JP2021184702A - Closed circulation type breeding water purification system for high density/fast-growing aquaculture - Google Patents

Abstract

To provide a breeding water purification system that enables simplification and miniaturization of a device structure, can reduce equipment cost and running expense while maintaining sufficient purification performance, and can reduce cleaning cost.SOLUTION: A closed circulation type breeding water purification system for high density aquaculture includes: a denitrifying tank 12 for performing denitrification processing of a breeding water 10a from a breeding aquarium 10 under an anaerobic atmosphere; a nitrification tank 14 for performing nitrification processing of the breeding water 10a under an aerobic atmosphere; an aerator 15 for performing aeration of the breeding water 10a; a fine bubble generator 17 for generating fine bubbles in the breeding water 10a; and a foam separation device 18 where at least a portion of the fine bubbles in the breeding water 10a is separated and removed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a breeding water purification system for high-density aquaculture that performs completely closed circulation.

In closed circulation breeding, water quality management of breeding water is important. Increasing pollutants such as ammonia, nitrite ions and / or nitrate ions in the breeding water that adversely affect the breeding body will have a significant life-and-death effect on the breeding fish and shellfish. In particular, ammonia easily binds to hemoglobin, which is one of the blood components and plays a role of transporting oxygen to the cells of the whole body of the breeding body, and when ammonia increases in the breeding water, the fish and shellfish of the breeding body become suffocated. In the worst case, it can be fatal.

In breeding water, ammonia is produced when bacteria decompose the residue of fish and shellfish that is the breeding body, which is the residue of food or excrement. The residue consists of organic nitrogen compounds such as proteins, and this organic nitrogen is divided into insoluble and water-soluble.

The organic nitrogen compound is insoluble and is decomposed into urea or the like, which is a water-soluble organic nitrogen, by the action of microorganisms or an enzymatic reaction, and the water-soluble organic nitrogen is decomposed into ammonia. For example, urea, which is a water-soluble organic nitrogen in excrement, is decomposed into carbon dioxide and ammonia by urease, which is a urea-degrading enzyme.

Ammonia is water soluble and exists as ammonium ions. Ammonium ions generate nitrite ions by ammonia acid oxidizing bacteria in an opportunistic atmosphere. Nitrite ions generate nitrate ions by nitrite-oxidizing bacteria in an opportunistic atmosphere.
NH ₄ ⁺ + 2O ₂ (Ammonia acid oxidizing bacteria) ⇒ NO ₂ ⁺ + 2H ₂ O

There are two types of treatment methods for nitrite ion and nitrate ion, a physical treatment method and a biological treatment method. Of these, ion exchange methods, electrodialysis methods, reverse osmosis membrane methods and catalytic denitrification methods are known as physical treatment methods, while heterotrophic denitrification methods and catalytic denitrification methods are known as biophysical treatment methods. The autotrophic denitrification method is known.

The ion exchange method in the physical treatment method is a method of removing nitrite ions and nitrate ions from water by bringing the ion exchange resin into contact with breeding water and performing ion exchange with the ions of the ion exchange resin. However, this method has a problem that the equipment cost is high and the processing cost is extremely high because a large amount of sodium chloride is required for the regeneration of the ion exchange resin.

The electrodialysis method in the physical treatment method is a method in which breeding water is partitioned by an ion-selective membrane and nitrite ions and nitrate ions are separated by induction by electrode charge. However, this method has a problem that the equipment cost is high.

The reverse osmosis membrane method in the physical treatment method is a method for separating nitrite ion and nitrate ion from water. A reverse osmosis membrane that allows water to pass through and does not allow impurities other than water such as ions and salts to permeate is used to separate nitrite ions and nitrate ions from water. However, this method has a problem that it is necessary to separately treat the separated high-concentration nitrate ion and nitrite ion.

The decatalyzed nitrogen method in the physical treatment method is a method of reducing nitrate nitrogen to nitrogen in the presence of a catalyst by directly using hydrogen gas as a hydrogen donor, but this method has a high cost of hydrogen gas. There was a problem.

In the dependent nutrient denitrification method in the biological treatment method, water containing nitrite ion and nitrate ion is passed through a granular filter medium layer to which dependent nutrient denitrifying bacteria have adhered and proliferated, and the nitrogen gas is reduced. The method. The autotrophic denitrification method in the biological treatment method is a method of treating sulfur denitrification bacteria, which are autotrophic bacteria, using a filter layer to which the autotrophic bacteria have adhered and proliferated. However, the treatment method using these heterotrophic denitrifying bacteria or autotrophic denitrifying bacteria has a problem that the water temperature greatly affects the treatment efficiency, and further, sulfuric acid is easily generated as a by-product, and advanced technology is required for the operation management of the device. There was a problem that it was needed. Sulfuric acid has a great effect on the breeding body.

Various methods have been conventionally proposed as a method for treating breeding water in a breeding water purification system. For example, Patent Documents 1 to 5 describe a treatment method called a circulating nitrification denitrification method. This treatment method uses nitric acid bacteria that decompose organic nitrogen containing ammonia into nitrite ions or nitrate ions using oxygen, and a carbon source in the state of anoxic oxygen of 0.5 to 1.0 ppm or less. It is a method that utilizes the biochemical properties of two types of microorganisms, nitrate ions or denitrifying bacteria that decompose nitrate ions into nitrogen.

A breeding water purification device in a general breeding water purification system consists of a denitrifying tank containing denitrifying bacteria and a nitrifying tank containing nitrifying bacteria. Only stirring is performed without stirring, and in the nitrification tank, air is blown into the treated water to dissolve it. In the nitrification tank, an oxidation reaction occurs in which organic nitrogen containing ammonia becomes nitrite ion or nitrate ion, and a part of the treated water is returned to the denitrification tank. At this time, since oxygen in the treated water is consumed by the activity of the nitrifying bacteria, the treated water containing nitrate ion and nitrite ion is supplied to the denitrification tank in an oxygen-deficient state. That is, in the nitrification tank, the reaction of ammonia / organic nitrogen + nitrifying bacteria + oxygen ⇒ oxygen-deficient + nitrite ion + nitrate ion is carried out.

When nitrate ions and nitrite ions are supplied to the denitrification tank, they are decomposed into oxygen and nitrogen by the denitrifying bacteria. Oxygen can be supplied by sending the purified treated water to the nitrification tank, and the amount of oxygen sent to the nitrification tank can be reduced. By repeating such operations, it becomes possible to decompose pollutants in the treated water. That is, in the denitrification tank, a reaction of nitrate ion / nitrite ion + anaerobic bacteria + organic matter ⇒ oxygen / nitrogen + others is carried out.

In the circulation type filtration device described in Patent Document 6, when the water level in the tank rises to the upper end of the inner pipe, water is discharged to the outside of the tank through the inner pipe by a siphon mechanism, and the water level in the tank becomes the outer pipe. When it descends to the vicinity of the opening, the siphon mechanism is stopped by the action of the float and the water level is repeatedly raised to intermittently aerate the filter medium laid in the tank.

The water treatment apparatus described in Patent Document 7 has a configuration in which a main route for breeding water to circulate in a water tank and a nitrification tank and an auxiliary route for intermittently flowing breeding water to a denitrification tank are provided. It is a standard water treatment device for closed circulation breeding.

