Closed circulation purification system for land-based aquaculture of fish and shellfish, electrolytic treatment device for land-based aquaculture applied to said system, and method for improving water quality in aquaculture tanks

Abstract

To improve water quality of aquaculture tank by laconically utilizing water in the aquaculture tank.SOLUTION: A purification system for a closed circulation-type land-based aquaculture comprises: an aquaculture tank for raising fish and shellfish to be farmed; a nitrification device for receiving aquaculture tank water before purification, containing an ammonia component stored in the aquaculture tank and nitrifying the ammonia component via aerobic bacteria; a denitrification device for receiving primary purified water containing nitrate nitrogen generated by nitrification of the ammonia component and denitrifying the nitrate nitrogen via anaerobic bacteria; an electrolytic treatment device configured to include an anode tank and a cathode tank demarcated by an ion-exchangeable diaphragm, receiving the aquaculture tank water in the cathode tank and performing electrolytic treatment; oxygen gas supply means for supplying oxygen gas generated in the anode tank to the nitrification device; hydrogen gas supply means for supplying hydrogen gas generated in the cathode tank to the denitrification device; and control means for controlling the electrolytic treatment device, the oxygen gas supply means and the hydrogen gas supply means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a purification technology for tanks used in land-based aquaculture of fish and shellfish, and more specifically to a closed-circulation land-based aquaculture purification system that purifies the water in the tanks efficiently using an electrolysis device in a purification system including a nitrification tank and a nitridation tank, as well as an electrolysis device for land-based aquaculture that is applied to the system and a method for improving the water quality of the aquaculture tanks. [Background technology]

[0002] It has been a long time since fish and shellfish have been cultivated in aquaculture tanks on the seashore or on land away from the seashore. In such aquaculture tanks, ammonia (so-called ammonia nitrogen) is generated due to the feed given to the fish and shellfish or the excretion of metabolic products such as feces, and it is known that this causes a deterioration in the water quality of the aquaculture tanks.

[0003] To address this issue, a conventional method involves installing a nutrient circulation system to circulate the water in the aquaculture tank, and then installing a nitrification tank in this circulation system, where aerobic bacteria nitrify the ammonia and convert it into nitrate nitrogen. Although the installation of this nitrification tank reduces the harm caused by ammonia to fish and shellfish, if the nitrate nitrogen accumulates in the water beyond a certain level, it can affect the feeding of fish and shellfish. Therefore, a denitrification process has also been used in which the water from the aquaculture tank is received and anaerobic bacteria decompose the nitrate nitrogen in the water to nitrogen gas.

[0004] There are also technologies for electrolyzing water in aquaculture tanks, as exemplified in the following patent documents: For example, Patent Document 1 proposes a technology in which the ammonia concentration of sodium chloride-containing water removed from the tank is measured using an ammonia measuring means, the water is electrolyzed to supply active chlorine species to the water, and the residual chlorine concentration in the treated water is measured using a chlorine measuring means and returned to the tank.

[0005] On the other hand, the electrolytic treatment device disclosed in Patent Document 2 has an anode cell equipped with an anode and a cathode cell equipped with a cathode separated by a specified diaphragm, and a portion of the rearing water treated in a bio-purification treatment device is supplied to the electrolytic treatment device and electrolyzed, with a portion of the water in the anode cell being discharged to the outside and the remainder being returned to the aquarium. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-160349 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-73458 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the prior art including the above-mentioned patent documents still has the following problems and there is much room for improvement. That is, it is true that effective improvement of water quality in aquaculture tanks can be achieved by utilizing electrolytic treatment equipment, as shown in Patent Documents 1 and 2. However, Patent Document 1 only describes the implementation of electrolytic treatment for the purpose of improving the efficiency of ammonia treatment, and does not go so far as to describe pH adjustment or other efficient uses.

[0008] On the other hand, according to Patent Document 2, compared to the configuration of Patent Document 1, it is more effective in that it also utilizes electrolysis to adjust the pH in the aquaculture tank. However, since the pH of the entire rearing water is adjusted by discharging a portion of the acidic water on the anode side generated by the electrolysis, waste of wastewater is inevitable, and there is room for further improvement in efficiency.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a closed-circulation purification system for land-based aquaculture of fish and shellfish, in which the products obtained by electrolyzing the water in aquaculture tanks can be used to improve the water quality of the aquaculture tanks without waste, and an electrolytic treatment device for land-based aquaculture that can be applied to the system. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, one embodiment of the present invention provides a closed-circulation land-based aquaculture purification system for fish and shellfish, characterized in that it includes: (1) aquaculture tanks for raising fish and shellfish to be cultured; a nitrification device that receives pre-purification tank water containing ammonia components stored in the aquaculture tanks and nitrifies the ammonia components using aerobic bacteria; a denitrification device that receives primary purified water containing nitrate nitrogen produced by nitrification of the ammonia components and denitrifies the nitrate nitrogen using anaerobic bacteria; an electrolytic treatment device that includes an anode chamber and a cathode chamber separated by an ion-exchangeable diaphragm and receives water from the aquaculture tanks in the cathode chamber and performs electrolysis; oxygen gas supply means that supplies oxygen gas produced in the anode chamber to the nitrification device; hydrogen gas supply means that supplies hydrogen gas produced in the cathode chamber to the denitrification device; and control means for controlling the electrolytic treatment device, the oxygen gas supply means, and the hydrogen gas supply means.

