JP2023120730A - Power generator and power generation method - Google Patents

Abstract

To provide a power generator capable of being used as a stable power supply source in the recovery and utilization of energy by electrode reaction using treated water after anaerobic treatment, and provide a power generation method.SOLUTION: There is provided a power generator which includes: a power generation unit that generates power through an electrode reaction using reducing substances in the treated water after anaerobic treatment as electron donors; and a control unit that controls the power generation unit to maintain the power generation output within the specified range. A power generation method using the power generator is also provided. With this, constant electrical energy can be obtained regardless of the properties of the treated water by maintaining the power generation output within the specified range. Accordingly, the power generator can be used as a stable power supply source.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a power generation device and a power generation method. More specifically, the present invention relates to a power generator and power generation method using treated water after anaerobic treatment.

Biological treatment using various microorganisms is generally known as a method for treating waste water containing organic matter. In particular, biological treatment in an anaerobic environment (hereafter referred to as "anaerobic treatment") is widely used due to its advantages such as no need for aeration power and almost no excess sludge. . In addition, various techniques using products generated in the process of wastewater treatment by anaerobic treatment are being studied. For example, as one of techniques for using products generated by anaerobic treatment, it is known to use biogas such as methane generated by anaerobic treatment as fuel to generate power.

On the other hand, a microbial fuel cell is known as a technology for generating electric power using oxidation-reduction reactions by microorganisms. A microbial fuel cell obtains electrical energy using the metabolic capacity of microorganisms. More specifically, a microbial fuel cell has a structure in which electrons generated in the process of oxidative decomposition of substrates such as organic substances by microorganisms are collected on the anode side and transferred to the cathode side to obtain current. is.

For example, in Patent Document 1, one of a pair of electrodes is used as an anode and is brought into contact with a solution (suspension) containing microorganisms that can grow under anaerobic conditions and an organic substance, and the other electrode is used as a cathode to create a structural void. A power generator is described which is formed of a material having a contact with air and which is electrically connected to the anode and the cathode to form a closed circuit. Patent document 1 also describes attaching microorganisms to the anode surface. Furthermore, Patent Document 1 also describes a power generation method in which this power generation device advances an oxidation reaction by microorganisms using an organic substance as an electron donor at the anode and a reduction reaction using oxygen as an electron acceptor at the cathode. It is

Japanese Patent Application Laid-Open No. 2004-342412

Power generation by a microbial fuel cell as described in Patent Document 1 has low energy conversion efficiency, and improvement of power generation output is a major issue for practical use. This is presumed to be due to the fact that since the microorganisms are brought into direct contact with or supported on the electrode, the transfer of substances to the electrode is inhibited by the microorganisms, and the metabolic rate of the microorganisms is rate-limiting.

Moreover, in recent years, in order to suppress the equipment driving power at the time of wastewater treatment and to achieve excellent energy saving, there is a demand for a technology that can efficiently recover and use energy as a technology accompanying wastewater treatment. As one of such technologies, a technology related to simultaneously performing wastewater treatment and power generation by applying a microbial fuel cell to wastewater treatment is being studied. There is a problem that is difficult.

As a technique for simply and efficiently recovering energy in wastewater treatment, it is conceivable to install electrodes on the wastewater treatment process and directly recover electrical energy through electrode reactions. In particular, the present inventors have already found that energy recovery (power generation) through electrode reactions becomes possible by using reducing substances (mainly hydrogen sulfide) generated during anaerobic treatment as electron donors. .

On the other hand, in the course of repeated studies, the present inventors found that when an electrode is provided on the anaerobic treatment process and an electrode reaction is performed, if the properties of the treated water after anaerobic treatment fluctuate depending on the anaerobic treatment status, the power output will be affected. Also, it has been found that there is a problem that it is difficult to stably use the recovered energy (electric power).

An object of the present invention is to provide a power generator and a power generation method that can be used as a stable power supply source in the recovery and utilization of energy by electrode reaction using treated water after anaerobic treatment.

As a result of intensive studies on the above-mentioned problems, the present inventors have found that stable supply of the generated energy is achieved by controlling the power generation output by the electrode reaction using the treated water after anaerobic treatment within a predetermined range.・The present invention was completed after discovering that it could be used.
That is, the present invention is the following power generator and power generation method.

The power generator of the present invention for solving the above problems is a power generation unit that generates power by an electrode reaction using a reducing substance in the treated water after anaerobic treatment as an electron donor, and a power generation output in the power generation unit within a predetermined range. and a control unit that controls to maintain at
The power generation device of the present invention generates power by directly using the reducing substance contained in the treated water after anaerobic treatment as an electron donor, so that there is no inhibition of substance transfer by microorganisms. Efficient power generation is possible compared to power generation. In addition, by maintaining the power generation output within a predetermined range, constant electrical energy can be obtained regardless of the properties of the treated water, and it becomes possible to use the water as a stable power supply source.

Moreover, as one embodiment of the power generator of the present invention, the control section has a feature of controlling the flow rate of the treated water supplied to the power generation section.
In the course of repeated studies, the inventors found that the flow rate of treated water affects the power output in power generation by electrode reaction using treated water after anaerobic treatment.
Therefore, according to this feature, by controlling the flow rate of the treated water supplied to the power generation unit, it becomes easy to maintain the power generation output within a predetermined range.

Moreover, as one embodiment of the power generator of the present invention, the control unit has a feature of controlling the concentration of reducing substances in the treated water after the anaerobic treatment.
In the course of repeated investigations, the inventors discovered that the concentration of reducing substances in the treated water affects the power output in power generation by electrode reaction using treated water after anaerobic treatment.
Therefore, according to this feature, it becomes easy to maintain the power generation output within a predetermined range by controlling the reducing substance concentration in the treated water supplied to the power generation unit.

