LSU's Christie Working On Water Treatment Through Use Of Membranes

In a lab on the third floor of Patrick F. Taylor Hall, LSU Civil and Environmental Engineering Assistant Professor Kofi Christie is bouncing from one station to another, checking in with the four students who make up the Christie Research Group. The fragile membranes they are creating and working with are relatively small, but if all goes to plan, the knowledge and insight they produce could be huge.

Christie and his students are researching the use of membrane distillation (MD) as a means of water purification. It is among the best available commercial technologies for extracting and recovering clean water from a wide range of water sources, including seawater, inland brackish water, and municipal/industrial wastewater. However, the formation of inorganic foulants—what most people would recognize as salts used for applications such as pharmaceuticals, food preservation, de-icing roads, and construction materials—at the surface of the membranes severely limits water recovery and adversely impacts the overall process efficiency and cost of water produced by MD desalination and water reuse facilities.

The goal of Christie’s project, funded by a grant from the Louisiana Board of Regents, is to advance the understanding of this inorganic fouling at the membrane surface, thereby improving the technology.

“Addressing the global issue of freshwater scarcity, which currently affects 40% of the world’s population, is one of the most significant technological hurdles in the 21st century,” Christie said. “Investigating the long-standing curiosities of dynamic salt-and-water interactions is fascinating! Did you know that some salts dissolve more readily at lower temperatures? This contrasts with table salt (NaCl) dissolving readily into your spaghetti water at a rapid boil.

“Understanding why and how these phenomena occur can help us to design better fouling-prevention technology, enable maximized water reuse from wastewater sources, and achieve stronger climate change resilience. As populations grow and freshwater scarcity increases, it’s becoming increasingly important to design more robust water-treatment technology in order to augment freshwater supplies with unconventional water sources.”

To improve this water-treatment technology, the Christie Research Group will conduct experiments in which the temperature and spatio-temporal chemical composition of the nucleating environment will be precisely controlled across a variety of wastewaters to observe the kinetic and morphological variations in mineral growth. Absorption spectroscopy, electron microscopy, and mass balance analysis will be used to make sense of the results from these experiments.

“Many people living in America take water for granted,” Christie said. “The water quality and water quantity that we have come to expect from our municipalities is maintained by large teams of engineers, chemists, and project managers who work diligently against economic restraints and tight deadlines. I hope that everyone reading this can take a moment to appreciate the people who protect and supply the water that we use to brush our teeth, wash dishes, and flush toilets every day.

“Accordingly, I hope that we can adopt water conservation practices that can help to preserve this precious resource. These can include taking shorter showers, using the dishwasher instead of handwashing, or recycling water-intensive consumer products like clothing and electronics.”