It consists in pushing water under high pressure through semi-permeable membranes, in order to obtain osmotic equilibrium. The salts and other impurities are retained on the side of the saltwater supply. RO is efficient for low or high concentrations of salts and can thus be used to treat brackish water as well as seawater.
The saline solution to be treated is separated into two phases:
- the permeate : freshwater free of salts and impurities
- the concentrate stream : brine enriched with the dissolved salts retained
Reverse Osmosis membranes being sensitive to the feed water quality, a highly effective pre-treatment is necessary upstream the RO skids of a desalination plant.