JP2000119114A - Disinfection of plant raising solution and disinfection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disinfection system designed to efficiently kill harmful microorganisms or the like contaminating a plant raising solution with ozone gas. SOLUTION: This disinfection system works as follows: a fertilizer component-contg. solution returned from raising beds is first subjected to temperature rise to 20-28 deg.C in a recovery tank 1; the resulting solution and ozone gas afforded by an ozonizer 38 are mixed together in an ozone mixer 8 and then brought into a bubble disperse unit 17 where the mixture is made into a solution dispersed with ozone microbubbles, and the solution is subsequently agitated in a gas-liquid contact unit 18 to effect killing microorganisms or the like in the solution by the aid of gas-liquid contact; the resulting solution thus disinfected is allowed to flow, via a gas-liquid separation unit 21, into a fertilizer component replenishing tank 26 where the solution is regulated with fertilizer components and then fed, through a discharge pump 33, to the raising beds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for disinfecting a cultivating solution circulated in a hydroponic bed for plants.

[0002]

2. Description of the Related Art Conventionally, a so-called hydroponic method for cultivating plants such as vegetables efficiently by circulating a solution containing a fertilizer component through a cultivation bed has been widely used. In addition to the three main components of nitrogen, phosphoric acid and potassium, the solution used is calcium,
Mineral components such as magnesium and iron and other components essential for plants are contained in desired ratios. However, when the solution is circulated in this manner, various pathogens increase in the solution, and the disease causes the plants to grow poorly or die. In order to prevent such adverse effects on plants, it is effective to sterilize the circulating solution.

[0003] On the other hand, an ozone sterilization method utilizing the strong oxidizing power of ozone is conventionally known as a simple sterilization method. The conventional ozone sterilization method uses an ozone generator that converts oxygen into ozone by discharging a high voltage to air, and converts the air containing generated ozone (hereinafter, such air containing ozone is referred to as ozone gas) into a processing solution. To be sterilized. When sterilizing with ozone in a dissolved state, the sterilizing power is relatively low.
It is necessary to increase the ozone concentration in the solution by using a high concentration ozone gas of 000 ppm or more. At that time, in order to dissolve as much ozone gas as possible in water, it is important to maintain the water temperature at a considerably low (usually 10 ° C. or lower) state.

[0004]

However, when high-concentration ozone gas is used as described above, a large amount of ozone gas is diffused into the greenhouse, for example, when a sterilizer is installed in the greenhouse for cultivation, and the leaves of the plant are oxidized. Or cause adverse effects on workers. Also, large amounts of ozone components tend to remain in the solution after sterilization, which may cause oxidative damage to plant roots. In addition, since an ozone generator having a high concentration or a large capacity is required, there is a problem that the cost is increased. Accordingly, an object of the present invention is to provide a method and an apparatus for disinfecting a solution for plant cultivation that solve such problems.

[0005]

According to a first aspect of the present invention, there is provided a method of sterilizing a solution for plant cultivation, wherein ozone gas is suctioned from a negative pressure side of the solution using a pump. By dissolving it in a solution under pressure, and then reducing the solution to atmospheric pressure, the dissolved ozone is converted into fine ozone bubbles in the solution and dispersed and mixed,
A method for sterilizing a plant cultivation solution, which comprises sterilizing microorganisms in the solution by gas-liquid contact.

In the above sterilization method, gaseous ozone is dissolved in a solution by pressure, and then the pressure is reduced to convert dissolved ozone into fine bubbles. As a result, a large number of fine ozone dispersed and mixed in the solution are obtained. Ozone bubbles and microorganisms in the solution can come into contact at the gas-liquid boundary. According to experiments, it has been found that the ozone sterilization efficiency at such a gas-liquid contact portion is higher than the sterilization efficiency in a conventional liquid, and rapid sterilization can be performed even with bubbles having a relatively low ozone concentration. Therefore, the concentration of ozone released into the greenhouse and the concentration of ozone contained in the solution after sterilization can be extremely low, so that oxidation damage to the leaves and roots of the plant can be avoided. In addition, since the ozone concentration in the ozone bubbles can be reduced, alteration of active ingredients such as fertilizers can be suppressed. Further, the capacity of the ozone generator can be reduced.

