JP2004154742A - Water treatment apparatus and water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment apparatus which can permanently maintain a sterilization effect by photocatalysts and are high in the sterilization effect, and a water treatment method. <P>SOLUTION: The water treatment apparatus has a pump 20 for flushing water 12 to be treated, such as bath water, and a reaction vessel 32 disposed in mid-way of piping 16 in which the water 12 to be treated flows. The reaction vessel 32 is internally provided with large-surface area materials 30, such as wire-shaped materials made of titanium or titanium alloy. An ozone generator 26 for injecting ozone into the water 12 to be treated is connected to the upstream side of the materials 30 and a UV light source 34 for irradiating the materials 30 with UV rays is disposed. The materials 30 made of the titanium or titanium alloy form the photocatalysts of titanium dioxide at all times as the titanium atoms of the materials are oxidized by the ozone even if the photocatalysts of the titanium dioxide on the surfaces are peeled off. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water treatment apparatus and a water treatment method for sterilizing water such as bathtub water, domestic wastewater, drinking water, pool water, cooling water, washing water, stored water, aquaculture water, and industrial wastewater.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. H8-89725 [Patent Document 2] Japanese Patent Application Laid-Open No. H11-262759 Conventionally, for example, bath water in hot springs and health facilities is circulated while temperature control, sterilization, and removal of suspended matter are performed. Is being done. The bathtub water had been cleaned to a certain degree through a filtration tank containing mineral particles and a sterilizer using an ozone injection device, and circulated by a circulation pump.
[0003]
In the above configuration, the amount of ozone required for sterilization in a large-scale bath is large, and it is necessary to use high-concentration ozone. However, high-concentration ozone which was not completely dissolved in the water to be treated with high-concentration ozone was discharged into the air, which was not preferable. Further, in the case of circulating water in a large-scale bath facility, there is a problem that the amount of circulating hot water is large and low-concentration ozone results in a large-sized ozone generator and poor efficiency.
[0004]
On the other hand, as disclosed in Patent Documents 1 and 2, a reaction vessel provided with a photocatalyst is provided in the middle of a path for circulating the water to be treated, and the reaction vessel is irradiated with ultraviolet rays, and the water to be treated is treated by the photocatalyst. Those that render the bacteria harmless have also been proposed. In this water treatment apparatus, a net sprayed with titanium oxide is placed in a reaction vessel and irradiated with an ultraviolet lamp to pass water to be treated and sterilized by the action of a photocatalyst. Further, Patent Document 2 proposes a processing method for supplying a gas containing ozone into the water to be treated by using a similar apparatus.
[0005]
The principle of the sterilization treatment using the photocatalyst is as follows. When a photocatalyst such as titanium oxide, which is a semiconductor substance, is irradiated with ultraviolet light having a wavelength of 400 nm or less, holes are generated in the valence band and electrons are generated in the conduction band. The oxidation potential of these holes is higher than the oxidation potential of fluorine, ozone, hydrogen peroxide, etc., and organic substances are completely oxidized and decomposed by a photocatalyst, and finally are completely oxidized to carbon dioxide gas, water, sulfuric acid, nitric acid, etc. Is done. The mechanism of the oxidation reaction by the photocatalyst is that the oxidation reaction is caused by a hole generated when the photocatalyst is irradiated with ultraviolet light or a highly reactive hydroxyl radical (OH radical) generated by a reaction between the hole and water. It is believed that. At this time, a reduction reaction between electrons generated simultaneously with holes generated when the ultraviolet rays are irradiated and oxygen gas or the like proceeds in parallel. The action of the photocatalyst has a stronger germicidal ability than conventional germicides such as ozone, hydrogen peroxide and chlorine due to such a strong oxidation reaction, and also has a function of decomposing organic substances. In addition, since the lifetime of holes and OH radicals generated by light irradiation is as short as milliseconds or less, there is no residue after treatment such as an oxidizing agent such as ozone or hydrogen peroxide, and a device for treating the residual oxidizing agent is unnecessary. There is an advantage that there is. For this reason, many water treatment apparatuses using a photocatalyst have been proposed.
[0006]
[Problems to be solved by the invention]
However, since the action of the photocatalyst occurs only on the surface of the photocatalyst irradiated with light, it is necessary to increase the surface area of the photocatalyst to increase the contact efficiency with the water to be treated in order to perform the treatment efficiently. In addition, holes or OH radicals generated when the photocatalyst is irradiated with ultraviolet light have a short life, and therefore need to be reacted in a short time. Further, there is a problem that ultraviolet light is easily absorbed by water and is easily attenuated in water.
