Aquaponics system

Abstract

To provide an aquaponics system that can reduce salt damage to plants.SOLUTION: A system includes an aquaculture tank 10 in which fish are raised in water with a higher salinity than fresh water, a filtration tank 20 that nitrifies ammonia contained in aquaculture wastewater discharged from the aquaculture tank 10 and converts it into nitric acid, a first normal vegetable tank 31 and a second normal vegetable tank 32 in which plants P are cultivated, a plurality of supply paths that can supply water with different salinities to the first normal vegetable tank 31 and the second normal vegetable tank 32, and a switching unit that switches whether or not water can flow through the plurality of supply paths so that the salinities of the water in the first normal vegetable tank 31 and the second normal vegetable tank 32 increase as the growth of the plants P progresses.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an aquaponics system technology that combines fish farming and plant cultivation. [Background technology]

[0002] Conventionally, aquaponics system technology that combines fish farming and plant cultivation has been publicly known, as described in Patent Document 1, for example.

[0003] The aquaponics system described in Patent Document 1 includes a breeding tank for breeding fish and shellfish, a cultivation bed for cultivating plants, a biological filtration device for nitrifying ammonia, and a water supply pump for sending water from the breeding tank to the cultivation bed. The aquaponics system is configured so that water is circulated through the breeding tank, the biological filtration device, and the cultivation bed by the operation of the water supply pump. By circulating water in this way, the aquaponics system can nitrify ammonia contained in the waste of fish and shellfish in the biological filtration tank and convert it into nitrate, and the nitrate can be absorbed by the plants in the cultivation bed. This allows the aquaponics system to simultaneously cultivate fish and plants.

[0004] If it were possible to cultivate saltwater fish, which are more preferred as food than freshwater fish, in a breeding tank as described in Patent Document 1, the profitability of the aquaponics system could be improved. However, in this case, it is necessary to cultivate plants in salt water (seawater, artificial seawater, etc.), so if one tries to grow vegetables that are usually cultivated in fresh water, such as lettuce or Japanese mustard spinach, there is a possibility that the production volume of the vegetables will decrease due to salt damage. For this reason, there is a demand for technology that can reduce the effects of salt damage and improve the production volume of vegetables. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6047749 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and the problem to be solved by the present invention is to provide an aquaponics system capable of reducing salt damage to plants. [Means for solving the problem]

[0007] The problem to be solved by the present invention has been described above, and the means for solving this problem will now be described.

[0008] That is, in claim 1, the system comprises an aquaculture tank in which fish are raised in water having a higher salinity than freshwater, a nitrification tank in which ammonia contained in the aquaculture wastewater discharged from the aquaculture tank is nitrified and converted into nitric acid, a cultivation tank in which plants are cultivated, a plurality of supply paths capable of supplying water having different salinities to the cultivation tank, and a switching unit that switches whether or not water can flow through the plurality of supply paths so that the salinity of the water in the cultivation tank increases as the growth of the plants progresses.

[0009] In claim 2, the multiple supply paths include a wastewater supply path capable of supplying the aquaculture wastewater discharged from the aquaculture tank to the cultivation tank, and the switching unit allows the aquaculture wastewater to circulate through the wastewater supply path at least during the harvest season of the plants.

[0010] In claim 3, the switching unit switches between allowing and not allowing the water to flow through the plurality of supply paths so that the salinity of the water in the cultivation tank is increased a plurality of times.

[0011] In claim 4, the cultivation tanks are provided in plurality so that the growth conditions of the plants differ from one another, the supply path is configured so that water having a different salinity concentration can be supplied to each cultivation tank, and the switching unit switches whether or not water can flow through the supply path for each cultivation tank.

[0012] In claim 5, the growth condition of the plant includes the height condition of the plant.

[0013] In claim 6, the present invention further includes a measuring unit that measures the height of the plant, and the switching unit switches between allowing and not allowing water to flow through the multiple supply paths depending on the measurement result of the height of the plant by the measuring unit.

[0014] In claim 7, the apparatus further comprises a removal section capable of removing more nitric acid than the cultivation tank, and a circulation path through which the aquaculture wastewater circulates through the aquaculture tank, the nitrification tank, and the removal section.

[0015] In claim 8, the removal section is configured to remove the nitric acid by organisms.

[0016] In claim 9, a first removal state in which the nitrate is removed by the organisms in the removal section and a second removal state in which the nitrate is removed by the plants in the cultivation tank are switched depending on the growth status of the fish.

[0017] In claim 10, the first removal state and the second removal state are switched by replacing the organisms grown in the aquarium. Effect of the Invention

[0018] The present invention has the following advantages.

[0019] In claim 1, salt damage to plants can be reduced.

[0020] According to claim 2, nitric acid can be efficiently treated.

[0021] In claim 3, the stress on the plant can be alleviated.

[0022] In claim 4, salt damage to plants in different growing conditions can be reduced.

[0023] In claim 5, the flow of water can be switched on and off depending on the height of the plant.

[0024] In claim 6, the flow of water can be easily switched on and off.

[0025] In claim 7, adverse effects on fish growth can be suppressed.

[0026] In claim 8, the aquaculture wastewater can be purified by using living organisms.

[0027] In claim 9, the first removal state and the second removal state can be switched according to the growth state of the fish.

[0028] According to claim 10, space can be saved. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is an explanatory diagram showing an aquaponics system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing the cultivation tank in detail. [Diagram 3] FIG. 4 is an explanatory diagram showing a state in which the height of a plant is measured. [Figure 4] 10 is a flowchart showing a flow control process for switching the water flow path. [Diagram 5] FIG. 13 is a diagram showing an example of the relationship between water for cultivating plants and plant height. [Figure 6] FIG. 4 is an explanatory diagram showing a state in which a freshwater nutrient solution is supplied to a first normal vegetable tank and a second normal vegetable tank. [Figure 7] FIG. 2 is an explanatory diagram showing a state in which aquaculture wastewater is supplied to a first normal vegetable tank. [Figure 8] FIG. 11 is an explanatory diagram showing an aquaponics system according to a second embodiment. [Figure 9]10 is a flowchart showing a distribution control process according to a second embodiment. [Figure 10] FIG. 11 is a diagram showing an example of the relationship between water for cultivating a plant and plant height in the second embodiment. [Figure 11] FIG. 11 is an explanatory diagram showing an aquaponics system according to a third embodiment. [Figure 12] 11 is a flowchart showing a cultivation tank switching process for switching a normal vegetable tank to a nitric acid absorption tank. [Figure 13] FIG. 11 is an explanatory diagram showing a state in which aquaculture wastewater is supplied to a first normal vegetable tank in the third embodiment. [Figure 14] FIG. 11 is an explanatory diagram showing the state in which the first normal vegetable tank is changed into a nitric acid absorption tank. [Figure 15] FIG. 11 is an explanatory diagram showing a state in which aquaculture wastewater is supplied to a second normal vegetable tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] An aquaponics system 1 according to a first embodiment of the present invention will be described below. The aquaponics system 1 is for simultaneously cultivating fish and growing a plant P. First, an overview of the aquaponics system 1 will be described.

