JP2018110569A - Sterilization method of shellfish and sterilization system of shellfish - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient sterilization method or sterilization system of shellfishes.SOLUTION: A sterilization method of shellfishes comprises preparing seawater to a reservoir 12, sinking the shellfishes to the reservoir 12, and also making bubbles of oxygen gas be contained in the seawater reserved in the reservoir 12. The bubbles are less than 100 nm in diameter. A sterilization system of the shellfishes includes a fine bubble-generating unit 14 for generating fine bubbles of the oxygen gas in the seawater, a first ultrasonic crushing unit 16 for crushing the fine bubbles in the seawater by applying pressure and generating ultra-fine bubbles, the reservoir 12 for holding the shellfishes along with the seawater containing the ultra-fine bubbles, and a first pump 18 for supplying the seawater from the reservoir 12 to fine bubble-generating unit 14 or the first ultrasonic crushing unit 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shellfish sterilization method and a shellfish sterilization system.

  Some shellfish are cultivated for food. For example, in edible oyster culture, oysters are harvested after being grown in the sea and shipped to the market. In this aquaculture process, deposits adhering to mud and shells are removed by a washing machine before being shipped to the market, and then kept in clean seawater for a certain period of time for purification.

  By the way, in shellfish represented by oysters, food poisoning due to viruses may be a problem. For example, norovirus accumulates in the midgut gland of oysters during the breeding process and enters the human body to cause food poisoning. In order to solve this problem of food poisoning, it is effective to inactivate the virus and clean and sterilize it. Therefore, there is a great deal of research on virus inactivation for the purpose of preventing food poisoning of shellfish. Has been.

  As one of such measures, for example, Non-Patent Document 1 describes a method for inactivating norovirus that causes food poisoning caused by eating raw shellfish such as oysters by ultraviolet rays. . According to this method, it has been confirmed that the number of viruses is reduced and inactivated by sinking oysters that have incorporated viruses into the midgut line into water tanks and refluxing the water tanks irradiated with ultraviolet rays.

  As another countermeasure, use of fine bubbles called microbubbles or nanobubbles has been studied. For example, Non-Patent Document 2 describes that norovirus in seawater can be inactivated by ozone microbubbles. In this method, an ozone bubble acts on a virus, and the virus is inactivated by a bactericidal effect between ozone and the bubble.

  Furthermore, Patent Document 1 describes a method for cultivating oysters using nanobubbles. In this method, it is also devised that the norovirus is killed and inactivated by washing oysters with seawater in which ozone gas is made into nanobubbles.

JP 2012-96216 A

Miwa Fukuda et al., “Cultivated Oyster Virus Purification Test”, Mie Prefectural Science and Technology Promotion Center, Health and Environment Research Department, National Institute of Public Health, Tokyo Metropolitan Institute of Public Health, Suzuka International University, Tanuki University, February 20, 2003, Journal of Infectious Diseases, Vol. 77, No. 2, p. 95-102 Masayoshi Takahashi, “Successful inactivation of norovirus”, AIST Today, National Institute of Advanced Industrial Science and Technology, March 2004, Vol. 4, No. 3, p. 18-20

  However, the purification method described in Non-Patent Document 1 circulates seawater in which oysters are submerged, and kills the virus by ultraviolet rays in the middle of the circulated seawater. The virus that has entered the midgut line cannot be discharged into the seawater, and because the ultraviolet rays do not reach the shellfish, the virus accumulated in the shellfish cannot be killed. .

  The inactivation methods described in Non-Patent Document 2 and Patent Document 1 are intended to inactivate viruses with bubbles of ozone gas. If ozone is applied to living shellfish, it may kill the shellfish together with the virus. There was no problem. Furthermore, research reports have shown that the bactericidal effect of microbubbles and nanobubbles alone is not sufficient to inactivate viruses.

  The present invention has been made in view of such problems, and an object thereof is to provide an effective shellfish sterilization method or sterilization system using ultrafine bubbles.

  The shellfish sterilization method according to the present invention includes preparing seawater in a storage section, sinking shellfish in the storage section, and containing oxygen gas bubbles in the seawater stored in the storage section. And the bubbles have a diameter of less than 100 nm.

  According to this shellfish sterilization method, by submerging shellfish in seawater containing bubbles with a diameter of less than 100 nm (hereinafter referred to as “ultrafine bubbles”), the bubbles enter the shellfish body, Viruses and the like in shells can be adsorbed and removed from the body, and discharged outside the body, that is, sterilized.

  Furthermore, since the ultrafine bubbles are oxygen gas, the shells that take in seawater containing them are activated, and the amount of shellfish that takes in seawater increases. Thereby, the circulation of the seawater which an oyster inhales and discharges is accelerated, and shellfish can be sterilized efficiently. Further, since the seawater itself is sterilized by the ultrafine bubbles, it is possible to prevent the sterilized shellfish from being contaminated with viruses again.

  In the shellfish sterilization method according to the present invention, the seawater may have a dissolved oxygen concentration in a range of 5 ppm to 20 ppm. If the dissolved oxygen concentration is less than 5 ppm, the shellfish are not activated sufficiently. On the other hand, even if the dissolved oxygen concentration exceeds 20 ppm, the shellfish are difficult to activate. Therefore, if the dissolved oxygen concentration is within this range, shellfish are activated and the sterilization efficiency is increased. The bubbles do not consist only of oxygen gas, but may be bubbles containing oxygen gas such as air bubbles. In addition to bubbles having a diameter of less than 100 nm, bubbles having a diameter of 100 nm or more may be present in seawater.

