RU2288189C1 - Water disinfection process - Google Patents

Abstract

FIELD: water treatment processes.

SUBSTANCE: invention relates to combination methods for treating drinking water using chemical reagents and ultraviolet emission. It can be used to disinfect drinking water in water supply systems of residential sites, in ships, and also in mobile installations used in emergency situations. Disinfection process comprises treatment of water with UV emission, hydrogen peroxide, and catalyst prepared by mixing pulverized naturally occurring mineral rutile with cupric oxide particles at rutile-to-cupric oxide weight ratio (50-100):1 followed by adding bentonite clay in amount 5-10% of the weight of rutile/cupric oxide mixture, adding water to form paste, partially drying the paste at 105-120°C, and molding the paste into pellets.

EFFECT: simplified and reduced in price process due to eliminated use of expensive silver and crushing process thereof, and prevented possibility of secondary bacterial contamination of water over a long (no lee than one month) period of time.

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Description

The invention relates to combined methods for treating drinking water using chemicals and ultraviolet (UV) radiation. It can be used for disinfection of drinking water in the water supply systems of settlements, on ships, as well as in special mobile installations used in emergency situations.

The most common way to disinfect water is to chlorinate it. Due to the fact that most of the chlorine is involved in reactions with various organic and inorganic impurities contained in water, significant amounts of this reagent are required to achieve the actual disinfecting effect. At the same time, water acquires an unpleasant taste and halls, the danger of its negative impact on the human body increases due to the appearance of organochlorine compounds in it. However, complete sterilization of the water does not occur, as single chlororesistant microorganisms remain in it. In addition, chlorine does not have a lasting aftereffect, because after a drop in its concentration, water may undergo secondary bacterial contamination.

In connection with the above circumstances, the urgent task is to completely reject chlorination in favor of alternative methods of disinfection or to reduce the concentration of chlorine due to its use in combination with other methods of water treatment.

As for the complete rejection of chlorination, for example, a multi-stage method for purifying natural waters is known, which includes two stages of mechanical treatment, sequential UV irradiation of a continuous spectrum, reverse osmosis desalination, transmission through a carbon fiber sorbent and repeated pulsed UV irradiation of a continuous spectrum (RU, 2033976, 1995). The disadvantage of this method is its complexity and high cost.

The closest analogue of the proposed invention is a comprehensive method of disinfecting water (patent RU 2213706, published 10.10.2003,). The specified method consists in sequential treatment of water with UV irradiation with a wavelength of 200-400 nm, hydrogen peroxide (50-100 mg / l) and a heterogeneous catalyst. The latter is obtained by mixing a powder of a natural mineral - rutile with a particle size of not more than 0.5 mm and metallic silver with a particle size of not more than 0.05 mm with their mass ratio correspondingly equal to (700-1000): 1. Water is then added to the mixture until a paste forms, which is dried at 100-150 ° C and molded, for example, in the form of tablets. Preferably, said catalyst is administered in an amount of 0.5-1.5 mg / L.

The disadvantages of this technology include the need to use expensive silver, its preliminary crushing, as well as the possibility of theft. According to known technology, the preparation of 1 ton of contact mass will require 0.7-1.0 kg of metallic silver.

The objective of the invention was to simplify and reduce the cost of the process of obtaining a catalyst by eliminating expensive silver and the process of its crushing, ensuring the possibility of preventing secondary bacterial infection of water for a long time (at least a month).

The method of water disinfection, including its treatment with ultraviolet radiation, hydrogen peroxide and a rutile-based catalyst, differs from the closest analogue in that the catalyst is obtained by mixing powdered natural rutile mineral with particles of copper (II) oxide at a mass ratio of rutile: copper oxide, equal (50-100): 1, followed by the addition of bentonite clay in an amount of 5-10 wt.% by weight of the mixture of rutile and copper oxide, the introduction of water to obtain a paste, drying it at a temperature (105-120 ° C) and molding tablets.

Thus, instead of metallic silver, we propose mixing powder of rutile with powder of copper oxide (CuO), which, as shown by our studies, has a high bactericidal activity and provides the antibacterial resistance to the water treated with it for a long time (about a month). In addition, copper oxide is a catalyst for the decomposition of hydrogen peroxide, during which OH radicals are extremely bactericidal, which accelerate the destruction of unwanted microorganisms, which, in turn, after a relatively short period of time (calculated in minutes) turn into water molecules. The simultaneous use of all the essential features of the invention leads to a non-additive increase in the efficiency of water treatment.

