Hydrogen production with effluent from an ethanol-H2-coproducing fermentation reactor using a single-chamber microbial electrolysis cell.
Hydrogen can be produced by bacterial fermentation of sugars, but substrate conversion to hydrogen is incomplete. Using a single-chamber microbial electrolysis cell (MEC), we show that additional hydrogen can be produced from the effluent of an ethanol-type dark-fermentation reactor. An overall hydrogen recovery of 83+/-4% was obtained using a buffered effluent (pH 6.7-7.0), with a hydrogen production rate of 1.41+/-0.08 m(3) H(2)/m(3) reactor/d, at an applied voltage of E(ap)=0.6 V. When the MEC was combined with the fermentation system, the overall hydrogen recovery was 96%, with a production rate of 2.11 m(3) H(2)/m(3)/d, corresponding to an electrical energy efficiency of 287%. High cathodic hydrogen recoveries (70+/-5% to 94+/-4%) were obtained at applied voltages of 0.5-0.8 V due to shorter cycle times, and repression of methanogen growth through exposure of the cathode to air after each cycle. Addition of a buffer to the fermentation effluent was critical to MEC performance as there was little hydrogen production using unbuffered effluent (0.0372 m(3) H(2)/m(3)/d at E(ap)=0.6 V, pH 4.5-4.6). These results demonstrate that hydrogen yields from fermentation can be substantially increased by using MECs.
State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China.
Lu
L
Lu
Nanqi
N
Ren
Defeng
D
Xing
Bruce E
BE
Logan
D000085:Acetates / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D003624:Darkness; D004572:Electrolysis; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics
D000085:Acetates; D000431:Ethanol; D006859:Hydrogen