Reverse osmosis is a process that involves the diffusion of water, at high pressure, through synthetic membranes. Applying a pressure higher than the osmotic pressure, the water is forced through semi-permeable membranes in the opposite direction to that of natural osmosis. In this process, the water molecules pass through the membranes, but most of the dissolved salts and undesirable substances are retained. Like demineralization, reverse osmosis produces high-quality water.
The feedwater flow into a reverse osmosis system originates two currents:
Pre-treatment of water before entering the reverse osmosis is required, which varies according to the characteristics of the available water. Different filtration techniques can also be combined with membranes. The rate of recovery of the process depends on the quality of the feedwater and the membranes.