Sustainable Valorization of Spent Coffee Grounds Within the Circular Economy: Innovative Applications in Food, Agriculture, Environmental, and Industrial Sectors

Spent coffee grounds (SCGs) are one of the most abundant agro-industrial by-products worldwide, with 650 kg generated per ton of green coffee processed, corresponding to an estimated global production of 6.7 million tons in 2022/2023. Improper disposal of SCG raises environmental concerns, while their reuse offers opportunities for sustainable resource management and circular economy strategies. This review examines SCG valorization by addressing their chemical composition, functional properties, and key applications in sectors such as food, agriculture, environmental remediation, bioenergy, and selected industrial fields, including pharmaceuticals, cosmetics, construction materials, and functional devices. In this context, it discusses technological approaches, performance outcomes, and implementation considerations, emphasizing the multifunctional potential of SCGs as a renewable feedstock capable of reducing waste, improving resource efficiency, and generating economic value. By consolidating the current state of knowledge and exploring diverse valorization pathways, this work frames SCG utilization within a circular bioeconomy framework and highlights how innovative applications can transform this widely available waste into sustainable and economically valuable products.