Plasma functional liquid production device and method and plant cultivation plant

Abstract

To provide a plasma functional liquid production device and a method, capable of achieving preferable washing effects and sterilization effects even when a plasma gas is introduced into liquid by bubbling, and a plant cultivation plant.SOLUTION: A plasma functional liquid production device 10 comprises: a plasma head 20 for generating a plasma gas including active species from a plasma generation gas; a plasma gas discharge part 30 for discharging the plasma gas in a bubble state; and a plasma function liquid generation tank 41 for storing a solvent S. The device further comprises: a plasma functional liquid generation part 40 for introducing the plasma gas in the bubble state to the solvent S for generating plasma functional liquid L, where oxygen density of the plasma generation gas is 90% or greater.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , ,

[0007] ,

[0001] The present invention relates to a plasma functional liquid production apparatus and method, and a plant cultivation plant.

Background Art

[0002] In recent years, technologies related to various cleaning and sterilization using plasma have been studied. In particular, introducing a plasma-treated gas (plasma gas) into a liquid (solvent) and using active species such as ozone, ions or radicals generated by the plasma treatment to clean or sterilize the liquid has been considered.

[0003] Patent Document 1 discloses introducing ozone, radicals, etc. generated by plasma into a liquid to be treated by bubbling to decompose organic substances and the like present in the liquid.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as a method of bubbling plasma gas, there are known a Venturi method of temporarily narrowing the liquid flow path to generate fine bubbles by a pressure change, and a fine pore method of dispersing gas from fine bubbles into the liquid flow and separating the bubbles generated in the fine pores by the shear force of the liquid flow.

[0006] However, ozone, radicals, etc. generated by plasma tend to lose their activity due to pressure changes and shear heat, and there is a problem that a sufficient cleaning effect or sterilization effect may not be obtained depending on the type of plasma gas.

[0007] Therefore, even when introducing plasma gas into a liquid by bubbling, technical challenges arise that must be addressed in order to achieve good cleaning and disinfecting effects, and the present invention aims to solve these challenges. [Means for solving the problem]

[0008] In light of the above-mentioned circumstances, the inventors conducted diligent research and found that good cleaning and disinfecting effects can be obtained by introducing plasma gas derived from oxygen gas of a predetermined concentration into a solvent by bubbling, thus completing the present invention.

[0009] To achieve the above objective, the plasma functional liquid manufacturing apparatus according to the present invention comprises a plasma gas generation unit that generates plasma gas containing active species from plasma generation gas, a plasma gas discharge unit that releases the plasma gas in a bubble state, and a plasma functional liquid generation tank that stores a solvent, and a plasma functional liquid generation unit that generates plasma functional liquid by introducing the plasma gas in a bubble state into the solvent, wherein the oxygen concentration of the plasma generation gas is 90% or higher.

[0010] Furthermore, the plasma functional liquid manufacturing method according to the present invention is a plasma functional liquid manufacturing apparatus comprising: a plasma gas generation unit that generates plasma gas containing active species from plasma generation gas; a plasma gas discharge unit that releases the plasma gas in a bubble state; and a plasma functional liquid generation tank that stores a solvent, wherein the plasma functional liquid generation unit generates plasma functional liquid by introducing the plasma gas in a bubble state into the solvent, and the oxygen concentration of the plasma generation gas is 90% or higher. [Effects of the Invention]

[0011] In this invention, a plasma gas containing active species with excellent cleaning and disinfecting effects is generated from a plasma generation gas with an oxygen concentration of 90% or more. This plasma gas is then introduced into the solvent in the plasma functional liquid generation tank in a bubbly state by passing through a plasma gas discharge section without excessive heat generation or pressure fluctuations, thereby obtaining a plasma functional liquid with excellent cleaning and disinfecting effects containing long-lived active species. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing the configuration of a plasma functional liquid manufacturing apparatus according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a plant cultivation plant according to a second embodiment of the present invention. [Figure 3] This is a schematic diagram showing the configuration of a plant cultivation plant according to the first modified example of the second embodiment. [Figure 4] This is a schematic diagram showing the configuration of a plant cultivation plant according to a second modified example of the second embodiment. [Figure 5] This is a schematic diagram showing the configuration of a plant cultivation plant according to a third modified example of the second embodiment. [Figure 6] This is a schematic diagram showing the experimental procedure for an example experiment. [Figure 7] This graph shows the experimental results for Experiment Example 1. [Figure 8] This is a schematic diagram showing the experimental procedure for Experiment Example 2. [Figure 9] This graph shows the experimental results for Experiment Example 2. [Figure 10] This graph shows the experimental results for Experiment Example 3. [Figure 11] This graph shows the experimental results for Experiment Example 4. [Figure 12] This graph shows the experimental results for Experiment Example 5. [Modes for carrying out the invention]

[0013] Various embodiments of the present invention will be described respectively based on the drawings. In the following, when referring to the number of components, numerical values, amounts, ranges, etc., unless otherwise specifically stated or limited to a specific number in principle, it is not limited to that specific number, and it may be more or less than the specific number.

