A nanotechnology roadmap for circular wastewater management

Circular wastewater management is increasingly recognized as a critical lever for climate resilience, water security, and the recovery of nutrients, energy, and strategic materials. Yet conventional treatment infrastructures remain constrained by limited selectivity, high energy demand, operational inflexibility, and weak coupling between treatment performance and resource valorization. Although nanotechnology has demonstrated substantial potential to address these bottlenecks, real-world deployment remains fragmented due to fouling, regeneration burdens, scale-up uncertainty, and unresolved safety and governance challenges. This review advances a roadmap that moves beyond material-centric assessments toward a decision-oriented, scale-aware framework for integrating nanotechnology into circular wastewater systems. Drawing on recent laboratory advances, pilot studies, and early demonstrations across municipal, industrial, and agro-food contexts, we situate nano-enabled adsorbents, catalysts, membranes, bio–nano hybrids, and nanosensors within integrated treatment–recovery–reuse platforms, rather than isolated unit operations. Techno-economic and life-cycle evidence is synthesized to identify conditions under which nano-enabled process trains deliver net circular value relative to incumbent technologies. The roadmap explicitly couples nanotechnology with digital intelligence, including nanosensing, AI-enabled monitoring, digital twins, and adaptive control, to translate nanoscale functionality into robust system-level performance under variable influent conditions. To support actionable decision-making, we introduce a pollutant-to-valorization decision matrix, a readiness–impact scorecard, and a 2030 research and standards agenda emphasizing safe-by-design materials, scalable regeneration, antifouling interfaces, hybrid bio–nano reactors, and harmonized risk assessment. By integrating materials science, digital process control, and governance, this roadmap positions nanotechnology as a systems enabler for circular wastewater infrastructure rather than a standalone fix.