From the viewpoint of growing the breeding body and maintaining the nitrification ability, it is important to increase the oxygen dissolution concentration in the breeding water and the treated water. The amount of oxygen dissolved in water is determined by temperature and pressure, and is limited to about 10 ppm at normal temperature and pressure. As for the amount of oxygen dissolved, the movement of oxygen in the boundary layer between water and oxygen (hereinafter referred to as the boundary film) is rate-determining, so if the contact area between water and oxygen is increased, it will take a shorter time. It is possible to increase the amount of oxygen dissolved. In a general closed circulation type breeding system, the air of microbubbles or nanobubbles is injected into water as bubbles of small diameter, and when handling the same amount of air, the smaller the diameter of bubbles, the more bubbles there are. Since the contact area becomes larger as the number of bubbles increases, the aim is to reduce the diameter of the bubbles.

Patent Document 8 describes a water tank for aquaculture using a nozzle for generating micro bubbles having a diameter of 50 μm or less, and according to this water tank for aquaculture, good oxygen dissolution performance can be obtained. It is said that.

In Patent Document 9, the active sludge mixture from the biological reaction tank is filtered by forming a dynamic filtration layer of sludge on the surface of the filter in a filtration separation tank equipped with a water-permeable filter to obtain filtered water. The activated sludge mixture after filtration is configured to be returned to the biological reaction tank, and when the filter body is washed, the active sludge mixture in the filtration separation tank is completely returned to the biological reaction tank, or to the filtration separation tank. Described is a filter cleaning device configured to backwash the inside of the filter when it is filled with filtered water and return the backwash wastewater to the biological reaction vessel.

Patent Document 10 describes a breeding water purification system for closed circulation type breeding, which is provided with a denitrification tank, a nitrification tank and an aeration tank, and oxygen is supplied from the aeration tank to the aquaculture tank. As a result, in the breeding water purification system of Patent Document 10, the purification efficiency and oxygen dissolution rate of the breeding water can be improved, and by downsizing the filtration device and reducing the amount of treated water circulation, the required area and required energy of the device, and further. Says that it can achieve a reduction in cleaning costs.

Japanese Unexamined Patent Publication No. 2002-263678 Japanese Unexamined Patent Publication No. 09-0477880 Japanese Unexamined Patent Publication No. 08-117793 Japanese Unexamined Patent Publication No. 09-010996 Japanese Unexamined Patent Publication No. 08-323393 Japanese Patent No. 467807 Japanese Unexamined Patent Publication No. 2013-188719 Japanese Unexamined Patent Publication No. 2010-0573366 Japanese Unexamined Patent Publication No. 2002-177892 Japanese Patent No. 6534245

The treatment methods described in Patent Documents 1 to 5 described above are highly efficient and low cost for treated water having a high concentration of necessary decomposition components such as sludge and sewage, but are used for breeding water of closed circulation type breeding. Since the treatment capacity is excessive and a circulation pump between the vitrification tank and the denitrification tank is also required, there is a problem that the equipment cost and the operation cost per unit pollutant treatment amount become excessive. Further, although pH fluctuation control is required to maintain the purification efficiency, there is also a problem that the control of the neutralizing agent becomes sophisticated due to the small amount of treatment. Furthermore, in these treatment methods, air is supplied from the bottom of the nitrification tank, and the amount of oxygen dissolved in water increases in proportion to the water depth, so it is necessary to secure a water depth of about 4 m, but it is a closed circulation type. In breeding, it was not realistic to use a water tank or nitrification tank with a water depth of 4 m or more due to the height restrictions of the building and the problem of cost.

Further, according to the circulation type filtration device described in Patent Document 6, there is a problem that the required power is increased due to the clogging of the filter medium portion and the siphon portion, and cleaning is required every 1 to 2 years. there were. Moreover, only the nitrification tank was handled by this circulation type filtration device.

Further, the water treatment apparatus described in Patent Document 7 requires a mechanism for switching the treatment route of the breeding water depending on the concentration of nitrite ion or nitrate ion in the breeding water, which causes a problem that the equipment cost becomes excessive.

Furthermore, in the aquaculture tank described in Patent Document 8, in order to generate fine bubbles, it is necessary to ventilate air through a nozzle having a small diameter or a porous material, which not only causes an increase in required power, but also a nozzle or a tank. There was a problem that contaminants during breeding adhered to the porous material and easily caused clogging, leading to equipment troubles.

Even in the cleaning device described in Patent Document 9, there is a problem that sufficient purification performance cannot be obtained due to clogging of the carrier and knitting of breeding water.

Further, according to the breeding water purification system described in Patent Document 10, when the aeration tank is operated without changing water for a long period of about 6 to 12 months, excrement of cultured fish and plankton generated in water are deposited in the aeration tank. However, as the size of the fish increases, the frequency of cleaning the aeration tank increases to about once every two weeks at the maximum. In particular, in equipment aimed at high-speed growth, the weight of the juveniles that start breeding first and the weight of the control that has finally grown will increase 6 to 8 times, so the amount of excrement and plankton generated will also increase. From the beginning, it was necessary to install a large-sized one with high separation capacity.

Therefore, an object of the present invention is to provide a breeding water purification system capable of downsizing and simplifying the device configuration.

Another object of the present invention is to provide a breeding water purification system capable of reducing equipment costs and operating costs while maintaining sufficient purification performance.

Still another object of the present invention is to provide a breeding water purification system capable of reducing cleaning costs.

According to the present invention, the closed circulation type breeding water purification system for high-density aquaculture is connected to the breeding water tank and is filled with denitrifying bacteria-carrying particles inside, so that the breeding water from the breeding water tank is in an anaerobic atmosphere. It is connected to the denitrification tank and the breeding water tank, and the inside is filled with nitrifying bacteria-bearing particles, and the inflowed breeding water is nitrified in an aerobic atmosphere. A gas is supplied to the nitrification tank, the aeration device that is connected to the nitrification tank and the breeding water tank to perform aeration treatment of the breeding water, and the orifice that is connected to the breeding water tank and exhibits an aspirator function to generate fine bubbles. It has a swirling flow type fine bubble generation nozzle, and is connected to a fine bubble generator that generates fine bubbles in breeding water, a fine bubble generator, and an aeration device, and at least a part of the fine bubbles in breeding water. It is equipped with a foam separator for separating and removing the gas.

Fine bubbles are generated in the breeding water by a swirling flow type fine bubble generation nozzle that supplies gas to the part of the orifice that exhibits an aspirator function to generate fine bubbles. As a result, both microbubbles and ultrafine bubbles can be efficiently generated. Microbubbles are tinged with negative ions, and have the effect of binding to dirt, which is positive ions, and floating to raise dirt to the surface of the water. Since the ultrafine bubble shrinks and disappears in water and dissolves the gas in the water, the gas can be efficiently dissolved in the water. As a result, the circulating breeding water can be maintained in the optimum state. In addition, by using a swirling flow type fine bubble generation nozzle, it is possible to simplify the device configuration of the breeding water purification system for closed circulation type breeding, and it is expected that the downsizing of the filtration tank and the reduction of pump power can be expected. In addition, by simplifying and reducing the equipment and reducing the required power, the initial cost and operating cost of the equipment can be reduced by 50% or more as compared with the conventional closed circulation type breeding equipment. This has the advantage that even a small-scale system can easily make the land-based aquaculture business profitable by closed-circulation breeding. That is, according to the present invention, it is possible to reduce the size and simplification of the device configuration, reduce the equipment cost and the operating cost while maintaining sufficient purification performance, and reduce the cleaning cost. be able to.

It is preferable that the fine bubble generator is configured to selectively generate air fine bubbles and oxygen fine bubbles.

In this case, a dissolved oxygen meter for detecting the dissolved oxygen concentration in the breeding water is further provided, and the fine bubble generator generates an air fine bubble when the dissolved oxygen concentration detected by the dissolved oxygen meter is equal to or higher than a predetermined value. When the detected dissolved oxygen concentration is less than a predetermined value, it is preferable that the oxygen fine bubble is generated.

The fine bubble generator uses either oxygen or air for the above-mentioned fine bubble generating nozzle that generates fine bubbles that have a bubble diameter of 50 μm to 200 μm and do not dissolve in the breeding water, and the gas supply port of the fine bubble generating nozzle. It is also preferable to have a switching mechanism for selectively supplying.

It is also preferable that the fine bubble generator is provided with a flow rate adjusting mechanism capable of adjusting the amount of gas supplied. As a result, the purification of water can be controlled manually or automatically depending on the degree of contamination of the water, and at the same time, the efficiency of dissolving oxygen in the cultured water can be increased, which is suitable for high-density and high-speed growth of the breeding body. A closed circulation type aquaculture facility can be realized.

It is also preferable that the fine bubble generator is configured so that the bubble diameter of the fine bubble can be adjusted according to the density and / or the body weight of the breeding body. When the density of the breeding body is low or the weight is small, the amount of gas supplied is reduced to reduce the amount of oxygen dissolved in the breeding water, and the breeding body becomes denser or heavier and the breeding water is bred. When it becomes dirty with body excrement, it is possible to increase the bubble diameter of the bubble and increase the number of bubbles for foam separation by increasing the gas supply amount or gas supply pressure to effectively remove the dirt in the water. can. As a result, it becomes possible to efficiently dissolve oxygen in breeding water at low cost.

It is also preferable that the fine bubble generator is configured to generate 500 or more fine bubbles having a bubble diameter of 1 μm to 500 μm.

It is also preferable that the foam separation device is configured so that the pollutants in the breeding water are adsorbed on the surface and the fine bubbles that have floated up are discharged and removed.

In this case, it is more preferable that the foam separation device includes a sub-chamber configured to increase the flow distance of the fine bubbles supplied from the fine bubble generator and to change the flow direction of the fine bubbles.

According to the present invention, fine bubbles are generated in the breeding water by a swirling flow type fine bubble generation nozzle that supplies gas to a portion of the orifice that exhibits an aspirator function to generate fine bubbles. As a result, both microbubbles and ultrafine bubbles can be efficiently generated. Microbubbles are tinged with negative ions, and have the effect of binding to dirt, which is positive ions, and floating to raise dirt to the surface of the water. Since the ultrafine bubble shrinks and disappears in water and dissolves the gas in the water, the gas can be efficiently dissolved in the water. As a result, the circulating breeding water can be maintained in the optimum state. In addition, by using a swirling flow type fine bubble generation nozzle, it is possible to simplify the device configuration of the breeding water purification system for closed circulation type breeding, and it is expected that the downsizing of the filtration tank and the reduction of pump power can be expected. In addition, by simplifying and reducing the equipment and reducing the required power, the initial cost and operating cost of the equipment can be reduced by 50% or more as compared with the conventional closed circulation type breeding equipment. This has the advantage that even a small-scale system can easily make the land-based aquaculture business profitable by closed-circulation breeding. That is, according to the present invention, it is possible to reduce the size and simplification of the device configuration, reduce the equipment cost and the operating cost while maintaining sufficient purification performance, and reduce the cleaning cost. be able to.

It is a block diagram schematically showing the structure in one Embodiment of the breeding water purification system of this invention. It is a block diagram which shows schematic structure of the fine bubble generator in the breeding water purification system of FIG. It is a block diagram which shows schematic structure of the foam separation apparatus in the breeding water purification system of FIG. It is a flowchart explaining a part operation of the control device in the breeding water purification system of FIG. It is a figure explaining the behavior in water of a bubble and a fine bubble by aeration. It is a characteristic diagram which shows the relationship between the bubble diameter of a microbubble and the rising speed. It is a characteristic diagram showing the transition of the dissolved oxygen concentration of the breeding water when the bubble is introduced by aeration in the breeding aquarium where the breeding body is densely packed. It is a characteristic diagram showing the transition of the dissolved oxygen concentration of the breeding water when the air fine bubble is introduced into the breeding aquarium where the breeding body is densely packed. It is a characteristic diagram which shows the transition of the dissolved oxygen concentration of the breeding water at the time of feeding in the breeding aquarium where the breeding body is dense. It is a characteristic diagram which shows the measurement result of the existing oxygen concentration of Example, Comparative Example 1 and Comparative Example 2. It is a block diagram which shows the structure of the evaluation apparatus roughly. It is a characteristic diagram which shows the measurement result of the relationship between the water flow rate and water pressure generated by each nozzle. It is a characteristic diagram which shows the result of having measured about the number of bubbles of the generated fine bubbles. It is a characteristic diagram which shows the result of having measured the dissolved oxygen amount which rises with the passage of time. It is a characteristic diagram which shows the measurement result of the relationship between the bubble diameter generated when the oxygen flow rate is changed, and the number of bubbles. It is a perspective view which shows roughly the structure of the experimental apparatus which performs the performance comparison by the difference of the nozzle of the foam separating apparatus. It is a characteristic diagram which shows the experimental result of the bubble diameter and the number of bubbles by the difference of a nozzle. It is a photograph figure of the test aeration tank for confirming the behavior of the bubble after passing through the aeration tank. It is a photographic view which shows the filter medium filled in the test aeration tank of FIG.

FIG. 1 schematically shows the configuration in one embodiment of the breeding water purification system of the present invention, FIG. 2 schematically shows the configuration of the fine bubble generator of FIG. 1, and FIG. 3 shows FIG. The configuration of the foam separator is shown schematically.

As shown in FIG. 1, the breeding water purification system of the present embodiment has a breeding water tank 10 in which the breeding water 10a is housed and a denitrification tank 12 connected to the breeding water tank 10 via a flow path and a circulation pump 11. And the vitrification tank 14 connected to the breeding water tank 10 via the flow path and the circulation pump 13, further connected to the denitrification tank 12 via the flow path, and further connected to the vitrification tank 14 via the flow path, and further reared. An aeration device 15 connected to the water tank 10 via a flow path, a fine bubble generator 17 connected to the breeding water tank 10 via a flow path and a circulation pump 16, and a fine bubble generator 17 via a flow path. A foam separation device 18 connected to the aeration device 15 via a flow path, a dissolved oxygen meter (DO meter) 19 for detecting the dissolved oxygen concentration of the breeding water in the breeding water tank 10, and a fine bubble generator 17 And a control device 20 electrically connected to the dissolved oxygen meter 19.

