JP2022067576A - Water treatment apparatus and water treatment method - Google Patents

Abstract

To provide water treatment apparatus and a water treatment method capable of recovering and utilizing energy by electrode reaction and performing desulfurization treatment in anaerobic treatment of treated water, and suppressing the decrease in electrode reaction efficiency.SOLUTION: There is provided a water treatment method and a water treatment apparatus including a reaction part that performs an electrode reaction using a reducing substance in treated water as an electron donor in an anaerobic treatment of treated water, and water content adjustment means that adjusts the water content on the cathode side of the reaction part. According to the present invention, by installing a reaction part using electrodes, efficient power generation and desulfurization treatment can be carried out in a series of treatment processes in water treatment. In addition, by adjusting the amount of water in the cathode solution, the decrease in concentration of electrode reaction components in the cathode solution due to water generated by the electrode reaction can be suppressed. This prevents the decrease in the electrode reaction efficiency and enables the improvement of the efficiency of power generation and desulfurization treatment.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water treatment apparatus and a water treatment method.

Various treatment methods are known as water treatment for treating water to be treated. Such water treatment includes physical characteristics related to the water to be treated, such as the components contained in the water to be treated and the amount of water to be discharged, and the balance between treatment efficiency and cost. In addition, the treatment method is selected in consideration of the equipment for carrying out water treatment and the characteristics related to operation.
Further, in water treatment, the efficiency of water treatment is improved by combining a plurality of different water treatment methods.

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

Japanese Unexamined Patent Publication No. 2004-330182

As described in Patent Document 1, in water treatment that combines electrochemical treatment and biological treatment, a reaction with high reaction efficiency is allowed to proceed for each treatment, and the treatment efficiency of the entire water treatment is improved. Is possible. On the other hand, in general, electrochemical treatment has a problem that the burden of running cost related to power consumption is large. In the water treatment described in Patent Document 1, it is possible to reduce the running cost as compared with the electrochemical treatment alone. However, in the water treatment described in Patent Document 1, it is necessary to supply energy related to electrochemical treatment and biological treatment from outside the water treatment system. Therefore, further energy saving during water treatment is required.

In recent years, in order to suppress equipment drive power during water treatment and to improve energy saving, a technique capable of recovering and utilizing energy in the water treatment process has been studied.
As one of such technologies, energy recovery using biogas generated by biological treatment is performed, but the heat energy obtained by the storage and purification equipment of biogas and the combustion of biogas is used as gas. Ancillary equipment such as equipment that converts electric energy into electric energy via an engine or gas turbine is required. Therefore, in water treatment, there is a demand for a technique for recovering and utilizing energy more easily and efficiently.

As a technique for recovering energy easily and efficiently in water treatment, it is conceivable to provide an electrode on the water treatment process and recover electrical energy directly by an electrode reaction. At this time, by using a reducing substance in the water to be treated as an electron donor to be subjected to the electrode reaction, it is possible to perform electrochemical treatment on the water to be treated at the same time as energy recovery by the electrode reaction, and the efficiency of water treatment is improved. Realization of energy saving can be expected. In particular, by using hydrogen sulfide generated by the anaerobic treatment as an electron donor, it is possible to perform the desulfurization treatment at the same time.

On the other hand, the present inventors have a problem that when an electrode is provided on the water treatment step and an electrode reaction is performed, water is generated on the cathode side, so that the concentration of the electrode reaction component is lowered and the electrode reaction efficiency is lowered. I found that there is.

An object of the present invention is to provide a water treatment apparatus and a water treatment method capable of recovering and utilizing energy by an electrode reaction and desulfurization treatment in anaerobic treatment of water to be treated and suppressing a decrease in electrode reaction efficiency. To provide.

As a result of diligent studies on the above-mentioned problems, the present inventor performs an electrode reaction using the reducing substance in the treated water as an electron donor when anaerobically treating the water to be treated, thereby efficiently recovering energy. By making it possible to use and desulfurization treatment and adjusting the water content on the cathode side in the electrode reaction, it is possible to suppress the decrease in the concentration of the electrode reaction component on the cathode side in the electrode reaction and suppress the decrease in the efficiency of the electrode reaction. The present invention was completed by finding that it is possible.
That is, the present invention is the following water treatment apparatus and water treatment method.

The water treatment apparatus of the present invention for solving the above problems is a water treatment apparatus that performs anaerobic treatment on the water to be treated, and has a reaction unit that performs an electrode reaction using a reducing substance in the water to be treated as an electron donor. It is characterized by including a water content adjusting means for adjusting the water content on the cathode side of the reaction unit.

In the water treatment apparatus of the present invention, by installing a reaction unit using electrodes in the water treatment apparatus, it becomes possible to carry out power generation in a series of treatment processes in water treatment. As a result, efficient power generation can be performed and energy can be recovered and used without increasing the size of the equipment. Further, it is possible to carry out an efficient desulfurization treatment without separately providing equipment for the desulfurization treatment. Further, by providing a means for adjusting the amount of water in the cathode solution, it is possible to suppress a decrease in the concentration of the electrode reaction component in the cathode solution due to water generated in the electrode reaction. As a result, it is possible to suppress a decrease in the efficiency of the electrode reaction and improve the efficiency of power generation and desulfurization treatment.

Further, as one embodiment of the water treatment apparatus of the present invention, the water content adjusting means is characterized by including a contact opportunity improving means for increasing the contact opportunity between the cathode solution and the gas.
According to this feature, the water content in the cathode solution can be adjusted by a relatively simple structure. Further, since the energy required for adjusting the water content in the cathode solution is small, it is possible to reduce the running cost of the water treatment device.

Further, as one embodiment of the water treatment apparatus of the present invention, the contact opportunity improving means is characterized by aeration.
According to this feature, the simple structure makes it possible to adjust the amount of water in the cathode solution. Further, since the aeration amount can be controlled relatively easily, the water content in the cathode solution can be easily and appropriately adjusted.