Moreover, as one embodiment of the power generator of the present invention, it has a feature of providing a branch passage for supplying part of the treated water after anaerobic treatment to the power generation unit.
When further treatment is required for the treated water after anaerobic treatment, treated water is used to smoothly supply the treated water after anaerobic treatment to post-treatment and to stabilize the power output of the power generation device. It may be difficult to simultaneously control the flow rate of
On the other hand, according to this feature, not all the treated water after anaerobic treatment is supplied to the power generation unit, but a part of the treated water is supplied to the power generation unit, so that the treated water after anaerobic treatment can be smoothly applied to the post-treatment. It is possible to easily control the power generation output of the power generation device.

Further, as a power generation method of the present invention for solving the above problems, a power generation step of generating power by an electrode reaction using a reducing substance in the treated water after anaerobic treatment as an electron donor, and a power generation output in the power generation step and a control step for controlling to maintain within the range of
In the power generation method of the present invention, the reducing substance contained in the treated water after anaerobic treatment is directly used as an electron donor to generate power, so that there is no inhibition of mass transfer by microorganisms. Efficient power generation is possible compared to power generation. Moreover, by maintaining the power generation output within a predetermined range, it is possible to obtain a constant power regardless of the properties of the treated water, and it is possible to perform a stable power supply.

Advantageous Effects of Invention According to the present invention, it is possible to provide a power generator and a power generation method that can be used as a stable power supply source in the recovery and utilization of energy by electrode reaction using treated water after anaerobic treatment.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the electric power generating apparatus in the 1st embodiment of this invention. 4 is a graph showing the relationship between the flow rate of treated water and the power output in power generation by the power generation unit of the power generation device according to the first embodiment of the present invention. It is a schematic explanatory drawing of the electric power generating apparatus in the 2nd embodiment of this invention. It is a schematic explanatory drawing of the electric power generating apparatus in the 3rd embodiment of this invention. 9 is a graph showing the relationship between reducing substance concentration in treated water and power generation output in power generation by the power generation unit of the power generation device according to the third embodiment of the present invention. It is a schematic explanatory drawing of the electric power generating apparatus in the 4th embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereafter, embodiment of the electric power generating apparatus which concerns on this invention, and an electric power generation method is described in detail, referring drawings. The power generation method in the present invention shall be replaced with the description of the operation of the power generation device in the present invention.
It should be noted that the power generation device and the power generation method described in the embodiments are merely examples for explaining the power generation device and the power generation method according to the present invention, and are not limited thereto.

In the present invention, the reducing substance contained in the treated water introduced into the power generation unit of the power generation device is not particularly limited as long as it functions as an electron donor. Whether or not a substance functions as an electron donor is relatively determined by the combination with a substance that functions as an electron acceptor (hereinafter simply referred to as "electron acceptor"). That is, the reducing substance in the present invention may be one that releases electrons more easily than the electron acceptor, that is, one that has a lower oxidation-reduction potential than the electron acceptor. For example, when oxygen is used as the electron acceptor, the reducing substance in the present invention may have a lower oxidation-reduction potential than oxygen. Such reducing substances include hydrogen sulfide, hydrogen, ammonia, and the like. is mentioned.

[First Embodiment]
FIG. 1 is a schematic explanatory diagram showing the structure of a power generator according to a first embodiment of the present invention.
As shown in FIG. 1, the power generation device 1A in this embodiment is applied to a wastewater treatment facility that performs anaerobic treatment of the water W to be treated, and is provided after the anaerobic treatment tank 2 that performs anaerobic treatment, It has a power generation unit 3 and a control unit 4 . In addition, the anaerobic treatment tank 2 is provided with a pipe L1 for introducing the water W to be treated, and the anaerobic treatment tank 2 is connected to the power generator 1A. and a pipe L3 for discharging the treated water W2 from the power generation unit 3 are provided. In FIG. 1, dashed-dotted arrows indicate that they are connected so as to be controllable or inputtable.

The anaerobic treatment tank 2 in this embodiment is a tank for treating the water W to be treated, and also functions as a tank for supplying the treated water W1 containing reducing substances to the power generator 1A.
The treatment performed in the anaerobic treatment tank 2 is suitable for the treatment target contained in the water W to be treated, and is not particularly limited as long as the treated water W1 after treatment contains reducing substances. For example, the treatments performed in the anaerobic treatment tank 2 include methane fermentation by acidogenic and methanogenic bacteria, denitrification by reducing nitric acid and nitrite by denitrifying bacteria, and sulfuric acid by reducing sulfuric acid by sulfate reducing bacteria. reduction treatment and the like. Methane fermentation, which produces methane, is particularly preferred from the viewpoint of processing costs and usefulness of generated gas.

The water W to be treated, which is the object of anaerobic treatment in the anaerobic treatment tank 2, is not particularly limited as long as it produces reducing substances as the treatment progresses. It should be noted that the reducing substance may be contained in the treated water W<b>1 , and may be contained in the water W to be treated before being introduced into the anaerobic treatment tank 2 . Specific examples of the water to be treated W include industrial wastewater discharged from various factories such as food factories, chemical factories, pulp and paper factories, and domestic wastewater such as sewage. In the following description, as the water W to be treated, water in which a reducing substance is generated through treatment will be mainly described, but the water W to be treated is not limited to this.

In the anaerobic treatment tank 2, especially when methane fermentation is performed among anaerobic treatments, in addition to methane, hydrogen sulfide, hydrogen, ammonia, etc. are generated in the water W to be treated. These products correspond to reducing substances in the present invention.

