JP2004097997A - Method and equipment for treating water-soluble polymer-containing waste liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for treating a water-soluble polymer-containing waste liquid which can increase the reactivity of the water-soluble polymer-containing waste liquid in a hydrothermal oxidation reaction, efficiently perform oxidative decomposition of water-soluble polymers by the hydrothermal oxidation reaction without increasing the size of a hydrothermal oxidation reactor, perform the stable treatment at a high level, and hardly generate carbon monoxide. <P>SOLUTION: The water-soluble polymer-containing waste liquid and a neutralizing agent are supplied to a deposition tank 1. The feed rate of a pump P2 is regulated by a pH controller 12 so as to adjust the pH of the waste liquid to a prescribed pH, thereby neutralizing the waste liquid and insolubilizing the water-soluble polymers to be deposited in a suspended state. The suspended waste liquid is fed to a feeder 13 of the hydrothermal oxidation reactor 2 by a high pressure pump P1, and mixed with an oxidizing agent supplied from an oxidizing agent supply means 4, in the feeder. The mixed flow is fed to a reactor 3, and the hydrothermal oxidation reaction is carried out in the supercritical or subcritical state of water to oxidatively decompose organic substances. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for treating a wastewater containing a water-soluble polymer by a hydrothermal oxidation reaction, preferably a wastewater containing a water-soluble polymer generated in a manufacturing process of a semiconductor or an electronic component, particularly a manufacturing process using a dry film resist. The present invention relates to a method and an apparatus for stably and highly treating a wastewater containing a water-soluble polymer.
[0002]
[Prior art]
2. Description of the Related Art In recent years, semiconductors and electronic components have been miniaturized with the advance of information technology. In such a flow, various waste liquids are discharged from the manufacturing process of semiconductors and electronic components, and these treatments are problematic in various fields. One of those waste liquids is a water-soluble polymer-containing waste liquid discharged from a manufacturing process using a resist such as a dry film resist. This waste liquid is cured by exposing the circuit pattern to a substrate on which a resist such as a dry film resist is adhered, and then curing the unexposed and uncured resist with an aqueous alkali solution to remove the polymer in the resist. Becomes water-soluble and dissolves in water, generating a water-soluble polymer-containing waste liquid. Heretofore, this waste liquid has often been treated by an industrial waste disposal company, taking it little by little and putting it into a biological treatment apparatus. However, there is a large amount of waste liquid and the need for in-house treatment is increasing. Therefore, a new treatment technique has been desired.
[0003]
As a method of treating this kind of waste liquid, there is a hydrothermal oxidation treatment in which a hydrothermal reaction is performed in a supercritical or subcritical state of water in the presence of water and an oxidizing agent to oxidatively decompose organic substances. Hydrothermal oxidation can decompose organic effluents to a high level in a short period of time, and can also treat highly alkaline effluents while suppressing corrosion by neutralizing them with carbon dioxide generated by the decomposition of organic matter. It is possible. Further, the precipitated carbonate can be continuously discharged by a salt scraping mechanism.
[0004]
However, when the water-soluble polymer-containing waste liquid is treated by such a hydrothermal oxidation treatment, carbon monoxide (CO), which is a product generated when oxidation is incomplete, is generated. Although the amount of carbon monoxide generated can be reduced by raising the reaction temperature or lengthening the reaction time, hydrothermal oxidation, which is a reaction at high temperature and high pressure, increases the reactor wall thickness and the reaction. It is necessary to enlarge the vessel size. Therefore, a method for improving the reactivity of the waste liquid itself is required.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to increase the reactivity of a wastewater containing a water-soluble polymer in a hydrothermal oxidation reaction, and to efficiently decompose a water-soluble polymer by hydrothermal oxidation without increasing the size of the hydrothermal reactor. It is another object of the present invention to provide a method and an apparatus for treating a wastewater containing a water-soluble polymer, which can perform the treatment stably and to a high degree.
[0006]
[Means for Solving the Problems]
The present invention is the following method and apparatus for treating a wastewater containing a water-soluble polymer.