[0014] Also, when referring to the shape, positional relationship, etc. of components, etc., unless otherwise specifically stated or considered not to be so in principle, it includes those substantially approximating or similar to the shape, etc.

[0015] Also, the drawings may be exaggerated, such as enlarging characteristic parts for easy understanding of the features, and the dimensional ratios of components, etc. are not necessarily the same as in reality. Also, in cross-sectional views, in order to make the cross-sectional structure of components easy to understand, the hatching of some components may be omitted.

[0016] <First Embodiment> First, the plasma functional liquid manufacturing apparatus 10 according to the first embodiment of the present invention will be described based on the drawings. FIG. 1 is a schematic diagram showing the configuration of the plasma functional liquid manufacturing apparatus 10. The plasma functional liquid manufacturing apparatus 10 manufactures a plasma functional liquid L excellent in cleaning effect and sterilization effect.

[0017] The plasma functional liquid manufacturing apparatus 10 includes a plasma head 20 which is a plasma gas generation unit. The plasma head 20 may have any configuration as long as it generates plasma, but an atmospheric pressure plasma device that generates plasma at a pressure near atmospheric pressure is preferable. The atmospheric pressure plasma device is smaller in device size, superior in operability, and higher in safety compared to low-pressure plasma devices such as vacuum plasma devices. Furthermore, the atmospheric pressure plasma device can generate a higher concentration of active species compared to low-pressure plasma devices.

[0018] The Inside the plasma head 20 are two plate-shaped electrodes, a first electrode 21 and a second electrode 22, which are positioned opposite each other with a gap between them. A high-frequency voltage is applied to the first electrode 21 by a power supply 23. The second electrode 22 is connected to ground 24.

[0019] A plasma-generating gas is supplied to the space between the first electrode 21 and the second electrode 22 via a compressor 25. The plasma-generating gas is a gas that generates plasma and contains at least oxygen gas. The oxygen concentration of the plasma-generating gas is preferably 90% or more, more preferably 90% to 95%, to achieve excellent cleaning and disinfecting effects. The oxygen concentration of the plasma-generating gas may be adjusted in advance using an oxygen concentrator (not shown) as needed. If the oxygen concentration of the plasma-generating gas is less than 100%, the plasma-generating gas will contain nitrogen components, etc. In particular, when a plasma-generating gas with an oxygen concentration of 95% is generated using an oxygen concentrator employing the PSA method, which generates high-concentration oxygen by adsorbing nitrogen from the air onto zeolite, theoretically about 0.5% nitrogen will be present. The nitrogen component of the plasma-generating gas is preferably 5% or less.

[0020] The plasma head 20 is connected to the plasma gas emission unit 30 via a gas transport path 31. The plasma head 20 and the plasma gas emission unit 30 are separated, which suppresses the transfer of heat generated in the plasma head 20 to the plasma gas emission unit 30.

[0021] The gas transport path 31 has one end connected to the plasma head 20 and the other end connected to the plasma gas discharge section 30, and sends the plasma gas generated in the plasma head 20 to the plasma gas discharge section 30. The plasma gas is pressurized to a degree that suppresses backflow from the plasma gas discharge section 30 to the plasma head 20.

[0022] The plasma gas emission unit 30 is immersed in liquid in the plasma functional liquid generation tank 41, which will be described later. The plasma gas emission unit 30 is a porous member, for example, formed in a hollow, substantially cylindrical shape, with numerous holes 32 formed on its outer surface. The plasma gas emission unit 30 introduces plasma gas bubbles B into the solvent S in the plasma functional liquid generation tank 41 by passing the plasma gas supplied to its interior through the holes 32.

[0023] The pore size of the holes 32 can be set to any size corresponding to the bubble size of the bubbles B introduced into the solvent S in the plasma functional liquid generation tank 41. For example, depending on the pore size of the holes 32, it is possible to generate microbubbles with a bubble size of about 1 μm to 100 μm, or ultrafine bubbles with a bubble size of about several tens of nanometers to 1 μm.

[0024] Bubble B contains active species such as ozone, hydrogen peroxide, hydroxide radicals, nitrogen oxides, and singlet oxygen, depending on the type of plasma generating gas. In this specification, "active species" refers to radicals etc. that are generated when the plasma generating gas is activated by the plasma. The radicals contained in the plasma gas differ depending on the type of plasma generating gas used to generate the plasma gas. For example, if the plasma generating gas contains an oxygen component, oxygen radicals are generated, and if the plasma generating gas contains a nitrogen component, nitrogen oxide radicals are generated. Nitrate nitrogen (nitrate radicals) is also useful for plant growth.

