The present paper summarizes the outlines of a simulation analysis study conducted on the BSM1 (formerly the COST benchmark) configuration using activated sludge models (ASM1, ASM2d and ASM3) coupled to Takács settler model. The prime objective was to develop reliable simulation software programs to implement these complex models according to the working conditions of a realistic plant. The analysis focused on comparing the steady state predictions of models ASM1/ ASM3 when imposed to pulse/ step type disturbances on wastewater characteristics and control variables, then on assessing the capability of the simulated configuration for bio-P removal using model ASM2d. Section 1 of the paper briefly presents problem definition/ solution approach while section 2 demonstrates some examples showing the main indications of the simulation analysis. ASM1/ ASM3 predictions indicate the presence of some significant differences between both models that could be related to their underlying concepts. ASM2d simulations show that adverse effects on the permissible limit of effluent's ammonia concentration should be expected when the plant is operated to achieve dual nutrient removal.