Liquid treatment device and liquid treatment method

Abstract

The present invention allows a liquid to retain therein various kinds of active species generated using atmospheric pressure low-temperature plasma for a long time while maintaining activity of the active species.　A liquid treatment device 1 comprises: a plasma generation device 10 including, in a cylindrical space thereof defined by a cylindrical dielectric barrier part 12, a first electrode 14 and a second electrode 16 opposed to the first electrode 14 with the dielectric barrier part 12 therebetween; a power supply device 20 for applying a voltage signal that changes with time between the first electrode 14 and the second electrode 16; an aspirator 30 to which a gas containing an active species generated using plasma from the cylindrical space is supplied, and which has a flow path through which a liquid flows, and draws and mixes the gas containing the active species into the liquid through decompression caused by the liquid flowing through the flow path; and a microbubble generation device 60 for generating microbubbles containing the active species by decompressing the liquid mixed with the gas containing the active species from the aspirator 30.

Description

Liquid treatment device and liquid treatment method

[0001] The present invention relates to a liquid treatment device and a liquid treatment method.

[0002] There are technologies that convert various gases into plasma to generate active species, mix the active species with a liquid to form an active species-containing liquid, and then use the active species-containing liquid for sterilization and other treatments. For example, Patent Document 1 proposes that active species generated by plasma PM are brought into contact with a liquid ML to diffuse the active species into the liquid ML to form a plasma-treated liquid MLp, and that the plasma-treated liquid MLp is applied to an object to sterilize the object. Patent Document 2 also proposes an active species-containing liquid injection device that includes a plasma generation unit that generates plasma using a gas that can be turned into plasma and is capable of generating a plasma-activated gas containing active species of the gas, a cooling unit that is capable of cooling the generated plasma-activated gas, and a dissolution spraying unit that dissolves the plasma-activated gas cooled by the cooling unit into a liquid to generate a solution containing the active species and sprays the solution.

[0003] Active species generated using plasma include reactive oxygen species (ROS) and reactive nitrogen species (RNS) generated from air and nitrogen gas, and carbon dioxide radical anions generated from carbon dioxide gas. These active species are highly reactive and therefore easily lose their activity (deactivation) through interactions with surrounding molecules, resulting in a very short lifespan.

[0004] In order to mix active species into a liquid and use it for treatments such as sterilization, it is necessary to keep the active species in the liquid for a long period of time. In this regard, Patent Document 1 employs a technique in which the temperature of the plasma-treated solution MLp is kept at 10° C. or below, or the plasma-treated solution MLp is once frozen and stored as solid ice MS, which is then thawed to return to a liquid plasma-treated solution and then applied to the object.

[0005] Furthermore, in Patent Document 2, the plasma activated gas can be cooled by a cooling means, and the plasma activated gas cooled by the cooling means is dissolved in a liquid to generate a solution containing active species, which is then sprayed, thereby preventing the short-lived active species in the solution from being deactivated due to a rise in temperature, and maintaining a high sterilization effect.

[0006] Furthermore, Patent Document 3 discloses that a pair of upper and lower electrode plates are arranged in an inclined state, the water to be treated is introduced between the upper and lower electrode plates, porous dielectrics are provided at intervals on the lower electrode plate, and the water to be treated is caused to flow over the lower electrode plate while a barrier discharge is generated between the electrodes, thereby plasma treating the water to be treated.

[0007] International Publication No. WO2013 / 161327, Patent No. 7215726, Patent No. 4635204

[0008] Plasma, particularly atmospheric pressure low-temperature plasma, can be easily generated without requiring a special reduced-pressure environment, and is therefore used to convert various gases into plasma and process various substances. However, the device disclosed in Patent Document 1 requires a mechanism for freezing the liquid to preserve the active species mixed in the liquid, which results in a problem of a complex device configuration. Furthermore, the device disclosed in Patent Document 2 also requires a cooling means to prevent deactivation of the active species, which results in a problem of a complex device configuration, similar to that of Patent Document 1.

[0009] Furthermore, atmospheric pressure low-temperature plasma can also be applied to the decomposition of PFAS (perfluorooctanesulfonic acid) which is currently banned from production and use due to its stability. However, the decomposition of PFOS (perfluorooctanesulfonic acid) and PFOA (perfluorooctanoic acid), which are particularly problematic among PFAS, generally requires plasma treatment for several minutes to about 10 minutes. The method of flowing the water to be treated between inclined electrodes, as in Patent Document 3, has the problem that the required treatment time cannot be secured.

[0010] The present invention has been made to solve the above and other problems, and has as its object to provide a liquid treatment device and a liquid treatment method that are configured to mix various active species generated by atmospheric pressure low-temperature plasma into the liquid to be treated, making it possible to retain them in the liquid for a longer period of time, and to extend the treatment time of the atmospheric pressure low-temperature plasma on the liquid to be treated as much as possible.

[0011] In order to achieve the above and other objects, one aspect of the present invention is a liquid treatment device comprising: a plasma generating unit including a first electrode disposed in a cylindrical space defined by a cylindrically formed dielectric layer; and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween; a power supply unit configured to apply a time-varying voltage signal between the first electrode and the second electrode to generate plasma in the cylindrical space; a gas-liquid mixing unit connected in fluid communication with the cylindrical space, the gas containing active species generated by the plasma being supplied from the cylindrical space, the gas having a flow path through which a liquid to be mixed with the gas flows, the flow path being capable of drawing the gas, the gas containing active species being drawn into the liquid by reducing the pressure caused by the liquid flowing through the flow path, and a microbubble generating unit configured to generate microbubbles containing the active species by reducing the pressure of the liquid into which the gas containing active species from the gas-liquid mixing unit has been mixed.

[0012] Another aspect of the present invention is a liquid treatment method comprising: generating plasma by applying a time-varying voltage signal between a first electrode disposed in a cylindrical space defined by a cylindrically formed dielectric layer and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween; fluidically connecting the cylindrical space and the second electrode, the second electrode being connected to the cylindrical space in a fluid communication state, and supplying a gas containing active species generated by the plasma from the cylindrical space; and having a flow path through which a liquid to be mixed with the gas flows; the flow path being capable of drawing in the gas; the gas containing the active species being sucked into the liquid by a reduced pressure brought about by the liquid flowing through the flow path and mixed therewith; and generating minute bubbles containing the active species by depressurizing the liquid in which the gas containing the active species has been mixed.

