KR810000769B1 - Process for treating waste water containing polyvinyl alcohol - Google Patents

Abstract

Textile finishing waste water contg. polyvinyl alcohol (I) is treated with 0.1-0.2% H3BO3 or borax. In the presence of colored matter, such as C particles, inorg. salts are added with H2BO3 or borax at pH 4-7. Starch in waste water is removed enzymically at 70≰. The formed I-H3BO3 complex can be reused in the textile sizing treatment at pH 4-8 and >70≰ Thus, waste water contg. 0.80% I was mixed with 0.12% borax and 0.9% Na2SO4, pH adjusted to 9, the supernatant liq. from the flocculated sludge enriched by an enzyme, to give an effluent contg. 0.05% borax and 0.3% Na2SO4. The I-H3BO3 flocs are removed at pH 9.

Description

Method of treating wastewater containing polyvinyl alcohol

The figure is a graph which shows the change of the peptizing speed of P.V.A film by temperature and pH.

Conventional activated sludge method is most commonly used for the treatment of wastewater containing organic substances. However, it is very difficult to decompose and process polyvinyl alcohol (hereinafter referred to as PVA) in this manner. One wastewater is treated with boric acid or borax in the presence of inorganic salts such as forget-me-not, so that PVA is collected and recovered by flocculation in a gel form as a boric acid compound. However, in this case, the remaining mother liquor from which P.V.A has been separated and recovered still contains a small amount of borate together with mu salts, and these salts are within the pollution limits. Even if it is hard, it cannot be discharged to nature, and discharge | release of this is also great loss in nature.

In the first aspect of the present invention, various wastewaters containing PVA are treated by the above-described method, and the PVA is separated and recovered, and the mother liquor is repeated for various uses, for example, the fabrication of fabrics. It is a control method of the wastewater containing PVA characterized by using.

PVA is flocculated at room temperature by adding 0.1-0.2% of boric acid or borax, and 0.3-0.6% of inorganic salts such as manganese to the wastewater containing PVA, and adjusting the pH to 8-10 with an oxide or hydroxide of alkali metal or alkaline earth metal. do. When the organic matter in the wastewater is P.V.A alone, the mother liquor after P.V.A separation contains 0.05 to 0.08% borate (as boron) and 0.6 to 1.0% inorganic salts. When this P.V.A recovered mother liquor is used, for example, for the fabrication of fabrics, the small amount of flocculant can be finished as about 30% of tap water, with an addition of 0.3-0.6% is sufficient. However, in this case, since the degree of deterioration is deteriorated to some extent, the pH is slightly increased, and the temperature is raised to 70 ° C. or higher to perform the call. Thereby, the objective can be fully achieved. The recovered P.V.A boric acid compound can be widely used for suitable applications such as fiber processing, paper processing, adhesives, and the like. This method is characterized by being economical and especially not completely pollution free. However, in the method of coagulating and separating P.V.A as a boric acid compound, when the wastewater contains solid impurities other than P.V.A, this may interfere and may cause a re-use of the recovered P.V.A. For example, the effluent treatment wastewater of PVA-containing fabrics may become cloudy due to carbides produced by carbonization of the wool of the fabric in the woolen process, and may be colored. The PVA recovered therein is impure and colored. have. Therefore, according to the method described above, when P.V.A aggregates, carbides and salts are absorbed at the same time, so the purity of P.V.A is low, so that it is difficult to use it as a high-quality product in addition to using it as a soil improving agent.

