Interplay among culture parameters, light, mixing, and photobioreactor configuration during H2 production by sulfur-deprived Chlamydomonas reinhardtii

The interplay among the culture parameters, light intensity and illumination conditions, mechanical mixing conditions, and reactor configurations during O2 evolution and H2 production in sulfur-deprived Chlamydomonas reinhardtii cultures is studied in this work. The advective-diffusive reaction equation is used to describe the diffusion and the local biochemical reactions of the species involved in the biological process for H2 production. Solutions of the diffusion equation are obtained for different boundary conditions. An empirical equation is used to describe the relation between the light attenuation coefficient and the initial chlorophyll concentration, which characterizes both the culture absorption property and the mechanical mixing condition. The dynamics of O2 evolution and H2 production in a tubular photobioreactor illuminated under three different light conditions on the boundary is studied for the cultures with different initial chlorophyll concentrations. For the culture with the initial chlorophyll concentration of 18 mg/L, the light attenuation level of Ka0 = 0.125, and the reference light intensity of 236.3 μE m−2 s−1, the results indicate that the maximum H2 production is 166 ml for the tubular reactor under uniform light illumination, 163 ml for the flat plate reactor under two-side light illumination, 85 and 75 ml for the tubular and the flat plate reactors, respectively, under one-side light illumination.

► We model the interplay among key parameters in tubular photobioreactor during H2 production. ► We use empirical light attenuation function to characterize both culture optical property and mechanical mixing condition. ► Tubular reactor is more favorite for H2 production than flat plate reactor under the given condition. ► High light intensity is preferred for high initial cell concentration in H2 production.