Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes

This paper deals with the equilibria and stability analysis of the two step anaerobic model initially proposed by [12] to describe the dynamical behavior of an anaerobic fixed-bed wastewater treatment process. In a first part, the model is analyzed: its equilibria and their stability are established considering qualitative properties of the kinetics. In a second part, it is shown that the overloading tolerance (denoted herein OT), a parameter proposed in [9] to monitor anaerobic processes on-line, may not be suitable for monitoring the system and even causes serious problems under certain functioning conditions. Based on the analysis results established in the first part, a modified OT is proposed and evaluated in simulation.

► We propose a generic mathematical analysis of equilibria and their stability of a two steps model (AM2).
► We revisit an interesting monitoring tool (stability criterion) proposed in the literature.
► A modified version of this criterion is proposed at the light of the previous performed mathematical analysis.
► Simulations results illustrate that the actual proposed criterion is more appropriate but it requires quite important a-priori knowledge about the system.