Management device, water circulation system, and management method

Abstract

To provide a method for appropriately setting the intensity of ultraviolet rays at a flow rate at which optimum power efficiency is obtained in order to prevent infection to individuals in other water tanks even if an individual in one of a plurality of water tanks develops an infectious disease in a water circulation system.SOLUTION: The management device 100 is configured to, based on a sterilization target value including a safe maximum viable cell count and an allowable immersion time, bacteria information including a viable cell count increase amount indicating the number of bacteria released into water per unit time by the aquatic organisms having developed infectious diseases and ultraviolet light sensitivity information of bacteria to be sterilized, and rearing condition information including a plurality of water tank 20A, a water amount of 20B, the number of water tanks, and a lower limit flow amount of a pump, A specifying unit configured to set an ultraviolet target intensity of the ultraviolet light source so that the number of viable bacteria in at least one of the plurality of water tanks falls below the safe maximum number of viable bacteria within the allowable immersion time when the set flow rate of the pump is set to a target flow rate based on a lower limit 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 an aquaculture management system that realizes closed-loop land-based aquaculture. [Prior art document] [Patent documents]

[0003] [Patent Document 1] Patent No. 7345037 Summary of the Invention [Problem to be solved by the invention]

[0004] In land-based aquaculture of aquatic organisms, it is desirable to improve power efficiency while reducing the risk of aquatic organisms becoming infected with pathogenic microorganisms. [Means for solving the problem]

[0005] A management device according to one embodiment of the present invention may be a management device that manages a water circulation system having a circulation path that purifies water from multiple tanks connected in parallel and returns it to the multiple tanks, 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 it with ultraviolet light from an ultraviolet light source. The management device may include a specification unit that specifies a target ultraviolet light intensity of the ultraviolet light source based on: a safe maximum viable count indicating the number of bacteria with a high probability that the aquatic organism will not develop an infectious disease in at least one of the multiple aquariums where the aquatic organism is kept; a sterilization target value including an allowable immersion time within which the aquatic organism is likely to not develop an infectious disease even if the number of bacteria in at least one of the multiple aquariums exceeds the safe maximum viable count; bacterial information including an increase in viable count indicating the number of bacteria released into water per unit time by the aquatic organism that has developed an infectious disease and ultraviolet sensitivity information of the bacterial species to be sterilized; and breeding condition information including the water volume and number of the multiple aquariums and a lower limit flow rate of the pump, so that the number of viable bacteria in at least one of the multiple aquariums will fall below the safe maximum viable count within the allowable immersion time when the set flow rate of the pump is set to a target flow rate based on the lower limit flow rate.

[0006] The management device may further include an input receiving unit that receives input of aquatic organism information indicating attributes such as the type, body length, or weight of the aquatic organism and a bacterial species to be sterilized. The identification unit may identify the sterilization target value and the bacterial information corresponding 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 the sterilization target value and the bacterial information.

[0007] In the management device, the relationship information may include organism species and bacterial species correspondence information indicating, for each attribute of the aquatic organism, a bacterial species to be sterilized, an increase in viable bacterial count, and ultraviolet sensitivity information of the bacterial species to be sterilized. The identification unit may refer to the organism species and bacterial species correspondence information to identify the increase in viable bacterial count and ultraviolet sensitivity information corresponding to the input aquatic organism information and the bacterial species to be sterilized.

[0008] In any of the management devices, the input receiving unit may receive input of biological information related to the biology of the aquatic organism, and the identifying unit may adjust the target ultraviolet light intensity to be higher than the current target ultraviolet light intensity when the biological information satisfies a predetermined condition indicating a high risk of developing an infectious disease.

[0009] In any one of the management devices, the input receiving unit may receive input of water quality information indicating a water quality of the water in the circulation path. The specifying unit may adjust the ultraviolet light target intensity based on the water quality of the water.

[0010] In any of the management devices, the identification unit may acquire from a transmittance measuring device the transmittance per unit length of water in the tank for the ultraviolet wavelength output by the ultraviolet light source, and adjust the target ultraviolet intensity based on the transmittance.

[0011] In any of the management devices, the identification unit may adjust the target ultraviolet intensity based on the intensity of ultraviolet light output by the ultraviolet light source from an 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.

[0012] 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.

[0013] In the water circulation system, 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.

[0014] In the water circulation system, aquatic organisms may be pre-classified into a first taxonomic group including individuals determined to have the potential to develop a bacterial or viral infectious disease, and a second taxonomic group consisting of other individuals. The aquatic organisms may be reared in the plurality of aquariums, separated into the first taxonomic group and the second taxonomic group.

[0015] If the individuals of the first taxonomic group do not develop an infectious disease, 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 in response to satisfaction of a predetermined condition indicating that an infection incubation period has elapsed since confirming the presence or absence of an infectious disease.If the individuals of the first taxonomic group develop an infectious disease, 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 after confirming the last individual with an infectious disease and removing that individual from the aquarium, and then after the infection incubation period has elapsed.

[0016] 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.

[0017] 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 a plurality of aquariums connected in parallel and returns the purified water to the plurality of aquariums, 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 plurality of aquariums may be connected in parallel via the circulation path. The management method may include a step in which the identification unit specifies a target ultraviolet light intensity of the ultraviolet light source based on: a safe maximum viable count indicating the number of bacteria with a high probability that the aquatic organism will not develop an infectious disease in at least one of the plurality of aquariums in which the aquatic organism is kept; a sterilization target value including an allowable immersion time within which the aquatic organism is likely to not develop an infectious disease even if the number of bacteria in at least one of the plurality of aquariums exceeds the safe maximum viable count; bacterial information including an increase in viable count indicating the number of bacteria released into water per unit time by the aquatic organism that has developed an infectious disease and ultraviolet sensitivity information of the bacterial species to be sterilized; and breeding condition information including the water volume of the plurality of aquariums, the number of aquariums, and a lower limit flow rate of the pump, so that the number of viable bacteria in at least one of the plurality of aquariums will fall below the safe maximum viable count within the allowable immersion time when the set flow rate of the pump is set to a target flow rate based on the lower limit flow rate.

