KLa measurement in two‐phase partitioning bioreactors: new insights on potential errors at low power input

Abstract

AbstractBACKGROUND: Two‐phase partitioning bioreactors (TPPBs) are based on the addition of a non‐aqueous phase (NAP) to a biological process in order to overcome a limited delivery of gaseous substrates to the microorganisms in the case of compounds with low affinity for water. However, the high power input (Pg/V) required to disperse the NAP is often the major limitation for TPPB applications at full scale. Therefore, the accurate determination of the overall mass transfer coefficient (KLa) at low Pg/V values is a critical issue as these operational conditions are more attractive from a scale‐up point of view.RESULTS: NAP addition altered the typical shape of the dissolved oxygen curves used for KLa determination at the lowest Pg/V values tested (70–80 W m−3). Below a threshold Pg/V value of 600 W m−3, the presence of the NAP increased the error in KLa measurements up to 115% relative to controls deprived of NAP.CONCLUSIONS: The error in KLa measurements at low Pg/V values might be related to failures in the fundamental assumption regarding liquid phase homogeneity in the mass transfer model used. Copyright © 2010 Society of Chemical Industry