KR20090127131A - Method and apparatus for removing organic matters - Google Patents

Abstract

A method and an apparatus for removing organic matters from water which can be appropriately used in recovering and reusing organic matter-containing water, for example, waste rinsing water discharged from a process for manufacturing electronic devices. After adding a sulfur compound having a peroxide group and, if necessary, a pH-controlling agent, discharged water containing organic matters is subjected to ultraviolet oxidization. After controlling the pH value of the water having been subjected to the ultraviolet oxidization if necessary, the oxidizing agent remaining therein is removed and the water, from which the oxidizing agent has been removed, is deionized. By adding the sulfur compound having a peroxide group to the untreated water followed by ultraviolet oxidization, sulfate radical having a very strong oxidizing power is generated. By this sulfate radical, the organic matters contained in the untreated water are morphologically converted into ionic organic matters which are then removed by the deionization.

Description

METHOD AND APPARATUS FOR REMOVING ORGANIC MATTERS}

The present invention relates to a method and apparatus for removing organic matters in water which can be suitably used for recovery and reuse of TOC-containing wastewater discharged from an electronic device manufacturing plant.

BACKGROUND ART In the electronic device manufacturing process, a large amount of ultrapure water is used for cleaning substrates and the like, and recovery and reuse of rinse drainage has been widely performed in view of reducing environmental load, effective utilization of water resources, and the like. However, since the rinse drain contains organic substances such as alcohol and surfactant, these organic substances must be removed to reuse the rinse drain.

As a conventional technique for removing organic matter in water, biological treatment, ozone treatment, reverse osmosis membrane separation treatment, and the like are known.

The biological treatment requires a long time for the organic substance decomposition reaction, and requires a large installation space (reactor). In addition, when the rinse drainage discharged from the process contains a surfactant, the surfactant is not sufficiently decomposed by biological treatment.

In the ozone treatment, the TOC component is oxidized by combining ozone with hydrogen peroxide, ozone with ultraviolet light, ozone with alkali, and the like (for example, Japanese Patent Application Laid-Open No. 2000-279973, Japanese Patent Application Laid-Open No. 10-85770, Japan). Japanese Patent Application Laid-Open No. 9-253695.

Ozone generates hydroxyl radicals having a very strong oxidizing power, and organic substances are decomposed by the strong oxidizing power. Since ozone and hydrogen peroxide decompose after treatment to become oxygen or hydrogen, secondary waste is not produced.

However, the ozone treatment method has a slow rate of decomposition of organic substances such as urea, tetramethylammonium hydroxide, and dimethyl sulfoxide (DMSO), which contain nitrogen or sulfur as organic constituents.

The reverse osmosis membrane separation treatment can efficiently remove impurities (ions, organics, fine particles, etc.) in water.

However, when the TOC concentration in raw water is high, microorganisms propagate in the reverse osmosis membrane separation apparatus, and the membrane pressure increases. When raw water contains surfactant, surfactant adheres to the membrane surface of a reverse osmosis membrane, and the permeation flux of a reverse osmosis membrane is reduced.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-279973

Patent Document 2: Japanese Patent Application Laid-Open No. 10-85770

Patent Document 3: Japanese Patent Application Laid-Open No. 9-253695

An object of the present invention is to provide a method and apparatus for removing organic matter in water, which can be suitably used for treatment of rinse drainage and the like discharged from an electronic device manufacturing process.

The organic matter removal method of the first aspect of the present invention includes a drug addition step of adding a sulfur compound containing a peroxide group to organic matter-containing wastewater, an ultraviolet oxidation step of irradiating ultraviolet light to the treated water of the drug addition step; And an oxidant removal step of removing the oxidant in the treated water of the ultraviolet oxidation step, and a deionization step of deionizing the treated water of the oxidant removal step.

In the 1st aspect, the organic substance removal method of a 2nd aspect WHEREIN: The addition amount of the said sulfur compound in the said chemical | medical agent addition process is 10-200 weight times with respect to the TOC density | concentration of the said organic substance containing wastewater, It is characterized by the above-mentioned.

The organic matter removing method of the third aspect is characterized in that, in the first or second aspect, the ultraviolet irradiation amount in the ultraviolet oxidation step is 0.05 kwh / m 3 or more per unit of water to be treated.

In the organic matter removal method of a 4th aspect, pH of the water which flows into the said ultraviolet oxidation process in 1st-3rd aspect is 4-10, It is characterized by the above-mentioned.