The denitrification tank 12 is filled with particles carrying denitrifying bacteria, and the denitrification reaction treatment of the breeding water 10a is performed by utilizing the particle flow in an anaerobic atmosphere. By the action of denitrifying bacteria, nitrite ions and nitrate ions in the breeding water are converted to nitrogen, and circulation with the breeding water tank is repeated until the concentration of harmful substances is reduced to less than the upper limit. By using particle flow, the reaction rate is about twice as high as in the case of a standard system, so it is possible to reduce the required power and required area. Further, stable denitrification efficiency can be obtained, and cleaning becomes unnecessary. In the denitrification tank 12, the dissolved oxygen concentration in the breeding water needs to be an oxygen-deficient condition of about 0.5 to 1.0 ppm or less, and this oxygen concentration is determined by blowing air from an aeration nozzle (not shown) provided in the aeration device 15. It can be adjusted by the amount.

The smaller the particle size of the denitrifying bacteria-carrying particles, the larger the contact area between the particles and the breeding water 10a and the higher the reaction rate. Therefore, it is desirable that the particle size is small. Since there is a risk of outflow and clogging of the flow path, it is appropriate that the diameter is 2 mm or more and 8 mm or less. Further, since the specific gravity of the breeding water 10a is 1.00 g / cm ³ or more and 1.05 g / cm ³ or less, if the density of the particles is smaller than this, it floats on the water surface and the contact area with the breeding water 10a decreases, and vice versa. On the other hand, if the density is higher than this, it sinks to the bottom surface and the contact area with the breeding water 10a decreases. Therefore, it is appropriate that the density of the particles is 1.00 g / cm ³ or more and 1.05 g / cm ^{3 or less.} Further, when the particles are simple spherical particles, the carried bacteria may be exfoliated due to the flow of the particles, so that it is desirable to provide a hole penetrating to the center of the particles. If the diameter of this hole is too small, the breeding water 10a does not permeate inside due to surface tension, and conversely, if it is too large, the carried bacteria may be exfoliated. Therefore, a diameter of 5 μm or more and 40 μm or less is appropriate. Any particles that satisfy these conditions may be used, but it is preferable to use ceramics, plastics, resins, etc. that have a good affinity for bacteria.

The denitrification tank 12 is provided with a stirring blade and a stirring motor (not shown) for promoting the reaction and degassing. The higher the rotation speed of the stirring motor, the higher the efficiency of reaction and degassing, but the required power increases as the rotation speed increases, so it is desirable that the rotation speed is 10 to 120 rpm. When the stirring motor is not used, a water flow may be generated by using a submersible pump or the like to stir. Further, since carbon is required for the denitrification reaction, the denitrification tank 12 is provided with a carbon source supply device (not shown). The carbon source may be any one containing carbon, but since the bacterium takes up carbon into the cell, it is desirable that the carbon source is water-soluble. As the carbon source, it is desirable to use such a compound having one carbon element because most of the bacteria can decompose only a compound having one carbon element (for example, methane or methanol). Methanol may be used as the water-soluble carbon source. As the solid carbon source, it is desirable to use a biodegradable plastic such as polyhydroxybutyrate. It is desirable that the supply rate of these liquid carbon sources is equal to the consumption rate by the bacteria, but if the carbon source remains in the breeding water exceeding the consumption rate by the bacteria, it will be sent to the aeration device. There is no problem because it is disassembled and made harmless. In the case of a solid carbon source, the carbon source is consumed as much as the bacteria consume, that is, since the carbon source does not diffuse into the breeding water, there is an effect that it is easy to grasp the consumption state of the solid content. In addition, since the required amount of bacteria can be supplied, the effect of not unnecessarily increasing the load of the aeration device can be obtained at the same time.

The nitrifying tank 14 is filled with nitrifying bacteria-supported particles, and in an aerobic atmosphere, the inflowed breeding water 10a is nitrified by utilizing the particle flow. Organic nitrogen and ammonia contained in the breeding water 10a are decomposed into nitrite ions and nitrate ions by the action of nitrifying bacteria, but the nitrification reaction rate increases 3 to 4 times by using particle flow, so it is standard. If the same nitrification efficiency as the standard system is aimed at, the treatment amount of the breeding water 10a, that is, the storage capacity of the nitrification tank 14, can be reduced from one half to one third of the standard system. The required area of the nitrification tank 14 can be reduced. Further, since the fluidized nitrifying bacteria-supported particle-filled layer has less resistance during liquid passage than the normal packed bed, the required power can be reduced. Further, it is difficult for the residue to adhere to the fluidized packed bed, and even if it adheres, it is immediately peeled off, so that the filter medium is not clogged. Therefore, stable nitrification efficiency can be obtained, and cleaning becomes unnecessary.

As for the particles carrying nitrifying bacteria, the smaller the particle size, the larger the contact area between the particles and the breeding water 10a and the higher the reaction rate. Therefore, it is desirable that the particle size is small. Since there is a risk of outflow and clogging of the flow path, it is appropriate that the diameter is 2 mm or more and 8 mm or less. Further, since the specific gravity of the breeding water 10a is 1.00 g / cm ³ or more and 1.05 g / cm ³ or less, if the density of the particles is smaller than this, the water surface rises and the contact area with the breeding water 10a decreases. On the contrary, if the density is higher than this, it sinks to the bottom surface and the contact area with the breeding water 10a decreases. Therefore, it is appropriate that the density of the particles is 1.00 g / cm ³ or more and 1.05 g / cm ^{3 or less.} Further, when the particles are simple spherical particles, the carried bacteria may be exfoliated due to the flow of the particles, so that it is desirable to provide a hole penetrating to the center of the particles. If the diameter of this hole is too small, the breeding water 10a does not permeate inside due to surface tension, and conversely, if it is too large, the carried bacteria may be exfoliated. Therefore, a diameter of 5 μm or more and 40 μm or less is appropriate. Any particles that satisfy these conditions may be used, but it is preferable to use ceramics, plastics, resins, etc. that have a good affinity for bacteria.

The aeration device 15 performs an aeration treatment for purifying the breeding water 10a. It has a function of filtering and decomposing large solids such as residual food, scales, feces, and slimy proteins from fish bodies in the breeding water 10a. That is, there is a function of supplying oxygen into the breeding water 10a sent from the nitrification tank 14 and the foam separating device 18 by blowing air from an aeration nozzle (not shown) to supplement the oxygen consumed by the breeding body. Further, as the solid content passes through the foam separation device 18 including the fine bubble generating nozzle, the solid content having a large size due to the shearing force becomes a finer size and has an effect of assisting decomposition by aerobic bacteria in the aeration device 15. .. In the case of the pre-shipment stage where the size of the fish becomes large at the time of breeding, or in the case of breeding at a higher density, the aeration device 15 is provided with a discharge valve (not shown), and after discharging the water containing the solid content of the aeration device, A function for separating solids may be provided in a settling filter tank.