[0025] The plasma gas emission section 30 is made of, for example, metal, ceramics, or plastic, preferably copper, silver, or an alloy thereof. This allows copper ions or silver ions to be introduced into the solvent S.

[0026] The plasma functional liquid manufacturing apparatus 10 includes a plasma functional liquid generation unit 40 that generates plasma functional liquid L. In this specification, "plasma functional liquid L" refers to a solution in which active species held in plasma gas are held in bubbles B in solvent S and then gradually dissolved in solvent S. That is, plasma functional liquid L contains active species held in bubbles B or active species dissolved in solvent S. By dissolving the active species in solvent S, solvent S itself is cleaned and disinfected, and plasma functional liquid L also cleans and disinfects other objects.

[0027] The plasma functional liquid generation unit 40 includes a plasma functional liquid generation tank 41 that stores solvent S and immerses the plasma gas emission unit 30 in the solvent S. The plasma functional liquid generation tank 41 is not equipped with stirring blades or the like to agitate the solvent S, and the generation of airflow in the solvent S is suppressed. The solvent S is water such as ultrapure water, ion-exchanged water, purified water, or distilled water, or a solution containing inorganic nutrients, or liquid fertilizer, but is not limited to these. When liquid fertilizer is used as the solvent S, the plasma functional liquid L can kill fungi contained in the liquid fertilizer, and active species suitable for plant growth can be included in the liquid fertilizer.

[0028] The bubbles B are preferably microbubbles or ultrafine bubbles that are retained in the solvent S for a long time. In particular, when bubbles B are ultrafine bubbles, there is almost no buoyancy acting on them, so the bubble state is maintained for a long time.

[0029] Thus, the plasma functional liquid manufacturing apparatus 10 according to this embodiment comprises a plasma head 20 that generates plasma gas containing active species from plasma generation gas, a plasma gas discharge unit 30 that releases plasma gas in a bubble state, and a plasma functional liquid manufacturing tank 41 that stores solvent S, and a plasma functional liquid manufacturing unit 40 that generates plasma functional liquid L by introducing plasma gas in a bubble state into solvent S, and the oxygen concentration of the plasma generation gas is 90% or higher.

[0030] With this configuration, a plasma gas containing active species with excellent cleaning and sterilization effects is generated from a plasma generation gas with an oxygen concentration of 90% or more. This plasma gas is then introduced into the solvent S in the plasma functional liquid generation tank 41 in a bubbly state by passing through the holes 32 of the plasma gas discharge section 30 without generating heat or pressure fluctuations, thereby obtaining a plasma functional liquid L containing long-lived active species with excellent cleaning and sterilization effects.

[0031] Furthermore, the plasma functional liquid manufacturing apparatus 10 according to this embodiment is configured such that the oxygen concentration of the plasma generation gas is 90% or more and 95% or less.

[0032] This configuration allows for the easy acquisition of plasma-generating gas using a small oxygen concentrator, and suppresses the generation of ozone that occurs when the oxygen concentration is excessively high, thus enabling the production of a plasma functional liquid L that is highly efficient and economical.

[0033] Furthermore, the plasma functional liquid manufacturing apparatus 10 according to this embodiment is configured such that the nitrogen concentration of the plasma generation gas is 0.5% or higher.

[0034] With this configuration, nitrate ions derived from nitrogen gas contained in the plasma generation gas dissolve in the plasma functional liquid L, making it possible to obtain a plasma functional liquid L suitable for plant growth.

[0035] Furthermore, in the plasma functional liquid manufacturing apparatus 10 according to this embodiment, the plasma head 20 is located outside the plasma functional liquid generation tank 41, and the plasma gas emission unit 30 is a porous member that is immersed in the solvent S stored in the plasma functional liquid generation tank 41 and releases the plasma gas in a bubble state as the plasma gas passes through it.

[0036] With this configuration, the plasma head 20 is placed outside the plasma functional liquid generation tank 41, and the plasma gas is introduced into the solvent S from the plasma gas emission unit 30 which is immersed in the solvent S. This suppresses the loss of activity of the active species contained in the plasma functional liquid L due to the heat generated when the plasma gas is generated, thereby extending the lifespan of the active species.

[0037] Furthermore, in the plasma functional liquid manufacturing apparatus 10 according to this embodiment, the plasma gas emission section 30 is made of copper, silver, or an alloy thereof.

[0038] With this configuration, copper ions or silver ions dissolved from the plasma gas emission unit 30 are introduced into the solvent S, thereby enhancing the cleaning and sterilization effects of the plasma functional liquid L.

[0039] Furthermore, the plasma functional liquid manufacturing apparatus 10 according to this embodiment is configured such that the bubbles of the plasma gas are microbubbles or ultrafine bubbles.

