KR20130116244A - Method and device for anaerobically treating wastewater containing terephthalic acid - Google Patents

Abstract

(Problem) The hardly decomposable terephthalic acid-containing waste water is anaerobicly treated efficiently at low cost without requiring complicated apparatus equipment or complicated operation, and highly decomposes and removes terephthalic acid.
(Solution means) In anaerobic treatment of wastewater containing terephthalic acid, sulfuric acid root is added to the wastewater so that the concentration of sulfate ions in the anaerobic treated water is 5 to 200 mg / L. In the anaerobic treatment of terephthalic acid-containing waste water, when a predetermined amount of sulfate root is added, the decomposition efficiency of terephthalic acid in the anaerobic treatment is greatly improved. It is preferable to add sulfate sulfate so that content may be 10 mass% or more with respect to terephthalic acid in waste water.

Description

Anaerobic treatment method and apparatus for treating terephthalic acid-containing wastewater {METHOD AND DEVICE FOR ANAEROBICALLY TREATING WASTEWATER CONTAINING TEREPHTHALIC ACID}

The present invention relates to a method and apparatus for anaerobic treatment of terephthalic acid-containing waste water, and more particularly, to a method and apparatus for efficiently decomposing and removing hardly decomposable terephthalic acid in waste water by anaerobic treatment.

Drainage from the manufacturing process of polyethylene terephthalate usually contains terephthalic acid, paratoluic acid, benzoic acid, and the like.

In the case of anaerobic treatment of wastewater, nutrients, trace metals and the like are required in the anaerobic treatment system for cell synthesis. For example, sulfate ions SO ₄ ² for COD _Cr in the waste water ^- are in need of 1.5% in terms of. Chemical wastewater and electronic industry wastewater contain almost no components necessary for the synthesis of these cells. In the anaerobic treatment of these wastewater, a mineral component is added. Sulfuric acid ions are decomposed by sulfuric acid reducing bacteria in a methane fermenter to generate hydrogen sulfide gas, thereby increasing the load on the exhaust gas treatment. Since hydrogen sulfide inhibits methane fermentation and lowers treatment efficiency, sulfate ions are added so as not to be higher than the concentration required for cell synthesis.

Terephthalic acid and paratoluic acid are hardly degradable for anaerobic treatment.

The wastewater containing hardly decomposable organic matter which does not decompose | disassemble well in anaerobic treatment is aerobic-treated. Anaerobic treatment has the advantage of lower running costs and lower CO ₂ emissions due to the higher load treatment compared to aerobic treatment. Therefore, it is desired to anaerobically treat wastewater containing terephthalic acid or paratoluic acid.

Patent Document 1 describes a method of anaerobic treatment after ozone treatment of terephthalic acid-containing waste water in order to increase the decomposition efficiency of terephthalic acid in anaerobic treatment. However, this method has a high treatment efficiency, but the apparatus for ozone treatment is complicated, and the treatment cost is also high.

In order to prevent the flotation and the outflow of granule sludge, Patent Literature 2 adds an iron salt and a sulfate ion source to the drainage to generate iron sulfide (FeS) by reaction of the iron salt and sulfate ion, and fills the cavity of the granule sludge with iron emulsion. An anaerobic wastewater treatment method is described. In this method, since the added sulfate ion source precipitates as FeS, the sulfate ion concentration in an anaerobic treatment tank does not become high.

As described above, in the anaerobic treatment of wastewater, when the concentration of sulfate ions in the system is increased, hydrogen sulfide gas is generated. In order to suppress the generation of hydrogen sulfide gas, in the conventional anaerobic treatment of wastewater, the concentration of sulfate ions is not made higher than the concentration required for cell synthesis.

Japanese Unexamined Patent Publication No. Hei 6-269797 Japanese Patent No. 3814851

An object of the present invention is to provide a method and an apparatus capable of highly decomposing and removing terephthalic acid by anaerobicly treating a hardly decomposable terephthalic acid-containing waste water efficiently and at low cost without requiring complicated apparatus equipment or complicated operation.

The present inventors have intensively studied. As a result, in the anaerobic treatment of the terephthalic acid-containing wastewater, a predetermined amount of sulfate (SO ₄ ^{2 -)} in order to solve the above problems with the addition of, the destruction efficiency of the terephthalic acid in the anaerobic treatment dramatically I found out that it improved.