The fine bubble generator 17 has a swirling flow type fine bubble generating nozzle 17a, and is configured to generate fine bubbles in the breeding water 10a. That is, as shown in FIG. 2, the fine bubble generator 17 is a flow rate adjusting valve 17c (the present invention) connected to the fine bubble generating nozzle 17a and the gas supply port 17b of the fine bubble generating nozzle 17a via a flow path. (Corresponding to the flow rate adjusting mechanism), the electromagnetic switching valve 17d (corresponding to the switching mechanism of the present invention) in which the output port is connected to the flow rate adjusting valve 17c, and the flow path and the flow path to one of the input ports of the electromagnetic switching valve 17d. It is provided with an oxygen cylinder 17f connected via a pressure reducing valve 17e. The other input port of the electromagnetic switching valve 17d is an air supply port. The electromagnetic switching valve 17d is electrically connected to the control device 20 of FIG. 1, and which input port is communicated with the output port is controlled by a control signal from the control device 20. The input port 17g of the fine bubble generation nozzle 17a is connected to the breeding water tank 10 via the flow path and the circulation pump 16, and the output port 17h is connected to the foam separation device 18 via the flow path.

The fine bubble generation nozzle 17a is a fine bubble generation nozzle by a swirling flow method that can efficiently generate a large amount of fine bubbles in a short time by supplying gas to a portion of an orifice that exhibits an aspirator function. A single swirl flow type in-line bubble generation nozzle (model number: FBS-15AI) manufactured by Sakamoto Giken is used. The bubble generation nozzle (model number: FBS-15AI) has a liquid discharge flow rate of 20 to 30 L / min and a gas flow rate of 0 to 5 L / min. Since it is an in-line type, it can be attached to existing pipes, easily incorporated into equipment, and easy to disassemble and clean, so it is excellent in maintainability. In addition, since there are no moving parts, it is resistant to foreign matter and has a long life. Of course, as the fine bubble generation nozzle 17a, another bubble generation nozzle of the swirling flow type may be used.

As shown in FIG. 3, the foam separation device 18 includes a foam separation tower 18a, a foam separation unit 18b connected above the foam separation tower 18a, and a suspended suspended substance (SS) separated by the foam separation unit 18b. ), The fine bubbles supplied from the fine bubble generator 17 via the flow path 18d, and the breeding water are first input, and the direction is changed to eject the fine bubbles into the foam separation tower 18a for stirring. The sub-chamber 18e and the flow path 18f for outputting the breeding water in the foam separation tower 18a to the aeration device 15 are provided. The foam separator 18 utilizes the property of adsorbing and concentrating pollutants on the interface between gas and liquid to adsorb and concentrate the pollutants on the bubbles supplied to the breeding water, and removes the bubbles to remove the pollutants in the breeding water. It removes the SS of.

The foam separation device 18 of the present embodiment is provided with a sub-chamber 18e for stirring to increase the flow distance of the fine bubbles and the breeding water inside and to change the flow direction of the fine bubbles and the breeding water. The residence time in the foam separation tower 18a can be increased to maximize the amount of floating bubbles. In addition, when a large amount of microorganisms or bacteria that are the source of stains are generated, the viscosity of water increases, so that the amount of bubbles that float increases, and conversely, when the amount of stains is small, the viscosity of water decreases. Reduces the amount of bubbles. As a result, the amount of wastewater for removing dirt was extremely reduced.

The control device 20 includes a programmable microcomputer, and switches and controls the electromagnetic switching valve 17d according to the dissolved oxygen concentration detected by the dissolved oxygen meter 19 to supply air or oxygen to the fine bubble generation nozzle 17a. It is configured in. FIG. 4 describes a partial operation of the control device 20. If it is determined in step S1 that the dissolved oxygen concentration detected by the dissolved oxygen meter 19 is 125% or more, the process proceeds to step S2, and the output port of the electromagnetic switching valve 17d is set to the other input port side, that is, the air supply port side. Connect to. On the other hand, if it is determined in step S1 that the dissolved oxygen concentration detected by the dissolved oxygen meter 19 is less than 125%, the process proceeds to step S3, and the output port of the electromagnetic switching valve 17d is set to one input port side, that is, the oxygen cylinder. Connect to the 17f side. As a result, when the dissolved oxygen concentration of the breeding water 10a is 125% or more, air is supplied to the fine bubble generating nozzle 17a, and when the dissolved oxygen concentration is less than 125%, oxygen is supplied to the fine bubble generating nozzle 17a. Will be.

The control device 20 further manually or automatically adjusts the flow rate adjusting valve 17c of the fine bubble generator 17 according to the density and weight of the breeding body, which is a farmed fish, and gas (air) to the fine bubble generating nozzle 17a. Or the supply amount of oxygen) can be adjusted. When the flow rate adjusting valve 17c is automatically adjusted, a control signal is sent from the control device 20 to the flow rate adjusting valve 17c, and when the density of the breeding body is low, the amount of gas supplied is reduced to the oxygen breeding water. When the amount of dissolved gas is reduced, the density of the breeding body becomes high, and the breeding water becomes dirty with the excrement of the breeding body, the bubble diameter of the bubble is increased by increasing the gas supply amount, and the bubble for foam separation is increased. To remove dirt in the water. As a result, it becomes possible to efficiently dissolve oxygen in breeding water at low cost. The control device 20 also controls the electromagnetic switching valve 17d of the fine bubble generator 17 to change the supply gas from air to oxygen when the weight of the breeding body has increased, so that the control device 20 is fine with a small amount of oxygen. By introducing foam into the breeding water and further increasing the efficiency of oxygen dissolution, it is possible to cope with the weight gain of the breeding body. Further, when the breeding water becomes extremely dirty, the flow rate adjusting valve 17c of the fine bubble generator 17 is manually or automatically adjusted to increase the supply amount of air or oxygen to increase the bubble diameter and separate bubbles. It is possible to carry out an operation that enhances the effect of the device 18. As a result, the oxygen concentration and cleanliness of the breeding water are kept constant, and high-speed growth and high-density aquaculture of the breeding body are achieved. When the flow rate adjusting valve 17c is automatically adjusted, if the dissolved oxygen concentration detected by the dissolved oxygen meter 19 is small (for example, if it is less than the threshold value), it can be determined that the breeding water is heavily contaminated. A control signal is sent to the flow rate adjusting valve 17c to increase the supply amount of air or oxygen, increase the bubble diameter, and increase the bubbles for foam separation to remove water stains. When the dissolved oxygen concentration detected by the dissolved oxygen meter 19 is large (for example, when it is equal to or higher than the threshold value), the reverse control is performed. Further, the control device 20 is based on data peculiar to each fish such as the Do value of the dissolved oxygen meter 19, the measured value of the pH meter (not shown), the measured value of the electric conductivity meter (measurement of turbidity degree), and the feeding time. It is also possible to predict the required oxygen amount in the breeding water 10 and control the solenoid valve 17d of the fine bubble generator 17 while performing the prediction calculation.

In the fine bubble generator 17 of the present embodiment, bubbles called microbubbles having a bubble diameter of 1 to 100 μm (average bubble diameter of about 10 μm when the bubble diameter distribution is measured) and ultrafine bubbles having a bubble diameter of less than 1 μm are usually used. Fine bubbles including bubbles (when the bubble diameter distribution is measured, the average bubble diameter is about 0.1 μm) are generated. Microbubbles, which are normal bubbles, rise in the water, burst at the surface of the water, and disappear. In addition, the microbubbles are tinged with negative ions, and have the effect of binding to dirt, which is positive ions, and floating up to raise the dirt to the surface of the water. However, unlike ordinary bubbles, ultrafine bubbles having a bubble diameter of less than 1 μm have the property of shrinking and disappearing (crushing) in water, and when they disappear, the gas dissolves in the water. In this way, the ultrafine bubble can efficiently dissolve the gas in water.

