Fermentative hydrogen production in an up-flow anaerobic biofilm reactor inoculated with a co-culture of Clostridium acetobutylicum and Desulfovibrio vulgaris.

Dark fermentation systems often show low H yields and unstable H production, as the result of the variability of microbial dynamics and metabolic pathways. Recent batch investigations have demonstrated that an artificial consortium of two anaerobic bacteria, Clostridium acetobutylicum and Desulfovibrio vulgaris Hildenborough, may redirect metabolic fluxes and improve H yields. This study aimed at evaluating the scale-up from batch to continuous H production in an up-flow anaerobic packed-bed reactor (APBR) continuously fed with a glucose-medium. The effects of various parameters, including void hydraulic retention time (HRTv), pH, and alkalinity, on H production performances and metabolic pathways were investigated. The results demonstrated that a stable H production was reached after 3-4days of operation. H production rates increased significantly with decreasing HRTv from 4 to 2h. Instead, H yields remained almost stable despite the change in HRTv, indicating that the decrease in HRTv did not affect the global metabolism.