The contribution of membrane techniques with the aim of producing potable water from brackish water without using chemical reactants has become a reality e.g. the supply of the towns of Gabes and Zarzis (south of Tunisia). The utilization of selective membranes CMX/ACS (selective to monovalent ions) allows one to reduce the contents of monovalent ions ( Na+ and Cl- which are responsible for the salinity of water) while reducing only slightly the contents of divalent ions. Experiment shows that low mobility of divalent ions in the membrane phase plays a determining role in ion extraction. A pilot equipped with a filmTec RO membrane (Nanomax 95) alimented with brackish water collected from Zarzis town was operated at 15 bars, 25°C, and up to a water recovery ratio of 50%. The results showed that the RO is actually efficient since it highly reduced the content of inorganic matter present in raw waters (rejection > 95% for the divalent ions and 85% for the monovalent ones ).
K. Walha, R. Ben Amar, F. Quemeneur, P. Jaouen
Brackish water, Desalination, Potable water, reverse Osmosis, Electrodialysis