Reverse Osmosis Plant (RO Plant)

Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules and larger particles from drinking water. Reverse osmosis can remove many types of dissolved and suspended chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and the production of potable water.

Reverse osmosis, invented in 1959, is the newest major method of water purification and one of the types of crossflow membrane filtration. It is a process which removes both dissolved organics and salts using a mechanism different from ion exchange or activated carbon. The pressurized feedwater flows across a membrane, with a portion of the feed permeating the membrane. The balance of the feed sweeps parallel to the surface of the membrane to exit the system without being filtered. The filtered stream is the “permeate” because it has permeated the membrane. The second stream is the “concentrate” because it carries off the concentrated contaminants rejected by the membrane. Because the feed and concentrate flow parallel to the membrane instead of perpendicular to it, the process is called “crossflow filtration”.

Depending on the size of the pores engineered into the membrane, crossflow filters are effective in the classes of separation known as reverse osmosis, nanofiltration, ultrafiltration and the more recent microfiltration.