Nanofiltration technology is utilized when special membrane pore diameter is not fit for the separation that reverse osmosis or ultrafiltration offers. It could be used for demineralization, decolorization, COD removal, wastewater recycling and desalination when other alternatives cannot be applied. Suspended solids and polyvalent ions are removed from organic solutions, and low molecular weight solutions such as monovalent ions and alcohol remains in permeate.

Nanofiltration (NF) – Membrane pore size is 0.001 micron, and the applied pressure is higher. All bacteria, viruses, and cysts could be removed with this system. NF also decreases the alkalinity level of the water, so the output water could be corrosive. NF membranes are also known as softening membranes since they remove minerals that cause hardness from the water.