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Open Access Publications from the University of California

Enhanced solar evaporation using a photo-thermal umbrella for wastewater management

  • Author(s): Menon, AK
  • Haechler, I
  • Kaur, S
  • Lubner, S
  • Prasher, RS
  • et al.

© 2020, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply. Zero-liquid discharge is an emerging wastewater management strategy that maximizes water recovery for reuse and produces a solid waste, thereby lowering the environmental impact of wastewater disposal. Evaporation ponds harvest solar energy as heat for zero-liquid discharge, but require large land areas due to low evaporation rates. Here, we demonstrate a passive and non-contact approach to enhance evaporation by more than 100% using a photo-thermal device that converts sunlight into mid-infrared radiation where water is strongly absorbing. As a result, heat is localized at the water’s surface through radiative coupling, resulting in better utilization of solar energy with a conversion efficiency of 43%. The non-contact nature of the device makes it uniquely suited to treat a wide range of wastewater without contamination, and the use of commercial materials enables a potentially low-cost and highly scalable technology for sustainable wastewater management, with the added benefit of salt recovery.

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