  In the shellfish sterilization method according to the present invention, the oxygen gas bubbles may have a particle diameter of 20 nm to 70 nm. Here, in order to adsorb and desorb viruses accumulated in the midgut line of shellfish, it is necessary that ultrafine bubbles surely enter the midgut line. If it is a bubble with a particle diameter of 20 nm to 70 nm, it has the same size as a general virus that has entered the midgut line, and it is possible to reliably allow ultrafine bubbles to enter the midgut line.

  In the shellfish sterilization method according to the present invention, the shellfish may be held in the seawater for 12 hours or more and 24 hours or less. According to this shellfish sterilization method, viruses and the like present in the shellfish body can be sufficiently discharged out of the body.

  In the shellfish sterilization method according to the present invention, the bubbles may be generated by being crushed by irradiating the seawater with ultrasonic waves. According to this shellfish sterilization method, the seawater containing the virus adsorbed and desorbed and discharged from the shellfish body is irradiated with ultrasonic waves to generate ultrafine bubbles for the purpose of adsorption and desorption. The virus is killed by the bactericidal effect of ultrasound. Therefore, it is possible to prevent the sterilized shellfish from being contaminated with viruses again.

  The shellfish sterilization system according to the present invention includes a fine bubble generating unit for generating fine bubbles of oxygen gas in seawater, and a first ultrasonic wave for generating ultrafine bubbles by crushing the fine bubbles in the seawater. A crushing part and a storage part holding shellfish with seawater containing the ultrafine bubbles are provided, and the seawater is supplied from the storage part to the fine bubble generation part or the first ultrasonic crushing part.

  According to this shellfish sterilization system, the fine bubbles of oxygen gas generated in the fine bubble generating portion are crushed by irradiating the first ultrasonic crushing portion with ultrasonic waves, thereby making the ultrafine bubbles that are smaller bubbles. Bubbles can be generated. At the same time, by irradiating the seawater with ultrasonic waves, viruses in the seawater can be killed by the sterilizing effect of the ultrasonic waves. Thereby, clean seawater containing ultrafine bubbles for adsorbing and desorbing the virus and killing the virus is obtained.

  The shellfish sterilization system according to the present invention further includes a second ultrasonic crushing unit that supplies the seawater from the storage unit and irradiates the supplied seawater with ultrasonic waves, and the second ultrasonic wave. The seawater may be discharged to the outside from the storage part after passing through the crushing part.

  In such a shellfish sterilization system, the seawater can be irradiated to the seawater at the second ultrasonic crushing part before the seawater held in the storage part is discharged to the outside. Therefore, the discharged seawater is sterilized by ultrasonic waves. Thereby, the load to an environment can be suppressed.

  According to the present invention, an effective shellfish sterilization method or sterilization system can be provided.

It is a figure which shows the functional block of the shellfish sterilization system which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the fine bubble generation | occurrence | production part shown in FIG. It is the schematic of the 1st ultrasonic crushing part shown in FIG. 1, (A) shows a side view, (B) shows a front view. It is the schematic of the storage part shown in FIG. It is a figure explaining the disinfection action by a bubble, (A) is the state which took the shell of the oyster, (B) is a schematic diagram of the ultrafine bubble in the midgut gland, (B) is the microbubble in the midgut gland A schematic diagram is shown. It is a schematic diagram of the ultrafine bubble in seawater. It is a figure which shows the result of having observed the ultrafine bubble using the PLL-mica board | substrate, (A) is an observation photograph, (B) is a graph of the height on the white line of (A). It is a figure which shows the result of having observed the ultrafine bubble using the PLL-mica board | substrate, (A) is an observation photograph, (B) is a graph of the height on the white line of (A). It is a figure which shows the result of having observed the ultrafine bubble using the APTES-mica board | substrate, (A) is an observation photograph, (B) is a graph of the height on the white line of (A). It is a figure which shows the result of having observed the ultrafine bubble using the APTES-mica board | substrate, (A) is an observation photograph, (B) is a graph of the height on the white line of (A).

[Embodiment of shellfish sterilization system]
A shellfish sterilization system according to an embodiment of the present invention will be described with reference to the drawings. The sterilization system 10 sterilizes the cultured shellfish before shipping them to the market. This embodiment demonstrates the case where an oyster is applied as shellfish. However, the sterilization system 10 may be applied to shellfish other than oysters.

  FIG. 1 shows a functional block diagram of a shellfish sterilization system 10. The sterilization system 10 stores seawater, a storage unit 12 for sinking oysters in the stored seawater, a microbubble generation unit 14 that generates microbubbles of oxygen gas in the seawater, and a first that crushes microbubbles. The ultrasonic crushing part 16 is provided. A first pump 18 is disposed between the storage unit 12 and the fine bubble generation unit 14 to supply seawater from the storage unit 12 to the fine bubble generation unit 14. The storage part 12, the fine bubble generating part 14, and the first ultrasonic crushing part 16 are connected to each other and form a circulation path 102 for circulating seawater.

  The sterilization system 10 also includes a second ultrasonic crushing unit 20 that irradiates the seawater derived from the storage unit 12 or the seawater pumped from the sea area 24 with ultrasonic waves. A valve 22 is provided between the storage unit 12 and the second ultrasonic crushing unit 20, and the amount of seawater derived from the storage unit 12 to the second ultrasonic crushing unit 20 or the second ultrasonic crushing unit is provided. The derivation amount of seawater from the unit 20 to the storage unit 12 can be adjusted. Further, a second pump 26 is disposed between the second ultrasonic crushing portion 20 and the external sea area 24, and the seawater discharged from the second ultrasonic crushing section 20 is discharged to the sea area 24. Alternatively, seawater can be pumped from the sea area 24 to the second ultrasonic crushing section 20.

