Model development, parameter identification, and simulation of SCP production processes in air lift tower reactors with external loop—II: Extended culture modelling and quasi steady state parameter identification

Abstract

Yeast was cultivated in extended culture in a bench-scale 275 cm high air lift tower reactor 15 cm dia. with an external loop. Longitudinal dissolved oxygen concentration profiles, substrate and cell mass concentrations in the medium, O 2 and CO 2 concentrations in the gas phase, as well as gas flow rates and liquid recirculation rates were measured. A distributed parameter model was used to describe the cultivation process variation along the column, cell mass, substrate and oxygen balances in the medium, O 2 and CO 2 balances in the gas phase, variation of the volumetric mass transfer coefficient along the column due to bubble coalescence, as well as double substrate Monod kinetics. Based on simulation runs it was assumed that under non limited and oxygen transfer limited growth conditions, the cell mass and substrate concentrations are uniform in the reactor. The simulation was carried out by a hybrid computer. The unknown model parameters (volumetric mass transfer coefficient at the gas entrance, k La E , and coalescence factor K ST ) and two kinetic parameter R Omax and K O were identified by means of experimental results with quasi steady state simulation methods.