RU2213705C1 - Drinking water disinfecting method - Google Patents

Abstract

FIELD: water treatment. SUBSTANCE: invention relates to methods for treating water via hydrogen peroxide oxidation in presence of heterogeneous catalyst containing manganese, copper, and silver compounds. It can be used in water-supply systems of towns and other inhabited localities. Hydrogen peroxide is introduced in two steps. In the first step, 70-90% of total amount of hydrogen peroxide is added to crude water placed in container and resulting mixture is kept for 0.5 h, after which follows addition of tablets containing hopcalite and silver, ageing for 0.5-1 h, and, in the second step, addition of the rest of hydrogen peroxide and ageing for further 0.5 h. Above-mentioned tablets are prepared by mixing powdered hopcalite granules with particles of metallic silver no more than 0.05 mm in size at ratio hopcalite to silver equal to 1000:1, followed by adding water to form paste, partially drying the latter at 100-110 C, and molding. Advantageously, total amount of hydrogen peroxide involved is 50 to 200 mg/l. EFFECT: accelerated and simplified process and prevented secondary bacterial infection of water for long time. 4 cl, 2 ex

Description

 The invention relates to methods for treating water by oxidation with hydrogen peroxide in the presence of a heterogeneous catalyst containing manganese, copper and silver compounds. It can be used to disinfect drinking water in the water supply systems of cities and other settlements.

 A known method of disinfecting water, which consists in the combined action of hydrogen peroxide and 0.05-1.0 mg / l of copper ions. In this case, copper not only enhances the antimicrobial properties of hydrogen peroxide, but also is a catalyst for its decomposition (Savluk I.P. et al. Antimicrobial properties of copper. "Chemistry and Water Technology", 1986, 8, 6, pp. 65-67). However, the effectiveness of this method is not high enough.

 More effective is the method of chemical treatment and disinfection of water and water systems, known from EP 0059978, C 02 F 1/50, 1982, which consists in the simultaneous use of quaternary ammonium compounds, water-soluble salts of copper and / or silver and a peroxide compound that liberates oxygen during decomposition. This method, however, requires the use of sufficiently scarce compounds.

 A known method of treating wastewater from dyes, comprising treating the water in the reactor with calcium peroxide in the form of a powder or suspension in the presence of a catalyst in the form of a powder or solution containing copper and manganese compounds, for example hopcalite. As a result of a chemical reaction, a precipitate forms into which dyes pass, as well as unreacted oxidizing agent and catalyst (RU 2031858, С 02 F 1/72, 1995). This method, however, is not suitable for disinfecting drinking water, since the reagents used in the form of a suspension may remain in the water after it has settled and the sediment has been removed. In addition, this method is not quite economical due to unproductive losses of some reagents.

The closest analogue of the claimed invention for its intended purpose, combination of essential features and the achieved result is the method of disinfection of drinking water known from RU 2188170, 02 F 9/04, August 27, 2002, including its treatment with hydrogen peroxide in an amount of 1-3 mg / l for 0.4-2 hours, passing through a UV reactor, introducing a solution of silver salt to achieve a concentration of Ag ⁺ ions in water equal to 0.001-0.005 mg / l, and then adding a solution of copper salt to achieve a concentration of Cu ²⁺ equal to 0.01-0.2 mg / l. This method is quite long and laborious.

 The technical problem to which the present invention is directed was to simplify the process of disinfecting water to drinking quality, as well as to prevent secondary bacterial infection of water for a long time (at least a month).

The problem is solved in that the method of disinfecting water, including its treatment with hydrogen peroxide and silver, is characterized in that hydrogen peroxide is introduced into water in two stages, in the first of which 70-90 wt.% Of the total amount is added to the container with the source water used in the process of hydrogen peroxide and incubated for 0.5-1 hour, then a heterogeneous catalyst is introduced into the water, incubated for 0.5-1 hour, then add 10-30 wt.% hydrogen peroxide of the total amount used in the process, and incubated for 0.5-1 hours, p and wherein said heterogeneous catalyst is prepared by mixing the pulverized granules of hopcalite with silver metal particles not larger than 0.05 mm at a weight ratio of hopcalite silver equal to 1000: 1, then adding water to form a paste, drying it at a temperature of 100-110 ^o C and molding.

 Preferably, the total amount of hydrogen peroxide used in the process is 50-200 mg / L.

 It is advisable to introduce the specified catalyst in an amount of 0.1-1 mg / L.

 In the particular case, the catalyst is formed into tablets.

 Namely, the above set of essential features of the proposed invention provides the intended technical result.

 Hydrogen peroxide is a promising, inexpensive bactericidal drug for the disinfection of drinking water, which does not change its physico-chemical characteristics.

 Hopcalite is a catalyst based on manganese dioxide and copper oxide, used in the form of granules, mainly in the oxidation of carbon monoxide. We found that when it is used in a mixture with silver particles, the water treatment process is significantly accelerated while increasing the degree of disinfection.