[0013] Yet another aspect of the present invention is a liquid treatment system comprising: a liquid tank containing a liquid to be treated, into which a microbubble-containing liquid containing a gas containing active species, generated by the liquid treatment device, is blown; a plasma generation device that applies plasma treatment to the liquid to be treated contained in the liquid tank; and a strip-shaped liquid distribution member that is positioned to penetrate the plasma generated in the plasma generation device, has one end immersed in the liquid to be treated contained in the liquid tank, and the other end is positioned outside the plasma generation device, and sucks up the liquid to be treated from the one end by capillary action, moves it through the plasma over a predetermined time, and releases it from the other end.

[0014] Yet another aspect of the present invention is a liquid treatment method comprising the steps of: injecting a microbubble-containing liquid that encapsulates a gas containing active species into a contained liquid to be treated; sucking up the liquid to be treated using a strip-shaped liquid flow material that has a required void space and generates capillary action; and plasma treating the liquid to be treated that is moving along the liquid flow material.

[0015] According to the present invention, a liquid treatment apparatus and a liquid treatment method are provided which are configured to mix various active species generated by atmospheric pressure low-temperature plasma into the liquid to be treated, allowing them to be retained in the liquid for a longer period of time, and to extend the treatment time of the atmospheric pressure low-temperature plasma on the liquid to be treated as much as possible.

[0016] FIG. 1 is a schematic diagram showing a configuration example of a liquid treatment apparatus according to an embodiment of the present invention. FIG. 2 is a schematic side cross-sectional view of a plasma generation apparatus used in a liquid treatment apparatus according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the plasma generation apparatus of FIG. 2. FIG. 4 is an explanatory diagram of an impedance variable mechanism ZV in the plasma generation apparatus of this embodiment. FIG. 5 is a schematic side cross-sectional view of a microbubble generation apparatus 60 of this embodiment. FIG. 6 is a schematic side cross-sectional view of an ultraviolet irradiation apparatus 50 of this embodiment. FIG. 7 is a schematic cross-sectional view of the ultraviolet irradiation apparatus 50 of FIG. 6. FIG. 8 is a schematic diagram showing a configuration example of a liquid treatment system according to an embodiment of the present invention. FIG. 9A is a schematic longitudinal cross-sectional view showing an example of a configuration of a plasma generation apparatus used in a liquid treatment system according to an embodiment of the present invention. FIG. 9B is a schematic plan view showing an example of a configuration of a plasma generation apparatus used in a liquid treatment system according to an embodiment of the present invention. FIG. 10A is a schematic plan view showing an example of the arrangement of a plasma generation apparatus in a liquid treatment system according to an embodiment of the present invention. FIG. 10B is a schematic plan view showing an example of the arrangement of a plasma generation apparatus in a liquid treatment system according to an embodiment of the present invention. FIG. 11 is a flow diagram showing an example of a treatment flow of a liquid to be treated by the liquid treatment system illustrated in FIG.

[0017] The present invention will be described below with reference to the drawings based on embodiments thereof. Note that the present invention is not limited to the following embodiments. Furthermore, the drawings referred to in the following description merely show the shapes, sizes, and positional relationships in a schematic manner to enable understanding of the contents of the present disclosure. In other words, the present invention is not limited to only the shapes, sizes, and positional relationships exemplified in the drawings.

[0018] [First Embodiment] <Liquid Treatment Apparatus> First, the overall configuration of a liquid treatment apparatus according to one embodiment of the present invention will be described. Fig. 1 schematically shows the overall configuration of a liquid treatment apparatus 1 according to this embodiment. As shown in Fig. 1, the liquid treatment apparatus 1 includes a plasma generation device 10 for generating atmospheric pressure low-temperature plasma, a power supply device 20 for supplying power to the plasma generation device 10, an aspirator 30 as gas suction means, an ultraviolet irradiation device 50 for irradiating ultraviolet rays onto a liquid mixed with plasma-treated gas in the aspirator 30, and a microbubble generation device 60 for rapidly reducing the pressure of the liquid mixed with plasma-treated gas to generate microbubbles.

[0019] 1, a gas to be subjected to plasma treatment is supplied through a conduit 40a connected to an upper opening of a plasma generating device 10 serving as a plasma generating unit. Examples of gases to be subjected to plasma treatment include air, nitrogen, and carbon dioxide. By converting these gases into atmospheric pressure low-temperature plasma, reactive species such as reactive oxygen species (ROS), reactive nitrogen species (RNS), and carbon dioxide radical anions are generated in the gas.

[0020] Although omitted in this embodiment, a flow rate adjusting device may be provided midway along the pipe 40a so as to adjust the flow rate of the gas supplied from the pipe 40a to the plasma generation device 10. The flow rate adjusting device has, for example, a valve device for adjusting the flow rate of the gas passing through the pipe 40a, and the opening degree of the valve device can be adjusted based on a detection value from a pressure sensor provided downstream of the plasma generation device 10.

[0021] The gas activated by atmospheric pressure low-temperature plasma in the plasma generator 10 passes through a pipe 40b connected to the lower opening of the plasma generator 10 and is drawn into the intake port of an aspirator 30, which serves as a gas-liquid mixer and is connected to the other end of the pipe 40b. The active species contained in the gas activated by atmospheric pressure low-temperature plasma are mixed with the liquid to be treated in the aspirator 30.

[0022] The liquid to be treated that has been mixed with the gas containing active species in the aspirator 30 passes through the ultraviolet irradiation device 50 via the conduit 40d, during which time it is irradiated with ultraviolet light in the UV-C band. The liquid to be treated then passes through the microbubble generator 60, during which time it is subjected to a rapid reduction in pressure, generating microbubbles with diameters of less than 1 μm. The active species contained in the plasma-treated gas are encapsulated within these microbubbles. The microbubbles disperse in the liquid and remain as bubbles for a long time, so the encapsulated active species are also retained in the liquid for a long time.

[0023] Next, each of the components constituting the liquid treatment device 1 illustrated in FIG. 1 will be described.

[0024] <Plasma generation device> First, a configuration example of a plasma generation device according to one embodiment of the present invention will be described. Fig. 2 shows a side cross-sectional view of the plasma generation device 10 according to this embodiment, and Fig. 3 shows a transverse cross-sectional view of the plasma generation device 10 of Fig. 2.

