RU2361818C1 - Method of purifying oily water effluents - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: proposed method involves feeding oily water into a reservoir through a zone of saturating water with air. The oily water effluents are fed by a pressure jet through an air volume, which is under pressure higher than atmospheric pressure, with subsequent floatation purification of the water from impurities at atmospheric pressure in a zone, separated from the zone of saturation with air. After the said floatation purification, the purified water undergoes repeated floatation purification from impurities at pressure less than atmospheric pressure in a zone, separated from the zone of previous floatation purification. In the water and air jet formed in the volume of water, adjacent to the zone of saturation with air, air is additionally injected from the zone saturating effluent water with air. The invention is aimed at increasing the degree of aeration of effluent water while increasing uniformity of aeration of a volume of oily water effluents with fine air bubbles. The method provides for floatation of fine particles.

EFFECT: increased degree of purification of oily water from floating impurities.

1 dwg

Description

The invention relates to wastewater treatment and can be used to isolate various impurities from them, for example, petroleum products.

A known method of purification of oily wastewater, including their supply to the tank under the surface of the wastewater in the tank with a flooded jet under pressure, followed by flotation treatment of water from impurities, in an area isolated from the zone of saturation of wastewater with air (SU No. 996332, MKI C02F 1 / 00, 1981).

The disadvantage of this solution is the unsatisfactory degree of purification of oily wastewater due to the low degree of aeration.

There is also a method of purification of oily wastewater, including their supply to the tank through the zone of water saturation with air, for which oily wastewater is supplied by jet under pressure, through a volume of air under pressure greater than atmospheric, followed by flotation purification of water from impurities at atmospheric pressure in the zone isolated from the zone of wastewater saturation with air (SU No. 1632949, MKI C02F 1/40, B01D 17/035, 1991).

The disadvantage of this solution is also the unsatisfactory degree of purification of oily wastewater from finely dispersed impurities uniformly distributed over their volume due to the insufficiently uniform distribution of air bubbles over the volume of water and their dispersion.

The problem to which the claimed solution is directed is to provide the ability to purify oily wastewater from fine impurities uniformly distributed over their volume.

The technical result achieved in solving this problem is expressed in the fact that the degree of aeration of wastewater is increased while the uniformity of aeration of the volume of oil-containing wastewater with finely dispersed air bubbles increases, which makes it possible to float finely dispersed particles of impurities and thereby allows to increase the degree of purification of oil-containing water from free (undissolved) impurities to a level of at least 99% of their initial content.

The problem is solved in that the method of purification of oily wastewater, including their supply to the tank through the zone of water saturation with air, for which oily wastewater is supplied by jet under pressure, through a volume of air under pressure greater than atmospheric, followed by flotation treatment of water from impurities, at atmospheric pressure in an area isolated from the zone of saturation of wastewater with air, characterized in that after flotation purification of water from impurities at atmospheric pressure, the purified water They are subjected to repeated flotation purification from impurities, at a pressure lower than atmospheric pressure, in an area isolated from the zone of the previous flotation purification of water from impurities, in addition, air from the zone is additionally ejected into a water-air stream formed in the volume of water adjacent to their saturation zone with air saturation of wastewater with air.

A comparative analysis of the features of the claimed solution with the features of the prototype and analogues indicates the conformity of the claimed solution to the criterion of "novelty."

The search results showed that the claimed invention does not follow explicitly from the prior art for the specialist, since the influence of the transformations provided for by the essential features of the claimed invention is not revealed from the prior art determined by the applicant, which provides a positive reaction to achieve a technical result - to increase the degree of aeration of wastewater while increasing the uniformity of aeration of the volume of oily wastewater with fine air bubbles, h This makes it possible to flotate finely dispersed particles of impurities and, due to this, allows to bring the degree of purification of oil-containing water from free (undissolved) impurities to a level of at least 99% of their initial content.

Therefore, the claimed invention meets the condition of "inventive step".

Moreover, the features of the distinguishing part of the claims provide a solution to a set of functional tasks:

The signs "... after flotation purification of water from impurities at atmospheric pressure, the purified water is subjected to repeated flotation purification of impurities at a pressure lower than atmospheric" initiate and support the process of separation of air dissolved in them at elevated air pressure and partially released at atmospheric pressure pressure (at the previous stage of flotation treatment).

Signs indicating the isolation of the repeated flotation treatment zone from the zone preceding the flotation water purification of impurities, realized at atmospheric pressure, ensure the efficiency of the repeated (vacuum) cleaning stage and reduce the load on the vacuum equipment used at this stage.

The signs "into the water-air stream formed in the volume of water adjacent to the zone of their saturation with air, additionally eject the air" can increase the degree of saturation of water with air.

Signs indicating that air is ejected “from the wastewater saturation zone with air” simplify the organization of the procedure for supplying an additional volume of air and increase the efficiency of the process of saturating water with air, since air under pressure corresponding to the pressure of the air used to saturate the wastewater is ejected.

The drawing schematically shows a device for implementing the inventive method.

