Abstract

Co-pelletization of agro-industrial residues represents a promising route for decentralized and low-carbon bioenergy production. This study investigates the valorization of a cellulose and glycerin-rich granular residue (RI), generated by the food processing industry during sausage manufacturing and currently landfilled through copelletization with coarse olive pits (CA). This strategy addresses the insufficient heating value of the target residue RI for commercial application via mono-pelletization, aiming to convert it into a solid biofuel suitable for industrial biomass boilers while complying with the ISO 17225 specifications. A simplified, low-energy pretreatment was applied, avoiding fine milling (particle size >= 1 mm) and enabling pelletization at high moisture (30-35 %). Four CA/RI blends (10-40 % RI w/w) were evaluated under ISO 17225 standards. The optimal blend (70%CA/30%RI) achieved a higher heating value of 17.6 MJ center dot kg-1, bulk density comparable to commercial wood pellets, and mechanical durability exceeding A2-grade thresholds. Combustion tests revealed lower NOx, SOx, and VOC emissions relative to Pinus radiata pellets, with slightly higher CO levels attributed to laboratory-scale combustion constraints. Olive pits were selected for their local availability and proven suitability as industrial boiler fuel. Life cycle assessment (LCA) indicated a 35 % lower carbon footprint compared to conventional Pinus radiata pellets. Techno-economic analysis estimated a production cost of 162.4 USD center dot t-1 with profitability achievable at a 1,800 t center dot yr-1 scale. These results confirm that simplified co-pelletization of CA and RI is technically feasible, economically viable, and environmentally advantageous, providing a circular bioeconomy pathway for valorizing underutilized food-industry residues.