The present invention has been achieved on the basis of the above-described findings, and the following will be devised.

[1] A method for anaerobic treatment of wastewater containing terephthalic acid, wherein the sulfuric acid root is added to the wastewater so that the concentration of sulfate ions in the anaerobic treated water is 5 to 200 mg / l. Treatment method.

[2] The anaerobic treatment method of terephthalic acid-containing wastewater according to [1], wherein a sulfate root is added to the wastewater so that the content of sulfate sulfate in the wastewater is 60 to 400 mg / L.

[3] The anaerobic treatment method of terephthalic acid-containing wastewater according to [1] or [2], wherein the sulfuric acid root is added to the wastewater so that the content of sulfate root is 10% by mass or more relative to the terephthalic acid in the wastewater.

[4] The anaerobic treatment method of terephthalic acid-containing wastewater according to any one of [1] to [3], wherein the waste water contains 50 to 2000 mg / L of terephthalic acid.

[5] The anaerobic treatment method of terephthalic acid-containing wastewater according to any one of [1] to [4], wherein the wastewater further contains paratoluic acid.

[6] at least one member selected from the group consisting of sulfuric acid, iron (I), iron (II) sulfate, polyiron sulfate, ammonium sulfate, aluminum sulfate, sodium sulfate, and potassium sulfate in order to add sulfate sulfate to the drainage; The anaerobic treatment method for terephthalic acid-containing wastewater according to any one of [1] to [5], which is added to the wastewater.

[7] An apparatus for anaerobic treatment of wastewater containing terephthalic acid, comprising: a means for adding sulfate root to the wastewater so that the concentration of sulfate ions in the anaerobic treated water is 5 to 200 mg / l. Anaerobic treatment device for drainage.

[8] An anaerobic treatment apparatus for terephthalic acid-containing wastewater according to [7], comprising a means for adding sulfate root to the wastewater so that the content of sulfate root in the wastewater is 60 to 400 mg / L.

[9] The anaerobic treatment apparatus for terephthalic acid-containing wastewater according to [7] or [8], wherein the sulfate root is added to the wastewater so that the content of sulfate root is 10% by mass or more relative to the terephthalic acid in the wastewater.

[10] The anaerobic treatment apparatus for terephthalic acid-containing wastewater according to any one of [7] to [9], wherein the wastewater contains 50 to 2000 mg / L of terephthalic acid.

[11] The anaerobic treatment apparatus for terephthalic acid-containing wastewater according to any one of [7] to [10], wherein the wastewater further contains paratoluic acid.

According to the present invention, so that the anaerobic treatment sulfate ion concentration of 5 ~ 200 ㎎ / ℓ in water, in the terephthalic acid-containing wastewater sulfate group (SO ₄ ^{2 -)} by the addition of I efficiently decomposed and removed by the degradation of terephthalic acid in the anaerobic treatment The treated water of high quality can be obtained (claims 1 and 7).

The present invention can be implemented easily and at low cost with a simple apparatus without requiring complicated apparatus equipment or complicated operation.

In this invention, it is preferable to add sulfate sulfate so that content of wastewater may be 10 mass% or more with respect to terephthalic acid in waste water, and it may be 60-400 mg / L in waste water (claim 2, 3, 8, 9).

The present invention is preferable for the treatment of terephthalic acid-containing wastewater containing 50-2000 mg / L of terephthalic acid and further containing paratoluic acid (claims 4, 5, 10, 11).

Hereinafter, embodiments of the present invention will be described in detail.

In the present invention, in the anaerobic treatment of terephthalic acid-containing wastewater, a predetermined amount of sulfate root is added to the wastewater. By adding an excess amount of sulfate root to the waste water in excess of the amount necessary for cell synthesis, it is possible to promote the sulfuric acid reduction reaction. As a result, the partial pressure of hydrogen is lowered, and as a result, the anaerobic treatment system is brought into a reduced state, and the methane production reaction is promoted, whereby the hardly decomposable terephthalic acid is decomposed and removed.

