Commercial scale membrane distillation for solar desalination

• Published in: npj clean water 2018-10, Vol.1 (1), Article 20
• Main Authors: Zaragoza, G., Andrés-Mañas, J. A, Ruiz-Aguirre, A.
• Format: Article
• Language: English
• Subjects: 639/766/25; 704/172; Air gaps; Aquatic Pollution; Boundary conditions; Desalination; Distillation; Earth and Environmental Science; Energy consumption; Energy costs; Energy efficiency; Environment; Heat; Heat recovery; Heat recovery systems; Hollow fiber membranes; Membranes; Nanotechnology; Perspective; Solar energy; Solar power; Spiral wound modules; Thermal energy; Vacuum; Vacuum distillation; Waste Water Technology; Water Industry/Water Technologies; Water Management; Water Pollution Control; Water Quality/Water Pollution
• ISSN: 2059-7037; 2059-7037
• DOI: 10.1038/s41545-018-0020-z

Membrane distillation is an attractive technology for solar-powered decentralized desalination that has not yet reached commercial breakthrough on a large scale. The main barriers are energy consumption and cost. Since the latter are mostly related to the former, thermal energy efficiency is key to assessing the potential of the different available membrane distillation systems at a commercial scale. As discussed here, existing membrane distillation technologies use mostly flat sheet membranes in plate and frame and spiral-wound modules. Modules based on hollow fibre membranes are also considered, as well as the concept of multi-effect vacuum membrane distillation for improved heat recovery. The heat efficiency of each system is analysed based on available experimental results. Better internal heat recovery and capacity for upscaling are found to be important elements of distinction which make multi-channelled spiral-wound modules working in air-gap configuration stand out currently, with the lowest heat consumption of all large scale modules. Potential for improvement of this and other technologies is also discussed, and an estimation based on the associated costs for solar energy is used for establishing boundary conditions towards the implementation of membrane distillation for solar desalination.