Periodic optimization of continuous microbial growth processes

Steady-state operation of continuous bioreactors is not necessarily the optimum type of operation. The method of pi-criterion is used in this work to determine whether periodic variation of the dilution rate can enhance the performance of continuous fermentation processes. It is found that the presence of time delay in the dynamic response of the chemostat renders a periodic operation of bioreactors, used for biomass production, superior to any steady-state operation. Also, employing Williams' structured model it is shown that cycling improves the average protein productivity.