RU2657903C1 - Method of introducing coagulant in the water treatment process - Google Patents

Abstract

FIELD: water and air purification technology.

SUBSTANCE: invention can be used in water treatment and water purification for purification and disinfection of drinking and waste water. Method of introducing the coagulant includes feeding coagulant (2) to the purified water, in pipeline (1), activating the coagulant by mixing it in water. At the same time, uniformly distributed turbulent jets of water are created by beam distributor (3) in the zone of coagulant injection into the flow along its cross section, with respect to them, a coagulant is supplied with the possibility of at least partial self-trapping by these jets and the movement of the formed mixture to next zone (4), where in this mixture turbulent jets of water with a coagulant are crushed on lattice (5) into smaller analogous formations with increasing self-trapping by turbulent water jets of coagulant (6), forming active mixing of the coagulant in water.

EFFECT: method ensures the use of the energy of the water flow in the pipeline by means of which an effective mixing of the coagulant solution with the treated water at low flow rates of 20–50 cm/s without additional activation in conditions of non-compulsory dissolution of coagulant in water.

1 cl, 1 dwg

Description

The present invention relates to water treatment and water purification in processes that use coagulation and saturation with liquid and gaseous components for the purification and disinfection of drinking and waste water in pipelines and pools.

Currently, natural and wastewater treatment is carried out in accordance with the recommendations given in:

- SNiP 2.04.02-84, Water supply. External networks and facilities. - M. Stroyizdat, 1985.S. 136,

- SNiP 2.04.03-85, Sewerage. External networks and facilities. - M. SITP Gosstroy of the USSR, 1986.P. 72.

There are other known methods of water purification given in the works:

- Babenkov E.D. Water purification by coagulants. - M. Science. 1977, p. 356,

- Guide to the properties and methods of analysis and purification of water. Kola L.A. and others, part I and part II. - Kiev: Naukova Dumka. 1980.S. 1206,

- Kola L.A. Theoretical foundations and water conditioning technology. - Kiev. Naukova Dumka. 1983, p. 528,

- Reference book (designer). Sewerage of populated areas and industrial enterprises. Ed. V.N. Samokhina. - M .: Stroyizdat. 1981. S. 639;

- Handbook for the treatment of natural and waste water. L.L. Paal, I.Ya. Karu, H.A. Mender, B.N. Repin. - M .: Higher. school., 1994.S. 336,

- Lutsenko G.N. Tsvetkova A.I., Sverdlov N.Sh. Physico-chemical treatment of urban wastewater. - M .: Stroyizdat, 1984, S. 89,

- Malkin V.P., Ivanov P.V. Wastewater treatment of heavy metals. / Methods and facilities for local treatment of industrial wastewater. - M.: Stroyizdat, 1983.P. 79,

- Malkin V.P. Technological aspects of the treatment of industrial waste containing heavy metal ions. - Irkutsk: Publishing House of Irkutsk University, 1991.P. 63.

At the same time, they are guided by the following document: “Instructions on the use of water purification technology for contact illuminators using optimal mixing modes of the coagulant with water” / Approved by order of the Ministry of Housing and Communal Services of the RSFSR of October 4, 1986 No. 431, Department of Scientific and Technical Information AKH, Moscow 1986.

According to these guidelines, one of the ways to intensify contact clarification of water is to improve the process of mixing coagulants with water. The data on the design of devices for the distribution of reagents in the treated water and hydraulic coagulant mixers with water are presented. So, water treatment of surface sources with high color, low suspension content and low temperature for a significant part of the year (water of lakes, reservoirs, rivers of the northern, northwestern and some other regions of the country) is usually carried out by contact coagulation of the suspension in a filter medium. This technology is implemented using single-stage water purification schemes on contact clarifiers and two-stage filtering schemes with contact prefilters and filters.

At the same time, one of the ways to intensify contact clarification technology is to improve the process of introducing and mixing the coagulant with water. This process of mixing the coagulant with water is usually built in two stages: 1) mixing the coagulant with water in order to quickly and evenly distribute it in the volume of treated water; 2) subsequent intensive mixing of water, which contributes to the formation of cereal embryos and affects the further formation of deposits in the filter charge. Ensuring the rapid distribution of coagulant in the volume of water treated in the first stage allows to obtain coagulant savings of 10-20% or to achieve a higher effect of water purification with the same dose of coagulant. This is achieved by making full use of the intermediate products of hydrolysis of the coagulant and enhancing the process of mutual coagulation of the products of hydrolysis of the coagulant and particles of contaminants. The optimal intensity of mixing depends on the quality of the treated water (turbidity, color, temperature). The selection and refinement of the optimal mixing modes is determined experimentally for each specific water source. Thus, it is well known that in industrial water treatment, the basic is the deposition / coagulation / filtration process, described in detail in a significant number of publications. Moreover, the coagulation process requires active mixing (mechanically, circulating the system, ultrasound, vortex type pumps, etc.) for the required time. To accelerate the coagulation process, a coagulant solution (for example, aluminum sulfate) is introduced into the system, and the system is further mixed for a predetermined time. Then the system is pumped to a clarifier, where it is left to stand for several hours, as a result of which two phases are formed: one - lower - sediment, and upper - water sludge. Each part is then subjected to analysis. Thus, the known methods of introducing a coagulant into a water treatment process are based on the active mixing of the coagulant with water, in particular using ultrasound.

The known process of “Mixing coagulants with water. Electronic resource. Access mode to the resource: "(see http://fortisgroup.livejournal.com/6021.html - free. Publ. 13.10.2012). According to him, during water treatment, the introduction of a coagulant is a process of mixing the coagulant with water. When considering the process of mixing the coagulant with water, two stages are distinguished: 1) mixing the coagulant with water in order to quickly and evenly distribute it in the volume of treated water; 2) subsequent intensive mixing of water, which contributes to the formation of cereal embryos and affects the further formation of deposits in the filter charge.

Ensuring the rapid distribution of coagulant in the volume of water treated in the first stage allows to obtain coagulant savings of 10-20% or to achieve a higher effect of water purification with the same dose of coagulant. This is achieved by making full use of the intermediate products of hydrolysis of the coagulant and enhancing the process of mutual coagulation of the products of hydrolysis of the coagulant and particles of contaminants.

The change in the intensity of mixing after introducing the coagulant into the water in the second stage makes it possible to affect the physicochemical properties of the resulting flakes (size, density, strength, and adhesion), which leads to an increase in the dirt capacity of the filter load and an increase in the duration of the filter cycle by 30-40%. The optimal intensity of mixing depends on the quality of the treated water (turbidity, color, temperature). The selection and clarification of the optimal mixing modes are usually set experimentally for each specific water source.

Based on the foregoing, it should be noted that when coagulating water impurities, it is necessary to force a quick and uniform distribution of reagents in its volume. This is believed to provide maximum contact of impurity particles with intermediate products of coagulant hydrolysis (which exist for a short period of time), since hydrolysis, polymerization and adsorption processes occur, for example, within 1 s.

Perekinetic (molecular kinetic) coagulation ends when the particles reach a size of 1 ... 10 microns, which practically coincides with the period of rapid distribution of coagulant in the treated water in the mixers. However, there is also an ineffective mixing of the coagulant with water, which leads to an overspending of the coagulant and a low agglomeration rate of water impurities at a given dose of the reagent. This is due to the forced mixing of the coagulant with water, when a large mass of water and its increased flow artificially creates a chaotic formation of turbulent eddies of the water layers in which the coagulant is dissolved. Moreover, this dissolution occurs more forcefully than in vivo. Therefore, it is necessary to create the optimal mode of operation of the mixers, in which the coagulant would come into contact with the maximum number of particles of water impurities before the hydrolysis and polymerization reactions end. For uniform and quick mixing of reagents with water, they should be introduced in the areas of greatest turbulence of the stream at several points of its cross section. To mix the reagent with water, it is necessary to provide reagent distributors (input devices for reagents, for example, coagulants) that ensure their fast uniform distribution in the feed channel or pipeline, and mixers, where the subsequent intensive mixing of the introduced reagents with the treated water takes place. Reagent distributors are recommended in the form of perforated tubular systems or inserts in the pipeline, which are local resistance. The pressure loss in the pipeline when installing these devices, respectively, is assumed to be 0.1 ... 0.2 and 0.2 ... 0.3 m.

The reagents are mixed with the treated water in mixing devices (Venturi nozzles, orifice plates), tubular mixers or in special mixer constructions that must satisfy the requirement for quick and complete mixing of the reagents with the entire mass of water (i.e., the residence time of water is 1 ... 3 min .). Mixers are divided into hydraulic and mechanical. Among the hydraulic mixers that have proven themselves best in practice are: corridor type (with vertical or horizontal movement of water); perforated, cloisonne with flow separation, vertical (vortex). The choice of mixer type is justified by the layout of the water treatment plant, taking into account its performance and method of water treatment, as well as structural and technological considerations.

