JP2007105010A - Live fish survival rate-improving apparatus and live fish survival rate-improving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a live fish survival rate-improving apparatus which can efficiently enhance a dissolved oxygen concentration of a growth environment and does not affect the bodies of the live fishes; and to provide a live fish survival rate-improving method. <P>SOLUTION: This live fish survival rate-improving apparatus 1 comprises an aquarium 3 capable of receiving a liquid 2 in which live fishes can grow, and a fine gas bubble-releasing means 4 for supplying oxygen to sea water received in the aquarium 3 to enhance the concentration of dissolved oxygen. The fine gas bubble-releasing means 4 is set to the bottom portion of the aquarium 3 and releases fine gas bubbles 5 in the liquid 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention increases the dissolved oxygen concentration of the liquid contained in the aquarium for transporting, growing, and the like of live fish, uniformly and quickly diffuses oxygen into the aquarium, and raises the overall surface of live fish metabolites (waste products). The present invention relates to an apparatus and method for improving the survival rate of live fish that can be separated, and particularly relates to an apparatus and method for improving the survival rate of live fish that suppress coalescing of microbubbles by using seawater as a liquid stored in a water tank and a supply liquid.

  In the case of transporting fish and shellfish alive or growing as they are, the fish and shellfish can be kept fresh. For this purpose, live fish is placed inside a container containing live fish. In addition, sufficient oxygen must be dissolved in the liquid contained therein to maintain the dissolved oxygen amount at a certain level.

  As a means for increasing dissolved oxygen in water, a method of generating fine bubbles in water by introducing a bubble generator into the water in a live fish container and supplying air to the bubble generator with an air pump is well known. (For example, refer to Patent Document 1).

  Such microbubbles have a large specific surface area with respect to volume and a long residence time in water, so they are suitable for introducing oxygen into water to increase the amount of dissolved oxygen in water. Since it has absorptivity to suspended matter etc., it can float underwater etc. on the water and is preferable for use in the growth of live fish.

As a technique for generating microbubbles, there are a method of ejecting gas from micropores, a method of using shearing force, etc., and the former includes a method of blowing gas from a minute nozzle or a method of blowing gas from a porous plate, etc. The latter includes a method in which a gas on the surface of the liquid is engulfed by a jet or a method in which a gas is blown into a high-speed liquid flow.

  However, such microbubbles may be merged again when they are generated, and may be released as larger bubbles, resulting in a decrease in the generation efficiency of microbubbles, and the effect has been halved.

In order to solve this problem, a liquid introduction part that introduces a liquid, a gas introduction part that mixes a gas into the introduced liquid, and a microbubble generation part that generates a large number of microbubbles from the mixed gas are generated. And a liquid containing a surfactant, and suppressing the coalescence of a large number of microbubbles generated in the microbubble generating part by the action of the surfactant. There is known a microbubble generating device that discharges microbubbles (see, for example, Patent Document 2), but this suppresses coalescence of microbubbles by adding a surfactant to the liquid, and the microbubbles remain as they are. Is to maintain.
JP 2003-333957 A Japanese Patent Laid-Open No. 2003-230824

  However, in the invention described in Patent Document 1, since bubbles immediately rise from the air pump, the effect of improving the dissolved oxygen concentration cannot be sufficiently obtained. In addition, the invention described in Patent Document 2 requires the addition of a surfactant. Although it is a component, when this is used during the growth of live fish, the impact on the live fish must be considered, especially artificial surfactants may affect the live fish There is also a report that it must be used with caution. For example, nonylphenol ethoxide, which is one of the surfactants, functions as an environmental hormone and is considered to be a causative substance of rainbow trout testis reduction. It is not preferable.

  Therefore, the present invention can efficiently increase the dissolved oxygen concentration in the growth environment by performing release into the growth environment without uniting the generated microbubbles, and can perform uniform and rapid diffusion of oxygen, An object of the present invention is to provide a live fish survival rate improvement device and a live fish survival rate improvement method capable of performing overall rapid floating separation of live fish metabolites (waste products) without affecting the live fish body. To do.

  The apparatus for improving the survival rate of live fish according to the present invention comprises a water tank that contains a liquid in which live fish can grow, and a micro-bubble releasing means that supplies oxygen into the liquid contained in the water tank to increase the dissolved oxygen concentration. An apparatus for improving the survival rate of live fish, wherein the microbubble releasing means includes a liquid introduction part for introducing a supply liquid, a gas introduction part for mixing gas into the introduced supply liquid, and a gas mixed in the supply liquid. It has a micro-bubble generating part that generates a large number of micro-bubbles, and a discharge port that discharges the generated many micro-bubbles together with the supply liquid into the liquid stored in the water tank.

