JP2018064586A - Sterilizer for liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet sterilization method and an ultraviolet sterilization device capable of effectively conducting ultraviolet sterilization on a liquid containing organic products, for example vegetable juice without deteriorating flavor thereof.SOLUTION: When sterilization is conducted by irradiating ultraviolet to a liquid to be sterilized consisting of a solution or a dispersion containing organic products, ultraviolet ray in a wavelength range of 253 nm to 280 nm is selectively irradiated to the liquid to be sterilized without contacting the liquid to be sterilized which exists in an area in which the ultraviolet ray is irradiated with an optical catalyst substance. At this time, the ultraviolet ray is irradiated from one direction or two directions opposing each other, and further width of an optical axis direction of the ultraviolet ray irradiated in the area is preferably set at a width with that the ultraviolet ray is irradiated to all of liquid to be sterilized existing in the area.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a liquid sterilization method and sterilization apparatus using ultraviolet rays.

  Unlike sterilization by chemicals, ultraviolet sterilization has no remaining material, is highly safe, and hardly changes the irradiated object. Therefore, it is suitable as a sterilization method for liquids such as drinking water that require safety and security. It has been proposed to use ultraviolet sterilization for liquid sterilization in various situations.

  However, in aqueous solutions in which solutes that absorb ultraviolet rays are dissolved and suspensions that contain suspended substances that absorb or scatter ultraviolet rays, the ultraviolet transmittance decreases, and the rate of decrease depends on the type and content of solutes and suspended substances. Change significantly. For example, in distilled water, the thickness (optical path length: the length of light passing through the sample) when the transmittance for ultraviolet rays of 253.7 nm is 10% is 300 mm, whereas the same thickness of milk and juice. The thicknesses are known to be 0.07 mm and 0.5-1 mm, respectively. For this reason, the efficiency of ultraviolet sterilization with respect to a liquid that absorbs ultraviolet rays, such as milk, fruit juice, and liquor, is lowered.

  As a method for solving such a problem, Patent Document 1 states that “in a liquid sterilization method in which a liquid is passed in front of an ultraviolet irradiator and irradiated with ultraviolet rays to sterilize the liquid, the ultraviolet rays are irradiated at the location. The thickness of the liquid is limited to a thickness at which the illuminance ratio, which is the ratio of the ultraviolet illuminance on the surface of the liquid to the ultraviolet illuminance at the farthest point from the surface, is 20% or more, and There is described a “liquid sterilization method characterized by irradiating ultraviolet rays at an irradiation line intensity or irradiation time that is obtained at an irradiation position of the ultraviolet rays so that a residual rate is a predetermined value or less”.

  In the liquid sterilization method described above, a pair of ultraviolet irradiators having a straight tube lamp that irradiates light having a wavelength of 254 nm, disposed opposite to each other with a drinking water channel interposed therebetween, and drinking water provided in the channel. A sterilizer having a slit nozzle that is sprayed between a pair of ultraviolet irradiators is used. And the control of the thickness of the liquid in the place irradiated with the ultraviolet ray is such that the drinking water introduced from the inlet of the slit nozzle has a film thickness corresponding to the slit width of the slit, and a liquid film having a length corresponding to the slit length. It is done by injecting as

  On the other hand, as a water treatment method using ultraviolet rays, a method is also known in which a photocatalyst is excited by ultraviolet rays and sterilization or decomposition of organic substances is performed by the photocatalytic action (see Patent Documents 2 to 4).

  In other words, in Patent Document 2, a liquid to be processed is introduced between the liquid infiltrating the liquid to be processed, a liquid exuding surface from which the permeated liquid exudes, and the liquid infiltrating surface to be treated and the liquid permeating liquid. And a photocatalytic substance that promotes decomposition of organic substances by irradiation with light such as ultraviolet rays is held on at least one of the treatment liquid intrusion surface, the permeation liquid exudation surface, and the transmission layer. A method for treating tap water with a filter equipped with a separation membrane is described.

  Patent Document 3 includes a septic tank and a purification unit provided in the septic tank, the purification unit includes a plurality of plate-like photocatalytic members, and water to be purified to be purified in the septic tank flows. The plate-like photocatalyst member has a plurality of bent flow paths, the plate-like photocatalyst member has a plate-like light emitter capable of surface light emission, and a photocatalyst layer provided on at least one surface of the plate-like light emitter, and the photocatalyst The water purification device is described in which the layer constitutes an inner wall of the flow path.

  Furthermore, the following techniques are known for the ultraviolet light source. That is, Patent Document 4 includes a light source and a light guide plate on which the light source is arranged on the side surface, and at least one of the front surface or the back surface of the light guide plate is a light emitting surface that emits light from the light source. A surface light emitting device is described in which a surface other than a light emitting surface of a light plate and a side surface on which a light source is disposed is formed as a light shielding surface, and emits light having a peak wavelength of 388 nm or less.

  Patent Document 5 includes a cylindrical or polygonal column-shaped substrate and a plurality of deep ultraviolet light emitting diodes that emit ultraviolet light having a main peak in a wavelength region of 200 nm or more and less than 300 nm. The diode is disposed on the side surface of the base so that the optical axis of each deep ultraviolet light emitting diode 112 passes through the central axis of the base, and a rod-shaped light source that emits deep ultraviolet rays radially with respect to the central axis; An ultraviolet ray generator having a condensing device for condensing emitted ultraviolet rays is described.

Japanese Patent Laying-Open No. 2015-62902 JP 2000-42382 A JP 2012-223670 A JP 2006-237563 A Japanese Patent No. 5591305

  According to the method described in Patent Document 1, it is possible to perform ultraviolet sterilization even for a liquid having a low ultraviolet transmittance.

  However, in the above method, since the film thickness is controlled by spraying the liquid to be sterilized as a liquid film having a film thickness according to the slit width from the slit nozzle, it is difficult to control the film thickness uniformly over the entire ultraviolet irradiation region. In addition, since it is necessary to spray the liquid from the nozzle at a considerable speed for spraying, it is difficult to control the flow rate of the liquid to be sterilized, and the processing amount is limited.

  Furthermore, since an ultraviolet lamp having a broad emission spectrum is used as the ultraviolet light source, it has been clarified that short wavelength ultraviolet irradiation is unavoidable, and depending on the type of liquid to be sterilized, there is a concern about its alteration.

  It is a well-known fact that when ultraviolet irradiation is applied for a long period of time, the bonds of molecules constituting the substance are broken by the energy of the ultraviolet rays, resulting in deterioration of the synthetic resin. In ultraviolet sterilization in which only ultraviolet irradiation is performed, the effect has hardly been regarded as a problem. Moreover, in the method of sterilizing water using ultraviolet rays, as is apparent from the fact that many photocatalysts are used, active species such as hydroxyl radicals (OH radicals) and ozone generated by ultraviolet irradiation are effective. Have been considered. In fact, as far as the present inventors know, nothing is pointed out in the technology relating to ultraviolet sterilization of liquids that points out the harmful effects of the above active species.

  Even if there is a problem due to the active species, it is considered that the problem can be easily avoided if the photocatalyst is not used. When irradiating ultra-short wavelength ultraviolet rays, even in the absence of a photocatalyst, the ultraviolet rays directly act on water and oxygen to generate a small amount of active species, but the lifetime of such active species is very high. It is known to be short, and it is usually difficult to think that these trace amounts of active species will have an adverse effect in normal UV sterilization.

  However, even if it is such a small amount of active species with a short life, its activity (oxidizing power) is very strong, so when organic substances are present in the liquid to be sterilized, there is no problem in health or hygiene. It can cause slight changes in the amount that are not at the same level, resulting in subtle changes in taste and aroma. The sensitivity to human taste and olfaction is extremely high, and even slight alteration of its active ingredients can be detected, so the quality of beverages and seasonings characterized by subtle flavors is reduced by UV sterilization. It is fully assumed that

Such problems may occur in J. of Photochemistry and Photobiology A: Chemistry, Vol. 137, pp 177-184, 2000 and Chem. Eng. Technol. Vol. 21, pp 187-191, 1998. ₂ O) and Fe (OH) ²⁺ generate OH radicals by ultraviolet irradiation, and it has been shown that quantum efficiency is increased when short wavelength ultraviolet rays are used in these OH radical generation reactions. No. 4332107 discloses that a water retaining surface capable of holding water on its surface in a granular state is wetted with water droplets and irradiates ultraviolet rays having a wavelength of 254 nm from a short distance to generate OH radicals, and ethylene gas is applied to the water retaining surface. It can also be understood from the description of a method for reforming ethylene into ethane and water by ventilating a gas containing benzene.

