JP2003275773A - Wastewater treatment method for polyphenylene sulfide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and continuously treat wastewater containing high COD substances discharged in a purification step at the time of production of polyarylene sulfide represented by polyphenylene sulfide without using a sedimentation tank Provided are a treatment method and a wastewater treatment device. SOLUTION: A coagulant is added to a wastewater containing a COD substance after pH adjustment, or a pH is adjusted by adding an acidic coagulant, so that the COD substance is insolubilized and the insolubilized COD substance is separated. It is a wastewater treatment method. In addition, the wastewater from the purification step is introduced, has a mixing function, and is equipped with a pH indicator controller, capable of pH adjustment and coagulation treatment, and an insolubilized reaction tank introduced from the coagulation reaction tank. A wastewater treatment device comprising a continuous centrifugal separator for separating COD substances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method and a wastewater treatment apparatus for producing polyphenylene sulfide (hereinafter abbreviated as PPS). More specifically, PP
Polyarylene sulfide represented by S (hereinafter, PA
The present invention relates to a wastewater treatment method and a wastewater treatment apparatus that contain a hardly decomposable COD substance (that is, an oxidizable substance) generated by washing with water in a purification step of S).

[0002]

2. Description of the Related Art PAS represented by PPS is heat resistant,
It has excellent chemical resistance and is being widely used for electric and electronic parts, molded parts such as automobile parts, fiber and film applications.

Typical methods for producing PAS include, for example, Japanese Patent Publication Nos. 45-3368 and 52-12240.
Organic polar solvents (eg,
N-methylpyrrolidone (hereinafter abbreviated as NMP), N, N
In dimethylacetamide, N-methyl-ε-caprolactam, etc., a sulfidizing agent (for example, an alkali metal sulfide represented by sodium sulfide, or an alkali metal hydrosulfide represented by sodium hydrosulfide and sodium hydroxide) Combination of alkali metal hydroxides)
And a polyhaloaromatic compound typified by p-dichlorobenzene.

The polymerization reaction is usually carried out under alkaline conditions of high temperature and high pressure. For example, sodium sulfide and p are used as raw materials.
-When dichlorobenzene is used, the target substance PP
In addition to the production of sodium chloride, the so-called "crude reaction product" after the polymerization reaction contains unreacted raw materials, solvents, by-products, oligomers and the like.

The crude reaction product after the polymerization reaction is taken out into a suitable container, and the solvent contained therein is separated and recovered by using a suitable solid-liquid separation device such as a vacuum distillation device, a filter, a centrifugal separator and the like. (This operation is called desolvation), and it is reused or, if necessary, further purified before use.

On the other hand, the "crude polyarylene sulfide" after desolvation is generally repeatedly washed with water and filtered to mainly remove impurities such as sodium chloride and alkaline substances. Generally, a method of washing with water below 100 ° C. and 1
There is hot water washing performed under high temperature and high pressure of 00 ° C or higher. PPS
After washing with water or hot water, the product is separated with a filter, a centrifugal filter, etc., then dried, and if necessary, heat treated to carry out a crosslinking reaction to obtain a product.

Of the wastewater generated during the refining process, COD
The solvent that causes the load can be improved by improving the recovery rate of the solvent at the time of desolventization, and unreacted sulfide can be reduced in COD by oxidation treatment, but it is more than half of the total washed wastewater It did not reach the reduction of COD substances contained in.

As a conventional method for treating wastewater containing a COD substance, a method of adjusting pH and aggregating is generally known. For example, JP-A-8-257574 discloses a COD.
To the wastewater containing the substance, an alcal agent is added to adjust the pH, an oxidant is added and mixed, the COD substance is oxidized in the presence of manganese dioxide, and an inorganic or polymer coagulant is further added to coagulate and precipitate. A method is disclosed in which a COD substance is insolubilized in a tank, precipitated while being aggregated, and then removed, and the supernatant water is neutralized and discharged. However, in the method described in JP-A-8-257574, it takes a long time to precipitate the insolubilized COD substance, and a large processing tank and a large installation space are required. In addition, considering the apparatus for extracting the precipitate and treating it with a decanter, the cost becomes high, and further there is a problem that continuous processing is difficult in the operation of extracting the precipitate.

