JPH06182362A - Treatment of dyeing waste water - Google Patents

Abstract

PURPOSE:To provide a novel waste water treatment method treating dyeing waste water containing a dye hardly decolored such as a reactive dye using a Fenton's reagent method, excellent in decoloration effect and the removal of COD and capable of also improving economical efficiency. CONSTITUTION:Dyeing waste water is adjusted to pH <=3 by hydrogen peroxide using an iron salt as a catalyst to be subjected to oxidation treatment in an oxidizing tank 1 and the treated water is adjusted to pH=6-7 in a pH adjusting tank 7 and, thereafter, an aluminum flocculant and a coagulant are added to the treated water in a chemicals mixing tank 8. Subsequently, a high-molecular flocculant is added to a flocculation tank 9 to perform solid-liquid separation by flocculation and sedimentation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating dyeing wastewater containing a difficult-to-decolorize dye such as a reactive dye, and more particularly to improvement of a method for treating dyeing wastewater using the Fenton's reagent method.

[0002]

As is well known, in the Fenton reagent method,
After oxidizing and decomposing organic matter in wastewater by the strong oxidizing power of hydrogen peroxide under iron salt catalyst, flocculating agent is added by adding coagulant such as slaked lime to the oxidation reaction liquid and solid-liquid separation. Therefore, it exhibits an excellent effect on the decolorization treatment of dyeing wastewater such as azo type and anthraquinone type.

However, the decolorizing effect of the dyeing wastewater containing a reactive dye such as a phthalocyanine type dye has not been sufficiently exhibited. In addition, there is a drawback in that a large amount of chemicals such as hydrogen peroxide, iron salt, and slaked lime is required, and further, a large amount of sludge is generated, which is a problem from the economical aspect.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an object thereof is to treat a dyeing wastewater containing a dye that is difficult to be decolorized such as a reactive dye. As a method, it is excellent in decolorizing effect and COD removing effect,
At the same time, it provides a new wastewater treatment method that can improve economic efficiency.

[0005]

According to the present invention, however, the dyeing wastewater is oxidized with hydrogen peroxide using iron salt as a catalyst at a pH ≦ 3 in an oxidation tank 1, and then the treatment liquid is subjected to a pH adjusting tank. After adjusting the pH to 6 to 7 in step 7, an aluminum-based coagulant and a coagulant are added to the treatment liquid in the chemical mixing tank 8, and then a polymer coagulant is added in the coagulating tank 9 to coagulate. The present invention relates to a dyeing wastewater treatment method characterized by separating and removing solid-liquid by precipitation.

[0006]

In the above construction, the dyeing wastewater is limited to be oxidized with hydrogen peroxide at pH≤3 using an iron salt as a catalyst because an effective reaction of the oxidation treatment does not occur unless such conditions are met. Further, the reason why the pH of the oxidized liquid is adjusted to 6 to 7 in the pH adjusting tank 7 is to enhance the functions of the coagulant and the coagulant as pretreatment.
This is because if the pH of the H adjusting tank 7 is alkaline, it reacts with the aggregating agent and it becomes impossible to form flocs.

Examples of the iron salt include anhydrous salts of ferrous sulfate, ferric sulfate, ferrous sulfate and ferrous sulfate, and hydrous salts thereof. Examples of the aluminum-based coagulant include polyaluminum chloride (PAC), sulfuric acid band, etc., examples of the coagulant include cationic polyamine resin, and examples of the polymer coagulant include anionic polyacrylamide. Etc. can be illustrated.

Further, the main function of the flocculant in the above constitution is to form flocs, which are used while stirring the inside of the tank, and the stirring speed at this time is preferably high. On the other hand, the main action of the polymer flocculant is to grow flocs, and the stirring speed at this time is preferably slower than that of the flocculant. Also, the main function of the cationic coagulant is to react with the anions in the dye component, and the coagulant used in combination and the polymer coagulant function together to separate the dyeing wastewater by solid-liquid separation by coagulation precipitation. can do.

