SU1638121A1 - Process for purifying waste waters of dye finishing manufacture - Google Patents

Abstract

The invention relates to methods for treating wastewater by coagulation and can be used in the treatment of wastewater from the dyeing and finishing industry of light industry. In order to increase the degree of purification of wastewater from dyes, additional removal of chloride ion, reduce reagent consumption, eliminate secondary contamination with salts of mineral acids, wastewater is treated with sludge obtained by treating the eluates of Na-cationaries of this production with soda-alkaline mixture with the molar ratio of NaOH: Na2C03 is 0, bb-2.00, and the consumption of NaOH 1.83-22.20 mol per mole, the precipitate formed is separated and neutralized with flue gases. The method provides for the removal of dyes at 85-95% in comparison with the known no more than 77%, as well as the removal of chlorides by 80% in the absence of purification in the known method, 1 C. f-ly, 3 tab. SS (L

Description

The invention relates to methods for treating wastewater by coagulation and can be used in the treatment of wastewater from the dyeing and finishing industry of light industry.

The purpose of the invention is additional purification of wastewater from chlorides, reduction of reagent consumption, elimination of secondary contamination with salts of mineral acids with an increase in the degree of purification from dyes.

For carrying out the process, the water treatment eluates, which are part of the wastewater of the dyeing and finishing plants, are treated with soda-alkaline mixture with molar ratios NaOH: Na C03 0, bb-2.0 to give a solid precipitate, which is then filtered, and the filtrate is neutralized hydrochloric acid and sent for the regeneration of Na-cationite filters. The resulting precipitate of calcium salts and magnesium is repulped in a solution alkali-i chi and metered as a coagulant into colored wastewater to a pH of 11.5-12.0. As a result of such wastewater treatment with the obtained precipitates, a high degree of wastewater purification from chlorides and dyes is observed. To eliminate secondary pollutants, the neutralization of wastewater is carried out with waste gases from the boiler house.

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PRI me R 1. In samples of eluates (200 ml each) of the Na-cationization plant, which are part of the dyeing and finishing production, and containing, g / l: Ca2 + 2.1; Mg24 1.0, C1 52.4, various amounts of soda-alkaline solution are introduced with a certain ratio

The sediments of hardness salts are hydrated, therefore, for processability of their subsequent dosing into wastewater, repulpation in alkali solutions

NaOH and Na2C03. After administration, reagent-1Q is carried out at a T: W ratio of 1: 3-4,

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the sample is stirred for 10 min, the precipitated precipitate is filtered, the filtrate is analyzed for Ca and Mg

The results of the treatment of Na-cationization eluates with soda-alkaline water are presented in Table 1.

Thus, depending on the ratio of calcium and magnesium in the initial eluate, it is possible to choose the optimal ratio of soda and alkali for minimum consumption of soda-alkaline mixture and complete precipitation of hardness salts.

The degree of magnesium deposition depends on the amount of alkali introduced and reaches 100% at a molar ratio of NaOH / Mg2 of 1.84-2.2.

With a ratio of NaOH / Mg24 It84, even with an excess of soda, there is no complete precipitation of magnesium, which is what determines the residual hardness.

The consumption of soda required for complete precipitation of calcium depends on the amount of alkali remaining after magnesium binding.

The most optimal ratio of alkali and soda in soda-alkaline mixture is 0.66-2.0.

PRI mme R 2. The precipitate of hardness salts, obtained by performing example 1, is spilled at T: W 1: 3 in a solution of NaOH with a concentration of 2.0; 3.0; 3.5; 3.8J 4, О M. The resulting D5 suspension is introduced into the colored wastewater with an initial dye content of 56 mg / l to a pH of 11.5-12.0. After stirring for 10 minutes, the solutions are filtered and the filtrate is analyzed for dye content (Table 3).

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in which the fluidity of the resulting pulp is observed for dosage.

From the obtained results it follows that in the case of using sludge for wastewater treatment, the degree of removal of dyes reaches 85-95%, while by a known method it does not exceed 77%, the degree of purification of wastewater from chlorides is 80, L% and in a known method chlorine wastewater is not treated.

Claims (2)

Claim 1. Waste water treatment method highly finishing production, including coagulant treatment, separation of precipitate formed by filtration and neutralization of the filtrate, which is different in order to further purify wastewater from chloridione, reduce reagent consumption, eliminate secondary contamination with mineral acid salts as the degree of purification increases from dyes, a precipitate formed during the treatment of the eluates of Na-cationization of water of a given production with a soda-alkaline mixture with a molar ratio of NaOH: Na2C03 0.66-2.00 and the consumption house NaOH 1.83-2.20 mol per 1 mol Mg 2-f in the initial eluate, and the neutralization of wastewater is carried out by flue gases. 2. Method pop. 1, characterized in that the treatment of wastewater is carried out with a suspension obtained by repulping the precipitate in a solution of NaOH with a concentration of 3-3.8 mol / l at T: W 1: 3-4, and the suspension is introduced into wastewater to a pH of 11.5-12.9. Specific examples of the implementation of the known and proposed methods for the treatment of wastewater from dyes are presented in Tables 2 and 3. The sediments of hardness salts are hydrated, therefore, for processability of their subsequent dosing into wastewater, repulpation in alkali solutions carried out at a ratio of T: W 1: 3-4, five 0 five 0 five five 0 in which the fluidity of the resulting pulp is observed for dosage. From the obtained results it follows that in case of using sludge for wastewater treatment, the degree of removal of dyes reaches 85-95%, while by a known method it does not exceed 77%, the degree of wastewater purification from chlorides is 80, L%, and In a known method, waste water from chlorides is not treated. Claim 1. Wastewater treatment method of dyeing and finishing plants, including treatment with coagulant, separating the formed precipitate by filtration and neutralizing the filtrate, characterized in that, in order to further purify wastewater from chloride, reduce the consumption of reagents, eliminate secondary pollution with salt mineral acids with an increase in the degree of purification from dyes, as a coagulant, a precipitate is used that is formed when treating the eluates of Na-cationization of water of a given soda-alkali production a mixture with a molar ratio of NaOH: Na2C03 of 0.66-2.00 and a consumption of NaOH of 1.83-2.20 mol per 1 mol Mg 2-f in the initial eluate, and the neutralization of wastewater is carried out by flue gases. 2. Method pop.1, characterized in that the treatment of wastewater is carried out with a suspension obtained by repulping the precipitate in an NaOH solution with a concentration of 3-3.8 mol / l at T: W 1: 3-4, and the suspension is introduced into wastewater to a pH of 11.5-12.9. Table 1 pH of CB The concentration of dyes in SV, mg / l Degree of cleaning,% from the edge of the chlorinators | 7,656 10,842 11,229 11.58 11.76 11.85 12.03 12.43 80.6 80.6 80.6 80.6 80.6 80.6 80.6 80.6