A rapid and reliable method of volumetric oxygen transfer coefficient ($K_La$) estimation in bubble column under fermentation is proposed.
This method consists of a sudden change of inlet oxygen concentration with rotameters and valves while gas flow rate was held constant. Dissolved oxygen concentration was measured by dissolved oxygen electrode. The slope of the semi-log plot of the dissolved oxygen concentration response was used for $K_La$ estimation.
In simulation studies, both gas and liquid phase dynamics were considered. The well-mixed gas and liquid phase model was well fitted and the effect of oxygen solubility variation on $K_La$ during fermentation was negligible with the slope method.
In fermentation systems, $K_La$ estimation was possible at low dissolved oxygen concentration with oxygen-enriched air if only the dissolved oxygen concentration were higher than the critical point.
This method needs less oxygen than when nitrogen is used for oxygen removal in the original gassing-in method.
