JP3840189B2 - Seafood farming equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a closed-circulation type seafood culture in which seafood (including artificial seawater) is circulated in a closed system and reused, while seafood is cultivated or temporarily raised in a breeding aquarium. It relates to the device.
[0002]
[Prior art]
A closed-type aquaculture device for raising edible or appreciating seafood at a land point remote from the sea surface has been studied. In this closed circulation type aquaculture apparatus, it is necessary to carry out the process of removing the excrement, residual food, etc. of the reared fishery products from the rearing aquarium in the system without depending on the discharge dilution to the surrounding environment. For this purpose, a circulation path is connected to the breeding aquarium, and the seafood excrement and residual food in the seawater are removed and purified while circulating the seawater in the breeding tank through the circulation path. ing.
[0003]
Microbial treatment using nitrifying bacteria has been the mainstream in the past for decomposing and removing nitrogen components such as ammonia dissolved in seawater from the excrement of seafood, but a method of decomposing and removing it by electrochemical treatment has also been proposed. ing. That is, an electrolysis tank is connected to the circulation path of the breeding aquarium, and hypohalous acid generated by electrolytic decomposition of seawater is reacted with ammonia to remove ammonia (for example, Patent Document 1). reference).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-10724
[Problems to be solved by the invention]
Here, the seawater contains bromine ions at a concentration of 60 mg / liter in addition to chlorine ions at a concentration exceeding 20000 mg / liter as halogen ions. When seawater is electrolyzed, both chlorine ions and bromine ions are oxidized, and hypochlorous acid and hypobromous acid are produced. Hypochlorous acid is represented by the following reaction formula (1) in the presence of bromine ions. As described above, oxygen is rapidly deprived of bromine ions to become chlorine ions and is converted to hypobromite.
[0006]
ClO ⁻ + Br ⁻ → Cl ⁻ + BrO ⁻ (1)
Therefore, when electrolyzing seawater to perform ammonia denitrification, it is mostly hypobromite that ammonia reacts. The general formula for the reaction of hypobromous acid and ammonia is as shown in the following formula (2).
[0007]
2NH ₄ ⁺ + 3BrO ⁻ + 2HO ⁻ → 4N ₂ + 3Br ⁻ + 5H ₂ O (2)
Thus, when hypobromite reacts with ammonia, hypobromite returns to bromine ions, but hypobromite is rich in reactivity, so it reacts well with ammonia, for example, reacts with organic matter in seawater. Thus, it is easy to form a volatile substance or to be bonded to the surface of the piping material of the aquaculture device, and accordingly bromine in seawater is easily lost. In this way, it is actually observed that bromine is gradually lost from the seawater in the circulation system of the aquaculture equipment.
[0008]
And when bromine is lost and deficient in seawater in this way, it is almost hypochlorous acid that reacts with ammonia by electrolysis of seawater, but ammonia between hypochlorous acid and hypobromous acid. There is a clear difference in the denitrification reaction, and hypobromite has higher reaction efficiency with ammonia. That is, the reaction between hypohalonic acid and ammonia produced by electrolyzing seawater first forms a haloamine substance such as monochloramine by combining hypohalous acid and ammonia, and then the haloamines react with each other. In this reaction, nitrogen is generated and hypohalous acid returns to a halogen ion. However, it does not proceed efficiently as in the general formula (2), and the reaction proceeds with hypohalous acid. Must be present in excess. It has been observed that this excess state is required 3-5 times more in the case of hypochlorous acid than in the case of hypobromite.
[0009]
Thus, in a system in which bromine ions are insufficient in seawater, a larger amount of electric power is required to generate surplus hypohalous acid such as hypochlorous acid in an electrolysis tank. In addition, since hypohalous acid is toxic in the rearing of seafood, it is necessary to install a removal tank to remove hypohalous acid, but as the excess hypohalous acid increases, the removal tank also has It will increase in size. Therefore, when seafood is cultivated in seawater lacking bromine ions, there has been a problem that the equipment cost and the operation cost are increased.
