No matter where you are in the world, Professor Karl Linden wants you to be able to turn on a tap and receive clean drinking water. It’s a basic, but vital, necessity that’s still missing from large swathes of the U.S. and low- and middle-income countries.
“People deserve reliable, trusted technology when it comes to something as essential as water,” said Linden, the Mortenson Endowed Professor in Sustainable Development at CU Boulder. “Water resources are getting scarcer and we need to be thinking about the next generation of efficient, affordable treatment options.”
The World Health Organization estimates that some 785 million people lack access to even basic drinking water filtration, leaving them vulnerable to pathogens such as cholera and dysentery. The problem is expected to grow in coming decades due to population growth and increased stress on water availability.
Treatment technology, meanwhile, hasn’t changed much in over a century. Sand- or carbon-based filtration and disinfectant chemicals are commonly employed in both municipal facilities and everyday life, from household Brita filters to chlorine tablets. Both methods have their limitations, however: Filtration is expensive to deliver to rural communities at scale and chemicals can add an unpleasant taste.
Linden, a member of the Department of Civil, Environmental and Architectural Engineering who has been researching water treatment for decades, is focused on a different solution: ultraviolet disinfection. UV rays can eliminate harmful pathogens like E. coli and Giardia on a scale of seconds compared to minutes, without harmful side effects. And while it’s not a new idea—large cities like New York already use UV in their utilities—it is one that has been historically difficult to bring down to the individual consumer level.
“UV has been around for decades, and is used in municipal and industrial water treatment around the world, but its potential for further innovation and application has been slowed due to the use of hazardous, bulky mercury vapor lamps,” Linden said. “But we’re interested in new UV sources with unique architectures that will allow us to advance this promising technology.”
In recent years, Linden and his colleagues have focused research on UV light emitting diodes, which are smaller (millimeters wide), nimbler and more durable. UV LEDs can be rigged in parallel, with multiple-emitting wavelength diodes to allow for a range of streamlined applications.
Another benefit: The UV LEDs are “instant-on” and don’t require any warm-up time before they start zapping contaminants, allowing users to save money by only running the devices when they need to. Water pulled from a well, for example, would be drinkable immediately after a quick UV treatment without the off-putting taste of chlorine.
Linden and his students recently completed a first-of-its-kind year-long study in Jamestown, Colorado, comparing UV LED disinfection to the town’s established chlorine treatment. They found that for a town of around 500 people without a large water plant, the UV technology provided equally effective disinfection capabilities without the added chemicals. The new technology only cost a few dollars a month in electricity and can run directly off solar power.
“Small-scale, rural systems are a natural place to start with this,” Linden said. “They have the majority of health violations because they typically don’t have engineers and dedicated water treatment staff. They might be relying on a system that’s not always operating correctly. So we feel this tech is a great solution because it can be operated remotely, autonomously and powered by solar to reduce energy draw.”
Earlier this year, Linden earned the Water Research Foundation’s Dr. Pankaj Parekh Research Innovation Award for his achievements in the advancement of water science.
Treatment that lasts
In the coming years, next steps could involve integrating UV LEDs directly into infrastructure. Linden envisions faucets with the diodes built right in to the taps, activating instantly when you turn on the water. His lab group has started looking at ways to build diodes into pipes to create a system-wide network of disinfectant points, mitigating biofilm growth in high-risk settings like hospitals.
“We really feel like this technology is sustainable and poised to revolutionize this field,” Linden said. “We want to work directly with more water managers to think about these improvements, try new things and ultimate bridge the research to the practical applications.”
Nationwide, momentum around the issue is building. This fall, the U.S. Department of Energy announced the creation of the $100 million Energy-Water Desalination Hub, an interdisciplinary partnership that will focus on early-stage research and development for energy-efficient and cost-competitive water treatment. The effort will be led by the National Alliance for Water Innovation, of which CU Boulder is a founding academic partner.
Linden, who will lead the CU Boulder efforts under the Hub, says that the prestigious award underscores a renewed interest in addressing water security, which has always been his calling.
“I feel like I’m on a mission to push society into the next generation of treatment approaches,” he said. “Some innovations have already taken hold and gotten traction. But we’ve had so many advances in society and technology like remote sensing, data analytics and real-time monitoring that we haven’t taken full advantage of yet for water security.”
Linden is also the principal investigator for CU Boulder’s Mortenson Center in Global Engineering on the 5-year, $15.3 million project Sustainable WASH Systems Learning Partnership, which focuses on maintaining the successful implementation of water systems by organizations like USAID over the long haul.
“In many low resourced countries we see a handpump or water system get put in and the treatment gets set up and it works for a while, but then eventually it breaks and the progress is lost,” Linden said. “So why is that, and what can be done about that? That’s when we need to think more holistically about the system that is available to support long term sustainable water services, and improved, integrated and innovative technology, like what we are working on in the Mortenson Center, is one aspect of the solution.”
The end goal? Bringing water solutions into everyday life seamlessly all around the globe.
“You turn on the tap and the water comes out and it’s already been treated and you don’t even have to think about it,” he said. “That’s the holy grail.”