| abstract |
(57) [Abstract] [Purpose] Separation membrane Prevents deposition of deposits on the membrane surface. [Structure] The separation membrane 1 is provided with a large number of elongated strip-shaped impermeable portions 2 in a dispersed manner. This impermeable portion is formed as follows. Apply a water impermeable agent to the membrane surface. Make the membrane surface impermeable by heat treatment. A film is formed on a supporting cloth provided with an impermeable region by a water impermeable agent or heat treatment. Weaving impermeable material, or forming a film on the laminated support cloth. By providing an impermeable area in the permeable material for allowing the permeated water that has permeated through the membrane to flow down, the impermeable area is provided on the membrane surface in contact with the permeable material located in the impermeable area only when the membrane and the permeable material are in close contact during pressure filtration. Generate a transparent area. [Effect] Accumulation of deposits on the surface of the separation membrane is suppressed, and it becomes possible to maintain the flux and the rejection rate high for a long period of time. |