JP2022104443A - Processing apparatus and processing method - Google Patents

Abstract

To provide a processing apparatus and a processing method capable of recovering and utilizing energy by electrode reaction and desulfurization treatment in anaerobic treatment of treated materials, and stably performing a highly efficient electrode reaction at a low cost.SOLUTION: A processing apparatus 1A includes a treatment tank 2, a reaction section 3, and a seawater supply means 4, and has an introduction piping L1 that introduces treated water W into the treatment tank 2, a connection piping L2 that connects the treatment tank 2 and the reaction part 3 and supplies treated water W1 after treated water W is treated in the treatment tank 2 to the reaction part 3, and a discharge piping L3 that discharges treated water W2 after electrode reaction from the reaction part 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a processing apparatus and a processing method for anaerobic treatment of an object to be treated.

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

For example, Patent Document 1 describes, as a treatment of water to be treated containing an organic substance, a treatment of immersing a pair of electrodes in the water to be treated, performing an electrochemical treatment, and then biologically treating the water to be treated. ..

Japanese Unexamined Patent Publication No. 2004-330182

As described in Patent Document 1, in the treatment in which the electrochemical treatment and the biological treatment are combined, it is possible to proceed the reaction with good reaction efficiency for each treatment and improve the treatment efficiency of the whole treatment. It becomes. 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 treatment described in Patent Document 1, it is possible to reduce the running cost as compared with the electrochemical treatment alone. However, in the treatment described in Patent Document 1, it is necessary to supply energy related to electrochemical treatment and biological treatment from outside the treatment system. Therefore, further energy saving at the time of processing is required.

In recent years, in order to suppress equipment drive power during processing and to improve energy saving, a technique capable of recovering and utilizing energy in the processing process has been studied.
As one of such technologies, energy recovery using biogas generated by biological treatment is performed, and the heat energy obtained by biogas storage / purification equipment and biogas combustion 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, there is a demand for a technique for recovering and utilizing energy more easily and efficiently in processing.

As a technique for recovering energy easily and efficiently in the treatment, it is conceivable to provide an electrode on the treatment step and recover the electric energy directly by the electrode reaction. At this time, by using a reducing substance contained in the aqueous solution (treated water or treated water) in the treatment step as an electron donor to be subjected to the electrode reaction, the energy to be recovered by the electrode reaction and the treated water or the treated water are simultaneously recovered. It is possible to perform electrochemical treatment on the surface, and it is expected that the treatment efficiency will be improved and energy saving will be realized. The present inventors have already found that, in particular, by using hydrogen sulfide generated by anaerobic treatment as an electron donor, desulfurization treatment of treated water is also possible.

Further, when the present inventors recover energy by an electrode reaction using a reducing substance contained in the aqueous solution in the treatment step, the salt concentration contained in the aqueous solution in the treatment step is not constant and the electrode is sufficient. We have found that it is difficult to obtain stable reaction efficiency.
Generally, as a means for increasing the salt concentration, an electrolyte may be added as an additive, but the increase in running cost due to the use of the additive becomes a problem.

An object of the present invention is a processing apparatus capable of recovering and utilizing energy by an electrode reaction and desulfurization treatment in an anaerobic treatment of an object to be treated, and capable of stably performing a highly efficient electrode reaction at low cost. It is to provide a processing method.

As a result of diligent studies on the above problems, the present inventor conducts an electrode reaction using the reducing substance contained in the treated water after anaerobic treatment of the object to be treated as an electron donor, thereby efficiently recovering energy. We have found that it is possible to use and desulfurize the treated water, and to provide a means to supply seawater to the reaction part where the electrode reaction is performed, so that the electrode reaction can be stably and highly efficient. , The present invention has been completed.
That is, the present invention is the following processing apparatus and processing method.

