Advancing circular economy in Amazonian forest management: A comparative study of the effects of wood waste segregation and traditional carbonization on charcoal properties, combustibility, and spontaneous combustion risk

This study integrates legal timber harvesting, conservation efforts, and circular economy concepts in Amazonia by converting wood waste into charcoal via real-scale kilns in remote regions. Emphasizing the benefits of species-based segregation, residues from 23 tropical species were classified via principal component analysis into four distinct Groups (G1—G4), whereas G5 represented traditional mixed-species carbonization. A novel approach was used to assess the impact of species-based segregation on charcoal quality, combustion behavior, and logistical safety (spontaneous combustion risk) through proximate and calorific analyses, thermogravimetric analysis, combustion indices, and self-combustion experiments. To support the selection of high-performance and safer biofuels, multi-criteria decision analysis (MCDA) was applied to systematically rank charcoal groups by integrating physicochemical and thermal performance indicators. The segregated groups exhibited variations in fixed carbon (69.61—73.92%, dry basis (db)), volatile matter (21.87—27.58%, db), ash content (1.20—6.03%, db), and higher heating value (26.5—30.0 MJ·kg⁻¹). G1 (Dinizia excelsa) had the highest fixed carbon content, lowest ash content, and superior combustion behavior, whereas G5 had a lower ignition temperature and greater reactivity. Spontaneous combustion tests revealed no self-ignition in G1 and G4, whereas G2, G3, and G5 presented incidence rates of 75%, 50%, and 25%, respectively. MCDA enables a robust, multi-indicator evaluation of charcoal performance, producing a ranking (G1 > G4 > G5 > G3 > G2) that is consistent with the spontaneous combustion results. These findings highlight the potential of selective biomass utilization to produce higher-quality, safer, and more sustainable charcoal, reinforcing its role in circular bioenergy systems in the Amazon.