JP2020099854A - Liquid treatment system - Google Patents

Abstract

To provide a liquid treatment system capable of maintaining treatment quality of water discharged high even if concentration of an organic matter in water to be treated is increased.SOLUTION: There is provided liquid treatment systems A which has a microbial fuel cell tank 1 comprising a negative electrode 20 which holds an anaerobic microorganism and is in contact with water 3 to be treated containing an organic matter and a positive electrode 10 electrically connected to the negative electrode. The liquid treatment systems A further comprises an activated sludge tank 2 having an oxygen supply part 200 which is provided on the downstream side of the microbial fuel cell tank and supplies oxygen to the water to be treated, a first organic matter concentration measuring part 220 which is provided on the downstream side of the microbial fuel cell tank and measures the concentration of an organic matter in the water to be treated flowing in the activated sludge tank and a control part 210 for controlling the oxygen supply part. The control part adjusts the amount of oxygen supplied from the oxygen supply part to the water to be treated according to the concentration of the organic matter measured by the first organic matter concentration measuring part.SELECTED DRAWING: Figure 2

Description

The present invention relates to liquid treatment systems.

Conventionally, various water treatment methods have been provided to remove organic substances and the like contained in wastewater. Specifically, there are provided water treatment methods such as an activated sludge method utilizing aerobic respiration of aerobic microorganisms and an anaerobic treatment method utilizing anaerobic respiration of anaerobic microorganisms.

In the activated sludge method, mud containing aerobic microorganisms (activated sludge) and waste water are mixed in a biological reaction tank, and the air necessary for the aerobic microorganisms to oxidize and decompose organic matter in the waste water is sent to the biological reaction tank. Waste water is purified by stirring at. While the activated sludge method can obtain good treated water quality, it requires enormous electric power for aeration of the biological reaction tank. Further, as aerobic microorganisms breathe oxygen and actively metabolize, a large amount of sludge, which is industrial waste, is generated.

On the other hand, in the anaerobic treatment method, since aeration is not required, it is possible to significantly reduce the amount of electric power required as compared with the activated sludge method. Further, since the free energy acquired by the anaerobic microorganisms is smaller than that of the aerobic microorganisms, the amount of sludge generated is reduced. However, the treated water quality obtained tends to be better when aerobic microorganisms are used.

Here, a microbial fuel cell is known as a technique using such anaerobic microorganisms. The microbial fuel cell is a wastewater treatment device that converts chemical energy of organic substances and nitrogen compounds contained in domestic wastewater and industrial wastewater into electric energy, and oxidizes and decomposes the organic substances and nitrogen compounds. 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 water to be treated. Then, the water to be treated containing an organic substance or the like is supplied to the negative electrode, and a gas containing oxygen is supplied to the positive electrode. The positive electrode and the negative electrode form a closed circuit (e ⁻ ) by being connected to each other via a load circuit. At the negative electrode, hydrogen ions (H ⁺ ) and electrons are generated from the water to be treated due to the catalytic action of microorganisms. Then, the generated hydrogen ions move to the positive electrode, and the electrons move to the positive electrode via the load circuit. Hydrogen ions and electrons transferred from the negative electrode are combined with oxygen (O ₂ ) in the positive electrode to be consumed as water (H ₂ O). At that time, the electric energy flowing through the closed circuit is recovered.

In Patent Document 1, a negative electrode that is immersed in an organic substrate to support anaerobic microorganisms, an outer shell formed of an ion-permeable diaphragm, and an inlet/outlet are enclosed together with an electrolytic solution in an enclosed hollow cassette. A microbial fuel cell comprising a positive electrode plugged into an organic substrate is disclosed. Then, in the microbial fuel cell, while supplying oxygen into the cassette via the inlet/outlet hole, electricity is taken out via a circuit electrically connecting the negative electrode and the positive electrode.

Japanese Patent No. 5164511

However, in the microbial fuel cell as shown in Patent Document 1, when the concentration of organic matter in the water to be treated flowing into the cell is increased, the decomposition of the organic matter becomes insufficient, and the treated water quality of the water discharged from the cell is There was a problem of lowering.

The present invention has been made in view of the problems of the related art. Then, an object of the present invention is to provide a liquid treatment system capable of maintaining the treated water quality of discharged water high even when the concentration of organic substances in the treated water rises.

In order to solve the above problems, the liquid treatment system according to the first aspect of the present invention holds an anaerobic microorganism, and is a negative electrode that is in contact with water to be treated containing an organic matter, and is electrically connected to the negative electrode. A microbial fuel cell tank having a positive electrode, and an activated sludge tank provided on the downstream side of the microbial fuel cell tank and having an oxygen supply unit for supplying oxygen to the water to be treated, and provided on the downstream side of the microbial fuel cell tank. A first organic substance concentration measuring unit that measures the concentration of organic substances in the water to be treated that flows into the activated sludge tank, and a control unit that controls the oxygen supply unit. The control unit controls the amount of oxygen supplied from the oxygen supply unit to the water to be treated according to the concentration of the organic substance measured by the first organic substance concentration measuring unit.

A liquid treatment system according to a second aspect of the present invention is a microbial fuel cell comprising a negative electrode that holds anaerobic microorganisms and is in contact with water to be treated containing organic matter, and a positive electrode electrically connected to the negative electrode. Tank and an activated sludge tank that is provided on the downstream side of the microbial fuel cell tank and has an oxygen supply unit that supplies oxygen to the water to be treated, and an activated sludge tank that is provided on the downstream side of the microbial fuel cell tank and that flows into the activated sludge tank. The first organic matter concentration measuring unit for measuring the concentration of organic matter in the treated water, the upstream side of the microbial fuel cell tank, and at least one of the microbial fuel cell tank and the activated sludge tank, the flow rate of the treated water And a control unit that controls the flow rate adjusting unit. The control unit controls the flow rate adjusting unit to adjust the flow rate of the water to be treated flowing into the activated sludge tank according to the concentration of the organic matter measured by the first organic matter concentration measuring unit.

According to the present disclosure, it is possible to provide a liquid treatment system capable of maintaining high treated water quality of discharged water even when the concentration of organic substances in treated water rises.

It is a perspective view which shows roughly the liquid processing system which concerns on 1st embodiment. It is sectional drawing which followed the II line in FIG. FIG. 3 is an exploded perspective view showing an example of an electrode cassette in the liquid processing system according to the first embodiment. 6 is a flowchart for explaining control of the oxygen supply amount to the activated sludge tank in the liquid treatment system according to the first embodiment. It is sectional drawing which shows schematically the liquid treatment system which concerns on 2nd embodiment. It is a flow chart for explaining control of the amount of oxygen supply to an activated sludge tank in the liquid treatment system concerning a second embodiment. It is sectional drawing which shows schematically the liquid processing system which concerns on 3rd embodiment. It is sectional drawing which shows schematically the liquid processing system which concerns on 4th embodiment. 9 is a flowchart for explaining control of the oxygen supply amount to the activated sludge tank in the liquid treatment system according to the fourth embodiment. It is a flow chart for explaining control of a flow of treated water which flows into an activated sludge tank in a liquid treatment system concerning a fifth embodiment. It is a perspective view which shows the liquid treatment system which concerns on 6th embodiment schematically. It is sectional drawing which followed the II-II line in FIG. It is an exploded perspective view showing an example of an oxygen supply cassette in a liquid treatment system concerning a sixth embodiment. It is a schematic diagram for explaining the oxygen supply part in the liquid treatment system concerning a sixth embodiment.

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.

[First embodiment]
As shown in FIG. 1, the liquid treatment system A according to the present embodiment is provided with a microbial fuel cell tank 1 that holds waste water 3 to be treated, which is waste water. Further, the liquid treatment system A holds the water to be treated 3, communicates with the microbial fuel cell tank 1 through the connecting pipe 4, and further includes an activated sludge tank 2 arranged downstream of the microbial fuel cell tank 1. I have it. Further, the liquid treatment system A includes an electrode cassette 100 provided inside the microbial fuel cell tank 1 and an oxygen supply unit 200 provided in the activated sludge tank 2. The microbial fuel cell tank 1 is a tank that produces electric energy while decomposing organic matter by the action of anaerobic microorganisms that are electricity-producing bacteria, and the activated sludge tank 2 is a vessel that oxidatively decomposes organic matter by the activated sludge method. is there.

The microbial fuel cell tank 1 is a substantially rectangular parallelepiped-shaped container, and an inlet 5 for supplying the water to be treated 3 to the microbial fuel cell tank 1 is provided above the front wall 1a of the microbial fuel cell tank 1. There is. The activated sludge tank 2 is also a substantially rectangular parallelepiped-shaped container, and an outlet 6 for discharging the treated water 3 after treatment from the activated sludge tank 2 is provided above the rear wall 2b of the activated sludge tank 2. There is. The upper part of the rear wall 1b of the microbial fuel cell tank 1 and the upper part of the front wall 2a of the activated sludge tank 2 are connected by a cylindrical connecting pipe 4.

The electrode cassette 100 is arranged so as to be immersed in the water to be treated 3 inside the microbial fuel cell tank 1, and at least a part of the oxygen supply unit 200 is arranged inside the activated sludge tank 2.