The processing apparatus of the present invention for solving the above-mentioned problems is a processing apparatus that performs anaerobic treatment on an object to be treated, and causes the treated water after the object to be treated to be anaerobically treated to come into contact with an electrode to generate electricity and / or. It is characterized by having a reaction section for removing sulfur components in the treated water and a seawater supply means for supplying seawater to the reaction section.
In the processing apparatus of the present invention, by installing a reaction unit using electrodes in the processing apparatus, it becomes possible to carry out power generation in a series of processing processes in anaerobic 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 of the treated water. Furthermore, by providing a means for supplying seawater to the reaction section where the electrode reaction is performed, the seawater can be used as an electrolyte during the electrode reaction, and the electrode reaction can be made highly efficient at low cost, and power generation and desulfurization can be achieved. It is possible to improve the processing efficiency.

Further, as one embodiment of the treatment apparatus of the present invention, the seawater supply means is characterized by having an adjusting function for adjusting the supply amount of seawater.
According to this feature, the electrolyte concentration in the reaction section can be changed by adjusting the supply amount of seawater, and the electrode reaction efficiency can be easily controlled. In addition, even if the content of reducing substances in the treated water fluctuates significantly, by adjusting the supply amount of seawater, the electrolyte concentration in the reaction part can be kept constant, and the efficiency of the electrode is improved. The reaction can be stably continued.

Further, as one embodiment of the processing apparatus of the present invention, the reaction unit is characterized by having a backflow prevention function to the upstream side.
Generally, in an electrode reaction, the salt concentration in the solution used for the electrode reaction greatly affects the improvement of the electrode reaction efficiency, while in a biological treatment such as anaerobic treatment, the activity of microorganisms decreases in an environment with a high salt concentration. However, it is also known that the processing efficiency is reduced.
Therefore, by providing a function of preventing backflow to the upstream side of the reaction section, it is possible to prevent the seawater added to the reaction section from affecting the anaerobic treatment.

Further, the treatment method of the present invention for solving the above-mentioned problems is a treatment method for performing anaerobic treatment on the object to be treated, in which the treated water after the object to be treated is anaerobically treated and the electrode is brought into contact with each other to generate electricity. It is characterized by including a reaction step of performing an electrode reaction for removing sulfur components in the treated water and / or a seawater supply step of supplying seawater to the reaction step.
In the 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. Furthermore, by providing a step of supplying seawater to the reaction section where the electrode reaction is performed, the seawater can be used as an electrolyte during the electrode reaction, and the electrode reaction can be made highly efficient at low cost, and power generation and desulfurization can be achieved. It is possible to improve the processing efficiency.

According to the present invention, in the anaerobic treatment of an object to be treated, a treatment apparatus capable of recovering and utilizing energy by an electrode reaction and desulfurization treatment, and capable of stably performing a highly efficient electrode reaction at low cost. A processing method can be provided.

It is a schematic explanatory drawing of the processing apparatus in 1st Embodiment of this invention. It is a schematic explanatory drawing which shows the other aspect of the processing apparatus in 1st Embodiment of this invention. It is a schematic explanatory drawing of the processing apparatus in the 2nd Embodiment of this invention. It is a schematic explanatory drawing of the processing apparatus in 3rd Embodiment of this invention. It is a schematic explanatory drawing of the processing apparatus in 4th Embodiment of this invention.

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

In the processing apparatus of the present invention, the object to be treated is not particularly limited as long as it contains a reducing substance that reacts with the electrode in the treated water after the anaerobic treatment, and may be either a solid or a liquid. May be good. The reducing substance may be contained in the object to be treated before being introduced into the treatment apparatus, or may be generated as the treatment progresses in the treatment apparatus and may be present in the treated water. good.
Specific examples of the object to be treated include industrial wastewater discharged from various factories such as food factories, chemical factories, and paper and pulp factories, and wastewater (wastewater) such as domestic wastewater such as sewage. .. In addition, as another example of the object to be treated, for example, in addition to biomass such as food waste, food waste and wood discharged from homes and various factories, domestic wastewater such as industrial wastewater and sewage discharged from various factories are treated. Examples include solid waste such as excess sludge after sewage. Here, when the object to be treated is a solid, the treated water after the anaerobic treatment refers to a filtrate from which the solid component has been removed.
In the following embodiments, wastewater (hereinafter referred to as “water to be treated”) in which a reducing substance is present in the treated water after undergoing anaerobic treatment will be mainly described as the object to be treated. Not limited to.

