Unknown Inputs Nonlinear Observer for an Activated Sludge Process

This paper deals with the jointly estimation problem of unknown inputs and nonmeasured states of one altering aerated activated sludge process (ASP). In order to provide accurate and economic concentration measures during aerobic and anoxic phases, a cascade high gain observer (HGO) approach is developed. Only two concentrations are available; the other process's states are assumed unavailable. The observer converges asymptotically and it leads to a good estimation of the unavailable states which are the ammonia and substrate concentration, as well as a quite reconstruction of the unknown inputs, which arc the influent ammonia and the influent substrate concentrations. To highlight the efficiency of the proposed HGO with this MIMO system's dynamics, simulation results are validated with experimental data.