Circulation water treatment system for breeding aquatic life and aquatic life breeding method

Abstract

To provide a circulation water treatment system for breeding aquatic lives for efficiently decomposing ammonia or ammonium ions in water by a method where dependence on microbes is suppressed, and for efficiently removing pollution elements other than the ammonia or ammonium ions.SOLUTION: A circulation type treatment system 1 comprises: a removal part 5; an electrolysis part 13; and a residual chlorine removal part. The removal part 5 removes a solid included in breeding water in a first region where the breeding water sent from a breeding tank 3 is stored or is circulated. The electrolysis part 13 generates a chloric acid compound by electrolysis of the breeding water, in a second region where the breeding water passed through the first region is stored or is circulated, then causes the generated chloric acid compound to react with ammonia or ammonium ions in the breeding water. The residual chlorine removal part removes at least residual chlorine, in a third region where the breeding water passed through the second region is stored or is circulated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a circulating water treatment system used for aquaculture of aquatic organisms and a method for aquaculture of aquatic organisms.

Background Art

[0002] As an example of a system for aquaculture of aquatic organisms, a closed-circuit aquaculture system is known. The closed-circuit aquaculture system is a system that decomposes and purifies uneaten feed and manure excreted by organisms in a filtration tank and circulates water. In a general closed-circuit aquaculture system, a method that utilizes microorganisms for decomposition and purification of nitrogen compounds in the breeding water is the mainstream. As this type of technology, something like Patent Document 1 has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the aquaculture management system disclosed in Patent Document 1, ammonia is generated due to the metabolic activities of aquatic organisms in the water tank and the decomposition of organic substances such as uneaten feed. Therefore, the breeding water is circulated and passed through a filtration tank for biological filtration to decompose the ammonia and change it into less toxic nitric acid. The filtration tank holds nitrifying bacteria (microorganisms) that oxidize ammonia in water containing oxygen to change it into nitrous acid and then nitric acid.

[0005] However, when adopting a purification method using microorganisms as in Patent Document 1, there is a problem that the purification ability depends on the microorganisms.

[0006] One of the objectives of the present disclosure is to provide a technology that can more effectively decompose ammonia or ammonium ions in water in a method that reduces dependence on microorganisms in the cultivation of aquatic organisms, and can effectively remove pollution elements other than ammonia and ammonium ions.

Means for Solving the Problems

[0007] A circulating water treatment system for use in cultivating aquatic organisms, which is one of the present disclosures, is a circulating treatment system that treats the breeding water in a breeding tank that is a tank for cultivating aquatic organisms and contains saline breeding water outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, in a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, in a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chlorate compound by electrolyzing the breeding water and reacts the generated chlorate compound with ammonia or ammonium ions in the breeding water, in a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, and has, further has an ozone generation unit that generates ozone, the removal unit includes a foam separator that generates foam containing ozone generated by the ozone generation unit and adsorbs the solids contained in the breeding water in the first region to the foam, the residual chlorine removal unit removes residual ozone in the third region.

[0008] A circulating water treatment system for use in cultivating aquatic organisms, which is one of the present disclosures, is a circulating treatment system that treats the breeding water in a breeding tank that is a tank for cultivating aquatic organisms and contains saline breeding water outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the breeding water and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, having, Furthermore, in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, it has an ammonium ion sensor that detects ammonium ions contained in the breeding water.

[0009] A circulating water treatment system for aquaculture, which is one of the present disclosures, is a circulating treatment system that is a tank for culturing aquatic organisms and circulates the breeding water in the breeding tank containing breeding water containing salt after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the breeding water and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, having, The removal unit, a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam, a storage tank that stores the breeding water introduced from the region of the previous process of the removal unit, An introduction part for introducing the breeding water stored in the storage tank into the foam separator; A lead-out part for returning the breeding water that has passed through the foam separator to the storage tank; A discharge part for discharging the breeding water stored in the storage tank to a region in a subsequent process of the removal part; It is provided with.

[0010] A circulating water treatment system used for culturing aquatic organisms, which is one of the present disclosures, is a circulating treatment system that treats the breeding water in a breeding tank that is a tank for culturing aquatic organisms and contains breeding water containing salt outside the breeding tank, and then circulates the treated breeding water back to the breeding tank. In a first region where the breeding water sent from the breeding tank is stored or flows, a removal part for removing at least solids; In a second region where the breeding water that has passed through the first region is stored or flows, a chlorate compound is generated by electrolyzing the breeding water, and the generated chlorate compound is reacted with ammonia or ammonium ions in the breeding water. An electrolysis part; In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal part for removing at least residual chlorine; It has The removal part is provided with a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region onto the foam. After introducing the breeding water supplied from a region in a previous process of the removal part into the foam separator through an introduction path, it is passed through the foam separator and led out to a region in a subsequent process of the removal part that is different from the region of the introduction source where the inlet of the introduction path is arranged.

[0011] A method for culturing aquatic organisms, which is one of the present disclosures, A removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and a circulation type treatment system that is a tank for culturing aquatic organisms and circulates the breeding water in the breeding tank containing salt after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank is used. In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solids are removed by the removal unit. In the second region where the breeding water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the breeding water to generate a chloric acid compound, and the generated chloric acid compound is reacted with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, at least residual chlorine is removed by the residual chlorine removal unit. Furthermore, an ozone generation unit for generating ozone is provided in the circulation type treatment system. A foam separator is provided in the removal unit. The foam separator generates foam containing ozone generated by the ozone generation unit, and adsorbs the solids contained in the breeding water in the first region to the foam. The residual chlorine removal unit removes at least residual chlorine and residual ozone in the third region.

[0012] One method for culturing aquatic organisms according to the present disclosure is A removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and a circulation type treatment system that is a tank for culturing aquatic organisms and circulates the breeding water in the breeding tank containing salt after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank is used. In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solids are removed by the removal unit. In the second region where the breeding water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the breeding water to generate a chloric acid compound, and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, the residual chlorine removal unit removes at least residual chlorine. Furthermore, ammonium ions contained in the breeding water are detected by an ammonium ion sensor in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank.

[0013] One of the aquaculture methods of the present disclosure is a tank having a removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and using a circulation type treatment system that circulates the breeding water in the breeding tank, which is a tank for culturing aquatic organisms and contains saline breeding water, after treating the breeding water outside the breeding tank, and returning the treated breeding water to the breeding tank. In the first region where the breeding water sent from the breeding tank is stored or flows, the removal unit removes at least the solids. In the second region where the breeding water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the breeding water to generate a chloric acid compound, and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, the residual chlorine removal unit removes at least residual chlorine. Furthermore, in the removal unit, a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam, a storage tank for storing the breeding water, an introduction unit for introducing the breeding water to the foam separator, a lead-out unit for returning the breeding water to the storage tank, and a discharge unit for discharging the breeding water are provided. In the removal section, the breeding water introduced from the area of the previous process of the removal section is stored in the storage tank, the breeding water stored in the storage tank is introduced into the foam separator by the introduction section, the breeding water that has passed through the foam separator is returned to the storage tank by the discharge section, and the breeding water stored in the storage tank is discharged by the discharge section to the area of the subsequent process of the removal section.

[0014] One of the aquaculture methods of the present disclosure is a removal section for removing solids, an electrolysis section for performing electrolysis, and a residual chlorine removal section for removing at least residual chlorine, and a circulation type treatment system that circulates the breeding water in a breeding tank that is a tank for culturing aquatic organisms and contains salt-containing breeding water after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank is used. In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solids are removed by the removal section. In the second region where the breeding water that has passed through the first region is stored or flows, the breeding water is electrolyzed by the electrolysis section to generate a chloric acid compound, and the generated chloric acid compound is reacted with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, at least residual chlorine is removed by the residual chlorine removal section. Furthermore, in the removal section, a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam is provided. In the removal section, the breeding water supplied from the area of the previous process of the removal section is introduced into the foam separator through an introduction path, then passed through the foam separator, and led out to the area of the subsequent process of the removal section, which is different from the area of the introduction source where the inlet of the introduction path is arranged.

Advantages of the Invention

[0015] The technology according to the present disclosure can more effectively decompose ammonia or ammonium ions in water in a method with reduced dependence on microorganisms, and can effectively remove pollution elements other than ammonia and ammonium ions.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0017] Each of the following [1] to

[20] is an example of characteristic technology included in the present disclosure.

[0018] 〔1〕 A circulating treatment system that is a tank for culturing aquatic organisms and circulates the breeding water in a breeding tank containing saline breeding water after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the breeding water and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, having, Furthermore, it has an ozone generation unit that generates ozone, The removal unit includes a foam separator that generates foam containing ozone generated by the ozone generation unit and adsorbs the solids contained in the breeding water in the first region to the foam, The residual chlorine removal unit removes residual ozone in the third region A circulating water treatment system for culturing aquatic organisms.

[0019] In order to maintain the water quality of the breeding water in the aquaculture of aquatic organisms, it is necessary to remove solids such as feces, uneaten feed, and parasites excreted by the aquatic organisms and discharge them outside the aquaculture system. Furthermore, nitrogen compound components such as ammonia, nitrite, and nitrate need to be detoxified as much as possible. In this regard, the circulating water treatment system of the above [1] produces the following first actions and effects. First, the circulating water treatment system of the above [1] can remove the solids contained in the breeding water in the first region by the removal unit. Furthermore, the circulating water treatment system of the above [1] can decompose ammonia or ammonium ions by the electrolysis unit in the second region after passing through the first region. Moreover, by electrolyzing the breeding water containing salt, a chloric acid compound (for example, sodium hypochlorite) is generated, and this chloric acid compound can be reacted with ammonia or ammonium ions present in the breeding water and directly decomposed into nitrogen. Therefore, during the decomposition process, the generation of nitrite, nitrate, etc. can be surely suppressed. Moreover, since the circulating water treatment system of the above [1] performs electrolysis of the breeding water after removing the solids by the removal unit, it can surely suppress the solids from inhibiting the electrolysis and is easy to perform electrolysis well. Furthermore, since the circulating water treatment system of the above [1] can remove the residual chlorine in the third region by the residual chlorine removal unit, even if the chloric acid compound not used for the decomposition remains in the breeding water in the third region while enabling the decomposition of ammonia or ammonium ions by the generation of the chloric acid compound based on electrolysis, this chloric acid compound can be removed. Thus, in the circulating water treatment system of the above [1], it is surely possible to suppress the remaining of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also surely possible to suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of the purification and detoxification of the breeding water.

[0020] Furthermore, the circulating water treatment system of the above [1] also produces the following second actions and effects. This circulating water treatment system can generate foam containing ozone generated in the ozone generation unit by a foam separator, and can adsorb solids contained in the breeding water in the first region to the foam containing ozone. That is, in this circulating water treatment system, during the process of the breeding water in the first region passing through the foam separator, not only can solids be removed, but also sterilization and disinfection by ozone can be performed, and the effects of viruses, bacteria, and parasites, which are factors inhibiting the growth of aquatic organisms, can be reliably suppressed. Moreover, this circulating water treatment system can perform sterilization and disinfection more efficiently and effectively by a characteristic technique of causing ozone to act on the foam separator that removes solids.

[0021] 〔2〕 An ammonium ion sensor that detects ammonium ions contained in the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank The circulating water treatment system for culturing aquatic organisms according to 〔1〕.

[0022] The circulating water treatment system of 〔2〕 above can inspect ammonium ions contained in the breeding water in the fourth region after decomposing ammonia and ammonium ions in the second region. However, when detecting ammonium ions in breeding water containing salt with an ammonium ion sensor, there is a high possibility that interfering substances (substances that the ammonium ion sensor is likely to misidentify as ammonium ions) are contained in the breeding water, and if detection is performed with an ammonium ion sensor without taking any measures, there is a risk that ammonium ions cannot be accurately detected due to the influence of the interfering substances. However, since the circulating water treatment system of 〔2〕 above can remove solids in the first region, perform removal by activated carbon in the third region, and then detect ammonium ions in the fourth region, the concentration fluctuation of ammonium ions can be accurately detected in the breeding water from which the interfering substances have been effectively removed.

[0023] A circulation type treatment system for treating the breeding water in a breeding tank that is a tank for breeding aquatic organisms and contains saline breeding water outside the breeding tank and then circulating the treated breeding water back to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chlorate compound by electrolyzing the breeding water and reacts the generated chlorate compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, and having, Furthermore, in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, it has an ammonium ion sensor that detects ammonium ions contained in the breeding water A circulation type water treatment system for breeding aquatic organisms.

[0024] Even in the circulation type water treatment system of the above [3], the above-described first actions and effects occur. Therefore, even in the circulation type water treatment system of the above [3], it is possible to surely suppress the remaining solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to surely suppress the remaining nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0025] The circulation type water treatment system of the above [3] further produces the following actions and effects. This circulating water treatment system can inspect the ammonium ions contained in the breeding water in the fourth region after decomposing ammonia and ammonium ions in the second region. However, when detecting ammonium ions in the breeding water containing salts with an ammonium ion sensor, there is a high possibility that interfering substances (substances that the ammonium ion sensor is likely to misidentify as ammonium ions) are contained in the breeding water. If detection is performed with an ammonium ion sensor without taking any measures, there is a risk that ammonium ions cannot be accurately detected due to the influence of the interfering substances. However, the circulating water treatment system described in [3] above can remove solid matter in the first region, remove residual chlorine by the residual chlorine removal unit in the third region, and then detect ammonium ions in the fourth region. Therefore, in the breeding water from which interfering substances have been effectively removed, the concentration fluctuations of ammonium ions can be accurately detected.

[0026] 〔4〕 The removal unit a storage tank for storing the breeding water introduced from the region of the previous process of the removal unit, an introduction unit for introducing the breeding water stored in the storage tank into the foam separator, a derivation unit for returning the breeding water that has passed through the foam separator to the storage tank, a discharge unit for discharging the breeding water stored in the storage tank to the region of the subsequent process of the removal unit, and comprises The circulating water treatment system for aquaculture use according to [1] or [2].

[0027] When the circulating water treatment system described in [4] above removes solid matter by the removal unit, the breeding water introduced from the region of the previous process is temporarily stored in the storage tank, introduced from this storage tank into the foam separator to remove solid matter, and then can be operated to return to the foam separator. If the removal unit is configured in this way, the storage tank serves as a buffer in the process of circulating the breeding water, and even if the introduction speed into the foam separator and the derivation speed from the foam separator are different from the circulating speeds of other processes, the water level is less likely to fluctuate significantly in other processes.

