Water scarcity is a pressing global challenge affecting over 2.2 billion people. The increasing demand for freshwater, driven by population growth, water pollution, industrialisation, urbanisation and climate change, has intensified pressure on conventional freshwater sources. With over 97% of Earth’s water stored in oceans, desalination of seawater has become an increasingly attractive strategy to augment water supply, particularly in arid and semi-arid regions. Conventional desalination technologies, including reverse osmosis (RO), multi-stage flash distillation, multi-effect distillation, and electrodialysis, have demonstrated high efficacy in converting saline water into potable water. However, these systems are associated with several critical drawbacks, including high energy consumption, greenhouse gas (GHG) emissions, substantial operational and capital costs, and the generation of concentrated brine, which can severely impact marine ecosystems when discharged untreated. For instance, RO plants typically consume 3–4 kWh/m3, while thermal desalination approaches may require 10–15 kWh/m3. Furthermore, fossil-fuel driven desalination contributes approximately 0.3–1.7 kg CO2 per m3 of water produced, highlighting the urgent need for more sustainable and energy-efficient desalination solutions. Biodesalination has emerged as a promising alternative, harnessing biological systems and bioinspired mechanisms for salt removal. This paper explores the principles, mechanisms, recent advances, and prospects of biodesalination as a sustainable approach. These include: (i) aquaporin-based biomimetic membranes that offer exceptional water permeability and selectivity; (ii) microalgal systems such as Chlorella vulgaris and Arthrospira platensis capable of 28–82% salt removal through biosorption and bioaccumulation; (iii) genetically engineered cyanobacteria with enhanced ion-exchange capacities; (iv) halophilic microorganisms capable of thriving in high-salinity environments; (v) halophyte-based phytodesalination; and (vi) microbial desalination cells (MDCs), which integrate desalination with wastewater treatment and bioelectricity generation (achieving up to 1.8 kWh/m3). Biodesalination offers a low-energy, sustainable alternative to tackle the global freshwater crisis. Leveraging biological and nature-driven processes alongside engineering innovations and data-driven optimisation and scale-up, it can complement or partially replace conventional desalination, contributing to achieving the UN Sustainable Development Goal 6 (Clean Water and Sanitation).
Keshavarz et al. (Thu,) studied this question.