Several techniques are available for production of drinking water. We use reverse osmosis to remove salts and minerals from sea water, brackish water or contaminated fresh water.
1: OSMOSIS Osmosis is a natural process which induces water to flow from a diluted saline solution and through a membrane to a more concentrated salt solution. The concentrated solution then becomes diluted.
2: OSMOSIS AT EQUILIBRIUM The flow of pure water through the membrane continues until the concentration of salt is equal in both solutions. The difference between the water level in the container, on each side of the membrane, is the osmotic pressure.
3: REVERSE OSMOSIS By applying pressure greater than the osmotic pressure to the concentrated salt solution, the process can be reversed. Pure water will then pass through the membrane and flow into the weaker salt solution. Desalinated water is thus obtained by means of dilution.
The spiral-woven module consists of two sheets of membrane, that are placed on both sides of a channel spacer. The three pieces are then sealed on three sides to form an envelope. The remaining open side is attached to a perforated purified water collection tube. A woven plastic sheet serves as a spacer and is laid on one side of the membrane envelope. The membrane envelope and spacer sheet are rolled up into a cylindrical bundle.