As a prototype, an invention is selected relating to water treatment and water treatment, namely, to a method for treating drinking and wastewater in open pools and pipelines (Patent No. 215858 91, IPC C02F 1/36, C02F 1/52, C02F 1/72, publ. April 27, 2001). This method includes feeding the reagent into the purified water located in the pipeline. In this case, acoustic vibrations are excited in the liquid being cleaned and at the same time a vacuum zone is created due to the passage of the water being cleaned through the sonar emitter. Thus, they create a forced active mixing of the coagulant with water.

However, it has a significant drawback. The introduction of a coagulant for water treatment requires increased energy consumption, the use of additional devices. In this case, a significant reduction in the consumption of coagulant does not occur. An increase in the intensity of forced mixing in the coagulant water by exciting acoustic vibrations in the liquid with the simultaneous formation of a vacuum zone in it when using a sonar emitter leads to an active increase in the input of the coagulant into the water. Obviously, it is not possible to use such a method of introducing coagulant during water treatment when low velocities (for example, 0.2 ... 0.5 m / s) of water flow take place without additional activation of mixing of the coagulant in water. This is especially unacceptable when water treatment should be done in the suburbs, in rural villages.

The objective of the present invention is to provide a new method for introducing a coagulant in the water treatment process with the achievement of the following technical result, namely, mixing solutions of a chemical agent in the treated water (coagulant, flocculant) at low flow velocities (0.2 ... 0.5 m / s) without additional activation under conditions of natural non-compulsory dissolution of the coagulant in water.

The problem is solved as follows. A known method for introducing a coagulant in a water treatment process comprises supplying a coagulant and / or an oxidizing reagent to the purified water located in the pipeline and activating the coagulant in water by mixing it in water.

According to the present invention, the energy of the water flow in the pipeline is used, with the help of which in the zone of coagulant entry into the flow, swirling water jets uniformly distributed over the cross-section of the flow are generated, a coagulant is supplied relative to them with the possibility of at least partial self-capture by these jets and movement formed mixture to the next zone, where in this mixture turbulent jets of water with a coagulant are crushed into smaller similar formations with an increase in self-capture by turbulent jets of water coagulant, forming the active mixing of the coagulant in water.

It is possible that when crushing a mixture of turbulent jets with a coagulant in the said zone, a coagulant is additionally introduced into it with the possibility of its capture by fragmented turbulent jets of water.

Such a new technical solution makes it possible to obtain a method for introducing a coagulant during the water treatment process, the implementation of which is based on at least double distribution of the coagulant together with turbulent jets of water in the water stream, and with the formation of natural conditions for their mixing. In this case, the orientation of the coagulant supply jets with respect to turbulent jets is possible, which ensures maximum self-trapping of the coagulant by them.

It turns out that in the proposed method, on the one hand, there is a combined two-zone system for mixing coagulant with water and a two-zone system for the formation of turbulent vortex jets in the stream. Moreover, in the first zone we have quasi-macroturbulent jets formed in the stream along its cross section (this is well known, and they tend to distribute these jets evenly over the section, as well as the coagulant). In the present invention, this is implemented in such a way that the turbulent jets themselves capture the coagulant, which is supplied with the possibility of self-capture by the said turbulent jets, and carries away to the second zone.

In the second zone, which is not observed in the known methods for a similar purpose, turbulent jets are split into even smaller swirl jets, which capture a large mass of the coagulant introduced earlier and are saturated with its additional portions already in another swirling flow medium. As a result, sequentially without mixing with any other reagents, a coagulant is introduced at least twice in the corresponding zones of the pipeline, but rebuilding the same turbulent jets in the water stream from large sizes and from one number to a smaller and a larger number and change, according to possibilities, orientation of the flow of coagulant in the stream.

In principle, there may be one more similar introduced system for reconstructing turbulent jets with a coagulant or with an additional introduced coagulant. In essence, other reagents required to increase the efficiency of water treatment, which in this case occurs under stationary conditions without involving external activators of the process of mixing the coagulant with water, can be introduced into a similar scheme of the method.

Thus, a method has been created in which, at low flow velocities (0.2 ... 0.5 m / s), without additional activation under conditions of natural non-forced dissolution of coagulant in water, an active jet of water jets is created in the form of swirling water uniformly distributed over the cross section and mixing with them a coagulant.

The inventors conducted a patent search on this subject. He showed that the proposed combination of essential features was not found. Therefore, this invention can be considered new.