  The storage unit 12, the fine bubble generation unit 14, the first ultrasonic crushing unit 16, the first pump 18, the second ultrasonic crushing unit 20, and the valve 22 are controlled by a control unit 28 that centrally manages the sterilization system 10. Managed. In FIG. 1, connections between the control unit 28 and each unit managed by the control unit 28 are indicated by broken lines. The control unit 28 may control the sterilization system 10 in cooperation with an external control device or the like. Moreover, each part of the sterilization system 10 may be controlled by another control device or the like.

[Microbubble generation part]
FIG. 2 is a schematic cross-sectional view of the fine bubble generating unit 14 shown in FIG. The fine bubble generating unit 14 includes a turning unit 142, a protrusion crushing unit 144, a breeding unit 146, and a foaming unit 148.

  The swirling unit 142 spirals the seawater supplied from the storage unit 12 by the first pump 18 to form a swirling flow, and supplies the seawater to the protrusion crushing unit 144. The seawater supplied to the swivel unit 142 by the first pump 18 is supplied with oxygen gas from an oxygen supply unit (not shown), and oxygen gas bubbles are generated (for example, Japanese Patent Application Laid-Open No. 2015-188671). reference).

  The protrusion crushing part 144 includes a plurality of protrusions 144a that are provided downstream of the swirl part 142 in the seawater flow direction and are adapted to the swirl flow. Thereby, the protrusion crushing part 144 shears and crushes the bubble-containing seawater that has passed through the swivel part 142 with the protrusion 144a. Accordingly, the bubbles of the bubble-containing seawater hit the protrusions 144a and are pulverized to become fine bubbles, and the bubble concentration of the bubble-containing seawater is improved by the bubbles becoming finer.

  The animal breeding part 146 retains the bubble-containing seawater whose bubble concentration is improved for a certain period of time by passing through the protrusion crushing part 144. As a result, the amount of charge held in the bubble generated by the shear collapse at the protrusion collapse portion 144 and the zeta potential can be made uniform. Therefore, in the livestock raising part 146, the particle size of the bubble of bubble-containing seawater can be arrange | equalized. Moreover, the livestock raising part 146 is connected to the livestock raising pressurizer (not shown), and can pressurize the inside of the livestock raising part 146 to a predetermined pressure (0.8 MPa to 2.0 MPa). The bubble concentration can be improved by increasing the pressure in the animal breeding unit 146 to a constant pressure by utilizing the pressurization and compression effect of the surplus gas.

  The foaming part 148 includes a slit hole (not shown) through which the bubble-containing seawater flows from the animal breeding part 146, a repressurization space 148a following the slit hole, and a decompression space 148b following the repressurization space 148a. The repressurization space 148a allows seawater to flow into the decompression space 148b through an outflow hole having a diameter smaller than that of the slit hole. As a result, the bubble-containing seawater temporarily retained in the animal breeding unit 146 flows into the repressurization space 148a through the slit hole, is pressurized in the repressurization space 148a, and then depressurizes through the outflow hole. The pressure is reduced by flowing into the space 148b. Seawater flowing into the foaming part 148 is pressurized and depressurized, and the bubble concentration is further increased.

  The fine bubble generating unit 14 according to the present embodiment has a configuration and a function of turning, crushing, animal husbandry, and foaming (pressurization, decompression). However, the present invention is not limited to these functions, and may have other configurations and functions as long as microbubbles can be generated (see, for example, JP-A-2015-202437).

[First ultrasonic crushing part]
3A and 3B are schematic views of the first ultrasonic crushing portion 16 shown in FIG. 1, wherein FIG. 3A shows a side view and FIG. 3B shows a front view. The first ultrasonic crushing portion 16 includes a passage 162 that is connected to the fine bubble generating portion 14 and allows the bubble-containing seawater produced by the fine bubble generating portion 14 to pass therethrough, and an exterior body 164 that covers the periphery of the passage 162. The two-layer structure has an intermediate space 166 between the passage 162 and the exterior body 164. The first ultrasonic crushing portion 16 is arranged so that the passage 162 extends in the horizontal direction.

  A plurality of ultrasonic transducers 168 are provided in the exterior body 164, and each ultrasonic transducer 168 irradiates ultrasonic waves toward the passage 162. The intermediate space 166 between the passage 162 and the exterior body 164 is filled with the propagation liquid, and the ultrasonic wave irradiated from the ultrasonic vibrator 168 is propagated to the inside of the passage 162 through the propagation liquid. The fine bubbles of the seawater containing bubbles are crushed.

  The propagation liquid is cooling water supplied from a cooling water supply device (not shown), introduced into the intermediate space 166 from the propagation liquid introduction port 164a provided in the exterior body 164, and also propagated in the exterior body 164. Derived from the liquid outlet 164b. In the first ultrasonic crushing portion 16, the bubble-containing seawater passing through the passage 162 is heated by the ultrasonic irradiation by the ultrasonic vibrator 168. Here, since the propagation liquid (cooling water) also has an action of cooling the first ultrasonic crushing portion 16, the temperature of the bubble-containing seawater passing through the passage 162 is adjusted by adjusting the flow rate of the propagation liquid. Can do.

  The passage 162 is formed of a pipe made of a fluororesin such as PFA (polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or PVC (polyvinyl chloride). Thereby, the passage 162 has a circular cross section, extends in a cylindrical shape with the same diameter, and forms a uniform flow path in the flow direction of the bubble-containing seawater. The passage 162 is connected so as to be interposed between the fine bubble generation unit 14 and the storage unit 12, and the bubble-containing seawater supplied from the fine bubble generation unit 14 is filled in the passage 162 and is stored in the storage unit 12. To be washed away.

