SU988778A1 - Process for degreasing potable water - Google Patents

Description

(54) METHOD FOR DISINFORING DRINKING WATER

The invention relates to methods for disinfecting water and can be used in household water supply, in particular when supplying water through water lines of a large extent.

There is a known method of disinfecting water by chlorination with chlorine gas or chlorine-containing inorganic substances l.

The disadvantages of this method are the increased consumption of chlorine, especially when. treatment of colored waters, and the short duration of the effect of water disinfection.

The closest to the proposed invention to the technical essence and the achieved result is a method of drinking water disinfection, including primary chlorination, treatment with inorganic coagulant, clarification, ammonization and secondary chlorination.

The advantages of this method are the possibility of reducing the dose of chlorine in a number of cases by 25-30% and longer maintaining residual chlorine in water to 4-5 hours {2.

However, the method has disadvantages associated with the agfunification process.

water, for example, reducing bactericidal chlorine by 3-25 times due to its conversion into chloramines and, as a result, the time required for contacting chlorine with water before it is supplied to the consumer.

The purpose of the invention is to increase the degree of disinfection and stabilization of residual chlorine in water.

ten

This goal is achieved by the fact that according to the method, chlorinated hydantoins containing chlorine and ammonium in a ratio of 1: 1-1: 2 are used as ammonium-chlorine containing reagent

In addition, either 1, 3-dicloro-5,5-dimethylhydantoin t or monochlor-5,5-dimethylhydantoin is used as chlorinated hydantoins.

20 —OR a mixture of the above compounds.

At the same time, 1, 3-dichloro-5,5-dimethylhydantoin contains twice as much active chlorine as monochlor-5,5-dimethylhydantoin, and during its use

25 weight consumption of the reagent with the same dose of chlorine is almost 2 times less, i.e. half the amount of organic matter is introduced into the water and, accordingly, in the filtrate half the concentration of residual

methylhydantoin. In this case, the ratio of chlorine to ammonium is 1: 1 (moles per mole).

However, 1.3 dichloro 5,5-dimethylhydantoin is limited soluble in water - 0.1%, i.e. the strength of the solution for disinfection in terms of chlorine can not exceed 1 g / l.

On the contrary, 5,5-dimethylhydantoin monochlorine is soluble in water to a concentration of 4%, i.e. 40 times higher. In its application, the chlorine to ammonium ratio increases to 1: 2 (moles per mole), since monochloro-5, 5-dimethylhydantoin contains two times less active chlorine.

For this reason, with the introduction of monochlorine 5,5-dimethylhydraxide to monochlorine, the amount of organic matter introduced per unit of chlorine and the content of residual amounts of dimethylhydantoin in the Filtrate doubles compared with 1,3-dichloro-5, 5-dimethylhydantoin,

Thus, the ratio of chlorine to ammonium depends on the reagent used and can range from 1: 1 (moles per mole) when using 1,3-dichloro-5, 5-dimethylhydantoin to 1: 2 (moles per mole) when using monochlor -5,5-dimethylhydantoin. When a mixture of these reagents is used, the mole to chlorine to ammonium ratio can assume any fractional value. more than 1 and less than 2.

Accordingly, the content of residual chlorine in water changes its oxidative capacity and the duration of the stabilizing effect of ammonia on residual chlorine, which allows in each case as required by the rules of operation of water supply systems to choose the optimal ratio of ammonium salts in the original water, from the length of the conduit, the presence of intermediate reservoirs and the residence time of water in them.

The use of 1,3-dichloro-5, 5-dimethylhydantoin (dichlorantin-DCA) as a reagent for secondary chlorination and stabilization of residual chlorine practically does not reduce bactericidal chlorine, as is typical of amines in general, and organic amines in particular.

This is due to the fact that of the three valences of nitrogen, which is part of the composition, two bind nitrogen into the pyridine ring, as a result of which chlorine saturating the third valence of nitrogen is highly mobile and easily hydrolyzed, forming a hypochlorite ion.

Thus, hypochlorite-ion, which is formed due to hydrolysis, has a bactericidal effect that is not inferior to that of gaseous chlorine, and chlorine remaining in the composition of DHA can dissociate (due to a low dissociation constant during step-by-step hydrolysis), the hygrochlorite ion disappears from water, i.e. . while decreasing c. water content of residual chlorine ..

The mechanism of this process provides a long, for several days, the presence of residual chlorine in the water during the processing of its DHA, i.e. stabilizes residual chlorine in water, which makes it possible to use the proposed method instead of repeated chlorination and ammoniation of water along the length of the conduit with a large extent used in individual cases ..

