Output-Feedback Stabilization of Continuous Bioreactors in the Presence of Biomass Decay

This paper studies the problem of designing output feedback controllers for enlarging the stability region of continuous stirred microbial bioreactors, in the presence of biomass decay. A specific application is in anaerobic digestion, where the stability region can be very small if the operating steady state is selected to maximize the methane production rate. A proportional output feedback control law is proposed and the size of the stability region of the closed-loop system is estimated using Lyapunov methods. The results show that, even though stability is not global, the guaranteed stability region is large enough to ensure proper operation of the reactor in the presence of physically realistic disturbances.