Then, the water 3 to be treated is continuously supplied into the microbial fuel cell tank 1 through the inflow port 5. The treated water 3 supplied to the microbial fuel cell tank 1 flows while contacting the electrode cassette 100, and then continuously moves into the activated sludge tank 2 through the connecting pipe 4. Oxygen is supplied from the oxygen supply unit 200 to the water to be treated 3 that has moved to the activated sludge tank 2 and then discharged from the outlet 6.

[Electrode cassette]
The electrode cassette 100 is composed of a microbial fuel cell capable of purifying organic substances in the water 3 to be treated and generating electric energy. Specifically, as shown in FIGS. 1 to 3, the electrode cassette 100 includes an electrode assembly 40 including a positive electrode 10, a negative electrode 20, and an ion transfer layer 30. In the electrode cassette 100, the negative electrode 20 is arranged so as to contact one surface 30a of the ion transfer layer 30, and the positive electrode 10 is arranged so as to contact the surface 30b opposite to the surface 30a of the ion transfer layer 30. ing. Then, the gas diffusion layer 12 of the positive electrode 10 is in contact with the ion transfer layer 30, and the water repellent layer 11 is exposed on the gas phase G side.

Then, as shown in FIG. 3, the electrode assembly 40 is laminated on the spacer member 50. The spacer member 50 is a U-shaped frame member that extends along the outer periphery of the surface 10 a of the positive electrode 10, and has an open top. That is, the spacer member 50 is a frame member in which the bottom surfaces of the two first columnar members 51 are connected by the second columnar member 52. Then, as shown in FIG. 2, the side surface 53 of the spacer member 50 is joined to the outer peripheral portion of the surface 10 a of the positive electrode 10.

As shown in FIG. 2, the electrode cassette 100 formed by stacking two sets of the electrode assembly 40 and the spacer member 50 has the inside of the microbial fuel cell tank 1 so that the gas phase G communicating with the atmosphere is formed. Is located in. The water 3 to be treated is held inside the microbial fuel cell tank 1, and the gas diffusion layer 12, the negative electrode 20 and the ion transfer layer 30 of the positive electrode 10 are immersed in the water 3 to be treated.

As described later, the positive electrode 10 includes a water repellent layer 11 having water repellency. Therefore, the water to be treated 3 held inside the microbial fuel cell tank 1 is separated from the inside of the spacer member 50, and the internal space formed by the electrode assembly 40 and the spacer member 50 is in the vapor phase G. .. In the liquid processing system A, the gas phase G is opened to the outside air, or air is supplied to the gas phase G from the outside by a pump, for example. Further, as shown in FIG. 2, the positive electrode 10 and the negative electrode 20 are electrically connected to the external circuit 60, respectively.

(Positive electrode)
As shown in FIG. 2, the positive electrode 10 according to the present embodiment is composed of a gas diffusion electrode including a water repellent layer 11 and a gas diffusion layer 12 that is stacked so as to contact the water repellent layer 11. 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 10.

<Water repellent layer>
The water repellent layer 11 in the positive electrode 10 is a layer having both water repellency and oxygen permeability. The water-repellent layer 11 is configured to allow the movement of oxygen from the gas phase G toward the liquid phase while favorably separating the gas phase G and the liquid phase in the electrochemical system in the electrode cassette 100. That is, the water-repellent layer 11 allows oxygen in the vapor phase G to permeate and move to the gas diffusion layer 12, while suppressing movement of the water to be treated 3 to the vapor phase G side. The term “separation” as used herein means to physically cut off.

The water-repellent layer 11 is in contact with the gas phase G containing oxygen and diffuses oxygen in the gas phase G. In the structure shown in FIG. 2, the water repellent layer 11 supplies oxygen to the gas diffusion layer 12 substantially uniformly. Therefore, the water repellent layer 11 is preferably a porous body so that the oxygen can be diffused. Since the water-repellent layer 11 has water repellency, it is possible to prevent the pores of the porous body from being clogged by dew condensation or the like, and reducing the diffusivity of oxygen. Further, since the water 3 to be treated is unlikely to soak into the water repellent layer 11, oxygen can be efficiently circulated from the surface of the water repellent layer 11 that contacts the gas phase G to the surface that faces the gas diffusion layer 12. It will be possible.

The water-repellent layer 11 is preferably formed of a woven or non-woven fabric into a sheet shape. The material forming the water-repellent layer 11 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 11 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 11 preferably has a plurality of through holes in the stacking direction X of the water-repellent layer 11 and the gas diffusion layer 12.

The water-repellent layer 11 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 11.

<Gas diffusion layer>
The gas diffusion layer 12 in the positive electrode 10 preferably includes a porous conductive material and a catalyst carried by the conductive material. The gas diffusion layer 12 may be composed of a porous catalyst having conductivity. By using such a gas diffusion layer 12 for the positive electrode 10, it becomes possible to conduct electrons generated by a local cell reaction, which will be described later, between the catalyst and the external circuit 60. That is, as will be described later, the gas diffusion layer 12 carries a catalyst, and the catalyst is an oxygen reduction catalyst. Then, the electrons move from the external circuit 60 through the gas diffusion layer 12 to the catalyst, whereby the oxygen reduction reaction by oxygen, hydrogen ions and electrons can be advanced by the catalyst.

In the positive electrode 10, it is preferable that oxygen permeates the water repellent layer 11 and the gas diffusion layer 12 and is supplied to the catalyst in order to ensure stable performance. Therefore, the gas diffusion layer 12 is preferably a porous body having a large number of pores through which oxygen permeates, from the surface facing the water repellent layer 11 to the surface opposite thereto. Further, it is particularly preferable that the shape of the gas diffusion layer 12 is a three-dimensional mesh shape. Such a mesh shape makes it possible to impart high oxygen permeability and conductivity to the gas diffusion layer 12.

In the positive electrode 10, in order to efficiently supply oxygen to the gas diffusion layer 12, the water repellent layer 11 is preferably bonded to the gas diffusion layer 12 via an adhesive. Thereby, the diffused oxygen is directly supplied to the gas diffusion layer 12, and the oxygen reduction reaction can be efficiently performed. From the viewpoint of ensuring the adhesiveness between the water repellent layer 11 and the gas diffusion layer 12, the adhesive is preferably provided on at least part of the water repellent layer 11 and the gas diffusion layer 12. However, from the viewpoint of enhancing the adhesiveness between the water repellent layer 11 and the gas diffusion layer 12 and stably supplying oxygen to the gas diffusion layer 12 for a long period of time, the adhesive is the water repellent layer 11 and the gas diffusion layer 12. More preferably, it is provided on the entire surface between 12 and 12.

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 12 of the positive electrode 10 in this embodiment will be described in more detail. As described above, the gas diffusion layer 12 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 12 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 12 is a platinum catalyst, a carbon catalyst using iron or cobalt, a transition metal oxide 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 12 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 12 without a conductive material.

The carbon-based material configured as the catalyst in the gas diffusion layer 12 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 nonmetal compound include pentaethylenehexamine, ethylenediamine, tetraethylenepentamine, triethylenetetramine, ethylenediamine, octylboronic acid, 1,2-bis(diethylphosphinoethane), triphenylphosphite, and benzyldisal. At least one compound selected from the group consisting of fido 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 12, 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 20 in the present embodiment has a function of supporting a microorganism described below, and further having a function of generating a hydrogen ion and an electron from an organic substance in the water to be treated 3 by a catalytic action of the microorganism. Therefore, the negative electrode 20 is not particularly limited as long as it has a configuration that causes such a function.

The negative electrode 20 has a structure in which microorganisms are carried on a conductive sheet having conductivity. As the conductor sheet, 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 can be used. 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 20, hydrogen ions generated by a local cell reaction described later easily move toward the ion transfer layer 30 and the oxygen reduction reaction It is possible to increase the speed. In addition, from the viewpoint of improving the ion permeability, the conductor sheet of the negative electrode 20 has a continuous space (void) in the stacking direction X of the positive electrode 10, the ion transfer layer 30, and the negative electrode 20, that is, the thickness direction. It is preferable.

The conductor sheet may be a metal plate having a plurality of through holes in the thickness direction. Therefore, as the material forming the conductor sheet of the negative electrode 20, 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 that can be used for the positive electrode 10 may be used as the conductor sheet of the negative electrode 20. The negative electrode 20 preferably contains graphite, and the graphene layers in the graphite are preferably arranged along the plane of the positive electrode 10, the ion transfer layer 30, and the negative electrode 20 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 20 are easily conducted to the external circuit 60, and the efficiency of the battery reaction can be further improved.

The microorganism carried on the negative electrode 20 is not particularly limited as long as it is a current-producing bacterium that decomposes organic substances in the water to be treated 3 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 for oxidatively decomposing organic substances in the water 3 to be treated. 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.

Examples of aerobic microorganisms retained on the negative electrode 20 include Escherichia bacterium, Escherichia coli, Pseudomonas bacterium, Pseudomonas aeruginosa, and Bacillus bacterium, Bacillus subtilis. Further, the anaerobic microorganisms retained on the negative electrode 20 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 20 by stacking and fixing the biofilm containing the microorganisms on the negative electrode 20. 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 20 without depending on the biofilm. The microorganisms may be retained not only on the surface of the negative electrode 20 but also inside.

