Removal of dissolved solids and salts
Reverse Osmosis (RO) is a membrane-based filtration technology which relies on a semi-permeable membrane to remove many types dissolved solids (from large molecules and ions) from liquids. In RO, an applied pressure, greater than the osmotic pressure, is exerted on the concentrated liquid, forcing the water of the concentrate stream (high salt concentration) to flow towards the fresh stream (low salt concentration). As a result, the concentrated side becomes even more concentrated. Though RO can be used with many liquids, its primary application is for water-based systems such as sea water (operating pressure is approximately 60 bar).
Sea Water Reverse Osmosis (SWRO), a more efficient form of RO, is used to desalinate brackish groundwater and employed by S&B Water where salinity exceeds 500 mg/L. SWRO is considered the most economical process for such applications because no heating or phase changes are needed.
Among RO's advantages are:
- Low capital costs
- High efficiency as a desalination method
- Ability to remove multiple contaminants