Further, as one embodiment of the water treatment apparatus of the present invention, the contact opportunity improving means includes a volatilizer that sucks up the cathode solution, and the volatilizer has a feature that the water in the sucked up cathode solution is naturally evaporated.
According to this feature, the simple structure makes it possible to adjust the amount of water in the cathode solution. In addition, since power is not required to adjust the amount of water in the cathode solution, the running cost of the water treatment device can be significantly reduced.

Further, as one embodiment of the water treatment apparatus of the present invention, the water content adjusting means is characterized by including a heating means.
According to this feature, it is possible to efficiently adjust the amount of water in the cathode solution. Further, by using the heat generated by the water treatment, it is possible to reduce the running cost related to the adjustment of the water content in the cathode solution.

Further, as one embodiment of the water treatment apparatus of the present invention, the water content adjusting means is characterized by including a membrane separating means using a membrane.
According to this feature, it is possible to adjust the amount of water in the cathode solution by discharging a part of the water in the cathode solution through the membrane. Further, the water content can be adjusted by minimizing the influence on the cathode solution from the outside, and the influence on the electrode reaction component in the cathode solution can be reduced.

Further, one embodiment of the water treatment apparatus of the present invention is characterized by comprising a detecting means for detecting the water content or the solute concentration in the cathode solution in the reaction unit.
According to this feature, by providing a detecting means for detecting the water content or the solute concentration in the cathode solution, it is possible to determine whether or not the water content in the cathode solution is appropriate. Further, based on this determination, by operating the water content adjusting means, it is possible to appropriately adjust the water content in the cathode solution and more effectively suppress the decrease in the electrode reaction efficiency.

Further, the water treatment method of the present invention for solving the above-mentioned problems is a water treatment method for performing anaerobic treatment on the water to be treated, in which an electrode reaction using a reducing substance in the water to be treated as an electron donor is performed. It is characterized by including a reaction step and a water content adjusting step for adjusting the water content on the cathode side of the reaction step.
In the water treatment method of the present invention, by providing an electrode reaction step using an electrode in water treatment, it becomes possible to carry out power generation in a series of treatment processes in water treatment. As a result, efficient power generation can be performed and energy can be recovered and used without increasing the size of the equipment. Further, it is possible to carry out an efficient desulfurization treatment without separately providing equipment for the desulfurization treatment. Further, by providing a water content adjusting step for adjusting the water content in the cathode solution, it is possible to suppress a decrease in the concentration of the electrode reaction component in the cathode solution due to water generated in the electrode reaction. As a result, it is possible to suppress a decrease in the efficiency of the electrode reaction and improve the efficiency of power generation and desulfurization treatment.

According to the present invention, a water treatment apparatus and a water treatment method capable of recovering and utilizing energy by an electrode reaction and desulfurization treatment in anaerobic treatment of water to be treated and suppressing a decrease in electrode reaction efficiency are provided. Can be provided.

It is a schematic explanatory drawing of the water treatment apparatus in 1st Embodiment of this invention. It is a schematic explanatory drawing which shows the water content adjusting means in the water treatment apparatus of 1st Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the water content adjusting means in the water treatment apparatus of 1st Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the water content adjusting means in the water treatment apparatus of 1st Embodiment of this invention. It is a schematic explanatory drawing which shows another aspect of the water content adjusting means in the water treatment apparatus of 1st Embodiment of this invention. It is a schematic explanatory drawing of the water treatment apparatus in the 2nd Embodiment of this invention. It is a schematic explanatory drawing of the water treatment apparatus in the 3rd Embodiment of this invention. It is a schematic explanatory drawing which shows the other aspect of the water treatment apparatus in the 3rd Embodiment of this invention. It is a schematic explanatory drawing of the water treatment apparatus in 4th Embodiment of this invention.

Hereinafter, embodiments of the water treatment apparatus and the water treatment method according to the present invention will be described in detail with reference to the drawings. The water treatment method in the present invention shall be replaced with the description of the operation of the water treatment device in the present invention.
The water treatment apparatus and the water treatment method described in the embodiments are merely exemplified for explaining the water treatment apparatus and the water treatment method according to the present invention, and the present invention is not limited thereto.

In the water 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 water treatment device, or is generated as the treatment progresses in the water treatment device and is present 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 paper and pulp 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 may be one that is more likely to emit electrons than the electron acceptor, that is, one having 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, and ammonia. Can be mentioned.

[First Embodiment]
[Water treatment equipment]
FIG. 1 is a schematic explanatory view showing the structure of a water treatment apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the water treatment apparatus 1A in the present embodiment includes a treatment tank 2, a reaction unit 3, and a water content adjusting means 4 on the cathode side of the reaction unit 3. Further, the water treatment device 1A connects the introduction pipe L1 for introducing the water to be treated W into the treatment tank 2, the treatment tank 2 and the reaction unit 3, and treats the water to be treated W after being treated in the treatment tank 2. It is provided with a connection pipe L2 for supplying water W1 to the reaction unit 3 and a discharge pipe L3 for discharging the treated water W2 after the electrode reaction from the reaction unit 3.

(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 treated water W1 after the treatment contains a reducing substance. For example, as biological treatment (anaerobic treatment) in an anaerobic environment, methane fermentation by acid-producing bacteria and methanogenic bacteria, denitrification treatment in which nitric acid and nitrite are reduced by denitrifying bacteria, and sulfuric acid by sulfate-reducing bacteria. Sulfate reduction treatment and the like for reducing the above can be mentioned. Further, as another example of biological treatment, as biological treatment (aerobic treatment) in an aerobic environment, activated sludge treatment using activated sludge can be mentioned, but aeration power is not required and excess sludge is generated. The treatment performed in the treatment tank 2 of the present embodiment is preferably an anaerobic treatment because it has a high merit of introduction such that it hardly occurs. Further, methane fermentation that produces methane is particularly preferable from the viewpoint of processing cost and usefulness of the produced gas.

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 treated water W1 after the treated water W is treated, 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 becomes the treated water W1 containing a reducing substance, and is introduced into the reaction unit 3 via the connecting pipe L2.