(1) a precipitation step of insolubilizing the water-soluble polymer in the water-soluble polymer-containing waste liquid and precipitating it in suspension;
A supply step of supplying the suspended waste liquid to the hydrothermal reactor,
A hydrothermal reaction step of performing a hydrothermal oxidation reaction in a supercritical or subcritical state of water in the presence of water and an oxidizing agent in a hydrothermal reactor to oxidatively decompose organic substances.
(2) The method according to the above 1, wherein the insolubilization of the water-soluble polymer is neutralization or esterification.
(3) The method according to the above (1) or (2), wherein the water-soluble polymer-containing waste liquid is a resist-containing waste liquid.
(4) a precipitation apparatus for insolubilizing the water-soluble polymer in the water-soluble polymer-containing waste liquid and depositing the suspension in a suspension state;
A supply device for supplying the suspended waste liquid to the hydrothermal reactor,
A water-soluble polymer-containing waste liquid containing a suspended liquid waste liquid and a hydrothermal reactor that performs a hydrothermal oxidation reaction in a supercritical or subcritical state of water in the presence of water and an oxidizing agent to oxidatively decompose organic substances. Processing equipment.
(5) The apparatus according to the above (4), wherein the precipitation apparatus is an apparatus for insolubilizing the water-soluble polymer by neutralization or esterification.
[0007]
The object to be treated in the present invention is a water-soluble polymer-containing waste liquid containing a water-soluble polymer. The water-soluble polymer is a polymer (organic polymer substance) having a hydrophilic group that becomes water-soluble. Examples of such a water-soluble polymer include, but are not limited to, resists used in semiconductor and electronic component manufacturing processes, such as dry film resists. Therefore, the water-soluble polymer-containing waste liquid is a waste liquid in which such a water-soluble polymer having a hydrophilic group is dissolved, and may contain other substances in addition to the water-soluble polymer. Examples of the water-soluble polymer-containing waste liquid include, but are not limited to, a waste liquid containing a resist discharged from a semiconductor or electronic component manufacturing process, such as a waste liquid containing a dry film resist.
[0008]
In the present invention, when treating such a water-soluble polymer-containing waste liquid, the water-soluble polymer in the water-soluble polymer-containing waste liquid is insolubilized and precipitated in a suspension, and the waste liquid deposited in the suspension is subjected to a hydrothermal reaction. The water is supplied to the apparatus, and in the hydrothermal reactor, a hydrothermal oxidation reaction is performed in a supercritical or subcritical state of water in the presence of water and an oxidizing agent to oxidatively decompose the polymer precipitated in suspension. To insolubilize and precipitate a water-soluble polymer in a suspended state means that the water-soluble polymer is insolubilized in a waste liquid, precipitates in a dispersed state, and exhibits a suspension state as a whole.
[0009]
As a result of examining measures to improve the reactivity of wastewater containing a water-soluble polymer in the hydrothermal oxidation reaction, the water-soluble polymer (resin) dissolved in the waste liquid is precipitated and suspended, and the hydrothermal oxidation reaction in the state of the suspension solution is performed. It was found that by performing the treatment, the reactivity of the hydrothermal oxidation reaction was greatly improved, and almost no carbon monoxide was generated. The reason why the reactivity is improved by precipitating and suspending the water-soluble polymer is considered as follows.
[0010]
As the water-soluble polymer-containing waste liquid is evaporated and concentrated, a polymer precipitates at a certain point in time. However, when the concentration is further continued, a phenomenon in which the polymer solidifies in a gel state is observed. A similar phenomenon occurs in the hydrothermal oxidation reactor, and the water-soluble polymer supplied into the reactor in the form of an aqueous solution is concentrated by evaporation when the liquid water gradually decreases in a high-temperature environment. As in the case where the polymer concentration increases, the polymer precipitates in a gel state and hardens. If the polymer solidifies in a gel state in such a state, the reaction proceeds only from the surface solidified in the gel state, and the reaction rate is reduced. As a result, the organic matter is not completely oxidized, and the carbon monoxide is discharged without decomposition.