[Terephthalic acid-containing drainage]

The raw water treated in the present invention includes a terephthalic acid-containing drainage, a terephthalic acid-containing wastewater discharged from various industrial fields such as the chemical industry and the electronics industry, for example, a manufacturing process drainage of polyethylene terephthalate.

The terephthalic acid concentration in the terephthalic acid-containing waste water is usually 50 to 2000 mg / L, preferably about 100 to 1000 mg / L, but is not limited thereto. If the concentration of terephthalic acid in the waste water is less than this lower limit, the significant difference from the normal treatment becomes small, and if it is larger than this upper limit, terephthalic acid tends to crystallize, which may lower the treatment efficiency.

The terephthalic acid-containing waste water may further contain easily decomposable organic substances such as paratoluic acid, benzoic acid, sugars, organic acids, and the like.

The addition of sulfate root in the anaerobic treatment is effective for improving the anaerobic treatment efficiency of paratoluic acid, and also shows a good treatment effect for wastewater containing paratoluic acid with terephthalic acid.

The content of paratoluic acid in the waste water is preferably 5000 mg or less, particularly preferably 50 to 5000 mg / l, more preferably 100 to 2000 mg / l, but is not limited thereto.

[Sulfuric acid root]

Sulfate (SO ₄ ^{2 -)} in the drainage agent for addition of the sulfuric acid, iron sulfate (I), iron sulfate (II), poly ferric sulfate, such as SO ₄ ^{2 -} containing an acid solution, ammonium sulfate, aluminum sulfate, sodium sulfate Although 1 type, or 2 or more types, such as soluble sulfates, such as potassium sulfate, are preferable, it is not limited to this.

Calcium sulfate and magnesium sulfate are poorly soluble in water, but at low concentrations, they are soluble in water.

The agent for adding the sulfate sulfate is preferably added as an aqueous solution having a SO ₄ ^{2 -} concentration of 5 to 30% by mass.

If the amount of the sulfate sulfate added to the waste water is too small, the effect of the present invention by adding the sulfate sulfate cannot be sufficiently obtained, and if it is too large, hydrogen sulfide gas is generated in a large amount.

The sulfate concentration of SO ₄ ^{2 −} concentration in the waste water is preferably 30 to 400 mg / l, more preferably 60 to 400 mg / l, more preferably 50 to 200 mg / l, particularly preferably 70 to 200 It is preferable to add so that it is mg / L.

The sulfate sulfate is preferably added to the wastewater at a ratio of 10% by mass or more, particularly 15 to 30% by mass, with respect to terephthalic acid in the wastewater. When the sulfate content is too small with respect to terephthalic acid in the waste water, the decomposition efficiency of terephthalic acid may not be sufficiently increased.

When the wastewater to be treated contains terephthalic acid and paratoluic acid, the sulfate root is preferably added to the wastewater at a ratio of 10% by mass or more, particularly 15 to 30% by mass, based on the total amount of terephthalic acid and paratoluic acid in the wastewater.

The sulfate root is added to the waste water so that the concentration of sulfate ion in the treated water obtained by the anaerobic treatment is 5 to 200 mg / l, preferably 10 to 20 mg / l. In the sulfate addition amount which the sulfate ion concentration of anaerobic treated water becomes lower than 5 mg / L, the addition effect of the sulfate root by this invention cannot fully be acquired. When the concentration of sulfate ions in the anaerobic treated water is excessively high, the amount of hydrogen sulfide gas generated increases, and the water quality of the anaerobic treated water itself is deteriorated, thereby increasing the load on the subsequent treatment process.

[Anaerobic treatment]

The anaerobic treatment method may be a one-phase formula in which the acid-producing step by the acid-producing bacteria and the methane fermentation step by the methane-producing bacteria are performed in the same tank, or a two-step formula in which these are carried out in different tanks.

Anaerobic treatment reactors are available in fixed phase, flow common sense, UASB (Upflow Anaerobic Sludge Blanket), EGSB (Expanded Granule Sludge Bed), which is capable of high load treatment by granulation of methane-producing bacteria. Sludge phase) system, etc. may be used, but it is preferably a UASB system or an EGSB system capable of high load treatment.

In the anaerobic treatment apparatus of one common sense, sulfate root may be added to any of the raw water flowing into the anaerobic treatment tank and the anaerobic treatment tank. When sulfuric acid is added as the sulfuric acid root, since the pH decreases due to the addition of sulfuric acid, when the pH adjusting tank is formed, it is preferable to add it at the front end thereof.

In the anaerobic treatment apparatus of the common sense, the addition point of the sulfate root is selected according to the amount of the substance to be treated in the wastewater. When there are many easy decomposition | disassembly substances in waste water, it is preferable to add sulfate sulfate in the position near a methane fermentation tank. When there are few easily decomposable substances in waste water, it is preferable to add sulfate sulfate in a shear side, for example, an acid production tank. This is because when the sulfate root is consumed during decomposition of the easily decomposable substance, the effect of promoting degradation of terephthalic acid and paratoluic acid is lowered.

Also in a biphasic treatment apparatus, since sulfuric acid is added as sulfuric acid, since a pH will fall, when a pH adjustment tank is formed, it is preferable to add sulfuric acid in the front end.

The conditions of the anaerobic treatment vary depending on the method employed, but the anaerobic sludge concentration is 10,000 to 40,000 mg-VSS / L, and the load is 1 to 15 kg It is preferable to set it as BOD / m <3> * day and CODcr load 2-30 kg-CODcr / m <3> * day.

The anaerobic treated water can be further provided for aerobic treatment such as activated sludge treatment or other post treatment in order to decompose the remaining organic matter. According to the present invention, in the anaerobic treatment, the hardly decomposable terephthalic acid can be efficiently decomposed and removed by the anaerobic treatment. Even after carrying out the anaerobic treatment of the waste water, the load of the anaerobic treatment is reduced, and the treatment cost is reduced.

[Treatment of Hydrogen Sulfide Gas]

In the present invention, since the sulfuric acid root is added to the terephthalic acid-containing waste water in the above-mentioned amount, methane fermentation is not inhibited, and the generation of hydrogen sulfide gas is suppressed, and the decomposition efficiency of terephthalic acid is increased. When a small amount of hydrogen sulfide gas is generated, biodesulfurization treatment of the hydrogen sulfide gas may be performed. In general, in the biological desulfurization treatment, when the hydrogen sulfide concentration in the target gas is changed, sulfur oxide bacteria do not grow stably and the treatment becomes unstable. In the present invention, since the concentration of hydrogen sulfide in the exhaust gas is stabilized by adding a predetermined amount of sulfate root to the waste water, biodesulfurization treatment is performed stably.

The biodesulfurization treatment of the hydrogen sulfide-containing exhaust gas is preferably carried out by the method described in Japanese Patent No. 3235131. In this method, a hydrogen sulfide-containing exhaust gas is brought into contact with a cleaning liquid, for example, a treatment liquid for aerobic microbial oxidation of an organic substance to absorb hydrogen sulfide in the gas, and the obtained absorption liquid is subjected to aerobic microbial oxidation to oxidize sulfur oxide bacteria. By action, hydrogen sulfide is oxidized to sulfate ions or elemental sulfur to be harmless.

According to this method, desulfurization treatment can be carried out at a high desulfurization rate without lowering the content of methane gas, efficiently and at low cost, and without generating new wastewater with desulfurization. However, the treatment method of hydrogen sulfide gas is not limited to this method at all.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The quality of the raw water subjected to anaerobic treatment in Examples and Comparative Examples is as follows.

Raw water quality

COD _Cr : 4050 ㎎ / ℓ

Terephthalic Acid Concentration: 400 ㎎ / ℓ

Paratoluic acid concentration: 620 mg / l

SO ₄ ^{2 -} Concentration: 30-40 mg / l

pH: 10

[Examples 1-3, Comparative Examples 1, 2]

Raw water was treated by a two-phase anaerobic treatment apparatus equipped with an acid production tank and an EGSB methane fermentation tank. The raw water was introduced into an acid generating tank and treated, and then treated with a methane fermentation tank. A portion of the treated water of the methane fermentation tank was circulated to the acid generating tank, and the remainder was taken out as treated water.

The specifications and treatment conditions of each tank are as follows, and the raw water flow rate is 5 ℓ / day.

