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Number 9 / 2020
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DOI 000000
UDC 628.161.3
Fedotov R. V.
Removal of silicon compounds from underground water by filtration through a modified media
Summary
A brief analysis of water desiliconization technologies is given. The results of experimental studies on the removal of silicic acid compounds from water by filtration through a modified media are presented. It is shown that the use of a filtering media made of activated alumina modified with 0.5% sodium aluminate solution acquires a sorption capacity twice as high as the media regenerated with alkali in relation to orthosilicates, and provides for 95–97% water desiliconization while reducing in-parallel the water hardness. The sorption capacity of the modified activated alumina in relation to silicon is 16kg in terms of SiO2 per 1 m3 of sorbent, which is twice as much in silicon holding capacity compared with the technology of desiliconization by regeneration of activated alumina with caustic soda. The working exchange capacity of the modified activated alumina in terms of the absorbed total hardness is 300–350 g-eq/m3, which is comparable to sulfonated carbon and KU-1 cation exchanger. A non-waste technology of desiliconization of groundwater with re-using the modifying chemical agent generated in the form of dehydrated crystalline aluminosilicate as a commercial raw material for the production of ceramic products has been developed.
Ключевые слова
potable water , filtration , sodium aluminate , desiliconization , activated aluminum oxide , alumosilicate sludge , media modification
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DOI 000000
UDC 628.17.001.4
Babaev A. A.
Removing hydrogen sulfide from water with air oxygen
by the method of «dry» filtration in anthracite media
Summary
One of the causes that limit the widespread use of artesian waters is the presence of hydrogen sulfide. The method of removing hydrogen sulfide from water by converting the ionic forms HS- and S2- into molecular H2S (acidification of water to pH ≤ 5) with subsequent degassing is not environmentally friendly due to air pollution with hydrogen sulfide blown away in the degasser. Oxidation of hydrogen sulfide to elemental sulfur or its oxides is carried out with the use of expensive oxidants that while being applied require special safety measures. An effective chemical free method of removing hydrogen sulfide from water can be the use of an oxidizing filter consisting of a sealed housing partially filled with non-submerged catalytic electrically conductive anthracite media with a grain size of 0.8–2 mm. Air is injected into the distribution perforated water feeding system located above the media. Herewith, the tightness of the filter eliminates the emission of hydrogen sulfide into the atmosphere and pollution of the room, whereas the entire volume of the catalytic media is residing in an oxygen-containing environment in the most active mode of catalytic oxidation of hydrogen sulfide. Purified water is collected at the bottom of the filter in a collector with an air outlet connected to it. After 2–4 days of operation, the filter is removed from the filtration mode to regenerate the catalytic media by back air washing with the removal of elemental sulfur S0 formed during the oxidation of hydrogen sulfide.
Key words
liquid-phase oxidation , «dry» filtration , hydrogen sulfide-containing underground water , anthracite filtering media , air oxygen
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DOI 000000
UDC 628.16:62-278
Vergunov A. I.
Removal of organic compounds from natural water
in a biosorption-membrane unit
Summary
The results of experimental studies on the purification of natural water of the Don River in a biosorption-membrane reactor equipped with flat-plate microfiltration membranes are presented. The research aimed at investigating the efficiency of the biosorption-membrane reactor operating with natural water with the subsequent determination of the kinetic characteristics of the running biosorption process. As a result of processing the experimental results, the efficiency of removing not only the turbidity and color of water, but also organic substances that caused high permanganate index and COD, was specified. The temperature constant was determined that provided for calculating the specific rate of oxidation of organic pollutants for the winter and summer seasons of the year. Using the obtained constants, it is possible to perform a design calculation of a biosorption-membrane reactor to any degree of purification required.
Key words
natural water , microfiltration , domestic water supply , biosorption membrane reactor , specific oxidation rate
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DOI 000000
UDC 628.166:661.833.322.21
Ignatenko S. I.