The invention according to claim 2 is a preferred embodiment of the sterilization method according to claim 1, wherein the ozone concentration in the ozone gas is set to 600 ppm or less. By maintaining the ozone concentration in such a range, according to the experiment, it is possible to more stably and reliably avoid the oxidative damage to the leaves and roots of the plant and perform the bactericidal action, and furthermore, to alter the active ingredients such as fertilizers. Can be suppressed more reliably. The invention according to claim 3 is a preferable embodiment of the sterilization method according to claim 1 or 2, wherein sterilization is performed after removing solid solids present in the solution with a filter device. It is characterized by the following.
Since the fungi in the solid mass are hardly ozone-sterilized, the removal of the fungi makes it possible to extremely reduce the residual fungi after the sterilization even if solids such as dust in the air are mixed in the solution. The invention according to claim 4 which solves the above-mentioned problem is a method of sterilizing by maintaining ozone at a temperature that does not substantially dissolve it. According to the present invention, the property that gaseous ozone hardly dissolves in water as the solution temperature rises is utilized, and the dissolved ozone can be efficiently converted into fine bubbles.

According to a fifth aspect of the present invention, there is provided an apparatus for sterilizing a solution for plant cultivation, comprising: a collection tank for collecting a solution from a plant cultivation floor; and a solution in the collection tank. Temperature adjusting means for adjusting the temperature, an ozone generator,
An ozone gas mixing device that mixes ozone gas from an ozone generator into the solution in the recovery tank to disperse fine ozone bubbles in the solution, and an ozone bubble from the ozone gas mixing device is provided at an outlet side for bringing the solution into gas-liquid contact with the solution. And a gas-liquid contact portion. The sterilization apparatus can adjust the solution in the collection tank to a temperature at which ozone is not substantially dissolved, and further mixes the temperature-adjusted solution with the ozone gas from the ozone generator using an ozone gas mixing device. By dispersing the fine ozone bubbles in the solution, the bacteria in the solution can be sufficiently contacted with the ozone at the gas-liquid contact portion. Therefore, the concentration of ozone released into the greenhouse and the concentration of ozone contained in the solution after sterilization can be extremely reduced, so that oxidation damage to the leaves and roots of the plant can be avoided. Further, the capacity of the ozone generator can be reduced.

The invention according to claim 6 is a preferred embodiment of the sterilization apparatus according to claim 5, wherein a fertilizer component supply tank is provided on the outlet side of the gas-liquid contact portion, and the fertilizer component supply tank is provided. It is characterized in that it is designed to replenish the insufficient fertilizer components. By providing such a fertilizer component replenishing tank, a solution having a desired fertilizer component concentration can always be supplied to the plant cultivation floor.

[0010]

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 are process flow diagrams showing an example of a sterilization apparatus for performing the sterilization method of the present invention. First, in FIG. 1, a pipe 2 for returning a solution from a plant cultivation bed (not shown) and a pipe 3 for replenishing insufficient water are connected to a recovery tank 1. In the recovery tank 1, the solution temperature is set to a temperature at which ozone is not substantially dissolved, for example, 20 to 2
A temperature adjusting means 40 for adjusting the temperature to 8 ° C., preferably 25 to 28 ° C. is provided. The temperature adjusting means 40 includes a heat exchanging section 4 composed of a coiled pipe, a temperature detecting section 5 for detecting a solution temperature, and a temperature controller (not shown). In the recovery tank 1, an upper limit level detector 6 for detecting the upper limit of the solution level and a lower limit level detector 7 for detecting the lower limit of the solution level are attached.