[0018] 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]

[0019] [Figure 1] FIG. 1 is a functional block diagram showing an example of the overall configuration of a closed-loop 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. 10 is a graph plotting the logarithmic viable cell count in a water tank with the average circulation number on the horizontal axis and the logarithmic sterilization rate of the device being changed. [Figure 5] FIG. 10 is a graph showing the time required for the logarithmic viable cell rate in the water tank to reach 3.0 or more when the amount of UV irradiation applied to the water in the sterilization treatment device is changed. [Figure 6] FIG. 10 is a diagram showing an example of the relationship between the proportionality coefficient α and the device logarithmic sterilization rate (logγ). [Figure 7] FIG. 10 is a flowchart illustrating an example of a procedure for setting a target flow rate and a target ultraviolet light intensity. [Figure 8] FIG. 10 is a diagram illustrating an example of the relationship between logN2(t) and time T. [Figure 9] FIG. 10 is a diagram showing an example of biological species and bacterial species correspondence information. [Figure 10] FIG. 10 is a flowchart illustrating an example of a procedure for setting a target flow rate and a target ultraviolet light intensity based on biological species / microbial species correspondence information. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] 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.

[0022] In closed-circulation water circulation systems used in closed-circulation land-based aquaculture, the possibility of pathogenic microorganisms being mixed in is considered extremely low. However, once some of the aquatic organisms being raised develop an infectious disease, the possibility of infecting other individuals becomes extremely high. For this reason, water is generally sterilized in the circulation route before being returned to the aquarium.

[0023] However, bacteria increase inside the bodies of infected aquatic organisms and release high concentrations of bacteria into the surrounding area, so even if the water is sterilized in the circulation route, there is a possibility that individuals in the same tank may be at higher risk of infection.

[0024] Therefore, the water circulation system of this embodiment includes multiple aquariums connected in parallel via a circulation path and a sterilization treatment device that sterilizes the water in the circulation path. In this water circulation system, even if an individual in one of the multiple aquariums develops an infectious disease, a method is provided for appropriately setting the ultraviolet light intensity at a flow rate that provides optimal power efficiency to prevent infection of individuals in the other aquariums.

[0025] 1 is a functional block diagram showing an example of the overall configuration of a closed-circulation water circulation system 10 according to this embodiment. The closed-circulation water circulation system 10 may be used in closed-circulation land-based aquaculture, which cultivates aquatic organisms such as fish on land.

[0026] The closed-circulation water circulation system 10 includes water tanks 20A and 20B, 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. In this embodiment, an example will be described in which the closed-circulation water circulation system 10 includes two water tanks, water tank 20A and water tank 20B. However, the closed-circulation water circulation system 10 may include three or more water tanks. Hereinafter, the water tanks 20A and 20B may be collectively referred to as water tank 20.

[0027] Aquariums 20A and 20B are containers for storing water (seawater or freshwater) for raising aquatic organisms such as farmed fish. Aquatic organisms 24 may be raised in aquariums 20A and 20B. Aquariums 20A and 20B are connected in parallel to a circulation path 22. Aquariums 20A and 20B share the circulation path 22. Water discharged from aquariums 20A and 20B is purified through the same circulation path 22, and then distributed and returned to aquariums 20A and 20B.

[0028] The circulation path 22 is a water flow path that supplies water discharged from the water tanks 20A, 20B back to the water tanks 20A, 20B via the settling tank 30, the biological filtration tank 40, and the sterilization treatment device 90. The settling tank 30 removes foreign matter contained in the water supplied from the water tanks 20A, 20B. 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 the sterilization treatment device 90 via a pump 80. The devices having various functions for purifying water that are arranged in the circulation path 22 are not limited to the devices described above. Furthermore, the locations at which each device is arranged are merely examples.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 mouse, a touch panel display, etc. 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.

[0034] The control unit 110 has an identification unit 112 and an input receiving unit 114. The identification unit 112 determines a target flow rate F based on the lower limit flow rate of the pump 80 based on a sterilization target value including a safe maximum viable cell count indicating the number of bacteria with which the aquatic organism 24 is likely to not develop an infectious disease in at least one of the aquariums 20A and 20B, an allowable immersion time with which the aquatic organism 24 is likely to not develop an infectious disease even if the number of bacteria exceeds the safe maximum viable cell count in at least one of the aquariums 20A and 20B, bacterial information including an increase in the number of viable cells indicating the number of bacteria released into water per unit time by an aquatic organism with an infectious disease and ultraviolet sensitivity information of the bacterial species to be sterilized, and breeding condition information including the water volume of the aquariums 20A and 20B, the number of the aquariums, and a lower limit flow rate of the pump 80. t When the ultraviolet light source 92 is set to the ultraviolet target intensity E, the number of viable bacteria in at least one of the water tanks 20A and 20B falls below the safe maximum viable bacteria number within the permissible immersion time. t The determination unit 112 determines the target flow rate F t As the lower limit flow rate F min The output unit 140 may output the target flow rate F t is output to the circulation control device 60, and the ultraviolet target intensity E t 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. t 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 target intensity E t 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.

[0035] 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

[0036] When ultraviolet light source 92 is, for example, a UV-C LED, sterilization treatment device 90 can change the ultraviolet intensity by changing the drive current supplied to ultraviolet light source 92. Sterilization treatment device 90 determines whether ultraviolet intensity E of ultraviolet light source 92 is greater than or equal to ultraviolet target intensity E t The sterilization treatment device 90 may control 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 may control 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

[0037] In order to achieve that the number of live bacteria in at least one of the water tanks 20A and 20B falls below the safe maximum number of live bacteria within the permissible immersion time, the flow rate of the pump 80 is set to a target flow rate F t The ultraviolet intensity is the target ultraviolet intensity E t It is fine if the values ​​are equal to or greater than the set values, but to avoid unnecessary power consumption, it is better to set them equal to the respective set values.

[0038] An aquatic organism 24 is kept in one of the multiple aquariums connected in parallel. If the aquatic organism 24 develops an infectious disease and continues to release pathogenic microorganisms into the water, the pathogenic microorganisms will spread to the other aquariums through the circulation path 22. In this case, in order to maintain the number of viable bacteria in the other aquariums at a safe level, a method for appropriately setting the ultraviolet light intensity at a target flow rate that provides optimal power efficiency will be further described.

[0039] First, let us consider the viable bacterial count in tank 20A, which contains an infectious aquatic organism 24. For example, if the total water volume of all tanks is V [L] and the flow rate of pump 80 is F [L / min], then on average, the water in tank 20A is circulated at a time of V / F [min]. However, it is reasonable to consider that not all of the water in tank 20A circulates once, and that the number of times it is circulated follows a statistical probability distribution.

[0040] 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 number of viable bacteria N1 [CFU / ml] in tank 20A follows the formula:

number

number

number

[0041] where n B is the increase in viable bacteria count [CFU / ml], which is the number of bacteria released into water per unit time by aquatic organisms that have developed an infectious disease, function Po(n) is the probability mass function of the Poisson distribution, and γ is the sterilization rate when water passes through the sterilization treatment device 90 once.

[0042] FIG. 3 shows the Poisson distribution when the expected value λ=3. FIG. 3 shows the ratio of the number of times that the water in water tank 20A circulates through circulation path 22. In other words, it shows the distribution of the number of times that the water in water tank 20A has circulated. The example shown in FIG. 3 shows that 5% of the total water in water tank 20A 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 water tank 20A. Therefore, when γ is sufficiently high (close to 1), the number of live bacteria in water tank 20A is n B *T*Po(n=0). On the other hand, when γ is low, Po(n≧1) also contributes to the viability rate.

[0043] Next, the viable bacteria count in a water tank other than water tank 20A will be described. In this embodiment, the other water tank is water tank 20B, and the viable bacteria count in water tank 20B follows formula (4) below.

number

[0044] where n tank is the number of tanks. The number of live bacteria N1 in tank 20A is calculated by dividing the number of tanks n tank The number of bacteria divided equally by circulates at a rate of the Poisson distribution probability mass function and enters the other tanks. At this time, the water passes through sterilization treatment device 90 the number of times it is circulated, and is sterilized by the nth power of the sterilization rate at each pass. Note that of the water that has been circulated more than once, water that has passed through tanks other than tank 20A is ignored.

[0045] 4 shows a graph in which the logarithmic viable count [log(CFU / ml)] in water tank 20B is plotted against the average circulation number (random variable) on the horizontal axis, while varying the equipment logarithmic sterilization rate, which is the sterilization rate of water passing through sterilization treatment device 90. At this time, the number of pathogenic microorganisms in water tank 20A is 10 per minute. 3 The calculation was performed under the condition of an increase in CFU / ml and V / F = 25 minutes. The average circulation frequency (expected value λ) on the horizontal axis is the elapsed time T ÷ (V / F).

[0046] As shown in Figure 4, the higher the sterilization rate of sterilization treatment device 90, the lower the peak of pathogenic microorganism growth and the fewer circulation times required. Since the average circulation time λ is λ = T ÷ (V / F), the greater the flow rate F, the shorter the circulation time per λ = 1. Therefore, the time during which pathogenic microorganisms are increasing is shortened. However, it should be noted that because the time that water passes through sterilization treatment device 90 is shortened in inverse proportion to the flow rate F, the amount of ultraviolet light irradiated on pathogenic microorganisms in the water is reduced for the same ultraviolet light irradiation intensity.

[0047] FIG. 5 shows that the logarithmic viable cell ratio in the water tank 20B is 3.0 (i.e., 10 3This graph shows the time it takes for the number of bacteria to reach or exceed CFU / ml when the amount of ultraviolet light (UV irradiation amount) applied to the water in the sterilization treatment device 90 is changed. The UV irradiation amount shown in the graph legend is the value when the flow rate F is 20 L / min, and the calculation reflects a value that varies inversely proportional to the flow rate F on the horizontal axis.

[0048] For example, to shorten the time it takes for the logarithmic viable count to reach 3.0, it is necessary to increase the sterilization rate within sterilization treatment device 90, as shown in Figure 5. Increasing the sterilization rate within sterilization treatment device 90 means increasing the amount of ultraviolet light irradiated onto the water passing through sterilization treatment device 90. There are two externally controlled methods for increasing the amount of ultraviolet light irradiated: increasing the ultraviolet intensity, and decreasing the flow rate F to increase the amount of ultraviolet light irradiated onto the water passing through sterilization treatment device 90.

[0049] The power consumption of pump 80 depends on the flow rate, but when it is on the order of several tens of L / min, it often exceeds kWh. Furthermore, the flow rate is generally proportional to the cube of the power consumption of pump 80. Meanwhile, the power consumption of sterilization treatment device 90 is on the order of 100 W at most, and UV intensity is linearly proportional to the power consumption. Therefore, reducing the flow rate F rather than increasing the UV intensity has the advantage of reducing power consumption. However, as mentioned above, closed-loop water circulation systems 10 often also perform water treatment other than water sterilization, such as filtration. Therefore, there may be cases where the flow rate F cannot be reduced solely for the sake of water sterilization.

[0050] The logarithmic viable count is the maximum safe viable count N, which is the safe level at which aquatic organisms are likely not to develop an infectious disease. th To ensure that the time required to reach this point is within the allowable immersion time, the flow rate F = F min At this time, it is necessary to appropriately set the sterilization rate of the water passing through the sterilization treatment device 90.

[0051] Logarithmic viable bacteria count is the maximum safe viable bacteria count N th If the time when it reaches is T, the following equation (5) is satisfied.

number

[0052] Since the sum of Poisson probability mass functions is approximated linearly on a logarithmic scale, we use the following equation (6):

number

[0053] In equation (6), α is a proportionality coefficient that depends on the device sterilization rate. Figure 6 shows an example of the relationship between the proportionality coefficient α and the device logarithmic sterilization rate (logγ).

