Stability analysis of the biodegradation of mixed wastes in a continuous bioreactor with cell recycle.

The stability characteristics of a continuous bioreactor with cell recycle for biodegradation of mixed wastes are investigated. The system involves a pure culture of Pseudomonas putida and media containing phenol and glucose as carbon and energy sources. The model growth kinetics for the two substitutable substrates were experimentally validated in a previous study. The stability analysis carried out using elementary principles of bifurcation theory shows rich dynamics characteristics of the reactor model, including steady-state multiplicity and hysteresis. The effect of the bioreactor operating parameters on the stability behavior of the model is discussed. Practical criteria are also derived for the safe operation of the unit and to prevent the occurrence of wash-out conditions.