  The method for improving the survival rate of live fish according to the present invention is a method for improving the survival rate of live fish in which live fish can grow and oxygen is supplied to the liquid contained in the aquarium together with the live fish to increase the dissolved oxygen concentration. A gas introduction step for mixing gas into the supply liquid, a microbubble generation step for generating a large number of microbubbles from the gas mixed in the gas introduction step, and a liquid in which the generated microbubbles are contained in a water tank together with the supply liquid And a bubble releasing step for releasing the bubble into the inside.

  Although the configuration of the microbubble generating unit is not limited, in a preferred embodiment, the nozzle body having the microbubble generating unit includes a throttle unit that narrows the flow cross-sectional area and a divergent part that increases the flow cross-sectional area in the flow direction of the gas-liquid mixed fluid. And have. A large number of microbubbles are generated by generating a pressure wave by generating a pressure difference in the flow direction of the gas-liquid mixed fluid. More preferably, the microbubble generator has a conical shape, and a venturi type that expands in the flow direction of the gas-liquid mixed fluid can be used.

  Furthermore, from the viewpoint of energy saving, it is desirable that the opening angle of the microbubble generating part is narrow (the pressure of the liquid to be introduced can be reduced), the opening angle of the microbubble generating part is less than 40 degrees, , 30 degrees or less, or even 20 degrees or less. In an embodiment described later, the opening angle of the microbubble generator is 10 degrees or less, specifically 6 degrees. If the opening angle of the microbubble generation part is narrowed, the problem of coalescence of the generated microbubbles may occur. However, in the present invention, seawater is used as the supply liquid, or a liquid appropriately added with an agent that stably disperses the microbubbles is used. The problem was cleared.

  In addition, the gas introduction unit may be either a natural intake or a forced introduction of gas, and can be selected according to the implementation situation. Forcible introduction means that gas is not naturally sucked, and includes, for example, introduction of gas pressurized using a compressor. By forcibly introducing the gas, the gas-liquid ratio can be arbitrarily set or adjusted, or the gas ratio in the liquid can be increased. It is considered that the flow rate ratio between the liquid to be introduced and the gas can be increased up to, for example, about 20% by volume. It is also possible to control the diameter of the generated microbubbles by controlling the flow rate ratio.

  According to the apparatus and method for improving the survival rate of live fish of the present invention, it is possible to release a large number of microbubbles generated in the microbubble generating unit into the living environment of the live fish without uniting with a simple configuration. The dissolved oxygen concentration in the liquid can be increased efficiently.

  Microbubbles have a large specific surface area with respect to volume and a long residence time in water, so it is easy to dissolve oxygen contained in gas in a liquid, and they are electrically charged and have an adsorptivity to suspended matters in water. Therefore, suspended substances such as metabolites (waste products) of live fish in water can be rapidly surfaced on the water. Therefore, the present invention is suitable for adjusting the growth environment of live fish.

  The apparatus and method for improving the survival rate of live fish of the present invention can significantly improve the survival rate of live fish as a result by effectively exhibiting the above effects.

  The present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram showing a configuration of a live fish survival rate improving apparatus according to the present invention, and FIGS. 2A and 2B are schematic cross-sectional views each showing a configuration example of a microbubble releasing means used in the present invention. is there.

  First, a live fish survival rate improving apparatus 1 according to the present invention includes a water tank 3 that contains a liquid 2 in which live fish can grow, and microbubbles that increase the dissolved oxygen concentration by supplying oxygen into the liquid contained in the water tank 3. It consists of the discharge means 4. This micro-bubble releasing means 4 releases micro-bubbles 5 into the liquid 2 accommodated in the water tank 3 and improves the dissolved oxygen concentration in the liquid 2, and increases the contact time between the micro-bubbles and the liquid. In order to sufficiently dissolve oxygen in the microbubbles in the liquid 2, it is preferably installed at the bottom of the water tank 3, and more preferably configured to inject the microbubbles 5 in the horizontal direction.

  At this time, the injection of the microbubbles 5 is preferably performed at a gas injection ratio of 0.2 to 0.4 MPa with a gas ratio in the supply liquid of 10 to 20% by volume, whereby the liquid 2 in the water tank 3 is discharged. While stirring, a long contact time between the microbubbles 5 and the liquid 2 can be ensured, and oxygen can be efficiently dissolved in the liquid 2. The arrival distance of the fine bubbles differs depending on the injection pressure, and therefore it is possible to cope with a change in the size of the water tank by controlling the injection pressure in a timely manner.