[0011] In addition, in the closed circulation land-based aquaculture purification system described in (1) above, it is preferable that (2) a foreign matter removal filter be further provided to remove foreign matter from the pre-purification tank water, and that the water from the aquaculture tank that has passed through the foreign matter removal filter be received in the cathode tank.

[0012] Furthermore, in the closed circulation land-based aquaculture purification system described in (1) or (2) above, it is preferable that the system further comprises (3) an acidic water storage tank for storing water different from the unpurified tank water sent to the cathode tank, and a pair of forward and return pipes connecting the acidic water storage tank and the anode tank, wherein the water stored in the acidic water storage tank is sent to the anode tank via the forward pipe, and the acidic water produced in the anode tank is returned to the acidic water storage tank via the return pipe.

[0013] In addition, in the closed circulation land-based aquaculture purification system described in (3) above, (4) it is preferable that the oxygen gas supply means includes the acidic water storage tank and an oxygen gas supply pipe that supplies the oxygen gas generated by gas-liquid separation in the acidic water storage tank to the nitrification device.

[0014] In addition, in the closed circulation land-based aquaculture purification system described in any of (1) to (4) above, (5) it is preferable that the hydrogen gas supply means includes an alkaline water storage tank that receives alkaline water produced by electrolysis in the cathode tank, and a hydrogen gas supply pipe that supplies hydrogen gas produced by gas-liquid separation in the alkaline water storage tank to the denitrification device.

[0015] The closed circulation land-based aquaculture purification system described in (5) above further comprises (6) a pH meter for detecting a pH value in the aquaculture tank, and an alkaline water supply pipe connecting the alkaline water storage tank and the aquaculture tank, means It is preferable to perform control to continuously supply the hydrogen gas to the denitrification device while intermittently returning the alkaline water to the aquaculture tank based on the pH value.

[0016] Furthermore, in order to solve the above-mentioned problems, an electrolytic treatment device for land-based aquaculture applicable to a closed-circulation land-based aquaculture purification system for fish and shellfish according to one embodiment of the present invention is (7) an electrolytic treatment device for land-based aquaculture used in a closed-circulation land-based aquaculture purification system described in any one of (1) to (6) above, comprising an electrolytic cell including an anode cell and a cathode cell separated by an ion-exchangeable diaphragm, an acidic water storage tank capable of storing acidic water produced in the electrolytic cell, an alkaline water storage tank capable of storing alkaline water produced in the electrolytic cell, and Acidic Water Storage Tank an oxygen supply means for supplying oxygen generated through the acidic water stored in the storage tank to the nitrification device; Alkaline Water Storage Tank a hydrogen supply means for supplying hydrogen generated through the alkaline water stored in the electrolytic cell to the denitrification device; and a control means for controlling the electrolytic cell, the oxygen supply means, and the hydrogen supply means. means and [Effects of the Invention]

[0018] According to the present invention, not only is electrolyzed water obtained by electrolyzing the water in the aquaculture tank, but oxygen gas and hydrogen gas generated through this electrolyzed water are also supplied to the nitrification device and denitrification device, so that the products obtained by the electrolysis process can be used efficiently and without waste. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an overall configuration diagram of a closed circulation type land-based aquaculture purification system for seafood, including an electrolytic treatment device for land-based aquaculture according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an electrolytic treatment tank included in an electrolytic treatment device for land-based aquaculture. [Figure 3] FIG. 2 is a schematic diagram showing the functional blocks of a control device included in the electrolytic treatment device for land-based aquaculture. [Figure 4] 1 is a flowchart showing a water quality improving method applied to a closed circulation land-based aquaculture purification system in the first embodiment. [Figure 5] FIG. 10 is an overall configuration diagram of a closed circulation type purification system for land-based aquaculture of seafood, including an electrolytic treatment device for land-based aquaculture according to a second embodiment. [Figure 6] FIG. 10 is an overall configuration diagram of a closed circulation type land-based aquaculture purification system for seafood, including an electrolytic treatment device for land-based aquaculture according to a third embodiment. [Figure 7] FIG. 10 is a configuration diagram of a modified closed circulation type land-based aquaculture purification system for fish and shellfish. DETAILED DESCRIPTION OF THE INVENTION

[0020] In the following, an embodiment for carrying out the present invention will be described, which is a closed circulation type land-based aquaculture purification system that is applied to an aquaculture tank installed, for example, near the coast or on land, etc. Note that configurations other than those described in detail below can be supplemented by referring to known technologies, including, for example, the patent documents mentioned above.

[0021] First Embodiment [Closed circulation land-based aquaculture purification system 100] 1 is an overall configuration diagram of a closed-circulation land-based aquaculture purification system 100 for fish and shellfish according to the first embodiment. That is, the closed-circulation land-based aquaculture purification system 100 of this embodiment includes an aquaculture tank 10, a nitrification device 20, a denitrification device 30, an electrolytic treatment device 40, an oxygen gas supply means 50, a hydrogen gas supply means 60, and a control device 70.

[0022] The aquaculture tank 10 is provided for raising the fish and shellfish to be cultivated. Various known tanks can be used as the aquaculture tank 10 depending on the properties and types of the target fish and shellfish. Furthermore, as will be described later, the aquaculture tank 10 may be equipped with a known sensor for measuring the water quality within the tank. As an example, in this embodiment, the aquaculture tank 10 is equipped with a known pH sensor 81 capable of detecting the pH within the aquaculture tank 10 and a known water temperature sensor 82 capable of detecting the water temperature within the aquaculture tank 10.