[0007]
Furthermore, in the case of the above-mentioned conventional technology, the oxidizing and disinfecting actions occur only on the surface of the photocatalyst irradiated with ultraviolet rays, and only a small part of the water to be treated comes into contact with the surface of the net sprayed with the photocatalyst such as titanium oxide on the surface. Only the processing was performed, and the processing capacity was low. In addition, a net on which a photocatalyst such as titanium oxide is sprayed has a low durability because the photocatalyst on the surface is easily separated. When the sprayed photocatalyst disappears, there is a problem that the function as the photocatalyst is lost and that part must be replaced.
[0008]
The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide a water treatment apparatus and a water treatment method which can maintain a sterilizing action by a photocatalyst permanently and have a high sterilizing action. And
[0009]
[Means for Solving the Problems]
According to the present invention, a titanium or titanium alloy net or a large surface area material of a linear assembly is provided in a reaction vessel provided in the middle of a pipe through which water to be treated flows, and a photocatalyst comprising titanium oxide on the surface of the large surface area material Is formed, ozone is injected into the water to be treated on the upstream side of the large surface area material, and the large surface area material is irradiated with ultraviolet rays, and the water to be treated is sterilized by ozone and sterilized by the photocatalyst, Further, there is provided a water treatment method in which titanium oxide can be always formed on the surface of the titanium or titanium alloy by the ozone.
[0010]
The present invention also provides a pump for flowing the water to be treated, a reaction vessel provided in the middle of a pipe through which the water to be treated flows, a large surface area material made of titanium or a titanium alloy provided in the reaction vessel, The water treatment apparatus includes an ozone injection means such as an ozone generator for injecting ozone into the water to be treated on the upstream side of the surface area material, and an ultraviolet light source for irradiating the large surface area material with ultraviolet light. The reaction vessel may also serve as a processing tank such as a hair catcher.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of a water treatment apparatus of the present invention. A water treatment apparatus 10 of this embodiment treats bath water circulated in a hot spring or a health facility as treated water 12. Is what you do. The water treatment apparatus 10 of this embodiment includes a hair catcher 18 for collecting hair, a circulation pump 20 provided downstream of the hair catcher 18, a circulation pipe 16 through which the water to be treated 12 in the large bath 14 flows and circulates. have. A filtration tank 22 is provided downstream of the circulation pump 20, a heat exchanger 24 is provided downstream of the filtration tank 22, and the temperature of the water to be treated 12 is raised to a predetermined temperature. The treatment water 12 is returned to the large bath 14.
[0012]
An ozone pipe 28 connected to an ozone generator 26 is connected between the water intake 16 a of the large tub 14 of the circulation pipe 16 and the hair catcher 18. The ozone generator 26 generates ozone in the air by electric discharge and sends ozone gas of a predetermined concentration. The generated ozone is mixed into the water to be treated 12 of the circulation pipe 16 from the ozone pipe 28 and is dissolved in the water to be treated 12.
[0013]
As shown in FIG. 2, the circulation pipe 16 between the hair catcher 18 and the circulation pump 20 has a net or titanium wire, an aggregate of fibrous titanium material, and other porous materials made of titanium or a titanium alloy. A reaction vessel 32 containing a large surface area material 30 such as a titanium material is attached. The high surface area material 30 may have a titanium dioxide photocatalyst formed on the surface of titanium or a titanium alloy in advance, or may use ozone to form a titanium dioxide photocatalyst during use, as described later.
[0014]
At least a part of the reaction vessel 32 is transparent, and the transparent part is formed of a material that easily transmits ultraviolet light. An ultraviolet light source 34 such as a fluorescent lamp for irradiating ultraviolet light is disposed facing the transparent portion of the reaction vessel 32. The ultraviolet light source 34 desirably contains a large amount of ultraviolet light (wavelength of 410 nm or less) in which a photocatalyst of titanium dioxide efficiently generates holes and electrons. An ultraviolet lamp, a low-pressure or high-pressure mercury lamp, or a wavelength of 300 to 400 nm is used. Fluorescent lamp or the like. Further, a plurality of LEDs that emit ultraviolet light may be arranged.
