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

This study investigates the overall volumetric oxygen transfer coefficient (KLa) in multiphase hydrocarbon-based bioprocess under a range of hydrocarbon concentrations (HC), solid loadings (deactivated yeast) (SL) and superficial gas velocities (UG) in a bubble column reactor (BCR). KLa increased with increasing UG 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 KLa significantly. Further increases in SL reduced KLa, due to increases in the bubble size with increasing SL. KLa decreased when HC was added in air-water-hydrocarbon systems. However, UG, SL and HC affected KLa 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 KL. This work illustrates the effect of the operating conditions (SL, HC and UG) on oxygen transfer behaviour in multiphase systems.