Room: Poster Area
Date: Thursday, 21 May 2026
Time: 11:30 - 12:45 CEST
Session code 3CV.4
Processes and concepts
Integrated Hydrothermal Carbonization and Anaerobic Digestion of Agro-Industrial Wastes: Enhanced Volatile Fatty Acid Production and Analytical Benchmarking
Short Introductive summary
Volatile fatty acids (VFAs) are emerging as key platform chemicals that can transform agro-industrial wastes from a disposal problem into a valuable resource. This study demonstrates how combining hydrothermal carbonization (HTC) with anaerobic digestion (AD), supported by advanced analytical tools, can significantly enhance both VFA recovery and bioenergy production. Agro-industrial residues from Lesvos (cheese whey, wine sludge, cocoa, and anise wastes) were processed through HTC (200–250 °C, up to 55 bar) and mesophilic AD (35 °C), with hydrochar or biochar added at low dosages (100 mg per reactor). Char-amended systems achieved biogas yields up to 670 mL/ g VS and produced a broad VFA spectrum dominated by acetic, propionic, and butyric acids, alongside medium-chain acids such as hexanoic and heptanoic acids (100 mg/ L). A direct comparison of GC-FID and GC-BID revealed that plasma-based GC-BID detected up to 10 VFAs, including formic acid (28 mg/ L), which conventional GC-FID failed to resolve. The results highlight the combined importance of process integration and high-sensitivity analytics for reliable VFA valorization within circular bioeconomy systems.
Presenter
Stergios VAKALIS
National Technical University of Athens, School of Chemical Engineering, Process Analysis and Plant Design, GREECE
Presenter's biography
Stergios Vakalis is an Assistant Professor of Energy Processes at the School of Chemical Engineering, NTUA. Stergios works primarily on energy analysis, thermochemical production of biofuels and modeling of energy processes.
Biographies and Short introductive summaries are supplied directly by presenters and are published here unedited
Co-authors:
D. Liakos, National Technical University of Athens, GREECE
S. Vakalis, National Technical University of Athens, GREECE
Session reference: 3CV.4.25