Evaluation on thermal treatment for sludge from the liquid digestion of restaurant food waste. (December 2021)

• Record Type: Journal Article
• Authors: Liu, Jingxin; Huang, Simian; Wang, Teng; Mei, Meng; Chen, Si; Zhang, Wenjuan; Li, Jinping
• Is Part Of: Renewable energy. Volume 179(2021)
• Page Start: 179
• Page End: 188
• Publication Date: 2021-12
• Subjects: Restaurant food waste -- Anaerobic digestion sludge -- Pyrolysis -- Combustion -- Gaseous emission; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2021.07.022
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: During the anaerobic digestion of restaurant food waste, the sludge obtained as the sediment from the liquid digestate (LDS) is a high–yield solid waste. However, its valorization has not attracted sufficient attention. This study systematically detected the physicochemical properties of this sludge, proposed and evaluated thermal strategies of pyrolysis and combustion. Pyrolysis was a mild endothermic process with considerable H2 O, CO2, and hydrocarbon releasing, and the LDS-derived biochar had pore structures and abundant functional groups. Combustion was exothermic in a broad temperature interval of 140 °C–580 °C with emissions of H2 O, CO2, and NH3, but the process was mild and slow, revealing the poor combustibility of LDS, in addition, the ash had a medium deposition tendency. According to the results obtained in this study, pyrolysis was suggested as a more appropriate method for the reduction and reutilization of LDS. This work will be useful and helpful for LDS valorization, thereby, facilitating the spread and popularization of anaerobic digestion of food waste. Highlights: Properties of the sludge from liquid digestion of food waste were characterized. Strategies of pyrolysis and combustion were proposed and systematically evaluated. Pyrolysis was an endothermic process with emissions of H2O, CO2, and hydrocarbon. Combustion was exothermic, H2O, CO2, and NH3 accounted for ∼99% of the evolved gases. The pyrolytic biochar and combustion ash show different utilization potentials.