ARTICLE BY ALICE DETERS | PHOTOS BY JAMIE MOON AND MELODY SCHMIDT
The idea of using LED light to purify water might sound like something from a futuristic science-fiction movie, but thanks to a group of chemical engineering students at The University of Alabama, the future might be closer than you think.
As part of a U.S. Environmental Protection Agency competition, a team of UA students was one of only 42 collegiate groups selected to design sustainable, alternative solutions to environmental challenges. The students chose to explore a new method of disinfecting water using ultraviolet LED lights instead of traditional UV lamps, which create harmful mercury waste and are inefficient compared to LED technology.
“There are so many real-world applications for this research,” says Cheryl Clifton, a member of the team and a graduate student studying civil engineering. “This technology could definitely be used in developing nations to purify drinking water in an easier and more environmentally friendly manner. But it could also be applied in something closer to home. Because the LED lights are so portable, it could be used to purify water from lakes or streams for people like hikers and campers. It could be used to purify tap water as well.”
UV light is one current method for killing pathogens including bacteria, viruses and protozoa in drinking water and wastewater. Pathogens that can be effectively treated withUV disinfection include Salmonella, Shigella, E. coli strains, Cryptosporidium and Giardia, norovirus and rotavirus. These pathogens cause intestinal infections that can result in abdominal pain, nausea, vomiting, dysentery or diarrhea – a leading cause of death in developing countries, where contaminated water is often the culprit and children under 5 are the most common victims, according to the World Health Organization.
Ultraviolet LED light holds a number of advantages for disinfecting water in developing countries, says Mark Elliott, assistant professor in the department of civil, construction and environmental engineering and an adviser for the team. “They are durable, unlike traditional bulbs, and they have the potential for lower cost and greater energy efficiency,” he says.
LEDs also operate at low heat and can be fine-tuned to different UV wavelengths, unlike current lamps that emit a limited range of UV light, says Lian Zhu, a graduate student studying environmental engineering who led efforts to create the proposal for the EPA’s P3 – People, Prosperity and the Planet – competition. Different wavelengths kill microbes by different mechanisms. For example, 250- to 280-nanometer wavelengths destroy DNA, whereas wavelengths below 240 nanometers destroy proteins. Conventional mercury lamps emit at 254 nanometers and rely on the DNA destruction mechanism, to which some pathogens are resistant.
Zhu and other students in Elliott’s Fall 2013 CE 521 Environmental Engineering Microbiology course wrote the proposal as their class project, using the concepts covered by the course. In CE 521, students learn to apply principles of environmental microbiology to the engineering of natural and manmade systems, including those for drinking-water and wastewater treatment.
Since Fall 2013, 24 students in CE 521 have worked to construct LED units to purify drinking water. Students have been involved in all aspects of the process, from writing proposals for project funding to leading research. In Fall 2014, 11 students enrolled in the class and prepared to present the project alongside those of other P3 teams at the National Sustainable Design Expo in Washington, D.C., in April 2015.
Other 2015 P3 projects included a device for use on exterior walls that generates electricity from sunlight, a method of extending the growing season for farmers by heating greenhouses with biomass and a way to reduce vehicle diesel emissions while lowering costs and improving fuel economy. Past P3 teams have used their ideas to form small businesses and nonprofit organizations.
“Each year, the projects and designs created by the P3 teams surpass expectations,” says Lek Kadeli, acting assistant administrator for EPA’s Office of Research and Development. “These students are creating sustainable solutions for our everyday needs and helping create a vibrant, growing economy.”
Elliott says a goal of his course and the P3 project is to better prepare engineering students for the important roles they plan to fill in society. “I hope they gain an improved understanding of the research process, from start to finish,” Elliott says, “including publishing findings and developing a viable product.” The project is still in progress, with publication and product-development aspects continuing.
For more information about CE 521 Environmental Engineering Microbiology, contact Mark Elliott at firstname.lastname@example.org or 205-348-5469.