Evaluation of hydraulic retention time on hydrogen production from corn industry wastewater by dark fermentation

Dark fermentation has the potential to produce biohydrogen using raw material waste, such as wastewater from the corn industry (cornWW), which is characteristically alkaline and improperly discharged. This study aimed to assess the impact of different hydraulic retention times (HRT) on hydrogen production in a sequencing batch reactor system using raw cornWW as feedstock. Different HRTs were evaluated (4, 2, and 1 day(s)). Higher biohydrogen productivity was observed in HRT value of 1 day (893.6 ± 10.1 NmL H₂/L_reactor/day), indicating its favorable metabolic pathways leading to the generation of hydrogen, carbon dioxide, acetate, butyrate, and caproate. Microbial analysis revealed that the Atopobium and Clostridium (genera) played key roles in hydrogen and organic acid production. Additionally, during the fermentation of cornWW, lactic acid in the feedstock facilitated the production of caproic and propionic acids, further enriching the range of valuable byproducts obtained through this process.