JP7404080B2 - Wastewater treatment equipment, wastewater treatment method, and treatment system - Google Patents

Description

The present invention relates to a wastewater treatment device and a wastewater treatment method. The present invention also relates to a treatment system including a wastewater treatment device and a combustion device.

Various treatment methods are known as wastewater treatment for treating water to be treated. This type of wastewater treatment depends on the physical characteristics of the water to be treated, such as the components contained in the water to be treated and the amount of water to be discharged, as well as the balance between treatment efficiency and cost. In addition, treatment methods are selected taking into consideration the characteristics of the equipment and operation for implementing wastewater treatment.
Furthermore, in wastewater treatment, efforts are being made to improve the efficiency of wastewater treatment by combining a plurality of different wastewater treatment methods.

For example, Patent Document 1 describes wastewater treatment in which a pair of electrodes is immersed in the water to be treated, electrochemical treatment is performed, and then the water to be treated is biologically treated, as treatment of water to be treated containing organic matter. There is.

Japanese Patent Application Publication No. 2004-330182

As described in Patent Document 1, in wastewater treatment that combines electrochemical treatment and biological treatment, reactions with high reaction efficiency proceed for each treatment to improve the treatment efficiency of the wastewater treatment as a whole. becomes possible. On the other hand, electrochemical processing generally has a problem in that running costs related to power consumption are large. The wastewater treatment described in Patent Document 1 is said to enable lower running costs than electrochemical treatment alone. However, in the wastewater treatment described in Patent Document 1, it is necessary to supply energy for electrochemical treatment and biological treatment from outside the wastewater treatment system. Therefore, there is a need for further energy savings during wastewater treatment.

In recent years, in order to reduce the power required to drive equipment during wastewater treatment and achieve superior energy savings, technologies that can recover and utilize energy during the wastewater treatment process have been studied.
One such technology is energy recovery using biogas generated through biological treatment. Ancillary equipment is required, such as equipment to convert it into electrical energy via an engine or gas turbine. Therefore, there is a need for technology that more simply and efficiently recovers and uses energy in wastewater treatment.

A conceivable technique for simply and efficiently recovering energy in wastewater treatment is to provide an electrode on the wastewater treatment process and directly recover electrical energy through the electrode reaction. At this time, it is possible to perform electrochemical treatment on the treated water at the same time as energy recovery through electrode reactions, which is expected to improve the efficiency of wastewater treatment and realize energy savings.

On the other hand, the present inventors have found that when an electrode is provided on a wastewater treatment process to perform an electrode reaction, there is a problem in that the pH on the cathode side increases and the electrode reaction efficiency decreases.

An object of the present invention is to provide a wastewater treatment device, a wastewater treatment method, and a treatment system that can recover and utilize energy through electrode reactions in wastewater treatment, and can suppress a decrease in electrode reaction efficiency. be.

As a result of intensive studies on the above-mentioned issues, the present inventor has discovered that efficient energy generation can be achieved by generating electricity (electrode reaction) using the components contained in the treated water after treating the treated water in wastewater treatment. We discovered that it is possible to recover and use the gas, and that by supplying exhaust gas from a combustion device, it is possible to suppress the pH increase on the cathode side in the electrode reaction and suppress the decrease in efficiency of the electrode reaction. Thus, the present invention was completed.
That is, the present invention provides the following wastewater treatment apparatus, wastewater treatment method, and treatment system.

The wastewater treatment device of the present invention for solving the above problems is a wastewater treatment device that processes water to be treated, and is a power generator that generates electricity by bringing an electrode into contact with the treated water after the water to be treated is treated. The present invention is characterized by comprising a section and a supply means for supplying the exhaust gas generated in the combustion device to the power generation section.

The wastewater treatment device of the present invention can generate power during a series of treatment steps in wastewater treatment by installing a power generation unit using electrodes in the wastewater treatment device. This makes it possible to efficiently generate power and recover and use energy without increasing the size of equipment. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply means for supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side during the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing.

Moreover, one embodiment of the wastewater treatment apparatus of the present invention is characterized in that the combustion apparatus is for incinerating sludge produced during wastewater treatment.
According to this feature, a combustion target can be easily obtained, and an existing combustion device related to sludge treatment can be used. Thereby, there is no need to newly provide a combustion device for the wastewater treatment apparatus of the present invention, and the initial cost can be significantly reduced.

Moreover, one embodiment of the wastewater treatment apparatus of the present invention is characterized in that it includes a temperature adjustment mechanism that adjusts the temperature of exhaust gas.
According to this feature, the temperature of the exhaust gas supplied to the power generation section can be adjusted, making it possible to suppress the occurrence of problems related to power generation, such as deterioration of electrodes due to heat and reduction due to evaporation (vaporization) of electrolyte solution. becomes.

In addition, the wastewater treatment method of the present invention for solving the above problems is a wastewater treatment method for treating water to be treated, in which an electrode is brought into contact with the treated water after the water to be treated is treated, and electricity is generated. The present invention is characterized by comprising a power generation process in which the combustion process is performed, and a supply process in which the exhaust gas generated in the combustion device is supplied to the power generation process.
In the wastewater treatment method of the present invention, by providing a power generation step using electrodes in wastewater treatment, it is possible to generate power during a series of treatment steps in wastewater treatment. This makes it possible to efficiently generate power and recover and use energy without increasing the size of equipment. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply step of supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side in the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing.

Furthermore, a treatment system of the present invention for solving the above problems is a treatment system comprising a wastewater treatment device that processes water to be treated and a combustion device that burns substances, the wastewater treatment device being The present invention is characterized in that it includes a power generation section that generates electricity by bringing the electrode into contact with the treated water after the water to be treated has been treated, and a supply means that supplies the exhaust gas generated in the combustion device to the power generation section.
The treatment system of the present invention includes a wastewater treatment device and a combustion device, and by installing a power generation unit using electrodes in the wastewater treatment device, it is possible to generate power during a series of treatment steps in wastewater treatment. It becomes possible. This makes it possible to efficiently generate power and recover and use energy without increasing the size of equipment. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply means for supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side during the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing as a processing system.

According to the present invention, it is possible to provide a wastewater treatment device, a wastewater treatment method, and a treatment system that can recover and utilize energy through electrode reactions in wastewater treatment, and can suppress a decrease in electrode reaction efficiency. be.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the wastewater treatment apparatus in the 1st embodiment of this invention. It is a schematic explanatory view showing the supply means in the wastewater treatment device of the first embodiment of the present invention. It is a schematic explanatory view which shows another aspect of the supply means in the wastewater treatment apparatus of the 1st embodiment of this invention. It is a schematic explanatory view of the wastewater treatment device 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 view of the wastewater treatment device in the 3rd embodiment of this invention. It is a schematic explanatory diagram of the processing system in the 4th embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a wastewater treatment device, a wastewater treatment method, and a treatment system according to the present invention will be described in detail with reference to the drawings. The description of the wastewater treatment method in the present invention shall be replaced with the explanation of the operation of the wastewater treatment device in the present invention.
Note that the wastewater treatment apparatus, wastewater treatment method, and treatment system described in the embodiments are merely exemplified to explain the wastewater treatment apparatus, wastewater treatment method, and treatment system according to the present invention, and are limited thereto. It's not a thing.

In the wastewater treatment apparatus and treatment system of the present invention, the water to be treated is not particularly limited as long as it generates a substance capable of electrode reaction through treatment. Examples of substances capable of electrode reactions include reducing substances. Further, 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, water to be treated will mainly be described as water in which reducing substances are generated through treatment, but the present invention is not limited to this.

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 certain substance functions as an electron donor is relatively determined by its combination with a substance that functions as an electron acceptor (hereinafter simply referred to as "electron acceptor"). That is, the reducing substance in the present invention may be one that releases electrons more easily than the electron acceptor, that is, one that has a lower 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 a lower redox potential than oxygen, and such reducing substances include hydrogen sulfide, hydrogen, ammonia, etc. can be mentioned.

[First embodiment]
[Wastewater treatment equipment]
FIG. 1 is a schematic explanatory diagram showing the structure of a wastewater treatment device according to a first embodiment of the present invention.
The wastewater treatment device 1A in this embodiment includes a treatment tank 2, a power generation section 3, and a supply means 4, as shown in FIG. In addition, the wastewater treatment device 1A connects an introduction pipe L1 that introduces the water W to be treated into the treatment tank 2, the treatment tank 2 and the power generation unit 3, and provides treatment after the water W to be treated is treated in the treatment tank 2. It includes a connection pipe L2 that supplies water W1 to the power generation section 3, and a discharge pipe L3 that discharges the treated water W2 after the electrode reaction from the power generation section 3. Furthermore, a reaction tank 5 is connected to the latter stage of the discharge pipe L3.

(processing tank)
The treatment tank 2 is a tank for treating the water W to be treated.
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 treated water W1 after treatment contains a reducing substance. Examples include biological treatment and chemical treatment (addition of chemicals, ozone treatment, etc.), but biological treatment does not involve the use or production of substances harmful to the human body and can be processed at a relatively low cost. It is desirable to do so.
Furthermore, as biological treatment, for example, biological treatment in an anaerobic environment (anaerobic treatment) includes methane fermentation using acid-producing bacteria and methanogenic bacteria, and denitrification treatment that reduces nitric acid and nitrite using denitrifying bacteria. Examples include sulfuric acid reduction treatment in which sulfuric acid is reduced by sulfuric acid-reducing bacteria. Furthermore, examples of biological treatment under an aerobic environment (aerobic treatment) include activated sludge treatment using activated sludge. As for biological treatment, anaerobic treatment is preferable because it has many advantages such as not requiring aeration power and generating almost no surplus sludge. Furthermore, from the viewpoint of processing cost and usefulness of the produced gas, methane fermentation that produces methane is particularly preferred.

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

The water to be treated W treated in the treatment tank 2 becomes treated water W1 containing reducing substances, and is introduced into the power generation section 3 via the connecting pipe L2.

(Power generation department)
The power generation unit 3 is for generating power using a reducing substance in the treated water W1 as an electron donor.
As shown in FIG. 1, the power generation section 3 of this embodiment is provided at the rear stage of the processing tank 2, and is provided so as to partition the first cell 31a and the second cell 31b, and between the cells 31a and 31b. ion exchanger 35, and electrodes 33a and 33b arranged in cells 31a and 31b, respectively. Here, the first cell 31a is formed so that the treated water W1 introduced from the treatment tank 2 via the connection pipe L2 comes into contact with the electrode 33a, and the electrode 33a arranged in the first cell 31a acts as an anode. On the other hand, the second cell 31b is formed to store or supply electron acceptors, and the electrode 33b arranged in the second cell 31b functions as a cathode. Furthermore, the electrodes 33a and 33b are connected to an external circuit via conductive wires (not shown). Thereby, in the power generation section 3, it becomes possible to recover and utilize the electrical energy generated by the reducing substance acting as an electron donor.

The first cell 31a may be of any material or shape as long as it includes an electrode 33a and is formed so that the treated water W1 comes into contact with the electrode 33a. For example, as shown in FIG. 1, it has a space that can temporarily store the treated water W1 introduced from the treated water inlet 32a via the connecting pipe L2, and the treated water W2 after contacting the electrode 33a is stored. For example, a discharge pipe L3 for discharging the treated water from the discharge port 32b may be provided. Thereby, the reducing substance in the treated water W1 donates electrons to the electrode 33a as an electron donor, and then is quickly discharged via the discharge pipe L3.
Note that a flow rate adjustment mechanism such as a valve may be provided in the connection pipe L2 and/or the discharge pipe L3. This makes it possible to adjust the amount and flow rate of the treated water W1 brought into contact with the electrode 33a and control the mass transfer rate to the electrode 33a.

The treated water W2 discharged via the discharge pipe L3 can be discharged as is if it satisfies water quality that allows discharge into a river or the like. Further, a reaction tank 5 for further processing the treated water W2 may be provided downstream of the discharge pipe L3, and the water may be discharged to the outside of the system as the treated water W3. The reaction tank 5 is not particularly limited as long as it can treat the treated water W2 to a quality that allows it to be discharged outside the system or into a river. Examples include an aeration tank and a pH adjustment tank.

The second cell 31b may be of any material or shape as long as it includes an electrode 33b and is formed to store or supply electron acceptors for the reducing substances in the treated water W1.

Here, the form of the electron acceptor may be either gas or liquid. Note that the liquid may be a solution in which a solid drug is dissolved, or a solution in which a gas is mixed (dissolved).
In particular, the second cell 31b in which the electrode 33b is arranged is filled with an electron acceptor solution. Thereby, the function of suppressing a decrease in electrode reaction efficiency by the supply means 4, which will be described later, is effectively exhibited.

As for specific examples of the electron acceptor in this embodiment, examples of the gas include oxygen and a gas containing oxygen. Note that gases containing oxygen include gases that contain oxygen as a mixture, such as air, and gases that contain oxygen as an element constituting a compound, such as carbon dioxide. When a gas is used as the electron acceptor, there are advantages in that it is not necessary (or easy) to dispose of the gas discharged after the reaction and that the cost of obtaining the gas can be reduced. Note that in order to take full advantage of these advantages, it is particularly preferable to use air as the electron acceptor.
In addition, other examples of the electron acceptor in this embodiment include, as the liquid, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous potassium ferricyanide solution, and the like. When a liquid is used as an electron acceptor, it is easy to handle a compound (oxidizing agent) that is highly effective as an electron acceptor, so there is an advantage that power generation efficiency can be further improved. Note that from the viewpoint of improving power generation efficiency, it is particularly preferable to use a potassium ferricyanide aqueous solution as the electron acceptor.

As the second cell 31b, for example, as shown in FIG. 1, a space capable of storing a liquid is provided in the second cell 31b, and an electron acceptor supply port 34a and an electron acceptor discharge port 34b are provided, respectively. An example of this is to provide a device capable of supplying a receptor solution and discharging the solution after the reaction. Further, as another example of the second cell 31b, there is a method for supplying gas to the second cell 31b in order to supply a gaseous electron acceptor (oxygen, air, etc.) to the electrode 33b. An example of this is to provide an electron acceptor supply port 34a and an electron acceptor discharge port 34b for discharging gas after the reaction. Thereby, the electron acceptor can receive electrons from the electrode 33a via the electrode 33b, and a current flows between the electrode 33a and the electrode 33b to generate power. Further, the electron acceptor after the reaction is quickly discharged to the outside of the power generation section 3 via the electron acceptor discharge port 34b.
Note that a flow rate adjustment mechanism such as a valve may be provided in the electron acceptor supply port 34a and/or the electron acceptor discharge port 34b to adjust the concentration of the electron acceptor in the second cell 31b. Furthermore, a control mechanism may be provided to control the flow rate adjustment mechanism so that the electron acceptor concentration is maintained in accordance with the amount of electrons generated by the reaction at the electrode 33a. Thereby, it becomes possible to suppress a decrease in reaction efficiency related to electron transfer between the electrode 33a and the electrode 33b, and to suppress a decrease in power generation efficiency.

In FIG. 1, one electron acceptor supply port 34a and one electron acceptor discharge port 34b are shown, but the present invention is not limited to this. For example, a plurality of electron acceptor supply ports 34a and a plurality of electron acceptor 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. Therefore, when providing a plurality of electron acceptor discharge ports 34b, for example, one for discharging gas and one for discharging liquid may be provided separately.

The ion exchanger 35 may have any known configuration that can transmit ions, and is not particularly limited. In particular, a cation exchange membrane that can permeate hydrogen ions generated at the electrode 33a (anode side) can be mentioned. Thereby, 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. Moreover, it is more preferable that the ion exchanger 35 has low oxygen permeability. This suppresses the electron acceptor (especially oxygen) supplied to the electrode 33b (cathode side) from moving to the electrode 33a side, and suppresses the reaction efficiency of the electron donor at the electrode 33a from decreasing due to oxygen. becomes possible.
Although FIG. 1 shows that the ion exchanger 35 is provided separately from the electrodes 33a and 33b, the ion exchanger 35 is not limited thereto. For example, the electrode 33a and/or the electrode 33b may be integrated with a material having ion exchange ability. This makes it possible to downsize the entire power generation section 3 and to shorten the time required for maintenance work.

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

The electrode 33a may be anything that functions as an anode, and there are no particular limitations on the material and shape. The material and shape of the electrode 33a can be appropriately selected in consideration of the cost of material procurement and processing, the reaction efficiency of the reducing substance in the electrode 33a, and the like. Examples of the material of the electrode 33a include carbon and metals (stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the electrochemical field. Further, examples of the shape of the electrode 33a include, for example, a flat plate shape, a rod shape, a mesh shape, and the like.
In particular, it is preferable to use a porous material as the electrode 33a of this embodiment in view of power generation efficiency. For example, as the electrode 33a, in addition to using porous carbon paper or carbon fiber such as carbon cloth, foamed metal, porous metal, or metal mesh may be used.

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

The electrode 33b may be any material as long as it functions as a cathode, and its 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 in the electrode 33b, and the like. Examples of the material of the electrode 33b include carbon and metals (stainless steel, platinum, copper, etc.) that are widely used as electrode materials in the electrochemical field. Further, examples of the shape of the electrode 33b include, for example, a flat plate shape, a rod shape, a mesh shape, and the like.
In particular, it is preferable to use a porous material as the electrode 33b of this embodiment in view of power generation efficiency. For example, as the electrode 33b, in addition to using porous carbon paper or carbon fiber such as carbon cloth, foamed metal, porous metal, or metal mesh may be used.

When the electron acceptor supplied into the second cell 31b is gas (air), one surface of the electrode 33b is in contact with the gas, and the other surface is in contact with the treated water W1. Therefore, it is preferable that the electrode 33b has a form suitable as a so-called air cathode. Examples of suitable forms for the air cathode include those having both gas permeability and water impermeability. By making the electrode 33b gas-permeable, it becomes possible to cause gas, which is an electron acceptor, to react effectively with the electrode 33b. Moreover, by providing the electrode 33b with water impermeability, it becomes possible to suppress the treated water W1 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, and one whose surface is treated with a material having gas permeability and water impermeability, or by laminating a film on the surface of the metal mesh. Can be mentioned. Note that water impermeability here refers to not allowing water to pass through. For example, making the electrode 33b waterproof, water repellent, hydrophobic, or watertight also means that it is water impermeable. It is included.

Hereinafter, power generation in the wastewater treatment device will be explained in detail.
Based on FIG. 1, reactions and steps related to power generation in the wastewater treatment apparatus according to the first embodiment of the present invention will be explained. The reaction and process related to power generation in the piping of this embodiment uses a reducing substance generated by anaerobically treating water W to be treated as an electron donor, and a solution containing oxygen and an oxidizing agent as an electron acceptor. This is an explanation of the following.
Note that the description of the reactions and steps based on FIG. 1 is given for an example of power generation in this embodiment, and is not limited thereto. In addition, the following explanation describes reactions and processes related to the process from the processing tank 2 to the power generation section 3, and the reactions and processes related to other configurations (introduction pipe L1, discharge pipe L3, reaction tank 5, etc.) are described. Explanation is omitted. Furthermore, the notations of reactions R1 to R4 and steps S1 to S3 are numbered for the purpose of explanation, and do not specify the order of the reactions or steps.

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

The treated water W1 that has been treated in the treatment tank 2 and contains reducing substances is introduced into the first cell 31a in the power generation section 3 via the connection pipe L2 (step S2). Here, when a 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 at the electrode 33a (reaction R1) is represented by the following reaction formula (Formula 1).

Further, a portion of hydrogen sulfide reacts as hydrogen sulfide ions. The reaction at this time is shown by the following reaction formula (Formula 2).

As shown in Formulas 1 and 2, in reaction R1, hydrogen sulfide contained in treated water W1 after being treated in treatment tank 2 donates electrons to electrode 33a, and hydrogen sulfide itself is oxidized. This makes it harmless and odorless. Therefore, the wastewater treatment device of this embodiment has the advantage of being able to perform desulfurization and deodorization as well as power generation. Note that reducing substances (such as ammonia) that are harmful substances and odor substances other than hydrogen sulfide also function as electron donors, and as the reaction progresses, it becomes possible to make them harmless and odorless.

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

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

Based on the reactions R1 to R4 and steps S1 to S3 described above, a current flows between the electrode 33a and the electrode 33b. Thereby, power generation is performed in the wastewater treatment apparatus of this embodiment.
Furthermore, the electrical energy obtained by power generation can be recovered and utilized through an external circuit connected to the electrodes 33a and 33b. Note that the use of electrical energy is not particularly limited. For example, it may be used to drive equipment of a wastewater treatment device, or it may be used outside the wastewater treatment device.

In the electrode reaction in the wastewater treatment apparatus of this embodiment, reaction R4 based on Formula 3 proceeds as hydrogen ions (H ⁺ ) move to the cathode side due to reaction R3. However, in reaction R3, since hydrogen ions move through the ion exchanger 35, the electrode reaction proceeds before sufficient hydrogen ions are supplied to the electrode 33b on the cathode side in the reaction based on formula 3. Sometimes. At this time, at the electrode 33b, instead of the reaction that generates water (H ₂ O) based on equation 3, a reaction that generates hydroxide ions (OH ^- ) proceeds, and at the electrode 33b (cathode side), the pH increases. happen. This causes a problem in that the electrode reaction (power generation) efficiency decreases.

For this reason, it is preferable to provide the wastewater treatment apparatus 1A in this embodiment with means for suppressing the pH increase on the cathode side of the power generation section 3. As a means for suppressing the pH increase, for example, adding an acidic component can be mentioned. Here, as a means of suppressing the pH increase, in addition to newly installing a means for adding acidic components as chemicals, a more preferable example is to create a structure that can utilize the waste discharged from existing equipment, etc. It will be done. This makes it possible to save cost and energy of the wastewater treatment device 1A.
As a means for suppressing the pH increase by utilizing waste discharged from existing devices, for example, supplying exhaust gas generated from various combustion devices to the wastewater treatment device 1A can be mentioned. The exhaust gas generated _by combustion equipment contains carbon dioxide (CO ₂ ), sulfur oxides ( _SO It is known. Therefore, by utilizing the exhaust gas generated by the combustion device, it is possible to suppress the pH increase in the power generation section 3.

(Supply means)
The supply means 4 supplies the exhaust gas generated in the combustion device to the power generation unit 3 and suppresses a pH increase, thereby suppressing a decrease in electrode reaction efficiency.
The supply means 4 is not particularly limited as long as it can supply the exhaust gas generated by the combustion device to the power generation section 3. Note that it is particularly preferable that the supply means 4 in this embodiment supply the exhaust gas into the second cell 31b on the cathode side, in which the electrode 33b is arranged. Examples of such supply means 4 include one provided with a structure for directly supplying exhaust gas to the second cell 31b, and one provided with a structure for supplying exhaust gas together with an electron acceptor.

A specific example of the supply means 4 is to directly provide the second cell 31b in the power generation section 3 with a mechanism for supplying the exhaust gas generated in the combustion device.
FIG. 2 is a schematic explanatory diagram when a mechanism for directly supplying exhaust gas to the second cell 31b is provided as the supply means 4 of this embodiment. Note that FIG. 2 is an enlarged view of the vicinity of the power generation section 3 in the wastewater treatment apparatus 1A, and illustration of the treatment tank 2 and reaction tank 5 is omitted.

As shown in FIG. 2, as the supply means 4, an exhaust gas supply port 41 is provided in the second cell 31b, and the exhaust gas supply port 41 is connected with a pipe 42 for supplying exhaust gas generated in a combustion device (not shown). One example is to connect. Here, the broken line arrow in FIG. 2 indicates the inflow direction of exhaust gas. Further, in FIG. 2, the exhaust gas supply port 41 is provided at the upper part of the second cell 31b to supply exhaust gas as the supply means 4, but the present invention is not limited to this. As another example of the supply means 4, for example, the exhaust gas supply port 41 is provided at the lower part of the second cell 31b, and the exhaust gas is supplied so as to rise from the bottom to the top inside the second cell 31b. Examples include things to do.

For the exhaust gas supply port 41 and the piping 42, a known structure related to gas supply/transfer can be used, and the specific structure is not particularly limited.
Further, the pipe 42 may be used as long as it is for transporting exhaust gas generated by the combustion device, and may be connected directly or indirectly to the combustion device.

The supply means 4 is not limited to one in which an exhaust gas supply port 41 and a pipe 42 are provided to the power generation section 3, as shown in FIG. For example, as the supply means 4, a pipe 42 may be connected to an electron acceptor storage location or an electron acceptor supply line, and the exhaust gas may be supplied from the electron acceptor supply port 34a to the electrode 33b. Thereby, there is no need to provide the exhaust gas supply port 41 as a separate body, so the device configuration can be simplified.

In this embodiment, there are no particular limitations on the structure of the combustion device itself connected to the supply means 4, the object to be burned by the combustion device, etc.
As the combustion device, a known configuration capable of burning substances can be used. The combustion device may be newly installed for the wastewater treatment device 1A in this embodiment, but in view of cost, an existing combustion device may be used. Examples include combustion devices in waste incineration facilities, as well as combustion devices in power generation facilities that burn gas such as biogas.
In addition, the substances burned in the combustion device include at least one of carbon, sulfur, and nitrogen components, and after combustion, carbon dioxide, sulfur oxides, nitrogen oxides, etc. are dissolved in an aqueous solution to reduce acidity. The substance is not particularly limited as long as it generates exhaust gas containing the indicated components.

Examples of combustion devices include those that burn waste generated during the treatment process of wastewater treatment. Thereby, in addition to generating electricity in a series of treatment steps in wastewater treatment, it is also possible to carry out a process related to suppressing a decrease in electrode reaction (power generation) efficiency. Therefore, as the wastewater treatment device 1A, energy recovery and utilization efficiency is improved, and costs can be reduced.
A specific example of such a combustion device is one that incinerates sludge produced in wastewater treatment. This makes it possible to easily obtain a target for combustion, and also to utilize an existing combustion device for sludge treatment. Furthermore, because of the wastewater treatment device of the present invention, there is no need to provide a new combustion device, making it possible to significantly reduce initial costs.
Furthermore, when the combustion target is sludge, the sludge contains a lot of organic matter, so the combustion process generates exhaust gas containing a lot of carbon dioxide. In recent years, carbon dioxide emission regulations have become stricter in view of the impact on the environment. Therefore, by supplying exhaust gas containing carbon dioxide to the power generation section 3, a decrease in electrode reaction efficiency in the power generation section 3 is suppressed, and since carbon dioxide is dissolved in the electrolyte solution in the power generation section 3, the carbon dioxide It also has the effect of making it possible to suppress discharge to the outside of the system.

Another aspect of the supply means 4 of this embodiment may include a mechanism for adjusting the temperature of the exhaust gas.
It is known that the temperature of exhaust gas produced in combustion devices can exceed 100 degrees. On the other hand, the power generation unit 3 of the wastewater treatment device 1A in this embodiment performs an electrochemical reaction using electrodes placed in an aqueous solution, and if exhaust gas exceeding 100 degrees is supplied as it is, it will accelerate the deterioration of the electrodes and Evaporation (vaporization) of the electrolyte solution in the power generation section 3 may cause problems due to heat, such as a decrease in electrode reaction efficiency. Therefore, it is preferable to adjust the temperature of the exhaust gas and supply it to the power generation section 3.

FIG. 3 is a schematic explanatory diagram when a mechanism for adjusting the temperature of exhaust gas is provided as the supply means 4 in this embodiment. Note that FIG. 3 is an enlarged view of the vicinity of the power generation section 3 in the wastewater treatment apparatus 1A, and illustration of the treatment tank 2 and reaction tank 5 is omitted.

As shown in FIG. 3, as a mechanism for adjusting the temperature of the exhaust gas, a temperature adjustment mechanism 43 is provided on the pipe 42 to adjust the temperature of the exhaust gas. More specifically, the temperature adjustment mechanism 43 may cool the temperature of the exhaust gas to 100 degrees or less. Thereby, when exhaust gas is supplied into the power generation section 3 (second cell 31b), it is possible to suppress the occurrence of problems due to heat.

The temperature adjustment mechanism 43 may be any mechanism as long as it can adjust the temperature of gas (exhaust gas), and a known configuration can be used. An example of the temperature adjustment mechanism 43 is a heat exchanger using a gas such as air or a liquid such as cooling water. In addition, as another example of the temperature adjustment mechanism 43, the arrangement of exhaust gas piping, etc. in the treatment tank 2 and reaction tank 5 in the wastewater treatment apparatus 1A of this embodiment so that heating using exhaust gas is possible. One example is to do the following. Thereby, by supplying the cooled exhaust gas after heating the treatment tank 2 and the reaction tank 5 to the power generation unit 3 via the pipe 42, a decrease in electrode reaction efficiency is suppressed, and the wastewater treatment device 1A It becomes possible to save energy as a whole.

The wastewater treatment apparatus 1A in this embodiment uses a reducing substance in the water to be treated W as an electron donor, generates electricity through an electrochemical reaction (electrode reaction), and recovers and utilizes energy. Generally, when performing an electrochemical reaction, a problem arises in that the efficiency of the electrochemical reaction decreases due to electrons moving to a location other than the location where the electrochemical reaction is actually performed (power generation section 3). Therefore, in the wastewater treatment apparatus 1A in this embodiment, it is preferable that the parts other than the part where the electrochemical reaction is performed (the power generation part 3) be insulated. Specific examples of insulation treatment include, for example, installing the treatment tank 2 and reaction tank 5 on top of an insulator, constructing the outer or inner walls of the treatment tank 2 and reaction tank 5 with an insulator, and Examples include coating the outer or inner walls of the tank 2 and the reaction tank 5 with an insulating material. Furthermore, examples of insulating treatment for the introduction pipe L1, the connection pipe L2, and the discharge pipe L3 include making each pipe made of an insulator, coating each pipe with an insulating material, and the like.

As described above, the wastewater treatment device and the wastewater treatment method of this embodiment make it possible to generate electricity during a series of treatment steps in wastewater treatment. This makes it possible to efficiently generate power and recover and use energy without increasing the size of equipment. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply means for supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side during the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing.

Hereinafter, other embodiments of the treatment tank 2, power generation section 3, and reaction tank 5 in the wastewater treatment apparatus of the present invention will be illustrated.

[Second embodiment]
FIG. 4 is a schematic explanatory diagram showing a wastewater treatment device in a second embodiment of the present invention. Moreover, FIG. 5 is a schematic explanatory diagram showing another aspect of the wastewater treatment device in the second embodiment of the present invention.
In the wastewater treatment device 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 a circulation flow path provided in the processing tank 2 (acid generation tank 21 and methane fermentation tank 22). Here, the wastewater treatment apparatuses 1B shown in FIGS. 4 and 5 each have a different installation location of the power generation section 3. Note that the supply means 4 may be any one of the supply means 4 shown in the first embodiment, and is not particularly limited. Further, description of the same components as those of the first embodiment will be omitted.

In the wastewater treatment apparatus 1B in this embodiment, as shown in FIGS. 4 and 5, the treatment tank 2 includes an acid production tank 21 and a methane fermentation tank 22, which are connected by a connection pipe L4, and a circulation pipe L5 for acid production. A circulation flow path is formed between the tank 21 and the methane fermentation tank 22, and a circulation flow path within the methane fermentation tank 22 is formed by the circulation pipe L6.
In addition, in the wastewater treatment apparatus 1B shown in FIG. 4, the power generation section 3 is provided on the circulation pipe L5. On the other hand, in the wastewater treatment apparatus 1B shown in FIG. 5, the power generation section 3 is provided on the circulation pipe L6.

The processing 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 using microorganisms housed inside. Note that 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-producing tank 21 generates solids such as sugars, proteins, and oils and high-molecular organic substances by acid-producing bacteria (mainly anaerobic acid-producing bacteria) housed inside the water to be treated W introduced through the introduction pipe L1. This is an acid-generating treatment that decomposes and produces 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 connection pipe L4.

Note that the acid generation tank 21 is equipped with an internal water temperature adjustment means, a means for introducing a pH adjuster, and a means for adding metals such as nitrogen, phosphorus, cobalt, and nickel, which are nutrient sources required by bacteria. (not shown).

The methane fermentation tank 22 performs methane fermentation processing to generate 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 through the connection pipe L4. be. Methane fermentation treatment is carried out in an anaerobic atmosphere free of dissolved oxygen using methanogenic bacteria maintained 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 something to do.

