Quantification of oxygen transfer coefficients in simulated hydrocarbon-based bioprocesses in a bubble column bioreactor.

This study investigates the overall volumetric oxygen transfer coefficient (Ka) in multiphase hydrocarbon-based bioprocess under a range of hydrocarbon concentrations (H), solid loadings (deactivated yeast) (S) and superficial gas velocities (U) in a bubble column reactor (BCR). Ka increased with increasing U in the air-water system; due to an increase in the number of small bubbles which enhanced gas holdup. In air-water-yeast systems, the initial addition of yeast increased Ka significantly. Further increases in S reduced Ka, due to increases in the bubble size with increasing S. Ka decreased when H was added in air-water-hydrocarbon systems. However, U, S and H affected Ka differently in air-water-yeast-hydrocarbon systems: an indication of the complex interactions between the yeast and hydrocarbon phases which changed the system's hydrodynamics and therefore affected K. This work illustrates the effect of the operating conditions (S, H and U) on oxygen transfer behaviour in multiphase systems.