JP7054104B2 - pH adjustment method and aquaculture method - Google Patents

Description

The present invention relates to a pH adjusting method and aquaculture method used for aquaculture of oysters and the like.

Conventionally, a device for cultivating shellfish and fish in a water tank (pool) into which seawater has been introduced has been known. For example, in oyster farming, it is common practice to immerse oysters in a water tank for a predetermined period of time and let the oysters discharge waste called fake feces to remove the odor.

Japanese Unexamined Patent Publication No. 2016-22480 Japanese Unexamined Patent Publication No. 2006-166894

By the way, it is desirable that the pH (hydrogen ion index) of the seawater in the aquarium is weakly alkaline. This is because if the acidity of seawater becomes too high, the growth of oysters may stop or the shells may melt. However, the pH of seawater introduced into the aquarium generally varies from season to season. In addition, the pH in the aquarium may change to the acidic side due to respiration of oysters or the like in the aquarium or excrement such as fake feces. Therefore, a device capable of maintaining the pH of seawater in the aquarium to be weakly alkaline is desired.

Patent Document 1 describes an apparatus that adjusts pH by injecting an alkaline substance such as sodium hydroxide into raw water. However, the use of alkaline substances may cause bias in seawater components and the resulting poor growth of shellfish and fish. Therefore, pH adjustment by injecting an alkaline substance is not suitable for aquaculture.

In Patent Document 2, acidic seawater and alkaline seawater are generated by electrolysis, and after aerating the acidic seawater to raise the pH, the pH is adjusted to maintain the seawater alkaline by mixing with the alkaline seawater. The device that performs the above is described. However, this device requires equipment for electrolysis and aeration, which requires very large-scale equipment.

Therefore, it is an object of the present invention to provide a small pH adjusting method and aquaculture method which are suitable for aquaculture and can maintain the pH of seawater to be weakly alkaline.

The present invention is a pH adjusting method for adjusting the pH of seawater in a water tank for the purpose of solving the above problems, in which a flow path through which seawater is circulated and discharged into the water tank and the flow path are circulated. Provided is a pH adjusting method comprising a light source for irradiating seawater with ultraviolet light having a wavelength of 250 nm or more and 350 nm or less, and raising the pH of the seawater by irradiating the seawater flowing through the flow path with ultraviolet rays from the light source. do.

Further, the present invention is a aquaculture method for cultivating the shellfish or fish while adjusting the pH of the seawater in the aquarium for storing the seawater and accommodating the shellfish or fish to be cultivated for the purpose of solving the above-mentioned problems. A flow path through which seawater is circulated and discharged to the water tank, and a light source for irradiating the seawater flowing through the flow path with ultraviolet light having a wavelength of 250 nm or more and 350 nm or less are provided, and the flow path is circulated from the light source. Provided is a culture method for raising the pH of seawater by irradiating the seawater with ultraviolet rays .

According to the present invention, it is possible to provide a small pH adjusting method and aquaculture method suitable for aquaculture and capable of maintaining the pH of seawater in a weak alkaline state.

It is a schematic block diagram of the culture apparatus using the pH adjustment apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the pH adjustment apparatus. (A) is a graph showing the spectral distribution of the light emitting diode used as a light source, and (b) is a graph showing the relationship between the temperature of the light emitting diode and the emission wavelength. It is explanatory drawing which shows the measurement point of the change of pH of underground seawater and the change of pH of seawater in aquarium.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Overall configuration of aquaculture equipment)
FIG. 1 is a schematic configuration diagram of an aquaculture device using the pH adjusting device according to the present embodiment. As shown in FIG. 1, the aquaculture device 100 includes a water tank (pool) 101 and a pH adjusting device 1.

Seawater W is stored in the aquarium 101, and shellfish or fish (not shown) to be cultivated are stored in the aquarium 101. In the present embodiment, the case where the aquaculture device 100 is used for aquaculture of oysters will be described. An oyster basket containing oysters is immersed in the seawater W stored in the water tank 101.

The water tank 101 is provided with an intake channel 110 for allowing underground seawater to flow into the water tank. The intake channel 110 is provided with an intake pump 111 for pumping underground seawater.

