State Estimation Based on Nonlinear Observer for Hydrogen Production in a Photocatalytic Anaerobic Bioreactor

Hydrogen concentration in a photocatalytic continuous bioreactor was estimated. For the above system, a novel kinetic model of the sulfate-reducing process for hydrogen production was proposed and experimentally confirmed. In addition, we present the design of an estimator based on nonlinear observer, which is robust against modeling errors, to estimate the observable states of the bioreactor. Sulfate, biomass, sulfide, carbon dioxide, cadmium in liquid, cadmium sulfide, and hydrogen concentrations were estimated in spite of errors in the evaluation of the parameters using sulfate concentration as measurable output. The convergence of the proposed observer was analyzed using Lyapunov stability theory. Finally, maximum hydrogen production was 225 mL and 175 mL for batch and continuous processes, respectively.