[0028] A circulating water treatment system for culturing aquatic organisms, which circulates the breeding water in a breeding tank containing breeding water with salt content after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chlorate compound by electrolyzing the breeding water and reacts the generated chlorate compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, having The removal unit A foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region onto the foam, A storage tank that stores the breeding water introduced from the region before the previous process of the removal unit, An introduction unit that introduces the breeding water stored in the storage tank into the foam separator, A derivation unit that returns the breeding water that has passed through the foam separator to the storage tank, A discharge unit that discharges the breeding water stored in the storage tank to the region after the subsequent process of the removal unit, comprising A circulating water treatment system for culturing aquatic organisms.

[0029] Even in the circulating water treatment system of the above [5], the above-described first actions and effects occur. Therefore, even in the circulating water treatment system of the above [5], it is possible to surely suppress the remaining of solids such as feces and residual feed in the breeding water after passing through the third region, and it is also possible to surely suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0030] The circulating water treatment system of the above [5] further produces the following actions and effects. When this circulating water treatment system removes solids by the removal unit, the breeding water introduced from the area of the previous process is temporarily stored in a storage tank, then introduced from this storage tank into a foam separator to remove solids, and then can be operated to return to the foam separator. If the removal unit is configured in this way, the storage tank serves as a buffer in the process of circulating the breeding water, and even if the introduction speed into the foam separator and the derivation speed from the foam separator are different from the circulation speed of other processes, the water level in other processes is less likely to fluctuate significantly.

[0031] 〔6〕 After introducing the breeding water supplied from the area of the previous process of the removal unit into the foam separator through an introduction path, the removal unit passes the breeding water through the foam separator and then discharges it to the area of the subsequent process of the removal unit, which is different from the area of the source where the inlet of the introduction path is arranged. The circulating water treatment system for aquaculture according to 〔1〕 or 〔2〕.

[0032] When the circulating water treatment system of the above 〔6〕 removes solids by the removal unit, after introducing the breeding water supplied from the area of the previous process into the foam separator through an introduction path, the breeding water is passed through the foam separator and then discharged to the area of the subsequent process, which is different from the area of the source where the inlet of the introduction path is arranged. Therefore, the circulating breeding water can pass through the foam separator more reliably, and the effect of removing solids and the effects of sterilization and disinfection by ozone can be further enhanced.

[0033] 〔7〕 A circulating treatment system that circulates the breeding water in a breeding tank for cultivating aquatic organisms and containing saline breeding water after treating the breeding water outside the breeding tank and then returning the treated breeding water to the breeding tank, In a first area where the breeding water sent from the breeding tank is stored or flows, at least a removal unit for removing solids, In a second area where the breeding water that has passed through the first area is stored or flows, an electrolysis unit that generates a chlorate compound by electrolyzing the breeding water and reacts the generated chlorate compound with ammonia or ammonium ions in the breeding water. In a third region where the breeding water that has passed through the second region is stored or flows, there is a residual chlorine removal unit that removes at least residual chlorine. It has The removal unit includes a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region onto the foam. After introducing the breeding water supplied from the region in the previous process of the removal unit into the foam separator through an introduction path, it is passed through the foam separator and then led to a region in the subsequent process of the removal unit that is different from the region of the introduction source where the inlet of the introduction path is arranged. A circulating water treatment system used for aquaculture of aquatic organisms.

[0034] Even in the circulating water treatment system of the above [7], the above-mentioned first actions and effects occur. Therefore, even in the circulating water treatment system of the above [7], it is possible to surely suppress the remaining of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to surely suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0035] Furthermore, the circulating water treatment system of the above [7] further exhibits the following actions and effects. When the circulating water treatment system of the above [7] removes solids by the removal unit, after introducing the breeding water supplied from the region in the previous process into the foam separator through an introduction path, it is passed through the foam separator and then led to a region in the subsequent process that is different from the region of the introduction source where the inlet of the introduction path is arranged. Therefore, the circulating breeding water can be more surely passed through the foam separator, and the effect of removing solids and the effects of sterilization and disinfection by ozone can be further enhanced.

[0036] 〔8〕 It includes a control unit that controls the electrolysis of the electrolysis unit based on the measurement result of the ammonium ion sensor. The circulating water treatment system used for aquaculture of aquatic organisms according to [2] or [3].

[0037] The above-described [8] circulating water treatment system can accurately measure the fluctuation of the ammonium ion concentration in the breeding water from which the interfering substances have been effectively removed, and control the electrolysis using this measurement result. Therefore, this circulating water treatment system can perform electrolysis in accordance with the degree of ammonium ions present in the fourth region after passing through the residual chlorine removal section.

[0038] 〔9〕 It includes a residual chlorine sensor that detects the residual chlorine contained in the breeding water in the region where the breeding water that has passed through the second region is stored or flows before returning to the breeding tank. The control unit controls the electrolysis of the electrolysis unit based on the measurement results of the ammonium ion sensor and the measurement results of the residual chlorine sensor. The circulating water treatment system for aquaculture of aquatic organisms according to [8].

[0039] The above-described [9] circulating water treatment system can control electrolysis in accordance with the degree of residual chlorine contained in the breeding water after passing through the second region where electrolysis is performed, and the degree of ammonium ions present in the fourth region after passing through the residual chlorine removal section.

[0040] 〔10〕 It includes a residual chlorine sensor that detects the residual chlorine contained in the breeding water in the region where the breeding water that has passed through the second region is stored or flows before returning to the breeding tank. The circulating water treatment system for aquaculture of aquatic organisms according to any one of [1] to [9].

[0041] The above-described

[10] circulating water treatment system can inspect the degree of residual chlorine contained in the breeding water after passing through the second region where electrolysis is performed, and the inspection results can be used for characteristic control and treatment.

[0042] As controls and processes applying the configuration of the above

[10] , it may be a control for performing electrolysis according to the degree of residual chlorine detected by the residual chlorine sensor, or it may be a control for removing or neutralizing residual chlorine when the residual chlorine detected by the residual chlorine sensor exceeds a predetermined value. Based on the degree of residual chlorine, the degree of ammonia or ammonium ions may be indirectly grasped, or control based on that degree may be performed. In any case, by inspecting the degree of residual chlorine contained in the breeding water after the residual chlorine sensor has passed through the second region, the control and process can be further advanced.

[0043] 〔11〕 A residual chlorine sensor that detects the residual chlorine contained in the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, When a predetermined measurement result is obtained by the residual chlorine sensor, a treatment unit that removes residual chlorine from the breeding water in the fourth region or stops returning the breeding water in the fourth region to the breeding tank, A circulating water treatment system for aquaculture of aquatic organisms according to any one of [1] to [9], which has the above.

[0044] Depending on the degree of residual chlorine contained in the breeding water after passing through the second region, the circulating water treatment system of the above

[11] can remove residual chlorine from the breeding water in the fourth region or stop returning the breeding water in the fourth region to the breeding tank, and can suppress the risk that the breeding water containing residual chlorine is returned to the breeding tank as it is.

[0045] 〔12〕 The treatment unit includes a neutralizing agent supply unit that supplies a neutralizing agent that causes a neutralization reaction with residual chlorine to the breeding water before returning to the breeding tank when the detection value of the residual chlorine sensor exceeds a predetermined value A circulating water treatment system for aquaculture of aquatic organisms according to

[10] or

[11] .

[0046] When the detection value of the residual chlorine sensor exceeds a predetermined value, the circulating water treatment system described above can supply a neutralizing agent that causes a neutralization reaction with the residual chlorine in the breeding water before returning to the breeding tank. Therefore, when the breeding water in the fourth region contains a certain amount of residual chlorine, the residual chlorine contained in the breeding water can be neutralized and reliably reduced.

[0047] 〔13〕 An electrolysis tank in which the breeding water that has passed through the removal unit is stored or flows, The breeding water that has passed through the electrolysis tank is stored or flows, and a reaction tank that secures a reaction time between the chlorate compound generated in the electrolysis tank and ammonia or ammonium ions contained in the breeding water, A residual chlorine removal tank in which the breeding water that has passed through the reaction tank is stored or flows, A standby tank in which the breeding water that has passed through the residual chlorine removal tank is stored or flows, and the water quality of the breeding water before returning to the breeding tank is inspected, A first residual chlorine sensor that detects the residual chlorine contained in the breeding water from when it passes through the electrolysis tank until it flows into the residual chlorine removal tank, A second residual chlorine sensor that detects the residual chlorine contained in the breeding water in the standby tank, A control unit that controls the electrolysis of the electrolysis unit based on the measurement results of the ammonium ion sensor and the measurement results of the first residual chlorine sensor, When a predetermined measurement result is obtained by the second residual chlorine sensor, a treatment unit that stops removing residual chlorine from the breeding water in the fourth region or stops returning the breeding water in the fourth region to the breeding tank, having The second region includes at least the internal region of the electrolysis tank, The third region includes at least the internal region of the residual chlorine removal tank, The fourth region includes at least the internal region of the standby tank The circulating water treatment system for aquaculture of aquatic organisms according to (2) or (3).

[0048] The above-described [

[13] ] circulating water treatment system generates a chloric acid compound (e.g., sodium hypochlorite) in an electrolytic cell to decompose ammonia or ammonium ions. However, ammonia or ammonium ions that cannot be completely decomposed in the electrolytic cell can react with the chloric acid compound in the reaction tank. Therefore, even if there is a certain degree of fluidity in the electrolytic cell and ammonia or ammonium ions are discharged from the electrolytic cell without complete reaction, the reaction can be promoted in the reaction tank. This circulating water treatment system can thus more surely react ammonia or ammonium ions. On the other hand, a standby tank is secured in the subsequent process of the residual chlorine removal tank, and ammonium ions in the breeding water before returning to the breeding tank can be inspected by an ammonium ion sensor and residual chlorine can be inspected by a second residual chlorine sensor. Furthermore, this circulating water treatment system can also inspect the residual chlorine contained in the breeding water from the time it passes through the electrolytic cell until it flows into the residual chlorine removal tank by the first residual chlorine sensor. And this circulating water treatment system can use the measurement results of the two types of residual chlorine sensors for different purposes, control the electrolysis using the measurement results of the ammonium ion sensor and the first residual chlorine sensor, and when the measurement result of the second residual chlorine sensor (the degree of residual chlorine contained in the breeding water after passing through the second region) is a predetermined measurement result, it is possible to remove the residual chlorine from the breeding water in the fourth region or stop returning the breeding water in the fourth region to the breeding tank, thereby suppressing the risk that the breeding water containing residual chlorine is directly returned to the breeding tank.

[0049] 〔14〕 A pH sensor that measures the pH of the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, A pH adjustment unit that adjusts the pH of the fourth region or the region from the fourth region to the breeding tank based on the measurement result of the pH sensor, having The circulating water treatment system for aquaculture use according to any one of 〔1〕 to 〔13〕.

[0050] The above-mentioned

[14] circulating water treatment system decomposes ammonia or ammonium ions based on electrolysis in the electrolysis unit, then removes residual chlorine by the residual chlorine removal unit, and can inspect the pH of the breeding water before returning it to the breeding tank using a pH sensor. In the method of removing residual chlorine by the residual chlorine removal unit in the post-process of the electrolysis unit as described above, there is a concern that the pH of the breeding water after passing through the residual chlorine removal unit may vary. Therefore, as in the circulating water treatment system of the above

[14] , if the pH of the breeding water is inspected using a pH sensor in the fourth region downstream of the residual chlorine removal unit and the pH is adjusted based on the measurement result, even if the pH of the breeding water entering the fourth region varies, it is easy to appropriately adjust the pH based on a highly accurate measurement result.

[0051]

[15] A removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and a breeding tank for cultivating aquatic organisms and storing breeding water containing salt, and using a circulating treatment system that circulates the treated breeding water back to the breeding tank after treating the breeding water in the breeding tank outside the breeding tank. By the removal unit, at least the solids are removed in the first region where the breeding water sent from the breeding tank is stored or flows. By the electrolysis unit, the breeding water is electrolyzed in the second region where the breeding water that has passed through the first region is stored or flows to generate a chlorate compound, and the generated chlorate compound is reacted with ammonia or ammonium ions in the breeding water. By the residual chlorine removal unit, at least residual chlorine is removed in the third region where the breeding water that has passed through the second region is stored or flows. Further, an ozone generation unit for generating ozone is provided in the circulating treatment system. In the removal unit, a foam separator is provided. By the foam separator, foam containing ozone generated by the ozone generation unit is generated, and the solids contained in the breeding water in the first region are adsorbed onto the foam. The residual chlorine removal unit removes at least residual chlorine and residual ozone in the third region. A method for culturing aquatic organisms.

[0052] Even in the method for culturing aquatic organisms described in

[15] above, the above-described first actions and effects occur. Therefore, even in the method for culturing aquatic organisms described in

[15] above, it is possible to surely suppress the remaining of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to surely suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0053] Furthermore, the culturing method described in

[15] above further produces the following actions and effects. The culturing method described in

[15] above generates foam containing ozone generated in the ozone generation unit by a foam separator, and adsorbs solids contained in the breeding water in the first region to the foam containing ozone. That is, in this culturing method, in the process of the breeding water in the first region passing through the foam separator, not only the removal of solids but also sterilization and disinfection by ozone can be performed, and the effects of viruses, bacteria, and parasites, which are factors inhibiting the growth of aquatic organisms, can be surely suppressed. Moreover, due to the characteristic technique of applying ozone to the foam separator for removing solids, sterilization and disinfection can be performed more efficiently and effectively.

[0054] 〔16〕 In a fourth region where the breeding water passing through the third region is stored or flows before returning to the breeding tank, ammonium ions contained in the breeding water are detected by an ammonium ion sensor. The method for culturing aquatic organisms according to

[15] .

[0055] In the aquaculture method described in

[16] above, it is possible to inspect the ammonium ions contained in the breeding water in the fourth region after decomposing ammonia and ammonium ions in the second region. However, when detecting ammonium ions in breeding water containing salt using an ammonium ion sensor, there is a high possibility that interfering substances (substances that the ammonium ion sensor is likely to misidentify as ammonium ions) are contained in the breeding water. If detection is performed using an ammonium ion sensor without taking any measures, there is a risk that fluctuations in the ammonium ion concentration cannot be accurately detected due to the influence of the interfering substances. However, in the aquaculture method described in

[16] above, solid matter is removed in the first region, and after removal by the residual chlorine removal unit in the third region, ammonium ions can be detected in the fourth region. Therefore, in the breeding water from which interfering substances have been effectively removed, fluctuations in the ammonium ion concentration can be accurately detected.

