Management device, water circulation system, and management method

Abstract

To provide a control method for controlling ultraviolet intensity and a flow rate with optimum power efficiency in order to achieve "a target sterilization rate per unit time".SOLUTION: The management apparatus specifies, as a set flow rate of the pump, a target flow rate of the pump at which a sterilization rate in water per unit time reaches a target sterilization rate within an allowable immersion time after the ultraviolet light source starts irradiating the water with ultraviolet light, based on an ultraviolet light irradiation dose threshold of the ultraviolet light source, an apparatus sterilization rate indicating a sterilization rate in the sterilization treatment apparatus achieved by irradiating the water with ultraviolet light by the ultraviolet light source at the ultraviolet light irradiation dose threshold, and a water volume in a water tank. The ultraviolet irradiation apparatus may further include a specifying unit configured to specify, as an ultraviolet target intensity, an ultraviolet target intensity of the ultraviolet light source that becomes the ultraviolet irradiation amount threshold value when the set flow rate of the pump is set to the target flow rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a management device, a water circulation system, and a management method. [Background technology]

[0002] Patent Document 1 discloses a water sterilization device that sterilizes water by circulating the water through an ultraviolet irradiation tank. [Prior art document] [Patent Documents] [Patent Document 1] Patent No. 3144887 Summary of the Invention [Problem to be solved by the invention]

[0003] In a water circulation system in which water from an aquarium is sterilized by ultraviolet light in a circulation path and then returned to the aquarium, it is desirable to appropriately manage both the ultraviolet light intensity and the water flow rate. [Means for solving the problem]

[0004] A management device according to one aspect of the present invention may be a management device for controlling a water circulation system including a circulation path that purifies water in an aquarium and returns it to the aquarium, a circulation control device that circulates the water in the circulation path using a pump, and a sterilization treatment device that sterilizes the water passing through the circulation path by irradiating it with ultraviolet light from an ultraviolet light source. The management device may include an identification unit that identifies, as a set flow rate of the pump, a target flow rate of the pump at which the sterilization rate in the water per unit time reaches a target sterilization rate within an allowable immersion time from when the ultraviolet light source starts irradiating the water with ultraviolet light, based on an ultraviolet irradiation threshold of the ultraviolet light source, an apparatus sterilization rate indicating a sterilization rate in the sterilization treatment device achieved by irradiating the water with ultraviolet light from the ultraviolet light source at the ultraviolet irradiation threshold, and the volume of water in the aquarium, and identifies, as a set ultraviolet light intensity, a target ultraviolet light intensity of the ultraviolet light source that reaches the ultraviolet irradiation threshold when the set flow rate of the pump is set to the target flow rate.

[0005] The management device may further include an input receiving unit that receives input. Aquatic organisms may be kept in the aquarium. The input receiving unit may receive input of aquatic organism information indicating attributes such as the type, body length, or weight of the aquatic organism, a target bacterial species for sterilization corresponding to the aquatic organism information, and a bacterial concentration in the aquarium. The identification unit may identify an allowable bacterial concentration and an allowable immersion time corresponding to the input aquatic organism information and the target bacterial species for sterilization based on relationship information indicating a relationship between the target bacterial species for sterilization corresponding to the aquatic organism information, an allowable bacterial concentration, and the allowable immersion time, and may further identify a target sterilization rate per unit time for reducing the bacterial concentration to the allowable bacterial concentration within the allowable immersion time, and may identify the ultraviolet irradiation dose threshold and the device sterilization rate that are predetermined according to the target bacterial species for sterilization.

[0006] In any of the management devices, the input receiving unit may receive input of ultraviolet sensitivity information predetermined according to the type of bacteria to be sterilized, and the identification unit may identify the ultraviolet irradiation dose threshold or the device sterilization rate according to the ultraviolet sensitivity information.

[0007] In any of the management devices, the identification unit may refer to a memory unit that stores ultraviolet sensitivity information indicating the ultraviolet sensitivity according to the bacterial species to be sterilized for each type of aquatic organism, identify the ultraviolet sensitivity corresponding to the input aquatic organism information, and identify the ultraviolet irradiation dose threshold or the device sterilization rate according to the identified ultraviolet sensitivity information.

[0008] In any one of the management devices, the specifying unit may specify the target sterilization rate per unit time and the allowable immersion time at a preset time.

[0009] In any of the management devices, the input receiving unit may receive input of water quality information indicating a quality of the water in the circulation path, and the specifying unit may specify the target sterilization rate per unit time further based on the water quality information of the water.

[0010] In any of the management devices, the input receiving unit may receive input of biological information regarding the living body of the aquatic organism, and the identifying unit may identify the target sterilization rate per unit time and the allowable immersion time when the biological information satisfies a predetermined condition indicating a high risk of developing an infectious disease.

[0011] In any of the management devices, the input receiving unit may receive input of flow rate condition information indicating a flow rate condition value according to breeding control of the aquatic organism, and the specifying unit may specify a target flow rate of the circulation path and a target sterilization rate per unit time based on the flow rate condition information.

[0012] In any of the management devices, the identification unit may obtain the transmittance per unit length of water in the tank for the ultraviolet wavelength output by the ultraviolet light source from a transmittance measuring device, and identify the ultraviolet intensity in the water based on the transmittance.

[0013] In any of the management devices, the identification unit may update the ultraviolet intensity of the water based on the intensity of the ultraviolet light output by the ultraviolet light source from the ultraviolet detector, an electrical signal of the ultraviolet light source from the sterilization treatment device, or the accumulated lighting time of the ultraviolet light source from the sterilization treatment device.

[0014] In any one of the management devices, the specifying unit may periodically specify the target sterilization rate per unit time.

[0015] A water circulation system according to one aspect of the present invention may include the management device, the circulation path, the circulation control device, and the sterilization treatment device. The circulation control device may control the pump so that a flow rate of the pump is equal to or greater than a target flow rate. The sterilization treatment device may control the ultraviolet light source so that an ultraviolet intensity of the ultraviolet light source is equal to or greater than the target ultraviolet intensity.

[0016] In the water circulation system, when the allowable immersion time has elapsed since the ultraviolet light source began irradiating the water with ultraviolet rays, the sterilization treatment device may reduce the target ultraviolet intensity of the ultraviolet light source, turn off the ultraviolet light source, or cancel the setting of the target ultraviolet intensity.

[0017] In any of the water circulation systems, the circulation control device may control the pump so that the flow rate of the pump is equal to the target flow rate. The sterilization treatment device may control the ultraviolet light source so that the ultraviolet intensity of the ultraviolet light source is equal to the target ultraviolet intensity.

[0018] In any of the water circulation systems, the water circulation system may be a closed circulation water circulation system in which water is not discharged from the circulation path, or a semi-closed circulation system in which water is poured into and discharged from the circulation path.

