This article originally appeared in the November 2020 issue of WQP as "Let There Be Light"
For more than a century, ultraviolet light has been used to disinfect water by physically disrupting the DNA of harmful microorganisms and destroying their ability to reproduce. Recently, however, the industry is seeing major advancements in the use of UV light for water disinfection. In particular, the emergence of powerful deep ultraviolet (UVC) light-emitting diodes (LEDs) as a viable source for disinfection is creating opportunities for new solutions in water applications. Promising advances in UVC LED technology expands the water technology industry’s ability to eliminate harmful viruses, bacteria, and fungi, including, but not limited to Pseudomonas, E. coli, and legionella. These innovations empower the industry to develop a wide variety of new solutions, creating a bright future for additional UVC LED applications.
Microbiological research in disinfection has transformed the ways in which reactors, or systems that expose flowing water to UV light, are used in the design of solutions across the globe. The design flexibility of UVC LEDs makes new applications possible in disinfection technology at a lower-cost and longer-lifetime. However, because UVC LEDs are a relatively new technology, it is critical for researchers to deeply understand the characteristics of UVC LEDs to best apply the technology for the biggest impact in water quality around the world.
The Importance of UVC LED Characterization
UVC LEDs provide a host of differences and many advantages over UVC lamp technologies. To best utilize these benefits, researchers must fully study the characteristics of these new light sources, including how the fundamental technology of UVC LEDs perform in disinfection, as well as how specific applications using the technology eradicate real pathogens under different conditions. In many cases, this process begins with repeatability studies and the testing of multiple reactors to understand the range of performance across various products. Effective characterization testing allows for specific products and solutions to be applied not only more effectively to new applications but also at the lowest total cost of ownership, adding critical value to a variety of products and use cases.
Through characterization of a product’s performance in disinfection, researchers are able to refine specific application performance against real pathogens. Microbiological characterization can measure how UVC LEDs of different wavelengths perform against several strains of harmful pathogens, including viruses, bacteria, and fungi, such as human adenovirus, E. coli, Pseudomonas, legionella, C. halotolerens, and S. chartarum. Of course, non-pathogenic standards such as Q-beta and MS2 can also be studied. Microbiological characterization is used to measure effectiveness of water disinfection in real-world systems and also in various specific applications, such as carbonated water appliances.
Likewise, extensive LED characterization builds a more thorough understanding of key design aspects, such as radiation pattern, thermal performance and lifetime. For example, lifetime tests of more than 15,000 UVC LEDs in the past three years have produced ample data sets that can be used by product designers to ensure the greatest effect when designing water disinfection reactors. LED characterization can then be combined with biological characterization to predict performance of water disinfection systems in different applications over time.
In practice, mathematical simulations using abundant LED lifetime data can be used to predict what fluence might be achieved after hundreds of hours of operation; calculated fluence can be used to project, based on biological characterization, disinfection performance in a particularreactor design. Overall, understanding the distribution of disinfection rates after several hundred hours of testing provides confidence in safe water quality long after usage requirements have expired, which becomes essential in ensuring protection against new or emerging pathogens of interest.
How Characterization Can Help in the Fight Against COVID-19
Most recently, the widespread outbreak of SARS-CoV-2, or COVID-19, has proven that while the race to find a vaccine and a cure for the virus continues at a rapid pace, we can use technologies like UVC LEDs to help fight the virus now. Cities across the world are now faced with new challenges related to water, air and surface disinfection and are searching for reliable and sustainable alternatives that LEDs can offer. The technology has already been implemented into systems that disinfect N95 masks and even indoor drones that disinfect spaces to ensure a safe level of cleanliness is regularly maintained.
We are fortunate to live in this modern era of technology with access to chemical and optical processes that can fight against COVID-19. UVC LEDs are able to inactivate the virus and can be used within products where mercury lamps or xenon flash lamps are impractical for disinfection. Both water and surface disinfection products that utilize UVC LED technology take advantage of several features that include a point light source that can be cycled an unlimited number of times without degrading lifetime, a smaller footprint and heat radiation away from the target of disinfection. Microbiological research of UVC LEDs has created the opportunity to explore additional ways in which the technology can be applied to aiding in the reopening of businesses and communities.
While businesses find new ways for UV light to disinfect high-touch surfaces and highly populated areas, water supplies must also be carefully monitored. The pandemic has exacerbated the need for clean water in many populations that do not normally have access to safe drinking water, such as those affected by lead contamination. Additionally, the return to work has created challenges for populations that normally do not consider water quality an issue. With people spending long periods of time away from offices and public buildings, many plumbing systems have been sitting stagnant for months on end. When water is left undisturbed, there is a higher chance of harboring pathogens like legionella and Pseudomonas, creating unsafe conditions for consumption and normal use in simple things like handwashing.
Beyond the sink, once-safe sources of water from drinking fountains, refrigerator water taps, and even coffee makers, are now potential health hazards. In order to protect water at the source, UVC LED technology can be applied to kill bacteria as the last line of defense at the point of use (POU). Extensive microbiological research has proven that UVC LEDs can eliminate concerns for water quality hazards, further proving that this technology can be a valuable tool in safely welcoming people back into offices or public buildings.
The Future of Disinfection Research
Both LED and microbiological characterization capabilities are important enablers in the use of UVC LED disinfection technology. As research continues to provide a comprehensive understanding of performance over time against different pathogens in real-life applications, the long-lasting disinfection challenges related to COVID-19 will further drive the need for industry innovation. The current global climate underscores the critical function of microbiological characterization, demanding more innovation and a faster response to threats in the future.
In addition, the reality of the pandemic has caused product manufacturers and consumers to quickly become more aware of the importance of sanitization and place a higher value on investing in the safe disinfection of water, surfaces and air. This realization will accelerate the research behind technology like UVC LEDs to more quickly incorporate proven effective solutions into consumer products and understand the effectiveness of different designs against current and future pathogens. As the need for disinfection evolves with the emergence or re-emergence of disease-causing pathogens due to climate change or pandemics, the need for microbiological characterization of disinfection performance will only become more important.
Microbiological research on UVC LED technology targets pathogens to find more reliable disinfection measures that can better prepare people across the world for sustainable solutions to unprecedented problems. The possibilities of tested, long-lasting disinfection will pave the way for more research that changes the ways technology can respond to and prevent the spread of harmful pathogens in 2020 and beyond.