Gravity-driven highly selective ultrafiltration: a sustainable solution for addressing global drinking water scarcity

This review explores the potential of gravity-driven ultrafiltration (GDU) systems as a sustainable solution to global drinking water challenges. Leveraging hydrostatic pressure instead of external energy inputs, GDU systems offer a low-maintenance, cost-effective approach well-suited for decentralized and resource-constrained settings. The paper provides a detailed analysis of the fluid dynamics and transport mechanisms that underpin GDU operation, emphasizing the influence of biofilm formation, membrane morphology, and material selectivity on system performance. Recent advancements in membrane materials have demonstrated significant improvements in antifouling performance, flux stability, and contaminant removal. Innovative membrane designs are also reviewed for their potential to enhance adaptability and multifunctionality. Real-world case studies highlight the operational feasibility and economic advantages of GDU systems, while identifying key barriers such as long-term reliability, feedwater variability, and limited community-based monitoring capacity. Socio-economic considerations, including modular design strategies and institutional engagement, are examined to support scalable implementation. This comprehensive review offers interdisciplinary insights to inform future research, technology development, and policy planning aimed at advancing sustainable water purification solutions worldwide.