The water to be treated W that has been treated in the anaerobic treatment tank 2 becomes treated water W1 containing reducing substances, and is introduced into the power generator 1A via the pipe L2.

[Power generator]
(Power Generation Department)
The power generation unit 3 is for performing a power generation step of generating power using reducing substances in the treated water W1 as electron donors.
As shown in FIG. 1, the power generation unit 3 of this embodiment is provided after the anaerobic treatment tank 2, and is provided so as to partition the first cell 31a and the second cell 31b and the cells 31a and 31b. and electrodes 33a and 33b arranged in cells 31a and 31b, respectively. Here, the first cell 31a is formed so that the treated water W1 introduced from the anaerobic treatment tank 2 through the pipe L2 comes into contact with the electrode 33a. acts as an anode. On the other hand, the second cell 31b is formed to store or supply an electron acceptor, and the electrode 33b arranged in the second cell 31b functions as a cathode. Moreover, the electrodes 33a and 33b are connected to an external circuit C by means of conducting wires. As a result, in the power generation unit 3, it becomes possible to recover and utilize electrical energy generated by the reducing substance acting as an electron donor.

The first cell 31a is provided with an electrode 33a, and the material and shape are not particularly limited as long as it is formed so that the treated water W1 is in contact with the electrode 33a. For example, as shown in FIG. 1, it has a space that can temporarily store the treated water W1 introduced from the treated water inlet 32a through the pipe L2, and treats the treated water W2 after contact with the electrode 33a. For example, a pipe L3 for discharging water from the water discharge port 32b may be provided. As a result, the reducing substances in the treated water W1 donate electrons to the electrode 33a as electron donors, and then are rapidly discharged through the pipe L3.

The treated water W2 discharged through the pipe L3 can be discharged as it is if it satisfies the water quality that allows discharge to a river or the like. A treatment facility for further treating the treated water W2 may be provided downstream of the pipe L3, and after the treated water W2 is treated, it may be discharged to the outside of the system. Such a treatment facility is not particularly limited as long as it can treat the treated water W2 so that it can be discharged outside the system or into a river. Examples include an aeration tank and a pH adjustment tank.

The second cell 31b is provided with an electrode 33b, and may be formed so as to store or supply an electron acceptor for reducing substances in the treated water W1, and its material and shape are not particularly limited.

Here, the form of the electron acceptor may be either gas or liquid. The liquid may be a solution in which a solid drug is dissolved, or a solution in which a gas is mixed (dissolved).
Specific examples of the electron acceptor in this embodiment include, for example, oxygen and oxygen-containing gases. The gas containing oxygen includes a gas containing oxygen as a mixture such as air and a gas containing oxygen as an element constituting a compound such as carbon dioxide. When a gas is used as an electron acceptor, there are advantages in that it is not necessary (or easy) to dispose of the material discharged after the reaction, and that the cost associated with acquisition can be reduced. In order to maximize these advantages, it is particularly preferable to use air as the electron acceptor.
Other examples of the electron acceptor in this embodiment include, for example, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous solution of potassium ferricyanide, and the like. When a liquid is used as an electron acceptor, it is possible to easily handle a compound (oxidizing agent) that is highly effective as an electron acceptor, so there is an advantage that power generation efficiency can be further improved. From the viewpoint of improving power generation efficiency, it is particularly preferable to use an aqueous solution of potassium ferricyanide as the electron acceptor.

As the second cell 31b, for example, as shown in FIG. For example, an electron acceptor supply port 34a for supplying gas via the pipe L5 and an electron acceptor discharge port 34b for discharging gas after the reaction are provided via the pipe L5. As another example of the second cell 31b, a space capable of storing liquid is provided in the second cell 31b, and an electron acceptor supply port 34a and an electron acceptor discharge port 34b are provided, respectively. For example, it is possible to supply the solution and to discharge the solution after the reaction. As a result, electrons from the electrode 33a can be received by the electron acceptor via the electrode 33b, and a current flows between the electrodes 33a and 33b to generate power. In addition, the electron acceptor after the reaction is rapidly discharged to the outside of the power generation section 3 through the electron acceptor discharge port 34b and the pipe L5.
The electron acceptor supply port 34a and/or the electron acceptor outlet 34b, or the pipe L4 and/or the pipe L5 is provided with a flow control mechanism such as a valve to adjust the concentration of the electron acceptor in the second cell 31b. It may be possible. Furthermore, a control mechanism may be provided to control the flow rate adjustment mechanism so that the electron acceptor concentration corresponding to the amount of electrons generated by the reaction at the electrode 33a is maintained. As a result, it is possible to suppress a decrease in reaction efficiency related to electron transfer between the electrodes 33a and 33b, thereby suppressing a decrease in power generation efficiency.

Although one electron acceptor supply port 34a and one electron acceptor discharge port 34b are shown in FIG. 1, the present invention is not limited to this. For example, a plurality of electron acceptor supply ports 34a and electron acceptor discharge ports 34b may be provided. In particular, when a gas containing oxygen is used as an electron acceptor, water is produced by a reaction at the electrode 33b, as will be described later. Therefore, when a plurality of electron acceptor discharge ports 34b are provided, for example, one for discharging gas and one for discharging liquid are provided separately.

