Exploration on physicochemical properties and combustion behaviors of hydrochar from co-hydrothermal carbonization of swine manure and tea waste

Co-hydrothermal carbonization (co-HTC) of animal manure and lignocellulosic biomass is recognized as an innovative approach to improve the quality of hydrochar derived from the HTC of animal manure. This study explored the effects of mass mixing ratio and temperature on the physicochemical properties and combustion behaviors of hydrochar from co-HTC of swine manure (SM) and tea waste (TW). The synergistic effect between SM and TW promoted the deoxygenation of SM and the aromatization of hydrochar. Compared to hydrochar from HTC of SM, the carbon content and higher heating value increased considerably, reaching the maximum of 48.64 % and 19.94 MJ/kg, respectively. Less lamellar structure and numerous microspheres were observed on the surface of hydrochar produced at 250 °C with 1/1 mass ratio. Additionally, the combustion performance of hydrochars from co-HTC were improved, as indicated by increases in the comprehensive combustion index and combustion stability index. Kinetic analysis showed that the activation energy of hydrochar increased with the increasing TW proportion and temperature. These findings provided valuable insights into the co-HTC of SM and TW, supporting the effective upgrading of animal manure and lignocellulosic biomass. • Synergistic effect promoted deoxygenation of SM and aromatization of hydrochar. • Hydrochars from co-HTC exhibited higher HHV values than HC-SM. • The surface of HC-250-2-1/1 showed less lamellar structure and numerous microspheres. • Combustion behaviors and activation energy of hydrochars from co-HTC were improved.