Freshwater scarcity, intensified by population growth, urbanization, and industrial development, has positioned desalination as a critical solution for augmenting global water supplies. This paper presents a comprehensive review of desalination technologies, covering both mature processes—such as Reverse Osmosis (RO), Multi-Stage Flash (MSF), and Multi-Effect Distillation (MED)—and emerging methods, including Forward Osmosis (FO), Nanofiltration (NF), Electrodialysis (ED), Capacitive Deionization (CDI), Hydration (HY), and Secondary Refrigerant Freezing (SRF). Each technology is described in terms of its operating principles, energy requirements, advantages, limitations, and readiness level. Schematic diagrams are provided for all processes, accompanied by a comparative table summarizing key parameters such as feedwater type, energy consumption, and development status. The analysis highlights the dominant role of RO in the global market, accounting for nearly 70% of total installed capacity, and underscores the growing interest in hybrid and renewable-powered systems as promising pathways for improving efficiency and sustainability. In addition, environmental concerns associated with brine disposal are recognized as a major challenge influencing technology choice and future research priorities. The review identifies significant opportunities for innovation in desalination, particularly in integrating renewable energy sources, improving brine management, and developing low-energy processes. Future research should focus on enhancing energy recovery, optimizing hybrid configurations, and scaling up promising emerging technologies to achieve cost-effective and environmentally sustainable desalination solutions.
Sodiq A Alaka (Fri,) studied this question.