Advanced nanocomposite membranes for sustainable water reuse in agriculture

Agricultural irrigation accounts for the large majority of global freshwater withdrawals, and mounting water scarcity is driving increased interest in reusing municipal, industrial, and agricultural wastewater as an irrigation source. Membrane-based treatment spanning microfiltration, ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, membrane bioreactors, and membrane distillation already underpins much of this reuse, but conventional membranes remain constrained by fouling, high energy demand, and an inherent trade-off between removing contaminants and retaining agronomically valuable nutrients. This review examines nanocomposite membranes as a materials-based strategy for overcoming these limitations. It surveys the classification of nanomaterials used in membrane design (zero-to three-dimensional fillers, including metal/metal oxide nanoparticles, carbon nanotubes, graphene oxide, and metal-organic frameworks, as well as emerging bio-based alternatives) and the principal fabrication routes dope blending, interfacial polymerization, surface coating, electrospinning, and in situ growth used to integrate them into polymeric and ceramic matrices. Evidence from the literature is synthesized across key performance dimensions relevant to agricultural reuse: water permeability and flux, fouling resistance and antimicrobial activity, selectivity and contaminant rejection, and mechanical, thermal, and chemical stability, with particular attention to configurations such as photocatalytic and antimicrobial nanofiltration membranes and fertilizer-drawn forward osmosis systems that target nutrient-selective performance. The review finds that nanocomposite modification can produce substantial, mechanism-specific improvements over pristine membranes, but that translating these laboratory-scale gains into field-scale agricultural practice will depend on resolving open questions around nanoparticle leaching and environmental safety, manufacturing scalability, and cost. Emerging directions, including machine-learning-guided membrane design, hybrid process integration, and green-synthesized nanomaterials, are identified as promising routes toward more sustainable, field-ready nanocomposite membrane technologies for agricultural water reuse.