RU2182128C1 - Method of drinking water producing - Google Patents

Abstract

FIELD: technology of water treatment. SUBSTANCE: invention relates to the combined methods of drinking water treatment using chemical reagents and ultraviolet radiation. Method of producing drinking water involves its filtration, preliminary treatment, sterilization by UV-radiation and the following conditioning by addition of silver ions. Preliminary treatment of water is carried out by chlorination and sterilization of water layer is carried out in device of tray type using low-pressure mercury lamps producing preferably UV-irradiation with the wavelength 260 ± 40 nm being these lamps are disposed over the layer of water to be treated with a height 20-50 cm in the dose of irradiation 15-30 mJ/cm². The conditioning is performed by the dosed feeding silver complex ammonia compounds of the formula Ag(NH₃)₂NO₃ or [Ag(NH₃)₂]SO₄ or a mixture of these compounds up to the final silver concentration 0.005-0.05 mg/l in water to be treated. Indicated solution of ammonia complex compound/silver compound is prepared by mixing 0.1- 1.0% solution of AgNO₃ and/or Ag₂SO₄ and gaseous ammonia or ammonia water up to the ratio Ag⁺ : NH₃ = 2.8-3.0. Method provides the production of drinking water being among from very infected sources and possibility of storage of the produced water for a long time without its deterioration of its quality. Invention can be used for drinking water disinfection in water supply systems of settlements, in ships and special mobile units used in extreme situations. EFFECT: simplified and accelerated method. 5 cl, 1 tbl, 3 ex

Description

 The invention relates to combined methods for the treatment of drinking water using chemicals and ultraviolet (UV) radiation. It can be used to disinfect drinking water in the water supply systems of settlements, on ships, as well as on 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 smell, the danger of its negative effect 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 the complete rejection of chlorination in favor of alternative methods of disinfection or a decrease in the concentration of chlorine due to its use in combination with other methods of water treatment.

 For example, a combination of chlorination with treatment with ions of copper, silver or zinc is known (US 5858246, C 02 F 1/50, 1999). However, this method is effective only when the concentration of heavy metal ions exceeds their MAC in water.

 As for the complete rejection of chlorination, for example, there is a multi-stage method for purifying natural waters, 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.

 A known method for producing drinking water from bacteriologically infected sources, including the first stage of coarse and then fine mechanical filtration, the second stage of removal of toxic anions and cations using ion-exchange resins, the third stage of treatment on activated carbon, the fourth stage of sterilization using UV radiation and the final conditioning stage (giving preservative properties) by passing water through silver-coated sand (RO 116545, 03/30/2001). This method, in combination of essential features and the achieved result, is the closest analogue of the proposed invention. Its disadvantages: complexity and long implementation time, high cost due to the use of multi-stage processing, as well as the need for periodic regeneration of ion-exchange resins and sand treatment with silver.

 The technical problem to which the present invention is directed was to simplify and speed up the method of producing drinking water, including from highly contaminated sources, reduce the concentration of reagents used and provide the possibility of storing the obtained water for a long period without deterioration of its quality.

The problem is solved in that the method of producing drinking water, including its filtering, pre-treatment, sterilization with UV radiation and subsequent conditioning with the introduction of silver ions, is characterized in that the pre-treatment is chlorinated, the water layer is sterilized in a tray-type installation with low-pressure mercury lamps mainly generating UV radiation with a wavelength of (260 ± 40) nm, located above the surface of the treated water layer with a height of 20-50 cm with an irradiation dose of 15-30 mJ / cm ² and conditioning is carried out by dosing a solution of an ammonia complex silver compound of the formula Ag (NH ₃ ) ₂ NO ₃ or [Ag (NH ₃ ) ₂ ] ₂ SO ₄ , or a mixture of these compounds until the silver concentration in the treated water reaches 0.005-0.05 mg / l, while the specified solution of ammonia complex compounds / compounds of silver is prepared by mixing a 0.1-1.0% solution of AgNO ₃ and / or Ag ₂ SO ₄ and gaseous ammonia or ammonia water to achieve a mass ratio of Ag ⁺ : NH ₃ equal to 2.8-3.0.

 Preferably, the chlorination is carried out with liquefied chlorine, bleach or sodium hypochlorite obtained by electrolysis of a NaCl solution at an active chlorine concentration of 0.5-1.0 mg / L.

Optimally, to prepare a solution of the ammonia complex silver compound, a 0.1% solution of AgNO ₃ or a 0.2% solution of Ag ₂ SO _{4 is used} .

 In the particular case of the embodiment of the proposed method, it is carried out on a mobile installation.

 The resulting water can be bottled and sealed.

 It is the combination of essential features of the invention reflected in the independent claim that provides the above technical result, and the features of the dependent clauses specifying the optimal concentration of reagents enhance this result or reflect particular cases of using the invention.

В результате в воде находятся небольшие количества ионов серебра и молекул аммиака. Последний также проявляет бактерицидные свойства. Поскольку в природных водах всегда имеются ионы Сl^-, ионы серебра, их связывают в малодиссоциирующую соль AgCl, поэтому равновесие реакции (3) смещено вправо, и в воду постоянно переходят новые порции ионов Аg⁺, поддерживая тем самым бактериальную устойчивость воды в течение длительного срока ее хранения.The combination of chlorination of water, its UV treatment and silvering using a complex compound / compounds of silver allows you to expand the possible areas of application of the method by disinfecting water with a greater bacteriological contamination and at the same time reduce the concentration of chlorine and silver ions in comparison with most known methods of water treatment. The proposed ammonia complex silver ions are reduced more slowly than simple Ag ⁺ ions; therefore, the bactericidal effect manifests itself over a longer period of time, while the effective concentration of silver ions obtained during dissociation of complex compounds is even lower than their MPC in water. A possible explanation for this effect is that the following equilibrium reactions take place in water:

As a result, small amounts of silver ions and ammonia molecules are in the water. The latter also exhibits bactericidal properties. Since Cl ^- ions and silver ions are always present in natural waters, they are bound into a slightly dissociating AgCl salt, therefore, the equilibrium of reaction (3) is shifted to the right, and new portions of Ag ⁺ ions constantly pass into the water, thereby maintaining the bacterial stability of water for a long time her storage.

 The use of low-pressure mercury lamps emitting in the most "bactericidal region" of the ultraviolet spectrum provides a high disinfecting effect at low energy costs. The proposed quantitative restrictions on the height of the treated water layer, the radiation dose, and also the concentration of silver ions are optimal for this water treatment scheme. Recommended concentration ratios of silver and ammonia ions, corresponding to an excess of ammonia relative to stoichiometry, correspond to the maximum stability of complex compounds.

 The simplification and acceleration of the proposed method in comparison with the prototype is associated with a reduction in the number of stages of water treatment, using relatively easily prepared reagents, with high productivity and efficiency of the flow-through UV sterilization unit.

 Below are examples of the implementation of the proposed method.

Example 1. The initial water volume of 400 l was filtered through a column loaded with quartz sand, after which liquefied chlorine was introduced from the cylinder in an amount of 1.0 mg / l and kept for 2 hours. Then the water was sterilized, passing at a rate of 0.5 l / min through a tray-type installation containing 60 W BUW-60P argon-mercury lamps installed above a layer of flowing water 30 cm high, most of the radiation of which had a wavelength of 254 nm. The radiation dose was 20 mJ / cm ² . Sterilized water was collected in a separate container into which a solution of [Ag (NH ₃ ) ₂ ] NO ₃ was introduced with a dispenser until a silver concentration of 0.01 mg / L was reached in water. The specified solution was previously prepared by mixing a 0.5% solution of AgNO ₃ and gaseous ammonia to achieve a mass ratio of Ag ⁺ : NH ₃ equal to 2.8. The method was carried out on a mobile installation.

 The table shows some indicators of water quality before and after treatment. The data presented indicate a high quality water treatment carried out by the proposed method. At the same time, not only is disinfection of water achieved, but also other indicators are improved - taste, smell, color, inorganic and organic impurities. The resulting water was bottled in 20 L bottles and corked. When storing treated water for 3 months, pathogenic microorganisms were not found in it.

Example 2. Strain M-16 was additionally introduced into the source water and prepared analogously to Example 1, except that chlorination was carried out with sodium hypochlorite obtained by electrolysis of a 10% NaCl solution. The concentration of active chlorine in water during its preliminary treatment was 0.8 mg / L. Also, the difference was that instead of [Ag (NH ₃ ) ₂ ] NO ₃ , a solution of [Ag (NH ₃ ) ₂ ] ₂ SO _{4 was used} , obtained by mixing a 0.5% aqueous solution of Ag ₂ SO ₄ and ammonia water when the mass ratio of Ag ⁺ : NH ₃ equal to 3.0, and the concentration of silver in water was 0.05 mg / L. The method was carried out under stationary conditions.

 The results are presented in the table. The resulting water met all accepted quality standards.

Example 3. The initial water was additionally infected with hepatitis A. The water was treated analogously to Example 1, except that the sterilization was carried out with a UV dose of 30 mJ / cm ² , and a solution of a mixture of ammonia complex compounds [Ag (NH _{3 was} used as a disinfectant). ) ₂ ] NO ₃ and [Ag (NH ₃ ) ₂ ] ₂ SO ₄ . The solution was prepared from a mixture of salts AgNO ₃ and Ag ₂ SO ₄ taken in a mass ratio of 2: 1. The concentration of Ag ⁺ was 0.03 mg / L.

 The results are presented in the table. They indicate a high degree of bactericidal action of water obtained by this method. Water is purified from pathogenic microflora and, according to sanitary standards, is suitable for use in drinking, medical and household purposes.

 The advantage of the proposed method is its effectiveness in cases where available water sources have a strong bacterial infection, as well as the possibility of its implementation in compact mobile units to ensure the supply of drinking water to the population in emergency situations.

Claims (5)

1. The method of producing drinking water, including its filtration, pre-treatment, sterilization with UV radiation and subsequent conditioning with the introduction of silver ions, characterized in that the pre-treatment is carried out by chlorination, sterilization is carried out in a tray-type installation with low-pressure mercury lamps, mainly generating UV radiation wavelength (260 ± 40) nm and a surface layer disposed over the treated water is 20-50 cm in height, with a radiation dose of 15-30 mJ / cm ^2, and air conditioning is performed by d ized solution feed ammoniacal silver complex compound of formula [Ag (NH _{3) 2]} NO _3, or [Ag _{(NH3) 2] 2} SO _4, or mixtures of these compounds to achieve a water to be treated silver concentration 0.005-0.05 mg / l, while the specified solution of ammonia complex compounds / silver compounds are prepared by mixing a 0.1-1.0% solution of AgNO ₃ and / or Ag ₂ SO ₄ and gaseous ammonia or ammonia water to achieve a mass ratio of Ag ⁺ : NH ₃ equal to 2.8-3.0.  2. The method according to p. 1, characterized in that the chlorination is carried out with liquefied chlorine or sodium hypochlorite obtained by electrolysis of a NaCl solution, at a concentration of active chlorine in the treated water of 0.5-1.0 mg / L. 3. The method according to p. 1 or 2, characterized in that for the preparation of a solution of ammonium complex compounds of silver using a 0.1% solution of AgNO ₃ or 0.2% solution of Ag ₂ SO ₄ .  4. The method according to any one of paragraphs. 1-3, characterized in that it is carried out on a mobile installation.  5. The method according to any one of paragraphs. 1-4, characterized in that the resulting water is bottled and corked.

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