Nonlinear PI with state feedback control for activated sludge process

In this paper, an attempt is made to find a centralized nonlinear PI controller with state feedback for the activated sludge process (ASP) used in wastewater treatment plants. The effluent substrate concertation and dissolved oxygen (DO) concentration is controlled irrespective of the variations in disturbance and system parameters. The theoretical framework in this paper is developed on the basis of Falb's row by row decoupling (RRDP) concept. The centralized controller is implemented in a ASP control simulation and the closed loop structure is observed to decouple the process variables better than previous linear controller reported.