[0056] 〔17〕 A treatment system that has a removal unit for removing solid matter, an electrolysis unit for performing electrolysis, and at least a residual chlorine removal unit for removing residual chlorine, and that circulates the breeding water in a breeding tank that has an aquaculture tank for culturing aquatic organisms and contains breeding water containing salt, after treating the breeding water outside the breeding tank, and returning the treated breeding water to the breeding tank. By the removal unit, at least the solid matter is removed in the first region where the breeding water sent from the breeding tank is stored or flows. By the electrolysis unit, the breeding water is electrolyzed in the second region where the breeding water that has passed through the first region is stored or flows to generate a chlorate compound, and the generated chlorate compound is reacted with ammonia or ammonium ions in the breeding water. By the residual chlorine removal unit, at least residual chlorine is removed in the third region where the breeding water that has passed through the second region is stored or flows. Furthermore, ammonium ions contained in the breeding water are detected by an ammonium ion sensor in the fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank. Aquaculture method for aquatic organisms.

[0057] Even in the method for culturing aquatic organisms described in

[17] above, the above-described first actions and effects are produced. Therefore, even in the method for culturing aquatic organisms described in

[17] above, it is possible to reliably suppress the remaining of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to reliably suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0058] The culturing method described in

[17] above further produces the following actions and effects. This culturing method can inspect ammonium ions contained in the breeding water in the fourth region after decomposing ammonia and ammonium ions in the second region. However, when detecting ammonium ions in breeding water containing salt with an ammonium ion sensor, there is a high possibility that interfering substances (substances that the ammonium ion sensor is likely to misidentify as ammonium ions) are contained in the breeding water. If detection is performed with an ammonium ion sensor without taking any measures, there is a risk that ammonium ions cannot be accurately detected due to the influence of interfering substances. However, since the culturing method described in

[17] above can remove solids in the first region, perform removal by the residual chlorine removal unit in the third region, and then detect ammonium ions in the fourth region, it is possible to accurately detect fluctuations in the concentration of ammonium ions in the breeding water in which interfering substances have been effectively removed.

[0059] 〔18〕 A circulation type treatment system having a removal unit for removing solids, an electrolysis unit for performing electrolysis, and at least a residual chlorine removal unit for removing residual chlorine, and using the treatment system to circulate the breeding water in a breeding tank that is a tank for culturing aquatic organisms and contains salt-containing breeding water after treating the breeding water outside the breeding tank and returning the treated breeding water to the breeding tank. In the first region where the breeding water sent from the breeding tank is stored or flows by the removal unit, at least the solids are removed. In the second region where the breeding water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the breeding water to generate a chloric acid compound, and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, the residual chlorine removal unit removes at least residual chlorine. Furthermore, in the removal unit, a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam, a storage tank that stores the breeding water, an introduction unit that introduces the breeding water to the foam separator, a discharge unit that returns the breeding water to the storage tank, and a discharge unit that discharges the breeding water are provided. In the removal unit, the breeding water introduced from the region of the previous process of the removal unit is stored in the storage tank, the breeding water stored in the storage tank is introduced into the foam separator by the introduction unit, the breeding water that has passed through the foam separator is returned to the storage tank by the discharge unit, and the breeding water stored in the storage tank is discharged to the region of the subsequent process of the removal unit by the discharge unit. Aquatic organism cultivation method.

[0060] Even in the aquatic organism cultivation method of the above

[18] , the above-described first actions and effects occur. Therefore, even in the aquatic organism cultivation method of the above

[18] , it is possible to surely suppress the remaining of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to surely suppress the remaining of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0061] The cultivation method of the above

[18] further produces the following actions and effects. When removing solids by the removal unit, the breeding water introduced from the area of the previous process is temporarily stored in a storage tank, and after being introduced into a foam separator from this storage tank to remove solids, it can be operated to return to the foam separator. If the removal unit is configured in this way, the storage tank serves as a buffer in the process of circulating the breeding water, and even if the introduction speed into the foam separator or the derivation speed from the foam separator is different from the circulation speed of other processes, the water level in other processes is less likely to fluctuate significantly.

[0062] 〔19〕 A circulating treatment system having a removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and circulating the breeding water in a breeding tank that is a tank for cultivating aquatic organisms and contains saline breeding water after treating the breeding water outside the breeding tank and returning the treated breeding water to the breeding tank. In the first region where the breeding water sent from the breeding tank is stored or flows by the removal unit, at least the solids are removed. In the second region where the breeding water that has passed through the first region is stored or flows by the electrolysis unit, the breeding water is electrolyzed to generate a chlorate compound, and the generated chlorate compound is reacted with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows by the residual chlorine removal unit, at least residual chlorine is removed. Furthermore, in the removal unit, a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam is provided. In the removal unit, after introducing the breeding water supplied from the area of the previous process of the removal unit into the foam separator through an introduction path, it is passed through the foam separator and led out to the area of the subsequent process of the removal unit that is different from the area of the introduction source where the inlet of the introduction path is arranged. A method for cultivating aquatic organisms.

[0063] Even in the method for culturing aquatic organisms described in

[19] above, the above-described first actions and effects are produced. Therefore, even in the method for culturing aquatic organisms described in

[19] above, it is possible to surely suppress the residue of solids such as feces and uneaten feed in the breeding water after passing through the third region, and it is also possible to surely suppress the residue of nitrogen compound components such as ammonia, nitrite, and nitrate. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0064] In the culturing method described in

[19] above, when removing solids by the removing unit, the breeding water supplied from the region of the previous step is introduced into the foam separator through the introduction path, then passed through the foam separator, and led out to the region of the subsequent step different from the region of the introduction source where the inlet of the introduction path is arranged. Therefore, the circulating breeding water can pass through the foam separator more surely, and the effect of removing solids and the effects of sterilization and disinfection by ozone can be further enhanced.

[0065] 〔20〕 Controlling the electrolysis of the electrolysis unit based on the measurement result of the ammonium ion sensor by the control unit The method for culturing aquatic organisms according to

[16] or

[17] .

[0066] The culturing method described in

[20] above can accurately measure the fluctuation of the concentration of ammonium ions in the breeding water from which interfering substances have been effectively removed, and then control the electrolysis using this measurement result. Therefore, in this culturing method, electrolysis can be performed in accordance with the degree of ammonium ions present in the fourth region after passing through the vicinity of the residual chlorine removal unit.

[0067] <First Embodiment> 1. Outline of the Circulating Water Treatment System 1 Used for Culturing Aquatic Organisms The circulating water treatment system 1 illustrated in Fig. 1 is a system used for aquaculture. The circulating water treatment system 1 is configured as a closed-loop aquaculture system that circulates the breeding water in the breeding tank 3 containing the breeding water with salt content outside the breeding tank 3 and then returns the treated breeding water to the breeding tank 3, and is designed to recycle water. When culturing aquatic organisms in the breeding tank 3, the circulating water treatment system 1 operates to decompose and purify the residual feed and feces discharged by organisms remaining in the breeding water during the breeding in the breeding tank 3 in the process from the breeding tank 3 until the water is circulated back to the breeding tank 3 again while continuously breeding the aquatic organisms inside the breeding tank 3.

[0068] As shown in Fig. 1, the circulating water treatment system 1 mainly includes a breeding tank 3, a removal unit 5, an electrolysis tank 11, a reaction tank 15, a filtration tank 17, an activated carbon tank 21, a standby tank (water quality adjustment tank) 25, a treatment unit 31, etc. Furthermore, the circulating water treatment system 1 also includes a temperature control machine 35, a filter 37, etc. The electrical configuration of the circulating water treatment system 1 is, for example, as shown in Fig. 2. The types of aquatic organisms that can be bred inside the breeding tank 3 are various. For example, fish, crustaceans, shellfish, etc. are cited as suitable examples, and other types (for example, squid, octopus, etc.) may also be used.

[0069] 2. Configuration and Operation of Each Part (Breeding Tank) The breeding tank 3 shown in Fig. 1 is a tank for breeding and culturing aquatic organisms. Inside the breeding tank 3, breeding water containing salt such as artificial seawater or natural seawater is stored, and aquatic organisms such as fish and shellfish are bred in this breeding water. In the example of Fig. 1, a plurality (for example, four) of breeding tanks 3 are provided, and the breeding water in these breeding tanks 3 is guided to be collected by the filter 37, filtered by the filter 37, and internally circulated so as to be distributed from the filter 37 to the plurality of breeding tanks 3. The water temperature of the breeding water in the breeding tank 3 is adjusted to a desired set temperature by the temperature control machine 35. In the example of Fig. 1, a plurality of breeding tanks 3 are used, but it may also be composed of a single water tank.

[0070] (Removal Unit) The removal unit 5 shown in Fig. 1 functions to remove at least solids in the first region where the breeding water sent from the breeding tank 3 is stored or flows. The breeding water in the breeding tank 3 is guided to the removal unit 5 through the flow path 41. As shown in Fig. 3, the removal unit 5 includes an ozone generator 9, a foam separator 7, a storage tank 60, an introduction section 62, a discharge section 64, and a drainage section 66. In Fig. 3 and the like, the symbol W conceptually indicates a part of the circulating breeding water.

[0071] The storage tank 60 is a tank for storing the breeding water introduced from the region of the previous process of the removal unit 5. In the example of Fig. 1, the region of the previous process of the removal unit 5 is the region inside the breeding tank 3. The method of flowing the breeding water from the breeding tank 3 to the storage tank 60 may be a method of flowing it using a pump or a method of flowing it using a height difference.

[0072] The ozone generator 9 corresponds to an example of an ozone generation section, generates ozone by a known method, for example, and supplies the generated ozone to the foam separator 7. The method of introducing the ozone from the ozone generator 9 into the foam separator 7 is not particularly limited, and examples include a method of supplying the ozone generated by the ozone generator 9 from the inlet for introducing air provided in the foam generation section in a known foam separator. The foam separator 7 operates to generate foam containing the ozone generated by the ozone generator 9 and adsorb the solids contained in the breeding water in the first region where the breeding water sent from the breeding tank 3 is stored or flows onto the foam. In the example of Fig. 3, the first region is the internal region of the storage tank 60.

[0073] The introduction section 62 is a flow path for introducing the breeding water stored in the storage tank 60 into the inside of the foam separator 7. The discharge section 64 is a flow path for returning the breeding water that has passed through the foam separator 7 from the foam separator 7 to the storage tank 60. The drainage section 66 has a flow path for discharging the breeding water stored in the storage tank 60 to the region of the subsequent process of the removal unit 5. In the examples of Figs. 1 and 3, the region of the subsequent process of the removal unit 5 is the region inside the electrolysis tank 11.

[0074] In the removal section 5, solids such as feces, uneaten feed, etc. contained in the breeding water introduced into the foam separator 7, removal proteins of metabolites of seafood, bacteria, viruses, parasites, etc. are attached to the fine bubbles generated in the foam separator 7 and removed from the breeding water. Moreover, since the bubbles generated in the foam separator 7 are bubbles containing ozone, they have a high sterilizing power, and this sterilizing power also acts on the breeding water that passes through the foam separator 7 and returns to the outlet section 64. By such an operation, it is surely suppressed that dirt flows out to the electrolytic cell 11 in the subsequent process, and it is surely suppressed that the dirt obstructs the electrolysis of the electrolytic cell 11.

[0075] In the example of FIG. 3, the flow path 41 communicates near the bottom 60A of the storage tank 60, and the breeding water from the flow path 41 is supplied into the storage tank 60 from a position near the lower end on the side portion of the storage tank 60. The inlet (the inlet for taking in the breeding water) in the introduction section 62 is arranged at a position closer to the bottom 60A in the storage tank 60, facilitating the intake of the breeding water immediately after being introduced into the storage tank 60 from the flow path 41. On the other hand, the breeding water that has passed through the foam separator 7 is led out by the outlet section 64 to a position closer to the discharge section 66 than the flow path 41. The outlet (the outlet for discharging the breeding water) of the outlet section 64 is arranged at a position closer to the water surface W1 than the bottom 60A of the storage tank 60. The discharge section 66 is configured as a flow path for flowing the breeding water in the storage tank 60 toward the outside of the storage tank 60. The discharge section 66 is configured not to guide the water located below a predetermined first height in the storage tank 60 to the outside of the storage tank 60, but to guide the water located above the first height to the outside of the storage tank 60. The first height is the height of the lower end of the boundary with the storage tank 60 on the inner wall surface of the flow path of the discharge section 66. When the water surface of the breeding water in the storage tank 60 is higher than this first height, the water in the region higher than the first height is discharged from the discharge section 66.

[0076] The configuration of the removal unit 5 shown in FIG. 3 can be more specifically configured as shown in FIG. 4. In the specific example of FIG. 4, a foam generation part 8 and a foam separation tank 7A are provided in the foam separator 7. Further, the inlet (water intake) of the introduction part 62 configured as a pipe is arranged near the bottom of the storage tank 60 and close to the flow path 45 in the storage tank 60, and a filter 61 is provided so as to cover this inlet. Among the breeding water stored in the storage tank 60, the breeding water that can pass through the filter 61 is introduced from the introduction part 62 into the foam separator 7. The filter 61 is configured to block the passage of objects with a large particle size and allow the passage of objects with a small particle size, and is, for example, configured in a net shape. Although not shown in FIG. 4, a pump for flowing the breeding water so as to flow into the foam separator 7 through the introduction part 62 may be provided.

[0077] In the configuration of FIG. 4, the foam generation part 8 injects a gas containing ozone generated by the ozone generator 9 into the breeding water flowing in from the introduction part 62, and contains bubbles of the gas containing ozone in the breeding water passing through the foam generation part 8. The breeding water that has passed through the foam generation part 8 flows into the foam separation tank 7A through the introduction part 63 configured as a pipe as the breeding water containing bubbles containing ozone. In the foam separation tank 7A, the bubbles to which solids adhere are separated so as to gather near the water surface, and the gathered bubbles are discharged to the outside of the foam separation tank 7A through the discharge path 65. On the other hand, the breeding water on the lower side of the foam separation tank 7A is discharged near the water surface of the storage tank 60 by the lead-out part 64 configured as a pipe. The outlet (discharge port) of the lead-out part 64 is arranged so that a vortex is generated in a certain direction in the breeding water stored in the storage tank 60. The discharge part 66 configured as a discharge flow path is arranged near the water surface of the storage tank 60, and the supernatant of the breeding water stored in the storage tank 60 is discharged from the discharge part 66.

