BIODEGRADATION OF WASTES IN A CYCLICALLY OPERATED REACTOR - THEORY, EXPERIMENTAL-VERIFICATION AND OPTIMIZATION STUDIES

A cyclically operated biological reactor employed for treatment of liq uid wastestreams containing a single pollutant was mathematically mode led and analyzed, using the principles of bifurcation theory for force d systems. The analysis showed that the system has two qualitatively d ifferent solutions (washout and culture survival), and that there are regions in the operating parameter space where multistability occurs. The theoretical predictions were experimentally verified with a 5-lite r continuously operated reactor. Phenol was used as the model pollutan t, and the biomass consisted of a pure culture of Pseudomonas putida ( ATCC 31800). In all cases, an excellent agreement was found between ex perimental data and model predictions, both at a qualitative and a qua ntitative level. The model was subsequently used in numerical studies, the objective of which was to find optimal operating parameter values for maximizing the productivity (volumetric efficiency) of the reacto r. The results indicate that in all cases, optimal parameter value set s exist. The system considered here is a variation of the sequencing b atch reactors (SBRs) used in wastewater treatment applications. The re sults of this study suggest a methodology for optimal bioreactor desig n for environmental applications.