[0019] In any of the water circulation systems, the ultraviolet light source may be a UV-C LED having an output peak wavelength in the wavelength band of 220 nm or more and 280 nm or less.

[0020] A management method according to one aspect of the present invention may be a method for managing a water circulation system including a circulation path that purifies water in an aquarium and returns it to the aquarium, a circulation control device that circulates the water in the circulation path using a pump, and a sterilization treatment device that sterilizes the water by irradiating the water passing through the circulation path with ultraviolet light from an ultraviolet light source. The management method may include a step of: an identification unit identifying, based on an ultraviolet irradiation dose threshold of the ultraviolet light source, an apparatus sterilization rate indicating a sterilization rate in the sterilization treatment device achieved by irradiating the water with ultraviolet light from the ultraviolet light source at the ultraviolet irradiation dose threshold, and a water volume of the aquarium, a target flow rate of the pump at which the sterilization rate in the water per unit time reaches a target sterilization rate within an allowable immersion time from when the ultraviolet light source starts irradiating the water with ultraviolet light, and identifying, as a set ultraviolet light intensity, a target ultraviolet light intensity of the ultraviolet light source that becomes the ultraviolet irradiation dose threshold when the set flow rate of the pump is set to the target flow rate.

[0021] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a functional block diagram showing an example of the overall configuration of a closed-circuit water circulation system according to an embodiment of the present invention. [Figure 2] FIG. 2 illustrates an example of functional blocks of a management device. [Figure 3] FIG. 10 is a diagram showing the ratio of the number of times that water in the aquarium circulates through the circulation path. [Figure 4] FIG. 1 is a graph in which the logarithmic sterilization rate in water is plotted against the average circulation number on the horizontal axis, while the logarithmic sterilization rate of the device is changed. [Figure 5] FIG. 10 is a graph plotting the elapsed time until the logarithmic sterilization rate in water reaches 0.5, with the horizontal axis representing the flow rate, while varying the device logarithmic sterilization rate of the sterilization treatment device. [Figure 6] FIG. 10 is a diagram showing an example of the relationship between the proportionality coefficient α and the device logarithmic sterilization rate. [Figure 7] FIG. 10 is a flowchart illustrating an example of a procedure for setting a set flow rate of a pump and a set ultraviolet intensity of an ultraviolet light source. [Figure 8] FIG. 10 is a diagram showing the relationship between the logarithmic sterilization rate in water and the operating time of the sterilization treatment by the sterilization treatment device. [Figure 9] This figure shows an example of relationship information showing the relationship between fish species, which are attributes of aquatic organisms, the bacterial species that are targeted by that fish species, the bacterial concentration that poses an infection risk for that bacterial species, and the allowable immersion time at that bacterial concentration. [Figure 10] 1 is a functional block diagram showing an example of the overall configuration of a semi-closed water circulation system. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0024] 2. Description of the Related Art A closed-loop water circulation system used to cultivate aquatic organisms such as fish is known as a water circulation system in which water from an aquarium is sterilized by ultraviolet light in a circulation path and then returned to the aquarium.

[0025] In closed-circulation water circulation systems used in closed-circulation land-based aquaculture, the possibility of pathogenic microorganisms being introduced is considered extremely low. However, if the fish are carrying the bacteria from the time they are young, or if pathogenic microorganisms are introduced from the outside through feeding, there is a possibility that the aquatic organisms being raised in the system may be exposed to the pathogenic microorganisms for a long period of time, increasing the risk of infection and mass death.

[0026] On the other hand, even if the bacterial concentration in an aquarium is high enough to cause aquatic organisms to become infected with pathogenic microorganisms, if the immersion time, the time the aquatic organisms are exposed to that bacterial concentration, is short, the risk of the aquatic organisms becoming infected with pathogenic microorganisms during that immersion time is low. Therefore, in order to reduce the risk of aquatic organisms becoming infected with pathogenic microorganisms, even if pathogenic microorganisms are introduced into the aquarium, the time the aquatic organisms are exposed to the bacterial concentration that is high enough to cause infection with pathogenic microorganisms must be kept within an acceptable immersion time that keeps the risk of aquatic organisms becoming infected with pathogenic microorganisms low even if the aquatic organisms are exposed to that bacterial concentration. In other words, the bacterial concentration and immersion time in the aquarium must be kept below a safe level to prevent aquatic organisms from becoming infected with pathogens.

[0027] Therefore, in closed-circulation water circulation systems, water is sterilized within the circulation path while being circulated by a pump in the tank. The sterilization method is often deep ultraviolet (UV-C) radiation.

[0028] For example, Patent Document 1 (Patent No. 3144887) discloses a water sterilization device that sterilizes water with ultraviolet light in a water circulation path, although it is not an aquaculture system. In Patent Document 1, even if the number of bacteria in the water whose bacterial concentration has been reduced by sterilization increases again, the number of bacteria is always kept at a safe level by intermittently circulating the water with a pump and sterilizing the water with ultraviolet light.

[0029] In closed-circulation land-based aquaculture, it is necessary to keep the bacterial concentration in the water and the immersion time below a safe level, for example, to achieve a "target sterilization rate per unit time" of 90% or so within about one hour of pathogenic bacteria in the water in the tank. However, there is a problem in that the method for controlling the ultraviolet intensity or the flow rate of the water circulation by pump to achieve this is not clear.

[0030] Therefore, in the closed-circulation water circulation system of this embodiment, the sterilization rate per unit time in the water tank is determined in two ways: in some cases it depends on the ultraviolet intensity, and in other cases it depends only on the water flow rate in the circulation path, with little dependence on ultraviolet intensity. This provides a control method for controlling the ultraviolet intensity and flow rate with optimal power efficiency to achieve the "target sterilization rate per unit time."

[0031] FIG. 1 is a functional block diagram showing an example of the overall configuration of a closed-loop water circulation system 10 according to this embodiment.

[0032] The closed-loop water circulation system 10 includes a water tank 20, a circulation path 22, a sedimentation tank 30, a biological filtration tank 50, a circulation control device 60, a pump 80, a sterilization treatment device 90, and a management device 100.

[0033] The aquarium 20 is a container for storing water (seawater or freshwater) for raising aquatic organisms such as farmed fish. Aquatic organisms 24 may be raised in the aquarium 20. The circulation path 22 is a water flow path that supplies water discharged from the aquarium 20 back to the aquarium 20 via the settling tank 30, the biological filtration tank 50, and the sterilization treatment device 90.

[0034] The settling tank 30 removes foreign matter contained in the water supplied from the water tank 20. The biological filtration tank 50 removes ammonia components dissolved in the water by filtering the water supplied from the settling tank 30 using a filter medium to which microorganisms are attached. The water from the biological filtration tank 50 is supplied to a sterilization treatment device 90 via a pump 80. The devices with various functions for purifying water that are placed in the circulation path 22 are not limited to the devices described above. Furthermore, the locations where each device is placed are merely examples.