  The exterior body 164 is made of stainless steel and includes a side peripheral member 164c extending in a hexagonal column shape having a regular hexagonal cross section, and a pair of disk-shaped planar members 164d sandwiching the side peripheral member 164c from both sides in the extending direction. . Both planar members 164d have a passage 162 fixed in the center thereof, and the passage 162 is fixed so that the passage 162 extends on the central axis of the regular hexagonal column formed by the side peripheral member 164c. Thus, an intermediate space 166 is formed by the outer periphery of the passage 162 and the inner surface of the side peripheral member 164c of the exterior body 164.

  In the exterior body 164, an ultrasonic transducer 168 is attached to each surface of the hexagonal column formed by the side peripheral member 164c. The ultrasonic transducer 168 is provided in two stages in the front-rear direction in the direction in which the passage 162 extends. The ultrasonic bubble group 14 side is the front ultrasonic transducer group, and the storage unit 12 side is the rear ultrasonic vibration. It is a child group. The ultrasonic transducer group in each stage is composed of six ultrasonic transducers 168 provided radially from the central axis of the passage 162. The two ultrasonic transducers 168 facing each other constitute a pair of transducers, and the six ultrasonic transducers 168 at each stage constitute a total of three transducer pairs. Each ultrasonic transducer 168 can adjust the frequency and output of the generated ultrasonic wave by the control unit 28. In the present embodiment, all twelve ultrasonic transducers 168 irradiate ultrasonic waves with the same frequency and the same output.

  Each of the ultrasonic transducers 168 at each stage irradiates an ultrasonic wave toward a central point of the passage 162. Therefore, each ultrasonic transducer 168 irradiates ultrasonic waves from different positions in different radial directions and radially inward toward the center of the passage 162. Thereby, it is suppressed that the bubble-containing seawater which flows through the channel | path 162 is inhibited from flowing by ultrasonic waves. In particular, the ultrasonic transducers 168 constituting each pair irradiate ultrasonic waves from the positions facing each other toward the facing direction. Therefore, an ultrasonic crushing field is formed in the center of the passage 162, the fine bubbles of the bubble-containing seawater passing through the passage 162 are crushed, and the ultrafine bubbles are generated.

  In the 1st ultrasonic crushing part 16, an ultrasonic wave is irradiated from a some direction, and an ultrasonic crushing field is formed in the place where an ultrasonic wave concentrates. Therefore, in this embodiment, the ultrasonic transducer group at each stage forms an ultrasonic crushing field in the passage 162. Even if all of the fine bubbles are not crushed in the ultrasonic crushing field formed by the ultrasonic transducer group at the front stage, the ultrasonic crushing field formed by the ultrasonic transducer group at the rear stage crushes the remaining fine bubbles. To do. Therefore, in the first ultrasonic crushing portion 16 according to the present embodiment, the fine bubbles can be surely crushed and the ultrafine bubbles having a uniform particle diameter can be generated. In the present embodiment, the first ultrasonic crushing portion 16 generates ultrafine bubbles.

  In the present embodiment, the passage 162 of the first ultrasonic crushing portion 16 is formed from a pipe made of a fluororesin such as PFA or a PVC pipe, but may be made of other resin or hygiene. A metal that has no problem in terms of surface and corrosion may be used as a material. In addition, the first ultrasonic crushing portion 16 has a two-layer structure including the passage 162 and the exterior body 164, but may have other configurations as long as the fine bubbles can be crushed by irradiation with ultrasonic waves. For example, a cylindrical member with a single-layer structure is formed from a metal such as titanium that does not cause problems in terms of hygiene and corrosion even when seawater is passed, and an ultrasonic transducer is placed directly around the cylindrical member And you may make it pass bubble-containing seawater inside the said cylindrical member.

  The 1st ultrasonic crushing part 16 concerning the embodiment of the present invention forms an ultrasonic crushing field, crushes the fine bubble which seawater contains, and converts it into an ultrafine bubble. The ultrasonic crushing field is formed by continuously irradiating ultrasonic waves, and ultraviolet rays are generated in the ultrasonic crushing field by a so-called sonoluminescence phenomenon. Therefore, the sterilization effect by ultraviolet rays can be obtained for seawater passing through the ultrasonic crushing field.

  Furthermore, in the 1st ultrasonic crushing part 16, the ultrasonic wave which forms an ultrasonic crushing field is irradiated to seawater, A countless vacuum bubble arises by cavitation in a liquid. When this vacuum bubble collapses by repeated compression and expansion, an ultrahigh temperature and high pressure reaction field is formed. In this reaction field, the cell walls of bacteria are destroyed by rupture of vacuum bubbles, and an effect of killing viruses such as Norovirus in addition to general living bacteria, Legionella bacteria, Escherichia coli and the like can be obtained.

[Reservoir]
FIG. 4 shows a schematic diagram of the reservoir 12 shown in FIG. The storage unit 12 is a container that holds the seawater 30 and the oysters 32. The oysters 32 are cultivated and fully grown in the ocean, and are before being shipped to the market. The storage unit 12 may have any shape, for example, a hollow cylindrical shape. In the present embodiment, the storage unit 12 is a hollow rectangular parallelepiped (square column). The storage unit 12 is provided with a seawater introduction pipe 122, a recursive derivation pipe 124, and a seawater exchange pipe 126. The seawater inlet pipe 122 and the recursive outlet pipe 124 are included in the circulation path 102. A net shelf 128 is horizontally disposed below the storage unit 12. The oyster 32 is arranged on the net shelf 128 and is suspended in the seawater 30 by the string 32b. In the present embodiment, the storage unit 12 uses a water tank such as a pool.

  The seawater introduction pipe 122 is connected to the first ultrasonic crushing section 16 and introduces the seawater 30 containing ultrafine bubbles. The seawater introduction pipe 122 is mainly composed of a cylindrical pipe, and extends from above the storage part 12 toward the bottom part. The end of the seawater introduction pipe 122 inside the storage unit 12 is arranged at a height of 1/2 from the bottom of the storage unit 12. The seawater 30 is maintained in such an amount that the water surface is positioned at substantially the upper end of the reservoir 12 in a steady state.

  The bubbles contained in the seawater 30 tend to diffuse downward as the particle size decreases. Therefore, an NB region in which the presence of so-called nanobubbles is dominant is formed at the bottom of the storage unit 12, an MN region in which nanobubbles and microbubbles are mixed is formed above, and the presence of microbubbles is further above that A dominant MB region is formed. Even in the NB region formed at the bottom of the reservoir 12, the closer to the bottom, the smaller the particle size of the bubbles, and the ultrafine bubbles are dominant near the bottom where the oysters 32 arranged on the net shelf 128 are present.

  The height and position of each region in the storage unit 12 vary depending on the storage amount of the seawater 30, the operation state of the fine bubble generation unit, the ultrasonic crushing unit, and the like. Here, “nanobubble” refers to a bubble having a particle size on the order of nanometers, and “microbubble” refers to a bubble having a particle size on the order of micrometers. “Ultrafine bubbles” refer to nanobubbles having a diameter of less than 100 nm.

  The seawater introduction pipe 122 has an end disposed inside the storage unit 12 bent into an L shape, and discharges the seawater 30 in the horizontal direction. Thereby, the seawater 30 containing ultrafine bubbles receives a discharge pressure in the horizontal direction and is agitated. However, since the seawater 30 does not receive the discharge pressure in the vertical direction, it does not prevent the bubbles having a small particle diameter from being highly concentrated below the reservoir 12.

  The recursive derivation tube 124 is connected to the fine bubble generating unit 14 via the first pump 18, and guides the seawater 30 to the fine bubble generating unit 14. The recursive derivation pipe 124 is mainly composed of a cylindrical pipe, and extends upward from the bottom of the storage section 12. The end of the recursion lead pipe 124 inside the storage unit 12 is arranged at a height position of ¼ from the bottom of the storage unit 12.

  The recursive derivation pipe 124 causes the fine bubble generating unit 14 to recurse the seawater 30 at a ¼ height position from the bottom of the storage unit 12 via the first pump 18. The recursive derivation pipe 124 has an end disposed inside the storage unit 12 bent into an L shape and sucks the seawater 30 in the horizontal direction. As a result, the seawater 30 containing ultrafine bubbles is subjected to suction pressure in the horizontal direction and is stirred in the reservoir 12. However, since the seawater 30 does not receive the suction pressure in the vertical direction, it does not prevent the bubbles having a small particle diameter from being highly concentrated below the reservoir 12.

  The seawater exchange pipe 126 functions as a bottom valve and is connected to the second ultrasonic crushing portion 20 via the valve 22, and guides the seawater 30 to the second ultrasonic crushing portion 20, and Seawater 30 is introduced from the ultrasonic crushing section 20. The seawater exchange pipe 126 is mainly composed of a cylindrical pipe, extends from the bottom of the storage unit 12 to the lower surface of the storage unit 12, takes out the seawater 30 from the bottom of the storage unit 12 together with the excrement of the oysters 32, and the like. Seawater 30 can be supplied from the bottom of the reservoir 12.

  The net shelf 128 has a mesh smaller than the oyster 32. Since the excrement of the oyster 32 falls below the net shelf 128, the oyster 32 can be prevented from re-inhaling the excrement. In the embodiment of the present invention, the oyster 32 is arranged on the net shelf 128 and is suspended in the seawater 30 by the string 32b, but if it can be submerged in the seawater 30 stored in the storage unit 12, It may be arranged only on the net shelf 128, may be simply suspended in the seawater 30 by the string 32b, or may be submerged in the seawater 30 stored in the storage unit 12 by another method.

  In the shellfish sterilization system 10 according to this embodiment, the storage unit 12 and the bubble-containing seawater supply unit configured by the fine bubble generation unit 14 and the first ultrasonic crushing unit 16 are separated. Thereby, the bubble-containing seawater supply unit can continuously supply a certain amount of seawater containing ultrafine bubbles without being affected by the capacity of the storage unit 12. Since the seawater 30 containing ultrafine bubbles is stored in the storage unit 12, the bubbles are prevented from aggregating in the storage unit 12.

  Further, the oyster 32 held in the storage unit 12 allows the ultrafine bubbles contained in the seawater 30 to selectively adsorb viruses and the like in the body to be detached from the body and discharged out of the body. That is, it is sterilized by the ultrafine bubbles of the seawater 30.

[Second ultrasonic crushing part]
The second ultrasonic crushing unit 20 is connected to the storage unit 12 via a valve 22, and a second pump 26 is connected to the side opposite to the valve 22. Since the second ultrasonic crushing portion 20 has the same configuration as the first ultrasonic crushing portion 16, a description of a specific configuration is omitted.

  The second ultrasonic crushing section 20 opens and closes the valve 22 as necessary between the storage section 12 and introduces and leads out seawater. When seawater is not introduced and led out, the valve 22 is closed.

  When seawater is introduced from the storage unit 12 to the second ultrasonic crushing unit 20, the second ultrasonic crushing unit 20 irradiates the introduced seawater with ultrasonic waves to remove germs and viruses remaining in the seawater. Annihilate. Then, the seawater 32 is discharged to the sea area 24 by the second pump 26. Since the discharged seawater is irradiated with ultrasonic waves and kills germs and viruses, it is possible to suppress the environmental load and adverse effects of the sea area 24.

