Studying the processes of sulphates and chlorides extraction from water at low-waste water demineralization technology

Abstract

To solve the disposal problem of high-salinity liquid wastes resulting from the water demineralization, researched are the processes of chlorides’ and sulphates’ ion-exchange separation with further sulphates (in the form of calcium sulphate) removal from the technological cycle. It is shown that the desulphatized water can be effectively desalinated by reverse osmosis filters, including low-pressure membranes Filmtec TW30-1812-50. The liquid waste obtained in form of concentrates,  does contain chlorides, sodium ions and hardness ions. Established is that at these concentrates processing by lime and sodium carbonate or alkali and sodium carbonate they are softened  with hardness decrease up to 0,25…0,95 mg-eq/dm3, which allows these solutions’ further electrolysis to obtain alkali and hydrochloric acid. Through direct electrolysis of concentrates, obtained by reverse osmosis water desalination at anionic membrane two-chamber electrolysers, we obtained a disinfectant solution containing chlorine oxigenates (active chlorine, hypochlorite, chlorite and sodium chlorate) and duly effective in water sterilization. The resulting solution well keeps its properties and is promising for disinfection of natural and waste waters.