In the organic matter removal method of a 5th aspect, in 1st-4th aspect, dissolved oxygen (DO) density | concentration in the water flows into the water which flows into the said ultraviolet oxidation process, and DO is compared with the total organic carbon (TOC) concentration of the water. And an oxygen dissolution step of dissolving oxygen such that / TOC? 3 (weight ratio).

In the 1st-5th aspect, the organic substance removal method of 6th aspect WHEREIN: pH of the water which flows into the said oxidizing agent removal process is characterized by five or more.

The organic matter removal method of a 7th aspect WHEREIN: The degassing process of degassing the process water of the said oxidizer removal process in any one of 1st-6th aspect, The process water of this degassing process is supplied to the said deionization process. It is characterized by.

The organic matter removing apparatus of the eighth aspect includes drug addition means for adding a sulfur compound containing a peroxide group to organic matter-containing waste water, ultraviolet ray oxidation means for irradiating ultraviolet light to the treated water of the drug addition means, and the ultraviolet oxidation means Oxidant removing means for removing the oxidant in the treated water and deionizing means for deionizing the treated water of the oxidant removing means.

In the 8th aspect, the organic matter removal apparatus of 9th aspect WHEREIN: The addition amount of the said sulfur compound in the said chemical | medical agent addition means is 10-200 weight times with respect to the TOC density | concentration of the said organic substance containing wastewater.

In the eighth or ninth aspect, the organic matter removing device of the tenth aspect is characterized in that the ultraviolet irradiation amount in the ultraviolet oxidation means is 0.05 kwh / m 3 or more per unit of water to be treated.

In the organic matter removing apparatus of the eleventh aspect, in the eighth to tenth aspect, the pH of the water flowing into the ultraviolet oxidation means is 4 to 10.

The organic matter removing apparatus of the twelfth aspect is the ratio of the dissolved oxygen (DO) concentration in the water and the total organic carbon (TOC) concentration of the water to the water flowing into the ultraviolet oxidation means according to the eighth to eleventh aspects. (Weight ratio) It is characterized by including the oxygen dissolving means which dissolves oxygen so that DO / TOC may be three or more.

In the organic matter removing apparatus of the thirteenth aspect, in the eighth to twelfth aspect, the pH of the water flowing into the oxidant removing means is 5 or more.

The organic matter removing apparatus of the fourteenth aspect includes the degassing means for degassing the treated water of the oxidant removing means in any one of the eighth to thirteenth aspects, wherein the treated water of the degassing means is supplied to the deionizing means. It is characterized by.

According to the present invention, various organic substances such as compounds containing nitrogen and sulfur, such as alcohols and surfactants, and urea, tetramethylammonium hydroxide and dimethyl sulfoxide, which are discharged from organic matter-containing waste water, in particular, from an electronic device manufacturing plant, etc. The organic matter in the high concentration TOC to low concentration TOC containing wastewater contained can be removed efficiently, and the treated water of very high purity can be obtained.

Therefore, this invention can be used suitably for collection | recovery reuse, etc. of organic substance containing wastewater, such as the rinse wastewater discharged | emitted in an electronic device manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS It is a graph which shows the relationship between pH of the water supply of a ultraviolet oxidation device, and TOC removal rate in Example 1. FIG.

FIG. 2 is a graph showing a relationship between Na ₂ S ₂ O ₈ / TOC (weight ratio) and TOC removal rate of water supply of an ultraviolet oxidation device in Example 2. FIG.

3 is a graph showing the relationship between DO / TOC (weight ratio) and TOC removal rate of water supply of the ultraviolet oxidation device in Example 3. FIG.

FIG. 4 is a graph showing the relationship between the ultraviolet irradiation amount and the TOC removal rate in the ultraviolet oxidation device in Example 4. FIG.

EMBODIMENT OF THE INVENTION Below, embodiment of the organic substance removal method and apparatus of this invention is described in detail.

The present invention is effective for treating various organic matter-containing wastewater, but is particularly suitable for the treatment of organic matter-containing wastewater discharged from an electronic device manufacturing plant. The wastewater from the electronic device manufacturing plant contains at least one of a surfactant, a nitrogen-containing compound and a sulfur-containing compound. Examples of the nitrogen-containing compound and the sulfur-containing compound include urea, tetramethylammonium hydroxide, dimethyl sulfoxide and the like.

When a suspended substance exists in raw water, it is preferable to remove this suspension substance beforehand, and to provide it to the process of this invention. As the means for removing the suspended matter, raw material is agglomerated and solid-liquid separated to remove suspended substances contained in the raw water, such as pressure filtration, gravity filtration, microfiltration, ultrafiltration, pressure flotation, precipitation, and the like. Do.

