JP2021035672A - Wastewater treatment apparatus, power generation apparatus, desulfurization treatment apparatus, power generation method and desulfurization method - Google Patents

Abstract

To provide a wastewater treatment apparatus, a power generation apparatus, a desulfurization treatment apparatus, a power generation method and a desulfurization method enabling further efficient energy recovery/utilization or desulfurization as a technique associated with wastewater treatment.SOLUTION: A wastewater treatment apparatus for treating water to be treated, a power generation apparatus, a desulfurization treatment apparatus, a power generation method and a desulfurization method in which power generation or desulfurization treatment is carried out by a reaction using a reducing substance contained in water to be treated, as an electron donor. This invention enables efficient power generation and desulfurization treatment, because there occurs no inhibition of mass transfer by microorganisms when power generation or desulfurization treatment is carried out by a reaction using a reducing substance contained in water to be treated, as a direct electron donor. In addition, this makes it possible to downsize a wastewater treatment facility compared to a case where a power generation facility using a microbial fuel cell and a desulfurization treatment facility are installed separately.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wastewater treatment apparatus accompanied by power generation or desulfurization treatment. The present invention also relates to a power generation device and a power generation method in wastewater treatment. Furthermore, the present invention relates to a desulfurization treatment apparatus and a desulfurization method in wastewater treatment.

Generally, as a method for treating wastewater containing organic substances, biological treatment using various microorganisms is known. In particular, biological treatment in an anaerobic environment (hereinafter referred to as "anaerobic treatment") is widely used because it does not require aeration power and has high advantages such as almost no excess sludge. .. In addition, various treatment processes and techniques are combined in association with wastewater treatment by anaerobic treatment. For example, as one of the techniques associated with anaerobic treatment, it is known that biogas such as methane generated by anaerobic treatment is used as fuel to generate electricity.

On the other hand, a microbial fuel cell is known as a technique for generating electricity by utilizing an oxidation-reduction reaction by a microorganism. A microbial fuel cell is one that obtains electrical energy by utilizing the metabolic capacity of microorganisms. More specifically, a microbial fuel cell has a configuration in which electrons generated in the process of oxidative decomposition of a substrate such as an organic substance by microorganisms are recovered on the anode side and an electric current is obtained by moving the electrons to the cathode side. 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 a microorganism and an organic substance capable of growing under anaerobic conditions, and the other electrode is used as a cathode to form a structural void. A power generation device is described in which a closed circuit is formed by electrically connecting an anode and a cathode by forming them from a material to be brought into contact with air. Further, Patent Document 1 also describes that microorganisms are attached to the surface of the anode. Further, Patent Document 1 also describes a power generation method in which this power generation device proceeds an oxidation reaction by a microorganism using an organic substance as an electron donor at an anode and a reduction reaction using oxygen as an electron acceptor at a cathode. Has been done.

Japanese Unexamined Patent Publication No. 2004-342212

Power generation by a microbial fuel cell as described in Patent Document 1 has low energy conversion efficiency, and improvement of power generation output has become a major issue in practical use. It is presumed that this is because the microorganisms directly contact or support the electrodes, so that the mass transfer to the electrodes is inhibited by the microorganisms, and the metabolic rate of the microorganisms becomes rate-determining.

Further, in recent years, in order to suppress equipment drive power at the time of wastewater treatment and to improve energy saving, a technology capable of efficiently recovering and using energy is required as a technology associated with wastewater treatment. As one of such technologies, a technology related to applying a microbial fuel cell to wastewater treatment and simultaneously performing wastewater treatment and power generation has been studied, but as described above, it is possible to obtain sufficient power generation output. There is a problem that it is difficult.

Further, as a technology associated with wastewater treatment, in addition to efficient energy recovery and utilization, a technology for efficiently removing harmful substances in the water to be treated generated during wastewater treatment is required. As such a technique, in particular, it is required to efficiently perform a desulfurization treatment for removing hydrogen sulfide generated during wastewater treatment.

An object of the present invention is to provide a wastewater treatment apparatus, a power generation apparatus, a desulfurization treatment apparatus, a power generation method, and a desulfurization method that enable more efficient energy recovery / utilization or desulfurization treatment as a technique associated with wastewater treatment. Is.

As a result of diligent studies on the above problems, the present inventor has made it possible to efficiently recover and utilize energy by power generation in wastewater treatment by performing a reaction using a reducing substance in the water to be treated in wastewater treatment. The present invention has been completed by finding that it is possible to perform a desalination treatment of the water to be treated.
That is, the present invention is the following wastewater treatment apparatus, power generation apparatus, desulfurization treatment apparatus, power generation method and desulfurization method.

The wastewater treatment apparatus of the present invention for solving the above problems is a wastewater treatment apparatus for treating water to be treated, and has a feature of generating electricity by a reaction using a reducing substance in the water to be treated as an electron donor. ..

The wastewater treatment apparatus of the present invention directly uses the reducing substance contained in the water to be treated as an electron donor to generate electricity, so that the movement of the substance is not hindered by microorganisms, so that efficient power generation is possible. It becomes. In addition, the equipment can be downsized as compared with the power generation by the microbial fuel cell.

Another aspect of the wastewater treatment apparatus of the present invention for solving the above problems is a wastewater treatment apparatus that treats water to be treated by a reaction in which a reducing substance in the water to be treated is used as an electron donor. It has the characteristic of performing desulfurization treatment.

The wastewater treatment apparatus of the present invention can convert hydrogen sulfide, which is a reducing substance, into sulfur by performing desulfurization treatment by directly using the reducing substance contained in the water to be treated as an electron donor, and can be treated. It becomes possible to efficiently remove hydrogen sulfide in water.

Further, one embodiment of the wastewater treatment apparatus of the present invention is characterized in that electrodes are installed in the water to be treated to generate electricity.
According to this feature, by installing the electrode directly in the water to be treated introduced into the wastewater treatment apparatus, it becomes possible to carry out power generation in a series of treatment processes in the wastewater treatment. This makes it possible to carry out efficient power generation without increasing the size of the equipment. At this time, the electrode reaction using hydrogen sulfide contained in the water to be treated as an electron donor proceeds to convert it into sulfur. Therefore, it is possible to carry out the efficient desulfurization treatment without separately providing equipment for the desulfurization treatment.

Further, one embodiment of the wastewater treatment apparatus of the present invention is characterized in that an ion exchanger is arranged between the electrodes.
According to this feature, it is possible to increase the electron transfer efficiency between the pair of electrodes, so that it is possible to further improve the power generation efficiency and the desulfurization treatment efficiency.

Further, as one embodiment of the wastewater treatment apparatus of the present invention, a treatment tank for treating water to be treated and a power generation unit are provided after the treatment tank, and reduction of the water to be treated after being treated by the treatment tank is provided. It has the characteristic of introducing a sex substance into the power generation section to generate electricity.
In power generation using a microbial fuel cell, which is a conventional technique, by increasing the concentration of microorganisms required for wastewater treatment, mass transfer to the electrodes is further hindered by the microorganisms, so that wastewater treatment efficiency and power generation efficiency Is known to cause problems that are in a trade-off relationship.
According to this feature, by separating the treatment tank that treats the water to be treated and the power generation unit that generates power, wastewater treatment and power generation do not occur at one place at the same time, and the wastewater treatment efficiency and power generation efficiency are mutually exclusive. It is possible to avoid a trade-off relationship. In particular, by using the reducing substance generated by the treatment of the water to be treated as an electron donor, it is possible to perform not only power generation but also oxidation treatment (desulfurization treatment) of the reducing substance contained in the water to be treated after wastewater treatment. Since it is possible, it is possible to improve the wastewater treatment efficiency as a whole.

Further, one embodiment of the wastewater treatment apparatus of the present invention is characterized by providing a pH control means for dissolving a reducing substance in the water to be treated in the water to be treated.
According to this feature, it is possible to retain more reducing substances whose solubility in the water to be treated changes depending on the pH in the water to be treated, and to increase the amount of the reducing substances to be subjected to the reaction as an electron donor. Can be done. This makes it possible to increase the power generation efficiency and the desulfurization treatment efficiency.

Further, one embodiment of the wastewater treatment apparatus of the present invention is characterized in that a temperature control means for a reaction in which a reducing substance in the water to be treated is used as an electron donor is provided.
According to this feature, it is possible to control the temperature of a reaction using a reducing substance as an electron donor so as to improve the mass transfer rate and the reaction efficiency. This makes it possible to increase the power generation efficiency and the desulfurization treatment efficiency.

