Nano filtration is mainly applied in drinking water purification process steps, such as water softening, decolouring and micro pollutant removal. During industrial processes nano filtration is applied for the removal of specific components, such as colouring agents. Nano filtration is a pressure related process, during which separation takes place, based on molecule size. Membranes bring about the separation. The technique is mainly applied for the removal of organic substances, such as micro pollutants and multivalent ions. Nano filtration membranes have a moderate retention for univalent salts. Other applications of nano filtration are.