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

Abstract

To provide a circulation type water treatment system capable of efficiently decomposing ammonia or ammonium ions in water by a method for suppressing dependence on lives.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 solids 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 performs electrolysis to the breeding water in a second region where breeding water passed through the first region is stored or is circulated, for generating a chloric acid compound, and 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-loop aquaculture system is known. The closed-loop 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-loop aquaculture system, a method that utilizes microorganisms for decomposition and purification of nitrogen compounds in 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 activity 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 only the purification method using microorganisms is adopted as in Patent Document 1, there is a problem that the purification ability depends on organisms.

[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 organisms in the cultivation of aquatic organisms.

Means for Solving the Problems

[0007] A circulating water treatment system used for 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 is stored or flows, an electrolysis unit that generates chlorate compounds by electrolyzing the breeding water and reacts the generated chlorate compounds 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 A circulating water treatment system used for cultivating aquatic organisms.

[0008] A method for cultivating aquatic organisms, which is one of the present disclosures, has 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 uses 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, the removal unit removes at least the solids in a first region where the breeding water sent from the breeding tank is stored or flows, In the second region where the breeding water 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, the residual chlorine removal unit removes at least residual chlorine. A method for culturing aquatic organisms.

Advantages of the Invention

[0009] The technology according to the present disclosure can more effectively decompose ammonia or ammonium ions in water in a method with reduced dependence on organisms.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0011] Each of the following [1] to

[45] is an example of a characteristic technique included in the present disclosure.

[0012] 〔1〕 A circulating water treatment system that circulates the breeding water in a breeding tank that is a tank for breeding aquatic organisms and contains saline breeding water back to the breeding tank after treating the breeding water outside the breeding tank, in a first region where the breeding water sent from the breeding tank is stored or flows, a removal section 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 section 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 section that removes at least residual chlorine, and having A circulating water treatment system for use in the cultivation of aquatic organisms.

[0013] 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 described in [1] above produces the following first actions and effects. First, the circulating water treatment system described in [1] above can remove solids contained in the breeding water in the first region by the removal unit. Furthermore, the circulating water treatment system described in [1] above can decompose ammonia or ammonium ions by the electrolysis unit. Moreover, by electrolyzing the breeding water containing salts, 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 reliably suppressed. Furthermore, since the circulating water treatment system described in [1] above can remove the residual chlorine in the third region by the residual chlorine removal unit, even if the chloric acid compound not used in the decomposition remains in the breeding water in the third region, this chloric acid compound can be removed. Thus, in the circulating water treatment system described in [1] above, it is possible to reliably suppress the remaining of solids such as feces and uneaten feed in the breeding water, 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 the purification and detoxification of the breeding water. And such an effect can be realized by a method that suppresses dependence on organisms.

[0014] 〔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 aquaculture of aquatic organisms according to [1].

[0015] The above-described [2] circulating water treatment system 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 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 interfering substances. However, since the above-described [2] circulating water treatment system can perform detection of ammonium ions in the fourth region after performing removal with activated carbon in the third region, it is possible to accurately detect fluctuations in the concentration of ammonium ions in the breeding water from which interfering substances have been effectively removed.

[0016] 〔3〕 It is provided with a control unit that controls 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].

[0017] The above-described [3] circulating water treatment system can accurately measure fluctuations in the concentration of ammonium ions in breeding water from which interfering substances have been effectively removed, and then use this measurement result to control electrolysis. Therefore, this circulating water treatment system can perform electrolysis according to the degree of ammonium ions present in the fourth region after passing through the residual chlorine removal unit.

[0018] 〔4〕 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, A control unit that controls electrolysis of the electrolysis unit based on the measurement result of the residual chlorine sensor, and is provided with The circulating water treatment system used for aquaculture of aquatic organisms according to any one of [1] to [3].

[0019] The above-mentioned [[4]] 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 can control the electrolysis of the electrolysis unit according to the degree of residual chlorine.

[0020] [[5]] A residual chlorine sensor for detecting residual chlorine contained in the breeding water in a region where the breeding water passing 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 [[3]].

[0021] [[6]] A residual chlorine sensor for detecting residual chlorine contained in the breeding water in a fourth region where the breeding water passing 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 for removing residual chlorine from the breeding water in the fourth region or stopping the return of the breeding water in the fourth region to the breeding tank, having The circulating water treatment system for aquaculture of aquatic organisms according to any one of [[1]] to [[5]].

[0022] The above-mentioned [[6]] circulating water treatment system can, depending on the degree of residual chlorine contained in the breeding water after passing through the third region, remove residual chlorine from the breeding water in the fourth region or stop the return of the breeding water in the fourth region to the breeding tank, and can suppress the risk that the breeding water containing residual chlorine is directly returned to the breeding tank.

[0023] [[7]] A first residual chlorine sensor for detecting residual chlorine contained in the breeding water until the breeding water passing through the second region flows into the third region, A second residual chlorine sensor for detecting residual chlorine contained in the breeding water in a fourth region where the breeding water passing through the third region is stored or flows before returning to the breeding tank, A control unit that controls the electrolysis of the electrolysis unit based on 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 returning the breeding water in the fourth region to the breeding tank; having A circulating water treatment system for culturing aquatic organisms according to any one of [1] to [6].

[0024] In the circulating water treatment system of [7] above, the residual chlorine contained in the breeding water can be inspected by the second residual chlorine sensor in the fourth region where the breeding water passing through the third region is stored or flows before returning to the breeding tank. Furthermore, in this circulating water treatment system, the residual chlorine contained in the breeding water until the breeding water passing through the second region flows into the third region can also be inspected by the first residual chlorine sensor. And, in this circulating water treatment system, 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 first residual chlorine sensor. When the measurement result of the second residual chlorine sensor (the degree of residual chlorine contained in the breeding water after passing through the third region) is a predetermined measurement result, it is possible to 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 it is possible to suppress the risk that the breeding water containing residual chlorine is directly returned to the breeding tank.

[0025] A pH sensor that measures the pH of the breeding water in the fourth region where the breeding water passing 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 results of the pH sensor; having A circulating water treatment system for culturing aquatic organisms according to any one of [1] to [7].

[0026] The above-mentioned [[8]] circulating water treatment system can decompose ammonia or ammonium ions based on electrolysis in the electrolysis section, and after removing residual chlorine by the residual chlorine removal section, the pH of the breeding water before returning to the breeding tank can be inspected by a pH sensor. In the method of removing residual chlorine by the residual chlorine removal section in the post-process of the electrolysis section as in the above configuration, there is a concern that the pH of the breeding water after passing through the residual chlorine removal section may vary. Therefore, as in the [[8]] circulating water treatment system, if the pH of the breeding water is inspected by a pH sensor in the fourth region downstream of the residual chlorine removal section 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 the highly accurate measurement result.

[0027] [[9]] Having a biological tank that reduces ammonia or ammonium ions in the breeding water by organisms in the region until the breeding water sent out from the breeding tank flows into the second region A circulating water treatment system for aquaculture according to any one of [[1]] to [[8]].

[0028] The above-mentioned [[9]] circulating water treatment system can reduce ammonia or ammonium ions by a biological tank at a stage prior to decomposing ammonia or ammonium ions by an electrolysis section. Therefore, compared with a configuration in which the reduction of ammonia or ammonium ions contained in the breeding water is performed only by the electrolysis section, the burden on the electrolysis section can be suppressed, and it is also easy to suppress the power consumption required for electrolysis. On the other hand, since it is not a configuration in which the reduction of ammonia or ammonium ions contained in the breeding water is performed only by the biological tank, ammonia or ammonium ions in the water can be more effectively decomposed by a method that suppresses dependence on organisms. Further, the above-mentioned [[9]] circulating water treatment system generates a chloric acid compound (for example, sodium hypochlorite) in the second region into which the breeding water passing through the biological tank flows, so that not only the removal of ammonia or ammonium ions but also the sterilization and inactivation of viruses can be performed when the breeding water passing through the biological tank contains bacteria and viruses.