Further, in the present invention, the reducing substance contained in the treated water 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]
[Processing device]
FIG. 1 is a schematic explanatory view showing the structure of the processing apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, the treatment apparatus 1A in the present embodiment includes a treatment tank 2, a reaction unit 3, and a seawater supply means 4. In this embodiment, the case where the object to be treated is wastewater (hereinafter referred to as “water to be treated W”) in which a reducing substance is present in the treated water after undergoing anaerobic treatment. explain.
Further, as shown in FIG. 1, the treatment apparatus 1A in the present embodiment 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 is covered by the treatment tank 2. It is provided with a connection pipe L2 for supplying the treated water W1 after the treated water W has been treated 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 performing anaerobic treatment on 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, methane fermentation that produces methane is particularly preferable from the viewpoint of processing cost and usefulness of the produced gas. The treatment tank 2 may be a single tank or may be composed of a plurality of tanks. For example, when the treatment performed in the treatment tank 2 is methane fermentation, a combination of a plurality of tanks such as an acid generation tank and a methane fermentation tank may be used as the treatment tank 2.

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 this 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 into a river, the ocean, 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 rivers and the ocean. 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. The liquid may be a solution in which a solid drug is dissolved or a solution in which a gas is mixed (dissolved).

Specific examples of the electron acceptor in the present embodiment include, for example, oxygen and a gas containing oxygen as a gas. Examples of the gas containing oxygen include those containing oxygen as a mixture such as air and those containing oxygen as an element constituting a compound such as carbon dioxide. When a gas is used as an electron acceptor, there are advantages that the treatment of the discharged substance after the reaction is unnecessary (or easy) and the cost for obtaining the gas can be reduced. In order to take full advantage of these advantages, it is particularly preferable to use air as the electron acceptor.
Further, as another example of the electron acceptor in this embodiment, for example, as a liquid, a solution containing dissolved oxygen, an aqueous solution of an oxidizing agent such as an aqueous solution of potassium ferricyanide, and the like can be mentioned. When a liquid is used as the electron acceptor, the compound (oxidizing agent) having a high effect as the electron acceptor can be easily handled, so that there is an advantage that the 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 receptor supply port 34a and the electron receptor 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 another example of the second cell 31b, a gas is supplied to the second cell 31b via the pipe L5 in order to supply a gaseous electron acceptor (oxygen, air, etc.) to the electrode 33b. It is possible to provide an electron acceptor supply port 34a for discharging the gas after the reaction and an electron acceptor discharge port 34b for discharging the gas after the reaction through the pipe L4.
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 and the pipe L4.
The electron acceptor supply port 34a and / or the electron acceptor discharge port 34b may be provided with a flow rate adjusting mechanism such as a valve so that the concentration of the electron acceptor in the second cell 31b can be adjusted. Further, a control mechanism for controlling the flow rate adjusting mechanism may be provided so that the electron acceptor concentration corresponding to the amount of electrons generated by the reaction at the electrode 33a is maintained. 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.

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. 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 a plurality of electron acceptor discharge ports 34b are provided, for example, a gas discharge port and a liquid discharge port may be provided separately.

The ion exchanger 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 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.) 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 may 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.

When the electron acceptor supplied into the second cell 31b is a gas (air), one surface of the electrode 33b is in contact with the gas, but the other surface is in contact with the treated water W1. Therefore, it is preferable that the electrode 33b has a form suitable as a so-called air cathode. Suitable forms for an air cathode include, for example, having both gas permeable and impermeable properties. By forming the electrode 33b so as to have gas permeability, it is possible to effectively react the gas, which is an electron acceptor, with the electrode 33b. Further, since the electrode 33b is impermeable to water, it is possible to prevent the treated water W1 in the first cell 31a from penetrating the electrode 33b and flowing into the second cell 31b. Specific examples of such an electrode 33b include those made of carbon fiber, those coated with a material having gas permeability and impermeableness on the surface of a metal mesh, and those subjected to surface treatment such as laminating a film. Can be mentioned. The term "water impermeable" as used herein means that water does not pass through, and for example, the electrode 33b is provided with impermeable property even when it is made waterproof, water repellent, hydrophobic, or watertight. It is included.

