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

Comparative evaluation of the economic effectiveness of using chlorine-containing media in water disinfection technologies

Summary

An engineering and economic comparison of three methods of water disinfection using: gaseous chlorine, high concentrated sodium hypochlorite and low concentrated sodium hypochlorite is presented. A comparative analysis was carried out using the example of an operating chlorination plant located on the territory of the wastewater treatment facilities in the city of Leninsk-Kuznetsky, Kemerovo Region. The economic analysis has shown that the use of low concentrated sodium hypochlorite compared to high concentrated sodium hypochlorite is beneficial, as the payback period is reduced. This confirms the expediency of using this technology since it provides for implementing a socially oriented tariff policy for consumers to a greater extent. Besides, while choosing a chemical, its advantages should be sought in the safety of delivery and storage, technological effectiveness in use, the amount of by-products in the preparation of the product at the place of use, as well as the delivery price of a chlorine-containing chemical or the cost of apparatus that produce it directly at the premises of the water treatment facilities from purchased raw materials.

Key words

gaseous chlorine , low-concentrated sodium hypochlorite , direct water electrolysis , high concentrated sodium hypochlorite , comparative analysis