The negative electrode 20 may be modified, for example, with an electron transfer mediator molecule. Alternatively, the water 3 to be treated in the microbial fuel cell tank 1 may contain an electron transfer mediator molecule. As a result, electron transfer from the microorganisms to the negative electrode 20 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 a mediator molecule is introduced into the water to be treated 3, the mediator molecule acts as the final electron acceptor for metabolism, and the received electron is transferred to the negative electrode 20. As a result, it becomes possible to increase the rate of oxidative decomposition of organic substances in the water 3 to be treated. 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 cassette 100 of the present embodiment further includes an ion transfer layer 30 provided between the positive electrode 10 and the negative electrode 20 and having proton permeability and electrical insulation. Then, as shown in FIGS. 1 and 2, the negative electrode 20 is separated from the positive electrode 10 via the ion transfer layer 30. The ion transfer layer 30 has a function of transmitting hydrogen ions generated in the negative electrode 20 and moving them to the positive electrode 10 side.

As the ion transfer layer 30, 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 30, a porous film having pores through which hydrogen ions can permeate may be used. That is, the ion transfer layer 30 may be a sheet having a space (void) for hydrogen ions to move from the negative electrode 20 to the positive electrode 10. Therefore, the ion transfer layer 30 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 30 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 laminated body 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 30 is not particularly limited as long as hydrogen ions can move from the negative electrode 20 to the positive electrode 10.

As described above, the ion transfer layer 30 has a function of transmitting hydrogen ions generated in the negative electrode 20 and moving the hydrogen ions to the positive electrode 10 side. However, for example, if the negative electrode 20 and the positive electrode 10 are close to each other without coming into contact with each other, hydrogen ions can move from the negative electrode 20 to the positive electrode 10. Therefore, in the liquid processing system A, the ion transfer layer 30 is not an essential component. However, by providing the ion transfer layer 30, it becomes possible to efficiently transfer hydrogen ions from the negative electrode 20 to the positive electrode 10. Therefore, it is preferable to provide the ion transfer layer 30 from the viewpoint of improving the output. A space may be provided between the positive electrode 10 and the ion transfer layer 30, and a space may be provided between the negative electrode 20 and the ion transfer layer 30.

In the electrode cassette 100, the entire upper portion of the spacer member 50 is open, but it may be partially open or closed if it is possible to introduce air (oxygen) into the interior. Good.

[External circuit]
As shown in FIGS. 1 and 2, an external circuit 60 is electrically connected to the positive electrode 10 and the negative electrode 20. As will be described later, due to the catalytic action of the microorganisms carried on the negative electrode 20, the organic substances in the water 3 to be treated are decomposed to generate electrons. The electrons generated in the negative electrode 20 move to the external circuit 60, and further move from the external circuit 60 to the positive electrode 10. At this time, the external circuit 60 can recover the electric energy flowing in the closed circuit.

[Oxygen supply section]
In the liquid treatment system A, the activated sludge tank 2 includes an oxygen supply unit 200 for supplying oxygen from outside to the water to be treated 3 held inside the activated sludge tank 2. The configuration of the oxygen supply unit 200 is not particularly limited as long as oxygen can be supplied to the water to be treated 3 inside the activated sludge tank 2 based on a command from the control unit 210. Further, the oxygen supply unit 200 may be configured to supply air to the water to be treated 3 inside the activated sludge tank 2.

For example, the oxygen supply unit 200 preferably includes an air diffuser that diffuses oxygen into the water 3 to be treated. Specifically, as shown in FIG. 2, the air diffusing device 110 includes an air diffusing member 111 having holes for diffusing oxygen, and an oxygen supplying member 112 that supplies oxygen to the holes. You can

The diffuser member 111 is a member having a large number of holes through which oxygen can flow. The air diffusing member 111 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 111.

The oxygen supply member 112 is a hollow member that holds the diffuser member 111 and further supplies oxygen to the holes of the diffuser member 111. Then, the oxygen supplied from the oxygen supply member 112 passes through the holes of the diffuser member 111 to form bubbles, which diffuse into the water 3 to be treated.

A pipe 113 for supplying oxygen from the outside of the activated sludge tank 2 is preferably connected to the oxygen supply member 112. Specifically, it is preferable that a hollow pipe 113 is connected to the lower portion of the oxygen supply member 112. The pipe 113 penetrates the rear wall 2b of the activated sludge tank 2 and extends to the outside of the activated sludge tank 2. A compressor 114 for pumping oxygen is connected to the end of the pipe 113.

In the activated sludge tank 2, the positions of the air diffuser member 111 and the oxygen supply member 112 are not particularly limited. However, from the viewpoint of efficiently supplying oxygen to the water 3 to be treated inside the activated sludge tank 2, it is preferably provided near the center of the activated sludge tank 2 in a plan view.

[First organic matter concentration measuring section]
The liquid treatment system A includes a first organic substance concentration measuring unit 220 that measures the concentration of organic substances in the water to be treated 3 flowing into the activated sludge tank 2. The first organic matter concentration measuring unit 220 can be provided in the connecting pipe 4 between the microbial fuel cell tank 1 and the activated sludge tank 2, as shown in FIGS. 1 and 2. Then, it is preferable that the first organic matter concentration measuring unit 220 continuously or intermittently measure the concentration of organic matter in the treated water 3 flowing into the activated sludge tank 2. The configuration of the first organic substance concentration measuring unit 220 is not particularly limited as long as the concentration of organic substances in the water to be treated 3 can be measured, but for example, a UV type organic substance meter can be used. The UV type organic substance meter is a device for measuring the concentration of organic substances in the water to be treated 3 by means of ultraviolet absorbance. The first organic substance concentration measuring unit 220 is electrically connected to the control unit 210 described later and has a function of transmitting the measured organic substance concentration to the control unit 210.

[Control part]
The liquid processing system A includes a control unit 210 that controls the oxygen supply unit 200. As shown in FIGS. 1 and 2, the control unit 210 is electrically connected to the oxygen supply unit 200 provided in the activated sludge tank 2 and controls the operating state of the oxygen supply unit 200. The control unit 210 is also electrically connected to the first organic substance concentration measuring unit 220 and receives the organic substance concentration measured by the first organic substance concentration measuring unit 220. The control unit 210 includes at least one selected from the group consisting of CPU, RAM, ROM, and hard disk.

Next, the operation of the liquid processing system A of this embodiment will be described. First, the water to be treated 3 containing organic matter is fed into the microbial fuel cell tank 1 and the activated sludge tank 2. Then, as shown in FIGS. 1 and 2, the electrode cassette 100 including the positive electrode 10 and the negative electrode 20 is immersed in the water 3 to be treated. In this case, the gas diffusion layer 12 of the positive electrode 10 and the negative electrode 20 are immersed in the water 3 to be treated, and at least a part of the water repellent layer 11 is exposed to the gas phase G.

During operation of the liquid treatment system A, the water to be treated 3 is continuously supplied to the negative electrode 20 and the air is supplied to the positive electrode 10 through the inflow port 5 of the microbial fuel cell tank 1. At this time, the air is continuously supplied through the opening provided in the upper portion of the spacer member 50.

Then, in the positive electrode 10, oxygen permeates the water repellent layer 11 and diffuses into the gas diffusion layer 12. In the negative electrode 20, hydrogen ions and electrons are generated from organic substances in the water 3 to be treated by the catalytic action of microorganisms. The hydrogen ions generated in the negative electrode 20 move to the positive electrode 10 side and reach the gas diffusion layer 12 in the positive electrode 10. As shown in FIG. 2, when the electrode cassette 100 has the ion transfer layer 30, the hydrogen ions generated in the negative electrode 20 pass through the ion transfer layer 30 and move to the positive electrode 10 side, and the gas in the positive electrode 10 moves. It reaches the diffusion layer 12. Further, the generated electrons move to the external circuit 60 through the conductor sheet of the negative electrode 20, and further move from the external circuit 60 to the gas diffusion layer 12 of the positive electrode 10. Then, the hydrogen ions and the electrons are combined with oxygen by the action of the catalyst in the gas diffusion layer 12 and consumed as water. At this time, the external circuit 60 recovers the electric energy flowing in the closed circuit. In this way, the electrode cassette 100 can decompose the organic matter in the water 3 to be treated by the action of the microorganisms on the negative electrode 20.

The water 3 to be treated, which has been treated by the electrode cassette 100 of the microbial fuel cell tank 1, continuously moves into the activated sludge tank 2 through the connecting pipe 4. The treated water 3 sent into the activated sludge tank 2 is further purified by the aerobic microorganisms retained in the treated water 3 inside the activated sludge tank 2. Specifically, the oxygen supply unit 200 is operating in the activated sludge tank 2, and the air is continuously or intermittently supplied to the water to be treated 3 inside the activated sludge tank 2. Therefore, the aerobic respiration of aerobic microorganisms oxidizes and decomposes the organic matter remaining in the water 3 to be treated. The aerobic microorganisms retained in the water to be treated 3 in the activated sludge tank 2 are microorganisms having a metabolic mechanism based on oxygen and are not particularly limited as long as they can decompose organic substances in the water to be treated 3. Examples of the aerobic microorganism include Escherichia bacterium, Escherichia coli, Pseudomonas bacterium, Pseudomonas aeruginosa, and Bacillus bacterium, Bacillus subtilis.