In order to remedy such drawbacks and recover high purity PVA boric acid compounds, in the second invention of the present invention, boric acid or borax and inorganic dyes such as manganese sulfate and ammonium sulfate are added to the wastewater to reduce the pH to 70 as PH 4-7. After heating to more than C, by cooling the pH to room temperature adjusted to 8 to 10, the colorless and high purity PVA boric acid compound is separated and recovered without containing carbide and unnecessary salts. Even when the wastewater contains only P.V.A, there is an advantage that the salt content of the obtained P.V.A boric acid compound is reduced. It is considered that P.V.A is sufficiently peptized by heating from mild acid to high temperature, and P.V.A is gelled to high purity without absorbing solids such as boric acid compounds and excess salts in cooling. At this time, solids such as carbides become precipitates and settle at the bottom of the container, and are easily separated from the mother liquor. Therefore, the mother liquor can be used repeatedly for various purposes as in the first method. Next, starch may be mixed with P.V.A in addition to P.V.A as an organic substance in wastewater containing P.V.A. Therefore, in the third invention of the present invention, the mother liquor from which the PVA is recovered according to the first or second invention described above is neutralized, and 0.1 to 0.2% of an enzyme inhibitor is added, followed by 5-15 minutes at 70 ° C. or higher. Glycosylation or hydrolysis with acid. If solid impurities such as carbides are present, they can be removed before or after saccharification. This prevents the obstacle due to the presence of starch when the P.V.A recovered mother liquor is used, for example, for the fabrication of fabrics. In other words, the organic matter in the waste water achieves the object with a small amount of the same flocculant as in the case of P.V.A alone. When the starch is not saccharified and the viscosity is not lowered, the starch accumulates during continuous use and prevents dropping, and it is difficult to coagulate and segregate the P.V.A in recovering P.V.A from the wastewater.

As described above, the recovered P.V.A boric acid compound according to the present invention can be widely used for a suitable use as P.V.A. However, when it is used as an artificial arc in crops, it is necessary to consider the effect of boric acid powder. Therefore, in the present invention, the processing temperature in this case is higher than usual, and the pH is adjusted to 4 to 8 to determine the firing at 70 ° C or higher. This can bring about the same effect as in the case of the new P.V.A.

Example 1

To wastewater containing 0.80% of PVA (average degree of polymerization 1700, 88%), 0.12% of borax and 0.9% of forget-me-not were added to the calcined circuit as PH 9 and stirred at room temperature for 10 minutes to give PVA as a boric acid compound. Aggregate separation. The composition after drying was P.V.A 80.2% and boric acid (as B) 10.3% CaO 0.20%. The mother liquor was PH 7 and 0.12% of bioreactor enzyme bioreactor (Nagase Industrial Co., Ltd.) was added to reinforce the T / C brood at 97 to 100 ° C. It was. Borax boron 0.05% and forget-me-not 0.3% were added to the waste-treated wastewater, and it was treated with calcination circuit PH 9 for 15 minutes at room temperature. As a result, P.V.A boric acid compound was coagulated and separated as in the first time.

Example 2

0.12% boric acid and 0.7% ammonium sulfate were added to a T / C brood-treated wastewater containing 0.75% PVA and 0.4% starch, heat-treated at about 98 ° C for 30 seconds, and cooled to room temperature with a calcination circuit of PH 8 Colorless PVA was recovered by aggregation as a boric acid compound. The composition after drying was 83.7% P.V.A, 12.4% boric acid (as B), 0.04% CaO 0.09%, and the presence of impurities such as carbides was hardly seen.

Example 3

After leaving the mother liquor in Example 2 to remove the precipitate, 0.1% of the enzyme inhibitor biotex was added, and the starch was saccharified by heating at 80 DEG C for 10 minutes at PH 7. The concentration of starch in mother liquor was reduced to 0.06%. The protection effect of the fabric using this mother liquor was the same as in Example 1.

Example 4

2 g / L of concentrated sulfuric acid was added to the mother liquor of Example 2 to boil for 5 minutes to hydrolyze the starch, and when the precipitate was removed, the starch concentration of the mother liquor decreased to 0.05%.

Example 5

Using a foaming agent made of 60% P.V.A boric acid compound recovered in Example 2 and 40% of starch, the woven processing of the woven fabric was performed at 80 ° C. The result was the same as the process at 50 degreeC by commercially available arc, and the thread trimming test of the product was as follows.

Collection P.V.A A Product B Product

45 single thread T ₆₅ / C ₃₆ number of rounds 2664 3231 1470

100% Tetron Cutoff 3506 4800 2557

Claims (1)

A boron compound selected from the group consisting of boric acid and borax is added to the wastewater containing PVA in the presence of inorganic salts such as manganese, and the solution is then heated to 70 ° C. or higher at pH 4-7 and then to pH To 8-10, and then cooled to room temperature to separate high-purity PVA containing no solid impurities such as carbides contained in the wastewater and excess salts as a complex with a boric acid compound. Treatment method of wastewater containing.

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