[0010]
The present invention has been made in view of the above points, and an object of the present invention is to provide a seafood aquaculture device that can efficiently decompose and remove ammonia in seawater by electrolysis.
[0011]
[Means for Solving the Problems]
The seafood aquaculture apparatus according to claim 1 of the present invention removes nitrogen components such as ammonia in seawater in the electrolysis tank 3 while circulating the seawater in the breeding tank 1 for breeding the seafood through the circulation path 2. The fish and shellfish aquaculture apparatus is provided with a bromine ion addition device 4 for adding bromine ions in the circulation path 2, and at the downstream side of the water flow from the electrolysis tank 3, Reservoir tanks 7 having residual hypohalous acid detectors 5 and 6 are connected to the outlets, respectively, and the residual hypohalous acid detectors 5 and 6 at the inlet and outlet of the reservoir tank 7 It is characterized in that bromine ions are added from the bromine ion addition device 4 when the difference in the concentration of residual hypohalous acid is smaller than a predetermined set value.
[0012]
The invention of claim 2 is characterized in that, in claim 1, the bromine ion addition device 4 is a device for adding a bromine salt solution or a hydrogen bromide solution dropwise to the water in the circulation path 2. It is.
[0013]
The invention of claim 3 is characterized in that, in claim 1, the bromine ion adding device 4 is a device for adding bromine salt powder or tablets dissolved in water in the circulation path.
[0014]
The invention of claim 4 is characterized in that in any one of claims 1 to 3, bromine ions are added to the storage tank 7 on the downstream side of the electrolysis tank 3.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0016]
FIG. 1 shows an example of an embodiment of the present invention. A circulation path 2 is connected to a breeding aquarium 1 where fish and shellfish are bred, and a circulation pump 11 provided in the circulation path 2 is operated. The seawater in the breeding aquarium 1 is circulated through the circulation path 2. And in this circulation path 2, the sedimentation tank 12, the fine bubble SS separation device 13, the electrolysis tank 3, the storage tank 7, the halogen removal tank 14, the circulation pump 11, and the heat exchange in the order along the direction of the seawater flow. A vessel 15 is connected.
[0017]
In addition, a hypohalous acid concentration detection sensor is provided at each of the inlet portion where the seawater flowing through the circulation path 2 flows into the storage tank 7 and the outlet portion where the seawater flows out of the storage tank 7 to detect residual hypohalous acid at the inlet side. A part 5 and a residual hypohalous acid detection part 6 on the outlet side are formed. As this hypohalous acid concentration detection sensor, a current detection type sensor or an ORP (oxidation reduction potential) sensor can be used.
[0018]
A bromine ion adding device 4 is connected to the storage tank 7 so that bromine ions can be added to the seawater in the storage tank 7. As a bromine ion addition source, bromine salts such as sodium bromide and hydrogen bromide can be used. As the bromide ion adding device 4, a bromide solution such as an aqueous solution of sodium bromide or an aqueous solution of hydrogen bromide such as an aqueous solution of hydrogen bromide is dropped into the storage tank 7 to add to the seawater in the circulation path 2. What was formed can be used. Alternatively, a device formed as a device for adding to the seawater in the circulation path 2 by introducing a powder or tablet of bromine salt such as sodium bromide into the storage tank 7 and dissolving it in seawater can also be used. Moreover, the residual hypohalous acid detection units 5 and 6 at the inlet and outlet of the storage tank 7 are electrically connected to a bromine ion addition control unit 17 formed with a built-in control circuit, Data on the amount of residual hypohalous acid detected by each of the remaining hypohalous acid detection units 5 and 6 is input to the bromine ion addition control unit 17. This bromide ion addition controller 17 is also electrically connected to the pump 4a of the bromide ion addition device 4 so that the addition of bromine ions by the bromide ion addition device 4 can be controlled.
[0019]
In the closed circulation type aquaculture system formed as described above, seawater in the breeding aquarium 1 including excrement of reared fish and shellfish and uneaten food is first sent from the bottom of the breeding aquarium 1 to the settling tank 12. After the relatively large particles are settled and separated, the floating solid matter is removed by the fine bubble SS separation device 13 by the pressure floating separation using the fine bubbles. In the fine bubble SS separation device 13, a soluble polymer substance such as protein derived from the secretion of the fish body surface is removed as a foam together with the floating solid matter. Thus, the seawater physically filtered by the settling tank 12 and the fine bubble SS separator 13 is sent to the electrolysis tank 3 and subjected to electrolytic treatment.
[0020]
A pair of electrodes 19 are disposed in the electrolysis tank 3 so as to face each other. The pair of electrodes 19 and 19 are arranged in a direction parallel to the flow of seawater, and a direct current is applied from the power supply device 20. The electrode 19 is made of a platinum / iridium-plated titanium plate or the like, and alternates between the anode and the cathode by reversing the applied potential at every preset time. The electrolysis voltage applied from the power supply device 20 is preferably about 3 to 20 V, and the electrolysis current value is preferably about 10 to 20 A. Then, in the electrolysis tank 3, the seawater undergoes an ammonia denitrification reaction with bromic acid as described above, and ammonia in the seawater is removed. Nitrous acid contained in seawater is oxidized to nitric acid, and seawater is decolorized and sterilized by the oxidizing power of hypohalous acid.
[0021]
The seawater thus electrolyzed in the electrolysis tank 3 passes through the storage tank 7 and is then sent to the halogen removal tank 14. The halogen removal tank 14 is filled with activated carbon, and the active halogen that is not consumed in the reaction is decomposed by the catalytic action of the activated carbon, and the concentration of the active halogen is reduced to a concentration that exhibits fish toxicity. The The seawater treated in the halogen removal tank 14 passes through the heat exchanger 15 via the circulation pump 11, is adjusted to a temperature suitable for the breeding of seafood, and then returned to the breeding tank 1. By circulating the seawater in the breeding aquarium 1 while purifying the seawater in this way, the seafood can be bred in the breeding aquarium 1 for a long period of time without having to exchange the breeding seawater.
[0022]
In addition, when the operation is performed while circulating the seawater in the breeding aquarium 1 through the circulation path 2 as described above, the seawater treated in the electrolysis tank 3 flows into the storage tank 7 and then flows out after being stored for a predetermined time. It is like that. The residual hypohalous acid concentration of the seawater at the inlet flowing into the storage tank 7 is measured by the residual hypohalous acid detection section 5, and the seawater at the outlet flowing out after being retained in the storage tank 7 is measured. The residual hypohalous acid concentration is measured by the residual hypohalous acid detector 6. The residual hypohalous acid concentration data detected by the residual hypohalous acid detection units 5 and 6 in this way is input to the bromine ion addition control unit 17 and calculated, and a difference between the two concentrations is set in advance. When the value is larger than the value, it is determined that a sufficient amount of bromine ions are present in the seawater, and when the difference between the two concentrations is smaller than a predetermined value, it is determined that the bromine ions in the seawater are insufficient.
