Integration of the pelletization and combustion of biodried products derived from municipal organic wastes: The influences of compression temperature and pressure

Abstract

Derived through the biodrying of municipal organic wastes (MOWs), biodried products (BPs) are widely accepted as carbon-neutral and renewable fuels. In this study, for efficient combustion utilization of BPs, the pelletization and combustion of BPs were investigated based on the effects of compression temperature and pressure. During pelletization, organics from MOWs were found to decrease the energy consumption and moisture absorption, and the organics bonding and lignin softening synergistically improved the hardness and durability of the pellets, especially at a temperature of 120 °C and at pressures above 100 MPa. Furthermore, this pelleting temperature was indicated to improve the heating values and thermal stabilities of the BP samples with higher C/O ratios and activation energies (146.85–149.29 kJ/mol). In addition, high compression pressures enhanced the ignition delays of the BP pellets, and these delays could promote devolatilization with complete combustion. Consequently, the pelleting pressures had no significant influences on the NO and SO2 emission amounts, but brought about higher emissions of metal elements. In summary, under optimized temperature and pressure levels, the BP pellets exhibited desirable properties and upgraded combustion characteristics for energy recovery. By integrating biodrying with pellet combustion, this study provided an efficient alternative for MOW management.