JPH08197093A - Water treatment and device therefor - Google Patents

Abstract

PURPOSE: To suppress the generation of hydrogen peroxide and to effectively oxidize and decompose org. matter by adding the ozonized water obtained from an electrolytic ozonized water producing device to the water to be treated and adding the water passed through an anion-exchange resin or the hydroxide of an alkali metal to make the water alkaline. CONSTITUTION: The ozonized water of an electrolytic ozonized water producing device is added to the water to be treated from an ozonized water inlet 5 directly before a UV irradiation device 8. In this case, the water is regulated to pH 8-9 on this side of the inlet 5 by the water passed through an anion-exchange resin or the aq. alkali metal hydroxide soln. adding device 7. The org. matter in the water is then allowed to react with ozone by UV of the irradiation device 8 and decomposed into org. acid or carbonic acid. The water contg. H<+> ion and H free radical is added from a water inlet 6 of the electrode counter to an ozone generating electrode to return the water to neutral. The org. acid, carbonic acid, excess OH<-> ion and H<+> ion are removed in a mixed-bed ion- exchange resin tower 9. The by-produced hydrogen peroxide is removed in the water without using an activated-carbon treatment or a pH regulating chemical.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to organic matter (TOC) in water.
The present invention relates to a water treatment method and apparatus for removing water, and in particular, in order to produce pure water or ultrapure water, the water to be treated is irradiated with ultraviolet rays to decompose dissolved organic matters, and this treated water is treated with an ion exchange resin tower. In the method of treating to remove organic acids and carbonic acid which are decomposition products, ozone water is added to the water to be treated prior to irradiation of ultraviolet rays to enhance the decomposition efficiency, and the water to be treated is treated under alkaline conditions before the addition of the ozone water. The present invention relates to a water treatment method and apparatus for controlling the reaction between ozone and an organic acid to remove hydrogen peroxide by-produced by ultraviolet irradiation.

[0002]

2. Description of the Related Art A large amount of pure water or ultrapure water is used in the cleaning process of a semiconductor manufacturing plant.
The problem of removing organic matter dissolved in pure water or ultrapure water has been widely taken up.

That is, since city water or well water generally used as raw water for pure water or ultrapure water often contains organic substances derived from spoiled animals and plants or microorganisms, pure water or ultrapure water is used. In the manufacturing process of, it is necessary to remove these organic substances. Further, in a cleaning process in a semiconductor process, an organic cleaning agent such as isopropyl alcohol is mixed into cleaning wastewater, but when recycling a large amount of cleaning wastewater, it is necessary to remove organic substances in the wastewater. .

Conventionally, as a method for producing pure water / ultra pure water from city water, well water or washing wastewater, a combined treatment of coagulation filtration, reverse osmosis membrane treatment, ion exchange treatment, ultrafiltration membrane treatment, etc. has been used. However, it is difficult to completely remove organic substances by these methods.

In recent years, in order to reduce the concentration of a small amount of organic matter remaining in the water to be treated, the water to be treated is irradiated with ultraviolet rays to oxidize and decompose the organic matter in the water into an organic acid or carbonic acid, which is produced by oxidative decomposition. A method of removing an organic acid or carbonic acid by an ion exchange resin tower installed in a subsequent stage has come to be used. However, with this method,
There is a problem that a large amount of power consumption is required to completely decompose the organic matter only by irradiating with ultraviolet rays, which results in a high processing cost.

As a method for solving this problem, a method has been proposed in which ozone is added to the water to be treated and the water to be treated after the ozone addition is irradiated with ultraviolet rays to efficiently oxidize and decompose organic substances in the water to be treated. . According to this method, the photoreaction of ozone and water is performed to generate .OH radicals having a strong oxidizing power, and the oxidative decomposition of organic substances is effectively performed.

However, in this method, hydrogen peroxide is generated by the reaction between ozone and water, which causes oxidative deterioration of the ion-exchange resin installed in the subsequent stage, or corrodes the pipe, which causes new problems. There is.

Conventionally, in order to remove such hydrogen peroxide, a method has been used in which an activated carbon tower is installed in the latter stage to catalytically decompose hydrogen peroxide. In this method, microorganisms are generated in the activated carbon tower. There has been a problem that a part of the organic substances that grow and are produced by the microorganisms are adsorbed on the activated carbon and redissolved, which greatly affects the water quality. Also, when microorganisms grow in the activated carbon tower, the ion exchange resin tower in the latter stage is also affected and the water permeability decreases, but in such a state, the ion exchange tower requires maintenance such as decomposition and cleaning. There was also a problem that the operating cost increased and the management became complicated.

[0009]

As described above, in the system for producing pure water or ultrapure water, in order to reduce the concentration of a small amount of organic substances remaining in the water to be treated, it is decomposed and produced by ultraviolet irradiation and an ion exchange resin tower. In the method of removing the substances, there is a problem that a large amount of power consumption is required and the treatment cost is high, and the method of efficiently oxidizing and decomposing the organic substances by adding ozone into the water to be treated and irradiating with ultraviolet rays. Then, there is a problem that hydrogen peroxide is generated by the reaction of ozone and water, and this hydrogen peroxide causes the oxidative deterioration of the ion exchange resin and the corrosion of the pipes. In the method of catalytically decomposing the generated hydrogen peroxide, microorganisms grow in the activated carbon tower and some of the organic substances caused by the microorganisms are adsorbed on the activated carbon and redissolved. Reduce the water permeability of-exchange resin column, operating costs are required maintenance such as brush cleaning there is a problem in that it becomes complicated administrative increases.

The present invention has been made to solve the above conventional problems, does not require a large amount of power consumption, and
Hydrogen peroxide generated as a by-product of UV irradiation can be removed without using an activated carbon tower. Therefore, there is no problem of microbial growth in the activated carbon tower or re-elution of organic matter, and water treatment with low operating costs. It is an object to provide a method and a water treatment device.

[0011]

The water treatment method of the present invention comprises:
A step of adding ozone water generated by an electrolytic ozone water producing apparatus to the water to be treated, a step of adjusting the water to be treated to an alkaline condition, and the ozone water being added and adjusted to an alkaline condition A step of irradiating the water to be treated with ultraviolet rays to decompose organic substances, and adding water containing H ⁺ ions or H radicals generated in the electrolytic ozone water producing apparatus to the water to be treated in which the organic substances have been decomposed And a step of treating water to be treated to which water containing H ⁺ ions or H radicals is added in an ion exchange resin tower, and the water treatment apparatus of the present invention comprises:
Means for adjusting the treated water to alkaline conditions, an ultraviolet irradiation device for irradiating the treated water adjusted to alkaline conditions with ultraviolet rays for decomposing organic substances, and an ion exchange resin tower using the treated water by the ultraviolet irradiation device as inlet water And an electrolytic ozone water producing apparatus for supplying ozone water to the inlet water of the ultraviolet irradiation apparatus and supplying water containing H ⁺ ions or H radicals to the inlet water of the ion exchange resin tower. It has a feature.

In the present invention, in order to adjust the water to be treated to alkaline conditions, for example, at least a part of the water to be treated is passed through an anion ion exchange resin, or the hydroxide of an alkali metal is added to the water to be treated. It may be added. In addition,
The anion type ion exchange resin should be as low as possible in the impurity level, and the alkali metal hydroxide should be of the grade for the electronics industry or a grade equivalent thereto. The inlet for the water passing through the anion-based ion exchange resin or the hydroxide of the alkali metal is provided immediately before the ultraviolet irradiation device, in the main body of the ultraviolet irradiation device, or in the middle between the front side and the rear side of the two-part ultraviolet irradiation device. As alkaline conditions, pH of about 8 to 9 is suitable.

The ultraviolet irradiation device in the present invention is as follows:
A low or medium pressure mercury lamp is used, and it is preferable that the inside of the chamber is lined with a resin having chemical resistance or stainless steel is used. Examples of the material of the resin lining include fluorine-based resins such as PFA having strong chemical resistance, and stainless steel is more preferably subjected to chemical resistance / corrosion resistance treatment such as electrolytic polishing or complex electrolytic polishing.

In the present invention, an anion-type or anion-cation-type ion-exchange resin column is used as the ion-exchange resin column installed after the ultraviolet irradiation device. The ion exchange resin packed in the ion exchange resin tower is
It is preferable that it is new or that does not have crushing similar to it,
It is more preferable that the ion exchange resin itself has high performance and little elution.

[0015]

In the present invention, in order to decompose the organic matter in the water to be treated into organic acid or carbonic acid, the ozone water produced by the electrolytic ozone water producing apparatus is added to the water to be treated, and the anionic ion exchange resin The water to be treated is adjusted to an alkaline condition of about pH 8-9 by adding passing water or an alkali metal hydroxide.

After that, ultraviolet rays are irradiated to decompose organic substances into organic acids or carbonic acids.

H generated in the outlet water of the ultraviolet irradiation device on the opposite side of the ozone generating electrode in the electrolytic ozone water producing device.
By supplying water containing ⁺ ions or H radicals, hydrogen peroxide generated as a by-product when ozone water is added is removed, and the liquid property of the water to be treated is returned to around the neutral region.

Furthermore, the excess organic acid of the for-treatment water by the ion exchange resin column disposed downstream OH ^-
Ions and H ⁺ ions are removed.

[0019]

EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

FIG. 1 is a schematic view of electrodes of an electrolytic ozone water producing apparatus used in the present invention.

[0021] Each ozone generated by electrolysis H ⁺ ions, the anode 1 side is ozone water cathode 4 side separated as H ⁺ ionized water. The separated ozone water and H ⁺ ion water are introduced into the water treatment device.

2 to 4 are flow charts of the respective water treatment devices.

Embodiment 1 FIG. 2 shows a flow chart 1 of a water treatment device. The ozone water generated by the electrolytic ozone water producing apparatus is added to the water to be treated just before the ultraviolet irradiation device 8, and the treated water to which the ozone water is added is subsequently introduced into the ultraviolet irradiation device 8. At that time, the liquid property is controlled to about pH 8-9 by the anion-based ion exchange resin passing water or the alkali metal hydroxide aqueous solution addition device 7 before the ozone water inlet 5.

Next, the organic matter in the water to be treated is reacted with ozone by photoexcitation by ultraviolet rays, and the organic matter is decomposed into organic acid or carbonic acid. However, since hydrogen peroxide is simultaneously generated at this time, H ⁺ ions generated on the counter electrode side of the ozone generating electrode in the electrolytic ozone water producing apparatus and
Water containing H radicals is added from the ozone generating electrode counter electrode water inlet 6 to decompose hydrogen peroxide and return the liquidity on the alkaline side to the neutral region.

Finally, the water to be treated is introduced into the anion type ion exchange resin column or the mixed bed type ion exchange resin column 9 to remove the organic acid and carbonic acid and excess OH ⁻ ions and · H ⁺ ions.

Example 2 FIG. 3 shows a flow chart 2 of the water treatment apparatus of Example 2.
The same devices as those in FIG. 2 are designated by the same reference numerals as those in FIG.

The anion type ion exchange resin passing water or the alkali metal hydroxide aqueous solution is added to the main body of the ultraviolet irradiation device 8 by the anion type ion exchange resin passing water or the alkali metal hydroxide aqueous solution adding device 7 to make the liquid property. pH
Control to about 8-9.

