Catalytic co-hydrothermal carbonization of food waste digestate and yard waste for energy application and nutrient recovery

• Published in: Bioresource technology Vol. 344; no. Pt B; p. 126395
• Main Authors: He, Mingjing, Zhu, Xiefei, Dutta, Shanta, Khanal, Samir Kumar, Lee, Keat Teong, Masek, Ondrej, Tsang, Daniel C.W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2022
• Subjects: Bioenergy; biomass; Carbon; citric acid; combustion; energy; energy content; energy recovery; Food; food waste; Food waste hydrochar; hydrochars; hydrothermal carbonization; lignocellulose; Nutrients; Refuse Disposal; Resource recovery; Solid fuel; Sustainable waste management; technology; Temperature; Yard waste recycling; yard wastes; Yard waste recycling; Resource recovery; Bioenergy; Solid fuel; Food waste hydrochar; Sustainable waste management
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2021.126395

[Display omitted] •Non-catalytic co-HTC of FWD and YW marginally increased energy potential of hydrochar.•Co-HTC with 0.5 M HCl exhibited the highest carbon utilization efficiency.•Co-HTC with citric acid provided ∼3-fold increase in pressure with ∼74% C loss.•Catalytic system of 0.5 M HCl had better overall energy and nutrient recovery performance.•Ash content and mineral constituents were the decisive factors for combustion behaviour. Hydrothermal carbonization (HTC) provides a promising alternative to valorize food waste digestate (FWD) and avoid disposal issues. Although hydrochar derived from FWD alone had a low calorific content (HHV of 13.9 MJ kg−1), catalytic co-HTC of FWD with wet lignocellulosic biomass (e.g., wet yard waste; YW) and 0.5 M HCl exhibited overall superior attributes in terms of energy recovery (22.7 MJ kg−1), stable and comprehensive combustion behaviour, potential nutrient recovery from process water (2-fold higher N retention and 129-fold higher P extraction), and a high C utilization efficiency (only 2.4% C loss). In contrast, co-HTC with citric acid provided ∼3-fold higher autogenous pressure, resulting in a superior energy content of 25.0 MJ kg−1, but the high C loss (∼74%) compromised the overall environmental benefits. The results of this study established a foundation to fully utilize FWD and YW hydrochar for bioenergy application and resource recovery from the process water.