JPH11333443A - Recycling method for rinse wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycling method for rinse wastewater whereby rinse wastewater contg. a high-boiling component is recovered from the step of wafer cleaning in a semiconductor production factory and is sent to a distillation-type pure water production apparatus to be used as feed water for the pure water production by distillation. SOLUTION: A pure water production/waste water recycling system for glass substrates or liq. crystals in a liq. crystal production process is provided. Pure water used at a use point 4 is recovered separately according to chemicals used. Rinse wastewater contg. TMAH is adjusted to a neutral pH at a pH- adjusting vessel 5 and then is recovered into a raw water vessel 1 or the wastewater is directly recovered into a raw water vessel 1 and then is adjusted to a desired pH (weakyl acidic, i.e., a pH of 4.2-6.5) at the upstream side of a vacuum deaerator 2, a pretreatment apparatus. A pure water production apparatus 3 used is a distillation apparatus. The concentrating ratio of the pure water production apparatus, though determined by the properties of feed water, is set at 4-5, and the blowdown is joined with other waste water and, if necessary, is subjected to a wastewater treatment to a degree suitable for discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering pure water used in the electronics industry such as the semiconductor industry, and more particularly, to rinse water containing high-boiling components generated in a wafer cleaning process in a semiconductor manufacturing plant. Rinsing wastewater collected from the same process, sent to a distillation pure water production apparatus, and reused as supply water for the distillation pure water production.

[0002]

2. Description of the Related Art Conventionally, TMAH rinsing wastewater and organic rinsing wastewater have not been recovered as feed water for a pure water production system, and organic rinsing wastewater is a wastewater for pH adjustment, biological treatment, coagulation sedimentation and the like. It has been treated and released.

[0003]

In recent years, due to the growing interest in environmental issues, it has been studied to recover and reuse rinse water used in ultra-pure water even in a semiconductor manufacturing process using a large amount of ultra-pure water. Have been.

[0004] Inorganic rinse wastewater is recovered through activated carbon filtration and ion exchange equipment.

[0005] Attempts have been made to recover organic rinsing wastewater by performing a treatment combining ultraviolet oxidation, biological treatment and membrane separation, and collecting the wastewater.

However, since the conventional ultrapure water production process mainly comprises a system combining ion exchange technology and membrane separation technology, when bacteria or organic substances serving as bait for bacteria enter the system, ion exchange resin or Bacterial slime may be generated on the membrane, which may cause troubles such as blockage of the flow path. For this reason, at present, organic rinse wastewater is not recovered as supply water for pure water production.

According to the present invention, a rinsing wastewater containing a high boiling point component is recovered from a wafer cleaning process in a semiconductor manufacturing plant, sent to a distillation pure water production apparatus, and reused as supply water for the distillation pure water production. It aims to provide a wastewater recycling law.

[0008]

SUMMARY OF THE INVENTION A method of recycling rinse water according to the present invention is a method of recovering rinse water containing a substance having a boiling point higher than the distillation temperature of water and reusing it as feed water in a distillation pure water production method. It is.

The above substances are, for example, tetramethyl ammonium hydroxide (hereinafter referred to as TM).
AH, decomposed at 130 ° C.), N-methyl-2-
Pyrrolidone (boiling point 204 ° C.).

After the pH of the above rinse water is adjusted, it is preferable to recover the rinse water and reuse it as feed water for the distillation pure water production method.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A distillation pure water production apparatus evaporates supply water under reduced pressure, removes mist accompanying the generated steam, obtains pure steam, condenses the pure steam, and converts the pure water to pure water. What you get.

Accordingly, substances having a boiling point higher than the evaporation temperature of water do not evaporate and are not included in the pure water side. Conversely, a substance having a boiling point lower than the evaporation temperature of water evaporates with water and is included in the pure water side.

[0013] Even if the feed water contains organic matter and bacteria, the feed water is heated to about 90 ° C in the first effect step of the distillation pure water production apparatus, so that the heat-sterilized bacteria die, No trouble caused by bacteria occurs in the pure water production equipment.

[0014] Based on this, if a simple distillation test is performed to confirm that the target substance does not enter the distillate side, rinse water containing the substance is recovered and reused as raw water for the distillation pure water production method. Can be used.

