Optimization of a Microorganisms Growth Process

This paper presents an optimization strategy for a microorganisms growth process with inhibition kinetics. Two optimization problems are solved: the problem of optimal operation for maximum productivity in steady state and the problem of the start-up to the optimal steady state. The proposed control law is of bang-bang type with no singular intervals. It drives the bioreactor from an initial state to a small neighbourhood (target set) of the optimal steady state while maximizing the productivity. Once the target set is reached, the control effort is switched to the optimal dilution rate, which allows the process to converge to the optimum. The bang-bang controller substantially increases the stability region of the optimal equilibrium point.