  And the probability that such a problem will generate | occur | produce reliably increases by making the to-be-sterilized liquid more irradiated with the ultraviolet-ray of a very short wavelength by narrowing a flow path width.

  Therefore, the present invention solves the above-mentioned problems peculiar to ultraviolet sterilization of solutions and suspensions containing organic substances such as beverages and liquid seasonings in which taste, fragrance or flavor is important, and does not reduce the quality. An ultraviolet sterilization method and apparatus capable of performing ultraviolet sterilization with efficiency and certainty that can be implemented on an industrial scale, in addition to providing the method and apparatus, and having such characteristics. Is an issue.

  The present invention has a concept of not irradiating ultraviolet rays having a very short wavelength (high energy) such as 250 nm or less and further 220 nm or less having a high ability to generate the active species as much as possible, and in a state where a flow rate is controllable and a large amount This is based on the concept of irradiating ultraviolet light while passing the liquid to be sterilized through a narrow channel.

  That is, the ultraviolet sterilization method of the present invention is an ultraviolet sterilization method for sterilizing a liquid to be sterilized composed of a solution or suspension containing an organic substance by irradiating ultraviolet light, wherein the liquid to be sterilized is 253 nm or more and 280 nm or less, Preferably, the method includes an ultraviolet irradiation step of selectively irradiating ultraviolet rays having a wavelength region of 260 nm or more and 280 nm or less, and exists in a region irradiated with ultraviolet rays (hereinafter also referred to as an ultraviolet irradiation zone) in the ultraviolet irradiation step. The liquid to be sterilized is not brought into contact with the photocatalytic substance.

  Here, selectively irradiating ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less means that in the spectrum of the irradiated ultraviolet rays, the horizontal axis indicates the wavelength and the vertical axis indicates the relative emission intensity. The sum of the relative intensities of ultraviolet rays in the wavelength region of 280 nm or less, preferably 260 nm or more and 280 nm or less is 70% or more, preferably 80% or more, and most preferably 90% or more of the sum of the relative intensities of all wavelength regions. means. At this time, the sum of the relative intensities in the wavelength region of 250 nm or less is preferably 10% or less, preferably 5% or less, more preferably 3% or less, and the sum of the relative intensities in the wavelength region of 220 nm or less is 7%. % Or less, preferably 3% or less, more preferably 1% or less.

In the method of the present invention, more reliable ultraviolet sterilization can be performed, and the quality deterioration of the liquid to be sterilized as compared with the normal ultraviolet sterilization (which does not limit the wavelength of the irradiated ultraviolet rays). For the reason that the prevention effect is higher, in the ultraviolet irradiation step, the region irradiated with ultraviolet rays is irradiated with ultraviolet rays from one direction or two opposite directions, and the width of the irradiated ultraviolet rays in the region in the optical axis direction. The width is preferably such that all the liquid to be sterilized in the region is irradiated with the ultraviolet light. Specifically, when defined as the layer thickness of the liquid to be sterilized so that the irradiance of the transmitted ultraviolet light when the irradiated ultraviolet light passes through the layer of liquid to be sterilized is 0.001 mW / cm ² , It is preferable that the width be less than or equal to the sum of the effective optical path lengths of ultraviolet rays irradiated from the one direction or the two directions.

  In addition, since a liquid or suspension containing nitrate nitrogen that generates nitrite ions and the like easily generates hydroxyl radicals upon irradiation with ultraviolet rays (see, for example, Japanese Patent No. 4803684), the method of the present invention described above includes organic substances and It is preferable to employ for sterilizing a liquid to be sterilized comprising a solution or suspension containing nitrate nitrogen.

  Furthermore, from the viewpoint of reducing the generation of the active species and the reactivity thereof, in the ultraviolet sterilization method of the present invention, the temperature of the liquid to be sterilized in the ultraviolet irradiation step may be more than 0 ° C. and 10 ° C. or less. Preferably, it is preferable to further include a step of reducing or removing dissolved oxygen contained in the liquid to be sterilized as a pre-step of the ultraviolet irradiation step.

  The ultraviolet sterilizer of the present invention is a treatment tank for irradiating a liquid to be sterilized comprising a solution or suspension containing an organic substance with ultraviolet rays, and a supply means for supplying the fluid to be sterilized to the treatment tank, In the processing tank, a plurality of independent flow paths each having a predetermined width are arranged in parallel by arranging a plurality of partition walls in parallel with a predetermined gap in the processing tank. And at least one of the mutually facing wall surfaces of each of the plurality of flow paths has an ultraviolet light emitting surface, and the width of each of the plurality of flow paths, that is, the distance between the wall surfaces facing each other is Less than the sum of the effective optical path lengths of ultraviolet rays irradiated from the surface, and the ultraviolet light emitting surface selectively emits ultraviolet rays in a wavelength region of 253 nm to 280 nm, preferably 260 nm to 280 nm. And, wherein the absence of the photocatalytic material in the portion in contact with the disinfection liquid in the channel.

  Here, selectively emitting ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less means that in the spectrum in which the horizontal axis represents wavelength and the vertical axis represents relative emission intensity, 253 nm or more and 280 nm or less. UV light having a spectrum in which the sum of the relative intensities of the ultraviolet rays in the wavelength region of preferably 260 nm or more and 280 nm or less is 70% or more, preferably 80% or more, and most preferably 90% or more of the sum of the relative intensities of all the wavelength regions. It means to emit. At this time, the sum of the relative intensities in the wavelength region of 250 nm or less is preferably 10% or less, preferably 5% or less, more preferably 3% or less, and the sum of the relative intensities in the wavelength region of 220 nm or less is 7%. % Or less, preferably 3% or less, more preferably 1% or less.

  The apparatus of the present invention is preferably an apparatus for sterilizing a liquid to be sterilized comprising a solution or suspension containing an organic substance and nitrate nitrogen.

  The device of the invention is (1) transmitting ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less, and the transmittance of ultraviolet rays having a wavelength of 265 nm is higher than the transmittance of ultraviolet rays having a wavelength of 220 nm. The ultraviolet light emitting surface is covered with a resin film that is 10% or more higher, at least one selected from the following features: (2) further having temperature control means, and (3) further having dissolved oxygen reduction or removal means. It preferably has one feature.

  According to the liquid sterilization method or sterilization apparatus of the present invention, a solution or suspension containing an organic substance such as a beverage or liquid seasoning in which taste, fragrance or flavor is important, without impairing the taste, fragrance or flavor. UV sterilization can be performed. Moreover, ultraviolet sterilization can be performed with such efficiency and certainty that it can be carried out on an industrial scale.

It is a figure which illustrates typically the liquid sterilizer 100 concerning one embodiment. It is AA sectional drawing of FIG. (A) It is a top view which illustrates the surface light source 2 typically. (B) It is a side view which illustrates the surface light source 2 typically. (C) It is a side view which illustrates typically another example of the surface light source 2. FIG. Adjacent surface light source (partition wall) 2,2 ultraviolet light-emitting surface 21a, schematic cross-sectional view seen from the direction parallel to 21b, and is a diagram including a graph illustrating the coordinate dependence of the irradiance I ₁ of transmitted ultraviolet . It is sectional drawing which illustrates the liquid sterilizer 1100 typically. It is the cross-sectional view and the longitudinal cross-sectional view (when cut along the XX ′ plane) of the rod-shaped light source (rod-shaped ultraviolet light emitting module) 110. It is a cross-sectional view of the ultraviolet ray generator 24 having the rod-shaped light source 110. It is a side view of the ultraviolet-ray generator 24 which has the rod-shaped light source 110.

  The ultraviolet sterilization method of the present invention is an ultraviolet sterilization method for performing sterilization by irradiating a liquid to be sterilized comprising a solution or suspension containing an organic substance with ultraviolet rays, wherein the liquid to be sterilized has a wavelength region of 253 nm or more and 280 nm or less. An ultraviolet irradiation step of selectively irradiating the ultraviolet ray, and the liquid to be sterilized present in the region irradiated with the ultraviolet ray in the ultraviolet irradiation step is not brought into contact with the photocatalytic substance.