A granule layer containing anaerobic bacteria suitable for anaerobic treatment is formed in the methane fermentation tank 22 . 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, gas containing methane and carbon dioxide as main components is generated, and treated water W1 containing reducing substances is generated. Note that a settler 23 serving as gas-solid-liquid separation means may be provided inside the methane fermentation tank 22. Gas generated within the methane fermentation tank 22 is released or recovered outside the tank (not shown). Furthermore, the treated water W3 generated in the methane fermentation tank 22 is discharged to the outside of the treatment system via the discharge pipe L7.

Note that the methane fermentation tank 22 can be further provided with various types of incidental equipment. For example, it may be equipped with an internal water temperature adjustment means, a means for introducing a pH adjuster, and a means for adding metals such as nitrogen, phosphorus, cobalt, and nickel, which are nutrients required by bacteria (not shown). .

The methane fermentation tank 22 is preferably equipped with means for recovering, purifying, and storing methane gas among the gases generated within the methane fermentation tank 22. Thereby, in addition to power generation by the power generation unit 3, it becomes possible to recover and effectively utilize methane gas, which is a useful energy source, from the water to be treated W. In addition, when power generation is performed by gas combustion as a utilization of methane gas, the exhaust gas discharged from the combustion device used for this gas combustion may be used as the exhaust gas supplied by the supply means 4 in this embodiment. Thereby, it becomes possible to suppress a decrease in the electrode reaction efficiency of the power generation section 3 by using the waste generated by the wastewater treatment.
The methane fermentation tank 22 also includes a means for recovering, purifying, and storing carbon dioxide gas among the gas generated in the methane fermentation tank 22, and the methane fermentation tank 22 is equipped with a means for recovering, refining, and storing carbon dioxide gas from among the gases generated in the methane fermentation tank 22. It may also be provided with a means capable of introducing carbon dioxide gas into the interior of 31b. This makes it possible to effectively utilize carbon dioxide gas as an electron acceptor and reduce the cost of supplying the electron acceptor. Further, the above-mentioned means capable of introducing carbon dioxide may be provided separately from the supply means 4 or may overlap with a part of the supply means 4. This allows carbon dioxide to be stably supplied into the second cell 31b, making it possible to more reliably suppress an increase in pH on the cathode side.

Furthermore, the methane fermentation tank 22 in this embodiment is equipped with a circulation pipe L5 and/or a circulation pipe L6. The circulation pipe L5 supplies the water to be treated W from the upper part of the methane fermentation tank 22 to the acid production tank 21, and forms a circulation flow path between the acid production tank 21 and the methane fermentation tank 22. Further, the circulation pipe L6 supplies the water to be treated W from the upper part of the methane fermentation tank 22 to the lower part of the methane fermentation tank 22, and forms a circulation flow path within the methane fermentation tank 22.

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

As shown in FIG. 4, in the case where the power generation unit 3 is provided on the circulation pipe L5, the treated water W1 from the methane fermentation tank 22 is supplied to the first cell 31a, and the treated water W2 after the reaction at the electrode 33a is , is supplied to the acid generation tank 21 via the circulation pipe L5. At this time, the treated water W2 after the reaction at the electrode 33a has an increased hydrogen ion concentration as shown in equations 1 and 2, and becomes a solution with an acidic pH. Generally, it is known that in order for the reaction within the acid generation tank 21 to progress suitably, it is preferable that the pH within the acid generation tank 21 be on the acidic side. Therefore, the water to be treated W discharged from the power generation unit 3 to the acid generation tank 21 may be used as a pH adjusting agent for allowing the reaction in the acid generation tank 21 to proceed under favorable conditions. Furthermore, a flow rate adjustment mechanism such as a valve or an adsorption treatment means such as activated carbon may be provided on the circulation pipe L5 on the acid generation tank 21 side. Thereby, when the pH range in the acid generation tank 21 deviates from the appropriate range due to the treated water W2 discharged from the power generation unit 3 flowing into the acid generation tank 21, the inflow amount of the treated water W2 can be controlled. It is possible to control the pH of the water to be treated W in the acid generation tank 21, and it is possible to suppress inhibition of the reaction in the acid generation tank 21.

Further, as shown in FIG. 5, in the case where the power generation section 3 is provided on the circulation pipe L6, the treated water W1 from the upper part of the methane fermentation tank 22 is supplied to the first cell 31a, and the treatment after the reaction at the electrode 33a is performed. Water W2 is supplied to the lower part of the methane fermentation tank 22 via the circulation pipe L6. At this time, the treated water W2 after the reaction at the electrode 33a becomes a solution in which the concentration of dissolved hydrogen sulfide is reduced as shown in equations 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 treated water W2 discharged from the power generation unit 3 to the lower part of the methane fermentation tank 22 can be circulated within the methane fermentation tank 22 without inhibiting methane fermentation.

In addition, in the wastewater treatment device 1B of this embodiment, the treated water W3 discharged via the discharge pipe L7 can be discharged as is if it satisfies the water quality that allows discharge into a river or the like. . Further, the reaction tank 5 shown in the first embodiment may be provided downstream of the discharge pipe L7. As a result, the treatment efficiency of the water W to be treated can be further improved through the treatment in the reaction tank 5, and the water W to be treated can be discharged from the wastewater treatment apparatus 1B to the outside of the system.

Moreover, in the wastewater treatment apparatus 1B of this embodiment, it is possible to generate electricity through the same steps as in the first embodiment.

As described above, in the wastewater treatment method using the wastewater treatment apparatus 1B and the wastewater treatment apparatus 1B in this embodiment, by configuring the treatment tank 2 with the acid generation tank 21 and the methane fermentation tank 22, each treatment ( Since wastewater treatment can be performed under conditions suitable for acid generation treatment and methane fermentation, wastewater treatment efficiency can be further improved.

In addition, the wastewater treatment device 1B in this embodiment has the power generation unit 3 installed on the circulation flow path provided in the treatment tank 2 (acid generation tank 21 and methane fermentation tank 22). After the reaction, the treated water W1 supplied to the side is once again supplied to the treatment tank 2 (acid generation tank 21 or methane fermentation tank 22). Therefore, the water to be treated W is repeatedly treated, and it becomes possible to improve the wastewater treatment for the treated water W2 discharged from the power generation section 3 as well. Furthermore, by reintroducing the treated water W2 discharged from the power generation unit 3 into the treatment tank 2 (acid generation tank 21 or methane fermentation tank 22), the reaction in the treatment tank 2 can proceed under favorable conditions. It also has the effect of making it possible.

[Third embodiment]
FIG. 6 is a schematic explanatory diagram showing a wastewater treatment device in a third embodiment of the present invention.
As shown in FIG. 6, a wastewater treatment apparatus 1C according to the third embodiment is the same as the wastewater treatment apparatus 1A according to the first embodiment, in which the reaction tank 5 is replaced with an aeration tank 51, and the aeration tank 51 and the The electron acceptor supply port 34a provided in the second cell 31b is connected to the electron acceptor supply port 34a through a connecting pipe L8. In addition, the supply means 4 in the wastewater treatment apparatus 1C in this embodiment can be appropriately selected from the above-mentioned supply means 4. Further, description of the same components as those of the first embodiment will be omitted.