Example 3 FIG. 4 shows a flow chart of the water treatment device of Example 3. The same devices as those in FIG. 2 are designated by the same reference numerals as those in FIG.

The ultraviolet irradiation device 8 is divided into two stages, and the position of the introduction port from the anion-type ion exchange resin passing water or the alkali metal hydroxide aqueous solution addition device 7 is located between the front ultraviolet irradiation device 8a and the rear ultraviolet irradiation device 8b. The pH is controlled to about 8 to 9 by adding water passing through the anion-based ion exchange resin or aqueous alkali metal hydroxide solution.

The front-stage ultraviolet irradiation device 8a decomposes organic substances only by ultraviolet irradiation, and the rear-stage ultraviolet irradiation device 8b decomposes organic substances by ozone by photoexcitation of ultraviolet irradiation.

[0031]

EFFECTS OF THE INVENTION According to the present invention, it is generated as a by-product in the removal of dissolved organic substances for reuse of cleaning waste water of pure water / ultra pure water used in large quantities in the cleaning process of semiconductor manufacturing plants. The hydrogen peroxide can be removed without using an activated carbon tower or chemicals for pH control, and complicated management during normal equipment operation becomes unnecessary. It is now possible to efficiently and effectively use the water on the counter electrode side of the ozone generation electrode in the electrolytic ozone production equipment that was conventionally drained, chemical injection, activated carbon exchange, activated carbon tower maintenance, ion exchange from activated carbon. Since the load on the resin tower is eliminated, the initial and running costs can be reduced.

[Brief description of drawings]

FIG. 1 Schematic diagram of electrodes for electrolytic ozone production equipment

FIG. 2 Flow chart of water treatment device 1

FIG. 3 Flow chart of water treatment device 2

FIG. 4 Flow chart of water treatment device 3

[Explanation of symbols]

1 Anode 2 A diaphragm 3 Solid electrolyte 4 A cathode 5 Ozone water inlet 6 An ozone generating electrode counter electrode inlet 7 Anion ion exchange resin water or Alkali metal hydroxide aqueous solution addition device 8 ………… Ultraviolet irradiation device 8a ………… Previous stage ultraviolet irradiation device 8b ………… Post stage ultraviolet irradiation device 9 ………… Anion ion exchange resin tower or mixed bed type ion exchange resin tower

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C02F 9/00 504 BE 1/32 1/42 B 1/46 Z 1/78

Claims (5)

[Claims] 1. A step of adding ozone water generated by an electrolytic ozone water producing apparatus to the water to be treated, a step of adjusting the water to be treated to an alkaline condition, and the ozone water being added, and an alkali The step of irradiating the treated water adjusted to the conditions with ultraviolet rays to decompose the organic matter, and the treated water in which the organic matter is decomposed are treated with H ⁺ ions or H radicals generated in the electrolytic ozone water producing apparatus. A water treatment method comprising: a step of adding contained water; and a step of treating water to be treated to which water containing H ⁺ ions or · H radicals is added in an ion exchange resin tower. 2. The step of adjusting to alkaline conditions is a step of passing at least a part of the water to be treated through an anion ion exchange resin or a step of adding a hydroxide of an alkali metal. The water treatment method according to claim 1. 3. A means for adjusting treated water to an alkaline condition, an ultraviolet irradiation device for irradiating the treated water adjusted to an alkaline condition with ultraviolet rays for decomposing organic substances, and the treated water by the ultraviolet irradiation device to the inlet water. And an ion exchange resin tower to supply ozone water to the inlet water of the ultraviolet irradiation device and to supply water containing H ⁺ ions or H radicals to the inlet water of the ion exchange resin tower. And a water treatment device. 4. The water treatment apparatus according to claim 3, wherein the ion exchange resin tower is an anion exchange resin tower or an anion / cation exchange resin mixed bed tower. 5. The water treatment method according to claim 1 or the water treatment device according to claim 3, wherein the alkaline condition is pH 8-9.