[0023] Furthermore, the "seafood" in this embodiment refers to various known fish species such as pufferfish, flounder, and sturgeon, shellfish such as scallops and abalone, and echinoderms such as sea cucumbers and sea urchins, as well as known aquatic animals and plants that can be cultivated for food. Although edible seafood is exemplified in this embodiment, the closed-circulation land-based aquaculture purification system 100 of the present invention is not limited to the above applications and may also be used to raise ornamental aquatic animals such as dolphins.

[0024] The nitrification device 20 receives the pre-purification tank water W1 containing ammonia components stored in the aquaculture tank 10 and nitrifies the ammonia components using aerobic bacteria. Such a nitrification device 20 contains known nitrifying bacteria (ammonia-oxidizing bacteria, nitrite-producing bacteria) capable of nitrifying ammonia components, such as the nitrification device disclosed in Japanese Patent Laid-Open Publication No. 3-216129. Within such a nitrification device 20, ammonia components are nitrified by the aerobic nitrifying bacteria that require oxygen.

[0025] Therefore, in this embodiment, as shown in Figure 1, the pre-purification tank water W1 containing ammonia components in the aquaculture tank 10 is pumped to the nitrification device 20 via a known pumping pump P, where the pre-purification tank water W1 is nitrified, and then the primary purified water W2 containing nitrate nitrogen is returned from the nitrification device 20 to the aquaculture tank 10.

[0026] The denitrification device 30 receives the primary purified water containing nitrate nitrogen produced by the nitrification of the ammonia component, and denitrifies the nitrate nitrogen using anaerobic bacteria. The denitrification device 30 can be exemplified by the nitrification device disclosed in Japanese Patent Laid-Open Publication No. 3-216129, which performs a reaction to reduce the nitrate nitrogen to nitrogen gas, and generates nitrogen gas by using the oxygen in the nitrate nitrogen to oxidize and decompose organic matter into carbon dioxide and water. Within the denitrification device 30, nitrate nitrogen is denitrified by anaerobic bacteria that require an anaerobic atmosphere with a reduced oxygen concentration.

[0027] In this way, the nitrification device 20 increases the concentration of nitrate nitrogen in the aquaculture tank 10, and the denitrification device 30 denitrifies the nitrate nitrogen contained in the primary purified water W2 to produce secondary purified water W3. More specifically, as shown in Fig. 1, the primary purified water W2 containing nitrate nitrogen in the aquaculture tank 10 is pumped to the denitrification device 30 via a known pumping pump P, where the primary purified water W2 is denitrified. Thereafter, the secondary purified water W3 in which the nitrate nitrogen has been reduced is returned from the denitrification device 30 to the aquaculture tank 10.

[0028] The electrolytic treatment device 40 is configured to have at least the function of receiving water from the aquaculture tank described above in a cathode chamber 43 and performing electrolysis. More specifically, as shown in Fig. 2, the electrolytic treatment device 40 of this embodiment is configured with a known electrolytic chamber 41 including an anode chamber 42 and a cathode chamber 43 separated by a known ion-exchangeable diaphragm 44. An anode E2 is installed in the anode chamber 42, and a cathode E1 is installed in the cathode chamber 43. The cathode E1 and the anode E2 are electrically connected to a known commercial power source E, allowing a desired voltage to be applied between these electrodes. In this embodiment, the water in the aquaculture tank described above tends to become acidic through the raising of fish and shellfish. To neutralize this acidity, the aquaculture water is directly electrolyzed in the electrolytic treatment device 40 to make it alkaline. It is important to note that, because the water in the aquaculture tank is seawater, flowing seawater into the anode chamber 42 would produce highly toxic substances such as hypochlorous acid. On the other hand, flowing seawater into the cathode chamber 43 and subjecting it to electrolysis would not produce highly toxic substances such as hypochlorous acid. Therefore, in this embodiment, a liquid other than seawater, such as tap water, is flowed into the anode chamber 42 of the electrolytic treatment device 40, and the water from the aquaculture tank (seawater) is flowed only into the cathode chamber 43. If the seawater in the cathode chamber 43 and the tap water in the anode chamber 42 were to mix, the hypochlorous acid produced in the anode chamber 42 would flow into the cathode chamber 43, resulting in the hypochlorous acid being mixed with the seawater. To prevent this, the diaphragm 44 (ion exchange membrane) described above is used.

[0029] As shown in the figure, water Wc is supplied from an acidic water storage tank 51 (described later) through a known pipe (outgoing pipe 52a) to an anode cell 42 separated by a diaphragm 44 from an electrolytic cell 41, and acidic water W5 electrolyzed by an anode E2 arranged in the anode cell 42 is returned to the acidic water storage tank 51 through a known pipe (return pipe 52b).

[0030] As described above, the closed circulation land-based aquaculture purification system 100 of this embodiment is configured to include an acidic water storage tank 51 that stores water different from the pre-purification tank water W1 that is supplied to the anode tank 42, and a pair of forward and return pipes 52a and 52b that connect this acidic water storage tank 51 and the anode tank 42.