The waste water treatment device 1C in this embodiment supplies the treated water W2 in the aeration tank 51 to the power generation section 3 and uses it as an electron acceptor in the power generation section 3. Note that the treated water W2 other than that supplied to the power generation unit 3 through the connection pipe L8 is discharged to the outside of the system as treated water W3.

The aeration tank 51 aerates the treated water W2 introduced into the tank with oxygen-containing gas (oxygen, air, etc.) by an aeration device 52, and performs aerobic treatment by aerobic microorganisms and oxidation reaction by dissolved oxygen. This is to advance the process.
As shown in FIG. 6, the aeration tank 51 in this embodiment is one into which the treated water W2 discharged from the first cell 31a of the power generation section 3 is introduced, and aerates the introduced treated water W2. Not limited. Other examples of the aeration tank 51 include one in which treated water W1 is directly introduced from the treatment tank 2 and aeration is performed.

The aeration device 52 is not particularly limited as long as it can supply gas containing oxygen to the treated water W2 in the aeration tank 51. For example, one that is widely used in aeration treatment is one that consists of a combination of a blower and an aeration pipe.

Since gas containing oxygen is introduced into the aeration tank 51 by the aeration device 52, the treated water W2 in the aeration tank 51 is a liquid containing dissolved oxygen. Therefore, the treated water W2 introduced into the second cell 31b of the power generation section 3 via the connection pipe L8 becomes an electron acceptor in the power generation section 3. Thereby, power generation can be performed by effectively utilizing what is generated during the treatment process in the wastewater treatment device 1C.

The treated water W3 after being used as an electron acceptor in the power generation section 3 is discharged from the electron acceptor outlet 34b. At this time, the discharged treated water W3 can be discharged as is if it satisfies the water quality that allows discharge into a river or the like. Alternatively, the discharged treated water W3 may be returned to the aeration tank 51 and subjected to aeration treatment again. This makes it possible to more reliably control the quality of the treated water W3 discharged outside the system.

Moreover, in the wastewater treatment apparatus 1C of this embodiment, it is possible to generate electricity through the same steps as in the first embodiment.

As described above, in the wastewater treatment device 1C and the wastewater treatment method using the wastewater treatment device 1C in this embodiment, what is generated in the treatment process proceeding within the wastewater treatment device 1C is used as an electron donor in the power generation section 3 and It can be used as an electron acceptor, making it possible to reduce running costs related to power generation.

[Fourth embodiment]
[Processing system]
The treatment system in the present invention is a combination of a wastewater treatment device and a combustion device. In particular, by combining wastewater treatment equipment that can generate electricity during a series of wastewater treatment processes with combustion equipment that burns materials, it is possible to efficiently recover and use energy. It is something to do.

FIG. 7 is a schematic explanatory diagram showing the structure of a processing system according to the fourth embodiment of the present invention.
A treatment system 100 in this embodiment includes a wastewater treatment device 1 and a combustion device 10, as shown in FIG.

The wastewater treatment device 1 in the treatment system 100 of this embodiment processes water to be treated and also generates power.
The wastewater treatment apparatus 1 in this embodiment includes one that includes a power generation section that generates power by bringing an electrode into contact with treated water after the water to be treated has been treated. Furthermore, there may be mentioned one that includes a supply means for supplying the exhaust gas generated in the combustion device to the power generation section. This makes it possible to efficiently generate power during a series of wastewater treatment processes, and to recover and utilize energy. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply means for supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side during the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing.
Examples of such a wastewater treatment apparatus 1 include the wastewater treatment apparatuses 1A to 1C in the first to third embodiments described above. In addition, as the wastewater treatment apparatus 1 in FIG. 7, the same structure as the above-mentioned wastewater treatment apparatus 1A is used.

Although a detailed description of each structure of the wastewater treatment device 1 in this embodiment will be omitted, it is preferable that the piping 42 in the supply means 4 be directly connected to the combustion device 10, as shown in FIG. Thereby, the configuration of the processing system 100 can be simplified, and cost and energy savings can be achieved.

The combustion device 10 in the processing system 100 of this embodiment burns substances. Further, exhaust gas generated in the combustion device 10 is supplied to the wastewater treatment device 1.
As the combustion device 10 in this embodiment, a known configuration capable of burning substances can be used. The combustion device may be newly installed for the processing system 100 in this embodiment, or an existing combustion device may be used.
The substances to be burned in the combustion device 10 include at least one of carbon components, sulfur components, and nitrogen components. The substance is not particularly limited as long as it generates exhaust gas containing a component exhibiting the following.

An example of the combustion device 10 is one that burns waste generated during the treatment process in the wastewater treatment device 1. Thereby, in addition to generating electricity in a series of treatment steps in wastewater treatment, it is also possible to carry out a process related to suppressing a decrease in electrode reaction (power generation) efficiency. Therefore, the processing system 100 can improve energy recovery and utilization efficiency and reduce costs.
Specific examples of such a combustion device 10 include one that incinerates sludge produced in the wastewater treatment device 1, one that burns biogas produced in the wastewater treatment device 1, and the like. This makes it possible to easily obtain a combustion target, and also to use an existing combustion device, making it possible to significantly reduce initial costs. In particular, when the combustion target is sludge, the sludge contains a lot of organic matter, so the combustion process generates exhaust gas containing a lot of carbon dioxide. In recent years, carbon dioxide emission regulations have become stricter in view of the impact on the environment. Therefore, by supplying exhaust gas containing carbon dioxide to the power generation section 3, a decrease in electrode reaction efficiency in the power generation section 3 is suppressed, and since carbon dioxide is dissolved in the electrolyte solution in the power generation section 3, the carbon dioxide It also has the effect of making it possible to suppress discharge to the outside of the system.

As described above, in the treatment system of this embodiment, by combining a wastewater treatment device and a combustion device, and installing a power generation unit using electrodes in the wastewater treatment device, It becomes possible to generate electricity. This makes it possible to efficiently generate power and recover and use energy without increasing the size of equipment. Further, by performing an electrode reaction using components contained in treated water after treating the water to be treated, it becomes possible to effectively utilize components generated within the wastewater treatment process. Furthermore, by providing a supply means for supplying the exhaust gas generated in the combustion device to the power generation section, it is possible to suppress an increase in pH on the cathode side during the electrode reaction. This suppresses a decrease in the efficiency of the electrode reaction and makes it possible to improve the efficiency of power generation and electrochemical processing as a processing system.