[0029] 〔10〕 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 it is a tank for culturing aquatic organisms and the culture water containing salt is stored. After treating the culture water in the culture tank outside the culture tank, a circulation type treatment system is used to circulate the treated culture water back to the culture tank. In the first region where the culture water sent from the culture tank is stored or flows, at least the solids are removed by the removal unit. In the second region where the culture water that has passed through the first region is stored or flows, the electrolysis unit electrolyzes the culture water to generate a chloric acid compound, and reacts the generated chloric acid compound with ammonia or ammonium ions in the culture water. In the third region where the culture water that has passed through the second region is stored or flows, at least the residual chlorine is removed by the residual chlorine removal unit. A method for culturing aquatic organisms.

[0030] The method for culturing aquatic organisms in the above

[10] has the same effect as [1].

[0031] 〔11〕 A circulation type treatment system that is a tank for culturing aquatic organisms and after treating the culture water in the culture tank containing salt outside the culture tank, circulates the treated culture water back to the culture tank, In the first region where the culture water sent from the culture tank is stored or flows, a removal unit for removing at least solids, In the second region where the culture water that has passed through the first region is stored or flows, an electrolysis unit that generates a chloric acid compound by electrolyzing the culture water and reacts the generated chloric acid compound with ammonia or ammonium ions in the culture water, In the third region where the culture water that has passed through the second region is stored or flows, a residual chlorine removal unit for removing at least residual chlorine, and has 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 onto the foam. The residual chlorine removal unit removes residual ozone in the third region. A circulating water treatment system for aquaculture of aquatic organisms.

[0032] 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, the circulating water treatment system described in

[11] has the following first actions and effects. First, the circulating water treatment system described in

[11] can remove the solids contained in the breeding water in the first region by the removal unit. Furthermore, in the second region after passing through the first region, the circulating water treatment system described in

[11] can decompose ammonia or ammonium ions by the electrolysis unit, and moreover, by electrolyzing the breeding water containing salt, a chloric acid compound (for example, sodium hypochlorite) is generated, and then this chloric acid compound can be reacted with ammonia or ammonium ions present in the breeding water and directly decomposed into nitrogen. Therefore, in the process of decomposition, the generation of nitrous acid, nitric acid, etc. can be surely suppressed. Moreover, since the circulating water treatment system described in

[11] performs electrolysis of the breeding water after removing solids by the removal unit, it can surely suppress the inhibition of electrolysis by solids and is easy to perform electrolysis well. Furthermore, since the circulating water treatment system described in

[11] can remove the residual chlorine in the third region by the residual chlorine removal unit, even if the chloric acid compound not used in 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 described in

[11] , 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, nitrous acid, and nitric acid. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0033] Furthermore, the circulating water treatment system described in

[11] also has the following second actions and effects. This circulating water treatment system can generate foam containing ozone generated in the ozone generation unit with a foam separator, and can adsorb 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 can not only remove solids, but also perform sterilization and disinfection with ozone, and can surely suppress the influence of viruses, bacteria, and parasites, which are factors inhibiting the growth of aquatic organisms. 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 for removing solids.

[0034] 〔12〕 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 〔11〕.

[0035] The circulating water treatment system of the above 〔12〕 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 the 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 circulating water treatment system of the above 〔12〕 can remove solids in the first region, perform removal with 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 interfering substances have been effectively removed.

[0036] A circulation-type treatment system for treating the breeding water in a breeding tank that is a tank for breeding aquatic organisms and contains salt-containing 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 removing portion 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 portion 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 removing portion that removes at least residual chlorine, and has, 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.

[0037] Even in the circulation-type water treatment system of the above

[13] , the above-described first actions and effects occur. Therefore, even in the circulation-type water treatment system of the above

[13] , 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.

[0038] The circulation-type water treatment system of the above

[13] 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 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 the above

[13] can remove solid matter in the first region, remove residual chlorine with a 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, fluctuations in the concentration of ammonium ions can be accurately detected.

[0039]

[14] 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, comprises The circulating water treatment system for aquaculture use according to any one of

[11] to

[13] .

[0040] When the circulating water treatment system described in the above

[14] removes solid matter with a removal unit, the breeding water introduced from the region of the previous process is temporarily stored in a storage tank, introduced from this storage tank into a 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 in other processes is less likely to fluctuate significantly.

[0041] A circulating treatment system for treating the breeding water in a breeding tank for culturing aquatic organisms and containing saline 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 removing 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, an electrolysis part for generating a chloric acid compound by electrolyzing the breeding water and reacting 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 removing part for removing at least residual chlorine, and having The removing part 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 introduced from the region in the previous process of the removing part, An introduction part for introducing the breeding water stored in the storage tank into the foam separator, A leading-out part for returning the breeding water that has passed through the foam separator to the storage tank, A discharging part for discharging the breeding water stored in the storage tank to the region in the subsequent process of the removing part, and comprising A circulating water treatment system for culturing aquatic organisms.

[0042] Even in the circulating water treatment system of the above

[15] , the above-mentioned first actions and effects occur. Therefore, even in the circulating water treatment system of the above

[15] , 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 purifying and detoxifying the breeding water.

[0043] The circulating water treatment system described above in

[15] further provides the following actions and effects. This circulating water treatment system can be operated so that when removing solids with the removal unit, the rearing water introduced from the previous process area is temporarily stored in a storage tank, and then introduced from this storage tank into the foam separator to remove solids, and then returned to the foam separator. If the removal unit is configured in this way, the storage tank acts as a buffer in the process of circulating the rearing water, and even if the speed of introduction into the foam separator or the speed of discharge from the foam separator differs from the circulation speed in other processes, the water level is unlikely to fluctuate significantly in the other processes.

[0044]

[16] The removal section introduces the rearing water supplied from a region upstream of the removal section into the foam separator through an inlet passage, passes the rearing water through the foam separator, and discharges the rearing water to a region downstream of the removal section different from the region of the introduction source where an inlet of the inlet passage is located. A circulating water treatment system for cultivating aquatic organisms according to any one of

[11] to

[13] .

[0045] In the above-mentioned circulating water treatment system

[16] , when solids are removed by the removal section, rearing water supplied from a previous process area is introduced into the foam separator through an inlet passage, and then passed through the foam separator and discharged to a subsequent process area different from the source area where the inlet of the inlet passage is located. This allows the circulating rearing water to pass through the foam separator more reliably, thereby further enhancing the effect of removing solids and the effect of sterilization and disinfection by ozone.

[0046]

[17] 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, comprising: 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; In a second region where the breeding water that has passed through the first region is stored or flows, a chloric acid compound is generated by electrolyzing the breeding water, and the generated chloric acid compound is reacted with ammonia or ammonium ions in the breeding water, an electrolysis unit; 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 solid matter 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, the foam separator is passed through, and it is 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. A circulating water treatment system for aquaculture.

[0047] Even in the circulating water treatment system of the above

[17] , the above-described first action and effect occur. Therefore, even in the circulating water treatment system of the above

[17] , it is possible to surely suppress the remaining of solid matter 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 breeding water.

[0048] Furthermore, the circulating water treatment system of the above

[17] further exhibits the following actions and effects. When the circulating water treatment system of the above

[17] removes solid matter 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, the foam separator is passed through, and it is led out to a region in the subsequent process 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 solid matter and the effects of sterilization and disinfection by ozone can be further enhanced.

[0049] 〔18〕 Comprising a control unit that controls the electrolysis of the electrolysis unit based on the measurement result of the ammonium ion sensor The circulation type water treatment system used for culturing aquatic organisms as described in

[12] or

[13] .

