Characterstics of different membranes

Characteristics	MF	UF	NF	RO
Membrane pore size (microns)	10-1 to 10	10-2 to 10-1	10-3 to 10-2	10-3 to10-3
Operating pressure (psi.)	1 to 25	10 to 200	300	1500
Porosity (%)	~70	~60	~50	~50
Structure	Several types	Asymmetric	Asymmetric thin film composite	Asymmetric thin film composite
Permeate	Water + dissolved solutes	Water + small molecules	Water + monovalent and some divalent ions	Water
Retentate	Large suspended particles, some emulsion, most bacteria	Most organics over 1000 molecular weight including pyrogenes, viruses, bacteria and colloids	Salts, organic molecules over 500	Ions and most organics over 200 molecular weight