Improvement of fermentative biohydrogen production by Clostridium butyricum CWBI1009 in sequenced-batch, horizontal fixed bed and biodisc-like anaerobic reactors with biomass retention

• Biofilm formation by a pure Clostridium butyricum strain was studied.
• The H2 production rate and yield from glucose were efficiently enhanced.
• An horizontal fixed bed bioreactor and an anaerobic biodisc-like reactor were tested.
• The liquid to gas transfer of H2 from culture medium to gaseous phase was improved.
• The effect of H2 partial pressure and H2 supersaturation was reduced.

A horizontal tubular fixed bed bioreactor (HFBR) and an anaerobic biodisc-like reactor (AnBDR) were designed to both fix Clostridium biomass and enable rapid transfer of the hydrogen produced to gas phase in order to decrease the strong effect of H2 partial pressure and H2 supersaturation on the performances of Clostridium strains. The highest H2 production rate (703 mL H2/L h) and yield (302 mL/g glucose consumed i.e. 2.4 mol/mol) with the pure culture were recorded in the AnBDR with 300 mL culture medium (total volume 2.3 L) at pH 5.2 and a glucose loading rate of 2.87 g/L h. These results are about 2.3 and 1.3-fold higher than those achieved in the same bioreactor with 500 mL liquid medium and with the same glucose consumption rate. Therefore, our experimentations and a short review of the literature reported in this paper emphasize the relevance of performing bioreactors with high L/G transfer.