Reverse Osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the Osmotic Pressure.
This is the reverse of the normal Osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied. The membrane here is semi permeable, meaning it allows the passage of solvent but not of solute. These RO units are custom designed for drinking water, brackish water, USP grade water for pharmaceutical application, sea water desalination and waste water recycling for industrial application.
Ultra filtration is a pressure driven membrane separation process that separates particulate matter from soluble components in the carrier fluid (such as water). UF membranes typically have pore sizes in the range of 0.01 - 0.10 µm and have a high removal capability for bacteria and most viruses, colloids and silt (SDI). The smaller the nominal pore size, the higher the removal capability. UF units are designed for municipal drinking water, pretreatment of RO and other industrial application.
Nano filtration is a pressure driven separation process. The filtration process takes place on a selective separation layer formed by an organic semi-permeable membrane. It separates divalent and multivalent ions in concentration of organic solutes, suspended solids, and polyvalent ions, the Permeate contains monovalent ions and low-molecular-weight organic solutions like alcohol. NF units are custom designed for industrial application.