PRACTICAL IDENTIFICATION OF UNSTRUCTURED GROWTH-KINETICS BY APPLICATION OF OPTIMAL EXPERIMENTAL-DESIGN

This paper deals with the practical identification of the parameters o f unstructured growth kinetics during growth of biomass on one limitin g substrate in a fed-batch bioreactor. We consider kinetic models in w hich the specific growth rate is a function of the substrate concentra tion only. Two classes of models are distinguished: non-monotonic kine tics (with the Haldane model as a prototype) and monotonic kinetics (w ith the Monod model as a prototype). The information content of severa l simulation experiments, each with a different volumetric feed rate p rofile is evaluated by using the modified E-criterion for optimal expe rimental design (i.e., ratio of the largest to the smallest eigenvalue of the Fisher information matrix). The main contribution of this pape r is to provide theoretical evidence and to present illustrative examp les for the following conjecture: A feed rate strategy which is optima l in the sense of process performance, is an excellent starting point for feed rate optimization with respect to estimation of those paramet ers with large influence upon process performance. For a two degrees o f freedom optimization of the feed rate profile, we obtain for the fir st time a modified E-criterion value equal to 1, which is the optimal value for this criterion.