[0031] When cultivating fish, ammonia contained in fish wastewater is harmful to fish, so it is necessary to purify the aquaculture wastewater used in the fish farming. Specifically, it is necessary to oxidize the ammonia in the aquaculture wastewater to nitrate and nitrite, and then denitrify the nitrate. Nitrate and the like are substances that are weakly toxic to fish, but are nutrients for plant P. Focusing on this point, the aquaponics system 1 replaces the above-mentioned denitrification with the cultivation of plant P, thereby cultivating fish and cultivating plant P at the same time while purifying the aquaculture wastewater polluted by fish farming. The configuration of the aquaponics system 1 will be described below with reference to Figs. 1 to 3.

[0032] The aquaponics system 1 includes an aquaculture tank 10, a filtration tank 20, a cultivation tank 30, a drainage valve 40, a nutrient solution tank 50, a nutrient solution valve 60, an acquisition unit 70, and a control unit 80.

[0033] The aquaculture tank 10 shown in Fig. 1 is for raising fish. In this embodiment, saltwater fish are raised in the aquaculture tank 10. In this case, water suitable for raising saltwater fish is stored in the aquaculture tank 10. For example, water with a higher salt concentration than freshwater (natural seawater, artificial seawater, etc.) is stored in the aquaculture tank 10.

[0034] The filtration tank 20 is for filtering the aquaculture wastewater and adjusting the components of the aquaculture wastewater. In this embodiment, the filtration includes both physical filtration and biological filtration. The filtration tank 20 is connected to the aquaculture tank 10 via a first drainage pipe K11 so that the aquaculture wastewater discharged from the aquaculture tank 10 flows into the filtration tank 20. The filtration tank 20 can filter impurities contained in the aquaculture wastewater by physical filtration. Furthermore, the filtration tank 20 can nitrify ammonia contained in the aquaculture wastewater and convert it into nitric acid by biological filtration.

[0035] The filtration tank 20 can also adjust the composition of the aquaculture wastewater by, for example, adding components necessary for the fish in the aquaculture tank 10 and the plants P in the cultivation tank 30 to the aquaculture wastewater. The filtration tank 20 is connected to the cultivation tank 30 via the second drainage piping K12 so that the aquaculture wastewater that has been filtered and has its composition adjusted in this manner flows into the cultivation tank 30.

[0036] The cultivation tank 30 is primarily for cultivating plants P. In the cultivation tank 30, the plants P are cultivated by hydroponic cultivation. The aquaculture wastewater that flows into the cultivation tank 30 has nitric acid removed therein, and is returned to the aquaculture tank 10 via the third drainage pipe K13, the filtration tank 20, and the fourth drainage pipe K14. This allows the aquaponics system 1 to simultaneously cultivate fish and the plants P. The detailed configuration of the cultivation tank 30 will be described later.

[0037] As described above, since saltwater fish are raised in the culture tank 10, the salt concentration of the culture wastewater circulating in the aquaponics system 1 is at least higher than that of freshwater. If vegetables that are normally grown in freshwater, such as lettuce and Japanese mustard spinach, are grown for a long period of time (for example, from the seedling stage to the harvest stage) in this culture wastewater with a high salt concentration, the production volume of the vegetables may decrease due to salt damage.

[0038] Therefore, the aquaponics system 1 supplies water with different salinity concentrations to the cultivation tank 30 so that the salinity increases as the growth of the plant P progresses. In this embodiment, the aquaponics system 1 supplies water to the cultivation tank 30 in the order of a freshwater nutrient solution with a lower salinity than the aquaculture wastewater, and then the aquaculture wastewater. In this way, the aquaponics system 1 cultivates the plant P (vegetables) in the aquaculture wastewater only during the period when the plant P has a relatively high salt tolerance, thereby reducing salt damage to the plant P.

[0039] The following describes the detailed configuration of the cultivation tank 30 and the configuration of various devices (drain valve 40, nutrient solution tank 50, nutrient solution valve 60, acquisition unit 70, and control unit 80) related to the supply of water to the cultivation tank 30. As shown in FIG. 2, the cultivation tank 30 includes a first normal vegetable tank 31, a second normal vegetable tank 32, and a high nitrate absorption tank 33.

[0040] The first normal vegetable tank 31 and the second normal vegetable tank 32 are for cultivating vegetables (such as lettuce) that are normally cultivated in fresh water as the plant P. As shown in FIG. 3, the first normal vegetable tank 31 and the second normal vegetable tank 32 have panels 31b and 32b that support the plant P installed on the upper sides of the water tanks 31a and 32a, so that the plant P can be cultivated (hydroponically cultivated) in the water in the water tanks 31a and 32a. The same types of vegetables are cultivated in the first normal vegetable tank 31 and the second normal vegetable tank 32. The plant P cultivated in the first normal vegetable tank 31 is in a more advanced state of growth than the plant P cultivated in the second normal vegetable tank 32.

[0041] The plants P cultivated in the first normal vegetable tank 31 and the like are not particularly limited, but are preferably plants P that are suitable for hydroponic cultivation and have relatively high consumer demand. For example, the plants P cultivated in the first normal vegetable tank 31 and the like are preferably leafy vegetables, herbs, tomatoes, and the like. By cultivating such plants P, the profitability of cultivating the plants P can be improved.

[0042] The high nitrate absorption tank 33 shown in Fig. 2 is a tank for cultivating organisms specialized in absorbing nitrate. In the high nitrate absorption tank 33, organisms capable of growing in water with a high salinity and absorbing nitrate are grown. Specifically, at least one of halophytes (ice plants, etc.), seaweeds, microalgae, etc. are grown in the high nitrate absorption tank 33. The high nitrate absorption tank 33 can remove more nitrate than the first normal vegetable tank 31 and the second normal vegetable tank 32 by having the nitrate in the aquaculture wastewater absorbed by halophytes, etc.

[0043] The above-mentioned second drainage pipe K12 (piping connecting the filtration tank 20 and the cultivation tank 30) branches midway and is connected to the first normal vegetable tank 31, the second normal vegetable tank 32, and the high nitrate absorption tank 33, respectively. In the following, the part of the second drainage pipe K12 connected to the first normal vegetable tank 31 is referred to as the "first branch K12a." In addition, the part of the second drainage pipe K12 connected to the second normal vegetable tank 32 is referred to as the "second branch K12b." In addition, the part of the second drainage pipe K12 connected to the high nitrate absorption tank 33 is referred to as the "third branch K12c."

