Extremum-Seeking Control Approach Based on the Influent Variability for Anaerobic Digestion Optimization

Abstract

Extremum-seeking optimization of the anaerobic digestion processes is often cited in literature. Its achievement implies the use of an external dither signal, either deterministic or stochastic, which is reflected on the command variability, thus affecting the actuator fatigue and the energy consumption. This paper proposes the use of the extremum-seeking control but without using a dither signal included in the extremal controller for the process optimization. Instead we will use, as searching signals, the diurnal variations of the influent wastewater concentration. In the optimization a criterion is used that considers the biogas production rate and that is penalized with a term counting for the pollution resulting with the anaerobic digestion effluent discharge.