JP2001259621A - Water treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treating device efficiently decomposing and removing organic compounds in water to be treated by using an excimer lamp without requiring the addition of a special component. SOLUTION: In the water treating device provided with a first treating mechanism having an oxygen dissolving means for dissolving oxygen into influent water to be treated, and a second treating mechanism for treating the water to be treated by UV rays irradiated from the excimer lamp, the water to be treated with dissolved oxygen concentration adjusted to more than a specified value by the first treating mechanism is fed to the second treating mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a water treatment apparatus for removing harmful components contained in water to be treated by ultraviolet rays.

[0002]

2. Description of the Related Art Conventionally, activated carbon adsorption treatment has been used as a method for treating organic compounds in water that cause water or air pollution.
Ozone treatment and film treatment utilizing the oxidizing power of ozone are being carried out. Among these treatment methods, activated carbon treatment is not economical because activated carbon is an adsorbent, and its performance decreases when the adsorption amount is saturated, and it is necessary to replace it with a new one in order to maintain purification performance. It takes time to dispose of used activated carbon. In addition, in the method of regenerating activated carbon, the apparatus becomes complicated and large. Furthermore, harmful organic compounds that can be adsorbed by activated carbon are generally hydrophobic organic substances or organic substances having a non-polar functional group. Therefore, organic substances having high hydrophilicity or polarity cannot be adsorbed and removed by activated carbon. Another problem is that it is difficult to remove by adsorption. In addition, the ozone treatment has excellent decolorization, deodorization and sterilization effects, but has a low function of decomposing pollutants. Membrane treatment is excellent from the viewpoint of water treatment, but has the problem of replicating waste.

Therefore, in order to comprehensively solve the problems of the above-mentioned processing methods, a low-pressure mercury lamp or an excimer lamp and an oxidizing agent are used.
For example, a composite treatment with ozone gas and hydrogen peroxide is known (Japanese Patent Application Laid-Open No. 11-33569). In the treatment method described, active species having extremely strong oxidizing power are generated by an oxidizing agent, and the water to be treated is treated with the generated active species.
The active species is a stronger oxidizing agent than ozone or hydrogen peroxide, and can decompose and remove harmful components during processing that cannot be decomposed by ozone alone. In addition, it is an effective treatment method that has excellent deodorizing, decoloring and sterilizing effects and does not generate secondary waste.

There is also known a method of treating water to be treated without adding an oxidizing agent to the water to be treated by using an excimer lamp which emits, at a high output, ultraviolet rays having a wavelength for generating active species from dissolved oxygen in the water. ing. (JP-A-10-2167
16)

[0005]

However, the above-mentioned treatment method using ozone or hydrogen peroxide in combination with ultraviolet rays has a strong oxidizing and oxidizing effect, and can clean organic compounds which are difficult to treat by other methods. Although it has extremely excellent characteristics, unreacted hydrogen peroxide and ozone gas have to be removed in a subsequent step, and there has been a problem that the apparatus becomes complicated and large.

In the case of excimer lamp single treatment,
It is not necessary to remove the unreacted oxidizing agent, but since the amount of active species generated varies depending on the dissolved oxygen concentration during the treatment, the treated water containing the same concentration of the organic compound was similarly irradiated with an excimer lamp. Even in this case, there is a problem that the decomposition efficiency varies depending on the concentration of dissolved oxygen contained in the water to be treated. In addition, there is a problem that the time required for the treatment of the water to be treated having a low dissolved oxygen concentration is increased, and the running cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a water treatment apparatus using ultraviolet light includes:
Water comprising an oxygen dissolving means, a first treatment mechanism for dissolving oxygen in the water to be treated, and a second treatment mechanism for treating the water to be treated treated by the first treatment mechanism with ultraviolet rays emitted from an excimer lamp. The object of the present invention is to provide an apparatus for purifying water by controlling the oxygen dissolving means so that the concentration of dissolved oxygen in the water to be treated on the outlet side of the first treatment mechanism is maintained at a predetermined value or more. And According to the present invention, the water to be treated can be treated without adding an oxidizing agent and always at a stable and high decomposition efficiency, so that the treatment cost and the treatment time can be reduced.

