Díez, Mario P.Barahona, EmmaDe la Rubia, M. ÁngelesMohedano, Ángel F.Diaz, Elena2024-12-182024-12-182024-09-21M.P. Diez, E. Barahona, M.A. de la Rubia, A.F. Mohedano, E. Diaz, Valorization of process water from hydrothermal carbonization of food waste by dark fermentation, International Journal of Hydrogen Energy, Volume 89, 2024, Pages 1383-1393, ISSN 0360-3199, https://doi.org/10.1016/j.ijhydene.2024.09.289.0360-3199https://hdl.handle.net/10115/43237Hydrothermal carbonization (HTC) of food waste produces hydrochar—a suitable biofuel—and process water (PW), which has a high organic content suitable for material and energy recovery. In this work, we study the effect of pH (4.8, 5.3, and 6.0) and organic loading rate (OLR; 2.5, 5.0, and 7.5 gCOD L- 1 d- 1) throughout the dark fermentation (DF) of PW from the HTC of food waste (180 ◦C, 1 h) in a continuous stirred tank reactor. The highest hydrogen yield (197.5 mL H2 L- 1 d- 1) was reached at pH 4.8 and OLR 5 gCOD L- 1 d-1, associated with a prevalence of Clostridium bacteria. The highest volatile fatty acids concentration (10.2 gCOD⋅L- 1) was achieved at pH 4.8 and OLR 7.5 gCOD L- 1 d- 1, with a dominance of Actinobacteria phylum. The integrated system HTC-DF allowed a potential energy recovery of 11.2 MJ kg􀀀 1.en-USAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Continuous acidogenic fermentationHydrocharHydrogenHydrothermal carbonizationMicrobial communityVolatile fatty acidsArticlehttps://doi.org/10.1016/j.ijhydene.2024.09.289info:eu-repo/semantics/openAccess