A comprehensive model was proposed to describe dynamic processes in a porous substrate biofilm photobioreactor.

Comparison of simulated results and experimentally derived data were carried out along the depth gradient of the biofilm.

The model predicted distributions of light, dissolved oxygen, pH and biomass growth with a high fidelity.

Results strongly suggest a vital role of facilitated CO₂ transfer in inorganic carbon transfer at low CO₂ concentrations.

With minor modifications, the proposed model can be used for optimization of biofilm bioreactors.