A pipe 9 communicating with an ozone gas mixing device 8 such as a gas mixing type cascade pump is connected to a lower portion of the recovery tank 1, and a solid content existing in a solution of the pipe 9 is removed.
For example, a filter device 10 such as a wind cartridge filter for removing solids having a particle diameter of 10 μm or more, an on-off valve 11 and a compound meter 12 for detecting the solution pressure on the suction side of the ozone gas mixing device 8 are provided. Further, a pipe 13 for sucking ozone gas from an ozone generator described later is connected to the ozone gas mixing device 8, and the pipe 13 is provided with a solenoid valve 14 for preventing backflow. It should be noted that a check valve may be used instead of the solenoid valve 14.

An on-off valve 1 is provided on the outlet side of the ozone gas mixing device 8.
5 and a pressure gauge 15a are provided, and a cylindrical bubble dispersing portion 17 having an enlarged diameter is connected to a secondary side of the on-off valve 15 via a tapered portion 16, and a downstream side of the bubble dispersing portion 17 is connected thereto. A cylindrical gas-liquid contact portion 18 having the same diameter is connected. The bubble dispersing portion 17 has an action of rapidly reducing the pressure of the solution discharged from the ozone gas mixing device 8 to sufficiently disperse a large number of fine ozone bubbles in the solution. Gas-liquid contact part 1
For example, a passing type mixing mixer is used as 8.
The pass-type mixing mixer used publicly here is a so-called static mixer, in which a left-handed spiral and a right-handed spiral are alternately mounted along the longitudinal direction in a cylindrical main body, and the solution passes therethrough. During this time, a turbulent flow occurs due to the spiral, and a large number of dispersed fine ozone bubbles are agitated with the solution so as to be in sufficient gas-liquid contact. Further, a drain pipe 19 is connected to the tapered portion 16, and an on-off valve 20 is provided in the drain pipe 19.

Downstream of the gas-liquid contact portion 18, a cylindrical gas-liquid separation portion 21 having the same diameter as the gas-liquid contact portion 18 is connected. Gas-liquid separation unit 21
Is connected to a liquid outlet 23 having an inclined plate 22 therein, and an upper portion is provided with a gas filter 24 containing activated carbon.
May be connected. Then, the ozone gas slightly present in the gas is released after being adsorbed and removed by the gas filter unit 24. Note that the inclined plate 22 in the liquid outlet 23 has a function of returning fine air bubbles mixed into the gas-liquid separator 21.
The downstream side of the liquid outlet 23 is connected to a fertilizer component supply tank 26 via a connection pipe 25. A fertilizer component replenishing unit 27 having a control device is provided in the fertilizer component replenishment tank 26, and a conductivity meter (EC sensor) 28 that detects a change in fertilizer concentration as a change in electric conductivity is installed in the fertilizer component replenishment tank 26. Is done.

Two fertilizer component supply pipes 29 and 30 are connected to the upper part of the fertilizer component supply tank 26,
The electromagnetic valves (not shown) provided in the respective pipes are controlled to open and close based on the control command from, and different fertilizer components are appropriately supplied into the fertilizer component supply tank 26 at a predetermined ratio. In addition,
By connecting three or more fertilizer component supply pipes, more kinds of fertilizer can be supplied. Further, the fertilizer component replenishment tank 26 is provided with an upper limit level detector 31 for detecting the upper limit of the solution level and a lower limit level detector 32 for detecting the lower limit of the solution level. A pipe 33a provided with a discharge pump 33 is connected to a lower part of the fertilizer component supply tank 26 in order to supply a sterilized solution to a cultivation bed of a plant (not shown). It is preferable that the ozone gas mixing device 8 uses a material such as stainless steel having good corrosion resistance for the liquid contact portion in order to prevent corrosion such as metal elution, and other devices through which the solution including the pipe 9 flows are used. It can be made of resin such as vinyl chloride resin.