[0011]
In the present invention, the water-soluble polymer is insolubilized and precipitated in a suspension, and the waste liquid precipitated in the suspension is supplied to a hydrothermal reactor to perform a hydrothermal oxidation reaction. In this state, it undergoes hydrothermal oxidation and undergoes oxidative decomposition. In the state where the polymer is precipitated in a suspended state, the surface area of the resin is larger than that in the state where the polymer is solidified, so that the treatment is performed with high efficiency with little decrease in reactivity, and the organic matter is completely oxidized. As a result, carbon monoxide is prevented from being discharged without decomposition.
[0012]
The method of insolubilizing the water-soluble polymer in the water-soluble polymer-containing waste liquid and causing it to precipitate in suspension can be selected according to the characteristics of each water-soluble polymer. In short, it suffices to make the hydrophilic group imparting water solubility hydrophobic, and examples thereof include neutralization and esterification. For example, in the case of a water-soluble polymer having a carboxylic acid Na salt as a functional group, the polymer is insolubilized and precipitated in suspension by neutralizing with an acid to form a carboxylic acid. In the case of esterification, a hydrophilic group can be made hydrophobic by an esterification reaction. However, in consideration of the fact that the precipitated polymer must have a large surface area, a simple precipitation method, and the like, a precipitation method by neutralization is preferable. The neutralizing pH varies depending on the state of the waste liquid, but is usually in the range of pH 3 to 7, preferably in the range of pH 4 to 6. If the pH is too high, the precipitation of the resin will be incomplete, and if the pH is too low, acid corrosion of the reactor may occur.
[0013]
In the case of a waste liquid containing a resist discharged from a semiconductor or electronic component manufacturing process, for example, a waste liquid containing a dry film resist, the carboxylic acid of the resist remaining uncured without being exposed becomes an Na salt by washing with an aqueous alkali solution, and the entire polymer is removed. Is dissolved as a water-soluble polymer. Therefore, by neutralizing the waste liquid with an acid, the polymer is insolubilized and precipitates in suspension.
[0014]
In the precipitation step of the present invention, the water-soluble polymer in the water-soluble polymer-containing waste liquid is insolubilized as described above, and is precipitated in a suspended state. This precipitation step may be provided in a supply step of supplying the waste liquid to the hydrothermal reactor, for example, injecting a neutralizing agent into a pipe for supplying the waste liquid to the hydrothermal reactor, but before the supply step or It is preferable to provide an apparatus for insolubilizing and precipitating the polymer in a suspension state in the supply step. For example, in the middle of the pipe for supplying the waste liquid to the hydrothermal reactor, a neutralization tank having a chemical injection tube, a stirrer and a pH adjuster is provided, and the mixture is stirred with the stirrer and the pH is adjusted with the pH adjuster so that the pH reaches a predetermined value. A neutralizing agent can be injected to neutralize the waste liquid, insolubilize the polymer and precipitate it in suspension.
[0015]
The supply step of the present invention is configured to supply the suspended waste liquid to the hydrothermal reactor by the supply device. Since the hydrothermal reactor is maintained at a high temperature and a high pressure, the supply device is configured to pressurize, and in some cases, heat the waste liquid in suspension to supply it to the hydrothermal reactor. In this case, for example, air may be pressurized as an oxidant and supplied to the hydrothermal reactor together with the waste liquid.