[0044] The third drainage pipe K13 also branches midway and is connected to the first normal vegetable tank 31, the second normal vegetable tank 32, and the high nitrate absorption tank 33, respectively. In the following, the part of the third drainage pipe K13 that is connected to the first normal vegetable tank 31 is referred to as the "first branch K13a." In addition, the part of the third drainage pipe K13 that is connected to the second normal vegetable tank 32 is referred to as the "second branch K13b." In addition, the part of the third drainage pipe K13 that is connected to the high nitrate absorption tank 33 is referred to as the "third branch K13c."

[0045] The drain valve 40 is for switching whether or not the aquaculture wastewater is allowed to flow to the cultivation tank 30. The drain valve 40 can switch whether or not the aquaculture wastewater is allowed to flow to each of the first normal vegetable tank 31, the second normal vegetable tank 32, and the high nitrate absorption tank 33. The drain valve 40 includes a first drain valve 41 to a third drain valve 43.

[0046] The first drain valve 41 is for switching whether or not the aquaculture wastewater is allowed to flow to the first normal vegetable tank 31. The first drain valve 41 is provided on the upstream side and downstream side of the first normal vegetable tank 31 in the flow direction of the aquaculture wastewater. Specifically, the first drain valve 41 is provided in the first branch portions K12a and K13a of the second drain pipe K12 and the third drain pipe K13.

[0047] The second drain valve 42 is for switching whether or not the aquaculture wastewater is allowed to flow to the second normal vegetable tank 32. The second drain valves 42 are provided on the upstream and downstream sides (second branch portions K12b and K13b) of the second normal vegetable tank 32 in the flow direction of the aquaculture wastewater.

[0048] The third drain valve 43 is for switching whether or not the aquaculture wastewater is allowed to flow to the high nitrate absorption tank 33. The third drain valve 43 is provided on the upstream side and downstream side (third branch portions K12c and K13c) of the high nitrate absorption tank 33 in the flow direction of the aquaculture wastewater.

[0049] In this embodiment, the third drain valve 43 is basically maintained in an open state. Therefore, the aquaculture drainage can circulate through the aquaculture tank 10, the filtration tank 20, and the high nitrate absorption tank 33 via the first drain pipe K11, the second drain pipe K12 (third branch K12c), the third drain pipe K13 (third branch K13c), and the fourth drain pipe K14, regardless of the open / closed state of the first drain valve 41 and the second drain valve 42.

[0050] The nutrient solution tank 50 is for adjusting the nutritional components when the plants P in the first normal vegetable tank 31 and the second normal vegetable tank 32 are cultivated in freshwater (freshwater nutrient solution). The nutrient solution tank 50 stores freshwater nutrient solution. The freshwater nutrient solution is water suitable for cultivating the plants P in the first normal vegetable tank 31 and the like. The salt concentration of the freshwater nutrient solution is at least lower than the salt concentration of the aquaculture wastewater. For example, the salt concentration of the freshwater nutrient solution is about the same as that of freshwater (0.05% or less). The nutrient solution tank 50 can adjust the nutritional components by adding nutrients to the freshwater nutrient solution based on the measurement results of a water quality sensor, for example.

[0051] The nutrient solution tank 50 is connected to the first normal vegetable tank 31 and the like via a first nutrient solution pipe K21 so that freshwater nutrient solution flows into the first normal vegetable tank 31 and the second normal vegetable tank 32. The first nutrient solution pipe K21 branches midway and is connected to the first normal vegetable tank 31 and the second normal vegetable tank 32, respectively. In the following, the part of the first nutrient solution pipe K21 that is connected to the first normal vegetable tank 31 is referred to as the "first branch section K21a." In the following, the part of the first nutrient solution pipe K21 that is connected to the second normal vegetable tank 32 is referred to as the "second branch section K21b."

[0052] The nutrient solution tank 50 is connected to the first normal vegetable tank 31 and the like via a second nutrient solution pipe K22 so that freshwater nutrient solution returns from the first normal vegetable tank 31 and the second normal vegetable tank 32 to the nutrient solution tank 50. The second nutrient solution pipe K22 branches midway and is connected to the first normal vegetable tank 31 and the second normal vegetable tank 32, respectively. In the following, the part of the second nutrient solution pipe K22 that is connected to the first normal vegetable tank 31 is referred to as the "first branch K22a." In the following, the part of the second nutrient solution pipe K22 that is connected to the second normal vegetable tank 32 is referred to as the "second branch K22b."

[0053] The nutrient solution valve 60 is for switching whether or not freshwater nutrient solution is allowed to flow to the first normal vegetable tank 31 and the second normal vegetable tank 32. The nutrient solution valve 60 can switch whether or not freshwater nutrient solution is allowed to flow to the first normal vegetable tank 31 and the second normal vegetable tank 32, respectively. The nutrient solution valve 60 includes a first nutrient solution valve 61 and a second nutrient solution valve 62.

[0054] The first nutrient solution valve 61 is for switching whether or not the freshwater nutrient solution flows into the first normal vegetable tank 31. The first nutrient solution valve 61 is provided on the upstream side and downstream side of the first normal vegetable tank 31 in the flow direction of the freshwater nutrient solution. Specifically, the first nutrient solution valve 61 is provided in the first branched portions K21a and K22a of the first nutrient solution piping K21 and the second nutrient solution piping K22.

[0055] The second nutrient solution valve 62 is for switching whether or not the freshwater nutrient solution flows into the second normal vegetable tank 32. The second nutrient solution valve 62 is provided on the upstream side and downstream side (second branch portions K21b and K22b) of the second normal vegetable tank 32 in the flow direction of the freshwater nutrient solution.

[0056] The acquisition unit 70 is for acquiring growth information related to the growth status of the plant P cultivated in the first normal vegetable tank 31 and the second normal vegetable tank 32. The growth information is information that makes it possible to determine the growth status of the plant P. The growth information includes various pieces of information that change depending on the growth status of the plant P. For example, the growth information includes information that makes it possible to determine the height (grass height H) and leaf area of ​​the plant P.

[0057] The acquisition unit 70 is configured with, for example, a camera (such as an RGB-D camera) capable of acquiring distance information to a subject. As shown in Fig. 3, the acquisition unit 70 is installed in the cultivation tank 30 so as to be able to photograph the plants P in the first normal vegetable tank 31 and the second normal vegetable tank 32. The acquisition unit 70 of this embodiment is provided so as to be able to photograph the plants P from above.

[0058] The control unit 80 shown in Fig. 2 and Fig. 3 is for controlling the flow of water to the first normal vegetable tank 31 and the second normal vegetable tank 32 according to the growth information acquired by the acquisition unit 70. The control unit 80 includes a calculation unit, a memory unit, and the like. The control unit 80 is connected to the drain valve 40, the nutrient solution valve 60, and the acquisition unit 70. Note that Fig. 2 shows a state in which only the third drain valve 43 of the drain valve 40 and the nutrient solution valve 60 is connected to the control unit 80, but in reality, each of the valves 41 to 43, 61, and 62 is connected to the control unit 80.