Further, the present invention is effective for decolorizing a hardly decolorizing dye such as a reactive dye contained in the dyeing wastewater, but the present invention is not limited to this, and is not limited to the dyeing wastewater. It is not necessary to contain a difficult-to-decolorize dye such as a reactive dye.

The conventional method and the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a conventional wastewater treatment method by the Fenton reagent method. In such a treatment method, first, the dyeing wastewater is sent to the oxidation tank 1 and is oxidized with hydrogen peroxide using an iron salt as a catalyst. At this time, the pH of the oxidation tank 1 is adjusted to pH ≦ 3 by an inorganic acid such as sulfuric acid, and is stirred at a sufficient speed by the stirring propeller 5. Next, flocculation tank 2
Add a flocculant such as slaked lime. At this time, p in the coagulation tank 2
H is pH = 8 to 10 due to alkali such as caustic soda
Has been adjusted to. Next, after solid-liquid separation in the settling tank 3, sludge is discarded by the pump 6, and the supernatant liquid is neutralized in the neutralization tank 4.
After adjusting the pH to 7, the product is discharged.

FIG. 2 is a diagram showing a wastewater treatment method according to the present invention. According to the invention, the dyeing wastewater is first treated in the oxidation tank 1
Then, oxidation treatment is performed by the Fenton reagent method. Then pH
In the adjusting tank 7, pH = 6 with alkali such as caustic soda.
Adjust to 7 and add aluminum coagulant and coagulant in the chemical mixing tank 8. Next, a polymer flocculant is added in the flocculation tank 9, and solid-liquid separation is performed in the precipitation tank 3, sludge is discarded by the pump 6, and the supernatant liquid is discharged after adjusting it to pH = 7.

Hereinafter, examples of the present invention and comparative examples by a conventional method will be described.

Example 1 As a dye, 2 pieces of Remazol Green 6B manufactured by Hoechst Co. were used.
The phthalocyanine-based dyeing waste liquid containing 00 mg / l was subjected to wastewater treatment under the following conditions. That is, hydrogen peroxide 400 mg / l, ferrous sulfate 7 as Fenton's reagent
Using 80 mg / l of water salt, the oxidation conditions are as follows: oxidation temperature 26 to 30 ° C., oxidation time 1.0 hour, pH of oxidation tank
It was set to 2.7. In addition, polyaluminum chloride was used as an aluminum-based coagulant at 300 mg / l, a water-soluble polyamine resin as a coagulant was 50 to 300 mg / l, and polyacrylamide (anion) as a polymer coagulant was 1 mg / l. The following operation was performed under the above conditions. That is, immediately after the completion of the oxidation treatment in the oxidation tank 1, the pH is adjusted to 6.3 with NaOH in the pH adjustment tank 7, the aluminum-based coagulant and the coagulant are added in the chemical mixing tank 8, and then in the coagulation tank 9. A polymer flocculant was added and the solid-liquid was precipitated and separated in the precipitation tank 3. Then, the transmittance and COD of the supernatant were measured. However, the transmittance of the stock solution is 0% and the COD is 110 mg / l. Also,
The transmittance is based on the Macbeth CE3000W spectrophotometer (5
00 nm) and the COD is JIS-K 0102.
(Oxygen consumption by potassium permanganate at 100 ° C.) method.

For comparison with Example 1, wastewater treatment by the conventional method was carried out under the following conditions.

Comparative Example 1 That is, as a dye, Remazol Green 6B manufactured by Hoechst Co., Ltd.
1000m of hydrogen peroxide as a Fenton's reagent for a phthalocyanine dye waste solution containing 200mg / l of
g / l, ferrous sulfate heptahydrate 400 mg / l, and the oxidation conditions are as follows: oxidation temperature 30 to 35 ° C., oxidation time 2.5.
Time, pH of the oxidation tank was set to 3.0. The following operation was performed under the above conditions. That is, immediately after the completion of the oxidation treatment in the oxidation tank 1, the pH was adjusted to 10 with NaOH in the coagulation tank 2, and after the solid-liquid was precipitated and separated in the precipitation tank 3, the transmittance and COD of the supernatant liquid were measured. The measurement was performed in the same manner as in 1. However, the transmittance of the stock solution is 0% and the COD is 110 mg / l.