Hereinafter, the reaction and the process related to the electrode reaction in the processing apparatus of 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 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 oxygen and an oxidizing agent is used as an electron acceptor. It is intended to explain what is used as.
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 processing apparatus 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 power generation and desulfurization treatment in the treatment apparatus 1A of the present embodiment are performed.
Further, the electric energy obtained by power generation can be recovered and used through an external circuit connected to the electrode 33a and the electrode 33b. The use of electric energy is not particularly limited. For example, it may be used for driving the equipment of the processing device, or may be used outside the processing device.

In the electrode reaction in the processing apparatus of the present embodiment, the ease of current flow changes according to the salt concentration (electrolyte concentration), which affects the electrode reaction efficiency. However, since the concentrations of reducing substances and salts in the treated water W1 are not always constant, it is difficult to stably improve the efficiency of the electrode reaction. On the other hand, when an electrolyte such as sodium chloride is added to the reaction unit 3 as an additive, the cost of the additive becomes a problem. Therefore, as a means for increasing the salt concentration in the reaction unit 3, we focused on seawater, which is inexpensive and can be obtained in large quantities and also functions as an electrolyte. Therefore, the processing apparatus 1A in the present embodiment is provided with means for supplying seawater to the reaction unit 3.

(Seawater supply means)
The seawater supply means 4 may be any as long as it can supply seawater to the reaction unit 3, and the specific structure is not particularly limited.
The source of seawater supplied by the seawater supply means 4 (hereinafter referred to as “seawater source”) is not particularly limited. For example, the natural environment (ocean) may be used as the seawater source, and seawater may be introduced directly from the ocean to the seawater supply means 4, such as seawater used for ocean storage treatment of carbon dioxide or ballast water for ships. Seawater temporarily stored artificially, such as seawater used in the above-mentioned purpose or seawater stored in a storage tank, may be used as an ocean source.
The cost of procuring raw materials for seawater is mainly the cost of transporting seawater. For example, by installing the treatment device 1A of the present invention on land near the sea or on the sea, it is possible to use seawater at the minimum transportation cost.

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

As shown in FIG. 1, the seawater supply means 4 includes a pipe 40 connected to the first cell 31a in the reaction unit 3 and a storage tank 41 for storing seawater. Then, the seawater in the storage tank 41 is introduced into the first cell 31a via the pipe 40, and the seawater and the treated water W1 are mixed.
Since the pipe 40 and the storage tank 41 are used for supplying and storing seawater, it is preferably made of a material having corrosion resistance. As a result, deterioration due to seawater can be suppressed and the life of the device can be extended.

Seawater contains various ionic species. For example, monovalent metal ions such as Na ⁺ and K ⁺ , divalent metal ions such as Ca ²⁺ and Mg ²⁺ , as well as ^anions such as Cl ⁻ and SO _4-2 are included. These ionic species function as an electrolyte in the first cell 31a, and increase the electrode reaction efficiency in the electrodes 33a and 33b.

Here, when the treated water W1 obtained by anaerobic treatment of the water to be treated W is compared with the seawater, the concentration of the electrolyte contained in the seawater is considerably higher. Therefore, even if the salt concentration in the treated water W1 fluctuates, the concentration of the electrolyte contained in the seawater is higher, so that the electrode reaction in the reaction unit 3 becomes more efficient according to the concentration of the electrolyte contained in the seawater. Further, since it can be considered that the fluctuation of the electrolyte concentration in the first cell 31a does not occur substantially, it is possible to stably continue the highly efficient electrode reaction.

FIG. 2 is a schematic explanatory view showing another aspect of the processing apparatus 1A in the present embodiment.
As shown in FIG. 2, a storage tank T for storing the solution (mixed solution of treated water W1 and seawater) in the pipe L6, the pipe L7, and the reaction unit 3 is provided in the reaction unit 3 to form a circulation flow path. It may be a thing. As a result, the mixing of the seawater supplied by the seawater supply means 4 and the treated water W1 is promoted, and the electrode reaction efficiency in the reaction unit 3 can be improved.