Acid generator tank capacity: 0.5 ℓ

Acid generator pH: 6.5 to 7.5

Methane fermentation tank capacity: 2 ℓ

Methane Fermenter pH: 7-8

Methane Fermenter Sludge Concentration: 67 g / ℓ as VSS

Methane Fermenter Temperature: 35 ℃

Amount of circulation water from the methane fermentation tank to the acid production tank: 1 Q (= 5 L / day) was circulated with respect to the raw water flow rate Q (= 5 L / day).

In Comparative Example 1, sulfuric acid was not added to the raw water. Examples 1 to 3 and Comparative Example 2, SO ₄ ² shown in Table 1 in a set of acid generated ^{shear-sulfate} was added to the raw water to the added amount. Sulfuric acid was added as an aqueous 20 mass% solution. Since pH decreased by addition of sulfuric acid, pH was adjusted by adding sodium hydroxide after addition of sulfuric acid. By addition of sulfuric acid, the SO ₄ ^{2 -} content in the waste water provided for the anaerobic treatment, including SO ₄ ^{2 -} contained in the raw water, was as shown in Table 1.

Table 1 shows the water quality of the treated water obtained by the anaerobic treatment, the activity of the sludge obtained from the treatment result, and the presence or absence of generation of hydrogen sulfide gas.

According to the present invention, it can be seen from Table 1 that the highly degradable terephthalic acid-containing waste water can be efficiently anaerobic treated to obtain high-quality treated water.

Although this invention was demonstrated in detail using the specific aspect, 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.

In addition, this application is based on the JP Patent application (patent application 2010-224001) of an application on October 1, 2010, The whole is taken in into consideration.

Claims (11)

A method for anaerobic treatment of wastewater containing terephthalic acid, wherein the sulfuric acid root is added to the wastewater so that the concentration of sulfate ions in the anaerobic treated water is 5 to 200 mg / L. The anaerobic treatment method of terephthalic acid-containing wastewater. The method of claim 1,
Sulfate root is added to the waste water so that content of the sulfate root in the said wastewater may be 60-400 mg / L, The anaerobic treatment method of the terephthalic acid containing wastewater characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The anaerobic treatment method of terephthalic acid containing waste water which adds sulfuric acid root to the said waste water so that content of sulfate root may be 10 mass% or more with respect to terephthalic acid in the waste water. The method according to any one of claims 1 to 3,
The said wastewater contains 50-2000 mg / L of terephthalic acid, The anaerobic treatment method of terephthalic acid containing wastewater characterized by the above-mentioned. The method according to any one of claims 1 to 4,
Said wastewater further contains paratoluic acid, The anaerobic treatment method of terephthalic acid containing wastewater. 6. The method according to any one of claims 1 to 5,
In order to add the sulfate sulfate to the drainage water, at least one selected from the group consisting of sulfuric acid, iron sulfate (I), iron sulfate (II), polyiron sulfate, ammonium sulfate, aluminum sulfate, sodium sulfate, and potassium sulfate is added to the drainage. The anaerobic treatment method of terephthalic acid containing wastewater characterized by the addition. An apparatus for anaerobic treatment of wastewater containing terephthalic acid, comprising: means for adding sulfate root to the wastewater so that the concentration of sulfate ions in the anaerobic treated water is 5 to 200 mg / l. Processing unit. The method of claim 7, wherein
The anaerobic treatment apparatus for terephthalic acid containing wastewater characterized by including a means for adding sulfate sulfate to the wastewater so that the content of sulfate root in the wastewater becomes 60 to 400 mg / L. 9. The method according to claim 7 or 8,
A sulfate anaerobic treatment apparatus for terephthalic acid-containing wastewater, wherein the sulfuric acid root is added to the wastewater such that the content of sulfate root is 10% by mass or more relative to the terephthalic acid in the wastewater. 10. The method according to any one of claims 7 to 9,
The said wastewater contains 50-2000 mg / L of terephthalic acid, The anaerobic treatment apparatus of terephthalic acid containing wastewater characterized by the above-mentioned. 11. The method according to any one of claims 7 to 10,
The wastewater further contains paratoluic acid, wherein the anaerobic treatment apparatus for terephthalic acid-containing wastewater.