[0016]
In the hydrothermal reaction step, the waste liquid in which the polymer is precipitated in a suspended state is subjected to a hydrothermal oxidation reaction in a supercritical or subcritical state of water in a hydrothermal reactor in the presence of water and an oxidizing agent, and the precipitated polymer is Performs oxidative decomposition of other organic substances. The hydrothermal reactor is configured to perform a hydrothermal oxidation reaction by maintaining the waste liquid in a supercritical or subcritical state of water in the presence of an oxidizing agent. Here, the hydrothermal oxidation reaction is a reaction in which a concentrate is oxidatively decomposed by an oxidation reaction in the presence of high-temperature, high-pressure water and an oxidizing agent in a supercritical or subcritical state. The supercritical state is a state of 374 ° C. or higher and 22 MPa or higher. The subcritical state refers to, for example, a state of 374 ° C. or more, 2.5 MPa or more and less than 22 MPa, or a state of 374 ° C. or less, 22 MPa or more, or a high temperature and high pressure state of less than 374 ° C. or less than 22 MPa close to a critical point.
[0017]
Such a hydrothermal oxidation reaction is performed in a hydrothermal reactor in a state where the waste liquid is mixed with an oxidizing agent, and the mixture undergoes a hydrothermal reaction inside the reactor. Air, oxygen, liquid oxygen, and hydrogen peroxide can be used as the oxidizing agent. The oxidizing agent may be supplied by being mixed with the mixed sludge of the material to be treated, or may be supplied as a multi-layer flow by using a supply pipe with a double pipe nozzle. If necessary, a catalyst, a neutralizing agent, and the like may be added. These may be mixed with the waste liquid or separately supplied to the reactor.
[0018]
The hydrothermal reactor used in the present invention is formed of a heat-resistant and pressure-resistant material so as to perform a hydrothermal reaction in a supercritical or subcritical state. When the supercritical or subcritical state is not reached only by the heat of reaction, an external heating means can be provided.
[0019]
Although the material of the hydrothermal reactor is not limited, a corrosion-resistant material such as Hastelloy, Inconel, or stainless steel is preferable. Preferably, the hydrothermal reactor is provided with a corrosion resistant liner. The corrosion-resistant liner is not particularly limited, and a corrosion-resistant liner having a gap between the corrosion-resistant liner and the pressure load wall can be used.
[0020]
The hydrothermal reactor can be provided with cooling means for cooling the reaction mixture before discharging it from the outlet. The cooling means is not particularly limited, but quenching water can be introduced into the reactor to cool it, and the inorganic salt can be dissolved to facilitate its discharge. In addition, water containing an acid or an alkali can be introduced into the reactor and cooled to neutralize the alkali or the acid. If the solid is very sticky, a mechanical removal device for removing the solid attached to the inner wall of the reactor can be provided. The mechanical removal device for removing solids is not particularly limited, but a substantially cylindrical scraper including a cutout window is preferable. In order to provide such a mechanism, a tubular reactor arranged substantially vertically is preferable as a reactor shape. A cylindrical, elliptical, or polygonal cylindrical reactor can be used as the shape of the cylindrical reactor, and the lower end portion can have a cone shape.
[0021]
Separation means for separating solids in the reaction fluid discharged from the hydrothermal reactor can be provided. The solid matter separation means is not particularly limited, and a container having an inlet for introducing a reaction fluid from a hydrothermal reactor and an outlet for discharging a fluid from which solids have been removed, and a container provided in the container and having the reaction fluid One provided with a means for removing and discharging the solid contained therein can be used. The solids separating means is desirably provided upstream of a valve for reducing the pressure of the processing fluid. By doing so, wear and blockage of the pressure reducing valve can be prevented.
[0022]
In the present invention, in the hydrothermal reaction step, when a hydrothermal oxidation reaction is performed in a supercritical or subcritical state by the above-described hydrothermal reactor, the organic matter of the reactant is oxidized by the oxidizing agent and finally becomes water. Decomposed into carbon dioxide.
[0023]
The means for starting the reaction by the hydrothermal reactor is not particularly limited. Usually, the reactor is preheated to around a predetermined reaction temperature at the start of the reaction. The preheating can be carried out by providing a heating device in the reactor, or by introducing heated water or air provided in a waste liquid and / or oxidant supply passage. Further, usually, water or an oxidizing agent is supplied to the reactor, and the reactor is pressurized to a predetermined pressure by a normally provided pressure regulating valve. After the temperature and pressure are adjusted to predetermined values, a fluid containing mixed sludge as a reactant is supplied to start a hydrothermal reaction. Organic substances are decomposed by the reaction, and heat of reaction is generated.
