DOI 10.35776/VST.2021.12.05
UDC 628.1/.2
Gvozdev V. A., Leonov L. V., Rublevskaya O. N.
Eternal engine of progress
Summary
The quality of water supply and wastewater disposal services over the first twenty years of the 21st century has brought SUE «Vodokanal of St. Petersburg» to a new level of development owing to the introduction of innovative technologies in water supply and wastewater disposal systems. The use of technologies, such as two-stage disinfection of drinking water, odor control of landfills, geotubing, the use of Flottweg centrifuges, powdered one-component flocculant, powdered activated carbon, the introduction of a precipitation measurement system, were carried out with the active participation of Fedor Ivanovich Lobanov, Assistant to the General Director of SUE «Vodokanal of St. Petersburg» on dealing with industries, who turned 80 in November 2021.
Key words
sodium hypochlorite , flocculant , powdery activated carbon , soil , geotubing , atmospheric precipitates , precipitation gauge , innovative technology , polyacrylamide , prevention of olfaction
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UDC 628.162.8
KINEBAS A. K., JAKOVLEV V. Ju.
Introduction of Two-Stage Scheme of Water Disinfection at Waterworks of St. Petersburg
Summary
It is told about the modernization of systems of water disinfection at waterworks of St. Petersburg using sodium hypochlorite and ammonium sulphate. It has allowed to liquidate completely the threat of affecting the city’s territory and population with highly toxic substances (gaseous chlorine and ammonia) owing to possible failures at industrial sites of the State Unitary Enterprise Vodokanal Sankt-Peterburga and at transportation of liquefied chlorine and ammonia solutions, and also to exclude chlorine and ammonia influence on the environment in the case of equipment depressurization. Introduction of the technology of water disinfection with ultra-violet irradiation has favored the realization of the concept of multiple barriers at potable water disinfecting at the city’s waterworks.
Key words:
potable water , disinfection , liquefied chlorine , sodium hypochlorite , ammonia water , ammonium sulphate , ultra-violet irradiation
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UDC 628.166.094.3(477.75)
Gutenev V. V., Denisov V. V., Skryabin A. Yu., FESENKO L. N.
Water supply of the Crimea: advanced water disinfection technologies based on the local resources
Summary
Supplying population with high quality drinking water and efficient industrial and domestic wastewater treatment have been global challenges aggravating against the growing scarcity of available fresh water. These problems together with the impact on the human health and economy have also been urgent for many territorial entities of the Russian Federation including the new one – Republic of Crimea. The main problems in water supply of the present-day Crimea have been caused by the deficiency of drinking water, low sanitary reliability of the water treatment systems, lack of sufficient amount of disinfecting units in the agricultural areas, unsatisfactory sanitary and engineering condition of the water distribution networks. All that is worsening the epidemiologic situation at the health resorts of the peninsula, particularly during the high season. The unsatisfactory and even critical condition of the Crimean municipal and communal water supply infrastructure makes it difficult to provide adequate quality water (and wastewater) services to the population. The options of applying water treatment technologies with the use of different concentrations of sodium hypochlorite with an account of the specific features of the South and Steppe Crimea are considered. The availability of sea water and brackish water sources on the peninsula plain, possible use of the «honeycomb» system of disinfectant distribution make introducing the given technology on the large-scale environmentally safe and economically feasible.
Key words
water supply , sodium hypochlorite , electrolysis , water disposal , water disinfection , sea water , ground brackish water
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UDC 628.1
Skryabin A. Yu., FESENKO L. N., Popovian G. V.
Imports substitution technologies and equipment for sodium hypochlorite production
Summary
The relevance and economic viability of substituting the imported electrolyzers with the home-made units for producing low concentrated sodium hypochlorite in drinking water disinfection are shown. Russia started practicing disinfection of drinking water by chlorination at the beginning of the 1920-ies (in St. Petersburg). It turned to be a practical solution to the problem of efficient sanitary water supply of the communities. However, in relation to the current requirements water disinfection by gaseous chlorine transported to the water treatment facilities in liquid form has a number of limitations; the most significant among them is the power of chlorine in case of a leak to affect both the operating personnel and the population of the territories adjacent to the water treatment facilities. Transportation of chlorine barrels and warehousing chlorine large tonnage is a real threat to the cities and communities. This fact gave rise to the tendency of rejecting the traditional chlorination in drinking water treatment in favor of electrolytic sodium hypochlorite produced onsite by electrolysis of common salt solution.
