Fermentative biohydrogen production potential of sorghum distillers grains using anaerobic microflora at various pH values

Abstract

Sorghum distillers grains (SDGs) are rich in proteins, vitamins, and minerals and are a good feedstock for anaerobically generating biogases such as biohydrogen and biomethane. The present work aims to investigate the anaerobic biohydrogen production potential of SDG to explore its added value. pH is an important operating factor affecting biological reactions and was tested at values of 5.0, 5.5, 6.0, and 6.5. The experimental results show that the hydrogen production rate (HPR) is less pH-dependent, but the hydrogen yield (HY) is rather pH-dependent with near-neutral conditions favoring biohydrogen production. pH 6.5 resulted in an HPR of 4.9 L/L-d (188 mmol/L-d) and peak HY of 81 mL/g chemical oxygen demand. It is shown that SDG is a new and prospective biomass source for biohydrogen production, and with this application, the problem of treating kaoliang liquor SDG could be reduced. Approaches to increase biohydrogen production and applications of the experimental results were also elucidated.