The water 3 to be treated which has been treated in the microbial fuel cell tank 1 and the activated sludge tank 2 has a greatly reduced concentration of organic substances and is discharged to the outside from the outlet 6 of the activated sludge tank 2.

Here, in the liquid processing system A, the control unit 210 supplies the water to be treated 3 from the oxygen supply unit 200 according to the concentration of the organic substance in the water to be treated 3 measured by the first organic substance concentration measuring unit 220. Control is performed to adjust the amount of oxygen to be generated. That is, the control unit 210 increases the amount of oxygen supplied from the oxygen supply unit 200 to the treated water 3 when the concentration of the organic matter in the treated water 3 flowing into the activated sludge tank 2 is higher than usual. Then, control is performed to increase the organic matter treatment capacity of the activated sludge tank 2. On the contrary, when the concentration of organic substances in the treated water 3 flowing into the activated sludge tank 2 is lower than usual, the control unit 210 controls the amount of oxygen supplied from the oxygen supply unit 200 to the treated water 3. Control is performed to reduce the organic matter treatment capacity of the activated sludge tank 2.

Specifically, the control unit 210 is electrically connected to the first organic substance concentration measuring unit 220 and receives the organic substance concentration measured by the first organic substance concentration measuring unit 220. The control unit 210 includes a storage unit, and the storage unit stores a normal operation range corresponding to the concentration of organic substances in the treated water 3 flowing into the activated sludge tank 2. The normal operation range is a range of the organic substance concentration in which the oxygen supply unit 200 normally operates, and in the normal operation, a predetermined amount of oxygen is supplied to the water 3 to be treated. The upper limit value and the lower limit value of the normal operation range can be appropriately set according to the treatment capacity of the activated sludge tank 2.

When such a liquid treatment system A operates, the oxygen supply unit 200 performs a normal operation and supplies a predetermined amount of oxygen to the water 3 to be treated. The first organic matter concentration measuring unit 220 continuously or intermittently measures the concentration of organic matter in the water to be treated 3 flowing into the activated sludge tank 2. The first organic substance concentration measuring unit 220 transmits the measured organic substance concentration to the control unit 210. As shown in FIG. 4, the control unit 210 that has received the measurement result compares the concentration of the organic matter in the water to be treated 3 with the normal operation range stored in the storage unit, and the concentration of the organic matter is within the normal operation range. It is determined whether there is any (step S1). When the concentration of organic substances in the water 3 to be treated is within the normal operation range, the oxygen supply unit 200 continues the normal operation.

When the concentration of the organic substance in the water to be treated 3 is outside the normal operating range, the control unit 210 compares the concentration of the organic substance with the upper limit value and the lower limit value of the normal operating range (step S2).

When the concentration of the organic substance in the treated water 3 exceeds the upper limit value of the normal operation range, it is determined that the concentration of the organic substance is higher than usual, and the oxygen supplied from the oxygen supply unit 200 to the treated water 3 is increased. The control is performed to increase the amount of the above compared to that during normal operation (step S3). Specifically, the control unit 210 is electrically connected to the compressor 114 of the oxygen supply unit 200, and sends a command to the compressor 114 to increase the amount of air to be pressure-fed as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 becomes larger than in the normal operation, so that the aerobic microorganisms are activated and the oxidative decomposition of the organic matter can be promoted.

On the contrary, in step S2, when the concentration of the organic matter in the treated water 3 is lower than the lower limit value of the normal operation range, it is determined that the concentration of the organic matter is lower than usual, and the oxygen supply unit 200 determines that the treated water 3 The control is performed to reduce the amount of oxygen supplied to the valve from that during normal operation (step S4). Specifically, the control unit 210 transmits a command to the compressor 114 to reduce the amount of air to be pressure-fed as compared with that during normal operation. When the concentration of organic substances in the water to be treated 3 is lower than usual, sufficiently purified water is discharged to the outside even if the treatment capacity of the activated sludge tank 2 is lowered. Then, since the amount of oxygen supplied to the water to be treated 3 is smaller than that during normal operation, it is possible to reduce the electric power for operating the compressor 114.

As described above, the liquid treatment system A of the present embodiment includes the negative electrode 20 that holds the anaerobic microorganisms and is in contact with the water to be treated 3 containing the organic matter, and the positive electrode 10 electrically connected to the negative electrode 20. A microbial fuel cell tank 1 having the same is provided. The liquid treatment system A further includes an activated sludge tank 2 that is provided on the downstream side of the microbial fuel cell tank 1 and has an oxygen supply unit 200 that supplies oxygen to the water 3 to be treated. The liquid treatment system A is further provided on the downstream side of the microbial fuel cell tank 1 and has a first organic matter concentration measuring unit 220 for measuring the concentration of organic matter in the water to be treated 3 flowing into the activated sludge tank 2 and oxygen. And a control unit 210 that controls the supply unit 200. The control unit 210 performs control for adjusting the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 according to the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. In this way, even when the concentration of organic substances in the water to be treated 3 increases and the amount of organic substances to be removed increases, the amount of oxygen supplied to the water to be treated 3 is appropriately adjusted to treat the discharged water. It is possible to maintain high water quality.

The control unit 210 increases the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the organic substance concentration measured by the first organic substance concentration measuring unit 220 exceeds the normal operating range. It is preferable to perform control. Further, the control unit 210 controls the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the concentration of the organic substance measured by the first organic substance concentration measuring unit 220 is below the normal operating range. Is preferably performed. As described above, the load of the oxygen supply unit 200 is reduced and the energy consumption in the oxygen supply unit 200 is reduced by increasing the oxygen supply amount when the organic substance concentration increases and decreasing the oxygen supply amount when the organic substance concentration decreases. Can be suppressed.

[Second embodiment]
Next, a liquid treatment system according to the second embodiment will be described in detail with reference to the drawings. The same components as those in the first embodiment are designated by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 5, the liquid treatment system B of the present embodiment is arranged in a microbial fuel cell tank 1 having an electrode cassette 100 and a downstream side of the microbial fuel cell tank 1, as in the first embodiment. The activated sludge tank 2 having the oxygen supply unit 200 is provided. The liquid treatment system B further includes a first organic substance concentration measuring unit 220 that measures the concentration of organic substances in the treated water 3 that flows into the activated sludge tank 2, and a control unit 210 that controls the oxygen supply unit 200. ing. The control unit 210 is electrically connected to the first organic substance concentration measurement unit 220 and the oxygen supply unit 200.

The liquid processing system B further includes an external circuit 60 electrically connected to the positive electrode 10 and the negative electrode 20. Then, the external circuit 60 collects the electric energy generated between the positive electrode 10 and the negative electrode 20. As shown in FIG. 5, the external circuit 60 is electrically connected to the control unit 210. The external circuit 60 has a function of measuring at least one of a current value and a voltage value between the positive electrode 10 and the negative electrode 20 and transmitting the measurement result to the control unit 210.

In the liquid processing system B of the present embodiment as well, as in the first embodiment, the control unit 210 controls the water to be treated from the oxygen supply unit 200 in accordance with the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. The control for adjusting the amount of oxygen supplied to No. 3 is performed. Specifically, the control unit 210 supplies the oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the organic substance concentration measured by the first organic substance concentration measuring unit 220 exceeds the normal operating range. The control is performed so that the amount of is larger than that during normal operation. In addition, the control unit 210 normally operates the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the concentration of the organic matter measured by the first organic matter concentration measuring unit 220 falls below the normal operation range. Control to reduce the time.

Here, when the concentration of organic substances in the water to be treated 3 fed into the microbial fuel cell tank 1 increases, the amount of organic substances decomposed in the negative electrode 20 increases, so that the current value measured by the external circuit 60 and The voltage value also increases. However, since the amount of organic matter that can be decomposed by the electrode cassette 100 is limited, when the concentration of organic matter in the water to be treated 3 fed into the microbial fuel cell tank 1 increases, the microbial fuel cell tank 1 The amount of organic substances that cannot be completely treated by the method increases. Since the organic matter concentration measured by the first organic matter concentration measuring unit 220 also increases, it is necessary to enhance the treatment capacity of the activated sludge tank 2.

Therefore, the liquid treatment system B of the present embodiment supplies the water to be treated 3 from the oxygen supply unit 200 according to at least one of the current value and the voltage value between the positive electrode 10 and the negative electrode 20 measured by the external circuit 60. Control is performed to adjust the amount of oxygen to be generated. Specifically, as described above, the control unit 210 is electrically connected to the external circuit 60 and receives the current value and/or voltage value measured by the external circuit 60. The control unit 210 includes a storage unit, and the storage unit stores a normal operation range corresponding to the current value and/or the voltage value. The normal operation range is a range of current value and voltage value in which the oxygen supply unit 200 performs normal operation, and in the normal operation, a predetermined amount of oxygen is supplied to the water to be treated 3. The upper limit value and the lower limit value of the normal operation range can be appropriately set according to the treatment capacity of the activated sludge tank 2.

Then, when such a liquid treatment system B operates, the oxygen supply unit 200 performs a normal operation and supplies a predetermined amount of oxygen to the water to be treated 3. The external circuit 60 measures the current value and/or the voltage value continuously or intermittently. The external circuit 60 transmits the measured current value and/or voltage value to the control unit 210. As shown in FIG. 6, the control unit 210 having received the measurement result compares the current value and/or the voltage value with the normal operation range stored in the storage unit, and the current value and/or the voltage value is in the normal operation range. It is determined whether or not it is within (step S1). When the current value and/or the voltage value is within the normal operation range, the oxygen supply unit 200 continues the normal operation.

When the current value and/or the voltage value is outside the normal operation range, the control unit 210 compares the concentration of the organic substance with the upper limit value and the lower limit value of the normal operation range (step S2). When the current value and/or voltage value exceeds the upper limit value of the normal operating range, it is determined that the concentration of organic substances is higher than normal, and the amount of oxygen supplied from the oxygen supply unit 200 to the water 3 to be treated. Is controlled to be higher than that during normal operation (step S3). Specifically, the control unit 210 is electrically connected to the compressor 114 of the oxygen supply unit 200, and sends a command to the compressor 114 to increase the amount of air to be pressure-fed as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 becomes larger than in the normal operation, so that the aerobic microorganisms are activated and the oxidative decomposition of the organic matter can be promoted.

On the contrary, in step S2, when the current value and/or the voltage value is lower than the lower limit value of the normal operation range, it is determined that the concentration of the organic matter is lower than usual, and the oxygen supply unit 200 supplies the water 3 to be treated. Control is performed to reduce the amount of oxygen to be generated as compared with that during normal operation (step S4). Specifically, the control unit 210 transmits a command to the compressor 114 to reduce the amount of air to be pressure-fed as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 is smaller than that during normal operation, so that the electric power for operating the compressor 114 can be reduced.

As described above, the liquid treatment system B of the present embodiment further includes the external circuit 60 that measures at least one of the current value and the voltage value between the positive electrode 10 and the negative electrode 20. Then, the control unit 210 performs control for adjusting the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 according to at least one of the current value and the voltage value between the positive electrode 10 and the negative electrode 20. .. Thereby, even when the organic substance concentration in the water to be treated 3 increases, based on the concentration of the organic substance measured by the first organic substance concentration measuring unit 220 and the current value and/or voltage value measured by the external circuit 60, The amount of oxygen supplied to the water to be treated 3 can be adjusted appropriately. Therefore, the treated water quality of the water discharged from the liquid treatment system B can be maintained high.

In the liquid treatment system B, the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 is adjusted according to at least one of the current value and the voltage value measured by the external circuit 60. However, the present embodiment is not limited to such an aspect, and adjusts the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 based on the cathode potential of the positive electrode 10 and/or the anode potential of the negative electrode 20. You may.

When the concentration of organic substances in the water to be treated 3 fed into the microbial fuel cell tank 1 increases, the amount of organic substances decomposed in the negative electrode 20 increases, so that the anode potential of the negative electrode 20 shifts to a negative value. When the anode potential is negatively shifted, the cathode potential of the positive electrode 10 electrically connected to the negative electrode 20 is positively shifted. On the contrary, when the concentration of organic substances in the water to be treated 3 fed into the microbial fuel cell tank 1 decreases, the amount of organic substances decomposed in the negative electrode 20 decreases, so the anode potential at the negative electrode 20 shifts to the positive. .. When the anode potential shifts to the positive, the cathode potential at the positive electrode 10 shifts to the negative. Therefore, control may be performed to adjust the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 in accordance with the cathode potential of the positive electrode 10 and/or the anode potential of the negative electrode 20. The cathode potential on the positive electrode 10 and the anode potential on the negative electrode 20 can be measured using an electrometer. The electrometer is equipped with a reference electrode such as a silver-silver chloride electrode. By immersing the reference electrode in the water 3 to be treated and using the positive electrode 10 and the negative electrode 20 as working electrodes, the potentials of the positive electrode 10 and the negative electrode 20 are changed. Can be measured.

[Third embodiment]
Next, a liquid processing system according to the third embodiment will be described in detail with reference to the drawings. The same components as those in the first and second embodiments are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 7, the liquid treatment system C of the present embodiment is, as in the first embodiment, arranged with a microbial fuel cell tank 1 having an electrode cassette 100 and a downstream side of the microbial fuel cell tank 1, The activated sludge tank 2 having the oxygen supply unit 200 is provided. The liquid treatment system C further includes a first organic substance concentration measuring unit 220 that measures the concentration of organic substances in the treated water 3 that flows into the activated sludge tank 2, and a control unit 210 that controls the oxygen supply unit 200. ing.

The liquid treatment system C of the present embodiment is different from the liquid treatment system A of the first embodiment in that the second organic matter concentration measuring unit 221 provided on the upstream side of the microbial fuel cell tank 1 and the activated sludge tank 2 are provided. It further includes a third organic substance concentration measuring unit 222 provided on the downstream side.

Specifically, the second organic matter concentration measuring unit 221 can be provided at the inflow port 5 of the microbial fuel cell tank 1. The second organic matter concentration measuring unit 221 measures the concentration of organic matter in the water to be treated 3 flowing into the microbial fuel cell tank 1 continuously or intermittently. Further, the third organic matter concentration measuring unit 222 can be provided at the outflow port 6 of the activated sludge tank 2. The third organic substance concentration measuring unit 222 measures the concentration of organic substances in the water to be treated 3 discharged from the activated sludge tank 2 continuously or intermittently. The configurations of the second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222 are not particularly limited as long as the concentration of organic substances in the water to be treated 3 can be measured. For example, a UV type organic substance meter can be used. .. The second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222 are electrically connected to the control unit 210 and have a function of transmitting the measured organic substance concentration to the control unit 210.

In the liquid treatment system C of the present embodiment as well, as in the first embodiment, the control unit 210 controls the water to be treated from the oxygen supply unit 200 according to the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. The control for adjusting the amount of oxygen supplied to No. 3 is performed. Specifically, the control unit 210 supplies the oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the organic substance concentration measured by the first organic substance concentration measuring unit 220 exceeds the normal operating range. The control is performed so that the amount of is larger than that during normal operation. In addition, the control unit 210 normally operates the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the concentration of the organic matter measured by the first organic matter concentration measuring unit 220 falls below the normal operation range. Control to reduce the time.

Here, when the organic matter concentration in the water to be treated 3 fed into the microbial fuel cell tank 1 is higher than usual, it is necessary to enhance the treatment capacity of either the microbial fuel cell tank 1 or the activated sludge tank 2. is there. However, in the microbial fuel cell tank 1, it is difficult to immediately improve the treatment capacity of the microbial fuel cell tank 1 because the organic substances are decomposed by the anaerobic microorganisms carried on the negative electrode 20. Further, when the concentration of organic substances in the water to be treated 3 discharged from the activated sludge tank 2 is higher than usual, the treatment in the liquid treatment system C is insufficient, so the microbial fuel cell tank 1 and the activated sludge tank It is necessary to increase the processing capacity of either one of the two. However, as described above, it is difficult to immediately increase the treatment capacity of the microbial fuel cell tank 1.

Therefore, the liquid treatment system C of the present embodiment supplies the water to be treated from the oxygen supply unit according to the concentration of the organic substance measured by at least one of the second organic substance concentration measuring unit and the third organic substance concentration measuring unit. Control is performed to adjust the amount of oxygen to be generated. Specifically, as described above, the control unit 210 is electrically connected to the second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222, and the measured organic substance concentration is transmitted to the control unit 210. It has a function to send. The control unit 210 receives the organic substance concentrations measured by the second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222. The control unit 210 includes a storage unit, and the storage unit stores a predetermined value corresponding to the second organic substance concentration measuring unit 221 and a predetermined value corresponding to the third organic substance concentration measuring unit 222. ing.

Then, when such a liquid treatment system C is operated, the second organic matter concentration measuring unit 221 continuously or intermittently measures the concentration of the organic matter in the treated water 3 flowing into the microbial fuel cell tank 1. .. The third organic substance concentration measuring unit 222 measures the concentration of organic substances in the water to be treated 3 discharged from the activated sludge tank 2 continuously or intermittently. The second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222 transmit the measured organic substance concentration to the control unit 210.

Upon receiving the measurement result by the second organic substance concentration measuring unit 221, the control unit 210 compares the measured value with a predetermined value corresponding to the second organic substance concentration measuring unit 221. When the measured value exceeds a predetermined value, it is determined that the concentration of organic substances in the water to be treated 3 fed into the microbial fuel cell tank 1 is higher than usual, and the oxygen supply unit 200 causes the water to be treated 3 to be treated. The control is performed to increase the amount of oxygen supplied to the engine from that during normal operation. Specifically, the control unit 210 is electrically connected to the compressor 114 of the oxygen supply unit 200, and sends a command to the compressor 114 to increase the amount of air to be pressure-fed as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 becomes larger than in the normal operation, so that the aerobic microorganisms are activated and the oxidative decomposition of the organic matter can be promoted.