  When the seawater is derived from the second ultrasonic crushing unit 20 to the storage unit 12, the seawater pumped up from the sea area 24 by the second pump 26 is irradiated with ultrasonic waves and then guided to the storage unit 12. Since the seawater led out to the storage unit 12 is irradiated with ultrasonic waves and kills germs and viruses, the load on the oysters held in the storage unit 12 and adverse effects can be suppressed.

[Circulation route]
In the shellfish sterilization system 10 according to the present embodiment, the storage unit 12, the fine bubble generation unit 14, and the first ultrasonic crushing unit 16 are incorporated in the circulation path 102, and sequentially from the upstream side in the flow direction of seawater. 12 is connected to the fine bubble generating unit 14 via the first pump 18, the first ultrasonic crushing unit 16 is connected to the fine bubble generating unit 14, and the storage unit 12 is connected to the first ultrasonic crushing unit 16. It is connected. In addition, a second ultrasonic crushing portion 20 is connected to the storage portion 12 via a valve 22, and the second ultrasonic crushing portion 20 is connected to the sea area 24 via a second pump 26.

  That is, in the circulation path 102, seawater introduced from the sea area 24 through the second pump 26, the second ultrasonic crushing section 20 and the valve 22 into the storage section 12 is converted into the fine bubble generating section 14 and the first It is formed so as to return to the storage part 12 again via the ultrasonic crushing part 16. Since the seawater containing the ultrafine bubbles recurs, the content of the ultrafine bubbles in the seawater held in the reservoir 12 can be maintained higher than when all the seawater is newly introduced from the sea area 24.

  Seawater produced by the sterilization system according to the present embodiment contains ultrafine bubbles. Ultrafine bubbles remain in seawater for a long period of several months. Therefore, the seawater produced by the sterilization system according to the present embodiment can suppress the growth of bacteria by the remaining ultrafine bubbles and can obtain a sterilization effect over a long period of time.

[Examples of shellfish sanitization method]
Next, the shellfish sterilization method according to the embodiment of the present invention will be described. In this sterilization method, the sterilization system 10 is used to sterilize shellfish.

  In the shellfish sterilization method according to the embodiment of the present invention, the oysters 32 are held in the seawater 30 held in the storage unit 12 of the sterilization system 10. The seawater 30 contains oxygen gas ultrafine bubbles by the operations of the fine bubble generating unit 14 and the first ultrasonic crushing unit 16 of the sterilization system 10, and the ultrafine bubbles are bubbles having a diameter of less than 100 nm.

  In the sterilization method according to the present invention, first, seawater 30 is prepared in the reservoir. Specifically, the pump 26 operates and the seawater 30 in the sea area is introduced into the storage unit 12 via the second ultrasonic crushing unit 20. At this time, the bacteria and viruses in the seawater are killed by the operation of the second ultrasonic crushing section 20.

  Next, the shellfish are submerged in the seawater 30 stored in the storage unit 12. Specifically, the oyster 32 is sunk from the upper side opened to the storage part 12 in which the seawater 30 is stored. However, the oyster 32 may be prepared in the storage unit 12 first, and the oyster 32 may be submerged in the seawater 32 by supplying seawater later.

  Next, oxygen gas bubbles are contained in the seawater 32 stored in the storage unit 12. Specifically, the seawater 30 stored in the storage unit 12 is supplied to the fine bubble generation unit 14 by the operation of the first pump 18, and the seawater 30 in which the fine bubbles of oxygen gas are generated by the microbubble generation unit 14. Is supplied to the first ultrasonic crushing portion 16, and the seawater 30 in which the fine bubbles are converted into the ultrafine bubbles in the first ultrasonic crushing portion is returned to the storage portion 12. Therefore, the seawater stored in the storage unit 12 via the circulation path 102 contains oxygen gas bubbles having a particle size of less than 100 nm.

  The oyster 32 sterilized by the shellfish sterilization method according to the embodiment of the present invention is cultivated and grown in the ocean. Therefore, the shellfish sterilization method according to the embodiment of the present invention is also referred to as “beach raising, livestock cleaning, sterilization”. The oyster 32 is suspended by the string 32b in the seawater 30 of the storage unit 12 after removing dirt and small shellfish attached to the shell during aquaculture in the ocean, or a net shelf 128. Is held by being placed on the top.

  In the shellfish sterilization method according to the embodiment of the present invention, the oyster 32 is held in the seawater 30 for 12 hours to 24 hours.

  FIG. 5 is a diagram for explaining the sterilization action by bubbles, (A) is a state where oyster shells are taken off, (B) is a schematic diagram of ultrafine bubbles in the midgut gland, (B) is a midgut gland The schematic diagram of the microbubble in is shown. The oyster 32 may have viruses such as norovirus accumulated in its body. For example, norovirus causing food poisoning is accumulated in the midgut gland located at the position shown in FIG. Therefore, the oysters 32 are washed and sterilized after they are grown by aquaculture and before being shipped to the market.

  As shown in FIG. 5B, since the ultrafine bubbles 34 have a very small particle size, they reach every corner of the midgut gland 32a. The ultrafine bubbles 34 that have reached the intestinal digestive wall inside the midgut gland have a negative charge, are selectively adsorbed by a virus or the like having the property of a bipolar electrolyte, and desorbed from the body. It can be discharged. That is, the oyster 32 can be sterilized.

  On the other hand, as shown in FIG. 5C, the microbubbles 36 do not reach every corner inside the midgut gland 32a. Further, even nanobubbles having a diameter of 100 nm or more cannot be adsorbed by oyster eyelashes and reach the midgut gland. For this reason, microbubbles 36 and nanobubbles having a diameter of 100 nm or more cannot sufficiently sterilize viruses and the like.