As shown in FIG. 1, by installing the fine bubble generator 17 on the upstream side of the foam separation device 18, the dirt component in the breeding water 10a is bubbled to the foam separation portion 18b by the microbubbles having a bubble diameter of 1 to 100 μm. Ultrafine bubbles with a bubble diameter of less than 1 μm generated in the water pass through without being captured by the aeration tank on the downstream side, and return to the water tank 10 to return to the oxygen in the breeding water 10a. Can contribute to supply.

In the prior art, in a foam separator, oxygen or air is pressurized by a pump, passed through a mesh such as a sintered filter, and bubbled into water to generate bubbles. According to such a conventional method, the bubble diameter (size) of the bubble is as large as μm to mm, and the rising speed is also high, so that the bubble comes out of the water to the surface of the water in a very short time and goes into the water. There was a problem that the dissolution efficiency of the gas was low. In other words, when bubbles are generated by normal aeration, the size of most bubbles is about μm to mm, and most of the bubbles are used only for the function of adhering dust to the bubbles and separating them when they rise from the water to the surface of the water. It had been destroyed.

On the other hand, in the present embodiment, the fine bubble generator 17 has a fine bubble generating nozzle by a swirling flow method capable of efficiently generating a large amount of fine bubbles in a short time by supplying gas to a portion of the orifice that exhibits an aspirator function. Since the bubbles are generated by the bubble, both microbubbles (average bubble diameter of about 10 μm) and ultrafine bubbles (average bubble diameter of about 0.1 μm) are generated. Microbubbles and ultrafine bubbles behave differently in water. That is, microbubbles are used to separate underwater dust by enclosing water dust in bubbles and floating on the surface of the water, and ultrafine bubbles cause the bubble to shrink in water and the bubble diameter shrinks, eventually reducing the bubble diameter. The gas in the bubble shifts to one of the behaviors of dissolving in water. In particular, the efficiency of gas dissolution in water is generally indicated by the relationship between the temperature of water, the partial pressure of gas in the gas phase, and the concentration of gas dissolved in water. At the same time as the bubble is generated, it causes a dissolution behavior in water and dissolves in water one after another.

FIG. 5 explains the behavior of bubbles and fine bubbles due to aeration in water, and as shown in the figure, it can be seen that there are bubbles that dissolve immediately in water and bubbles that float in water. When a certain amount of gas is dissolved in water, ultrafine bubbles show shrinkage behavior in water, and show behavior of floating in water while shrinking the bubble diameter. Locally, the gas in the bubble behaves to dissolve when the dissolved oxygen in the water is consumed by an organism (such as aquaculture fish or microorganisms that require oxygen).

By attaching such a fine bubble generating nozzle 17a to the fine bubble generating device 17 and operating it and utilizing the difference in bubble function due to the difference in bubble diameter, the operation control of the foam separating device 18 according to the state of the breeding water can be controlled. This can be done so that the circulating breeding water can be maintained in optimum condition. By keeping the circulating breeding water in the optimum condition at all times, high-speed growth and high-density aquaculture of the breeding body become possible.

FIG. 6 shows the relationship between the bubble diameter of the microbubbles and the rising speed, where the horizontal axis is the bubble diameter (μm) and the vertical axis is the rising speed (μm / sec). The broken line represents the relationship between the particle diameter D _p which is based on the Stokes equation _(cell diameter) and terminal velocity v _{s (rising} speed), ■ is the measured value of the rising speed and the cell diameter. For example, if the bubble diameter is 30 μm, the rising speed is 400 μm / sec, but as the bubble diameter increases, the rising speed increases by the square of the bubble diameter.

According to the ultrafine bubble as described above, since the area of the gas-liquid interface becomes overwhelmingly large in the same amount of gas, it becomes possible to efficiently dissolve the gas in water. By increasing the amount of dissolved oxygen in the water, the breeding density of the breeding body can be increased, and at the same time, the aerobic microorganisms can efficiently take in oxygen, so that the aerobic microorganisms in the breeding water can be activated. can.

However, if the breeding body is small, for example, a larva weighing about 150 g or a larva that has just hatched from an egg, the ultrafine bubbles floating in the breeding tank are affected by the energy of the bubble popping while adhering to the gill tissue. , "Egg burn" occurred and the breeding body died, or bubbles adhered to the scales of the breeding body (for example, Iwashi) and "the phenomenon that the scales opened" occurred. In addition, in the breeding aquarium, aerobic microorganisms and breeding organisms may be damaged by the shock wave when the ultrafine bubble is crushed, causing a problem of death.

On the other hand, according to the present embodiment, it is possible to adjust the flow rate adjusting valve 17c of the fine bubble generator 17 to adjust the supply amount of gas (air or oxygen) according to the body weight of the breeding body. Therefore, when the weight of the breeding body is small, it is possible to introduce fine bubbles into the breeding water with a small amount of oxygen to prevent the occurrence of "grill burning" and "the phenomenon that the scales open".

Next, the effect of introducing fine bubbles into the breeding water will be described with actual examples. FIG. 7a shows the transition of the dissolved oxygen concentration of the breeding water when a bubble is introduced by aeration by the conventional technique into the breeding water tank in which the breeding body (campachi) is densely packed, and FIG. 7b shows the transition of the dissolved oxygen concentration of the breeding body (campachi). Shows the transition of the dissolved oxygen concentration in the breeding water when an air fine bubble is introduced into the breeding water tank where the breeding bodies (campachi) are densely packed. It shows the transition of the dissolved oxygen concentration in the breeding water at that time. In each figure, the horizontal axis is time (min) and the vertical axis is the dissolved oxygen concentration (mg / L).

From FIGS. 7a and 7b, fine bubbles produce high oxygen dissolution efficiency when dissolving oxygen in water, so in a breeding aquarium where dissolved oxygen is depleted, conventional aeration is applied to overcrowded fish schools. In comparison, it can be seen that the dissolved oxygen concentration is dramatically improved. In addition, from FIG. 7c, when the dissolved oxygen in the breeding aquarium decreases while feeding the breeding body (during active activity of the breeding body), the behavior of the breeding body is such that a slight oxygen deficiency occurs or prey. However, it can be seen that the situation is dramatically improved by introducing fine bubbles in such cases.

[Basic evaluation of bubble generation due to differences in fine bubble generation nozzles]
Examples and comparative examples of the breeding water purification system of the present invention will be described below. When normal water is stored in a 1-ton water tank manufactured by Japan Marine Ponics Co., Ltd. and no bubbles are introduced (Comparative Example 1), when oxygen bubbles are introduced by aeration using an air diffuser for an aquarium (comparison). Example 2) Measure the time transition of the dissolved oxygen concentration in water when oxygen fine bubbles are introduced using a single swirl flow type in-line bubble generation nozzle (FBS-15AI) manufactured by Sakamoto Giken Co., Ltd. (Example). did. The amount of gas (oxygen) introduced was 0.5 L / min.