Similarly, the control unit 210 that has received the measurement result by the third organic substance concentration measuring unit 222 compares the measured value with a predetermined value corresponding to the third organic substance concentration measuring unit 222. When the measured value exceeds the predetermined value corresponding to the third organic matter concentration measuring unit 222, it is determined that the treatment of the organic matter in the microbial fuel cell tank 1 and the activated sludge tank 2 is insufficient, and oxygen supply Control is performed to increase the amount of oxygen supplied from the part 200 to the water to be treated 3 as compared with that during normal operation. Specifically, the control unit 210 is electrically connected to the compressor 114 of the oxygen supply unit 200, and sends a command to the compressor 114 to increase the amount of air to be pressure-fed as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 becomes larger than in the normal operation, so that the aerobic microorganisms are activated and the oxidative decomposition of the organic matter can be promoted.

As described above, the liquid treatment system C of the present embodiment has the second organic matter concentration measuring unit 221 provided on the upstream side of the microbial fuel cell tank 1 and the third organic matter concentration provided on the downstream side of the activated sludge tank 2. And a measuring unit 222. The second organic matter concentration measuring unit 221 measures the concentration of organic matter in the water to be treated 3 flowing into the microbial fuel cell tank 1. The third organic matter concentration measuring unit 222 measures the concentration of organic matter in the treated water 3 flowing out from the activated sludge tank 2. The control unit 210 responds to the concentration of the organic substance measured by the first organic substance concentration measuring unit and the concentration of the organic substance measured by at least one of the second organic substance concentration measuring unit and the third organic substance concentration measuring unit. , Control for adjusting the amount of oxygen supplied from the oxygen supply unit to the water to be treated. In addition, the control unit controls the oxygen supply unit 200 to perform the process when the concentration of the organic substance measured by at least one of the second organic substance concentration measuring unit 221 and the third organic substance concentration measuring unit 222 exceeds a predetermined value. It is preferable to perform control to increase the amount of oxygen supplied to the water 3. As a result, even if the concentration of organic matter in the water to be treated 3 fed into the microbial fuel cell tank 1 is higher than usual, the organic matter can be oxidatively decomposed by the activated sludge tank 2, so that the liquid treatment system C It becomes possible to maintain high quality of treated water discharged. Further, even when the concentration of organic substances in the water to be treated 3 discharged from the activated sludge tank 2 is higher than usual, the treatment capacity of the activated sludge tank 2 can be immediately increased, so that the water is discharged from the liquid treatment system C. It is possible to maintain high quality of treated water.

As described above, the liquid treatment system of the present embodiment includes the microbial fuel cell tank 1, the activated sludge tank 2, the first organic matter concentration measuring unit 220, and the control unit 210 that controls the oxygen supply unit 200. ing. However, the liquid processing system may be configured to include only the second organic substance concentration measuring unit 221 as the organic substance concentration measuring unit. The liquid processing system may be configured to include only the third organic substance concentration measuring unit 222 as the organic substance concentration measuring unit. The liquid processing system may be configured to include only the first organic substance concentration measuring unit 220 and the second organic substance concentration measuring unit as the organic substance concentration measuring unit. The liquid processing system may be configured to include only the first organic substance concentration measuring unit 220 and the third organic substance concentration measuring unit 222 as the organic substance concentration measuring unit. The liquid processing system may be configured to include only the second organic substance concentration measuring unit and the third organic substance concentration measuring unit 222 as the organic substance concentration measuring unit. Then, the control unit 210, according to the concentration of the organic substance measured by at least one selected from the group consisting of the first organic substance concentration measuring unit, the second organic substance concentration measuring unit and the third organic substance concentration measuring unit, Control may be performed to adjust the amount of oxygen supplied from the oxygen supply unit to the water to be treated. Even with these configurations, the treated water quality of the discharged water can be maintained high when the concentration of organic substances in the treated water rises.

[Fourth Embodiment]
Next, a liquid treatment system according to the fourth embodiment will be described in detail with reference to the drawings. The same components as those in the first embodiment to the third embodiment are designated by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 8, the liquid treatment system D of the present embodiment is, as in the first embodiment, arranged with a microbial fuel cell tank 1 having an electrode cassette 100 and a downstream side of the microbial fuel cell tank 1, The activated sludge tank 2 having the oxygen supply unit 200 is provided. The liquid treatment system D further includes a first organic substance concentration measuring unit 220 that measures the concentration of organic substances in the treated water 3 that flows into the activated sludge tank 2, and a control unit 210 that controls the oxygen supply unit 200. ing.

The liquid treatment system D of the present embodiment is different from the liquid treatment system A of the first embodiment in that the first flow rate adjusting unit 230 provided on the upstream side of the microbial fuel cell tank 1, the microbial fuel cell tank 1 and the active A second flow rate adjusting unit 231 provided between the sludge tank 2 and the sludge tank 2 is further provided. The first flow rate adjusting unit 230 adjusts the flow rate of the water to be treated 3 flowing into the microbial fuel cell tank 1. Further, the second flow rate adjusting unit 231 adjusts the flow rate of the treated water 3 flowing into the activated sludge tank 2. The first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are electrically connected to the control unit 210, and control for increasing or decreasing the flow rate of the treated water 3 based on a command from the control unit 210. I do. The configurations of the first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are not particularly limited, but for example, an electric valve or a solenoid valve can be used.

In the liquid treatment system D of the present embodiment as well, similar to the first embodiment, the control unit 210 controls the water to be treated from the oxygen supply unit 200 according to the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. The control for adjusting the amount of oxygen supplied to No. 3 is performed. Specifically, the control unit 210 supplies the oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the organic substance concentration measured by the first organic substance concentration measuring unit 220 exceeds the normal operating range. The control is performed so that the amount of is larger than that during normal operation. In addition, the control unit 210 normally operates the amount of oxygen supplied from the oxygen supply unit 200 to the water to be treated 3 when the concentration of the organic matter measured by the first organic matter concentration measuring unit 220 falls below the normal operation range. Control to reduce the time.

Here, when the flow rate of the treated water 3 flowing into the activated sludge tank 2 decreases, the treated water 3 stays in the activated sludge tank 2 for a longer time. The longer residence time increases the contact between the organic matter in the water to be treated 3 and the aerobic microorganisms, so that the organic matter can be efficiently oxidatively decomposed by the aerobic microorganisms.

Therefore, the liquid processing system D of the present embodiment uses the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 according to the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. Control is performed to adjust the flow rate of the treated water 3 flowing into the activated sludge tank 2. Specifically, when the liquid treatment system D operates, the oxygen supply unit 200 performs a normal operation and supplies a predetermined amount of oxygen to the water to be treated 3. In addition, the first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are also in an open state, and a predetermined amount of water to be treated 3 flows. The first organic matter concentration measuring unit 220 continuously or intermittently measures the concentration of organic matter in the water to be treated 3 flowing into the activated sludge tank 2. The first organic substance concentration measuring unit 220 transmits the measured organic substance concentration to the control unit 210. As shown in FIG. 9, the control unit 210 that has received the measurement result compares the concentration of the organic matter in the water to be treated 3 with the normal operating range stored in the storage unit, and confirms that the concentration of the organic matter is within the normal operating range. It is determined whether there is any (step S1). When the concentration of the organic matter in the water to be treated 3 is within the normal operation range, the oxygen supply unit 200 continues the normal operation, and the first flow rate adjustment unit 230 and the second flow rate adjustment unit 231 are also in the open state. maintain.

When the concentration of the organic substance in the water to be treated 3 is outside the normal operating range, the control unit 210 compares the concentration of the organic substance with the upper limit value and the lower limit value of the normal operating range (step S2).

When the concentration of the organic substance in the treated water 3 exceeds the upper limit value of the normal operation range, it is determined that the concentration of the organic substance is higher than usual, and the oxygen supplied from the oxygen supply unit 200 to the treated water 3 is increased. The control is performed to increase the amount of than that during normal operation. Further, the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 controls to reduce the flow rate of the treated water 3 flowing into the activated sludge tank 2 (step S3). Specifically, the control unit 210 sends a command to the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 to reduce the flow rate of the water to be treated 3 as compared with that during normal operation. As a result, the amount of oxygen supplied to the water to be treated 3 in the activated sludge tank 2 becomes larger than in the normal operation, so that the aerobic microorganisms are activated and the oxidative decomposition of the organic matter can be promoted. Further, since the inflow amount of the treated water 3 into the activated sludge tank 2 is reduced and the residence time of the treated water 3 is prolonged, the contact between the organic matter in the treated water 3 and the aerobic microorganisms is increased. Therefore, it becomes possible to efficiently oxidize and decompose organic substances.

On the contrary, in step S2, when the concentration of the organic matter in the treated water 3 is lower than the lower limit value of the normal operation range, it is determined that the concentration of the organic matter is lower than usual, and the oxygen supply unit 200 determines that the treated water 3 The amount of oxygen supplied to the control unit is controlled to be smaller than that during normal operation. Further, the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 controls to increase the flow rate of the treated water 3 flowing into the activated sludge tank 2 (step S4). Specifically, the control unit 210 sends a command to the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 to increase the flow rate of the water to be treated 3 as compared with that during normal operation. When the concentration of organic substances in the water to be treated 3 is lower than usual, sufficiently purified water is discharged even if the flow rate of the water to be treated 3 flowing into the activated sludge tank 2 is increased. Therefore, it becomes possible to increase the treatment amount of the water 3 to be treated by the liquid treatment system D. Further, when the amount of oxygen supplied to the water 3 to be treated in the activated sludge tank 2 is smaller than that during normal operation, it is possible to reduce the electric power for operating the compressor 114.

