A robust feedforward/feedback control for an anaerobic digester

A linear feedforward/feedback approach is derived for an up-flow fixed bed anaerobic digester; which used for the treatment of industrial wine distillery wastewater. The approach is novel in the sense that (i) the prescribed reference is the feedforward signal while the tracking error is the feedback signal and (ii) such an approach deals with uncertain kinetic terms, and attenuates load disturbances from the inlet composition. In addition, it requires neither the measurement nor the structure of such disturbances. Moreover, departing from physical properties of the process, some open-loop stability properties are analyzed. Finally, an antireset windup (ARW) scheme completes the control approach by taking into account constraints by actuator saturation. Results show that the ARW scheme improves the closed-loop performance.