Hollow -fiber ultrafiltration membrane having excellent resistance to fouling

摘要

An object of the present invention is to provide a hollow-fiber ultrafiltration membrane that can be used in treatment in various aqueous fluids such as water purification, beverage treatment, seawater clarification, and that has excellent fractionation characteristics and permeability, while deterioration of its performance due to passage of time is minimized, and that has excellent recovery of the membrane-separation characteristics by cleaning. The main feature of the hollow-fiber ultrafiltration membrane of the present invention is that the specific surface area of the membrane surface to which raw water is supplied falls within the range from not less than 1.10 to not greater than 1.55. The present invention also provides a process for producing a hollow-fiber ultrafiltration membrane, wherein a heat treatment is conducted under the condition that the membrane having a residual organic solvent content of not greater than 300 mg/g.