[0059] The control unit 80 can open and close the second drain pipe K12 and the third drain pipe K13 by sending a signal to the drain valve 40, and control the flow of the aquaculture drainage water to the first normal vegetable tank 31 and the second normal vegetable tank 32. The control unit 80 can open and close the first nutrient solution pipe K21 and the second nutrient solution pipe K22 by sending a signal to the nutrient solution valve 60, and control the flow of the freshwater nutrient solution to the first normal vegetable tank 31 and the second normal vegetable tank 32. The control unit 80 can obtain an image of the plant P, including the distance from the acquisition unit 70 to the plant P, by receiving a signal from the acquisition unit 70. The control unit 80 can measure (calculate) the plant height H based on the image result, and determine the growth status of the plant P.

[0060] The information for determining the growth status of the plant P is not limited to the plant height H, and can be changed arbitrarily. For example, the control unit 80 can determine the growth status of the plant P by measuring the leaf area of ​​the plant P based on the image capturing result of the acquisition unit 70 (camera).

[0061] An example of a flow control process for controlling the flow of water to the first normal vegetable tank 31 and the second normal vegetable tank 32 will be described below with reference to FIG. 4. The flow control process shown in FIG. 4 is for controlling the flow of water in one tank (the first normal vegetable tank 31 or the second normal vegetable tank 32). The control unit 80 executes the flow control process for each of the first normal vegetable tank 31 and the second normal vegetable tank 32. The control unit 80 also executes the flow control process repeatedly. The control of the flow of water in the second normal vegetable tank 32 is the same as that in the first normal vegetable tank 31. Therefore, the flow control process will be described below with the first normal vegetable tank 31 as an example. When the flow control process is started, the control unit 80 proceeds to step S10.

[0062] In step S10, the control unit 80 acquires the photographing results of the plant P from the acquisition unit 70, and measures the plant height H based on the photographing results. When the process of step S10 ends, the control unit 80 proceeds to step S20.

[0063] In step S20, if the measurement result of the grass height H in step S10 is 0 mm (step S20: Yes), the control unit 80 proceeds to step S30. On the other hand, if the measurement result is not 0 mm (step S20: No), the control unit 80 proceeds to step S40.

[0064] In step S30, the control unit 80 controls the first drain valve 41 and the first nutrient solution valve 61 to close, thereby prohibiting the circulation of the aquaculture wastewater and the freshwater nutrient solution to the first normal vegetable tank 31. When the processing of step S30 ends, the control unit 80 ends the circulation control processing. This makes it possible to prevent water from circulating in the first normal vegetable tank 31 when it is considered that the plant P is not being cultivated in the first normal vegetable tank 31.

[0065] In step S40, if the measurement result of the grass height H in step S10 is less than 60 mm (step S40: Yes), the control unit 80 proceeds to step S50. On the other hand, if the measurement result is 60 mm or more (step S50: No), the control unit 80 proceeds to step S60.

[0066] In step S50, the control unit 80 controls the first drain valve 41 and the first nutrient solution valve 61 so that the freshwater nutrient solution flows into the first normal vegetable tank 31. Specifically, the control unit 80 controls the first drain valve 41 to close, thereby prohibiting the flow of aquaculture wastewater into the first normal vegetable tank 31. The control unit 80 also controls the first nutrient solution valve 61 to open, thereby allowing the flow of freshwater nutrient solution into the first normal vegetable tank 31. This allows the freshwater nutrient solution to circulate between the nutrient solution tank 50 and the first normal vegetable tank 31. When the processing of step S50 ends, the control unit 80 ends the flow control processing.

[0067] In step S60, if the water flowing through the first normal vegetable tank 31 is switched from freshwater nutrient solution to aquaculture wastewater in step S70 (the water flow route is switched), the control unit 80 proceeds to step S70 after the water in the first normal vegetable tank 31 is drained into the nutrient solution tank 50. If the flow route is not switched, the water (aquaculture wastewater) in the first normal vegetable tank 31 is not drained, and the control unit 80 proceeds to step S70.

[0068] The method of determining whether the circulation route is switched in step S60 is not particularly limited. For example, the control unit 80 can determine whether the circulation route is switched by checking the open / closed state of the first drain valve 41 and the first nutrient solution valve 61. The method of draining the water from the first normal vegetable tank 31 is not particularly limited. For example, the water from the first normal vegetable tank 31 may be drained by an operator or the like.

[0069] In step S70, the control unit 80 controls the drain valve 40 and the nutrient solution valve 60 so that the aquaculture wastewater flows to the first normal vegetable tank 31. Specifically, the control unit 80 controls the first drain valve 41 to open, thereby allowing the aquaculture wastewater to flow to the first normal vegetable tank 31. The control unit 80 also controls the first nutrient solution valve 61 to close, thereby prohibiting the flow of freshwater nutrient solution to the first normal vegetable tank 31. This allows the aquaculture wastewater to circulate between the aquaculture tank 10, the filtration tank 20, and the first normal vegetable tank 31.

[0070] In this embodiment, when the water circulation route is switched (when switching from freshwater nutrient solution to aquaculture wastewater), the water in the first normal vegetable tank 31 is drained in step S60, and then the aquaculture wastewater is supplied in step S70. This makes it possible to prevent freshwater nutrient solution with a low salt concentration from flowing into the aquaculture tank 10, thereby suppressing adverse effects on fish growth. When the process of step S70 ends, the control unit 80 ends the circulation control process.

[0071] As shown in Figures 5 and 6, according to the flow control process, the plants P in the first normal vegetable tank 31 are cultivated in a freshwater nutrient solution with a low salt concentration during the seedling period (period when the plant height H is low) when their growth is relatively slow and their salt tolerance is relatively low (step S50). Also, as shown in Figures 5 and 7, the plants P are cultivated in the aquaculture wastewater from the planting period when their growth has progressed and their salt tolerance has increased until the harvest period (step S70). In this state, nitric acid is absorbed by the plants P in the first normal vegetable tank 31, and the aquaculture wastewater is purified.

[0072] According to this configuration, the water flow path can be appropriately controlled according to the growth state of the plant P, so that even when saltwater fish farming is combined with the cultivation of the plant P (vegetables that are usually grown in freshwater), it is possible to reduce salt damage to the plant P and suppress a decrease in the production volume of the plant P. In addition, it is possible to achieve the objective of aquaponics, which is to cultivate the plant P using polluted aquaculture wastewater from fish farming.