[0040] With this configuration, since bubble B is retained for a long period of time, the active species contained in the plasma functional liquid L can be maintained for a long period of time.

[0041] <Second Embodiment> Next, a plant plant 1A according to a second embodiment of the present invention will be described with reference to the drawings. Figure 2 is a schematic diagram showing the configuration of the plant plant 1A according to the second embodiment. The plant plant 1A comprises a cultivation tank 2 for hydroponically cultivating plants P and a plasma functional liquid production device 10.

[0042] The cultivation tank 2 comprises a container 2a for storing a solution A containing liquid fertilizer, and a support part 2b for supporting the plant P so that the underground portion of the plant P reaches the solution A in container 2a.

[0043] The plasma functional liquid generation unit 40 is equipped with a liquid supply passage 42, which serves as a discharge section for sending the plasma functional liquid L to the container 2a. The liquid supply passage 42 has its upstream end connected to the plasma functional liquid generation tank 41 and its downstream end connected to the container 2a. The plasma functional liquid L sent through the liquid supply passage 42 is pressurized using a pump (not shown) or the like and mixed with solution A. Note that solution A does not necessarily have to contain liquid fertilizer.

[0044] In this way, the plasma functional liquid L generated in the plasma functional liquid manufacturing device 10 is sent to the cultivation tank 2 via the liquid supply passage 42, and the solution A in the cultivation tank 2 is disinfected or sterilized by the plasma functional liquid L, so that the plants P grow well.

[0045] <Example 1> Next, a modified example of the plant plant 1A according to the second embodiment will be described with reference to the drawings. Figure 3 is a schematic diagram showing the configuration of the plant plant 1B according to this modified example. The plant plant 1B according to this modified example differs from the plant plant 1A according to the second embodiment described above in the following respects, while other configurations are common. Therefore, common components are denoted by the same reference numerals, and redundant explanations are omitted.

[0046] Both solution A in container 2a and solvent S in the plasma functional liquid generation tank 41 contain liquid fertilizer. In addition, the plasma generation gas contains nitrogen components, and the plasma functional liquid contains nitrate nitrogen (nitrate radicals), which are nutrients for plants.

[0047] The plasma functional liquid generation unit 40 is equipped with a liquid circulation path 43 that connects the container 2a and the plasma functional liquid generation tank 41. The upstream end of the liquid circulation path 43 is connected to the container 2a, and the downstream end is connected to the plasma functional liquid generation tank 41. The solution in the container 2a and the plasma functional liquid L are returned from the container 2a to the plasma functional liquid generation tank 41 via the liquid circulation path 43 by a pump or the like (not shown). In other words, the solution A circulates between the container 2a and the plasma functional liquid generation tank 41 via the liquid supply path 42 and the liquid circulation path 43.

[0048] The solution refluxed from container 2a is mixed with the solvent S stored in the plasma functional liquid generation tank 41, and plasma gas bubbles B released from the plasma gas emission unit 30 are introduced into the solvent S stored in the plasma functional liquid generation tank 41. In this way, the plasma functional liquid L containing dissolved active species circulates between the plasma functional liquid generation unit 40 and the cultivation tank 2.

[0049] Furthermore, since the lifespan of the liquid fertilizer contained in solvent S and solution A is longer than the lifespan of the active species, the liquid fertilizer can be reused repeatedly by continuously supplying the active species as described above.

[0050] <Modification 2> Next, other modifications of the plant plant 1A according to the second embodiment will be described with reference to the drawings. Figure 4 is a schematic diagram showing the configuration of the plant plant 1C according to this modification. The plant plant 1C according to this modification differs from the plant plant 1A according to the second embodiment described above in the following respects, while other configurations are common. Therefore, common components are denoted by the same reference numerals, and redundant explanations are omitted.

[0051] The plant plant 1C includes a cultivation container 3 for growing plants P planted in culture soil, and a plasma functional liquid production device 10.

[0052] The plasma functional liquid generation unit 40 includes a liquid supply pipe 44 and a spray head 45 as discharge units. The base end of the liquid supply pipe 44 is connected to the plasma functional liquid generation tank 41, and the tip is connected to the spray head 45. The plasma functional liquid L supplied by the liquid supply pipe 44 is pumped using a pump or the like (not shown). The liquid supply pipe 44 is preferably flexible.

[0053] The spray head 45 sprays the plasma functional liquid L to the outside. The flowers, leaves, stems, or fruits of plant P that are sprayed with the plasma functional liquid L are disinfected or sterilized by the active species contained in the plasma functional liquid L.

