Closed loop paradigm control based on positive invariance for a wastewater treatment plant

This paper deals with on-line estimation and control of a biological wastewater treatment plant process. The objective of the control is to force the residual substrate and the dissolved oxygen to track a given set point despite the disturbances and system parameter uncertainties. The control law is a closed loop paradigm control based on the positive invariance. The control approach structure is combined with a discrete minimal-order observer, for the on-line reconstruction of unmeasured biological states and unknown parameters of the bioprocess. The efficiency of both the control and estimation are demonstrated via computer simulations.