Biodegradation of wastes in a cyclically operated reactor: Theory, experimental verification and optimization studies

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.

Biodegradation of mixed wastes in continuously operated cyclic reactors

The problem of simultaneous biodegradation of two dissimilar substrates in a continuously operated cyclic reactor was studied both at the theoretical and experimental levels using a simple model system. The system involved media containing mixtures of glucose and phenol as carbon sources. A pure culture of Pseudomonas putida (ATCC 17514) was employed. Independent kinetic experiments have revealed that glucose and phenol are involved in a crossinhibitory uncompetitive kinetic interaction. The dynamics of a cyclically operated reactor were analyzed using the principles of bifurcation theory for forced systems. Experimental results have confirmed the theoretical predictions. Implications of the results for the design of waste-treating facilities are discussed.