The ion exchanger 35 is not particularly limited as long as it has a known configuration that allows ions to pass therethrough. In particular, a cation exchange membrane capable of permeating hydrogen ions generated at the electrode 33a (anode side) may be used. As a result, the hydrogen ions move from the electrode 33a (anode side) to the electrode 33b (cathode side), so that the reaction efficiency of the electron acceptor at the electrode 33b can be increased, and the electrode reaction efficiency can be improved. . Further, it is more preferable that the ion exchanger 35 has low oxygen permeability. This suppresses the electron acceptor (especially oxygen) supplied to the electrode 33b (cathode side) from moving to the electrode 33a side, and suppresses the decrease in the reaction efficiency of the electron donor at the electrode 33a due to oxygen. becomes possible.
Although FIG. 1 shows that the ion exchanger 35 is provided separately from the electrodes 33a and 33b, it is not limited to this. For example, a material having an ion exchange capacity and the electrode 33a and/or the electrode 33b may be integrated. As a result, it is possible to reduce the size of the power generation unit 3 as a whole, and it is possible to shorten the time required for maintenance work.

The electrode 33a is an electrode that collects electrons from reducing substances in the treated water W1, and functions as a so-called anode. Further, the electrode 33a in this embodiment is arranged in the first cell 31a so as to come into contact with the treated water W1 after being treated in the anaerobic treatment tank 2. As shown in FIG.

The electrode 33a is not particularly limited in material and shape as long as it functions as an anode. The material and shape of the electrode 33a can be appropriately selected in consideration of the cost of material procurement and processing, the reaction efficiency of the reducing substance in the electrode 33a, and the like. Examples of the material of the electrode 33a include carbon and metals (stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the electrochemical field. Moreover, examples of the shape of the electrode 33a include a flat plate shape, a rod shape, and a mesh shape.
In particular, as the electrode 33a of this embodiment, it is preferable to use a porous material in view of the electrode reaction efficiency. For example, as the electrode 33a, in addition to carbon fibers such as carbon paper, carbon cloth, and carbon felt, which are porous bodies, foam metal, porous metal, and metal mesh may be used.

The electrode 33a in this embodiment does not allow microorganisms to come into contact with or carry on the surface of the electrode. Therefore, the mass transfer of the reducing substance is not inhibited by the microorganism, and the reaction efficiency as an electron donor (mass transfer rate of the reducing substance to the electrode 33a) can be improved, thereby improving the power generation efficiency. can be done.
Further, the electrode 33a in this embodiment does not collect electrons generated by metabolism of microorganisms, but directly collects electrons from reducing substances. Therefore, the metabolism of microorganisms does not become rate-determining, and the reaction efficiency as an electron donor (the electron collection rate at the electrode 33a) is improved, and the power generation efficiency can be improved.

The electrode 33b is a counter electrode to the electrode 33a, an electrode that transfers electrons to an electron acceptor, and functions as a so-called cathode. Also, the electrode 33b in this embodiment is arranged in the second cell 31b.

The electrode 33b is not particularly limited in material and shape as long as it functions as a cathode. The material and shape of the electrode 33b can be appropriately selected in consideration of the cost of material procurement and processing, the reaction efficiency of the electron acceptor in the electrode 33b, and the like. Examples of materials for the electrode 33b include carbon and metals (stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the field of electrochemistry. Moreover, examples of the shape of the electrode 33b include a plate shape, a bar shape, a mesh shape, and the like.
In particular, as the electrode 33b of this embodiment, it is preferable to use an electrode made of a porous body in view of the electrode reaction efficiency. For example, as the electrode 33b, in addition to carbon fibers such as carbon paper, carbon cloth, and carbon felt, which are porous bodies, foam metal, porous metal, and metal mesh may be used.

When the electron acceptor supplied into the second cell 31b is gas (air), one surface of the electrode 33b is in contact with the gas and the other surface is in contact with the treated water W1. Therefore, it is preferable that the electrode 33b has a form suitable for a so-called air cathode. Forms suitable for air cathodes include, for example, having both gas permeable and water impermeable properties. By making the electrode 33b gas-permeable, it is possible to effectively react the gas, which is an electron acceptor, at the electrode 33b. In addition, since the electrode 33b is water-impermeable, it is possible to prevent the treated water W1 in the first cell 31a from permeating the electrode 33b and flowing into the second cell 31b. Specific examples of such an electrode 33b include those made of carbon fiber, those subjected to surface treatment such as application of a material having gas permeability and water impermeability to the surface of the metal mesh, lamination of films, and the like. mentioned. The term “water-impermeable” as used herein refers to impermeability to water. It is included.

Hereinafter, based on FIG. 1, reactions and processes relating to electrode reactions in the power generator according to the first embodiment of the present invention will be described.
In the reaction and process related to the electrode reaction in the power generation device 1A of the present embodiment, the reducing substance contained in the treated water W1 after anaerobic treatment is used as an electron donor, and a solution containing an oxidant and oxygen is used as an electron acceptor. It describes things.
It should be noted that the description of the reactions and steps based on FIG. 1 shows an example of the electrode reaction in this embodiment, and is not limited to this. In addition, the following description mainly describes the reactions and processes related to the power generation unit 3 of the power generation device 1A, and the reactions and processes related to the anaerobic treatment tank 2 that generates the treated water W1 to be introduced into the power generation device 1A. simplifies the description. Furthermore, the notations of reactions R1 to R4 and steps S1 to S3 are numbered for the sake of explanation, and do not specify the reaction and the order of the steps.

As shown in FIG. 1, the water to be treated W introduced into the anaerobic treatment tank 2 is anaerobically treated by anaerobic microorganisms (acidogenic bacteria and methanogenic bacteria) in the anaerobic treatment tank 2 (step S1). At this time, reducing substances (hydrogen, hydrogen sulfide, ammonia, etc.) are produced in addition to methane.