  The liquid to be sterilized is not particularly limited as long as it is a solution or suspension containing an organic substance, but for the reason that the effect of the present invention is remarkable, the taste, aroma and / or flavor are important, and various sugars and aromas are used as organic substances. A beverage or liquid seasoning comprising an aqueous solution or aqueous suspension containing an ester compound as a component is preferred. In addition, since the effect of promoting the generation of OH radicals by nitrate nitrogen compounds can be suppressed, and the effect of the present invention becomes more obvious, the method of the present invention uses nitrate nitrogen compounds such as tomato juice and vegetable juice. It is preferable to apply the liquid to be sterilized.

  In the method of the present invention, the liquid to be sterilized is selectively irradiated with ultraviolet rays having a wavelength range of 253 nm to 280 nm, preferably 260 nm to 280 nm. By selectively irradiating ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less, high-energy ultraviolet rays are applied to the liquid to be sterilized while maximizing the bactericidal effect of damaging bacterial DNA. It can suppress generation | occurrence | production of active species, such as OH radical and ozone, acting on the water and dissolved oxygen which are contained, and it becomes possible to maintain the quality of the liquid to be sterilized.

  Here, selectively irradiating ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less means that in the spectrum of the irradiated ultraviolet rays, the horizontal axis indicates the wavelength and the vertical axis indicates the relative emission intensity. The sum of the relative intensities of ultraviolet rays in the wavelength region of 280 nm or less, preferably 260 nm or more and 280 nm or less is 70% or more, preferably 80% or more, and most preferably 90% or more of the sum of the relative intensities of all wavelength regions. means. At this time, the sum of the relative intensities in the wavelength region of 250 nm or less is preferably 10% or less, preferably 5% or less, more preferably 3% or less of the sum of the relative intensities in all the wavelength regions, and 220 nm or less. The sum of the relative intensities in the wavelength region is 7% or less, preferably 3% or less, more preferably 1% or less, of the sum of the relative intensities in all the wavelength regions. Furthermore, from the viewpoint of preventing so-called photorecovery or reactivation, the sum of the ultraviolet intensities in the wavelength region of 300 nm or more is 7% or less, preferably 3% or less, more preferably 1% of the sum of the relative intensities in all the wavelength regions. % Or less is preferable.

  That is, the spectrum of the irradiated ultraviolet rays becomes more preferable from (1) to (6) below.

  (1) The sum of the relative intensities of ultraviolet rays in the wavelength region of 253 nm or more and 280 nm or less is 70% or more of the sum of the relative intensities of all the wavelength regions, and the sum of the relative intensities of the wavelength regions of 250 nm or less is relative to all the wavelength regions. A spectrum that is 10% or less of the sum of intensities, and the sum of UV intensities in the wavelength region of 300 nm or more is 7% or less of the sum of relative intensities in all wavelength regions; (2) UV in the wavelength region of 260 nm or more and 280 nm or less The total sum of relative intensities is 70% or more of the sum of relative intensities in all wavelength regions, the sum of relative intensities in the wavelength regions of 250 nm or less is 10% or less of the sum of relative intensities in all wavelength regions, and is 300 nm or more. The sum of the ultraviolet intensities in the wavelength region is a spectrum that is 7% or less of the sum of the relative intensities in all the wavelength regions; (3) the ultraviolet rays in the wavelength region from 253 nm to 280 nm. The sum of the pair strengths is 80% or more of the sum of the relative intensities in the whole wavelength region, the sum of the relative intensities in the wavelength region of 250 nm or less is 5% or less of the sum of the relative intensities in all the wavelength regions, and is 300 nm or more. A spectrum in which the total sum of ultraviolet intensities in the wavelength region is 3% or less of the sum of relative intensities in all wavelength regions; (4) The sum of the relative intensities of ultraviolet rays in the wavelength region of 260 nm or more and 280 nm or less is the relative intensity of all wavelengths. 80% or more of the total sum, the sum of relative intensities in the wavelength region of 250 nm or less is 5% or less of the sum of the relative intensities in all the wavelength regions, and the sum of the ultraviolet intensities in the wavelength region of 300 nm or more is the total wavelength region (5) The sum of the relative intensities of ultraviolet rays in the wavelength region of 253 nm or more and 280 nm or less is 90% or more of the sum of the relative intensities of all the wavelength regions. , The sum of the relative intensities in the wavelength region of 250 nm or less is 3% or less of the sum of the relative intensities in all the wavelength regions, and the sum of the ultraviolet intensities in the wavelength region of 300 nm or more is 1 of the sum of the relative intensities in all the wavelength regions. (6) The sum of the relative intensities of ultraviolet rays in the wavelength region of 260 nm or more and 280 nm or less is 90% or more of the sum of the relative intensities of all wavelength regions, and the sum of the relative intensities in the wavelength region of 250 nm or less is A spectrum in which the sum of relative intensities in all wavelength regions is 3% or less and the sum of ultraviolet intensities in wavelength regions of 300 nm or more is 1% or less of the sum of relative intensities in all wavelength regions.

  In order to selectively irradiate ultraviolet rays in such a wavelength region, a method using an optical filter that absorbs or reflects ultraviolet rays in a wavelength region other than the wavelength region to be irradiated, or irradiates by extracting ultraviolet rays having a specific wavelength with a monochromator. For example, a method using an ultraviolet light-emitting diode (hereinafter also referred to as UV-LED) designed to emit ultraviolet light in a specific wavelength region can be employed. Among these methods, 253 nm or more and 280 nm can be obtained because of the advantages of the excellent characteristics of the ultraviolet light emitting diodes, such as instantaneous startup, low power drive, long life, and no use of mercury. Hereinafter, it is preferable to use a UV-LED having a main peak in a wavelength region of preferably 260 nm or more and 280 nm or less and having an emission spectrum as described above as a light source.

  In the method of the present invention, it is necessary that the liquid to be sterilized existing in the ultraviolet irradiation zone is not brought into contact with the photocatalytic substance in the ultraviolet irradiation step. Here, the photocatalytic substance means a substance having a function (photocatalytic function) that is excited by light irradiation in the presence of water or dissolved oxygen to generate active species such as superoxide, hydrogen peroxide, OH radical, and ozone. Typical photocatalytic substances include titanium oxide and tungsten oxide. In order to prevent the liquid to be sterilized present in the ultraviolet irradiation zone from coming into contact with the photocatalytic substance, it is sufficient that such a photocatalytic substance does not exist in a portion in contact with the liquid to be sterilized in the ultraviolet irradiation zone. In addition, in order to prevent the photocatalytic substance from being mixed into the liquid to be sterilized supplied to the ultraviolet irradiation zone, for example, a material containing the photocatalytic substance is used in the wetted part of various members such as a filter and a stirrer arranged upstream as necessary. It is preferable not to do so.

  In the method of the present invention, the ultraviolet irradiation method in the ultraviolet irradiation zone and the shape and size of the ultraviolet irradiation zone are not particularly limited. For the reason that the effect of preventing deterioration of the quality of the liquid to be sterilized when compared with the case of not selectively irradiating ultraviolet rays having a wavelength, the ultraviolet irradiation zone is irradiated with ultraviolet rays from one direction or two directions opposite to each other, and In the ultraviolet irradiation zone, it is preferable that the width of the irradiated ultraviolet light in the optical axis direction is not more than the sum of the effective optical path lengths of the ultraviolet light irradiated from the one direction or the two directions.

Here, the effective optical path length is the liquid to be sterilized in which the irradiance of the transmitted ultraviolet light is 0.001 mW / cm ² when the ultraviolet light irradiated from the ultraviolet light source or the ultraviolet light emitting surface passes through the layer of the liquid to be sterilized. The determination method is described later in detail.

