Extremum seeking control for an anaerobic digestion process

The paper deals with the optimal control (extremum seeking algorithm) of an anaerobic digestion process. It uses a simplified version of the anaerobic digester model. Three cases of optimization criteria are considered taking into account the quality variable of the process: 1. the methane quantity in gaseous form, 2. the level of pollutants (it is expressed as the difference between the influent substrate and the substrate quantities accumulated in the digester) and 3. an aggregated quality variable resulted from the combination of the first two criteria. The analysis of anaerobic digestion process static characteristics shows that each characteristic reaches a point of maximum. The extremum seeking algorithm aims to keep the operating point in this point of maximum. The simulation results confirm the good behaviour of the extremum seeking algorithm.