Anaerobic fluidized bed reactor with expanded clay as support for hydrogen production through dark fermentation of glucose

This study evaluated hydrogen production in an anaerobic fluidized bed reactor (AFBR) fed with glucose-based synthetic wastewater. Particles of expanded clay (2.8–3.35 mm) were used as a support material for biomass immobilization. The reactor was operated with hydraulic retention times (HRT) ranging from 8 to 1 h. The hydrogen yield production increased from 1.41 to 2.49 mol H₂ mol⁻¹ glucose as HRT decreased from 8 to 2 h. However, when HRT was 1 h, there was a slight decrease to 2.41 mol H₂ mol⁻¹ glucose. The biogas produced was composed of H₂ and CO₂, and the H₂ content increased from 8% to 35% as HRT decreased. The major soluble metabolites during H₂ fermentation were acetic acid (HAc) and butyric acid (HBu), accounting for 36.1–53.3% and 37.7–44.9% of total soluble metabolites, respectively. Overall, the results demonstrate the potential of using expanded clay as support material for hydrogen production in AFBRs.