(Explanation of pH adjusting device 1)
FIG. 2 is a cross-sectional view showing the pH adjusting device 1 according to the present embodiment.

The pH adjusting device 1 adjusts the pH (hydrogen ion concentration) of the seawater W, and is mounted on, for example, a rack provided in the vicinity of the water tank 101 for storing the seawater W. The pH adjusting device 1 includes a flow path 2 through which the seawater W flows and discharges to the water tank 101, and a light source 3 for irradiating the seawater W flowing through the flow path 2 with ultraviolet light.

The flow path 2 has an inflow pipe 21 into which the seawater W flows in, a discharge pipe 22 in which the seawater W is discharged, and a straight pipe 23 in which the inflow pipe 21 and the discharge pipe 22 communicate with each other and extend linearly. .. The end of the inflow pipe 21 opposite to the straight pipe 23 is immersed in the seawater W in the water tank 101, and the seawater W in the water tank 101 is sucked up from the end. The seawater W discharged from the end of the discharge pipe 22 opposite to the straight pipe 23 is returned to the water tank 101.

Both ends of the straight pipe 23 are inserted into the first housing 41 and the second housing 42, respectively. Hereinafter, the axial direction of the straight pipe 23 is simply referred to as an axial direction. The first housing 41 and the second housing 42 are formed in a substantially rectangular parallelepiped shape, and also play a role of fixing the pH adjusting device 1 to a predetermined installation position such as a rack.

The first housing 41 is connected to a first straight pipe insertion hole 41a that opens in one of the axial directions and into which the end of the straight pipe 23 is inserted, and an inflow pipe 21 that opens in the direction perpendicular to the axial direction. A first connection hole 41b and a first rectifying chamber 41c that communicate the first straight pipe insertion hole 41a and the first connection hole 41b are formed. One end of the straight pipe 23 is arranged so as to project into the first rectifying chamber 41c.

In the second housing 42, a second straight pipe insertion hole 42a that opens to the other side in the axial direction and into which the end of the straight pipe 23 is inserted, and a discharge pipe 22 that opens in the direction perpendicular to the axial direction are connected. A second connecting hole 42b and a second rectifying chamber 42c communicating the second straight pipe insertion hole 42a and the second connecting hole 42b are formed. The straight pipe 23 is arranged so that the other end thereof protrudes into the second rectifying chamber 42c.

The straight tube insertion holes 41a and 42a and the connection holes 41b and 42b extend in directions orthogonal to each other. That is, the straight pipe 23 inserted into the straight pipe insertion holes 41a and 42a and the inflow pipe 21 or the discharge pipe 22 inserted into the connection holes 41b and 42b extend in directions orthogonal to each other. In the present embodiment, the inflow pipe 21 and the discharge pipe 22 are provided so as to extend downward in the vertical direction (upper side in FIG. 2). Although the first housing 41 and the inflow pipe 21 and the second housing 42 and the discharge pipe 22 are shown integrally in FIG. 2, they may be separate bodies. Further, a part of the inflow pipe 21 and the discharge pipe 22 may be integrally formed with the housings 41 and 42.

Seawater W flows into the inflow pipe 21 from one end thereof, and the other end is connected to the first connection hole 41b of the first housing 41. That is, the other end of the inflow pipe 21 communicates with one end of the straight pipe 23 via the first housing 41. The seawater W flowing from the inflow pipe 21 is introduced into the straight pipe 23 through the first rectifying chamber 41c.

One end of the discharge pipe 22 is connected to the second connection hole 42b of the second housing 42, and the seawater W is discharged to the water tank 101 from the other end. One end of the discharge pipe 22 communicates with the other end of the straight pipe 23 via the second housing 42. The seawater W that has passed through the straight pipe 23 is introduced into the discharge pipe 22 through the second rectifying chamber 42c, and is discharged from the other end of the discharge pipe 22 to the water tank or the like. The inflow pipe 21 is provided with a pump 24 for inflowing and discharging seawater W.