Further, the power generation device of the present invention for solving the above problems is a power generation device provided in a wastewater treatment device for treating water to be treated, and power generation is performed using a reducing substance in the water to be treated as an electron donor. It has characteristics.
In the power generation device of the present invention, by directly using the reducing substance contained in the water to be treated as an electron donor to generate power, the movement of the substance is not hindered by microorganisms, so that efficient power generation is possible. Become. In addition, the equipment can be downsized as compared with the power generation by the microbial fuel cell. Furthermore, by applying it to an existing wastewater treatment device, it becomes possible to update the wastewater treatment device to a wastewater treatment device capable of generating electricity without updating the entire wastewater treatment device on a large scale.

Further, the desulfurization treatment apparatus of the present invention for solving the above problems is a desulfurization treatment apparatus provided in a wastewater treatment apparatus for treating water to be treated, and desulfurization treatment using a reducing substance in the water to be treated as an electron donor. It has the characteristic of being used for.
The desulfurization treatment apparatus of the present invention enables efficient desulfurization without discharging hydrogen sulfide to the outside of the system by performing desulfurization treatment using the reducing substance contained in the water to be treated directly as an electron donor. Become. Further, by applying it to an existing wastewater treatment apparatus, it is possible to update the wastewater treatment apparatus to a wastewater treatment apparatus capable of performing desulfurization treatment without updating the entire wastewater treatment apparatus on a large scale.

Further, the power generation method of the present invention for solving the above problems is a power generation method in wastewater treatment for treating water to be treated, and includes a step of generating power using a reducing substance in the water to be treated as an electron donor. It has the feature.
In the power generation method of the present invention, by directly using the reducing substance contained in the water to be treated as an electron donor to generate power, the movement of the substance is not hindered by microorganisms, so that efficient power generation is possible. Become. In addition, the equipment can be downsized as compared with the power generation by the microbial fuel cell.

Further, the desulfurization method of the present invention for solving the above problems is a desulfurization method in wastewater treatment for treating water to be treated, and a step of subjecting a reducing substance in the water to be treated to the desulfurization treatment as an electron donor. It has the feature of being prepared.
In the desulfurization method of the present invention, the desulfurization treatment is carried out by directly using the reducing substance contained in the water to be treated as an electron donor, so that efficient desulfurization can be performed without discharging hydrogen sulfide to the outside of the system. ..

According to the present invention, as a technique associated with wastewater treatment, a wastewater treatment device, a power generation device, a desulfurization treatment device, a power generation method, and a desulfurization method that enable more efficient energy recovery / utilization or desulfurization treatment are provided. Can be done.

It is a schematic explanatory drawing of the wastewater treatment apparatus in the 1st Embodiment of this invention. It is a schematic explanatory drawing of the wastewater treatment apparatus in the 2nd Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the wastewater treatment apparatus in the 2nd Embodiment of this invention. It is a schematic explanatory drawing of the wastewater treatment apparatus in the 3rd Embodiment of this invention. It is a schematic explanatory drawing of the wastewater treatment apparatus in 4th Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the wastewater treatment apparatus in 4th Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the wastewater treatment apparatus in 4th Embodiment of this invention. It is a schematic explanatory drawing of the wastewater treatment apparatus in 5th Embodiment of this invention. It is a schematic explanatory drawing of the wastewater treatment apparatus in the 6th Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the wastewater treatment apparatus in the 6th Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the wastewater treatment apparatus in the 6th Embodiment of this invention.

Hereinafter, embodiments of the wastewater treatment apparatus, the power generation apparatus, the desulfurization treatment apparatus, the power generation method, and the desulfurization method according to the present invention will be described in detail with reference to the drawings. The power generation method and the desulfurization method in the present invention shall be replaced with the description of the operation of the wastewater treatment device, the power generation device and the desulfurization treatment device in the present invention.
Regarding the wastewater treatment apparatus, power generation apparatus, desulfurization treatment apparatus, power generation method and desulfurization method described in the embodiments, the wastewater treatment apparatus, power generation apparatus, desulfurization treatment apparatus, power generation method and desulfurization method according to the present invention will be described. It is merely exemplified in the above, and is not limited to this.

In the wastewater treatment apparatus of the present invention, the water to be treated is not particularly limited as long as it contains a reducing substance. The reducing substance may be contained in the water to be treated before being introduced into the wastewater treatment apparatus, and is generated as the treatment progresses in the wastewater treatment apparatus and exists in the water to be treated. There may be. Specific examples of water to be treated include industrial wastewater discharged from various factories such as food factories, chemical factories, and pulp and paper factories, and domestic wastewater such as sewage. In the following embodiments, the water to be treated, which produces a reducing substance through the treatment, will be mainly described, but the present invention is not limited thereto.

Further, in the present invention, the reducing substance contained in the water to be treated 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 is one that is more likely to emit electrons than the electron acceptor, that is, has a lower redox potential than the electron acceptor. For example, when oxygen is used as an electron acceptor, the reducing substance in the present invention may have an oxidation-reduction potential lower than that of oxygen, and such reducing substances include hydrogen sulfide, hydrogen, and ammonia. Can be mentioned.

[First Embodiment]
(Wastewater treatment equipment)
FIG. 1 is a schematic explanatory view showing a structure of a wastewater treatment apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the wastewater treatment device 1A in the present embodiment includes a treatment tank 2 and a power generation unit 3. Further, the wastewater treatment device 1A includes an introduction pipe L1 for introducing the water to be treated W into the treatment tank 2, a connection pipe L2 for connecting the treatment tank 2 and the power generation unit 3, and a discharge pipe for discharging the water to be treated W from the power generation unit 3. L3 is provided, and the water to be treated W is introduced into the power generation unit 3 after being treated by the treatment tank 2.

(Processing tank)
The treatment tank 2 is a tank for treating the water to be treated W.
The treatment performed in the treatment tank 2 is a treatment suitable for the treatment target contained in the water to be treated W, and is not particularly limited as long as the water to be treated W contains a reducing substance after the treatment. For example, biological treatment, chemical treatment (drug addition, ozone treatment, etc.) can be mentioned, but it is a biological treatment that does not involve the use and production of substances harmful to the human body and can be treated at a relatively low cost. It is desirable to do.
Further, as the biological treatment, for example, as a biological treatment in an anaerobic environment (anaerobic treatment), methane fermentation by acid-producing bacteria and methane-producing bacteria, and denitrification treatment in which sulfuric acid and nitrite are reduced by denitrifying bacteria. Examples thereof include sulfuric acid reduction treatment in which sulfuric acid is reduced by sulfuric acid reducing bacteria. In addition, as a biological treatment (aerobic treatment) in an aerobic environment, activated sludge treatment using activated sludge and the like can be mentioned. From the viewpoint of treatment cost and usefulness of the produced gas, anaerobic treatment is preferable as the biological treatment, and methane fermentation that produces methane is particularly preferable.

In the treatment tank 2, especially when methane fermentation is performed in the anaerobic treatment, hydrogen sulfide, hydrogen, ammonia and the like are generated in the water to be treated W in addition to methane. In addition, these products correspond to the reducing substance in this invention.

The water to be treated W treated in the treatment tank 2 is in a state of containing a reducing substance, and is introduced into the power generation unit 3 via the connection pipe L2.

(Power generation unit (power generation equipment / desulfurization treatment equipment))
The power generation unit 3 is for generating electricity by using the reducing substance in the water to be treated W as an electron donor. Further, the power generation unit 3 in the present embodiment can perform desulfurization treatment by using a sulfur-containing compound such as hydrogen sulfide as an electron donor among the reducing substances in the water to be treated W.
Hereinafter, the structure of the power generation unit 3 of the present embodiment will be described from the viewpoint of power generation. The details of the desulfurization treatment by the power generation unit 3 of this embodiment will be described later.

As shown in FIG. 1, the power generation unit 3 of the present embodiment is provided after the processing tank 2 and is provided so as to partition between the first cell 31a and the second cell 31b and the cells 31a and 31b. The ion exchanger 32 and the electrodes 33a and 33b arranged in the cells 31a and 31b, respectively, are provided. Here, the first cell 31a is formed so that the water W to be treated introduced from the treatment tank 2 via the connection pipe L2 comes into contact with the electrode 33a, and the electrode is arranged in the first cell 31a. 33a functions as an anode. On the other hand, the second cell 31b is formed so as to store or supply an electron acceptor, and the electrode 33b arranged in the second cell 31b functions as a cathode. Further, the electrodes 33a and 33b are connected to an external circuit by a conducting wire (not shown). As a result, in the power generation unit 3, the electric energy generated by the reducing substance acting as an electron donor can be recovered and utilized.

The first cell 31a may be any as long as it includes an electrode 33a and is formed so that the water W to be treated comes into contact with the electrode 33a, and the material and shape are not particularly limited. For example, as shown in FIG. 1, the water to be treated W introduced through the connection pipe L2 has a space that can be temporarily stored, and the water to be treated W after contacting the electrode 33a is discharged. For example, the discharge pipe L3 is provided. As a result, the reducing substance in the water to be treated W donates electrons to the electrode 33a as an electron donor, and then is quickly discharged through the discharge pipe L3.
The connection pipe L2 and / or the discharge pipe L3 may be provided with a flow rate adjusting mechanism such as a valve. This makes it possible to adjust the amount and flow velocity of the water W to be treated in contact with the electrode 33a and control the mass transfer rate with respect to the electrode 33a.

