Comparative study on bio-hydrogen production from corn stover: Photo-fermentation, dark-fermentation and dark-photo co-fermentation

In this study, three different fermentation methods, such as photo-fermentation (PF), dark fermentation (DF) and dark-photo co-fermentation (DPCF) for bio-hydrogen production from corn stover were compared in terms of hydrogen production, substrate consumption, by-products formation and energy conversion efficiency. A modified Gompertz model was applied to perform the kinetic analysis of hydrogen production. The maximum cumulative hydrogen yield of 141.42 mL.(g TS)(-1) was achieved by PF, DF with the minimum cumulative hydrogen yield of 36.08 mL.(g TS)(-1) had the shortest lag time of 4.33 h, and DPCF had the maximum initial hydrogen production rate of 1.88 mL.(g TS)(-1).h(-1) and maximum initial hydrogen content of 44.40%. The results also indicated PF was an acid-consuming process with a low total VFAs concentration level of 2.90-4.19 g.L-1, DF was a process of VFAs accumulation with a maximum total VFAs concentration of 12.66 g.L-1, and DPCF was a synergistic process in which the total VFAs concentration was significantly reduced and the hydrogen production efficiency was effectively improved compared with DF. The energy conversion efficiency of PF, DF and DPCF were 10.12%, 2.58% and 6.45%, respectively. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.