Microbial dynamics in a continuously stirred tank reactor with 100% cell recycle

Abstract

ABSTRACT: Effects of continuous cultivation on the dynamics of heterogenous populations were investigated by employing a continuously stirred tank reactor (CSTR) with 100% cell recycle to minimize biomass waste and any shifts in microbial populations. Phenol was used as model substrate and as the sole carbon source. Activated sludge bacteria, acclimated to phenol, were grown in a CSTR with 100% cell recycle operated at the same dilution rate but with different influent phenol concentrations. During the steady state, the kinetic parameters for the Haldane model (µm, Ks, and K1) characterizing growth on phenol were determined by a long‐term batch experiment. The dominant microbial species at each steady state were analyzed by biochemical assays. There was a shift in microbial species at different influent phenol concentrations with a corresponding change in µm values whereas the values of Ks and K1 were not influenced. Even though the changes in microbial populations and kinetic parameters were attributed to changes in the influent phenol concentration, there was no direct correlation between them.