Woodruff School of Mechanical Engineering

Faculty Candidate Seminar


Solar-driven desalination and wastewater management via radiative heating


Dr. Akankska Menon


Lawrence Berkeley National Laboratory


Thursday, February 6, 2020 at 2:00:00 PM


MRDC Building, Room 4211


Dr. Devesh Ranjan


The global demand for water is projected to increase by 55% by 2050, and this has brought the treatment of non-traditional waters to the forefront. While techniques to remove salt and other contaminants from water have existed for centuries, the use of electricity or high-grade thermal energy still accounts for half the cost of desalinated water. Furthermore, the water-energy nexus necessitates the treatment of water in a manner that minimizes the use of high quality energy resources. In this scenario, integration of desalination technologies with renewable energy offers a unique opportunity to reduce the cost of water, as well as emissions associated with wastewater treatment and management. Evaporation ponds harness solar energy to passively evaporate water from waste streams to achieve zero-liquid discharge. However, efficient utilization of solar energy for evaporation is limited by the transparency of water at these wavelengths. To address this, I will discuss the development and application of a photo-thermal converter for radiative heat localization at the water surface that enhances evaporation and achieves ZLD. The second part of this talk will focus on an emerging desalination technology, forward osmosis, which is suitable for high salinity waters that cannot be treated by state-of-the-art reverse osmosis. FO uses a draw solution to drive water flux across a membrane. However, the separation of the draw from water to produce clean water requires significant energy, thereby limiting its applicability. To address this, I will introduce a novel class of thermally responsive draw solutes that can be regenerated using solar heat to yield clean water. Beyond desalination, the temperature-dependent morphology of these soft materials can be leveraged to modulate heat and mass transport for the next generation energy and water systems, with applications ranging from low-energy separations, to dynamic buildings optimized for thermal comfort.


Dr. Akanksha Menon is an ITRI-Rosenfeld Postdoctoral Fellow advised by Dr. Ravi Prasher at Lawrence Berkeley National Laboratory. Her current research is focused on treating high salinity wastewater using solar energy and novel membrane technologies, with the goal of recovering water for reuse and achieving zero liquid discharge. Akanksha obtained her Ph.D. in Mechanical Engineering from Georgia Tech in 2018, where she developed polymer thermoelectric materials and devices for energy harvesting in lab of Prof. Shannon Yee. Akanksha is a recipient of the 2019 Sigma Xi Dissertation Award and the 2017 MRS Graduate Student Silver Award for outstanding materials research. She has served as the Co-President of the Energy Club @ Georgia Tech and founded the Water Wednesday initiative at Berkeley Lab.


Refreshments will be served.