Revisiting Basics of <i>k<sub>L</sub>a</i> Dependency on Aeration in Bubble Columns: <i>a</i> Is Surprisingly Stable
Moritz Wild, Yannic Mast, Ralf Takors
Abstract
Abstract A comprehensive experimental characterization of a small‐scale bubble column bioreactor (60 mL) is presented. Bubble size distribution (BSD), gas holdup, and k L a were determined for different types of liquids, relevant fermentation conditions and superficial gas velocities u G . The specific interfacial area a and liquid mass transfer coefficient k L have been identified independent of each other to unravel their individual impact on k L a . Results show that increasing u G leads to larger bubbles and higher gas holdup. As both parameters influence a in opposite ways, no increase of a with u G is found. Furthermore, k L increases with increasing bubble size outlining that improved oxygen transfer is not the result of higher a but of risen k L instead. The results build the foundation for further simulative investigations.