Key words
sodium hypochlorite , electrolytic equipment , decarbonator , regenerating solution , saturator
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UDC 628.166
Zhuravkova I. V.
Import substitution in full play
Summary
According to the resolution of the Government of the Russian Federation the economic model of the country development shall be restructured to provide for the import substitution of the technologies applied in strategically significant branches using internal sources. «Nevskii Crystal» Research and Production Company has developed and manufactured a wide assortment of electrolyzers for producing and dosing low concentrated electrolytic sodium hypochlorite. The units conform fully to the international standards.
Key words
sodium hypochlorite , water treatment , water disinfection , electrolyzer , import substitution
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UDC 628.161:66.081.63
DOI 10.35776/VST.2024.01.02
Pervov A. G., Spitsov D. V., Tet Zo Aung, Medved’ko Viktoriia
Use of the reverse osmosis method for the preparation of concentrated sodium chloride solutions for the production of sodium hypochlorite
Summary
The use of membrane reverse osmosis and nanofiltration plants for the production of drinking water is described. It is noted that using hypochlorite obtained by the electrolysis of concentrated solutions of table salt is an effective method of disinfection in drinking water supply systems. A new area of application of reverse osmosis systems is considered, i. e., the preparation, in addition to clean water, of concentrated solutions of sodium chloride used for the production of sodium hypochlorite to reduce the operating costs of a drinking water treatment plant eliminating the purchase of the chemical, i. e., table salt. A process flow scheme of the proposed technology is presented, that involves cascade processing of the source water using nanofiltration membranes of low selectivity to provide for separating the concentrate into the solutions of monovalent and divalent ions. The experimental procedure is described and experimental dependencies are presented to determine the efficiency of the concentrate separation. Based on the results of the experiments, an economic calculation of the costs of designing an additional system for producing concentrated solutions was performed proving the economic efficiency of the proposed process compared to the use of table salt.
Key words
disinfection , sodium hypochlorite , reverse osmosis , reverse osmosis unit , nanofiltration , concentrate utilization , water treatment , electrolysis method
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UDC 628.166:661.417/.418
FESENKO L. N., Pchel'nikov I. V., Terikov A. S., Nguen Tkhi Tuan Z’ep
Study of chloride concentration effect on the generation of active chlorine in direct electrolysis
Summary
Electrochemical sodium hypochlorite has been most often used in water treatment at the water and wastewater treatment facilities. Natural water containing chlorides can be used as raw material for its production. The results of studies of electrolysis of low mineralized water with 25, 50 and 100 mg/dm3 chloride concentration are presented. The simulated solution was prepared by «Ekstra» table salt dilution in distilled water. The tests were carried out within 10–500 A/m2 current density range. The concentration of active chlorine is increasing alongside with the electrolysis time. It is stated that at the preset values of anodic current density active chlorine of different concentrations can be obtained, e. g. up to 220 mg/dm3 at 100 A/m2 current density and 100 mg/dm3 chloride concentration. The process is notable for the amount of generated active chlorine exceeding the stoichiometric chloride concentration in water in process up to 1.7–1.9 times; this can be caused by the formation of other oxidants, e. g. hydrogen peroxide. At the current density less than 500 A/m2 the output of active chlorine decreases. According to the experimental results a nomogram for determining the active chlorine current yield depending on the chlorine concentration in the solution and current density is proposed.
Key words
sodium hypochlorite , chlorides , underground and surface water , direct water electrolysis , oxidants , current density
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UDC 628.17.001.4
Pchel'nikov I. V.