[0054] By using an atmospheric pressure plasma device in the plasma head 20, the plasma functional liquid manufacturing device 10 can be made lightweight and safe, and the plasma functional liquid manufacturing device 10 can be miniaturized to a portable size. Therefore, the user can carry the plasma functional liquid manufacturing device 10 to the vicinity of the cultivation container 3 and spray the plasma functional liquid L onto any plant P. Note that the plasma functional liquid manufacturing device 10 is not limited to spraying the plasma functional liquid L onto the plant P, but may also be used to drip the plasma functional liquid L onto the plant P, etc.

[0055] <Variation 3> Next, other modifications of the plant plant 1A according to the second embodiment will be described with reference to the drawings. Figure 5 is a schematic diagram showing the configuration of the plant plant 1D according to this modification. The plant plant 1D according to this modification differs from the plant plant 1A according to the second embodiment described above in the following respects, while other configurations are common. Therefore, common components are denoted by the same reference numerals, and redundant explanations are omitted.

[0056] The plant plant 1D comprises three cultivation containers 4 for growing plants P planted in culture soil, and a plasma functional liquid production device 10.

[0057] The plasma functional liquid generation unit 40 is equipped with a liquid supply pipe 46 as a discharge unit and three spray heads 47.

[0058] The liquid supply pipe 46 has its base end connected to the plasma functional liquid generation tank 41, branches into three in the middle, and each tip is connected to a respective spray head 47. The plasma functional liquid L supplied by the liquid supply pipe 46 is pumped under pressure using a pump or the like (not shown).

[0059] The spray heads 47 are positioned above each cultivation container 4 and spray the plasma functional solution L toward each container 4. The flowers, leaves, stems, or fruits of the plants P that are sprayed with the plasma functional solution L are disinfected or sterilized by the active species contained in the plasma functional solution L. The number of spray heads 47 can be increased or decreased depending on the number of plants P and cultivation containers 4, and the area to which the spray heads 47 spray the plasma functional solution L.

[0060] The spray head 47 is controlled by a controller 48. The controller 48 controls the timing and amount of plasma functional liquid L sprayed by the spray head 47 according to the temperature and the growth status of the plant P, which are obtained by sensors (not shown). The plasma functional liquid production apparatus 10 is not limited to spraying the plasma functional liquid L onto the plant P, but may also be one that drops the plasma functional liquid L onto the plant P, etc. [Examples]

[0061] (Experimental Example 1) A comparative experiment was conducted to examine the sterilization effects of the plasma gases generated when oxygen, carbon dioxide, air, and nitrogen were used as the plasma generation gases.

[0062] First, 248 ml of purified water and 2 ml of spore solution were mixed to prepare a 250 ml spore suspension. The spores used in the spore solution were Fusarium oxysporum f.sp. fragariae: NBRC 31982. These spores are the main cause of strawberry wilt disease, and by disinfecting or sterilizing them, it is possible to control the disease in strawberries and suppress growth inhibition and wilting.

[0063] Next, as shown in Figure 6, 50 ml of spore suspension was placed in beaker 101 and plasma treatment was performed using plasma gas in the plasma bubbling apparatus 100. The plasma gas generated by the multi-gas plasma jet 102, which is the plasma generation unit, was sent via cylindrical piping 103 to the porous filter 104, which is the plasma gas emission unit immersed in the spore suspension, and introduced into the spore suspension in the form of bubbles through the porous filter 104. The length of cylindrical piping 103 was set to approximately 90 mm, the length of porous filter 104 to approximately 20 mm, and the flow rate of the introduced plasma gas was set to 3 SLPM.

[0064] Four types of plasma generating gases were prepared to generate plasma gas: oxygen, carbon dioxide, air, and nitrogen. The time for introducing the plasma gas generated from each gas into the spore suspension in bubble form (processing time) was set to 0 seconds, 120 seconds, 300 seconds, and 600 seconds.

[0065] Then, 1 ml of the spore suspension into which the plasma gas in a bubbly state had been introduced was serially diluted and dropped onto an agar medium in a Petri dish 105. After incubation at room temperature for 2 days, the number of spores that germinated was counted. The results are shown in Figure 7.

[0066] As shown in Figure 7, when oxygen gas is used as the plasma generating gas, a bubbling period of 120 seconds is required for the plasma gas; when carbon dioxide gas is used as the plasma generating gas, a bubbling period of 300 seconds or more is required for the plasma gas; and when air is used as the plasma generating gas, a bubbling period of 600 seconds or more is required for the plasma gas to be generated. On the other hand, the bubbling effect of plasma gas generated using nitrogen gas is smaller than that of plasma gas generated from oxygen, carbon dioxide, or air. From these results, it can be concluded that using oxygen gas as the plasma generating gas is the most effective.

[0067] (Experimental Example 2) Next, we conducted an experiment to verify the relationship between the oxygen concentration of the oxygen gas contained in the plasma generation gas and the sterilization effect of the plasma gas.