[0054] Furthermore, when n=0, the Poisson probability mass function has the relationship with λ as shown in the following equation (7).

number

[0055] Therefore, the maximum safe viable cell count N th This equation can be transformed into the following equation (8).

number

[0056] In this case, T may have either no solution or two solutions. Strictly speaking, there may also be a single solution, but this will be ignored. Physically, if there is no solution, the maximum safe number of viable bacteria N th This means that the maximum safe number of viable bacteria N th means the time that exceeds

[0057] Under the condition that T has a solution, the maximum safe number of viable bacteria N th The lower the value of n, the greater the increase in the number of live bacteria released into water by aquatic organisms per unit time. B The higher the value, the greater the difference between the two solutions. As the device logarithmic sterilization rate increases and α approaches 2.3, the difference between the two solutions for T becomes smaller, and there is no solution at all.

[0058] FIG. 7 is a flowchart showing an example of a procedure for setting a target flow rate and a target ultraviolet light intensity.

[0059] The input receiving unit 114 receives the lower limit flow rate F of the pump 80 via the interface unit 130. min The specifying unit 112 receives the input of the lower limit flow rate F min Based on this, the target flow rate F t (S102).

[0060] Lower limit flow rate F min may be determined based on the flow rate conditions or constraints in water treatment in the circulation path 22, such as the filtration tank 40 or the denitrification tank 70. Increasing the flow rate increases the power consumption of the pump 80. In addition, decreasing the flow rate increases the amount of ultraviolet radiation emitted by the sterilization treatment device 90. Therefore, the specifying unit 112 determines the lower limit flow rate F of the pump 80. min may be specified as the target flow rate for pump 80.

[0061] 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 Otherwise, the control unit 110 issues a command to the circulation control device 60 via the output unit 140 to set the flow rate F of the pump 80 to the target flow rate F t The set flow rate is adjusted so as to control the rotation speed of the pump 80 (S106).

[0062] Next, the input receiving unit 114 receives input of the sterilization target value, the quantity and number of each water tank 20, and the increase in the number of live bacteria per unit time (S108).

[0063] The sterilization target value is the maximum safe viable bacterial count N, which indicates the number of bacteria that is likely to prevent aquatic organisms from developing an infectious disease in at least one of the aquariums 20A and 20B. th and the number of bacteria in at least one of the water tanks 20A and 20B is equal to or greater than the maximum safe viable number N thThe sterilization target value includes the maximum safe viable count N, which indicates the number of bacteria that is likely to prevent aquatic organisms from developing an infectious disease in aquarium 20B other than aquarium 20A where an infectious disease-affected aquatic organism is present. th In the water tank 20B other than the water tank 20A, the number of bacteria is the maximum safe viable number N th The acceptable immersion time may include an acceptable immersion time above which aquatic organisms are likely not to develop infectious diseases.

[0064] Here, in order to reduce the risk of aquatic organisms being infected with pathogenic microorganisms, the allowable immersion time is set to the maximum safe viable count N th The time required to reach the maximum safe viable count N must be longer than T. th The time T at which t = 1 can be determined according to equation 8 above.

[0065] Because it is a complicated formula, the input values ​​of water volume V, flow rate F, and increase in viable bacteria count n B and the maximum safe viable count N, which is the sterilization target value. th It is also difficult to uniquely calculate and identify an α that satisfies the allowable immersion time. Two examples of methods for deriving α are shown below. The identification unit 112 may derive α in advance and store it in the storage unit 120 according to one of the following two methods.

[0066] First, the first method will be described. The determination unit 112 may derive α according to the following equation (9).

number

[0067] The specifying unit 112 inputs the water volume V, the flow rate F, and the increase in the viable cell count n B , and the number of tanks n tank Substituting N2(t) and the maximum safe viable number of bacteria N thThe relationship between the time T and the time required to reach the predetermined value is calculated. The water volume V is the total water volume of the parallel tanks in the closed-loop water circulation system 10. If there are multiple tanks other than the tank 20A in which the infectious aquatic organism is present, the water volume V is the total water volume of the multiple tanks. Similarly, the flow rate F is the total flow rate of the multiple tanks other than the tank 20A in which the infectious aquatic organism is present.

[0068] Figure 8 shows the results for V = 1000, F = 30 L / min, n B = 1000 CFU / ml / min, n tank When α is set to 2, the relationship between logN2(t) and time T is plotted by decreasing α from 3.4 in increments of 0.05. It can be seen that when α = 3.25, the time when logN(t) ≥ 3.0 is reached is less than 30 minutes.

[0069] That is, the specifying unit 112 determines the maximum safe viable count N th 1000CFU / ml, the maximum safe viable cell count N th If the allowable immersion time that may exceed is 30 minutes, then α should be set to 3.25 or less.

[0070] Next, the second method will be described. The determination unit 112 may transform equation (8) into the following equation (10), and derive α according to equation (10).

number

[0071] The identification unit 112 calculates the maximum safe viable count N by iterative substitution according to equation (10). th The time T at which

[0072] The specifying unit 112 determines the input values, the water volume V, the flow rate F, and the increase in the number of live bacteria n B , number of tanks n tank , and α are substituted into the right-hand side of equation (10), and then the temporary value τ1 of T is substituted into the right-hand side of equation (10) to calculate equation (10). Considering the program, τ1 is 2 n is preferred.

[0073] If the calculation result on the right side is greater than τ1, then τ2 = τ1 - 2 n-1 and if it is less than τ1, then τ2 = 1 + 2 n-1 Then, substituting τ2 as T on the right side again, calculate Equation (10). Similarly, if the calculation result on the right side is greater than τ2, the specific part 112 sets τ3 = τ2 - 2 n-2 and if it is less than τ2, then τ3 = τ2 + 2 n-2 Then, substituting τ3 as T on the right side again, calculate Equation (10). The specific part 112 repeats this calculation m times until the calculation result on the right side approximates the left side. The approximate value obtained here corresponds to the larger solution of the two solutions of T. Denote this as T1. m can be determined according to the required approximation level.

[0074] To obtain the other solution of T, the specific part 112 performs successive substitution again. However, τ1 is 2 n smaller than 2 k and when the calculation result of substituting τm into T on the right side is greater than τm, τm + 1 = τm + 2 k-m and when it is less than τm, τm + 1 = τm - 2 k-m The approximate value obtained by repeating until the calculation result on the right side approximates the left side corresponds to the smaller solution of the two solutions of T. Denote this as T2.

