Faster, cleaner, better: revolutionary water treatment
Anthony Straub (r) with PhD student Kian Lopez in a lab.
Anthony Straub is making revolutionary advances in water purification for life on Earth and in space.
Using nanoscale membranes—thinner than 1/100th the width of a human hair—Straub has developed a technology that could significantly improve conventional water treatment, microchip production, and desalination.
His efforts are receiving major recognition from the National Science Foundation, which is honoring Straub with a five-year, $550,000 grant to advance his research.
“We’re excited about this work,” said Straub, an assistant professor in the Department of Civil, Environmental and Architectural Engineering at the University of Colorado Boulder. “For desalination, switching to these membranes could produce 50 times cleaner water while lasting much longer. It’s really a big deal.”
Membrane technology has been in use for water purification for over five decades. It works well for many applications, but filter degradation is a problem, and even at peak conditions, some contaminants can still pass through the membranes.
“Current membranes are very hard to clean,” Straub said. “A major advance of this new membrane is you can expose it to concentrated bleach and cleaning chemicals. It also removes almost every impurity from water – salts, dissolved metals, and organic contaminants like hormones, PFAS, and pharmaceuticals.”
In the new process, Straub traps a tiny layer of air inside a porous membrane. Using pressure, water is forced against the membrane until it evaporates and recondenses on the other side of the air layer. The technology requires no additional electricity or heat and operates with pumps already used in water systems.
“It’s reimagining distillation. Thermal distillation – essentially boiling water – has been used to purify water for centuries, but it is really energy intensive. We’re laying the groundwork for distillation with pressure as the driving force, and it is 10 times more energy efficient,” Straub said.
The technology has advanced beyond the initial research phase. Straub has conducted successful small-scale tests and has two provisional patents on the design. Last year, he co-founded a spinoff company and received a grant from NASA for a prototype purification system for astronauts to use on a future Moon base.
Design of ultrathin air-trapping membranes for pressure-driven vapor transport. For more details, read in the journal Science Advances.
“There were papers discussing this process; the theoretical foundations were there. Our major advance was demonstrating it successfully. We had to understand how to develop materials with really small pore sizes that can trap air,” Straub said.
A major focus of the future work will be better analysis and modeling of the process.
“This technology is transitioning to applied use, but some aspects of the process aren’t as well understood. That’s very important for end users, to know how this design works, how the transport happens. We have some models, but they’re for very idealized systems, which isn’t how things work in the real world,” he said.
Beyond traditional water treatment, the process has drawn significant interest from microchip producers. Semiconductor wafers are manufactured in clean rooms, and ultrapure water is needed to rinse wafers and wash away residue produced during chip etching.
Even the tiniest water impurities can damage the chips, so water must be purified to levels far beyond what is needed for regular drinking water, requiring an expensive, elaborate system. Straub’s technology would dramatically simplify the process and lower costs.
“This is a huge potential market. Companies currently use a treatment process involving at least 14 different steps, and they avoid shutting down the machines because they’re worried that particles could enter the production line,” he said.
In addition to advancing research, Straub is also developing an education and outreach component as part of the CAREER award. Collaborating with a faculty colleague in the mechanical engineering department, Daniel Knight, the pair are developing a project-based water treatment course that will be used in rural K-12 schools across Colorado.
“Lots of these schools are in areas where they don’t have enough water, so this is really important,” Straub said.
He hopes the outreach will be both educational and promote career opportunities for the next generation of water engineers.
“My parents grew up in Latin America in underserved areas,” he said. “In undergrad, I was drawn to improve water treatment in low resource settings, and I caught the research bug. I want to encourage other people, too. It’s about making the world a better place.”