FIG. 2 shows the ozone generator 28 connected to the ozone gas mixing device 8 in detail. The opening / closing valve 3 is provided at the inlet side of a gas drying device 34 filled with silica gel or the like.
A pipe 36 that opens to the atmosphere is connected through the pipe 5, and an ozone generator 38 is connected to the outlet side through a pipe 37.
Air containing a predetermined concentration of ozone gas is supplied from the outlet side of the ozone generator 38 to the ozone gas mixing device 8 via the pipe 13. In addition, it is preferable to use, for example, a silicon tube for piping through which ozone gas flows, from the viewpoint of corrosion resistance and simplicity.

Next, a method for sterilizing a plant cultivation solution using the above apparatus will be described. First, the solution containing the fertilizer component from the plant cultivation bed is returned to the collection tank 1 by the pipe 2.
When the solution level falls below the lower limit level, the operation is stopped by a signal from the lower limit level detector 7. When the amount of the solution returned from the pipe 2 into the recovery tank 1 is small, the pipe 3
Supplies fresh water into the recovery tank 1 from the tank. As described above, the solution in the recovery tank 1 is set to 20
Adjusted to the range of ~ 28 ° C. For example, if the set temperature is 2
When the temperature is 5 ° C., when the temperature of the solution falls below 25 ° C., the heat source (not shown) to the heat exchange unit 4 is returned to a set value by a temperature controller (not shown) according to a signal from the temperature detecting unit 5 for detecting the temperature. For example, the amount of heating steam) is increased. Conversely, when the solution temperature rises above 25 ° C., control is performed to reduce the amount of the heating source. Further, the temperature of the solution is 28 ° C.
If the temperature exceeds the limit, the plant may be adversely affected. Therefore, cooling water or the like is supplied to the heat exchange unit 4 so that the temperature is controlled so as to quickly return to the safe area.

The temperature of the solution is set to an optimum value in consideration of the balance between the solubility of ozone in the solution and the energy cost required for heating. By the way, ozone gas concentration is 600p
The calculated ozone concentration in saturated water at pm is 1
0.45 mg / l at 5 ° C., 20 ° C. and 28 ° C.
0.37 mg / l and 0.31 mg / l. The higher the temperature, the lower the solubility, and more ozone can be used for sterilization in the state of microbubbles.

The ozone generator 38 and the ozone gas mixing device 8 are started by a signal for starting the solution feeding. Then, the solution in the recovery tank 1 is sucked into the ozone gas mixing device 8 via the pipe 9, and the line of the pipe 13 becomes negative pressure, and the air in the atmosphere is sucked from the pipe 36 and the gas drying device 3
At 4, a part of the air is converted to ozone while passing through the ozone generator 38. This ozone gas is sucked into the ozone gas mixing device 8 and mixed with the solution, then discharged from the outlet side, and the pressure is rapidly reduced in the bubble dispersing portion 17 to cause fine ozone bubbles, for example, 20 to 80 μm.
It is dispersed in the solution as a number of ozone bubbles having a particle size of about m. When the solution level in the recovery tank 1 has dropped to the position of the lower limit level detector 7, the signal stops the ozone generator 38 and the ozone gas mixer 8 and closes the backflow prevention electromagnetic valve 14. This solenoid valve 14
Closing prevents the solution from flowing back to the ozone generator 38 side by the outlet side head of the ozone gas mixing device 8.

In the ozone gas mixing device 8, for example, 4K
The solution and the ozone gas are mixed at a pressure of about g / cm ² G, and the pressure is monitored while monitoring the pressure gauge 15a.
5 is adjusted. The amount of solution sucked into the ozone gas mixing device 8 is set by adjusting the on-off valve 11 while monitoring the pressure of the compound meter 12, and the amount of ozone gas sucked into the ozone gas mixing device 8 is adjusted by adjusting the on-off valve 35. Is set by Further, the concentration of the ozone gas is set by a concentration adjusting section (not shown) of the ozone generator 38. The solution in the bubble dispersing section 17 in which a large number of fine ozone bubbles are dispersed then enters the gas-liquid contact section 18, where the bacteria in the solution and the ozone bubbles are sufficiently contacted, and an efficient sterilization operation is performed. Then, the sterilized solution flows into the gas-liquid separation unit 21 together with the remaining ozone bubbles, where the gas component and the liquid component are separated, and the gas component is adsorbed and removed by the gas filter unit 24 and released. The liquid component, that is, the solution, flows into the fertilizer component supply tank 26 via the liquid outlet 23 and the connection pipe 25. The slight bubbles remaining while the solution passes through the liquid outlet 23 are:
It is returned to the gas-liquid separation unit 21 by the inclined plate 22.