The water to be treated W discharged through the discharge pipe L3 can be discharged as it is as long as it satisfies the water quality that can be discharged into a river or the like. Further, a reaction tank 4 for further treating the water to be treated W may be provided after the discharge pipe L3. The reaction tank 4 is not particularly limited as long as it can be treated so that the water to be treated W has a water quality that can be discharged into a river. For example, an aeration tank, a pH adjustment tank, and the like can be mentioned.

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

Here, the form of the electron acceptor may be either a gas or a 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 a gas containing oxygen as a gas. Examples of the gas containing oxygen include those containing oxygen as a mixture such as air and those containing oxygen as an element constituting a compound such as carbon dioxide. When a gas is used as the electron acceptor, there are advantages that the treatment of the gas discharged after the reaction is unnecessary (or easy) and the cost for obtaining the gas can be reduced. In order to make the best use of these advantages, it is particularly preferable to use air as the electron acceptor.
In addition, as another example of the electron acceptor in this embodiment, for example, as a liquid, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous solution of potassium ferricyanide, and the like can be mentioned. When a liquid is used as the electron acceptor, the compound (oxidizing agent) having a high effect as the electron acceptor can be easily handled, so that there is an advantage that the power generation efficiency can be further improved. From the viewpoint of improving power generation efficiency, it is particularly preferable to use an aqueous potassium ferricyanide solution as the electron acceptor.

As the second cell 31b, for example, as shown in FIG. 1, a gas is supplied to the second cell 31b in order to supply a gaseous electron acceptor (oxygen, air, etc.) to the electrode 33b. It is possible to provide an electron acceptor supply port 34a for discharging the gas after the reaction and an electron acceptor discharge port 34b for discharging the gas after the reaction. Further, as another example of the second cell 31b, a space capable of storing a liquid is provided in the second cell 31b, and the electron receptor supply port 34a and the electron receptor discharge port 34b are used as the electron receptor supply port 34a and the electron receptor discharge port 34b, respectively. It is possible to provide a solution capable of supplying the solution and discharging the solution after the reaction. As a result, the electrons from the electrode 33a can be received by the electron receptor via the electrode 33b, and a current flows between the electrode 33a and the electrode 33b to generate electricity. Further, the electron acceptor after the reaction is rapidly discharged to the outside of the power generation unit 3 through the electron acceptor discharge port 34b.
The electron acceptor supply port 34a and / or the electron acceptor discharge port 34b may be provided with a flow rate adjusting mechanism such as a valve so that the concentration of the electron acceptor in the second cell 31b can be adjusted. Further, a control mechanism for controlling the flow rate adjusting mechanism may be provided 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, and to suppress a decrease in power generation efficiency.

In FIG. 1, one electron receiver supply port 34a and one electron receptor discharge port 34b are provided, but the present invention is not limited thereto. For example, a plurality of electron receptor supply ports 34a and a plurality of electron receptor discharge ports 34b may be provided. In particular, when a gas containing oxygen is used as the electron acceptor, water is generated by the reaction at the electrode 33b, as will be described later. Therefore, when a plurality of electron acceptor discharge ports 34b are provided, for example, a gas discharge port and a liquid discharge port may be provided separately.

The ion exchanger 32 may have a known structure capable of allowing ions to permeate, and is not particularly limited. In particular, a cation exchange membrane capable of permeating hydrogen ions generated at the electrode 33a (anode side) can be mentioned. As a result, 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 power generation efficiency can be improved. Further, it is more preferable that the ion exchanger 32 has low oxygen permeability. As a result, the electron acceptor (oxygen) supplied to the electrode 33b (cathode side) is suppressed from moving to the electrode 33a side, and the reaction efficiency of the electron donor at the electrode 33a is suppressed from being lowered by oxygen. Is possible.
Note that, in FIG. 1, the ion exchanger 32 is provided as a separate body from the electrode 33a and the electrode 33b, but is not limited thereto. For example, the material having an ion exchange ability and the electrode 33a and / or the electrode 33b may be integrated. As a result, the entire power generation unit 3 can be miniaturized, and the time required for maintenance work can be shortened.

The electrode 33a is an electrode that recovers electrons from the reducing substance in the water W to be treated, and functions as a so-called anode. Further, the electrode 33a in the present embodiment is arranged in the first cell 31a so as to come into contact with the water to be treated W after being treated in the treatment tank 2.

The electrode 33a may be any as long as it functions as an anode, and the material and shape are not particularly limited. 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 at the electrode 33a, and the like. Examples of the material of the electrode 33a include carbon and metals (stainless steel, platinum, copper, etc.) widely used as electrode materials in the electrochemical field. Examples of the shape of the electrode 33a include a flat plate shape, a rod shape, and a mesh shape.

The electrode 33a in this embodiment does not bring microorganisms into contact or support on the surface of the electrode. Therefore, the mass transfer of the reducing substance is not hindered by the microorganism, and the reaction efficiency as an electron donor (the mass transfer rate of the reducing substance with respect to the electrode 33a) can be improved, and the power generation efficiency can be improved. Can be done.
Further, the electrode 33a in the present embodiment does not recover the electrons generated by the metabolism of the microorganism, but directly recovers the electrons from the reducing substance. Therefore, the metabolism of microorganisms does not become rate-determining, the reaction efficiency as an electron donor (electron recovery rate at the electrode 33a) is improved, and the power generation efficiency can be improved.

Further, the electrode 33a in the present embodiment does not need to be processed so that the structure of the electrode 33a is suitable for retaining microorganisms, and the cost for producing the electrode 33a can be reduced. Further, in consideration of the amount of microorganisms retained on the electrode 33a and the reaction efficiency by the microorganisms, it is not necessary to increase the size of the electrode 33a, so that the equipment related to the wastewater treatment apparatus 1 can be miniaturized.

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

The electrode 33b may be any as long as it functions as a cathode, and the material and shape are not particularly limited. 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 at the electrode 33b, and the like. Examples of the material of the electrode 33b include carbon and metals (stainless steel, platinum, copper, etc.) widely used as electrode materials in the electrochemical field. Examples of the shape of the electrode 33b include a flat plate shape, a rod shape, and a mesh shape.

When the electron acceptor supplied into the second cell 31b is a gas (air), one surface of the electrode 33b is in contact with the gas, but the other surface is in contact with the water W to be treated. Therefore, it is preferable that the electrode 33b has a form suitable as a so-called air cathode. Suitable forms for the air cathode include, for example, having both gas permeable and impermeable properties. By forming the electrode 33b so as to have gas permeability, it is possible to effectively react the gas, which is an electron acceptor, with the electrode 33b. Further, since the electrode 33b is impermeable to water, it is possible to prevent the water W to be treated in the first cell 31a from passing through the electrode 33b and flowing into the second cell 31b. Specific examples of such an electrode 33b include one made of carbon fiber, one coated with a material having gas permeability and impermeableness on the surface of a metal mesh, or one subjected to surface treatment such as laminating a film. Can be mentioned. The term "water impermeable" as used herein means that water does not pass through, and for example, the electrode 33b is also provided with impermeable property for making the electrode 33b waterproof, water repellent, hydrophobic, or watertight. It is included.

The wastewater treatment apparatus 1A in the present embodiment uses the reducing substance in the water to be treated W as an electron donor, and performs power generation or desulfurization treatment by an electrochemical reaction (electrode reaction). Generally, when an electrochemical reaction is carried out, there arises a problem that the efficiency of the electrochemical reaction is lowered due to the movement of electrons to a place other than the place where the electrochemical reaction is actually carried out (power generation unit 3). Therefore, it is preferable that the wastewater treatment apparatus 1A in the present embodiment is insulated except for the portion where the electrochemical reaction is performed (power generation unit 3). Specific examples of the insulation treatment include, for example, installing the treatment tank 2 and the reaction tank 4 above the insulator, configuring the outer wall or the inner wall of the treatment tank 2 and the reaction tank 4 with an insulator, and treating. Examples thereof include coating the outer wall or inner wall of the tank 2 and the reaction tank 4 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.

In the wastewater treatment apparatus 1A according to the above-described embodiment, power generation or desulfurization treatment can be performed by a reaction using the reducing substance in the water to be treated W as an electron donor.
Hereinafter, the power generation and desulfurization treatment in the wastewater treatment apparatus 1A will be described in detail.

