Hydrogen production from propionate in a biocatalyzed system with in-situ utilization of the electricity generated from a microbial fuel cell

Hydrogen could be produced in a biocatalyzed system, which was configured through coupling a hydrogen-producing microbial electrolysis cell (MEC) and an electricity-assisting microbial fuel cell (MFC). It was demonstrated hydrogen was effectively produced from propionate through in-situ utilization of the electric energy generated from such an MEC–MFC-coupled system. The electricity input of the MEC was regulated by applying different loading resistors connected into the circuit in series. The loading resistors shared the MFC power output and reduced the MEC electricity input. As a result, the hydrogen production was negatively affected by the loading resistance. As the resistance was changed from 10 to 1000 Ω, the current density and volumetric hydrogen production rate varied from 343 to 81 mA/m2 and 11.9 to 3.6 ml/l/d, respectively. The hydrogen yield (YH2YH2) decreased with an increase in loading resistance, and the highest YH2YH2 of 4.8 ± 0.7 (YMECH2YMECH2)/2.5 ± 0.4 (YsysH2YsysH2) mol-H2/mol-propionate was obtained at 10 Ω.