JP2005245328A - Closed circulation aquaculture system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a closed circulation culture system capable of removing excess hypochlorous acid without using a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device. The present invention relates to a closed circulation type aquaculture system that circulates while purifying seawater in a breeding aquarium 1 through a circulation path 2. A first electrolytic cell 5 that electrolyzes salt water between the anode 3 and the cathode 4 that are opposed to each other with a diaphragm and generates hypochlorous acid on the anode 3 side is connected to the circulation path 2. A second electrolysis that forms an anode chamber 8 in which an anode 7 is disposed by partitioning with a diaphragm 6 and a cathode chamber 10 in which a cathode 9 is disposed, and generates hydrogen peroxide on the cathode 9 side by electrolyzing salt water. A tank 11 is provided. The salt water in the cathode chamber 10 of the second electrolytic cell 11 is mixed with the seawater that has passed through the first electrolytic cell 5.
[Selection] Figure 1

Description

  The present invention relates to a closed circulation aquaculture system that circulates in a closed system while purifying seawater (including artificial seawater) on land to cultivate seafood in a breeding aquarium or temporarily cultivate it. Is.

  A closed-type aquaculture system for raising food or appreciating seafood at a land point remote from the sea surface has been studied. In this closed-circulation aquaculture system, it is necessary to perform the process of removing the excrement and residual food of the reared fishery products from the rearing aquarium without using dilution in the surrounding environment. For this purpose, a circulation path for circulating seawater is connected to the breeding aquarium, and a physical filtration device and an electrolysis tank are provided in this circulation path, or a physical filtration device, a biological purification tank and an electrolysis tank are provided, During circulation, seafood excrement and residual food in seawater are removed and purified.

In the former system in which a physical filtration device and an electrolytic cell are installed in the circulation path, solids in seawater are removed by filtration with a physical filtration device, and the seawater is electrolyzed in the electrolytic cell. With active chlorine species such as chlorous acid, it is possible to decompose and remove ammonia and the like resulting from seafood excrement, and further disinfect and disinfect seawater. In the latter system, a physical filtration device, a biological septic tank, and an electrolytic cell are provided in the latter circulation path, and solids in seawater are removed by filtration with a physical filtration device. Further, in the biological septic tank, ammonia such as nitrifying bacteria is removed. It is possible to disinfect and disinfect seawater with active chlorine species such as hypochlorous acid produced by electrolyzing seawater in an electrolytic cell. (For example, see Patent Document 1)
JP 2003-27496 A

  However, when electrolyzing seawater in an electrolytic cell to generate hypochlorous acid as described above, excess hypochlorous acid has a fish poisoning action, so that the electrolytic cell is used as disclosed in Patent Document 1. Next, it is necessary to provide a chlorine removing device to remove excess hypochlorous acid.

  And as a chlorine removal apparatus, the activated carbon filling tank, the neutralizing agent addition apparatus which adds chlorine neutralizing agents, such as sodium thiosulfate, etc. are used, but in the case of an activated carbon filling tank, SS ( suspended solid (suspended solids, suspended solids) and insoluble salts generated by electrolysis, the tank tends to be clogged, and frequent cleaning is required. There are problems such as complicated replenishment and maintenance.

  The present invention has been made in view of the above points, and it is not necessary to use a chlorine removal device such as an activated carbon filling tank or a neutralizer addition device, and a closed circulation type that can remove excess hypochlorous acid. The purpose is to provide an aquaculture system.

  A closed-circulation aquaculture system according to claim 1 of the present invention is a closed-circulation aquaculture system in which seawater in a breeding aquarium 1 for rearing fish and shellfish is circulated while purifying it through a circulation path 2, and is opposed to each other with a diaphragm. The first electrolytic cell 5 that electrolyzes salt water between the anode 3 and the cathode 4 to generate hypochlorous acid on the anode 3 side is connected to the circulation path 2 and is partitioned by the diaphragm 6 so that the anode 7 A cathode chamber 10 in which an anode chamber 8 and a cathode 9 are arranged is formed, and a second electrolytic cell 11 that electrolyzes salt water to generate hydrogen peroxide on the cathode 9 side is provided. The salt water in the cathode chamber 10 of the second electrolytic cell 11 is mixed with the seawater that has passed through the electrolytic cell 5.

  According to the present invention, seawater can be sterilized and disinfected with hypochlorous acid generated by electrolyzing seawater in the first electrolytic cell 5, and the seawater electricity in the second electrolytic cell 11. Hydrogen peroxide produced in the cathode chamber 10 by decomposition can decompose excessive hypochlorous acid contained in seawater passing through the first electrolytic cell 5, and can be an activated carbon filling tank or a neutralizing agent. Excess hypochlorous acid can be removed without using a chlorine removing device such as an adding device.

  According to a second aspect of the present invention, in the first aspect, the second electrolyzer 11 is electrically energized for electrolysis in accordance with the amount of electricity energized in the first electrolyzer 5 for electrolysis. It comprises the control part 12 which controls quantity, It is characterized by the above-mentioned.

  According to the present invention, the amount of hydrogen peroxide generated in the cathode chamber 10 of the second electrolytic cell 11 can be adjusted according to the amount of hypochlorous acid generated in the first electrolytic cell 5. It is possible to remove hypochlorous acid with hydrogen peroxide with high efficiency.

  A closed-circulation aquaculture system according to claim 3 of the present invention is a closed-circulation aquaculture system in which seawater in a breeding aquarium 1 for rearing fish and shellfish is circulated while purifying it through a circulation path 2, and is opposed to each other with a non-circular membrane An electrolytic cell 15 for electrolyzing salt water between the anode 13 and the cathode 14 to generate hypochlorous acid on the anode 13 side and hydrogen peroxide on the cathode 14 side is connected to the circulation path 2. It is characterized by comprising.

  According to the present invention, seawater can be sterilized and sterilized by hypochlorous acid produced on the anode 13 side of the electrolytic cell 15, and seawater is produced by hydrogen peroxide produced on the cathode chamber 14 side. It is possible to decompose hypochlorous acid contained in excess, and it is possible to remove excess hypochlorous acid without using a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device. It can be done.

  According to the present invention of claim 1, seawater can be sterilized and disinfected with hypochlorous acid generated by electrolyzing seawater in the first electrolytic cell 5, and the second electrolytic cell 11 is used. , The hypochlorous acid contained excessively in the seawater passing through the first electrolytic cell 5 can be decomposed by hydrogen peroxide generated in the cathode chamber 10 by electrolysis of seawater. As a result, it is possible to remove excess hypochlorous acid without using a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device.

  According to the invention of claim 3, seawater can be sterilized and sterilized by hypochlorous acid generated on the anode 13 side of the electrolytic cell 15, and peroxidation generated on the cathode chamber 14 side. With hydrogen, hypochlorous acid contained excessively in seawater can be decomposed. As a result, it is possible to remove excess hypochlorous acid without using a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1A shows an example of an embodiment of the present invention, in which a circulation path 2 is connected to a breeding aquarium 1 where seafood is raised, and a circulation pump 20 provided in the circulation path 2 is operated. By doing so, the seawater in the breeding aquarium 1 is circulated through the circulation path 2. The circulation path 2 is connected with a circulation pump 20, a water purification device 21, a first electrolytic tank 5, and a mixing tank 22 in the order along the flow of seawater. The water purification device 21 includes a physical filtration unit that removes solids in seawater by filtration, a biological filtration unit that decomposes and removes ammonia in seawater with microorganisms such as nitrifying bacteria, and the like. By passing the seawater in the breeding aquarium 1 through the water purification device 21 and circulating it, the seawater in the breeding aquarium 1 is maintained in a water quality suitable for breeding seafood, and the seafood is raised in a closed circulation system. It is something that can be done.

  As shown in FIG. 1B, an anode 3 and a cathode 4 are disposed in the tank of the first electrolytic cell 5 in parallel with the direction in which seawater flows, and the anode 3 and the cathode 4 do not pass through a diaphragm. Directly opposed. The anode 3 and the cathode 4 are electrically connected to a DC power source (not shown) via the control unit 12 so that a positive potential is applied to the anode 3 and a negative potential is applied to the cathode 4. It is.

  In FIG. 1, reference numeral 11 denotes a second electrolytic cell. An anode chamber 8 and a cathode chamber 10 are formed in the second electrolytic cell 11 by partitioning a diaphragm 6. An anode 7 is disposed in the anode chamber 8, and a cathode 9 is disposed in the cathode chamber 10, and the anode 7 and the cathode 9 are opposed to each other through the diaphragm 6. The anode 7 and the cathode 9 are electrically connected to a DC power source via the control unit 12 so that a positive potential DC current is passed through the anode 7 and a negative potential is passed through the cathode 9. A salt water storage tank 24 is connected to the second electrolytic tank 11 through a circulation water channel 25 so that the salt water is circulated through the second electrolytic tank 11. As the salt water, salt water such as seawater is preferably used, and the salt concentration is desirably 0.5% by mass or more. The circulation water channel 25 is branched on the inlet side of the second electrolytic cell 11 and connected to the inlets of the anode chamber 8 and the cathode chamber 10, respectively. On the outlet side of the second electrolytic cell 11, the circulation water channel 25 is connected to the anode chamber. 8 outlets are connected. The outlet of the cathode chamber 10 is connected to the mixing tank 22 by the addition water channel 26.

  In the closed circulation system aquaculture system formed as described above, seawater in the breeding aquarium 1 is supplied to the water purification device 21 through the circulation path 2 by the circulation pump 20 and purified in the water purification device 21 as described above. It is processed. The seawater thus purified flows from the water purification device 21 into the first electrolytic cell 5 through the circulation path 2 and passes through the first electrolytic cell 5. In this way, seawater can be electrolyzed by passing a direct current through the anode 3 and the cathode 4 facing each other with a non-diaphragm while passing seawater through the first electrolytic cell 5. The following electrode reaction occurs on the surface of the cathode and the surface of the cathode 4.

Anode: Cl ⁻ + 2OH ⁻ → ClO ⁻ + H ₂ O + 2e ⁻
Cathode: 2H ⁺ + 2e ⁻ → H ₂
Thus, hypochlorous acid is generated by the electrode reaction on the surface of the anode 3, and seawater containing this hypochlorous acid flows into the mixing tank 22 through the circulation path 2 and is stored in the mixing tank 22. During this time, seawater can be disinfected and decolorized with hypochlorous acid. Here, it is possible to decompose ammonia in seawater with hypochlorous acid. However, when ammonia is biologically nitrified and removed by the water purification device 21 as described above, hypochlorous acid is used. It is not necessary to decompose ammonia by means of seawater, so it is not necessary to electrolyze seawater so as to generate hypochlorous acid at a high concentration. For example, hypochlorous acid is generated at a concentration of about 0.5 mg / L or less. You can make it. Further, since hydrogen ions (H ⁺ ) are released as hydrogen gas (H ₂ ) by the cathode reaction of the cathode 13, the pH rises due to the decrease in hydrogen ions, and the pH of seawater can be raised. It is. When ammonia is biologically nitrified and removed with the water purification device 21 as described above, the pH of seawater tends to decrease due to the formation of nitric acid, but as described above, the pH increases due to the cathodic reaction. By adjusting the pH, the pH of seawater can be adjusted and maintained at a pH suitable for the rearing of seafood.

  On the other hand, the salt water can be electrolyzed by passing a direct current through the anode 7 and the cathode 9 facing each other through the diaphragm while allowing the salt water to pass through the second electrolytic cell 11. The following electrode reaction occurs on the surface of the cathode 9.

Anode: Cl ⁻ + 2OH ⁻ → ClO ⁻ + H ₂ O + 2e ⁻
Cathode: O ₂ + 2e ⁻ → O ₂ ⁻
O ₂ ⁻ + 2H ⁺ + e ⁻ → H ₂ O ₂
Thus, hydrogen peroxide is generated in the cathode chamber 10 by the electrolytic reaction on the surface of the cathode 9. Here, in order to efficiently generate hydrogen peroxide by the electrolytic reaction of the cathode 9, it is desirable that the dissolved oxygen amount (DO) of the salt water passed through the cathode chamber 10 is high, and it is DO5 mg / L or more. preferable. For this purpose, oxygen may be supplied to the salt water passed through the cathode chamber 10. Further, instead of supplying salt water to the cathode chamber 10, purified water (fresh water) not containing salt may be supplied to the cathode chamber 10 from the purified water supply path 27 and passed therethrough. Purified water serves as a source of H ^{+ for} the cathodic reaction and can increase the production efficiency of hydrogen peroxide.

  Then, water containing hydrogen peroxide passing through the cathode chamber 10 of the second electrolytic cell 11 is added to the mixing vessel 22 through the addition water channel 26, and flows into the mixing vessel 22 through the first electrolytic cell 5. Mixed with seawater. Since hydrogen peroxide has a disinfecting and disinfecting action and a decolorizing action, seawater can be disinfected and discolored with this hydrogen peroxide. Further, this hydrogen peroxide can react with hypochlorous acid in the following reaction formula to decompose hypochlorous acid into chlorine.

H ₂ O ₂ + ClO ⁻ → Cl ⁻ + H ₂ O + O ₂
Thus, the excess hypochlorous acid produced | generated in the 1st electrolytic cell 5 by supplying the water containing hydrogen peroxide from the cathode chamber 10 of the 2nd electrolytic cell 11 to the mixing tank 22, and adding it. Can be decomposed by neutralizing with hydrogen peroxide, and seawater is bred from the mixing tank 22 in a state where the concentration of excess hypochlorous acid is low enough not to exert fish poisoning action. 1 can be returned through the circulation path 2. Accordingly, it is not necessary to provide a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device in order to remove excess hypochlorous acid. In addition, when hypochlorous acid reacts with hydrogen peroxide and decomposes in this way, the following intermediate reaction occurs, generating chlorine radicals and hydroxyl radicals with strong oxidizing power. This radical can also disinfect and disinfect seawater.

HClO + H ₂ O ₂ → Cl · + 3OH ·
For example, when hypochlorous acid is generated at a concentration of 0.5 mg / L in the first electrolytic cell 5 and hydrogen peroxide is generated at a concentration of 0.5 mg / L in the cathode chamber 10 of the second electrolytic cell 11 By keeping these in the mixing tank 22 for 3 minutes, the seawater can be sterilized at a sterilization rate of 99%, and neither hypochlorous acid nor hydrogen peroxide remains in the seawater. Is something that can be done.

  Since hydrogen peroxide has very low fish toxicity, the amount of hydrogen peroxide generated in the cathode chamber 10 of the second electrolytic cell 11 is smaller than the amount of hypochlorous acid generated in the first electrolytic cell 5. It is desirable that there are many. Therefore, the control unit 12 detects the amount of electricity when the anode 3 and the cathode 4 of the first electrolytic cell 5 are energized to electrolyze seawater, and the second electrolytic cell 11 is based on the detected amount of electricity. The amount of hydrogen peroxide generated in the cathode chamber 10 of the second electrolytic cell 11 is reduced to hypochlorous acid generated in the first electrolytic cell 5 by calculating and controlling the amount of electricity supplied to the control unit 12. It is set to be larger than the acid amount. Here, the relationship between the amount of electricity supplied to the first electrolytic cell 5 and the amount of generated hypochlorous acid, and the relationship between the amount of electricity applied to the second electrolytic cell 11 and the amount of generated hydrogen peroxide. Are obtained in a preliminary test, and their relational expressions are stored in the control unit 12. When the amount of electricity supplied to the first electrolytic cell 5 is detected by the control unit 12, the amount of hypochlorous acid generated can be calculated based on the amount of electricity, and the calculated hypochlorous acid is further calculated. The amount of electricity supplied to the second electrolytic cell 11 can be calculated and controlled so that the amount of hydrogen peroxide generated is greater than the amount of acid generated.

  FIG. 2 shows an example of another embodiment of the present invention. The circulation pump 20, the water purification device 21, the electrolytic cell 15, and the mixing are arranged in the order along the flow of seawater in the circulation path 2 of the breeding aquarium 1. A tank 22 is connected. The structure of the breeding water tank 1, the circulation path 2, the circulation pump 20, the water purification device 21, and the mixing tank 22 is the same as that of the embodiment of FIG.

  As shown in FIG. 2, an anode 13 and a cathode 14 are disposed in the tank of the electrolytic cell 15 in parallel with the direction in which seawater flows. The anode 13 and the cathode 14 are directly opposed to each other without a diaphragm. A DC power supply 29 is electrically connected to the anode 13 and the cathode 14 so that a positive potential DC current is supplied to the anode 13 and a negative potential is supplied to the cathode 14.

And in this electrolytic cell 15, the anode 13 and the cathode 14 are each formed with the iridium plating titanium electrode, and the distance between electrodes of the anode 13 and the cathode 14 is set to the range of 3-5 mm. The water flow rate of seawater passing through the electrolytic cell 15 is set to 90 mm / second or more (preferably 1500 mm / second or less), and the current density of the direct current flowing through the anode 13 and the cathode 14 is 0.1. It is set to ~4A / dm ^2. Furthermore, oxygen is supplied to the seawater passed through the electrolytic cell 15 so that the dissolved oxygen content of the seawater at the inlet of the electrolytic cell 15 is a dissolved oxygen amount close to saturation of 5 mg / L or more.

  When seawater is electrolyzed in the electrolytic cell 15 under the above conditions, the following electrode reaction occurs on the surface of the anode 13 and the surface of the cathode 14.

Anode: Cl ⁻ + 2OH ⁻ → ClO ⁻ + H ₂ O + 2e ⁻
Cathode: O ₂ + 2e ⁻ → O ₂ ⁻
O ₂ ⁻ + 2H ⁺ + e ⁻ → H ₂ O ₂
Thus, hypochlorous acid is generated by the electrode reaction on the surface of the anode 13, and hydrogen peroxide is generated by the electrode reaction on the surface of the cathode 14.

