Control of Anaerobic Digestion Reactor with Recirculation Using an Input-Output Linearizing Control Strategy

This work deals with the development and application of a model-based control system for an anaerobic digestion process which can recover energy using methane combustion. Due to the spatially distributed dynamics of some variables of the upflow anaerobic sludge blanket (UASB) reactor, a type of anaerobic digestion process, the traditional control systems may have insufficient performance to handle the complexity. An input-output (I/O) linearizing control scheme for a UASB reactor is developed for a two-step (acidogenesis-methanogenesis) kinetic model described by a coupled PDE-ODE system. The organic substrate (characterized by COD) is manipulated through the feed flow to achieve the desired trajectories. A simulation for closed-loop responses of the proposed control system is conducted and control performances are determined for servo and regulatory problems. The results show that the developed method provides very good responses to achieve the desired set points and handle the control problems without offset. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.