[0078] (Electrolysis cell) The electrolysis tank 11 shown in Fig. 5 is a tank for performing electrolysis, and is a tank in which the breeding water that has passed through the removal unit 5 is stored or flows. The internal region of the electrolysis tank 11 is a region in which the breeding water that has passed through the above-described first region (in the example of Fig. 3, the region in the storage tank 60) is stored or flows, and corresponds to an example of the second region. An electrolysis unit 13 is provided in the electrolysis tank 11. In the second region, the electrolysis unit 13 generates a chloric acid compound (for example, sodium hypochlorite) by electrolyzing the breeding water, and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water to decompose the ammonia or ammonium ions. Further, in the electrolysis tank 11, since the chloric acid compound is generated by the electrolysis unit 13, sterilization, deodorization, and decolorization of the breeding water can be performed.

[0079] In the electrolysis tank 11, electrolysis shown by the following formula (1) is performed. 2NaCl + 3H2O → NaClO + NaCl + 2H2O + H2↑ ··· (1)

[0080] Then, the decomposition of ammonia or the decomposition of ammonium ions is performed by the chemical reactions shown by the following formulas (2) and (3). 2NH3 + 3NaClO → N2↑ + 3NaCl + 3H2O ··· (2) 2NH4 + + 3NaClO → N2↑ + 3H2O + 3NaCl + 2H + ··· (3)

[0081] In the electrolysis tank 11 shown in Fig. 5, the internal region of the electrolysis tank 11 is a "region" where the electrode unit 55 is disposed and electrolysis is performed. An electrolysis unit 13 is provided in the electrolysis tank 11. The electrolysis unit 13 includes an electrode unit 55 having a first electrode 55A and a second electrode 55B disposed in the above "region" (second region), and a voltage application unit 51 that applies a voltage between the electrodes of the first electrode 55A and the second electrode 55B.

[0082] The voltage application unit 51 includes a control device 52 and a drive circuit 53. The control device 52 is an information processing device having an information processing unit, a storage unit, a communication unit, etc., and is a device capable of performing various controls and various calculations. The drive circuit 53 is a circuit that applies a voltage between the electrodes of the first electrode 55A and the second electrode 55B in response to a command from the control device 52.

[0083] The electrode unit 55 includes an electrode holding part 55C that holds the first electrode 55A and the second electrode 55B, and the first electrode 55A, the second electrode 55B, and the electrode holding part 55C are integrally formed. The integrally formed electrode unit 55 is attached to and detached from the electrolytic cell 11. The configuration for making the electrode unit 55 detachable from the electrolytic cell 11 is not particularly limited. For example, when mounting, the electrode holding part 55C is placed on the mounting table provided on the electrolytic cell 11, and when removing, the electrode holding part 55C is detached from the mounting table. In the example of FIG. 5, a plurality of first electrodes 55A and a plurality of second electrodes 55B are provided, and both the plurality of first electrodes 55A and the plurality of second electrodes 55B are formed in a plate shape from a metal material. In the electrode unit 55, the first electrode 55A and the second electrode 55B are alternately arranged at intervals. The plurality of first electrodes 55A are configured to be short-circuited to each other and are electrically connected to the first terminal of the drive circuit 53 via a conductive path 54A. The plurality of second electrodes 55B are configured to be short-circuited to each other and are electrically connected to the second terminal of the drive circuit 53 via a conductive path 54B. In the example of FIG. 5, the first electrode 55A and the second electrode 55B are alternately arranged at intervals.

[0084] The electrodes used in the electrolysis cell 11 are preferably made of a metal material that is not corroded by seawater and has a high chlorine acid compound generation efficiency. For example, an electrode formed by coating the surface of titanium with a platinum iridium alloy can be preferably used. Platinum is excellent in conductivity and corrosion resistance, iridium is excellent in durability and chemical stability, and the platinum iridium alloy has a characteristic that the surface is uniform and smooth. The electrode formed by coating the surface of titanium with a platinum iridium alloy can be used for both the anode and the cathode. Note that the example of the electrode described here is merely an example, and when the electrode inversion method described later is not used, an electrode obtained by coating titanium with ruthenium or the like may be used as the anode, or other materials may be used.

[0085] Part or all of the electrode part 55 is arranged on the side of the water surface W2 of the breeding water in the electrolysis cell 11 so that the breeding water is interposed between the first electrode 55A and the second electrode 55B. On the other hand, the electrolysis cell 11 is provided with a water flow generation part 57 that generates a water flow from the lower side to the upper side (electrode part side) of the electrode part 55.

[0086] The water flow generation part 57 has a structure that causes the breeding water introduced into the electrolysis cell 11 from the outside of the electrolysis cell 11 through the flow path 42 to flow upward from the lower side to the upper side of the electrode part 55 in the electrolysis cell 11. The flow path 42 is a flow path that allows the breeding water discharged through the discharge part 66 to flow into the electrolysis cell 11, and may be constituted by the discharge part 66 or may be constituted as a flow path following the discharge part 66. The water flow generation part 57 has a first partition wall 57A. The first partition wall 57A is a wall that partitions a predetermined upstream region and a predetermined downstream region in the electrolysis cell 11. The downstream region is a region on the downstream side of the first partition wall 57A and is a region where the electrode part 55 is provided. The upstream region is a region on the upstream side of the first partition wall 57A and on the upstream side of the downstream region.

[0087] In the example of FIG. 5, the upstream region is the internal region of the first breeding water flow chamber 11A formed by the first partition wall 57A and the portion of the outer peripheral wall and the bottom wall 11Z of the electrolysis cell 11 upstream of the first partition wall 57A, and is the region into which the breeding water flows from the flow path 42. An opening for moving the breeding water in the first breeding water flow chamber 11A to the second breeding water flow chamber is provided on the bottom wall side in the first breeding water flow chamber 11A. In the example of FIG. 5, the opening is formed by the lower end portion of the first partition wall 57A, the outer peripheral wall of the electrolysis cell 11, and the bottom wall 11Z.

[0088] The downstream region is the internal region of the second breeding water flow chamber 11B formed by the first partition wall 57A, the second partition wall 57B, and the portion between the first partition wall 57A and the second partition wall 57B in the outer peripheral wall and the bottom wall 11Z of the electrolysis cell 11, and is the region where part or all of the electrode portion 55 is arranged. In the second breeding water flow chamber 11B, the height of the upper end portion of the second partition wall 57B is lower than the height of the upper end portion of the outer peripheral wall of the electrolysis cell 11. When water exceeding the upper end portion of the second partition wall 57B enters the second breeding water flow chamber 11B, the water flows to the downstream side of the second breeding water flow chamber 11B over the second partition wall 57B. Due to this configuration, in the second breeding water flow chamber 11B, the breeding water is introduced from the lower opening, and the breeding water is led out so as to exceed the upper end portion of the second partition wall 57B. Therefore, a water flow of the breeding water is generated so as to rise from below the electrode portion 55 toward the electrode portion 55 side.

[0089] Note that in the example of FIG. 5, the second partition wall 57B is provided, but the second partition wall 57B may not be provided. In this case, the entire downstream side of the first partition wall 57A in the electrolysis cell 11 is the downstream region, and the second breeding water flow chamber 11B is formed by the first partition wall 57A and the portion of the outer peripheral wall and the bottom wall 11Z of the electrolysis cell 11 downstream of the first partition wall 57A.

[0090] As shown in FIG. 6, an induction part 58 is provided in the electrolysis cell 11. The induction part 58 functions to guide and collect the deposits that have sunk from the electrode part 55 in the electrolysis cell 11 toward a predetermined position in the electrolysis cell 11. In the examples of FIGS. 5 and 6, the above-mentioned predetermined position is a position above a part of the bottom wall 11Z. In the examples of FIGS. 5 and 6, on the downstream side of the second breeding water flow chamber 11B, a third breeding water flow chamber 11C is formed by the second partition wall 57B and the part of the outer peripheral wall and the bottom wall 11Z of the electrolysis cell 11 that is downstream of the second partition wall 57B, and the position above a part of the bottom wall 11Z in the third breeding water flow chamber 11C is the above-mentioned predetermined position. The induction part 58 includes an inclined part 58A having an inclined surface inclined with respect to the vertical direction. The inclined surfaces of the inclined parts 58A and 58B constitute the inner wall surface of the third breeding water flow chamber 11C. In the third breeding water flow chamber 11C, when an object (for example, a deposit) that sinks reaches the inclined surface of the inclined part 58A, it is guided by the inclined surface during the further sinking process and is induced to the vicinity of the above-mentioned predetermined position on the bottom wall 11Z. The inclined surfaces of the inclined parts 58A and 58B guide the object sinking along these inclined surfaces to move in a predetermined first direction orthogonal to the vertical direction (specifically, to move toward the discharge part 59 side in the first direction).

[0091] As shown in FIGS. 5 and 6, a discharge part 59 is provided in the electrolysis cell 11. In the example of FIG. 5, the discharge part 59 is provided at two locations. However, it is not limited to this example, and the number of the discharge parts 59 may be 1 or may be 3 or more. The discharge part 59 has a pipe 59A for discharging the deposits that have sunk from the electrode part 55 in the electrolysis cell 11 and an opening / closing part 59B for opening and closing this pipe 59A. The discharge part 59 functions to take in the deposits into the inside of the pipe 59A at a position lower than the electrode part 55 and discharge the deposits from the electrolysis cell 11 through the pipe 59A.

[0092] In the examples of FIGS. 5 and 6, the opening / closing part 59B is a stop valve that switches between a state of blocking the pipe 59A and a state of opening it, for example, by manual operation. Note that the opening / closing part 59B may be an electromagnetic valve or the like whose opening and closing are switched by control. In any case, when the opening / closing part 59B is in the open state, the breeding water is discharged from near the predetermined position in the electrolytic cell 11 through the pipe 59A. When deposits precipitate near the predetermined position, the deposits are discharged through the pipe 59A together with the breeding water. In the examples of FIGS. 5 and 6, the pipe 59A is a fixed pipe permanently installed in the electrolytic cell 11, but it may be a pipe that can be attached to and detached from the electrolytic cell 11. Further, when discharging from near the predetermined position through a pipe, it may be discharged by utilizing the water pressure in the electrolytic cell 11, or it may be discharged by suction or flowing by means of a pump or the like.

[0093] As shown in FIGS. 5 and 6, a first guiding path 56 is provided in the electrolytic cell 11. The first guiding path 56 corresponds to an example of a guiding path. The first guiding path 56 functions as a flow path that does not guide the water located below the first height in the electrolytic cell 11 to the outside of the electrolytic cell 11, but guides the water located above the first height to the outside of the electrolytic cell 11. The first height corresponds to an example of a predetermined height. In the example of FIG. 5, the water surface W2 of the breeding water in the electrolytic cell 11 is located above the lower end position of the inner wall surface of the flow path at the inlet of the first guiding path 56 (the boundary part with the first guiding path 56 which is the outlet of the electrolytic cell 11), and the water near the water surface of the breeding water in the electrolytic cell 11 flows into the first guiding path 56 exceeding the height of the bottom of the first guiding path 56. In the example of FIG. 5, the height of the lower end of the inner wall surface of the flow path at the inlet of the first guiding path 56 is the first height (predetermined height), and this first height (predetermined height) is located above the lower end of the electrode part 55. The height of the lower end of the electrode part 55 is the height of the lowest position among the plurality of first electrodes 55A and the plurality of second electrodes 55B. The first guiding path 56 functions to flow the breeding water in the electrolytic cell 11 toward the reaction tank 15.

[0094] (Reaction tank) The reaction tank 15 stores the breeding water supplied from the electrolysis tank 11 through the flow path 43, secures the reaction time between the ammonia or ammonium ions contained in the stored breeding water and the chloric acid compound (for example, sodium hypochlorite) generated in the electrolysis tank 11, and is a tank that promotes these chemical reactions. The flow path 43 may be constituted by the first guiding path 56, or may be configured as a flow path following the first guiding path 56. If all of the ammonia or ammonium ions present in the breeding water in the electrolysis tank 11 do not completely react with the chloric acid compound in the electrolysis tank 11 and remain and flow out of the electrolysis tank 11, and if the chloric acid compound generated in the electrolysis tank 11 does not completely react and flows out of the electrolysis tank 11, either or both of the chemical reactions of the formula (2) or the formula (3) above occur in the reaction tank 15, and the ammonia or ammonium ions are decomposed.

[0095] As shown in FIG. 5, a second guiding path 72 is provided in the reaction tank 15. The second guiding path 72 functions as a flow path that does not guide the water located below the second height in the reaction tank 15 to the outside of the reaction tank 15, but guides the water located above the second height to the outside of the reaction tank 15. In the example of FIG. 5, the water surface W3 of the breeding water in the reaction tank 15 is located above the lower end position of the inner wall surface of the flow path at the inlet of the second guiding path 72 (the boundary part with the second guiding path 72 which is the outlet of the reaction tank 15), and the water near the water surface of the breeding water in the reaction tank 15 flows into the second guiding path 72 exceeding the height of the bottom of the second guiding path 72. In the example of FIG. 5, the height of the lower end of the inner wall surface of the flow path at the inlet of the second guiding path 72 is the second height. The second guiding path 72 functions to flow the breeding water in the reaction tank 15 toward the subsequent process of the reaction tank 15.

[0096] In the subsequent process of the reaction tank 15, a filtration tank 17 that constitutes a detection region for detecting residual chlorine is provided. The filtration tank 17 is a part configured to store the breeding water supplied from the reaction tank 15 through the flow path 44 and lead it to the flow path 45. The flow path 44 is a flow path that allows the breeding water discharged through the second guiding path 72 to flow into the filtration tank 17. It may be constituted by the second guiding path 72 or may be configured as a flow path following the second guiding path 72. In the example of FIG. 1, a flow path for guiding the breeding water from the reaction tank 15 to the activated carbon tank 21 is constituted by the flow path 44, the filtration tank 17, and the flow path 45. However, as long as the breeding water flows from the reaction tank 15 to the activated carbon tank 21, other configurations (for example, a configuration in which a pipe continues from the reaction tank 15 to the activated carbon tank 21 without providing the filtration tank 17) may be used.