[0073] Furthermore, in this embodiment, the plants P are cultivated in the aquaculture wastewater from the time when the plant height H exceeds 60 mm until harvest (at least during the harvest season). This allows the plants P, which have absorbed a greater amount of nitrate, to absorb the nitrate in the aquaculture wastewater, making it possible to efficiently treat the nitrate in the aquaculture wastewater. This configuration makes it possible to create an environment that is good for the growth of the fish and plants P (an environment in which the nitrate concentration in the aquaculture tank 10 is low and salt damage to the plants P can be reduced), allowing the fish and plants P to grow appropriately.

[0074] Here, when cultivating saltwater fish and cultivating plants P (vegetables that are usually grown in freshwater), there is a possibility that the amount of nitrate absorbed by the plants P will decrease due to the influence of salinity. Therefore, in this embodiment, a high nitrate absorption tank 33 is installed to improve the purification capacity (amount of nitrate absorbed) of the aquaculture wastewater. This makes it possible to suppress an increase in the nitrate concentration in the aquaculture tank 10 even if the amount of nitrate absorbed by the plants P decreases due to the influence of salinity. Therefore, it is possible to suppress adverse effects on fish growth without growing a large amount of plants P on a vast area of ​​land.

[0075] Furthermore, in the distribution control process, the control unit 80 changes the distribution route in accordance with the grass height H, so that it is possible to reduce the workload of the worker (labor saving).

[0076] As described above, the aquaponics system 1 according to this embodiment includes an aquaculture tank 10 in which fish are raised in water having a higher salinity than freshwater, a filtration tank 20 (nitrification tank) in which ammonia contained in the aquaculture wastewater discharged from the aquaculture tank 10 is nitrified and converted into nitric acid, a first normal vegetable tank 31 and a second normal vegetable tank 32 (cultivation tanks) in which plants P are cultivated, a plurality of supply paths (a second drainage pipe K12 and a first nutrient solution pipe K21) capable of supplying water having different salinities to the first normal vegetable tank 31 and the second normal vegetable tank 32, and a switching unit (a drainage valve 40, a nutrient solution valve 60, and a control unit 80) that switches whether or not water can flow through the plurality of supply paths so that the salinity of the water in the first normal vegetable tank 31 and the second normal vegetable tank 32 increases as the growth of the plants P progresses.

[0077] By configuring in this manner, salt damage to the plant P can be reduced.

[0078] In addition, the multiple supply paths include a wastewater supply path (second drainage piping K12) capable of supplying the aquaculture wastewater discharged from the aquaculture tank 10 to the first normal vegetable tank 31 and the second normal vegetable tank 32, and the switching unit (control unit 80, etc.) allows the aquaculture wastewater to circulate in the wastewater supply path at least during the harvest season of the plants P (step S40: No, steps S60 and S70).

[0079] By configuring in this way, nitric acid can be efficiently treated.

[0080] In addition, multiple cultivation tanks are provided so that the growth conditions of the plants P are different from one another, and the supply path is configured so that water with different salinity concentrations can be supplied to each cultivation tank, and the switching unit (control unit 80, etc.) switches the flow of water through the supply path for each cultivation tank (see Figures 6 and 7). In this embodiment, as an example of the plurality of cultivation tanks 30, a first normal vegetable tank 31 and a second normal vegetable tank 32 are provided.

[0081] With this configuration, the flow of water can be appropriately controlled for each cultivation tank, thereby reducing salt damage to plants P in different growth conditions.

[0082] Further, the growth state of the plant P includes the height state of the plant P (plant height H).

[0083] By configuring in this way, it is possible to switch whether or not water flows depending on the height of the plant P.

[0084] In addition, the aquaponics system 1 further includes a measurement unit (acquisition unit 70 and control unit 80) that measures the height of the plant P, and the switching unit switches whether or not water is allowed to flow through the multiple supply paths depending on the measurement result of the height of the plant P by the measurement unit (steps S20 to S70).

[0085] With this configuration, it is possible to easily switch between allowing and not allowing water to flow.

[0086] In addition, the aquaculture tank 10 further includes a high nitrate absorption tank 33 (removal section) capable of removing more nitrate than the first normal vegetable tank 31 and the second normal vegetable tank 32, and a circulation path (first drainage pipe K11, second drainage pipe K12 (third branch section 12c), third drainage pipe K13 (third branch section K13c), fourth drainage pipe K14) through which the aquaculture wastewater circulates through the aquaculture tank 10, the filtration tank 20 and the high nitrate absorption tank 33.

[0087] By configuring in this manner, the purification capacity of the aquaculture wastewater can be improved, thereby suppressing adverse effects on fish growth.

[0088] The high nitrate absorption tank 33 is configured to remove the nitrate by organisms.

[0089] By configuring in this way, it is possible to purify aquaculture wastewater using living organisms.

[0090] The filtration tank 20 according to this embodiment is one embodiment of a nitrification tank according to the present invention. Moreover, the first normal vegetable tank 31 and the second normal vegetable tank 32 according to this embodiment are one embodiment of the cultivation tank 30 according to the present invention. Moreover, the second drainage pipe K12 and the first nutrient solution pipe K21 according to this embodiment are one embodiment of a plurality of supply paths according to the present invention. Moreover, the drain valve 40, the nutrient solution valve 60 and the control unit 80 according to this embodiment are an embodiment of a switching unit according to the present invention. Moreover, the second drainage pipe K12 according to this embodiment is one embodiment of a drainage supply path according to the present invention. The acquisition section 70 and the control section 80 according to this embodiment are an embodiment of a measurement section according to the present invention. Moreover, the high nitric acid absorption tank 33 according to this embodiment is one embodiment of the removal section according to the present invention. Furthermore, the first drainage pipe K11, the second drainage pipe K12 (third branch portion 12c), the third drainage pipe K13 (third branch portion K13c), and the fourth drainage pipe K14 in this embodiment are one embodiment of the circulation path according to the present invention.

[0091] Although the first embodiment of the present invention has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention described in the claims.

[0092] For example, although saltwater fish are cultured in the culture tank 10, the type of fish cultured in the culture tank 10 is not limited to saltwater fish. For example, the culture tank 10 may be used to culture freshwater fish that can be cultured in water (seawater, artificial seawater, etc.) with a higher salt concentration than freshwater.

[0093] In this embodiment, the plant P is cultivated in the aquaculture wastewater after being cultivated in the freshwater nutrient solution, but the water used for cultivating the plant P after the freshwater nutrient solution may be water that contains at least the aquaculture wastewater (water that uses the aquaculture wastewater). For example, it is also possible to cultivate the plant P in water obtained by mixing the aquaculture wastewater with other water after cultivating the plant P in the freshwater nutrient solution.

[0094] In this embodiment, the plant P is grown in a freshwater nutrient solution during the seedling period (see FIG. 5), but the cultivation period of the plant P in the freshwater nutrient solution is not particularly limited and can be changed as desired. For example, the cultivation period of the plant P in the freshwater nutrient solution can be changed depending on the type of the plant P. The cultivation period of the plant P in the aquaculture wastewater can also be changed as desired.

[0095] The high nitrate absorption tank 33 (removal section) is configured to grow at least one of halophytes, seaweeds, microalgae, etc., but the specific configuration of the high nitrate absorption tank 33 is not particularly limited as long as it is configured to be able to remove more nitrate than the first normal vegetable tank 31 and the second normal vegetable tank 32. For example, the high nitrate absorption tank 33 can also decompose nitrate by utilizing the action of microorganisms such as denitrifying bacteria.

[0096] Next, an aquaponics system 101 according to a second embodiment will be described.

[0097] In the following description, components that are configured in the same manner as the aquaponics system 1 according to the first embodiment are given the same reference numerals as in the first embodiment, and descriptions thereof will be omitted.

[0098] The aquaponics system 1 of the first embodiment shown in Fig. 1 cultivates plants P in the first normal vegetable tank 31 and the like using two types of water (freshwater nutrient solution and aquaculture wastewater) with different salinity concentrations. In contrast, the aquaponics system 101 of the present embodiment cultivates plants P using three or more types of water, as shown in Fig. 8. In this embodiment, the plants P are cultivated using three types of water: freshwater nutrient solution, aquaculture wastewater, and mixed water.

[0099] For the sake of convenience, the second normal vegetable tank 32 and the high nitrate absorption tank 33 are omitted in Fig. 8, but in reality, the high nitrate absorption tank 33 is configured to circulate the aquaculture wastewater, as in the first embodiment (see Fig. 2). The second normal vegetable tank 32 is configured in the same manner as the first normal vegetable tank 31. For this reason, the following will explain the configuration for cultivating plants P in freshwater nutrient solution, aquaculture wastewater, and mixed water (the configuration of the second embodiment) using the first normal vegetable tank 31 as an example.

[0100] The aquaponics system 101 includes an aquaculture tank 10, a filtration tank 20, a cultivation tank 30, a drainage valve 40, a nutrient solution tank 50, a nutrient solution valve 60, an acquisition unit 70, and a control unit 80, as well as a mixing tank 110 and a mixing valve 120 for supplying mixed water to the plant P.

[0101] The mixing tank 110 is for storing mixed water. The mixed water is water with a higher salinity than the freshwater nutrient solution and a lower salinity than the aquaculture wastewater. The mixed water is produced by mixing the aquaculture wastewater and freshwater. The mixing tank 110 can adjust the nutritional components, similar to the nutrient solution tank 50.

[0102] The mixing tank 110 is connected to the first normal vegetable tank 31 via a first mixing pipe K31 so that the mixed water flows into the first normal vegetable tank 31. The mixing tank 110 is also connected to the first normal vegetable tank 31 via a second mixing pipe K32 so that the mixed water returns from the first normal vegetable tank 31.

[0103] The mixing valve 120 is for switching between allowing and not allowing the mixed water to flow, and is provided in each of the first mixing pipe K31 and the second mixing pipe K32.

[0104] Although not shown in the figures, the first mixing pipe K31 and the second mixing pipe K32 are branched in the middle and connected to the first normal vegetable tank 31 and the second normal vegetable tank 32, respectively, in the same manner as the first nutrient solution pipe K21 (see FIG. 2). The mixing valves 120 are provided at the branching portions of the first mixing pipe K31 and the second mixing pipe K32, respectively, in the same manner as the nutrient solution valve 60 (see FIG. 2), and can switch between allowing and not allowing the mixed water to flow to the first normal vegetable tank 31 and the second normal vegetable tank 32, respectively.

[0105] The flow control process of this embodiment shown in FIG. 9 will be described below using the first normal vegetable tank 31 as an example. The flow control process of this embodiment is for controlling the flow of the mixed water in addition to the aquaculture wastewater and the freshwater nutrient solution. The flow control process controls the flow of water in one tank (the first normal vegetable tank 31 or the second normal vegetable tank 32). The control unit 80 executes the flow control process for each of the first normal vegetable tank 31 and the second normal vegetable tank 32. The control unit 80 also executes the flow control process repeatedly. The control of the flow of water in the second normal vegetable tank 32 is the same as that in the first normal vegetable tank 31. Therefore, the flow control process will be described below using the first normal vegetable tank 31 as an example. When the flow control process is started, the control unit 80 proceeds to step S110.

[0106] In step S110, the control unit 80 measures the grass height H in the same manner as in step S10 of the first embodiment (FIG. 4), and proceeds to step S120. In step S120, if the measurement result is 0 mm (step S120: Yes), the control unit 80 proceeds to step S130. On the other hand, if the measurement result is not 0 mm (step S120: No), the control unit 80 proceeds to step S140.

[0107] In step S130, the control unit 80 controls the first drain valve 41, the first nutrient solution valve 61, and the mixing valve 120 to close, thereby prohibiting the circulation of the aquaculture wastewater, the freshwater nutrient solution, and the mixed water into the first normal vegetable tank 31. When the processing of step S130 ends, the control unit 80 ends the circulation control processing.

[0108] In step S140, if the measurement result of the grass height H in step S110 is less than 60 mm (step S140: Yes), the control unit 80 proceeds to step S150. On the other hand, if the measurement result is 60 mm or more (step S140: No), the control unit 80 proceeds to step S160.

[0109] In step S150, the control unit 80 controls the first drain valve 41, the first nutrient solution valve 61, and the mixing valve 120 so that the freshwater nutrient solution circulates between the nutrient solution tank 50 and the first normal vegetable tank 31. Specifically, the control unit 80 controls the first drain valve 41 and the mixing valve 120 to close, thereby prohibiting the flow of the culture wastewater and mixed water to the first normal vegetable tank 31. The control unit 80 also controls the first nutrient solution valve 61 to open, thereby allowing the flow of the freshwater nutrient solution to the first normal vegetable tank 31. When the processing of step S150 ends, the control unit 80 ends the flow control processing.

[0110] In step S160, if the measurement result of the grass height H in step S110 is less than 100 mm (step S160: Yes), the control unit 80 proceeds to step S170. On the other hand, if the measurement result is 100 mm or more (step S160: No), the control unit 80 proceeds to step S190.

[0111] In step S170, if the water flowing through the first normal vegetable tank 31 is switched from freshwater nutrient solution to mixed water (the water flow route is switched) in step S180 described below, the control unit 80 proceeds to step S180 after the water in the first normal vegetable tank 31 is drained into the nutrient solution tank 50. If the flow route is not switched, the control unit 80 proceeds to step S180 without draining the water in the first normal vegetable tank 31. The method of determining whether the flow route is switched in step S170 is the same as step S60 in the first embodiment (FIG. 4).