(Reaction part)
The reaction unit 3 is for performing an electrode reaction using the reducing substance in the treated water W1 as an electron donor. Further, in the reaction unit 3, power generation and desulfurization treatment can be performed by this electrode reaction.
Hereinafter, the structure of the reaction unit 3 of the present embodiment will be described from the viewpoint of power generation. The details of the desulfurization treatment by the reaction unit 3 of this embodiment will be described later.

As shown in FIG. 1, the reaction unit 3 of the present embodiment is provided after the treatment 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 35 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 treated water W1 introduced from the treatment tank 2 via the connecting 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 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). This makes it possible to recover and utilize the electrical energy generated by the reducing substance acting as an electron donor in the reaction unit 3.

The first cell 31a may be any as long as it includes an electrode 33a and is formed so that the treated water W1 comes into contact with the electrode 33a, and the material and shape are not particularly limited. For example, as shown in FIG. 1, the treated water W2 having a space capable of temporarily storing the treated water W1 introduced from the treated water introduction port 32a via the connection pipe L2 and contacting the electrode 33a is stored. It is possible to include a discharge pipe L3 for discharging from the treated water discharge port 32b. As a result, the reducing substance in the treated water W1 donates electrons to the electrode 33a as an electron donor, and then is rapidly 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 treated water W1 in contact with the electrode 33a and control the mass transfer rate with respect to the electrode 33a.

The treated water W2 discharged through the discharge pipe L3 can be discharged as it is as long as it satisfies the water quality that can be discharged to a river or the like. Further, a treatment facility for further treating the treated water W2 may be provided in the subsequent stage of the discharge pipe L3, and the treated water W2 may be treated and then discharged to the outside of the system. Such treatment equipment is not particularly limited as long as it can be treated so that the treated water W2 can be discharged to the outside of the system or to a river. For example, an aeration tank, a pH adjustment tank, and the like can be mentioned.

The second cell 31b may be any as long as it has an electrode 33b and is formed so as to store or supply an electron acceptor for a reducing substance in the treated water W1, 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, but the form of the electron acceptor in the present embodiment is preferably a liquid. This makes it possible to fully exert the effect of suppressing the decrease in the electrode reaction efficiency according to the present invention.
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, a solution of the electron acceptor may be used to fill the inside of the second cell 31b in which the electrode 33b is arranged. As a result, the function of suppressing the decrease in the electrode reaction efficiency by the water content adjusting means 4, which will be described later, is effectively exhibited.

Specific examples of the electron acceptor in the present embodiment include, 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. 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 electrode reaction efficiency can be further improved. From the viewpoint of improving the electrode reaction 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 space capable of storing a liquid is provided in the second cell 31b, and electrons are used as the electron acceptor supply port 34a and the electron acceptor discharge port 34b, respectively. It is possible to provide a solution capable of supplying a solution of the receptor and discharging the solution after the reaction.
As a result, the electrons from the electrode 33a can be received by the electron acceptor via the electrode 33b, and a current flows between the electrodes 33a and 33b to generate electricity. Further, the electron acceptor after the reaction is rapidly discharged to the outside of the reaction unit 3 via the electron acceptor discharge port 34b.

Further, as shown in FIG. 1, the second cell 31b in the present embodiment is connected to the reservoir 40 of the water content adjusting means 4 described later via the electron acceptor supply port 34a and the electron acceptor discharge port 34b. There is.

In FIG. 1, an electron acceptor supply port 34a and an electron acceptor discharge port 34b are provided one by one, but the present invention is not limited thereto. For example, a plurality of electron receptor supply ports 34a and electron receptor discharge ports 34b may be provided. For example, in order to deal with the case where gas and liquid are present in the second cell 31b due to the reaction at the electrode 33b, a plurality of electron acceptor discharge ports 34b are provided to discharge the gas and the liquid. It is possible to separate each of them.

The ion exchanger 35 may have a known structure capable of allowing ions to pass through, and is not particularly limited. In particular, a cation exchange membrane capable of transmitting 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 electrode reaction efficiency can be improved. .. Further, it is more preferable that the ion exchanger 35 has low oxygen permeability. As a result, the electron acceptor (particularly 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 35 is provided as a separate body from the electrode 33a and the electrode 33b, but is not limited thereto. For example, the electrode 33a and / or the electrode 33b may be integrated with a material having an ion exchange ability. As a result, the entire reaction 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 treated water W1 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 treated water W1 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 related to 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.) widely used as electrode materials in the electrochemical field. Further, examples of the shape of the electrode 33a include a flat plate shape, a rod shape, a mesh shape, and the like.
In particular, as the electrode 33a of this embodiment, it is preferable to use one made of a porous body in view of the electrode reaction efficiency. For example, as the electrode 33a, in addition to using carbon fibers such as carbon paper and carbon cloth which are porous bodies, foamed metal, porous metal, and metal mesh can be used.

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 related to 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.) widely used as electrode materials in the electrochemical field. Further, examples of the shape of the electrode 33b include a flat plate shape, a rod shape, a mesh shape, and the like.
In particular, as the electrode 33b of the present embodiment, it is preferable to use one made of a porous body in view of the electrode reaction efficiency. For example, as the electrode 33b, in addition to using carbon fibers such as carbon paper and carbon cloth which are porous bodies, foamed metal, porous metal, and metal mesh may be used.

Hereinafter, the reaction and the process related to the electrode reaction in the water treatment apparatus according to the first embodiment of the present invention will be described with reference to FIG.
In the reaction and step related to the electrode reaction in the water treatment apparatus 1A of the present embodiment, a reducing substance produced by anaerobic treatment of the water to be treated W is used as an electron donor, and a solution containing an oxidizing agent and oxygen is received as an electron. It explains what is used as a body.
The description of the reaction and the process based on FIG. 1 shows an example of the electrode reaction in this embodiment, and is not limited thereto. Further, the following description describes the reaction and process related to the treatment tank 2 to the reaction unit 3, and the description of the reaction and process related to other configurations (introduction pipe L1, discharge pipe L3, etc.) is omitted. ing. 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 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 treated in the treatment tank 2 and containing the reducing substance is introduced into the first cell 31a in the reaction unit 3 via the connecting 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 by the formulas 1 and 2, in the reaction R1, the hydrogen sulfide contained in the treated water W1 after being treated in the treatment tank 2 donates electrons to the electrode 33a, and the hydrogen sulfide itself is oxidized. This makes it harmless and odorless. Therefore, the water treatment device 1A 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 as the reaction proceeds, detoxification and deodorization become possible.