(Power generation and desulfurization in wastewater treatment equipment)
Based on FIG. 1, a reaction and a process related to power generation and desulfurization treatment in the wastewater treatment apparatus 1A according to the first embodiment of the present invention will be described. In the reaction and process related to power generation in the wastewater treatment apparatus of the present embodiment, the reducing substance produced by anaerobic treatment of the water to be treated W is used as an electron donor and air (oxygen) is used as an electron acceptor. It is to explain. In particular, those using hydrogen sulfide as an electron donor correspond to the reactions and steps related to the desulfurization treatment in the wastewater treatment apparatus of this embodiment.
The description of the reaction and the process based on FIG. 1 shows an example of power generation and desulfurization treatment in the present embodiment, and is not limited thereto. Further, the following description describes the reaction and process related to the processing tank 2 to the power generation unit 3, and describes the reaction and process related to other configurations (introduction pipe L1, discharge pipe L3, reaction tank 4, etc.). The explanation is omitted. Further, 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 process sequence.

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

The water W to be treated, which has been treated in the treatment tank 2 and contains a reducing substance, is introduced into the first cell 31a in the power generation unit 3 via the connection pipe L2 (step S2). Here, when the reducing substance (hydrogen, hydrogen sulfide, ammonia, etc.) comes into contact with the electrode 33a, the reducing substance functions as an electron donor, and electrons are donated 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).

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

As shown in the formulas 1 and 2, in the reaction R1, the hydrogen sulfide contained in the water to be treated W after being treated in the treatment tank 2 donates electrons to the electrode 33a, and the hydrogen sulfide itself is oxidized. By doing so, it becomes harmless and odorless. Therefore, the wastewater treatment apparatus of the present embodiment can perform desulfurization treatment and deodorization treatment as well as power generation. Reducing substances (ammonia, etc.), which are harmful substances and odorous substances other than hydrogen sulfide, also function as electron donors, and the reaction proceeds to make 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 conducting wire (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 32 (reaction R3).

On the other hand, air (oxygen) is introduced into the second cell 31b as an electron acceptor from the electron acceptor supply port 34a (step S3). Here, the electron receptor moves through the electrode 33b to receive the electrons transferred from the electrode 33a to the electrode 33b by the reaction R2. At this time, the hydrogen ion that has moved to the second cell 31b side via the ion exchanger 32 also reacts with the electron acceptor (oxygen) by the reaction R3. The reaction (reaction R4) at the electrode 33b at this time is represented by the following reaction formula (formula 3).

Based on the above-mentioned reactions R1 to R4 and steps S1 to S3, a current flows between the electrodes 33a and 33b. As a result, the reaction using the reducing substance in the water to be treated W as an electron donor proceeds, and the power generation and desulfurization treatment in the wastewater treatment apparatus 1A of the present embodiment are performed.
Further, the electric energy obtained by power generation can be recovered and used through an external circuit connected to the electrode 33a and the electrode 33b. The use of electrical energy is not particularly limited. For example, it may be used for driving the equipment of the wastewater treatment device, or may be used outside the wastewater treatment device.

As described above, by using the wastewater treatment apparatus of the present embodiment, it is possible to improve the power generation efficiency and the desulfurization treatment efficiency without the inhibition of mass transfer by microorganisms and the rate-determining step based on the metabolic rate of microorganisms. In addition, the equipment can be downsized as compared with the power generation by the microbial fuel cell. Further, it is possible to carry out an efficient desulfurization treatment without separately providing equipment for the desulfurization treatment.

In power generation using a microbial fuel cell, which is a conventional technique, by increasing the concentration of microorganisms required for wastewater treatment, mass transfer to the electrodes is further hindered by the microorganisms, so that wastewater treatment efficiency and power generation efficiency Is known to cause problems that are in a trade-off relationship. On the other hand, in the wastewater treatment apparatus and the power generation method of the present embodiment, wastewater treatment and power generation can be performed separately. Therefore, in the wastewater treatment apparatus and the power generation method of the present embodiment, the wastewater treatment efficiency and the power generation efficiency do not have a trade-off relationship, and efficient power generation is possible.

The configuration of the power generation unit 3 in the present embodiment can be independent as the power generation device or desulfurization treatment device according to the present invention. This power generation device or desulfurization treatment device can be applied to an existing wastewater treatment device. Thereby, the wastewater treatment apparatus of the present invention can be provided without updating the entire wastewater treatment apparatus on a large scale. Further, it is possible to provide a power generation method and a desulfurization method using this wastewater treatment device.

[Second Embodiment]
FIG. 2 is a schematic explanatory view showing a wastewater treatment apparatus according to the second embodiment of the present invention. Further, FIG. 3 is a schematic explanatory view showing another aspect of the wastewater treatment apparatus according to the second embodiment of the present invention.
In the wastewater treatment apparatus 1B according to the second embodiment, the treatment tank 2 includes an acid generation tank 21 and a methane fermentation tank 22. Further, the power generation unit 3 is provided on the circulation flow path provided in the treatment tank 2 (acid generation tank 21 and methane fermentation tank 22). Here, the wastewater treatment devices 1B shown in FIGS. 2 and 3 show different installation locations of the power generation unit 3. The description of the same configuration as that of the first embodiment will be omitted.

In the wastewater treatment apparatus 1B of the present embodiment, as shown in FIGS. 2 and 3, the treatment tank 2 includes an acid generation tank 21 and a methane fermentation tank 22 connected by a connection pipe L4, and acid is generated by a circulation pipe L5. A circulation flow path is formed between the tank 21 and the methane fermentation tank 22, and a circulation flow path in the methane fermentation tank 22 is formed by the circulation pipe L6.
In the wastewater treatment device 1B shown in FIG. 2, the power generation unit 3 is provided on the circulation pipe L5. On the other hand, in the wastewater treatment device 1B shown in FIG. 3, the power generation unit 3 is provided on the circulation pipe L6.

The treatment tank 2 in this embodiment includes an acid generation tank 21 and a methane fermentation tank 22. Further, the acid generation tank 21 and the methane fermentation tank 22 are reaction tanks for anaerobically treating the water to be treated W by the microorganisms housed therein. The acid generation tank 21 and the methane fermentation tank 22 preferably have a ceiling and form a closed space in order to maintain anaerobic conditions.

The acid generation tank 21 is a solid or high molecular organic substance such as sugar, protein and oil due to the acid-producing bacteria (mainly anaerobic acid-producing bacteria) contained therein with respect to the water W to be treated introduced by the introduction pipe L1. Is decomposed to carry out an acid production treatment to produce monosaccharides, amino acids, lower fatty acids and acetic acid. The water to be treated W treated in the acid generation tank 21 is supplied to the methane fermentation tank 22 via the connecting pipe L4.

It should be noted that the acid generation tank 21 is provided with an internal water temperature adjusting means, a means for adding a pH adjusting agent, and a means for adding metals such as nitrogen, phosphorus, cobalt and nickel which are nutrient sources required by bacteria. May be (not shown).

The methane fermentation tank 22 performs a methane fermentation treatment that produces methane from monosaccharides, amino acids, lower fatty acids, acetic acid, etc. contained in the water to be treated W treated in the acid generation tank 21 supplied by the connecting pipe L4. is there. The methane fermentation treatment is performed in an anaerobic atmosphere without dissolved oxygen by methanogens retained by the floating method, fixed bed method, fluidized bed method, UASB (Upflow Anaerobic Sludge Blanket) method, EGSB (Expanded Granular Sludge Bed) method, etc. It is what you do.

In the methane fermentation tank 22, a granule layer in which anaerobic bacteria suitable for anaerobic treatment are present is formed. Then, when the water to be treated W is introduced into the methane fermentation tank 22 from the acid generation tank 21, methane fermentation is performed by the anaerobic bacteria contained in the granule layer. As a result, in the methane fermentation tank 22, a gas containing methane and carbon dioxide as main components is generated, and water W to be treated containing a reducing substance is generated. A settler 23, which is a gas-solid-liquid separation means, may be provided inside the methane fermentation tank 22. The gas generated in the methane fermentation tank 22 is released or recovered outside the tank (not shown). Further, the water to be treated W generated in the methane fermentation tank 22 is discharged to the outside of the treatment system via the discharge pipe L7.

The methane fermentation tank 22 can be further provided with various incidental equipment. For example, it may be provided with an internal water temperature adjusting means, a means for adding a pH adjusting agent, and a means for adding metals such as nitrogen, phosphorus, cobalt and nickel which are nutrient sources required by bacteria (not shown). ..

It is preferable that the methane fermentation tank 22 is provided with means for recovering, purifying and storing the methane gas among the gases generated in the methane fermentation tank 22. As a result, in addition to the power generation by the power generation unit 3, methane gas, which is a useful energy source, can be recovered from the water to be treated W and effectively used.
Further, the methane fermentation tank 22 is provided with means for recovering, purifying and storing carbon dioxide gas among the gases generated in the methane fermentation tank 22, and is a second cell from the electron acceptor supply port 34a in the power generation unit 3. A means capable of introducing carbon dioxide gas into 31b may be provided. As a result, carbon dioxide gas can be effectively used as an electron acceptor, and the supply cost of the electron acceptor can be reduced.