Next, the results of a distillation test of 50 ppm of TMAH are shown.

[0016]

[Table 1] From these results, it was confirmed that even when the dilute TMAH solution (54 ppm) was distilled, neither the TOC component nor the unmore component was contained on the distillate side.

Since the apparatus for producing pure water by the distillation method has a mist separator, the mist separation effect is better than that of a distillation tester.

The above test was conducted to determine the pH of the TMAH rinse wastewater.
However, TMAH is more difficult to volatilize if the pH of the rinsing wastewater is adjusted and the wastewater is reused as feed water on the neutral or weakly acidic side.

From the above, the TMAH rinse drainage is p
It can be seen that the water can be recovered as feed water for the distillation pure water production apparatus only by performing H adjustment.

The organic alkali having a high boiling point is also TMA.
H can be recovered.

Embodiment 1 FIG. 1 shows a pure water production / drainage recovery system for a glass substrate, a liquid crystal and the like in a liquid crystal production process.

The pure water used at the use point (4) is
Collected separately for each chemical system used. Rinse wastewater containing TMAH (eg, TMAH concentration of 54 ppm and pH 9.7)
Is adjusted to neutral pH in the pH adjusting tank (5) and the raw water tank (1)
Or a predetermined pH (weakly acidic pH 4.2-
Adjusted to 6.5).

The pure water producing apparatus (3) is an apparatus of a distillation method.
The concentration ratio of the pure water production equipment (3) is determined by the properties of the feed water, but the concentration ratio should be in the range of 4 to 5 times. Blowdown should be combined with other wastewater, and if necessary, wastewater treatment until suitable for discharge. And discharge.

Embodiment 2 FIG. 2 shows an ultrapure water production / drainage recovery system in a semiconductor production process.

The ultrapure water used at the use point (4) is separated and collected for each chemical system used.

Rinse drainage containing TMAH (eg, TMA
The H concentration of 54 ppm and pH of 9.7) is adjusted to neutral pH in the pH adjusting tank (5) and collected in the raw water tank (1), or collected directly in the raw water tank (1) and vacuum degassed for pretreatment. It is adjusted to a predetermined pH (weakly acidic pH 4.2 to 6.5) upstream of the vessel (2).

The primary pure water-based pure water producing apparatus is an apparatus of a distillation method. The concentration ratio of the pure water production equipment (3) is determined by the properties of the feed water, but the concentration ratio should be in the range of 4 to 5 times. Blowdown should be combined with other wastewater, and if necessary, wastewater treatment until suitable for discharge. And discharge.

The subsystem is the same as that of the conventional method. That is, the subsystem sets the TOC component to 1 ppb
The apparatus comprises an ultraviolet oxidation device (6), a cartridge polisher (7) for removing trace metal ions, and an ultrafiltration device (8) for removing fine particles. The cartridge polisher (7) contains a non-regenerated ion exchange resin.

[0029]

According to the method of the present invention, rinse water containing high-boiling components is recovered from a wafer cleaning step in a semiconductor manufacturing plant and sent to a distillation-method pure water producing apparatus to supply water for distillation-method pure water production. As can be reused.

Accordingly, it is possible to reduce the amount of industrial water and city water used as raw water, thereby achieving a reduction in pure water production cost.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a pure water production / drainage recovery system for a glass substrate, a liquid crystal and the like in a liquid crystal production process.

FIG. 2 is a flow sheet showing an ultrapure water production / drainage recovery system in a semiconductor production process.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Yoshida 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi Inside Tachibana Shipbuilding Co., Ltd. (72) Inventor Shiro Inoue 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi No.Tachi Shipbuilding Co., Ltd.

Claims (3)

[Claims] 1. A method of recycling rinsing wastewater in which rinsing wastewater containing a substance having a boiling point higher than the distillation temperature of water is collected and reused as feed water in a distillation pure water production method. 2. The method according to claim 1, wherein said substance is tetramethylammonium hydroxide or N-methyl-2-pyrrolidone. 3. The recycling method according to claim 1, wherein after the pH of the rinse wastewater is adjusted, the rinse wastewater is recovered and reused as feed water in a distillation pure water production method.