Based on the reaction formulas shown in the formulas 1 and 2, after the reaction at the electrode 33a proceeds, the 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 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. At this time, the hydrogen ion that has moved to the second cell 31b side via the ion exchanger 35 also reacts with the electron acceptor by the reaction R3. The reaction (reaction R4) at the electrode 33b at this time is represented by the following reaction formula (formula 3). Oxygen in Equation 3 corresponds to an electron acceptor.

A current flows between the electrodes 33a and 33b based on the above-mentioned reactions R1 to R4 and steps S1 to S3. As a result, the reaction using the reducing substance (reducing substance contained in the treated water W1) in the water to be treated W as an electron donor proceeds, and the water treatment apparatus 1A of the present embodiment performs power generation and desulfurization treatment. ..
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 electric energy is not particularly limited. For example, it may be used for driving the equipment of the water treatment device, or may be used outside the water treatment device.

In the electrode reaction in the water treatment apparatus of the present embodiment, as described above, the reaction R3 causes the hydrogen ion (H ⁺ ) to move to the cathode side, so that the reaction R4 based on the formula 3 proceeds. At this time, water ( _H2O ) increases in the cathode solution, so that the concentration of electron acceptors in the cathode solution decreases. This causes a problem that the electrode reaction efficiency is lowered. Therefore, it is preferable that the water treatment apparatus 1A in the present embodiment is provided with means for adjusting the water content on the cathode side in the reaction unit 3.

(Moisture content adjusting means)
The water content adjusting means 4 is not particularly limited as long as it can adjust the water content on the cathode side. Examples of the water content adjusting means 4 include those including means for adjusting the water content in the cathode solution in the second cell 31b. At this time, in addition to directly adjusting the water content in the cathode solution in the second cell 31b, the water content in the cathode solution once discharged from the second cell 31b may be adjusted.
Here, from the viewpoint of suppressing the influence on the electrode reaction in the second cell 31b, the water content adjusting means 4 in the present embodiment adjusts the water content with respect to the cathode solution once discharged from the second cell 31b. I will mainly explain what to do.

Hereinafter, a specific example of the water content adjusting means 4 in this embodiment will be described. The following description of the water content adjusting means 4 is based on an example of the water content adjusting means 4 in the present embodiment, and is not limited thereto.

FIG. 2 is a schematic explanatory view according to the water content adjusting means 4 of the present embodiment. Note that FIG. 2 is an enlarged view of the periphery of the reaction unit 3 and the water content adjusting means 4 in the water treatment apparatus 1A, and the treatment tank 2 is not shown.

As shown in FIG. 2, the water content adjusting means 4 includes a reservoir 40 connected to the second cell 31b and a contact opportunity improving means 4a for increasing the contact opportunity between the cathode solution and the gas in the reservoir 40. Things can be mentioned. Here, the cathode solution is recovered from the second cell 31b via the pipe L4 connecting the electron acceptor discharge port 34b and the reservoir 40, and through the pipe L5 connecting the electron acceptor supply port 34a and the reservoir 40. The cathode solution after adjusting the water content is returned to the second cell 31b. As a result, the amount of water contained in the cathode solution in the reservoir 40 is adjusted, and the cathode solution having an appropriate amount of water is returned to the second cell 31b again to improve the electrode reaction efficiency in the reaction unit 3. It is possible to suppress the decrease.

The reservoir 40 in the present embodiment may have a structure as a storage tank capable of storing the cathode solution once discharged from the second cell 31b, and may further have a structure in which the upper portion is open. preferable. As a result, the water discharged from the cathode solution by the contact opportunity improving means 4a is effectively discharged to the outside of the reservoir 40, and the amount of water in the cathode solution can be appropriately adjusted. The water treatment apparatus 1A in the present embodiment may be provided with a separate source of the cathode solution for the second cell 31b, but it is preferable that the reservoir 40 functions as a source of the cathode solution. This makes it possible to reduce the equipment cost related to the water treatment device 1A.

The contact opportunity improving means 4a in the present embodiment discharges the water in the cathode solution to the outside of the cathode solution by increasing the contact opportunity between the cathode solution in the reservoir 40 and the gas.

As a specific example of the contact opportunity improving means 4a, as shown in FIG. 2, an air supply port 41 for supplying gas to the reservoir 40 is provided, and the air supply port 41 is provided with a gas supply source such as a blower. A pipe 42 for supplying gas from (not shown) may be connected.
Here, the air supply port 41 and the pipe 42 can use a known configuration related to gas supply / transfer. More specifically, it is possible to supply fine bubbles from the air supply port 41 by using a structure related to aeration (aeration). As a result, the gas supplied from the air supply port 41 and the cathode solution come into efficient contact with each other, and the simple structure makes it possible to efficiently adjust (reduce) the amount of water in the cathode solution.
The gas supplied from the gas supply source is not particularly limited. For example, supplying a gas usually used in aeration (aeration) treatment such as air can be mentioned.

As shown in FIG. 2, the contact opportunity improving means 4a is not limited to the one provided with a structure related to aeration. FIG. 3 is a schematic explanatory view showing another aspect of the contact opportunity improving means 4a in the water content adjusting means 4 of the present embodiment. Note that FIG. 3 is an enlarged view of the periphery of the reaction unit 3 and the water content adjusting means 4 in the water treatment apparatus 1A, as in FIG. 2, and the treatment tank 2 is not shown.