[0097] The first residual chlorine sensor 19 is a sensor that detects the concentration of residual chlorine contained in the breeding water from the time it passes through the electrolysis tank 11 until it flows into the residual chlorine removal tank (specifically, the activated carbon tank 21). For example, it detects the concentration of residual chlorine contained in the breeding water in the region where the breeding water flows between the reaction tank 15 and the activated carbon tank 21. In the representative example shown in FIG. 1, the first residual chlorine sensor 19 detects the residual chlorine contained in the breeding water in the filtration tank 17. In this specification, residual chlorine means combined chlorine and free chlorine remaining in the breeding water. The total amount of chlorine, which is the sum of the amount of combined chlorine and the amount of free chlorine contained in the breeding water, is the amount of residual chlorine. By the first residual chlorine sensor 19 detecting the residual chlorine contained in the breeding water in the region between the reaction tank 15 and the activated carbon tank 21, the amount of chlorate compounds remaining due to the decomposition of ammonia or ammonium ions in the electrolysis tank 11 and the reaction tank 15 can be measured.

[0098] (Residual chlorine removal tank) In the example of FIG. 5, an activated carbon tank 21 is provided as an example of a residual chlorine removal tank. The residual chlorine removal tank is a tank that removes at least residual chlorine from the breeding water, and functions to remove residual chlorine from the breeding water by passing the breeding water through the residual chlorine removal section. The activated carbon tank 21 illustrated in FIG. 5 is a tank in which the breeding water that has passed through the reaction tank 15 is stored, and specifically, is a tank provided downstream of the detection region where the first residual chlorine sensor 19 is disposed (the region in the filtration tank 17 in the example of FIG. 1). The activated carbon tank 21 functions as a tank that removes chloric acid compounds (for example, sodium hypochlorite) generated in the electrolytic cell 11. The activated carbon tank 21 is provided with an activated carbon section 23 including activated carbon, and the activated carbon section 23 corresponds to an example of the residual chlorine removal section. The activated carbon section 23 removes at least residual chlorine and residual ozone from the breeding water in the activated carbon tank 21 by means of the activated carbon. In the example of FIG. 1, the internal region of the activated carbon tank 21 corresponds to an example of the third region, and is a region where the breeding water that has passed through the second region is stored or flows.

[0099] In the activated carbon tank 21, for example, it reacts as shown in the following formula (4), and can remove the surplus chloric acid compounds that have not been used for the decomposition of ammonia or ammonium ions. HClO + C → CO + H + + Cl - ···(4)

[0100] The activated carbon tank 21 illustrated in FIG. 5 can be configured as shown in FIG. 7, for example. In the example of FIG. 7, the activated carbon tank 21 is configured as a flow path through which the breeding water passes, and the activated carbon section 23 is configured in such a form that the internal space of the flow path is filled with activated carbon particles. In the activated carbon tank 21, the gaps in the activated carbon section 23 (specifically, the gaps in the internal space filled with activated carbon particles) are configured such that the breeding water flows, and in the process of the breeding water flowing in from the inlet 21A of the activated carbon tank 21 passing through the gaps between the numerous particles in the activated carbon tank 21, the residual chlorine and residual ozone contained in the breeding water are adsorbed by the activated carbon, and the breeding water discharged from the outlet 21B becomes breeding water from which part or all of the chlorine and ozone have been removed.

[0101] (Standby tank) The breeding water introduced from the flow path 45 into the activated carbon tank 21 passes through the internal area of the activated carbon tank 21, is discharged into the flow path 46, and flows into the standby tank 25 through the flow path 46. The standby tank 25 is a tank in which the breeding water that has passed through the activated carbon tank 21 is stored and the water quality before returning to the breeding tank 3 is inspected. The internal area of the standby tank 25 corresponds to an example of the fourth area, and is an area where the breeding water that has passed through the above-described third area is stored or flows before returning to the breeding tank 3.

[0102] The second residual chlorine sensor 27 is a sensor that detects the concentration of residual chlorine contained in the breeding water in the fourth area where the breeding water that has passed through the above-described third area is stored or flows, and in the example of FIG. 1, detects the concentration of residual chlorine contained in the breeding water in the standby tank 25. The second residual chlorine sensor 27 can more accurately detect fluctuations in the concentration of residual chlorine due to such outflow when residual chlorine flows out due to deterioration of the activated carbon provided in the activated carbon part 23 or the like.

[0103] The ammonium ion sensor 29 is a sensor that detects the concentration of ammonium ions contained in the breeding water in the fourth area where the breeding water that has passed through the above-described third area is stored or flows, and in the example of FIG. 1, detects the concentration of ammonium ions contained in the breeding water in the standby tank 25. The ammonium ion sensor 29 can more accurately detect fluctuations in the concentration of ammonium ions when ammonium ions remain without being completely reacted by the electrolysis tank 11 or the reaction tank 15.

[0104] The pH sensor 28 is a sensor that measures the pH (hydrogen ion exponent) of the breeding water in the fourth area where the breeding water that has passed through the above-described third area is stored or flows. In the example of FIG. 1, the pH sensor 28 measures the pH of the breeding water in the standby tank 25 and gives a value specifying the pH of the breeding water in the standby tank 25 to the control device 52.

[0105] In the standby tank 25, aeration is performed by an aeration device (not shown) to remove CO2 from the breeding water. Then, the breeding water in the standby tank 25 flows into the breeding tank 3 through the flow path 47. The operation of flowing the breeding water from the standby tank 25 to the breeding tank 3 through the flow path 47 can be switched between a state of continuously flowing the breeding water from the standby tank 25 to the breeding tank 3 and a state of stopping or blocking the flow of the breeding water from the standby tank 25 to the breeding tank 3.

[0106] 3. Control of the Circulating Water Treatment System 1 (Configuration for Control) In the circulating water treatment system 1, the breeding water in the breeding tank 3 is circulated in the order of the removal unit 5, the electrolysis tank 11, the reaction tank 15, the filtration tank 17, the activated carbon tank 21, and the standby tank 25. A plurality of pumps (not shown) for flowing the breeding water are provided at multiple locations along the circulation path for circulating the breeding water from the breeding tank 3 and returning it to the breeding tank 3. The control device 52 shown in FIG. 2 controls the driving and stopping of the above pumps. Further, the control device 52 controls the driving and stopping of the temperature regulator 35, the driving and stopping of the ozone generator 9, the driving and stopping of the foam separator 7, the driving and stopping of the electrolysis unit 13, the operation of the treatment unit 31, etc.

[0107] The detection values of the first residual chlorine sensor 19, the second residual chlorine sensor 27, the pH sensor 28, and the ammonium ion sensor 29 are input to the control device 52 shown in FIG. 2. The detection value input from the first residual chlorine sensor 19 is a value indicating the concentration of residual chlorine contained in the breeding water in the above detection region (specifically, inside the filtration tank 17). The detection value input from the second residual chlorine sensor 27 is a value indicating the concentration of residual chlorine contained in the breeding water in the above fourth region (specifically, inside the standby tank 25). The detection value input from the pH sensor 28 is a value indicating the pH (hydrogen ion index) of the breeding water in the above fourth region (specifically, inside the standby tank 25). The detection value input from the ammonium ion sensor 29 is a value indicating the concentration of ammonium ions contained in the breeding water in the above fourth region (specifically, inside the standby tank 25).

[0108] (Control of Electrolysis) The control device 52 corresponds to an example of a control unit and controls the electrolysis of the electrolysis unit 13. The control device 52 may control the electrolysis of the electrolysis unit 13 based on the measurement results of the ammonium ion sensor 29 and the measurement results of the first residual chlorine sensor 19, may control the electrolysis of the electrolysis unit 13 based on the measurement results of the ammonium ion sensor 29, or may control the electrolysis of the electrolysis unit 13 based on the measurement results of the first residual chlorine sensor 19. When the control device 52 controls the electrolysis of the electrolysis unit 13 based on the measurement results of the ammonium ion sensor 29, for example, the current flowing between the first electrode 55A and the second electrode 55B may be feedback-controlled so that the detected value of the ammonium ion sensor 29 becomes equal to or less than a predetermined value. When the control device 52 controls the electrolysis of the electrolysis unit 13 based on the measurement results of the first residual chlorine sensor 19, for example, the current flowing between the first electrode 55A and the second electrode 55B may be feedback-controlled so that the detected value of the first residual chlorine sensor 19 falls within a predetermined range.

[0109] When grasping the ammonia concentration and the concentration of available chlorine in the breeding water (for example, seawater) used in this embodiment, it can be grasped based on the discontinuous point chlorine treatment method. For example, in the first state where the concentrations of ammonia and ammonium ions in the breeding water are equal to or higher than a certain concentration with respect to the concentration of available residual chlorine, the higher the addition amount of the chlorate compound, the higher the available residual chlorine concentration. On the other hand, in the second state where ammonia or ammonium ions are present but the concentrations of ammonia and ammonium ions are less than the above-mentioned certain concentration with respect to the concentration of available residual chlorine, the available residual chlorine concentration decreases even when a chlorate compound is added because it is consumed by the reaction with ammonia or ammonium ions. Then, in the third state where ammonia and ammonium ions are not present, the higher the addition amount of the chlorate compound, the higher the available residual chlorine concentration. If the pH, salinity concentration, and temperature of the breeding water are constant, the above-mentioned certain concentration can be considered as a fixed value.

[0110] The control device 52 is configured to be able to detect the current flowing between the first electrode 55A and the second electrode 55B in the electrolysis unit 13, and continuously monitors the current flowing between the first electrode 55A and the second electrode 55B. Various configurations can be adopted for the configuration in which the control device 52 monitors the current flowing between the first electrode 55A and the second electrode 55B. For example, the current may be detected by a current sensor, and the control device 52 may acquire the value detected by the current sensor, or other configurations may be used. Then, the control device 52 controls the current flowing between the first electrode 55A and the second electrode 55B based on the detection value of either or both of the ammonium ion sensor 29 and the first residual chlorine sensor 19.

[0111] The control device 52 may perform a first current control so as to control the current flowing between the first electrode 55A and the second electrode 55B based on the detection values of both the ammonium ion sensor 29 and the first residual chlorine sensor 19. The greater the current flowing between the first electrode 55A and the second electrode 55B, the more the electrolysis is promoted and the greater the amount of the chloric acid compound generated. Therefore, when performing the first current control, the control device 52 adjusts the current flowing between the first electrode 55A and the second electrode 55B so that the value (detection value) of the ammonium ion concentration detected by the ammonium ion sensor 29 is equal to or less than the first threshold value. The first threshold value may be 0 or a value slightly greater than 0. On the other hand, in a state where ammonia and ammonium ions are not present, the higher the current flowing between the first electrode 55A and the second electrode 55B, the higher the effective chlorine concentration. Therefore, the control device 52 adjusts the current flowing between the first electrode 55A and the second electrode 55B so that the current range is such that the detection value of the ammonium ion sensor 29 is equal to or less than the first threshold value and the current range is such that the value (detection value) of the residual chlorine amount detected by the first residual chlorine sensor 19 is equal to or less than the second threshold value.

[0112] The control device 52 may perform a second current control to control the current flowing between the first electrode 55A and the second electrode 55B based on the detection value of the ammonium ion sensor 29 without using the detection value of the first residual chlorine sensor 19. Even when the control device 52 performs the second current control, it adjusts the current flowing between the first electrode 55A and the second electrode 55B so that the value (detection value) of the ammonium ion concentration detected by the ammonium ion sensor 29 is equal to or less than the first threshold value. The first threshold value may be 0 or a value slightly larger than 0. When the control device 52 performs the second current control, it repeats "current adjustment control for confirming the value (detection value) of the ammonium ion concentration detected by the ammonium ion sensor 29 after controlling the current flowing between the first electrode 55A and the second electrode 55B to the set current value and performing electrolysis for a certain period of time". In this control, if the detection value of the ammonium ion sensor 29 exceeds the first threshold value in the previous current adjustment control, the next current adjustment control is performed so that the current value increased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control is used as the next set current value. On the other hand, if the detection value of the ammonium ion sensor 29 is equal to or less than the first threshold value in the previous current adjustment control, the next current adjustment control is performed so that the set current value used in the previous current adjustment control is used as the next set current value. By doing so, electrolysis can be performed while gradually increasing the current until the detection value of the ammonium ion sensor 29 becomes equal to or less than the first threshold value, and when the detection value of the ammonium ion sensor 29 becomes equal to or less than the first threshold value, electrolysis can be performed while maintaining the current state.

[0113] The control device 52 may perform a third current control to control the current flowing between the first electrode 55A and the second electrode 55B based on the detection value of the first residual chlorine sensor 19 without using the detection value of the ammonium ion sensor 29. When performing the third current control, the control device 52 repeats "current adjustment control for confirming the value (detection value) of the residual chlorine amount detected by the first residual chlorine sensor 19 after controlling the current flowing between the first electrode 55A and the second electrode 55B to the set current value and performing electrolysis for a certain period of time". In this control, when the set current value in the previous current adjustment control is increased by a predetermined ratio (for example, 10%) with respect to the set current value in the previous-previous current adjustment control, and the value (detection value) of the residual chlorine amount detected in the previous current adjustment control is smaller than the value (detection value) of the residual chlorine amount detected in the previous-previous current adjustment control, it can be estimated that the above-mentioned second state is present. Therefore, in this case, in the next current adjustment control (the current adjustment control this time), the current adjustment control is performed so that the current value increased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control is set as the set current value. That is, while the detected value of the residual chlorine amount decreases, the current adjustment control for each time is performed so that the set current value is gradually increased. On the other hand, when performing the control of gradually increasing the set current value in this way, when the set current value in the previous current adjustment control is increased by a predetermined ratio (for example, 10%) with respect to the set current value in the previous-previous current adjustment control, and the value (detection value) of the residual chlorine amount detected in the previous current adjustment control is larger than the value (detection value) of the residual chlorine amount detected in the previous-previous current adjustment control, it can be estimated that the above-mentioned third state is present. Therefore, in this case, in the next current adjustment control (the current adjustment control this time), the current adjustment control is performed so that the current value decreased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control is set as the set current value.In addition, when the set current value in the previous current adjustment control is decreased by a predetermined ratio (for example, 10%) with respect to the set current value in the previous - previous current adjustment control, if the value (detection value) of the residual chlorine amount detected in the previous current adjustment control is smaller than the value (detection value) of the residual chlorine amount detected in the previous - previous current adjustment control, then in the next current adjustment control (the current adjustment control this time), the current adjustment control is performed such that the set current value is a current value decreased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control. If the value (detection value) of the residual chlorine amount detected in the previous current adjustment control is larger than the value (detection value) of the residual chlorine amount detected in the previous - previous current adjustment control, then in the next current adjustment control (the current adjustment control this time), the current adjustment control may be performed such that the set current value is a current value increased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control.

