Waste valorisation has become a key strategy for applying circular economy principles in the agro-industrial field. This study investigated the territorial implementation of the waste composting on a territorial scale. The wastes considered were the post-processing orange waste, spent olive oil pomace, and spent wine grape pomace. Their potential use as soil amendments across the provinces of Sicily was assessed through a GIS-based analysis, taking into account nitrogen (N) application constraints. Moreover, a cascade valorisation scheme was also evaluated: post-processing orange waste was first used as animal feed, and the remaining fraction was directed to composting; olive pomace was first sent to pomace oil extraction mills, and the residual material was subsequently used for composting. Results indicate that N inputs derived from composted residues remain below legal thresholds in all provinces, with relative contributions ranging from 38% to 92% of the regulatory limits. Spatial variability in nitrogen availability reflects the territorial distribution of agro-industrial activities, highlighting the importance of localised management strategies. These findings demonstrate that composting, combined with cascade valorisation, is an effective pathway to close nutrient cycles, reduce waste generation, and support sustainable biomass management in regional agri-food systems.
Cinardi et al. (Fri,) studied this question.