As shown in FIG. 3, another example of the contact opportunity improving means 4a includes a reservoir 40 provided with a volatilizer 43 that sucks up the cathode solution.
The volatilizer 43 sucks up the cathode solution and naturally evaporates the water in the sucked up cathode solution. More specifically, the volatilizer 43 has a function of sucking up a solution, and also has a function of contacting the sucked up solution with air in the atmosphere on the surface of the volatilizer 43 and spontaneously evaporating the moisture in the solution into the atmosphere. It is made of the material or structure of the material. Specific examples of the volatilizer 43 in this embodiment include a non-woven fabric and a structure having a sponge-like structure.

A part of the volatilizer 43 is arranged so as to be immersed in the cathode solution in the reservoir 40. Then, the cathode solution in the reservoir 40 is sucked up by the volatilizer 43, and water naturally evaporates from the surface of the volatilizer 43 facing the atmosphere. This makes it possible to adjust the amount of water in the cathode solution. Further, since no power is required to adjust the amount of water in the cathode solution, the running cost of the water treatment device 1A can be significantly reduced.

Further, as the water content adjusting means 4 of the present embodiment, means other than the contact opportunity improving means 4a may be provided. 4 and 5 are schematic explanatory views showing another aspect of the water content adjusting means 4 of the present embodiment. Note that FIGS. 4 and 5 are enlarged views of the periphery of the reaction unit 3 and the water content adjusting means 4 in the water treatment apparatus 1A, and the treatment tank 2 is not shown.

As one of the other aspects of the water content adjusting means 4 in this embodiment, as shown in FIG. 4, the heating means 4b may be provided.
By heating the cathode solution with the heating means 4b, the water content in the cathode solution can be discharged (transpiration). This makes it possible to efficiently adjust the amount of water in the cathode solution.

The heating means 4b may be any as long as it can heat the cathode solution, and its structure and arrangement are not particularly limited. For example, as shown in FIG. 4, a heating unit 44 may be provided on the pipe L4. Further, as another example, a heating unit may be provided in the reservoir 40.
In addition to using a known heating device, the heating unit 44 may use a heating device used in another treatment step in the water treatment device 1A. In particular, by using the heat generated by the water treatment, it is possible to reduce the running cost related to the adjustment of the water content in the cathode solution.

Further, as another aspect of the water content adjusting means 4 in this embodiment, as shown in FIG. 5, a membrane separating means 4c using a membrane may be provided.
The membrane separation means 4c can partially separate the water content in the cathode solution. This makes it possible to adjust the amount of water in the cathode solution. Further, the water content can be adjusted by minimizing the influence on the cathode solution from the outside, and the influence on the electrode reaction component in the cathode solution can be reduced.

The membrane separating means 4c is not particularly limited as long as it can partially separate water in the cathode solution using a membrane. For example, as shown in FIG. 5, a membrane separation portion 46 having spaces 46a and 46b partitioned by a semipermeable membrane 45 is provided on the pipe L4, a cathode solution is introduced into the space 46a on the pipe L4 side, and the semipermeable membrane is introduced. Partially permeating the water in the cathode solution into the space 46b via the membrane 45 can be mentioned. This makes it possible to adjust the water content of the cathode solution discharged from the space 46a and introduced into the reservoir 40.

The semipermeable membrane 45 may be either a forward osmosis membrane or a reverse osmosis membrane, as long as the solvent (water) can be permeated from the cathode solution in the space 46a to the space 46b side. For example, when a forward osmosis membrane is used as the semipermeable membrane 45, the space 46b is filled with a solution having a concentration higher than that of the cathode solution so that the water in the cathode solution is permeated to the space 46b side. On the other hand, when a reverse osmosis membrane is used as the semipermeable membrane 45, the space 46b is provided with a solution having a concentration lower than that of the cathode solution, so that the water content in the cathode solution is permeated to the space 46b side. This makes it possible to adjust the amount of water in the cathode solution.

The water content adjusting means 4 of the present embodiment may be any one of the contact opportunity improving means 4a, the heating means 4b, and the membrane separating means 4c, or a combination of a plurality of them.

Further, in addition to the above-mentioned water content adjusting means 4, a flow rate adjusting mechanism such as a valve is provided in any one or all of the electron acceptor supply port 34a, the electron acceptor discharge port 34b, the pipe L4, and the pipe L5, and the second. The concentration of the electron acceptor in the cell 31b of the cell 31b may 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. This makes it possible to suppress a decrease in the reaction efficiency related to electron transfer between the electrodes 33a and 33b, and to suppress a decrease in the electrode reaction efficiency.

The water treatment apparatus 1A in the present embodiment uses the reducing substance in the water to be treated W as an electron donor, generates electricity by an electrochemical reaction (electrode reaction), and recovers and utilizes the energy. 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 (reaction unit 3). Therefore, it is preferable that the water treatment apparatus 1A in the present embodiment is subjected to insulation treatment except for the portion where the electrochemical reaction is performed (reaction unit 3). Specific examples of the insulation treatment include, for example, installing the treatment tank 2 on the upper part of the insulator, configuring the outer wall or the inner wall of the treatment tank 2 with an insulator, and insulating the outer wall or the inner wall of the treatment tank 2. For example, coating with a 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.

As described above, the water treatment method using the water treatment device 1A and the water treatment device 1A of the present embodiment makes it possible to carry out the electrode reaction in a series of treatment processes in the water treatment. As a result, efficient power generation can be performed and energy can be recovered and used without increasing the size of the equipment. Further, it is possible to carry out an efficient desulfurization treatment without separately providing equipment for the desulfurization treatment. Further, by providing a means for adjusting the amount of water in the cathode solution, it is possible to suppress a decrease in the concentration of the electrode reaction component in the cathode solution due to water generated in the electrode reaction. As a result, it is possible to suppress a decrease in the efficiency of the electrode reaction and improve the efficiency of power generation and desulfurization treatment.

[Second Embodiment]
FIG. 6 is a schematic explanatory view showing a water treatment apparatus according to the second embodiment of the present invention.
The water treatment device 1B according to the second embodiment is provided with the detection means 5 for detecting the water content or the solute concentration in the cathode solution with respect to the water treatment device 1A according to the first embodiment. The water content adjusting means 4 may be any of the water content adjusting means 4 shown in the first embodiment, and is not particularly limited. Further, the description of the same configuration as that of the first embodiment will be omitted.