[0035] Sterilization treatment device 90 has an ultraviolet light source 92, an ultraviolet intensity meter 94, and a transmittance meter 96. Ultraviolet light source 92 may be a UV-C LED with an output peak wavelength in the wavelength band of 220 nm or more and 280 nm or less. Water supplied via pump 80 is irradiated with ultraviolet light in the UV-C band from ultraviolet light source 92 to sterilize the water. Ultraviolet intensity meter 94 measures the intensity of ultraviolet light irradiated onto the water. Water sterilized by sterilization treatment device 90 is returned to water tank 20 via circulation path 22. Transmittance meter 96 measures the ultraviolet transmittance of the water in circulation path 22.

[0036] Circulation control device 60 controls pump 80 to control the flow rate of water flowing through circulation path 22. Pump 80 has a flow meter 82. Flow meter 82 measures the flow rate (L / min) of water flowing through circulation path 22. Management device 100 is a device that controls the entire closed-circulation water circulation system 10, and sets the target water flow rate that circulation control device 60 should achieve and the target ultraviolet intensity of ultraviolet light source 92 that sterilization treatment device 90 should achieve.

[0037] FIG. 2 is a diagram illustrating an example of functional blocks of the management device 100. The management device 100 may include a computer having a central processing unit (CPU) and memory. The computer may be a personal computer, tablet computer, smartphone, workstation, server computer, general-purpose computer, or a computer system in which multiple computers are connected. Such a computer system is also considered a computer in the broad sense. The computer may be a dedicated computer designed for controlling the closed-loop water circulation system 10, or may be dedicated hardware realized by dedicated circuitry. The computer may be implemented in a virtual computer environment.

[0038] The management device 100 includes a control unit 110, a storage unit 120, an interface unit 130, and an output unit 140. The control unit 110 may be configured with a microprocessor such as a CPU or MPU, or a microcontroller such as an MCU. The storage unit 120 may be a computer-readable non-transitory recording medium, and may include at least one of SRAM, DRAM, EPROM, EEPROM, and flash memory such as a USB memory.

[0039] The interface unit 130 receives input of information from the user that is necessary to identify control values ​​that control the operation of the circulation control device 60 and the sterilization processing device 90. The interface unit 130 may be a keyboard, a touch panel display, or the like. The output unit 140 is a communication interface that outputs the control values ​​identified by the control unit 110 to the circulation control device 60 and the sterilization processing device 90.

[0040] The control unit 110 includes a determination unit 112 and an input reception unit 114. The determination unit 112 determines the ultraviolet irradiation amount threshold Qe th and the ultraviolet exposure threshold Qe thBased on the device sterilization rate, which indicates the sterilization rate in the sterilization treatment device 90 achieved by irradiating the water with ultraviolet light from the ultraviolet light source 92, and the amount of water in the water tank 20, a target flow rate F is set as the set flow rate of the pump 80 at which the sterilization rate in the water per unit time can reach the target sterilization rate within the allowable immersion time after the ultraviolet light source 92 starts irradiating the water with ultraviolet light. t is identified, and the set flow rate of the circulation path 22 is set to the target flow rate F t When set to UV exposure threshold Qe th The UV target intensity E of the UV light source 92 becomes t The output unit 140 outputs the target flow rate F t is output to the circulation control device 60, and the ultraviolet irradiation amount threshold Qe th may be output to the sterilization treatment device 90. The output unit 140 may output the target flow rate F t may be output to the display unit of the circulation control device 60 to prompt the user to specify the set flow rate of the pump 80. th may be output on the display unit of sterilization treatment device 90 to prompt the user to specify the ultraviolet light setting intensity of sterilization treatment device 90. The output unit 140 may output the target flow rate F t and UV exposure threshold Qe th may be output to prompt the user to specify at least one of the set flow rate of pump 80 and the set ultraviolet light intensity of sterilization treatment device 90. In other words, the control value set by specification unit 112 may be set as the control value of circulation control device 60 and sterilization treatment device 90 without the intervention of the user, or may be set as the control value of circulation control device 60 and sterilization treatment device 90 via the user.

[0041] The circulation control device 60 controls the flow rate of the pump 80 to a target flow rate F t The circulation control device 60 controls the pump 80 so that the flow rate of the pump 80 measured by the flow meter 82 is equal to or greater than the target flow rate F t The circulation control device 60 controls the pump 80 so that the flow rate F of the pump 80 is equal to or greater than the target flow rate F t The pump 80 may be controlled so that the pressure is equal to

[0042] The sterilization treatment device 90 is configured such that the ultraviolet intensity E of the ultraviolet light source 92 is equal to or greater than the ultraviolet target intensity E t The sterilization treatment device 90 controls the ultraviolet light source 92 so that the ultraviolet intensity E of the ultraviolet light source 92 measured by the ultraviolet intensity meter 94 is equal to or greater than the ultraviolet target intensity E t The sterilization treatment device 90 controls the ultraviolet light source 92 so that the ultraviolet intensity E of the ultraviolet light source 92 is equal to or greater than the ultraviolet target intensity E t The ultraviolet light source 92 may be controlled so that the UV radiation intensity is equal to

[0043] In order to achieve the target sterilization rate in the water per unit time, the flow rate of the pump 80 needs to be equal to or greater than the target flow rate, and the ultraviolet irradiation amount needs to be equal to or greater than the ultraviolet irradiation amount threshold, but in order to avoid unnecessary power consumption, it is best to make them equal to the respective set values.

[0044] Here, an example of a method for specifying a target sterilization rate per unit time will be shown.

[0045] For example, in the case of a young flounder weighing less than 100g, E. tarda bacteria can be found at 10 4 If young fish are immersed in seawater with a concentration of 10 CFU / ml or more for more than 30 minutes, they may be at risk of contracting Edwardsiellosis. 2 ~10 3 Even if the CFU / ml level is low, the risk of infection increases if young fish are immersed for several hours. In other words, depending on the fish species or growth stage, the bacterial concentration at which the risk of infection is low and the maximum immersion time that must not exceed that bacterial concentration can be specified.

[0046] Possible reasons for the presence of pathogenic microorganisms in the aquarium 20 include bacteria being introduced from the outside and fish infected with pathogenic microorganisms releasing bacteria into the water. In the latter case, bacteria multiply within the fish's body, resulting in a greater number of bacteria than the former case of accidental introduction, and for example, a maximum of 10 3 ~10 4In this way, if the sterilization rate in the aquarium 20 can be increased to a target sterilization rate per unit time so that the bacterial concentration can be reduced from the maximum bacterial concentration expected to be mixed into the aquarium 20 to a bacterial concentration that poses a low risk of infection within the allowable immersion time, the risk of infection for the fish can be reduced.

