The process of movement of solvent through a semipermeable membrane from the solution to the pure solvent by applying excess pressure on the solution side is called reverse osmosis.
Reverse Osmosis (RO) is the tightest possible membrane process in liquid/liquid separation. Water is in principle the only material passing through the membrane; essentially all dissolved and suspended material is rejected. Osmosis separates impurities from water by passing it through a semi-permeable membrane. The semi-permeable membrane allows only very small atoms and groups of atoms (such as water molecules, small organic molecules and gases) to pass through it.
Advanced reverse osmosis technology uses “cross flow” that allows a partially permeable membrane to clean itself continually. As some of the fluid passes through the membrane,
The rest continues downstream, sweeping the rejected species away from it. The process requires a pump to push the fluid through the membrane. The higher the pressure, the larger the driving forces.
As concentration of the fluid being rejected increases, so does the driving force? Reverse osmosis is used to reject bacteria, salts, sugars, proteins, particles, dyes, and other constituents. Separation of ions with reverse osmosis is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane. The larger the charge and the particle; the more likely it will be rejected.
Reverse Osmosis has several advantages, including the following:
