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 the 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. (c) 2007 Elsevier Ltd. All rights reserved.