[0047] For example, if the volume of water in the water tank 20 is V [L] and the flow rate of the pump 80 is F [L / min], then on average the water in the water tank 20 is circulated at a time of V / F [min]. However, it is reasonable to consider that not all of the water in the water tank 20 circulates once, and that the number of times it is circulated follows a statistical probability distribution.

[0048] As an example, consider the number of circulations per unit volume of water using a Poisson distribution model with the number of circulations as a random variable. In this case, the viable bacteria rate in the water tank 20 follows the formula below.

number

[0049] Here, the function Po(n) is the probability mass function of the Poisson distribution, and γ is the sterilization rate (γ<1) when water passes through the sterilization treatment device 90 once.

[0050] FIG. 3 shows a Poisson distribution when the expected value λ=3. FIG. 3 shows the ratio of the number of times the water in aquarium 20 circulates through circulation path 22. In other words, it shows the distribution of the number of times the water in aquarium 20 has circulated. The example shown in FIG. 3 shows that 5% of the total water in aquarium 20 has never been circulated. In other words, no matter how much the water is sterilized by sterilization treatment device 90 in circulation path 22 (no matter how high γ is), the bacteria in this 5% of the water remain in aquarium 20. Therefore, when γ is sufficiently high (close to 1), the viable bacteria rate in aquarium 20 approaches Po(n=0). On the other hand, when γ is low, Po(n≧1) also contributes to the viable bacteria rate.

[0051] 4 shows a graph in which the logarithmic microbial reduction rate in water is plotted against the horizontal axis, with the average circulation frequency λ (random variable) being plotted against the equipment logarithmic microbial reduction rate of sterilization treatment device 90. In this example, it can be seen that even if the equipment logarithmic microbial reduction rate is increased above 2, the change in the logarithmic microbial reduction rate in water is small.

[0052] The average circulation frequency (expected value λ) on the horizontal axis can be considered as the elapsed time T ÷ (V / F), so if the set flow rate of pump 80 is increased, the logarithmic sterilization rate of the device in the water relative to the elapsed time T, i.e., the sterilization rate per unit time, can be increased.

[0053] FIG. 5 is a graph plotting the time elapsed until the logarithmic sterilization rate in water reaches 0.5, with the horizontal axis representing the flow rate, while varying the device logarithmic sterilization rate of sterilization treatment device 90.

[0054] For example, if the target sterilization rate in water per hour is 90%, the elapsed time until the logarithmic sterilization rate in the water reaches 0.5 must be 30 minutes or less. If the device logarithmic sterilization rate is 0.5 and the flow rate F is 20 L / min, to achieve 30 minutes or less, it is necessary to increase the flow rate F, or to increase both the flow rate F and the device logarithmic sterilization rate. The device logarithmic sterilization rate can be increased by increasing the amount of ultraviolet light irradiated by the ultraviolet light source 92. The amount of ultraviolet light irradiated by the ultraviolet light source 92 is the product of the ultraviolet intensity and irradiation time for the water passing through the sterilization treatment device 90, so it can be increased by increasing the ultraviolet intensity. However, it must also be considered that increasing the flow rate F shortens the irradiation time, so it is also necessary to consider that the amount of ultraviolet light irradiated depends on the flow rate F.

[0055] The flow rate F of the pump 80 can be controlled, for example, by changing the rotation speed of the pump 80. The rotation speed of the pump 80 may be changed manually or by changing an electrical signal to an inverter that controls the rotation speed of the pump 80. In addition, as an example, the circulation control device 60 may control the target flow rate F t At this time, the circulation control device 60 may adjust the set flow rate so that the flow rate F measured by the flow meter 82 becomes the desired flow rate.

[0056] When the ultraviolet light source 92 is, for example, a UV-C LED, the sterilization treatment device 90 can change the ultraviolet intensity by changing the drive current supplied to the ultraviolet light source 92. In addition, as an example, the management device 100 determines whether the ultraviolet intensity E of the ultraviolet light irradiated by the ultraviolet light source 92 in the water is equal to or exceeds the ultraviolet target intensity E t The ultraviolet light intensity setting of the sterilization treatment device 90 may be adjusted so that the ultraviolet light intensity E measured by the ultraviolet light intensity meter 94 is equal to or greater than the ultraviolet light target intensity E t The ultraviolet light intensity setting of the sterilization treatment device 90 may be adjusted to adjust the amount of irradiation from the ultraviolet light source 92 so as to achieve the above.

[0057] The power consumption of pump 80 depends on the flow rate, but often exceeds kWh when it is on the order of several tens of L / min. Furthermore, the flow rate is generally proportional to the cube of the power consumption of pump 80. On the other hand, the power consumption of sterilization treatment device 90 is at most on the order of 100 W, and the UV intensity is linearly proportional to the power consumption. Therefore, in order to shorten the time it takes for the logarithmic sterilization rate in the water to reach 0.5, it is better to increase the UV irradiation amount in areas where increasing the UV irradiation amount is effective, and to increase the flow rate of pump 80 in areas where increasing the UV irradiation amount is not effective, as this will result in better overall power efficiency.

[0058] The range of ultraviolet light intensity where increasing the ultraviolet light intensity has no or only a small effect on increasing the sterilization rate depends on the sterilization rate (device sterilization rate) when passing through sterilization treatment device 90. In other words, the range of ultraviolet light irradiation dose where there is no or only a small effect on sterilization rate depends on the sterilization rate (device sterilization rate) when passing through sterilization treatment device 90. In calculations using a Poisson distribution model, as shown in Figure 4, even if the device logarithmic sterilization rate is increased to 2.0 or more, there is only a small change in the effect on increasing the sterilization rate. Therefore, for example, the ultraviolet light irradiation dose at which the device logarithmic sterilization rate becomes 2.0 is set to the ultraviolet light irradiation dose threshold Qe th Alternatively, the ultraviolet irradiation amount when the upper limit of the ultraviolet intensity of the sterilization treatment device 90 is set may be set to the ultraviolet irradiation amount threshold Qe th Since the sterilization rate of the device is not uniquely determined by the target bacteria, the ultraviolet irradiation threshold Qe th The sterilization rate of the device at that time must be input from outside.

[0059] Therefore, the input receiving unit 114 receives input. The input receiving unit 114 receives input from the user via the interface unit 130. The input receiving unit 114 may receive input of the device sterilization rate via the interface unit 130.

[0060] Once the equipment sterilization rate is determined, the function of elapsed time to achieve the water sterilization rate relative to the flow rate F is determined as follows. Therefore, the target flow rate F to achieve the target sterilization rate per unit time (logarithmic sterilization rate) is t is decided. Ft [L / min] = α × V [L] × (target sterilization rate per unit time (1 minute))

[0061] Here, α is a proportionality coefficient determined according to the device sterilization rate. Figure 6 shows an example of the relationship between the proportionality coefficient α and the device sterilization rate (device logarithmic sterilization rate).