  Although the aquarium 3 used in the present invention will be described, the aquarium 3 is not particularly limited as long as it can accommodate a liquid capable of growing live fish and can grow live fish. It is required to ensure a sufficient size.

  Here, the liquid 2 stored in the aquarium 3 can be used without particular limitation as long as live fish can grow, and examples thereof include tap water, seawater, river water, and lake water. These may be prepared by appropriately adding an emulsifier (such as glycerin fatty acid ester) used as a food additive for adjusting the growth environment, or an agent that stably disperses microbubbles such as sugars.

  The liquid 2 is preferably seawater, wherein the seawater is not only natural seawater but also artificial seawater in which the salt is dissolved in water to make it the same or similar to the seawater, In which can be grown. More preferable seawater includes a salt concentration of 3 to 4% by weight.

  Further, the microbubble releasing means 4 used in the present invention is a gas in which gas is introduced into the supply liquid by forcible introduction from a gas introducing unit, although not shown, such as the microbubble emitting means 10 shown in FIG. 2A. / The gas / liquid mixture introduction part 11 for drawing the liquid mixture into the interior and the divergent nozzle part 12 are constituted. The divergent nozzle portion 12 is a nozzle that gradually increases after the cross-sectional area initially decreases in the flow direction, and has a shape similar to a Venturi tube. The connecting portion between the gas / liquid mixture introducing portion 11 and the divergent nozzle portion 12 is formed with a constricted portion with a reduced flow cross-sectional area, and after passing through the throat 13 with a constant cross-sectional area, the inner wall The diameter is continuously expanded, and the space surrounded by the inner wall after the throat 13 has a substantially conical shape. A space (substantially conical space) surrounded by the inner wall of the divergent nozzle portion 12 forms a microbubble generator 14. In the illustrated example, the throttle portion of the divergent nozzle portion 12 is formed on a linear inclined surface, but the sectional view shape may be formed on an R surface.

  Further, the divergent nozzle portion 12 has a tip portion that constitutes a discharge port 15 that discharges a gas-liquid mixed fluid that communicates with the microbubble generating portion 14. Here, the micro-bubble generator 14 (substantially conical space) has an expansion angle θ of preferably 0 to 40 degrees, particularly preferably 3 to 10 degrees, and the angle θ illustrated in FIG. 2A. Is 6 degrees.

  When this divergence angle θ is large, flow separation occurs in the vicinity of the discharge port 15 and resistance to the flow increases. Therefore, it is necessary to increase the pressure at the inlet of the nozzle, and it is necessary to use extra power accordingly. By narrowing the spread angle θ, it is possible to provide a nozzle that is excellent in energy saving. In the illustrated embodiment, the inner wall of the space surrounded by the inner wall of the divergent nozzle portion 12 is linear in the sectional view (the space is conical). For example, it is formed in a gently curved surface in the sectional view. May be.

  In addition, the gas / liquid mixture introduction unit 11 is connected to the other end of the nozzle body connected to the liquid introduction port into the liquid contained in the water tank 3 to suck up and supply the liquid in the water tank 3. You may comprise so that it may circulate as a liquid. At this time, the water sucked up from the aquarium is contaminated with live fish feces, residual food, live fish mucus, peeled protein, and the like. Therefore, it is preferable to clean and circulate the liquid using a filtration device.

  The constituent members of the microbubble releasing means 10 can be made of metal (stainless steel, etc.), plastic (acrylic resin, etc.), etc., but are not limited to these materials, and are used in water so that the pressure of the supply liquid etc. An appropriate material can be adopted among materials having withstand strength.

  In addition, the microbubbles emitted from the microbubble emitting means 10 of the present invention may be emitted in any direction, but may be configured to be emitted in the horizontal direction or downward from the horizontal direction. preferable. Since bubbles rise upward due to the difference in specific gravity with the contained liquid, if the bubbles are discharged downward in the horizontal direction or in the horizontal direction, the time during which the microbubbles exist in the water can be lengthened. Since the contact time between the oxygen in the gas and the liquid in the water tank 3 can be increased, the dissolved oxygen concentration can be increased more efficiently.

  Another example of the microbubble emitting means is the microbubble emitting means 20 shown in FIG. 2B. In the microbubble releasing means 10, the microbubble releasing means 10 is provided with a suction-type gas introduction port for introducing gas, supplying the supply liquid from the supply liquid introduction unit 21, and taking in the gas from the suction-type gas introduction port 25. Except for this, the configuration is the same as that of the microbubble emitting means 10 in FIG. 2A.