By providing the detecting means 5 in the water treatment apparatus 1B of the present embodiment, it is possible to grasp the water content and the solute concentration contained in the cathode solution. Further, by controlling the water content adjusting means 4 based on the result of the detecting means 5, it is possible to appropriately maintain the water content in the cathode solution.
The detecting means 5 and the water content adjusting means 4 may be connected so as to be automatically controllable, or the operator may operate the water content adjusting means 4 based on the result of the detecting means 5. .. From the viewpoint of reducing the load on the operator, it is preferable to connect the detecting means 5 and the water content adjusting means 4 so that they can be automatically controlled.

The detecting means 5 is not particularly limited as long as it can detect the water content or the solute concentration in the cathode solution. For example, as shown in FIG. 6, a detection unit 51 is provided on the pipe L4 so that the detection unit 51 and the water content adjusting means 4 (for example, an air supply blower B that sends gas to the air supply port 41) can be controlled. It is possible to connect. At this time, as a specific example of the detection unit 51, it is possible to use various analyzers / measuring devices for detecting the water content or the solute concentration of the cathode solution. For example, when an aqueous potassium ferricyanide solution is used as the electron acceptor, the detection unit 51 for detecting the solute concentration of the cathode solution may include an absorbance measuring device, an electric conductivity measuring device, or the like.

Other examples of the detecting means 5 include those that detect the power generation efficiency (output) due to the electrode reaction in the reaction unit 3 and those that detect the water level fluctuation of the reservoir 40 in the water content adjusting means 4. As a result, it can be determined that the cathode solution contains excess water due to the decrease in power generation efficiency (output) in the reaction unit 3 and the increase in the water level in the reservoir 40. Based on this determination, the water content adjusting means By operating 4, it becomes possible to appropriately adjust the amount of water in the cathode solution.

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

As described above, in the water treatment method using the water treatment device 1B and the water treatment device 1B in the present embodiment, the water content in the cathode solution is provided by providing a detecting means for detecting the water content or the solute concentration in the cathode solution. It becomes possible to judge whether or not the amount is appropriate. Further, based on this determination, by operating the water content adjusting means, it is possible to appropriately adjust the water content in the cathode solution and more effectively suppress the decrease in the electrode reaction efficiency.

In the water treatment apparatus of the present invention, the aspect of the treatment tank 2 and the positional relationship between the treatment tank 2 and the reaction unit 3 are limited to the water treatment apparatus 1A and 1B shown in the first and second embodiments. is not.
Hereinafter, another embodiment of the treatment tank 2 and the reaction unit 3 in the water treatment apparatus of the present invention will be illustrated.

[Third Embodiment]
FIG. 7 is a schematic explanatory view showing a water treatment apparatus according to a third embodiment of the present invention. Further, FIG. 8 is a schematic explanatory view showing another aspect of the water treatment device according to the third embodiment of the present invention.
In the water treatment apparatus 1C according to the third embodiment, the treatment tank 2 includes an acid generation tank 21 and a methane fermentation tank 22. Further, the reaction 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 water treatment apparatus 1C shown in FIGS. 7 and 8 shows different installation locations of the reaction unit 3. The water content adjusting means 4 may be any of the water content adjusting means 4 shown in the first embodiment, and is not particularly limited. Further, the description of the same configuration as that of the first embodiment will be omitted.

In the water treatment apparatus 1C in the present embodiment, as shown in FIGS. 7 and 8, the treatment tank 2 includes an acid generation tank 21 and a methane fermentation tank 22 connected by a connection pipe L6. Further, FIG. 7 shows a circulation flow path formed by the circulation pipe L7 between the acid generation tank 21 and the methane fermentation tank 22. On the other hand, FIG. 8 shows a circulation flow path formed in the methane fermentation tank 22 by the circulation pipe L8.
In the water treatment device 1C shown in FIG. 7, the reaction unit 3 is provided on the circulation pipe L7. On the other hand, in the water treatment apparatus 1C shown in FIG. 8, the reaction unit 3 is provided on the circulation pipe L8.

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 contained 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-producing tank 21 is a solid or high-molecular-weight 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 L6.

The acid generation tank 21 is provided with an internal water temperature adjusting means, a pH adjusting agent charging means, and a means for adding metals such as nitrogen, phosphorus, cobalt and nickel which are nutrient sources required by the fungus. May be good (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 L6. be. The methane fermentation treatment is performed in an anaerobic atmosphere without dissolved oxygen by methanogens 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.

In the methane fermenter 22, a granule layer in which anaerobic bacteria suitable for anaerobic treatment are present is formed. Then, when the water W to be treated 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 fermenter 22, gas containing methane and carbon dioxide as main components is generated, and treated water W1 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 to the outside of the tank (not shown). Further, the treated water W3 generated in the methane fermentation tank 22 is discharged to the outside of the treatment system via the discharge pipe L9.

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 the fungus (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 reaction unit 3, methane gas, which is a useful energy source, can be recovered from the water to be treated W and effectively used. When power is generated by gas combustion as the utilization of methane gas, the heat discharged from the combustion device used for this gas combustion may be used for the heating means 4b of the water content adjusting means 4. This makes it possible to suppress a decrease in the electrode reaction efficiency of the reaction unit 3 by using the waste generated by the water treatment.

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 reaction unit 3. A means capable of introducing carbon dioxide gas into 31b may be provided. This makes it possible to effectively utilize carbon dioxide gas as an electron acceptor and reduce the supply cost of the electron acceptor. Further, the above-mentioned means capable of introducing carbon dioxide may be provided separately from the contact opportunity improving means 4a of the water content adjusting means 4, and is a part of the contact opportunity improving means 4a of the water content adjusting means 4. It may overlap with. As a result, carbon dioxide is stably supplied to the second cell 31b, so that the water content on the cathode side can be easily adjusted.