Research and development of the technology for the production of electrolytic sodium hypochlorite by electrolysis of seawater
Summary
Chlorination continues to be the most widely used method of water disinfection in the world owing to the sanitary-hygienic reliability, relative simplicity and economic efficiency. The toxicity of chlorine, the need for the transportation through the residential areas, as well as storage under excessive pressure served as the basis for the search for alternative ways to ensure industrial safety and anti-terrorist sustainability of water supply systems. Among the chemicals alternative to chlorine, electrolytic sodium hypochlorite obtained at the point of consumption by electrolysis of an aqueous solution of sodium chloride takes the first place. The use of natural water containing chlorides as a raw material for the production of sodium hypochlorite is most promising. The use of natural water simplifies essentially the process flow scheme and provides for abandoning the purchase of sodium chloride which reduces the cost of the finished product. The results of research and development of the technology for producing electrolytic sodium hypochlorite by direct electrolysis of the Black Sea water are presented. The expediency of the technology was experimentally confirmed and the optimal conditions for the production of sodium hypochlorite by electrolysis of seawater were determined. The results of the study of deposits formed on the cathodes during the electrolysis of the Black Sea water are presented. Recommendations for the selection of process flow schemes for the production of sodium hypochlorite by electrolysis of seawater have been compiled.
Key words
disinfection , sodium hypochlorite , sea water , electrolyzer , direct electrolysis of seawater , electrode
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DOI 10.35776/MNP.2019.10.01
UDC 628.166:661.417/.418
Pchel'nikov I. V., Terikov A. S., Nguen Tkhi Tuan Z’ep, Shchukin S. A.
The study of direct electrolysis of water in the Vietnam Sea
in the production of sodium hypochlorite
Summary
Electrochemical sodium hypochlorite is used at water supply facilities all around the world. The use of natural waters containing chlorides as a raw material is very promising since it greatly simplifies the process flow scheme for producing sodium hypochlorite. Direct electrolysis technology can be retrofitted into the existing water treatment schemes without significant changes. The use of natural water containing chlorides eliminates the purchase of salt which reduces the cost of the finished product. The results of studies of direct electrolysis of water in the Vietnam Sea are presented. During the experiments the effect of seawater flow rate and current density on the concentration of active chlorine in the resulting sodium hypochlorite, the change in the current chlorine yield and the specific energy consumption per 1 kg of generated active chlorine were determined. The main process parameters are determined that provide for producing sodium hypochlorite by direct electrolysis of sea water using an iridium-ruthenium oxide titanium anode as electrodes. It was shown that the current chlorine yield reaches maximum values (85–90%) at an active chlorine concentration in the product of 2 ± 0.2 g/dm3 which motivate the technological and economic feasibility of obtaining sodium hypochlorite from sea (ocean) water.
Key words
sodium hypochlorite , chlorides , sea water , direct water electrolysis , current density
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UDC 628.237.2:628.521
Tcherkesov A. Yu., Shchukin S. A., Israilov R.
Study of removing hydrogen sulfide from ventilation
and sewage gas-air emissions by absorption cleaning
Summary
The results of studying the removal of hydrogen sulfide from ventilation and sewage gas-air emissions by absorption cleaning on a packing irrigated with sodium hypochlorite are presented. The studies were carried out in a laboratory setup. The subject of research was artificially prepared gas mixture of air and hydrogen sulfide obtained by dosing hydrogen sulfide solution into acidic solution (gas generator). Variation of the hydrogen sulfide concentration in the air was achieved by changing the feed from a hydrogen sulfide-containing solution dispenser. The laboratory setup included an absorber with a volumetric packing made on the model of Raschig rings. Chlorine-containing 0.3% sodium chloride solution was used as the absorption solution. The regeneration of active chlorine (reduced by hydrogen sulfide to chlorides) in the absorbent was carried out by direct electrolysis in a flow-through electrolyzer installed in the line supplying the absorbent to the absorber. The actual dose of active chlorine for the oxidation of hydrogen sulfide absorbed by the absorbent was determined. The main dependences describing the chemisorption of hydrogen sulfide and the electrochemical regeneration of sodium hypochlorite in the absorbent are presented. A method for calculating the absorber of the laboratory setup is presented. Specific electricity consumption for removing hydrogen sulfide from air was determined. In the follow-up studies the obtained results will provide for calculating the costs of air purification, estimating the operating costs and conducting an engineering and economical comparison of the proposed and competing methods of removing malodorous substances from ventilation emissions from sewer facilities. The presented method can be recommended in the schemes for cleaning ventilation emissions at the wastewater treatment facilities.
