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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 628.162:62-278
Andrianov A. P., Pervov A. G., Efremov R. V., Spitsov D. V.
Selection of efficient inhibitors for process flow schemes of the Black Sea water desalination
Summary
Sea water desalination by reverse osmosis has been widely used in drinking and domestic water supply. However, one of the major problems that complicate the operation of desalination facilities is the deposition of low solubility salts in membrane apparatus. In order to control the formation of crystal sediments on membranes different methods are used. Inhibitor dosing to raw water is the most efficient method. A variety of efficient inhibiting agents has been developed. Lately one of the main directions of studies in this field has been new types of phosphorus free and easily biodegradable inhibitors. Tests of six new phosphorus free inhibitors were carried out; the comparison with traditionally used Aminat-K inhibitor is given. The experimental dependencies that allow determining the rate of calcium carbonate scale formation in membrane apparatus are presented. Basing on the obtained results the optimal operational expenditures for sea water desalination were calculated. The study was aiming mainly at comparing the efficiency of newly developed and traditional inhibitors in the process of their use in sea water desalination schemes (by the example of the Black Sea water simulant). The conclusion of the efficiency of the inhibitors used is made on the basis of the minimum operational expenditures for desalination.
Key words
water treatment , reverse osmosis , inhibitor , desalination , membrane unit , sea water , low solubility salt deposit
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UDC 631.67:628.165
Kofman V. Ya.
The use of desalinated water for the needs of irrigation (review)
Summary
In quite a few foreign countries that suffer from water scarcity (Spain, Israel, Australia, Cyprus, OAE, Chile, China) and that are located in the regions with arid climate noticeable success has been reached or major developments in the field of using desalinated sea or underground water for irrigation have been initiated. The main technologies of water desalination for agricultural needs are reverse osmosis, ion exchange, electrodialysis. The factors that are constraining at this time large-scale deployment of desalinated water in irrigation practice include the high cost of desalination; the need of placing desalination plants close to agricultural fields; discharge of toxic concentrate from desalination process; the need of ensuring safety and remineralization of desalinated water. Quite a few research works in this field have been dedicated to the improvement of the energy efficiency of desalination, development of the improved irrigation schemes and selection of arable crops that could be irrigated with desalinated water with the highest economic benefit. Anyhow the steady increase of investments into the given field in foreign countries indicates that desalinated water can be definitely adapted for agricultural needs.
Key words
ground water , sea water , desalinated water , irrigation , remineralization , calcium , magnesium
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DOI 10.35776/VST.2021.12.04
UDC 628.166:541.135
Pchel'nikov I. V., Nguen Tkhi Tuan Z’ep, FESENKO L. N.
Study of the current waveform effect on the formation of cathode deposits during direct electrolysis
Part 2. Electrolysis of sea water
Summary
Sodium chloride is a raw material for the production of sodium hypochlorite; however, the cost of its purchase and delivery is up to 25–30% of the total cost of the disinfectant produced. An alternative raw material for the production of sodium hypochlorite can be chlorides present in natural mineral water, e. g., underground, sea and oceanic water. Mineral water will be the raw material for obtaining sodium hypochlorite solution of a sufficiently high concentration that can then be added to the treated water. The experience of operating CHLOREFS units manufactured by EKOFES SPE LLC showed that the main problem related to the electrolyzer operation reliability is associated with the formation of deposits of hardness salts – calcium carbonate on the surface of the cathodic electrode, and magnesium hydroxide on the surface of the electrolyzer cathodes. This results in a negative electrolysis regime, an increase in voltage, overheating and warping of the electrode system, destruction of the oxide coating of the anodes, etc. The results of studies of direct electrolysis by direct and reverse current of salt water of the South Vietnam Sea are presented. During the tests the effect of reverse current in comparison with direct current on the reduction of the formation of insoluble substances on the cathodes of the electrolyzer was estimated, and besides, the electrolysis process parameters were determined. The current chlorine yield for seawater was above 100% in the reverse mode with a current density of 100 A/m2.
Key words
disinfection , water treatment , sea water , sodium hypochlorite , direct electrolysis with constant and reverse current
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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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DOI 10.35776/VST.2022.02.03
UDC 628.165:66.081.6
Mazhuga Aleksandr, Kagramanov Georgii, Parusov Denis, Бланко-Педрехон А. М.
Aspects of the desalination of mineralized water in arid
and water-deficient territories
Summary
Supplying drinking water in coastal arid and water-deficient regions has been an urgent problem due to the population growth and progressive pollution of natural waters. To desalinate seawater, evaporation (distillation) or a membrane separation process – reverse osmosis – is usually used. The justification for choosing a seawater desalination method and the productivity of desalination plants is based on the solution of a number of closely related engineering, economic and environmental tasks. Water desalination involves relatively high energy costs; therefore, reducing the costs can be provided by increasing the fuel heat-availability factor, that is, by using cogeneration (cogeneration of heat and electricity). This determines the comprehensive technology of desalination using membrane methods of demineralization followed by the evaporation of the reject water. Herewith, the balance of the reverse osmosis and evaporator plant performance is determined by the ratio of the generated thermal and electrical energy.
Key words
potable water , reverse osmosis , desalination , desalination , evaporation , sea water
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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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