[0050] The circulation type water treatment system of

[18] can accurately measure the fluctuation of the concentration of ammonium ions in the breeding water from which harmful substances have been effectively removed, and can control electrolysis by using this measurement result. Therefore, this circulation type water treatment system can perform electrolysis according to the degree of ammonium ions present in the fourth region after passing through the residual chlorine removal section.

[0051] 〔19〕 includes 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 measurement results of the residual chlorine sensor. The circulation type water treatment system used for culturing aquatic organisms as described in

[18] .

[0052] The circulation type water treatment system of

[19] can control 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 residual chlorine removal section.

[0053] 〔20〕 includes 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 circulation type water treatment system used for culturing aquatic organisms as described in any one of

[11] to

[19] .

[0054] The circulation type water treatment system of

[20] 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.

[0055] As controls and processes applying the configuration of the above

[20] , 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.

[0056] 〔21〕 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, 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, The circulating water treatment system for aquaculture of aquatic organisms according to any one of

[11] to

[19] , which has the above.

[0057] Regarding the circulating water treatment system of the above

[21] , depending on the degree of residual chlorine contained in the breeding water after passing through the third region, it is possible to 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 it is possible to suppress the risk that the breeding water containing residual chlorine is directly returned to the breeding tank.

[0058] 〔22〕 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 of aquatic organisms according to

[20] or

[21] .

[0059] Since the above-described [

[22] ] circulating water treatment system can supply a neutralizing agent that causes a neutralization reaction with residual chlorine to the breeding water before returning to the breeding tank when the detected value of the residual chlorine sensor exceeds a predetermined value, 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.

[0060] 〔23〕 An electrolysis tank in which the breeding water that has passed through the removal section is stored or flows, A reaction tank in which the breeding water that has passed through the electrolysis tank is stored or flows, and the reaction time between the chloric acid 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 the residual chlorine contained in the breeding water from the time 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 section based on the measurement results of the ammonium ion sensor and the measurement results of the first residual chlorine sensor, A treatment unit that, when a predetermined measurement result is obtained by the second residual chlorine sensor, 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, 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 any one of [

[12] ], [

[13] ], [

[18] ], and [

[19] ].

[0061] The above-described [

[23] ] 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 reliably 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 the 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 using a 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 third 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 of the breeding water containing residual chlorine being directly returned to the breeding tank.

[0062] 〔24〕 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 of aquatic organisms according to any one of 〔11〕 to 〔23〕.

[0063] The above-mentioned [

[24] ] circulating water treatment system can decompose ammonia or ammonium ions based on electrolysis in the electrolysis unit, and then remove residual chlorine by the residual chlorine removal unit. After that, the pH of the breeding water before returning to the breeding tank can be inspected by a pH sensor. In the method of removing residual chlorine by the residual chlorine removal unit in the subsequent 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, like the [

[24] ] circulating water treatment system, if the pH of the breeding water is inspected by 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 the highly accurate measurement result.

[0064] [

[25] ] 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 culturing aquatic organisms and storing breeding water containing salt. After treating the breeding water in the breeding tank outside the breeding tank, a circulating treatment system is used to circulate the treated breeding water back to 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 chloric acid compound, and the generated chloric acid 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. A foam separator is provided in the removal unit. 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 by 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.

[0065] Even in the method for culturing aquatic organisms described in

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

[25] 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.

[0066] Furthermore, the culturing method described in

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

[25] 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, not only the removal of solids but also sterilization and disinfection by ozone can be performed during the process in which the breeding water in the first region passes through the foam separator, and the influence of viruses, bacteria, and parasites, which are factors that inhibit the growth of aquatic organisms, can be surely suppressed. Moreover, by the characteristic technique of allowing ozone to act on the foam separator that removes solids, sterilization and disinfection can be performed more efficiently and effectively.

[0067] 〔26〕 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, ammonium ions contained in the breeding water are detected by an ammonium ion sensor. The method for culturing aquatic organisms according to

[25] .

[0068] In the above-mentioned aquaculture method

[26] , ammonium ions contained in the breeding water can be inspected in the fourth region after the decomposition of ammonia and ammonium ions in the second region. However, when detecting ammonium ions in breeding water containing salts 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 carried out 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

[26] , solid matter can be 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.

[0069] 〔27〕 A circulation-type treatment system having 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 circulating the breeding water in a breeding tank that has an aquaculture tank for culturing aquatic organisms and contains breeding water containing salts after treating the breeding water outside the breeding tank and then 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, at least the solid matter is 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 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 removal unit. 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.

[0070] Even in the method for culturing aquatic organisms described in

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

[27] 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.

[0071] The above-described culturing method according to

[27] further produces the following actions and effects. This culturing method 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 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 misrecognize 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, since the culturing method according to

[27] can perform solid removal in the first region, removal by the residual chlorine removal unit in the third region, and then detection of 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 the interfering substances have been effectively removed.

[0072]

[28] 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 treat the breeding water in a breeding tank that is a tank for culturing aquatic organisms and contains salt-containing breeding water outside the breeding tank and then circulate the treated breeding water back to the breeding tank. 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, in 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, an introduction unit that introduces the breeding water into 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 culture method.

[0073] Even in the aquatic organism culture method of the above

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

[28] , 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, nitrous acid, and nitric acid. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0074] The above-described culture method of

[28] further produces the following actions and effects. In this culture method, when the solids are removed by the removal unit, the rearing water introduced from the previous process area can be temporarily stored in a storage tank, and then introduced from this storage tank into the foam separator to remove the solids, and then returned to the foam separator. If the removal unit is configured in this way, the storage tank acts as a buffer in the process of circulating the rearing water, and even if the speed of introduction into the foam separator or the speed of discharge from the foam separator differs from the circulation speed in other processes, the water level is unlikely to fluctuate significantly in the other processes.

[0075]

[29] A circulation treatment system is used, which has 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 which treats the breeding water in a breeding tank, which is a tank for cultivating aquatic organisms and contains salt-containing breeding water, outside the breeding tank, and then circulates the treated breeding water back to the breeding tank, The removal unit removes at least the solid matter in a first area in which the breeding water sent from the breeding tank is stored or flows; the electrolysis unit electrolyzes the breeding water in a second region in which the breeding water that has passed through the first region is stored or flows, thereby generating a chlorite compound, and reacting the generated chlorite compound with ammonia or ammonium ions in the breeding water; The residual chlorine removal unit 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; Further, a foam separator is provided in the removal unit to generate foam and adsorb the solid matter contained in the breeding water in the first region to the foam, In the removal section, the rearing water supplied from a region upstream of the removal section is introduced into the foam separator through an inlet passage, and then the rearing water passes through the foam separator and is discharged to a region downstream of the removal section, which is different from the region from which the rearing water is introduced, where the inlet of the inlet passage is located. A method for cultivating aquatic organisms.

[0076] Even in the method for culturing aquatic organisms described in

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

[29] 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, nitrous acid, and nitric acid. Therefore, it is extremely advantageous in terms of purification and detoxification of the breeding water.

[0077] In the culturing method described in

[29] 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 by 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 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.

[0078] 〔30〕 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

[26] or

[27] .

[0079] The culturing method described in

[30] above can accurately measure the variation in 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 according to the degree of ammonium ions present in the fourth region after passing near the residual chlorine removal unit.

[0080] 〔31〕 An electrolysis device used in a circulating water treatment system that circulates and treats the breeding water from a breeding tank that houses aquatic organisms and contains breeding water containing salt, and returns the treated breeding water to the breeding tank. In a region where the breeding water is stored or flows, an electrolysis unit is provided that generates a chloric acid compound by electrolyzing the breeding water and decomposes ammonia or ammonium ions in the breeding water by reacting the generated chloric acid compound with ammonia or ammonium ions in the breeding water. The electrolysis unit includes an electrode unit having a first electrode and a second electrode disposed in the region, and a voltage application unit that applies a voltage between the electrodes of the first electrode and the second electrode. The voltage application unit switches between a first state in which electrolysis is performed in the region by applying a voltage with the first electrode as the anode and the second electrode as the cathode, and a second state in which a voltage is applied with the second electrode as the anode and the first electrode as the cathode. An electrolysis device for aquaculture.