[0075] While changing α from the larger one to the smaller one, the specific part 112 performs this successive substitution. If T1 - T2 becomes less than or equal to the allowable immersion time, the desired α can be obtained. For example, if the goal is to make T1 - T2 less than or equal to 30 minutes, since T1 < 30 < T2, it is advisable to perform successive substitution calculations with n = 5 or 6 and k = n - 1.

[0076] In this way, the specific part 112 specifies α such that the difference between the two Ts is within the allowable immersion time. When the allowable immersion time is set to 0, the specific part 112 specifies α in the range where there is no solution for T.

[0077] Next, the specific part 112 determines the target flow rate F tThe required equipment sterilization rate in is identified (S110). The identification unit 112 identifies the required equipment sterilization rate that satisfies the above-identified α. The identification unit 112 may identify the required equipment sterilization rate that satisfies α based on relationship information that indicates the relationship between the equipment logarithmic sterilization rate and the proportionality coefficient α, as shown in FIG.

[0078] The specifying unit 112 specifies a target ultraviolet irradiation dose based on the required equipment sterilization rate (S112). Because the sterilization rate for a given ultraviolet irradiation dose varies depending on the ultraviolet sensitivity of pathogenic microorganisms, the specifying unit 112 may specify a target ultraviolet irradiation dose that satisfies the required equipment sterilization rate according to the ultraviolet sensitivity information of the bacterial species to be sterilized. The specifying unit 112 may specify a target ultraviolet irradiation dose that satisfies the required equipment sterilization rate according to the ultraviolet sensitivity information of the bacterial species to be sterilized. The ultraviolet irradiation dose and the equipment logarithmic sterilization rate often have a linear relationship such as equipment logarithmic sterilization rate = a × ultraviolet irradiation dose + b, and the coefficient a and intercept b may be used as ultraviolet sensitivity information. The specifying unit 112 may specify a target ultraviolet irradiation dose from the equipment logarithmic sterilization rate and ultraviolet sensitivity information a and b based on equipment logarithmic sterilization rate = a × ultraviolet irradiation dose + b.

[0079] The identification unit 112 may identify a target ultraviolet irradiation amount that satisfies the required equipment sterilization rate from the relationship between the equipment sterilization rate corresponding to the reference ultraviolet sensitivity information and the ultraviolet irradiation amount, and further identify the ratio of the ultraviolet sensitivity information of the bacterial species to be sterilized this time to the reference ultraviolet sensitivity information, and multiply the identified target ultraviolet irradiation amount by the ratio, thereby identifying a target ultraviolet irradiation amount that satisfies the required equipment sterilization rate.

[0080] Furthermore, since the amount of ultraviolet radiation in the sterilization treatment device 90 varies depending on the flow rate of the pump 80 even if the ultraviolet intensity is the same, the determination unit 112 determines the flow rate F=F t UV target intensity E, which is the UV target irradiation amount t(S114). For example, the amount of ultraviolet radiation given a flow rate F1 and an ultraviolet intensity E1 is assumed to be Qe1. If the flow rate is changed from F1 to c×F1, the time it takes for water to pass through the sterilization treatment device 90 will be 1 / c, so in order to maintain the same amount of ultraviolet radiation Qe1, the ultraviolet intensity must be changed to c×E1. The determination unit 112 determines the amount of ultraviolet radiation and ultraviolet intensity that can achieve the required device sterilization rate at the standard flow rate, based on relationship information that indicates the relationship between the device sterilization rate and the amount of ultraviolet radiation and ultraviolet intensity that can achieve that device sterilization rate at the standard flow rate. Furthermore, the determination unit 112 determines the amount of ultraviolet radiation and ultraviolet intensity that can achieve the required device sterilization rate at the standard flow rate based on the relationship information that indicates the relationship between the device sterilization rate and the amount of ultraviolet radiation and ultraviolet intensity that can achieve that device sterilization rate at the standard flow rate. t By multiplying the ratio of t UV target intensity E to achieve the UV target irradiation amount t Identify.

[0081] 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 (S116). 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 (S118). 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.

[0082] By the above setting process, the lower limit flow rate F min Target flow rate F based on t While adjusting the flow rate, the sterilization treatment device 90 adjusts the ultraviolet target intensity E tThe ultraviolet light intensity is controlled so that the logarithmic viable bacteria count in the water tank 20B is equal to or greater than the maximum safe viable bacteria count N th In order to make the time T for achieving this fall within the allowable immersion time, the ultraviolet intensity can be appropriately controlled at the set flow rate that provides optimal power efficiency.

[0083] Although the target UV intensity is determined by calculation of the probability distribution model in this way, in an actual system, it is not always possible to follow the ideal, so a margin may be added to the theoretical value.

[0084] Safe maximum viable bacteria count N th , and the maximum safe viable cell count N th The allowable immersion time that may exceed this depends on the type of aquatic organism, information on attributes of the aquatic organism that relate to its resistance to pathogenic microorganisms, such as its body length and weight, and information on the target bacterial species that are likely to cause disease in the aquatic organism.

[0085] For example, in the case of a young flounder weighing less than 100g, E. tarda bacteria can be found at 10 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 number of CFU / ml is low, the risk of infection increases if the fish is immersed for several hours. 3 ~10 4 It is expected that the concentration will be about CFU / ml. th =10 3 CFU / ml, safe maximum viable bacterial count N th The allowable soaking time may exceed 30 minutes, and the increase in viable bacteria count n B =10 3 May be expressed as CFU / ml / min.

[0086] The input receiving unit 114 may receive input of aquatic organism information indicating attributes of aquatic organisms and sterilization target bacterial species. The identifying unit 112 may identify the sterilization target value and bacterial information corresponding to the input aquatic organism information and sterilization target bacterial species, based on relationship information indicating the relationship between the sterilization target bacterial species corresponding to the aquatic organism information, and the sterilization target value and bacterial information.

