Enhancement on photobiological hydrogen production from corn stalk via reducing hydrogen pressure in bioreactors by way of phased decompression schemes.

[Display omitted] • An experimental pressure control device for photo-fermentation was designed. • Lowering the hydrogen pressure by headspace decompression enhanced hydrogen yield. • The optimized phased decompression schemes were provided to improve hydrogen yield. • Cumulative hydrogen yield of experiments could be fitted well by Gompertz model. In this project, it was verified that properly reducing the bioreactor hydrogen partial pressure (HPP) could significantly enhance the photo-fermentative hydrogen production (PFHP) by corn stalk. The maximal cumulative hydrogen yield (CHY) of 82.37 mL/g was obtained under full decompression to 0.4 bar, which was 35% higher than that without decompression. To increase CHY and save the pressure control cost, 12-hour, 24-hour and 36-hour decompression schemes were provided, and the optimal decompression phase in fermentation under each scheme was investigated. The 12-hour decompression scheme was suitable for 24–36 h of fermentation; the 24-hour decompression scheme implemented within 12–36 h of fermentation had a more desirable CHY; when adopting the 36-hour decompression scheme, operation during 12–48 h yielded a CHY of 81.70 mL/g that approximated whole process decompression. The strategies of decompression at the appropriate phase of fermentation were innovative, which offered a new option for optimizing PFHP economically. [ABSTRACT FROM AUTHOR]