Reverse Osmosis
This fact sheet explains what Reverse Osmosis and Desalination are and how they pertain to water. Understanding Desalination and Reverse Osmosis is important to understanding how salt is removed from sea water and how it can be cleaned by reverse osmosis.
Around the world, sea water is known to have approximately 70 times higher salt levels than drinking water. Throughout the centuries, the scarcity of fresh water resources and the need for additional water supplies has been a critical issue in many arid regions of the world and will continue to be a great concern for the future. This scarcity lowered people’s living standards and limited economic growth. For years, irrigated areas have suffered from salinity problems. Fortunately, during the 1950’s, a great development unfolded mastering the separation of pure water from Brackish and Sea Water. This process is called “Reverse Osmosis”.
Reverse Osmosis: the process of using a pump to highly pressurize Brackish or Sea water against the surface of a semi-porous membrane forcing the transport of salt-depleting water, suspended colloidal particles, minerals ,ions, and other disassociated species across the membrane leading to the emergence of purified water on the lower-pressured side.
But before applying Reverse Osmosis to purify sea water, a method called “pretreatment” needs to be implemented.
Pretreatment is important when working with RO membranes due to the nature of their spiral wound design. The material is engineered in such a fashion as to allow only one-way flow through the system. As such, the spiral wound design does not allow for back pulsing with water or air agitation to scour its surface and remove solids. Since accumulated material cannot be removed from the membrane surface systems, they are highly susceptible to fouling. Therefore, pretreatment is a necessity for any RO system. Pretreatment in SWRO systems has four major components: Screening of solids, Cartridge filtration, Chemical Dosing, and Pre-filtration pH adjustments.
To broaden your understanding of Reverse Osmosis, watch the following video: