State estimation for wastewater treatment plant with slow and fast dynamics using multiple models

This paper addresses the state estimation of two-time scale nonlinear systems by designing an unknown input multi-observer (UIMO). In order to design such an observer, the nonlinear system is transformed into an equivalent multiple model form and the fast dynamics are considered as unknown inputs. An application to a model of Wastewater Treatment Plants (WWTP) is considered and gives encouraging results.