[0112] In step S180, the control unit 80 controls the first drain valve 41, the first nutrient solution valve 61, and the mixing valve 120 so that the mixed water circulates between the mixing tank 110 and the first normal vegetable tank 31. Specifically, the control unit 80 controls the first drain valve 41 and the first nutrient solution valve 61 to close, thereby prohibiting the flow of the aquaculture wastewater and the freshwater nutrient solution to the first normal vegetable tank 31. The control unit 80 also controls the mixing valve 120 to open, thereby allowing the flow of the mixed water to the first normal vegetable tank 31. When the processing of step S180 ends, the control unit 80 ends the flow control processing.

[0113] In step S190, if the water flowing through the first normal vegetable tank 31 is switched from mixed water to aquaculture wastewater in step S200 (the water flow route is switched) described below, the control unit 80 proceeds to step S200 after the water in the first normal vegetable tank 31 is drained into the mixing tank 110. If the flow route is not switched, the water in the first normal vegetable tank 31 is not drained, and the control unit 80 proceeds to step S200. The method of determining whether the flow route is switched in step S190 is the same as that in step S170.

[0114] In step S200, the control unit 80 controls the first drain valve 41, the first nutrient solution valve 61, and the mixing valve 120 so that the aquaculture wastewater circulates among the aquaculture tank 10, the filtration tank 20, and the first normal vegetable tank 31. Specifically, the control unit 80 controls the first nutrient solution valve 61 and the mixing valve 120 to close, thereby prohibiting the flow of the freshwater nutrient solution and mixed water to the first normal vegetable tank 31. The control unit 80 also controls the first drain valve 41 to open, thereby allowing the flow of the aquaculture wastewater to the first normal vegetable tank 31. When the processing of step S200 ends, the control unit 80 ends the flow control processing.

[0115] 10, according to the flow control process, the control unit 80 can gradually (multiple times) increase the salinity of the water in which the plant P is grown as the growth progresses. For example, the plant P can be grown in freshwater nutrient solution during the seedling period, grown in mixed water immediately after planting, and grown in aquaculture wastewater before harvesting. This makes it possible to prevent the root zone environment (salt concentration) from changing significantly, and to alleviate stress on the plant P.

[0116] In this embodiment, the salt concentration in the first normal vegetable tank 31 is increased twice as the growth of the plant P progresses, but the number of times the salt concentration is increased is not limited to this embodiment. For example, by providing a plurality of mixing tanks 110 and mixing valves 120, it is also possible to increase the salt concentration three or more times. This allows the salt concentration in the first normal vegetable tank 31 to be managed more precisely, and therefore makes it possible to effectively prevent the root zone environment (salt concentration) from changing significantly.

[0117] As described above, the switching unit (control unit 80, etc.) in this embodiment switches whether or not water flows through the multiple supply paths (the second drainage piping K12, the first nutrient solution piping K21, and the first mixing piping K31) so that the salinity concentration of the water in the first normal vegetable tank 31 and the second normal vegetable tank 32 is increased multiple times.

[0118] By configuring in this manner, the stress on the plant P can be alleviated.

[0119] The second drainage pipe K12, the first nutrient solution pipe K21, and the first mixing pipe K31 according to this embodiment are one embodiment of a plurality of supply pipes according to the present invention.

[0120] In the present embodiment, as an example, the freshwater nutrient solution and the mixed water are supplied to the first normal vegetable tank 31 through different paths (the first nutrient solution piping K21 and the first mixing piping K31), but the configuration for supplying the freshwater nutrient solution and the mixed water to the first normal vegetable tank 31 is not limited to this embodiment and can be changed as desired. For example, by connecting one tank in which the freshwater nutrient solution and the mixed water are stored to the first normal vegetable tank 31, it is also possible to supply the freshwater nutrient solution and the mixed water to the first normal vegetable tank 31 through a common path.

[0121] Next, an aquaponics system 201 according to a third embodiment will be described.

[0122] In the following description, components that are configured in the same manner as the aquaponics system 1 according to the first embodiment are given the same reference numerals as in the first embodiment, and descriptions thereof will be omitted.

[0123] The aquaponics system 1 of the first embodiment shown in Fig. 2 removes nitrate from the aquaculture wastewater using the high nitrate absorption tank 33 regardless of the growth conditions of the plants P and fish. In contrast, the aquaponics system 201 of this embodiment removes nitrate from the aquaculture wastewater by switching the roles of the first normal vegetable tank 31 and the high nitrate absorption tank 33 depending on the growth conditions of the fish (see Figs. 13 and 15). The roles are switched by replacing the organisms grown in the common tank 31a through which the aquaculture wastewater flows. A specific description will be given below.

[0124] Fig. 11 shows the configuration of an aquaponics system 201 in which nitrate in the aquaculture wastewater is removed by the first normal vegetable tank 31 without using the high nitrate absorption tank 33. In the state shown in Fig. 11, the aquaponics system 201 does not have the high nitrate absorption tank 33, unlike the first embodiment.

[0125] 11, when the high nitrate absorption tank 33 is not provided, the first drain valve 41 is opened and the second drain valve 42 is maintained in a closed state. Therefore, the aquaculture wastewater circulates through the aquaculture tank 10, the filtration tank 20, and the first normal vegetable tank 31 via the first drain pipe K11, the second drain pipe K12 (first branch K12a), the third drain pipe K13 (first branch K13a), and the fourth drain pipe K14.

[0126] When the high nitrate absorption tank 33 is not provided, the first nutrient solution valve 61 is closed and the second nutrient solution valve 62 is maintained in an open state. Therefore, the freshwater nutrient solution circulates through the nutrient solution tank 50 and the second normal vegetable tank 32.

[0127] The filtration tank 20 of this embodiment is provided with a concentration sensor 21 that measures the nitrate concentration of the aquaculture wastewater. The concentration sensor 21 is connected to a control unit 80 (see FIG. 2). The control unit 80 can obtain the measurement result of the nitrate concentration based on a signal from the concentration sensor 21.

[0128] The control unit 80 can execute the circulation control process of the first embodiment (FIG. 4) as well as the cultivation tank switching process shown in FIG. 12. The cultivation tank switching process is for switching the first normal vegetable tank 31 to the high nitrate absorption tank 33 depending on the growth status of the fish. The control unit 80 repeatedly executes the cultivation tank switching process. When the cultivation tank switching process is started, the control unit 80 proceeds to step S210.

[0129] In step S210, the control unit 80 acquires the measurement result of the nitric acid concentration from the concentration sensor 21, and if the measurement result is below a concentration that affects the growth of fish (step S210: Yes), the control unit 80 proceeds to step S220. In this embodiment, the control unit 80 proceeds to step S220 if the measurement result is below 400 ppm. On the other hand, if the measurement result is 400 ppm or more (step S210: No), the control unit 80 proceeds to step S230. Note that the threshold value (400 ppm) in step S210 is an example and can be changed depending on the type of fish cultivated in the fish farm tank 10, etc.

