Development of a 4-Measurable States Activated Sludge Process Model Deduced from the ASM1

The Activated Sludge Model No.1 (ASM1) allows the prediction of organic matter degradation, nitrification and denitrification in the activated sludge bioreactors using thirteen states variables. This paper deals with modal reduction procedure applied to the ASM1, that followed by physical considerations about the process allows the development of a 4-state variables model which is still able to describe the nonlinear behavior of bioreactors in the Activated Sludge Process (ASP). Furthermore, coupling the reduced bioreactor model with a simplified model for the secondary settler (as the Taka ́cs model), the overall ASP behavior is deduced.