 The use of a catalyst in the form of molded products, such as tablets, prevents its particles from entering drinking water. In addition, such tablets are conveniently stored until use in the disinfection process. The method of their preparation is very simple. The catalyst can also be molded in the form of granules, balls, etc.

 The combined treatment of water with hydrogen peroxide and the proposed heterogeneous catalyst by several orders of magnitude (compared to using only peroxide or only a catalyst) increases the rate of the oxidation and decomposition of bacteria, viruses, fungi, and also organic impurities contained in the source water. The catalyst also helps to remove excess hydrogen peroxide after the process of water disinfection.

 The proposed process parameters and reagent concentrations are optimal for this water treatment scheme.

 Below are examples of the implementation of the proposed method.

 Example 1

The source water had the following indicators: temperature 18 ^o C, pH 7.0, suspended solids 0.56 mg / l, color 28 degrees, permanganate oxidation 25 mg / l, coli index 7. Then, hydrogen peroxide was introduced into the water in an amount 40 mg / l (80% of the total amount of H ₂ O ₂ ). The resulting water was held for 1 hour, after which it had the following indicators: pH 7.4, suspended solids 0.38 mg / l, color 18 degrees, alkalinity 0.42 mEq / l, permanganate oxidation 15 mg / l O ₂ , if the index is 4.0.

Then, tablets containing hopcalite and silver were introduced into the water in an amount of 0.5 mg / L. Tablets were preliminarily prepared by mixing hopcalite powder (particle size 0.01-0.05 mm) with finely divided metallic silver particles 0.03-0.05 mm in size with a mass ratio of hopcalite: silver equal to 1000: 1, adding water to obtain paste, drying it at a temperature of 105 ^o C and molding on the press. The tablets had a diameter of 12 mm and a height of 5 mm. The water was kept for 1 hour.

After that, 10 mg / L of hydrogen peroxide was introduced into it and held for another 0.5 hours. Indicators of water obtained: suspended solids 0.25 mg / l, color 12 degrees, permanganate oxidation 12 mg / l O ₂ , coli index 2.0.

The treated water was kept in a pre-sterilized container for 48 hours, and then the coli index was determined. It amounted to 2.0. After that, the water was subjected to repeated bacteriological infection with a culture of E. coli 1257 in an amount of 10 ² cells / ml and after 24 hours a bacteriological analysis of water was carried out. The coli index was 2.0. There was no smell and unpleasant taste near the water. The effect lasted at least 1 month.

 For comparison, experiments were conducted on treating water only with hydrogen peroxide, only with a catalyst made in the form of tablets described in the example, and also with hopcalite in the form of granules (without adding silver). In none of these cases was it possible to obtain a stable disinfecting and preserving effect when storing water for a month or more.

 Example 2

For testing, pond water with a turbidity of 4.8 mg / L, color 60 degrees, pH 7.6, with an oxidizability of 18.1 mg O / L was used. Water was infected with one of the most resistant to external influences of microorganisms - Aerobacter cloacae in the amount of 10 ⁹ individuals / liter. Water was treated analogously to example 1 with some parameters changed: the concentration of hydrogen peroxide in the first stage was 90 mg / l, the tablets were administered in an amount of 0.8 mg / l, and the amount of hydrogen peroxide in the second stage was 10 mg / l. After the treatment, the water quality indicators were as follows: turbidity 0.24 mg / L, color 14 degrees, pH 6.9, oxidation 7 mg O / L. Aerobacter cloacae were not detected.

 Thus, the proposed method of disinfecting water is effective and relatively simple and affordable, and it can be used in cases where there is a high risk of secondary bacterial infection of water.

Claims (4)

1. The method of disinfecting drinking water, including its treatment with hydrogen peroxide and silver, characterized in that hydrogen peroxide is introduced into the water in two stages, at the first of which 70-90 wt.% Of the total amount used in the process is added to the container with the source water hydrogen peroxide and incubated for 0.5-1 h, then a heterogeneous catalyst is introduced into the water, incubated for 0.5-1 h, then add 10-30 wt.% hydrogen peroxide of the total amount used in the process, and incubated for 0.5-1 h, while the specified heterogeneous to catalyst was prepared by mixing the pulverized granules of hopcalite with silver metal particles not larger than 0.05 mm at a weight ratio of hopcalite silver equal to 1000: 1, adding water to form a paste, drying it at a temperature of 100-110 ^o C and postforming .  2. The method according to claim 1, characterized in that the total amount of hydrogen peroxide used in the process is 50-200 mg / L.  3. The method according to any one of claim 1 or 2, characterized in that said catalyst is introduced in an amount of 0.1-1 mg / L.  4. The method according to any one of claims 1 to 3, characterized in that said catalyst is used in the form of tablets formed on a press.