[0015]
Next, the operation and operation of this embodiment will be described. The water to be treated 12 is pressurized by a circulation pump 20 and sent to a filtration tank 22 of the water treatment apparatus 10 under pressure to remove foreign substances and the like to some extent, and is heated to a certain temperature via a heat exchanger 24 to form a large bath. Returned to 14. Further, on the upstream side of the circulation pump 20, the water to be treated 12 from the large bath 14 is removed from the hair and the like by the hair catcher 18 by the circulation pipe 16, and is sucked into the circulation pump 20 via the reaction vessel 32. At this time, in the circulation pipe 16 on the upstream side of the reaction vessel 32, the ozone-containing air from the ozone generator 26 is mixed with the water to be treated 12, and the water to be treated 12 having the ozone has a large surface area in the reaction vessel 32. It passes between the materials 30. On the surface of the large surface area material 32, a photocatalyst by titanium dioxide is formed, and around this photocatalyst 32, sterilization by OH radicals and decomposition of organic substances are performed by ultraviolet irradiation. This sterilization mechanism is as described above. At the same time, ozone sterilization is also performed. When the photocatalyst on the surface of the titanium or titanium alloy material 30 is peeled off, the ozone in the liquid to be treated 12 reacts with the exposed titanium atoms, and the photocatalyst of titanium dioxide is easily deposited on the surface. It is formed.
[0016]
According to the water treatment method and apparatus of this embodiment, sterilization and decomposition of organic substances can be performed on the water to be treated 12 with high efficiency using a photocatalyst, and sterilization with ozone is also performed. Bath water can be reliably prevented from being contaminated, and a large amount of water to be treated 12 can be treated. Further, even if the photocatalyst of titanium dioxide of the large surface area material 30 in the reaction vessel 32 is peeled off due to long-term use, the ozone from the ozone generator 26 causes the surface of the large surface area material 30 made of titanium or a titanium alloy to be exposed. In this method, titanium dioxide is always generated and the photocatalyst does not disappear.
[0017]
In addition, in the photocatalyst at the time of ultraviolet light irradiation, electrons generated simultaneously with holes react quickly with oxygen to generate superoxide (O ₂ ⁻ ). At this time, if oxygen is insufficient, unreacted electrons are recombined with holes to inhibit the oxidation reaction of holes. However, in the present invention, a sufficient oxygen-containing gas including ozone is supplied to the photocatalyst surface. Therefore, the recombination of the electrons and holes can be prevented, and as a result, the efficiency of the oxidation reaction between the water to be treated 12 and the photocatalyst of titanium dioxide can be increased.
[0018]
Further, according to this embodiment, due to the mixing and stirring effect of the water to be treated 12 in the reaction vessel 32, the water to be treated 12 can be efficiently brought into contact with the surface of the photocatalyst, and sufficient oxygen is supplied, and titanium dioxide or the like is supplied. The reaction efficiency between the photocatalyst and the water to be treated 12 can be dramatically increased.
[0019]
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same members as those in the above embodiment are denoted by the same reference numerals, and the description will be omitted. The water treatment apparatus 40 of this embodiment includes a secondary-side pressurizing pump 44 that is provided downstream of the heat exchanger 24 and pressurizes the water to be treated 12 that is sent to the large bath 14 by bypassing the bypass pipe 42. The ozone generator 26 is connected to the bypass pipe 42. The reaction vessel 32 is provided in the circulation pipe 16 on the downstream side of the portion where the bypass pipe 42 is connected to the circulation pipe 16.
[0020]
Ozone from the ozone generator 26 is mixed and dissolved in the water to be treated 12 flowing through the bypass pipe 42 via the ozone pipe 28. As shown in FIG. 4, a connection between the bypass pipe 42 and the ozone pipe 28 is provided downstream of the secondary-side pressurizing pump 44, and a mixer 46 is provided at this connection. The mixer 46 has a Venturi tube inside, and the ozone pipe 28 is connected to the throat of the Venturi tube. The ozone pipe 28 is sucked into the mixer 46 by a negative pressure to efficiently mix and dissolve.
[0021]
Further, the connection between the bypass pipe 42 and the ozone pipe 28 may be provided upstream of the secondary side pressure pump 44 as shown in FIG. In this case, the ozone and the water to be treated 12 are sufficiently stirred by the secondary side pressure pump 44, and the ozone is dissolved in the water to be treated 12.
