring unit 80. be able to.

The measurement unit 80 may measure the height of the interface between the accumulated sludge and the electrolytic solution 60, for example. The height of the interface is, for example, the height from the bottom surface of the electrolytic solution tank 70 to the interface. When the measuring unit 80 measures the height of the interface, the measuring unit 80 may be, for example, a sludge interface meter. The sludge interface meter is not particularly limited as long as it can measure the height of the interface, but may be, for example, an ultrasonic sludge interface meter. The ultrasonic sludge interface meter may include, for example, a transmitter that can transmit ultrasonic waves and a receiver that can receive the ultrasonic waves reflected at the interface. Then, the ultrasonic sludge interfacial meter can measure the height of the interface by measuring the time until the transmitted ultrasonic waves are reflected at the interface with the accumulated sludge and return.

Therefore, in the measuring unit 80, the potential difference between the negative electrode 30 and the positive electrode 20, the current flowing between the negative electrode 30 and the positive electrode 20, the potential of the negative electrode 30 or the positive electrode 20, and the current flowing between the negative electrode 30 and the positive electrode 20. At least one selected from the group consisting of the elapsed time, the elapsed time, and the height of the interface between the accumulated sludge and the electrolytic solution 60 may be measured. Specifically, the measuring unit 80 may be at least one measuring device selected from the group consisting of a voltmeter, an ammeter, an electrometer, a timer, and a sludge interface meter.

[Transportation part]
The transfer unit 90 transfers the sludge accumulated in the electrolytic solution tank 70 from the electrolytic solution tank 70. The transfer unit 90 may, for example, pull out sludge accumulated from the bottom of the electrolytic solution tank 70 and transfer the sludge from the electrolytic solution tank 70 to the outside of the electrolytic solution tank 70, or at least the electrolytic solution 60 at the bottom of the electrolytic solution tank 70. The sludge accumulated by stirring may be transferred from the electrolytic solution tank 70 to the outside of the electrolytic solution tank 70, or a combination thereof.

When the sludge accumulated from the bottom of the electrolytic solution tank 70 is extracted and transferred from the electrolytic solution tank 70, the transfer unit 90 is a pump 91 for discharging the sludge accumulated in the electrolytic solution tank 70 as shown in FIG. Good.

In FIG. 2, the pump 91 is provided in the discharge part 76 connected to the bottom wall 75 of the electrolytic solution tank 70. By operating the pump 91, the sludge accumulated in the bottom part of the electrolytic solution tank 70 is dissolved in the electrolytic solution. Discharge from the tank 70. The discharge part 76 is preferably provided on the outflow part 72 side, which is the downstream side of the electrolytic solution tank 70 in which sludge is more likely to accumulate than the inflow part 71, but is not particularly limited as long as it is a position where sludge can be discharged. ..

In the form of FIG. 2, the bottom wall 75 of the electrolytic solution tank 70 is a plane parallel to the water surface 61, but in the vicinity of the discharge part 76, the vertical direction is set so that sludge easily gathers around the discharge part 76. It may be formed to be inclined downward in Y. Further, a bottom conveyor 75 may be provided with something like a belt conveyor for transferring the sludge to the vicinity of the discharge unit 76 so that the sludge may easily collect around the discharge unit 76.

When stirring the electrolytic solution 60, the transfer section 90 may be an electrolytic solution stirring section as shown in FIGS. 5 and 6. The electrolytic solution stirring section can stir at least the electrolytic solution 60 existing at the bottom of the electrolytic solution tank 70. By stirring the electrolytic solution 60 existing at least at the bottom of the electrolytic solution tank 70, sludge rises up from the bottom of the electrolytic solution tank 70 and is diffused in the electrolytic solution 60. The diffused sludge passes through the outflow portion 72 and is discharged to the outside of the electrolytic solution tank 70 such as the settling tank 110 described later.

The configuration of the electrolytic solution stirring unit is not particularly limited as long as the electrolytic solution 60 at the bottom of the electrolytic solution tank 70 can be stirred. For example, as shown in FIG. 5, the electrolytic solution stirring unit preferably includes a pump for generating a flow of the electrolytic solution 60 at the bottom of the electrolytic solution tank 70. By using such a pump, a flow of the electrolytic solution 60 is generated at the bottom of the electrolytic solution tank 70, and sludge accumulated at the bottom of the electrolytic solution tank 70 is generated by the water flow and/or water pressure of the electrolytic solution 60. It becomes possible to diffuse it inside and transfer it from the electrolytic solution tank 70. The pump forming the electrolyte stirring unit is not particularly limited, but a submersible pump or a submersible motor pump can be used. A submersible pump is a pump that has electrical components that are wholly or partially submerged in electrolyte 60 during normal use. The submersible motor pump is a pump that is used by putting the entire pump together with the electric motor in the electrolytic solution 60.

The electrolytic solution stirring unit includes a pump arranged outside the electrolytic solution tank 70 and a pipe connected to the pump, and discharges the electrolytic solution 60 from the end of the pipe to remove the electrolytic solution tank 70. The configuration may be such that the flow of the electrolytic solution 60 is generated at the bottom.

The electrolytic solution stirring unit is not limited to the pump described above. For example, it is also preferable that the electrolytic solution stirring unit includes an air diffuser that diffuses the positive electrode 20. Specifically, as shown in FIG. 6, the air diffuser 93 (transfer unit 90) includes an air diffuser 94 having holes for diffusing gas, and a gas supply member for supplying gas to the holes. 95 may be provided.

The diffusing member 94 is a member having a large number of holes through which gas can flow. The air diffusing member 94 is not particularly limited, but for example, a porous ceramic air diffusing plate in which coarse ceramic particles are bonded with a binder or the like, or a synthetic resin diffusing plate can be used. A membrane diffuser can also be used as the air diffuser 94.

The gas supply member 95 is a hollow member that holds the diffusing member 94 and further supplies gas to the holes of the diffusing member 94. Then, the gas supplied from the gas supply member 95 passes through the holes of the air diffusing member 94 to form bubbles, and diffuses into the electrolytic solution 60.

It is preferable that a pipe 96 for supplying gas from the outside of the electrolytic solution tank 70 is connected to the gas supply member 95. Specifically, it is preferable that a hollow pipe 96 is connected to the lower portion of the gas supply member 95. The pipe 96 penetrates the front wall 73 of the electrolytic solution tank 70 and extends to the outside of the electrolytic solution tank 70. A compressor 97 for pumping gas is connected to the end of the pipe 96.

The gas diffused from the air diffuser 93 to the electrolytic solution 60 is not particularly limited. For example, air can be used as the gas. However, as described above, in order to enhance the activity of anaerobic microorganisms, it is preferable to keep the periphery of the negative electrode 30 in an anaerobic atmosphere. Therefore, the gas to be diffused is preferably a gas containing no oxygen, and for example, nitrogen is preferably used.

It is preferable that the electrolytic solution stirring section is provided at the bottom of the electrolytic solution tank 70, on the outflow section 72 side, which is the downstream side of the electrolytic solution tank 70 in which sludge is more likely to accumulate than the inflow section 71. However, the position where the electrolytic solution stirring unit is provided is not particularly limited as long as it is a position where sludge can be discharged. Further, the electrolytic solution stirring section is preferably provided below the positive electrode 20 and the negative electrode 30 in the vertical direction Y.

Specifically, as shown in FIG. 5, when the electrolytic solution stirring unit includes a submersible pump or a submersible motor pump, the pump is provided below the positive electrode 20 and the negative electrode 30 in the vertical direction Y. Is preferably provided. As a result, when the electrolytic solution stirring unit operates, a water flow upward from the bottom of the electrolytic solution tank 70 is generated, so that the sludge is diffused in the electrolytic solution 60, and the sludge accumulated in the electrolytic solution tank 70 is effectively removed. Can be removed. When the electrolytic solution stirring unit includes a pump arranged outside the electrolytic solution tank 70 and a pipe connected to the pump, the end of the pipe discharged by the electrolytic solution 60 is connected to the positive electrode in the vertical direction Y. It is preferably provided below 20 and the negative electrode 30.