[0114] (Control based on monitoring of residual chlorine) When a predetermined measurement result is obtained by the second residual chlorine sensor 27, the treatment unit 31 may operate to remove residual chlorine from the breeding water in the fourth region, or may operate to stop returning the breeding water in the fourth region to the breeding tank 3.

[0115] For example, when the concentration (detection value) of the residual chlorine detected by the second residual chlorine sensor 27 exceeds a predetermined value, the treatment unit 31 may supply a neutralizing agent to the breeding water before it returns to the breeding tank 3. As the neutralizing agent, for example, sodium thiosulfate, catechin, polyphenol, cysteine, etc. can be preferably used. In the example of FIG. 7, as an element constituting at least a part of the treatment unit 31, a neutralizing agent supply device 31A for supplying a neutralizing agent to the breeding water in the fourth region is provided. Specifically, for example, the control device 52 and the neutralizing agent supply device 31A function as the treatment unit 31 and the neutralizing agent supply unit. When the concentration (detection value) of the residual chlorine detected by the second residual chlorine sensor 27 exceeds a predetermined value, the control device 52 gives a neutralizing agent input command to the neutralizing agent supply device 31A, and in response to this neutralizing agent input command, the neutralizing agent supply device may operate to input a "neutralizing agent that causes a neutralization reaction with residual chlorine" into the standby tank 25.

[0116] When the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 exceeds a predetermined value, the treatment unit 31 may operate to switch the flow path so that the breeding water is not returned from the standby tank 25 to the breeding tank 3 but is flowed from the standby tank 25 to another area. For example, a three-way valve (not shown) may be provided in the middle of the flow path 47 so that the supply destination of the breeding water flowing through the flow path 47 can be switched between the breeding tank 3 and another area by the three-way valve. In this example, the control device 52 and the three-way valve can function as the treatment unit 31. Specifically, when the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 is equal to or less than the predetermined value, the control device 52 sets the supply destination from the three-way valve to the breeding tank 3, and when the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 exceeds the predetermined value, the control device 52 may perform control so that the supply destination from the three-way valve is another area.

[0117] Alternatively, when the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 exceeds a predetermined value, the treatment unit 31 may block the flow path for flowing the breeding water from the standby tank 25 to the breeding tank 3 and stop returning the breeding water to the breeding tank 3, and may also stop the circulation of the breeding water in the system 1 and stop returning the breeding water to the breeding tank 3. For example, an on-off valve (not shown) may be provided in the middle of the flow path 47, and when the on-off valve is in the open state, the flow of the flow path 47 is allowed, and when the on-off valve is in the blocked state, the flow of the flow path 47 is blocked. In this example, the control device 52 and the on-off valve can function as the treatment unit 31. Specifically, when the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 is equal to or less than the predetermined value, the control device 52 sets the on-off valve to the open state, and when the detected value of the residual chlorine concentration detected by the second residual chlorine sensor 27 exceeds the predetermined value, the control device 52 may perform control so that the on-off valve is in the blocked state. In this example, when the on-off valve is in the blocked state, the driving of the pump for circulating the breeding water in the system may be stopped so that the standby tank 25 does not overflow, and when the water surface of the standby tank 25 exceeds a certain level, the flow path may be provided so that the breeding water escapes from the standby tank 25 to another area.

[0118] (Control Based on pH Monitoring) In this embodiment, an adjusting material supply device 32 is provided to supply a pH adjusting material to the breeding water in the fourth region. In the example of FIG. 7, the adjusting material supply device 32 is configured to supply a pH adjusting material to the breeding water in the standby tank 25. The control device 52 gives an instruction on the supply timing and supply rate to the adjusting material supply device 32, and the adjusting material supply device 32 supplies the pH adjusting material at the supply rate instructed by the control device 52 at the supply timing instructed by the control device 52.

[0119] As the pH adjusting material supplied from the adjusting material supply device 32, for example, any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and sodium hydrogen carbonate can be preferably used, and it is more preferable to use either sodium carbonate or sodium hydrogen carbonate, and it is even more preferable to use sodium carbonate. When using sodium carbonate, sodium hydrogen carbonate, calcium carbonate, etc. as the pH adjusting material, an aqueous solution containing any of them may be used. When using sodium carbonate with a high pH, since it is a strong alkali, it has the merit of easily increasing the pH of the breeding water and being less likely to disrupt the ion balance. Sodium hydrogen carbonate has the merit of being less likely to disrupt the ion balance and being able to exhibit a pH buffering function. In addition, in order to prevent the inhibition of the pH adjustment effect due to the precipitation of magnesium contained in seawater, the pH of the pH adjusting material is preferably 11.5 or less.

[0120] The method of control by the control device 52 is various. For example, when the pH of the breeding water detected by the pH sensor 28 becomes equal to or less than the first reference value, the control device 52 operates the adjusting material supply device 32 to supply a pH adjusting material with a pH higher than the first reference value at a predetermined supply rate. When the pH of the breeding water detected by the pH sensor 28 exceeds the second reference value while the adjusting material supply device 32 is supplying the pH adjusting material, on-off control may be performed to stop the supply of the pH adjusting material by the adjusting material supply device 32. In the above example, the first reference value and the second reference value may be the same or different.

[0121] In addition, in order to reduce the consumption of the pH adjuster, solid calcium carbonate (e.g., pellets, etc.) may be provided in the fourth region (e.g., inside the flow paths 46 and 47 and the standby tank 25).

[0122] In the above example, the timing of inputting the pH adjuster is controlled. Instead of such a method, the pH adjuster may be continuously supplied at a constant supply rate.

[0123] 4. Cleaning of Electrodes As shown in FIG. 5, in the present embodiment, the control device 52 and the drive circuit 53 function as the voltage application unit 51. The voltage application unit 51 applies a voltage so that the first electrode 55A is the anode and the second electrode 55B is the cathode, and performs electrolysis in the above-mentioned "region" (specifically, inside the electrolytic cell 11), and a first state in which a voltage is applied so that the second electrode 55B is the anode and the first electrode 55A is the cathode. It operates to switch to the second state. For example, the voltage application unit 51 periodically switches between an operation of continuously electrolyzing the breeding water in the first state and an operation of continuously electrolyzing the breeding water in the second state. The switching period in the case of periodic switching may be, for example, every several tens of minutes, every several hours, every day, or other periods.

[0124] The timing at which the voltage application unit 51 switches between the first state and the second state is not limited to a periodic timing, and may be a timing when a predetermined condition is satisfied. For example, it may be switched at a timing when the operating time of the circulating water treatment system 1 has reached a certain time since the previous switching time, or at a timing when a detection value by some sensor has reached a predetermined value, or at a randomly determined timing, or other timings.

[0125] In this embodiment, while continuously performing "replacement of the breeding water" so as to continuously conduct the introduction of the breeding water from the flow path 42 into the electrolysis cell 11 and the drainage of the breeding water from the electrolysis cell 11 to the first induction path 56, the operation in the first state of continuously applying a voltage such that the first electrode 55A is used as the anode and the second electrode 55B is used as the cathode by the voltage application unit 51 is continuously performed. When the switching condition is satisfied during the operation in the first state, a switch from the first state to the second state is made while performing the above-mentioned "replacement of the breeding water". After the switching, the operation in the second state of continuously applying a voltage such that the second electrode 55B is used as the anode and the first electrode 55A is used as the cathode while performing the above-mentioned "replacement of the breeding water" is continuously performed. When the switching condition is satisfied during the operation in the second state, a switch from the second state to the first state is made while performing the above-mentioned "replacement of the breeding water". In such a flow, the operation in the first state and the operation in the second state are alternately performed. During the continuation of the operation in the first state or the continuation of the operation in the second state, the operation may be continuous without interruption, or may be temporarily interrupted for some reason.

[0126] 5. Examples of effects In order to maintain the water quality of the breeding water in the aquaculture of aquatic organisms, it is necessary to remove solids such as feces, uneaten feed, and parasites excreted by the aquatic organisms and discharge them outside the aquaculture system. Furthermore, nitrogen compound components such as ammonia, nitrous acid, and nitric acid need to be detoxified as much as possible. In this regard, in the circulating water treatment system 1 and the aquaculture method using the system 1, solids and the like contained in the breeding water in the above-mentioned first region can be removed by the removal unit 5 equipped with the foam separator 7. Furthermore, the circulating water treatment system 1 can decompose ammonia or ammonium ions by the electrolysis unit 13 in the second region after passing through the first region. Moreover, by electrolyzing the breeding water containing salt, a chloric acid compound (for example, sodium hypochlorite) is generated, and this chloric acid compound can be directly decomposed into nitrogen by reacting with ammonia or ammonium ions present in the breeding water. Therefore, during the decomposition process, the generation of nitrous acid, nitric acid, etc. can be reliably suppressed. In addition, since the circulating water treatment system 1 performs electrolysis of the breeding water after removing solids by the removal unit 5, it can surely suppress the solids from inhibiting electrolysis and is easy to perform electrolysis well. Furthermore, the circulating water treatment system 1 can remove residual chlorine with activated carbon in the third region where the breeding water passing through the second region is stored or flows. Therefore, even if the chloric acid compound not used for the decomposition of ammonia is contained in the breeding water in the third region, this chloric acid compound can be effectively removed by the activated carbon unit 23. Thus, in the circulating water treatment system 1, solids such as feces and uneaten feed are surely reduced in the breeding water after passing through the third region, and nitrogen compound components such as ammonia, nitrous acid, and nitric acid are also surely suppressed. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0127] As a prior art, as in Patent Document 1, there is a technique of decomposing ammonia using microorganisms and changing it to nitric acid or the like. However, in this type of technique, when the breeding environment (for example, metabolism and water quality) can change depending on the type of aquatic organisms, breeding density, etc., it is difficult to perform appropriate control according to the breeding environment.

[0128] For example, among aquatic organisms, there are those that prefer low temperatures of 20°C or lower, and there are also those that prefer temperature ranges of 25°C or higher. In contrast, since the microorganisms that contribute to the decomposition of ammonia generally become less active at 20°C or lower, in low temperature zones, it is necessary to increase the absolute amount of microorganisms in order to ensure the purification and decomposition ability. The larger the absolute amount of microorganisms, the larger the required size of the filtration tank. Therefore, in this type of technology, in order to sufficiently perform purification and decomposition whether at normal temperature or low temperature, it is necessary to increase the absolute amount of microorganisms assuming low temperature, and accordingly, an excessive equipment design such as increasing the size of the filtration tank must be adopted. On the other hand, in high temperature zones of 25°C or higher, the activity of microorganisms improves, and the decomposition and purification of ammonia proceed relatively quickly. However, in high temperature zones, the reproduction of pathogenic bacteria also becomes active, so it is necessary to increase the frequency of drug administration and water replacement, which easily leads to a decrease in productivity and workability.

[0129] In contrast, the above-described circulating water treatment system 1 and the above-described aquaculture method can more effectively decompose ammonia and ammonium ions in water by a method that suppresses dependence on microorganisms, and can easily solve the above problems. Moreover, it is also possible to effectively remove pollution elements other than ammonia and ammonium ions (solids such as feces and uneaten feed contained in the breeding water, removal proteins of metabolites of fishery products, bacteria, viruses, parasites, etc.), and a synergistic effect can be exerted.

[0130] Furthermore, the circulating water treatment system 1 operates to generate foam containing ozone generated by the ozone generator 9 with the foam separator 7, and adsorb the solids contained in the breeding water in the first region to the foam containing ozone. That is, in the process of the breeding water in the first region passing through the foam separator, this circulating water treatment system 1 can not only remove solids, but also perform sterilization and disinfection with ozone, and can more surely suppress the influence of viruses, bacteria, and parasites, which are factors that inhibit the growth of aquatic organisms. Moreover, due to the characteristic technology of allowing ozone to act on the foam separator 7 for removing solids, sterilization and disinfection can be performed more efficiently and effectively.

[0131] Furthermore, the recirculating water treatment system 1 can inspect ammonium ions contained in the breeding water by an ammonium ion sensor 29 in the region after ammonia decomposition in the second region. However, when detecting ammonium ions in breeding water containing salts by the ammonium ion sensor 29, there is a high possibility that interfering substances (substances that the ammonium ion sensor 29 is likely to misidentify as ammonium ions) are contained in the breeding water. If detection is performed by the ammonium ion sensor 29 without taking any measures, there is a risk that ammonium ions cannot be accurately detected due to the influence of the interfering substances. However, the recirculating water treatment system 1 can address this problem by inspecting with the ammonium ion sensor 29 in the fourth region where the breeding water passing through the third region is stored or flows before returning to the breeding tank 3. That is, the recirculating water treatment system 1 can remove solids in the first region, perform removal by activated carbon in the third region, and then detect ammonium ions in the fourth region. Therefore, in the breeding water from which interfering substances have been effectively removed, the concentration variation of ammonium ions can be accurately detected.

[0132] Also, when the removal unit 5 removes solids, the breeding water introduced from the previous process region can be temporarily stored in the storage tank 60, introduced from this storage tank 60 into the foam separator 7 to remove solids, and then returned to the foam separator 7. If the removal unit 5 is configured in this way, the storage tank 60 serves as a buffer in the process of circulating the breeding water, and even if the introduction speed into the foam separator 7 or the discharge speed from the foam separator 7 is different from the circulation speed of other processes, the water level in other processes is less likely to fluctuate significantly.