[0024]
The reaction fluid that has exited the hydrothermal reactor is subjected to cooling and gas-liquid separation, and then the pressure of the processing liquid and the processing gas are separately reduced and discharged. The finally generated water, gas, and solid are directly recovered for energy recovery, reused as a substance, or directly or additionally processed for disposal.
[0025]
【The invention's effect】
According to the present invention, in a state where the water-soluble polymer in the water-soluble polymer-containing waste liquid is insolubilized and precipitated in the form of a suspension, a hydrothermal oxidation reaction is performed to oxidatively decompose the polymer. The water-soluble polymer can be efficiently oxidized and decomposed by the hydrothermal oxidation reaction without increasing the size of the hydrothermal reactor, and the treatment can be performed stably and at a high level. Thus, it is possible to obtain a method and an apparatus for treating a wastewater containing a water-soluble polymer, which hardly generates carbon monoxide.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of a water-soluble polymer-containing waste liquid treatment apparatus according to an embodiment.
[0027]
In FIG. 1, 1 is a precipitation tank, 2 is a hydrothermal reactor, 3 is a reactor, 4 is an oxidant supply means, 5 is a cooler, and 6 is a gas-liquid separator. The precipitation tank 1 supplies the wastewater containing the water-soluble polymer from the line L1, supplies the neutralizing agent from the line L2, measures the pH with the pH adjuster 12 while stirring with the stirrer 11, and adjusts the supply amount of the pump P2. Is configured to neutralize. The hydrothermal reactor 2 has a supply unit 13 at the upper part of the reactor 3, the lower part of the reactor 3 is formed in a cone shape, has a scraper 14 inside, and a quench water supply pipe 15 opens at the lower part. I have.
[0028]
A line L3 having a high-pressure pump P1 for supplying waste liquid from the precipitation tank 1 is connected to a supply device 13 provided above the reactor 3 of the hydrothermal reactor 2. The supply device 13 is connected to a line L4 connected to oxidant supply means 4 for supplying an oxidant. The supply device 13 is mounted so as to supply a mixed flow of the oxidizing agent and the waste liquid to the reactor 3 as a downward flow. A line L5 communicates with the cooler 5 from the lower part of the hydrothermal reactor 4, and a line L7 communicates with the gas-liquid separator 6 from the cooler 5. A gas discharge path line L8 having a pressure reducing valve V1 and a liquid discharge path L9 having a pressure reducing valve V2 communicate with the outside of the system from the gas-liquid separator 6. The cooling device 5 is connected to a cooling water passage L6.
[0029]
In the water-soluble polymer-containing waste liquid treating apparatus, the water-soluble polymer-containing waste liquid is supplied from the line L1 to the precipitation tank 1, the neutralizing agent is supplied from the line L2, and the pH is adjusted by the pH adjuster 12 while stirring with the stirrer 11. Is measured, and the supply amount of the pump P2 is adjusted to neutralize the measured value of the pH of the pH adjuster 12 so as to be a predetermined value (for example, pH 5). As a result, the water-soluble polymer in the waste liquid becomes insoluble and precipitates in suspension, and the waste liquid becomes a suspension.
[0030]
The suspended waste liquid is sent from the line L3 to the supply device 13 of the hydrothermal reactor 2 by the high-pressure pump P1, where the oxidant (eg, air, hydrogen peroxide solution) sent from the oxidant supply means 4 through the line L4. The mixture is mixed, and the mixed stream is supplied to the reactor 3 in a downward flow to perform a hydrothermal reaction. Organic matter is oxidized and decomposed in the reactor 3 by a hydrothermal oxidation reaction in a supercritical or subcritical state of the water in the reactor 3. In this hydrothermal oxidation reaction, the polymer is precipitated in suspension, so the surface area of the resin is larger than that in a gel-like state. Is diffused, whereby the organic matter is completely oxidized to carbon dioxide with little reduction in reactivity, and the organic matter is prevented from being discharged without being decomposed.
