RU2225846C2 - Method of water purification - Google Patents

Abstract

FIELD: preparation of drinking water and purification of sewage. SUBSTANCE: the invention presents a method of water purification and may be used for preparation of potable water and sewage purification by ozonization with the subsequent coagulation. For implementation of the method water is treated with ozone, accelerating it together with an ozone-air mixture up to a supersonic speed with consequent retardation of the mixture till a subsonic speed at transition of the mixture through a compression shock. A coagulating agent is fed in the mixing zone and after retardation of the mixture it is once again accelerated and a flocculating agent is introduced. Then water is discharged in a basin and settled. A preferable version of implementation of the method provides for a concentration of an ozone-air mixture is equal to 0.35- 0.65. EFFECT: the method ensures reduction of duration of the process of ozonization, coagulation, flocculation and simplifies procedure of water purification with the help of ozone. 2 cl, 1 dwg

Description

The invention relates to the preparation of drinking water with significant contamination of the source water, wastewater treatment by ozonation, followed by coagulation and can be used in wastewater treatment plants and plants using ozone as an oxidizing agent.

A known method and equipment [1] for the preparation of drinking water. Through the piping system, the ozone-air mixture is supplied to contact pools equipped with a distribution system of porous ceramic or titanium disk elements. After ozonation, water is sent to a mixer, where it is treated with chlorine, mixed with a coagulant (aluminum sulfate or oxychloride) and a flocculant. This is followed by the traditional two-stage clarification in sedimentation tanks and filters loaded with quartz sand.

The main disadvantage of the method and its implementing equipment is the long cleaning time, the availability of additional equipment for mixing the coagulant, flocculant and the introduction of additional chlorine, because coagulation proceeds at the highest rate at certain threshold concentrations of anions [2]. Combining the processes of ozonation and coagulation is impossible, because the precipitate clogs the pores of the dish-shaped elements and the flow of the ozone-air mixture stops.

Closest to the proposed technical solution is a method of ozonation of a liquid according to the patent of the Russian Federation No. 2034799 (application 4870887/26 from 07.19.90).

In this method, the mixing of purified water with an ozone-air mixture is carried out in a multi-barrel ejector by accelerating it to a supersonic speed when the mixture passes through a shock wave. The liquid in a supersonic two-phase mixture is distributed in a thin film, with intensive stirring. The efficiency of water treatment with ozone increases many times. But when using this method, with preliminary ozonation of waters having a color more than 50 ° on a platinum-cobalt scale, additional treatment of water with coagulated and flocculation is necessary.

The purpose of the invention is to reduce the time of the processes of ozonation and coagulation with speculation, significantly reduce the production area and range of equipment used.

This is based on the fact that when organizing ozonation according to RF patent No. 2034799, the precipitate formed does not penetrate the mixing part and does not clog the holes of the mixing head of the ejector.

The objective of the invention is achieved by the fact that, according to the known method of purifying water with ozone by treating it in a multi-barrel ejector, the gas-liquid mixture is accelerated to supersonic speed, followed by braking to subsonic speed when the mixture passes through the shock wave, simultaneously the coagulant is fed into the liquid and gas mixing zone, and after braking the mixture, it is again dispersed and a flocculant is introduced, then the water is poured into the tank for sludge and filtering. This method is most effective at a relative volumetric concentration of a gas-liquid mixture of 0.35-0.65.

New in the proposed method is the combination of the processes of ozonation and coagulation with flocculation in one spatio-temporal continuum. This has become possible since coagulants began to be used everywhere: aluminum sulfate and oxychloride [1], as well as on the basis of titanium - the destructive effects of ozone, which are not observed. Further, upon dissolution of ozone in water, anions (OH ^- ) are formed along with other radicals [3], which significantly reduces the coagulation time [2].

The proposed solution is illustrated in the drawing, which shows the installation with an ejector, in which a nozzle with a number of shafts of more than ten is used.

