Enhanced energy recovery of non-hazardous organic wastes via moderate pyrolysis with natural calcium- and potassium-based additives

The current research focuses on the efficiency of energy recovery from non-hazardous organic wastes. It entails the generation of low-chloride refuse-derived fuel (RDF) from municipal solid waste (MSW) through moderate pyrolysis of combustible components. The moderate pyrolysis settings and composition ratio of biogenic/non-biogenic content from MSW combination (food waste, plastic waste, and paper waste) had a significant impact on the thermochemical characteristics and fuel behavior of RDF. Furthermore, pyrolysis with optimal MSW composition was studied to reduce toxic elements (chlorides, sulphides, and nitrides) and enhance the energy value in RDF by utilizing potassium-rich (waste orange peels (OP); banana peels (BP); and maize cob (MC)) and calcium-rich species (waste animal bone meal (ABM); egg shells (ES); and mussel shells (MS)) as natural additives. The results showed that increasing the pyrolysis temperature maximized the carbon concentration with reduced oxygen moieties (low O/C ratio), indicating a high energy value as the oxygenates were eliminated during moderate pyrolysis. The RDF treated at 400 °C (SF4-400) with MSW composition of 55% non-biogenic carbon and 45% biogenic carbon resulted in HHV of 29.22 MJ kg −1 , the lowest ash concentration (0.96%), and a densified microstructural surface. The addition of natural maize cob additive into MSW (SF4-400-MC) yielded the maximum HHV (33.07 MJ kg −1 ) with considerable reductions in chlorides (71.43%), sulphides (87.50%), and insignificant nitrides content, all of which meet ASTM RDF quality criteria Grade I.