Key words
sodium hypochlorite , reeking substances , hydrogen sulfide , absorption , cleaning of ventilation emissions
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UDC 621.357.1:628.162.8
KINEBAS A. K., JAKOVLEV V. Ju., NEFEDOVA E. D., Lobanov Fedor
Water Disinfection with Weak Sodium Hypochlorite at Water Supply Stations of St. Petersburg
Summary
The method of water disinfection with sodium hypochlorite produced from common salt solution using the electrolysis method at the place of use has been introduced at two largest water supply stations, Southern and Northern, of St. Petersburg. The use of sodium hypochlorite of low concentration makes it possible to avoid the necessity of transportation and long-term storage of a ready solution. The technology introduced makes it possible to minimize considerably the risk existing in the case of the use of liquefied chlorine and reduce the operation expenses comparing with strong solutions of sodium hypochlorite.
Key words:
disinfection , sodium hypochlorite , weak solution , electrolysis , common salt , softened water , process automation
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UDC 628.166:628.1.033 (470.61-25)
FESENKO L. N., Ignatenko S. I., Skryabin A. Yu., Fedotov R. V.
Ensuring of Wastelessness and Ecological Compatibility of Technology of Sodium Hypochlorite at the ChlorefsUnits
Summary
The ways of solving the problem of ensuring of wastelessness and ecological compatibility of the technology of large-tonnage production of sodium hypochlorite at electrolysis stations of high-capacity water treatment facilities are considered. It is shown that for conditioning of water used for preparation of salt solutions the method of acid decarbonization is more preferable as excluding the generation of some accompanying waste water. It is considerably cheaper than the cationite softening and makes it possible to use the salt of any quality. The saturators for preparation of saturated salt solution should be equipped with the washing systems similar to high-rate water supply filters with wash water discharge into the system of treatment and its reuse in the scheme of dissolution.
Key words
disinfection , sodium hypochlorite , electrolysis , wash water , dissolution , cationite softening , decarbonization
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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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UDC 628.166
KINEBAS A. K., Kostyuchenko S. V., Portnova T. M., Mikhailov V. V.
Experience of drinking water disinfection in Saint-Petersburg
Summary
The experience of the SUE «Vodokanal of St. Petersburg» activities in the field of retrofitting the technology of two-stage disinfection of drinking water with sodium hypochlorite and UV-irradiation is presented. The concept of ensuring guaranteed safety of the drinking water supply in and around Saint-Petersburg is described. The upgrade of the water disinfection system was carried out at the operating facilities eliminating any decrease in purification efficiency and waterworks capacity. The water treatment facilities use «A» trademark sodium hypochlorite and low-concentrated sodium hypochlorite (NaOCl) manufactured at the factories at the Southern and Northern Waterworks. The process of sodium hypochlorite production includes: salt storage, preparation of saturated salt solution, preparation of softened water, preparation of 3–4% (mass.) concentration work salt solution, production of 0.8% concentration (mass.) sodium hypochlorite, sodium hypochlorite storage in two tanks. The process of NaOCl production is operated in automatic mode. In order to affect efficiently the entire spectrum of microorganisms including bacteria, viruses and protozoan cysts UV-irradiation is used. The outstanding feature of the UV-disinfection plants at the facilities of SUE «Vodokanal of St. Petersburg» is the fact that the UV-equipment is installed at the point of drinking water supply to the distribution network (the contact time is less than 1 minute). The reliability of water disinfection is ensured by the selected method of UV-irradiation of thin water layer. Beginning from 2017 the equipment operation and irradiation dosage monitoring has been carried out in automatic mode. The analytical equipment installed at the facilities was manufactured in Saint-Petersburg.
Key words
potable water , sodium hypochlorite , ultra-violet irradiation , water supply plant , sanitation-and-epidemiological safety , liquid chlorine
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UDC 628.162.84.004.1
Sivolov G. E., Karmalov A. I., Medrish G. L., Piskov M. V., Panchuk S. A., Zorin A. P.
Experience in Operation and Enhancement of Water Disinfection System with the Use of Sodium Hypochlorite
Summary
Over ten years ago at the water treatment facilities of the city of Seversk the operation of the disinfection system with the use of liquid chlorine was converted to the use of sodium hypochlorite. At present the modernization of equipment due to the application of aerohydrodynamic mixers was made, the processes of mixing the reagent with water being treated were intensified, the operation of reagent facilities was completely automated including the dosing of sodium hypochlorite proportional to water flowrate.
Key words
disinfection , filter , sodium hypochlorite , water treatment , computerization , aerohydrodynamic mixer
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UDC 628.237.2:628.521
DOI 10.35776/VST.2023.10.03
Tcherkesov A. Yu., Israilov R.
Removing malodorous substances from gas-air mixtures in wastewater disposal systems
Summary
A scientific justification is given for the use of the method of hydrogen sulfide absorption by aqueous media containing an oxidizer – hypochlorite ion, obtained electrochemically in a stream of reusable absorption solution, in a countercurrent absorber for gas-air mixture purification in wastewater disposal systems. The results of theoretical and experimental studies of the influence of operational factors on the efficiency of removing hydrogen sulfide from gas-air mixtures using the proposed method are presented. Recommendations for using the method are given. A process flow scheme for gas-air mixture purification in wastewater disposal systems using the method of hydrogen sulfide absorption by aqueous media containing an oxidizer – hypochlorite-ion, as well as the process parameters for its application, are presented. The results of estimating the economic efficiency of the developed technology are provided.
Key words
sodium hypochlorite , hydrogen sulfide , absorption , gas cleaning , absorbent , absorber
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UDC 628.16.081:628.161.2
Seliukov Aleksandr, Raff P. A., Semenov Mikhail, Mishina T. F.
Pilot testing the technology of low-turbid colored water conditioning in the process of two-stage filtration
Summary
The results of the pilot tests of the technology of low-turbid colored water conditioning by two-stage filtration are presented. The tests were carried out to specify the parameters of the technology being developed and to determine the effectiveness of water purification of the Zeya River (Amur Region) with a view to its use in domestic and industrial water supply of the designed industrial facility. During the test period the river water was characterized by low temperature (3.5–7.5 °С), low pH values (6.5–6.7) and alkalinity (0.4–0.5 mg-eq/dm3) with color up to 80 degrees. To specify the chemical dosages preliminary (laboratory) tests were carried out. It was established that the treatment of river water with sodium hypochlorite provided for a noticeable bleaching effect – up to 40%. However, increasing the oxidizer dosage to more than 10 g/m3 is ineffective. At the specified river water color the dosage of chemical can be set within 5–7 g/m3. Owing to low alkalinity values it is recommended to alkalize water with soda ash at an optimal dose of 6 g/m3. According to the results of the test chemical treatment of water the preference was given to Aqua-Aurat™30 coagulant at doses of 35–40 g/m3. By comparison of the flocculants of Praestol group, Praestol 650TR showed the best results at doses of 0.1–0.15 g/m3. Pilot tests of purifying Zeya river water proved the high efficiency of the two-stage filtration technology (contact prefilter + rapid filter). The use of Aqua-Aurat™30 coagulant in combination with Praestol 650TR flocculant ensured the standard quality of drinking water, as well as the quality required for industrial water supply of the designed industrial facility.
Key words
sodium hypochlorite , water treatment , coagulant , flocculant , low-turbid colored river water , two-stage clarification , soda ash
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UDC 628.16.087
FESENKO L. N., Skryabin A. Yu., Bessarabov S. Iu., Pchel'nikov I. V., Ignatenko S. I.
Utilization of concentrate from reverse osmosis units in the production of electrolytic sodium hypochlorite
Summary
Owing to high efficiency and minimum chemical consumption reverse osmosis and nanofiltration have been widely used in process flow schemes of drinking water demineralization and softening and water preparation for industrial use (in steam boiler-houses, recycling cooling circuits, heat network make up etc.). However, the methods of membrane separation are accompanied by concentrate generation which is very difficult to process and utilize. The data on utilization of concentrates of membrane separation units with obtaining chloride-sodium raw material for the production of electrolytic low-concentrated sodium hypochlorite is presented. Since the waste stream of reverse osmosis units contains elevated concentrations not only of chloride ions but also of Са2+, Mg2+, НCO3- and SO42- ions it would be reasonable at the first stage to reduce the amount of process concentrate by repeated concentrating as per flowchart «nanofiltration-reverse osmosis». Further on the concentrate of nanofiltration containing mainly Са2+, Mg2+ and SO42- divalent ions is subject to chemical treatment as per flowchart: at the first stage with barium compounds; at the second stage with sodium carbonate and hydroxide. This will allow separating practically insoluble BaSO4 from the solution with its precipitation in a vortex reactor or first-stage lamellar separator; then CaCO3 and Mg(OH)2 low-soluble in alkaline environment are precipitated in the second stage reactor. BaSO4, CaCO3 and Mg(OH)2 insoluble salts removed from the mass balance are dewatered in a filter-press and sold as commodity or raw products. Aqueous solution of sodium chloride is repeatedly concentrated by three-stage reverse osmosis to obtain 2–2.5% aqueous solution of table salt – high-grade raw material for the production of electrolytic sodium hypochlorite with 6–8 g/l chlorine equivalent concentration. Chlorine-containing product can be used for drinking and waste water disinfection, biocidal processing of cooling towers, heat exchanging units for preventing and removing biofouling, washing ultra-and microfiltration membranes, disinfecting water treatment facilities and equipment, pipelines and other components used in the production of drinking and process water.
Key words
sodium hypochlorite , concentrate , reverse osmosis , nanofiltration , desulfatation , chemical softening
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UDC 628.166.094.3
FESENKO L. N., Ignatenko S. I., Pchel'nikov I. V.
Improving the technology of sodium hypochlorite production by seawater electrolysis
Summary
An alternative method of low concentrated sodium hypochlorite production by seawater electrolysis in substitution for sodium hypochlorite produced by the traditional technology from table white salt solution is considered. The results of studying sodium hypochlorite production by electrolysis of the natural Black Sea water, model Black Sea water in comparison with 3% table white salt solution are presented. The effect of physical and chemical parameters of seawater electrolysis on the amount of generated active chlorine was experimentally investigated. The chemical composition and structure of cathodic deposits formed with time during the electrolysis of seawater, decarbonated seawater and 3% table white salt solution were determined. Comparative evaluation of corrosion and electrochemical characteristics of metal-oxide anode coatings (oxide ruthenium-titanium anodes and oxide iridium-ruthenium-titanium anodes) at seawater and 3% NaCl solution is presented. The expediency of producing sodium hypochlorite by seawater electrolysis was experimentally confirmed and the optimal process conditions were determined. The optimal composition of metal-oxide anode coatings used in low concentrated sodium hypochlorite by seawater electrolysis was determined. Based on the results of research and experimental studies the recommendations for the selection of process flow schemes of sodium hypochlorite production by seawater electrolysis in circulating and flow operation modes were prepared, and the sound fields of their application were justified. The technical and economic assessment of the recommended technology was carried out.
Key words
disinfection , sodium hypochlorite , electrolysis , sea water , gaseous chlorine , oxide ruthenium-titanium anode , iridium-ruthenium-titanium anode
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UDC 628.1.033:66.094.413
Zholdakova Z. I, Lebed’-Sharlevich Ia. I., Mamonov R. A., Sinitsyna O. O.
Enhancement of the requirements to monitoring the safety of drinking water during chlorination
Summary
Oxidative methods involving the use of chlorine and sodium hypochlorite are most widely used for water disinfection. At the same time the regulatory requirements included into the sanitary and epidemiological legislation do not fully reflect the requirements to monitoring their use. A comparative analysis of scientific, technical and methodological literature, as well as of the statutory documents regulating the parameters of the effectiveness and safety of drinking water disinfection with chlorine showed that in the process of developing the first SanPiN 2.1.4.559-96 an exact definition was neglected. It consisted in the fact that the quantitative indicators of these parameters shall not stipulate mandatory simultaneous presence of free and combined residual chlorine in water. The data on the in-process control of drinking water at the water treatment plant in the city of Perm showed no need to maintain the concentration of residual free chlorine at 0.3–0.5 mg/l granting residual combined chlorine in the range of 0.8–1.2 mg/l is available. In this regard it is advisable to introduce appropriate updated requirements for monitoring the concentrations of free and combined chlorine in drinking water in SanPiN 2.1.4.1074-01. When water is chlorinated with gaseous chlorine and sodium hypochlorite a large amount of hazardous halogen-containing volatile and semivolatile compounds including carcinogenic are formed. However, water quality control is carried out only for certain volatile substances. A differentiated approach to the selection of indicators for monitoring the concentration of halogen-containing compounds taking into account the characteristics of raw and disinfected drinking water is recommended.
Key words
chlorination , sodium hypochlorite , water disinfection , chlorine-containing compounds , chlorine , requirements to monitoring , residual free and combined chlorine
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