Reverse osmosis is a process of water passing through a semipermeable membrane. The water passes from richer to less saturated state under pressure.
Reverse osmosis membranes have a porous structure and are made of thin film composite. Pore diameter (0.0001 microns) is big enough to let water molecules pass, but too small fot ions and molecules of dissolved impurities. Feed pressure, at which reverse osmosis begins to be observed, is called osmotic. This is the external pressure on the membrane, which is necessary to be created by the source water so that water molecules begin to pass through the membrane pores. The higher the pressure of water supplied to the membrane, the greater the degree and speed of filtration. Operating pressure for low-pressure osmosis is 6 ÷ 12 atm, for high-pressure osmosis it is 12 ÷ 16 atm, and for clean sea water at the operating osmotic pressure it is 40 ÷ 70 atm.
After reverse osmosis the water is purified from salts by 80 ÷ 99.7%, depending on the composition of the water, the type of membrane and equipment configuration.
Areas of application of industrial reverse osmosis systems:
- production of alcoholic and soft drinks, bottled water, artificially mineralized water, food production;
- medical and pharmaceutical industries;
- drinking water supply;
- boiler make-up water preparation.