[0133] Furthermore, the circulating water treatment system 1 includes a control device 52 (control unit) that controls the electrolysis of the electrolysis unit 13 based on the measurement results of the ammonium ion sensor 29. After the interfering substances are effectively removed from the breeding water, the concentration fluctuation of ammonium ions can be accurately measured, and the electrolysis can be controlled using this measurement result. Therefore, the circulating water treatment system 1 can perform electrolysis according to the degree of ammonium ions present in the fourth region after passing through the activated carbon unit 23.

[0134] Furthermore, the circulating water treatment system 1 includes a residual chlorine sensor that detects the residual chlorine contained in the breeding water in the region where the breeding water that has passed through the above-mentioned second region is stored or flows before returning to the breeding tank 3. The control device 52 (control unit) controls the electrolysis of the electrolysis unit 13 based on the measurement results of the ammonium ion sensor 29 and the measurement results of the residual chlorine sensor. In this way, the circulating water treatment system 1 can control the electrolysis according to the degree of residual chlorine contained in the breeding water after passing through the second region where electrolysis is performed, and the degree of ammonium ions present in the fourth region after passing through the activated carbon unit 23.

[0135] Furthermore, when a predetermined measurement result is obtained by the second residual chlorine sensor 27 that detects the residual chlorine contained in the breeding water in the above-mentioned fourth region, the treatment unit 31 stops removing the residual chlorine from the breeding water in the fourth region or stops returning the breeding water in the fourth region to the breeding tank 3. Depending on the degree of residual chlorine contained in the breeding water after passing through the above-mentioned second region, the circulating water treatment system 1 can stop removing the residual chlorine from the breeding water in the fourth region or stop returning the breeding water in the fourth region to the breeding tank 3, and can suppress the risk that the breeding water containing residual chlorine is directly returned to the breeding tank 3.

[0136] When the detection value of the second residual chlorine sensor 27 exceeds a predetermined value, the circulating water treatment system 1 can supply a neutralizing agent that causes a neutralization reaction with the residual chlorine in the breeding water before returning to the breeding tank 3. Therefore, when the breeding water in the fourth region contains a certain amount of residual chlorine, the residual chlorine contained in the breeding water can be neutralized and surely reduced.

[0137] The circulating water treatment system generates a chloric acid compound in the electrolysis tank 11 to decompose ammonia and ammonium ions, and ammonia and ammonium ions that cannot be completely decomposed in the electrolysis tank 11 can react with the chloric acid compound in the reaction tank 15. Therefore, even if there is a certain degree of fluidity in the electrolysis tank 11 and ammonia is discharged from the electrolysis tank 11 without complete reaction, the reaction can be promoted in the reaction tank 15. This circulating water treatment system 1 can thus make ammonia and ammonium ions react more surely. On the other hand, a standby tank 25 is secured in the post-process of the activated carbon tank 21, and the ammonium ions in the breeding water before returning to the breeding tank 3 can be inspected by the ammonium ion sensor 29 and the residual chlorine can be inspected by the second residual chlorine sensor 27. On the other hand, the residual chlorine contained in the breeding water from when it passes through the electrolysis tank 11 until it flows into the standby tank 25 can also be inspected by the first residual chlorine sensor 19. And the measurement results of the two types of residual chlorine sensors can be used for different purposes. The electrolysis is controlled using the measurement results of the ammonium ion sensor 29 and the measurement results of the first residual chlorine sensor 19. On the other hand, depending on the measurement results of the second residual chlorine sensor 27 (the degree of residual chlorine contained in the breeding water after passing through the second region), it is possible to remove the residual chlorine from the breeding water in the fourth region or stop returning the breeding water in the fourth region to the breeding tank 3, and the risk that the breeding water containing residual chlorine is directly returned to the breeding tank 3 can be suppressed.

[0138] <Second Embodiment> The following description relates to the second embodiment. The circulation-type water treatment system 1 according to the second embodiment and the aquaculture method using this system 1 are different from the first embodiment in that, as the removal unit 5 shown in FIG. 1, a configuration as shown in FIG. 8 is used instead of the configurations shown in FIGS. 3 and 4. Except for the configuration of the removal unit 5, it is the same as the first embodiment. Therefore, in the following description, for the configurations other than those in FIG. 3, it is assumed that the configurations in FIGS. 1, 2, 5, 6, 7, etc. are used, and the reference numerals, names, etc. attached to these figures are appropriately used.

[0139] In the example of FIG. 8, the removal unit 5 is configured to introduce the breeding water introduced from the area of the previous process of the removal unit 5 into the foam separator 7, and then pass it through the foam separator 7 and lead it out to an area of the subsequent process different from the area of the previous process. The area of the previous process is the area inside the breeding tank 3. The area of the subsequent process is the area inside the electrolysis tank 11. In the removal unit 5, after introducing the breeding water supplied from the area of the previous process of the removal unit 5 into the foam separator 7 through the flow path 41 (the flow path 41 corresponds to an example of an introduction path), it passes through the foam separator 7 and is led out to the "area of the subsequent process of the removal unit 5" (for example, the area inside the electrolysis tank 11) different from the area of the introduction source where the inlet of the flow path 41 (introduction path) is arranged (for example, the area inside the breeding tank 3). In the removal unit 5, the total amount of the breeding water flowing in from the breeding tank 3 through the flow path 41 is sent into the foam separator 7, and there is no flow path that flows from the breeding tank 3 to the electrolysis tank 11 without passing through the foam separator 7. Among the breeding water sent into the foam separator 7, except for the removed substances removed together with the bubbles in the foam separator 7, it is sent into the electrolysis tank 11 through the flow path 43 from the foam separator 7. Note that the operation of the foam separator 7 is the same as that in the first embodiment. Also in this example, bubbles containing ozone are generated in the foam separator 7.

[0140] In this way, when the solid matter is removed by the removal unit 5, the breeding water introduced from the previous process area is introduced into the foam separator 7 and then passed through the foam separator 7 and led out to the subsequent process area different from the previous process area. Therefore, the circulating breeding water can pass through the foam separator 7 more reliably, and the effect of removing solid matter and the effect of sterilization and disinfection by ozone can be further enhanced.

[0141] <Third Embodiment> The following description relates to the third embodiment. The circulating water treatment system 1 according to the third embodiment and the aquaculture method using this system 1 are different from the first embodiment in that, instead of the configuration shown in FIG. 5, the configuration shown in FIG. 9 is used. Specifically, it is the same as the first embodiment except that the inclined portions 58C, 58D, 58E, 58F and the discharge portions 110, 112 are provided in addition to the configuration shown in FIG. 5. Therefore, in the following description, for the configurations other than FIG. 5, it is assumed that the configurations shown in FIGS. 1 to 4, 6, 7, etc. are used, and the reference numerals and names attached to these figures are appropriately used.

[0142] As shown in FIG. 9, in the electrolysis tank 11, in addition to the discharge portion 59, a discharge portion 110 is provided. The discharge portion 110 has a pipe 110A for discharging the precipitate that has settled from the electrode portion 55 in the electrolysis tank 11 and an opening / closing portion 110B for opening and closing this pipe 110A. The discharge portion 110 functions to take in the precipitate inside the pipe 110A at a position lower than the electrode portion 55 and discharge the precipitate from the electrolysis tank 11 through the pipe 110A. The opening / closing portion 110B is, for example, a shut-off valve that switches between a state of blocking the pipe 110A and a state of opening it by manual operation. Note that the opening / closing portion 110B may be an electromagnetic valve or the like whose opening and closing are switched by control. In any case, when the opening / closing portion 110B is in the open state, the breeding water is discharged from the vicinity of a predetermined position in the electrolysis tank 11 through the pipe 110A. When the precipitate precipitates near the predetermined position, the precipitate is discharged through the pipe 110A together with the breeding water.

[0143] In the example of Fig. 9, in addition to the inclined portions 58A and 58B, an inclined portion 58C is provided. The inclined surface of the inclined portion 58C is inclined with respect to the vertical direction, and the inclined portion 58C guides an object that sinks along the inclined surface of the inclined portion 58C to move in the vertical direction and in a second direction orthogonal to the first direction (specifically, to move toward the discharge portion 59 side in the second direction). Further, in the example of Fig. 9, an inclined portion 58D is provided. The inclined surface of the inclined portion 58D is inclined with respect to the vertical direction, and the inclined portion 58D guides an object that sinks along the inclined portion 58D to move in the second direction (specifically, to move toward the discharge portion 110 side in the second direction).

[0144] In the example of Fig. 9, in the reaction tank 15 as well, a discharge portion 112 is provided. The discharge portion 112 has a pipe 112A for discharging the precipitate that has sunk in the reaction tank 15 and an opening / closing portion 112B for opening and closing the pipe 112A. The discharge portion 112 functions to take in a sinking object into the inside of the pipe 112A and discharge it through the pipe 112A. The opening / closing portion 112B is, for example, an opening / closing plug that switches between a state of blocking the pipe 112A and a state of opening it by manual operation. Note that the opening / closing portion 112B may be an electromagnetic valve or the like whose opening and closing are switched by control. In any case, when the opening / closing portion 112B is in the open state, the breeding water is discharged through the pipe 112A from near a predetermined position in the reaction tank 15. When an object precipitates near the predetermined position, the object is discharged through the pipe 112A together with the breeding water. In the reaction tank 15 as well, inclined portions 58E and 58F are provided. The inclined surfaces of the inclined portions 58E and 58F are inclined with respect to the vertical direction, and each of the inclined portions 58E and 58F guides an object that sinks along the inclined surface of each inclined portion to move in the second direction (specifically, to move toward the discharge portion 112 side in the second direction).

[0145] Note that in the example of Fig. 9, the pipes 59A, 110A, and 112A are fixed pipes that are permanently installed, but they may be pipes that can be attached and detached. Also, for any of the pipes, when discharging, it may be discharged by utilizing the water pressure in the tank, or it may be discharged by suction or flowing by means of a pump or the like.

[0146] <Fourth Embodiment> The following description relates to the fourth embodiment. The circulating water treatment system 1 according to the fourth embodiment and the aquaculture method using this system 1 are different from the first embodiment in that, instead of the configuration shown in FIG. 7, the configuration shown in FIG. 10 is used. In addition to the configuration of FIG. 7, it is different from the first embodiment in that a switching unit 140 is provided in the middle of the flow path 46, and other configurations are the same as those of the first embodiment. Therefore, in the following description, for configurations other than the switching unit 140, it is assumed that the configurations shown in FIGS. 1 to 7 are used, and the reference numerals and names attached to these figures are appropriately used.

[0147] In the circulating water treatment system 1 of the fourth embodiment, a switching valve 142 is provided in the switching unit 140. The switching valve 142 can switch the path through which the breeding water discharged from the residual chlorine removal tank (for example, the activated carbon tank 21) to the flow path 46 flows, either to the flow path 143A that does not pass through the second removal unit 146 or to the flow path 143B that passes through the second removal unit 146.

[0148] The second removal tank 144 is configured as a flow path through which the breeding water passes, and the internal space of the flow path is filled with a component for removing residual chlorine (for example, calcium sulfite particles), thereby constituting the second removal unit 146. The second removal tank 144 is configured as a flow path having an inlet and an outlet. In a representative example, the internal space is filled with calcium sulfite particles. When the switching valve 142 is set so that the outflow destination from the switching valve 142 becomes the flow path 143B, the breeding water that has passed through the switching valve 142 and flowed into the inlet of the second removal tank 144 passes through the gaps in the internal space of the second removal tank 144 (the gaps between a large number of calcium sulfite particles). In this process, the residual chlorine and residual ozone contained in the breeding water are removed by the calcium sulfite, and the breeding water discharged from the outlet of the second removal tank 144 to the downstream flow path 46 becomes breeding water from which part or all of the chlorine and ozone have been removed.

[0149] In such a configuration, when the concentration of residual chlorine detected by the second residual chlorine sensor 27 is equal to or lower than the reference value, the control device 52 switches the switching valve 142 so that the breeding water flows through the flow path 143A from the residual chlorine removal tank (for example, the activated carbon tank 21) and does not flow through the flow path 143B. On the other hand, when the concentration of residual chlorine detected by the second residual chlorine sensor 27 exceeds the reference value, the control device 52 switches the switching valve 142 so that the breeding water flows through the flow path 143B from the residual chlorine removal tank (for example, the activated carbon tank 21) and does not flow through the flow path 143A. By doing so, when the concentration of residual chlorine detected by the second residual chlorine sensor 27 becomes relatively high, the breeding water from the residual chlorine removal tank (for example, the activated carbon tank 21) can be switched to flow through the second removal unit 146, and the second removal unit 146 can also remove the residual chlorine. Note that the control method described here is merely an example, and the timing and period for flowing the breeding water through the second removal tank 144 are not limited to the above example.

[0150] <Other Embodiments> The present invention is not limited to the embodiments described above with reference to the description and drawings. For example, the features of the above-described or below-described embodiments can be combined in any combination without contradiction. Also, any feature of the above-described or below-described embodiments can be omitted if it is not explicitly specified as essential. Further, the above-described embodiments may be modified as follows.

[0151] In the above-described embodiment, ozone is supplied as a gas to the foam separator 7 to generate bubbles containing ozone, but a configuration may be adopted in which a gas other than ozone (for example, air) is supplied to generate bubbles of the other gas.

[0152] In the above-described embodiment, the internal region of the electrolysis tank 11 configured as a tank having a portion for storing the breeding water is the second region, but the electrolysis tank 11 may be configured as a flow path not having a portion for storing, and this internal region may be defined as the second region.

[0153] In the above-described embodiment, the reaction tank 15 is configured as a tank having a portion for storing the breeding water, but it may be configured as a flow path having no portion for storing.

[0154] In the above-described embodiment, the first residual chlorine sensor 19 is arranged to detect the concentration of residual chlorine in the breeding water in the filtration tank 17, but it may be configured to detect the concentration of residual chlorine in the flow path between the reaction tank 15 and the activated carbon tank 21.

[0155] In the above-described embodiment, the internal region of the activated carbon tank 21 configured as a tank having a portion for storing the breeding water is the third region, but the activated carbon tank 21 may be configured as a flow path having no portion for storing, and this internal region may be the third region.

[0156] In the above-described embodiment, the internal region of the standby tank 25 configured as a tank having a portion for storing the breeding water is the fourth region, but the standby tank 25 may be configured as a flow path having no portion for storing, and this internal region may be the fourth region.

