​A new distillation device can better recycle contaminants produced by a desalination plant to dramatically reduce waste.

When sea water is purified using reverse osmosis membranes, a liquid brine containing salts and other impurities is often disposed of directly into the environment. Strict regulations are now pushing desalination plants to adopt zero liquid discharge principles to treat this waste water. Current technologies, however, rely on expensive electrical or thermal treatments to concentrate the brine.

A more sustainable approach is now being investigated by Peng Wang and colleagues from the Water Desalination and Reuse Center at KAUST. The team is developing solar photothermal distillation devices that can convert sunlight into heat. When placed upon a typical sample of liquid brine, these photothermal devices can evaporate water with 90 percent energy efficiency.

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Image: The 3D-cup-shaped solar evaporator at increasing time intervals (l-r) at 0, 24, 48, 72, 96 and 120 hours.
Reproduced under a Creative Common 4.0 License from reference 1 © 2018 Shi et al.