Robust interval-based SISO and SIMO regulation for a class of highly uncertain bioreactors: application to the anaerobic digestion

A robust set-valued regulation law is proposed for the stabilization of an anaerobic digester for the treatment of wastewater. This process exhibits a highly nonlinear dynamic behavior. In addition, it must operate in an uncertain environment with the presence of unknown inputs. Supporting some structural and operational conditions, this regulation law exponentially stabilizes the two most important variables in the anaerobic digester: the chemical oxygen demand concentration and the volatile fatty acids concentration around a desirable steady state in the presence of kinetic uncertainties and input disturbances. Simulations are carried out handling operational conditions close to those used in a real plant.