OPTIMAL ADAPTIVE-CONTROL OF FED-BATCH FERMENTATION PROCESSES

This paper presents a unifying methodology for optimization of biotech nological processes, namely optimal adaptive control which combines th e advantages of both the optimal control and the adaptive control appr oaches. As an example, the design of a substrate feeding rate controll er for a class of biotechnological processes in stirred tank reactors characterized by a decoupling between biomass growth and product forma tion is considered. More specifically, the most common case is conside red of a process with monotonic specific growth rate and non-monotonic specific production rate as functions of substrate concentration. The main contribution is to illustrate how the insight, obtained by preli minary optimal control studies, leads to the design of easy-to-impleme nt adaptive controllers. The controllers derived in this way combine a nearly optimal performance with good robustness properties against mo deling uncertainties and process disturbances. Since they can be consi dered model-independent, they may be very helpful also in solving the model discrimination problem, which often occurs during biotechnologic al process modeling. To illustrate the method and the results obtained , simulation results are given for the penicillin G fed-batch fermenta tion process.