Example 1. A water treatment plant filtrate obtained after primary chlorination of water before clarifiers with suspended sediment at a dose of 3 mg / l when coagulated with aluminum sulphate at a dose of 4 mg / l () / and also secondary chlorination of water after filters at a dose of 2 mg / l and ammoniation at a dose of 0.8 mg / l, taken in the tank. In this case, the filtrate is characterized by the following indicators: temperature 4 g5 ° C, transparency more than 300 cm across the cross, color 8 degrees, alkalinity 2.1 mEq / l, pH 7.4, oxidability 3.2 mg / l Q, total nitrogen 0., 84 mg / l, residual aluminum 0.23 mg / l, residual chlorine, 1.43 mg / l, total 2.36 mg / l.

Before the filtrate enters the clean water tank, its smell is 5 points (chlorine), and the taste is 4 points (medicinal).

Water samples are taken from the tank to determine the dynamics of changes in the concentration of residual chlorine over time and to determine the bactericidal behavior of water.

EXAMPLE 2. The filtrate of a waterworks, taken after filters prior to secondary chlorination and ammoniation, i.e. treated with a primary dose of chlorine 3 mg / l and aluminum sulfate at a dose of 4 mg / l (Ae2Oz), clarified in clarifiers with suspended sediment and filtered through fast sand filters, are treated instead of secondary chlorination with chlorine gas, 1, 3-dichloro-5, 5-dimethylhydantoin, or monochloro-5, 5-dimethylhydantoin, or a mixture of 1, 3-dichloro-5,5-dimethylhydantoin and monochloro-5,5-dimethylhydantoin.

The dose of chlorinated hydantoin in terms of chlorine is 2.5 mg / l.

In this case, the ratio of chlorine to ammonium varies from 1: 1 (mol per mole) with the use of 1,3-dichloro 5,5-dimethylhydantoin to 1: 2 (mol per mole)

when using monochlor-5, B-dimethylhydantoin. When using a mixture of these reagents, the molar ratio of chlorine to ammonium is fractional, i.e. greater than 1 and less than 2.

The quality of the filtrate, taken for experiments prior to the introduction of secondary chlorine and ammonia at the station, is characterized by the following indicators: temperature 4.5 ° C, transparency greater than 300 cm across the cross; color 7 °; alkalinity 2.2 mEq / l; pH 7.45; oxidability 5.4 mg / l Oj; total nitrogen 0.16 mg / l; residual aluminum 0.28 mg / l; residual chlorine is absent; smell and taste 1 point (marsh). ,

The effect of chlorinated hydantoino on the content of residual chlorine and coli titer in secondary water disinfection is shown in Table 1. As can be seen from the table, the use of chlorinated hydantoins instead of secondary chlorination by chlorine and ammonia with ammonia ensures the production of water that meets the quality requirements of FOCT-2874-73 according to bacteriological indicators and contains residual chlorine for 7 days, including 2 mg / l for 2 days.

The solution of a mixture of 1,3-dichloro-5, 5-dimethylhydantoin 333 333 333 300 300

and monochloro-5,5-dimethyl-l7TO T7lO 1, then 0780 0776

gidaitoina

This provides the possibility of using chlorinated hydantoins to stabilize the residual chlorine in water.

The main design parameters of the technical-economic efficiency are summarized in Table 2.

Cost effective use for water stabilization

t DHA for a station of 100 thousand meters. The cost of reduced costs is 2575 rubles / g. .

Thus, the technical and economic advantages of the proposed method are the possibility of carrying out the process of secondary chlorination and ammoniation of water using a single reagent instead of two, the possibility of stabilizing residual chlorine for a very long time, which allows a large amount of water to flow through pipelines without additional chlorination. femininity. The use of the proposed method is most useful when used under the conditions of a non-circular water mixture that has dead-end areas, including on rural group water pipelines.

Table 1

230 111

o7bz o7z1

Chlorine

Chlorine 212 0.63

Ammonia

Ammonia 169 0.5

OfferedDHA 183.

Claims (2)

DHA 0,5 Formula of the invention 1. Method of drinking water disinfection / including chlorination, treatment with inorganic coagulant, clarification and treatment of ammonium with chlorine-containing reagent, so that with the aim of increasing the degree of disinfection and stabilization residual chlorine in water, chlorinated hydantoins containing zhor and ammonium in the ratio 1: 1-1: 2 are used as ammonium-chlorine-containing reagent. table 2 48002 51556 45796 48981 9256 47871 2. A method according to claim 1, about tl and h. Ayush and the fact that either 1, 3-dichloro-5,5-dimethylhydantoin, or monochloro-5,5-dimethylhydantoin is used as chlorinated hydantoins, or a mixture of the above compounds. Sources of information taken into account in the examination 1.Klko V.A ,, Apeltsin N.E. Purification of natural waters. M., stroiizdat, .1971, p. 288-316. 2. Cherkinsky S.N. Guide to water hygiene, M., Medicine 1975, p. 155-161.