RU2442753C1 - Water purifying method - Google Patents

Abstract

FIELD: central utility and drinking water supply.

SUBSTANCE: invention can be used in the field of central utility and drinking water supply, mainly in the course of surface water treatment. The method includes curdling that is performed by means of introduction of a nonorganic coagulating agent, flaking, further separation of the flakes from water by suppression and filtration, and decontamination. Water treatment is carried out using compositions based on the water solution of polyhexamethylen guainidine hydrochloride and alkyldimethylbenzyl ammonium chloride; the ratio of the components included in the composition amounts in the weight %: polyhexamethylen guainidine hydrochloride 37,9-46,4; alkyldimethylbenzyl ammonium chloride 7,0-8,6; water - the rest. The mentioned composition is introduced into the water in two stages as follows: at the first stage - after introduction of the coagulating agent before flaking, and at the second one - after separation of the flakes from water by suppression.

EFFECT: high quality water treatment that corresponds to modern requirements with simultaneous improvement of the cost-performance ratio.

1 dwg, 2 tbl, 1 ex

Description

The invention relates to methods for water purification and can be used in the field of centralized drinking water supply, mainly in surface water treatment.

The method of water purification is widely known, including its ammoniation, coagulation by introducing an inorganic coagulant, flocculation, the subsequent separation of flakes from water by precipitation and filtration, as well as disinfection with a chlorine-containing reagent, carried out in two stages: before coagulation, at the first and after filtration - On the second.

In this case, either liquid chlorine or sodium hypochlorite is used as a chlorine-containing reagent, and ammoniation is performed to prolong the disinfecting effect when transporting purified water to consumers [1].

The main disadvantages of this method are:

- a low degree of water purification (especially color and low turbidity) in the winter, when the process of flocculation proceeds very sluggishly and the resulting flakes practically do not separate from the water by precipitation;

- insufficient water safety in an epidemic sense in cases where the source water contains enteroviruses and Giardia cysts;

- the formation of organochlorine compounds during disinfection, most of which are carcinogenic.

The closest to the proposed technical essence and the achieved effect is a method of water purification, including its ammonia, coagulation, carried out by introducing an inorganic coagulant, flocculation, carried out by continuous recirculation of part of the resulting flakes, separation of flakes from water by precipitation and filtration, as well as disinfection, produced in two stages, by treating the water with ultraviolet light - in the first and the introduction of a chlorine-containing reagent after separation of the flakes - in the second.

Moreover, in this method (as in the above), liquid chlorine or sodium hypochlorite is used as the chlorine-containing reagent, and ammoniation is performed to prolong the disinfection during transportation of purified water to consumers [2].

This method in comparison with the widely known method provides a much higher degree of water purification due to the intensification of the process of flocculation and, accordingly, better separation of flocs from water by precipitation.

However, this method also has a number of significant disadvantages:

- the difficulty of implementation, due to the need, on the one hand, in the process of flocculation to continuously recycle part of the resulting flakes, and on the other hand, apply water treatment with ultraviolet light to increase the effect of disinfection;

- the formation of organochlorine compounds in the second stage of disinfection, most of which (as noted above) has carcinogenic properties.

The aim of the invention is the development of such a method of water purification in which the degree of purification corresponding to modern requirements would be stably and reliably achieved, while improving technical and economic indicators by simplifying the method and, accordingly, reducing costs associated with its implementation.

The goal according to the invention is achieved due to the fact that in the method of water purification, including: coagulation, carried out by introducing an inorganic coagulant, flocculation, the subsequent separation of flakes from water by precipitation and filtration, as well as disinfection, the cleaning process is carried out using an aqueous composition solution of polyhexamethylene guanidine hydrochloride (PHMG) and alkyldimethylbenzylammonium chloride, introducing the specified composition into water in two stages, of which the first after entering gulyanta before flocculation, and in the second - after separating the flakes from water precipitation.

It is advisable that the ratio of the components included in the composition, in wt.%:

polyhexamethylene guanidine hydrochloride 37.9-46.4 alkyldimethylbenzylammonium chloride 7.0-8.6 water rest

Example

Water from a surface water source characterized by: color 130-140 degrees, turbidity 3.8-4.5 mg / l, oxidizability 14.2-14.8 mgO ₂ / l, containing 100 ml total microbial number (TBC) - 132, the total number of bacteria (OKB) is 95, the number of thermo-tolerant coliform bacteria is 60, they are purified by settling, filtering and disinfection.

Spend several series of experiments. In all series of experiments, the dose of inorganic coagulant was 12.5 mg / l (according to Al ₂ O ₃ ), the flocculation time was 25 min, and the filtration rate was 6.3 m / h (with a loading height of 1.5 m and grain size in it from 0.6 to 1.7 mm). The residence time of purified water in a special contact container (simulating a reservoir of clean water and providing temporary contact of the disinfecting agent with water) was about 35 minutes.

