Hydrothermal carbonization of mixture waste Gingko leaf and wheat straw for solid biofuel production

Co-hydrothermal carbonization (co-HTC) of ginkgo leaf residues (GLR) and wheat straw (WS) were conducted to investigate the possibility for mutually benefitting the two residues as feedstock to produce solid biofuel pellets. The mass yield, proximate, and elemental analysis of the hydrochar were characterized. The energy consumption during pelletization, pellet density, pellet durability, water resistance ability, and pyrolysis characteristics of hydrochar pellets were evaluated. The results show that when WS blended with 50%, the energy density of pellet increased from to the highest of 26.7 GJ/m3. The ash content decreased from 7.7% to 6.3% when the WS blended with 30%− 70%, while HHV showed a opposite trend. As the WS blended ratio increased from to 30–70%, the high lignin content in WS helped to enhance the mechanical properties of pellet including pellet density, durability, and hardness. The hydrochar pellets from high ratio WS had high devolatilization index indicating increased devolatilization ability. These findings imply adding WS in co-HTC would potentially promote the GLR to manufacture high quality solid biofuel. Overall, the co-HTC of WS and GLR is a promising alternative to transfer solid wastes to renewable fuels.