Routes for reuse of aged pressure-driven membranes: Current status and future perspectives

The rapid expansion of reverse osmosis (RO) desalination generates millions of end-of-life (EoL) membrane elements each year, most of which are still landfilled. This review examines the technical and practical routes available to divert these polymers from disposal, while also refining the existing hierarchy of membrane reuse. The analysis encompasses temporary storage, rewetting, cleaning, direct reuse, recycling, and upcycling, providing a comprehensive framework that connects laboratory findings with practical implementation. Chlorine-based oxidation—especially NaClO—emerges as the most mature option, reliably converting EoL RO modules into ultrafiltration- or nanofiltration-like membranes with viable costs (∼US$ 8 per element). Upcycling methods such as layer-by-layer coatings, interfacial polymerization, and ion-exchange grafting widen functionality but remain lab-scale, hindered by adhesion, fouling, and scale-up barriers. Standardized protocols, long-term field data, and supportive business models are now critical for industrial adoption and circular water management. This review also assessed the maturity of each technique, noting that most strategies are not yet ready for larger-scale deployment, and it introduces a quantitative bibliometric map of the field and proposes an expanded, processual hierarchy tailored to pressure-driven membranes. By coupling evidence-based literature analytics with an updated ordering of EoL options (prioritized direct reuse, staged RO → NF → UF conversion, advanced upcycling, and pre-disposal material recovery), the paper provides a novel, actionable framework for closing the loop in membrane technology.