Further, the method of sending the reaction liquid containing the agglomerated COD substance to the solid-liquid separation device and performing the separation treatment has a problem in practical use because the oily substance as it is has extremely low separation efficiency. Therefore, there is a method of diluting with a large amount of water and draining it, but it is not preferable in terms of environmental pollution.

Further, JP-A-11-169870 discloses a method of adding a hypochlorous acid compound after adjusting the pH of the colored waste water discharged in the step of isolating and purifying PAS during the production of PAS to 7 to 10. However, the purpose was to decolorize the colored wastewater, not to remove the COD substance.

[0011]

SUMMARY OF THE INVENTION In view of the above problems, the present invention efficiently removes high COD substance-containing wastewater discharged in the purification step during the production of polyarylene sulfide typified by polyphenylene sulfide. It is an object of the present invention to provide a wastewater treatment method and a wastewater treatment apparatus capable of continuous treatment without using a settling tank.

[0012]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that alkaline waste water containing a COD substance in a purification step during the production of PAS represented by PPS is acidic. Solid-liquid separation is achieved by adding an aggregating agent to adjust the pH to 4 to 6 to insolubilize or sparingly dissolve the COD substance (referred to as “acid deposition treatment”) and to precipitate large flocs in the form of an acidic aggregating agent. To facilitate
The inventors have found that the COD substance can be easily removed, and completed the present invention.

That is, the present invention is a step of isolating and purifying polyphenylene sulfide from a product containing polyphenylene sulfide obtained by reacting a polyhaloaromatic compound with a sulfidizing agent in an organic polar solvent (purification step).
In the wastewater containing the COD substance (that is, the oxidizable substance), the pH of the COD substance is added after the pH is adjusted, or the pH of the COD substance is adjusted by adding an acidic flocculant to make the COD substance insoluble or hardly soluble. A method for treating wastewater of polyphenylene sulfide, which comprises separating a solubilized COD substance.

Further, according to the present invention, an aggregating reaction tank is introduced in which wastewater in the purification step during the production of polyphenylene sulfide is introduced, has a mixing function, and is equipped with a pH indicator controller and capable of pH adjustment and aggregating treatment. And a continuous centrifugal separator for separating insolubilized or sparingly-solubilized COD substances introduced from the coagulation reaction tank, which is a wastewater treatment device for polyphenylene sulfide.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A PAS typified by PPS is a conventionally known compound containing at least one polyhaloaromatic compound and at least one sulfidizing agent in an organic polar solvent such as N-methylpyrrolidone. Obtained by reacting under polymerization conditions. After the polymerization reaction, a method of recovering the solvent by removing the solvent from the crude reaction product by a suitable method such as distillation of the solvent or filtration under a reduced pressure condition is generally used, and the present invention is not particularly limited.

The polyhaloaromatic compound referred to in the present invention is
For example, a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic ring, for example, p
-Dichlorobenzene, o-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, tetrachlorobenzene, dibromobenzene, diiodobenzene, tribromobenzene, triiodobenzene, dichloronaphthalene, dibromonaphthalene, dichloro Polyhaloaromatic compounds such as diphenylbenzene, dibromodiphenylbenzene, dichlorobenzophenone, dibromobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl sulfide, dichlorobiphenyl, dibromobiphenyl, and these A mixture may be mentioned. Among these, preferred is one containing p-dichlorobenzene in an amount of 80 mol% or more based on the total number of moles of the polyhaloaromatic compound used.

The sulfidizing agent referred to in the present invention is
It is not particularly limited and can be used as an anhydride or a water-containing substance or an aqueous solution of an alkali metal sulfide, for example, lithium sulfide, sodium sulfide, potassium sulfide,
Examples thereof include rubidium sulfide and cesium sulfide, and hydrates thereof. These may be used alone or in combination of two or more. Among the above alkali metal sulfides, sodium sulfide and potassium sulfide are preferable from the viewpoint of excellent reactivity, and sodium sulfide is particularly preferable.

These alkali metal sulfides can be obtained by, for example, contacting an alkali metal hydrosulfide and an alkali metal hydroxide or hydrogen sulfide and an alkali metal hydroxide in advance in a reaction vessel and reacting them. Although it can also be obtained, a product prepared outside the reaction system may be used.

