UDC 628.166.085
DOI 10.35776/VST.2023.03.06

Bogun P. V.

Effect of the reflection from the reactor walls
on the energy efficiency of UV water disinfection units

Summary

The results of a theoretical study of possible improving the effective dose of irradiation in a water disinfection unit with ultraviolet (UV) radiation without increasing the lamp power, as well as studying the effect of the radiation reflection from the reactor inner surface on the operation of the disinfection units are presented. The calculations were carried out for the most popular design with one lamp and a cylindrical reactor with specular reflection from the walls. The calculations have shown that at a high reflection coefficient of radiation and at certain ratios of the effective length of the propagation of UV radiation in water and the dimensions of the reactor, the energy efficiency, i. e., the plant capacity per unit of power consumed, can be increased by 35–40 % compared to the already known designs.

Key words

energy efficiency , water disinfection , ultraviolet irradiation , effective length of radiation propagation

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UDC 628.1/.2(98)

Kofman V. Ya.

Water supply and wastewater disposal in the Arctic Region:
advanced technical soltions (a review)

Summary

In Canada wastewater treatment technology has been developed for small isolated arctic communities based on the effective biodegradation of organic carbon using a combination of anaerobic methanogenic and microbial bioelectrochemical processes that provide for biomethane generation. Microbial electrochemical degradation is executed in a membrane-free flow-type reactor with a bioanode and a biocathode operating at a voltage below the threshold of water electrolysis. In laboratory-based experiments in a wide range of mesophilic and psychrophilic temperatures (5–23 °C) a high efficiency of reducing BOD₅ (90–97%) was achieved with a residual content of less than 7 mg/l. Energy consumption is 0.6 kWh/kg COD. Low energy consumption along with the production of biomethane ensures the operation of the reactor in the mode of power generation. For the conditions of Greenland a scheme of wastewater disinfection involving chemical coagulation and addition of peracetic acid, and/or ultraviolet irradiation was developed. Complete inactivation of Escherichia coli is achieved with the combined use of ultraviolet radiation (2.1 kWh/m³) and peracetic acid. Preliminary coagulation is an essential prerequisite for the effective inactivation of microorganisms. In the United States a closed water treatment scheme based on the peroxone process with reuse of water for drinking purposes has been proposed for the city of Fairbanks (Alaska). The big advantage of the closed-loop scheme is 85% conservation of the water in the system while preserving the thermal energy obtained from different water heaters. As a result the purified warm water is returned to the consumer; while less energy is required for its additional heating. In addition, the mineralization of organic substances in the oxidation process ensures the achievement of 0.7 mg/l residual COD.

Key words

wastewater , water disinfection , water treatment , ultraviolet irradiation , water reuse , the Arctic Region , preliminary coagulation , peracetic acid , peroxone process , heat energy of water , anaerobic methanogenic process , microbial electrochemical process

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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 628.166

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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УДК 628.166

Kofman V. Ya.

Новые подходы к обеззараживанию воды
(обзор)

Summary

In the process of using traditional methods of water disinfection with chlorine containing disinfectants or ozone byproducts of different toxic effect are formed. As alternative water chemical oxidants-free water disinfection methods and methods characterized by lower disinfection byproducts formation are developed. In this regard photocatalytic water disinfection process with ultraviolet irradiation or visible light impact; microorganism inactivation with the use of nanomaterials in the form of titanium dioxide, silver nanoparticles, fullerenes, graphene, carbon nanotubes, peptides and chitosan, as well as ferrate process are most intensively investigated. The given process flow schemes have certain advantages also in microcystine destruction. The mechanism of microorganism inactivation is considered. Technical problems that have to be solved to expand the practical use of alternative water disinfection methods are presented.

Key words

water disinfection , photocatalytic process , nanotechnologies , titanium dioxide , silver nanoparticles , carbon nanotubes , graphene , peptides , chitosan , fullerenes , ferrate process , microcystine destruction

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UDC 628.166.085

Bogun P. V.

On increasing the capacity of UV-units for liquid disinfection

Summary

The results of theoretical studies of the possible capacity improvement of units for disinfecting liquids including water by ultraviolet irradiation eliminating any increase in energy consumption are presented. Capacity improvement is possible at the fixed reactor geo­metry and source strength owing to the redistribution of liquid flows in the reactor. It is shown that the maximum possible efficient radiation dose is equal to the mean by reactor volume radiation intensity multiplied by the mean time of liquid residence in the reactor. The necessary and sufficient condition for obtaining this dose is the availability of liquid flow in every point of the reactor volume and equal radiation dose for every microvolume of liquid. By way of example the calculations of the maximum possible radiation dose for a spherical reactor with a point source of radiation and for a cylindrical reactor with a linear radiation source are presented. It is noted that widely manufactured at present UV water disinfection unit designs with a single source (a lamp) use only 30% of the source capa­city. The design with a cylindrical reactor and spiral downward liquid flow distributed along the reactor length provides for the maximum possible radiation dose and/or capacity of the installation.

Key words

water disinfection , ultraviolet irradiation , irradiation dose , reactor , installation capacity

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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УДК 628.166

Platonov M. M., Kochelaeva G. A.

Optimization of drinking water chlorammoniation process

Summary

Water disinfection is the most important function of the public water supply. Chlorammoniation used for this purpose has a number of advantages compared to the traditional chlorination. However, it sets raised requirements to the analytical control instruments which limit the automation potential. Different control parameters are considered in relation to their possible application for the automation of the disinfection process. It is shown that the best parameter indicative of the optimal conditions of the process is the concentration of free ammonium. To choose a method of measuring free ammonium under the conditions of chlorammoniation at the existing water supply facilities tests on monitoring free ammonium by different methods were carried out. The limitations of some laboratory techniques are shown together with the advantages of the method using a gas-selective electrode, particularly in automatic analysis. The method of free ammonium monitoring with the use of an automatic analyzer with a gas-selective electrode has a number of advantages: a clear criterion of the optimal process conditions; the lowest absolute error of the measurements; possible use of the method for the automation of chlorine (ammonium) dosing. The operational tests showed the efficiency of the given method of the process control, reliable operation of the analyzer and good repeatability in relation to the laboratory data.

Key words

water disinfection , chlorammoniation , free ammonium , gas-selective electrode , automatic analysis

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UDC 628.166.085

Kostyuchenko S. V., SMIRNOV A. D., Tolstoi M. Iu.

Domestic technologies and equipment for chemical free treatment of water and wastewater of the Siberian cities and industries

Summary

The chemicals used in liquid and gaseous media treatment and purification either stay intact in the processed environment or disinteg­rate and react with the processed environment or admixtures in it and form numerous secondary and often toxic products. In this context chemical free methods of media purification aiming at their environmental safety are of most interest. Chemical free methods of treatment do not result in the formation of such a big amount of secondary products; whereas the efficiency of their use is often higher because they less depend on the type and structure of the targeted substance or admixture as well as on the conditions of use. Ultraviolet irradiation has been the most efficient and widely used method of chemical free disinfection of effluents both in Russia and abroad. The capital expenses for UV-disinfection are significantly reduced since there is no need in constructing contact tanks for chlorination and dechlorination; in addition the absence of chemical consumption eliminates the need in constructing a chemical plant and installing dosing systems. Using the example of the Siberian Region the advantages of using UV-irradiation in wastewater treatment is described.

Key words

ultra-violet irradiation , ecological safety , water disinfection , chlororganic compounds , residual chlorine , dechlorination , chemical free disinfection

DOI 10.35776/MNP.2020.05.01
UDC 628.166.085

Bogun P. V., Kniazeva Elena

Improving the energy efficiency of UV water disinfection systems

Symmary

The performance of a number of ultraviolet water disinfection systems available on the market is analyzed in comparison with systems of the maximum capacity reached as a result of theoretical studies, at the same energy consumption. It is demonstrated that the maximum performance values declared by the system manufacturers are 1.1–2 times less than could be obtained for the same designs, provided the irradiation uniformity of the treated flow is ensured. A technical solution is proposed that provides for the uniform exposure due to the flow velocity distribution that decreases with the distance from the lamp in proportion to a decrease in the average irradiation intensity along the length of the lamp. This solution allows approaching significantly the maximum design performance with the minimal cost and minor changes in the design. The distribution of treated water flows in a system with diaphragms-spreaders that ensure the required flow direction, is investigated. It is demonstrated that for a reactor vessel up to 50 cm long one diaphragm is enough, whereas for larger vessels installing additional flow spreaders can solve the problem. Possible use of the proposed solution for any systems with a longitudinal flow relative to the location of the UV lamps is shown.

Key words

ultraviolet , water disinfection , flow rate , irradiation dose , UV-lamp , flow spreader

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UDC 628.166:661.418
DOI 10.35776/VST.2024.02.08

Pchel'nikov I. V., Pchel’nikova Anastasiia, Kaberskaia Dar’ia, Kuz’menko Liudmila

Production of sodium hypochlorite by ground water electrolysis

Summary

Possible using groundwater to prepare a disinfecting chemical – sodium hypochlorite – has been considered. The use of natural water containing chlorides provides for eliminating the purchase of table salt and reducing the cost of the finished product by up to 40%. However, due to significant differences in the composition of natural waters, particularly, related to the concentration of chloride ions, the electrolysis of mineralized water can occur in an inefficient zone with high power consumption and low yield of active chlorine. On the territory of the Municipal Enterprise «Azovvodokanal» (Azov, Rostov region) an electrolysis plant is located with a capacity of 500 kg/day as active chlorine. The raw material for the production of sodium hypochlorite is mineralized groundwater. In the course of studies, the optimal conditions for the electrolysis of groundwater were established in order to determine the maximum current efficiency by chlorine with the minimum energy consumption. The studies were carried out using direct electric current in a flow-through mode at a current density of 10, 50, 100, 200, 500, 800 and 1000 A/m², and an initial solution temperature of 18–22°С. The working areas of the anode and cathode were 0.0022 m² each. The range of flow rates studied varied from 0.36 to 4.8 l/h, which corresponded to an electrolysis time of 3.5–0.26 min. The pH value during electrolysis ranged from 8.8 to 9.5. As a result of the studies, dependencies were obtained that characterize the parameters of the direct electrolysis of ground mineralized water.