As described above, the 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. be. 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 processing apparatus 1A in the present embodiment performs an insulating treatment other than 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 treatment method using the treatment device 1A and the treatment device 1A of the present embodiment makes it possible to carry out the electrode reaction in a series of treatment processes in the anaerobic treatment of the object to be treated. 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. Furthermore, by providing a means for supplying seawater to the reaction section where the electrode reaction is performed, the seawater can be used as an electrolyte during the electrode reaction, and the electrode reaction can be made highly efficient at low cost, and power generation and desulfurization can be achieved. It is possible to improve the processing efficiency.

[Second Embodiment]
FIG. 3 is a schematic explanatory view showing a processing apparatus according to the second embodiment of the present invention.
The treatment device 1B according to the second embodiment is provided with a supply amount adjusting function 42 for adjusting the supply amount of seawater with respect to the seawater supply means 4 in the treatment device 1A in the first embodiment. The description of the same configuration as that of the first embodiment will be omitted.

In the treatment apparatus 1B of the present embodiment, the seawater supply means 4 is provided with a supply amount adjusting function 42, and the electrolyte concentration in the reaction unit 3 can be changed by adjusting the supply amount of seawater. This makes it possible to easily control the electrode reaction efficiency in the reaction unit 3.
Further, even when the content of the reducing substance in the treated water W1 fluctuates significantly, the electrolyte concentration in the reaction unit 3 can be kept constant by adjusting the supply amount of seawater. This makes it possible to stably continue the highly efficient electrode reaction.

The supply amount adjusting function 42 may be provided on the pipe 40 and can adjust the amount of seawater supplied from the pipe 40 to the reaction unit 3, and examples thereof include a flow rate adjusting valve and a valve.

Further, the operation of the supply amount adjusting function 42 may be manually performed by the operator, or may be automatically controlled based on a program or the like. In view of improving work efficiency and the like, it is preferable that the supply amount adjusting function 42 in this embodiment is provided with a control unit 43 as shown in FIG. The one-dot dashed arrow in FIG. 3 indicates that they are connected so as to be controllable.
The control unit 43 in the present embodiment controls the opening / closing operation of the supply amount adjusting function 42. Further, the control unit 43 calculates the supply amount and supply timing of seawater based on the data acquisition unit that acquires data related to the reaction efficiency (output) of the electrode reaction in the reaction unit 3 and the data acquired by the data acquisition unit. It is more preferable to have a calculation unit. This makes it possible to control the supply amount adjusting function 42 with higher accuracy and at a suitable timing.
Examples of the type of data acquired by the data acquisition unit include the potential difference between the electrodes 33a and 33b, the amount of current, and the conductivity of the solution in the first cell 31a.

As described above, in the treatment method using the treatment device 1B and the treatment device 1B in the present embodiment, the electrolyte concentration in the reaction section can be changed or made constant by adjusting the supply amount of seawater supplied to the reaction section. It will be possible to keep. As a result, the electrode reaction efficiency can be easily controlled, and the highly efficient electrode reaction can be stably continued.

[Third Embodiment]
FIG. 4 is a schematic explanatory view showing a processing apparatus according to a third embodiment of the present invention.
The processing device 1C according to the third embodiment has a feature that the reaction unit 3 of the processing device 1A in the first embodiment is provided with a backflow prevention function 5 to the upstream side. The description of the same configuration as that of the first embodiment will be omitted.

Generally, in the electrode reaction, the salt concentration in the solution (treated water W1 or the like) used for the electrode reaction has a great influence on the improvement of the electrode reaction efficiency, while in the biological treatment such as anaerobic treatment, the salt concentration is high. It is also known that underneath, the activity of microorganisms decreases and the treatment efficiency decreases.

The treatment apparatus 1C in the present embodiment includes a treatment tank 2 for performing anaerobic treatment on the water to be treated W on the upstream side of the reaction unit 3, and the treated water W1 after being treated in the treatment tank 2 is provided. It becomes a solution to be subjected to the electrode reaction in the reaction unit 3. Therefore, by providing the reaction unit 3 with a function of preventing backflow to the upstream side, it is possible to prevent the seawater supplied to the reaction unit 3 from affecting the anaerobic treatment in the treatment tank 2. Become.

