Nano-filtration plant are generally constructed by installing hollow fiber membranes or spiral wound membranes.
They have a medium-high working pressure (4-30 bar) and they are normally used to reduce water hardness, to recover salts from dying baths, to remove colour and to recover acids and caustic soda.
retains bivalent salts and organic substances
allows the passage of monovalent salts, inorganic acids and alkaline compounds
the dimension of pores is between the dimension used in ultrafiltration process and the one used in reverse osmosis process.
Both plant configuration and process pressure changes in relation with the different applications of the process and with the dimention of the plant itself.