Feed rate optimization for fed-batch bioreactors: from optimal process performance to optimal parameter identification

In this paper the optimization of a cost criterion combining both a performance cost and a parameter identification cost is discussed for the growth of biomass on one limiting substrate in a fed-batch bioreactor. Both monotonic and non-monotonic unstructured kinetic models in which the specific growth rate is a function of the substrate concentration only are considered. The parametric optimization of the feed rate profile in the fed-batch bioreactor with respect to a novel combined cost function yields a continuous transformation of the optimal performance feed rate profile towards the optimal identification profile as more weight is assigned to the identification purpose. As such we provide support for the conjecture that a feed rate strategy which is optimal in the sense of process performance, is an excellent starting point for feed rate optimization with respect to estimation of those parameters with large influence upon process performance.