The technology for producing a catalyst based on rutile and copper oxide is as follows. Rutile powder with a particle size of not more than 0.5 mm is mixed with a powder of copper oxide CuO (particle size 0.2-0.5 mm) at a given ratio. To the resulting mixture add bentonite clay as a binder and water to the consistency of the paste, then it is dried at 105-120 ° C and formed. Preferably, said catalyst is added in an amount of 1-1.5 g per 1 m ^{3 of} disinfected water.

It is known that hydrogen peroxide is an environmentally friendly, relatively inexpensive bactericidal drug for the disinfection of drinking water, which does not change its physico-chemical characteristics.

Rutile is a mineral, one of the crystalline modifications of titanium dioxide, sometimes with an admixture of iron, tantalum, niobium. The hardness according to the mineralogical scale is 6-6.5; density 4200-4300 kg / m ³ . Titanium dioxide is practically insoluble in water, so the use of a catalyst in the form of 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 also helps to remove excess hydrogen peroxide after the end of the water disinfection process.

The following are examples of the implementation of the proposed method.

Example 1

Natural water with a concentration of microorganisms shown in the table at a temperature of 20 ° C and a pH of 6.8 was placed in a reactor and irradiated with xenon flash lamps of a continuous spectrum, mainly emitting in the range of 200-400 nm at a pulse frequency of 2 Hz, a flux density of 2 kW / cm ² and specific energy consumption of 2 J / cm ^{3 of} water. Then, hydrogen peroxide was introduced into the water in an amount of 50 mg / L. The resulting water was kept for 0.2 hours, after which catalyst tablets based on rutile and copper oxide were introduced into it in an amount of 1 mg / l (1 g / m ³ ). Tablets were preliminarily prepared by mixing rutile powder (particle size 0.01-0.5 mm) with copper oxide powder (bp) at a mass ratio of rutile: copper oxide of 50: 1, followed by the addition of bentonite clay in an amount of 5 wt.% From the mass of the above mixture and water to obtain a paste, drying it at a temperature of 105 ° C and molding on the press in the form of tablets with a diameter of 15 mm and a height of 8 mm After the introduction of the catalyst, the water in the reactor was held for 1 hour. The test results are presented in the table.

Example 2

For the tests used source water infected with E. coli 1257 Escherichia coli with the concentrations indicated in the table. The water was treated in accordance with example 1, except that the concentration of hydrogen peroxide was 100 mg / l, the mass ratio of rutile: copper oxide was 100: 1, the amount of bentonite clay was 10 wt.% By weight of the mixture of rutile and copper oxide, and the drying temperature of the paste is 120 ° C. The test results are presented in the table.

As follows from the test results presented in the table, the proposed method is quite effective in bactericidal relation. Moreover, after 1 hour of contacting the catalyst with water containing hydrogen peroxide, no traces of the latter were found. In order to study the effect of bactericidal aftereffect, they set up a separate experiment. The treated water (see examples 1 and 2, the initial concentration of E. coli 10 ⁵ individuals / l) was kept for 48 hours, and then their number was determined. These microorganisms were not detected, which indicated the presence of an aftereffect due to the presence of a catalyst. Similar analyzes carried out over the next 28 days with an interval of 48 hours gave the same results, i.e. the effect of bactericidal aftereffect (the ability to resist secondary bacterial contamination) persisted for a month. There was no smell and unpleasant taste near the water, the color did not change.

For comparison, experiments were conducted on water treatment (after exposure to UV radiation) only with hydrogen peroxide, only rutile in the form of a powder (without the addition of copper oxide), and also only with the proposed catalyst. In the first case, the appearance of E. coli microorganisms in water was already noted in two days, in the second - after 4 days. Only in the presence of the finished catalyst did a stable disinfecting and preserving effect be found.

Thus, the proposed method of water disinfection can be characterized as effective and characterized by relative simplicity and accessibility. It can be used in cases where there is a great danger of secondary bacterial contamination of water.

METHOD FOR WATER DISINFECTION OF HYDROGEN PEROXIDE AND CATALYST
Table Type of microorganism The initial number of microorganisms, individuals / l The final concentration of microorganisms, individuals / l example 1 example 2 E. coli E. coli 10 ³ 2 not detected 10 ⁴ 3 2 May ¹⁰ 45 fifty

Claims (1)

A method of disinfecting water, including its treatment with ultraviolet radiation, hydrogen peroxide and a rutile-based catalyst, characterized in that the catalyst is prepared by mixing powdered natural rutile mineral with copper (II) oxide particles at a mass ratio of rutile: copper oxide (50-100) : 1, the subsequent addition of bentonite clay in an amount of 5-10% by weight of a mixture of rutile and copper oxide, the introduction of water to obtain a paste, drying it at a temperature of 105-120 ° C and molding in the form of tablets.