MATHEMATISCHE BEHANDLUNG VON SINGLE-CELL-PROTEIN-PROZESSEN

Abstract

Hansenula polymorpha fed-batch cultivations were carried out on ethanol-substrate in a cocurrent 275 cm high bubble column loop bioreactor. The studied single-cell-protein-( SCP-) processes are time- and spacedependent. The mathematical description leads to a set of coupled nonlinear partial differential equations (distributed parameter system). The model equations contain X-, S-, and 0,- balances in the liquid phases of column and loop as well as 0,-, No- (inert) and C0, - balances in the gas phase of the reactor. Nonstationary model equations have been solved and unknow parameters, volumetric mass transfer coefficient ky +a, 0,- and Syield coefficients, Yyyo and Yyys> 0,- and S-saturation constants, Ko and Ko» have been identified -by fast hybrid simulation methods. Some identified parameters depend strongly on the process conditions, classified into unlimited growth, oxygen transferand substrate-limited growth. The time dependence of parameters during the dynamical processes needs adaptive control strategies. Based on excellent agreement of experiments and mathematical model on-line control algorithmen (OLFO=Open Loop Feedback Optimal Control) have been developed for optimal control of batch processes in tower reactors.