The volume of sewage increases as the population grows and the standard of living rises, that varies in proportion to the volume of available water supply. As of 1998, the sewage treatment ratio is 66%, and 114 sewage treatment facilities are under operation. While sewage treatment plant has been constructed in large cities and heavily industrialized cities, mostly activated sludge process is employed, which may not be always desirable for some cities in economical point of view and process optimization. Moreover, poor sewer systems resulted in low organic strength influent than the designed strength. In this study, in an attempt to improve the operation efficiency, several existing sewage treatment plants were evaluated. And some managerial suggestions including privatization were proposed to enhance the efficiency of sewage treatment facility.