The treated water W1 that has been treated in the anaerobic treatment tank 2 and contains reducing substances is introduced into the first cell 31a in the power generation unit 3 through the pipe L2 (step S2). Here, when a reducing substance (hydrogen, hydrogen sulfide, ammonia, etc.) contacts the electrode 33a, the reducing substance functions as an electron donor to donate electrons to the electrode 33a. At this time, taking hydrogen sulfide as an example of the reducing substance that functions as an electron donor, the reaction (reaction R1) at the electrode 33a is represented by the following reaction formula (formula 1).

Also, part of the hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is represented by the following reaction formula (Formula 2).

As shown by formulas 1 and 2, in reaction R1, hydrogen sulfide contained in treated water W1 after being treated in anaerobic treatment tank 2 donates electrons to electrode 33a, and hydrogen sulfide itself is oxidized. This makes it harmless and odorless. Therefore, the power generator 1A of this embodiment can perform desulfurization and deodorization as well as power generation. In addition to hydrogen sulfide, reducing substances (ammonia, etc.), which are harmful substances and odorous substances, similarly function as electron donors, and the progress of the reaction makes it possible to render them harmless and odorless.

Based on the reaction formulas shown in formulas 1 and 2, after the reaction at the electrode 33a proceeds, electrons move from the electrode 33a to the electrode 33b via the lead (reaction R2). At this time, the hydrogen ions generated by the reaction at the electrode 33a move to the second cell 31b side via the ion exchanger 35 (reaction R3).

On the other hand, an electron acceptor (solution) is introduced from the electron acceptor supply port 34a into the second cell 31b (step S3). Here, the electron acceptor receives the electron transferred from the electrode 33a to the electrode 33b through the electrode 33b by the reaction R2. At this time, the hydrogen ions that have moved to the second cell 31b through the ion exchanger 35 by the reaction R3 also react with the electron acceptor. The reaction (reaction R4) at the electrode 33b at this time is represented by the following reaction formula (formula 3). Note that oxygen in Formula 3 corresponds to an electron acceptor.

A current flows between the electrodes 33a and 33b based on the reactions R1 to R4 and steps S1 to S3 described above. As a result, a reaction using the reducing substance in the treated water W1 as an electron donor proceeds, and power generation is performed in the power generation device 1A of the present embodiment.

In power generation using conventional microbial fuel cells, increasing the concentration of the microorganisms required for wastewater treatment further inhibits the transfer of substances to the electrodes. is known to have a trade-off relationship. On the other hand, in the power generation device 1A of the present embodiment and the power generation method using the power generation device 1A, wastewater treatment (anaerobic treatment tank 2) and power generation (power generation device 1A) can be performed separately. Therefore, in the power generation device 1A and the power generation method of this embodiment, there is no trade-off relationship between waste water treatment efficiency and power generation efficiency, and efficient power generation is possible.

Moreover, the electrical energy obtained by the power generation in the power generator 1A of this embodiment can be recovered and utilized through the external circuit C connected to the electrodes 33a and 33b. Note that the use of electric energy is not particularly limited. For example, the anaerobic treatment tank 2 or the like may be used to drive the wastewater treatment facility in which the power generator 1A is arranged, or may be used outside the wastewater treatment facility.

Here, the relationship between the power generation output in the power generation unit 3 and the flow rate of the treated water W1 supplied into the first cell 31a through the pipe L2 will be described based on an example.
FIG. 2 is a graph showing the relationship between the flow rate of treated water supplied to the power generation unit 3 and the power output in power generation using the power generation unit 3 of the power generation device 1A of this embodiment.
As the measurement conditions in FIG. 2, carbon felt electrodes were used as the electrodes 33a and 33b, and a cation exchange membrane was used as the ion exchanger . Further, a solution of potassium ferricyanide dissolved in a phosphate buffer is supplied to the second cell 31b at a constant flow rate, while the first cell 31a corresponds to the treated water W1 in this embodiment, A sample solution in which sodium hydrogen sulfide was dissolved in a phosphate buffer was used and supplied at different flow rates (unit: mL/min). At this time, the voltage flowing between the electrodes 33a and 33b is measured with a potentiostat, and the flow rate is zero (a state in which the sample solution is simply stored in the first cell 31a without entering or exiting the first cell 31a). An output ratio was obtained.

As shown in FIG. 2, it was found that as the flow rate of the sample solution (corresponding to treated water W1) supplied to the power generation unit 3 increased, the power generation output ratio increased and gradually approached a constant value. Here, depending on the treatment conditions in the anaerobic treatment tank 2, the flow rate of the treated water W1 discharged from the anaerobic treatment tank 2 may change. It will fluctuate according to the flow rate of the treated water W1.
On the other hand, when the power generation output obtained by the power generation unit 3 is used as electrical energy outside the power generation device 1A via the external circuit C, the power generation output itself fluctuates in addition to the strength of the power generation output. This poses a problem in stably using it as a supply source.
Therefore, in order to use the power generator 1A in this embodiment as a stable power supply source, the power generation unit It is necessary to be able to obtain constant electrical energy from 3.

(control part)
The control unit 4 is for performing control steps for controlling the power generation output of the power generation unit 3 to be maintained within a predetermined range.
As the control unit 4 in this embodiment, based on the above-described relationship between the power generation output and the flow rate of the treated water W1, the power generation output in the power generation unit 3 is maintained within a predetermined range. One that controls the flow rate of the water W1 can be mentioned.
More specifically, as shown in FIG. 1, the controller 4 may include an arithmetic controller 41 and a flow rate adjustment mechanism 42 .

The arithmetic control unit 41 is connected to the external circuit C, receives the power output from the power generation unit 3, and calculates the flow rate of the treated water W1 required to maintain the power output within a predetermined range. Based on the result, control relating to the operation of the flow rate adjusting mechanism 42 is performed.
Further, the flow rate adjustment mechanism 42 is for adjusting the flow rate of the treated water W1 supplied to the power generation unit 3 via the pipe L2, and includes a known mechanism for adjusting the flow rate, such as an on-off valve and a valve. can be used.

The arithmetic control unit 41 in this embodiment may include, for example, manual operation by an operator, but has a data input/output function for acquiring information, and controls the operation of the flow rate adjustment mechanism 42. It is preferable to enable automatic control by using a computing device in which a processor such as a CPU executes a program for performing such calculation and control signal transmission. This facilitates optimization of the control for maintaining the power output from the power generation unit 3 within a predetermined range.
The control unit 4 may be provided with display means for displaying parameters used for control, such as power generation output and flow rate of treated water W1, and input means for the display means.

As described above, by using the power generation device 1A of the present embodiment and using the reducing substances contained in the treated water after the anaerobic treatment as direct electron donors to generate power, it is possible to inhibit mass transfer by microorganisms. Therefore, it is possible to generate power more efficiently than power generation by microbial fuel cells. Further, by using the power generator 1A of the present embodiment and maintaining the power generation output within a predetermined range based on the relationship between the flow rate of the treated water supplied to the power generator and the power generation output, regardless of the flow rate of the treated water Constant electrical energy can be obtained, and it can be used as a stable power supply source.

The power generator 1A in this embodiment uses a reducing substance in the treated water W1 as an electron donor to generate power through an electrochemical reaction (electrode reaction). In general, when an electrochemical reaction is performed, there is a problem that the efficiency of the electrochemical reaction is lowered due to movement of electrons to a place other than the place where the electrochemical reaction is actually performed (the power generation section 3). Therefore, it is preferable that the power generator 1A in this embodiment is insulated except for the part where the electrochemical reaction is performed (power generation unit 3). Specific examples of the insulation treatment include, for example, placing the anaerobic treatment tank 2 on top of an insulator, configuring the outer wall or inner wall of the anaerobic treatment tank 2 with an insulator, For example, the inner wall is coated with an insulating material. Insulation treatment of the introduction pipe L1, the connection pipe L2, and the discharge pipe L3 includes, for example, making each pipe made of an insulator, coating each pipe with an insulating material, and the like.

[Second Embodiment]
FIG. 3 is a schematic explanatory diagram showing a power generator according to a second embodiment of the present invention.
In addition to the anaerobic treatment tank 2 for performing anaerobic treatment on the water W to be treated, the power generator 1B according to the second embodiment includes a reaction tank for further performing wastewater treatment on the treated water discharged from the anaerobic treatment tank 2. 5, and for the power generator 1A in the first embodiment, the treated water discharged from the anaerobic treatment tank 2 is supplied to the power generation unit 3 (treated water W1) and the one to be supplied to the reaction vessel 5 (treated water W1'). The description of the same configuration as that of the first embodiment will be omitted.

As shown in FIG. 3, in the power generator 1B in this embodiment, the treated water discharged from the anaerobic treatment tank 2 is supplied to the power generation unit 3 through the pipe L2 as the branch passage 43 (treated water W1 ) to generate power.

In addition, the reaction tank 5 is for further treating the treated water discharged from the anaerobic treatment tank 2 in order to satisfy the water quality that can be discharged to a river or the like. Specifically, aeration is performed. A tank, an aerobic treatment tank, etc. are mentioned. In addition to the treated water W1 discharged from the anaerobic treatment tank 2 (treated water W1′) supplied through the pipe L6, the reaction tank 5 also contains the treated water W2 discharged from the power generation unit 3. It is preferable that the waste water is introduced through the pipe L3 and subjected to waste water treatment. As a result, the wastewater treatment efficiency for the water to be treated W can be improved as a whole wastewater treatment facility to which the power generator 1B is applied. Then, the treated water W3 discharged after being treated in the reaction tank 5 is discharged outside the treatment system through the pipe L7.

The branch path 43 branches off from the pipe L6 that connects the anaerobic treatment tank 2 and the reaction tank 5, and connects the anaerobic treatment tank 2 and the power generation section 3 of the power generation device 1B, as shown in FIG. , and piping L2.
Further, as shown in FIG. 3, a flow rate adjusting mechanism 42 is provided at the starting point of the branch passage 43, and treated water W1' supplied to the pipe L6 side and treated water W1 supplied to the branch passage 43 side (pipe L2 side) are controlled. By controlling the ratio with the arithmetic control unit 41, it becomes easy to control the flow rate of the treated water W1 supplied to the power generation unit 3 so as to maintain the power generation output in the power generation unit 3 within a predetermined range. .

As in the wastewater treatment facility shown in FIG. 3, when the treated water W1 after anaerobic treatment needs to be further treated, the treated water W1 after anaerobic treatment can be smoothly supplied to the post-treatment, and power generation It may be difficult to control the flow rate of the treated water W1 in order to keep the power generation output of the apparatus constant.
On the other hand, in the power generation device 1B in this embodiment, not all of the treated water W1 after anaerobic treatment is supplied to the power generation unit 3, but a part of the treated water W1 is supplied to the power generation unit 3, so that after anaerobic treatment The treated water W1' can be smoothly supplied to the reaction tank 5, which is the post-treatment, and the power generation output of the power generator 1B can be easily controlled.

