Membrane separation method and a membrane separation device

PROBLEM TO BE SOLVED: To provide a membrane separation method and a membrane separation device, each of which enables to reduce deterioration in membrane separation performance during the membrane separation of water to be processed by reducing adsorption of membrane contaminating materials contained in the water onto the membrane surface. SOLUTION: In the membrane separation method, the water to be processed is subjected to membrane separation after being added with particles made of a cationic polymer which swells but does not substantially dissolve in water. COPYRIGHT: (C)2009,JPO&INPIT