[0023]
That is, hypochlorous acid is quickly converted to hypobromous acid in the presence of bromine ions as in the above-described formula (1), and therefore residual hypohalous acid in seawater in the presence of bromine ions. Contains only hypobromite (the amount of iodine in seawater is negligible, so it is almost negligible). Since this hypobromite is rich in reactivity as described above, it is likely to be lost by reacting with the organic matter and the surface material of the tank 7 while staying in the storage tank 7, and hypobromine in seawater. The acid concentration is greatly reduced. Therefore, if bromine ions are sufficiently present in the seawater, the concentration of hypobromite, that is, the concentration of hypohalous acid, is greatly reduced while the seawater stays in the storage tank 7 and flows out of the storage tank 7. The residual hypohalous acid concentration of the seawater detected by the residual hypohalous acid detection unit 5 at the outlet is determined by the residual subhalogenous acid concentration detected by the residual hypohalous acid detection unit 6 at the inlet flowing into the storage tank 7. It becomes smaller than the halous acid concentration. On the other hand, if the amount of bromine ions in the seawater decreases, hypochlorous acid will not be converted to hypochlorous acid, so the hypochlorous acid in the seawater generated in the electrolysis tank 3 will remain as hypochlorous acid. The remaining hypohalous acid in the seawater that exists and flows into the storage tank 7 is only hypochlorous acid. And since this hypochlorous acid has lower reactivity than hypochlorous acid, even if seawater stays in the storage tank 7, the amount lost by reacting in the meantime is small. Therefore, if the amount of bromine ions in the seawater is small, the concentration of hypochlorous acid, that is, the concentration of hypohalous acid, does not drop significantly while the seawater stays in the storage tank 7. The residual hypohalous acid concentration of seawater detected by the residual hypohalous acid detection unit 6 at the outlet flowing out of the tank 7 is detected by the residual hypohalous acid detection unit 5 at the inlet flowing into the storage tank 7. The residual hypohalous acid concentration in the seawater is not much smaller.
[0024]
Thus, when the bromine ion concentration in seawater is high, the residual hypohalous acid concentration of seawater at the inlet of the storage tank 7 and the residual hypohalous acid concentration of seawater at the outlet of the storage tank 7 When the concentration of bromine ions in the seawater is low, the residual hypohalous acid concentration of seawater at the inlet of the storage tank 7 and the residual hypohalous acid of seawater at the outlet of the storage tank 7 The difference from the concentration is reduced. When the seawater stays in the storage tank 7 when there is a sufficient amount of bromine ions in the seawater, the residual hypohalous acid concentration of the seawater at the outlet of the storage tank 7 is the inlet of the storage tank 7. If the bromine ion concentration in the seawater is insufficient, the concentration of residual hypohalous acid in the seawater will be reduced. The decrease will be less than 10%. Accordingly, in this case, the residual hypohalous acid concentration measured by the residual hypohalous acid detection unit 5 at the inlet of the storage tank 7 and the residual hypohalous acid detection unit 6 at the outlet of the storage tank 7 are measured. If the difference in residual hypohalous acid concentration is 10% or more, it can be determined that the bromine ion concentration in seawater is sufficient. If the difference in residual hypohalous acid concentration is less than 10%, it can be determined that the bromine ion concentration in seawater is insufficient. The unit 17 controls the pump 4a of the bromine ion addition device 4 to operate, supplies bromine salt or hydrogen bromide from the bromine ion addition device 4 to the storage tank 7, and adds bromine ions to the seawater for replenishment. It is something that can be done.
[0025]
The location of the addition of bromine ions to the seawater may be any location in the circulation path 2, but bromine ions in the storage tank 7 located at the rear stage of the electrolysis tank 3 as in the above embodiment. Is added, it is possible to convert hypochlorous acid produced in the electrolysis tank 3 into hypobromous acid having high reactivity with ammonia, which is preferable in terms of ammonia removal efficiency.
[0026]
Here, when bromine ions are artificially added to seawater to increase the bromine ion concentration as described above, if the bromine ion concentration becomes too high, another function of the electrolysis tank 3 is nitrous acid in water. The observation results show that the ability to oxidize is deteriorated. In other words, nitrifying bacteria grow unintentionally upstream of the electrolysis tank 3 in the aquaculture device and in the piping, upstream of the flow of seawater, and ammonia is oxidized to nitrite by the biological nitrification reaction of this nitrifying bacteria. This nitrite exerts a strong fish poisoning effect on seafood. When seawater containing this nitrous acid flows into the electrolysis tank 3, the nitrous acid is oxidized by electrolysis and can be converted into nitric acid having a much lower toxicity than nitrous acid. However, when bromine ions are excessively added to seawater and the bromine ion concentration becomes too high, oxidation of nitrous acid is inhibited, and a dangerous state occurs due to nitrous acid remaining in seawater. This is because the reaction probability on the surface of the electrode 19 of the electrolysis tank 3 depends on the reactant concentration, and if the bromine ion concentration is excessively higher than the nitrite concentration, the oxidation reaction of nitrous acid is inhibited. In the experimental results, it is determined that oxidation of nitrous acid is inhibited when the bromine ion concentration in seawater exceeds 600 mg / liter. Therefore, the amount of bromine ions added to the seawater is preferably set so that the bromine ion concentration in the seawater in the system of the aquaculture device does not exceed 600 mg / liter.
[0027]
【The invention's effect】
As described above, the fish culture apparatus according to claim 1 of the present invention removes nitrogen components such as ammonia in seawater in the electrolysis tank while circulating the seawater in the breeding tank for breeding the seafood through the circulation path. The fish and shellfish aquaculture apparatus has a bromide ion addition device for adding bromide ions in the circulation path, and is connected to the circulation path at a position downstream of the water flow from the electrolysis tank, to the inlet and outlet parts. Each storage tank having a residual hypohalous acid detection unit is connected, and the difference in the concentration of residual hypohalous acid in seawater measured by the residual hypohalous acid detection unit at the inlet and outlet of the storage tank is predetermined. When bromine ions are added from the bromine ion addition device when the value is smaller than the set value, the shortage of bromine ions can be detected based on the concentration of residual hypohalous acid in seawater. In addition, it is possible to maintain bromine ion concentration in seawater by adding bromine ions to seawater in response to the detection of shortage of bromine ions. Efficient decomposition and removal of ammonia in seawater by electrolysis tank It can be done.
[0028]
The invention of claim 2 is the addition of bromine ions to seawater because the bromine ion addition device in claim 1 is an apparatus for adding a bromine salt solution or a hydrogen bromide solution dropwise to the water in the circulation path. Can be reliably performed.
[0029]
The invention of claim 3 is the apparatus of claim 1, wherein the bromine ion addition apparatus is an apparatus for adding bromine salt powder or tablets dissolved in water in the circulation path, so that the addition of bromine ions to seawater is ensured. Can be done.
[0030]
Further, the invention of claim 4 is the method according to any one of claims 1 to 4, wherein bromine ions are added in the storage tank downstream of the electrolysis tank, so that hypochlorous acid produced in the electrolysis tank is reduced. In the storage tank, it can be immediately converted into hypobromous acid having high reactivity to ammonia, and the efficiency of ammonia removal can be increased.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Breeding tank 2 Circulation path 3 Electrolysis tank 4 Bromine ion addition apparatus 5 Residual hypohalous acid detection part 6 Residual hypohalous acid detection part 7 Reservoir

Claims (4)

Add bromine ions to the circulation path in a fish culture device that removes nitrogen components such as ammonia in the seawater in the electrolysis tank while circulating the seawater in the breeding tank for raising seafood through the circulation path In addition to a bromine ion addition device, a storage tank having a residual hypohalous acid detection unit at each of an inlet and an outlet is connected to a circulation path at a position downstream of the water flow from the electrolysis tank. When bromine ions are added from the bromine ion addition device when the difference in the concentration of residual hypohalous acid in seawater measured by the residual hypohalous acid detection unit at the inlet and outlet is smaller than the preset value A seafood aquaculture device characterized by comprising: The apparatus for cultivating fish and shellfish according to claim 1, wherein the bromine ion adding device is a device for adding a bromine salt solution or a hydrogen bromide solution dropwise to the water in the circulation path. The apparatus for cultivating seafood according to claim 1, wherein the bromine ion adding apparatus is an apparatus for adding bromine salt powder or tablets by dissolving them in water in a circulation path. 4. The fish and shellfish cultivation apparatus according to claim 1, wherein bromine ions are added to a storage tank downstream of the electrolysis tank.

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