As the straight tube 23, it is preferable to use a straight tube 23 whose inner peripheral surface 23a is made of a material that reflects ultraviolet light from the light source 3. Examples of the material that reflects the ultraviolet light from the light source 3 include polytetrafluoroethylene (PTFE), which has a high reflectance of ultraviolet light and is excellent in durability, heat resistance, and chemical resistance. In this embodiment, a straight pipe 23 made of PTFE and having an inner diameter of about 40 mm was used.

In the second housing 42, a window member 31 is provided so as to partition the second rectifying chamber 42c in the axial direction. The space partitioned by providing the window member 31 is referred to as a light source accommodating space 41d. A light source 3 is provided in the light source accommodating space 41d so as to face the downstream end of the straight tube 23 via the window member 31. That is, in the running water sterilizer 1, the light source 3 is provided on the downstream side (discharge pipe 22 side) of the straight pipe 23, and irradiates ultraviolet light in the axial direction of the straight pipe 23. As the window member 31, it is preferable to use a window member 31 having a high transmittance of ultraviolet light. For example, a window member 31 made of quartz glass (SiO ₂ ), sapphire glass (Al ₂ O ₃ ), an amorphous fluororesin, or the like is used. Can be used. Although not shown, the light source accommodating space 41d accommodates a circuit board on which the light source 3 is mounted.

Further, although not shown in FIG. 1, a connector portion is provided in the second housing 42, and a cable extending from an external power supply device is electrically connected to the circuit board via the connector portion. Has been done. Further, it is desirable that the second housing 42 is provided with a cooling means for cooling the light source 3. As the cooling means, a water-cooled cooling device using seawater W or the like as cooling water, or an air-cooled cooling device having a fan or the like can be used.

Further, in the first housing 41, a plate-shaped reflector 32 that reflects ultraviolet light is provided along the inner wall facing the upstream end of the straight pipe 23 of the first rectifying chamber 41c. That is, in the present embodiment, the reflector 32 is provided on the upstream side (inflow pipe 21 side) of the straight pipe 23 so as to face the light source 3. The reflector 32 enhances the irradiation efficiency of the ultraviolet light by reflecting the ultraviolet light emitted from the light source 3 and propagating inside the straight tube 23 to the downstream side. The reflector 32 may have a flat reflecting surface, or may have a reflecting surface having a curved surface such as a concave curved surface. As the reflector 32, for example, a reflector obtained by depositing aluminum on aluminum as a base material and further depositing an oxide film layer can be used.

In the pH adjusting device 1, the ultraviolet light emitted from the light source 3 passes through the window member 31, is reflected by the inner peripheral surface 23a of the straight tube 23, and propagates in the axial direction of the straight tube 23. The ultraviolet light that has passed through the straight tube 23 is reflected by the reflector 32 and propagates in the straight tube 23 again in the axial direction. In the pH adjusting device 1, the pH of the seawater W flowing through the straight tube 23 is adjusted by the ultraviolet light propagating in the straight tube 23 in the axial direction. In addition, since ultraviolet rays have a sterilizing ability, seawater W is also sterilized at the same time.

(Explanation of configuration for adjusting pH)
In the present embodiment, a light emitting diode 3a that irradiates ultraviolet rays is used as the light source 3, and the pH of the seawater W is raised by irradiating the seawater W flowing through the flow path 2 from the light source 3 with ultraviolet rays. The seawater W is kept weakly alkaline.

Here, 19 light emitting diodes 3a are used as the light source 3, but the number of light emitting diodes 3a used as the light source 3 is not limited to this. Note that FIG. 2 shows only one light emitting diode 3a for the sake of simplification of the figure. The drive circuit of the light emitting diode 3a is provided outside the second housing 42. In this embodiment, a drive circuit is mounted in an external power supply device.

The light distribution angle of the light source 3 is preferably 30 degrees or less. As a result, the incident angle of the ultraviolet light on the inner peripheral surface 23a of the straight tube 23 is set to 75 degrees or more, the reflectance on the inner peripheral surface 23a of the straight tube 23 is increased, and the irradiation efficiency to the seawater W can be improved. .. The light source 3 may include a member such as a concave mirror for adjusting the light distribution angle of the light emitted from the light emitting diode 3a.