[0008]

Means for Solving the Problems and Action / Effect As a result of the research of the present invention, although the value is affected by the concentration and type of the organic compound in the water to be treated, the dissolved oxygen concentration in the water to be treated depends on the decomposition efficiency. Was found to have a significant effect on That is, it has been found that if the dissolved oxygen concentration is maintained at a constant level, the efficiency of decomposing organic compounds using an excimer lamp increases, and stable processing is possible.

Accordingly, the present invention comprises a first treatment mechanism having oxygen dissolving means for dissolving oxygen in the inflowing water to be treated, and a second treatment mechanism for treating the water to be treated with ultraviolet rays emitted from an excimer lamp. In the water treatment apparatus, the water to be treated whose dissolved oxygen concentration has been adjusted to a predetermined value or more by the first treatment mechanism is supplied to the second treatment mechanism.

First, FIG. 1 shows a change in the concentration of dissolved oxygen in the water to be treated when the water to be treated is irradiated with a low-pressure mercury lamp and an excimer lamp which are usually used for water treatment. As can be seen from FIG. 1, when an excimer lamp is used, the dissolved oxygen in the water to be treated is radiated with high output from the dissolved oxygen in the water at a wavelength that generates active species that contribute to the decomposition of organic compounds. It can be seen that the oxygen concentration decreases significantly.

FIG. 2 shows the initial dissolved oxygen concentration and organic matter concentration (TO) in the water treatment using an excimer lamp.
C) shows the change. Here, DO means dissolved oxygen.
As described above, active species that contribute to organic matter decomposition are generated from dissolved oxygen in water by ultraviolet light output from an excimer lamp, and the active species contributes to organic matter decomposition.
It can be seen that the higher the dissolved oxygen concentration, the higher the organic matter decomposition ability. Also, it is understood that the dissolved oxygen content is preferably 6 ppm or more.

[0012] With the above structure, the water to be treated, in which the concentration of dissolved oxygen contributing to the decomposition efficiency is always kept at a certain concentration or more, can be irradiated with ultraviolet light output from an excimer lamp. High efficiency,
Further, a water treatment apparatus exhibiting a stable decomposition ability can be provided.

When dissolving oxygen in the water to be treated, it is conceivable that oxygen gas is dissolved by bubbling into the water to be treated. Oxygen gas present as air bubbles reacts with ultraviolet light to produce ozone gas harmful to the human body,
It is necessary to separately provide a step of treating the ozone gas, and the apparatus becomes large.

By separating the step of dissolving oxygen and the step of irradiating ultraviolet rays as in the structure of the present invention, such ozone gas is not generated, and the ozone gas removing step can be omitted.

Preferably, in the water treatment apparatus according to claim 1, a circulation path is provided for allowing the treated water flowing out of the second treatment mechanism to flow again into the first treatment mechanism, so that the water to be treated is connected to the first treatment mechanism. Processing is performed while circulating through the two processing mechanisms.

As shown in FIG. 1, depending on the concentration of organic compounds contained in the water to be treated, when water treatment is carried out using an excimer lamp, the excimer lamp has an activity that contributes to decomposition of organic compounds from dissolved oxygen in the water. Since high-output ultraviolet rays having a wavelength for generating seeds are irradiated, the concentration of dissolved oxygen in the water to be treated decreases. Therefore, when the dissolved oxygen concentration becomes insufficient in the treatment of the organic compound with ultraviolet rays in the second treatment mechanism, the decomposition rate may be reduced.
From this, by adopting the above configuration, the dissolved oxygen reduced in the ultraviolet treatment by the excimer lamp in the second treatment unit can be supplied again to the water to be treated in the first treatment unit by supplying oxygen thereto, so that rapid and high decomposition is achieved. The organic compound can be efficiently and stably processed.

Preferably, the apparatus further comprises a dissolved oxygen detector for detecting the concentration of dissolved oxygen in the water to be treated.

