Sustainability Assessment of Coffee Silverskin Waste Management in the Metropolitan City of Naples (Italy): A Life Cycle Perspective

The use of renewable biological resources, including biowaste, within a circular framework, is crucial for the transition to more sustainable production and consumption patterns. By means of life cycle assessment and life cycle costing methodologies, this study compares the environmental and economic performances of two disposal scenarios for coffee silverskin, the major waste from coffee roasting. The business-as-usual (BaU) scenario, currently applied in the Metropolitan City of Naples (Italy), involves silverskin composting, while the proposed alternative scenario explores the valorization of silverskin as a functional ingredient in bakery products. The alternative scenario results are more advantageous since replacing flour with silverskin in bakery products reduces environmental impact by 96% more than replacing synthetic fertilizers with compost in the BaU scenario. Furthermore, in the alternative scenario, coffee roasters halve their silverskin disposal costs, compared to the BaU scenario (447.55 € versus 190.09 €, for 1 ton). Finally, the major environmental burdens are resource use for equipment construction (37% for BaU, 62% for alternative, on average) and electricity consumption (30% for BaU, 67% for alternative, on average), while the highest economic cost is due to personnel (58% for BaU, 88% for alternative, on average).