In the present invention, a sulfur compound containing a peroxide group is first added to raw water (organic-containing wastewater), and a pH adjuster is added as necessary to adjust the pH to pH 4 to 10, and the water is passed through an ultraviolet oxidation device (通 水).

By adding a sulfur compound containing a peroxide group to raw water and performing an ultraviolet oxidation treatment, sulfuric acid radicals having very high oxidizing power are generated. This sulfuric acid radical changes the organic substance present in raw water into an ionic organic substance. Since sulfuric acid radicals have a very high rate of decomposing organic matters compared to hydroxyl radicals generated only by ultraviolet oxidation treatment or ozone treatment, organic matters decompose very efficiently by a small amount of ultraviolet irradiation.

As a sulfur compound containing the peroxide group added to raw water, a peroxy sodium sulfate salt, a peroxy ammonium sulfate salt, a peroxy potassium sulfate, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

It is preferable that the sulfur compound containing a peroxide group is added 10 to 200 weight times, especially 10 to 50 weight times with respect to TOC density | concentration of raw water. When the addition amount of the sulfur compound containing a peroxide group is too small, generation | occurrence | production of a sulfuric acid radical will not be enough and TOC removal rate will fall extremely. Even if the addition amount of the sulfur compound containing a peroxide group is excessively large, TOC removal rate does not improve very much.

The pH of the water flowing into the ultraviolet oxidation device is preferably 4 to 10. Water below pH 4 may corrode the ultraviolet oxidation device. On the other hand, when the pH of this water exceeds 10, the reaction efficiency in organic matter decomposition will fall by self-decomposition of the sulfur compound containing a peroxide group. Therefore, alkali water, such as sodium hydroxide, acids, such as a sulfuric acid and hydrochloric acid, are added to raw water as needed, Preferably pH adjusts to 4-10, More preferably, 4-8.

A pH adjuster may be added before adding the sulfur compound containing a peroxide group to raw water, may be added after adding the sulfur compound containing a peroxide group, and may be added together with the sulfur compound containing a peroxide group.

It is preferable that the ultraviolet irradiation amount in an ultraviolet oxidation apparatus is 0.05 kwh / m <3> or more with respect to the quantity which flows into an ultraviolet oxidation apparatus. When the amount of ultraviolet irradiation is less than 0.05 kwh / m 3, the generation of hydroxy radicals that become groups for generating sulfuric acid radicals is insufficient, so that the TOC removal rate is lowered. However, even if the amount of ultraviolet irradiation is excessively large, the TOC removal rate reaches a limit, so the amount of ultraviolet radiation is preferably 0.05 to 2 kwh / m 3.

When the ratio (weight ratio) DO / TOC of the dissolved oxygen (DO) concentration of water flowing into the ultraviolet oxidation unit and the TOC concentration of the raw water is less than 3, the decomposition efficiency of organic matter in the ultraviolet oxidation unit is lowered. For this reason, in response to the quality of raw water, an oxygen dissolving means is provided as necessary to dissolve oxygen in the raw water so that the DO / TOC (weight ratio) of water flowing into the ultraviolet oxidation device is three or more, and then the ultraviolet oxidation device. It is preferable to pass water into.

Examples of the oxygen dissolving means include a membrane dissolution method and an aeration method. Even if the DO / TOC of the water supply of the ultraviolet oxidation device is excessively high, the TOC removal rate does not improve so much, so the DO / TOC (weight ratio) of the water supply of the ultraviolet oxidation device is about 3-5.

Subsequently, the treated water of the ultraviolet oxidation device is deionized after removing the residual oxidizing agent, that is, a sulfur compound containing peroxide groups not used for decomposition of organic matter. If water containing the peroxide sulfur-based oxidant which is not used for organic matter decomposition is passed through the deionizer as it is, there is a risk of oxidative deterioration of the ion exchange resin, ion exchange membrane or the like of the deionizer. Therefore, the ultraviolet oxidation treated water removes the oxidant prior to the deionization treatment.

As this oxidizing agent removal method, addition of reducing agents, such as sodium bisulfite, installation of an activated carbon tower, installation of a catalyst tower carrying palladium, platinum, etc. can be utilized. Here, since the remaining oxidizing agent is stable under acidic conditions, it is preferable from the viewpoint of the reduction efficiency to adjust the pH to 5 or more before performing the reduction treatment. Therefore, the pH oxidation treatment water is added to the ultraviolet oxidation treatment water as necessary, and the pH is adjusted to pH 5 or higher, preferably pH 5 to 8, and then used for the oxidizing agent removal treatment.