FIG. 8 shows the measurement result of the dissolved oxygen concentration. The horizontal axis is time (min), and the vertical axis is the amount of dissolved oxygen (%). In the figure, a shows Example, b shows Comparative Example 1, and c shows Comparative Example 2. In Comparative Example 2 in which the bubble was not introduced, the dissolved oxygen amount hardly changed or slightly decreased with the passage of time. In Comparative Example 2 in which an oxygen bubble by aeration was introduced, it took about 50 minutes to raise the dissolved oxygen amount to 110%. When oxygen was not consumed in the absence of the breeding body in the breeding water, the dissolved oxygen amount was saturated at about 110% and became constant. On the other hand, in the example in which the oxygen fine bubble was introduced using the swirling flow type bubble generation nozzle (FBS-15AI), the dissolved oxygen amount could be increased to 110% in about 5 minutes, and the dissolved oxygen amount could be increased. Further increased to 130%.

Next, in order to select the optimum fine bubble generating nozzle, the amount of fine bubble water, the number of bubbles, and the amount of dissolved oxygen were evaluated for some nozzles. The evaluation device shown in FIG. 9 was used for this evaluation. In the figure, 90 is a water tank, 91 is a shielding plate provided in the water tank 90, 92 is a dissolved oxygen meter (DO meter) for detecting the oxygen concentration of the water 90a in the water tank 90, and 93 is the water 90a in the water tank 90. In the stirrer, 94 indicates a pump for sending water 90a in the water tank 90, 95 indicates a flow meter, 96 indicates a pressure gauge, and 97 indicates a fine bubble generation nozzle to be evaluated. The fine bubble generation nozzle 97 is configured to introduce a gas for bubbles.

The performance of each of the three different fine bubble generating nozzles was measured using the above-mentioned evaluation device while maintaining the same gas flow rate and pump performance (power consumption). The three nozzles used are A is a single swirl flow type in-line bubble generation nozzle (model number: FBS-15AI) manufactured by Sakamoto Giken Co., Ltd., and B is a loop flow type manufactured by OK Engineering Co., Ltd. with a smaller amount of bubble generation. The OK nozzle (model number: OKE-MB07) and C were ejector-type fine bubble generation nozzles (model number: TH-05) manufactured by Daisei Kogyo Co., Ltd.

FIG. 10a shows the measurement result of the relationship between the water flow rate generated by each nozzle and the water pressure, the horizontal axis is the water flow rate (L / min), and the vertical axis is the water pressure (MPa). FIG. 10b shows the results of measuring the number of fine bubbles (microsize) generated while maintaining the same pump performance (power consumption) and oxygen supply amount. The horizontal axis is the bubble diameter (μm), and the vertical axis is the vertical axis. The number of bubbles (pieces / mL). FIG. 10c shows the results of measuring the amount of dissolved oxygen that increases with the passage of time while maintaining the same pump performance (power consumption) and oxygen supply amount. The horizontal axis is time (min), and the vertical axis is the amount of molten oxygen ( %).

From these measurement results, A's single swirl flow type in-line bubble generation nozzle (model number: FBS-15AI) manufactured by Sakamoto Giken Co., Ltd. has a water volume, number of bubbles, and final compared to other bubble generation nozzles. It was found to have high performance in terms of dissolved oxygen concentration.

Next, it was investigated how much the oxygen flow rate supplied to the fine bubble generation nozzle was appropriate. Using the evaluation device shown in FIG. 8, the bubble diameter and the number of bubbles generated by changing the oxygen flow rate supplied to the single swirl flow type in-line bubble generation nozzle (model number: FBS-15AI) manufactured by Sakamoto Giken Co., Ltd. The relationship was measured.

FIG. 11 shows the measurement results of the relationship between the bubble diameter generated when the oxygen flow rate is changed and the number of bubbles, the horizontal axis is the bubble diameter (μm), and the vertical axis is the number of bubbles (pieces / mL). The oxygen flow rate was 0.25 L / min, 0.5 L / min, and 1.0 L / min. In the single swirl flow type in-line bubble generation nozzle (model number: FBS-15AI) manufactured by Sakamoto Giken Co., Ltd., the number of bubbles with a small diameter tended to increase as the gas supply amount was reduced. The larger the number of fine bubbles, the stronger the ability to keep the dissolved oxygen high, but if the amount of introduced gas is too small, the volume of the gas itself becomes small and the time required for a simple increase in dissolved oxygen increases. .. From these balances, it was determined that a gas supply amount of 0.5 L / min was appropriate.

[Measurement of bubble diameter and number of bubbles due to difference in fine bubble generation nozzle]
FIG. 12 schematically shows the configuration of an experimental device for comparing the performance by different nozzles of the foam separation device, and the amount of microbubbles and the bubble diameter were measured using this experimental device. In the figure, 100 is a water tank, 116 is a circulation pump, 117 is a nozzle provided downstream of the circulation pump, and 118 is a foam separation device.

The experiment was carried out at room temperature and water temperature of 25 ° C., the amount of water in the foam separator 118 was about 45 L, the amount of water in the water tank 100 was 150 L, and 195 L of water was measured in a circulating state by a circulation pump 116 (flow rate of 110 L / min). .. The foam separation device 118 was used by sucking gas from a nozzle 117 in the inflow portion downstream of the circulation pump 116 to generate bubbles. Therefore, a conventional ejector nozzle made by narrowing the flow path as a nozzle 117 and a fine bubble generating nozzle (model number: FB-M40A) manufactured by Sakamoto Giken Co., Ltd. are used, and the generated bubbles differ depending on the nozzle. A comparison was made. The water used for measuring the microbubbles was tap water, and the measurement position of the bubbles was near the discharge port at the upper part of the foam separator 118 (notation of MB measurement). The amount and diameter of microbubbles (bubbles having a diameter of 1 μm or more) were measured by capturing a sample with a full-frame camera using a microtrack (model number: PART AN SI) manufactured by Microtrack Bell Co., Ltd. and measuring the particle diameter by image analysis. 2 L / min of water is supplied to the measuring instrument from the notation position of "MB measurement" in FIG. 12, and the amount of microbubbles is used by using the calibration curve using the microbubble image in the water acquired in advance. And the bubble diameter were quantified. The gas flow rate introduced into the foam separator 118 was changed to 2 L / min, 5 L / min, and 10 L / min. The experimental results are shown in FIG.

From FIG. 13, it was found that the diameter of the microbubbles in the foam separator 118 tended to be as large as 10 μm to 50 μm in any of the nozzles. In addition, the amount of microbubbles tended to increase as the gas flow rate increased in the aspirator type nozzle, but in the fine bubble nozzle, the amount of microbubbles tended to increase as the flow rate was smaller.

When oxygen is used, the smaller the amount of gas introduced, the lower the cost. Therefore, paying attention to the comparison at 2 L / min, the fine bubble nozzle is more efficient in foam separation than the aspirator nozzle. It was confirmed that the number of bubbles was about 2 to 2.5 times with a bubble diameter of 40 μm. That is, it was found that high foam separation performance can be obtained with a small amount of gas.

[Checking the behavior of microbubbles and ultrafine bubbles after passing through the aeration tank]
The behavior of the microbubbles and ultrafine bubbles generated by the foam separator 118 when they passed through the aeration tank was confirmed. That is, as shown in the photograph of FIG. 14, a straw-shaped filter medium as shown in the photograph of FIG. 15 (sold by Marine Theater Co., Ltd., diameter 7 to 12 mm × height 7 mm) is placed in a test aeration tank having a diameter of 425 m and a height of 500 m. Was filled in 500 mm, and the number of microbubbles and ultrafine bubbles in water that passed through the filling cylinder at 800 cc / min: SV = 2600 (1 / hr) was measured.

