Combustion behavior of refuse-derived fuel produced from sewage sludge and rice husk/wood sawdust using thermogravimetric and mass spectrometric analyses

Waste-to-energy conversion is an environmentally friendly way for disposing of sewage sludge (SS), with this study investigating the use of rice husk (RH) and wood sawdust (WS) as agricultural/forestry wastes for production of sludge-based refuse-derived fuel (RDF). Thermogravimetric and mass spectrometric (TG-MS) analysis has been used to investigate the combustion characteristic, interactions and kinetics of the RDFs, with the gaseous emissions produced during combustion being analyzed. These results reveal that introduction of RH and WS can improve the combustion stability, burnout characteristics and SO2 emission, however, higher NO (NO and NO2) levels are produced. Interactions within the fuel promote combustion of volatiles and the release of SO2 and NO, with a reduction in the reaction of char, as well as the generation of NO2. Addition of biomass leads to an increase in activation energy of the combustion process for RDF relative to SS, particularly in the presence of RH. Diffusion, interfacial reactions and nucleation processes were shown to be the dominant factors affecting the combustion kinetics of RDF. (C) 2019 Elsevier Ltd. All rights reserved.