As described above, the liquid treatment system D of the present embodiment is provided on the upstream side of the microbial fuel cell tank 1 and at least one of the microbial fuel cell tank 1 and the activated sludge tank 2, and controls the flow rate of the water to be treated. The flow rate adjusting unit 230, 231 for adjusting is further provided. Then, the control unit 210 adjusts the flow rate of the treated water 3 flowing into the activated sludge tank 2 by the flow rate adjusting units 230 and 231 according to the concentration of the organic substance measured by the first organic substance concentration measuring unit 220. Take control. Further, the control unit 210 controls the flow rate adjusting units 230 and 231 to reduce the flow rate of the water to be treated 3 when the concentration of the organic matter measured by the first organic matter concentration measuring section 220 exceeds the normal operation range. Is preferably performed. With such a configuration, when the organic matter concentration of the treated water 3 is high, the inflow amount of the treated water 3 into the activated sludge tank 2 is decreased, and the retention time of the treated water 3 is lengthened. Therefore, the contact between the organic matter in the water to be treated 3 and the aerobic microorganism is enhanced, and the organic matter can be efficiently oxidatively decomposed. In addition, the control unit 210 controls the flow rate adjusting units 230 and 231 to increase the flow rate of the water to be treated 3 when the organic matter concentration measured by the first organic matter concentration measuring unit 220 falls below the normal operating range. It is preferable. This makes it possible to increase the treatment amount of the water to be treated 3 by the liquid treatment system D.

[Fifth Embodiment]
Next, a liquid treatment system according to the fifth embodiment will be described in detail with reference to the drawings. The same components as those in the first to fourth embodiments will be designated by the same reference numerals, and overlapping description will be omitted.

The liquid treatment system of the present embodiment is arranged in the microbial fuel cell tank 1 having the electrode cassette 100 and the downstream side of the microbial fuel cell tank 1, as in the fourth embodiment shown in FIG. And an activated sludge tank 2 having The liquid treatment system further includes a first organic substance concentration measuring unit 220 for measuring the concentration of organic substances in the treated water 3 flowing into the activated sludge tank 2, and a control unit 210.

Similar to the fourth embodiment, the liquid treatment system according to the present embodiment is provided between the first flow rate adjusting unit 230 provided on the upstream side of the microbial fuel cell tank 1 and the microbial fuel cell tank 1 and the activated sludge tank 2. And a second flow rate adjusting unit 231 provided in the. The first flow rate adjusting unit 230 adjusts the flow rate of the water to be treated 3 flowing into the microbial fuel cell tank 1. Further, the second flow rate adjusting unit 231 adjusts the flow rate of the treated water 3 flowing into the activated sludge tank 2. The first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are electrically connected to the control unit 210, and control for increasing or decreasing the flow rate of the treated water 3 based on a command from the control unit 210. I do. The configurations of the first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are not particularly limited, but for example, an electric valve or a solenoid valve can be used.

Here, as described above, when the flow rate of the treated water 3 flowing into the activated sludge tank 2 decreases, the treated water 3 stays in the activated sludge tank 2 for a longer time. The longer residence time increases the contact between the organic matter in the water to be treated 3 and the aerobic microorganisms, so that the organic matter can be efficiently oxidatively decomposed by the aerobic microorganisms.

Therefore, in the liquid treatment system of the present embodiment, depending on the concentration of the organic substance measured by the first organic substance concentration measuring unit 220, the first flow amount adjusting unit 230 and/or the second flow amount adjusting unit 231 activates the liquid. Control is performed to adjust the flow rate of the treated water 3 flowing into the sludge tank 2. Specifically, when the liquid treatment system operates, the oxygen supply unit 200 performs a normal operation and supplies a predetermined amount of oxygen to the water to be treated 3. In addition, the first flow rate adjusting unit 230 and the second flow rate adjusting unit 231 are also in an open state, and a predetermined amount of water to be treated 3 flows. The first organic matter concentration measuring unit 220 continuously or intermittently measures the concentration of organic matter in the water to be treated 3 flowing into the activated sludge tank 2. The first organic substance concentration measuring unit 220 transmits the measured organic substance concentration to the control unit 210. As shown in FIG. 10, the control unit 210 having received the measurement result compares the concentration of the organic matter in the water to be treated 3 with the normal operation range stored in the storage unit, and the concentration of the organic matter is within the normal operation range. It is determined whether there is any (step S1). When the concentration of the organic matter in the water to be treated 3 is within the normal operation range, the oxygen supply unit 200 continues the normal operation, and the first flow rate adjustment unit 230 and the second flow rate adjustment unit 231 are also in the open state. maintain.

When the concentration of the organic substance in the water to be treated 3 is outside the normal operating range, the control unit 210 compares the concentration of the organic substance with the upper limit value and the lower limit value of the normal operating range (step S2).

When the concentration of the organic matter in the water to be treated 3 exceeds the upper limit of the normal operating range, it is determined that the concentration of the organic matter is higher than usual, and the first and/or the second flow rate adjusting section activates the organic matter. Control is performed to reduce the flow rate of the treated water 3 flowing into the sludge tank 2. Specifically, the control unit 210 sends a command to the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 to reduce the flow rate of the water to be treated 3 from that during normal operation (step). S3). As a result, the inflow amount of the treated water 3 into the activated sludge tank 2 decreases and the residence time of the treated water 3 becomes long, so that the contact between the organic matter in the treated water 3 and the aerobic microorganisms is increased. It becomes possible to efficiently oxidize and decompose organic substances.

On the contrary, in step S2, when the concentration of the organic matter in the water to be treated 3 is lower than the lower limit value of the normal operating range, it is determined that the concentration of the organic matter is lower than usual, and the first and/or second flow rate The adjustment unit controls to increase the flow rate of the treated water 3 flowing into the activated sludge tank 2. Specifically, the control unit 210 sends a command to the first flow rate adjusting unit 230 and/or the second flow rate adjusting unit 231 to increase the flow rate of the water to be treated 3 as compared with that during normal operation (step). S4). When the concentration of organic substances in the water to be treated 3 is lower than usual, sufficiently purified water is discharged even if the flow rate of the water to be treated 3 flowing into the activated sludge tank 2 is increased. Therefore, it becomes possible to increase the treatment amount of the water 3 to be treated by the liquid treatment system.

As described above, the liquid treatment system of the present embodiment has the negative electrode 20 that holds the anaerobic microorganisms and is in contact with the water to be treated 3 containing the organic matter, and the positive electrode 10 that is electrically connected to the negative electrode 20. A microbial fuel cell tank 1 is provided. The liquid treatment system further includes an activated sludge tank 2 that is provided on the downstream side of the microbial fuel cell tank 1 and that has an oxygen supply unit 200 that supplies oxygen to the water to be treated 3. The liquid treatment system further includes a first organic substance concentration measuring unit 220 which is provided on the downstream side of the microbial fuel cell tank 1 and measures the concentration of organic substances in the water to be treated 3 flowing into the activated sludge tank 2. The liquid treatment system is further provided on the upstream side of the microbial fuel cell tank 1 and at least on one side between the microbial fuel cell tank 1 and the activated sludge tank 2, and a flow rate adjusting unit 230 for adjusting the flow rate of the water 3 to be treated. , 231 and a control unit 210 for controlling the flow rate adjusting units 230, 231. The control unit 210 controls the flow rate adjusting units 230 and 231 to adjust the flow rate of the treated water 3 flowing into the activated sludge tank 2 according to the concentration of the organic matter measured by the first organic matter concentration measuring unit 220. To do. In this way, even if the organic matter concentration in the treated water 3 rises and the amount of organic matter to be removed increases, it is discharged by appropriately adjusting the flow rate of the treated water 3 flowing into the activated sludge tank 2. It is possible to maintain high quality of treated water.

The control unit 210 controls the flow rate adjusting units 230 and 231 to reduce the flow rate of the water to be treated 3 when the organic matter concentration measured by the first organic matter concentration measuring unit 220 exceeds the normal operating range. It is preferable. With such a configuration, when the organic matter concentration of the treated water 3 is high, the inflow amount of the treated water 3 into the activated sludge tank 2 is decreased, and the retention time of the treated water 3 is lengthened. Therefore, the contact between the organic matter in the water to be treated 3 and the aerobic microorganism is enhanced, and the organic matter can be efficiently oxidatively decomposed. In addition, the control unit 210 controls the flow rate adjusting units 230 and 231 to increase the flow rate of the water to be treated 3 when the organic matter concentration measured by the first organic matter concentration measuring unit 220 falls below the normal operating range. It is preferable. This makes it possible to increase the treatment amount of the water to be treated 3 by the liquid treatment system D.

[Sixth Embodiment]
Next, a liquid treatment system according to the sixth embodiment will be described in detail with reference to the drawings. The same components as those in the first to fifth embodiments will be designated by the same reference numerals, and overlapping description will be omitted.