Further, the methane fermentation tank 22 in this embodiment includes a circulation pipe L5 and / or a circulation pipe L6. The circulation pipe L5 supplies the water W to be treated at the upper part of the methane fermentation tank 22 to the acid generation tank 21, and forms a circulation flow path between the acid generation tank 21 and the methane fermentation tank 22. Further, the circulation pipe L6 supplies the water W to be treated in the upper part of the methane fermentation tank 22 to the lower part of the methane fermentation tank 22, and a circulation flow path in the methane fermentation tank 22 is formed.

The power generation unit 3 in the present embodiment is provided on the circulation flow path formed by the circulation pipe L5 and the circulation pipe L6.

As shown in FIG. 2, in the case where the power generation unit 3 is provided on the circulation pipe L5, the water to be treated W from the methane fermentation tank 22 is supplied to the first cell 31a, and the water to be treated after the reaction at the electrode 33a is provided. W is supplied to the acid generation tank 21 via the circulation pipe L5. At this time, the water W to be treated after the reaction at the electrode 33a becomes a solution having an increased hydrogen ion concentration and an acidic pH as shown in Formulas 1 and 2. In general, it is known that the pH in the acid generation tank 21 is preferably closer to acidity in order for the reaction in the acid generation tank 21 to proceed favorably. Therefore, the water W to be treated discharged from the power generation unit 3 to the acid generation tank 21 may be used as a pH adjuster for proceeding the reaction in the acid generation tank 21 under favorable conditions. Further, a flow rate adjusting mechanism such as a valve or an adsorption processing means such as activated carbon may be provided on the circulation pipe L5 on the acid generation tank 21 side. As a result, when the pH range in the acid generation tank 21 deviates from the appropriate range due to the inflow of the water to be treated W discharged from the power generation unit 3 into the acid generation tank 21, the inflow amount into the water to be treated W is increased. It is possible to control and control the pH of the water to be treated W, and it is possible to suppress inhibition of the reaction of the acid generation tank 21.

Further, as shown in FIG. 3, in the case where the power generation unit 3 is provided on the circulation pipe L6, the water to be treated W from the upper part of the methane fermentation tank 22 is supplied to the first cell 31a, and after the reaction at the electrode 33a. The water to be treated W is supplied to the lower part of the methane fermentation tank 22 via the circulation pipe L6. At this time, the water W to be treated after the reaction at the electrode 33a becomes a solution in which the concentration of dissolved hydrogen sulfide is reduced as shown in the formulas 1 and 2. It is known that the metabolism of methane bacteria contained in the granule layer in the methane fermentation tank 22 is inhibited by hydrogen sulfide. Therefore, the water to be treated W discharged from the power generation unit 3 to the lower part of the methane fermentation tank 22 has an effect that it can be circulated in the methane fermentation tank 22 without inhibiting the methane fermentation.

As described above, in the wastewater treatment apparatus 1B in the present embodiment, the treatment tank 2 is composed of the acid generation tank 21 and the methane fermentation tank 22, so that the conditions suitable for each treatment (acid generation treatment and methane fermentation) are suitable. Since the wastewater treatment can be performed below, the wastewater treatment efficiency can be further improved.
Further, in the wastewater treatment device 1B in the present embodiment, the installation location of the power generation unit 3 is set on the circulation flow path provided in the treatment tank 2 (acid generation tank 21 and methane fermentation tank 22), so that the first cell 31a After the reaction, the water to be treated W supplied to the side is supplied to the treatment tank 2 (acid generation tank 21 or methane fermentation tank 22) again. Therefore, since the water to be treated W is repeatedly treated, it is possible to improve the wastewater treatment with respect to the water to be treated W discharged from the power generation unit 3. Further, by reintroducing the water to be treated W discharged from the power generation unit 3 into the treatment tank 2 (acid generation tank 21 or methane fermentation tank 22) at this time, the reaction in the treatment tank 2 can proceed under favorable conditions. It also has the effect of making it possible.

Since the power generation unit 3 in the present embodiment is provided on the circulation flow path that circulates the water to be treated W in the upper part of the methane fermentation tank 22, the amount of microorganisms present in the water to be treated W in the circulation flow path is relatively large. It is presumed that there are few. Therefore, it is possible to suppress the influence of microorganisms on the reaction in the power generation unit 3 and improve the power generation efficiency.

In the wastewater treatment device 1B of the present embodiment, the water to be treated W discharged through the discharge pipe L7 can be discharged as it is as long as it satisfies the water quality that can be discharged to a river or the like. is there. Further, the reaction tank 4 shown in the first embodiment may be provided after the discharge pipe L7. As a result, the treatment efficiency for the water to be treated W can be further improved by undergoing the treatment by the reaction tank 4, and the water to be treated W can be discharged from the wastewater treatment device 1B to the outside of the system.

Further, in the wastewater treatment apparatus 1B of the present embodiment, it is possible to perform power generation and desulfurization treatment by the same steps as in the first embodiment.

[Third Embodiment]
FIG. 4 is a schematic explanatory view showing a wastewater treatment apparatus according to the third embodiment of the present invention.
In the wastewater treatment device 1C according to the third embodiment, as shown in FIG. 4, in the wastewater treatment device 1A according to the first embodiment, the reaction tank 4 is an aeration tank 41, and the aeration tank 41 and the power generation unit are the first. The electron acceptor supply port 34a provided in the cell 31 of 2 is connected by the connection pipe L8. The description of the same configuration as that of the first embodiment will be omitted.

The wastewater treatment device 1C in the present embodiment supplies the treated water W1 in the aeration tank 41 to the power generation unit 3 and uses it as an electron acceptor in the power generation unit 3. The treated water W1 other than that supplied to the power generation unit 3 by the connection pipe L8 is discharged to the outside of the system.

In the aeration tank 41, the aeration device 42 aerates the water W to be treated introduced into the tank with a gas containing oxygen (oxygen, air, etc.), and aerobic treatment by aerobic microorganisms or oxidation by dissolved oxygen. It promotes the reaction.
As shown in FIG. 4, the aeration tank 41 in the present embodiment introduces the water to be treated W discharged from the first cell 31a of the power generation unit 3 and aerates the introduced water W to be treated. Not limited to things. As another example of the aeration tank 41, for example, the one in which the water to be treated W is directly introduced from the treatment tank 2 to perform aeration can be mentioned.

The aeration device 42 is not particularly limited as long as it can supply a gas containing oxygen to the water to be treated W in the aeration tank 41. For example, those widely used in aeration treatment include those composed of a combination of a blower and an aeration tube.

Since a gas containing oxygen is introduced into the aeration tank 41 by the aeration device 42, the treated water W1 in the aeration tank 41 is a liquid containing dissolved oxygen. Therefore, the treated water W1 introduced into the second cell 31b of the power generation unit 3 via the connection pipe L8 becomes an electron acceptor in the power generation unit 3. As a result, it is possible to generate electricity by effectively utilizing what is generated in the treatment process in the wastewater treatment device 1C.

The treated water W1 after being used as an electron acceptor in the power generation unit 3 is discharged from the electron acceptor discharge port 34b. At this time, the discharged treated water W1 can be discharged as it is as long as it satisfies the water quality that can be discharged into a river or the like. Further, the discharged treated water W may be returned to the aeration tank 41 and the aeration treatment may be performed again. This makes it possible to more reliably control the water quality of the treated water W1 discharged to the outside of the system.

As described above, the wastewater treatment apparatus 1C in the present embodiment can utilize what is generated in the treatment step proceeding in the wastewater treatment apparatus 1C as an electron donor and an electron acceptor in the power generation unit 3, and in particular. It is possible to reduce the running cost related to power generation.

Further, in the wastewater treatment apparatus 1C of the present embodiment, it is possible to perform power generation and desulfurization treatment by the same steps as in the first embodiment.

[Fourth Embodiment]
FIG. 5 is a schematic explanatory view showing a wastewater treatment apparatus according to a fourth embodiment of the present invention. 6 and 7 are schematic explanatory views showing another aspect of the wastewater treatment apparatus according to the fourth embodiment of the present invention.
As shown in FIGS. 5 to 7, the wastewater treatment apparatus 1D according to the fourth embodiment receives the treated water W discharged from the first cell 31a in the wastewater treatment apparatus 1A according to the first embodiment. An insulation mechanism 5 for insulating is provided. The description of the same configuration as that of the first embodiment will be omitted. Further, in FIGS. 5 to 7, it is an enlarged explanatory view of the vicinity of the power generation unit 3 of the wastewater treatment device 1D, and the configuration of the treatment tank 2 and the reaction tank 4 is not shown.

As described above, when the electrochemical reaction (electrode reaction) is carried out, it is preferable to insulate the parts other than the part where the electrochemical reaction is carried out (power generation unit 3).
The wastewater treatment device 1D in the present embodiment is provided with an insulation mechanism 5 that insulates the water to be treated W. As a result, the electrons generated by the power generation unit 3 are prevented from flowing except between the electrodes 33a and 33b, and the electrode reaction efficiency is improved. As a result, the power generation efficiency and the desulfurization treatment efficiency can be improved. The wastewater treatment device 1D in the present embodiment may also insulate the structures (treatment tanks and pipes) constituting the wastewater treatment device as shown in the first embodiment. As a result, a further insulating effect can be obtained, and the power generation efficiency in the power generation unit 3 can be improved.

The insulation mechanism 5 is not particularly limited as long as it can insulate the water W to be treated. Examples of the means for insulating the water to be treated W by the insulating mechanism 5 include eliminating the electrical contact (liquid entanglement) between the electrode 33a of the power generation unit 3 and the water to be treated W (liquid entanglement) or shortening the liquid entanglement time. Examples of such a liquid entanglement eliminating means or a means for shortening the liquid entanglement time include a means for discontinuous (intermittent) flow of the water to be treated W and an insulator such as air to be interposed in the water to be treated W. Means, or a combination of these means, and the like can be mentioned.

FIG. 5 is a schematic explanatory view showing the insulation mechanism 5 of the wastewater treatment device 1D in the present embodiment.
As shown in FIG. 5, the insulation mechanism 5 in the present embodiment includes a storage tank 51 and a watering means 52 for sprinkling the water to be treated W into the storage tank 51.

The storage tank 51 stores the water to be treated W discharged from the power generation unit 3 via the discharge pipe L3. The storage tank 51 is not particularly limited as long as it can store the water to be treated W. Since the air existing in the storage tank 51 functions as an insulator against the water to be treated W, the water level in the storage tank 51 should be adjusted so that the water level in the storage tank 51 does not reach the maximum (full state). Is preferable. This makes it possible to further enhance the insulating effect of the water to be treated W.

The watering means 52 discharges the water to be treated W in the form of water droplets. Since the air in the storage tank 51 is interposed as an insulator between the water droplets of the water to be treated W discharged by the water sprinkling means 52, it is possible to eliminate the liquid entanglement or shorten the liquid entanglement time.
The watering means 52 is not particularly limited as long as it can form the water W to be treated into water droplets. As a specific example of the water sprinkling means 52, for example, as shown in FIG. 5, a structure connected to the discharge port of the discharge pipe L3 and having a plurality of holes such as a shower head may be provided. Further, as another example of the water sprinkling means 52, a flat plate-shaped structure facing the discharge port of the discharge pipe L3 and separated by a predetermined distance may be provided in the storage tank 51.

FIG. 6 is a schematic explanatory view showing another aspect of the insulation mechanism 5 of the wastewater treatment device 1D in the present embodiment.
As shown in FIG. 6, the insulation mechanism 5 in the present embodiment includes a storage tank 53 and a water discharge means 54 that intermittently discharges the water to be treated W in the storage tank 53.

The storage tank 53 stores the water to be treated W discharged from the power generation unit 3 via the discharge pipe L3. The storage tank 53 is not particularly limited as long as it can store the water to be treated W.
The water discharge means 54 is not particularly limited as long as it can intermittently discharge the water to be treated W in the storage tank 53. As the water discharge means 54, an electromagnetic valve 54a is provided in the water discharge pipe L9 that discharges the water to be treated W from the storage tank 53, and the solenoid valve 54a is periodically opened and closed. As a result, the flow of the water to be treated W discharged from the storage tank 53 through the water discharge pipe L becomes intermittent, so that it is possible to eliminate the liquid entanglement of the water to be treated W or shorten the liquid entanglement time. is there.

FIG. 7 is a schematic explanatory view showing another aspect of the insulation mechanism 5 of the wastewater treatment device 1D in the present embodiment.
As shown in FIG. 7, the insulation mechanism 5 in the present embodiment has a pipe diameter reducing means 55 for narrowing a part of the pipe diameter of the discharge pipe L3 and an upstream of the pipe diameter reducing means 55 on the discharge pipe L3. A gas supply means 56 for supplying gas into the discharge pipe L3 from the side is provided.

The pipe diameter reducing means 55 is not particularly limited as long as it can partially reduce the pipe diameter of the discharge pipe L3. Examples of the pipe diameter reducing means 55 include a structure in which a structure for narrowing the pipe diameter is provided in the discharge pipe L3, a structure in which the structure is inserted from the outside of the discharge pipe L3, and a discharge by pressing from the outside of the discharge pipe L3. Deformation of the pipe L3 itself and the like can be mentioned.
The gas supply means 56 is not particularly limited as long as it can supply gas into the discharge pipe L3 from the upstream side of the pipe diameter reducing means 55. Examples of the gas supply means 56 include those that supply air into the discharge pipe L3 by using a pump or the like that applies pressure to the air to blow air. The gas supplied by the gas supply means 56 is not limited to air. For example, in addition to air, biogas generated in the treatment tank 2 and exhaust gas after combustion of the biogas may be used.

By supplying gas (air) from the upstream side of the pipe diameter reducing means 55 by the gas supply means 56, only the gas intermittently flows into the portion narrowed by the pipe diameter reducing means 55, and only the gas flows in intermittently in the discharge pipe L3. It is possible to make the flow of the water W to be treated discontinuous. This makes it possible to eliminate the liquid entanglement of the water to be treated W in the discharge pipe L3 or shorten the liquid entanglement time.

As described above, the wastewater treatment device 1D in the present embodiment can eliminate the liquid entanglement or shorten the liquid entanglement time between the power generation unit 3 and the water to be treated W by providing the insulation mechanism 5 that insulates the water to be treated W. It becomes. As a result, it is possible to prevent the electrons generated in the power generation unit 3 from flowing outside between the electrodes 33a and 33b and lower the electrochemical reaction (electrode reaction) efficiency, and improve the power generation efficiency and the desulfurization treatment efficiency.

Further, in the wastewater treatment apparatus 1D of the present embodiment, it is possible to perform power generation and desulfurization treatment by the same steps as in the first embodiment.

[Fifth Embodiment]
FIG. 8 is a schematic explanatory view showing a wastewater treatment apparatus according to the fifth embodiment of the present invention.
As shown in FIG. 8, the wastewater treatment apparatus 1E according to the fifth embodiment provides the pH control means 6 between the methane fermentation tank 22 and the power generation unit 3 in the wastewater treatment apparatus 1B according to the second embodiment. It is a thing. The wastewater treatment device 1E in the present embodiment is shown to have the same configuration as the wastewater treatment device 1B shown in FIG. 3, and the description of the same as the configuration of the second embodiment is omitted. To do.

As described above, in the methane fermentation tank 22, the acid-oriented water to be treated W is introduced from the acid generation tank 21, and the methane fermentation treatment proceeds. At this time, hydrogen sulfide, which is a reducing substance, is generated in the methane fermentation tank 22 as the methane fermentation process progresses.
On the other hand, it is known that the solubility of hydrogen sulfide in a solution changes according to the pH, and the solubility is increased by making the pH 6 or higher closer to alkali, and the release of hydrogen sulfide to the outside of the solution is suppressed.
Therefore, by adjusting the pH of the water to be treated W, the solubility of the reducing substance (particularly hydrogen sulfide) can be changed, and the reducing substance in the water to be treated W can be dissolved in the water to be treated W. Become.

In the wastewater treatment apparatus 1E of the present embodiment, the pH of the water to be treated W after the methane fermentation treatment is adjusted by providing the pH control means 6, the gasification of hydrogen sulfide is suppressed, and the water to be treated is sulfided. It becomes possible to dissolve hydrogen. As a result, the amount of the reducing substance in the water to be treated W is increased, and the amount of the electron donor to be subjected to the reaction is increased, so that the power generation efficiency and the desulfurization treatment efficiency in the power generation unit 3 can be improved.

The pH control means 6 is not particularly limited as long as it can adjust the pH of the water to be treated W and dissolve the reducing substance in the water to be treated W in the water to be treated W.
As shown in FIG. 8, the pH control means 6 includes a storage unit 61 for storing the pH adjuster, an addition unit 62 for adding the pH adjuster to the water to be treated W, and a pH detection unit 63. Can be mentioned.

The storage unit 61 is not particularly limited as long as it can store the pH adjuster. Further, the pH adjusting agent stored in the storage unit 61 is not particularly limited, and it is preferable to select the type of the pH adjusting agent according to the pH dependence of the solubility of the reducing substance. For example, when the reducing substance is hydrogen sulfide, a pH adjusting agent that makes the pH of the water to be treated W closer to alkaline may be used in order to increase the solubility of hydrogen sulfide. More specifically, as the pH adjuster, hydroxides such as sodium hydroxide and calcium hydroxide may be used. Further, as the pH adjuster, an acid such as hydrochloric acid or sulfuric acid may be used.

The addition unit 62 is for adding the pH adjuster in the storage unit 61 to the water to be treated W. Further, as shown in FIG. 8, the addition portion 62 in this embodiment is provided on the circulation pipe L6.
The addition unit 62 in the present embodiment is not particularly limited as long as it has a structure capable of adding a pH adjuster to the water to be treated W in the circulation pipe L6. For example, a pipe that connects the circulation pipe L6 and the storage unit 61 and has a flow rate adjusting function may be mentioned.

The arrangement position of the addition portion 62 is not particularly limited, but it is preferable to select a location where the pH of the water to be treated W can be adjusted and the solubility of the reducing substance can be appropriately controlled. For example, as shown in FIG. 8, the addition unit 62 may be provided on the circulation pipe L6 that circulates the water to be treated W from the power generation unit 3 to the methane fermentation tank 22 side. At this time, the circulation pipe L6 is connected to the middle stage of the methane fermentation tank 22. As a result, in the lower part of the methane fermentation tank 22, the methane fermentation treatment proceeds in an environment closer to acidity, while the pH adjuster added by the addition part 62 is transferred to the middle part of the methane fermentation tank 22 via the circulation pipe L6. By introducing the methane fermentation tank 22, the pH of the water to be treated W in the upper part of the methane fermentation tank 22 becomes closer to alkaline, and the hydrogen sulfide generated in the methane fermentation tank 22 is more reliably dissolved in the water to be treated W. , Can be introduced into the power generation unit 3.

Further, as shown in FIG. 8, a pH detection unit 63 is provided on the circulation pipe L6 that circulates the water to be treated W from the methane fermentation tank 22 to the power generation unit 3 side, and an addition unit is provided according to the detection result of the pH detection unit 63. It is preferable to control the amount of the pH adjuster added from 62. As a result, the pH of the water to be treated W can be easily adjusted, and the pH can be adjusted at an appropriate timing. As a result, the amount of the reducing substance in the water to be treated W introduced into the power generation unit 3 is increased, and the amount of the electron donor to be subjected to the reaction is increased, thereby increasing the power generation efficiency and the desulfurization treatment efficiency in the power generation unit 3. It becomes possible.
The control means of the addition unit 62 according to the detection result of the pH detection unit 63 is not particularly limited. For example, the operator visually confirms the detection result of the pH detection unit 63 and manually operates the addition unit 62 according to the result, or the pH detection unit 63 and the addition unit 62 are connected in a controllable manner to be covered. Examples include automating the pH detection of the treated water W and the addition of a pH adjuster.

The structure of the wastewater treatment device 1E provided with the pH adjusting means 6 is not limited to the structure of the wastewater treatment device 1B shown in FIG. As another example of the wastewater treatment device 1E provided with the pH adjusting means 6, for example, on the connection pipe L2 of the wastewater treatment device 1A shown in FIG. 1 or on the circulation pipe L5 of the wastewater treatment device 1B shown in FIG. , The addition part 62 may be arranged. This makes it possible to adjust the pH of the water to be treated W introduced from the treatment tank 2 (methane fermentation tank 22) into the power generation unit 3 and increase the amount of the reducing substance introduced into the power generation unit 3.

As described above, the wastewater treatment apparatus 1E in the present embodiment is provided with a pH control means for dissolving the reducing substance in the water to be treated, so that the solubility in the water to be treated is determined according to the pH. It is possible to retain more reducing substances in the water to be treated, and it is possible to increase the amount of reducing substances to be subjected to the reaction as an electron donor. This makes it possible to increase the power generation efficiency and the desulfurization treatment efficiency.

Further, in the wastewater treatment apparatus 1E of the present embodiment, it is possible to perform power generation and desulfurization treatment by the same steps as in the first embodiment.

[Sixth Embodiment]
FIG. 9 is a schematic explanatory view showing a wastewater treatment apparatus according to the sixth embodiment of the present invention. 10 and 11 are schematic explanatory views showing another aspect of the wastewater treatment apparatus according to the sixth embodiment of the present invention.
As shown in FIGS. 9 to 11, the wastewater treatment apparatus 1F according to the sixth embodiment is provided with the temperature control means 7 in the wastewater treatment apparatus 1B according to the second embodiment. The wastewater treatment device 1F in the present embodiment has the same configuration as the wastewater treatment device 1B shown in FIG. 3, and the description of the same configuration as that in the second embodiment will be omitted. To do.

As described above, in the power generation unit 3, an electrode reaction using a reducing substance in the water to be treated as an electron donor is proceeding. Further, in general, it is known that in the electrode reaction, the mass transfer rate and the reaction efficiency are improved by increasing the temperature.
Therefore, by controlling the temperature related to the electrode reaction in the wastewater treatment apparatus 1F, the efficiency of the electrode reaction can be improved, and the power generation efficiency and the desulfurization treatment efficiency can be improved.

In the wastewater treatment device 1F in the present embodiment, the temperature of the power generation unit 3 can be adjusted by providing the temperature control means 7. This makes it possible to increase the efficiency of the reaction using the reducing substance as the electron donor, and to increase the power generation efficiency and desulfurization treatment efficiency in the power generation unit 3.

The temperature control means 7 is not particularly limited as long as it can adjust the temperature of the power generation unit 3. For example, the temperature of the power generation unit 3 itself may be adjusted, or the temperature of the solution (water to be treated W or the like) to be introduced into the power generation unit 3 may be adjusted.
Further, as the temperature control means 7, equipment related to the heat source may be newly installed, or the heat source may be brought in from outside the wastewater treatment device 1F, but it is more preferable to use the heat source inside the wastewater treatment device 1F. This makes it possible to reduce the initial cost and running cost of the equipment related to the wastewater treatment device 1F.

As the temperature control means 7 in this embodiment, it is possible to use the existing heat exchange facility 71 provided for advancing the methane fermentation process in the methane fermentation tank 22. For example, as shown in FIG. 9, a power generation unit 3 is provided in the vicinity of the existing heat exchange facility 71, and the cells (first cell 31a and second cell 31b) and electrodes (electrodes 33a and electrodes 33b) of the power generation unit 3 are provided. ), And the water to be treated to be introduced into the power generation unit 3 itself and the power generation unit 3 by arranging the circulation pipe L6 and the electron acceptor supply port 34a so that the heat from the existing heat exchange facility 71 is supplied. Heating W and electron acceptors can be mentioned. This makes it possible to control the temperature of the location where the reaction using the reducing substance in the water to be treated W as an electron donor and the substance used for the reaction, without newly installing equipment related to temperature control.

As another example of the temperature control means 7, as shown in FIG. 10, pipes 72 and 73 for connecting the existing heat exchange equipment 71 and the power generation unit 3 are provided, and the inside of the pipes 72 and 73 is filled with air, water, or the like. The movement of the heat medium may supply heat from the existing heat exchange facility 71 to the power generation unit 3. This makes it possible to control the temperature of the power generation unit 3 and control the temperature of the portion of the water to be treated W where the reducing substance is used as the electron donor. The connection means between the pipes 72 and 73 and the power generation unit 3 is not particularly limited. For example, the pipes 72 and 73 are arranged so as to surround the entire power generation unit 3, and the pipes 72 and 73 are constituent members of the power generation unit 3 (electrodes 33a and electrodes 33b, or first cells 31a and second cells. It may be arranged so as to be in contact with any one of 31b).
Further, as another example of the temperature control means 7, as shown in FIG. 11, pipes 74 and 75 for connecting the existing heat exchange equipment 71 and the circulation pipe L6 are provided, and air, water, etc. are provided in the pipes 74 and 75. By moving the heat medium of the above, the heat from the existing heat exchange facility 71 can be supplied to the water to be treated W in the circulation pipe L6. As a result, the temperature of the water to be treated W to be introduced into the power generation unit 3 is controlled, and the temperature of the substance (reducing substance) used for the reaction using the reducing substance in the water to be treated W as an electron donor is controlled. Is possible. Further, as a place where the pipes 74 and 75 are connected, an electron acceptor supply port 34a may be used instead of the circulation pipe L6. As a result, the temperature of the substance (electron acceptor) used for the reaction in which the heat from the existing heat exchange facility 71 is supplied to the electron acceptor and the reducing substance in the water to be treated W is used as the electron donor is controlled. It becomes possible.
The temperature control means 7 shown in FIGS. 10 and 11 may be provided individually or in combination of two or more. It can be appropriately selected in consideration of the temperature control efficiency by the temperature control means 7 and the cost related to the equipment.