Incidentally, the irradiance that defines the effective optical path length ^{values: 0.001mW / cm 2 (1μW /} cm 2) is not necessarily has critical significance in that number itself, a practical processing time (ultraviolet irradiation time ) Is an index determined from the viewpoint that an effective bactericidal effect can be obtained. For example, when considering the sterilization of Escherichia coli having an ultraviolet irradiation amount (integrated irradiation amount) necessary for 99.9% inactivation of about 10 (mJ / cm ² = mW · sec / cm ² ), 1 μW / cm ² 99.9% inactivation is possible with irradiation of 10,000 seconds (about 2.8 hours) with irradiance of 0.1 μW / cm ² , but about 28 hours, 10 times that with 0.1 μW / cm ² irradiance. In short, it's not realistic. That is, the basic technical idea of defining the thickness of the flow path with the effective optical path length is practical in the sterilized fluid layer flowing in the flow path when sterilizing the liquid to be sterilized with low UV transmittance. This is to avoid creating an area where the integrated irradiation amount necessary for sterilization cannot be obtained even if ultraviolet irradiation is performed for a long time.

  In the method of the present invention, it is preferable to irradiate the liquid to be sterilized which circulates in the flow path in the ultraviolet irradiation step with ultraviolet rays because ultraviolet sterilization can be performed by a continuous method. The flow path is not particularly limited as long as it can irradiate the liquid to be sterilized that circulates inside the flow path. For example, the flow path is emitted from an ultraviolet light source arranged outside and made of an ultraviolet light transmissive material such as quartz or fluororesin. A tubular, slit-shaped or groove-shaped flow path having a window for taking in ultraviolet light inside, or a slit-shaped or groove-shaped flow path with an ultraviolet light emitting surface arranged on the side wall surface can be adopted. In the former case, the entire flow path may be made of an ultraviolet light transmissive material, such as a quartz plate or a quartz tube, without providing a window portion. As such an example, the flow path in the apparatus shown by FIG. 1 and 2 of Unexamined-Japanese-Patent No. 2006-106682 can be mentioned.

  These flow paths can irradiate ultraviolet rays from one direction or from two opposite directions, more specifically, ultraviolet rays from windows or ultraviolet light emitting surfaces provided on one or both of a pair of opposing wall surfaces. An ultraviolet ray that is a slit-like or groove-like channel that can be irradiated and that is irradiated with the thickness (width) in the optical axis direction of the ultraviolet ray that is irradiated in the channel from the one or two directions. It is preferable that the flow path be equal to or less than the sum of the effective optical path lengths.

  In the method of the present invention, the temperature of the liquid to be sterilized in the ultraviolet irradiation step is set to 0 ° C. from the viewpoint of suppressing the generation of the active species and further reducing the reactivity of the active species that are inevitably generated. It is preferable that the temperature exceeds 10 ° C., and it is preferable to further include a step of reducing or removing dissolved oxygen contained in the liquid to be sterilized as a pre-step of the ultraviolet irradiation step.

  In order to set the temperature of the liquid to be sterilized in the ultraviolet irradiation step within the above range, the temperature of the liquid to be sterilized may be controlled upstream through a heat exchanger or the like before being supplied to the ultraviolet irradiation zone. Further, as a method for reducing or removing dissolved oxygen, a method of bubbling nitrogen gas or hydrogen gas can be employed.

  Further, in the method of the present invention, after completion of the ultraviolet sterilization step, the liquid to be sterilized with ultraviolet rays sterilized without passing ultraviolet rays having a wavelength of 400 nm or less is maintained in a container that does not transmit ultraviolet rays having a wavelength of 400 nm or less. It is preferable to further have a filling step of filling and sealing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these forms. In the drawing, some symbols may be omitted.

FIG. 1 is a diagram schematically illustrating a liquid sterilizer 100 according to an embodiment of the present invention. The liquid sterilization apparatus 100 is an apparatus used for the liquid sterilization method S1 according to _one embodiment of the present invention. As shown in FIG. 1, the liquid sterilization apparatus 100 has a cylindrical sterilization tank 1 whose body has a rectangular cross section, and an inflow port 1 a is provided at one end of the sterilization tank 1. An outlet 1b is provided at the other end of the tank 1, respectively. The liquid that has flowed into the sterilization tank 1 from the inlet 1a is sterilized by ultraviolet rays inside and then flows out from the outlet 1b.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. As shown in FIG. 2, the liquid sterilization apparatus 100 includes a plurality of surface light sources 2, 2... (Hereinafter sometimes simply referred to as “surface light sources 2”) inside the sterilization tank 1. As will be described later, each surface light source 2 has a pair of ultraviolet light emitting surfaces. In the sterilization tank 1, a plurality of surface light sources 2, 2,... Are arranged so that their ultraviolet light emitting surfaces face each other, and are arranged in parallel between a plurality of adjacent surface light sources 2. It has slit-like flow paths 3, 3,... (Hereinafter, simply referred to as “flow path 3”). The liquid flowing into the sterilization tank 1 from the inflow port 1a is branched and sterilized by being irradiated with ultraviolet rays from the surface light source 2 while passing through the plurality of slit-like flow paths 3, 3,. . The plurality of flow paths 3, 3,... Form an ultraviolet irradiation zone having the same width and independent from each other. Since each flow path 3 does not communicate in the middle, a certain width (thickness) can be reliably maintained in the ultraviolet irradiation zone, and the thickness (width) of the ultraviolet rays irradiated with the liquid to be sterilized is irradiated in the optical axis direction. ) Is also kept constant. The sterilized liquid that has passed through the flow paths 3, 3,... Merges downstream and flows out of the sterilization tank 1 from the outlet 1 b.

  FIG. 3A is a plan view illustrating the surface light source 2, and FIG. 3B is a side view illustrating the surface light source 2. As shown in FIGS. 3A and 3B, the surface light source 2 includes a light guide plate 21 having a pair of ultraviolet light emitting surfaces 21 a and 21 b and a plurality of deep ultraviolet rays arranged at one end of the light guide plate 21. .. (Hereinafter, simply referred to as “deep ultraviolet light emitting diode 22”), and light diffusion dots 23, 23,... (Hereinafter, referred to as “surfaces of the pair of ultraviolet light emitting surfaces 21a, 21b”). In this case, it may be simply referred to as “light diffusion dot 23”). Although details are omitted in FIG. 2, one end portion of the surface light source 2 (more specifically, the light guide plate 21) extends to the outside of the body portion of the sterilization tank 1, and a deep ultraviolet light emitting diode is formed at the end portion. Are connected to a power source (not shown) and emits ultraviolet rays. The deep ultraviolet light-emitting diodes 22, 22,... Have a main peak in a wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less in an emission spectrum in which the horizontal axis represents wavelength and the vertical axis represents relative emission intensity. And the sum of the relative intensities of ultraviolet rays in the wavelength region of 253 nm or more and 280 nm or less, preferably 260 nm or more and 280 nm or less is 70% or more, preferably 80% or more, and most preferably 90% or more of the sum of the relative intensities of all the wavelength regions. The sum of the relative intensities in the wavelength region of 250 nm or less is 10% or less, preferably 5% or less, more preferably 3% or less of the sum of the relative intensities in all the wavelength regions, and the relative intensity in the wavelength region of 220 nm or less. The total sum is 7% or less, preferably 3% or less, more preferably 1% or less, of the total relative intensity in all wavelength regions. In addition, the sum of the ultraviolet intensities in the wavelength region of 300 nm or more is 7% or less, preferably 3% or less, more preferably 1% or less of the sum of the relative intensities in all wavelength regions (hereinafter referred to as such an emission spectrum). Is also referred to as “specific emission spectrum”).

  The ultraviolet rays emitted from the ultraviolet light emitting surfaces 21a and 21b have the same emission spectrum. The ultraviolet light diffusing dots 23 are provided such that one surface is in contact with the ultraviolet light emitting surface 21a or 21b and reflects the ultraviolet light, and the light diffusing dot base material provided on the other surface of the reflecting film 23c. 23a and light diffusing agents 23b, 23b,... Dispersed and held inside the light diffusing dot base material 23a (hereinafter sometimes simply referred to as “light diffusing agent 23b”). As shown by an arrow B in FIG. 3B, the ultraviolet light emitted from the deep ultraviolet light emitting diode 22 enters the light guide plate 21 from one end portion 21c of the light guide plate 21, and the reflection films 23c, 23c,. The light is propagated through the light guide plate 21 while being reflected by the light, and is emitted to the outside of the light guide plate 21 from the ultraviolet light emitting surface 21a or 21b without the reflective film 23c or the other end portion 21d of the light guide plate 21.

  The light diffusing agent 23b is preferably made of fine particles such as magnesium oxide, calcium carbonate, magnesium carbonate, and aluminum, which have high reflectivity with respect to ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less, and can effectively diffuse such ultraviolet rays. used. It is not preferable to use a material that easily absorbs ultraviolet rays in the above wavelength region as a light diffusing agent, and a photocatalytic substance cannot be used as a light diffusing agent.

  .. Are disposed on the surface of the light guide plate 21, the liquid collides with the light diffusion dots 23 when the liquid flows through the slit-shaped flow path 3, and turbulent flow is generated. Since the liquid is agitated by the generation of the turbulent flow, the sterilization efficiency by ultraviolet rays is improved.

  3A and 3B, the light diffusion dot base material 23 a is provided on the surface of the reflection film 23 c that is not in contact with the light guide plate 21, and as a result, the light diffusion dots 23 are the ultraviolet light emitting surface 21 a of the light guide plate 21. However, the surface light source 2 is not limited to this form. For example, the light diffusing dots 23 are formed from the ultraviolet light emitting surfaces 21a and 21b of the light guide plate 21. It is also possible to employ a surface light source that does not protrude. FIG.3 (c) is a side view explaining another example of such a surface light source, and is a figure corresponding to FIG.3 (b). As shown in FIG. 3C, the light diffusing dots 23 may be provided so as to be buried in the ultraviolet light emitting surface 21a or 21b. In FIG. 3C, the reflective film 23 c is provided at the interface between the light diffusing dot base material 23 a and the light guide plate 21. Thus, according to the embodiment in which the light diffusion dots are buried in the surface of the light guide plate, the surface can be covered with a film that transmits ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less. For example, a fluororesin film such as polychlorotrifluoroethylene (PDTFE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropane copolymer (FEP), ethylenetetrafluoroethylene (ETFE), or polyethylene Polyolefin films such as (PE) have a high transmittance for ultraviolet rays in the wavelength region of 253 nm or more and 280 nm or less, and therefore, when the ultraviolet light emitting surface is coated with these films, not only the antifouling property is improved, but also dirt By appropriately replacing the film according to the degree, the ultraviolet irradiation state can always be kept in a good state, and maintenance is facilitated. Among these films, when covered with a resin film in which the transmittance of ultraviolet rays having a wavelength of 265 nm, such as ETFE, FEP, PFA, PE, etc. is higher by 10% or more than the transmittance of ultraviolet rays having a wavelength of 220 nm, as an optical filter It is possible to use a light source that functions and has a broad emission spectrum. The thickness of these films is not particularly limited, but is usually 5 to 25 μm.

  Refer to FIG. 2 again. In the liquid sterilizer 100, the surface light sources 2, 2,... Having the pair of ultraviolet light emitting surfaces 21a, 21b are opposed to each other, that is, the ultraviolet light emitting surfaces of adjacent surface light sources are opposed to each other. Since they are arranged in parallel, the liquid can be irradiated with ultraviolet rays from both sides of the slit-shaped flow path 3, and the liquid can be sterilized efficiently. As will be described later, the width (thickness) d of each slit-shaped flow path 3 in the direction perpendicular to the ultraviolet light emitting surfaces 21 a and 21 b, that is, in the optical axis direction of the irradiated ultraviolet light is the ultraviolet light sandwiching the flow path 3. It is below the sum of the effective optical path lengths of the light emitting surfaces 21a and 21b.

For liquid sterilization method S ₁ according to an embodiment of the present invention will be described with reference to FIGS. Liquid sterilization method S ₁ is in the flow path 3 formed between (1) a predetermined pair of partition walls arranged in parallel to provide a gap width 2,2 (i.e. adjacent surface light source 2,2), and step S ₁₁ for circulating the sterilization liquid 5 consisting of a solution or suspension containing an organic substance, (2) to be sterilized liquid 5 passing through the channel 3, both the two surfaces facing the pair of partition walls 2,2 and a step _{S 12} is irradiated with ultraviolet rays from the ultraviolet light-emitting surface 21a, 21b provided in the. The width d of the gap (that is, the distance between the adjacent surface light sources 2 and 2) in the direction perpendicular to the ultraviolet light emitting surfaces 21a and 21b is the effective optical path lengths L _a and L of the ultraviolet light emitting surfaces 21a and 21b. The total sum of _b is set to L _a + L _b or less. Here, the effective optical path lengths L _a and L _b of the respective ultraviolet light emitting surfaces 21a and 21b are the irradiances of the transmitted ultraviolet rays when the ultraviolet rays irradiated from the ultraviolet light emitting surfaces 21a / 21b pass through the layer of the liquid 5 to be sterilized. Is defined as the thickness of the layer of the liquid 5 to be sterilized, which is 0.001 mW / cm ² (1 μW / cm ² ). The effective optical path lengths L _a and L _b of the ultraviolet light emitting surfaces 21a and 21b are separately measured.

The effective optical path lengths L _a and L _b of the ultraviolet light emitting surfaces 21a and 21b can be determined by, for example, the following steps (a) to (e) (S _{101 to} S ₁₀₅ ):
(A) Step S ₁₀₁ of filling the sterilized liquid 5 into the inside of an ultraviolet transmissive optical measurement cell having a predetermined optical path length (hereinafter sometimes simply referred to as “cell”);
(B) The ultraviolet light emitting surface 21a (or 21b) is brought into close contact with the cell, and the ultraviolet light emitted from the ultraviolet light emitting surface 21a (or 21b) under the same light emission conditions as in the sterilization treatment is irradiated toward the inside of the cell. Step _S102 ;
(C) Step S ₁₀₃ of measuring the irradiance (unit: mW / cm ² ) of the transmitted ultraviolet light that has passed through the cell;
(D) the steps (a) to the _{(c) (S 101 ~S 103} ), by performing a plurality of cells having different optical path lengths, the step _{S 104} to determine the relationship between the irradiance and the optical path length of the transmitted ultraviolet ;and,
(E) The effective optical path length L _a (or L _b ) of the ultraviolet light emitting surface 21a (or 21b) based on the relationship between the irradiance of transmitted ultraviolet rays and the optical path length obtained in the step (d) (S ₁₀₄ ). Determining step S ₁₀₅ .

In the steps (d) to (e) (S _{104 to} S ₁₀₅ ), the relationship between the irradiance of transmitted ultraviolet light and the optical path length follows Lambert-Beer's law. That is, the irradiance I ₁ of transmitted ultraviolet rays is in the relationship of the following equation (1) with respect to the optical path length L.
log (I ₁ / I ₀ ) = − αL (1)
In Equation (1), I ₀ is the irradiance of ultraviolet light having a wavelength λ before entering the medium, and α is a proportionality constant (absorption coefficient) determined corresponding to the liquid to be sterilized 5 and the wavelength λ _peak . In general, the peak width of the emission spectrum of a light emitting diode is extremely narrow. Therefore, in discussing the dependence of the irradiance of transmitted ultraviolet rays on the optical path length, the extinction coefficient α (λ _peak ) at the emission peak wavelength λ _peak of the deep ultraviolet light emitting diode 22. It is enough to consider only. Equation (1) can be transformed into the following equation (2).
logI ₁ = −αL + logI ₀ (2)
Therefore, by obtaining a plurality of pairs of the logarithm of the transmitted ultraviolet irradiance I _{1 at} the main peak wavelength λ _peak and the optical path length L of the cell, the transmitted ultraviolet irradiance I ₁ and the optical path length L at the main peak wavelength λ _peak Can be obtained (step (d) above, step S ₁₀₄ ). For example, a known method such as a least square method can be used to calculate the regression line. The effective optical length _{L a} of the ultraviolet light-emitting surface 21a (or 21b) (or _{L b)} is be obtained as the optical path length L to provide a ^{_{I 1 = 0.001mW / cm 2 (}} 1μW / cm 2) in the regression line (Step (e) (S ₁₀₅ ) above). If the ultraviolet light emitting surfaces 21a and 21b have the same light emission intensity, L _a = L _b .

The steps (a) to (e) (S _{101 to} S ₁₀₅ ) can be performed separately before the steps S ₁₁ and S ₁₂ .

