Inducing oscillations in a gas-lift bioreactor via anaerobic/aerobic switching
Bio-photolysis yields diatomic molecules from the breaking of water molecules; this takes place in the thylakoid membrane of some species of algae or cyanobacteria under anaerobic conditions. In anaerobic conditions, there is a consumption of the microorganism intracellular starch pools; thus aerobic conditions are induced to recover the intracellular starch pools and to sustain the bio-photolysis. Under aerobic conditions these microorganisms produce carbohydrates, through CO\2 fixation via the Calvin cycle, that are accumulated as starch. In order to carry out both anaerobic/aerobic steps into a process, a gas-lift continuous photobioreactor is supposed such that a mechanism is used to switch between them. As a consequence of the switching, the alternation consumption/accumulation of the intracellular starch pools lead us to investigate oscillatory behavior for a constant dilution rate. Thus, the aim of this work is to determine conditions on switching, with a constant dilution rate, such that the oscillatory behavior occurs into a photobioreactor gas-lift continuous. The equilibria stability analysis was conducted and then the switching effect is studied. Hence, a simple switching rules are proposed to induce oscillatory behavior.