Further, as another example of the temperature control means 7, instead of the existing heat exchange facility 71, exhaust heat in gas power generation using methane generated from the methane fermentation tank 22 may be used. More specifically, the water to be treated W is supplied with heat by bringing a heat medium such as air or water heated using this exhaust heat into contact with the power generation unit 3 or the circulation pipe L6 or the like through a pipe. It becomes possible to control the temperature related to the reaction using the reducing substance inside as an electron donor. As a result, power generation efficiency and desulfurization treatment efficiency can be improved, and waste heat related to methane gas power generation can be effectively used.

The structure of the wastewater treatment device 1F provided with the temperature control means 7 is not limited to the structure of the wastewater treatment device 1B shown in FIG. As another example of the wastewater treatment device 1F provided with the temperature control means 7, for example, in the wastewater treatment device 1A shown in FIG. 1, the reaction in which the reducing substance in the water to be treated W is used as an electron donor (power generation unit). 3. Connection pipe L2, etc.) and wastewater treatment equipment 1B shown in FIG. 2 for reactions (power generation unit 3, circulation pipe L5, etc.) that use a reducing substance in the water to be treated as an electron donor. A structure capable of supplying heat from the existing heat exchange facility 71 can be mentioned. As a result, the temperature related to the reaction in which the reducing substance in the water to be treated W is used as the electron donor can be controlled, and the mass transfer rate related to the reaction and the reaction efficiency can be improved.

As described above, the wastewater treatment apparatus 1F in the present embodiment provides a temperature control means for the reaction in which the reducing substance in the water to be treated is the electron donor, so that the reaction in which the reducing substance is the electron donor can be carried out. It is possible to control the temperature so that the transfer rate of the substance is improved and the reaction efficiency is improved. This makes it possible to increase the power generation efficiency and the desulfurization treatment efficiency.

Further, in the wastewater treatment apparatus 1F of the present embodiment, it is possible to perform power generation and desulfurization treatment by the same steps as in the first embodiment.

The above-described embodiment shows an example of a wastewater treatment device, a power generation device, a desulfurization treatment device, a power generation method, and a desulfurization method. The wastewater treatment device, the power generation device, the desulfurization treatment device, the power generation method, and the desulfurization method according to the present invention are not limited to the above-described embodiments, and the above-described embodiments can be applied to the above-described embodiments without changing the gist described in the claims. Such wastewater treatment equipment, power generation equipment, desulfurization treatment equipment, power generation method and desulfurization method may be modified.

For example, when the water to be treated W contains a reducing substance in advance, the wastewater treatment apparatus in this embodiment may be provided with the power generation unit 3 in front of the treatment tank 2. As a result, along with the power generation by the power generation unit 3, pretreatment for reducing the reducing substances in the water to be treated W can be performed.
Further, the wastewater treatment device in this embodiment may include a plurality of power generation units (power generation devices). For example, both the power generation unit shown in the first embodiment and the power generation unit shown in the second embodiment may be provided. As a result, it becomes possible to perform power generation at a plurality of locations by effectively utilizing the treatment in the wastewater treatment apparatus, and it is possible to improve both the wastewater treatment efficiency and the power generation efficiency.

Further, for example, the wastewater treatment apparatus in the present embodiment may be provided with electrodes 33a and 33b in the settler 23 portion in the treatment tank 2 (methane fermentation tank 22) as the power generation unit 3. The electrode 33a and the electrode 33b may be provided in the vicinity of the settler 23, or the settler 23 itself may be used as the electrode 33a and the electrode 33b. As a result, the power generation unit 3 is incorporated in the processing tank 2, so that the equipment can be further miniaturized.

Further, for example, in the wastewater treatment device of the present embodiment, the electrode 33b may be provided in the aeration tank 41, and the aeration tank 41 may function as the second cell 31b of the power generation unit 3. As a result, the power generation unit 3 and the reaction tank 4 (aeration tank 41) are integrated, and the equipment can be further miniaturized.

Further, for example, the wastewater treatment apparatus in the present embodiment may be provided with means for preventing the adhesion and accumulation of microorganisms on the electrodes 33a and 33b. Examples of such means include coating the surface of the electrode with a material that prevents the adhesion of microorganisms, and making the electrode structure itself a shape that makes it difficult for microorganisms to adhere. Be done. As a result, even when microorganisms flow into the first cell 31a and the second cell 31b of the power generation unit 3, it is possible to suppress the inhibition by the microorganisms to the electrode reaction at the electrodes 33a and 33b.

Further, for example, the wastewater treatment apparatus in the present embodiment may omit a part of the structure to further simplify the apparatus configuration.
Examples of the structure that can be omitted include an ion exchanger 32. This makes it possible to simplify the power generation unit 3 (power generation device / desulfurization treatment device) and facilitate maintenance work.
Further, as another example of the structure that can be omitted, the electron receptor supply port 34a and the electron receptor discharge port 34b in the second cell 31b can be mentioned. This makes it possible to further simplify the power generation unit 3 (power generation device / desulfurization treatment device). At this time, one surface of the electrode 33b may be in contact with the water to be treated W or the ion exchanger 32, and the other surface may be in direct contact with the outside air (air) as a whole. Further, it is preferable to provide a breathable material that can be easily replaced or washed on the surface of the electrode 33b on the outside air side. As a result, it is possible to prevent solid impurities such as dust from adhering to the surface of the electrode 33b.

The wastewater treatment apparatus, power generation method and desulfurization method of the present invention are suitably used in wastewater treatment for treating water to be treated containing a reducing substance and wastewater treatment in which a reducing substance is generated by treating the water to be treated. It is a thing.

By applying the power generation device of the present invention to an existing wastewater treatment device, it is possible to provide the wastewater treatment device and the power generation method of the present invention without updating the entire wastewater treatment device on a large scale.
Further, by applying the desulfurization treatment apparatus of the present invention to an existing wastewater treatment apparatus, it is possible to provide the wastewater treatment apparatus and the desulfurization method of the present invention without updating the entire wastewater treatment apparatus on a large scale.

1A, 1B, 1C, 1D, 1E, 1F Wastewater treatment equipment, 2 treatment tanks, 21 acid generation tanks, 22 methane fermentation tanks, 23 settler, 3 power generation units, 31a first cell, 31b second cell, 32 ions Exchanger, 33a, 33b electrode, 34a electron acceptor supply port, 34b electron acceptor outlet, 4 reaction tank, 41 aeration tank, 42 aeration device, 5 insulation mechanism, 51, 53 storage tank, 52 sprinkling means, 54 water discharge Means, 54a electromagnetic valve, 55 pipe diameter reduction means, 56 gas supply means, 6 pH adjusting means, 61 storage section, 62 addition section, 63 pH detection section, 7 temperature control means, 71 existing heat exchange equipment, 72 to 75 Piping, L1 introduction piping, L2 connection piping, L3, L7 discharge piping, L4, L8 connection piping, L5, L6 circulation piping, L9 water discharge piping, W treated water, W1 treated water

Claims (11)

A wastewater treatment device that treats water to be treated.
A wastewater treatment apparatus characterized in that power is generated by a reaction using a reducing substance in the water to be treated as an electron donor. A wastewater treatment device that treats water to be treated.
A wastewater treatment apparatus characterized in that desulfurization treatment is performed by a reaction using a reducing substance in the water to be treated as an electron donor. The wastewater treatment apparatus according to claim 1 or 2, wherein an electrode is installed in the water to be treated to generate electricity. The wastewater treatment apparatus according to claim 3, wherein an ion exchanger is arranged between the electrodes. A treatment tank for treating the water to be treated and a power generation unit are provided after the treatment tank.
The wastewater treatment apparatus according to any one of claims 1 to 4, wherein a reducing substance in the water to be treated after being treated by the treatment tank is introduced into the power generation unit to generate power. .. The wastewater treatment apparatus according to any one of claims 1 to 5, wherein a pH control means for dissolving the reducing substance in the water to be treated is provided. The wastewater treatment apparatus according to any one of claims 1 to 5, wherein a temperature control means for a reaction using a reducing substance in the water to be treated as an electron donor is provided. It is a power generation device installed in a wastewater treatment device that treats water to be treated.
A power generation device characterized in that power is generated using the reducing substance in the water to be treated as an electron donor. A desulfurization treatment device installed in a wastewater treatment device that treats water to be treated.
A desulfurization treatment apparatus, characterized in that the reducing substance in the water to be treated is subjected to a desulfurization treatment as an electron donor. It is a power generation method in wastewater treatment that treats water to be treated.
A power generation method comprising a step of generating power using the reducing substance in the water to be treated as an electron donor. A desulfurization method for wastewater treatment that treats water to be treated.
A desulfurization method comprising a step of subjecting a reducing substance in the water to be treated to a desulfurization treatment as an electron donor.