LAUSR

Abstract The aim of this study was to investigate the anaerobic granular sludge (AGS) as feedstock for hydrochar production using the hydrothermal carbonization (HTC) process. HTC experiments were conducted at 250 °C for 2 h. The hydrochar produced was then co-pelletized with yard waste to produce densified biofuel pellets. The hydrochar yield was around 80%, while the hydrochar energy yield was around 93%. The calorific value of hydrochar increased to approximately 19 MJ/kg as compared to 16 MJ/kg for the raw AGS. HTC improved the combustion behavior of hydrochar by improving ignition and burnout temperatures. Hydrochar pellets were able to withstand the compressive force of 3.10 MPa as compared to 2.44 MPa by raw AGS pellets thus proving its enhanced robustness. This study demonstrated that combined HTC and pelletization could be integrated with the wastewater treatment plant for solid biofuel production from AGS, providing a valuable renewable energy source.