Here, the anode 14 and the cathode 14 are formed with iridium-plated titanium electrodes, the distance between the electrodes is set to 3 mm, the current density is set to 0.45 A / dm ² , and the dissolved oxygen amount is set to 6 mg / L. 15, the relationship between the water flow rate of seawater passing through the electrolytic cell 15 and the hydrogen peroxide concentration in the seawater at the outlet of the electrolytic cell 15 when electrolysis is performed at 15 is shown in Table 1. . As seen in Table 1, hydrogen peroxide was generated by setting the water flow rate to 90 mm / second or more.

  Further, the anode 14 and the cathode 14 are formed with iridium-plated titanium electrodes, the distance between the electrodes is set to 3 mm, the passage speed of seawater in the electrolytic cell 15 is set to 1095 mm / sec, and the dissolved oxygen amount is set to 6 mg / L. The relationship between the current density applied to the electrolytic cell 15 and the hydrogen peroxide concentration in the seawater at the outlet of the electrolytic cell 15 when electrolysis is performed in the electrolytic cell 15 is shown in Table 2.

  By electrolyzing seawater in the electrolytic cell 15 as described above, hypochlorous acid is produced at the anode 13 and hydrogen peroxide is produced at the cathode 14, and this hypochlorous acid and hydrogen peroxide are contained. The seawater that flows into the mixing tank 22 flows from the electrolytic tank 15 through the circulation path 2. And while storing in the mixing tank 22, seawater can be disinfected and decolored with hypochlorous acid. Further, since hydrogen peroxide also has a disinfecting and disinfecting action and a decolorizing action, seawater can be disinfected and discolored with this hydrogen peroxide. For example, when hypochlorous acid and hydrogen peroxide are produced at a concentration of 0.5 mg / L, the seawater can be sterilized at a sterilization rate of 99% by retaining the seawater in the mixing tank 22 for 3 minutes. it can.

  Further, hydrogen peroxide reacts with hypochlorous acid in the mixing tank 22 by the same reaction formula as described above, and hypochlorous acid can be decomposed into chlorine. In this way, excess hypochlorous acid can be decomposed by neutralizing with hydrogen peroxide, and the concentration of excess hypochlorous acid was made low enough not to exert fish poisoning effects. In this state, seawater can be returned from the mixing tank 22 to the breeding tank 1 through the circulation path 2. Accordingly, it is not necessary to provide a chlorine removing device such as an activated carbon filling tank or a neutralizing agent adding device in order to remove excess hypochlorous acid.

BRIEF DESCRIPTION OF THE DRAWINGS It shows an example of embodiment of this invention, (a) is the whole schematic, (b) is the expanded schematic sectional drawing of the part of a 1st electrolytic cell, a 2nd electrolytic cell, and a mixing tank. is there. It is the whole schematic which shows an example of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Breeding tank 2 Circulation route 3 Anode 4 Cathode 5 First electrolytic cell 6 Diaphragm 7 Anode 8 Anode chamber 9 Cathode 10 Cathode chamber 11 Second electrolytic cell 12 Control unit 13 Anode 14 Cathode 15 Electrolyzer

Claims (3)

  In a closed-circulation aquaculture system that circulates the seawater in the rearing tank for rearing seafood while purifying it through the circulation path, the salt water is electrolyzed between the anode and the cathode that are opposed to each other with a non-diaphragm, and the anode side The first electrolytic cell for generating hypochlorous acid is connected to the circulation path, and the anode chamber in which the anode is disposed and the cathode chamber in which the cathode is disposed is partitioned by a diaphragm, and the salt water is electrolyzed. A second electrolytic cell for generating hydrogen peroxide is provided on the cathode side, and salt water in the cathode chamber of the second electrolytic cell is mixed with seawater that has passed through the first electrolytic cell. Closed circulation aquaculture system.   The first electrolyzer is provided with a control unit that controls the amount of electricity energized for electrolysis in accordance with the amount of electricity energized for electrolysis. The closed circulation culture system according to claim 1. In a closed-circulation aquaculture system that circulates the seawater in the rearing tank for raising seafood while purifying it through the circulation path, the salt water is electrolyzed between the anode and the cathode that are opposed to each other with a non-diaphragm. A closed-circulation aquaculture system comprising an electrolytic cell for generating hypochlorous acid on the side and hydrogen peroxide on the cathode side, connected to a circulation path.

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