ABSTRACT
Bioreactors of different configurations are used for the biodegradation of municipal and industrial wastes. These include flow bioreactors with or without recycle, suspended batch reactors (SBR), and plug flow reactors (PFR), among other configurations. Among all types of bioreactors, flow reactors have been used extensively in the treatment of industrial wastewaters. One advantage they offer over other types of bioreactors is that they produce a greater operational stability in response to shock loads. In this chapter, we investigate the performance of a continuous stirred tank bioreactor with the following features: (1) the bioreactor is considered for the case of a gaseous limiting substrate. This situation occurs in aerobic growth subjected to oxygen limitation and accounts for the mass transfer of oxygen; (2) the growth rate is assumed to follow the Contois model [81]. This biomass growth-dependent model is qualitatively different from substrate-dependent growth models studied in previous chapters and also studied by Pinheiro et al. [287]. The Contois growth model was used in a number of biodegradation studies of different food and industrial wastes [55, 60, 125, 161, 171, 190, 260]. The methodology in this chapter consists of the analysis of an unstructured model for the aerated bioreactor. Unlike structured models [147], simpler unstructured models are better suited for rigorous analysis and may provide useful insights in the complex dynamics of the process. The complexity of the real microbial system is accounted for by allowing the kinetic rates in the model to take on a wide but reasonable range. This allows a general analysis of the effect of operating and kinetic parameters [21].