[0062] F=F t In order to achieve the target sterilization rate per unit time, the ultraviolet irradiation dose is set to the ultraviolet irradiation dose threshold Qe th However, at this time, the flow rate F must also be taken into consideration and the ultraviolet irradiation threshold Qe th UV target intensity E t It is necessary to control it.

[0063] For example, let the amount of ultraviolet radiation given a flow rate of F1 and an ultraviolet radiation intensity of E1 be Qe1. If the flow rate is changed from F1 to c×F1, the time it takes for water to pass through sterilization treatment device 90 will be 1 / c, so in order to achieve the same amount of ultraviolet radiation Qe1, the ultraviolet radiation intensity must be changed to c×E1.

[0064] Although the target flow rate and ultraviolet irradiation dose threshold are determined by calculation of a probability distribution model, in an actual system, they do not necessarily follow the ideal, so a margin may be added to the theoretical value.

[0065] FIG. 7 is a flowchart of an example of a procedure for setting the set flow rate of the pump 80 and the set ultraviolet intensity of the ultraviolet light source 92.

[0066] The input receiving unit 114 receives the target sterilization rate per unit time and the ultraviolet irradiation dose threshold Qe via the interface unit 130. th The determination unit 112 receives an input of the device sterilization rate at the ultraviolet irradiation amount threshold Qe th Based on the device sterilization rate at t (S102). That is, the determination unit 112 determines the proportionality coefficient α by referring to the relationship information between the proportionality coefficient α and the device sterilization rate (device logarithmic sterilization rate) as shown in FIG. 6, which is stored in the storage unit 120. The determination unit 112 determines the water volume V in the water tank 20 stored in the storage unit 120, and calculates the target flow rate F by α × V[L] × (target sterilization rate per unit time). t is identified as the set flow rate.

[0067] The control unit 110 acquires the flow rate F measured by the flow meter 82 and determines whether the flow rate F is equal to the target flow rate F. t It is determined whether the flow rate F is equal to or greater than the target flow rate F (S104). t If it is not equal to or greater than the target flow rate F, the control unit 110 sends a command to the circulation control device 60 via the output unit 140 to instruct the flow rate F of the pump 80 to exceed the target flow rate F t The set flow rate is adjusted so as to control the rotation speed of the pump 80 (S106).

[0068] Next, the specifying unit 112 determines the ultraviolet irradiation amount threshold Qe th The target ultraviolet intensity E t The ultraviolet ray set intensity is set to the ultraviolet ray irradiation amount threshold Qe th Based on a predetermined relationship between the flow rate and the ultraviolet intensity to achieve the ultraviolet exposure threshold Qe th The target ultraviolet intensity E t Identify the UV target intensity E t For example, when the flow rate is Fn, the ultraviolet irradiation threshold Qe th The ultraviolet intensity at which n In this case, the specification unit 112 calculates (F / Fn)×E n The target UV intensity E tmay be specified.

[0069] The control unit 110 acquires the ultraviolet intensity E measured by the ultraviolet intensity meter 94, and determines whether the ultraviolet intensity E is the ultraviolet target intensity E t It is determined whether the ultraviolet intensity E is equal to or greater than the ultraviolet target intensity E (S110). t If it is not equal to or greater than this, the control unit 110 issues a command to the sterilization treatment device 90 via the output unit 140 to increase the drive current supplied to the ultraviolet light source 92, thereby adjusting the set ultraviolet light intensity of the ultraviolet light source 92 (S112). Alternatively, the set ultraviolet light intensity of the ultraviolet light source 92 may be adjusted based on a previously determined relationship between the drive current of the ultraviolet light source and the ultraviolet intensity, without using the ultraviolet intensity meter 94. For example, the drive current of the ultraviolet light source can be changed by changing a resistance value in a drive current circuit. The set value of this resistance may be adjusted as the actual ultraviolet intensity. If the ultraviolet intensity E is equal to the target ultraviolet intensity E t If so, the control unit 110 ends the process of setting the set flow rate of the pump 80 and the set ultraviolet intensity of the ultraviolet light source 92.

[0070] Through the above process, the closed-loop water circulation system 10 can identify the target ultraviolet light intensity and target flow rate with optimal power efficiency to achieve the target sterilization rate per unit time.

[0071] Figure 8 shows the relationship between the logarithmic reduction rate in water and the operating time of sterilization treatment by sterilization treatment device 90. As shown in Figure 8, the longer the operating time of sterilization treatment by sterilization treatment device 90, the greater the logarithmic reduction rate in water.

[0072] As mentioned above, the target sterilization rate per unit time is set from the expected maximum bacterial concentration to a bacterial concentration that poses a low risk of infection within the allowable immersion time. For example, if the maximum bacterial concentration is 10 3 ~10 4 In the case of CFU / ml, if the target sterilization rate is 90% in 1 hour, it will be 10% after 30 minutes. 4 As shown in Figure 8, after 2 hours or more, or at most 3 hours, the logarithmic reduction rate is 3 or more, and the result is 10 2This calculation results in a concentration below the CFU / ml, reducing the risk of infection. After four hours, the logarithmic reduction rate will be 4, meaning the bacteria will have fallen to the detection limit. Therefore, in this case, the logarithmic reduction rate can be set to 3 until the concentration falls below the target bacterial concentration, or it can be set to 4 for safety.

[0073] In closed-loop land-based aquaculture, bacteria do not grow in the aquarium 20 unless there are fish infected with pathogenic microorganisms, so ultraviolet sterilization is unnecessary if a sufficient amount of sterilization is achieved. When the target ultraviolet light intensity is reduced or hidden, the intensity of the ultraviolet light source may be lowered, lowered, or turned off. The flow rate of the pump 80 may also be changed to any desired intensity. Therefore, in response to the elapse of the allowable immersion time after the ultraviolet light source 92 begins irradiating the water with ultraviolet light, the sterilization treatment device 90 may lower the target ultraviolet light intensity of the ultraviolet light source 92, turn off the ultraviolet light source 92, or cancel the setting of the target ultraviolet light intensity so that the ultraviolet light source 92 is turned off. This reduces power consumption in the sterilization treatment device 90 and extends the life of the ultraviolet light source 92.

[0074] To achieve a safe bacterial concentration that will not infect aquatic organisms, it is necessary to set the target sterilization rate per unit time to an appropriate value based on information about the aquatic organisms, such as their type, growth period, body length, and weight, which is related to their resistance to pathogenic microorganisms, and information about the target bacterial species that are likely to cause infection in the aquatic organisms.

