TREATMENT DEVICE, STERILIZATION DEVICE, STERILIZATION WATER, AND STERILIZATION METHOD

Abstract

A treatment apparatus and a sterilization apparatus each include a liquid reservoir portion configured to store a treatment subject liquid, a plasma generation portion configured to generate a plasma on or above a liquid surface of the treatment subject liquid, and a bubble supply portion configured to generate a bubble containing the generated plasma on or above the liquid surface and configured to supply the bubble into the treatment subject liquid. Thus, the plasma is generated on or above the liquid surface of the treatment subject liquid, and the bubble containing the generated plasma is generated and supplied into the treatment subject liquid.

Claims

1. A treatment apparatus comprising: a housing, a liquid reservoir portion formed in a lower portion of the housing, and configured to store a treatment subject liquid, a circulation flow path containing a liquid distribution portion formed on an upper portion of the housing, and circulating the treatment subject liquid in the liquid reservoir portion into the liquid distribution portion, at least one plasma generation portion configured to generate a plasma on or above a liquid surface of the treatment subject liquid in the liquid reservoir portion, and a plurality of bubble supply portions each including an aspirator being hung down from the liquid distribution portion toward the liquid reservoir portion and configured to return the treatment subject liquid in the liquid distribution portion to the liquid reservoir portion, each of the bubble supply portions configured to generate a bubble containing the generated plasma on or above the liquid surface of the liquid reservoir portion and to supply the bubble into the treatment subject liquid, wherein each of the bubble supply portions is configured to introduce the plasma from the plasma generation portion through a venturi portion of the aspirator to generate the bubble.

2. The treatment apparatus according to claim 1, wherein the treatment subject liquid is controlled to be an acidic liquid.

3. The treatment apparatus according to claim 1, wherein: the treatment apparatus has a space formed on or above the liquid surface of the treatment subject liquid, a plasma generating gas is introduced into the space, the plasma generation portion and the bubble supply portion are placed in the space, and the plasma generation portion is configured to generate the plasma based on introduction of the plasma generating gas into the space.

4. The treatment apparatus according to claim 1, wherein the treatment apparatus contains at least one combination of the one plasma generation portion and a plurality of the bubble supply portions.

5. The treatment apparatus according to claim 4, wherein the plurality of bubble supply portions are arranged on a circle centered at the one plasma generation portion or arranged circularly around the one plasma generation portion.

6. A sterilization apparatus comprising: a housing, a liquid reservoir portion formed in a lower portion of the housing, and configured to store a treatment subject liquid, a circulation flow path containing a liquid distribution portion formed on an upper portion of the housing, and circulating the treatment subject liquid in the liquid reservoir portion to the liquid distribution portion, at least one plasma generation portion configured to generate a plasma on or above a liquid surface of the treatment subject liquid in the liquid reservoir portion, and a plurality of bubble supply portions each including an aspirator being hung down from the liquid distribution portion toward the liquid reservoir portion and configured to return the treatment subject liquid in the liquid distribution portion to the liquid reservoir portion, each of the bubble supply portions configured to generate a bubble containing the generated plasma on or above the liquid surface of the liquid reservoir portion and to supply the bubble into the treatment subject liquid, wherein each of the bubble supply portions is configured to introduce the plasma from the plasma generation portion through a venturi portion of the aspirator to generate the bubble.

7. The sterilization apparatus according to claim 6, wherein the treatment subject liquid is controlled to be an acidic liquid.

8. A sterilization water produced by a sterilization apparatus comprising: a housing, a liquid reservoir portion formed in a lower portion of the housing, and configured to store a treatment subject liquid, a circulation flow path containing a liquid distribution portion formed on an upper portion of the housing, and circulating the treatment subject liquid in the liquid reservoir portion to the liquid distribution portion, at least one plasma generation portion configured to generate a plasma on or above a liquid surface of the treatment subject liquid in the liquid reservoir portion, and a plurality of bubble supply portions each including an aspirator being hung down from the liquid distribution portion toward the liquid reservoir portion and configured to return the treatment subject liquid in the liquid distribution portion to the liquid reservoir portion, each of the bubble supply portions configured to generate a bubble containing the generated plasma on or above the liquid surface of the liquid reservoir portion and to supply the bubble into the treatment subject liquid, wherein each of the bubble supply portions is configured to introduce the plasma from the plasma generation portion through a venturi portion of the aspirator to generate the bubble.

