The effects of the modification of biodegradation and the interaction of bulking agents on the combustion characteristics of biodried products derived from municipal organic wastes

Abstract

Biodried products (BPs) derived from municipal organic wastes have been identified as renewable and attractive solid fuels. The combustion characteristics of BPs are closely associated with the bulking agent used as well as with the properties of the waste and are influenced by biodegradation during biodrying. In this study, thermogravimetry was performed on BPs using different bulking agents (corncob, straw and sawdust). The results indicated that organic wastes were more flammable than biomass, with lower Ea (77.88–83.55 kJ/mol), but the biomass exhibited higher combustion parameters; their interaction resulted in intensified performance during BP combustion. Based on BP combustion kinetics, biodegradation was shown to decrease organic devolatilization, accelerate lignocellulose decomposition and promote char formation. Furthermore, compared with lignite, BPs showed lower ignition temperatures (<525 K) and Ea evolutions, and the BPs also showed high combustion indexes and heating values, especially the BPs using sawdust. In addition, except for CO2, CO and H2O, negligible CO and CC vibrations were observed during devolatilization, and low heavy metal contents were detected in the combustion ashes. In general, the BP combustion behaviours intensified by the bulking agents and modified by biodegradation, and the BPs exhibited favourable and eco-friendly combustion characteristics for energy recovery.