[0087] The relationship information may include organism species / bacterial species correspondence information indicating, for each attribute of the aquatic organism, the bacterial species to be sterilized, the increase in viable bacterial count, and ultraviolet sensitivity information for the bacterial species to be sterilized. Here, ultraviolet sensitivity varies depending on the bacterial species. Once the bacterial species to be sterilized is determined, the ultraviolet sensitivity information is also determined. For example, the ultraviolet irradiation amount and the device logarithmic sterilization rate often have a linear relationship such as device logarithmic sterilization rate = a × ultraviolet irradiation amount + b, and the coefficient a and intercept b may be used as ultraviolet sensitivity information.

[0088] For example, it is possible to identify the bacterial species that need to be sterilized for each fish species based on the scale of damage caused by existing marine aquaculture, such as E. tarda, the bacteria that causes Edwardsiellosis, for flounder, and Vibrio for kuruma prawns.

[0089] The biological species and bacterial species correspondence information may include, for example, the fish species, the bacterial species to be sterilized, and the maximum safe viable bacterial count N th , allowable soaking time, increase in viable bacteria count n B , and ultraviolet sensitivity information.

[0090] The identifying unit 112 may refer to the organism species / microbial species correspondence information as shown in FIG. 9 to identify the amount of increase in viable bacteria count and ultraviolet sensitivity information corresponding to the input aquatic organism information and the sterilization target bacterial species.

[0091] In closed-loop land-based aquaculture, it is considered unlikely that the same bacteria that cause damage in existing marine aquaculture will be introduced. Taking this risk into consideration, it is possible to decide which bacterial species to sterilize.

[0092] The information on the species and bacteria correspondence is obtained by conducting new experiments or by examining the literature on past infection experiments, and by determining the maximum safe number of live bacteria N from the bacterial concentration and immersion time that pose an infection risk depending on the combination of the species and aquatic organism, or the weight of the aquatic organism. th , allowable soaking time, increase in viable bacteria count n B , and ultraviolet sensitivity information (a and b). The biological species and bacterial species correspondence information does not indicate growth information such as weight as an attribute of aquatic organisms, but is based on the minimum size that is most susceptible to disease, and is used to determine the safe maximum number of live bacteria N th may be shown.

[0093] FIG. 10 shows an example of a procedure for setting a target flow rate and a target ultraviolet light intensity based on the biological species / microbial species correspondence information.

[0094] The input receiving unit 114 receives the lower limit flow rate F of the pump 80 via the interface unit 130. min The specifying unit 112 receives the input of the lower limit flow rate F min Based on this, the target flow rate F t is set (S202).

[0095] 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 (S204). 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 to achieve the above, and the rotation speed of the pump 80 is controlled (S206).

[0096] Next, the input receiving unit 114 receives input of the water volume and number of each aquarium 20, aquatic organism information, and target bacterial species for sterilization (S208). The identifying unit 112 determines the maximum safe viable bacterial count N th The determination unit 112 determines the maximum safe viable count N corresponding to the input aquatic organism information and the target bacterial species by referring to the organism species correspondence information as shown in FIG. th , the allowable soaking time, the amount of increase in viable bacteria per unit, and UV sensitivity information may be specified.

[0097] Next, the specifying unit 112 determines the target flow rate F t The determination unit 112 determines the required device sterilization rate in the water volume V, the flow rate F, the increase in the viable bacteria count n B and the maximum safe viable count N, which is the sterilization target value. thand specifies α that satisfies the allowable soaking time. The specifying unit 112 may specify α according to equation (8) or equation (10). The specifying unit 112 may specify the required equipment sterilization rate that satisfies α based on relationship information that indicates the relationship between the equipment logarithmic sterilization rate and the proportionality coefficient α, as shown in FIG.

[0098] The specifying unit 112 specifies a target ultraviolet irradiation dose based on the required equipment sterilization rate (S214). The specifying unit 112 may specify a target ultraviolet irradiation dose that satisfies the required equipment sterilization rate according to ultraviolet sensitivity information of the bacterial species to be sterilized. The specifying unit 112 may specify a target ultraviolet irradiation dose from the equipment logarithmic sterilization rate and the ultraviolet sensitivity information a and b, based on the equation equipment logarithmic sterilization rate = a × ultraviolet irradiation dose + b.

[0099] The determination unit 112 determines the flow rate F=F t UV target intensity E, which is the UV target irradiation amount t The determination unit 112 determines the ultraviolet irradiation amount and ultraviolet intensity that can achieve the required device sterilization rate at the reference flow rate based on relationship information that indicates the relationship between the device logarithmic sterilization rate and the ultraviolet irradiation amount and ultraviolet intensity that can achieve the device sterilization rate at the reference flow rate. Furthermore, the determination unit 112 determines the ultraviolet irradiation amount and ultraviolet intensity that can achieve the required device sterilization rate at the reference flow rate based on the determined ultraviolet intensity. min By multiplying the ratio of min UV target intensity E to achieve the UV target irradiation amount t may be specified.

[0100] 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 (S218). tIf 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 (S220). 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 the 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.

[0101] As described above, the specifying unit 112 determines the lower limit flow rate F min , the ultraviolet target intensity E according to the input of the water volume and number of each aquarium 20, aquatic organism information, and the target bacterial species for sterilization. t This allows the ultraviolet intensity at the flow rate that provides the optimum power efficiency to be appropriately set.

[0102] If biological information about the aquatic organisms being kept indicates that there is an aquatic organism at high risk of developing an infectious disease, increasing the UV irradiation dose from the current UV irradiation dose may increase the likelihood of preventing the spread of disease to the aquatic organisms in the aquarium 20. Therefore, the input receiving unit 114 may receive input of biological information about the aquatic organisms. If the biological information satisfies predetermined conditions indicating a high risk of developing an infectious disease, the identifying unit 112 may adjust the target UV intensity to be higher than the current target UV intensity. The UV irradiation dose of the UV light source 92 is the product of the UV intensity and the irradiation time for the water passing through the sterilization treatment device 90, so it can be increased by increasing the UV intensity. For example, if the identifying unit 112 can identify a risk of developing an infectious disease from the biological information, it may set the target UV intensity higher than the current target UV intensity at that time. The biological information may include results of direct confirmation of the presence or absence of pathogenic microorganisms in the aquatic organisms, such as blood tests, or confirmation of their stress state. The biological information may also include non-invasive sensing information, such as pulse wave or mitochondrial membrane potential measurements, or abnormal behavior detection using a camera.

[0103] When the biological information indicates that the aquatic organism is carrying a pathogenic microorganism, the identification unit 112 may determine that a predetermined condition is satisfied and set the target ultraviolet light intensity higher than the current target ultraviolet light intensity. When the sensing information indicates that the aquatic organism is carrying a pathogenic microorganism, the identification unit 112 may determine that a predetermined condition is satisfied and set the target ultraviolet light intensity higher than the current target ultraviolet light intensity. In this case, the identification unit 112 may increase the target ultraviolet light intensity by a predetermined percentage from the current target ultraviolet light intensity.

[0104] 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 adjust the target ultraviolet light intensity 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 ultraviolet light intensity by a predetermined percentage from the current target ultraviolet light intensity. The identifying unit 112 may calculate the increase in the number of live bacteria n based on the water quality information. B is set higher than the current value, and the increase in viable bacteria count after updating n B The ultraviolet target intensity may be adjusted to be higher than the current ultraviolet target intensity by specifying the ultraviolet target intensity based on the above.

[0105] The specifying 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 specifying unit 112 may adjust the ultraviolet target intensity based on the transmittance.

[0106] 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 2 The 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, the 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 adjust 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.

[0107] The transmittance measuring device 96 may have a photodiode that can detect ultraviolet light intensity, and may measure the transmittance of ultraviolet light by measuring the ultraviolet light intensity that would be expected at a transmittance of 100% relative to the distance from the ultraviolet light source 92.

[0108] The specifying unit 112 may adjust the target UV intensity for the water based on the UV intensity output by the UV light source 92 from the UV intensity meter 94, the electrical signal of the UV light source 92 from the sterilization treatment device 90, or the accumulated lighting time of the UV light source 92 from the sterilization treatment device 90. Generally, even if the magnitude of the drive current is the same, the UV intensity of the UV light source 92 fluctuates over time. Therefore, the specifying unit 112 may adjust the target UV intensity of the UV light source 92 in accordance with the change over time.

[0109] UV intensity meter 94 may have an element for detecting UV intensity, such as a photodiode, and may measure directly using that element. If UV 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 over time in the amount of UV irradiation, specifying unit 112 may estimate the UV intensity of UV light source 92 based on the correlation between the electrical signal acquired from sterilization treatment device 90 and the changes over time. Alternatively, specifying unit 112 may estimate changes in the intensity of UV light source 92 from the cumulative lighting time of UV light source 92.

[0110] Aquatic organisms may be classified into a first taxonomic group including individuals determined to be susceptible to bacterial or viral infectious diseases and a second taxonomic group consisting of other individuals, and the first taxonomic group and the second taxonomic group may be reared separately in multiple aquariums 20. Aquatic organisms in the first taxonomic group may be aquatic organisms capable of developing the same type of infectious disease. Aquatic organisms in the first taxonomic group may be the same type of aquatic organism. For example, aquatic organisms of the first taxonomic group may be reared in aquarium 20A, and aquatic organisms of the second taxonomic group may be reared in aquarium 20B. This prevents infection of the second taxonomic group even if an individual in the first taxonomic group develops an infectious disease. Furthermore, preventing the spread of infection provides a grace period for treating the first taxonomic group without immediately discarding it.

[0111] The following methods can be used to determine the possibility of developing an infectious disease. For example, when aquatic organisms are moved from another environment to a new tank, they are subjected to stress from the change in environment. Even if the bacterial concentration in the environment is such that the organism's defenses would normally be able to resist it, the organism's defenses will be weakened if it is stressed, making it more susceptible to developing an infectious disease.

[0112] The input receiving unit 114 may receive input of biometric information about the living aquatic organism. If the biometric information satisfies predetermined conditions indicating a high risk of infectious disease, the aquatic organism may be classified into a first taxonomic group. The biometric information may include results of direct blood tests or other tests to confirm the presence or absence of pathogenic microorganisms in the aquatic organism or the result of stress assessment. The biometric information may also include non-invasive sensing information, such as measurements of pulse waves or mitochondrial membrane potential, or detection of abnormal behavior using a camera. Even if an individual is suspected of having an infectious disease, the individual can be prevented from being infected with the second taxonomic group without being immediately discarded. Therefore, even if the method for determining the possibility of an infectious disease is inaccurate and the individual is not actually infected, this does not lead to a decrease in yield.

[0113] The identification unit 112 may determine whether or not an individual has developed an infectious disease based on biological information related to the living aquatic organism. The identification unit 112 may determine whether or not an individual has developed an infectious disease based on biological information indicating whether or not the individual has developed an infectious disease.

[0114] If there is no longer any suspicion that all of the individuals in the first taxonomic group will develop an infectious disease, there is no risk of the infection spreading, so power consumption can be reduced by stopping ultraviolet sterilization by the sterilization treatment device 90 or reducing the ultraviolet intensity of the ultraviolet light source 92. Whether there is no suspicion that all of the individuals in the first taxonomic group will develop an infectious disease can be determined by checking whether there are no new cases of the disease for a period longer than the incubation period from when the pathogenic microorganism or virus that causes the infectious disease enters the body until the onset of the disease.

[0115] The incubation period here refers to the period until infection can be determined. For example, if it takes up to seven days for infection to be clearly visible, such as spots appearing on the body, then the incubation period can be set at seven days. Alternatively, if infection can be determined by testing excrement, and the maximum period for determining whether the excrement test is positive is four days, then the incubation period can be set at four days.

