UDC 628.161.3:628.166
DOI 10.35776/VST.2025.03.01
Veselovskaya Tat’iana, Svintsitsky Viacheslav
Drastic reduction of trihalomethane concentration
in domestic water supply systems
Summary
Disinfection stage that guarantees the safety of drinking water in epidemiological terms is mandatory in the process of water treatment. One of the main disinfection methods is chlorination with chlorine or hypochlorites. As a result, chlororganics are generated in drinking water. Some representatives of this class of compounds – trihalomethanes pose a danger to human health, producing a carcinogenic, mutagenic effect, and accumulating in the body. In this regard, the sanitary legislation strictly regulates the concentration of these compounds in drinking water, and the standards for them continuously toughen. Reducing the concentration or limiting the generation of trihalomethanes in drinking water has been an urgent task, and for the purpose of solving this task a number of technical methods are proposed. A promising method of water disinfection is presented that provides for almost complete elimination of trihalomethane generation; namely processing water with «Chlorine dioxide and chlorine» disinfectant, obtained in local automated installations of «DH-100» type. As the practice of implementing this method at more than 50 water treatment facilities in Russia and Kazakhstan has shown, the method provides for reducing trihalomethane concentrations, including water supply sources containing bromides, up to their complete elimination, while ensuring complete disinfection and safety of drinking water.
Key words
potable water , disinfection , bioreactor , water treatment , ozone , trihalomethanes , chlororganic compounds , chlorine , chlorine dioxide , preammoniation , hypochlorites , bromides
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DOI 1035776/MNP.2020.07.01
UDC 628.162.84
FESENKO L. N., Ignatenko S. I., Skryabin A. Yu., Pchel'nikov I. V.
Formation of volatile chlororganic compounds in the process
of the Don River water disinfection with chlorine-containing agents
Summary
Various oxidants are used for water purification and disinfection, including chlorine and its derivatives (hypochlorites, chloramines, bleach, etc.), ozone, less often chlorine dioxide, hydrogen peroxide, potassium permanganate, etc. Traditionally, the sanitary and epidemiological safety of drinking water is ensured by chlorination owing to the sanitary and hygienic reliability, prolonged bactericidal action, relative simplicity and economic efficiency of the method. While disinfecting water, an agent containing active chlorine is used, which, upon entering into a substitution reaction with organic substances present in water, forms toxic compounds belonging to the group of trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, bromoform, etc.). The Don River water is characterized by the presence of bromides (0.18–0.2 mg/dm3) resulting in the formation of bromine-containing volatile chlororganic compounds. The water treatment facilities of the Industrial District of Novocherkassk have introduced the technology of «Chlorine dioxide and chlorine» disinfectant production based on the redox reaction between chlorate and sodium chloride in acid environment. The use of liquid chlorine and sodium hypochlorite for the disinfection of the Don River water leads to the formation of volatile chlororganic compounds with dibromochloromethane and chlorodibromomethane dominated. Preammoniation of water with a chlorine to ammonium sulfate ratio of 4:1 is an effective way to reduce the concentrations of volatile chlororganic compounds to 0.02–0.1 MPC while using liquid chlorine or sodium hypochlorite. Chlorate-chloride technology of producing chlorine dioxide in acid environment instead of «Chlorine dioxide and chlorine» agent generates 100% hypochlorite solution in the hypochlorous acid format that, in the absence of water preammoniation, is capable of forming volatile chlororganic compounds in concentrations exceeding the MPC.
Key words
sodium hypochlorite , water disinfection , chlorine water , chlorine dioxide , bromine-containing trihalomethanes , preammoniation , chlorate-chloride production of chlorine dioxide
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