Enhancement of PHB Production Process in a Fed-Batch Bioreactor Using Input-Output Linearization Technique with Optimal Setpoints

Abstract

Polyhydroxy butyrate (PHB) is a polyester that has been widely applied to formulate bioplastics. A challenge for the PHB production is the enhancement of PHB accumulation in bacterial cells, which can be conducted through the nutrient feeding strategy. A control system based on an input/output (I/O) linearization technique for the PHB production in a fed-batch bioreactor is proposed in this work. The concept of feast/famine phase is employed to provide the optimal desired targets for each time instant through optimization problems. The developed controller is applied to regulate the controlled output to follow the desired setpoints by manipulating the feed flow rate of nutrients. Simulation results show that the proposed control system attempts to follow the optimal desired targets (discrete-time approach) during the process operation. The accumulation of PHB in bacterial cells is around 25% higher than that of the process with a modified PI controller. Control performance tests indicate that the proposed control strategy successfully regulates the process according to the desired targets and handles the process disturbance effectively.