Study and engineering and economic comparison of chemical methods of softening the Bolshoi Kinel River water

Summary

Softening water for domestic water supply can be carried out by different methods including the addition of alkaline agents into water. Experimental studies of the use of lime-soda and caustic soda methods for softening the Bolshoi Kinel River water that is the source of drinking water supply for the city of Otradny, Samara Region, have been carried out by the employees of EKOFES SPE LLC in the laboratory and working environment. A diagram of a laboratory setup has been developed consisting of a mixer with aeration and an air separator, a vertical sedimentation tank with laminar modules, and a rapid filter. Experimental studies on the effect of chemical doses on the values of residual water hardness and total dissolved solids have been carried out. It has been established that the caustic soda method provides for efficient water softening, however results in an increase in the total dissolved solids, thus limiting the area of application. The results obtained in the study of the lime-soda method allow to conclude that the technology is advantageous owing to the elimination of extra water salinization and to recommend it for softening the water of the Bolshoi Kinel River. The engineering and economic calculation of the cost of 1 m³ of processed water depending on the softening method is presented.

Key words

drinking water supply , chemical softening , water hardness , lime-soda softening method , caustic soda softening method