[0068] As shown in Figure 8, 50 ml of purified water was placed in beaker 101, and plasma gas was introduced into the purified water using a plasma bubbling device 100. Specifically, the plasma gas generated by the multi-gas plasma jet 102, which is the plasma generation unit, was sent via cylindrical piping 103 to a porous filter 104, which is the plasma gas discharge unit immersed in purified water, and introduced into the purified water in the form of bubbles through the porous filter 104. The length of the cylindrical piping 103 was set to approximately 90 mm, the length of the porous filter 104 to approximately 20 mm, and the flow rate of the introduced plasma gas was set to 3 SLPM.

[0069] Five types of plasma generating gases were prepared, and the time for introducing the plasma gas generated from each gas into purified water in a bubble state (processing time) was set to 60 seconds and 300 seconds. Plasma generation gas 1: 100% air (21% oxygen, 78% nitrogen, 1% argon) Plasma generation gas 2: 40% oxygen, 58% nitrogen, 2% argon Plasma generation gas 3: 70% oxygen, 27% nitrogen, 3% argon Plasma generation gas 4: 90% oxygen, 6% nitrogen, 4% argon Plasma generating gas 5: 100% oxygen

[0070] Next, 10 μl of spore lysate was mixed with 990 μl of purified water into which a plasma gas in a bubbly state had been introduced, and the mixture was allowed to stand for 10 minutes to prepare a spore suspension. The spores used in the spore lysate were Fusarium oxysporum f.sp. fragariae: NBRC 31982. Then, 1 ml of the spore suspension was serially diluted and dropped onto agar plates in a Petri dish 105, and incubated at room temperature for 2 days before the number of viable bacteria was counted. The results are shown in Figure 9.

[0071] As shown in Figure 9, when the oxygen concentration of the plasma generating gas was set to 90% and 100%, the number of surviving bacteria decreased significantly after bubbling times (processing times) of 60 seconds and 300 seconds, indicating a remarkable sterilization effect. On the other hand, when the oxygen concentration of the plasma generating gas was set to 21%, 40%, and 70%, the decrease in the number of surviving bacteria, i.e., the sterilization effect, was smaller compared to the 90% and 100% oxygen concentrations.

[0072] (Experimental Example 3) Next, we conducted an experiment to further investigate the relationship between the oxygen concentration of the oxygen gas contained in the plasma generation gas and the sterilization effect of the plasma gas.

[0073] In the same manner as in Experimental Example 2, a spore suspension was prepared by mixing 990 μl of purified water into which a plasma gas in a bubbly state had been introduced with 10 μl of spore liquor. As in Experimental Example 2, Fusarium oxysporum f.sp. fragariae: NBRC 31982 was used as the spores in the spore liquor.

[0074] Three types of plasma generating gases were prepared, and the time for introducing the plasma gas generated from each gas into purified water in a bubble state (processing time) was set to 10 seconds, 20 seconds, 30 seconds, and 60 seconds. Then, as in Example 2, 1 ml of the spore suspension was serially diluted and dropped onto an agar medium in Petri dish 105, and the number of viable bacteria was counted after incubation at room temperature for 2 days. The results are shown in Figure 10. Plasma generation gas 6: 80% oxygen, 17% nitrogen, 3% argon Plasma generation gas 7: 90% oxygen, 6% nitrogen, 4% argon Plasma generating gas 8: 100% oxygen

[0075] Figure 10 shows that when the oxygen concentration of the plasma generating gas is set to 90% and 100%, the number of surviving bacteria decreases significantly after a bubbling time (processing time) of 10 seconds or more, resulting in a remarkable sterilization effect. On the other hand, when the oxygen concentration of the plasma generating gas is set to 80%, the reduction in the number of surviving bacteria, i.e., the sterilization effect, is smaller compared to when the oxygen concentration is 90% and 100%.

[0076] Note that although the plasma generating gas 4 in Experimental Example 2 and the plasma generating gas 7 in Experimental Example 3 were conducted using the same components, the number of spores per unit volume of the spore solution used in the experiment differed from experiment to experiment, and the number of viable bacteria before culturing in the petri dish also differed. Therefore, the absolute values ​​of the number of viable bacteria in Figures 9 and 10 are different. The same applies to plasma generating gas 5 in Experimental Example 2 and plasma generating gas 8 in Experimental Example 3.

[0077] (Experimental Example 4) Next, we conducted an experiment to further investigate the relationship between the oxygen concentration of the oxygen gas contained in the plasma generation gas and the sterilization effect of the plasma gas, when the processing time was set to 60 seconds.

[0078] In the same manner as in Experimental Example 3, a spore suspension was prepared by mixing 990 μl of purified water into which a plasma gas in a bubbly state had been introduced with 10 μl of spore saturate. As in Experimental Example 3, Fusarium oxysporum f.sp. fragariae: NBRC 31982 was used as the spores in the spore saturate.