As the alkali metal hydroxide, for example,
Lithium hydroxide, sodium hydroxide, potassium hydroxide,
Examples include rubidium hydroxide and cesium hydroxide,
Of these, lithium hydroxide, sodium hydroxide and potassium hydroxide are preferable, and sodium hydroxide is particularly preferable. These may be used alone or in combination of two or more. The alkali metal hydrosulfide and the alkali metal hydroxide may be used in the reaction in any form such as a solid state, a liquid state and a molten state, and there is no particular limitation.

Incidentally, a small amount of alkali metal hydroxide may be added in order to react with the alkali metal hydrosulfide and the alkali metal thiosulfate which are usually present in trace amounts in the alkali metal sulfide.

The alkali metal hydrosulfide is not particularly limited, and it can be used as an anhydrous or hydrous substance or an aqueous solution of the alkali metal hydrosulfide. As the alkali metal hydrosulfide, for example, lithium hydrosulfide, sodium hydrosulfide,
Examples thereof include potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide, with sodium hydrosulfide being preferred. These may be used alone or in admixture of two or more.

The organic polar solvent used in the present invention is, for example, N-methylpyrrolidone (hereinafter abbreviated as NMP), N-cyclohexylpyrrolidone, N-methyl-ε.
-Caprolactam, formamide, acetamide, N-
Methylformamide, N, N-dimethylacetamide,
2-pyrrolidone, ε-caprolactam and the like can be mentioned, and among these, N-methylpyrrolidone is particularly preferable because it is excellent in the property of improving the reactivity of the sulfidizing agent.

The amount of the organic polar solvent used is not particularly limited because it varies depending on the type of solvent used and the amount of water in the system relative to the solvent in the system, but the reaction system is maintained in a stirrable state. In order to achieve this, the amount of the organic polar solvent used for the polymerization is preferably in the range of 1.0 to 6.0 mol, and more preferably 2.5 to 4 mol, per mol of the sulfur source in the sulfidizing agent. It is in the range of 0.5 mol.

If necessary, before carrying out the polymerization reaction,
For example, an organic polar solvent and an alkali metal sulfide as a raw material, or an alkali metal hydrosulfide and an alkali metal hydroxide are added to a reaction vessel, water in the system is distilled out of the system while heating, a so-called, It is advisable to carry out the polymerization reaction by performing a dehydration reaction and then sealing and then dropping a melt of a polyhaloaromatic compound or a solution using an organic polar solvent.

The polymerization conditions are not particularly limited, but are preferably in the range of 180 to 300 ° C, more preferably 200 to 260 ° C, particularly preferably 200 to 250 ° C.
Is the range. By carrying out the polymerization reaction at a relatively low temperature, side reactions can be suppressed, and PAS having excellent physical properties and good color tone can be obtained.

After the completion of the polymerization reaction, it is usually preferred that the solvent in the crude reaction product is desolvated and separated and recovered by an appropriate solid-liquid separation device such as a vacuum distillation device, a filter and a centrifugal separator. .

The crude polyarylene sulfide after desolvation is usually subjected to repeated washing with water and filtration, and further under high temperature and high pressure conditions of 100 ° C. or higher (for example, about 190 ° C. and about 1.6 MP.
It is preferable that the hot water washing and filtration in a) are repeated to remove impurities such as an alkali metal halide salt (for example, sodium chloride), an alkaline substance (for example, NaSH, NaOH, etc.), and a by-product.

The present inventors have found that PAS represented by PPS
The COD substances contained in the wastewater are analyzed in detail throughout the entire process from the polymerization process to the purification process and the solvent recovery process during production, and the main causative agent is the release of organic polar solvents (eg NMP). It was elucidated that it is a reaction product of a ring compound and a polyhaloaromatic compound (for example, p-dichlorobenzene), which is discharged together with the filtrate in the filtration in the hot water washing step and contained in the waste water.

Furthermore, the present inventors have found that the ring-opened product of an organic polar solvent (eg, NMP), which is the main COD substance, and a polyhaloaromatic compound (eg, p-dichlorobenzene).
As a result of diligent study to remove the reaction product with A, the reaction product has the following characteristics due to the difference in pH range.
COD can be converted into 3 types of compounds of B type, B type, or C type, and by adjusting the pH range of the filtrate, the COD can be converted into a type that is insoluble or hardly soluble in water and separated to significantly reduce COD. It has been found that it can be reduced to.