Key words

water disinfection , membraneless electrolysis , low-concentrated sodium hypochlorite , direct electrolysis of ground water

UDC 628.166.094.3:661.418
DOI 10.35776/VST.2023.06.01

FESENKO L. N., Pchel'nikov I. V., Pchel’nikova Anastasiia

Direct electrolysis of underground water in production

Summary

The results of production tests of flow-through electrolyzers operating in the mode of direct electrolysis of natural surface water are presented. In the process of electrolysis, sodium hypochlorite for disinfecting water is synthesized from the chlorides present in the source water. Electrolyzers are a part of the water treatment plant. Krinitsa-45 block-modular water treatment plant with a capacity of 45 m³/day has been in operation since 2020. Flow-through electrolyzers are used for the disinfection of raw water (primary disinfection) and drinking water (secondary disinfection) by direct electrolysis; they operate with current reversal in automatic mode. The oxide coating of the electrodes is OIRTA (oxide-iridium-ruthenium-titanium anode) with the addition of tantalum. In the course of studies, the process parameters of the operation of the electrolyzers were determined. The current density was changed from 25 to 75 A/m², the concentration of active chlorine was determined, and the change in the voltage on the electrolyzer terminals was recorded. The measurements were taken every fortnight during past three years. Current density 40–50 A/m² was considered as optimal in terms of efficiency since it provided for 10–12% current efficiency by chlorine and 2–2.8 mg/dm³ active chlorine concentration. Using current reversal (polarity reversal time +1 hour and –1 hour) provided for operating a flow-through electrolyzer with natural water with a total hardness of about 9–11 meq/dm³ eliminating the use of hydrochloric acid for regular washing of the electrodes.

Key words

water disinfection , membraneless electrolysis , low-concentrated sodium hypochlorite , direct electrolysis of surface water

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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

UDC 628.166:661.418
DOI 10.35776/VST.2024.02.07

FESENKO L. N., Pchel'nikov I. V., Ignatenko S. I., Skryabin A. Yu., Kaberskaia Dar’ia, Zaichko Dmitrii

Engineering-economic analysis and study of acid washing of electrolyzer cathodes with solutions of hydrochloric and sulfamic acids

Summary

Experience in operating electrolysis plants shows that the main problem with the reliability of their operation is associated with insoluble compounds – CaCO₃, CaSO₄, Mg (OH)₂ – buildup on the surface of the cathodes that cause abnormal electrolysis mode, overheating and warping of the electrode system, destruction of the oxide coating of the anodes, sudden reduction in the plant efficiency etc. The greatest effect on the liquid salts and gypsum buildup during the electrolysis of salt solutions is produced by the chemical composition of water that is associated with the presence of Ca²⁺, Mg²⁺, HCO^-₃, SO₄ and dissolved CO₂ ions. The method used in practice to remove carbonate deposits by regular washing the electrode system with 3–5% solution of hydrochloric acid is not always economically justified, particularly, for the water sources characterized by increased carbonate hardness. An engineering-economic comparison of two methods of acid washing of electrode plates of an electrolysis plant with solutions of hydrochloric and sulfamic acids while dissolving in them the accumulated buildup resulted from the preparation of sodium hypochlorite from a 3% solution of sodium chloride is presented. With a slightly higher cost of 1 liter of 5% sulfamic acid (6.9 rubles/l) compared to 5% hydrochloric acid (5.36 rubles/l), the cost of one washing with sulfamic acid (2.9 rubles) is 6 times higher than the cost of one washing with hydrochloric acid (0.48 rubles), which is associated with different possibilities for reusing acids for the next washing of the electrolysis plant. In other words, if 5% hydrochloric acid (HCl) can be used 11.1 times before its neutralization, then 5% sulfamic acid (NH₂SO₃H) can be used only 2.4 times, or 11.1/2.4 = 4.6 times less, which is illustrative of the obvious economic preference of hydrochloric acid over sulfamic acid.

Key words

water disinfection , membraneless electrolysis , acid-washing , low-concentrated sodium hypochlorite

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UDC 628.16.065.2 (282.247.33)

Linevich S. N., Breus S. A.

Efficiency of Natural Water Disinfection in the Course of Coagulation Treatment

Summary

Results of experimental and theoretical studies of the coagulation treatment of the Don water and monitoring of the concomitant process of its disinfection are presented. The mechanism of separation of algae, bacteria and viruses from water due to their sorption on aluminium hydroxide generated in the course of coagulation is described. The best effect of water disinfection observed during electrocoagulation is 93,8%. The use of this method makes it possible to abandon the primary water disinfection with chlorine, exclude a large-size reagent services and improve the ecological situation in connection with reduction of the volume of the generated sludge (waste of coagulation process).

Key words

coagulation , ecology , computerization , electrocoagulation , water disinfection , disinfection efficiency