[0025] The plasma generation device 10 of this embodiment has a hollow cylindrical shape as a whole and includes a first electrode 14, a second electrode 16, and a dielectric barrier portion 12 as a dielectric layer. The first electrode 14 is formed as a hollow cylindrical conductor. The first electrode 14 is a stainless steel tube made of stainless steel such as SUS304, and can have an outer diameter of approximately 10 mm and an inner diameter of approximately 9 mm, for example. Stainless steel is used as the material because it is resistant to corrosion by the generated plasma and has high durability in the surrounding environment. Another advantage is that it is easy to process, such as by cutting. Any conductive material other than stainless steel may be used as long as it meets these requirements.

[0026] The dielectric barrier section 12 is made of a dielectric material formed into a hollow cylindrical shape, and in this embodiment is formed as a glass tube. However, other dielectric materials, such as resin-based dielectric materials such as fluororesin, may be used as long as they can ensure plasma durability, processability, and the like. The inner diameter of the dielectric barrier section 12 is set to a dimension that allows the cylindrical first electrode 14 to be inserted and slide smoothly. Although a strict fit is not required, a precision is ensured that the first electrode 14 does not rattle when inserted into the dielectric barrier section 12. The thickness of the dielectric barrier section 12 can be, for example, about 1 mm, but specifically, it may be determined based on the relationship with the outer diameter of the first electrode 14 to be fitted.

[0027] The second electrode 16 is provided on the outer periphery of the dielectric barrier section 12 with a certain width in the longitudinal direction. The second electrode 16 is formed, for example, by wrapping a stainless steel plate of a certain width around and attaching it to the outer periphery of the dielectric barrier section 12. The second electrode 16 may be formed from a conductive material other than stainless steel. Furthermore, the second electrode 16 is not limited to a thin plate or thin film material, and a mesh material or the like may also be used.

[0028] 2 , the second electrode 16 is covered with a cover film 18 made of an insulating material to prevent contact with the surrounding air. The cover film 18 is provided by adhering, for example, a polyimide resin to the outer periphery of the dielectric barrier section 12 so as to cover the second electrode 16. By providing this cover film 18, it is possible to prevent plasma from being generated at the end of the second electrode 16 located on the outer periphery of the dielectric barrier section 12.

[0029] As shown in Fig. 1, a power supply device 20 is connected between a first electrode 14 and a second electrode 16 of a plasma generation device 10 according to this embodiment. The power supply device 20 converts DC power received from an external source into high-voltage AC power and applies it between the first electrode 14 and the second electrode 16 of the plasma generation device 10, causing a dielectric barrier discharge between the electrodes to generate atmospheric pressure low-temperature plasma. The input of the power supply device 20 is DC 12 V, and the output is AC power with a frequency of 1 kVp-p and 20 kHz. However, the input / output specifications of the power supply device 20 are not limited to those described above.

[0030] <Operation of Plasma Generating Device> Next, the operation of the plasma generating device 10 having the above-described configuration will be described. Fig. 4 shows a configuration in which a power supply device 20 is connected to the plasma generating device 10 according to the embodiment. Figs. 1 to 3 will also be referred to as appropriate.

[0031] 2 and 3 , in the plasma generation device 10, the first electrode 14 is inserted into the dielectric barrier section 12, and the outer periphery of the first electrode 14 and the inner periphery of the second electrode 16 face each other via the dielectric barrier section 12. When AC power is input between the first electrode 14 and the second electrode 16 from the power supply device 20 in this state, a dielectric barrier discharge occurs between the insertion side end of the first electrode 14 and the inner periphery of the second electrode 16, and atmospheric pressure low temperature plasma P (hereinafter may be simply referred to as "plasma P") is generated at the insertion side end of the first electrode 14, as shown in FIG.

[0032] As shown in FIG. 1 , a gas such as air supplied from the outside flows through a duct 40 a inside the dielectric barrier section 12. When the gas is converted into plasma, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated around the plasma P. A slight airflow is generated in the area where the plasma P is generated. For example, in FIG. 2 , an airflow is generated from the insertion end of the first electrode 14 toward the right in the figure. As a result, the generated reactive species R flow rightward inside the dielectric barrier section 12, and outside air is introduced from the opposite end of the first electrode 14. Note that, because the airflow caused by the generation of the plasma P is very weak, a blower may be provided upstream or downstream of the plasma generation device 10 to forcibly generate an airflow inside the dielectric barrier section 12.

[0033] As shown in FIG. 4 , the plasma generation device 10 according to this embodiment constitutes an impedance variable mechanism ZV by itself. The power supply device 20 includes a DA converter 22 that receives DC input from an external source and converts it into AC power, and a step-up transformer 24 that boosts the AC output of the DA converter 22 to the high voltage required for plasma generation. In this embodiment, the output of the step-up transformer 24 is 1 kVp-p, a high frequency of 20 kHz. If the output impedance, which is mainly determined by the secondary winding of the step-up transformer 24, is mismatched with the load impedance of the plasma generation device 10, the transmission efficiency to the plasma generation device 10 decreases due to reflected waves. In this embodiment, as described with reference to FIG. 2 , the first electrode 14, inserted into the dielectric barrier portion 12, can be slid in the longitudinal direction of the dielectric barrier portion 12 (indicated by symbol S in FIG. 2 ). This sliding can change the length (indicated by symbol L in FIG. 4 ) over which the first electrode 14 and the second electrode 16 face each other via the dielectric barrier portion 12. The portion where the first electrode 14 and the second electrode 16 face each other provides capacitive reactance on the load side, so by sliding the first electrode 14 to change the facing length of the first electrode 14 and the second electrode 16, the load side impedance of the plasma generation device 10 can be changed through the change in capacitive reactance. That is, with an extremely simple configuration in which the relative positional relationship between the first electrode 14 and the second electrode 16, which are components of the plasma generation device 10, is changed, the output impedance of the power supply device 20 used in combination with the plasma generation device 10 and the load side impedance of the plasma generation device 10 can be matched. Note that, as a specific impedance matching method, it is conceivable to measure the relationship between the position of the first electrode 14 with respect to the second electrode 16 and the dielectric barrier discharge current obtained in the plasma generation device 10, and to position the first electrode 14 at a position where the discharge current is maximized.