FIG. 3 is a view showing a state in which the bubble dispersing section 17 is connected to the gas-liquid contact section 18.
FIG. 4 is a diagram schematically showing a state of ozone bubbles in a solution reaching a gas separation unit 21 through the above. As is apparent from the figure, a number of fine ozone bubbles are uniformly dispersed in the solution in the bubble dispersing portion 17 and are stirred while passing through the gas-liquid contact portion 18 to gradually sterilize the microorganisms while disinfecting microorganisms. Is consumed, the bubble diameter decreases, and the apparent number of bubbles also decreases. The ozone bubbles remaining in the solution flowing out of the gas-liquid contact section 18 are separated by the gas separating section 21, and the ozone bubbles slightly remaining in the solution flowing out of the liquid outlet section 23 are captured by the inclined plate 22. It is returned to the gas separation unit 21 while rising. The concentration of the fertilizer in the solution flowing into the fertilizer component replenishing tank 26 is measured by a conductivity meter 28. If the concentration drops below a desired value, a fertilizer replenishment command is issued from the fertilizer component replenishment unit 27 and the fertilizer component supply is performed. Fertilizer components are supplied from the pipes 29 and 30 into the fertilizer component supply tank 26.

When the liquid level in the fertilizer component replenishing tank 26 rises to the position of the upper limit level detecting section 31, the discharge pump 3
3 is activated and the sterilized solution is supplied to the plant growing bed. In addition, you may send a solution to a storage tank and supply it to each cultivation bed suitably from there. When the liquid level in the fertilizer component replenishing tank 26 drops to the position of the lower limit level detection unit 32 by performing the discharging operation, the discharging pump 33 is stopped. Hereinafter, the discharge pump 33 is repeatedly started and stopped by the same control command. The operation of each of the above-described devices can be centrally performed by control means such as a computer and a sequencer (not shown). Further, the fertilizer component supply tank 26 may be omitted, and the connection pipe 25 may be directly connected to the cultivation bed liquid supply pipe. In this case, the ozone gas mixing device 8 which is also a pump doubles as a liquid supply pump.

[0022]

Next, embodiments of the present invention will be described. The solution for plant cultivation was sterilized using the apparatus of FIG. Pseudomos sol in the solution contains the tomato bacterial wilt pathogen Pseudomos sol.
anacearum (bacteria) and Fusarium oxysorum race J3
(Filamentous fungus) was used. In the case of bacteria, the initial concentration in the solution was about 211,000 in 1 ml, and in the case of filamentous fungi, the initial concentration in the solution was about 6,400 in 1 ml. The temperature of the solution in the recovery tank 1 was set to 25 ° C., and the solution sucked into the ozone gas mixing device 8 was supplied at a rate of 10 liters per minute and a concentration of 600 ppm.
On-off valve 1 so that the ozone gas of the air becomes 1 liter per minute
1, 35 and 15 were adjusted. The ozone bubbles flowing out of the ozone gas mixing device 8 and dispersed in the bubble dispersing section 17 are 20 to
It was in the range of 80 μm. As a result of measuring the presence of bacteria in the fertilizer component replenishing tank 26, none of the bacteria was detected. In addition, the residual ozone gas concentration in the fertilizer component replenishing tank 26 is as low as the detection limit or less (0.02 ppm or less),
It was below the value that affects plants. The fertilizer component in the solution hardly decreased, but only manganese tended to slightly decrease.