The claimed invention meets the condition of patentability "inventive step". It for a specialist does not logically follow from the prior art. So, the analogs reflect a general trend in the method of introducing coagulant into the water treatment process, which is based on the desire to distribute the coagulant in the water stream as evenly as possible and actively mix it with the help of external activators, including the use of various physical field influences.

In the present invention, there is no use of external activators for maintaining the mixing of the coagulant with water. In the present invention, the method system is self-executing due to the flow energy. In this case, the coagulant is mixed in two zones with a change in its turbulent jets. Moreover, the proposed method at least twice mixes the coagulant in the respective areas of the pipeline. Moreover, the reconstruction of turbulent flows with a coagulant from one type of flow to another occurs sequentially.

The proposed method for the introduction of coagulant in the process of water treatment has practical application, and its essence is illustrated by the drawing and the following description.

FIG. 1: General scheme of the proposed method in longitudinal section, where:

1 - raw water pipeline;

2 - pipeline supply coagulant solution;

3 - beam distributor of the coagulant solution;

4 - the movement of the jets of the coagulant solution to the lattice;

5 - a lattice;

6 - flow movement after the grate.

Mixing the solution with the raw water to be processed takes place by applying a solution of a chemical agent (coagulant) to a moving stream of water under excessive pressure. Although under these conditions (the diameter of the pipeline and the working flow rate of the raw water) a turbulent flow regime should be observed, nevertheless, the random speeds of the jets of water may not be sufficient for high-quality mixing of the solution of the chemical agent (coagulant) with the treated raw water.

When the coagulant solution flows around the beam distributor (3), the water flow further swirls, and the speed of the chaotic movement of water jets increases, into which the coagulant solution is injected into the beam distributor (3). After the initial mixing, the water flow with the introduced and pre-distributed coagulant solution reaches, for example, a swirl lattice (5), where, when flowing over the partitions of its cells, the secondary randomness of the stream jets is uniformly distributed over the entire cross section of the stream, further improving the quality of mixing.

In essence, the proposed method is implemented as follows (illustrated by the above diagram). Water is supplied to pipeline 1, and at a certain distance from its entry into the zone, a coagulant is fed through a special supply pipe 2. From this pipeline, the coagulant enters through a beam distributor 3. This beam distributor 3 can be equipped with swirl jet shaper elements in a stream of water that flows around them and twists (not shown in the drawing). The water and the coagulant located in the pipeline 1 are actively mixed, for which purpose the energy of the water flow in the pipeline is used, with the help of which in the zone of introduction of the coagulant into the stream, vortex jets of water 4 uniformly distributed over the cross section of the stream are created. Relatively they are supplied with a coagulant with the possibility of at least partial self-capture by these jets and moving the formed mixture to the next zone, where in this mixture turbulent jets of water with a coagulant are split into smaller similar formations with an increase in coagulant self-capture by new swirling jets of water. For crushing turbulent jets of water with a coagulant, a mesh or mesh filter (not shown) can be used located across the stream.

A situation is possible when there is an additional introduction of coagulant in the water treatment process, which is also carried out when the mixture of turbulent jets with the coagulant is crushed in the mentioned zone - naturally, subject to the self-trapping conditions by the fragmented turbulent water jets of the additionally introduced coagulant. It should be noted that in the second zone, the initial turbulent jets of water in the stream and the coagulant trapped by them are crushed, for example, through a grating 5 with small windows specially installed across the stream (not shown in the drawing). These turbulent jets pass through them, swirl and crush into smaller ones, forming at the exit from the lattice 5 with a coagulant a form of a water cloud 6, inside of which intensive mixing of water with the coagulant takes place. As a result, an optimal natural regimen for introducing the coagulant into the water treatment process is created, in which the coagulant comes into contact with the maximum number of particles of water impurities before the hydrolysis and polymerization reactions end.

Claims (1)

A method for introducing a coagulant in a water treatment process, comprising supplying a coagulant to a purified water located in a pipeline and activating a coagulant by stirring it in water, characterized in that they use the energy of the water flow in the pipeline, by means of which, in the zone where the coagulant is introduced into the flow along its transverse the cross section is created by turbulent jets of water evenly distributed over the cross section of the flow, relative to them, a coagulant is fed with the help of a beam distributor located in the water flow along the edge at least partial self-capture by these jets and moving the formed mixture to the next zone, where in this mixture turbulent water jets with a coagulant are crushed on a grid placed in a water stream into smaller similar formations with an increase in self-capture by the turbulent jets of water of the coagulant, forming active mixing of the coagulant in water, wherein the creation of turbulent jets of water distributed over the cross section of the pipeline is carried out by flowing around the beam distributor of the coagulant solution.

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