1. Valorization of process water from hydrothermal carbonization of food waste by dark fermentation.
- Author
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Diez, M.P., Barahona, E., de la Rubia, M.A., Mohedano, A.F., and Diaz, E.
- Subjects
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HYDROTHERMAL carbonization , *FOOD waste , *PH effect , *FATTY acids , *POTENTIAL energy , *UPFLOW anaerobic sludge blanket reactors - Abstract
Hydrothermal 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 g COD 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 H 2 L−1 d−1) was reached at pH 4.8 and OLR 5 g COD L−1 d−1, associated with a prevalence of Clostridium bacteria. The highest volatile fatty acids concentration (10.2 g COD ·L−1) was achieved at pH 4.8 and OLR 7.5 g COD 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. [Display omitted] • HTC process water from food waste has suitable characteristics for dark fermentation. • Optimal H 2 production was found at pH 4.8 and organic loading rate of 5 g COD L−1 d−1. • Highest VFA production was obtained at pH 4.8 and 7.5 g COD L−1 d−1. • The energy recovery of the coupled process achieved the 63.3% from food waste. • H 2 yield and VFA production rate is driven by dominant microbial consortia. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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