As the light emitting diode 3a used for the light source 3, it is preferable to use a diode that irradiates ultraviolet light having a wavelength of 250 nm or more and 350 nm or less. That is, it is desirable to use a light emitting diode 3a whose center wavelength or peak wavelength is included in the range of 250 nm or more and 350 nm or less. When it is desired to obtain a sufficient sterilizing effect at the same time as adjusting the pH, it is preferable to use a light emitting diode 3a that irradiates ultraviolet light having a wavelength of 255 nm or more and 285 nm or less, which has a high sterilizing effect. Further, in order to suppress the occurrence of fouling on the inner peripheral surface 23a of the window member 31 or the straight tube 23, as the light emitting diode 3a, the emitted light is infrared light or light having a wavelength of 200 nm or less having a large oxidizing power. It is advisable to use one that does not contain.

The mechanism by which the pH of seawater W rises due to irradiation with ultraviolet rays is currently unknown and is under investigation. However, when the present inventors investigated the pH of the seawater W for several months, it was confirmed that the seawater W in the water tank 101 could be maintained to be weakly alkaline by using the pH adjusting device 1. The pH of the underground seawater introduced into the water tank 101 fluctuates, and the pH tends to be acidic due to the breathing of oysters in the water tank 101. It is kept weakly alkaline, and it is considered certain that the pH adjusting device 1 keeps the seawater W weakly alkaline.

FIG. 3A is a graph showing the spectral distribution of the light emitting diode 3a used for the light source 3 in the present embodiment, and FIG. 3B is a graph showing the relationship between the temperature of the light emitting diode 3a and the emission wavelength. It is a figure. Note that FIG. 3A shows the spectral distribution in an environment of 25 ° C.

As shown in FIGS. 3A and 3B, the light emitting diode 3a used as the light source 3 in the present embodiment has a peak wavelength of 285 nm in an environment of 25 ° C. Further, the light emitting diode 3a does not include infrared light or light having a wavelength of 200 nm or less in the light to be irradiated. As the light emitting diode 3a, a diode using aluminum gallium nitride (AlGaN) for the light emitting layer (active layer) was used.

In order to confirm the effect of the pH adjusting device 1, as shown in FIG. 4, the underground seawater is introduced into the first water tank 101a, the underground seawater in the first water tank 101a is introduced into the pH adjusting device 1, and the pH adjusting device 1 is used. The seawater W that passed through the above water tank 101b was discharged to the second water tank 101b, and the pH of the underground seawater in the first water tank 101a and the pH of the seawater W in the second water tank 101b that passed through the pH adjusting device 1 were measured. The results are shown in Table 1.

As shown in Table 1, the seawater W after passing through the pH adjusting device 1 is higher than the pH of the underground seawater, and it can be seen that the pH is increased by using the pH adjusting device 1. Further, the seawater W after passing through the pH adjusting device 1 maintains a weak alkalinity having a pH of 7.68 or more and 7.89 or less. Although not shown, the same result is obtained when the pH of the seawater W in the water tank 101 is measured while continuing the oyster farming work in the water tank 101 in the culture device 100 of FIG. Normally, the pH tends to become acidic due to the breathing of oysters or the like, but by using the pH adjusting device 1, the pH of the seawater W in the water tank 101 can be maintained to be weakly alkaline. Further, seawater (underground seawater to be introduced) usually tends to be acidic in summer, but the present inventors can use the pH adjusting device 1 even in summer when such seawater tends to be acidic. It has been confirmed that the pH of the seawater W in the water tank 101 can be maintained to be weakly alkaline.

(Actions and effects of embodiments)
As described above, in the pH adjusting device 1 according to the present embodiment, the flow path 2 that circulates the seawater W and discharges it to the water tank 101, and the light source 3 that irradiates the seawater W flowing through the flow path 2 with ultraviolet light. , And the pH of the seawater W is raised by irradiating the seawater W flowing through the flow path 2 with ultraviolet rays from the light source 3.