[0079] Seven types of plasma-generating gases were prepared, and the resulting bubbly plasma gas was introduced into purified water for 60 seconds. Then, as in Example 2, 1 ml of the spore suspension was serially diluted and dropped onto an agar medium in a Petri dish 105. After incubation at room temperature for 2 days, the number of viable bacteria was counted. The results are shown in Figure 11. In Figure 11, the horizontal axis represents the plasma-generating gases 9-15, and the vertical axis represents the number of viable bacteria. The dashed line in Figure 11 indicates the number of bacteria at the start of the experiment (initial bacterial count). Plasma generation gas 9: 80% oxygen, 17% nitrogen, 3% argon Plasma generation gas 10: 85% oxygen, 11% nitrogen, 4% argon Plasma generation gas 11: 90% oxygen, 6% nitrogen, 4% argon Plasma generation gas 12: Oxygen 94%, Nitrogen 1%, Argon 5% Plasma generation gas 13: 95% oxygen, 0% nitrogen, 5% argon Plasma generation gas 14: 99% oxygen, 1% nitrogen, 0% argon Plasma generation gas 15: 100% oxygen, 0% nitrogen, 0% argon

[0080] According to Figure 11, when plasma-generating gases 9-10 are used, the number of reduced bacteria, which is the difference between the initial bacterial count and the number of surviving bacteria, is less than 1 on a logarithmic scale, or less than 1 / 10 on a linear scale. On the other hand, when plasma-generating gases 11-15 are used, the number of reduced bacteria is greater than or equal to 1 on a logarithmic scale, or greater than 1 / 10 on a linear scale.

[0081] (Experimental Example 5) In Examples 1 to 4, Fusarium oxysporum f.sp. fragariae: NBRC 31982 was used as the spores in the spore solution. However, in this example, the bactericidal effect against bacteria other than Fusarium oxysporum f.sp. fragariae: NBRC 31982 was investigated. In this example, a bacterial suspension containing the following three types of bacteria and one type of spore solution were used. In the same manner as in Experimental Example 3, 990 μl of purified water into which plasma gas in a bubbly state was introduced was mixed with 10 μl of the bacterial suspension or spore solution to prepare a bacterial suspension or spore suspension. • Bacterial solution 1: S. aureus (Staphylococcus aureus) ·Bacterial liquid 2: E. coli (E. coli) ·Bacterial solution 3: P. aeruginosa (Pseudomonas aeruginosa) • Spore solution 1: Gray mold fungus

[0082] Two types of oxygen gases with different concentrations, produced using a PSA-type oxygen concentrator, were prepared as plasma generation gases. Note that the nitrogen and argon concentrations in plasma generation gases 16-17 are estimated values. Plasma generation gas 16: Oxygen 90%, Nitrogen 5.7%, Argon 4.3% Plasma generation gas 17: 95% oxygen, 0.5% nitrogen, 4.5% argon

[0083] Then, the plasma gas generated from the plasma generating gas was introduced into purified water in a bubble state for 60 seconds. Then, as in Example 2, 1 ml of the spore suspension was serially diluted and dropped onto an agar medium in Petri dish 105, and the number of viable bacteria was counted after incubation at room temperature for 2 days. The results are shown in Figure 12. In Figure 12, the horizontal axis represents the bacterial suspensions 1-3 and spore suspension 1 described above, and the vertical axis represents the initial bacterial count and the number of viable bacteria when plasma generating gases 16-17 were used for the bacterial suspensions 1-3 and spore suspension 1 described above.

[0084] As shown in Figure 12, using plasma generating gases with oxygen concentrations of 90% and 95% for any of the bacterial suspensions 1-3 and spore suspension 1, the decrease in the number of bacteria, which is the difference between the initial number of bacteria and the number of surviving bacteria, is greater than 1 on a logarithmic scale, or greater than 1 / 10 on a linear scale.

[0085] Thus, as shown in Example 1, oxygen gas is very effective as a plasma generating gas, and in particular, a remarkable bactericidal effect can be obtained when the oxygen concentration is at least 90% or higher, as can be seen from Examples 2 to 4. Furthermore, as shown in Experimental Example 5, it can be seen that using oxygen gas as a plasma generating gas shows an effective bactericidal effect not only against Fusarium oxysporum f.sp. fragariae: NBRC 31982, which is the spore that mainly causes strawberry yellowing disease, but also against S. aureus (Staphylococcus aureus), E. coli (Escherichia coli), P. aeruginosa (Pseudomonas aeruginosa), or gray mold fungi.

[0086] However, raising the oxygen concentration above 95% requires a very expensive high-concentration oxygen generator, making it impractical. In contrast, setting the oxygen concentration below 95% allows the use of a small oxygen concentrator. Furthermore, excessively high oxygen concentrations increase the amount of ozone generated, raising concerns about its effects on humans and plants. In particular, when the oxygen concentration exceeds 95%, the ozone introduced into the liquid does not dissolve and is released into the air, requiring separate ozone countermeasures. Therefore, considering workability and cost, an oxygen concentration between 90% and 95% is preferable.

