Desalination of Synthetic Brackish and Saline Water by Freezing Technology



Today many countries have water shortage problems, so most of them compel to resort to desalination processes. This paper describes the effect of indirect contact freezing by external cooling for desalination of seawater and brackish water. Although various types of processes are introduced for desalination and such processes as reverse osmosis (RO) and multi-effect distillation (MED) are used commercially, there are also less common processes, like freezing and solar evaporation which in special regions and time may have good applications. In this study 5 synthetic sample of brackish and saline water was made in laboratory and process including freezing, crystallization, and separation, surface washing and melting accomplished on samples. With first freezing of sample at -20 oC, about 58% reduction of Total Dissolved Solid was happened to samples. At firs by one freezing process potable water was not produced but by two successive freezing processes on potable water was produced from first, second, third and fourth sample. Of course it doesn't happen to fifth sample. Accordingly, the TDS of the first water sample with initial dissolved solids concentration of 3066 mg/L had reduced 38% after the first process of freezing and to 84% after the second process of freezing. For second sample with 4775 mg/L TDS, by first and second freezing TDS reduction was 47% and 89% respectively. Third sample with 11900mg/L TDS, by first and second freezing had 65% and 90% TDS reduction and fourth sample with 19000mg/L TDS, by first and second freezing had 69% and 91% TDS reduction.