Simulation of biofilm growth and biohydrogen production in dynamic membrane bioreactors using a coupled LBM–CA framework

Biohydrogen is a promising renewable energy carrier, and dynamic membrane bioreactors (DMBRs) enhance its production through microbial retention. However, the coupled effects of biofilm growth, hydrodynamics, and mass transport at the pore scale remain inadequately understood. In this study, a CT-informed lattice Boltzmann method–cellular automata (LBM–CA) framework is developed to simulate biofilm growth and biohydrogen production in a DMBR. The model integrates flow dynamics, multicomponent transport, biochemical reactions, and biofilm growth. The effects of initial biofilm concentration (1–8%) and threshold shear stress (75–150%) are investigated. Results show that higher initial biofilm concentrations accelerate biofilm growth and enhance early hydrogen production, while higher shear stress thresholds improve biofilm retention and increase cumulative hydrogen extraction by up to 20%. Excessive biofilm growth, however, causes pore blockage and transport limitations. Sensitivity analysis indicates that model predictions are more sensitive to biomass yield than to the biomass inactivation coefficient.