The drawings show a tank 1, nozzle nozzles 2, a casing 3 with an edge 4, a chipper 5 with an edge 6, a gap 7 between the walls of a chipper 5 and a tank 1, an additional tank 8 with a vertical chipper 9, dividing it into a floating 10 and accumulating 11 compartments . In addition, the outlet pipes 12 and 13 of the tank 1, the branch pipes 14 and 15 of the additional tank 8, the drain pipes 16 of the tank 1, the additional tank 8, the flotation compartment 10 and the chipper 5, the supply pipe 17 of the tank 1, the air pipes 18 and 19, respectively, are shown reservoir 1 and additional reservoir 8, distributor 20, pipeline 21, confuser nozzles 22 with channels 23. In addition, the surface of the liquid 24, the water-air stream 25, the foam layer 26 containing flotated impurities are shown.

The listed elements and parts do not differ in design and materials from known elements and parts used for similar purposes, with similar requirements for strength, performance, etc.

The claimed method is as follows.

The operating parameters in the installation are brought to face value, namely:

the tank is filled with water (it is advisable to use purified water at the start-up stage), create a pressure above atmospheric pressure up to 0.1 MPa in the cavity of the casing 3 (in the zone of saturation of water with air), for example, by connecting the pipe 18 to a source of compressed air - compressor (in the drawings shown), in addition, in the air cavity of the additional tank 8 create a vacuum up to 0.03-0.05 MPa (for example, by connecting to a vacuum pump, not shown in the drawings). Then start the flow of water to be treated. The purified water is poured out of the nozzle nozzle 2 at a high speed, in the form of a jet under a pressure of 0.8-1.0 MPa, down through an air layer (located in the casing 3 above the surface of the liquid 24 already in the tank 1). In the process of moving through the air layer, the jet of purified water captures a large amount of air, which, under the influence of the jet, is entrained in the volume of liquid, where it disperses into small bubbles and partially dissolves in the volume of water below the surface of the liquid 24. As a result, air-to-water is formed in the volume of treated water jet 25, extending deep into the liquid from its surface. The depth of penetration of the jet 25 and the dimensions of its cross section are determined by the flow parameters of the treated water. Interacting with the outlet openings of the confuser nozzles 22, the air-water jet 25, due to the ejection effect, “draws” an additional volume of air (through channels 23) from the zone of water saturation with air into the liquid volume. Further, the purified water, saturated with bubbles of dispersed air and the air dissolved in them, is forced out through the zone between the bottom of the tank 1 and the edge 4 of the casing 3, where the jet energy is extinguished, into the gap between the walls of the casing 3 and the chipper 5. In this case, the rest of the device the flow of water takes a calm character, convective currents are absent. Under these conditions, an intensive unimpeded separation of impurity particles occurs in the entire volume of the liquid being cleaned (particles of oil products flotate with air bubbles, i.e., particle-bubble aggregates that float to the surface due to their low specific gravity). The result is a foam layer 26 containing flotted impurities, which is removed in a known manner through the outlet pipes 13. Clean water is lowered to the bottom of the tank 1 through the gap 7, where it is discharged through the pipe 12. The chipper 5 prevents impurities from entering the purified water during its downward movement , to the nozzle 12 of the tank 1. Next, the liquid after the first stage of cleaning is fed through a pipe 21 to the distributor 20 of the additional tank 8. The water pressure in the distributor 20 of the floatation compartment 10 is determined by the sum of the pressure ozduha above the water surface and the hydrostatic pressure in the tank 8, its value is below atmospheric pressure and admission of water through conduit 21 into the rail 20 is released small bubbles due to dissolved air solubility reduction ratio due to the pressure reduction. The exit of the water-air flow from the distributor 20 to the bottom of the flotation compartment 10 causes flotation cleaning in the second stage with fine bubbles. In addition, when lifting the water-air mixture in compartment 10, the hydrostatic pressure in the water-air flow decreases, which leads to an increase in fine air mass due to the continuous release of bubbles from the volume of the liquid being cleaned due to a decrease in hydrostatic pressure. The average sizes of air bubbles in the second stage are many times smaller than the average sizes of air bubbles released in the first stage of purification. Their number per unit volume is much larger with increasing flow height and uniform distribution over the cross section. Under these conditions, intensive flotation of particles of oil products remaining after the first stage of purification occurs with the formation of particle-bubble aggregates that float to the surface due to their low specific gravity. As a result, a layer of foam 26 is formed on the surface of the additional tank 8 containing flotted impurities, which is periodically removed in a known manner through the branch pipes 14. The purified water, as a denser medium, is carried down to the bottom of the additional tank 8, while the vertical baffle 9 prevents ingress impurities in the purified water in the process of its movement down to the branch pipe 15 of the tank 8. For periodic cleaning of the bottom of the tanks 1, 8 and the chipper 5 from accumulating sludge I use t drainage pipes 16.

The aeration coefficient in the proposed method as a result of creating favorable conditions for saturation of the cleaned liquid with air is 10-12. The final degree of purification of water processed in the proposed method reaches 99%, which indicates the appropriateness of the application of the proposed method.

Claims (1)

A method for purifying oil-containing wastewater, including supplying it to a tank through a zone of water saturation with air, for which oil-containing wastewater is supplied by a stream under pressure, through a volume of air under high atmospheric pressure, followed by flotation treatment of water from impurities at atmospheric pressure in the zone, isolated from the zone of saturation of wastewater with air, characterized in that after flotation treatment of water from impurities at atmospheric pressure, the treated water is subjected to repeated flotation treatment about impurity at a pressure less than atmospheric pressure, in an area isolated from the flotation zone prior water purification from impurities in addition, a water-air jet generated in a volume of water adjacent to the zone of aeration, the air further ejected from the wastewater saturation zone air.