The measurement results of transmittance and COD in Example 1 and Comparative Example 1 obtained as described above are as shown in Table 1.

[0015]

[Table 1]

[0016]

Example 2 As a dye, Levafix Turquoise Blue E-BA (Levafix Tur manufactured by Bayer Co., Ltd.)
quiose Blue E-BA) 200 mg / l
The phthalocyanine-based dyeing waste liquid contained was subjected to the following conditions. That is, hydrogen peroxide 400 mg / l and ferrous sulfate heptahydrate 80 mg / l were used as the Fenton's reagent, and the oxidation conditions were as follows: oxidation temperature 26 to 30 ° C., oxidation time 1.0 hour, oxidation tank pH = 2. It was set to 7. Also, 300 mg / l of polyaluminum chloride as an aluminum-based coagulant,
50-300 mg of water-soluble polyamine resin as a coagulant
/ L, and polyacrylamide (anion) as a polymer flocculant was 1 mg / l. The same operation as in Example 1 was carried out under the above conditions, and the transmittance and C
The OD was measured. However, the transmittance of the stock solution is 0%, and COD
Is 110 mg / l.

For comparison with Example 2, wastewater treatment by the conventional method was carried out under the following conditions.

Comparative Example 2 That is, as a dye, Levafix Turquoise Blue E-BA (Levafix) manufactured by Bayer Co., Ltd.
Turquoise Blue E-BA) 200m
For phthalocyanine dye waste liquid containing g / l,
Hydrogen peroxide (1000 mg / l) and ferrous sulfate heptahydrate (400 mg / l) were used as Fenton's reagent, and the oxidation conditions were as follows: oxidation temperature 30 to 35 ° C., oxidation time 1 hour, and oxidation tank pH = 3.0. . Under the conditions as described above, Comparative Example 1
The same operation as above is carried out, and the transmittance and CO
D was measured. However, the transmittance of the stock solution is 0% and the COD is 110 mg / l.

The measurement results of transmittance and COD in Example 2 and Comparative Example 2 obtained as described above are as shown in Table 2.

[0019]

[Table 2]

[0020]

[Example 3] As a dye, Drimalene Navy X-RBL (Drimarene Navy X- manufactured by Sand Co., Ltd.)
RBL) was applied to an azo dyeing waste liquid containing 200 mg / l under the following conditions. That is, hydrogen peroxide 400 mg / l, ferrous sulfate heptahydrate 80 as Fenton's reagent
Using mg / l, the oxidation conditions are oxidation temperature 26 to 3
The temperature was 0 ° C., the oxidation time was 1.0 hour, and the pH of the oxidation tank was 2.7. Moreover, polyaluminum chloride is used as an aluminum-based coagulant.
0 mg / l, 50% water-soluble polyamine resin as a coagulant
˜300 mg / l, and polyacrylamide (anion) as a polymer flocculant was 1 mg / l. Under the above conditions, the same operation as in Example 1 was performed, and the transmittance and COD of the supernatant liquid were measured. However, the transmittance of the stock solution was 11% and the COD was 96 mg / l.

For comparison with Example 3, wastewater treatment by the conventional method was carried out under the following conditions.

[Comparative Example 3] That is, as a dye, Drimalene Navy X-RBL (Drimarene Navy) manufactured by Sand Co.
X-RBL) to 200 mg / l of the azo dye waste solution, hydrogen peroxide 800 as Fenton's reagent
1. mg / l, ferrous sulfate heptahydrate 500 mg / l were used, and the oxidation conditions were an oxidation temperature of 30 to 35 ° C. and an oxidation time of 2.
The pH of the oxidation tank was set to 3.0 for 5 hours. Under the above conditions, the same operation as in Comparative Example 1 was performed, and the transmittance and COD of the supernatant liquid were measured. However, the transmittance of the stock solution was 11% and the COD was 96 mg / l.

Table 3 shows the results of measuring the transmittance and COD in Example 3 and Comparative Example 3 obtained as described above.