  This suction-type gas inlet 25 naturally sucks the gas by the action of the liquid introduced by the supply liquid introduction part 21 and moves in such a manner as to supply gas in a self-sufficient manner. Thus, a device such as a compressor is not required, and the gas can be taken into the supply liquid at a constant rate, that is, the suction air amount (void ratio) with respect to the unit water flow rate at a constant rate. Therefore, it is possible to configure a live fish survival rate improving device that is simple in operation and low in cost.

  The method for improving the survival rate of live fish according to the present invention is a method for improving the survival rate of live fish in which live fish can grow and oxygen is supplied to the liquid contained in the aquarium together with the live fish to increase the dissolved oxygen concentration. A gas introduction step for mixing gas into the supply liquid, a microbubble generation step for generating a large number of microbubbles from the gas mixed in the gas introduction step, and a liquid in which the generated microbubbles are contained in a water tank together with the supply liquid And a bubble releasing step for releasing the bubble into the inside.

  The gas introduction step in the present invention mixes gas in the supply liquid in which seawater is mixed, and examples of the gas used here include gas containing 20% by volume or more of oxygen such as air and oxygen. Particularly preferred is oxygen gas. This is because the purpose is to improve the concentration of dissolved oxygen in the liquid by dissolving oxygen contained in the gas in the liquid contained in the water tank. In order to introduce such a gas containing oxygen, it can be introduced by applying pressure using a compressor, or can be introduced by self-sufficiency of gas drawn by the flow rate of the supply liquid.

  When the gas is introduced by a compressor, the gas can be forcibly introduced, so that the gas-liquid ratio can be arbitrarily set, and the amount of dissolved gas can be increased by pressure, which is preferable. In addition, when introducing the gas in a self-sufficient manner, a device such as a compressor for introducing the gas is unnecessary, and it can be performed with a simple configuration capable of automatically taking a certain proportion of the gas into the supply liquid, It is preferable in that the cost can be suppressed.

  For example, when the diameter of the throat portion in the microbubble generating means in FIG. 2A is 3 mm and θ is 6 °, and the pressure applied to the supply water is 0.4 MPa, the water flow rate is 10 L / min, The inflow rate is 1.0 to 3.7 L / min. When 0.3 MPa, the water flow rate is 7.5 L / min, the air blowing rate is 0.75 to 2.8 L / min, and In the case of 2 MPa, the water flow rate is preferably 5 L / min, and the air blowing rate is preferably 0.38 to 1.4 L / min.

  Moreover, as the supply liquid used here, the same liquid as that contained in the water tank can be used. Therefore, any live fish can be used without particular limitation, and examples thereof include tap water, sea water, river water, lake water, and the like. Emulsifiers (glycerin fatty acid esters and the like) used as food additives, and agents appropriately added with agents that stably disperse microbubbles such as sugars may be used.

  At this time, since the supply liquid is supplied into the water tank together with the microbubbles, it is preferable to use the same or the same kind of liquid as the liquid stored in the water tank, and it is preferable to use seawater. If this differs, the concentration of the liquid component changes with the passage of time, and in some cases, the survival rate of live fish is also reduced.

  The microbubble generation process in the present invention is to generate a large number of microbubbles from the gas mixed in the gas introduction process, and can effectively increase the dissolved oxygen concentration in the aquarium where live fish is grown, For example, bubbles having a diameter of 50 to 500 μm, preferably 50 to 200 μm are generated. In order to generate such fine bubbles, for example, a pressure difference is generated in the flow direction of the gas-liquid mixed fluid so that the supply liquid into which the gas is introduced passes through a narrower channel and a wider channel. A large number of microbubbles can be generated.

  In the bubble releasing step in the present invention, the microbubbles generated in the microbubble generating step are released together with the supply liquid into a water tank where live fish grows, and the liquid contained in the water tank is the same as the released gas. By contact, oxygen in the gas is taken in and the dissolved oxygen concentration is increased. At this time, the larger the contact area, the higher the efficiency of taking in oxygen. Therefore, the present invention that can suppress the coalescence of bubbles and release them as fine bubbles is highly effective in improving the dissolved oxygen concentration. It improves the survival rate of live fish.

  The following experiment was conducted using the live fish survival rate improving apparatus as shown in FIG.

  The live fish survival rate improving device 31 used here is configured by installing a water tank 33 containing seawater 32 and a microbubble releasing means 34 at the bottom thereof so that the microbubbles are discharged in the horizontal direction. The discharge means 34 is connected to a seawater supply pipe 36 having a pump 35. Moreover, the microbubble discharge | release means 34 is connected with the gas introduction pipe | tube 37 which takes in air self-sufficiently with the flow of the introduce | transduced seawater.

