The membranes may be composed of different kinds of membranes depending on the application being used to separate the fluid...http://www.google.com/patents/US7459084?utm_source=gb-gplus-sharePatent US7459084 - Membrane-assisted fluid separation apparatus and methodAdvanced Patent SearchPublication numberUS7459084 B2Publication typeGrantApplication numberUS 10/481,119PCT numberPCT/CA2002/000933Publ