When the electrolytic solution stirring unit includes the air diffuser 93 for diffusing the positive electrode 20, the air diffusing member 94 and the gas supply member 95 are arranged in the vertical direction Y in the positive electrode 20 as shown in FIG. And is preferably provided below the negative electrode 30. As a result, the bubbles float upward from the bottom of the electrolytic solution tank 70 and reach the water surface 61 of the electrolytic solution 60. At this time, the bubbles rise while stirring the sludge. Therefore, the air bubbles generated from the air diffuser 94 lift up the sludge from the bottom of the electrolytic solution tank 70 and diffuse it in the electrolytic solution 60. Therefore, for example, the sludge rides on the flow of the electrolytic solution 60, is transferred to the outside of the electrolytic solution tank 70, such as the settling tank 110 described later, through the outflow portion 72, and is removed from the electrolytic solution tank 70.

[Control part]
The control unit 100 controls the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the measurement result measured by the measurement unit 80. As shown in FIGS. 2, 5 and 6, the control unit 100 is electrically connected to the measuring unit 80 and the transfer unit 90, and based on the comparison result between the measurement result and the set value, the transfer unit 90. It controls the operating state of. Specifically, the control unit 100 controls the transfer unit 90 when the measurement result is larger than the set value or when the measured value is smaller than the set value. It should be noted that the set value is an arbitrary predetermined value (threshold value) because the optimum value varies depending on the conditions such as the concentration of the organic substance in the electrolytic solution 60 and the type of microorganism. The control unit 100 may include a CPU, and may further include at least one selected from the group consisting of RAM, ROM, and hard disk.

The control unit 100 may control the transfer unit 90 by turning it on/off, or may control the transfer unit 90 by performing multi-step adjustment such as off/weak/strong. In the case of ON/OFF control, the transfer unit 90 may be controlled so that it is turned OFF by an electric signal of 0 and turned ON by an electric signal of 1, for example. When the transfer unit 90 is the above-described electrolytic solution stirring unit, for example, the electrolytic solution 60 may be stirred when it is turned on and stopped when it is turned off.

Note that, as described above, the measurement result is the measured value of the potential difference between the negative electrode 30 and the positive electrode 20, the measured value of the current flowing between the negative electrode 30 and the positive electrode 20, the measured value of the potential of the negative electrode 30 or the positive electrode 20. At least one selected from the group consisting of a measured value of time during which an electric current flows between the negative electrode 30 and the positive electrode 20, a measured value of elapsed time, and a measured value of the height of the interface between the accumulated sludge and the electrolytic solution 60. It may be one.

That is, the measurement result may be a measured value of the potential difference between the negative electrode 30 and the positive electrode 20. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result between the measured value and the set value. Further, as described above, the measurement result may be a measured value of the current flowing between the negative electrode 30 and the positive electrode 20. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result between the measured value and the set value. In addition, as described above, the measurement result may be a measured value of the potential of the negative electrode 30 or the positive electrode 20. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result between the measured value and the set value.

Further, as described above, the measurement result may be a measurement value of elapsed time. Specifically, the measurement result may be a measured value of the time during which the current flows between the negative electrode 30 and the positive electrode 20. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result between the measured value and the set value. Further, as described above, the measurement result may be a measured value of the current flowing between the negative electrode 30 and the positive electrode 20 and a measured value of the time when the current flows between the negative electrode 30 and the positive electrode 20. .. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result of the product of the measured current value and the measured time value and the set value. Further, as described above, the measurement result may be a measured value of the height of the interface between the accumulated sludge and the electrolytic solution 60. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the comparison result between the measured value and the set value.

Next, an example of a method for transferring sludge from the electrolytic solution tank 70 will be described using the flowchart shown in FIG. 7. As shown in FIG. 7, in step S1, the control unit 100 compares and determines whether the value obtained based on the measurement result measured by the measurement unit 80 is smaller than the set value. When the above value is smaller than the set value (YES), the control unit 100 advances the process to step S2 and instructs the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70. On the other hand, when the above value becomes larger than the set value (NO), the control unit 100 returns the process to step S1. In the present embodiment, the control unit 100 instructs the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 when the above value becomes smaller than the set value. However, when the above value becomes larger than the set value, the control unit 100 may instruct the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70.

Specifically, the measured value of the potential difference between the negative electrode 30 and the positive electrode 20, the measured value of the current flowing between the negative electrode 30 and the positive electrode 20, the measured value of the potential of the negative electrode 30 or the positive electrode 20, and the measurement of the current. When at least one selected from the group consisting of the product of the value and the measured value of the time when the current flows between the negative electrode 30 and the positive electrode 20 becomes smaller than the set value, the control unit 100 electrolyzes the sludge. The transfer unit 90 may be controlled to transfer the liquid from the liquid tank 70. Further, when at least one of the measured value of the elapsed time and the measured value of the height of the interface between the accumulated sludge and the electrolytic solution 60 becomes larger than the set value, the control unit 100 causes the sludge to flow into the electrolytic solution tank. The transfer unit 90 may be controlled so as to transfer from the transfer unit 70.

[Settling tank]
As shown in FIGS. 4 to 6, the liquid treatment system 1 may further include a settling tank 110 arranged on the downstream side of the electrolytic solution tank 70. Then, the control unit 100 may control the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 to the settling tank 110 based on the measurement result. The transfer unit 90 is, for example, the electrolytic solution stirring unit as described above. The liquid processing system 1 also includes a connecting pipe 111 that supplies the electrolytic solution 60 discharged from the electrolytic solution tank 70. In the embodiment shown in FIGS. 5 and 6, the connecting pipe 111 discharges the electrolytic solution 60 from the electrolytic solution tank 70, and therefore also corresponds to the outflow portion 72. That is, one of the connecting pipes 111 is connected to the upper part of the rear wall 74 of the electrolytic solution tank 70, and the other of the connecting pipes 111 is connected to the upper part of the front wall 117 on the front side of the precipitation tank 110. Further, the liquid processing system 1 is provided with an outflow portion 112 that discharges the electrolytic solution 60 held in the precipitation tank 110, above the rear wall 118 behind the precipitation tank 110.

The liquid treatment system 1 is configured such that the electrolytic solution 60 passes through the connecting pipe 111, the precipitation tank 110, and the outflow portion 112 in order. Then, the sludge transferred by the transfer unit 90 is also supplied from the electrolytic solution tank 70 to the settling tank 110 through the connecting pipe 111. Since the sludge has a higher density than the electrolytic solution 60, the sludge settles on the bottom of the settling tank 110 as the precipitate 114. Therefore, in the settling tank 110, the electrolytic solution 60 treated in the electrolytic solution tank 70 is separated from the sludge.

The settling tank 110 is formed to have a recessed shape toward the bottom wall 119 so that the settling material 114 can be easily collected in a part. A discharge unit 115 is connected to the bottom wall 119 of the settling tank 110, and a pump 116 capable of discharging the precipitate 114 from the settling tank 110 is connected to the discharge unit 115. The precipitate 114 that has settled in the settling tank 110 is operated from the settling tank 110 through the outlet 113 and the discharge part 115 formed on the bottom wall 119 by operating the pump 116 under the control of the controller 100. May be discharged.

The liquid processing system 1 has one end connected to the discharge part 115 and the other end connected to the inflow part 71, and a return pipe (not shown) for returning the precipitate 114 precipitated in the settling tank 110 to the electrolytic solution tank 70. May be further provided. With such a return pipe, at least a part of the precipitate 114 is returned from the settling tank 110 to the electrolytic solution tank 70, and can be used for treating the electrolytic solution 60 in the electrolytic solution tank 70.

In the embodiment shown in FIGS. 5 and 6, an electrolytic solution stirring section is used as the transfer section 90, and a precipitation tank 110 is provided downstream of the electrolytic solution tank 70. However, if the sludge can be transferred from the electrolytic solution tank 70, the liquid treatment system 1 can suppress a decrease in the electrical energy recovery efficiency and a large decrease in the treated water quality due to long-term operation. Therefore, even when the electrolytic solution stirring unit is used as the transfer unit 90, the precipitation tank 110 is not an essential component.