[Third Embodiment]
FIG. 4 is a schematic explanatory diagram showing a power generator according to the third embodiment of the present invention.
The power generator 1C according to the third embodiment is, as shown in FIG. 41 and the flow rate adjustment mechanism 42, an arithmetic control unit 44 and a concentration control mechanism 45 for controlling the concentration of reducing substances in the treated water W1 are provided. The description of the same configuration as that of the first embodiment will be omitted.

The power generator 1C in this embodiment focuses on factors other than the flow rate of the treated water W1 shown in the power generator 1A in the first embodiment as properties of the treated water W1 that affect the power generation output. Specifically, the focus is on the reducing substance concentration in the treated water W1.

Here, the relationship between the power generation output of the power generation unit 3 and the reducing substance concentration in the treated water W1 supplied into the first cell 31a through the pipe L2 will be described based on an example.
FIG. 5 is a graph showing the relationship between the reducing substance concentration (sulfide concentration) in the treated water supplied to the power generation unit 3 and the power output in the power generation by the power generation unit 3 of the power generation device 1C of this embodiment. .

As the measurement conditions in FIG. 5, carbon felt electrodes were used as the electrodes 33a and 33b, and a cation exchange membrane was used as the ion exchanger . Further, a solution of potassium ferricyanide dissolved in a phosphate buffer is supplied to the second cell 31b at a constant flow rate, while the first cell 31a corresponds to the treated water W1 in this embodiment, Sample solutions were prepared by dissolving different amounts of sodium hydrogen sulfide in phosphate buffer, and supplied at a constant flow rate for each sulfide concentration (unit: mM). At this time, the voltage flowing between the electrodes 33a and 33b was measured with a potentiostat, and the maximum output ratio was obtained with reference to the sulfide concentration of zero.

As shown in FIG. 5, it was found that the power generation output ratio tends to increase as the sulfide concentration (corresponding to the reducing substance concentration) in the sample solution (corresponding to the treated water W1) increases. Here, depending on the treatment conditions in the anaerobic treatment tank 2, the concentration of reducing substances in the treated water W1 discharged from the anaerobic treatment tank 2 may change. It will fluctuate according to the reducing substance concentration of the treated water W1 discharged from.
Therefore, in order to use the power generator 1C in this embodiment as a stable power supply source, it is necessary to First, it is necessary to obtain a constant amount of electrical energy from the power generation section 3 .

As the control unit 4 in this embodiment, based on the above-described relationship between the power generation output and the reducing substance concentration in the treated water W1, the power generation output of the power generation unit 3 is maintained within a predetermined range. , which controls the concentration of reducing substances in the treated water W1 supplied to .
More specifically, as shown in FIG. 4, the controller 4 may include an arithmetic controller 44 and a density control mechanism 45 .

The arithmetic control unit 44 is connected to the external circuit C, receives the power output from the power generation unit 3, and calculates the reducing substance concentration in the treated water W1 required to maintain the power output within a predetermined range. At the same time, it controls the operation of the density control mechanism 45 based on the calculation result.
The arithmetic control unit 44 in this embodiment may include, for example, a manual operation by an operator, as in the arithmetic control unit 41 in the first embodiment. It is preferable to use a computing device having an output function and having a processor such as a CPU to execute a program for performing calculations related to the operation control of the concentration control mechanism 45 and transmitting control signals, so that automatic control is possible. This facilitates optimization of the control for maintaining the power output from the power generation unit 3 within a predetermined range.

The concentration control mechanism 45 is for adjusting the concentration of reducing substances in the treated water W1 supplied to the power generation unit 3 through the pipe L2.
As the concentration control mechanism 45 in this embodiment, for example, when the power generation output tends to decrease below a predetermined range, the treatment in the anaerobic treatment tank 2 is performed to increase the concentration of reducing substances in the treated water W1. While performing an operation to increase the amount of generated reducing substances, if the power generation output tends to increase beyond a predetermined range, the anaerobic treatment tank 2 is used to reduce the concentration of reducing substances in the treated water W1. can be carried out to reduce the amount of reducing substances generated by the treatment of

More specifically, as one of the concentration control mechanisms 45, sulfur addition means for adding sulfur to the anaerobic treatment tank 2 is provided to increase the concentration of reducing substances (hydrogen sulfide) contained in the treated water W1. Things are mentioned. At this time, the sulfur content addition means is not particularly limited as long as it can add sulfur content to the anaerobic treatment tank 2, but based on Equations 1 and 2, the sulfur content generated in the power generation unit 3 is preferred. For example, in order to use the sulfur contained in the treated water W2 discharged from the power generation unit 3, a line (not shown) for introducing a part of the treated water W2 into the anaerobic treatment tank 2 may be formed, or the power generation unit 3 By providing a means (not shown) for removing sulfur adhering to the electrode 33a, the total amount of sulfur contained in the treated water W2 can be increased, and the treated water W2 can be introduced into the anaerobic treatment tank 2. mentioned. Moreover, at this time, a flow rate adjusting mechanism for controlling the flow rate of the treated water W2 introduced into the anaerobic treatment tank 2 may be provided. As a result, it is possible to control the reducing substance concentration and reduce the cost for treating the sulfur generated in the power generation unit 3 .

Further, as another example of the concentration control mechanism 45, the concentration of reducing substances (hydrogen sulfide) contained in the treated water W1 can be lowered by providing dilution water addition means for adding water for dilution to the treated water W1. mentioned. At this time, the water for dilution added by the dilution water addition means may be any water that can reduce the concentration of reducing substances in the treated water W1. Use of other treated water (particularly, treated water that can be discharged to a river or the like) can be mentioned.

The control unit 4 in this embodiment may be provided with display means for displaying parameters used for control, such as power generation output and concentration of reducing substances in the treated water W1, and input means for the display means.