[0157] In the above-described embodiment, as shown in FIGS. 1 and 7, as the residual chlorine removal tank, the activated carbon tank 21 having the activated carbon part 23 filled with activated carbon particles is provided. However, instead of the activated carbon particles of the activated carbon part 23, calcium sulfite particles may be used, and a configuration in which the calcium sulfite particles are filled may be adopted. Also in this example, the residual chlorine removal tank can be configured as a flow path having an inlet and an outlet, and the internal space of the flow path can be configured to be filled with calcium sulfite particles. Also in this example, in the process where the breeding water flowing in from the inlet of the residual chlorine removal tank passes through the gaps in the internal space (gaps between a large number of calcium sulfite particles), the residual chlorine and residual ozone contained in the breeding water are removed by the calcium sulfite, and the breeding water discharged from the outlet becomes the breeding water from which part or all of the chlorine and ozone have been removed.

[0158] In the configuration of FIG. 10 of the fourth embodiment, the switching unit 140 is provided in the middle of the flow path 46. However, in any of the configurations of the first to third embodiments, the switching unit 140 may be provided in the middle of the flow path 47 (for example, at the position of the two-dot chain line X in FIG. 1) in the configuration of FIG. 1. In this case, by performing the same control as in the above-described fourth embodiment, the path through which the breeding water discharged from the standby tank 25 to the flow path 47 flows is switched to either the flow path 143A that does not pass through the second removal unit 146 or the flow path 143B that passes through the second removal unit 146, and the breeding water that has passed through either the flow path 143A or the second removal unit 146 may be configured to be supplied to the breeding tank 3.

[0159] It should be considered that all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed this time, and it is intended that all modifications within the scope shown by the claims or within the scope equivalent to the claims are included.

Explanation of Reference Numerals

[0160] 1: Circulating water treatment system 3: Breeding tank 5: Removal unit 7: Foam separator 9: Ozone generator 11: Electrolysis tank 11A: First breeding water flow chamber 11B: Second breeding water flow chamber 11C: Third breeding water flow chamber 11Z: Bottom wall 13: Electrolysis section 15: Reaction tank 17: Filtration tank 19: First residual chlorine sensor 21: Activated carbon tank (residual chlorine removal tank) 23: Activated carbon section (residual chlorine removal section) 25: Standby tank 27: Second residual chlorine sensor 29: Ammonium ion sensor 31: Treatment section 35: Temperature control machine 37: Filter 41, 42, 43, 44, 45, 46, 47: Flow path 51: Voltage application unit 52: Control device 53: Drive circuit 54A: Conductive path 54B: Conductive path 55: Electrode part 55A: First electrode 55B: Second electrode 55C: Electrode holding part 56: First induction path 57: Water flow generation part 57A: First partition wall 57B: Second partition wall 58: Induction part 58A, 58B: Inclined part 59: Discharge part 59A: Pipe 59B: Opening / closing part 60: Storage tank 60A: Bottom 62: Introduction part 64: Derivation part 66: Discharge part 72: Second induction path W1: Water surface W2: Water surface W3: Water surface

Claims

1. A circulating treatment system that treats the breeding water in a breeding tank for cultivating aquatic organisms and containing saline water outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, comprising: In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids; In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the breeding water and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water; In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine; having; further comprising an ozone generation unit that generates ozone; The removal unit includes a foam separator that generates foam containing ozone generated by the ozone generation unit and adsorbs the solids contained in the breeding water in the first region to the foam; The residual chlorine removal unit removes residual ozone in the third region A circulating water treatment system for cultivating aquatic organisms.

2. Including an ammonium ion sensor that detects ammonium ions contained in the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank The circulating water treatment system for cultivating aquatic organisms according to claim 1.

3. A circulating treatment system that treats the breeding water in a breeding tank for cultivating aquatic organisms and containing saline water outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, comprising: In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids; In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the breeding water and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water; In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine; having; The fourth area includes an ammonium ion sensor that detects ammonium ions contained in the breeding water, the fourth area being stored or flowing in the fourth area before the breeding water that has passed through the third area is returned to the breeding tank. A circulating water treatment system used for cultivating aquatic organisms.

4. The removal unit includes: a storage tank for storing the rearing water introduced from a region preceding the removal unit; An introduction section that introduces the rearing water stored in the storage tank into the foam separator; An outlet portion that returns the rearing water that has passed through the foam separator to the storage tank; a discharge unit that discharges the rearing water stored in the storage tank to a region subsequent to the removal unit; Equipped with A circulating water treatment system for use in cultivating the aquatic organisms according to claim 1 or 2.

5. A circulating treatment system for cultivating aquatic organisms, which treats salty water in a breeding tank outside the breeding tank, and then circulates the treated water back to the breeding tank, a removal unit that removes at least solid matter in a first area where the breeding water sent from the breeding tank is stored or flows; an electrolysis unit that generates a chlorine acid compound by electrolyzing the breeding water in a second region in which the breeding water that has passed through the first region flows or is stored therein, and reacts the generated chlorine acid compound with ammonia or ammonium ions in the breeding water; a residual chlorine removal section that removes at least residual chlorine in a third area in which the rearing water that has passed through the second area is stored or flows; having The removal unit includes: A foam separator that generates foam and adsorbs the solid matter contained in the breeding water in the first area to the foam; a storage tank for storing the rearing water introduced from a region preceding the removal unit; An introduction section that introduces the rearing water stored in the storage tank into the foam separator; An outlet portion that returns the rearing water that has passed through the foam separator to the storage tank; a discharge unit that discharges the rearing water stored in the storage tank to a region subsequent to the removal unit; Equipped with A circulating water treatment system used for cultivating aquatic organisms.

6. The removal section introduces the rearing water supplied from a region preceding the removal section into the foam separator through an inlet passage, passes the rearing water through the foam separator, and delivers the rearing water to a region following the removal section, which is different from the region of the introduction source where the inlet of the inlet passage is located. The circulating water treatment system used for culturing aquatic organisms according to claim 1 or claim 2.

7. A circulating treatment system that treats the breeding water in a breeding tank for culturing aquatic organisms and containing saline breeding water outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, In a first region where the breeding water sent from the breeding tank is stored or flows, a removal unit that removes at least solids, In a second region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that generates a chlorate compound by electrolyzing the breeding water and reacts the generated chlorate compound with ammonia or ammonium ions in the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, a residual chlorine removal unit that removes at least residual chlorine, having, The removal unit includes a foam separator that generates foam and adsorbs the solids contained in the breeding water in the first region to the foam. After introducing the breeding water supplied from the region in the previous process of the removal unit into the foam separator through an introduction path, it is passed through the foam separator and led out to a region in the subsequent process of the removal unit different from the region of the introduction source where the inlet of the introduction path is arranged The circulating water treatment system used for culturing aquatic organisms.

8. Comprising a control unit that controls the electrolysis of the electrolysis unit based on the measurement result of the ammonium ion sensor The circulating water treatment system used for culturing aquatic organisms according to claim 2 or claim 3.

9. Including a residual chlorine sensor that detects residual chlorine contained in the breeding water in a region where the breeding water that has passed through the second region is stored or flows before returning to the breeding tank, The control unit controls the electrolysis of the electrolysis unit based on the measurement results of the ammonium ion sensor and the residual chlorine sensor The circulating water treatment system used for culturing aquatic organisms according to claim 8.

10. Including a residual chlorine sensor that detects residual chlorine contained in the breeding water in a region where the breeding water that has passed through the second region is stored or flows before returning to the breeding tank The circulating water treatment system used for culturing aquatic organisms according to claim 1 or claim 2.

11. A residual chlorine sensor that detects residual chlorine contained in the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank; A treatment unit that, when a predetermined measurement result is obtained by the residual chlorine sensor, stops removing residual chlorine from the breeding water in the fourth region or stops returning the breeding water in the fourth region to the breeding tank; The circulating water treatment system for aquaculture according to claim 1 or claim 2, comprising:

12. The treatment unit includes a neutralizing agent supply unit that supplies a neutralizing agent that causes a neutralization reaction with residual chlorine to the breeding water before returning to the breeding tank when the detection value of the residual chlorine sensor exceeds a predetermined value. The circulating water treatment system for aquaculture according to claim 11.

13. An electrolysis tank in which the breeding water that has passed through the removal unit is stored or flows; A reaction tank in which the breeding water that has passed through the electrolysis tank is stored or flows, and a reaction time between the chlorate compound generated in the electrolysis tank and ammonia or ammonium ions contained in the breeding water is ensured; A residual chlorine removal tank in which the breeding water that has passed through the reaction tank is stored or flows; A standby tank in which the breeding water that has passed through the residual chlorine removal tank is stored or flows, and the water quality of the breeding water before returning to the breeding tank is inspected; A first residual chlorine sensor that detects residual chlorine contained in the breeding water from when it passes through the electrolysis tank until it flows into the residual chlorine removal tank; A second residual chlorine sensor that detects residual chlorine contained in the breeding water in the standby tank; A control unit that controls the electrolysis of the electrolysis unit based on the measurement result of the ammonium ion sensor and the measurement result of the first residual chlorine sensor; A treatment unit that, when a predetermined measurement result is obtained by the second residual chlorine sensor, stops removing residual chlorine from the breeding water in the fourth region or stops returning the breeding water in the fourth region to the breeding tank; comprising: The second region includes at least the internal region of the electrolysis tank; The third region includes at least the internal region of the residual chlorine removal tank; The fourth region includes at least the internal region of the standby tank. The circulating water treatment system for aquaculture according to claim 2 or claim 3.

14. A pH sensor that measures the pH of the breeding water in a fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank; Based on the measurement results of the pH sensor, a pH adjustment unit that adjusts the pH of the fourth region or the region from the fourth region to the breeding tank. The circulating water treatment system for aquaculture according to claim 1 or claim 2, which has the above.

15. A removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine. The breeding water in the breeding tank, which is a tank for breeding aquatic organisms and contains salt water, is treated outside the breeding tank, and then the treated breeding water is circulated back to the breeding tank. A circulating treatment system is used. In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solids are removed by the removal unit. In the second region where the breeding water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the breeding water to generate chlorate compounds, and the generated chlorate compounds are reacted with ammonia or ammonium ions in the breeding water. In the third region where the breeding water that has passed through the second region is stored or flows, at least residual chlorine is removed by the residual chlorine removal unit. Furthermore, an ozone generation unit for generating ozone is provided in the circulating treatment system. In the removal unit, a foam separator is provided. The foam separator generates foam containing ozone generated by the ozone generation unit, and adsorbs the solids contained in the breeding water in the first region to the foam. The residual chlorine removal unit removes at least residual chlorine and residual ozone in the third region. A method for cultivating aquatic organisms.

16. In the fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, ammonium ions contained in the breeding water are detected by an ammonium ion sensor. The method for cultivating aquatic organisms according to claim 15.

17. A removal unit for removing solids, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine. The breeding water in the breeding tank, which is a tank for breeding aquatic organisms and contains salt water, is treated outside the breeding tank, and then the treated breeding water is circulated back to the breeding tank. A circulating treatment system is used. In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solid matter is removed by the removing unit, In the second region where the breeding water that has passed through the first region is stored or flows, the breeding water is electrolyzed by the electrolysis unit to generate a chloric acid compound, and the generated chloric acid compound is reacted with ammonia or ammonium ions in the breeding water, In the third region where the breeding water that has passed through the second region is stored or flows, at least residual chlorine is removed by the residual chlorine removing unit, Furthermore, in the fourth region where the breeding water that has passed through the third region is stored or flows before returning to the breeding tank, ammonium ions contained in the breeding water are detected by an ammonium ion sensor Aquatic organism cultivation method.

18. A removal unit for removing solid matter, an electrolysis unit for performing electrolysis, and a residual chlorine removal unit for removing at least residual chlorine, and using a circulation type treatment system that circulates the breeding water in the breeding tank that contains the breeding water containing salt and is used for cultivating aquatic organisms back to the breeding tank after treating the breeding water outside the breeding tank, In the first region where the breeding water sent from the breeding tank is stored or flows, at least the solid matter is removed by the removing unit, In the second region where the breeding water that has passed through the first region is stored or flows, the breeding water is electrolyzed by the electrolysis unit to generate a chloric acid compound, and the generated chloric acid compound is reacted with ammonia or ammonium ions in the breeding water, In the third region where the breeding water that has passed through the second region is stored or flows, at least residual chlorine is removed by the residual chlorine removing unit, Furthermore, in the removing unit, a foam separator that generates foam and adsorbs the solid matter contained in the breeding water in the first region to the foam, a storage tank for storing the breeding water, an introduction unit for introducing the breeding water into the foam separator, a discharge unit for returning the breeding water to the storage tank, and a discharge unit for discharging the breeding water are provided. In the removal section, the breeding water introduced from the area of the previous process of the removal section is stored in the storage tank, the breeding water stored in the storage tank is introduced into the foam separator by the introduction section, the breeding water that has passed through the foam separator is returned to the storage tank by the discharge section, and the breeding water stored in the storage tank is discharged to the area of the subsequent process of the removal section by the discharge section. Aquaculture method for aquatic organisms.

19. A removal section for removing solids, an electrolysis section for performing electrolysis, and a residual chlorine removal section for removing at least residual chlorine, and a breeding tank for breeding aquatic organisms and storing breeding water containing salt. A circulation type treatment system is used to treat the breeding water outside the breeding tank and then circulate the treated breeding water back to the breeding tank. By the removal section, at least the solids are removed in the first region where the breeding water sent from the breeding tank is stored or flows. By the electrolysis section, the breeding water is electrolyzed in the second region where the breeding water that has passed through the first region is stored or flows to generate a chlorate compound, and the generated chlorate compound is reacted with ammonia or ammonium ions in the breeding water. By the residual chlorine removal section, at least residual chlorine is removed in the third region where the breeding water that has passed through the second region is stored or flows. Furthermore, in the removal section, a foam separator is provided that generates foam and adsorbs the solids contained in the breeding water in the first region onto the foam. In the removal section, the breeding water supplied from the area of the previous process of the removal section is introduced into the foam separator through an introduction path, then passed through the foam separator, and led to the area of the subsequent process of the removal section, which is different from the area of the introduction source where the inlet of the introduction path is arranged. Aquaculture method for aquatic organisms.

20. The electrolysis of the electrolysis section is controlled by a control unit based on the measurement result of the ammonium ion sensor. The aquaculture method for aquatic organisms according to claim 16 or claim 17.

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