[0087] When the oxygen concentration is below 95%, the plasma generation gas also contains nitrogen gas. As a result, nitrate ions, which function as nutrients for plant growth, are generated as active species in the plasma functional liquid L.

[0088] Furthermore, the present invention can be modified in various ways other than those described above, as long as it does not deviate from the spirit of the invention, and it goes without saying that the present invention extends to such modified forms. [Explanation of Symbols]

[0089] 1A, 1B, 1C, 1D: Plant 2:Cultivation tank 2a: Container 2b: Support part 3:Cultivation container 4:Cultivation container 10: Plasma functional fluid manufacturing equipment 20: Plasma head 21: First electrode 22: Second electrode 23: Power supply 24: Earth 25: Compressor 30: Plasma gas emission section 31: Gas transport route 32: Hole 40: Plasma functional liquid generation unit 41: Plasma functional liquid generation tank 42:Liquid supply path 43:Liquid circulation path 44, 46:Liquid supply pipe 45, 47: Spray head 48: Controller A: Solution B: Air bubbles L: Plasma functional liquid P:Plant S: Solvent

Claims

1. a plasma gas generating unit that generates a plasma gas containing active species from a plasma generating gas; a plasma gas emission section that emits the plasma gas in a bubble state; a plasma functional fluid generating unit that includes a plasma functional fluid generating tank for storing a solvent, and that generates a plasma functional fluid by introducing the plasma gas in a bubble state into the solvent; Equipped with The plasma functional fluid manufacturing apparatus is characterized in that the oxygen concentration of the plasma generating gas is 90% or more.

2. 2. The plasma functional fluid manufacturing apparatus according to claim 1, wherein the oxygen concentration of the plasma generating gas is 90% or more and 95% or less.

3. 3. The plasma functional fluid manufacturing apparatus according to claim 1, wherein the nitrogen concentration of the plasma generating gas is 0.5% or more.

4. the plasma gas generating unit is disposed outside the plasma functional fluid generating tank, 2. The plasma functional fluid manufacturing apparatus according to claim 1, wherein the plasma gas emission section is a porous member that is immersed in a solvent stored in the plasma functional fluid generation tank and that emits the plasma gas in a bubble state.

5. 5. The plasma functional fluid manufacturing apparatus according to claim 1, wherein the plasma functional fluid generating unit includes a discharge unit capable of discharging the plasma functional fluid to the outside of the plasma functional fluid generating tank.

6. The plasma functional fluid manufacturing apparatus according to claim 5; a cultivation container for cultivating plants; Equipped with The plant cultivation plant is characterized in that the discharging unit drips or sprays the plasma functional liquid onto the plant.

7. The plasma functional fluid manufacturing apparatus according to claim 5; a cultivation tank for hydroponically cultivating plants; Equipped with The plant cultivation plant is characterized in that the discharge unit supplies the plasma functional liquid to the cultivation tank.

8. the solvent is a liquid fertilizer; the plasma generating gas contains at least nitrogen; The plant cultivation plant according to claim 7, characterized in that the plasma functional fluid generating unit is provided with a return path for returning the plasma functional fluid supplied to the cultivation tank from the cultivation tank to the plasma functional fluid generating tank.

9. A plant cultivation plant as described in Claim 7, characterized in that the plasma functional liquid exhibits a bactericidal effect against at least one of spores that cause strawberry yellows, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, or Botrytis cinerea.

10. a plasma gas generating unit that generates a plasma gas containing active species from a plasma generating gas; a plasma gas emission section that emits the plasma gas in a bubble state; a plasma functional fluid generating unit that includes a plasma functional fluid generating tank for storing a solvent, and that generates a plasma functional fluid by introducing the plasma gas in a bubble state into the solvent; A plasma functional fluid manufacturing method using a plasma functional fluid manufacturing apparatus comprising: The plasma functional fluid manufacturing method is characterized in that the oxygen concentration of the plasma generating gas is 90% or more.

11. 11. The plasma functional fluid manufacturing method according to claim 10, wherein the oxygen concentration of the plasma generating gas is 90% or more and 95% or less.

12. 12. The plasma functional fluid manufacturing method according to claim 10, wherein the nitrogen concentration of the plasma generating gas is 0.5% or more.

13. the plasma gas generating unit is disposed outside the plasma functional fluid generating tank, 11. The plasma functional fluid manufacturing method according to claim 10, wherein the porous member of the plasma gas emission section is immersed in the solvent stored in the plasma functional fluid generation tank, and the plasma gas is emitted in the form of bubbles when the plasma gas passes through.

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