The Advanced feed outside hollow-fiber ultrafiltration membrane prepared from specially synthesized high-molecular weight polyacrylonitrile (PAN) has been developed. The hollow-fiber possesses high physical strength and high chemical resistance. In the consequence of the pore size on the feedside skin layer of the hollow-fiber membrane being designed to be 0.01 μm, the excellent removability of accumulated solids and fouling components has been achieved. The filtration performance, which is affected by the operating conditions such as the filtration velocity, the feed water quality, physical and chemical cleaning conditions, can be maintained in good conditions. At the same time, the proper operating conditions for the hollow-fiber membrane modules are determined and kept throughout the operation.