Reverse Osmosis is a filtration process where you demineralise and deionise water by pushing it through a semi-permeable, Reverse Osmosis membrane. The process is often used to treat brackish water (water that is saltier than fresh water with less than 14,000 ppm of salt) and seawater (water that has more than 14,000 ppm of salt).
The Reverse Osmosis Process
Reverse Osmosis is widely used to treat water in industrial and agricultural applications. The RO filters have a pore size of around 0.0001 micron (or 0.000001 mm). After water passes through a RO filter, it is essentially pure water. The chart below summarises the types of particles that are removed from the water through the reverse osmosis process as compared to Ultrafiltration process.
Reverse Osmosis is capable of removing dissolved solids (ions), particles, colloids, organics and bacteria from the feed water. It is used to remove monovalent ions, which means that it desalinates the water. Desalination is the process of removing dissolved salts from water thus producing fresh water from seawater or brackish water. When the RO process separates dissolved salt from water, the salt is collected in a concentrate, called the brine, and the fresh water is ready to be reused. Brine requires proper disposal including permits or other regulatory compliance. They are often discharged into the sewer or sent to an evaporation pond.
It is important to note that Reverse Osmosis process is not only for brackish water or salt water. It can also be used to treat water from rivers, artesian and bore holes and in wastewater treatment plants. It is used in industrial processes in pharmaceutical plants, in boiler feed water, food and beverage, metal finishing and semiconductor manufacturing facilities, to name a few.
Pre-Treatment for Reverse Osmosis
Often Reverse Osmosis systems require pre-treatment, using both mechanical and chemical treatments. Pre-treatment helps prevent fouling, scaling and premature RO membrane failure as well as frequent cleaning requirements. Through this membrane filtration series, we have talked about pre-treatment solution to RO including Media Filtration, Microfiltration and Ultrafiltration.
Containerised Reverse Osmosis Plants
Enivro Concepts designs and builds Reverse Osmosis systems for Industrial water treatment. The RO systems can remove up to 99% of dissolved solids and virtually any colloidal or suspended matter from the feed water. The systems are containerised for smaller footprint. If pre-treatment is needed, it is designed and built into the containerised system. The RO systems are pre tested and are ready to produce water when it is installed on site within a matter of days.
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