Subsequently, the oxidant removal treatment water is deionized to remove ionic organic substances generated by the oxidation treatment. As a deionization means which removes this ionic organic substance, a reverse osmosis membrane separation apparatus, an ion exchange apparatus, an electrical regenerative deionization apparatus, etc. are mentioned, A combination of two or more of these may be sufficient.

The treated water from which the oxidant has been removed contains carbon dioxide (CO ₂ ) generated by decomposition of organic matter. When water having a high CO ₂ concentration is introduced into an electric regenerative deionization unit or an ion exchanger, there is a possibility that problems such as a decrease in the quality of treated water and an increase in the regeneration frequency may occur. Therefore, the treated water from which the oxidant has been removed may be previously passed through a membrane degassing, vacuum degassing, nitrogen degassing column or the like, degassed to remove CO ₂ , and then passed through the deionizer.

The treatment process according to the invention,

After coagulation filtration of raw water and activated carbon treatment

After coagulation filtration of raw water, activated carbon treatment and reverse osmosis membrane treatment

After coagulation filtration of raw water, activated carbon treatment and two-stage reverse osmosis membrane treatment

After coagulation filtration of raw water, activated carbon treatment and ion exchange treatment

It is suitable for application to the back.

Example

An Example is given to the following and this invention is demonstrated to it further more concretely.

In the following examples, the semiconductor plant process wastewater containing the following water chelating agent and DMSO was treated as raw water.

<Semiconductor Plant Process Drainage Water Quality>

TOC concentration: 2 mg / L

TOC ingredient: chelating agent = 0.1 mg / L

DMSO = 1.5 mg / L

Other = 0.4 mg / L

DO: 3 mg / L

pH: 5.4

In addition, the TOC density | concentration of treated water was measured using SIEVERS company TOC system "SIEVERS900", and the removal rate with respect to TOC density | concentration of raw water was calculated | required.

Example 1

Experiment 1

The semiconductor factory process wastewater was aerated with raw water of pH 5.4 without pH adjustment, and was made DO 6mg / L (DO / TOC = 3), and 20 weight-fold of sodium peroxydisulfate was added with respect to TOC density | concentration. Thereafter, the wastewater was passed through an ultraviolet oxidation device and irradiated with ultraviolet rays under the condition of 0.1 kwh / m 3.

Sodium hydroxide aqueous solution was added to this ultraviolet oxidation treatment water, and it adjusted to pH6. Subsequently, this water was passed through an activated carbon [Kurita Industrial Co., Ltd. "Chicol WG10-32") tower on the conditions of SV = 20hr- ¹ , and the residual oxidizing agent was decomposed | processed. Subsequently, the carbon dioxide produced by the decomposition of organic matter was removed by membrane degassing, and then the water was passed through an electric regenerative deionizer to remove organic acids and residual ions.

The TOC removal rate by this process is shown in FIG.

Experiment 2

Acid (hydrochloric acid) was added to the semiconductor plant process drainage with sodium peroxydisulfate to pH 4, and then water was treated in the same procedure as in Experiment 1. The TOC removal rate by this process is shown in FIG.

Experiment 3

Alkaline (NaOH) was added to the semiconductor plant process drainage along with sodium peroxydisulphate and passed through the UV oxidation apparatus at a pH of 10, and then water was treated in the same procedure as in Experiment 1. The TOC removal rate by this process is shown in FIG.

Experiment 4

Alkaline (NaOH) was added to the semiconductor plant process drain with sodium peroxydisulfate to pH 10.5, and water was treated in the same procedure as in Experiment 1. The TOC removal rate by this process is shown in FIG.

In Fig. 1, good results can be obtained when the pH of the water supply of the ultraviolet oxidation device is in the range of 4 to 10, and when the pH exceeds 10, it can be seen that the TOC removal rate rapidly decreases. This is due to the self decomposition of sodium peroxydisulfate in the alkaline region.

Example 2

In Experiment 1 of Example 1, except that the addition amount of sodium peroxydisulfate was changed in the range of 1 to 300 weight times with respect to the raw water TOC value [Na ₂ S ₂ O ₈ / TOC = 1 to 300 (weight ratio)]. treatment, expressed in Na ₂ S ₂ O ₈ / TOC and Figure 2 the relationship between the TOC removal rate.

In Fig. 2, as the amount of sodium peroxydisulfate added increases, the TOC removal rate is improved, but when Na ₂ S ₂ O ₈ / TOC = 200 times, the TOC removal rate is almost unchanged, that is, Na ₂ S ₂ O ₈ / It turns out that the range of TOC = 10-200 is preferable.

Example 3

In Experiment 1 of Example 1, the air aeration amount of the raw water was controlled, and the same treatment was performed except that the DO / TOC of the water supply of the ultraviolet oxidation device was changed to a range of 1.5 to 4, and the relationship between the DO / TOC and the TOC removal rate 3 is shown.

In Fig. 3, it can be seen that the TOC removal rate improves with increasing DO / TOC, and when the DO / TOC = 3 times, the TOC removal rate is almost unchanged, that is, DO / TOC≥3. .

Example 4

In Experiment 1 of Example 1, except having changed the ultraviolet irradiation amount in the ultraviolet oxidation apparatus into the range of 0.01 kwh / m <3> -0.7 kwh / m <3>, it processed similarly and the relationship of ultraviolet irradiation amount and TOC removal rate is shown in FIG.

In Fig. 4, it can be seen that the TOC removal rate is improved with the increase of the ultraviolet irradiation amount, and that the TOC removal rate is almost unchanged at an irradiation dose of 0.05 kwh / m 3 or more, that is, the ultraviolet irradiation amount is preferably 0.05 kwh / m 3 or more. .

Although this invention was demonstrated in detail using the specific form, it is clear for those skilled in the art for various changes to be possible, without leaving | separating the intent and range of this invention.

This application is based on the JP Patent application (Japanese Patent Application 2007-068881) of an application on March 16, 2007, The whole content is integrated by reference.

Claims (14)

A pharmaceutical addition step of adding a sulfur compound containing a peroxide group to the organic-containing wastewater, An ultraviolet oxidation step of irradiating ultraviolet light to the treated water from the drug addition step; An oxidizing agent removing step of removing an oxidizing agent in the treated water from the ultraviolet oxidation step; Deionization process which deionizes the treated water from this oxidant removal process Organic material removal method comprising a. The organic matter removal method according to claim 1, wherein the amount of the sulfur compound added in the chemical agent addition step is 10 to 200 weight times the TOC concentration of the organic matter-containing waste water. The method for removing organic matters according to claim 1, wherein the amount of ultraviolet irradiation in the ultraviolet oxidation step is 0.05 kwh / m 3 or more per unit of water to be treated. The organic material removal method according to claim 1, wherein the pH of the water flowing into the ultraviolet oxidation process is 4 to 10. The method of claim 1, wherein oxygen is dissolved in water introduced into the ultraviolet oxidation process so that dissolved oxygen (DO) concentration in the water is DO / TOC ≧ 3 (weight ratio) relative to the total organic carbon (TOC) concentration of the water. An organic substance removal method comprising an oxygen dissolving step. The method of claim 1, wherein the pH of the water flowing into the oxidizing agent removing step is 5 or more. The organic substance removal according to any one of claims 1 to 6, further comprising a degassing step of degassing the treated water of the oxidant removing step, wherein the treated water of the degassing step is supplied to the deionization step. Way. Chemical | medical agent addition means which adds the sulfur compound containing a peroxide group to organic matter containing wastewater, Ultraviolet oxidizing means for irradiating ultraviolet light to the treated water from the drug adding means; Oxidant removing means for removing oxidant in the treated water from the ultraviolet oxidizing means, Deionization means for deionizing the treated water from the oxidant removing means Organic material removal device comprising a. The organic matter removal apparatus according to claim 8, wherein the amount of the sulfur compound added in the chemical agent addition means is 10 to 200 weight times the TOC concentration of the organic matter-containing waste water. The organic matter removing apparatus according to claim 8, wherein the amount of ultraviolet irradiation in the ultraviolet oxidation means is 0.05 kwh / m 3 or more per unit of water to be treated. The organic material removing apparatus according to claim 8, wherein the pH of the water flowing into the ultraviolet oxidation means is 4 to 10. 9. The method of claim 8, wherein oxygen is introduced into the water flowing into the ultraviolet oxidation means such that the ratio DO / TOC of the dissolved oxygen (DO) concentration in the water and the total organic carbon (TOC) concentration in the water is 3 or more. And an oxygen dissolving means for dissolving. The organic matter removing apparatus according to claim 8, wherein the pH of the water flowing into the oxidizing agent removing means is 5 or more. The organic substance removal according to any one of claims 8 to 13, comprising degassing means for degassing the treated water of the oxidant removing means, wherein the treated water of the degassing means is supplied to the deionizing means. Device.

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