As described above, in the liquid sterilizing method _{S 1,} ultraviolet light-emitting surface 21a, the width d in a direction perpendicular to 21b, the ultraviolet light-emitting surface 21a, the effective optical path length _L a of 21b, and less total _L a + _{L b} of _{L b} To do. At this time, the lower limit value of d takes into consideration the control range of ultraviolet intensity (particularly the highest intensity) irradiated from the ultraviolet light emitting surface of the surface light source to be used and the control range of the flow rate of liquid to be sterilized (particularly the lowest flow rate), It is determined from the viewpoint of obtaining an integrated irradiation amount necessary for sterilization within an assumed processing time (within the ultraviolet irradiation time). The lower limit of d is preferably 10 to 90% of the total sum L _a + L _b of the effective optical path lengths L _a and L _b , more preferably 20 to 80%, and more preferably 30 to 70%. Most preferred.

The length of the flow path 3 and / or the flow rate of the liquid 5 to be sterilized (if the length of the flow path 3 is not adjustable, the flow rate of the liquid 5 to be sterilized) It is preferable to determine so that the integrated dose I _int (mJ / cm ² ) is reliably achieved. This can be performed, for example, by the above steps (a) to (d) (S _{101 to} S ₁₀₄ ) and the following steps (f) to (i) (S _{106 to} S ₁₀₉ ):
(F) The flow path based on the relationship between the irradiance I ₁ of the transmitted ultraviolet light on the ultraviolet light emitting surfaces 21a and 21b and the optical path length L and the width d of the flow path 3 in the direction perpendicular to the ultraviolet light emitting surfaces 21a and 21b. 3 of ultraviolet light-emitting surface 21a, the irradiance distribution of the ultraviolet in a direction perpendicular to 21b, and the minimum irradiance _{I min} (unit: mW / cm ²⁾ in the irradiance distribution step _{S 106} of determining;
(G) Step S ₁₀₇ for determining an integrated irradiation amount I _int (unit: mJ / cm ² ) of ultraviolet rays necessary for sterilization of the liquid 5 to be sterilized;
(H) a step S ₁₀₈ of determining a minimum irradiation time t _min (unit: second) defined by a value obtained by dividing the integrated irradiation amount I _int by the minimum irradiance I _min ; and
(I) The length 1 of the flow path 3 and / or the liquid 5 to be sterilized flowing through the flow path 3 so that the stay time T during which the liquid 5 to be sterilized stays in the flow path 3 is equal to or longer than the minimum irradiation time t _min . Step S ₁₀₉ of adjusting the flow velocity (linear velocity) v.

In the step (f) (S ₁₀₆ ), the relationship between the irradiance I _{1 of the} transmitted ultraviolet rays and the optical path length L related to the ultraviolet light emitting surfaces 21 a and 21 b is the above steps (a) to (d) (S _{101 to} S ₁₀₄ ). ). Please refer to FIG. 4 shows a schematic cross-sectional view of the adjacent surface light source (partition wall) 2,2 ultraviolet light-emitting surface 21a, in a direction parallel to 21b, and a graph for explaining the coordinate dependence of the irradiance I ₁ of transmitted ultraviolet Appears. The x axis is taken in the direction perpendicular to the ultraviolet light emitting surfaces 21a and 21b, and the position of the ultraviolet light emitting surface 21a is taken as the origin of the x axis. The contributions I _a (x) and I _b (x) of the ultraviolet rays emitted from the ultraviolet light emitting surfaces 21a and 21b to the irradiance I (x) of the transmitted ultraviolet ray at the coordinate x are expressed by the following equations (3a) and (3b): It is represented by
I _a (x) = I _{0, a} · 10 ^−αx (3a)
I _b (x) = I _{0, b} · 10 ^{−α (d−x)} (3b)
However, d is the width | variety of the direction perpendicular | vertical to the ultraviolet light emission surface 21a, 21b of the flow path 3. FIG.
Therefore, the irradiance I (x) of the transmitted ultraviolet light at the coordinate x is
I (x) = I _a (x) + I _b (x)
= I _{0, a} · 10 ^−αx + I _{0, b} · 10 ^{−α (d−x)} (4)
It is represented by I (x) is an ultraviolet irradiance distribution on the ultraviolet light emitting surfaces 21 a and 21 b of the flow path 3. The coordinate x ₁ giving dI (x) / dx = 0 is x ₁ = (log (I _{0, a} / I _{0, b} ) + αd) / 2α (6)
It is. When the light emission intensities of the ultraviolet light emitting surfaces 21a and 21b are the same, I _{0, a} = I _{0, b.} Therefore, in this case, equation (6) can be expressed as x ₁ = d / 2 ( 7)
It becomes. When 0 ≦ x ≦ d, it is always d ² I (x) / dx ² > 0 (8)
Therefore, the irradiance I (x) of the transmitted ultraviolet ray takes the minimum value (minimum value) I (x ₁ ) at the coordinate x ₁ in the equation (6). I (x ₁ ) is the lowest irradiance I _min in the irradiance distribution I (x).

In the step (g) (S ₁₀₇ ), the cumulative irradiation amount I _int (unit: mJ / cm ² ) of ultraviolet rays necessary for sterilization of the liquid 5 to be sterilized is the main amount of ultraviolet rays irradiated from the ultraviolet light emitting surfaces 21a and 21b. It can be determined based on the peak wavelength (that is, the emission peak wavelength λ _peak of the deep ultraviolet light-emitting diode 22) and the microorganisms to be sterilized that are supposed to be contained in the liquid 5 to be sterilized. As I _int , for example, an integrated irradiation amount at which 99.9% of microorganisms to be sterilized are killed when irradiated with deep ultraviolet light having a wavelength λ _peak can be selected. Such an integrated dose can be known from preliminary experiments or literature.

In step (h) (S ₁₀₈ ), the minimum irradiation time t _min is the minimum irradiance I _min determined in (f) step S ₁₀₆ and the integrated irradiation amount determined in (g) step S ₁₀₇ . From I _int , it can be determined by the following equation (9).
t _min = I _int / I _min (9)
In the step (i) (S ₁₀₉ ), the staying time T during which the liquid 5 to be sterilized stays in the flow path 3 is the length l of the flow path 3 and the flow velocity (linear velocity) of the liquid 5 to be sterilized flowing through the flow path 3. ) From v
T = 1 / v (10)
It depends on. (H) T = 1 / v ≧ t _min (11) with respect to the minimum irradiation time t _min obtained in step S ₁₀₈ .
Adjust l and / or v so that When there are a plurality of flow paths 3,... And the flow rate of the liquid 5 to be sterilized differs depending on the flow path, the formula (11) should be satisfied for the flow path with the fastest flow rate. When the length l of the flow path 3 is not adjustable, the flow velocity v of the liquid to be sterilized 5 is adjusted. The flow velocity v of the liquid 5 to be sterilized can be easily adjusted by changing the liquid feed speed of a liquid feed pump (not shown) arranged upstream and / or downstream of the liquid sterilizer 100.

In the above description regarding the present invention, the sterilized liquid 5 is circulated through the two or more flow paths 3, 3,... In (1) Step S ₁₁ , and the two or more flow paths are used in (2) Step S ₁₂ . Are irradiated with ultraviolet rays, and each of the two or more flow paths 3, 3,... Has three or more partition walls 2, 2,. A flow path 3 formed between a pair of adjacent partition walls 2 and 2, and a liquid in a form in which ultraviolet light emitting surfaces 21 a and 21 b are provided on both surfaces of the three or more partition walls 2, 2,. Although the sterilization method was illustrated, the liquid sterilization method of this invention is not limited to the said form. For example, the ultraviolet light emitting surface 21a is provided only on one side of each of the three or more partition walls 2, 2,... (The ultraviolet light emitting surface 21b does not exist), and the three or more partition walls 2, 2,. A liquid sterilization method in which the surface provided with the ultraviolet light emitting surface 21a is arranged in the same direction (see FIG. 2) may be used. As such a form, for example, in FIGS. 3A to 3C, a form in which the ultraviolet light emitting surface 21b is entirely covered with the ultraviolet reflecting film can be exemplified. In such a form, in the step (2), the liquid 5 to be sterilized passing through the flow path 3 is irradiated with ultraviolet rays from one ultraviolet light emitting surface 21 a provided on one of the two opposing surfaces of the pair of partition walls 2. It becomes a process to do.

  Moreover, in the said process (1), the to-be-sterilized liquid 5 is distribute | circulated through the single flow path 3, and in the said process (2), the to-be-sterilized liquid 5 which passes through this single flow path 3 is irradiated with an ultraviolet-ray. A liquid sterilization method in the form is also possible.

  In the above description regarding the present invention, each surface light source 2 has a light guide plate 21 having a pair of ultraviolet light emitting surfaces 21a and 21b, and a plurality of light sources having a specific emission spectrum arranged at one end 21c of the light guide plate 21. Although the liquid sterilization apparatus 100 having the deep ultraviolet light emitting diodes 22, 22,... Is illustrated, the liquid sterilization apparatus of the present invention is not limited to the form. For example, with respect to the surface light source, in addition to the light guide plate of another form, a deep ultraviolet light emitting diode 22 arranged in a large number of planes like the LED module described in JP2012-115715A is used. It is also possible. However, such a surface light source inevitably increases the thickness of the surface light source, which makes it difficult to reduce the size of the apparatus. In addition, the deep ultraviolet light emitting diode 22 itself must be disposed inside the sterilization tank 1. Maintenance of the apparatus becomes complicated. For these reasons, it is preferable to use a light guide plate as the surface light source.

  As an example of a suitable device other than the liquid sterilizer 100, each surface light source includes a light guide plate having a pair of ultraviolet light emitting surfaces, and an ultraviolet ray generator that is disposed apart from the light guide plate and generates ultraviolet rays. And a liquid sterilization apparatus having an ultraviolet wave guiding means for guiding ultraviolet rays from the ultraviolet ray generating apparatus to one end portion of the light guide plate. FIG. 5 is a diagram illustrating a liquid sterilizer 1100 according to another embodiment. FIG. 5 is a cross-sectional view schematically illustrating the liquid sterilization apparatus 1100, and the direction perpendicular to the paper surface of FIG. 5 is the direction in which the sterilized liquid 5 flows.

  The liquid sterilizer 1100 is different from the liquid sterilizer 100 described above in that it has surface light sources 1002, 1002,... Instead of the surface light sources 2, 2,. Each surface light source 1002 includes a light guide plate 21 having a pair of ultraviolet light emitting surfaces 21 a and 21 b, an ultraviolet ray generator 24 that is disposed apart from the light guide plate 21 and generates ultraviolet rays, and is guided from the ultraviolet ray generator 24. Ultraviolet wave guide means 25 for guiding ultraviolet rays to one end 21c of the optical plate 21 is provided. 5, the light diffusion dots 23, 23,... Provided on the surface of the light guide plate 21 are omitted to simplify the drawing. As the ultraviolet waveguide means 25, for example, a waveguide capable of transmitting strip-shaped parallel light, such as a folded light guide plate, a flexible light guide film, a waveguide having an inner wall made of an ultraviolet reflector, and the like. Can be used without restriction. In the liquid sterilization apparatus 1100, a part of the light guide plate 21 passes through a through hole provided in one side wall of the sterilization tank 1 in order to facilitate the connection between the end 21 c of the light guide plate 21 and the ultraviolet wave guiding means 25. One end portion of the ultraviolet wave guiding means 25 is connected to the end portion 21 c of the light guide plate 21 that extends from the inside of the sterilization tank 1 to the outside of the sterilization tank 1 and exists outside the sterilization tank 1. The other end of the ultraviolet wave guiding means 25 is connected to the ultraviolet ray generator 24.

  The ultraviolet ray generator 24 will be described with reference to FIGS. The ultraviolet ray generator 24 includes a rod-like light source 110 that emits ultraviolet rays, and a condensing device that collects the ultraviolet rays emitted from the rod-like light source 110. The rod-like light source 110 includes a cylindrical or polygonal column base 111, The plurality of deep ultraviolet light emitting diodes 112, 112,... Have a specific emission spectrum, and the optical axis of each deep ultraviolet light emitting diode 112 is the central axis of the substrate 111. Such an ultraviolet ray generator that is arranged on the side surface of the base 111 so as to pass through 114 and emits deep ultraviolet rays radially with respect to the central axis 114 is described in Japanese Patent No. 5591305 (Patent Document 5). The contents of which are incorporated herein by reference.

  FIG. 6 shows a transverse sectional view and a longitudinal sectional view of the rod-shaped light source (rod-shaped ultraviolet light emitting module) 110 (when cut along the XX ′ plane). As shown in FIG. 6, the rod-shaped light source 110 has a plurality of deep ultraviolet light emitting diodes 112, 112,... (Hereinafter simply referred to as “deep ultraviolet LED 112”) having a specific emission spectrum on the surface of the cylindrical substrate 111. .) Are aligned, and a cooling medium flow path 113 is formed inside the cylindrical base 111. Further, the cylindrical substrate 111 on which the deep ultraviolet LED 112 is mounted is covered with a cover 116 formed of an ultraviolet light transmissive material such as quartz. The cover 116 is attached to the cylindrical substrate 111 in an airtight or watertight manner using a sealing member 117 such as a sealant, packing, or O-ring, and an inert gas is provided inside the cover 116 to enhance the durability of the deep ultraviolet LED 112. Or dry air is enclosed.

  The deep ultraviolet LEDs 112, 112,... Are arranged with the elements mounted on the submount or housed in a package, and emit ultraviolet rays in a certain direction. Although not shown, the submount or package is formed with wiring for supplying power to the deep ultraviolet LED 112 from the outside, a circuit for operating the deep ultraviolet LED 112 normally, and the like. The electric power is supplied through wiring formed on the surface or inside of the cylindrical substrate 111.

  The cylindrical substrate 111 functions as a support for fixing and holding the deep ultraviolet LED 112, and also has a function as a heat sink, and a cooling medium such as cooling water or cooling air is provided in the cooling medium channel 113 inside. By circulating 118, temperature rise due to heat generated by the deep ultraviolet LED 112 can be prevented, stable operation of the device can be facilitated, and device life can be extended.

  In order to efficiently remove the heat generated by the deep ultraviolet LED 112, the cylindrical substrate 111 is preferably mainly composed of a metal having high thermal conductivity such as copper or aluminum, ceramics, or the like. In order to increase the heat exchange area, it is preferable to groove the inner wall surface of the cooling medium flow passage 113. Further, when the cylindrical substrate 111 is made of a metal material, it is preferable that an insulating layer for insulation from a copper wire or a circuit for supplying power to the deep ultraviolet LED 112 from an external power source is formed. .

  A plurality of deep ultraviolet LEDs 112, 112,... Are arranged on the side surface of the cylindrical substrate 111 along the circumferential direction so that the optical axis 115 of each deep ultraviolet LED 112 passes through the central axis 114 of the substrate 111. . As a result, deep ultraviolet light emitted from the deep ultraviolet LED 112 is emitted radially with respect to the central axis 114 of the substrate 111. The optical axis 115 of the deep ultraviolet LED 112 means the central axis of the light beam emitted from the deep ultraviolet LED 112, and is almost synonymous with the traveling direction of the light beam. In addition, here, “arrangement so that the optical axis 115 passes through the central axis 114 of the base 111” means that the optical axis 115 is arranged so as to realize such a state as much as possible, and is slightly inclined from the state. There is no problem.

  FIG. 6 shows an example in which four deep ultraviolet LEDs are arranged in the circumferential direction of the substrate 111, but the present invention is not limited to this form, and the number of arranged deep ultraviolet LEDs 112 is outside the cylindrical substrate 111. It can be appropriately changed according to the diameter. The number of deep ultraviolet LEDs 112 arranged in the circumferential direction is usually in the range of 3 to 20, preferably 4 to 12. However, the larger the number of deep ultraviolet LEDs 112 arranged in the circumferential direction, the more emitted from the rod-shaped light source 110. Since the intensity of deep ultraviolet light (photon flux density) is high, when higher intensity deep ultraviolet light is required, the diameter of the cylindrical substrate 111 is increased, and the number of ultraviolet light emitting elements arranged in the circumferential direction is It can be increased beyond the above range.

  The deep ultraviolet LEDs 112, 112,... Are preferably arranged so as to form a row in the longitudinal direction of the cylindrical substrate 111 as shown in the longitudinal sectional view of FIG. At this time, the deep ultraviolet LEDs 112, 112,... Are preferably arranged so as to be densely and regularly arranged on the side surface of the cylindrical substrate 111 so that the light emission intensity in the axial direction of the rod-shaped light source 110 is uniform.

