JP2002028669A - Device and method for continuously treating water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an device and a method for continuously treating water containing organic matter with high efficiency. SOLUTION: Water, namely liquid to be treated, is continuously treated by decomposing materials dissolved in the liquid by using a photocatalyst, ultraviolet rays and ozone while agitating the liquid and further using a settling/ separating pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous water treatment apparatus and method for performing water treatment using a combination of a photocatalyst, ozone, and ultraviolet rays.

[0002]

2. Description of the Related Art Conventionally, a water treatment apparatus using a photocatalyst includes:
(1) A method of flowing photocatalyst particles into a processing solution (Japanese Patent Application Laid-Open No. H11-10136), (2) A photocatalyst is applied to the wall surface of a processing tank to be fixed, or a photocatalyst coated and fixed substance is inserted into the tank. (Japanese Patent Laid-Open No. 9-57279). Further, the ozone decomposition method of the water treatment apparatus using ozone and ultraviolet rays is described in (3) a method of bubbling ammonia gas with a diffuser tube (JP-A-11-19456), and (4) using a gas-liquid contact device such as an ejector. Method (Japanese Unexamined Patent Publication
309450).

The method (1) of flowing the photocatalyst into the treatment liquid has an effect of improving the establishment of contact with the photocatalyst and is effective for water treatment. However, the separation of the treatment liquid after treatment and the photocatalyst particles is difficult. It was difficult. In the method (2) of coating and immobilizing the photocatalyst, only the processing liquid in contact with the photocatalyst coating surface can be decomposed, so that the reaction efficiency is poor, and decomposition products of dissolved substances in the processing liquid adhere to the photocatalyst coating surface. However, there is a problem that the reaction efficiency is reduced.

A water treatment apparatus using a photocatalyst has a problem that the photocatalyst has a sufficient decomposition ability but the reaction speed is low, so that the processing speed of the processing solution is slow and a large amount of water is required to treat a large amount of water. was there.

In the method (3) of bubbling a gas with an air diffuser, the apparatus can have a simple structure, but it is difficult to reduce the diameter of bubbles to be formed, and it is difficult to improve the gas dissolving efficiency. It is. The method (4) using a gas-liquid contact device such as an ejector can easily improve the expected dissolving efficiency, but requires a power source such as a circulating pump and has a problem of increasing running costs. .

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a processing apparatus for continuously decomposing dissolved substances in a liquid to be treated by using a promoted oxidation method to decompose dissolved substances in the processing liquid with high efficiency. It is an object of the present invention to provide a continuous water treatment apparatus and method capable of easily separating and discharging a decomposed treatment liquid that can be produced.

[0007]

A continuous water treatment apparatus according to the present invention comprises a tank for storing a liquid to be treated, an ultraviolet lamp installed to irradiate the liquid to be treated with ultraviolet light, and a stirring means for stirring the photocatalyst particles. It is characterized by having a sedimentation / separation device installed to efficiently contact gas bubbles generated from the air diffuser and to separate photocatalytic particles.

[0008] An ozone gas is used as a gas for flowing a photocatalyst, the ozone gas is decomposed by ultraviolet irradiation, and a reaction of generated OH radicals is utilized. That is, an ultraviolet lamp having a wavelength of 189.4 nm is used. The flow of the liquid to be treated improves the establishment of contact with the ultraviolet lamp, and performs water treatment using high energy generated near the lamp. Further, there is provided a continuous water treatment apparatus characterized in that a decomposition product of a photocatalyst and a dissolved substance is continuously separated by a sedimentation separation tube.

As the photocatalyst, various metals, metal compounds, metal salts and the like, or a combination thereof are known. As the photocatalyst used in the present invention, hydrophobic, hydrophilic, titanium oxide, zinc oxide, cadmium sulfide,
Iron sulfide and the like are particularly preferable, and a titanium oxide compound is particularly preferable. As the particle size, a particle having a small particle size is preferably used in order to improve the establishment of contact with the liquid to be treated, and a particle having a size of 0.1 mm to 5 mm, preferably 0.2 mm to 1 mm is used. Further, it can be used by being supported on a carrier such as silica gel.

As the gas bubbles, any gas having an oxidizing power may be used, and oxygen and ozone, preferably, ozone gas are most suitable. Ozone gas is decomposed to generate radicals, which generally oxidize substances, and are widely used as oxidizing agents. The present invention further provides the ozone gas with ultraviolet irradiation,

[0009] The oxidizing power is further increased by reacting with the photocatalyst described in [0009].

The ultraviolet light is emitted using an ultraviolet irradiation device manufactured by Sen Special Light Source Co., Ltd., and the wavelength region is 184.9 nm.
Not less than 420.0 nm, preferably 184.9 nm
Not less than 254 nm. If it is above this range, the reaction with ozone and photocatalyst is slow, and if it is below this range, the speed of the oxidation reaction is almost the same level.

By combining photocatalyst, ozone and ultraviolet light, the dissolved substances in the solution to be treated and these photocatalysts,
The contact with ozone is more reliably made dense, and the oxidation treatment is more easily performed. That is, generation of radicals on the titanium oxide surface is further promoted.

Further, gas bubbles are ejected from a diffuser tube having fine holes, whereby the gas bubbles are evenly and uniformly diffused into the liquid to be treated. As a result, the photocatalyst and the dissolved substance come into contact with each other and ozone surely comes into contact, and the irradiation of ultraviolet rays becomes more efficient.

By agitating the liquid to be treated in the reaction vessel for performing these treatments with a stirrer, more efficient contact with the photocatalyst and gas bubbles is performed to perform the oxidation treatment.

The solution to be treated according to the present invention is one containing an organic solvent such as underground leachate. These underground leachates are discharged from factory premises and final disposal sites for waste. It also includes clean water, sewage / manure maintenance water, and the like. In particular, it is suitable for treating wastewater containing decomposed products of animals and plants contained in soil and the like.

The treatment liquid treated according to the present invention is decomposed by a photocatalyst, ultraviolet rays and ozone in a reaction tank.
In order to carry out this decomposition continuously, it is necessary to continuously decompose with a photocatalyst. Therefore, by installing a sedimentation separation tube in the reaction vessel, the photocatalyst always stays in the reaction tank and continuous treatment of the water to be treated is possible.

That is, a schematic view of the sedimentation separation tube is shown in FIG.
One end of the sedimentation tube is opened in the liquid to be treated in the reaction vessel shown in FIG. 1, and the other end has a discharge port outside the system by a pump through a discharge tube. The opening in the liquid to be treated preferably has a height at the lower end of the ultraviolet lamp in the reaction tank, and at least one portion of the flow path is bent. In this tube, the photocatalyst and the dissolved substance decomposed are separated due to a difference in specific gravity. The sedimentation / separation tube preferably has a shape that does not cause turbulence in the flow in the reaction tank, and is preferably a cylindrical shape in which the flow velocity at the entrance of the sedimentation / separation tube is equal to or less than the particle sedimentation velocity.

As shown in FIG. 2 (a), the opening is formed such that the pipe walls facing the opening are substantially parallel to each other, or as shown in FIG. 2 (b), turbulence and eddies are not easily generated near the opening. The trumpet shape can minimize the flow of the liquid to be treated.

As long as no decomposition products accumulate in the sedimentation / separation tube, the inner tube inner diameter may be gradually increased with respect to the inner diameter of the opening as shown in FIG. 2 (c).
In addition, as shown in FIG. 2D, a plurality of openings are provided in order to obtain a cross-sectional area necessary for a sedimentation separation tube as shown in FIG. And the like. In the present invention, (c) was preferable.

By using the sedimentation separation tube, the separated dissolved substance and the photocatalyst can be easily separated, and continuous operation can be performed without clogging which occurs at the time of separation by a conventional filter. As a result, the decomposition products in the liquid to be treated remain in the reaction tank, and only purified water is discharged out of the system.

The stirrer may be in the form of a stirring blade which forms a vertical circulating flow. It is preferable that the mounting position of the stirring blade is lower than the position of the opening of the sedimentation / separation tube because the influence of the flow of the liquid to be treated on the opening of the sedimentation / separation tube can be reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A continuous water treatment apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of the continuous water treatment apparatus of the present invention. The continuous water treatment apparatus of the present invention includes a reaction tank 1 for storing a treatment liquid, a treatment liquid supply pipe 2 for supplying a treatment liquid, a treatment liquid supply pump 3, and an ultraviolet lamp 4 installed in the reaction tank 1. , An ozone supply pipe 13 for supplying ozone, an ozone diffuser 6, a stirring blade 5 for stirring and mixing the photocatalyst and the liquid to be treated, and a sedimentation separation pipe 7 for separating photocatalyst particles.
And a processing liquid drain pipe 8 and a drain pump 9 for discharging the processing liquid.
An ozone exhaust pipe 10 for exhausting unreacted ozone to the outside of the system and an exhaust ozone treatment device 11 are provided.

Next, a method for decomposing dissolved substances in the processing solution will be described. The liquid to be treated is received in the reaction tank 1, gaseous ozone is supplied from below by the ozone diffuser 6, and the generated ozone bubbles and the photocatalyst particles introduced into the liquid to be treated by the stirrer 5 are dispersed and flown in the liquid to be treated. Let it. The photocatalyst particles flowing in the liquid to be treated absorb the light energy of the ultraviolet lamp 4 installed in the reaction tank to cause a photocatalytic reaction, and oxidatively decompose dissolved substances in the liquid to be treated by radicals generated by the photocatalytic reaction. I do. The treatment liquid after the oxidative decomposition is separated into the photocatalyst particles and the treatment liquid by the sedimentation separation tube 7, and only the treatment liquid is drained out of the system by the drain pump 9 via the drain pipe 8. The unreacted ozone supplied to the reaction tank is exhausted from the ozone exhaust pipe 10 to the outside of the system via the exhaust ozone device 11.

The gaseous ozone supplied in the present apparatus not only acts to flow the photocatalyst particles in the reaction tank 1 to improve the establishment of contact with the liquid to be treated, but also oxidatively decomposes due to hydroxyl radicals generated by the decomposition of ozone itself. generate. The rate of decomposition of the supplied ozone is accelerated by the light energy of the ultraviolet lamp 4 installed in the reaction tank 1, and the efficiency of oxidative decomposition is improved by increasing the generation rate of the hydroxyl radical.

Further, by agitating the liquid to be treated with the stirring blade 5 with ozone bubbles, the dissolved energy can be decomposed with high efficiency at a wavelength of 189.4 nm generated near the surface of the ultraviolet lamp 4 with high efficiency. Becomes possible.

The reaction tank used in the present apparatus is preferably made of a material that can withstand ozone and ultraviolet rays, and is preferably made of stainless steel. It is preferable to use a metal sintered filter or a ceramic filter as the material of the ozone diffuser, and it is preferable to use an opening having a diameter of about several tens of micrometers.

The stirring blade has a blade shape capable of forming a vertical circulating flow, and the rotation speed and the blade diameter are preferably selected under conditions where the number of stirring Reynold nozzles is in a turbulent region.
When it is 0 or more and 100000 or less, preferably 30,000 or more and 70,000 or less, stirring can be performed sufficiently efficiently, and the liquid level of the liquid to be treated is small. If the stirring speed is lower than this, the stirring efficiency is reduced. On the other hand, if the rotation speed is higher than this range, the liquid level greatly varies and the sedimentation separation tube is affected.

[0028]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to the following Examples.

In the apparatus configuration shown in FIG. 1, a liquid containing a humic substance (unnecessary black matter generated when the protein is decomposed) was stirred and oxidized at 25 ° C. for 15 minutes. As a photocatalyst, 3.5 g of titanium oxide by Ishihara Sangyo was added. The processing speed of extracting from the sedimentation separation tube was 300 cc / min. Chromaticity is JISK010
The measurement was performed according to the method of Example 1. The operating conditions are summarized below.・ Target liquid: Waste liquid containing humic substances ・ Reaction tank capacity: 3.5 L ・ Photocatalyst diameter: 0.5 mm ・ Ultraviolet lamp: 40 W ・ Ozone air volume: 2 L / min ・ Diffuser tube diameter: 40 μm / Min • Number of rotations of stirring blade: 400 rpm Table 1 shows part of the experimental results. The evaluation was based on chromaticity due to humic substance decomposition. As a comparative example, hydrogen peroxide and ultraviolet light alone were used instead of ozone. That is, a photocatalyst,
The ultraviolet irradiation was performed under the same conditions as in the example, and only ozone was used as a hydrogen peroxide solution. A spare port was attached to the ozone diffuser in FIG. 1 and hydrogen peroxide solution was supplied from here. Table 1 shows the results.

[0030]

[Table 1]

Table 1 From the above results, the decomposition of humic substances in this apparatus was confirmed by the change in chromaticity over time. That is, by using this processing apparatus, the chromaticity was smaller than that of the comparative example, and the transparency was confirmed.

[0032]

According to the continuous water treatment apparatus of the present invention,
Continuous water treatment using photocatalyst particles can be performed, and the dissolved substances contained in the liquid to be treated can be oxidatively decomposed with high efficiency. The present invention is very useful industrially.

[Brief description of the drawings]

FIG. 1 is an example of a flow diagram of a continuous water treatment apparatus of the present invention.

FIG. 2 is a schematic view showing a specific example of a sedimentation separation tube used in the continuous water treatment apparatus of the present invention.

[Explanation of symbols]

 1. Reaction tank 2. 2. Liquid supply pipe to be treated Liquid supply pump 4 UV lamp 5. Stirrer blade 6. Air diffuser 7. Settling separation tube 8. 8. Treatment liquid drain pipe Treatment liquid drainage pump 10. Ozone exhaust pipe 11. Exhaust ozone treatment device 12. Stirrer 13. Ozone supply pipe 31. Separation plate

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01F 3/04 B01F 3/04 B B01J 21/06 B01J 21/06 M 35/02 35/02 J C02F 1/00 C02F 1/00 G 1/32 1/32 1/52 1/52 Z 1/78 1/78 F term (reference) 4D037 AA11 AB02 AB11 BA18 CA06 CA12 4D050 AA12 AB13 BB01 BB02 BC04 BC09 BD02 CA20 4D062 BA29 BB01 CA01 CA20 EA32 4G035 AA01 AB10 4G069 AA15 BA04A BA04B BA48A CA05 CA10 DA05 EA02X EA02Y

Claims (8)

[Claims] In a system for decomposing dissolved substances in a liquid to be treated using gas bubbles, ultraviolet rays and a photocatalyst, a new liquid to be treated is continuously supplied to the system, and at the same time, the liquid to be treated is stirred. A continuous water treatment apparatus for discharging the treatment liquid, in which dissolved substances in the liquid to be treated have been decomposed, out of the system by a sedimentation tube. 2. The continuous water treatment apparatus according to claim 1,
A sedimentation separation tube that continuously separates the photocatalyst and the processing solution in which the dissolved substance in the liquid to be processed is decomposed is installed in the system, and the photocatalyst is brought into contact with gas bubbles while stirring the liquid to be processed. The tube forms a flow path through which the liquid to be treated passes while causing the photocatalyst to settle in the system, and the opening for introducing the liquid to be treated in the dissolved substance decomposed in the liquid to be treated is provided with the liquid to be treated. A continuous water treatment apparatus characterized in that it is directed downstream of a circulating flow by agitation and that at least one portion of the flow path is bent. 3. A reaction tank for storing a liquid to be treated, an ultraviolet lamp installed for irradiating the liquid to be treated with ultraviolet light, and high contact between gas bubbles generated from a diffuser by stirring the photocatalyst particles. A continuous water treatment device characterized by efficiency. 4. The continuous water treatment apparatus according to claim 1, wherein the photocatalyst is titanium dioxide. 5. The continuous water treatment apparatus according to claim 1, wherein the gas bubbles are ozone. 6. The continuous water treatment apparatus according to claim 1, wherein a photocatalyst, ultraviolet light, and ozone are combined. 7. The continuous water treatment apparatus according to claim 1, wherein the liquid to be treated is a waste liquid containing an organic substance. 8. A continuous water treatment method using the continuous water treatment apparatus according to claim 1.