The installation consists of an ejector body 1, partubes for the supply of treated water 2 and ozone 3, a mixing chamber 4, a cylindrical section 5 of the ejector, a diffuser 6 and a nozzle 7. To introduce the coagulant there is a metering tank 8, a shut-off valve 9 and a supply pipe 10. For input the flocculant is a container 11, a shut-off valve 12 and a supply pipe 13.

The ejector is docked with the contact chamber 14 having partitions 15 and 16.

The method is implemented as follows.

Through the pipe 2 and the nozzle 7, the treated water enters the mixing chamber 4 of the ejector, where it “captures” the gas entering through the pipe 3, and enters the cylindrical section 5.

The coagulant from the dispensing tank 8, when the shut-off valve 9 is opened, is piped 10 to the zone of initial contact of the liquid and gas, in the area of their outflow from the nozzle 7. At a volumetric flow rate of 10 · 10 ⁴ cm ³ / s, the addition of coagulant with a volume of 10 cm ³ / c does not affect the physical picture of the gas-liquid flow.

The ejector is used as a mixer and the vacuum in the mixing chamber can be reduced, i.e. increased coefficient of ejection K> 1 · 10 ^-3 . At pressure P _rail mixture leaving the ejector is less than 1.4 × 10 ^-1 MPa in a cylindrical portion of a two-phase gas-liquid mixture is supersonic.

In the diffuser, the static pressure increases sharply and the flow becomes subsonic. The change in pressure occurs spasmodically over a very short length, i.e. in compaction surges.

The dissolution of a coagulant with a volume of 10 cm ³ in a liquid with a volume of 10 · 10 ⁴ cm ³ in a few seconds is a rather complicated task, but easily solved using the above method. The fluid in the supersonic mixture is distributed in a thin film that is highly turbulized. In the diffuser, in the shock waves, the pressure and the rate of mass transfer sharply increase, and a liquid with a uniformly distributed coagulant in volume enters the input of zone A of the contact chamber.

In zone A, intensive mixing of the liquid for hydrolysis of coagulants occurs, at the maximum rate of formation of micelles and primary sol aggregates, as well as the formation of sufficiently large rapidly settling flakes.

In zone B, fluid mixing sharply decreases, and the formation of rapidly settling flakes and their precipitation continue.

To accelerate the further coagulation process, a flocculant is introduced into zone B located in the tank 11, when the shut-off valve 12 is opened, through the supply pipe 13.

Zone B is organized in the contact chamber by reducing its cross section by the partition 15. In a narrow section, the liquid is accelerated and flocculant is introduced, and conditions favorable for flocculation are created in zone B.

The separated gas is removed from the upper part of the contact chamber, and the liquid is drained from the lower part into the reservoir for sedimentation and filtration.

The advantage of the proposed method compared to the known ones is to expand the range of the processed source water (color on the Pt-Co scale to 50-100 °), and therefore the expansion of the market for equipment that implements this method.

In addition, the distribution of coagulant in the volume of liquid is very uniform, which means that the consumption of coagulant is significantly reduced; intermediate removal of sludge (drawing, zone B), allows to reduce flocculant consumption, eliminates the equipment for mixing coagulant and flocculant, reduces the processing time of water, significantly reduces production area.

Sources of information

1. Khramenkov S.V., Koverga A.V., Blagova O.E. Experience and prospects for the use of ozonation in the Moscow water supply // Water supply and dignity. equipment. 2000, No. 1 (p. 6-8).

2. Taube P.R., Baranova A.G. Chemistry and Microbiology of water. - M.: Higher School, 1983, p. 127.

3. Bo D., Gerasimov G.N. The practice of ozini in the processing of injection water // Water supply and dignity. equipment. 2000, No. 1, p. 26-29.

Claims (2)

1. A method of purifying water by treating with ozone in a multi-barrel ejector, comprising accelerating water with an ozone-air mixture to a supersonic speed, followed by braking the mixture to subsonic speed when the mixture passes through a shock wave, characterized in that a coagulant is introduced into the mixing zone, and after the mixture is braked flocculant is again dispersed and introduced, then the water is poured into the tank and defended. 2. The method of water purification according to claim 1, characterized in that the volume concentration of the ozone-air mixture is 0.35-0.65.

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