[0075] Therefore, the input receiving unit 114 may receive input of aquatic organism information indicating attributes related to the aquatic organism's resistance to pathogenic microorganisms, such as the type, body length, or weight of the aquatic organism, a bacterial species to be sterilized according to the aquatic organism information, and a bacterial concentration in the aquarium 20. The identifying unit 112 may identify an allowable bacterial concentration and an allowable immersion time according to the input attributes of the aquatic organism and the bacterial species to be sterilized, based on relationship information indicating the relationship between the attributes of the aquatic organism and the bacterial species to be sterilized, and the allowable bacterial concentration and allowable immersion time, and may further identify a target sterilization rate per unit time for reducing the bacterial concentration to the allowable bacterial concentration within the allowable immersion time.

[0076] For example, based on the scale of damage in existing marine aquaculture, bacterial species that are likely to cause disease in aquatic organisms, such as E. tarda, the causative bacterium of Edwardsiellosis, for flounder, or Vibrio for kuruma shrimp, can be identified and stored in advance in the memory unit 120.

[0077] FIG. 9 shows an example of relationship information indicating the relationship between the fish species, which is an attribute of an aquatic organism, the target bacterial species for that fish species, the bacterial concentration that poses an infection risk for that bacterial species, and the allowable immersion time at that bacterial concentration. If the bacterial concentration within the allowable immersion time is below the bacterial concentration that poses an infection risk, the risk of the fish becoming infected with the bacteria can be reduced. The identification unit 112 may identify the allowable bacterial concentration so that it is below the bacterial concentration that poses an infection risk by referring to the relationship information such as that shown in FIG. 9 stored in the memory unit 120.

[0078] For example, the sterilization rate in 1 hour is 90%. For a young flounder weighing less than 100g, the sterilization rate is 90%. 4 Immersion in seawater with a concentration of CFU / ml or higher for more than 30 minutes carries the risk of contracting Edwardsiellosis. 2 ~10 3 Even if the concentration is only around CFU / ml, the risk of infection increases if the fish is immersed for several hours. Possible reasons for the presence of pathogenic microorganisms in an aquarium include bacteria being mixed in from the outside, and fish infected with pathogenic microorganisms releasing bacteria into the water. In the latter case, the bacteria multiply within the fish's body, so the number of bacteria is thought to be higher than in the former case where bacteria are accidentally mixed in, and as an example, the maximum number of bacteria is 10 3 ~10 4 CFU / ml. In other words, for example, the bacterial concentration in a closed-loop water circulation system is 10 3 ~10 4 If the CFU / ml level is about 90% in 1 hour, the sterilization rate will be 10% after 30 minutes. 4 CFU / ml below 10 for at least 2 hours, at most 3 hours. 2 The count falls below CFU / ml, lowering the risk of infection. After 4 or 5 hours, the bacteria levels drop to the detection limit.

[0079] Furthermore, the specifying unit 112 may specify a predetermined ultraviolet irradiation amount threshold and device sterilization rate depending on the type of bacteria to be sterilized.

[0080] As shown in Figure 6, even if the device sterilization rate is increased beyond a certain level, the change in α becomes small. In other words, the contribution of the sterilization rate per unit time to changes in ultraviolet irradiation dose becomes small. Therefore, as an example, the specifying unit 112 may set the device logarithmic sterilization rate (device sterilization rate) at the ultraviolet irradiation dose threshold to 2.0. Furthermore, the specifying unit 112 may set the upper limit of the ultraviolet irradiation dose of the sterilization treatment device 90 as the ultraviolet irradiation dose threshold.

[0081] Furthermore, since the ultraviolet irradiation dose threshold is determined by the sterilization rate for bacteria in water that passes through sterilization treatment device 90 once, the type of bacteria to be sterilized and their ultraviolet sensitivity information are required to determine the ultraviolet irradiation dose threshold and the device sterilization rate at that time. In many cases, the device logarithmic sterilization rate lrv of bacteria has a linear relationship with the ultraviolet irradiation dose Qe, lrv = a × Qe + b. Input receiving unit 114 may receive input of this coefficient a and intercept b as ultraviolet sensitivity information for each type of bacteria to be sterilized.

[0082] The identification unit 112 may identify the ultraviolet sensitivity corresponding to the input aquatic organism information by referencing the storage unit 120, which stores ultraviolet sensitivity information indicating the ultraviolet sensitivity corresponding to the target bacterial species for sterilization for each type of aquatic organism. The identification unit 112 may identify the ultraviolet sensitivity information according to the target bacterial species, and identify the ultraviolet irradiation dose threshold or the device sterilization rate according to the identified ultraviolet sensitivity information. The identification unit 112 may identify the ultraviolet irradiation dose threshold or the device sterilization rate according to the coefficient a and intercept b, which are the identified ultraviolet sensitivity information, according to lrv = a × Qe + b. The identification unit 112 may identify the target ultraviolet intensity based on the ultraviolet sensitivity. The identification unit 112 may identify the target ultraviolet intensity by multiplying the target ultraviolet intensity at the reference ultraviolet sensitivity by the reciprocal of the ultraviolet sensitivity corresponding to the target bacterial species for sterilization.

[0083] In land-based aquaculture using the closed-loop water circulation system 10, it is considered unlikely that the causative bacteria that cause damage in existing marine aquaculture will be introduced. In consideration of this risk, the type of bacteria to be sterilized may be determined.

[0084] 8 in advance in the memory unit 120, the identification unit 112 can set the sterilization rate per unit time to an appropriate value depending on the information on the aquatic organisms and the bacterial species to be sterilized. The identification unit 112 may refer to literature on past infection experiments or conduct a new experiment and store the related information in the memory unit 120 based on the results. This allows the identification unit 112 to identify the target sterilization rate per unit time from the bacterial concentration that poses an infection risk and the allowable immersion time depending on the combination of the bacterial concentration, bacterial species, and aquatic organism that may be mixed into the aquarium 20, or the body length or weight of the aquatic organism.

[0085] Instead of inputting growth information such as body length or weight, a target sterilization rate per unit time based on the minimum size most susceptible to disease may be stored in the memory unit 120 instead of the bacterial concentration that poses an infection risk. Also, the coefficient a and intercept b of lrv = a × Qe + b may be stored in advance in the memory unit 120 as ultraviolet sensitivity information for each bacterial species to be sterilized.

[0086] In this way, when the input receiving unit 114 receives input of minimum aquatic organism information, the identification unit 112 can identify an appropriate target sterilization rate per unit time, ultraviolet irradiation threshold value, and device sterilization rate.

[0087] The control unit 110 may have a timer 116. The determination unit 112 may refer to the time on the timer 116 and determine the target sterilization rate per unit time and the allowable soaking time when a preset time is reached. For example, feeding poses a risk of contamination with pathogenic microorganisms from outside. In many cases, the feeding time is fixed. Therefore, the determination unit 112 may determine the target sterilization rate per unit time at the timing of feeding. In other words, the control unit 110 may start controlling the sterilization treatment device 90 at the timing of feeding, and start sterilizing water with ultraviolet light.

[0088] The specifying unit 112 may periodically specify a target sterilization rate per unit time. The flow rate and UV intensity are set so as to achieve the target sterilization rate per unit time. The flow rate and UV intensity are controlled to an appropriate level, and the system is operated at the target sterilization rate per unit time. This allows for an immediate response to changes in the physical condition of aquatic organisms, and allows for appropriate UV sterilization of water.

[0089] The input receiving unit 114 may receive input of biological information related to the living aquatic organism. If the biological information satisfies a predetermined condition indicating a high risk of developing an infectious disease, the identifying unit 112 may identify a target sterilization rate per unit time and an allowable immersion time.

[0090] For example, if the identification unit 112 can identify a risk of infectious disease development from the biometric information, it may set the target sterilization rate per unit time higher than the current target sterilization rate at that time. The biometric information may include results of direct confirmation of the presence or absence of pathogenic microorganisms in the aquatic organism, such as a blood test, or confirmation of the stress state. The biometric information may also include non-invasive sensing information, such as measurement of pulse waves or mitochondrial membrane potential, or detection of abnormal behavior using a camera. If the biometric information indicates that the aquatic organism is carrying pathogenic microorganisms, the identification unit 112 may determine that the predetermined conditions are met and specify a target sterilization rate per unit time and a permissible immersion time. If the sensing information indicates that the aquatic organism is carrying pathogenic microorganisms, the identification unit 112 may determine that the predetermined conditions are met and specify a target sterilization rate per unit time and a permissible immersion time. In this case, the identification unit 112 may increase the target sterilization rate by a predetermined percentage from the current target sterilization rate.

[0091] The input receiving unit 114 may receive input of water quality information indicating the quality of the water in the circulation path 22. The identifying unit 112 may identify a target sterilization rate per unit time further based on the water quality. The water quality information may indicate the number of bacteria in the water estimated from the protein information. The water quality information may also indicate the results of measuring the number of bacteria using a biosensor. For example, if a correlation is found between a decrease in the biological defense ability or the onset of disease in aquatic organisms and the concentration of a specific component in metabolites or excreta, the water quality information may indicate the concentration of the characteristic component in the water measured by the sensor. If the number of bacteria or the concentration of the characteristic component indicated in the water quality information satisfies a predetermined condition, the identifying unit 112 may increase the target sterilization rate by a predetermined percentage from the current target sterilization rate.

[0092] The input receiving unit 114 may receive input of flow rate condition information indicating flow rate condition values ​​according to breeding control of aquatic organisms. The specifying unit 112 may specify a target flow rate for the circulation path and a target sterilization rate per unit time further based on the flow rate condition information. For example, if an upper limit flow rate is determined from the viewpoint of energy conservation or from flow rate conditions indicating requirements for other water treatments such as ammonia treatment, the specifying unit 112 may set the target flow rate so as not to exceed the upper limit flow rate, and then specify the target sterilization rate per unit time.

[0093] The determination unit 112 may acquire from the transmittance measuring device 96 the transmittance per unit length of water in the circulation path 22 for the ultraviolet wavelength output by the ultraviolet light source 92. The determination unit 112 may determine the ultraviolet intensity for the water based on the transmittance, the target flow rate, and the target ultraviolet intensity.

[0094] When the ultraviolet light source 92 is, for example, a UV-C LED, the ultraviolet output (luminous flux) (W, lumens) from the light source can be changed by changing the drive current. The ultraviolet intensity (illuminance) (W / cm 2The UV intensity (lux) varies depending on the UV transmittance of the water, even if the UV output from the UV light source 92 is the same. Due to factors such as a decrease in UV transmittance after feeding or fish excretion, UV transmittance may fluctuate in the closed-loop water circulation system 10 used in closed-loop land-based aquaculture. Therefore, the specifying unit 112 may ultimately specify the target UV intensity by multiplying the target UV intensity by a coefficient corresponding to the UV transmittance measured by the transmittance measuring device 96.

[0095] The transmittance measuring device 96 may have a photodiode that can detect ultraviolet intensity, and may measure the ultraviolet transmittance by measuring the ultraviolet intensity expected at 100% transmittance relative to the distance from the ultraviolet light source 92.

[0096] Identifying unit 112 may update the ultraviolet intensity of the water based on the ultraviolet intensity output by ultraviolet light source 92 from ultraviolet intensity meter 94, an electrical signal of ultraviolet light source 92 from sterilization treatment device 90, or the accumulated lighting time of ultraviolet light source 92 from sterilization treatment device 90. Generally, even if the magnitude of the drive current is the same, the ultraviolet output of ultraviolet light source 92 fluctuates over time. Therefore, identifying unit 112 may reflect changes in the ultraviolet output of ultraviolet light source 92 in the ultraviolet intensity of the water.

[0097] The ultraviolet intensity meter 94 may have an element for detecting ultraviolet intensity, such as a photodiode, and may measure the intensity directly using that element. If the ultraviolet light source 92 is a UV-C LED and changes over time in parameters other than the drive current, such as leakage current or drive voltage for the same drive current, are correlated with changes in ultraviolet output over time, the identifying unit 112 may measure the output of the ultraviolet light source based on the correlation between the electrical signal acquired from the sterilization treatment device 90 and the changes over time. Alternatively, the identifying unit 112 may estimate changes in the output of the ultraviolet light source 92 from the cumulative lighting time of the ultraviolet light source 92.

[0098] In this embodiment, the water circulation system has been described using a closed circulation water circulation system 10 as an example, in which water is not drained from the circulation path 22. However, as shown in Fig. 10, the system of this embodiment can also be provided as a semi-closed water circulation system 10A in which water is poured into and drained from the circulation path 22. Note that the functional blocks indicated by the reference numerals in Fig. 10 may have the same functions as the functional blocks indicated by the reference numerals in Fig. 1.

[0099] In the case of a closed circulation system, i.e., when water exchange is performed, the identification unit 112 may identify the viable bacteria rate in the aquarium 20 by multiplying the viable bacteria rate in the aquarium 20 identified in the case of a completely closed circulation system by the water volume V of the aquarium 20 / (water volume V of the aquarium + water exchange amount). Naturally, the more the amount of water exchange, the lower the viable bacteria rate, but since the calculation is based on the viable bacteria rate in the aquarium 20 described above, this embodiment can also be applied to a semi-closed circulation system.

[0100] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0101] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0102] 10 Closed loop water circulation system 10A Semi-closed water circulation system 20 aquarium 22 Circulation Route 24 Aquatic life 30 Sedimentation tank 50 Biological filtration tank 80 Pump 82 Flow meter 60 Circulation Control Device 90 Sterilization treatment equipment 92 Ultraviolet light source 94 UV intensity meter 96 Transmittance measuring instrument 100 Management device 110 control section 112 Specific part 114 Input reception section 116 Timer 120 Storage section 130 Interface section 140 Output section

Claims

1. A management device for controlling a water circulation system having a circulation path that purifies water in an aquarium and returns the water to the aquarium, a circulation control device that circulates the water in the circulation path with a pump, and a sterilization treatment device that sterilizes the water by irradiating the water passing through the circulation path with ultraviolet light from an ultraviolet light source, the management device comprising an identification unit that identifies, based on an ultraviolet light irradiation dose threshold of the ultraviolet light source, an apparatus sterilization rate that indicates the sterilization rate inside the sterilization treatment device achieved by the ultraviolet light source irradiating ultraviolet rays onto water at the ultraviolet irradiation dose threshold, and the amount of water in the water tank, a target flow rate of the pump at which the sterilization rate in the water per unit time reaches a target sterilization rate within an allowable immersion time from when the ultraviolet light source starts irradiating ultraviolet rays onto the water, and identifies, as a ultraviolet light set intensity, a target ultraviolet light intensity of the ultraviolet light source that becomes the ultraviolet irradiation dose threshold when the set flow rate of the pump is set to the target flow rate.

2. further comprising an input receiving unit that receives input, Aquatic organisms are kept in the aquarium, The input receiving unit aquatic organism information indicating attributes of the aquatic organism; A bacterial species to be sterilized according to the aquatic organism information, and Accepting an input of the bacterial concentration in the water tank; the specifying unit specifies an allowable bacterial concentration and an allowable immersion time according to the input aquatic organism information and the bacterial species to be sterilized, based on relationship information indicating the relationship between the bacterial species to be sterilized according to the aquatic organism information, and an allowable bacterial concentration and the allowable immersion time, and further specifies a target sterilization rate per unit time for reducing the bacterial concentration to the allowable bacterial concentration within the allowable immersion time; The management device according to claim 1 , wherein the ultraviolet irradiation amount threshold and the device sterilization rate are determined in advance according to the target bacterial species.

3. The input receiving unit receives ultraviolet light sensitivity information predetermined according to the target bacterial species, The management device according to claim 2 , wherein the specifying unit specifies the ultraviolet irradiation amount threshold or the device sterilization rate in accordance with the ultraviolet sensitivity information.

4. The management device described in claim 2, wherein the identification unit refers to a memory unit that stores ultraviolet sensitivity information indicating the ultraviolet sensitivity according to the bacterial species to be sterilized for each type of aquatic organism, identifies the ultraviolet sensitivity corresponding to the input aquatic organism information, and identifies the ultraviolet irradiation dose threshold or the device sterilization rate according to the ultraviolet sensitivity information.

5. The management device according to claim 2 , wherein the specifying unit specifies the target sterilization rate per unit time and the allowable immersion time at a preset time.

6. The input receiving unit Accepting input of water quality information indicating the quality of water in the circulation path; The management device according to claim 2 , wherein the specifying unit specifies the target sterilization rate per unit time further based on the water quality information of the water.

7. The input receiving unit Accepting input of biological information regarding the biological body of the aquatic organism; The management device according to claim 2 , wherein the specifying unit specifies the target sterilization rate per unit time and the allowable immersion time when the biological information satisfies a predetermined condition indicating a high risk of developing an infectious disease.

8. The input receiving unit receiving input of flow rate condition information indicating a flow rate condition value according to the breeding control of the aquatic organism; The management device according to claim 2 , wherein the specifying unit specifies the target flow rate of the circulation path and the target sterilization rate per unit time based further on the flow rate condition information.

9. The identification unit Obtaining a transmittance per unit length of water in the water tank for the ultraviolet wavelength output by the ultraviolet light source from a transmittance measuring device; The management device according to claim 1 , wherein the intensity of ultraviolet light on the water is determined based on the transmittance.

10. 2. The management device of claim 1, wherein the identification unit updates the ultraviolet intensity of the water based on an ultraviolet intensity output by the ultraviolet light source from an ultraviolet detector, an electrical signal of the ultraviolet light source from the sterilization treatment device, or an accumulated lighting time of the ultraviolet light source from the sterilization treatment device.

11. The management device according to claim 2 , wherein the specifying unit periodically specifies the target sterilization rate per unit time.

12. A management device according to any one of claims 1 to 11; The circulation path; The circulation control device; The sterilization treatment device; Equipped with the circulation control device controls the pump so that the flow rate of the pump is equal to or greater than the target flow rate; The sterilization treatment device is a water circulation system that controls the ultraviolet light source so that the ultraviolet intensity of the ultraviolet light source is equal to or greater than the target ultraviolet intensity.

13. 13. The water circulation system of claim 12, wherein, in response to the elapse of the allowable immersion time from when the ultraviolet light source starts irradiating the water with ultraviolet light, the sterilization treatment device reduces the target ultraviolet intensity of the ultraviolet light source, turns off the ultraviolet light source, or cancels the setting of the target ultraviolet intensity.

14. the circulation control device controls the pump so that the flow rate of the pump is equal to the target flow rate; The water circulation system according to claim 12 , wherein the sterilization treatment device controls the ultraviolet light source so that the ultraviolet intensity of the ultraviolet light source is equal to the target ultraviolet intensity.

15. The water circulation system according to claim 12, wherein the water circulation system is a closed circulation water circulation system in which no drainage is performed on the circulation path, or a semi-closed circulation system in which water is poured into and drained from the circulation path.

16. The water circulation system according to claim 12 , wherein the ultraviolet light source is a UV-C LED having an output peak wavelength in the wavelength band of 220 nm or more and 280 nm or less.

17. A management method for managing a water circulation system having a circulation path that purifies water in an aquarium and returns the purified water to the aquarium, a circulation control device that circulates the water in the circulation path with a pump, and a sterilization treatment device that sterilizes the water by irradiating the water passing through the circulation path with ultraviolet light from an ultraviolet light source, a specifying unit specifying, based on an ultraviolet irradiance threshold of the ultraviolet light source, an apparatus sterilization rate indicating the sterilization rate inside the sterilization treatment device achieved by the ultraviolet light source irradiating water with ultraviolet rays at the ultraviolet irradiance threshold, and the amount of water in the water tank, a target flow rate of the pump at which the sterilization rate in the water per unit time reaches a target sterilization rate within an allowable immersion time after the ultraviolet light source starts irradiating water with ultraviolet rays, as a set flow rate of the pump; and specifying, based on an ultraviolet irradiance threshold of the ultraviolet light source, an apparatus sterilization rate indicating the sterilization rate inside the sterilization treatment device achieved by the ultraviolet light source irradiating water with ultraviolet rays at the ultraviolet irradiance threshold, and the amount of water in the water tank, a target ultraviolet intensity of the ultraviolet light source that becomes the ultraviolet irradiance threshold when the set flow rate of the pump is set to the target flow rate, as a set ultraviolet intensity.

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