[0081] The electrolysis device of the above

[31] generates a chloric acid compound (for example, sodium hypochlorite) by electrolyzing breeding water containing salt, and then reacts this chloric acid compound with ammonia or ammonium ions present in the breeding water to directly decompose it into nitrogen. During the decomposition process, the generation of nitrous acid, nitric acid, etc. can be reliably suppressed. However, when this method is adopted, if no measures are taken, there is a concern that deposits will adhere to the surface of the electrode and inhibit electrolysis. However, the above electrolysis device can switch between a first state in which electrolysis is performed by applying a voltage with the first electrode as the anode and the second electrode as the cathode, and a second state in which a voltage is applied with the second electrode as the anode and the first electrode as the cathode. Therefore, the deposits adhering to the surface of the electrode due to continuous electrolysis are likely to detach from the electrode due to the switching. Therefore, this electrolysis device can easily remove the deposits deposited on the surface of the electrode.

[0082] The electrode unit includes an electrode holding unit that holds the first electrode and the second electrode, and the first electrode, the second electrode, and the electrode holding unit are integrally formed. In the above-described circulation type water treatment system, an electrolysis tank configured such that the breeding water is stored or flows is provided, and the interior of the electrolysis tank is the above-described region. The integrally formed electrode part is attachable to and detachable from the electrolysis tank. The electrolysis device for aquatic organism breeding according to

[31] .

[0083] In the electrolysis device of the above

[32] , since the electrode part in which the first electrode, the second electrode, and the electrode holding part are integrally formed is configured to be attachable to and detachable from the electrolysis tank, the work of removing the electrode part for cleaning becomes easier. In particular, the promotion of the detachment of the deposit due to switching and the facilitation of the attachment / detachment work of the electrode part exhibit a synergistic effect, and further facilitation of cleaning is achieved.

[0084] 〔33〕 It includes an electrolysis tank configured such that the breeding water is stored or flows, the interior of the electrolysis tank is the above-described region, and further includes a guiding part that guides and collects the deposits that have sunk from the electrode part in the electrolysis tank toward a predetermined position in the electrolysis tank. The electrolysis device for aquatic organism breeding according to

[31] or

[32] .

[0085] In the electrolysis device of the above

[33] , since the deposits that have sunk from the electrode part can be automatically collected toward a predetermined position by the guiding part, not only can the deposits be detached from the electrode part, but also the detached deposits can be easily collected.

[0086] 〔34〕 It includes an electrolysis tank configured such that the breeding water is stored or flows, the interior of the electrolysis tank is the above-described region, and further includes a discharge part having a pipe for discharging the deposits that have sunk from the electrode part in the electrolysis tank, the discharge part takes in the deposits inside the pipe at a position lower than the electrode part, and discharges the deposits from the electrolysis tank through the pipe. The electrolysis device for aquaculture according to any one of

[31] to

[33] .

[0087] Since the electrolysis device of the above

[34] can take in and discharge the precipitate that has sunk from the electrode part into the pipe at a position below the electrode part, it is possible to suppress the precipitate from being dispersed during the process of discharging the precipitate and easily flowing into the subsequent process.

[0088] 〔35〕Comprising an electrolysis tank configured such that the breeding water is stored or flows, The inside of the electrolysis tank is the above-mentioned area, Furthermore, the electrolysis tank has a guiding path that does not guide the water located below a predetermined height inside the electrolysis tank to the outside of the electrolysis tank, and guides the water located above the predetermined height to the outside of the electrolysis tank. The electrolysis device for aquaculture according to any one of

[31] to

[34] .

[0089] The electrolysis device of the above

[35] can guide the supernatant water located above a predetermined height to the outside, and can make it difficult to guide the precipitate that has sunk below the predetermined height to the outside of the electrolysis tank.

[0090] 〔36〕The predetermined height is above the lower end of the electrode part. The electrolysis device for aquaculture according to

[35] .

[0091] In the electrolysis device of the above

[36] , it becomes difficult for the precipitate that detaches from the electrode part and sinks downward from the lower end to be guided to the outside of the electrolysis tank.

[0092] 〔37〕Comprising an electrolysis tank configured such that the breeding water is stored or flows, The inside of the electrolysis tank is the above-mentioned area, The electrode part is arranged on the water surface side of the breeding water in the electrolysis tank. Furthermore, it is provided with a water flow generating unit that causes the breeding water introduced into the electrolysis cell from the outside of the electrolysis cell to flow upward from the lower side to the upper side of the electrode unit in the electrolysis cell. The electrolysis device for aquaculture according to any one of

[31] to

[36] .

[0093] Since the electrolysis device of

[37] above can generate a water flow so as to rise upward from the lower side to the upper side of the electrode unit in the electrolysis cell, new breeding water is likely to be introduced to the electrode unit, and the efficiency of electrolysis can be further enhanced.

[0094] 〔38〕 The voltage application unit periodically switches between an operation of electrolyzing the breeding water while continuing the first state and an operation of electrolyzing the breeding water while continuing the second state. The electrolysis device for aquaculture according to any one of

[31] to

[37] .

[0095] The electrolysis device of

[38] above can periodically detach deposits and can periodically clean the electrodes.

[0096] 〔39〕 A circulating water treatment system for aquaculture including the electrolysis device for aquaculture according to any one of

[31] to

[38] , 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 which is the region where the breeding water that has passed through the first region is stored or flows, an electrolysis unit that electrolyzes the breeding water, In a third region where the breeding water that has passed through the second region is stored or flows, an activated carbon unit that removes at least residual chlorine with activated carbon, A circulating water treatment system for aquaculture including the same.

[0097] The above-mentioned [

[39] ] circulating water treatment system can remove solids contained in the breeding water in the first region by a removal unit. Further, in the second region after passing through the first region, this circulating water treatment system can decompose ammonia or ammonium ions by an electrolysis unit, and perform electrolysis of the breeding water after removing solids by the removal unit, so that it is possible to surely suppress solids from inhibiting electrolysis and it is easy to perform electrolysis well. Further, in the third region where the breeding water passing through the second region is stored or flows, residual chlorine can be removed by activated carbon. Therefore, even if a chlorate compound not used for the decomposition of ammonia or ammonium ions is contained in the breeding water in the third region, this chlorate compound can be effectively removed by the activated carbon unit. Thus, in the above-mentioned circulating water treatment system, 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, ammonium ions, nitrous acid, and nitric acid are also surely suppressed, which is extremely advantageous in terms of purification and detoxification of the breeding water.

[0098] 〔40〕 A circulating water treatment system for aquaculture equipped with an electrolysis device for aquaculture according to any one of 〔31〕 to 〔38〕, an electrolysis tank configured such that the breeding water is stored or flows, a reaction tank configured such that the breeding water discharged from the electrolysis tank is stored or flows, comprising the inside of the electrolysis tank being the region, the electrolysis tank having a first guiding path that does not guide water located below a first height in the electrolysis tank to the outside of the electrolysis tank and guides water located above the first height to the outside of the electrolysis tank, the reaction tank having a second guiding path that does not guide water located below a second height in the reaction tank to the outside of the reaction tank and guides water located above the second height to the outside of the reaction tank Circulating water treatment system for aquaculture.

[0099] For the above-mentioned circulating water treatment system of

[40] , since the supernatant water located above the first height in the electrolysis tank can be induced outside the electrolysis tank, when deposits detach from the electrodes and sink, it is difficult for the deposits to be induced outside the electrolysis tank. Even if some deposits are discharged from the electrolysis tank and enter the reaction tank, since the supernatant water located above the second height in the reaction tank can be induced outside the reaction tank, the deposits that enter the reaction tank are likely to precipitate in the reaction tank and are difficult to be induced outside the reaction tank.

