Monitoring of an industrial wastewater plant employing finite‐time convergence observer

In this paper, the estimation of non measured variables (bioreactor biomass and settler biomass concentrations) is addressed. The plant is subjected to sudden step disturbances on the inlet oxygen flow, such that an observer with finite‐time convergence is required, to maintain adequate estimation performance. The observer structure contains a fractional power of the estimation error which is proposed to ensure the convergence properties needed. Under the assumptions considered, a mathematical analysis is performed to demonstrate the convergence of the estimation error and the convergence time is also calculated. The performance of the observer is illustrated with numerical experiments and compared with standard nonlinear Luenberger observer. Copyright © 2006 Society of Chemical Industry