Nanofiltration is a membrane filtration-based method that uses nanometer sized through-pores that pass through the membrane. Nanofiltration membranes have pore sizes from 1-10 nanometers, smaller than that used in microfiltration and ultrafiltration, but just larger than that in reverse osmosis. Membranes used are predominantly created from polymer thin films.
Ultra filtration is a membrane separation technology. It is based on pressure difference across membrane to realize liquid separation according to screening principle.
For water treatment, UF can remove particle, colloid, bacterium, virus, protein and organics in water to get purified water.