[0022]
The water to be treated 12 mixed with ozone is also sent to the reaction vessel 32 by the water treatment apparatus 40 of this embodiment, and sterilization by ozone and photocatalysis by titanium dioxide are performed in the reaction vessel 32 to sterilize and decompose organic substances. Is performed efficiently. Furthermore, even if the photocatalyst on the surface of the high-surface-area material 30 in the reaction vessel 32 is peeled off, titanium atoms are oxidized to titanium dioxide one after another by ozone, and the photocatalyst of titanium dioxide does not peel off.
[0023]
The drawing processing method and apparatus of the present invention are not limited to the above-described embodiment, and the large surface area material 30 may be an aggregate formed by forming a linear material of titanium or a titanium alloy into a predetermined shape, or a titanium or titanium alloy. A collection of needle-like bodies or granular bodies of a titanium alloy or a collection of porous bodies may be used. Further, as shown in FIG. 6, the ultraviolet light sources 34 may be provided at three places around the reaction vessel 32, or may be provided at a plurality of places as appropriate. This promotes the photocatalytic reaction more efficiently.
[0024]
Further, as shown in FIG. 7A, an ultraviolet light source 34 may be arranged in the reaction vessel 32. Thereby, the attenuation of the ultraviolet rays by the reaction vessel 32 can be eliminated, and the reaction of the photocatalyst can be caused more efficiently. Further, as shown in FIG. 7 (B), the reaction vessel 32 may be used also as a processing tank such as the hair catcher 18. For example, a hair catcher basket 48 is provided on the inlet side of the water to be treated 12 of the reaction vessel 13, and the large surface area material 30 is provided downstream on the downstream side of the partition wall 50 in the reaction vessel 32. This can further reduce the size and space of the device.
[0025]
The water to be treated, which is the object of the water treatment method and apparatus of the present invention, can be used for domestic wastewater, industrial water, and all other water that requires sterilization, in addition to hot water in a bathtub.
[0026]
【The invention's effect】
According to the water treatment method and apparatus using a photocatalyst according to the present invention, the water to be treated is subjected to sterilization and decomposition of organic substances by the photocatalyst together with ozone, so that harmful organic substances and bacteria contained in the water to be treated are included. Microorganisms, odorous substances, hardly decomposable substances and the like can be efficiently sterilized, decomposed and removed in large quantities. Furthermore, since the titanium oxide or titanium alloy is used to form the large surface area material with the photocatalyst formed on the surface, even if the titanium dioxide photocatalyst peels off due to long-term use, the strong oxidizing action of ozone will remove the titanium atoms of the large surface area material. Oxidizes and constantly forms a titanium dioxide photocatalyst on the surface. Accordingly, the high surface area material can semipermanently function as a photocatalyst, and can solve problems such as separation of the photocatalyst due to use.
[Brief description of the drawings]
FIG. 1 is a schematic piping diagram of a water treatment device according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the reaction vessel of this embodiment.
FIG. 3 is a schematic piping diagram of a water treatment apparatus according to a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view showing the piping of the reaction vessel of this embodiment.
FIG. 5 is a longitudinal sectional view showing another piping of the reaction vessel of this embodiment.
FIG. 6 is a schematic sectional view showing an arrangement of an ultraviolet light source according to another embodiment of the present invention.
FIG. 7 is a schematic sectional view (A) of a reaction vessel provided with an ultraviolet light source according to another embodiment of the present invention, and a schematic sectional view (B) of a reaction vessel also serving as a hair catcher.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Water treatment apparatus 12 Treated water 14 Large bath 16 Circulation piping 20 Circulation pump 22 Filtration tank 24 Heat exchanger 26 Ozone generator 30 Large surface area material 32 Reaction vessel 34 Ultraviolet light source

Claims (2)

A large surface area material made of titanium or a titanium alloy is provided in a reaction vessel provided in the middle of a pipe through which water to be treated flows, and a photocatalyst made of titanium oxide is formed on the surface of the large surface area material. Inject ozone into the water to be treated, irradiate the large surface area material with ultraviolet rays, sterilize the water to be treated with ozone, sterilize with the photocatalyst, and oxidize the titanium or titanium alloy surface with the ozone. A water treatment method, wherein titanium is formed. A pump for flowing the water to be treated, a reaction vessel provided in the middle of a pipe through which the water to be treated flows, a large surface area material made of titanium or a titanium alloy provided in the reaction vessel, and an upstream side of the large surface area material A water treatment apparatus comprising: an ozone injection means for injecting ozone into the water to be treated; and an ultraviolet light source for irradiating the large surface area material with ultraviolet light.

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