eNews November 2018

NMSU Student Studying Membrane Distillation with Photocatalysis for Use in Alternative and Brackish Water Restoration

by Catherine Ortega Klett, NM WRRI Program Manager

Lin Chen is a graduate student in the NMSU Department of Civil Engineering, and he is working on his PhD in environmental engineering. He is also
a recipient of a 2018 NM WRRI Student Water Research Grant entitled, “Water Reuse and Desalination with Self-cleaning Photocatalytic Membrane Distillation.”

As an arid region in the United States, New Mexico faces a significant challenge in water resources management due to increasing fresh water demand, economic growth, and chronic droughts. A potential solution to address the water challenge is to develop a highly functional desalination technology, driven by renewable energy, to treat alternative waters (e.g., wastewater, brackish water, etc.). Membrane distillation (MD) is an emerging thermal-driven membrane separation process that utilizes low-grade heat (e.g., solar thermal) for vapor transport. Photocatalysis is another attractive emerging technology that uses solar irradiation to decompose organic pollutants and inactivate microbes. By integrating photocatalysis with MD (PMD), the hybrid membrane can fully utilize solar irradiation to stimulate photocatalytic degradation of organic contaminants in wastewater as well as to heat the feed solution for the MD process. Lin and his faculty advisor Dr. Pei Xu, Associate Professor of the Civil Engineering Department at NMSU, are working together on the development and analysis of high performance PMD membranes.

The overarching goal of the study is to develop a multi-functional self-cleaning PMD system driven by solar energy to deliver potable-quality water and enhance desalination performance. The specific tasks underway include: (1) Development of high-performance membranes, based on their previous work on photocatalysis and superhydrophobic coatings. To this end, silica and TiO2 nanoparticles are being layered onto a ceramic underlying membrane surface. (2) Evaluation of PMD system performance on a bench-scale with synthesized flat-sheet membranes to treat synthetic and real wastewater under solar light irradiation to evaluate system performance. The water quality of feed and product water, and membrane fouling potential are being studied and characterized.

The project may ultimately lead to the development of alternative water supplies in a low-cost, energy-neutral, and environmentally sustainable manner. The novel membrane photoreactor can potentially make the hybrid photocatalysis and membrane distillation a critical technology for integrated water resources management. It could have important applications such as providing safe drinking water for populations living in remote areas, and it may also provide an economically viable means to carry out such important tasks as water reuse, the desalination of brackish water and seawater, and the onsite treatment of oil and natural gas wastewater.

Lin is expecting to graduate with a doctoral degree in environmental engineering in May 2020. He is from China and received undergraduate and master’s degrees from Nanjing Forestry University in Jiangsu Province, China. Lin said recently, “I am lucky to be involved in the project, and I got help from others such as my classmates. I learned a lot from communicating with them on experiment methods, arrangement of study, etc.” He indicated the NM WRRI student grant has been of great assistance, and he presented a poster on his project at the institute’s October annual water conference. Lin Chen says his career goal is to become a professor like his advisor, Dr. Pei Xu.