This computer program (FORTRAN, IBM 1130) can be used to compute the quasi-steady-state performance and cost of groups of conventional and advanced wastewater treatment unit processes arranged in any configuration. Each subroutine computes the performance and cost of single unit process. An influent stream vector and decision variables are input. The program presently contains subrountines for simulating the following wastewater treatment processes: preliminary treatment, primary sedimentation, aeration-final sedimentation, trickling filtration-final sedimentation, chlorination, anaerobic sludge digestion, vacuum filtration, gravity sludge thickening, sludge elutriation, sludge drying beds, stream mixer, and stream splitter. To obtain the punched cards see PB-219 468. (Author Modified Abstract)