Leather waste valorization as solid fuel for thermal energy

Solid waste is an attractive renewable resource for thermal energy systems in the effort to reduce greenhouse gases(GHG) emissions globally. Footwear industries play a significant role in many countries, and generate a huge amount of LeatherSolid Waste (LSW) in forms of scraps and losses as strips, sides, or edges, powdered or compacted. The objective of this workwas to investigate the characteristics of LSW, originated in footwear industries, as it serves as a solid fuel that can be convertedinto thermal energy. Experimental tests for evaluation of solid fuel characteristics included proximate and ultimate analysis, highheating value, bulk and energy density, and also the particle size distribution. The bulk and energy density achieved were low(110 kg.m-3and 2 GJ.m-3, respectively), and densification could provide a more interesting solid fuel. The LSW has characteristicssimilar to biomass, particulary in terms ofvolatile matter (76%)and fixed carbon (17%) on a dry basis, and for hydrogen/carbon(H/C) and oxygen/carbon (O/C) ratios in the same magnitude asEucalyptuswood. The high ash content (7%) demands the sameoperational care in thermal equipment, as in sugarcane bagasse combustion.The achieved moisture of 12% showed that it doesnot require artificial drying for combustion.LSW has a goodhigh heating value(HHV), of approximately 20 MJ.kg-1, which ishigher compared to typical biomasses such as sugarcane bagasse or agricultural residues. All the relevant characteristics forthegood quality of a solid fuel are present in the evaluated LSW.