Further, the methane fermentation tank 22 in the present embodiment includes a circulation pipe L7 and / or a circulation pipe L8. The circulation pipe L7 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 L8 supplies the treated water W 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.

As shown in FIGS. 7 and 8, the reaction unit 3 in the present embodiment illustrates that the reaction unit 3 is provided on the circulation flow path formed by the circulation pipe L7 and the circulation pipe L8.
Hereinafter, the circulation route from the methane fermentation tank 22 to the reaction unit 3 in the water treatment apparatus 1C of the present embodiment will be described.

As shown in FIG. 7, in the case where the reaction unit 3 is provided on the circulation pipe L7, 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 L7. At this time, the treated water W2 after the reaction at the electrode 33a becomes a solution in which the hydrogen ion concentration increases and the pH shows acidity as shown in the formulas 1 and 2. In general, it is known that the pH in the acid generation tank 21 is preferably closer to acid in order to allow the reaction in the acid generation tank 21 to proceed suitably. Therefore, the water W to be treated discharged from the reaction unit 3 to the acid generation tank 21 may be used as a pH adjuster for the reaction in the acid generation tank 21 to proceed 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 L7 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 treated water W2 discharged from the reaction unit 3 into the acid generation tank 21, the inflow amount of the treated water W2 is controlled. The pH of the water to be treated W in the acid generation tank 21 can be controlled, and the inhibition of the reaction in the acid generation tank 21 can be suppressed.

Further, as shown in FIG. 8, in the case where the reaction unit 3 is provided on the circulation pipe L8, 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. The 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 the formulas 1 and 2. It is known that the metabolism of methane bacteria contained in the granule layer in the methane fermenter 22 is inhibited by hydrogen sulfide. Therefore, the treated water W2 supplied from the reaction unit 3 to the lower part of the methane fermentation tank 22 has the effect of being able to circulate in the methane fermentation tank 22 without inhibiting the methane fermentation.

The cathode solution after being used as an electron acceptor in the reaction section 3 in FIGS. 7 and 8 is discharged from the electron acceptor discharge port 34b and sent to the water content adjusting means 4. Then, after the water content in the cathode solution is adjusted by the water content adjusting means 4 described above, the water content is returned to the second cell 31b again. This makes it possible to suppress a decrease in the electrode reaction efficiency in the reaction unit 3.

In the water treatment device 1C of the present embodiment, the treated water W3 discharged through the discharge pipe L9 can be discharged as it is as long as it satisfies the water quality that can be discharged to a river or the like. .. Further, a processing facility may be provided after the discharge pipe L9. As a result, the treatment efficiency for the water to be treated W can be further improved by undergoing the treatment by the treatment equipment, and the water W to be treated can be discharged from the water treatment device 1C to the outside of the system.

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

As described above, in the water treatment method using the water treatment device 1C and the water treatment device 1C in the present embodiment, the treatment tank 2 is composed of the acid generation tank 21 and the methane fermentation tank 22, respectively. Since water treatment can be performed under conditions suitable for acid production treatment and methane fermentation), water treatment efficiency can be further improved.

Further, in the water treatment apparatus 1C in the present embodiment, the installation location of the reaction 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 treated water W1 supplied to the side is supplied to the treatment tank 2 (acid generation tank 21 or methane fermentation tank 22) again. Therefore, the water to be treated W is repeatedly treated, and it is possible to improve the water treatment with respect to the treated water W2 discharged from the reaction unit 3. Further, by reintroducing the treated water W2 discharged from the reaction 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.

[Fourth Embodiment]
FIG. 9 is a schematic explanatory view showing a water treatment apparatus according to a fourth embodiment of the present invention.
As shown in FIG. 9, the water treatment device 1D according to the fourth embodiment treats the treated water W2 discharged from the discharge pipe L3 of the reaction unit 3 in the water treatment device 1A according to the first embodiment. An aeration tank 6 is provided, and the aeration tank 6 and the electron acceptor supply port 34a provided in the second cell 31b of the reaction unit 3 are connected by a connection pipe L10. As the water content adjusting means 4 in the water treatment device 1D in the present embodiment, the above-mentioned water content adjusting means 4 can be appropriately selected. Further, the description of the same configuration as that of the first embodiment will be omitted.

The water treatment device 1D in the present embodiment supplies the treated water W2 in the aeration tank 6 to the reaction unit 3 and uses it as an electron acceptor in the reaction unit 3. The treated water W2 other than that supplied to the reaction unit 3 by the connecting pipe L10 is discharged to the outside of the system as the treated water W3.

The aeration tank 6 aerates the treated water W2 introduced into the tank with a gas containing oxygen (oxygen, air, etc.) by the aeration device 6a, and aerates with aerobic microorganisms or an oxidation reaction with dissolved oxygen. Is to advance.
In the aeration tank 6 in the present embodiment, as shown in FIG. 9, the treated water W2 discharged from the first cell 31a of the reaction unit 3 is introduced, and the introduced treated water W2 is aerated. Not limited. As another example of the aeration tank 6, for example, the one in which the treated water W1 is directly introduced from the treatment tank 2 to perform aeration can be mentioned.

The aeration device 6a is not particularly limited as long as it can supply a gas containing oxygen to the treated water W2 in the aeration tank 6. For example, those widely used in aeration treatment include those consisting of a combination of a blower and an aeration tube.

Since a gas containing oxygen is introduced into the aeration tank 6 by the aeration device 6a, the treated water W2 in the aeration tank 6 is a liquid containing dissolved oxygen. Therefore, the treated water W2 introduced into the second cell 31b of the reaction unit 3 via the connection pipe L10 becomes an electron acceptor in the reaction unit 3. As a result, it is possible to carry out an electrode reaction that effectively utilizes what is generated in the treatment step in the water treatment device 1D.

Further, the cathode solution after being used as an electron acceptor in the reaction unit 3 is discharged from the electron acceptor discharge port 34b and sent to the water content adjusting means 4. Then, after the water content in the cathode solution is adjusted by the water content adjusting means 4 described above, the water content is returned to the second cell 31b again. This makes it possible to suppress a decrease in the electrode reaction efficiency in the reaction unit 3.

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

As described above, in the water treatment method using the water treatment device 1D and the water treatment device 1D in the present embodiment, the one generated in the treatment step progressing in the water treatment device 1D is combined with the electron donor in the reaction unit 3 and the water treatment method. It can be used as an electron acceptor, and the running cost related to the electrode reaction can be reduced.

The above-described embodiment shows an example of a water treatment apparatus and a water treatment method. The water treatment apparatus and water treatment method according to the present invention are not limited to the above-described embodiments, and the water treatment apparatus and water treatment method according to the above-described embodiments can be used without changing the gist described in the claims. It may be deformed.

For example, the water treatment apparatus in this embodiment may include a plurality of reaction units 3. For example, in the third embodiment, both the reaction sections shown in FIGS. 7 and 8 may be provided. As a result, it is possible to carry out an electrode reaction at a plurality of locations by effectively utilizing the treatment process of the water to be treated W in the water treatment device, and it is possible to improve both the water treatment efficiency and the electrode reaction efficiency. Become.

Further, for example, the water content adjusting means 4 of the water treatment apparatus in the present embodiment may include not only a means for reducing the water content in the cathode solution but also a means for adding water to the cathode solution. .. As a result, when the amount of the cathode solution in the reaction unit 3 is insufficient, the amount of the cathode solution can be appropriately maintained, and the decrease in the electrode reaction efficiency can be suppressed.

Further, for example, the electrode 33a and the electrode 33b of the water treatment apparatus according to the present embodiment are arranged in the housing with the surfaces of the electrode 33a and the electrode 33b exposed, and the reaction unit is a reaction unit that can be taken out from the reaction unit 3. It may be provided in 3. This facilitates maintenance work because it is easy to take out the electrode 33a and the electrode 33b from the reaction unit 3 at the time of maintenance.

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

Further, for example, in the water treatment apparatus of the present embodiment, the electrode 33b may be provided in the aeration tank 6, and the aeration tank 6 may function as the second cell 31b of the reaction unit 3. As a result, the reaction unit 3 and the aeration tank 6 are integrated, and the equipment can be further miniaturized.

Further, for example, the water treatment apparatus in this embodiment may be provided with an insulating mechanism. The insulating 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 reaction unit 3.
Examples of the insulating means by the insulating mechanism include elimination of electrical contact (liquid entanglement) between the electrode 33a of the reaction unit 3 and the treated water W2, or shortening of the liquid entanglement time. Examples of such liquid entanglement eliminating means or means for shortening the liquid entanglement time include means for discontinuously (intermittently) flowing the treated water W2, means for interposing an insulator such as air in the treated water W2, and the like. Alternatively, a combination of these means may be mentioned. This prevents the electrons generated in the reaction unit 3 from flowing except between the electrodes 33a and 33b, and improves the electrode reaction efficiency.
The water treatment device in the present embodiment may also be insulated from the structures (treatment tanks and pipes) constituting the water treatment device as shown in the first embodiment. As a result, a further insulating effect can be obtained, and the electrode reaction efficiency in the reaction unit 3 can be improved.

Further, for example, the water 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 35. This makes it possible to simplify the reaction unit 3 and facilitate maintenance work.
Further, as another example of the structure that can be omitted, the electron acceptor supply port 34a and the electron acceptor discharge port 34b in the second cell 31b can be mentioned. This makes it possible to further simplify the reaction unit 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. 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. This makes it possible to prevent solid impurities such as dust from adhering to the surface of the electrode 33b.

The water treatment apparatus and water treatment method of the present invention are used for water treatment for treating water to be treated. In particular, it is suitably used in water treatment in which a reducing substance is generated by treating water to be treated.

1A, 1B, 1C, 1D water treatment equipment, 2 treatment tanks, 21 acid generation tanks, 22 methane fermentation tanks, 23 settler, 3 reaction parts, 31a first cell, 31b second cell, 32a treated water inlet, 32b treated water discharge port, 33a, 33b electrode, 34a electron receptor supply port, 34b electron receptor discharge port, 35 ion exchanger, 4 water content adjusting means, 4a contact opportunity improving means, 4b heating means, 4c membrane separation Means, 40 Reservoir, 41 Air supply port, 42 Piping, 43 Volatilizer, 44 Heating part, 45 Semi-transparent film, 46 Membrane separation part 46a, 46b Space, 5 Detection means, 51 Detection part, 6 Air exposure tank, 6a Exposure Equipment, B blower, L1 introduction pipe, L2, L6, L10 connection pipe, L3, L9 discharge pipe, L4, L5 pipe, L7, L8 circulation pipe, W treated water, W1, W2, W3 treated water

Claims (8)

A water treatment device that performs anaerobic treatment on the water to be treated.
A reaction part that performs an electrode reaction using the reducing substance in the water to be treated as an electron donor, and
A water treatment apparatus comprising: a water content adjusting means for adjusting the water content on the cathode side of the reaction unit. The water treatment apparatus according to claim 1, wherein the water content adjusting means includes a contact opportunity improving means for increasing the contact opportunity between the cathode solution and the gas. The water treatment apparatus according to claim 2, wherein the contact opportunity improving means is aeration. The contact opportunity improving means includes a volatilizer that sucks up the cathode solution.
The water treatment apparatus according to claim 2, wherein the volatilizer spontaneously evaporates the water content in the sucked-up cathode solution. The water treatment apparatus according to claim 1, wherein the water content adjusting means includes a heating means. The water treatment apparatus according to claim 1, wherein the water content adjusting means includes a membrane separating means using a membrane. The water treatment apparatus according to any one of claims 1 to 6, further comprising a detecting means for detecting a water content or a solute concentration in the cathode solution in the reaction unit. It is a water treatment method that performs anaerobic treatment on the water to be treated.
The reaction step of performing an electrode reaction using the reducing substance in the water to be treated as an electron donor, and
A water treatment method comprising: a water content adjusting step of adjusting the water content on the cathode side of the reaction step.

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