9. The sterilization water according to claim 8, wherein the treatment subject liquid is controlled to be an acidic liquid.

10. A sterilization method comprising the steps of: circulating a treatment subject liquid stored in a liquid reservoir portion to a liquid distribution portion formed on an upper portion of a housing, returning the treatment subject liquid, which is circulated to the liquid distribution portion, to the liquid reservoir portion through a plurality of bubble supply portions each including an aspirator being hung down from the liquid distribution portion toward the liquid reservoir portion, generating a plasma on or above a liquid surface of the treatment subject liquid in the liquid reservoir portion, and supplying a bubble containing the plasma generated in the plasma generating step into the treatment subject liquid, the bubble being generated on or above the liquid surface in the liquid reservoir portion, wherein in the bubble supplying step, the plasma generated in the plasma generating step is introduced through a venturi portion of the aspirator to generate the bubble.

11. The sterilization method according to claim 10, wherein the treatment subject liquid is controlled to be an acidic liquid.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] FIG. 1 is a schematic structural view of a treatment apparatus according to a first embodiment (a first treatment apparatus);

[0042] FIG. 2 is a schematic structural view from above of the first treatment apparatus;

[0043] FIG. 3 is an explanatory view of a structure of a plasma generation portion and a bubble supply portion;

[0044] FIG. 4 is a front view of a structure of a first discharge electrode and a second discharge electrode in a discharge electrode portion;

[0045] FIG. 5 is a schematic structural view of a treatment apparatus according to a second embodiment (a second treatment apparatus); and

[0046] FIG. 6 is a schematic structural view from above of the second treatment apparatus.

DESCRIPTION OF EMBODIMENTS

[0047] Several embodiments of the treatment apparatus, the sterilization apparatus, the sterilization water, and the sterilization method of the present invention will be described below with reference to FIGS. 1 to 6.

[0048] As shown in FIGS. 1 and 2, a treatment apparatus according to a first embodiment of the present invention (hereinafter referred to as the first treatment apparatus 10A) has a liquid reservoir portion 14 for storing a treatment subject liquid 12, plasma generation portions 16 for generating a plasma on or above a liquid surface 12a of the treatment subject liquid 12, and bubble supply portions 20 for generating bubbles 18 containing the generated plasma on or above the liquid surface 12a and for supplying the bubbles 18 into the treatment subject liquid 12. The treatment subject liquid 12 is an acidic liquid. For example, the pH value of the treatment subject liquid 12 is controlled at 4.8 or less. The term on or above the liquid surface 12a means at the same level as the liquid surface 12a or above the liquid surface 12a.

[0049] More specifically, for example, the first treatment apparatus 10A has a rectangular housing 22. The housing 22 has an upper surface 24a, a lower surface 24b, and four side surfaces (a first side surface 26a to a fourth side surface 26d). In the housing 22, for example, a gas inlet 28 is formed on the first side surface 26a, and a gas outlet 30 is formed on a second side surface 26b opposite to the first side surface 26a. The liquid reservoir portion 14 is formed in a lower portion of the housing 22. In the housing 22, a space 34, into which a plasma generating gas 32 is introduced, is formed on or above the liquid surface 12a of the treatment subject liquid 12. The plasma generating gas 32 is supplied through the gas inlet 28 into the space 34 and is discharged through the gas outlet 30.

[0050] For example, on the second side surface 26b of the housing 22, a circulation flow path 36 for circulating the treatment subject liquid 12 extends from the liquid reservoir portion 14.

[0051] The circulation flow path 36 contains a liquid distribution portion 38 formed on an upper portion of the housing 22, and further contains a connection flow path 40 for connecting the liquid distribution portion 38 to the liquid reservoir portion 14. The connection flow path 40 extends outside of the second side surface 26b of the housing 22. For example, the treatment subject liquid 12 in the liquid reservoir portion 14 is drawn through the connection flow path 40 into the liquid distribution portion 38 by a pump (not shown). The pump may be a non-special common drawing pump.

[0052] The treatment subject liquid 12 in the liquid reservoir portion 14 is drawn by the pump through the connection flow path 40 into the upper liquid distribution portion 38. The drawn treatment subject liquid 12 is supplied into the liquid reservoir portion 14 again. Thus, the treatment subject liquid 12 is circulated through the circulation flow path 36 into the liquid reservoir portion 14. Incidentally, as viewed from the upper surface of the housing 22, the area of the liquid distribution portion 38 is approximately equal to that of the liquid reservoir portion 14.

[0053] Meanwhile, each of the bubble supply portions 20 extends from the liquid distribution portion 38 in the circulation flow path 36 toward the liquid reservoir portion 14. For example, the bubble supply portion 20 preferably contains an aspirator 44 having a venturi portion 42. An upper end 44a of the aspirator 44 is connected to the liquid distribution portion 38, and a lower end 44b is located on or above the liquid surface 12a of the treatment subject liquid 12. Thus, the aspirator 44 is hung down from the liquid distribution portion 38. The first treatment apparatus 10A contains a plurality of the aspirators 44. In the example of FIG. 2, four lines of the aspirators 44 are arranged from the first side surface 26a toward the second side surface 26b, four rows of the aspirators 44 are arranged from a third side surface 26c toward the fourth side surface 26d, and thus the first treatment apparatus 10A contains sixteen aspirators 44 in total.

[0054] The plasma generation portion 16 is disposed on the venturi portion 42 in each of the aspirators 44. As shown in FIG. 3, each plasma generation portion 16 contains a casing 46, e.g., having a cylindrical shape, formed on the venturi portion 42, and further contains a discharge electrode portion 48 placed in the casing 46. In the casing 46, the area having the discharge electrode portion 48 is a plasma generation area 49. The casing 46 has a gas inlet 50 for introducing the plasma generating gas 32 and a through-hole 52 connected to the venturi portion 42. The inner space of the casing 46 is connected with the inner portion of the aspirator 44 by the through-hole 52. In the example of FIG. 2, the casings 46 (the gas inlets 50) in the plasma generation portions 16 are oriented in the same direction. The arrangement of the casings 46 is not limited thereto, and the casings 46 may be oriented in different directions.

[0055] A high-voltage pulse is applied from a pulse power supply 54 to the discharge electrode portion 48. The pulse power supply 54 may be attached to each of the plasma generation portions 16. Alternatively, one common pulse power supply 54 may be attached to a plurality of the plasma generation portions 16. In FIGS. 1 and 2, the pulse power supply 54 is not shown.

[0056] As shown in FIG. 4, the discharge electrode portion 48 contains a first discharge electrode 56A used as a positive electrode and a second discharge electrode 56B used as a negative electrode. The first discharge electrode 56A and the second discharge electrode 56B are arranged at a distance from each other along the flow direction. The fluid flows in the direction, in which the intensity of the electric field generated between the first discharge electrode 56A and the second discharge electrode 56B is maximized. Therefore, generation efficiency of the active species can be improved. The discharge electrode portion 48 may have the two-stage structure containing the first discharge electrode 56A and the second discharge electrode 56B, and may have a multi-stage structure such as a three-stage structure.

[0057] The first discharge electrode 56A contains a plurality of rod-shaped first conductors 58A, which extend in a first direction (an x direction) and are arranged in a second direction (a y direction) perpendicular to the first direction. The first discharge electrode 56A further contains a first common conductor 60A for connecting the plurality of first conductors 58A, and further contains first ceramic layers 62A applied to at least the first conductors 58A.

