Tag:sodium hypochlorite

№2|2010

PROBLEMS, PERSPECTIVES

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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.

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№9|2014

DRINKING WATER SUPPLY

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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.

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№08|2015

DRINKING WATER SUPPLY

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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.

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№09|2015

DRINKING WATER SUPPLY

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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.

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№8|2018

WATER TREATMENT

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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.

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№3|2010

PROBLEMS, PERSPECTIVES

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UDC 621.357.1:628.162.8

KINEBAS A. K., JAKOVLEV V. Ju., NEFEDOVA E. D., LOBANOV F. I.

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.

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№8|2011

POTABLE WATER SUPPLY

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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.

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№10|2018

DRINKING WATER SUPPLY

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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.

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№9-1|2011

POTABLE WATER SUPPLY

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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.

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№6|2019

DRINKING WATER SUPPLY

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UDC 628.16.081:628.161.2

Selyukov A. V., Raff P. A., Semenov M. Yu., 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.

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№11|2018

WATER TREATMENT

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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.

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№01|2015

DRINKING WATER SUPPLY

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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.

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№7|2019

DRINKING WATER SUPPLY

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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.

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Российская ассоциация водоснабжения и водоотведения

Конференция итог

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