[0130] In step S220, the control unit 80 maintains the state shown in Fig. 11. That is, when the measurement result of the nitric acid concentration is relatively low, the control unit 80 removes nitric acid from the aquaculture wastewater by having the plants P in the first normal vegetable tank 31 absorb the nitric acid. As shown in Fig. 12, when the process of step S220 ends, the control unit 80 ends the cultivation tank switching process.

[0131] In step S230, the control unit 80 switches the first normal vegetable tank 31 to the high nitrate absorption tank 33. At this time, for example, the panel 31b supporting the plant P is replaced with a panel 33b supporting the plant P1 which is less susceptible to salt damage than the plant P (see FIG. 14). When the process of step S230 ends, the control unit 80 ends the cultivation tank switching process.

[0132] According to the cultivation tank switching process, the control unit 80 can appropriately switch between the plants P and P1 cultivated in the tank 31a of the first normal vegetable tank 31 depending on the growth status of the fish. Specifically, when the growth status of the fish is not very advanced (for example, when cultivating young fish), the amount of ammonia contained in the aquaculture wastewater is relatively small. Therefore, when the growth status of the fish is not very advanced, the amount of nitrate converted in the filtration tank 20 is relatively small, and even if the amount of nitrate absorbed by the plant P (lettuce, etc.) decreases due to the influence of salinity, the plant P can sufficiently absorb nitrate.

[0133] Therefore, as shown in FIG. 13, the control unit 80 checks the growth status of the fish (the balance between the amount of nitrate converted in the filtration tank 20 and the amount of nitrate absorbed by the plants P) from the nitrate concentration of the aquaculture wastewater in the filtration tank 20, and if the growth status of the fish is not progressing well, causes the plants P in the first normal vegetable tank 31 to absorb nitrate (step S210: Yes, step S220).

[0134] In addition, the amount of ammonia contained in the aquaculture wastewater increases as the fish grow. Therefore, when the fish grow, the amount of nitrate converted in the filtration tank 20 increases, and there is a possibility that the plants P in the first normal vegetable tank 31 cannot keep up with the absorption of the nitrate.

[0135] Therefore, as shown in Fig. 14, when it is considered that the fish growth is progressing and the absorption of nitrate cannot keep up, the control unit 80 switches the first normal vegetable tank 31 to the high nitrate absorption tank 33 (step S210: No, step S230). In this way, the control unit 80 can efficiently absorb the increased nitrate caused by the progress of the fish growth into the plants P1 in the high nitrate absorption tank 33, and suppress an increase in the nitrate concentration (adverse effect on the growth of the fish).

[0136] When the control unit 80 switches the first normal vegetable tank 31 to the high nitrate absorption tank 33, it executes the flow control process of the first embodiment shown in Fig. 4 to control the flow of water to the second normal vegetable tank 32. As a result, as shown in Fig. 15, when the growth of the plants P in the second normal vegetable tank 32 progresses, the control unit 80 can remove nitrate from the aquaculture wastewater by the high nitrate absorption tank 33 and the second normal vegetable tank 32.

[0137] In this way, the high nitrate absorption tank 33 does not always remove nitrate regardless of the growth conditions of the fish and plants P, but is also capable of removing nitrate only when the fish have grown to the point where the balance between the amount of nitrate generated (the amount converted in the filtration tank 20) ​​and the amount absorbed is disrupted (step S210: No).

[0138] As described above, the aquaponics system 201 of this embodiment can switch between a first removal state (state shown in Figure 15) in which the nitrate is removed by the organisms (plant P1 or algae) in the high nitrate absorption tank 33, and a second removal state (state shown in Figure 13) in which the nitrate is removed by the plants P in the first normal vegetable tank 31, depending on the growth status of the fish (steps S210 to S230).

[0139] With this configuration, it is possible to switch between the first removal state and the second removal state depending on the growth status of the fish.

[0140] Moreover, the first removal state and the second removal state are switched by replacing the organisms grown in the water tank 31a (step S230).

[0141] With this configuration, the organisms in the first normal vegetable tank 31 and the high nitrate absorption tank 33 can be grown in the common tank 31a, thereby making it possible to save space. [Explanation of symbols]

[0142] 1. Aquaponics System 10 Aquaculture tank 31 First normal vegetable tank 32 Second normal vegetable tank F-fish P plant

Claims

1. Aquaculture tanks in which fish are raised in water with a higher salt concentration than freshwater; a nitrification tank for nitrifying ammonia contained in the aquaculture wastewater discharged from the aquaculture tank into nitric acid; A cultivation tank for cultivating plants; A plurality of supply paths capable of supplying water having different salinity concentrations to the cultivation tank; A switching unit that switches whether or not water flows through the multiple supply paths so that the salinity of the water in the cultivation tank increases as the growth status of the plant progresses; Equipped with Aquaponics system.

2. The plurality of supply paths include: A drainage supply path is provided that can supply the aquaculture drainage discharged from the aquaculture tank to the cultivation tank, The switching unit is Allowing the aquaculture wastewater to flow through the wastewater supply path at least during the harvest season of the plant; 2. The aquaponics system of claim 1.

3. The switching unit is Switching between allowing and not allowing the water to flow through the plurality of supply paths so that the salinity of the water in the cultivation tank is increased a plurality of times.

3. The aquaponics system according to claim 1 or 2.

4. The cultivation tank is A plurality of the plants are provided so that the growth conditions of the plants are different from each other, The supply path is The water having a different salinity can be supplied to each of the cultivation tanks, The switching unit is Switching whether or not water flows through the supply path for each of the cultivation tanks.

3. The aquaponics system according to claim 1 or 2.

5. The growth status of the plant includes: The height status of the plant is included.

3. The aquaponics system according to claim 1 or 2.

6. A measuring unit that measures the height of the plant is further provided. The switching unit is switching between allowing and disabling the flow of water through the plurality of supply paths depending on a result of the measurement of the height of the plant by the measurement unit; 6. The aquaponics system of claim 5.

7. A removal unit capable of removing more of the nitric acid than the cultivation tank; a circulation path through which the aquaculture wastewater circulates through the aquaculture tank, the nitrification tank, and the removal unit; Further comprising:

3. The aquaponics system according to claim 1 or 2.

8. The removal unit includes: The nitrate is removed by a living organism.

8. The aquaponics system of claim 7.

9. A first removal state in which the nitrate is removed by the organisms in the removal section and a second removal state in which the nitrate is removed by the plants in the cultivation tank are switched according to the growth status of the fish.

9. The aquaponics system of claim 8.

10. The first removal state and the second removal state are The organisms grown in the tanks can be changed by replacing them.

10. The aquaponics system of claim 9.

Images