Optimization of the dark fermentation technique for hydrogen production through supplementation with ascorbic acid and/or l-cysteine by Clostridium butyricum CCDBC 11

Abstract

This study explores the enhancement of biohydrogen production through the addition of oxygen scavengers, ascorbic acid, and l-cysteine during dark fermentation by Clostridium butyricum strain. The supplementation of these compounds significantly reduced the bacterial lag phase and accelerated cell growth, thereby boosting the hydrogen output. Using saccharified corn scrap as the substrate, a maximum cumulative hydrogen yield of 2.20 mol H2/mol glucose was achieved with 5 mg/L ascorbic acid. This treatment reduced the lag phase by 65.6% and increased the hydrogen yield by 40.9% compared to the control and by 11.4% relative to l-cysteine supplementation alone. Biogas production was quantified via the water displacement method, and hydrogen content was analyzed using gas chromatography. The results indicate that ascorbic acid is a cost-effective and efficient additive for improving the hydrogen yield in dark fermentation processes.