[0031] The water stored in the acidic water storage tank 51 is sent to the anode tank 42 via the outgoing pipe 52a, and the acidic water W5 produced in the anode tank 42 is returned to the acidic water storage tank 51 via the return pipe 52b. In this embodiment, the acidic water storage tank 51 is configured to be supplied with known tap water or the like via a known water source WS (for example, a municipal water supply. Groundwater may also be used as a water source). Therefore, the acidic water storage tank 51 is initially supplied with the above-mentioned tap water, or tap water is appropriately replenished to dilute the returned acidic water. This tap water (which will contain acidic water after electrolysis) can be sent to the anode tank 42 via the outgoing pipe 52a. The acidic water storage tank 51 is connected to a drainage means DM equipped with a known drain pipe and valve, and the liquid in the tank can be drained appropriately via this drainage means DM. That is, if the liquid stored in the acidic water storage tank 51 is left for a long time, for example, the pH value will drop, which will have an adverse effect on the generation of alkaline water on the cathode side. Therefore, it is preferable to replenish and drain the acidic water storage tank 51 with tap water as described above. For example, in summer, the water in the acidic water storage tank 51 will become hot. In such cases, it is preferable to perform this drainage process to forcibly drain the water in the tank and replenish it with new water.

[0032] The oxygen gas supply means 50 is configured to have the function of supplying oxygen gas generated via the acidic water W5 sent from the anode tank 42 to the nitrification device 20. More specifically, the oxygen gas supply means 50 of this embodiment preferably includes the acidic water storage tank 51 described above, an oxygen gas supply pipe 52c that supplies the oxygen gas generated by gas-liquid separation in the acidic water storage tank 51 to the nitrification device 20, and a known supply valve (not shown) disposed on the oxygen gas supply pipe 52c. Specific examples of the oxygen gas supply pipe 52c include various known oxygen supply pipes that are sealed off from the outside air and ensure airtightness.

[0033] In this embodiment, the acidic water W5 stored in the acidic water storage tank 51 is appropriately diluted with the above-mentioned tap water, and the oxygen gas separated from the gas and liquid in the acidic water storage tank 51 is sent to the nitrification device 20 through the oxygen gas supply pipe 52c. This makes it possible to stably maintain and improve the oxygen concentration in the nitrification device 20, and to efficiently carry out the above-mentioned nitrification reaction by aerobic bacteria.

[0034] Similarly, water W4 (a mixture of pre-purification tank water W1, primary purified water W2, and secondary purified water W3) in the aquaculture tank 10, which has been supplied from the aquaculture tank 10 via a known piping 11, is poured into the cathode tank 43 of the electrolytic cell 41, which is separated by a diaphragm 44. At the same time, water W6 that has been electrolyzed by the cathode E1 arranged in the cathode tank 43 and has tended to be alkaline (water that has been electrolyzed on the cathode side and has tended to be alkaline in this embodiment is referred to as alkaline water) is supplied to the alkaline water storage tank 61 via a known alkaline water piping 62a.

[0035] As described above, the closed circulation land-based aquaculture purification system 100 of this embodiment is configured to include a pipe 11 for supplying pre-purification tank water W1 to the anode tank 42 via a known water supply pump, an alkaline water storage tank 61 for storing electrolyzed alkaline water, an alkaline water pipe 62a connecting the alkaline water storage tank 61 to the electrolytic treatment device, and an alkaline water delivery pipe 62b connecting the alkaline water storage tank 61 to the aquaculture tank 10.

[0036] In this embodiment, the alkaline water W6 stored in the alkaline water storage tank 61 is supplied to the aquaculture tank 10 via the alkaline water delivery pipe 62b, and the hydrogen gas obtained by gas-liquid separation in the alkaline water storage tank 61 is sent to the denitrification device 30 via the hydrogen gas supply pipe 62c. This makes it possible to stably maintain and improve the anaerobic atmosphere in the denitrification device 30, and enables the above-mentioned reduction reaction by anaerobic bacteria to be carried out efficiently.

[0037] The hydrogen gas supply means 60 is configured to have the function of supplying hydrogen gas generated via the alkaline water W6 delivered from the cathode chamber 43 to the denitrification apparatus 30. More specifically, the hydrogen gas supply means 60 of this embodiment preferably includes an alkaline water storage tank 61 that receives the alkaline water W6 generated by electrolysis in the cathode chamber 43, a hydrogen gas supply pipe 62c that supplies hydrogen gas generated by gas-liquid separation in the alkaline water storage tank 61 to the denitrification apparatus 30, and a known supply valve (not shown) disposed on the hydrogen gas supply pipe 62c. Specific examples of the hydrogen gas supply pipe 62c include various known hydrogen supply pipes that are sealed off from the outside air and ensure airtightness.

[0038] The control device 70 is configured to have the function of controlling the operations of the electrolytic treatment device 40, the oxygen gas supply means 50, and the hydrogen gas supply means 60. As shown in Fig. 3, such control device 70 can be exemplified by a known computer equipped with a known storage device MD (e.g., a memory MR, a hard disk HD, or a solid state drive SSD) and a processing unit CPU.

[0039] <Functional blocks of the control device 70> Next, functions that can be executed by the control device 70 in this embodiment will be described in detail with reference to Figure 3. The functions described below are programmed by software and configured to be executable by the control device 70. Furthermore, at least a part of such programs may be executed by a known information processing server or other computer that is remotely located via a known network NW such as the Internet.

[0040] That is, the control device 70 in this embodiment is configured to include a pH detection unit 71 , an applied voltage determination unit 72 , an electrolytic cell drive unit 73 , an oxygen gas supply control unit 74 , and a hydrogen gas supply control unit 75 .