The backflow prevention function 5 may have a function of suppressing the inflow of the solution in the reaction unit 3 to the upstream side (treatment tank 2 side). For example, the treatment tank 2 and the reaction unit 3 may be used. A check valve may be provided on the connection pipe L2 to connect the above.

As described above, the treatment method using the treatment apparatus 1C and the treatment apparatus 1C in the present embodiment is provided with a function of preventing backflow to the upstream side of the reaction portion, so that the seawater added to the reaction portion is anaerobically treated. It is possible to suppress the inflow to the treatment tank side and not to affect the anaerobic treatment.

The treatment apparatus of the present invention is not limited to the one that anaerobically treats a liquid component such as water W to be treated in the treatment tank 2. Further, the treated water supplied to the reaction unit 3 is not limited to the one directly discharged from the treatment tank 2.
Hereinafter, as another embodiment of the processing apparatus of the present invention, an object to be treated composed of a solid component such as biomass will be exemplified.

[Fourth Embodiment]
FIG. 5 is a schematic explanatory view showing a processing apparatus according to a fourth embodiment of the present invention.
As shown in FIG. 5, the treatment apparatus 1D according to the fourth embodiment includes a solid-liquid separation unit 6 between the treatment tank 2 and the reaction unit 3, and further includes a seawater supply means 4.
Further, the treatment device 1D includes an introduction pipe L20 for introducing the object S to be processed into the treatment tank 2, a connection pipe L21 for connecting the treatment tank 2 and the solid-liquid separation unit 6, and the treated water W4 separated by the solid-liquid separation unit 6. Is provided with an introduction pipe L22 for introducing the water into the reaction unit 3, a discharge pipe L23 for discharging the solid matter separated by the solid-liquid separation unit 6 to the outside of the system, and a discharge pipe L24 for discharging the treated water W2 from the reaction unit 3 to the outside of the system. ing.

In the treatment apparatus 1D shown in FIG. 5, the object S to be treated is anaerobically treated by the treatment tank 2, and the discharged material (treatment liquid W3) after the anaerobic treatment is performed in the solid-liquid separation unit 6 is treated with the treated water W4 (treatment liquid W3). The filtrate) and the solid substance are separated, and the treated water W4 is introduced into the reaction unit 3. As a result, more efficient energy recovery / utilization or desulfurization treatment can be performed by utilizing the waste discharged after the anaerobic treatment of the object S to be treated.
Hereinafter, the configuration of the processing device 1F will be described.

(Processing tank)
The treatment tank 2 in the present embodiment performs anaerobic treatment on solid components such as biomass.
As the anaerobic treatment performed in the treatment tank 2 in the present embodiment, methane fermentation that produces methane is particularly preferable from the viewpoint of treatment cost and usefulness of the produced gas. Therefore, it is preferable that the treatment tank 2 has a structure that functions as a digestion facility for digesting the object S to be treated. More specifically, the treatment tank 2 preferably has a structure known as a digestion tank, and the specific structure related to the digestion tank is not particularly limited.

Of the anaerobic treatments in the treatment tank 2, especially when methane fermentation is performed, hydrogen sulfide, hydrogen, ammonia and the like are generated in the discharge (treatment liquid W3) after the treatment of the object S to be treated, in addition to methane. do. In addition, these products correspond to the reducing substance in this invention.

The object S to be treated in the treatment tank 2 becomes a discharge material (treatment liquid W3) containing a reducing substance, and is introduced into the solid-liquid separation unit 6 via the connection pipe L2.

(Solid liquid separation part)
The solid-liquid separation unit 6 is for separating the treatment liquid W3 introduced from the treatment tank 2 into the solid matter and the treatment water W4.
Here, the treatment liquid W3 separated by the solid-liquid separation unit 6 is a discharge after being anaerobically treated in the treatment tank 2, and is a solid-liquid mixture (sludge) containing a mud-like substance such as excess sludge. .. Further, the treatment liquid W3 contains a reducing substance produced by methane fermentation.
Therefore, the treatment liquid W3 is solid-liquid separated by the solid-liquid separation unit 6, the treated water W4 containing the reducing substance is recovered and introduced into the reaction unit 3 in the subsequent stage, whereby the reducing substance is used as an electron donor. The reaction can proceed.