[0116] If the individual of the first taxonomic group does not develop an infectious disease, the sterilization treatment device 90 may reduce 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 in response to satisfaction of a predetermined condition indicating that an infection incubation period has elapsed since the onset of the infectious disease was confirmed. The input receiving unit 114 may receive an input of the confirmation result of the onset of the infectious disease. When a predetermined infection incubation period has elapsed since the confirmation result of the onset of the infectious disease was input, the ultraviolet treatment device 90 may determine that the predetermined condition has been satisfied and reduce 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. The input receiving unit 114 may receive input of infection incubation period elapse notification information indicating that an infection incubation period has elapsed since the onset of the infectious disease was confirmed. When the infection incubation period elapse notification information is input, the ultraviolet treatment device 90 may determine that the predetermined condition has been satisfied and reduce 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. If an individual of the first taxonomic group develops an infectious disease, the last individual with the infectious disease is identified and removed from the aquarium. After the infection incubation period has elapsed, sterilization treatment device 90 may reduce the target ultraviolet intensity of ultraviolet light source 92, turn off ultraviolet light source 92, or cancel the setting of the target ultraviolet intensity. This reduces power consumption in sterilization treatment device 90 and extends the life of ultraviolet light source 92.

[0117] 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.

[0118] 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]

[0119] 10 Closed loop water circulation system 20, 20A, 20B aquariums 22 Circulation Route 24 Aquatic life 30 Sedimentation tank 50 Biological filtration tank 60 Circulation Control Device 80 Pump 82 Flow meter 90 Sterilization treatment equipment 92 Ultraviolet light source 94 UV intensity meter 96 Transmittance measuring instrument 100 Management device 110 control section 112 Specific section 114 Input reception section 120 Storage section 130 Interface section 140 Output section

Claims

1. A management device for managing a water circulation system having a circulation path that purifies water from multiple tanks connected in parallel and returns the purified water to the multiple tanks, 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 sterilization target value including a safe maximum viable count indicating a bacterial count with a high probability that the aquatic organisms will not develop an infectious disease in at least one of the plurality of aquariums where the aquatic organisms are kept, and an allowable immersion time with a high probability that the aquatic organisms will not develop an infectious disease even if the bacterial count in at least one of the plurality of aquariums exceeds the safe maximum viable count; Bacteria information including an increase in viable bacteria count indicating the number of bacteria released into water per unit time by the aquatic organisms that have developed an infectious disease and ultraviolet sensitivity information of the bacteria species to be sterilized; Based on breeding condition information including the water volume of the plurality of aquariums, the number of aquariums, and the lower limit flow rate of the pump, a management device including a specifying unit that specifies a target ultraviolet intensity of the ultraviolet light source so that the number of viable bacteria in at least one of the plurality of water tanks falls below the safe maximum viable bacteria count within the allowable immersion time when the set flow rate of the pump is set to a target flow rate based on the lower limit flow rate.

2. an input receiving unit that receives input of aquatic organism information indicating attributes of the aquatic organisms and the target bacterial species for sterilization; The management device described in claim 1, wherein the identification unit identifies the sterilization target value and the bacterial information corresponding to the input aquatic organism information and the sterilization target bacterial species based on relationship information indicating the relationship between the sterilization target bacterial species according to the aquatic organism information, and the sterilization target value and the bacterial information.

3. The relationship information includes organism species-bacterial species correspondence information indicating, for each attribute of the aquatic organism, a bacterial species to be sterilized, an increase in viable bacterial count, and ultraviolet sensitivity information of the bacterial species to be sterilized, The management device according to claim 2 , wherein the identification unit refers to the biological species / microbial species correspondence information to identify the amount of increase in viable bacteria count and the ultraviolet sensitivity information corresponding to the input aquatic organism information and the sterilization target bacterial species.

4. 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 adjusts the target ultraviolet light intensity to be higher than the current target ultraviolet light intensity when the biological information satisfies a predetermined condition indicating a high risk of developing an infectious disease.

5. 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 adjusts the ultraviolet target intensity based on the water quality information.

6. 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 ultraviolet target intensity is adjusted based on the transmittance.

7. 2. The management device of claim 1, wherein the identification unit adjusts the target ultraviolet intensity based on an intensity of ultraviolet light 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.

8. A management device according to any one of claims 1 to 7; 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.

9. 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 8 , 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.

10. The aquatic organisms are classified in advance into a first taxonomic group including individuals determined to have the potential to develop a bacterial or viral infectious disease, and a second taxonomic group consisting of other individuals; The water circulation system according to claim 8 , wherein the aquatic organisms are bred in the plurality of aquariums, separated into a first taxonomic group and a second taxonomic group.

11. When the individual of the first taxonomic group does not develop an infectious disease, 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 in response to satisfaction of a predetermined condition indicating that an infection incubation period has elapsed since the presence or absence of the infectious disease was confirmed; 11. The water circulation system of claim 10, wherein, when an individual of the first taxonomic group develops an infectious disease, the last individual that has developed the infectious disease is identified and removed from the aquarium, and then, after an infection incubation period has elapsed, 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.

12. The water circulation system according to claim 8 , wherein the ultraviolet light source is a UV-C LED having an output peak wavelength in a wavelength band of 220 nm or more and 280 nm or less.

13. A management method for managing a water circulation system having a circulation path that purifies water in a plurality of water tanks connected in parallel and returns the purified water to the plurality of water tanks, 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, comprising: the specifying unit includes a sterilization target value including a safe maximum viable count indicating a bacterial count with a high probability that the aquatic organisms will not develop an infectious disease in at least one of the plurality of aquariums where the aquatic organisms are kept, and an allowable immersion time with a high probability that the aquatic organisms will not develop an infectious disease even if the bacterial count in at least one of the plurality of aquariums exceeds the safe maximum viable count; Bacteria information including an increase in viable bacteria count indicating the number of bacteria released into water per unit time by the aquatic organisms that have developed an infectious disease and ultraviolet sensitivity information of the bacteria species to be sterilized; Based on breeding condition information including the water volume of the plurality of aquariums, the number of aquariums, and the lower limit flow rate of the pump, A management method comprising a step of specifying a target ultraviolet intensity of the ultraviolet light source so that the number of viable bacteria in at least one of the plurality of water tanks falls below the safe maximum viable bacteria count within the allowable immersion time when the set flow rate of the pump is set to a target flow rate based on the lower limit flow rate.

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