Improved hydrogen production of the downstream bioreactor by coupling single chamber microbial fuel cells between series-connected photosynthetic biohydrogen reactors

To obtain additional hydrogen recovery from the downstream photosynthetic biohydrogen reactor (PBR), a system (PBR1-MFCs-PBR2) that combined PBRs with three single chamber microbial fuel cells (MFCs) was proposed in this study. The results revealed that the PBR2 in PBR1-MFCs-PBR2 showed a hydrogen production rate of 0.44 ± 0.22 mmol L h−1, which was 15 and 4 times higher than those obtained by direct connecting the two PBRs (PBR1-PBR2) and pH regulated system (PBR1-pH regulation-PBR2), respectively. In addition, the PBR1-MFCs-PBR2 exhibited the highest glucose utilization (ηg) of 97.6 ± 2.1 %, while lower ηg values of 75.6 ± 2.2% and 70.1 ± 1.2% was obtained for PBR1-PBR2 and PBR1-pH regulation-PBR2, respectively. These improvements were due to the removal of inhibitory byproduct and H+ from the PBR1 effluent by the MFCs.