[0031]
The salt is dissolved in the suspended waste liquid, but does not dissolve in the supercritical state, and is precipitated in a salt state. When quench water is supplied from the lower quench water supply pipe 15 in this state, a part of the water becomes liquid and the salt is dissolved. The salt attached to the inner wall of the reactor 3 is removed by the scraper 14. The reactants in the reactor 3 are introduced into the cooler 5 from the line L5, and are cooled by cooling water supplied from the cooling water passage L6. The cooled gas-liquid mixed fluid is introduced into the gas-liquid separator 6 from the line L7 to be separated into gas and liquid, and the processing gas is discharged from the gas discharge path L8 and the processing water is discharged from the liquid discharge path L9.
[0032]
In the above embodiment, the neutralization tank type is shown as the precipitation apparatus, but another type such as a line mixer type may be used.
[0033]
【Example】
Hereinafter, examples of the present invention will be described.
Example 1
The wastewater containing a water-soluble polymer was treated by the treatment apparatus of FIG. A water-soluble polymer-containing waste liquid discharged from a manufacturing process using a dry film resist as a waste liquid to be treated was neutralized with sulfuric acid in a precipitation tank 3 with stirring to precipitate and suspend the dissolved polymer. Then, the waste liquid in which the polymer is suspended is supplied to the reactor 3 of the hydrothermal reactor 2 and air is supplied as an oxidizing agent. The reaction temperature is 650 ° C., the reaction pressure is 23.4 MPa, and the reaction time is 10 seconds. Oxidized. As a result, the hydrothermal oxidation treatment proceeded stably. The properties of the processing liquid and the processing gas were as follows, and organic substances could be almost completely decomposed.
Treated water TOC: <1 mg / L
Processing gas CO: <2 ppm
[0034]
Comparative Example 1
The water-soluble polymer-containing waste liquid discharged from the manufacturing process using a dry film resist was subjected to hydrothermal oxidation treatment under the same conditions as in Example 1 without pretreatment. As a result, during the hydrothermal oxidation treatment, a high concentration of carbon monoxide was detected in the treated gas. The properties of the treatment liquid and the treatment gas were also as follows, indicating that organic substances could not be completely decomposed and oxidation was incomplete.
Treated water TOC: 5mg / L
Processing gas CO: 200 to 900 ppm
[Brief description of the drawings]
FIG. 1 1 precipitation tank 2 hydrothermal reactor 3 reactor 4 oxidant supply means 5 cooler 6 gas-liquid separator 11 stirrer 12 pH adjuster 13 supply device 14 scraper 15 quench water supply pipe

Claims (5)

A precipitation step of insolubilizing the water-soluble polymer in the water-soluble polymer-containing waste liquid and precipitating it in suspension,
A supply step of supplying the suspended waste liquid to the hydrothermal reactor,
A hydrothermal reaction step of performing a hydrothermal oxidation reaction in a supercritical or subcritical state of water in the presence of water and an oxidizing agent in a hydrothermal reactor to oxidatively decompose organic substances. The method according to claim 1, wherein the insolubilization of the water-soluble polymer is neutralization or esterification. 3. The method according to claim 1, wherein the water-soluble polymer-containing waste liquid is a resist-containing waste liquid. A precipitation apparatus for insolubilizing a water-soluble polymer in a water-soluble polymer-containing waste liquid and depositing the suspension in suspension,
A supply device for supplying the suspended waste liquid to the hydrothermal reactor,
A water-soluble polymer-containing waste liquid containing a suspended liquid waste liquid and a hydrothermal reactor that performs a hydrothermal oxidation reaction in a supercritical or subcritical state of water in the presence of water and an oxidizing agent to oxidatively decompose organic substances. Processing equipment. The apparatus according to claim 4, wherein the precipitation apparatus is an apparatus for insolubilizing the water-soluble polymer by neutralization or esterification.

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