[0041] The pH detection unit 71 has a function of detecting the pH in the aquaculture tank 10 via the pH sensor described above. When the pH value detected by the pH detection unit 71 falls below a predetermined value, the control device 70 opens a valve (not shown) to supply alkaline water W6 from the alkaline water storage tank 61 into the aquaculture tank 10.

[0042] As a result, as described above, if the pH value in the aquaculture tank 10 drops to a pH value that is problematic for fish and shellfish (tending to be acidic), the aquaculture water can be directly electrolyzed (electrolyzed) in the cathode tank 43 to neutralize it so that it tends to be alkaline, thereby adjusting the pH value to a value suitable for aquaculture of fish and shellfish. The pH value that triggers the injection of alkaline water W6 can be set appropriately depending on the type of fish and shellfish being cultured in the aquaculture tank 10. As an example, in this embodiment, when the pH value detected by the pH detection unit 71 becomes 6.5 or lower, the control device 70 controls the supply of alkaline water W6 from the alkaline water storage tank 61 into the aquaculture tank 10.

[0043] The applied voltage determination unit 72 has the function of determining the voltage to be applied between the anode E2 and the cathode E1 of the electrolytic cell 41 described above. The applied voltage determination unit 72 may determine the applied voltage based on the pH value detected by the pH detection unit 71 described above. In addition to the above voltage, the applied voltage determination unit 72 may also determine the current value between the anode E2 and the cathode E1. As an example, the voltage applied between the anode E2 and the cathode E1 is preferably about 8 V to 45 V, and the current value is preferably controlled in the range of about 1 A to 20 A, but these can be adjusted appropriately depending on the scale of the apparatus.

[0044] The electrolytic cell drive unit 73 has a function of applying a voltage between the anode E2 and the cathode E1 of the electrolytic cell 41 via the commercial power supply E based on the voltage determined by the applied voltage determination unit 72. The control device 70 also controls valves (not shown) to supply water to the anode cell 42 and the cathode cell 43 of the electrolytic cell 41, respectively. As a result, the acidic water W5 and alkaline water W6 described above are stored in the acidic water storage tank 51 and the alkaline water storage tank 61.

[0045] The oxygen gas supply control unit 74 has a function of supplying oxygen stored in the acidic water storage tank 51 to the nitrification device 20. As an example, the oxygen gas supply control unit 74 can supply oxygen gas to the nitrification device 20 via the oxygen gas supply pipe 52c based on the oxygen concentration detected by an oxygen concentration sensor 83 installed in the nitrification device 20. Note that, although the oxygen concentration sensor 83 is used as described above in this embodiment, the present invention is not limited to this form, and the oxygen concentration sensor 83 may be omitted as appropriate when the above processing is performed based on time management using a known timer.

[0046] The hydrogen gas supply control unit 75 has a function of supplying hydrogen gas stored in the alkaline water storage tank 61 to the denitrification apparatus 30. As an example, the hydrogen gas supply control unit 75 can supply hydrogen gas to the denitrification apparatus 30 via the hydrogen gas supply pipe 62c based on the hydrogen concentration detected by a hydrogen concentration sensor 84 installed in the denitrification apparatus 30. Similarly, in this embodiment, the hydrogen concentration sensor 84 is used as described above, but the present invention is not limited to this embodiment, and the hydrogen concentration sensor 84 may be omitted as appropriate when the above process is performed based on time management using a known timer, for example.

[0047] Depending on the hydrogen concentration in the denitrification device 30, it may be preferable to continuously supply hydrogen gas to the denitrification device 30. Therefore, the closed-circulation land-based aquaculture purification system 100 of this embodiment is equipped with a pH sensor 81 that detects the pH value of the aquaculture tank 10 and an alkaline water delivery pipe 62b that connects the alkaline water storage tank 61 and the aquaculture tank 10, and the control device 70 may execute control to continuously supply hydrogen gas to the denitrification device 30 while intermittently returning alkaline water W6 to the aquaculture tank 10 based on the pH value.

[0048] The control device 70 of this embodiment is configured to be capable of communicating with various sensors 80 including the above-described pH sensor 81. The control device 70 may monitor the pH value in the aquaculture tank 10 and the status of the electrolytic treatment device 40 via a known display device DP such as a liquid crystal display panel. The control device 70 may also be connected to a known network NW such as the Internet via a known communication device CD such as a modem.

[0049] [Electrolytic treatment equipment for land-based aquaculture] The electrolytic treatment device for land-based aquaculture of this embodiment can be incorporated as part of the closed circulation type land-based aquaculture purification system 100 described above. More specifically, the electrolytic treatment device for land-based aquaculture of this embodiment is configured to include an electrolytic cell 41 including an anode cell 42 and a cathode cell 43 separated by the above-mentioned ion-exchangeable diaphragm 44, an acidic water storage tank 51 capable of storing the acidic water W5 produced in this electrolytic cell 41, an alkaline water storage tank 61 capable of storing the alkaline water W6 produced in this electrolytic cell 41, an oxygen gas supply means 50 that supplies oxygen produced via the acidic water W5 stored in the acidic water storage tank 51 to the nitrification device 20, a hydrogen gas supply means 60 that supplies hydrogen produced via the alkaline water W6 stored in the alkaline water storage tank 61 to the denitrification device 30, and a control device 70 that controls these electrolytic cell 41, the oxygen gas supply means 50, and the hydrogen gas supply means 60.