[0034] In the cylindrical space of the plasma generating device 10, the generated atmospheric pressure low-temperature plasma acts on the air and water vapor, and as is well known, produces, for example, singlet oxygen ( １ O ２ ), ozone (O ３ ), hydroxyl radical (OH), superoxide anion radical (O２ － ), hydroperoxy radical (HO ２ ), hydrogen peroxide (H ２ O ２ ), which generates activated species including various radicals such as argon, argon, and argon. The gas containing these activated species is supplied to the aspirator 30 through a conduit 40b connected downstream of the plasma generator 10. As shown in FIG. 1, a predetermined distance is ensured between the plasma generator 10 and the aspirator 30 by the conduit 40b. This distance prevents unexpected events such as electric leakage from the electrodes of the plasma generator 10 to the liquid to be treated, thereby ensuring the safety of the liquid treatment apparatus 1. The predetermined distance may be determined based on the specifications of the high voltage applied between the electrodes of the plasma generator 10, etc.

[0035] <Power Supply Device> The power supply device 20 has the function of applying a high voltage between the first electrode 14 and the second electrode 16 of the plasma generation device 10. As described above, in this embodiment, the power supply device 20 includes a DA converter 22 that receives DC input from an external source and converts it into AC power, and a step-up transformer 24 that boosts the AC output of the DA converter 22 to the high voltage required for plasma generation. Without being limited to this embodiment, the power supply device 20 may also include a power converter that receives AC 100V, 50 / 60 Hz from a commercial power source and converts the input into the high voltage to be applied between the electrodes. Examples of the power converter include a transformer, an AC / DC converter, or a combination of an AC / DC converter and a DC / AC inverter, which can apply a DC or AC high voltage between the first electrode 14 and the second electrode 16. Any step-up or switching circuit can be used to generate the high voltage. As an example, the power supply device 20 is configured to apply an appropriate high voltage between the first electrode 14 and the second electrode 16. The voltage applied between the electrodes may be either DC or AC, and its frequency may be determined appropriately. The voltage waveform may be an appropriate waveform such as a sine wave.

[0036] <Aspirator> The aspirator 30 is a device for mixing the gas treated by the plasma generation device 10 with the liquid to be treated by the liquid treatment device 1 of this embodiment. As shown in FIG. 1 , the aspirator 30 includes a tubular main body 32 for circulating the liquid to be treated, which is also the working fluid for decompression, and an intake port 34 protruding from the side of the tubular main body 32. Pipes 40c and 40d are connected to the openings at both ends of the tubular main body 32, respectively. The liquid to be treated flows into the aspirator 30 from the pipe 40c side and flows through a venturi V provided in the tubular main body 32 to the pipe 40d side. Pipe 40d is connected to the opening of the intake port 34, so that the gas leaving the plasma generation device 10 is introduced into the aspirator 30. As is well known, the aspirator 30 reduces the pressure in the space surrounding the flow by utilizing the increase in dynamic pressure caused by the increase in the velocity of the fluid passing through the venturi V. In the aspirator 30 shown in FIG. 1, when the liquid to be treated passes through the venturi V, the space communicating with the intake port 34 is depressurized, causing the gas treated by the plasma generator 10 to be drawn into the mixing chamber 36 within the aspirator 30 through the conduit 40b and mixed with the liquid to be treated flowing through the venturi V. A check valve 38 is provided between the mixing chamber 36 and the conduit 40b to prevent the liquid to be treated from flowing into the conduit 40b. Furthermore, the suction action of the aspirator 30 also depressurizes the cylindrical space within the plasma generator 10, making it easier for plasma to be generated between the electrodes in the cylindrical space. If the liquid to be treated is tap water, the conduit 40c may be directly connected to a water supply system, and in Japan, for example, tap water may be supplied at a specified water supply pressure of 0.15 to 0.75 MPa.

[0037] <Ultraviolet Irradiation Device> An ultraviolet irradiation device 50 is connected downstream of the aspirator 30. FIG. 6 shows a schematic side cross-sectional view of the ultraviolet irradiation device 50 of this embodiment, and FIG. 7 shows its cross-sectional view. The ultraviolet irradiation device 50 is a cylindrical device arranged to surround the periphery of the conduit 40d, which is a tube made of a light-transmitting material. A light-emitting diode chip (LED chip) 52 is provided on the inner surface of the tubular body 54. The LED chip 52 is a light-emitting device that emits short-wavelength ultraviolet light in the UV-C band (wavelength 100 to 280 nm) and can be selected from various commercially available products. Specifications such as input voltage, peak wavelength of emitted light, and optical output may be determined according to the specifications of the liquid treatment device 1 to be applied. In the illustrated ultraviolet irradiation device 50 of this embodiment, the inner surface of the tubular body 54 is mirror-finished to increase the efficiency of ultraviolet irradiation of the liquid to be treated passing through the conduit 40d. By irradiating the liquid containing active species to be treated with short wavelength ultraviolet light, new active species are generated, which has the effect of extending the life of the active species.

[0038] <Microbubble Generator> The microbubble generator 60 is provided downstream of the ultraviolet irradiation device 50. The microbubble generator 60 generates microbubbles with diameters of less than 1 μm, in other words, on the order of nanometers, by rapidly reducing the pressure of the liquid to be treated, which has been mixed with active species contained in the gas plasma-treated in the aspirator 30. Ordinary bubbles rise in the liquid and are broken when they reach the interface, but nanometer-order microbubbles remain suspended in the liquid for a long period of time due to the Brownian motion of the liquid molecules.

[0039] As shown in FIG. 5 , the microbubble generator 60 includes a cylindrical casing 62, a swirling flow generating unit 64 fitted inside the casing 62, a nozzle unit 66, and a bubble generating unit 68. As shown, a liquid, such as tap water, mixed with activated species generated by plasma is supplied to the microbubble generator 60 through a conduit 40d. The swirling flow generating unit 64 has, for example, a cylindrical resin molded body with multiple flow paths formed in a spiral around its central axis. The liquid passing through these flow paths forms a swirling flow and flows into the nozzle unit 66. The diameter of the nozzle unit 66 decreases, increasing the flow velocity and dynamic pressure. The liquid discharged from the nozzle unit 66 to the bubble generating unit 68 generates microbubbles due to a sudden decrease in static pressure. By adjusting the flow velocity of the swirling flow and the spatial volume of the bubble generating unit 68, microbubbles B of a desired size can be generated in the bubble generating unit 68. Active species are encapsulated in the microbubbles B, and as described above, the microbubbles B remain in the liquid for a long time. Therefore, the liquid containing the microbubbles B, together with the active species, is delivered to the object to be treated by sterilization, cleaning, or the like.

