SU1263639A1 - Method of treating petroleum-containing waste water - Google Patents

Abstract

A method for cleaning oil-containing sewage water, including flotation in the presence of a mineral sorbent, characterized in that, in order to increase the degree of water purification from emulsified oil products, mineralized sorbent with expanded dispersion of 6.2-1.2 mm is used as a mineral sorbent 9: 1 - 7: 3 closed pores and an open pore size of 20-300 nm, which is entered. d t in conjunction with dispersible air.

Description

The invention relates to methods for purifying water from petroleum and petroleum products and can be used to purify wastewater and process water from enterprises of machine-building, metallurgical, oil-producing, oil refining and other industries, where in the process of production stable, highly dispersed, stable oil-in-water emulsions are formed. - Increasing the degree of water purification from emulsified oil products, intensifying the process of emulsion separation. An increase in the efficiency of emulsion separation according to the proposed method is achieved as a result of the fact that the porous particles of hydrophobic perlite at the places where air bubbles enter the surface change the interface geometry, thus forming a three-phase wetting perimeter that has portions of a much greater curvature than the surface curvature of the bubbles . The surface tension at the air – liquid interface largely depends on the surface curvature. In this case, the surface tension in places where the bubble with the perlite particle is smaller than on the bubble. The presence on the surface of the bubble of areas with three-phase wetting perimeters having reduced surface tension contributes to an increase in the efficiency of capture and retention of hydrophobic emulsion droplets. Thus, perlite exhibits a qualitatively new property — the ability to lower the surface tension at the air – liquid interface in the zone of a three-phase wetting perimeter. The method is carried out as follows. The experiments were carried out on a laboratory and peller flotation machine of the brand FL-130V. I l emulsion machine wt. la MS-20 with a concentration of 1000 mg / l, stabilized by non-ionic surfactants -syntanol DS-1 O (10 mg / p) prepared using an ultrasonic disperser, is floated in the presence of hydrophobized perlite introduced into the emulsion by various methods. The average size of the emulsified oil droplets is 2 µm. A perm uta of a different fractional composition is used with a different ratio of open and closed pores and different sizes of open pores. In all experiments, perlite is used, which is hydrophobized with 1% aqueous emulsion of polyethylsiloxane. Air flow 2 l / mic. Flotation time 15 min. Example 1. Perlite (100 mg) is introduced into the emulsion together with air drawn in by the impeller of the flotation machine. Fractional composition of perlite 0.2-0.6 mm; the ratio of open and closed pores is 8.5: 1.5; open pore size of 20 - 300 mm. After the purification process, the residual oil content in water is 2 mg, i.e. the purification effect is 99.8%. Example 2. The experiment was carried out similarly to Example 1. Perlite was applied to the surface of the emulsion and flotation treatment was carried out. The residual oil content is 25 mg / l. Example 3 Perlite is introduced into the lower part of the working volume of the flotation cell and at the same time the flotation treatment is carried out. In this case, perlite is introduced separately from dispersible air. Residual oil content of 20 mg / l. To confirm that the increase in the degree of wastewater treatment offered by the method occurs only as a result of using the adsorption properties of hydrophobic perlite, the results of purification were compared separately only by flotation without pearlite, only by adsorption without flotation and the proposed method. As shown by the results of experiments, the use of only flotation emulsion processing reduces the residual oil content to 12080 mg / l; the post-floatation treatment of the emulsion with hydrophobic expanded perlite in an amount of 100 mg / l makes it possible to achieve a decrease in the oil content in water from 120-80 to 60-30 mg / l; The proposed method allows to reduce the oil content from 1000 to 2 mg / l, -i-.e. by-. to increase the degree of purification by a factor of 30–13 compared with the two processes carried out separately - flotation and adsorption.

3 263639

To determine the effect of the dispersion composition of the injected pearlite, the ratio of open and closed pores in it, as well as the size of open pores and selection of the boundary values of the claimed parameters, experiments were performed similar to Example I, the results of which are summarized in the table.

The proposed method

0.2 8.5: 1.5

10: 0 9: 1

6.5: 1.51.5-2

8: 2, 4.5-8

7: 310-15

6: 425-28

5: 545-55

Known method

The average

1-400 35-65 value

0.05-1.4 8.0: 2.0

From the presented results, it can be seen that the highest degree of purification of 2-15 mg / l is achieved when using perlite with a dispersion of 0.151.2 mm, which has an open ratio of

and closed pores 9-1 - 7-3 and the size of open pores 20 - 300 them.

In the case of the use of perlite dispersion of more than 0.15 mm and with a pore size of less than 20 nm efficiency

cleaning is reduced, since such perlite particles do not provide a sufficiently effective change in the surface tension in the zone of the three-phase wetting perimeter, and pores smaller than 20 nm cannot absorb larger oil droplets.

The lower limit of the dispersion of perlite 1.2 mm is limited by the fact that the rate of emergence of particles larger than 1.2 mm in size differs significantly from the rate of ascent of air bubbles, resulting in the separation of perlite particles from air bubbles, i.e. the destruction of flotation complexes, a piece of perlite - an air bubble. The feasibility of using a 9: 1 to 7: 3 ratio of open and closed pores is justified by the fact that the rate of emergence of pearlite particles with a ratio of open and closed pores greater than 9: 1 and less than 7: 3 is much different from the rate of bubbling of bubbles, as a result, the air bubble-particle of perlite is destroyed in the process of flotation, in connection with which the degree of water purification is reduced. The table also shows the data on water purification by lime method, according to which a mixture of perlite of different fractional composition is used and water purification is carried out by using only the adsorption properties of perlite (perlite was in contact with the emulsion by mixing it in the emulsion volume). From the presented data it is clear that the proposed method provides an increase in the degree of water purification by 23-32 times in comparison with the known method.

Claims (1)

METHOD FOR CLEANING OIL-CONTAINING WASTE WATERS, including flotation in the presence of mineral sorbent, characterized in that, in order to increase the degree of purification of water from emulsified oil products, gtsrofobizovanny expanded perlite with a dispersion of 0.2-1.2 mm with a ratio of open and closed pores 9: 1 - 7: 3 and an open pore size of 20-300 nm, which vvo-. together with dispersible air. >