Sea Water Reverse Osmosis (SWRO) Desalination Process
Under natural conditions, osmotic pressure would drive water with a lower concentration of dissolved salt though a separation membrane toward water with a higher concentration of salt. In the reverse osmosis (RO) process, pressure is applied to overcome this natural osmotic pressure and reverse the movement of water by driving it through RO membranes.
The process removes over 99% of the salt and other minerals, creating fresh water from roughly half of the intake volume. The remaining seawater concentrate is returned to the ocean.
Seawater: Process commences with seawater being withdrawn from the ocean.
Filtration: The seawater is filtered to remove impurities floating in the water.
RO System: The seawater is sent through a reverse osmosis (RO) system comprising membranes under high pressure, allowing fresh water to pass while excluding salt, minerals and other impurities.
Fresh water: About half of the processed seawater becomes high quality fresh water.
The concentrated seawater or brine: The other half of the water (including almost all of the salts rejected by the RO membrane) emerges from the RO system at high pressure. The energy in the concentrated seawater is transferred to the incoming seawater before it is returned to the ocean, lowering the overall energy requirements for the RO system.
24/7: The desalination facilities are designed to operate 24 hours a day, 7 days a week and produce water continuously.
Cost Trends in Reverse Osmosis Desalination
In recent years, SWRO technology has emerged as a cost-competitive water supply option. Learn more.