As a result, it is possible to prevent the seawater W from leaning toward acidity unsuitable for aquaculture due to pH fluctuations in underground seawater or pH fluctuations due to respiration of oysters, and the seawater W is maintained at a weak acidity to create an environment suitable for aquaculture. It will be possible to realize. Further, the pH adjusting device 1 does not require a large-scale equipment for performing electrolysis and aeration as in the prior art, and is very small. Therefore, it can be easily added to the existing aquaculture apparatus 100. As described above, according to the present embodiment, it is possible to realize a compact pH adjusting device 1 which is suitable for aquaculture and can maintain the pH of seawater W in a weak alkaline state.

Further, since the pH adjusting device 1 uses ultraviolet rays, it is possible to sterilize the seawater W at the same time as adjusting the pH of the seawater W. That is, by using this pH adjusting device 1, it is possible to simultaneously realize the pH adjusting and sterilizing of seawater W, and it is possible to keep the equipment cost low as compared with the case where each device is provided separately. It is possible.

(Summary of embodiments)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals and the like in the embodiment. However, the respective reference numerals and the like in the following description are not limited to the members and the like in which the components within the scope of the claims are specifically shown in the embodiment.

[1] A pH adjusting device (1) attached to a water tank (101) for storing seawater (W) and adjusting the pH of the seawater (W) in the water tank (101), and distributes the seawater (W). A flow path (2) discharged to the water tank (101) and a light source (3) for irradiating the seawater (W) flowing through the flow path (2) with ultraviolet light are provided from the light source (3). A pH adjusting device (1) that raises the pH of seawater (W) by irradiating the seawater (W) flowing through the flow path (2) with ultraviolet rays.

[2] The pH adjusting device (1) according to [1], wherein the light source (3) irradiates ultraviolet light having a wavelength of 250 nm or more and 350 nm or less.

[3] The flow path (2) has a straight pipe (23) extending linearly, and the light source (3) is provided at the end of the straight pipe (23), and the straight pipe (23) is provided. The pH adjusting device (1) according to [1] or [2], which irradiates ultraviolet light in the axial direction of the above.

[4] An aquarium (101) for storing seawater (W) and accommodating shellfish or fish to be cultivated, and a pH adjusting device (1) according to any one of [1] to [3]. Aquaculture device (100) provided.

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

The present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, the light source 3 is provided at the downstream end of the straight pipe 23, but the light source 3 may be provided at the upstream end of the straight pipe 23, or the upstream end of the straight pipe 23 may be provided. The light source 3 may be provided at both the downstream end and the downstream end.

Further, when it is sufficient to deal only with the pH fluctuation of the underground seawater, the pH adjusting device 1 may be provided in the intake channel 110. In this case, the intake channel 1 plays the role of the flow path 2.

1 ... pH adjusting device 2 ... Flow path 21 ... Inflow pipe 22 ... Discharge pipe 23 ... Straight pipe 3 ... Light source 3a ... Light emitting diode 31 ... Window member 32 ... Reflector 100 ... Aquaculture device 101 ... Water tank W ... Seawater

Claims (3)

It is a pH adjustment method that adjusts the pH of seawater in the aquarium.
A flow path that circulates seawater and discharges it to the aquarium,
The seawater flowing through the flow path is provided with a light source for irradiating the seawater flowing through the flow path with ultraviolet light having a peak wavelength of 285 nm in an environment of 25 ° C.
By irradiating the seawater flowing through the flow path with ultraviolet rays from the light source, the pH of the seawater is raised to 7.68 or more and 7.89 or less .
pH adjustment method. The flow path has a straight pipe extending linearly and has a straight pipe.
The light source is provided at the end of the straight tube and irradiates ultraviolet light in the axial direction of the straight tube.
The pH adjusting method according to claim 1 . A aquaculture method for cultivating the shellfish or fish while adjusting the pH of the seawater in the aquarium that stores the seawater and accommodates the shellfish or fish to be cultivated.
A flow path that circulates seawater and discharges it to the aquarium,
The seawater flowing through the flow path is provided with a light source for irradiating the seawater flowing through the flow path with ultraviolet light having a peak wavelength of 285 nm in an environment of 25 ° C.
By irradiating the seawater flowing through the flow path with ultraviolet rays from the light source, the pH of the seawater is raised to 7.68 or more and 7.89 or less .
Aquaculture method.

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