  7 and 8 show a cross-sectional view and a side view of the ultraviolet ray generator 24 having the rod-shaped light source 110. FIG. The ultraviolet ray generator 24 includes an emission side casing 125 whose inner surface is an emission side reflection mirror 120 made of an ellipse reflection mirror, and a condensing side reflection mirror 123 whose inner surface is made of an ellipse reflection mirror. A condensing side housing 126 in which an exit opening 130 is formed, and a main body 150 including a collimating optical system 140 disposed in the ultraviolet exit opening 130, and the rod-shaped light source 110 is inside the main body 150. Has been placed. In the main body 150, it is preferable that the emission side casing 125 and the condensing side casing casing 126 are detachable from each other or can be opened and closed using a hinge or the like. 7 and 8 of the main body 150 are provided with covers (not shown) for preventing ultraviolet rays from leaking to the outside.

  7 and 8, the exit-side reflecting mirror 120 and the condensing side reflecting mirror 123 are substantially elliptical reflecting mirrors having substantially the same shape. The shape of the internal space formed by coupling with the side housing 126 is an elliptical cross-section with two axes of the focal axis 121 of the exit-side reflecting mirror and the condensing axis 122 of the exit-side reflecting mirror, respectively. However, a portion corresponding to the opening 130 is missing.) The surfaces of the exit-side reflecting mirror 120 and the condensing-side reflecting mirror 123 are made of materials having a high reflectivity with respect to deep ultraviolet rays, such as platinum group metals such as Ru, Rh, Pd, Os, Ir, and Pt, Al, Ag, Ti, and the like. It is preferably composed of an alloy containing at least one of the above metals or magnesium oxide, and is formed of Al, a platinum group metal or an alloy containing a platinum group metal, or magnesium oxide because of its particularly high reflectance. It is particularly preferred.

  The condensing-side reflecting mirror 123 and the condensing-side housing 126 are provided with an ultraviolet emitting opening 130 in a slit shape, and the condensed ultraviolet is converted into a parallel or substantially parallel light flux in the opening 130. A collimating optical system 140 is disposed. The collimating optical system 140 is preferably made of a material having high ultraviolet transparency such as synthetic or natural quartz, sapphire, or ultraviolet transmissive resin. The collimating optical system 140 is preferably detachably attached to the ultraviolet light emitting opening 130.

  In the ultraviolet ray generator 24, the rod-shaped light source 110 is disposed so that the central axis 114 thereof coincides with the focal axis 121 of the exit side reflection mirror. Since the rod-shaped light source 110 is disposed at such a position, the deep ultraviolet light emitted radially from the rod-shaped light source 110 is reflected by the emitting-side reflecting mirror 120 and the collecting-side reflecting mirror 123, and the collecting-side reflecting mirror. The condensed deep ultraviolet light is converged so as to converge on the focal axis 124 (that is, the condensing axis 122 of the output side reflection mirror), and the condensed deep ultraviolet light is passed through one of the ultraviolet wave guide means 25 from the ultraviolet emission opening 130. It is incident on the end (on the opposite side of the end connected to the optical plate 21).

  Thus, in principle, the ultraviolet ray generator 24 can condense all of the deep ultraviolet rays emitted radially from the rod-shaped light source 110 onto the focal axis 124 of the condensing side reflection mirror 123, and the deep ultraviolet ray emitting aperture. It is also possible to effectively use deep ultraviolet rays emitted in a direction that does not face the portion 130 (for example, the opposite direction or the lateral method). That is, in the rod-shaped light source 110, it is not necessary to arrange all of the deep ultraviolet LEDs 112, 112,... On the same plane so that the optical axis 115 is directed toward the ultraviolet ray emitting opening 130, and is directed in the lateral direction or the opposite direction. It can also be arranged. Therefore, the rod-shaped light source 110 can greatly increase the number of deep ultraviolet light emitting diodes arranged per unit space, and the ultraviolet ray generator 24 can supply higher intensity ultraviolet rays to the light guide plate 21.

  The ultraviolet sterilizer of the present invention is not limited to that shown in the drawings, and can be arbitrarily modified and applied without departing from the spirit of the present invention.

  For example, a temperature control means such as a cooler or a heat exchanger is provided upstream of the sterilization tank 1 so that the temperature of the liquid to be sterilized supplied to the sterilization tank exceeds 0 ° C. and is 10 ° C. or less. Good. Similarly, dissolved oxygen reduction or removal means such as a bubbling device for bubbling nitrogen gas or hydrogen gas may be installed upstream of the sterilization tank 1.

  Furthermore, while maintaining the state where ultraviolet light having a wavelength of 400 nm or less is blocked downstream from the sterilization tank 1, the liquid to be sterilized with ultraviolet light is filled and sealed in a container that does not transmit ultraviolet light having a wavelength of 400 nm or less. A filling means for stopping may be arranged.

DESCRIPTION OF SYMBOLS 1 Sterilization tank 1a Inlet 1b Outlet 2,1002, Surface light source 21 Light guide plate 21a, 21b (A pair of) UV light emission surface 21c, 21d End (of light guide plate) 22, 112 Deep ultraviolet light emitting diode 23 Light diffusion dot 23a Light diffusing dot base material 23b Light diffusing agent 23c Reflective film 24 Ultraviolet generator 25 Ultraviolet wave guide means 26 Ultraviolet light emitting diode 3 (slit-shaped) flow path 5 Liquid to be sterilized 110, 3110 Rod-shaped light source 111 (cylindrical or polygonal columnar) ) Substrate 120 Outgoing side reflection mirror 121 Focal axis 122 of outgoing side reflection mirror Condensing axis 125 of outgoing side reflection mirror Outgoing side housing 123 Condensing side reflection mirror 124 Focal axis 126 of condensing side reflection mirror Condensation side housing 130 Deep UV Light Exit 140 Collimating Optical System 150 Main Body 100, 1100 Liquid Sterilizer

Claims (5)

It is an ultraviolet sterilizer that sterilizes the liquid to be sterilized by irradiating the liquid to be sterilized with ultraviolet light, which contains an organic substance consisting of saccharides and / or fragrance components and water, respectively, as a liquid to be sterilized,
The ultraviolet sterilizer has a treatment tank for irradiating the liquid to be sterilized with ultraviolet light, and a supply means for supplying the fluid to be sterilized to the treatment tank,
In the treatment tank, a plurality of independent flow paths each having a predetermined width are arranged in parallel by disposing a plurality of partition walls in parallel with a predetermined gap.
At least one of the opposing wall surfaces of each of the plurality of flow paths has an ultraviolet light emitting surface;
The region irradiated with ultraviolet rays is irradiated with ultraviolet rays from one direction or from two opposite directions. Further, the irradiance of the transmitted ultraviolet rays when the irradiated ultraviolet rays pass through the layer to be sterilized is 0.001 mW / cm ^2. When the thickness of the layer of the liquid to be sterilized is defined as an effective optical path length, the width of each of the plurality of flow paths is equal to or less than the sum of the effective optical path lengths of the ultraviolet rays irradiated from the ultraviolet light emitting surface,
The ultraviolet light emitting surface emits ultraviolet light having a total sum of relative intensities of ultraviolet rays in a wavelength region of 260 nm or more and 280 nm or less being 90% or more of a sum of relative intensities in all wavelength regions,
That there is no photocatalytic substance in the portion in contact with the liquid to be sterilized in the flow path;
The ultraviolet sterilizer is characterized in that the taste and flavor are not impaired by suppressing the generation of active species . The ultraviolet sterilizer according to claim 1 , wherein the apparatus is for sterilizing a liquid to be sterilized which is a beverage or liquid seasoning further containing nitrate nitrogen . The ultraviolet light emitting surface is covered with a resin film that transmits ultraviolet rays in a wavelength region of 253 nm or more and 280 nm or less and whose ultraviolet transmittance having a wavelength of 265 nm is 10% or more higher than the transmittance of ultraviolet rays having a wavelength of 220 nm. The ultraviolet sterilizer according to claim 1 or 2 . The ultraviolet sterilizer according to any one of claims 1 to 3 , further comprising a temperature control means. The ultraviolet sterilizer according to any one of claims 1 to 4 , further comprising means for reducing or removing dissolved oxygen.

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