# Enhanced solar evaporation using a photo-thermal umbrella: towards zero liquid discharge wastewater management

**Authors:** Akanksha K. Menon, Iwan Haechler, Sumanjeet Kaur, Sean Lubner, Ravi S. Prasher  
**arXiv:** [1905.10394](https://arxiv.org/abs/1905.10394)  
**Date:** 2019-05-24  
**Summary page:** https://www.summarizepaper.com/en/paper/1905.10394v1/

## Key points

- Increasing demand for water and depletion of freshwater resources require sustainable water management
- Global push towards Zero Liquid Discharge (ZLD) to maximize water recovery for reuse while reducing environmental impact of wastewater disposal
- Traditional evaporation ponds used for ZLD require large land areas due to low evaporation rates
- A new approach using a photo-thermal umbrella enhances evaporation by more than 100%
- Device converts sunlight into mid-infrared radiation where water strongly absorbs energy, enabling efficient utilization of solar energy and heat localization at the water surface through radiative coupling
- Passive and non-contact method is cost-effective and scalable due to construction from commercially available materials
- Added benefit of salt recovery which can be used in various applications such as agriculture or industrial processes
- Innovative approach has significant implications for achieving Zero Liquid Discharge goals while reducing land requirements and environmental impact associated with traditional evaporation ponds.

## Summary

The increasing demand for water and the depletion of freshwater resources have led to a growing need for desalination and wastewater treatment technologies to achieve sustainable water management. To this end, there is a global push towards Zero Liquid Discharge (ZLD) with the aim of maximizing water recovery for reuse while producing solid waste that reduces the environmental impact of wastewater disposal. However, traditional evaporation ponds used for ZLD require large land areas due to their low evaporation rates. In this study, Akanksha K. Menon, Iwan Haechler, Sumanjeet Kaur, Sean Lubner, and Ravi S. Prasher present a new approach to enhance evaporation by more than 100% using a photo-thermal umbrella. This device converts sunlight into mid-infrared radiation where water strongly absorbs energy, enabling efficient utilization of solar energy and heat localization at the water surface through radiative coupling. This passive and non-contact method is uniquely suited to treat a wide range of wastewater types while being cost-effective and scalable due to its construction from commercially available materials. Furthermore, it has the added benefit of salt recovery which can be used in various applications such as agriculture or industrial processes. This innovative approach has significant implications for achieving Zero Liquid Discharge goals while reducing land requirements and environmental impact associated with traditional evaporation ponds. Consequently, it provides an effective solution for sustainable wastewater disposal with multiple benefits that make it an attractive alternative to existing methods.