Even when there is no dissolved oxygen detector, the water to be treated can be kept at a dissolved oxygen concentration of a predetermined value or more by adding oxygen excessively by the oxygen dissolving means. By providing this, the dissolved oxygen concentration can be detected, and an appropriate amount of oxygen can be supplied. Therefore, the processing cost can be reduced, and the oxygen can be dissolved smoothly and in a short time.

Further, as a preferred embodiment of the present invention, means for detecting the flow rate of the treated water passing through the second treatment mechanism is provided, and the ultraviolet output from the excimer lamp is controlled according to the flow rate.

In the conventional water treatment apparatus, the ability to decompose and remove organic compounds does not change according to the flow rate of the treated water. Therefore, when the flow rate of the treated water is an appropriate amount, sufficient performance is exhibited. However, when the flow rate is increased, the organic compound removal performance is insufficient, and the water does not sufficiently remove the organic compound.

The water treatment apparatus of the present invention is provided with a means for detecting the flow rate of the treated water passing through the second treatment mechanism, and is capable of controlling the ultraviolet output from the excimer lamp according to the flow rate. Therefore, even if the flow rate changes, the performance of decomposing and removing organic compounds does not decrease. As a result, even if the flow rate of water changes, safe and clear water from which organic compounds have been removed can be supplied.

Preferably, the oxygen dissolving means is an ejector.

The ejector can efficiently dissolve oxygen in the water to be treated, and is compact, which contributes to a reduction in the scale of the apparatus.

Preferably, the oxygen dissolving means is a pump.

Since the supply amount of oxygen can be forcibly increased by using the pump, the oxygen can be more quickly dissolved in the water to be treated.

Still more preferably, the oxygen dissolving means uses a pump and a porous body.

When oxygen is mixed as bubbles and dissolved in the water to be treated, its solubility depends on the contact area between the bubbles and the water to be treated. Therefore, oxygen can be more rapidly dissolved in the water to be treated by mixing minute bubbles into the water to be treated using the pump and the porous body.

Preferably, the excimer lamp is 1
It is a lamp that emits ultraviolet light having a main wavelength of 50 nm or more and 200 nm or less.

The shorter the wavelength of ultraviolet light, the higher the energy of photons. The energy of photons having a wavelength of 200 nm or less readily breaks bonds such as carbon double bonds (C = C) in organic compounds that are difficult to decompose. It is known that it reacts with dissolved oxygen to generate active species having strong oxidizing power.
In addition, since ultraviolet rays having a wavelength of 150 nm or less are absorbed by water or a protective tube or a protective plate of an excimer lamp, the amount of ultraviolet rays that contribute to the decomposition of organic compounds is extremely small. Therefore, an organic compound in the water to be treated can be efficiently decomposed and removed by an excimer lamp having a main wavelength of ultraviolet light having a wavelength of 150 nm to 200 nm.

In a further preferred embodiment, the excimer lamp is a lamp which emits ultraviolet light having a main wavelength of 172 nm.

A xenon excimer lamp having an ultraviolet ray of 172 nm as a main wavelength can stably output ultraviolet light having a higher output than other excimer lamps at a high electrical conversion efficiency. Hydrogen peroxide can be generated well, and organic compounds in the water to be treated can be efficiently decomposed and removed.

As a further preferred embodiment, the excimer lamp is housed in a protective tube through which ultraviolet light can pass, or in a housing portion in which a part of the lamp housing portion is formed of a protective plate through which ultraviolet light can pass, and the atmosphere in the housing portion is reduced. 300 Torr
Or an atmosphere mainly containing a gas that does not absorb ultraviolet rays from an excimer lamp.

The ultraviolet light output from the excimer lamp is:
It hardly passes through a protective tube or a protective plate made of general soda lime glass or the like. Also, the transmittance is low in glass containing a large amount of components other than silicon and oxygen, such as natural quartz glass, but the transmittance is low in synthetic quartz glass and magnesium fluoride glass containing only trace amounts of components other than silicon and oxygen. high. Further, when the atmosphere in the storage section is an atmosphere containing oxygen, the intensity of ultraviolet rays is reduced by being absorbed by oxygen molecules. Therefore, the pressure is preferably 300 Torr or less, or nitrogen gas which is a gas which does not absorb ultraviolet rays from an excimer lamp.

