Biomanufacturing of hydrogen from waste molasses: A full-scale application.

Biomanufacturing of hydrogen by acidogenic fermentation presents a promising avenue for sustainable hydrogen production; however, data on its full-scale application remain limited. Here we evaluate the performance of a 100 m3 continuous-flow stirred-tank reactor (CSTR) utilizing waste molasses and inoculated with aerobic excess sludge for hydrogen production. The reactor operated at 35 °C with a constant hydraulic retention time of 5.8 h, while the organic loading rate (OLR) was incrementally increased from 9.3 to 57.3 kg COD m-3 d-1. By day 19, stable ethanol-type fermentation was established, yielding an average of 265 m3 of hydrogen per day. Over the subsequent 72 days, the reactor maintained continuous operation, achieving an average hydrogen production rate of 282 m3 d-1 at an average OLR of 28.5 kg COD m-3 d-1. Bioaugmentation with Ethanoligenens harbinense YUAN-3 at a 0.5 % volume fraction relative to the mixed liquor volatile suspended solids further enhanced hydrogen production to an average of 348 m3 d-1. Despite fluctuations in the OLR between 17.1 and 55.2 kg COD m-3 d-1, ethanol-type fermentation persisted throughout the bioaugmentation period. These findings demonstrate the viability of full-scale acidogenic fermentation for efficient hydrogen biomanufacturing from high-strength organic wastewater.