Reverse Osmosis Membrane is common membrane materials include polyamide thin film composites (TFC), cellulose acetate (CA) and cellulose triacetate (CTA) with the membrane material being spiral wound around a tube, or hollow fibres bundled together. In the reverse osmosis process cellophane-like membranes separate purified water from contaminated water. RO is when a pressure is applied to the concentrated side of the membrane forcing purified water into the dilute side, the rejected impurities from the concentrated side being washed away in the reject water.
The performance of a system depends on factors such as membrane type, flow control, feed water quality, temperature and pressure. Also only part of the water entering the unit is useable, this is called the % recovery. This is affected by the factors listed above. Reverse Osmosis Systems must be well maintained to ensure good performance with any fouling requiring cleaning maximizing the output of water. Biocides may be needed and the choice of biocide would depend on the membrane type, alternatively other filters may be required to remove chlorine from water to protect the life of the membranes.