Dark fermentative biohydrogen production from synthetic cheese whey in an anaerobic structured-bed reactor: Performance evaluation and kinetic modeling

Abstract

This study investigated the potential of dark fermentative hydrogen production from cheese whey in an acidogenic anaerobic structured-bed reactor (ASTBR). The reactor was operated at 25 °C with an organic loading rate (OLR) of 24 kg COD m−3 d−1 and a hydraulic retention time (HRT) of 24 h. The ASTBR had an average volumetric hydrogen production rate (VHPR) of 1.6 ± 0.7 L H2 L−1 d−1 and an average hydrogen yield (HY) of 1.4 ± 0.7 moL H2 mol−1 of consumed lactose. Batch experiments were performed with biomass from the ASTBR to characterize the main metabolic transformations involved in hydrogen production. An ADM1-based, unstructured kinetic model was developed and fitted to the obtained temporal profiles. The model allowed a satisfactory description of the process and indicated that hydrogen production from lactate and acetate could explain 74.5% of the total hydrogen volume produced. Because lactic-acid-producing bacteria are expected to ultimately colonize acidogenic reactors treating cheese whey, optimizing electron flow through this pathway may be a suitable strategy to enable long-term hydrogen production from cheese whey using mixed-culture fermentation.