Reverse osmosis is a modern process based on the use of semi-permeable membranes that have the property of letting water pass, without letting the substances it contains in solution through.
In physics, by introducing pure water into two communicating vessels, separated by a semipermeable membrane, the water reaches the same level in the two vessels. By adding a salt in vessel B, the water is pushed by a natural force (osmotic pressure) to pass from the saline solution (B) to the solution with lower salinity (A); this important phenomenon is called OSMOSIS.
To reverse the phenomenon, it is sufficient that the water with a high salt content is pushed through the membrane by a pump that exerts a higher and opposite pressure to the osmotic one.
This principle, called “reverse osmosis”, makes it possible to obtain two outgoing flows at different concentrations from a starting saline water flow: the “permeate”, pure water, poor in dissolved salts and micro pollutants, suitable for use and the “concentrate, rich in salinity, which is generally destined for waste.
To reverse the phenomenon, it is sufficient that the water to be treated, with a high salt content, is pushed through the membrane by a pump that exerts a pressure higher than the osmotic one, so as to obtain two outflows: the part of water that crosses the membrane constitutes the permeate (poor in salts) that goes to use, while the remaining part (the concentrate) comes out with a high salt concentration, due to the accumulation of all the salts that have not crossed the membrane, going to waste.
The main applications of reverse osmosis (RO) systems are:
- Food and beverage production
- Pre-treatment for boilers and cooling towers
- Pre-treatment for high purity systems (EDI)
- Biopharmaceutical productions
- Water jet cutting
- Humidification and steam production
- Power generation