[0040] <Operation of Liquid Treatment Apparatus> The operation of the liquid treatment apparatus 1 of this embodiment, which has the configuration described above with reference to the related drawings, will be described. Note that the order of the description is for convenience, and the apparatus does not necessarily need to be operated in the order of the description.

[0041] 1. The power supply device 20 is operated to apply a high voltage between the first electrode 14 and the second electrode 16 of the plasma generation device 10, thereby generating a dielectric barrier discharge between the two electrodes. This dielectric barrier discharge generates atmospheric pressure low-temperature plasma P in the cylindrical space within the plasma generation device 10.

[0042] 2. The liquid to be treated is introduced into the aspirator 30 through the conduit 40c. The liquid to be treated is, for example, tap water supplied from a waterworks. As the liquid to be treated passes through the venturi V of the aspirator 30, the pressure inside the mixing chamber 36 of the aspirator 30 is reduced, and plasma-treated gas is introduced into the mixing chamber 36 through the conduit 40b connected to the intake port 34.

[0043] 3. The gas introduced into the mixing chamber 36 of the aspirator 30 is treated by the plasma generator 10 and contains various active species. This plasma-treated gas is mixed with the liquid in the mixing chamber 36. At this time, by adjusting the flow rate of the gas supplied to the aspirator 30 from the conduit 40b, bubbling can be caused, in which the gas is mixed in the form of bubbles into the liquid passing through the aspirator 30. By mixing the gas in such a bubbling state, the various active species contained in the plasma-treated gas can be efficiently introduced into the liquid. The liquid flowing out of the aspirator 30 through the conduit 40d contains the various active species contained in the gas mixed in. This liquid containing active species can be used for various purposes, including sterilization, removal and inactivation of various viruses.

[0044] 4. The liquid containing various active species is irradiated with ultraviolet light in the UV-C range while passing through the ultraviolet irradiation device 50. At this time, oxygen (O ２ ), water molecules (H ２ The action of ultraviolet light on ozone (O ３ ), and further active species such as hydroxyl radicals (OH) are generated. As described above, the ultraviolet irradiation device 50 is not an essential component of the liquid treatment device 1.

[0045] 5. The liquid that has passed through the ultraviolet irradiation device 50 is introduced into the microbubble generator 60. In the microbubble generator 60, the introduced liquid is accelerated as a swirling flow, and the pressure is rapidly reduced in the bubble generating section, generating microbubbles B with diameters of less than 1 μm. Various active species contained in the liquid are encapsulated inside the microbubbles B. Unlike bubbles with diameters exceeding 1 μm, microbubbles on the order of nanometers remain suspended in the liquid for a long time. Therefore, they are retained in the microbubbles and reach the object being treated with the liquid, where they perform functions such as sterilization and surface treatment.

[0046] EXAMPLES The liquid treatment device 1 according to one embodiment of the present invention described above was manufactured according to the following specifications and an experiment was carried out.

[0047] (1) Plasma generation device 10 The dielectric barrier section 12 was composed of a glass tube with an outer diameter of 10 mm and a wall thickness of 1 mm, and the first electrode 14 was made of a stainless steel tube with an outer diameter of approximately 8 mm and a wall thickness of 1 mm so as to fit approximately inside the glass tube. A strip-shaped stainless steel plate with a thickness of 1 mm was wound around the outer periphery of the dielectric barrier section 12 to form the second electrode 16. A cover film 18 was placed over the second electrode 16 to ensure insulation.

[0048] (2) Power Supply Unit 20 A commercial AC power supply of 100 V, 50 Hz was used as input, and an output of 50 Hz frequency and 1 kVp-p voltage was obtained.

[0049] (3) Aspirator 30 A commercially available general-purpose aspirator available from, for example, Nishizawa Laboratory Co., Ltd. was used as the aspirator 30. Tap water was supplied as the liquid to be treated.

[0050] (4) Ultraviolet irradiation device 50 A commercially available UV-C band ultraviolet irradiating LED chip was mounted in a transparent silicone tube and placed around the outer periphery of pipe 40d. The inner circumferential surface of the silicone tube was mirror-finished except for the ultraviolet irradiating portion.

[0051] (5) Microbubble Generator 60 A commercially available microbubble generator was purchased and used.

[0052] By combining the above components and using a simple manual flow control valve to reduce pressure and create bubbling using the aspirator 30, it was confirmed that the plasma-treated air was well mixed with tap water and discharged from the aspirator 30. It was also shown that active species were trapped in the microbubbles B generated by the microbubble generator 60 and remained in the liquid for a long period of time, making it effective for applications such as liquid sterilization and surface treatment.

[0053] According to the embodiment described above, the following effects are achieved.

[0054] A liquid treatment device 1 according to one embodiment of the present invention is provided with: a plasma generation device 10 including a first electrode 14 disposed in a cylindrical space defined by a cylindrically formed dielectric barrier section 12; and a second electrode 16 disposed so as to face the first electrode 14 with the dielectric barrier section 12 interposed therebetween; a power supply device 20 configured to apply a time-varying voltage signal between the first electrode 14 and the second electrode 16 in order to generate plasma in the cylindrical space; an aspirator 30 connected in fluid communication with the cylindrical space, the aspirator 30 having a flow path through which a gas containing active species generated by the plasma is supplied from the cylindrical space and through which a liquid to be mixed with the gas flows, the flow path being capable of drawing the gas, and the aspirator 30 drawing the gas containing active species into the liquid by reducing the pressure caused by the liquid flowing through the flow path and mixing the gas containing active species with the liquid; and a microbubble generator 60 configured to generate microbubbles containing the active species by reducing the pressure of the liquid into which the gas containing active species from the aspirator 30 has been mixed.

[0055] In this way, atmospheric pressure low-temperature plasma is generated in the cylindrical space by dielectric barrier discharge between the first electrode 14 and the second electrode 16, and various active species can be generated from the gas in the cylindrical space. Not only can these active species be efficiently mixed with the liquid to be treated, but the active species can also be trapped in microbubbles and retained in the liquid for a long period of time.

[0056] In the plasma generation device 10, the input impedance may be adjustable by varying the opposing area between the first electrode 14 and the second electrode 16 that face each other with the dielectric barrier section 12 interposed therebetween.

[0057] In this way, plasma can be generated with high efficiency using the power supplied from the power supply device 20 .

[0058] An ultraviolet irradiation device 50 for irradiating the liquid with ultraviolet light of a predetermined wavelength may be provided downstream of the aspirator 30 .

[0059] In this way, the life of the activated species contained in the gas mixed with the liquid in the aspirator 30 can be extended, and new activated species can also be generated by the ultraviolet light.

[0060] In another embodiment of the liquid treatment method of the present invention, plasma is generated by applying a time-varying voltage signal between a first electrode 14 disposed in a cylindrical space defined by a cylindrically formed dielectric barrier section 12 and a second electrode 16 disposed opposite the first electrode 14 with the dielectric barrier section 12 interposed therebetween; a liquid to be mixed with the gas is caused to flow through a flow path connected in fluid communication with the cylindrical space; the gas containing the active species is drawn into and mixed with the liquid from the cylindrical space by the reduced pressure caused by the liquid flowing through the flow path; and microscopic bubbles containing the active species are generated by reducing the pressure of the liquid in which the gas containing the active species has been mixed.

[0061] In this way, the same effects as those of the liquid treatment device of this embodiment can be achieved.

[0062] Second Embodiment Next, a second embodiment of the present invention will be described. The second embodiment relates to a configuration that utilizes the liquid treatment apparatus of the first embodiment while ensuring as long a plasma treatment time as possible for the liquid to be treated, thereby enabling purification of liquids containing stable chemical substances such as PFOA and PFOS that require a relatively long time for decomposition treatment.

[0063] <Liquid Treatment System> A schematic example of the overall configuration of a liquid treatment system according to this embodiment is shown in Fig. 8. The liquid treatment system 100 mainly includes a liquid treatment device 110, a microbubble-mixed liquid supply pipe 120, a filter 130, a liquid storage tank 140, a transfer pump 150, a liquid distribution member 160, a plasma generation device 170, and a treated liquid storage tank 180.

[0064] The liquid treatment device 110 can suitably be, for example, the liquid treatment device 1 in the first embodiment. However, the liquid treatment device 110 is not limited to the configuration of the liquid treatment device 1, as long as it includes a plasma generating unit capable of generating various activated species by plasma processing an appropriate gas and a configuration for mixing microbubbles containing the generated activated species into a liquid. The diameter of the microbubbles is preferably adjusted to, for example, about 1 to 100 μm, so that the microbubbles exhibit the property of rising to the liquid surface together with the fluorine-based compound (PFAS) attached to them due to their affinity for fluorine.

[0065] The microbubble-entrained liquid containing microbubbles in which various active species have been encapsulated by the liquid treatment device 110 is supplied through a microbubble-entrained liquid supply pipe 120 to the bottom of the liquid to be treated stored in a first liquid tank 140A of the liquid storage tank 140, via a filter 130. The filter 130 functions to prevent foreign matter and the like in the liquid tank from flowing back into the liquid treatment device 110. The filter 130 need only be a porous element with a required pore size, and is not limited to a specific type or material.

[0066] The liquid to be treated is, for example, a liquid containing PFOA or PFOS among PFAS. Alternatively, the liquid to be treated may be a liquid containing harmful heavy metals such as lead or cadmium. In general, the liquid to be treated is a liquid that can be purified through treatment with atmospheric pressure low-temperature plasma, which will be described later.

[0067] <Liquid Storage Tank> The liquid storage tank 140 is a container with any desired planar cross-sectional shape and depth, and is divided by a partition wall 141 into a first liquid tank 140A and a second liquid tank 140B. The first liquid tank 140A and the second liquid tank 140B may be provided as separate containers. The first liquid tank 140A concentrates hazardous substances, as described below, and the liquid with a high concentration of hazardous substances (hereinafter referred to as the "intermediate liquid") is transferred to the second liquid tank 140B. The liquid storage tank 140 may also include a single liquid tank. In this case, one end of the liquid flow material 160, described below, is immersed in the liquid to be treated in the single liquid storage tank 140 and draws up the liquid by capillary action. While this configuration does not achieve the effect of increasing the concentration of hazardous substances in the liquid to be treated, it still achieves the basic effect of this embodiment, namely, decomposing hazardous substances using atmospheric pressure low-temperature plasma.

[0068] <Transfer Pump> The transfer pump 150 is a pump for transferring the intermediate liquid concentrated in the first liquid tank 140A to the second liquid tank 140B, and may be of any suitable type as long as it can ensure the required transfer amount that satisfies the processing capacity of the liquid treatment system 100 of this embodiment.

[0069] <Liquid Flow Material> The liquid flow material 160 functions to wick the concentrated intermediate liquid stored in the second liquid tank 140B from the second liquid tank 140B by capillary action. It is preferable that the liquid flow material 160 generates capillary action in the liquid and has a predetermined durability. From this perspective, the liquid flow material 160 can be, for example, a cloth made of inorganic fibers such as glass fiber, ceramic fiber, or silicon fiber, or a nonwoven fabric made of chemical fibers with a predetermined durability. The liquid wicking capacity of the liquid flow material 160 varies depending on the size of the voids between the fibers, the properties of the fiber surface, etc., and can be determined experimentally. The liquid flow material 160 has a flat, band-like planar shape and can have a thickness of, for example, approximately 4 to 5 mm. The width of the liquid flow material 160 can be set to match the dimensions of the plasma generation device described below.

[0070] <Plasma Generation Device> The plasma generation device 170 performs plasma treatment using atmospheric pressure low-temperature plasma on the intermediate liquid that is sucked up from the second liquid tank 140B by the liquid flowing member 160 and moves through the liquid flowing member 160. The plasma generation device 170 of this embodiment has a frame 171 having a flat, hollow, box-like structure, with plate electrodes 172A and 172B provided above and below the hollow portion. The upper plate electrode 172A is provided with a dielectric layer 173 covering its entire surface. The dielectric layer 173 is provided to generate a stable dielectric barrier discharge between the plate electrodes 172A and 172B. The dielectric layer 173 may be provided on the lower plate electrode 172B side, or on both the upper and lower plate electrodes 172A and 172B. The plate electrodes 172A and 172B can be made of various conductive materials, but are preferably formed from metal plates such as copper, aluminum, or stainless steel. The dielectric layer 173 can be made of various materials that do not cause dielectric breakdown when subjected to high AC voltage and have the required heat resistance, and glass, for example, is preferably used.

[0071] A power supply unit 175 is connected between the plate electrodes 172A and 172B. The power supply unit 175 includes a conversion circuit that receives, for example, commercial AC power and converts it into a pulse voltage required to generate a dielectric barrier discharge. The pulse voltage supplied from the power supply unit 175 to the plate electrodes 172A and 172B has, for example, a frequency of 50 Hz and a voltage of 1 kVp-p, but is not limited thereto and may be designed to conform to the specifications of the plasma generation device 170.

[0072] In the hollow portion of the frame 171 of the plasma generation device 170, the liquid flow material 160 is placed so as to penetrate the frame 171 and contact the lower plate electrode 172B or the upper surface of the dielectric layer 173. On the right-hand side of FIGS. 10A and 10B , the liquid flow material 160 is immersed in the second liquid tank 141A, as illustrated in FIG. 8 . Meanwhile, the other end (on the left-hand side of FIG. 10A , etc.) of the liquid flow material 160 is an open end outside the frame 171 of the plasma generation device 170. With this configuration, the liquid sucked up from the second liquid tank 141B by the capillary phenomenon exhibited by the liquid flow material 160 moves along the liquid flow material 160 within the frame 171 of the plasma generation device 170. During this time, the moving liquid comes into contact with the plasma atmosphere, and chemical substances such as PFOA and PFOS and heavy metals contained therein are removed. The entire plasma generator 170 can be rotated around a support shaft 174, and a fixing means (not shown) can be used to set a desired downward gradient from the liquid inlet to the liquid outlet. This allows the slope component of gravity acting on the liquid to be adjusted, thereby adjusting the time required for the liquid to pass through the plasma generator 170. The time required for the liquid to pass through the plasma generator 170 can be set to be equal to or longer than the time required to decompose toxic substances such as PFAS contained in the liquid to be treated. Note that the liquid suction power varies depending on the material and properties of the liquid flow material 160, so the relative positional relationship between the second liquid tank 141B and the plasma generator 170 can be adjusted accordingly.

[0073] <Liquid Treatment by Liquid Treatment System 100> Next, a treatment flow of the liquid to be treated by the liquid treatment system 100 of this embodiment having the above configuration example will be described. Fig. 11 is a flowchart showing an example of the treatment flow of the liquid to be treated by the liquid treatment system 100.

[0074] First, by turning on the power of the liquid treatment device 110, a liquid (typically water) containing microbubbles encapsulating various active species is generated in the liquid treatment device 110. The generated microbubble-containing liquid is discharged near the bottom of the liquid to be treated, which contains harmful substances such as PFOS and PFOA and is stored in the first liquid tank 140A through the supply pipe 120 and the filter 130. At this time, the microbubbles discharged into the first liquid tank 140A rise toward the surface of the liquid to be treated stored in the first liquid tank 140A. During this process, the PFOS and PFOA contained in the liquid to be treated are adsorbed to the microbubbles due to the affinity of fluorine and rise toward the liquid surface. This produces a concentration effect in the liquid to be treated in the first liquid tank 140A, increasing the concentrations of PFOA and PFOS near the liquid surface.

[0075] In step S13, the supernatant liquid concentrated in the first liquid tank 140A is transferred to the second liquid tank 140B by the transfer pump 150. In step S14, the liquid to be treated, which has been transferred to and stored in the second liquid tank 140B and contains a high concentration of PFOA, is sucked up by the capillary action of the liquid flow material 160 and moves toward the plasma generation device 170.

[0076] In step S15, the liquid to be treated moves along the glass fiber cloth serving as the liquid flow material 160, which slopes downward from the inlet side to the outlet side of the plasma generation device 170. During this time, while the liquid to be treated passes between the plate electrodes 172A, 172B of the plasma generation device 170, it is exposed to atmospheric pressure low-temperature plasma generated throughout the space between the plate electrodes 172A, 172B by dielectric barrier discharge, and PFOA and PFOS are decomposed.

[0077] In step S16, the plasma-treated liquid that has been plasma-treated while moving within the glass fiber cloth liquid flow material 160 drips from the open end of the liquid flow material 160 into the container 180 and is stored therein.

[0078] In step S17, the concentrations of harmful substances such as PFOA and PFOS in the plasma-treated liquid stored in the container 180 are measured.

[0079] In step S18, the output of the plasma generating device 170 and the set downward gradient inclination angle of the plasma generating device 170 are adjusted based on the concentration of harmful substances in the plasma-treated liquid measured in step S17.

[0080] The liquid treatment system 100 of the present embodiment described above comprises a liquid tank 140 in which a liquid to be treated is accommodated, and into which a microbubble-containing liquid encapsulating a gas containing active species, which is produced by the liquid treatment device, is released; a plasma generation device 170 that applies plasma treatment to the liquid to be treated contained in the liquid tank 140; and a strip-shaped liquid distribution member 160 that is arranged to pass through the plasma generated in the plasma generation device 170, has one end immersed in the liquid to be treated contained in the liquid tank 140, and has the other end arranged outside the plasma generation device 170, and sucks up the liquid to be treated from the one end by capillary action, moves it through the plasma over a predetermined time, and releases it from the other end.

[0081] In this way, harmful substances can be decomposed by performing plasma treatment for the required time using the plasma generating device 170. Furthermore, the liquid to be treated can be moved from the liquid tank 140 to the plasma generating device 170 without using power, realizing a simple configuration with excellent energy efficiency.

[0082] The liquid tank 140 comprises a first liquid tank 140A and a second liquid tank 140B, in which the microbubble-containing liquid is released into the liquid to be treated at the bottom of the first liquid tank 140A, and in which the liquid to be treated that is pumped up from near the liquid surface of the first liquid tank 140A is transferred and stored in the second liquid tank 140B, and one end of the liquid flow material 160 is immersed in the liquid to be treated contained in the second liquid tank 140B.

[0083] In this way, the concentration of harmful substances contained in the liquid to be treated by the plasma treatment can be increased, and the efficiency of treating the liquid can be improved.

[0084] The plasma generating device 170 comprises a pair of flat plate electrodes arranged facing each other at a predetermined distance in the vertical direction, and a power supply unit 175 for applying a predetermined voltage between the flat plate electrodes, and the liquid flow material 160 can be placed in contact with the lower flat plate electrode 172B.

[0085] In this way, the desired plasma treatment can be performed on the liquid to be treated that moves within the liquid flowing member 160.

[0086] The liquid flow material suitably has a required void that generates a capillary phenomenon that draws up the liquid.

[0087] In this way, the liquid flow material can be given the required liquid absorbing ability.

