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KENT RO Systems
Reverse Osmosis (RO) is a filtration method that
removes many types of large molecules and ions from water by applying
pressure when it is on one side of a selective membrane. The result is that
the solute is retained on the pressurized side of the membrane and the pure
water is allowed to pass to the other side. To be "selective,"
this membrane should not allow large molecules or ions through the pores
(holes), but should allow smaller components of the solution to pass freely.
Reverse Osmosis is most commonly known for its use in drinking water
purification, and helps in removing the salt and other substances from the
water molecules. This is the reverse of the normal Osmosis process, in which
the solvent naturally moves from an area of low solute concentration,
through a membrane, to an area of high solute concentration. The movement of
a pure solvent to equalize solute concentrations on each side of a membrane
generates a pressure and this is the "osmotic pressure." Applying
an external pressure to reverse the natural flow of pure solvent, thus, is
The process is similar to membrane filtration. However, there are key
differences between Reverse Osmosis and filtration. The predominant removal
mechanism in membrane filtration is straining, or size exclusion, so the
process can theoretically achieve perfect exclusion of particles regardless
of operational parameters such as influent pressure and concentration.
Reverse Osmosis, however, involves a diffusive mechanism so that separation
efficiency is dependent on solute concentration, pressure, and water flux