Model-based design of different fedbatch strategies for phenol degradation in acclimatized activated sludge cultures

Abstract

Microbial degradation of phenol was studied using batch and fedbatch cultures of acclimatized activated sludge under a wide range of phenol (0–793mgl−1) and biomass (0.74–6.7gl−1) initial concentrations. As cell growth continued after total phenol removal, the production and later consumption of a main metabolic intermediate was considered the step governing the biodegradation kinetics. A model that takes explicitly into account the kinetics of the intermediate was developed by introducing a specific growth rate model associated with its consumption and the incorporation of a dual-substrate inhibitory effect on phenol degradation. Biomass growth and phenol removal were adequately predicted in all the cultures. Moreover, the model-based design of the fedbatch feeding strategies allowed driving separately the phenol degradation under substrate-limitation and substrate-inhibition modes. A sensitivity analysis was also performed in order to establish the importance of the parameters in the accuracy of model predictions.