In the liquid processing system according to the first to fifth embodiments, the oxygen supply unit 200 includes an air diffuser 111, an oxygen supply member 112, a pipe 113, and an air diffuser 110 including a compressor 114. However, the oxygen supply unit 200 is not limited to such a configuration, and may have a configuration including, for example, the oxygen supply cassette 120 and the oxygen amount adjustment unit 130. The oxygen supply cassette 120 supplies oxygen to the water to be treated 3 that has moved to the activated sludge tank 2 and promotes aerobic respiration of aerobic microorganisms.

Specifically, as shown in FIGS. 11, 12, and 13, the oxygen supply cassette 120 is formed by stacking two water repellent layers 121 and a spacer member 122. As the water repellent layer 121 and the spacer member 122, the same ones as the water repellent layer 11 and the spacer member 50 in the electrode cassette 100 described above can be used. Then, as shown in FIG. 13, the side surface 122 a of the spacer member 122 is joined to the outer peripheral portion of the surface 121 a of the water repellent layer 121. Therefore, the water to be treated 3 held inside the activated sludge tank 2 is separated from the inside of the spacer member 122, and the water repellent layer 121 and the spacer member 122 form an internal space 140. Then, in the liquid processing system E, air is sent into the internal space 140 from the outside by the oxygen amount adjusting unit 130. Then, the air (oxygen) in the internal space 140 passes through the water repellent layer 121 and is supplied to the water to be treated 3.

In the oxygen supply cassette 120, aerobic microorganisms are carried on the surface of the water repellent layer 121 on the side of the water 3 to be treated. However, from the viewpoint of further promoting the decomposition of organic substances in the water to be treated 3, it is preferable that the water repellent layer 121 in the oxygen supply cassette 120 be overlaid with the holder 123 that holds aerobic microorganisms. Furthermore, the holding body 123 is preferably laminated on the surface of the water-repellent layer 121 on the side of the water to be treated 3. By using the holder 123, it becomes possible to efficiently grow the aerobic microorganisms in the holder 123 and promote the oxidative decomposition reaction of the aerobic microorganisms. Further, since the holder 123 is provided on the surface of the water repellent layer 121 having oxygen permeability, oxygen can be sufficiently supplied to the aerobic microorganisms through the water repellent layer 121.

As the holding body 123, for example, a non-woven fabric-like or sponge-like structure can be used. The holding body 123 can be made of, for example, one or more materials selected from the group consisting of polyethylene, polypropylene, polyethylene glycol, polyurethane, and polyvinyl alcohol.

An oxygen amount adjusting unit 130 that adjusts the amount of oxygen (air amount) sent into the internal space 140 is attached to the upper end of the oxygen supply cassette 120. The configuration of the oxygen amount adjusting unit 130 is not particularly limited as long as the amount of oxygen to the internal space 140 can be controlled. The oxygen amount adjusting unit 130 may have the configuration shown in FIG. 14, for example.

Specifically, as shown in FIG. 14A, the oxygen supply cassette 120 has an opening 141 that connects the internal space 140 and the external space. Further, the oxygen amount adjusting unit 130 has a lid 131 that opens and closes the opening 141. Then, the lid 131 is operated according to a command from the control unit 210. By operating the lid 131 to close the opening 141, the amount of oxygen supplied to the internal space 140 can be reduced. Further, by operating the lid 131 and opening the opening 141, air can flow into the internal space 140 and the amount of oxygen supplied to the internal space 140 can be increased.

As shown in FIG. 14B, the oxygen amount adjustment unit 130 can be a mechanism that changes the pressure of oxygen in the internal space 140. That is, the oxygen amount adjustment unit 130 includes a tank 132 in which oxygen (air) is stored, and a supply unit 133 that connects the tank 132 and the internal space 140 and supplies the oxygen in the tank 132 to the internal space 140. Then, the control unit 210 can control the supply unit 133 to adjust the oxygen supply amount from the tank 132 to the internal space 140. As the supply unit 133, a solenoid valve for compressed air or an electric valve can be used.

In addition, the oxygen amount adjusting unit 130 can be configured to include a blower 134 that supplies oxygen to the internal space 140, as shown in FIG. By controlling the blower 134 by the control unit 210, the flow rate of oxygen supplied to the internal space 140 can be changed and the oxygen supply amount can be adjusted.

As described above, the oxygen supply unit 200 of the liquid processing system is not limited to the air diffuser 110, and may be configured to use the oxygen supply cassette 120, for example.

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.

DESCRIPTION OF SYMBOLS 1 Microbial fuel cell tank 2 Activated sludge tank 3 Treated water 10 Positive electrode 20 Negative electrode 200 Oxygen supply section 210 Control section 220 First organic matter concentration measuring section 221 Second organic matter concentration measuring section 222 Third organic matter concentration measuring section 230, 231 Flow rate adjusting unit A, B, C, D, E Liquid processing system

Claims (11)

A microbial fuel cell tank, which holds an anaerobic microorganism, and comprises a negative electrode that comes into contact with water to be treated containing an organic matter, and a positive electrode electrically connected to the negative electrode,
An activated sludge tank provided on the downstream side of the microbial fuel cell tank, comprising an oxygen supply unit for supplying oxygen to the water to be treated,
Provided on the downstream side of the microbial fuel cell tank, a first organic matter concentration measuring unit for measuring the concentration of the organic matter in the treated water flowing into the activated sludge tank,
A control unit for controlling the oxygen supply unit,
Equipped with
The control unit performs control to adjust the amount of oxygen supplied from the oxygen supply unit to the water to be treated according to the concentration of the organic substance measured by the first organic substance concentration measurement unit, liquid treatment system. The control unit increases the amount of oxygen supplied from the oxygen supply unit to the water to be treated when the concentration of the organic substance measured by the first organic substance concentration measuring unit exceeds the normal operating range. The liquid treatment system according to claim 1, wherein the liquid treatment system is controlled. The control unit controls to reduce the amount of oxygen supplied from the oxygen supply unit to the water to be treated when the concentration of the organic substance measured by the first organic substance concentration measuring unit is lower than the normal operating range. The liquid processing system according to claim 1, which is performed. A second organic matter concentration measuring unit, which is provided on the upstream side of the microbial fuel cell tank and measures the concentration of the organic matter in the treated water flowing into the microbial fuel cell tank, and is provided on the downstream side of the activated sludge tank. And further comprising a third organic matter concentration measuring unit for measuring the concentration of the organic matter in the treated water flowing out from the activated sludge tank,
The control unit, the concentration of the organic matter measured by the first organic matter concentration measurement unit, the organic matter measured by at least one of the second organic matter concentration measurement unit and the third organic matter concentration measurement unit The liquid treatment system according to claim 1, wherein control is performed to adjust the amount of oxygen supplied from the oxygen supply unit to the water to be treated according to the concentration. The control unit, when the concentration of the organic substance measured by at least one of the second organic substance concentration measuring unit and the third organic substance concentration measuring unit exceeds a predetermined value, from the oxygen supply unit The liquid treatment system according to claim 4, which controls to increase the amount of oxygen supplied to the treated water. An upstream side of the microbial fuel cell tank, and at least one between the microbial fuel cell tank and the activated sludge tank, further comprising a flow rate adjusting unit for adjusting the flow rate of the water to be treated,
The control unit performs control to adjust the flow rate of the treated water flowing into the activated sludge tank by the flow rate adjusting unit according to the concentration of the organic matter measured by the first organic matter concentration measuring unit, The liquid processing system according to claim 1. The control unit performs control to reduce the flow rate of the water to be treated by the flow rate adjusting unit when the concentration of the organic matter measured by the first organic matter concentration measuring unit exceeds the normal operating range, The liquid processing system according to claim 6. The control unit performs control to increase the flow rate of the water to be treated by the flow rate adjusting unit when the concentration of the organic matter measured by the first organic matter concentration measuring unit falls below a normal operating range, The liquid processing system according to 6 or 7. 9. The liquid treatment system according to claim 1, further comprising an external circuit that measures at least one of a current value and a voltage value between the positive electrode and the negative electrode. The control unit performs control for adjusting the amount of oxygen supplied from the oxygen supply unit to the water to be treated according to at least one of a current value and a voltage value between the positive electrode and the negative electrode. Item 9. The liquid treatment system according to Item 9. A microbial fuel cell tank, which holds an anaerobic microorganism, and comprises a negative electrode that comes into contact with water to be treated containing an organic matter, and a positive electrode electrically connected to the negative electrode,
An activated sludge tank provided on the downstream side of the microbial fuel cell tank, comprising an oxygen supply unit for supplying oxygen to the water to be treated,
Provided on the downstream side of the microbial fuel cell tank, a first organic matter concentration measuring unit for measuring the concentration of the organic matter in the treated water flowing into the activated sludge tank,
An upstream side of the microbial fuel cell tank, and a flow rate adjusting unit provided in at least one of the microbial fuel cell tank and the activated sludge tank, for adjusting the flow rate of the treated water,
A control unit for controlling the flow rate adjusting unit,
Equipped with
The control unit performs control to adjust the flow rate of the treated water flowing into the activated sludge tank by the flow rate adjusting unit according to the concentration of the organic matter measured by the first organic matter concentration measuring unit, Liquid handling system.

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