The measurement of microbubbles is quantified by the above-mentioned microtrack (model number: PART AN SI) manufactured by Microtrack Bell Co., Ltd., and for ultrafine bubbles, the zeta potential, particle size distribution, and number of particles manufactured by Microtrack Bell Co., Ltd. Measurement was performed by the Particle Tracking Analysis (PTA) method using a counting device ZetaView. This is a method of capturing the scattered light from the particles with a camera, irradiating the glass cell with laser light, and detecting the scattered light from the particles in the 90 ° direction with the camera. The scattered light of particles is observed as a shining point, and the diffusion coefficient and mobility are obtained from the movement of the scattered light. The measurement was carried out by the method of calculating the zeta potential from.

The measurement results are shown in Table 1. The number of bubbles shown in the table is the total number of bubbles with a diameter of 1 μm or more contained in the water after passing through the test aeration tank depending on whether the test aeration tank has a filling or no filling. be. As can be seen from the table, when there is a filling, the number of microbubbles, which was about 15,000 in 1 mL, is reduced to 64. In the absence of filling, the number was 410, and the total number of microbubbles was reduced to 1/7. This is because microbubbles adhere to the filling, and the phenomenon that the microbubbles are removed from the water after passing through the test aeration tank was observed. It was confirmed that among the fine bubbles generated by the foam separator, the microbubbles did not exist as bubbles after being used for separation and then passing through the test aeration tank.

On the other hand, for ultrafine bubbles (bubbles having a diameter of less than 1 μm), the number of bubbles before and after passing through the packed bed in the test aeration tank was measured. The measurement results are shown in Table 2. As it is shown in the same table, when through the ultra-pure water, was comparable with 10 ⁴ cells / mL before and after. Before and after some numbers, dust adhering to the filling was observed. The number of bubbles also increases a little when ultrafine bubble water is passed through the filler. It is also considered that this is also a measurement of dust in the filling washed with ultrafine bubble water. In other words, the number of ultrafine bubbles increases or decreases depending on the filling, but there is no significant effect. Even if the ultrafine bubbles pass through the test aeration tank, almost all of the bubbles return to the water tank and float in the water as ultrafine bubbles. Therefore, it was found that oxygen can be sufficiently supplied to the water even when the foam separation device is installed in front of the test aeration tank.

[Demonstration of foam separator in aquaculture equipment]
In a breeding pond with a water volume of 15 tons, Chairo Maruhata (classification: Perciformes Serranidae, Epinephelus, Origin: Taiwan), average weight: 1 kg, number of animals: 1200, period: October 2018-September 2019, It was bred under the condition of salt water concentration: 4%. The breeding water was replenished for evaporation but not replaced. Oxygen supply and removal of turbidity in water were carried out by a foam separator using fine bubbles. 110 L / min of breeding water was flowed in from the flow path 18d of the foam separation device 18 shown in FIG. 3, oxygen amount: 5 L / min, discharge amount from the drain pipe 18c: 300 cc / hr, discharge amount from the flow path 18f: The operation was carried out under the condition of about 5 L / min, and the oxygen concentration of 120% (26 ° C.) was controlled by the oxygen concentration meter 19 in the culture pond. As a result, the turbidity in the breeding water was dramatically reduced visually, and the state where the fish shadow was not visible before operation became transparent so that the fish shadow could be completely confirmed, and the oxygen concentration could be kept constant. .. We were able to simultaneously resolve the removal of turbidity in the breeding water and the supply of oxygen.

All of the above-described embodiments are illustrative and not limited to the present invention, and the present invention can be carried out in various other modifications and modifications. Therefore, the scope of the present invention is defined only by the scope of claims and the equivalent scope thereof.

10 Breeding water tank 10a Breeding water 11, 13, 16, 116 Circulation pump 12 Denitrification tank 14 Nitrification tank 15 Aeration device 17 Fine bubble generator 17a Fine bubble generator 17a Gas supply port 17c Flow control valve 17d Electromagnetic switching valve 17e Pressure reducing valve 1
17f Oxygen bomb 17g Input port 17h Output port 18, 118 Foam separation device 18a Foam separation tower 18b Foam separation part 18c Drain pipe 18d, 18f Channel 18e Sub-chamber 19 Dissolved oxygen meter 20 Control device 117 Nozzle

Claims (9)

It is a closed circulation type breeding water purification system for high-density aquaculture, which is connected to the breeding water tank and is filled with denitrifying bacteria-carrying particles inside, and performs denitrification reaction treatment of the breeding water from the breeding water tank. A denitrification tank, a nitrification tank connected to the denitrification tank and the breeding water tank and filled with nitrifying bacteria-bearing particles, and performing a nitrification treatment of the inflowed breeding water, and the nitrification tank and the breeding tank. A swirling flow type fine bubble that supplies gas to the aeration device that is connected to the water tank and performs aeration treatment of the breeding water and the part of the orifice that is connected to the breeding water tank and exhibits an aspirator function to generate fine bubbles. It has a generation nozzle and is connected to the fine bubble generator that generates fine bubbles in the breeding water, the fine bubble generator and the aeration device, and at least a part of the fine bubbles in the breeding water. A breeding water purification system characterized by being equipped with a foam separation device for separation and removal. The breeding water purification system according to claim 1, wherein the fine bubble generator is configured to selectively generate air fine bubbles and oxygen fine bubbles. Further, a dissolved oxygen meter for detecting the dissolved oxygen concentration in the breeding water is further provided, and when the dissolved oxygen concentration detected by the fine bubble generator is equal to or higher than a predetermined value, an air fine bubble is generated. The breeding water purification system according to claim 2, wherein when the detected dissolved oxygen concentration is less than a predetermined value, oxygen fine bubbles are generated. The fine bubble generator has a bubble diameter of 50 μm to 200 μm, and either oxygen or air is connected to the fine bubble generating nozzle that generates fine bubbles that do not dissolve in the breeding water and the gas supply port of the fine bubble generating nozzle. The breeding water purification system according to any one of claims 1 to 3, further comprising a switching mechanism for selectively supplying. The breeding water purification system according to any one of claims 1 to 4, wherein the fine bubble generator includes a flow rate adjusting mechanism capable of adjusting a gas supply amount. The breeding according to any one of claims 1 to 5, wherein the fine bubble generator is configured so that the bubble diameter of the fine bubble can be adjusted according to the density and / or the body weight of the breeding body. Water purification system. The breeding according to any one of claims 1 to 6, wherein the fine bubble generator is configured to generate 500 or more fine bubbles having a bubble diameter of 1 μm to 500 μm. Water purification system. Any one of claims 1 to 7, wherein the foam separating device is configured to discharge and remove the fine bubbles that have floated by adsorbing pollutants in the breeding water on the surface. Breeding water purification system described in. The foam separating device is characterized by including a sub-chamber configured to increase the flow distance of the fine bubbles supplied from the fine bubble generator and to rotate the flow direction of the fine bubbles. The breeding water purification system according to claim 8.

Images