Accordingly, the protective tube through which the ultraviolet rays from the excimer lamp can pass, or a part of the lamp accommodating portion is accommodated in the accommodating portion constituted by the protective plate capable of transmitting the ultraviolet light, and the atmosphere in the accommodating portion is 300 Torr or less. Alternatively, the organic compound in the water to be treated can be efficiently decomposed and removed by setting the atmosphere mainly containing a gas that does not absorb ultraviolet rays from the excimer lamp.

In a further preferred aspect, the member of the excimer lamp installation portion is made of a material that reflects ultraviolet light from the excimer lamp.

The ultraviolet light emitted from the excimer lamp is
It is absorbed by the inner wall of the excimer lamp installation part. In order to react with dissolved oxygen and organic compounds contained in the water to be treated and efficiently decompose and remove it, reduce the amount of ultraviolet light absorbed by the excimer lamp installation section and reflect it again by It is preferable to react with dissolved oxygen. For this reason, it is desirable that the material of the inner wall of the excimer lamp installation portion be made of aluminum, stainless steel, or the like having high ultraviolet reflectance.

Thus, the organic compound can be efficiently decomposed and removed by forming the member of the excimer lamp installation section to which the ultraviolet light from the excimer lamp is irradiated with a material that reflects the ultraviolet light from the excimer lamp.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below with reference to FIG. In FIG. 3, 1 is a pipe to be treated, 2 is a water pump, 3 is a reaction tank (a: first processing mechanism, b: second processing mechanism), 4 is oxygen supply means (a: air supply pump, b: porous) Body), 5 is an oxygen flow controller, 6 is a dissolved oxygen detector, 7 is an excimer lamp, 8 is a flow meter for treated water, 10 is an oxygen discharge pipe, and 12 is a degassing membrane.

Next, the operation of this embodiment will be described. First, the water to be treated is introduced into the reaction tank 3a by the water feed pump 2 through the water pipe 1 to be treated. Here, oxygen or oxygen containing accompanying gas is added to the reaction tank 3a as fine bubbles through the oxygen flow controller 5 and the porous body 4b by the air supply pump 4a. Thus, oxygen is sufficiently dissolved in the water to be treated. Usually, the initial dissolved oxygen concentration contained in the water to be treated differs depending on the concentration and type of the organic compound in the water to be treated. Therefore, when oxygen is dissolved in the water to be treated using the oxygen dissolving means, the dissolved oxygen detector 6 detects the concentration of dissolved oxygen in the water to be treated, and the oxygen flow controller 5 controls the oxygen supply amount, Control oversupply of oxygen. Next, the water to be treated, in which oxygen has sufficiently dissolved, passes through the flow meter 8 and the deaeration membrane 12, and is introduced into the reaction tank 3b in which the excimer lamp 7 is provided. At this time, even when air bubbles in the first processing mechanism enter the flow path from the first processing mechanism to the second processing mechanism, the air bubbles are removed by the deaeration film. Then, the treated water introduced into the second treatment mechanism is treated with the ultraviolet rays emitted from the excimer lamp 7 or the active species generated by the ultraviolet rays emitted from the excimer lamp 7 reacting with the dissolved oxygen in the water to be treated. The organic compounds in the water to be treated are decomposed. The ultraviolet output of the excimer lamp is controlled according to the flow rate detected by the water flow meter 8 to be treated.

FIG. 4 shows a second embodiment of the present invention. 11 is a discharge valve. The difference from the first embodiment is
As a configuration, a circulating path 9 is provided for causing the treated water flowing out of the second treatment mechanism to flow again into the first treatment mechanism, and the treated water is treated while circulating through the first treatment mechanism and the second treatment mechanism. As a result, the dissolved oxygen consumed in the second treatment mechanism can be supplemented by the first treatment mechanism at any time, so that the treatment of the water to be treated is performed more smoothly and in a shorter time. The treated water is discharged by opening the discharge valve 11.

In this embodiment, a degassing membrane has been described as an example of a means for removing air bubbles mixed in the flow path from the first processing mechanism to the second processing mechanism. However, air bubbles in the flow path can be removed. Anything may be used, and a method by centrifugation may be used.

If the present invention is used, a step of adding an oxidizing agent and removing ozone and the like harmful to the human body is unnecessary, and the concentration of dissolved oxygen contributing to the decomposition efficiency is always maintained at a predetermined value or more. Since the water can be treated, the water to be treated can be treated with a stable and high decomposition efficiency, and the treatment cost and the treatment time can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between irradiation time and dissolved oxygen concentration in irradiation with a low-pressure mercury lamp and an excimer lamp.

FIG. 2 is a diagram showing a change in TOC concentration depending on the concentration of dissolved oxygen in the initially treated water during excimer lamp irradiation.

FIG. 3 is a configuration diagram of a water treatment apparatus according to a first embodiment of the present invention.

FIG. 4 is a configuration diagram of a water treatment apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 1: water pipe to be treated 2: water pump 3: reaction tank (a: first processing mechanism, b: second processing mechanism) 4: oxygen supply means (a: air pump, b porous body) 5: oxygen flow controller 6: dissolved oxygen detector 7: excimer lamp 8: treated water flow meter 9: circulation path 10: oxygen discharge pipe 11: discharge valve 12: degassing membrane

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinra Endo 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Touchi Kiki Co., Ltd. (72) Inventor Shigeru Ando Nakajima, Kitakyushu-shi, Fukuoka 2-1-1, F-term (reference) in TOTO Kiki Co., Ltd. 4D037 AA01 AA05 AA11 AB01 BA18 BB01 BB02 BB07 CA12 4D050 AA01 AA12 AB07 BB01 BC09 BD02 BD03 BD06 BD08

Claims (11)

[Claims] 1. A water treatment system comprising: a first treatment mechanism having an oxygen dissolving means for dissolving oxygen in the inflowing water to be treated; and a second treatment mechanism for treating the water to be treated by ultraviolet rays emitted from an excimer lamp. In the apparatus, the water to be treated whose dissolved oxygen concentration has been adjusted to a predetermined value or more by the first treatment mechanism is supplied to the second treatment mechanism. 2. The water treatment apparatus according to claim 1, wherein a circulation path is provided for allowing the treated water flowing out of the second treatment mechanism to flow into the first treatment mechanism again, and the water to be treated is connected to the first treatment mechanism and the second treatment mechanism. The water treatment apparatus according to claim 1, wherein the treatment is performed while circulating the treatment mechanism. 3. The water treatment apparatus according to claim 1, further comprising a dissolved oxygen detector for detecting a dissolved oxygen concentration of the water to be treated. 4. The apparatus according to claim 1, further comprising means for detecting a flow rate of the water to be treated passing through said second processing mechanism, and controlling an ultraviolet output from an excimer lamp according to the flow rate. Water treatment equipment. 5. The water treatment apparatus according to claim 1, wherein said oxygen dissolving means is an ejector. 6. The water treatment apparatus according to claim 1, wherein said oxygen dissolving means is a pump. 7. The water treatment apparatus according to claim 6, wherein said oxygen dissolving means uses a pump and a porous body. 8. An excimer lamp having a wavelength of 150 nm or more
The water treatment apparatus according to claim 1, wherein the water treatment apparatus is a lamp that emits ultraviolet light having a main wavelength of not more than 00 nm. 9. The water treatment apparatus according to claim 1, wherein the excimer lamp is a lamp that emits ultraviolet light having a main wavelength of 172 nm. 10. The excimer lamp is housed in a protective tube through which ultraviolet light can pass, or in a housing portion in which a part of the lamp housing portion is formed of a protective plate through which ultraviolet light can pass, and the atmosphere in the housing portion is 300 Torr or less. The water treatment apparatus according to any one of claims 1 to 9, wherein the atmosphere is mainly composed of a gas that does not absorb ultraviolet light from an excimer lamp. 11. The member of the excimer lamp installation part,
The water treatment apparatus according to claim 1, wherein the water treatment apparatus is made of a material that reflects ultraviolet light from an excimer lamp.