Equipment manufactured by EKOFES SPE LLC in the field of import phaseout of electrolyzers for the large-scale production of sodium hypochlorite for water disinfection
Summary
Traditionally the sanitary and epidemiologic safety of drinking water is ensured by chlorination that continues to be the most widely used method of water disinfection in the world owing to its sanitary-hygienic reliability, prolonged bactericidal action, relative simplicity and economic efficiency. However, while using liquid chlorine, the problem of its transportation through populated areas and storage of multi-tonnage stocks at the water treatment facilities remains apparent. Low-concentration electrolytic sodium hypochlorite produced at the point of consumption by electrolysis of sodium chloride solution is generally recognized as an alternative disinfectant to liquid chlorine. Those who use foreign technologies and electrolyzers become contingent on foreign service and repair, as well as on the supply of imported components and consumables which causes serious financial difficulties. In addition, foreign companies in the production of sodium hypochlorite use deep-softened Na-cationized water and special salt not lower than Extra brand. The successful promotion of high-efficiency domestic electrolyzers in the field of import phaseout became possible only with taking into account the demands of water utilities for the use of the cheapest and available raw materials (table salt not higher than A-number), as well as for the after-sale service by the supplier and the manufacturer warranty to eliminate unforeseen shutdowns of the equipment, emergency failures or consequences of force majeure in the shortest possible time. The established in Russia (EKOFES SPE LLC) production of high-capacity electrolyzers that are not inferior in their technical and economic performance to foreign counterparts will provide for complete abandoning foreign supplies and implementing import phaseout of this type of equipment by a domestic manufacturer.
Key words
decarbonization , electrolyzer , low-concentration electrolytic sodium hypochlorite , salt dissolver , no-waste technology
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DOI 000000
UDC 628.166:661.418
Guzii V.
Study of the corrosion and electrochemical properties of anodic coatings in conditions of chlorine electrolysis
Summary
Traditionally for water purification and disinfection various oxidizing agents have been used, usually chlorine-containing products including low-concentration sodium hypochlorite obtained by electrolysis of aqueous solution of table salt at the point of consumption. The greatest influence on the electrolysis efficiency (current active chlorine yield), electrical and electrochemical performances, effectiveness of the process and operational practices, design of devices and their durability is exerted by the anode material; the main requirement to it being the chemical resistance in the mode of anodic polarization in the chemically active environment. Ruthenium-titanium oxide anodes have become widely used in practice owing to their high-wearing properties. A decrease in the rate of continuous decrease in the thickness of the active layer and the loss of ruthenium oxide can be achieved by using a three-component coating of the anode with the addition of a platinum group metal – iridium. Three-component coatings of anodes containing iridium (iridium-ruthenium-titanium oxide anodes), with a mass percentage of iridium to ruthenium of 80:20 provide for 8-fold increasing the corrosion resistance of the anodes (service life). As the iridium oxide concentration increases, the anode coatings consume less energy for generating sodium hypochlorite owing to the lower voltage across the electrolyzer. The corrosion resistance of anodes with different ruthenium and iridium oxide fills as well as their characteristics, i. e. chlorine yield in terms of current efficiency, electrolyzer voltage, dynamics of active chlorine concentration increase were determined.
Key words
low-concentrated sodium hypochlorite , oxide coatings , iridium , ruthenium , corrosion resistance of anodes , current chlorine yield , electrolysis of 3% solution of table salt
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DOI 000000
UDC 628.166
Pchel'nikov I. V., Nguen Tkhi Tuan Z’ep
Study of the optimal electrolysis mode while producing sodium hypochlorite from Mediterranean Sea water
Summary
The theoretical substantiation, as well as the research results of developing the technology for producing low-concentration sodium hypochlorite by direct electrolysis of Mediterranean water for the biocidal treatment of the cooling circuit of nuclear and thermal power plants are presented. The optimal process parameters have been determined. Methods for preventing the formation of cathode deposits have been studied. It has been established that during the electrolysis of seawater with an anode current density of 1000 A/m2 the maximum concentration of active chlorine 7.9 g/dm3 can be achieved; whereas at 600 A/m2 – up to 6.8 g/dm3 is achieved on iridium-ruthenium-titanium oxide anodes. The current chlorine yield is within 10%. It has been shown that the current chlorine yield and specific power consumption per 1 kg of generated active chlorine reach their optimum values (85–90% and 3–3.5 kWh/kg) at an active chlorine concentration in the electrolysis product of 2 ± 0.2 g/dm3. This determines the process and economic feasibility of producing sodium hypochlorite from sea (ocean) water.
Key words
disinfection , decarbonization , low-concentrated sodium hypochlorite , membraneless electrolysis , inhibition , acid-washing , electrolysis of Mediterranean water
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DOI 000000
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 000000
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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