[0023]

[Table 3]

[0024]

Example 4 A mixed waste liquid of various reactive dyes containing 124 mg / l of Levafix dye manufactured by Bayer, 57 mg / l of Cibacron dye manufactured by Ciba-Geigy, and 20 mg / l of Diamira dye manufactured by Mitsubishi Kasei Hoechst as dyes. On the other hand, it was performed under the following conditions. That is, hydrogen peroxide 200 mg / l, ferrous sulfate heptahydrate 80 as Fenton's reagent
Using mg / l, the oxidation conditions are oxidation temperature 26 to 3
The temperature was 0 ° C., the oxidation time was 1.0 hour, and the pH of the oxidation tank was 2.7. Moreover, polyaluminum chloride is used as an aluminum-based coagulant.
0 mg / l, 50% water-soluble polyamine resin as a coagulant
˜300 mg / l, and polyacrylamide (anion) as a polymer flocculant was 1 mg / l. Under the above conditions, the same operation as in Example 1 was performed, and the transmittance and COD of the supernatant liquid were measured. However, the transmittance of the stock solution is 36% and the COD is 43 mg / l.

For comparison with Example 4, wastewater treatment by the conventional method was carried out under the following conditions.

[Comparative Example 4] Mixing of various reactive dyes containing 124 mg / l of Levafix dye manufactured by Bayer, 57 mg / l of Cibacron dye manufactured by Ciba-Geigy, and 20 mg / l of Diamira dye manufactured by Mitsubishi Kasei Hoechst as dyes. The waste liquid was treated under the following conditions. That is, hydrogen peroxide 800 mg / l and ferrous sulfate heptahydrate 500 mg / l were used as Fenton's reagent, and the oxidation conditions were as follows: oxidation temperature 30 to 35 ° C., oxidation time 2.5 hours, oxidation tank pH =
It was set to 3.0. Under the above conditions, the same operation as in Comparative Example 1 was performed, and the transmittance and COD of the supernatant liquid were measured. However, the stock solution has a transmittance of 36% and a COD of 43.
mg / l.

Table 4 shows the measurement results of the transmittance and COD in Example 4 and Comparative Example 4 obtained as described above.

[0027]

[Table 4]

As is clear from the results of the above embodiment,
INDUSTRIAL APPLICABILITY The present invention exerts a sufficient effect on the decolorization of dyeing wastewater which contains a reactive dye such as a phthalocyanine type and is difficult to decolor, and also exerts an excellent effect on COD removal.
Furthermore, in the case of azo dyeing wastewater, the above-mentioned effect is exhibited with a smaller amount of chemicals, and even with the mixed waste liquid of various reactive dyes, the decolorizing effect and the COD removing effect are exhibited with a smaller amount of chemicals as compared with the conventional method.

[0029]

As described above, according to the present invention,
Even for a dyeing wastewater containing a difficult-to-decolorize dye such as a reactive dye, it exhibits an excellent effect in decolorization and COD removal as compared with the conventional dyeing wastewater treatment method using the Fenton's reagent method. Furthermore, since the amount of chemicals used can be reduced,
It is also extremely economical.

[0030]

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional wastewater treatment method by the Fenton reagent method.

FIG. 2 is a diagram showing a wastewater treatment method according to the present invention.

[Explanation of symbols]

 1 Oxidation tank 2 Coagulation tank 3 Precipitation tank 4 Neutralization tank 5 Stirring propeller 6 Pump 7 pH adjusting tank 8 Chemical mixing tank 9 Coagulation tank

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsuo Sawada 262 Sou Sou, Miyazu City, Kyoto Prefecture Gunze Co., Ltd.

Claims (1)

[Claims] 1. Dyeing wastewater is oxidized with hydrogen peroxide using iron salt as a catalyst at a pH ≦ 3 in an oxidation tank 1, and then the treated liquid is adjusted to pH = 6 to 7 in a pH adjusting tank 7. After the adjustment, an aluminum-based coagulant and a coagulant are added to the treatment liquid in the chemical mixing tank 8, and then a polymer coagulant is added in the coagulation tank 9 to separate and remove the solid liquid by coagulation precipitation. A method for treating dyeing wastewater, characterized by: