Enhancing water sustainability with direct contact membrane desalination: technological innovations and challenges

Freshwater scarcity poses a critical challenge to human survival, necessitating innovative desalination solutions to meet the growing global demand for potable water. Among these, membrane distillation (MD) has emerged as a promising technology due to its high salt rejection efficiency, lower energy consumption compared to conventional thermal desalination methods such as multi-stage flash (MSF) and multi-effect distillation (MED), and its adaptability to diverse water sources, including seawater, brackish water, and wastewater. Within MD, direct contact membrane distillation (DCMD) has gained significant attention for its simplicity, high desalination flux, and potential cost-effectiveness. Unlike other MD variants, DCMD operates without requiring expensive external condensers, making it economically attractive for large-scale deployment. However, despite these advantages, DCMD faces challenges such as membrane fouling, thermal polarization, and limited long-term stability, all of which can degrade performance and increase operational costs. This review provides a comprehensive overview of DCMD technology, focusing on membrane module design, material selection, and fabrication techniques. It also addresses key operational challenges and explores innovative strategies to enhance system efficiency. Additionally, it presents an up-to-date analysis of the economic and environmental implications of DCMD and its feasibility for large-scale implementation. By offering a thorough understanding of this technology, the review aims to facilitate its optimization and unlock its full potential as a sustainable solution to global freshwater scarcity.