[0050] <How to improve the water quality of aquaculture tanks> Next, a method for improving the quality of water in a closed circulation land-based aquaculture system using the electrolytic treatment device 40 of this embodiment will be described with reference to FIG. First, in step 1, the pH value in the aquaculture tank 10 is measured by the pH detection unit 71 via the pH sensor 81 described above.

[0051] Next, in step 2, the control device 70 determines whether the pH value measured in step 1 is equal to or less than a predetermined reference value. If the pH value is equal to or less than the reference value in step 2, the process proceeds to step 3, whereas if the pH value is not equal to or less than the reference value, the process returns to step 1 and continues detecting the pH value.

[0052] If the pH value becomes equal to or lower than the reference value in step 2, then in the following step 3, the voltage to be applied between the anode E2 and the cathode E1 of the electrolytic cell 41 is determined by the applied voltage determination unit 72 described above.

[0053] Next, in step 4, water W4 from the aquaculture tank 10 is poured through the piping 11, and water Wc (for example, tap water at first) is poured from the acidic water storage tank 51 through the outgoing pipe 52a. In step 4, electrolysis is then carried out in the electrolytic cell 41 based on the applied voltage determined in step 3.

[0054] In step 5-A, the control device 70 determines whether the oxygen concentration in the nitrification device 20 and the hydrogen concentration in the denitrification device 30 are below the reference value via the sensors 80 (oxygen concentration sensor 83, hydrogen concentration sensor 84). In this embodiment, both the oxygen concentration and hydrogen concentration are monitored, but it is also possible to monitor at least one of the values.

[0055] If at least one of the hydrogen concentration and oxygen concentration falls below a reference value in step 5-A, control is executed to supply the deficient gas to the target tank in the following step 6. For example, if the oxygen concentration in nitrification device 20 falls below the reference value and becomes insufficient, oxygen gas is supplied into nitrification device 20 via oxygen gas supply means 50 by oxygen gas supply control unit 74 in step 6.

[0056] On the other hand, in step 5-B, alkaline water W6 generated by the electrolytic cell 41 and stored in the alkaline water storage tank 61 is supplied to the aquaculture tank 10 by the control device 70. This allows the lowered pH in the tank to be restored to an appropriate value for the fish and shellfish being cultivated.

[0057] After the above steps, in step 7, it is determined whether the system power supply that controls the entire closed circulation land-based aquaculture purification system 100 has been turned off.If the system is still operating, the process returns to step 1 and continues the above-mentioned processing, while if the system power supply has been turned off, the processing by this method is terminated.

[0058] As described above, the method for improving the water quality of an aquaculture tank executed in the closed-circulation land-based aquaculture purification system 100 of this embodiment is characterized by including the steps of measuring the pH value in the aquaculture tank using a pH sensor, determining an applied voltage to be applied to the electrolytic treatment device based on the measured pH value, performing electrolytic treatment based on the determined applied voltage, measuring at least one of the oxygen concentration in the nitrification device and the hydrogen concentration in the denitrification device, and, when at least one of the oxygen concentration and the hydrogen concentration is below a reference value, supplying the missing gas of oxygen gas and hydrogen gas generated via the electrolytic treatment device to a target tank.

[0059] According to the closed circulation land-based aquaculture purification system 100 including the land-based aquaculture electrolytic treatment device in this embodiment described above, alkaline water generated by the electrolytic treatment is supplied to the aquaculture tank, which makes it possible to suppress a decrease in the pH value in the aquaculture tank. In addition, it is possible to supply oxygen gas and hydrogen gas necessary for the nitrification device and denitrification device via this electrolytic treatment. When fish and shellfish are raised in aquaculture tanks as in this embodiment, the pH value in the aquaculture tank tends to become acidic. When the water in the aquaculture tank becomes acidic, nitrification and other reactions become less likely to proceed, resulting in a poor breeding environment. In contrast, in this embodiment, by using the electrolytic treatment device configured as described above, it is possible to shift the pH value of the water in the aquaculture tank from the acidic side to the alkaline side without using chemicals. Furthermore, the oxygen and hydrogen generated by the electrolysis (electrolysis) of the water can be used in parallel to promote the nitrification and denitrification reactions described above. In this way, in this embodiment, not only the electrolyzed water obtained by electrolyzing the water in the aquaculture tank, but also the oxygen gas and hydrogen gas generated through this electrolyzed water can be utilized efficiently and without waste.

[0060] Second Embodiment Next, a closed circulation type land-based aquaculture purification system 110 according to a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, only the pipe from the acidic water storage tank 51 was connected to the anode tank 42 of the electrolytic tank 41, but the main feature of this embodiment is that the water W4 in the aquaculture tank 10 can also be selectively supplied to the anode tank 42. That is, when the liquid stored in the aquaculture tank 10 is freshwater rather than seawater, highly toxic substances such as hypochlorous acid are not necessarily produced even by electrolysis, and in such cases, the water in the aquaculture tank 10 can be selectively supplied to the anode tank and the cathode tank. Therefore, the following mainly describes the differences from the first embodiment, and elements having the same configuration or function as those in the first embodiment are given the same symbols as those in the first embodiment, and their descriptions will be omitted as appropriate (the same applies to the third embodiment described below).

[0061] 5, the closed-circulation land-based aquaculture purification system 110 in the second embodiment further includes a branch pipe 12 that branches off from the pipe 11 and is connected to the anode tank 42. As can be seen from the figure, an outbound pipe 52a extending from an acidic water storage tank 51 is connected to the branch pipe 12.

[0062] A known flow path switching valve is provided at the connection point between the pipe 11 and the branch pipe 12, so that water W4 from the aquaculture tank 10 can be divided and supplied to the anode tank 42 and the cathode tank. Therefore, the control device 70 can supply water W4 from the aquaculture tank 10 to at least one of the anode tank 42 and the cathode tank.

[0063] A well-known three-way valve is also provided at the connection point between the outgoing pipe 52a and the branch pipe 12, so that the water W4 from the aquaculture tank 10 and the water Wc from the acidic water storage tank 51 can be selectively supplied to the anode tank 42. Therefore, the control device 70 can supply at least one of the water W4 from the aquaculture tank 10 and the water Wc from the acidic water storage tank 51 to the anode tank 42.

[0064] According to the closed circulation land-based aquaculture purification system 110 including the land-based aquaculture electrolytic treatment device of the second embodiment described above, in addition to the effects of the first embodiment described above, water from the aquaculture tank can also be used to supply water to the anode tank, allowing for even more efficient and effective use of water resources.

[0065] Third Embodiment Next, a closed circulation type land-based aquaculture purification system 120 according to a third embodiment of the present invention will be described with reference to FIG. In each of the above embodiments, the water supplied from the aquaculture tank 10 is supplied to the electrolytic tank 41 without any particular filtering, but the main feature of this embodiment is that a foreign matter removal filter FT is provided in the piping 11.

[0066] 6, the closed-circulation land-based aquaculture purification system 120 in the third embodiment is configured to include a foreign matter removal filter FT that is provided in the piping 11 and removes foreign matter from the water W4 from the aquaculture tank 10, and the water that has passed through this foreign matter removal filter FT is received in at least the cathode tank 43. As such a foreign matter removal filter FT, a known filter material that can capture a portion of the fish excrement and feed contained in the water W4 of the aquaculture tank 10, such as a filtration membrane or a metal mesh filter, can be used.

[0067] In this embodiment, the foreign matter removal filter FT is installed inside the piping 11, but this is not limiting and the foreign matter removal filter FT may be installed in the outward piping 52a, the return piping 52b, the alkaline water piping 62a, the alkaline water delivery piping 62b, etc. Furthermore, these foreign matter removal filters FT can also be installed in the closed circulation type land-based aquaculture purification system 100 of the first embodiment and the closed circulation type land-based aquaculture purification system 110 of the second embodiment described above.

[0068] According to the closed circulation land-based aquaculture purification system 120 including the land-based aquaculture electrolytic treatment device of the third embodiment described above, in addition to the effects of the first embodiment described above, foreign matter contained in the water in the aquaculture tank is removed and electrolytic treatment is performed, so it is possible to suppress contamination of the electrolytic cell 41 and a decrease in the efficiency of the electrolytic treatment.

[0069] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0070] For example, in the above embodiment, electrolysis is performed when the pH value of the aquaculture tank falls below a predetermined value, but this is not limited to this form. For example, electrolysis may be performed periodically or irregularly after a predetermined time has elapsed, alkaline water may be supplied to the aquaculture tank, oxygen gas may be supplied to the nitrification device, or hydrogen gas may be supplied to the denitrification device.

[0071] Furthermore, in the above-described embodiment, if the polarity of the voltage applied to the electrolytic cell 41 is not changed, for example, foreign matter such as minerals will gradually adhere to the cathode side, and if this is left for a long period of time, there is a possibility that water will eventually stop flowing through the electrolytic cell 41. Therefore, as a countermeasure, the control device 70 may perform control to reverse the polarity of the voltage applied to the electrolytic cell 41 at any timing (for example, at predetermined intervals). The main parts of a closed circulation land-based aquaculture purification system 130 based on such a modified example are shown in Figure 7. In Figure 7, the explanation will focus on the parts that are different from the above-mentioned embodiment, and the explanation of the same components as the above-mentioned embodiment will be omitted or the same reference numbers will be used.

[0072] 7, the control device 70 in this modification periodically switches the cathode and anode in the electrolytic cell 41. As a specific device configuration, as shown in the figure, the electrolytic cell 41 can be installed as shown by applying three three-way valves V1 to V4, piping 11, an outflow pipe 52a, a return pipe 52b, an alkaline water piping 62a, an alkaline water delivery pipe 62b, and a switching flow path 90 (first switching flow path 91 to fourth switching flow path 94).

[0073] That is, as shown in the figure, a first three-way valve V1 is provided in an outgoing pipe 52a connecting the acidic water storage tank 51 to one of the electrolytic baths 41 (the bath located at the top in the figure), and a first switching flow path 91 is connected from the aquaculture tank 10 between the first three-way valve V1 and the electrolytic bath 41 via a second three-way valve V2. One end of a pipe 11 is connected to a second three-way valve V2 (side A in the figure) on the first switching flow path 91 connected to the aquaculture tank 10, and the other end of the pipe 11 is connected to the other bath of the electrolytic bath 41 (the bath located at the bottom in the figure). One end of a second switching flow path 92 is connected to the first three-way valve V1 (side B in the figure), and the other end of the second switching flow path 92 is connected to the above-mentioned pipe 11.

[0074] Furthermore, a water supply path is established from one of the electrolytic baths 41 to the acidic water storage tank 51 via a return pipe 52b, and a third three-way valve V3 is provided on this return pipe 52b. One end of a third switching flow path 93 is connected to the other of the electrolytic baths 41. The other end of the third switching flow path 93 is connected to the return pipe 52b between the third three-way valve V3 and the acidic water storage tank 51. A fourth three-way valve V4 is provided on this third switching flow path 93. One end of the alkaline water pipe 62a is connected to this fourth three-way valve V4 (side A in the figure), and the other end of the alkaline water pipe 62a is connected to the alkaline water storage tank 61. Furthermore, one end of the fourth switching flow path 94 is connected to the third three-way valve V3 (side B in the figure) described above, and the other end is connected to the alkaline water piping 62a between the fourth three-way valve V4 and the alkaline water storage tank 61.

[0075] For example, when one of the electrolytic baths 41 (upper side in the figure) is positive, the control device 70 controls the valves of the first three-way valve V1 to the fourth three-way valve V4 so that water enters through the C side and flows out through the A side. On the other hand, when the other of the electrolytic baths 41 (lower side in the figure) is positive, the control device 70 controls the valves of the first three-way valve V1 to the fourth three-way valve V4 so that water enters through the C side and flows out through the B side. This makes it possible to appropriately switch the piping configuration for water inflow and outflow of the electrolytic bath 41 and to switch the inlet and outlet channels of the liquid in response to polarity reversal of the electrolytic bath 41 via the multiple three-way valves.

[0076] The closed-loop land-based aquaculture purification system 130 based on the above-described modified example includes a three-way valve and a switching flow path that switch the inlet and outlet water paths to the electrolytic cell in response to polarity reversal (switching between anode and cathode) of the electrolytic cell. This makes it possible to solve the above-mentioned problems caused by minerals adhering to the cathode side of the electrolytic cell 41. [Industrial Applicability]

[0077] As described above, the closed circulation type land-based aquaculture purification system of the present invention is suitable for land-based aquaculture facilities that can utilize the products obtained by electrolysis treatment highly efficiently without waste. [Explanation of symbols]

[0078] 10 Aquaculture Tank 20 Nitrification equipment 30 Denitrification equipment 40 Electrolytic treatment equipment 50 Oxygen supply means 60 Hydrogen supply means 70 Control device 100, 110, 120, 130 Closed circulation land-based aquaculture purification system

Claims

1. aquaculture tanks for raising farmed seafood; a nitrification device that receives the pre-purification water containing ammonia components stored in the aquaculture tank and nitrifies the ammonia components using aerobic bacteria; a denitrification device that receives the primary purified water containing nitrate nitrogen generated by nitrification of the ammonia component and denitrifies the nitrate nitrogen using anaerobic bacteria; an electrolysis treatment device including an anode tank and a cathode tank separated by an ion-exchangeable diaphragm, the anode tank receiving water from the aquaculture tank and electrolyzing the water; an oxygen gas supply means for supplying the oxygen gas generated in the anode tank to the nitrification device; a hydrogen gas supply means for supplying the hydrogen gas generated in the cathode chamber to the denitrification device; a control means for controlling the electrolytic treatment device, the oxygen gas supply means, and the hydrogen gas supply means; A closed circulation land-based aquaculture purification system comprising:

2. Further provided is a foreign matter removal filter for removing foreign matter from the pre-purification tank water, The water from the aquaculture tank that has passed through the foreign matter removal filter is received in the cathode tank. The closed circulation land-based aquaculture purification system according to claim 1.

3. an acidic water storage tank for storing water different from the pre-purification water tank water sent to the cathode tank; a pair of outgoing and returning pipes connecting the acidic water storage tank and the anode tank; The water stored in the acidic water storage tank is sent to the anode tank through the outflow pipe, and the acidic water produced in the anode tank is returned to the acidic water storage tank through the return pipe. The closed circulation land-based aquaculture purification system according to claim 1 or 2.

4. The oxygen gas supply means the acidic water storage tank; an oxygen gas supply pipe that supplies the oxygen gas generated by gas-liquid separation in the acidic water storage tank to the nitrification device; The closed circulation land-based aquaculture purification system according to claim 3.

5. The hydrogen gas supply means an alkaline water storage tank that receives alkaline water produced by electrolysis in the cathode tank; a hydrogen gas supply pipe that supplies hydrogen gas generated by gas-liquid separation in the alkaline water storage tank to the denitrification device, The closed circulation land-based aquaculture purification system according to any one of claims 1 to 4.

6. a pH sensor for detecting the pH value of the aquaculture tank; An alkaline water supply pipe connecting the alkaline water storage tank and the aquaculture tank, the control means continues to supply the hydrogen gas to the denitrification device, while performing control to intermittently return the alkaline water to the aquaculture tank based on the pH value. The closed circulation land-based aquaculture purification system according to claim 5.

7. An electrolytic treatment device for land-based aquaculture used in the closed circulation land-based aquaculture purification system according to any one of claims 1 to 6, an electrolytic cell including an anode cell and a cathode cell separated by an ion-exchangeable diaphragm; an acidic water storage tank capable of storing the acidic water generated in the electrolytic cell; an alkaline water storage tank capable of storing alkaline water produced in the electrolytic cell; an oxygen supply means for supplying oxygen generated through the acidic water stored in the acidic water storage tank to the nitrification device; a hydrogen supply means for supplying hydrogen generated through the alkaline water stored in the alkaline water storage tank to the denitrification device; a control means for controlling the electrolytic cell, the oxygen supply means, and the hydrogen supply means; An electrolytic treatment device for land-based aquaculture, comprising:

Images