Dynamics modeling of hydrogen production by sulfur-deprived Chlamydomonas reinhardtii culture in tubular photobioreactor

A heterogeneous hydrogen production system induced by light attenuation across the culture in a photobioreactor and the boundary conditions is studied by solving the advective-diffusive reaction equation (ADRE) used to describe the system. A uniform light intensity is prescribed on the cylindrical surface of the tubular bioreactor and attenuated by Chlamydomonas reinhardtii culture toward the center. The rate constants and the kinetics orders of the S-system based kinetics equations were determined by correlating with the available experimentally measured data. The photobioreactor was operated for 200 h and the dynamics behavior of O₂ evolution and H₂ production were analyzed. The effects of different initial chlorophyll concentrations and quantities of sulfur re-added to the sulfur deprived culture on H₂ production were studied. The results demonstrate that H₂ production decreases with the light attenuation along radial direction. The overall H₂ production increases with the initial cell concentration and the amount of re-added sulfur, respectively, within the simulated range. The modeled results indicate that optimal combination of the culture parameters under the given light intensity and the mixing condition may exist for high H₂ production.