  FIG. 6 shows a schematic diagram of the presence of ultrafine bubbles in seawater. In the sea water, sodium ions 38 and chlorine ions 40 exist. Since the ultrafine bubbles 34 are negatively charged in the sea water, sodium ions 38 having a positive charge gather around the ultrafine bubbles 34. By collecting the sodium ions 38, a positively charged layer is formed around the ultrafine bubbles 34, and chlorine ions 40 are collected in the positively charged layer. Therefore, chlorine ions 40 concentrate around the ultrafine bubbles 34, and the chlorine concentration is significantly higher than other portions of the seawater 30. The sterilization effect of seawater can be improved by increasing this chlorine concentration.

  In the shellfish sterilization system 10 according to the embodiment of the present invention, the viruses accumulated in the shellfish are selectively adsorbed and desorbed by the ultrafine bubbles and discharged from the shellfish body, that is, sterilized. And the discharged | emitted virus is killed by an ultrasonic wave in an ultrasonic crushing part. In conventional chemical sterilization with hypochlorous acid or the like, it is possible to kill bacteria and viruses by mixing chemicals into seawater, but at the same time adversely affects shellfish. However, the shell sterilization system 10 according to the embodiment of the present invention does not affect the shellfish as long as it is physical sterilization using ultrasonic waves.

[Results of observation of ultrafine bubbles]
Next, the result of observing the ultrafine bubbles generated by the first ultrasonic crushing part according to the embodiment of the present invention will be described. For observation of ultrafine bubbles, a high-speed atomic force microscope (high-speed AFM) was used.

The observation conditions are as follows.
Equipment: High-speed atomic force microscope NanoExplorer
Observation environment: Room temperature (21 ° C)
Cantilever: BL-AC10DS-A2 (Olympus, Japan)
Resolution: 200 × 200 pixels Observation image: AC mode shape image in liquid Note that nanobubbles are generally known to have negative charges, and use positively charged substrates (PLL-mica substrate and APTES-mica substrate). And observed.

  7 and 8 show the observation results of the ultrafine bubbles observed using the PLL-mica substrate, each figure (A) shows an observation photograph, and each figure (B) is on the white line in (A). A graph of height is shown. The position of the triangular mark on the white line shown in (A) of each figure corresponds to the position of the triangular mark on the graph of (B). Here, PLL (Poly-L-Lycine) is a lysine polymer that is an amino acid. Lysine has an amino group and is positively charged. Therefore, by covering the negatively charged mica (mica) with the PLL, the mica surface can have a positive charge.

  FIG. 7A shows an observation photograph under a condition where the scanning range is 500 nm, and FIG. 8A shows an observation photograph under a condition where the scanning range is 200 nm. According to FIG. 7 (B), FIG. 7 (A) shows that particles having a height of 20.9 nm and a length in the white line direction of 75.4 nm were observed, according to FIG. 8 (B). FIG. 8A shows that particles having a height of 23.0 nm and a length in the white line direction of 59.5 nm were observed. In this observation using the PLL-mica substrate, the height of the particles is considered to be the particle size, and as a whole, about one particle having a particle size of about 20 nm was observed in the range of 500 nm × 500 nm.

  9 and 10 show the observation results of the ultrafine bubbles observed using the APTES-mica substrate, each figure (A) shows an observation photograph, and each figure (B) is on the white line in (A). A graph of height is shown. The position of the triangular mark on the white line shown in (A) of each figure corresponds to the position of the triangular mark on the graph of (B). Here, APTES (3-aminopropyl triethyl silane) exposes an amino group on the substrate surface by bonding an ethoxy group to a hydroxyl group on mica. Thereby, a positive charge can be given to the mica surface.

  FIG. 9A and FIG. 10A show observation photographs under conditions where the scanning range is 500 nm. According to FIG. 9 (B), FIG. 9 (A) shows that particles having a height of 15.7 nm and a length in the white line direction of 75.4 nm were observed, and according to FIG. 10 (B). FIG. 10 (A) shows that particles having a height of 8.57 nm and particles having a height of 4.53 nm were observed. In this observation using the APTES-mica substrate, the particle height was considered to be the particle size, and as a whole, a plurality of particles having a particle size of 20 nm or less and different particle sizes were observed in a range of 500 nm × 500 nm.

  From the above observation results, particles having a particle size of several nm to several tens of nm were observed. In these same positively charged substrates, since nanobubbles have been observed in the past, the observed particles are considered to be nanobubbles, and in the sterilization system according to the embodiment of the present invention, at least several nm. It can be seen that the above nanobubbles are generated in seawater.

[Modification of sterilization system]
A shell disinfection system 10 according to an embodiment of the present invention is provided with a circulation path 102 that returns from the storage unit 12 to the storage unit 12 via the fine bubble generation unit 14 and the first ultrasonic crushing unit 16. Yes. In addition to this, there may be provided another circulation path that does not go through the fine bubble generation unit 14 but returns from the storage unit 12 to the storage unit 12 through the first ultrasonic crushing unit 16. It may be possible to switch between the circulation path 102 and the other circulation path for circulating the seawater 30.

  Further, each of the fine bubble generating unit 14 and the first ultrasonic crushing unit 16 may be individually incorporated in a circulation path for circulating the seawater 30 stored in the storage unit 12. At this time, each circulation path may be circulated simultaneously or separately. For example, after circulating the circulation path in which the fine bubble generating part 14 is incorporated and storing the seawater 30 containing the fine bubbles in the storage part 12, the circulation path in which the ultrasonic crushing part 16 is incorporated is circulated. It is also possible to convert the microbubbles contained in the water into ultrafine bubbles and store the seawater 30 containing the ultrafine bubbles in the storage unit 12.

