Design and study of a risk management criterion for an unstable anaerobic wastewater treatment process

In this paper we consider an unstable biological process used for wastewater treatment. This anaerobic digestion ecosystem can have two locally stable steady states and one unstable steady state. We first study the model and characterise the attraction basin associated to the normal operating mode. In a second step we estimate the size of this attraction basin by using a simplified criterion that turns out to be a good approximation. Finally we apply the approach on a real anaerobic digestion plant, and we show that the proposed criterion allows to rapidly detect the conditions of a destabilisation.