The solid-liquid separation unit 6 is not particularly limited as long as it can separate the solid matter contained in the treatment liquid W3 and the treatment water W4. For example, a settling type such as a coagulation settling tank or a settling tank, a centrifuge type equipped with a centrifuge, or a pressure filtration device such as a belt press dehydrator or a screw press dehydrator. Can be mentioned.

The treated water W4 separated by the solid-liquid separation unit 6 is introduced into the reaction unit 3 as treated water containing a reducing substance (corresponding to the treated water W1) via the introduction pipe L22. On the other hand, the solid matter separated by the solid-liquid separation unit 6 is discharged to the outside of the system via the discharge pipe L23. At this time, a processing facility for processing solid matter may be provided after the discharge pipe L23.

Then, in the reaction unit 3 into which the treated water W4 is introduced, as in the case of using the treated water W1 described above, the reducing substance in the treated water W4 is used as an electron donor to generate power, and the treated water W4 contains the reducing substance. By using a sulfur-containing compound such as hydrogen sulfide as an electron donor among the reducing substances, it is possible to perform desulfurization treatment.

As described above, by the treatment method using the treatment device 1D and the treatment device 1D of the present embodiment, the discharge after the anaerobic treatment of the object to be treated is utilized, and the anaerobic treatment of the object to be treated composed of solid components is also performed. Efficient energy recovery and utilization by power generation and desulfurization can be performed. In particular, by enabling an electrode reaction using a reducing substance contained in a filtrate obtained by solid-liquid separation of the anaerobic discharge, it is possible to inhibit mass transfer by microorganisms used in anaerobic treatment and to improve the metabolic rate of microorganisms. There is no rate-determining step based on this, and it is possible to improve power generation efficiency and desulfurization treatment efficiency. In addition, the equipment can be downsized as compared with the power generation by the microbial fuel cell. Further, it is possible to carry out an efficient desulfurization treatment without separately providing equipment for the desulfurization treatment.

The above-described embodiment shows an example of a processing apparatus and a processing method. The processing apparatus and processing method according to the present invention are not limited to the above-described embodiment, and even if the processing apparatus and processing method according to the above-described embodiment are modified without changing the gist described in the claims. good.

For example, the processing 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 means for interposing an insulator such as air in the treated water W2. 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.
In addition, the processing apparatus in this embodiment may also perform insulation related to the structure (processing tank or piping) constituting the processing apparatus 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 processing 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 treatment apparatus and treatment method of the present invention are used for treatment of water to be treated. In particular, it is suitably used in a treatment in which a reducing substance is generated by treating water to be treated.

1A, 1B, 1C, 1D treatment device, 2 treatment tank, 3 reaction part, 31a 1st cell, 31b 2nd cell, 32a treated water inlet, 32b treated water discharge port, 33a, 33b electrode, 34a electron receiving Body supply port, 34b electron acceptor discharge port, 35 ion exchanger, 4 seawater supply means, 40 piping, 41 storage tank, 42 supply amount adjustment function, 43 control unit, 5 backflow prevention function, 6 solid-liquid separation unit, L1 , L20 introduction pipe, L2, L21 connection pipe, L3, L23 discharge pipe, L4 to L7 pipe, S object to be treated, T storage tank, W water to be treated, W1 to W4 treated water (treatment liquid)

Claims (4)

A processing device that performs anaerobic treatment on the object to be processed.
A reaction unit that brings the treated water after the anaerobic treatment of the object to be treated into contact with the electrode to generate electricity and / or remove the sulfur component in the treated water.
A treatment apparatus including a seawater supply means for supplying seawater to the reaction unit. The processing apparatus according to claim 1, wherein the seawater supply means includes an adjustment function for adjusting a supply amount of seawater. The processing apparatus according to claim 1 or 2, wherein the reaction unit has a function of preventing backflow to the upstream side. It is a processing method for performing anaerobic treatment on the object to be treated.
A reaction step in which the treated water after the anaerobic treatment of the object to be treated is brought into contact with the electrode to generate electricity and / or perform an electrode reaction to remove the sulfur component in the treated water.
A treatment method comprising a seawater supply step of supplying seawater to the reaction step.

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