The main criterion for the effectiveness of the tested methods was the compliance of the quality indicators of purified water with modern domestic requirements.

The first series of experiments was aimed at studying the effectiveness of using a composition based on an aqueous solution of polyhexamethylene guanidine hydrochloride and alkyldimethylbenzylammonium chloride in the process of water purification. At the same time, when testing, the reagent "DEZAVID concentrate" produced in Russia, in which the ratio of components is, in wt.%:

polyhexamethylene guanidine hydrochloride 37.9-46.4 alkyldimethylbenzylammonium chloride 7.0-8.6 water rest

An additional criterion during testing was to obtain the residual value of the reagent "DEZAVID concentrate" in an amount not exceeding 0.1 mg / l for the main active substance (PHMG), that is, the value corresponding to the MPC.

During testing, the DEZAVID concentrate reagent was introduced into water in one stage: before flocculation, or before purified water enters the contact container, or in two stages: in the first of which, the reagent was introduced into water after the coagulant was introduced before flocculation, and in the second after separating flakes from water by precipitation.

Tests showed that only with a two-stage introduction of the composition into water did the necessary degree of its purification be achieved.

The second series of experiments was aimed at studying the effectiveness of the proposed method in relation to the known.

Quality indicators of purified water by precipitation and filtration before it enters the contact tank are shown in table 1.

The quality indicators of purified water at the outlet of the contact tank, calculated, as noted above, for a residence time of water in it of 35 minutes, are shown in table 2.

Table 1 The main quality indicators of purified water before it enters the contact tank Water quality indicators Proven Methods famous proposed Turbidity, mg / l 0.05-0.08 0.06-0.08 Color, hail 11.2-11.5 10.0-11.1 Oxidation, mgO ₂ / L 4.8-5.0 3.4-3.6 Aluminum ost., Mg / l 0.05-0.09 0.03-0.04 OMC, KOE / ml 2.5-6.0 3.0-4.0 OKB, KOE / 100 ml 4.3-5.0 5.7-6.9 TKB, KOE / 100 ml 1.7-2.2 2.1-3.2 Chloroform, mg / L 55-62 - Desavid (according to PHMG), mg / l - 0.05-0.06

table 2 The main quality indicators of purified water at the outlet of the contact tank Water quality indicators Proven Methods famous proposed Turbidity, mg / l 0.05-0.08 0.06-0.08 Color, hail 11.2-11.5 10.0-11.1 Oxidation, mgO ₂ / L 4.8-5.0 3.4-3.6 Aluminum ost., Mg / l 0.05-0.09 0.03-0.04 TBC, KOE / ml 0 0 OKB, KOE / 100 ml 0 0 TKB, KOE / 100 ml 0 0 Chloroform, mg / L 59-66 - Desavid (according to PHMG), mg / l - 0.08-0.10

As follows from the data presented in table 2, the known and proposed methods make it possible to obtain water as a result of purification that meets existing standards in terms of quality.

However, the results of the tests showed that the proposed method has a number of significant advantages compared with the known:

- it is characterized by simplicity and cost-effectiveness, since during its implementation it is not necessary to carry out continuous recycling of part of the resulting flakes in the flocculation chambers, and it is also possible to exclude ammoniation, chlorination and ultraviolet treatment from the water treatment process;

- provides a more effective degree of purification, since when it is implemented, due to the rejection of chlorination, there are no organochlorine compounds in the purified water, some of which have carcinogenic properties. In addition, during its implementation, a deeper water purification is achieved by such indicators as: the value of residual aluminum and oxidizability.

Additionally, studies have shown that the disinfection of water carried out by the proposed method can increase the prolonging effect compared with the known. So, in the proposed method, it is 2.0-2.5 months, while in the known it does not exceed 2 weeks.

The above advantages of the proposed method are largely due to the fact that when a composition is introduced in two stages (based on an aqueous solution of polyhexamethylene guanidine hydrochloride and alkyl dimethylbenzylammonium chloride), the latter primarily plays the role of a cationic flocculant in the first stage of introduction into contaminated water, and in the clarified water, at the second stage disinfecting reagent.

Information sources

1. USSR author's certificate No. 656972, cl. C02F 1/18, 1977.

2. RF patent №2258677, cl. С02F 9/04, 2005 (prototype).

Claims (1)

A method of water purification, including coagulation by introducing an inorganic coagulant, flocculation, subsequent separation of flakes from water by precipitation and filtration, as well as disinfection, characterized in that the water purification process is carried out using a composition based on an aqueous solution of polyhexamethylene guanidine hydrochloride and alkyl dimethylbenzylammonium chloride, the ratio of the components included in the composition is in wt.%:
polyhexamethylene guanidine hydrochloride 37.9-46.4 alkyldimethylbenzylammonium chloride 7.0-8.6 water rest,
moreover, the specified composition is introduced into water in two stages, of which: the first - after the introduction of the coagulant before flocculation, and the second - after separation of the flakes from the water by precipitation.