Silica Removal from Brine by Using Ion Exchange

One of the most widely used processes for water desalination is reverse osmosis (RO), but this process is tied in with one big problem: waste brines, having a high salt concentration. These brines need to be disposed of properly to prevent environmental problems. The reduction in the amount of water, rejected from the RO system, is one of the most important challenges for this process. Alternatives for brine reduction include: disposal, recycling and additional treatment, followed by disposal. Brine recycling is limited by high salt concentration, and the amount of anions such as silica. High silica concentration can clog the membranes used in the RO process, reducing their lifespan and increasing operational costs. In the desalination process, silica is one of the major foulants of RO membranes, representing one of the biggest efficiency limiting factors for water. Silica is a very adherent scale, and it is very difficult to remove once it forms; therefore, the cleaning process may damage the membranes. Several ways to reduce the silica concentration ahead of the RO process have been reported; this reduction is done to maximize process efficiency and; therefore, minimize the brackish waste. The purpose of this work is to evaluate the possibility for silica concentration reduction in brines using the ion exchange process (IE). Resins were tested and the results for silica removal were reported.