[0100] 〔41〕 An electrolysis method used in a circulating water treatment system that treats while circulating the breeding water from a breeding tank that is a tank for cultivating aquatic organisms and contains saline breeding water, and returns the treated breeding water to the breeding tank. Using an electrolysis unit having a first electrode and a second electrode, and a voltage application unit that applies a voltage between the electrodes of the first electrode and the second electrode. With the first electrode and the second electrode arranged in the region where the breeding water is stored or flowing, a voltage is applied between the electrodes by the voltage application unit to electrolyze 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 to decompose the ammonia or ammonium ions in the breeding water. The voltage application unit switches between a first state in which the voltage is applied so that the first electrode is the anode and the second electrode is the cathode to perform the electrolysis in the region, and a second state in which the voltage is applied so that the second electrode is the anode and the first electrode is the cathode. Electrolysis method for aquaculture.

[0101] The electrolysis method of

[41] above generates a chloric acid compound (e.g., sodium hypochlorite) by electrolyzing breeding water containing salts, and then reacts this chloric acid compound with ammonia or ammonium ions present in the breeding water to directly decompose it into nitrogen. During the decomposition process, the generation of nitrous acid, nitric acid, etc. can be reliably suppressed. However, when this method is adopted, if no measures are taken, there is a concern that deposits will adhere to the surface of the electrodes and inhibit electrolysis. The above electrolysis method can be switched between a first state in which voltage is applied with the first electrode as the anode and the second electrode as the cathode for electrolysis, and a second state in which voltage is applied with the second electrode as the anode and the first electrode as the cathode. Therefore, the deposits adhering to the surface of the electrodes due to continuous electrolysis are likely to detach from the electrodes due to the switching. Thus, this electrolysis method facilitates the removal of the deposits deposited on the surface of the electrodes.

[0102]

[42] Using an electrolysis cell configured such that the breeding water is stored or flows, Arranging the electrode part so that the inside of the electrolysis cell is the region, Continuing the water introduction of the breeding water into the electrolysis cell and the drainage of the breeding water from the electrolysis cell, while replacing the breeding water, performing the operation in the first state, the operation in the second state, and the switching between the first state and the second state by the voltage application unit The electrolysis method for aquaculture organisms described in

[41] .

[0103] The electrolysis method of

[42] above can perform the operation in the first state, the operation in the second state, and the switching between the first state and the second state while continuously replacing the breeding water by continuously introducing the breeding water into the electrolysis cell and draining the breeding water from the electrolysis cell. Therefore, it is possible to clean the electrodes while circulating the breeding water more efficiently.

[0104]

[43] Periodically switching between the operation of continuously electrolyzing the breeding water in the first state and the operation of continuously electrolyzing the breeding water in the second state by the voltage application unit The electrolysis method for aquaculture described in

[41] or

[42] .

[0105] The electrolysis method of the above

[43] can periodically remove the precipitate and can periodically clean the electrodes.

[0106] 〔44〕 In any of the techniques of 〔1〕~〔43〕, the breeding water containing the salt is a liquid with an NaCl content of 0.5% by mass or more.

[0107] <First Embodiment> 1. Outline of the circulating water treatment system 1 used for aquaculture of aquatic organisms The circulating water treatment system 1 illustrated in Fig. 1 is a system used for aquaculture of aquatic organisms. 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 containing salt after treating it outside the breeding tank 3 and then returns the treated breeding water to the breeding tank 3, and is a system that circulates and uses 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 the 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 and returned to the breeding tank 3 again while continuously breeding the aquatic organisms inside the breeding tank 3.

[0108] 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. Further, 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 listed as preferred examples, and other types (for example, squid, octopus, etc.) may also be used.

[0109] 2. Configuration and operation of each part (Breeding tank) The breeding tank 3 shown in Fig. 1 is a tank for breeding and cultivating aquatic organisms. Inside the breeding tank 3, breeding water containing salts such as artificial seawater or natural seawater is stored, and aquatic organisms such as fish and shellfish are bred in this breeding water. Note that the "breeding water containing salts" stored in the breeding tank 3 is preferably a liquid with an NaCl content of 0.5 mass% or more. 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 induced to be collected in 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. Note that 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.

[0110] (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 induced into 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 unit 62, a lead-out unit 64, and a discharge unit 66. In Fig. 3 and the like, the symbol W conceptually indicates a part of the circulating breeding water.

[0111] 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.

[0112] The ozone generator 9 corresponds to an example of an ozone generation unit, 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. For example, a method of supplying the ozone generated by the ozone generator 9 from an inlet provided in a bubble generation section in a known foam separator for introducing air can be mentioned. The foam separator 7 operates to generate foam containing the ozone generated by the ozone generator 9 and adsorb solids contained in the breeding water in the first region where the breeding water sent from the breeding tank 3 is stored or flows to the foam. In the example of FIG. 3, the first region is the internal region of the storage tank 60.

[0113] The introduction section 62 is a flow path for introducing the breeding water stored in the storage tank 60 into the foam separator 7. The derivation 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 discharge 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 section 5. In the examples of FIGS. 1 and 3, the region of the subsequent process of the removal section 5 is the region inside the electrolysis tank 11.

[0114] In the removal section 5, solids such as feces and uneaten feed contained in the breeding water introduced into the foam separator 7, removal proteins of metabolites of fish and shellfish, bacteria, viruses, parasites, etc. are attached to 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 air 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 derivation section 64. By such an operation, it is surely suppressed that dirt flows out to the electrolysis tank 11 in the subsequent process, and it is surely suppressed that the dirt obstructs the electrolysis of the electrolysis tank 11.

[0115] In the example of FIG. 3, a 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 part 62 is arranged at a position near the bottom 60A in the storage tank 60, making it easier to take in the breeding water immediately after it is 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 lead-out part 64 to a position closer to the discharge part 66 than the flow path 41. The outlet (the outlet for discharging the breeding water) of the lead-out part 64 is arranged at a position closer to the water surface W1 than the bottom 60A of the storage tank 60. The discharge part 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 part 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 above-mentioned 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 part 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 part 66.

[0116] The configuration of the removal part 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 (the 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.

[0117] In the configuration shown in FIG. 4, the bubble generating unit 8 injects a gas containing ozone generated by the ozone generator 9 into the breeding water flowing in from the introduction unit 62, and contains bubbles of the gas containing ozone in the breeding water passing through the bubble generating unit 8. The breeding water that has passed through the bubble generating unit 8 flows into the foam separation tank 7A through the introduction unit 63 configured as a pipe as 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 unit 64 configured as a pipe. The outlet (discharge port) of the lead-out unit 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 unit 66 configured as a flow path for discharge 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 unit 66.

[0118] (Electrolysis tank) 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-mentioned 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. The electrolysis unit 13 generates a chloric acid compound (for example, sodium hypochlorite) by electrolyzing the breeding water in the above-mentioned second region, and reacts the generated chloric acid compound with ammonia or ammonium ions in the breeding water to decompose ammonia or ammonium ions. Further, in the electrolysis tank 11, since the electrolysis unit 13 generates a chloric acid compound, sterilization, deodorization, and decolorization of the breeding water can be performed.

[0119] In the electrolysis tank 11, electrolysis shown by the following formula (1) is performed. 2NaCl + 3H2O → NaClO + NaCl + 2H2O + H2↑ ··· (1)

[0120] Then, the decomposition of ammonia or the decomposition of ammonium ions is carried out by the chemical reactions shown in the following formulas (2) and (3). 2NH3 + 3NaClO → N2↑ + 3NaCl + 3H2O ···(2) 2NH4 + + 3NaClO → N2↑ + 3H2O + 3NaCl + 2H + ···(3)

[0121] In the electrolysis cell 11 shown in FIG. 5, the internal region of the electrolysis cell 11 is a "region" where the electrode part 55 is arranged and electrolysis is carried out. The electrolysis cell 11 is provided with an electrolysis part 13. The electrolysis part 13 has an electrode part 55 having a first electrode 55A and a second electrode 55B arranged in the above "region" (second region), and a voltage application part 51 that applies a voltage between the electrodes of the first electrode 55A and the second electrode 55B.

[0122] The voltage application part 51 has a control device 52 and a drive circuit 53. The control device 52 is an information processing device having an information processing part, a storage part, a communication part, 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 according to a command from the control device 52.

[0123] 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 detachably attached to the electrolysis cell 11. The configuration for making the electrode unit 55 detachable from the electrolysis cell 11 is not particularly limited. For example, when mounting, the electrode holding part 55C is placed on the mounting table provided in the electrolysis cell 11, and when removing, a configuration in which the electrode holding part 55C is detached from the mounting table can be mentioned. In the example of FIG. 5, a plurality of first electrodes 55A and a plurality of second electrodes 55B are provided, and all of 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 electrodes 55A and the second electrodes 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 the 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 the conductive path 54B. In the example of FIG. 5, the first electrodes 55A and the second electrodes 55B are alternately arranged at intervals.

[0124] The electrode used in the electrolysis cell 11 is preferably a metal material that is not corroded by seawater and has a high generation efficiency of chloric acid compounds. 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 characteristics of a uniform and smooth surface. 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 in which titanium is coated with ruthenium or the like may be used as the anode, or other materials may be used.

[0125] Part or all of the electrode unit 55 is disposed on the water surface W2 side of the breeding water in the electrolysis tank 11, and the breeding water is interposed between the first electrode 55A and the second electrode 55B. On the other hand, a water flow generating unit 57 is provided in the electrolysis tank 11, and the water flow generating unit 57 generates a water flow from the lower side to the upper side (electrode unit side) of the electrode unit 55.

[0126] The water flow generating unit 57 has a structure that causes the breeding water introduced into the electrolysis tank 11 from the outside of the electrolysis tank 11 through the flow path 42 to flow upward from the lower side to the upper side of the electrode unit 55 in the electrolysis tank 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 tank 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 generating unit 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 tank 11. The downstream region is a region downstream of the first partition wall 57A and is a region where the electrode unit 55 is provided. The upstream region is a region upstream of the first partition wall 57A and also upstream of the downstream region.

[0127] In the example of FIG. 5, the upstream region is the internal region of the first breeding water flow chamber 11A constituted by the first partition wall 57A, the outer peripheral wall of the electrolysis tank 11, and the portion of the bottom wall 11Z upstream of the first partition wall 57A, and is a region into which the breeding water flows from the flow path 42. An opening is provided on the bottom wall side in the first breeding water flow chamber 11A for moving the breeding water in the first breeding water flow chamber 11A to the second breeding water flow chamber. In the example of FIG. 5, the opening is constituted by the lower end of the first partition wall 57A, the outer peripheral wall of the electrolysis tank 11, and the bottom wall 11Z.

[0128] 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 on 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 part 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 beyond the second partition wall 57B. Due to such a configuration, in the second breeding water flow chamber 11B, the breeding water is introduced from the lower opening portion, 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 the lower side of the electrode part 55 toward the electrode part 55 side.

[0129] 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 on the downstream side of the first partition wall 57A on the outer peripheral wall and the bottom wall 11Z of the electrolysis cell 11.

[0130] 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 guided 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).

[0131] 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 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.

[0132] In the examples of FIGS. 5 and 6, the opening / closing part 59B is a stop valve that switches, for example, by manual operation between a state of blocking the pipe 59A and a state of opening it. 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 also be a pipe that can be attached to and detached from the electrolytic cell 11. Also, 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.

[0133] 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.

[0134] (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 induction path 56, or may be configured as a flow path following the first induction path 56. When 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 when 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.

[0135] As shown in FIG. 5, a second induction path 72 is provided in the reaction tank 15. The second induction path 72 functions as a flow path so as not to guide the water located below the second height in the reaction tank 15 to the outside of the reaction tank 15, but to guide 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 induction path 72 (the boundary with the second induction 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 induction path 72 exceeding the height of the bottom of the second induction 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 induction path 72 is the second height. The second induction path 72 functions to flow the breeding water in the reaction tank 15 toward the subsequent process of the reaction tank 15.

[0136] 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 the filtration tank 17) may be used.

[0137] 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 chlorine amount, which is the sum of the amount of combined chlorine and the amount of free chlorine contained in the breeding water, is the residual chlorine amount. 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.

[0138] (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, it is a tank provided on the downstream side of the detection area where the first residual chlorine sensor 19 is arranged (the area inside the filtration tank 17 in the example of Fig. 1). The activated carbon tank 21 functions as a tank for removing chlorine acid compounds (such as sodium hypochlorite) generated in the electrolytic cell 11. The activated carbon tank 21 is provided with an activated carbon section 23 equipped with 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 area of the activated carbon tank 21 corresponds to an example of the third area, and it is an area where the breeding water that has passed through the second area is stored or flows.

[0139] In the activated carbon tank 21, for example, it reacts as shown in the following formula (4) to remove excess chlorine acid compounds that were not used for the decomposition of ammonia or ammonium ions. HClO + C → CO + H + + Cl - ···(4)

[0140] The activated carbon tank 21 illustrated in Fig. 5 can be configured, for example, as shown in Fig. 7. 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 through them. In the process of the breeding water flowing in from the inlet 21A of the activated carbon tank 21 passing through the gaps between a large number of 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.

[0141] (Standby tank) The breeding water introduced from the flow path 45 into the activated carbon tank 21 passes through the internal region of the activated carbon tank 21 and 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 region of the standby tank 25 corresponds to an example of the fourth region, and is a region where the breeding water that has passed through the above-described third region is stored or flows before returning to the breeding tank 3.

[0142] The second residual chlorine sensor 27 is a sensor that detects the concentration of residual chlorine contained in the breeding water in the fourth region where the breeding water that has passed through the above-described third region 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.

[0143] The ammonium ion sensor 29 is a sensor that detects the concentration of ammonium ions contained in the breeding water in the fourth region where the breeding water that has passed through the above-described third region 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.

[0144] The pH sensor 28 is a sensor that measures the pH (hydrogen ion exponent) of the breeding water in the fourth region where the breeding water that has passed through the above-described third region 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.

[0145] 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.

[0146] 3. Control of the Recirculating Water Treatment System 1 (Configuration for Control) In the recirculating 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 in the middle of 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, and the like.

[0147] 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-described 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-described 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 exponent) of the breeding water in the above-described 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-described fourth region (specifically, inside the standby tank 25).

[0148] (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.

[0149] When grasping the ammonia concentration and the effective chlorine concentration in the breeding water (for example, seawater) used in the present 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 effective residual chlorine, the higher the addition amount of the chlorate compound, the higher the effective 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 lower than the above-mentioned certain concentration with respect to the concentration of effective residual chlorine, since they are consumed by the reaction with ammonia or ammonium ions, the effective residual chlorine concentration decreases even when a chlorate compound is added. 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 effective 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.

[0150] 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.

[0151] 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 do not exist, 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 it is within the current range where the detection value of the ammonium ion sensor 29 is equal to or less than the first threshold value and within the current range where 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.

[0152] 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 detected value of the ammonium ion sensor 29 without using the detected 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 (detected value) of the ammonium ion concentration detected by the ammonium ion sensor 29 becomes 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 (detected 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 detected 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 detected 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 detected value of the ammonium ion sensor 29 becomes equal to or less than the first threshold value, and when the detected 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.

[0153] 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 a 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 it is in the above-mentioned second state. 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 is decreasing, 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 it is in the above-mentioned third state. 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 detected value of the residual chlorine amount detected in the previous current adjustment control is smaller than the detected 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 the current value decreased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control. If the detected value of the residual chlorine amount detected in the previous current adjustment control is larger than the detected 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 the current value increased by a predetermined ratio (for example, 10%) from the set current value used in the previous current adjustment control.

[0154] (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 area, or may operate to stop returning the breeding water in the fourth area to the breeding tank 3.

[0155] For example, when the concentration (detected value) of 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 area 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 (detected value) of 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 the "neutralizing agent that causes a neutralization reaction with residual chlorine" into the standby tank 25.

[0156] 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 less than or equal to 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.

[0157] 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 through which the breeding water flows 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, a 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 less than or equal to 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 that circulates 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.

[0158] (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.

[0159] 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.

[0160] 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 having a pH higher than the first reference value at a predetermined supply rate, and 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.

[0161] In addition, in order to reduce the consumption of the pH adjuster, solid calcium carbonate (for example, pellets, etc.) may be provided in the fourth region (for example, the inside of the flow paths 46 and 47 and the standby tank 25).

[0162] 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.

[0163] 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 electrolysis tank 11), and applies a voltage so that the second electrode 55B is the anode and the first electrode 55A is the cathode. It operates to switch between the first state and 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.

[0164] 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 the timing when the operation time of the circulation type water treatment system 1 reaches a certain time from the previous switching time point, or may be a timing when a detection value by some sensor becomes a predetermined value, or may be a randomly determined timing, or may be other timings.

[0165] 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 to the electrolysis tank 11 and the drainage of the breeding water from the electrolysis tank 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 the anode and the second electrode 55B is the cathode by the voltage application unit 51 is continuously performed. When the switching condition is satisfied during the operation in the first state, the switching from the first state to the second state is performed 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 the anode and the first electrode 55A is the cathode is continuously performed while performing the above-mentioned "replacement of the breeding water". When the switching condition is satisfied during the operation in the second state, the switching from the second state to the first state is performed while performing the above-mentioned "replacement of the breeding water", and the operation in the first state and the operation in the second state are alternately performed in this manner. 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.

[0166] 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 reacted with ammonia or ammonium ions present in the breeding water to be directly decomposed into nitrogen. 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.

[0167] 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.

[0168] 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 temperatures of 20°C or lower, in low-temperature zones, it is necessary to increase the absolute amount of microorganisms in order to ensure purification and decomposition capabilities. The greater the absolute amount of microorganisms, the larger the required size of the filtration tank becomes. Therefore, in this type of technology, in order to sufficiently perform purification and decomposition whether at normal temperature or low temperature, it is inevitable to have an excessive facility design in which the absolute amount of microorganisms is increased assuming low temperature, and the size of the filtration tank is increased accordingly. 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 the frequency of drug administration and water replacement must be increased, which easily leads to a decrease in productivity and workability.

[0169] 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, pollution elements other than ammonia and ammonium ions (solids such as feces, uneaten feed, and removal proteins of metabolites of fishery products, bacteria, viruses, parasites, etc. contained in the breeding water) can also be effectively removed, and a synergistic effect can be exerted.

[0170] Furthermore, the circulating water treatment system 1 operates to generate foam containing ozone generated by the ozone generator 9 by the foam separator 7, and adsorb the solids contained in the breeding water in the first region to the foam containing ozone. That is, this circulating water treatment system 1 can not only remove solids but also perform sterilization and disinfection with ozone in the process of the breeding water in the first region passing through the foam separator, and can more surely suppress the influence of viruses, bacteria, and parasites, which are factors that inhibit the growth of aquatic organisms. Moreover, with the characteristic technology of applying ozone to the foam separator 7 that removes solids, sterilization and disinfection can be performed more efficiently and effectively.

[0171] Furthermore, the circulating water treatment system 1 can inspect the ammonium ions contained in the breeding water by the ammonium ion sensor 29 in the region after ammonia decomposition in the second region. However, when detecting ammonium ions in the breeding water containing salt 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 circulating 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, since the circulating 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, it can accurately detect fluctuations in the concentration of ammonium ions in the breeding water from which interfering substances have been effectively removed.

[0172] Also, when the circulating water treatment system 1 removes solids by the removal unit 5, the breeding water introduced from the previous process region is temporarily stored in the storage tank 60, and then introduced from this storage tank 60 into the foam separator 7 to remove solids, and then it can be operated to return 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 and the derivation speed from the foam separator 7 are different from the circulation speed of other processes, the water level in other processes is less likely to fluctuate significantly.

[0173] 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. The concentration fluctuation of ammonium ions can be accurately measured in the breeding water from which contaminants have been effectively removed, and 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.

[0174] Furthermore, the circulating water treatment system 1 includes 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 above-described 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 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.

[0175] Furthermore, when a predetermined measurement result is obtained by the second residual chlorine sensor 27 that detects residual chlorine contained in the breeding water in the above-described fourth region, the treatment unit 31 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 3. Depending on the degree of residual chlorine contained in the breeding water after passing through the above-described second region, the circulating water treatment system 1 can stop removing 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.

[0176] When the detection value of the second residual chlorine sensor 27 exceeds a predetermined value, the circulation type 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.

[0177] The circulation type water treatment system generates a chloric acid compound in the electrolysis tank 11 to decompose ammonia or ammonium ions, and ammonia or ammonium ions that cannot be completely decomposed in the electrolysis tank 11 can be reacted 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 circulation type water treatment system 1 can thus more surely react ammonia or ammonium ions, while securing a standby tank 25 in the subsequent process of the activated carbon tank 21, inspecting ammonium ions in the breeding water before returning to the breeding tank 3 with an ammonium ion sensor 29, and inspecting residual chlorine with a 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 with a 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 first residual chlorine sensor 19. On the other hand, depending on the measurement result 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, suppressing the risk that the breeding water containing residual chlorine is directly returned to the breeding tank 3.

[0178] <Second Embodiment> The following description relates to the second embodiment. The circulating 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.

[0179] 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 discharge it 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, the breeding water supplied from the area of the previous process of the removal unit 5 is introduced into the foam separator 7 through the flow path 41 (the flow path 41 corresponds to an example of an introduction path), then passed through the foam separator 7, and discharged 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 entire 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.

[0180] Thus, when the solid matter is removed by the removing 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 discharged to the subsequent process area different from the previous process area. Therefore, the circulating breeding water can surely pass through the foam separator 7, and the effect of removing solid matter and the effect of sterilization and disinfection by ozone can be further enhanced.

[0181] <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 the configuration shown in FIG. 9 is used instead of the configuration shown in FIG. 5. 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 of FIG. 5. Therefore, in the following description, for the configurations other than FIG. 5, it is assumed that the configurations of FIGS. 1 to 4, FIG. 6, FIG. 7, etc. are used, and the reference numerals and names attached to these figures are appropriately used.

[0182] 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 valve for switching the pipe 110A between a blocked state and an open state 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 settles near the predetermined position, the precipitate is discharged through the pipe 110A together with the breeding water.

[0183] 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).

[0184] In the example of FIG. 9, a discharge portion 112 is also provided in the reaction tank 15. 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, inclined portions 58E and 58F are also 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).

[0185] 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.

[0186] <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 the configuration shown in FIG. 10 is used instead of the configuration shown in FIG. 7. 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 the other configurations are the same as those of the first embodiment. Therefore, in the following description, for the 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.

[0187] In the circulating water treatment system 1 of the fourth embodiment, a switching valve 142 is provided in the switching unit 140, and 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 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.

[0188] 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 flows into the inlet of the second removal tank 144 passes through the gaps (gaps between a large number of calcium sulfite particles) in the internal space of the second removal tank 144. In this process, the residual chlorine and residual ozone contained in the breeding water are removed by 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.

[0189] In such a configuration, when the concentration of residual chlorine detected by the second residual chlorine sensor 27 is less than or equal to a reference value, the control device 52 causes the breeding water to flow through the flow path 143A from the residual chlorine removal tank (for example, the activated carbon tank 21), and switches the switching valve 142 so that the breeding water 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 causes the breeding water to flow through the flow path 143B from the residual chlorine removal tank (for example, the activated carbon tank 21), and switches the switching valve 142 so that the breeding water does not flow through the flow path 143A. In this way, when the concentration of residual chlorine detected by the second residual chlorine sensor 27 becomes relatively high, it is possible to switch so that the breeding water from the residual chlorine removal tank (for example, the activated carbon tank 21) flows 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.

[0190] <Other Embodiments> The present invention is not limited to the embodiments described by the above description and drawings. For example, the features of the above-described or below-described embodiments can be combined in any combination within a non-contradictory range. Also, any feature of the above-described or below-described embodiments can be omitted if it is not explicitly stated as essential. Furthermore, the above-described embodiments may be modified as follows.

[0191] 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.

[0192] 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 it may be configured as a flow path that does not have a portion for storing the electrolysis tank 11, and this internal region may be the second region.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] In the above-described embodiment, as shown in FIGS. 1 and 7, as the residual chlorine removal tank, an activated carbon tank 21 having an 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 of the breeding water flowing in from the inlet of the residual chlorine removal tank passing 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.

[0198] 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.

[0199] In any of the above embodiments, a biological tank may be provided in the region until the breeding water sent out from the breeding tank flows into the second region to reduce ammonia or ammonium ions in the breeding water by organisms. In this case, for example, in the circulating water treatment system 1 (FIG. 3) of the first embodiment, a biological tank may be provided between the storage tank 60 and the electrolysis tank 11, and the breeding water flowing out from the storage tank 60 may flow into the biological tank, and the breeding water flowing out from the biological tank may flow into the electrolysis tank 11. Alternatively, in the circulating water treatment system 1 (FIG. 8) of the second embodiment, the breeding water flowing out from the foam separator 7 may flow into the biological tank, and the breeding water flowing out from the biological tank may flow into the electrolysis tank 11. In this example, it is desirable that the biological tank is configured such that the breeding water flowing out from the breeding tank 3 flows in via a flow path or the like and can store the inflowing breeding water. On the other hand, it is desirable that the biological tank holds, for example, nitrifying bacteria (microorganisms) that oxidize ammonia to change it to nitrous acid and then nitric acid as an example of organisms. In the configuration thus formed, ammonia or ammonium ions contained in the breeding water flowing into the biological tank are reduced by the microorganisms, and the breeding water in which ammonia or ammonium ions have been thus reduced flows into the electrolysis tank 11 directly or via another region from the biological tank. The order of the removal unit and the biological tank may be configured such that the breeding water passing through the removal unit flows into the biological tank, or the breeding water passing through the biological tank flows into the removal unit. Alternatively, part or all of the biological tank may be used also as the removal unit. In any case, it is sufficient that part or all of the breeding water flowing out of the breeding tank 3 and flowing into the electrolysis tank 11 flows into the electrolysis tank 11 via the biological tank. In the above example, the biological tank is configured to hold breeding water and microorganisms inside. However, instead of or in addition to this configuration, it may be configured to reduce ammonia or ammonium ions contained in the breeding water by the action of other organisms. Also, the number of biological tanks is not limited to one, and there may be a plurality of them. For example, instead of the above-mentioned "biological tank that holds microorganisms", the biological tank may be configured to breed vegetables and other plants as "organisms". In this case, the breeding water flowing directly from the breeding tank 3 or flowing in via another area is temporarily stored or flowed in the biological tank, and the breeding water in the biological tank is continuously or intermittently supplied to the plants to grow the plants, so that the plants absorb ammonia or ammonium ions in the breeding water to achieve purification. In such a "circulating water treatment system that combines a biological tank and an electrolysis tank", ammonia or ammonium ions can be reduced by the biological tank at a stage prior to the decomposition of ammonia or ammonium ions by the electrolysis unit 13. Therefore, compared with a configuration in which the reduction of ammonia or ammonium ions contained in the breeding water is performed only by the electrolysis unit 13, the burden on the electrolysis unit 13 can be suppressed, and it is easy to suppress the power consumption required for electrolysis. On the other hand, since it is not a configuration in which the reduction of ammonia or ammonium ions contained in the breeding water is performed only by the biological tank, ammonia or ammonium ions in the water can be more effectively decomposed by a method that reduces dependence on organisms. Further, in the above circulating water treatment system, in the second region (the region in the electrolysis tank 11) into which the breeding water passing through the biological tank flows, a chloric acid compound (for example, sodium hypochlorite) is generated. Therefore, not only can ammonia or ammonium ions be removed, but also when the breeding water passing through the biological tank contains bacteria or viruses, sterilization and inactivation of the viruses can be performed.

[0200] It should be considered that all aspects of the embodiments disclosed this time are illustrative and not restrictive. The scope of the present invention is not limited to the embodiments disclosed this time, but is intended to include all modifications within the scope shown by the claims or within the scope equivalent to the claims.

Explanation of Reference Numerals

[0201] 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 unit 15: Reaction tank 17: Filtration tank 19: First residual chlorine sensor 21: Activated carbon tank (residual chlorine removal tank) 23: Activated carbon part (residual chlorine removal part) 25: Standby tank 27: Second residual chlorine sensor 29: Ammonium ion sensor 31: Treatment unit 35: Temperature controller 37: Filter 41, 42, 43, 44, 45, 46, 47: Flow path 51: Voltage application part 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 for treating the breeding water in a breeding tank that houses aquatic organisms and contains saline breeding water outside the breeding tank and then circulating 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 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 A circulating water treatment system for culturing 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 culturing aquatic organisms according to Claim 1.

3. 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 for culturing aquatic organisms according to Claim 2.

4. 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, and A control unit that controls the electrolysis of the electrolysis unit based on the measurement result of the residual chlorine sensor The circulating water treatment system for culturing aquatic organisms according to Claim 1 or Claim 2.

5. Comprising 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, and 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 for culturing aquatic organisms according to Claim 3.

6. 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 When a predetermined measurement result is obtained by the residual chlorine sensor, a treatment unit that stops removing residual chlorine from the breeding water in the fourth region or returning the breeding water in the fourth region to the breeding tank; The circulating water treatment system according to claim 1 or claim 2, which is used for culturing aquatic organisms.

7. A first residual chlorine sensor that detects residual chlorine contained in the breeding water until the breeding water that has passed through the second region flows into the third region; A second residual chlorine sensor that detects residual chlorine contained in the breeding water in a fourth region that is stored or flows before the breeding water that has passed through the third region returns to the breeding tank; A control unit that controls the electrolysis of the electrolysis unit based on the measurement result 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 returning the breeding water in the fourth region to the breeding tank; having The circulating water treatment system according to claim 1 or claim 2, which is used for culturing aquatic organisms.

8. A pH sensor that measures the pH of the breeding water in a fourth region that is stored or flows before the breeding water that has passed through the third region returns 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; The circulating water treatment system according to claim 1 or claim 2, which is used for culturing aquatic organisms.

9. Having a biological tank that reduces ammonia or ammonium ions in the breeding water by organisms in the region until the breeding water sent out from the breeding tank flows into the second region The circulating water treatment system according to claim 1 or claim 2, which is used for culturing aquatic organisms.

10. 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 circulating treatment system that circulates the breeding water in a breeding tank for culturing aquatic organisms and containing saline breeding water back to the breeding tank after treating the breeding water outside the breeding tank; The removal unit removes at least the solids in a first region where the breeding water sent from the breeding tank is stored or flows; In the second region where the breeding water 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, the residual chlorine removing unit removes at least residual chlorine. Aquatic organism cultivation method.

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