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Reverse osmosis
2.1. Function of reverse osmosis
When separating saline solution from pure water by a semi-permeable membrane, the
system tries to establish concentration compensation.
The water passes through the membrane without the influence of external forces and
dilutes the solution until a balance is established. This process is called osmosis.
In the balance, the static pressure in the solution is the same as the osmotic pressure.
The process is reversible when applying pressure to the saline solution, thus overcoming
the osmotic pressure.
During this process of reverse osmosis, pure water is transported through the
membrane, while the saline solution is concentrated.
In the technical reverse osmosis process, the concentrated solution is referred to as con-
centrate, which is continuously drained from the system and which produces pure water
permeate. Thus, when speaking about performance, permeate output or pure water
output are indicated.
Semi-permeable membrane
Concentrated
solution
Pure water
Osmotic
pressure
Osmosis
Reverse osmosis membrane
Reverse osmosis
Concentrated
solution
Pure water
Pressure
