SU1310343A1 - Method for removing nonionogenic surface-active substances from waste water - Google Patents

Abstract

. The invention relates to the field of wastewater treatment from non-ionic surfactants (NSA) and is used to clean up the degreasing drains in the iron and steel industry, mechanical engineering, metalworking and refining industries. The method allows to increase the degree of purification from. Nonionic surfactants and reduce cleaning time. To carry out the process, Na-montmorillonite is introduced into waste water containing nonionic surfactants and sodium phosphates in suspension in an amount corresponding to the ratio of nonionic surfactants and sorbent 0.2-0.4, mixed for 30 minutes, then calcium oxide is added to in the amount of milk of lime in an amount corresponding to the ratio of sodium phosphate and calcium oxide concentrations of 0.7-1.8 is stirred for 2 minutes and carbon dioxide is passed through the resulting suspension for 1-5 minutes until pH reaches 7. The resulting precipitate is separated. 1 hp f-ly, 1 tab. sl 00 so 00

Description

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The invention relates to wastewater treatment methods and can be used to clean sewage from non-ionic surfactants in the production of cold-rolled pipes, tin, sheet and hardware in ferrous metallurgy, engineering, metalworking and oil refining industries. (industrial after metal degreasing contains nonionic surfactants of the type OP and sodium phosphates, which makes them difficult to clean together).

The purpose of the invention is to increase the degree of purification of wastewater containing sodium phosphate, and to reduce the cleaning time.

Na-montmorillonite is used as a sorbent, and calcium oxide and carbon dioxide are successively introduced into the wastewater. In this case, the ratio of the concentrations of SCHAV and Na-montmorillonite is. 0.2-0.4, and the ratio of phosphate to calcium oxide concentrations is 0.7-1.8.

The introduction of Na-montmorillonite in an amount corresponding to the ratio of concentrations of nonionic surfactants and sorbent 0, i., Does not allow for effective purification from nonionic surfactants due to insufficient effect of sorption.

Increasing the consumption of Ma-montmorillonite to amounts corresponding to the ratio of the concentrations of nonionic surfactants and sorbent less than 0.2, does not improve the degree of purification and leads to an increase in the amount of solid phase to be removed.

The introduction of calcium oxide into the treated wastewater provides an increase in the degree of purification from surfactants by reducing the peptization of the sorbent particles and, consequently, increasing the efficiency of separating the solid phase from sorbed surfactants.

The presence of calcium oxide in the effluent after sorption of the surfactant also contributes to the transition of Ka-montmorillonite, which has high sorption properties, to the calcium form, which has good sedimentation characteristics, which allows accelerating the phase separation process and increasing the efficiency of the cleaning process.

The introduction of calcium oxide in an amount corresponding to the ratio of phosphate and CaO 1.8 concentrations is not enough to remove the peptizing agent.

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action of sodium phosphates — colloidal sorbent particles with surfactants adsorbed on them, falling into purified water, significantly lower

degree of purification from surfactants.

Increasing the added portion of calcium oxide to amounts corresponding to the ratio of phosphate concentrations and CaO 0.7, does not provide a significant increase in the degree of purification, while the amount of solids to be removed increases, which negatively affects the duration of the purification process.

The treatment with calcium oxide makes it possible to aggregate and precipitate the colloidal particles of the sorbent and thereby purify the water from the surfactant. However, a loose, flooded sediment is formed,

occupying a large volume.

Passing carbon dioxide through the precipitate improves its structure, increases its density and filterability, while the pH of the clarified

water is reduced to neutral values, which reduces the cost of filtering the precipitate and avoids the costs associated with neutralizing the purified water.

The method is carried out as follows.

Na-montmorillonite is introduced into waste water containing nonionic surfactants and sodium phosphates (for example, washing Hbie water after metal degreasing) in the form of a 20% suspension in the effluent and a sorbent of 0.2-0. 4 and stirred for 30 minutes (I stage). After that, calcium oxide is introduced in the form of milk of lime in an amount corresponding to the ratio of sodium phosphate concentrations in the effluent and calcium oxide 0.7-1.8, stirred for 2 minutes and carbon dioxide passed through the suspension for 1-5 minutes until reaching pH is D1L 7 (Stage II). The precipitate is separated in a known manner.

for example, by centrifuging, resulting in purified water.

Sequential injection into wastewaters containing NPA.V and sodium phosphates, Na-montmorillonite, calcium oxide and carbon dioxide allows to obtain purified water with a content of nonionic surfactants 4-5 mg / l and pH 7, which makes it possible to use it again without additional processing.

Example. The wastewater undergoing purification has a composition similar to the wash water after metal degreasing on metallurgical and hardware enterprises: nonionic surfactants (OP-7) 100 mg / l; 500 mg / l.

Na-montmorillonite is added to wastewater in an amount of 1 l in an amount of 100-1000 mg (as a 20% suspension) and stirred for 30 minutes, then calcium oxide (as 5% milk of lime) is added. ) in the amount of 170-1000 mg and stirred for 2 minutes, after which carbon dioxide is passed through the drains for 2 minutes.

The effluent treated in this manner is placed in a centrifuge where the separation of the solid phase from the clarified water is carried out. The content of OP-7 in purified water is determined spectrophotometrically on Specord UV-Vis. The results obtained in comparison with the data by a known method are shown in the table.

As follows from the table, the sequential introduction of Na-montmorillonite in an amount corresponding to a ratio of phosphate and calcium oxide concentrations of 0.7-1.8, and the subsequent introduction of carbon dioxide allow

1.00 0.40 0.25

The proposed method 86 42. 44 390 70 2 68 390 72 3 69 390

to obtain purified water with a residual content of nonionic surfactants in water of 4-5 mg / l.

The advantage of the proposed method is to increase the degree of purification of phosphate-containing waters from nonionic surfactants and spent sorbent, which allows the recycled water to be reused and to prevent the discharge of pollutants polluting the environment, and, in addition, to reduce the consumption of sorbent and increase the speed of the cleaning .

Claims (2)

Invention Formula one . The method of purification of wastewater from non-ionic surfactants, including the introduction of a sorbent, mixing and separation of sediment, characterized in that, in order to increase the degree of purification of wastewater containing sodium phosphates, and reduce the time of purification, Na-montmorillonite is used as a sorbent and wastewater is additionally treated with calcium oxide and carbon dioxide. 2. The POP.1 method, characterized in that the ratio of the concentrations of non-ionic surfactants and montmorillonite is 0.2-0.4, and that of sodium phosphates and calcium oxide is 0.7-1.8. 1.28 49 1.28 7 1.28 5 Order 1859/21 Circulation 852Under VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d.A / 5 Production and printing company, Uzhgorod, Projecto st., 4 Table continuation