[0058] The second discharge electrode 56B contains a plurality of rod-shaped second conductors 58B, which extend in the second direction (the y direction) and are arranged in the first direction (the x direction). The second discharge electrode 56B further contains a second common conductor 60B for connecting the plurality of second conductors 58B, and further contains second ceramic layers 62B applied to at least the second conductors 58B.

[0059] The first conductor 58A and the second conductor 58B may contain copper, iron, tungsten, stainless steel, platinum, etc. The first ceramic layer 62A and the second ceramic layer 62B may contain alumina, silica, titania, zirconia, etc.

[0060] The operation of the first treatment apparatus 10A will be described below with reference to FIGS. 1 and 2. For example, the pump is driven to circulate the treatment subject liquid 12. Meanwhile, the pulse power supply 54 (see FIG. 3) is activated to generate the plasma in each plasma generation portions 16. Furthermore, the plasma generating gas 32 is supplied through the gas inlet 28 into the space 34 in the housing 22.

[0061] The treatment subject liquid 12 is drawn by the pump into the upper liquid distribution portion 38, transferred through the aspirators 44 in the bubble supply portions 20, and then returned to the liquid reservoir portion 14. This process is repeated to circulate the treatment subject liquid 12.

[0062] When the treatment subject liquid 12 flows through the venturi portion 42 in each aspirator 44, the flow speed is increased and the pressure is lowered due to the venturi effect in the venturi portion 42. Therefore, the plasma generating gas 32 supplied into the space 34 is drawn into each plasma generation portion 16, and introduced through the casing 46 into the venturi portion 42. The plasma is generated in the plasma generation portion 16, and introduced together with the plasma generating gas 32 into the low-pressure venturi portion 42. Consequently, the bubbles 18 containing the plasma are generated in the treatment subject liquid 12 in the venturi portion 42. The treatment subject liquid 12 containing the bubbles 18 is returned through the aspirator 44 to the treatment subject liquid 12 in the liquid reservoir portion 14.

[0063] The plasma is generated on or above the liquid surface 12a of the treatment subject liquid 12, the bubbles 18 containing the generated plasma are generated on or above the liquid surface 12a, and the generated bubbles 18 are supplied into the treatment subject liquid 12. Therefore, the bubbles 18 containing the plasma can be supplied into the treatment subject liquid 12 without immersing the first treatment apparatus 10A per se in the treatment subject liquid 12. Consequently, the number of the first treatment apparatuses 10A is not limited by the volume of the vessel for the treatment subject liquid 12 (in this case, the liquid reservoir portion 14) and can be easily increased. Furthermore, the concentration of the bubbles 18 to be supplied into the treatment subject liquid 12, i.e., the bubble amount (number) per unit volume, can be increased.

[0064] In general, when the treatment subject liquid 12 is controlled to be acidic and when a treatment target material is immersed in the acidic treatment subject liquid 12, the treatment target material is damaged by the acidic treatment subject liquid 12. In contrast, in this embodiment, because the concentration of the bubbles 18 which is supplied into the treatment subject liquid 12 can be increased, the damage to the treatment target material can be reduced. Furthermore, when the treatment subject liquid 12 is controlled to be acidic and when the bubbles 18 are supplied into the acidic treatment subject liquid 12, the gas in the bubbles 18 can be dissolved more rapidly, and a plasma active species or a reaction product derived therefrom can be efficiently dissolved in the acidic treatment subject liquid 12. In addition, when the treatment subject liquid 12 is controlled to be acidic, the bubbles 18 exhibit a lower resistance (contact resistance) to the acidic treatment subject liquid 12, so that the bubbles 18 can be readily transferred in the acidic treatment subject liquid 12. Consequently, the plasma active species or the reaction product derived therefrom can be widely spread in a short time, the concentration of the plasma active species or the reaction product derived therefrom can be increased in the treatment subject liquid 12.