In the power generation device 1C of this embodiment, it is possible to generate power through the same steps as in the first embodiment.
Further, using the power generator 1C of the present embodiment, the power generation output is maintained within a predetermined range based on the relationship between the concentration of reducing substances in the treated water supplied to the power generator and the power generation output. Constant electrical energy can be obtained regardless of the concentration of the toxic substance, and it can be used as a stable power supply source.

[Fourth Embodiment]
FIG. 6 is a schematic explanatory diagram showing a power generator according to the fourth embodiment of the present invention.
In addition to the anaerobic treatment tank 2 for performing anaerobic treatment on the water W to be treated, the power generator 1D according to the fourth embodiment includes a reaction tank for further performing wastewater treatment on the treated water discharged from the anaerobic treatment tank 2. 5, and for the power generator 1C in the third embodiment, the treated water discharged from the anaerobic treatment tank 2 is supplied to the power generation unit 3 (treated water W1) and the one to be supplied to the reaction vessel 5 (treated water W1'). The description of the same configuration as that of the third embodiment will be omitted.

As shown in FIG. 6, in the power generator 1D of this embodiment, the treated water discharged from the anaerobic treatment tank 2 is supplied to the power generation unit 3 via the pipe L2 as the branch passage 43 (treated water W1 ) to generate power.
Note that the reaction vessel 5 has the same structure as that shown in the second embodiment described above, and the description thereof is omitted.

The branch path 43 branches from the pipe L6 that connects the anaerobic treatment tank 2 and the reaction tank 5, and connects the anaerobic treatment tank 2 and the power generation section 3 of the power generation device 1D, as shown in FIG. , and piping L2.
Further, as shown in FIG. 6, a diluting water addition means, which is one of the concentration control mechanisms 45, is provided on the branch channel 43, and the reducing property of the treated water W1 supplied to the branch channel 43 side (pipe L2 side) is controlled. By controlling only the substance concentration and supplying the treated water W1' supplied to the reaction tank 5 through the pipe L6 without changing the properties thereof, the total amount of treated water discharged from the anaerobic treatment tank 2 Control the reducing substance concentration in the treated water W1 supplied to the power generation unit 3 so that the power generation output in the power generation unit 3 is maintained within a predetermined range without the need to control the concentration of reducing substances for becomes easier.

In particular, in the power generator 1D of this embodiment, when the concentration control mechanism 45 dilutes the treated water W1, a portion of the treated water W3 after being treated in the reaction tank 5 is used as water for dilution. is mentioned. As a result, the existing structure in the waste water treatment facility can be used for the structure related to the concentration control mechanism 45, and the need to supply water from the outside is eliminated, making it possible to reduce costs.

In the power generation device 1D in this embodiment, not all of the treated water W1 after anaerobic treatment is supplied to the power generation unit 3, but a part of the treated water W1 is supplied to the power generation unit 3, so that the treatment after the anaerobic treatment It is possible to smoothly supply the water W1' to the reaction tank 5, which is the post-treatment, and to facilitate the control of the power generation output of the power generation device 1D.

In addition, the embodiment mentioned above shows an example of a power generation apparatus and a power generation method. The power generation device and power generation method according to the present invention are not limited to the above-described embodiments, and the power generation device and power generation method according to the above-described embodiments may be modified without changing the gist of the claims. good.

For example, the power generation device in this embodiment may include a plurality of power generation units. Also, a plurality of power generators of this embodiment may be provided in the wastewater treatment facility. As a result, it becomes possible to generate power at a plurality of locations by effectively utilizing the treatment in the wastewater treatment facility, and to improve both the wastewater treatment efficiency and the power generation efficiency.

In addition, the power generator in this embodiment may correspond to a plurality of elements as a control section that controls the power generation output in accordance with the property change of the treated water. For example, a combination of a flow rate adjustment mechanism for controlling the flow rate of treated water and a concentration control mechanism for controlling the concentration of reducing substances in the treated water is provided, and the power generation output of each mechanism is maintained within a predetermined range. for example, to control

INDUSTRIAL APPLICABILITY The power generation device and the power generation method of the present invention can be suitably used as a stable power supply source by applying it to wastewater treatment involving anaerobic treatment in which reducing substances are generated by treating the water to be treated. .

1A, 1B, 1C, 1D power generator, 2 anaerobic treatment tank, 3 power generation unit, 31a first cell, 31b second cell, 32a treated water inlet, 32b treated water outlet, 33a, 33b electrodes, 34a electron Receptor Supply Port 34b Electron Acceptor Discharge Port 35 Ion Exchanger 4 Control Unit 41 Operation Control Unit 42 Flow Control Mechanism 43 Branch Channel 44 Operation Control Unit 45 Concentration Control Mechanism 5 Reaction Tank C External circuit, L1 to L6 piping, W water to be treated, W1, W1', W2, W3 treated water

Claims (5)

A power generation unit that generates power by an electrode reaction using a reducing substance in the treated water after anaerobic treatment as an electron donor;
and a control unit that controls the power generation unit to maintain the power generation output within a predetermined range. 2. The power generator according to claim 1, wherein said control unit controls a flow rate of treated water supplied to said power generation unit. The power generator according to claim 1, wherein the control unit controls the concentration of reducing substances in the treated water after the anaerobic treatment. 4. The power generator according to any one of claims 1 to 3, further comprising a branch channel for supplying part of the treated water after the anaerobic treatment to the power generation unit. A power generation step of generating power by an electrode reaction using a reducing substance in the treated water after anaerobic treatment as an electron donor;
and a control step of controlling to maintain the power output in the power generation step within a predetermined range.