In addition, the embodiment mentioned above shows an example of a wastewater treatment device, a wastewater treatment method, and a treatment system. The wastewater treatment device, wastewater treatment method, and treatment system according to the present invention are not limited to the embodiments described above, and the wastewater treatment device and wastewater treatment system according to the embodiments described above are not limited to the embodiments described above. The processing method and processing system may be modified.

For example, the wastewater treatment device in this embodiment may include a plurality of power generation units. For example, it is possible to include both the power generation section shown in the first embodiment and the power generation section shown in the second embodiment. Thereby, it becomes possible to perform power generation at a plurality of locations by effectively utilizing the treatment process of the water to be treated W in the wastewater treatment device, and it becomes possible to improve both the wastewater treatment efficiency and the power generation efficiency.

Further, for example, the electrode 33a and the electrode 33b of the wastewater treatment apparatus in this embodiment may be arranged in the housing with the surfaces of the electrode 33a and the electrode 33b exposed, and the power generation unit may be used as an electrode unit that can be taken out from the power generation unit 3. 3 may be provided. This makes it easy to take out the electrodes 33a and the electrodes 33b from the power generation section 3 during maintenance, thereby facilitating maintenance work.

Further, for example, in the wastewater treatment apparatus in this embodiment, an electrode 33a and an electrode 33b may be provided in the settler 23 portion of the treatment tank 2 (methane fermentation tank 22) as the power generation unit 3. Note that the electrode 33a and the electrode 33b may be provided near the settler 23, or the settler 23 itself may be used as the electrode 33a and the electrode 33b. This allows the power generation section 3 to be incorporated into the processing tank 2, making it possible to further downsize the equipment.

Further, for example, in the wastewater treatment apparatus in this embodiment, the electrode 33b may be provided in the aeration tank 51, and the aeration tank 51 may function as the second cell 31b of the power generation section 3. Thereby, the power generation section 3 and the reaction tank 5 (aeration tank 51) are integrated, and it becomes possible to further downsize the equipment.

Further, for example, the wastewater treatment device in this embodiment may be provided with an insulation mechanism. The insulation mechanism is not particularly limited as long as it can insulate the treated water (treated water W2) other than the treated water W1 that reacts in the power generation section 3.
Examples of the insulation means using the insulation mechanism include eliminating electrical contact (liquid junction) between the electrode 33a of the power generation section 3 and the treated water W2 or shortening the liquid junction time. Examples of such liquid junction eliminating means or liquid junction time shortening means include means for making the flow of the treated water W2 discontinuous (intermittent), means for interposing an insulator such as air in the treated water W2, Alternatively, a combination of these means may be used. This prevents the electrons generated in the power generation section 3 from flowing outside of the area between the electrodes 33a and 33b, thereby improving power generation efficiency.
Note that the wastewater treatment apparatus in this embodiment may also provide insulation for the structures (treatment tank and piping) that constitute the wastewater treatment apparatus as shown in the first embodiment. Thereby, a further insulation effect can be obtained, and the power generation efficiency in the power generation section 3 can be improved.

Further, for example, the wastewater treatment device in this embodiment may omit some structures to further simplify the device configuration.
An example of the structure that can be omitted is the ion exchanger 35. This makes it possible to simplify the power generation section 3 and facilitate maintenance work.
Furthermore, other examples of structures that can be omitted include the electron acceptor supply port 34a and the electron acceptor discharge port 34b in the second cell 31b. This makes it possible to further simplify the power generation section 3. At this time, one surface of the electrode 33b may be in contact with the treated water W1 or the ion exchanger 35, and the other surface may be in direct contact with the outside air (air) as a whole. Furthermore, it is preferable to provide the surface of the electrode 33b on the outside air side with a breathable material that is easy to replace or clean. Thereby, it is possible to suppress solid impurities such as dust from adhering to the surface of the electrode 33b.

Further, for example, the treatment system in this embodiment is not limited to the wastewater treatment apparatuses shown in the first to third embodiments, and may use any of the configurations of the wastewater treatment apparatuses described above. Thereby, it becomes possible to appropriately select a combination of a wastewater treatment device and a combustion device as a treatment system, and improve the efficiency of energy recovery and utilization.

The wastewater treatment device and the wastewater treatment method of the present invention are used for wastewater treatment to treat water to be treated. In particular, it is suitably used in wastewater treatment where reducing substances are generated by treating water to be treated.

Furthermore, the treatment system of the present invention combines a wastewater treatment device that generates electricity and a combustion device during a series of treatment processes in wastewater treatment for treating water to be treated, and is capable of recovering and utilizing energy. It is suitable for use as a system.

1A, 1B, 1C wastewater treatment device, 10 combustion device, 100 treatment system, 2 treatment tank, 21 acid generation tank, 22 methane fermentation tank, 23 settler, 24 pH adjustment means, 3 power generation section, 31a first cell, 31b 2nd cell, 32a treated water inlet, 32b treated water outlet, 33a, 33b electrode, 34a electron acceptor supply port, 34b electron acceptor outlet, 35 ion exchanger, 4 supply means, 41 exhaust gas supply port, 42 piping, 43 temperature adjustment mechanism, 5 reaction tank, 51 aeration tank, 52 aeration device, L1 introduction piping, L2 connection piping, L3, L7 discharge piping, L4, L8, L9 connection piping, L5, L6 circulation piping, W cover Treated water, W1, W2, W3 Treated water

Claims (6)

A wastewater treatment device that processes water to be treated,
a power generation unit that generates power by bringing an anode-side electrode into contact with the treated water after the treated water has been treated;
Exhaust gas supply means for supplying exhaust gas generated in the combustion device to the cathode side of the power generation section ;
an electron acceptor supply means for supplying an electron acceptor to the cathode side of the power generation section ,
A wastewater treatment device , wherein the treated water contains hydrogen sulfide or hydrogen sulfide ions . The wastewater treatment device according to claim 1 , further comprising a temperature adjustment mechanism that adjusts the temperature of the exhaust gas. The wastewater treatment device according to claim 2, wherein the temperature adjustment mechanism adjusts the temperature of the exhaust gas to 100 degrees or less. The wastewater treatment device according to any one of claims 1 to 3 , wherein the combustion device incinerates sludge produced in wastewater treatment. A wastewater treatment method for treating water to be treated, the method comprising:
A power generation step in which the treated water after the treatment water is brought into contact with an anode-side electrode to generate power;
a supply step of supplying exhaust gas generated in the electron acceptor and the combustion device to the cathode side of the power generation step ,
A wastewater treatment method , wherein the treated water contains hydrogen sulfide or hydrogen sulfide ions . A wastewater treatment device according to any one of claims 1 to 4,
A processing system comprising a combustion device.