As described above, the liquid treatment system 1 according to the present embodiment includes the electrolytic solution tank 70 that stores the electrolytic solution 60 containing an organic substance, the negative electrode 30 that is in contact with the electrolytic solution 60 and carries microorganisms, and the gas phase G. And a positive electrode 20 that is in contact with and is electrically connected to the negative electrode 30. The liquid treatment system 1 includes a measuring unit 80 that measures the degree of sludge accumulation in the electrolytic solution tank 70, and a transfer unit 90 that transfers the sludge accumulated in the electrolytic solution tank 70 from the electrolytic solution tank 70. The liquid treatment system 1 includes a control unit 100 that controls the transfer unit 90 to transfer the sludge from the electrolytic solution tank 70 based on the measurement result measured by the measurement unit 80.

Therefore, according to the liquid treatment system 1 according to the present embodiment, even if sludge accumulates due to long-term operation and the efficiency of collecting electrolytic energy and the quality of treated water start to deteriorate, based on the measurement result measured by the measuring unit 80. Sludge is transferred from the electrolytic solution tank 70. Therefore, the sludge accumulated in the electrolytic solution tank 70 can be removed before the electric energy recovery efficiency and the treated water quality are significantly reduced by the sludge, and the state of the sludge in the electrolytic solution tank 70 can be maintained. Therefore, the liquid treatment system 1 can suppress a decrease in electric energy recovery efficiency and a great decrease in treated water quality due to long-term operation.

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.

1 Liquid Treatment System 20 Positive Electrode 30 Negative Electrode 60 Electrolyte 70 Electrolyte Tank 80 Measuring Section 90 Transfer Section 100 Control Section 110 Precipitation Tank G Gas Phase

Claims (8)

An electrolytic solution tank containing an electrolytic solution containing an organic substance,
A negative electrode that is in contact with the electrolytic solution and carries microorganisms,
A positive electrode that is in contact with the gas phase and is electrically connected to the negative electrode;
A measuring unit for measuring the degree of accumulation of sludge in the electrolytic solution tank,
A transfer unit for transferring the sludge accumulated in the electrolytic solution tank from the electrolytic solution tank,
Based on the measurement result measured by the measuring unit, a control unit that controls the transfer unit to transfer the sludge from the electrolytic solution tank,
A liquid processing system comprising: The measurement result is a measured value of a potential difference between the negative electrode and the positive electrode, a measured value of a current flowing between the negative electrode and the positive electrode, a measured value of the potential of the negative electrode or the positive electrode, the negative electrode and the positive electrode. And at least one selected from the group consisting of a measured value of the time during which an electric current flows, a measured value of the elapsed time, and a measured value of the height of the interface between the accumulated sludge and the electrolytic solution, The liquid treatment system according to claim 1. The measurement result is a measurement value of a potential difference between the negative electrode and the positive electrode,
The liquid processing system according to claim 1, wherein the control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank based on a comparison result between the measured value and the set value. The measurement result is a measurement value of a current flowing between the negative electrode and the positive electrode,
The liquid processing system according to claim 1, wherein the control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank based on a comparison result between the measured value and the set value. The measurement result is a measured value of the potential of the negative electrode or the positive electrode,
The liquid processing system according to claim 1, wherein the control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank based on a comparison result between the measured value and the set value. The measurement result is a measurement value of a time during which a current flows between the negative electrode and the positive electrode,
The liquid processing system according to claim 1, wherein the control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank based on a comparison result between the measured value and the set value. The measurement result is a measurement value of a current flowing between the negative electrode and the positive electrode, and a measurement value of a time during which a current flows between the negative electrode and the positive electrode,
The control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank based on a comparison result of a product of a measured value of the current and a measured value of the time and a set value, 3. The liquid processing system according to 1 or 2. Further comprising a settling tank arranged on the downstream side of the electrolytic solution tank,
The liquid processing system according to claim 1, wherein the control unit controls the transfer unit to transfer the sludge from the electrolytic solution tank to the settling tank based on the measurement result. ..

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