For example, when NMP is used as an organic polar solvent in a polymerization reaction using p-dichlorobenzene,
In the hot water washing step, the reaction product of the NMP ring-opened product and p-dichlorobenzene is removed from the PAS. The reaction product is changed to A type, B type, or C type depending on the pH range of the filtrate as follows. They can be converted into each other, and by conversion, they become water-soluble or insoluble or hardly soluble in water.

An example of interconversion of the reaction product of the NMP ring-opened product and p-dichlorobenzene will be shown below.

[0032]

[Chemical 1]

In the present invention, the pH of the filtrate in the hot water washing step is adjusted so that CO that is insoluble or sparingly soluble in water is precipitated.
It is preferable to separate the substance D by an appropriate method such as a centrifugation method or a decantation method.

In the present invention, the pH of the filtrate in the above-mentioned hot water washing step is adjusted and CO that is insoluble or sparingly soluble in water to be precipitated.
When separating the D substance, the coagulant is added to the waste water or the filtrate containing the COD substance after pH adjustment or the acidic coagulant is added to adjust the pH to make the COD substance insoluble or hardly soluble in water, and thus the insoluble or difficult to dissolve. It is more preferable to separate the solubilized COD substance from the viewpoint of increasing the removal rate of the COD substance.

The wastewater treatment method of polyphenylene sulfide of the present invention is a wastewater treatment method of introducing a liquid containing a COD substance insolubilized or hardly soluble in water into a continuous centrifugal separator and separating it together with the COD substance.

In the present invention, in order to make the COD substance insoluble or hardly soluble in water, it is preferable to adjust the pH of the waste water or the filtrate to an appropriate pH range. In the present invention, the pH of the waste water or the filtrate containing the COD substance (for example, the reaction product of the NMP ring-opened product and p-dichlorobenzene) is preferably in the range of 7 to 4, more preferably pH 6 to 4. It is preferable that the COD substance is adjusted to be in the range, and the COD substance is insolubilized or hardly solubilized in water to be precipitated and separated.

In the present invention, the pH of the waste water or the filtrate is adjusted to 4-6.
It is preferable to adjust to the range of (4) so that a floc of a size suitable for solid-liquid separation is formed. In order to make the solid-liquid separation treatment efficient, it depends on the type of the organic polar solvent used in the polymerization reaction, but in the case of NMP, it is particularly preferable to adjust the pH of the waste water or the filtrate to around 5.

Examples of the aggregating agent that can be used in the present invention include inorganic aggregating agents, surfactants and polymer aggregating agents.

The inorganic coagulant has a usable pH
Any one can be used as long as it has a wide range, flocs are rapidly produced, and separation treatment of agglomerates is appropriately performed. For example, vansulfate (aluminum sulfate), polyaluminum chloride, etc. can be used. , At least one acidic flocculant selected from ferrous sulfate, ferric sulfate, ferric chloride, zinc chloride, etc .; at least one acid selected from sulfuric acid, hydrochloric acid, carbon dioxide, etc .; or active silicic acid Etc. Among these inorganic flocculants used in the present invention, van sulphate is particularly preferable in terms of flocculation effect and storage stability.

Van sulphate soil produces, for example, an aggregate 1b of a size suitable for separation in the treatment method in which the reaction liquid 1a overflowed in FIG. 1 is introduced into the solid-liquid separator 9. The size of flocs, which are aggregates, is not particularly limited, but is usually about 2 to 4 mm.

The amount of bansulfate added is such that the pH of the wastewater or filtrate before addition (usually on the alkaline side, pH 10
However, in the case of a 6% aqueous solution of vanadium sulphate (aluminum sulfate) per liter of drainage or filtrate, it is not particularly limited, but is preferably in the range of 1 to 10 ml, more preferably Is 4-6 ml
Use in the range of.

In FIG. 1, the stirring blade 4 in the flocculation reaction tank 3
Is also related to the size of the flocs to be generated. For example, when the amount of the reaction solution 1a is 1.5 to 2.5 m ³ , in order to prevent the flocs from being broken and becoming smaller without reducing the reaction efficiency. The rotating speed of the stirring blade 4 may be appropriately adjusted and is not particularly limited, but is usually 100 to 200 rpm.
Is preferred.

The contact time (residence time) of the reaction liquid 1a in the flocculation reaction tank 3 is not particularly limited, but is usually 20.
It is preferably 5 minutes or less, more preferably 5 minutes or less. The temperature of the reaction solution 1a is not particularly limited,
Generally, the temperature is preferably lower than 100 ° C, more preferably 30 to
It is in the range of 60 ° C.

The polymer flocculants usable in the present invention include anionic polymer flocculants (sodium alginate, sodium carboxymethyl cellulose, sodium polyacrylate, maleic acid copolymer salt, polyacrylamide partial hydrolysis). Salt, etc., cationic polymer flocculant (water-soluble aniline resin hydrochloride, polythiourea acetate,
Polyethyleneaminotriazole, polyvinylbenzyltrimethylammonium chloride, chitosan, polyethyleneamine, vinylpyridine copolymer salt, polyacrylic acid ester-based cationic polymer, etc., nonionic polymer flocculant (starch, water-soluble urea resin, polyacrylamide) , Polyoxyethylene, etc.) and amphoteric polymer flocculants (gelatin etc.), and among these, anionic polymer flocculants and nonionic polymer flocculants are preferable. Also,
An inorganic flocculant and a polymer flocculant may be used together, and a surfactant may be used together, as long as the object of the present invention is not impaired.

In the wastewater treatment equipment of the present invention, the wastewater in the refining step in the production of polyarylene sulfide represented by polyphenylene sulfide is introduced, has a mixing function, and is equipped with a pH indicator controller to adjust pH. And a continuous centrifuge for separating insolubilized or sparingly soluble COD substances introduced from the coagulation reaction tank.

Examples of the solid-liquid separation apparatus for the solid-liquid mixture containing flocs used in the present invention include a centrifuge, a centrifugal filter, a filter press, a horizontal belt, etc. Has high separation efficiency,
A horizontal continuous centrifuge having a high processing capacity and a small installation space is preferable. Among these, a rotary type having a screw conveyor inside or a decanter having a structure in which the diameter is reduced to the discharge side of solid matter can be used, and for example, an RJ type rotary decanter / separator decanter (manufactured by Mitsubishi Kakoki Co., Ltd.) ), A screw decanter (manufactured by Saito Centrifugal Industry Co., Ltd.) and the like.

FIG. 1 shows an example in which a horizontal decanter type screw decanter type device is used as the solid-liquid separation device 9. FIG. 2 is a schematic sectional view of the screw decanter type device. Reaction liquid 1a supplied to the supply port 10
Is rotated by a speed reducer 11 which gives a relative speed difference, and is put into a space formed by a rotary cylinder 12 and screw blades 13. The treatment liquid 1c is brought to the inner surface of the outer periphery of the rotating body by centrifugal force, separated from the aggregate 1b, and the overflowed liquid is discharged. On the other hand, the flocs that are brought close to the outer circumference of the inner surface of the rotary cylinder 12 are sent to the side opposite to the processing liquid 1c by the screw blades 13. The number of revolutions of the solid-liquid separation device 9 is not particularly limited, but is preferably 3,000 to 5,000 rpm, more preferably 3,500 to 4,500 rpm. The water content (%) of the aggregate 1b separated by such a method is usually 40 to 6
It is 0% by weight. The term "water content" as used herein is a value calculated from the amount of decrease after about 2 g of a sample was weighed and left in a hot air dryer at 150 ° C for 2 hours.

FIG. 1 is a schematic flow chart showing one embodiment of wastewater treatment using the wastewater treatment method and the wastewater treatment apparatus of the present invention.

In FIG. 1, an alkaline raw water 1 produced during the production is introduced into a flocculation reaction tank 3 by a raw water feed pump 2. The aggregating reaction tank 3 is provided with a stirring blade 4 for uniformizing the liquid and promoting the reaction, and a pH indicator controller 5 for detecting the pH of the reaction liquid 1a. In addition, although FIG. 1 which is one embodiment of the present invention shows an example in which a stirring blade 4 is installed in order to make the liquid in the agglomeration reaction tank 3 uniform, mixing for making the liquid uniform and promoting the reaction is shown. Any material may be used as long as it has a function, for example, a method in which the coagulation reaction tank 3 has a return line and a circulation pump to circulate and mix the reaction treatment liquid 1a to homogenize it, and to use a gas such as nitrogen or air. A method of bubbling in the liquid in the agglutination reaction tank 3 to mix and homogenize it, and the like can be mentioned, and there is no particular limitation.

Next, the acidic coagulant 7 in the acidic coagulant storage tank 6 is supplied to the coagulation reaction tank 3 by the acidic coagulant supply pump 8 according to the value indicated by the pH indicator controller 5. The raw water 1 produces a floc-like aggregate 1b in the reaction liquid 1a by adjusting the pH to the weakly acidic side and stirring. The reaction liquid is allowed to overflow from the liquid upper surface of the aggregation reaction tank 3 and introduced into the solid-liquid separation device 9 so that the flocs that have aggregated are not precipitated.

The reaction liquid 1a is separated into an aggregate 1b and a treatment liquid 1c by the centrifugal separation type solid-liquid separation device 9. The flocs are discharged to the reduced diameter side of the apparatus by the sending means inside the separator, and the processing liquid 1c is discharged from the outer surface of the liquid supply side.

Next, the floc-like agglomerates 1b are stored by using an appropriate means such as a conveyer or a container, dried and reduced in volume as necessary, and then, for example, they are outsourced to an industrial waste disposal company or appropriately disposed. Incinerate at incineration facility. The treatment liquid 1c is discharged to the drainage pit 14, mixed with other treatment water in the treatment water storage tank, adjusted to an appropriate pH range, and then discarded or discharged.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings, but the present invention is not limited to these embodiments. All percentages are by weight unless otherwise specified.

Example 1 A pressure-resistant reactor equipped with a stirrer was charged with a predetermined amount of N-methylpyrrolidone (hereinafter abbreviated as NMP),
Sodium hydrosulfide (NaSH conversion concentration analysis value = 72.8
Wt%), 47.9 wt% sodium hydroxide aqueous solution was charged and the temperature was raised to 205 ° C. under stirring in a nitrogen atmosphere to obtain a distillate containing water. Next, after closing the nitrogen introduction line and the outflow line and sealing the pressure resistant reactor, 2
The temperature was raised to 30 ° C., and after reaching 230 ° C., a predetermined amount of an NMP solution of p-dichlorobenzene was added dropwise while controlling the heat generation of the reaction system, and after completion of the reaction, the mixture was reacted at 220 ° C. for 3 hours, then 30 The temperature is raised to 245 ° C over a period of 2 minutes and then 245
The reaction was carried out at ℃ for 1.5 hours. Then, the crude reaction product was taken out to a desolvation apparatus capable of distillation under reduced pressure and desolvated under heating and decompression conditions while stirring, and then the obtained solid product of crude polyarylene sulfide was transferred to a water-washing pot, and the weight of the polymer was adjusted according to the weight of the polymer. After adding a fixed amount of water and repeating washing with water at 80 ° C. and filtration, a predetermined amount of water was added at the end to obtain high temperature and high pressure conditions (190
Washing with hot water at 1.6 ° C. and filtration was performed. FIG. 1 shows a schematic flow chart of wastewater treatment using the wastewater treatment method and the wastewater treatment apparatus of the present invention.

In Example 1, the raw water 1 discharged from the washing filter medium in the PPS purification step is strongly alkaline and has a pH of 10 to 10.
It is about 12. After introducing the raw water 1 into the flocculation reaction tank 3,
A 6% aqueous solution of sulphate sulphate, which is the acidic flocculant 7, is continuously supplied by a pump, and the mixture is added with stirring to adjust the amount of sulphate sulphate to
The H was adjusted to about 5 to form flocs containing the COD material. In this way, the agglomerates 1b having a specific gravity of 1 or more were acidified, and the reaction liquid 1a containing the agglomerates 1b was introduced into the solid-liquid separator 9, that is, a screw decanter which is a horizontal continuous centrifugal separator, while stirring. . As a result, the COD of the treated liquid 1c treated with the vanadium sulfate soil which is the wastewater treatment method of the present invention was 436 mg / l, and the COD reduction rate in the raw water was 83%, which was excellent.

The treatment conditions with van sulphate are as follows. Acid Flocculant: Bansulfate Reaction liquid amount: 2 m ³ Reaction liquid temperature: 40 ° C. Contact time in reaction liquid: 10 minutes Stirring blade rotation speed: 150 rpm Type of screw decanter: Saito Centrifugal Industry Co., Ltd., Model SKD-320S Rotation speed: 4000 rpm

Example 2 Example 1 was repeated except that 20% hydrochloric acid aqueous solution was used instead of bansulfate.
I went the same way. As a result, the COD of the treated liquid 1c treated with the aqueous hydrochloric acid solution which is the wastewater treatment method of the present invention is 149.
It was 2 mg / l, and the COD reduction rate in raw water was 42%, which was excellent.

[Comparative Example 1] In Example 1, when the raw water 1 discharged from the washing filter medium was not treated in the PPS purification step, COD was 2557 mg / l, and the COD reduction rate in the raw water was It was 1% or less.

[0059]

INDUSTRIAL APPLICABILITY According to the present invention, wastewater containing a high COD substance, which is discharged in the purification step during the production of polyarylene sulfide represented by polyphenylene sulfide,
It is possible to provide a wastewater treatment method and a wastewater treatment apparatus that can efficiently and continuously perform COD substance removal without using a settling tank. Further, by using the wastewater treatment method and the wastewater treatment apparatus of the present invention, it becomes possible to reduce the installation area for wastewater treatment, to perform continuous treatment, and to increase the treatment capacity.

[Brief description of drawings]

FIG. 1 is a schematic flowchart showing processing steps.

FIG. 2 is a schematic cross-sectional view of a solid-liquid separation device in an example of the present invention.

[Explanation of symbols]

1 raw water 2 Raw water supply pump 3 Aggregation reaction tank 4 stirring blades 5 pH indicator controller 6 Acid Flocculant Storage Tank 7 Acid Flocculant 8 Acid Flocculant Supply Pump 9 Solid-liquid separator 10 Supply port 11 reducer 12 rotating cylinder 13 screw blades 14 drainage pit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hasegawa Sugio             2-6-3 Makizukadai, Sakai City, Osaka Prefecture (72) Inventor Nobuhiko Yamauchi             3-9-15 Futamachi, Izumiotsu City, Osaka Prefecture F-term (reference) 4D015 BA19 BA23 BB05 CA20 DA04                       DA05 DA15 DA16 DA28 EA13                       EA16 EA17 EA39                 4D038 AA08 AB09 AB12 AB14 BA06                       BB13 BB18 BB20                 4J030 BA03 BB29 BB31 BC02 BD22                       BG04 BG27

Claims (6)

[Claims] 1. A COD produced in a step (purification step) of isolating and purifying polyphenylene sulfide from a product containing a polyphenylene sulfide obtained by reacting a polyhaloaromatic compound with a sulfidizing agent in an organic polar solvent. The coagulant was added to the wastewater containing the substance (that is, the oxidizable substance) after the pH was adjusted, or the pH was adjusted by adding the acidic coagulant to insolubilize or sparingly dissolve the COD substance to make it insoluble or sparingly soluble. A method for treating wastewater of polyphenylene sulfide, which comprises separating COD substances. 2. The method for treating waste water of polyphenylene sulfide according to claim 1, wherein a liquid containing an insolubilized or sparingly solubilized COD substance is introduced into a continuous centrifugal separator and separated together with the COD substance. 3. The method for treating wastewater of polyphenylene sulfide according to claim 1, wherein the pH adjusting region of the wastewater containing the COD substance is 4 to 6. 4. The acidic coagulant is at least one selected from vanadium sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride and zinc chloride.
The method for treating wastewater of polyphenylene sulfide according to any one of 1. 5. The wastewater of the purification step at the time of producing polyphenylene sulfide is introduced and has a mixing function, and p
It is characterized by comprising an agglutination reaction tank equipped with an H indicator controller and capable of pH adjustment and agglutination treatment, and a continuous centrifugal separator for separating the insolubilized or hardly-solubilized COD substance introduced from the agglomeration reaction tank. Wastewater treatment equipment for polyphenylene sulfide. 6. The waste water treatment device for polyphenylene sulfide according to claim 5, wherein the continuous centrifugal separator is a screw decanter type device.