For comparison, the same bacteria were sterilized under the same conditions as above except that the solution temperature was lowered to 15 ° C.
As a result of measuring the presence of bacteria in the fertilizer component replenishment tank 26, 5 bacteria per 1 ml for bacteria and 12 bacteria per 1 ml for filamentous fungi.
Existed. The residual ozone gas concentration in the fertilizer component replenishing tank 26 was as high as about 0.04 ppm, which was a level that might cause oxidative damage to plant roots. Furthermore, the decrease in the fertilizer component in the solution was accompanied by a remarkable decrease in manganese, which required immediate replenishment. No decrease in other components was observed.

[0024]

As described above, according to the method for sterilizing a plant cultivation solution according to claim 1, ozone gas is sucked from its negative pressure side using a pump, and the ozone gas is dissolved in the solution in a pressurized state. Then, by decompressing the solution under atmospheric pressure, the dissolved ozone is converted into fine ozone bubbles in the solution, dispersed and mixed, and the microorganisms in the solution are sterilized by gas-liquid contact. The sterilization efficiency of ozone at the gas-liquid contact portion is higher than that of conventional liquids, and rapid sterilization can be performed even with bubbles having a relatively low ozone concentration. Therefore, the concentration of ozone released into the greenhouse and the concentration of ozone contained in the solution after sterilization can be extremely reduced, and oxidative damage to the leaves and roots of the plant can be avoided. In addition, since the ozone concentration in the ozone bubbles can be reduced, alteration of active ingredients such as fertilizers can be suppressed. Further, the capacity of the ozone generator can be reduced.

The method for disinfecting a solution for plant cultivation according to claim 2 is characterized in that the ozone concentration in the ozone gas is set to 600 ppm or less. It is possible to perform a bactericidal action by avoiding oxidative damage to plant leaves and roots,
Further, deterioration of active ingredients such as fertilizers can be suppressed more reliably. Furthermore, the method for sterilizing a plant cultivating solution according to claim 3 is characterized in that sterilization is performed after removing solid lumps present in the solution with a filter device, and when removing fungi in the solid lumps, Even in the case where solids such as dust in the air are mixed into the solution, residual bacteria after the sterilization treatment can be extremely reduced. Furthermore, in the method for sterilizing a plant cultivating solution according to claim 4, sterilization is performed by maintaining the temperature of the solution at a level at which ozone is not substantially dissolved. The bactericidal effect can be enhanced.

According to a fifth aspect of the present invention, there is provided an apparatus for sterilizing a plant cultivating solution, comprising: a collecting tank for collecting a solution from a plant cultivation bed; a temperature adjusting means for adjusting the temperature of the solution in the collecting tank;
An ozone generator, an ozone gas mixing device for mixing ozone gas from the ozone generator into the solution in the recovery tank to disperse fine ozone bubbles, and a gas-liquid for bringing the ozone bubbles from the ozone gas mixing device into contact with the solution. It is characterized by having a contact portion, and can adjust the temperature of the solution in the recovery tank to a temperature at which ozone is not substantially dissolved, and further converts the temperature-adjusted solution and ozone gas from the ozone generator into ozone gas. By mixing with a mixing device, a large number of fine ozone bubbles are dispersed in the solution, and the bacteria in the solution can be sufficiently brought into contact with the ozone at the gas-liquid contact portion. Therefore, the concentration of ozone released into the greenhouse and the concentration of ozone contained in the solution after sterilization can be extremely reduced, so that oxidation damage to the leaves and roots of the plant can be avoided. Further, the capacity of the ozone generator can be reduced. Further, in the sterilizing apparatus for plant cultivation solution according to claim 6, a fertilizer component replenishing tank is provided on the outlet side of the gas-liquid contact part, and the fertilizer component replenishing tank replenishes the insufficient fertilizer component. It is possible to always supply a solution having a desired fertilizer component concentration to the plant cultivation bed.