  And this live fish survival rate improvement apparatus 31 has the circulation path 39 provided with the filtration apparatus 38 which sucks up the seawater 32 in the water tank 33, and can supply it in the water tank 33 again. Therefore, by operating the pump 35, the seawater 32 in the water tank 33 passes through the circulation path 39 and is circulated while being purified, generating microbubbles and returning to the water tank again. Seawater used for growth can be used efficiently.

  In this embodiment, 730 L of seawater having a salt concentration of 3.5% by weight is accommodated in a 1460 mm × 1000 mm × 500 mm water tank, and 16 50 cm-class hamachi are placed in the water tank, and the water temperature is set to 18 to 18.6. The following experiment was conducted while maintaining the temperature.

  Seawater contained in the water tank 33 as a supply liquid was circulated through the circulation path 39 while cleaning the seawater by the filtration device 38, and supplied to the microbubble discharge means 34. Seawater, which is a supply liquid in the microbubble discharge means 34, is supplied at a flow rate of 7.5 L / min and a pressure of 0.3 MPa. At this time, the amount of air sucked from the gas introduction pipe 37 is 0.00. 75-2.8 L / min.

  When it was confirmed that microbubbles were stably generated and released, and the test under these conditions was continued for two months, the dissolved oxygen concentration (DO value) in seawater in the aquarium was constant at 7.3 ppm. All of the 16 hamachi survived, and the survival rate was 100%.

(Comparative example)
Using a dissolved oxygen enrichment apparatus having the same configuration as in Example 1 except that the microbubble releasing means is a method of bubbling with a conventional air stone and blowing air into the water tank alone, air blowing is performed When the test was conducted in the same manner at an amount of 40 L / min, eleven Hamachi survived and the survival rate was about 70%.

It is a schematic block diagram of the live fish survival rate improvement apparatus which concerns on this invention. It is a schematic sectional drawing of the microbubble discharge | release means based on this invention. It is a schematic sectional drawing of the other microbubble discharge | release means based on this invention. It is a schematic block diagram of the dissolved oxygen enrichment apparatus which concerns on a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Live fish survival rate improvement apparatus, 2 ... Liquid, 3 ... Water tank, 4 ... Microbubble discharge | release means, 5 ... Microbubble, 10 ... Microbubble discharge | release means, 11 ... Gas / liquid mixture introduction part, 12 ... Suehiro nozzle part , 13 ... Throat, 14 ... Microbubble generator, 15 ... Discharge port, 20 ... Microbubble discharge means, 21 ... Supply liquid introduction section, 22 ... Divergent nozzle section, 23 ... Throat, 24 ... Microbubble generator, 25 ... Suction-type gas introduction port, 26 ... discharge port, 31 ... live fish survival rate improving device, 32 ... seawater, 33 ... water tank, 34 ... microbubble releasing means, 35 ... pump, 36 ... seawater supply pipe, 37 ... gas introduction pipe 38 ... filtration device, 39 ... circulation path

Claims (8)

A live fish survival rate improving device comprising: a water tank that contains a liquid in which live fish can grow; and a microbubble releasing means that supplies oxygen into the liquid contained in the water tank to increase the dissolved oxygen concentration.
The microbubble releasing means introduces a supply liquid, introduces a gas into the supply liquid, introduces a gas into the supply liquid, and generates microbubbles from the gas mixed in the supply liquid. A live fish survival rate improving apparatus comprising: a portion; and a discharge port that discharges a large number of generated microbubbles together with a supply liquid into the liquid stored in the water tank.   The live fish survival rate improving device according to claim 1, wherein the gas introduction unit is self-contained.   The live fish survival rate improving device according to claim 1 or 2, wherein the microbubble releasing means discharges microbubbles from the discharge port in a horizontal direction. A method for improving the survival rate of live fish, in which live fish can grow, and in a liquid contained in the aquarium with live fish, supplies oxygen to increase the dissolved oxygen concentration,
A gas introduction step of mixing gas into the supply liquid;
A microbubble generating step for generating a large number of microbubbles from the gas mixed by the gas introducing step;
A bubble releasing step for discharging the generated microbubbles together with the supply liquid into the liquid contained in the water tank;
A method for improving the survival rate of live fish characterized by comprising:   The method for improving the survival rate of live fish according to claim 4, wherein the gas introduction step introduces gas in a self-sufficient manner.   6. The live fish survival rate improving method according to claim 4 or 5, wherein the bubble releasing step discharges from the discharge port in a horizontal direction.   The method for improving the survival rate of live fish according to any one of claims 4 to 6, wherein the liquid stored in the aquarium and the supply liquid are seawater.   The live fish survival rate improving method according to claim 7, wherein the salt concentration of the seawater is 3 to 4% by weight.

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