Simultaneous control of pH and dissolved oxygen in closed photobioreactor

This study investigates simultaneous pH and dissolved oxygen control (DO) in a closed photobioreactor (PBR), using a conventional linear feedback technique, i.e. individual PID and PID coupled with feedforward compensation. The proposed control scheme has been designed using linear approximations, whereas their evaluation has been done through simulation, considering a nonlinear process model, describing the complexity of this multivariable biological process. The proposed control including feedforward compensation present improved control performances, and consequently improves microorganism's growth conditions. This is of crucial importance in the case of lab scale set ups that have to provide fully controlled cultivation conditions for accurate study of growth dynamics.