From Batch to Pilot Scale: Continuous Biohydrogen Production from Potato Peel Residues by Thermotoga neapolitana

The transition to a sustainable hydrogen economy requires renewable production processes based on biomass and industrial waste streams. Thermophilic dark fermentation using the microorganism Thermotoga neapolitana is a promising approach because it can achieve hydrogen yields close to the theoretical maximum. This microorganism can also utilize starchy waste materials, such as potato peels, without extensive pretreatment. In this study, potato peel residues with a combined starch plus cellulose content of approximately 64% on a dry-matter basis were used as substrate for biohydrogen production. During scale-up from a 1 L laboratory reactor to a 50 L pilot-scale reactor, comparable fermentation profiles were obtained at both reactor scales. A substrate specific yield of 297 ± 11 NL H2·kg−1 dm (26.5 ± 1.0 g H2·kg−1 dm) of potato peel residues was produced. Furthermore, continuous operation at laboratory-scale demonstrated that the peak performance observed in batch fermentation could be maintained over an extended period. Taken together, these results demonstrate the potential for scale-up and continuous biohydrogen production from starch-rich waste streams such as potato peel residues.