[0088] The plurality of plasma generating devices can be arranged in series along the flow direction of the liquid to be treated, or in parallel so as to be perpendicular to the flow direction.

[0089] In this way, the amount of liquid to be treated that can be treated by the plasma generating device can be increased, and the treatment efficiency can be improved.

[0090] The liquid treatment method of this embodiment also includes the steps of blowing a microbubble-containing liquid that encapsulates a gas containing active species into the contained liquid to be treated, sucking up the liquid to be treated using a strip-shaped liquid flow material 160 that has the required voids and generates capillary action, and plasma treating the liquid to be treated that is moving along the liquid flow material 160.

[0091] In this way, harmful substances contained in the liquid to be treated can be decomposed by the plasma treatment.

[0092] The method may include a step of injecting a microbubble-containing liquid that encapsulates a gas containing active species into the bottom of the contained liquid to be treated, a step of pumping the contained liquid to be treated from near the liquid surface and storing it in a second liquid tank 140B, and a step of sucking up the liquid to be treated from the second liquid tank 140B using the liquid flow material 160.

[0093] In this way, harmful substances contained in the liquid to be treated can be decomposed by plasma treatment in a state where the concentration of the harmful substances is increased, thereby improving the treatment efficiency.

[0094] Although several embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take various other embodiments, and it is also possible to combine the configurations of the above embodiments and modifications. Furthermore, various modifications such as omissions and substitutions can be made without departing from the spirit of the present invention. These embodiments and modifications thereof are included within the scope and spirit of the invention described in this specification, etc., and are included in the invention described in the claims and their equivalents.

[0095] For example, in the first embodiment, the first electrode 14 and the second electrode 16 are not limited to the nested configuration as in the above-described embodiment, as long as they have a configuration suitable for generating atmospheric pressure low-temperature plasma by dielectric barrier discharge.

[0096] REFERENCE SIGNS LIST 1, 110 Liquid treatment device 10, 170 Plasma generation device 12 Dielectric barrier unit 14 First electrode 16 Second electrode 20 Power supply device 30 Aspirator 50 Ultraviolet irradiation device 60 Microbubble generation device 100 Liquid treatment system 140 Liquid storage tank 140A First liquid tank 140B Second liquid tank 160 Liquid flow material 180 Treated liquid storage tank

Claims

1. A liquid treatment device comprising: a plasma generating unit having a first electrode disposed in a cylindrical space defined by a cylindrically formed dielectric layer, and a second electrode disposed opposite the first electrode with the dielectric layer interposed therebetween; a power supply unit which applies a time-varying voltage signal between the first electrode and the second electrode in order to generate plasma in the cylindrical space; a gas-liquid mixing unit which is connected in fluid communication with the cylindrical space, and through which a gas containing active species generated by the plasma is supplied from the cylindrical space and which has a flow path through which a liquid to be mixed with the gas flows, the flow path being capable of drawing in the gas, and which draws the gas containing active species into the liquid by reducing the pressure brought about by the liquid flowing through the flow path, and a microbubble generating unit which generates microbubbles containing active species by reducing the pressure of the liquid into which the gas containing active species from the gas-liquid mixing unit has been mixed.

2. A liquid treatment device as described in claim 1, wherein the input impedance of the plasma generating section is adjustable by varying the opposing area between the first electrode and the second electrode which face each other via the dielectric.

3. The liquid treatment device according to claim 1 or 2, further comprising an ultraviolet irradiating section downstream of said gas-liquid mixing section for irradiating said liquid with ultraviolet light of a predetermined wavelength.

4. A liquid treatment method comprising the steps of: generating plasma by applying a time-varying voltage signal between a first electrode disposed in a cylindrical space defined by a cylindrically formed dielectric layer and a second electrode disposed opposite the first electrode via the dielectric layer; flowing a liquid to be mixed with the gas through a flow path connected in fluid communication with the cylindrical space; sucking the gas containing the active species from the cylindrical space into the liquid by the reduced pressure caused by the liquid flowing through the flow path and mixing it with the liquid; and generating minute bubbles containing the active species by reducing the pressure of the liquid in which the gas containing the active species has been mixed.

5. A liquid treatment system comprising: a liquid tank containing a liquid to be treated, into which a microbubble-containing liquid encapsulating a gas containing active species, produced by the liquid treatment device according to claim 1, is blown; a plasma generation device which applies plasma treatment to the liquid to be treated contained in the liquid tank; and a strip-shaped liquid distribution material which is disposed so as to penetrate through plasma generated by the plasma generation device, has one end immersed in the liquid to be treated contained in the liquid tank and has the other end disposed outside the plasma generation device, and sucks up the liquid to be treated from the one end by capillary action, moves it through the plasma over a predetermined period of time, and releases it from the other end.

6. A liquid treatment system as described in claim 5, wherein the liquid tank comprises a first liquid tank and a second liquid tank, in which the microbubble-containing liquid is released into the liquid to be treated at the bottom of the first liquid tank, in which the liquid to be treated that is pumped up from near the liquid surface of the first liquid tank is transferred and stored, and the one end of the liquid flow material is immersed in the liquid to be treated contained in the second liquid tank.

7. A liquid treatment system as described in claim 5, wherein the plasma generating device comprises a pair of flat plate electrodes arranged facing each other at a predetermined distance in the vertical direction, and a power supply device for applying a predetermined voltage between the flat plate electrodes, and the liquid flow material is placed in contact with the lower flat plate electrode.

8. The liquid treatment system according to claim 5, wherein the liquid flow material has a predetermined gap that generates a capillary phenomenon that draws up the liquid.

9. The liquid treatment system according to claim 5, wherein a plurality of said plasma generating devices are arranged in series along a flow direction of the liquid to be treated, or in parallel so as to be perpendicular to said flow direction.

10. A liquid treatment method comprising the steps of: blowing a liquid containing microbubbles that encapsulate a gas containing active species into a contained liquid to be treated; sucking up the liquid to be treated using a strip-shaped liquid flow material that has the required gaps and generates capillary action; and plasma treating the liquid to be treated that moves along the liquid flow material.

11. A liquid treatment method as described in claim 10, comprising the steps of: injecting a liquid containing microbubbles that encapsulate a gas containing an active species into the bottom of the contained liquid to be treated; pumping the contained liquid to be treated from near the liquid surface and storing it in another container; and sucking up the liquid to be treated from the other container using the liquid flow material.

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