[Brief description of the drawings]

FIG. 1 is a process flow diagram showing an example of a sterilization apparatus for performing a sterilization method of the present invention.

FIG. 2 is a process flow chart of an ozone gas supply portion to the ozone gas mixing device 8 in FIG.

FIG. 3 is a diagram illustrating a gas-liquid contact portion 1 from a bubble dispersing portion 17 in FIG.
FIG. 8 is a schematic diagram showing a state of ozone bubbles reaching the gas separation unit 21 via 8.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 collection tank 2 pipe 3 pipe 4 heat exchange section 5 temperature detection section 6 upper limit level detection section 7 lower limit level detection section 8 ozone gas mixing device 9 pipe 10 filter device 11 on-off valve 12 compound gauge 13 pipe 14 solenoid valve 15 on-off valve 15a Pressure gauge 16 Taper section 17 Bubble dispersion section 18 Gas-liquid contact section 19 Drain pipe 20 On-off valve 21 Gas-liquid separation section 22 Inclined plate 23 Liquid outlet section 24 Gas filter section 25 Connecting pipe 26 Fertilizer component supply tank 27 Fertilizer component supply section 28 Conductivity meter 29 Fertilizer component supply pipe 30 Fertilizer component supply pipe 31 Upper limit level detector 32 Lower limit level detector 33 Discharge pump 33a Pipe 34 Gas dryer 35 Open / close valve 36 Pipe 37 Pipe 38 Ozone generator 40 Temperature control means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 540 C02F 1/50 540A 550 550C // A01G 31/00 601 A01G 31/00 601A (72) Inventor Masako Yamauchi 3-7-1 Nishishinbashi, Minato-ku, Tokyo Toshiba Plant Construction Co., Ltd. (72) Inventor Makoto Iwan 3-7-1 Nishishinbashi, Minato-ku, Tokyo Toshiba Plant Construction Co., Ltd. (72) Inventor Hideo Maki 1-40-2 Nisshin-cho, Omiya-shi, Saitama F-term in the Research Institute for Biological Sciences (Reference) 2B314 MA17 MA48 ND30 PA03 PA13 PB24 PB44 PB55 PD43 4H011 AA01 AA02 DA22 DE10 DE11

Claims (6)

[Claims] In a method for sterilizing a solution for plant cultivation, ozone gas is sucked from a negative pressure side of the solution using a pump to dissolve it in a pressurized state, and then the solution is subjected to atmospheric pressure. A method for disinfecting a plant cultivation solution, which comprises converting ozone to be dissolved into fine ozone bubbles in a solution by dispersing and dispersing the ozone into the solution, and sterilizing microorganisms in the solution by gas-liquid contact. 2. An ozone concentration in ozone gas of 600 pp.
2. The method for sterilizing a plant cultivation solution according to claim 1, wherein m is equal to or less than m. 3. The method for sterilizing a solution for plant cultivation according to claim 1, wherein the solid matter present in the solution is removed by a filter device and then sterilized. 4. The method for sterilizing a solution for plant cultivation according to claim 1, wherein the sterilization is performed while maintaining a temperature at which ozone is not substantially dissolved. 5. An apparatus for sterilizing a solution for plant cultivation, comprising: a collection tank 1 for collecting a solution from a plant cultivation bed; a temperature adjusting means 40 for adjusting the temperature of the solution in the collection tank 1;
An ozone generator 38, an ozone gas mixer 8 for mixing ozone gas from the ozone generator 38 into the solution in the recovery tank 1 to disperse fine ozone bubbles in the solution, and an ozone bubble from the ozone gas mixer 8. An apparatus for sterilizing a solution for plant cultivation, comprising a gas-liquid contact part 18 for bringing the solution into gas-liquid contact. 6. The plant according to claim 5, wherein a fertilizer component replenishing tank 26 is provided on an outlet side of the gas-liquid contact portion 18, and the fertilizer component replenishing tank 26 is replenished with the insufficient fertilizer component. Sterilizer for cultivation solution.