Advances and Perspectives on Valorization of Grape Pomace into Functional Materials for Water and Wastewater Purification

The wine industry generates large quantities of grape pomace (GP), a lignocellulosic by-product rich in fibers, polyphenols, lipids, and minerals. Improper management and disposal of GP can lead to significant environmental impacts, whereas its valorization creates significant opportunities within a circular economy framework. This review examines the conversion of GP from an agro-industrial residue into functional materials for water and wastewater treatment. Recent advances in GP characterization, thermochemical conversion into biochars, development of hybrid silica- and biopolymer-based composites, and the use of polyphenol-rich extracts for green synthesis of nanomaterials are critically reviewed. GP-derived materials have exhibited high removal efficiencies for dyes, heavy metals, and emerging contaminants, while hybrid systems improve stability, selectivity, and catalytic performance. Despite promising laboratory-scale results, major challenges remain regarding regeneration efficiency, long-term stability, and scalability, which currently limit the competitiveness of GP-derived materials compared to commercial adsorbents. Furthermore, the lack of comprehensive life cycle assessment and techno-economic analysis hinders the validation of their environmental and economic viability, underscoring the need for integrated assessments to guide sustainable implementation. Overall, GP is positioned as a second-generation residue with strong potential for cascading valorization strategies that integrate high-value compound recovery with environmental applications, supporting the development of sustainable water purification technologies.