[0065] The treatment subject liquid 12 which is supplied into the liquid reservoir portion 14 is used as the treatment subject liquid 12 circulated from the liquid reservoir portion 14, i.e., the treatment subject liquid 12 supplied with the bubbles 18 containing the plasma. Therefore, the amount (number) of the bubbles 18 per unit volume can be increased, and the concentration (amount per unit volume) of the plasma active species or the reaction product derived therefrom can be increased in the treatment subject liquid 12.

[0066] By appropriately selecting the diameter and the like of the venturi portion 42, a microbubble having a diameter of 50 m or less can be generated as the bubble 18.

[0067] In the case of using the microbubble, the contact area between the treatment subject liquid 12 and the plasma active species or the reaction product derived therefrom can be increased. Furthermore, the inner pressure and the solubility can be increased due to the downsizing of the bubble 18, whereby the plasma active species or the reaction product derived therefrom can be efficiently dissolved in the treatment subject liquid 12.

[0068] In the first treatment apparatus 10A, most of the plasma generated in the one plasma generation portion 16 can be introduced through the one bubble supply portion 20 into the treatment subject liquid 12, whereby a large number of the bubbles 18 can be generated in the treatment subject liquid 12.

[0069] An oxygen-containing gas, a nitrogen-containing gas, a mixture gas of oxygen and nitrogen, or the like may be used as the plasma generating gas 32. In this case, radicals having a high sterilization effect can be generated by the plasma. Therefore, the radicals having the sterilization effect can be widely spread in the treatment subject liquid 12 in a short time, the concentration of the radicals can be increased in the treatment subject liquid 12, and for example a sterilization water having a high sterilization effect can be produced from the treatment subject liquid 12. Thus, the first treatment apparatus 10A can be used as a sterilization apparatus 70 for producing the sterilization water having the high sterilization effect.

[0070] A treatment apparatus according to a second embodiment (hereinafter referred to as a second treatment apparatus 10B) will be described below with reference to FIGS. 5 and 6.

[0071] As shown in FIGS. 5 and 6, the second treatment apparatus 10B has approximately the same structure as the first treatment apparatus 10A, and is different in that it contains at least one combination of one plasma generation portion 16 and a plurality of the bubble supply portions 20.

[0072] Specifically, a plurality of the bubble supply portions 20 are arranged on a circle centered at the one plasma generation portion 16 (or arranged circularly around the one plasma generation portion 16). In the example of FIG. 6, four bubble supply portions 20 are arranged on a circle 64 (shown by a two-dot chain line) centered at the one plasma generation portion 16. As shown in FIGS. 5 and 6, the casing 46 has the gas inlet 50, a gas guide portion 66 for introducing the plasma generating gas 32 into the plasma generation area 49, and a branched portion 68 for introducing the gas containing the plasma from the plasma generation area 49 into the venturi portions 42 in the four bubble supply portions 20.

[0073] The second treatment apparatus 10B has the same advantageous effects as the first treatment apparatus 10A.

[0074] In particular, in the second treatment apparatus 10B, the plasma generated in the one plasma generation portion 16 can be introduced through the plurality of bubble supply portions 20 into the treatment subject liquid 12, whereby a large number of the bubbles 18 can be dispersed and supplied into the treatment subject liquid 12.

[0075] The plasma generated in the one plasma generation portion 16 can be distributed approximately uniformly in the plurality of the bubble supply portions 20 arranged circularly. Thus, the one plasma generation portion 16 can be used with the plasma generation area 49 for the plurality of bubble supply portions 20. The number of the plasma generation areas 49 can be reduced, and the structure of the second treatment apparatus 10B can be simplified. In addition, a large amount of the bubbles 18 can be efficiently dispersed in the treatment subject liquid 12, and for example, the radical concentration can be rapidly uniformized in the treatment subject liquid 12.

[0076] The treatment apparatus, the sterilization apparatus, the sterilization water, and the sterilization method of the present invention are not particularly limited to the aforementioned embodiments. Various changes and modifications may be made to the embodiments without departing from the scope of the invention.