  In the shellfish sterilization system 10 according to the embodiment of the present invention, each of the first and second ultrasonic crushing portions includes a front and rear ultrasonic transducer group, and each ultrasonic transducer group is an ultrasonic crushing field. Is forming. However, the first and second ultrasonic crushing sections may include three or more stages of ultrasonic transducer groups, and each ultrasonic transducer group may form an ultrasonic collapse field. If it does in that way, a virus can be killed reliably by the seawater which passes the 1st and 2nd ultrasonic crushing part passing a some ultrasonic crushing field.

  However, the first ultrasonic crushing section may include a single-stage ultrasonic transducer group, and one ultrasonic transducer group may form an ultrasonic collapse field. By doing so, the structure of the first ultrasonic crushing portion can be simplified. Although the ability to kill viruses is reduced in one ultrasonic transducer group, the ability reduction of the first ultrasonic crushing portion can be compensated by increasing the number of times of circulating seawater.

  In the shellfish sterilization system 10 according to the embodiment of the present invention, when the oysters 32 are submerged in seawater containing ultrafine bubbles, the ultrafine bubbles enter the oysters 32 to selectively adsorb and desorb viruses. By doing so, the virus is discharged from the oysters 32 into the seawater, that is, sterilized. In particular, ultrafine bubbles having a particle size in the range of 20 nm to 70 nm enter the midgut line of oysters and adsorb and desorb viruses.

  Furthermore, in the shellfish sterilization system 10 according to the embodiment of the present invention, the discharged seawater is supplied to the ultrasonic crushing portion, and ultrafine bubbles are generated by the ultrasonic waves, and at the same time, the virus is killed. However, the sterilization system may be composed of another ultrafine bubble generation unit using a method other than ultrasonic waves and an ultraviolet irradiation unit, instead of the ultrasonic crushing unit.

  Moreover, in the shellfish sterilization system and the sterilization method according to the embodiment of the present invention, the amount of seawater uptake of the oysters 32 is greatly improved by physiological activation by bubbles of oxygen gas. As a result, the circulation of seawater sucked and discharged by the oysters 32 is accelerated, and the sterilizing effect of viruses and the like is increased.

  The sterilization cleaning technique as described above in the embodiment of the present invention is referred to as “selective adsorption / desorption cleaning sterilization method”.

Moreover, in the shellfish sterilization method according to the embodiment of the present invention, the following conditions are preferable for the ultrafine bubbles of oxygen gas.
Dissolved oxygen concentration in seawater: 5-20ppm
Bubble particle size: less than 200 nm In particular, in order to more effectively selectively adsorb and desorb and wash norovirus accumulated in the midgut gland, ultrafine bubbles need to reach the gut wall of the midgut gland and Since the same bubble particle size is required, the bubble particle size is more preferably in the range of 20 nm to 70 nm.
Further, if the dissolved oxygen concentration is less than 5 ppm, the shellfish are not activated sufficiently. On the other hand, even if the dissolved oxygen concentration exceeds 20 ppm, the shellfish is not activated.

  In addition to oxygen gas, other gases with high sterilization effect such as ozone gas can be bubbled, but shellfish shows rejection in such gas with high sterilization effect, and the activity of shellfish even at low concentrations The shellfish can even be killed at low concentrations.

  As mentioned above, although the example of the specific aspect of this invention was demonstrated by said embodiment and Example, this invention is not limited to the said embodiment and Example.

DESCRIPTION OF SYMBOLS 10 Sterilization system of shellfish 102 Circulation path 12 Reservoir part 122 Seawater introduction pipe 124 Recursive derivation pipe 126 Seawater exchange pipe 128 Net shelf 14 Fine bubble generation part 142 Swivel part 144 Protrusion crushing part 144a Protrusion 146 Breeding part 148 Foaming part 148a Repressurization Space 148b Decompressed space 16 First ultrasonic crushing portion 162 Passage 164 Exterior body 164a Propagating liquid inlet 164b Propagating liquid outlet 164c Side peripheral member 164d Planar member 166 Intermediate space 168 Ultrasonic transducer 18 First pump 20 Second Ultrasonic crushing part 22 Valve 24 Sea area 26 Second pump 28 Control part 30 Seawater 32 Oyster 32a Midgut 32b String 34 Superfine bubbles 36 Microbubbles 38 Sodium ion 40 Chlorine ion

Claims (7)

Preparing seawater in the reservoir,
Sinking shellfish in the reservoir;
Including oxygen gas bubbles in the seawater stored in the storage unit,
The method for disinfecting shellfish, wherein the bubbles have a diameter of less than 100 nm.   The shellfish disinfection method according to claim 1, wherein the seawater has a dissolved oxygen concentration in a range of 5 ppm to 20 ppm.   The shellfish sterilization method according to claim 1 or 2, wherein the oxygen gas bubbles have a particle diameter of 20 nm to 70 nm.   The shellfish sterilization method according to any one of claims 1 to 3, wherein the shellfish is held in the seawater for a period of 12 hours to 24 hours.   Furthermore, the said bubble is generated by irradiating the said seawater with an ultrasonic wave and being crushed, The sterilization method of shellfish as described in any one of Claims 1-4. A fine bubble generating part for generating fine bubbles of oxygen gas in sea water;
A first ultrasonic crushing portion that crushes the fine bubbles in the seawater and generates ultrafine bubbles;
A reservoir for holding shellfish with seawater containing the ultrafine bubbles,
A shellfish sterilization system, wherein the microbubble generation unit or the first ultrasonic crushing unit is supplied with the seawater from the storage unit. Furthermore, the seawater is supplied from the storage unit, and includes a second ultrasonic crushing unit that irradiates the supplied seawater with ultrasonic waves,
The shellfish sterilization system according to claim 6, wherein the seawater is discharged to the outside from the storage unit through the second ultrasonic crushing unit.