Water Conditioning & Purification Magazine

UVC LED Questions and Answers

By James Peterson

UVC LED disinfection is an increasingly popular solution over traditional methods of disinfection in a variety of industries, including healthcare, consumer appliances, food and beverage, and lab water. With UV light, disinfection is a physical process that employs ultraviolet radiation to inactivate microorganisms in water supplies, on surfaces and even in the air. UVC LEDs can be paired with filtration technology to provide a last-line of protection for water sources at the point of use. Because UVC LEDs with high power and the right UV wavelength provide longer device lifetime, there is an increased demand to learn more about their potential applications. The discussion below outlines more about the uses and benefits of UVC LEDs in disinfection today.

How do UVC LEDs actually work?
UVC LEDs are semiconductors similar to the LEDs that are now replacing the light bulbs in our homes. For ultraviolet disinfection applications, UVC LEDs in the 250- to 280-nm range are providing the same function as UV lamps, inactivating the DNA or RNA of microorganisms and making them unable to cause illness. DNA has a peak absorption of UV light at about 265 nm and, while UV lamps are effective at their wavelength of 253.7 nm, UVC LEDs manufactured to precisely match that 260- to 270-nm range are able to provide more disinfection with less UV energy for many microorganisms.

How do sanitizing and disinfecting differ in reference to systems with built-in UV treatment?
There are a number of water products coming out now with UVC LED sanitizing claims or UVC LED disinfection claims; these can mean drastically different things, depending on the system. Under Center for Disease Control and Prevention (CDC) definitions, sanitization is a process that will inactivate a portion of germs and disinfection for nearly 100 percent of germs. Some systems only use a low-power LED to sanitize a certain portion of a system (like a cooling tank), protecting that one area but not actually providing sufficient UV treatment to the water to significantly inactivate most microorganisms. Systems that provide effective UV treatment directly to flowing water will use higher-power UVC LEDs to inactivate microorganisms as they pass through a system, incorporating a properly designed UV chamber, to assure effective application of UV light. For system distributors assessing new systems, an easy way to identify this difference is reviewing laboratory reports at system flowrates or checking that the system is using at least 50mW of 250-nm to 280-nm UVC LED energy for every half gallon of flowrate. If a system cannot provide those assurances, it most likely is only sanitizing a portion of the system and not directly treating flowing water.

How can UV technology be used to treat particular viruses, bacteria and other pathogens in water, surface and airborne environments?
While UV is effective against all microorganisms, some organisms (such as spores) typically require higher doses of UV energy to inactivate. With UVC LEDs outside of the peak 260- to 270-nm range, even more UV energy is required. By selecting UV systems and vendors that use UVC LEDs in the peak-effectiveness range and have laboratory data against multiple organisms, distributors have the ability to provide direct assurance to their customers for treatment against particular organisms in which they have a priority concern.

Where in the treatment process should UV be placed?
UV treatment should always be the last treatment step in a system for two important reasons. The first is to provide the highest clarity of water for UV light transmission, as organics or other solids present in water can quickly reduce the effectiveness of UV treatment. The second is to assure that UV treatment acts as a barrier to inactivate the microorganisms that enter flowing water from fouling RO membranes and carbon filtration cartridges.

How does UVC LED technology stand out among other disinfection methods?
UVC LED technology provides a remarkable shift of the service lifetime and maintenance requirements of disinfection at the point of use, essentially becoming a durable component of water systems that can last for five to seven years. Alternatives like UV lamps, microbial filter cartridges or even chemical dosing pumps have never been able to offer users or service technicians such long windows of maintenance-free operation. POU end users typically benefit from this shift (in the long run) by securing UVC LED systems at no more than two times the initial capital cost of a conventional UV system, while achieving a three-to-four-times reduction of the total lifetime cost of the system due to reduced service and consumables costs. UVC LEDs also move water treatment into the realm of microelectronics, which allows devices to easily incorporate modern control features and power electronics with no thermal management requirements, using cost-effective and efficient components from the existing LED lighting and consumer electronics industries.

What are the unique disinfection needs in smaller commercial or residential systems?
The intermittent flow of residential and commercial applications frequently leads to an unpleasant experience with existing UV lamp systems. Users of UV lamp systems are familiar with the ‘hot shot’ of warmed water that comes out of the UV system when water has been idle in a hot UV lamp chamber with a lamp left on continuously. Automated bleed valve systems are available with temperature controllers to address this issue, but do increase the cost and complexity of the complete UV lamp system. Leaving the lamp on continuously also leads to annual replacement requirements, even if the system is only used rarely or seasonally. Some UVC LED systems are designed to directly eliminate those unpleasant aspects of ultraviolet solutions. By turning UVC LEDs on and off immediately, water heating is essentially eliminated and systems like these conserve their effective lifetime only for when dispensing is needed, eliminating the annual replacement need for POU systems. This ability to energize UVC LEDs when immediately needed also provides a drastic reduction in annual energy consumption for only POU, compared to UV lamp systems: greater than 80 percent in most cases.

What innovations should we expect to see emerge in the UV space over the next decade?
As power outputs continue to increase and costs continue to come down for highly effective 260- to 270-nm UVC LED devices, UVC LEDs will continue to replace current disinfection solutions used in water and also spread into new applications that previously found disinfection technologies too bulky or too costly to integrate. Flowrates of UVC LED systems are already increasing rapidly with portable, battery-powered UVC LED products that are giving consumers disinfection technology on-the-go. Appliances that previously did nothing to assure the hygiene of internal water are integrating UVC LEDs, all to provide users a promise of microbial hygiene, which is becoming paramount in our world today.

UVC LED technology can be implemented into the design of small and commercial water systems as a small-footprint, low-maintenance solution to ensure safe water quality. In light of the recent impacts of COVID-19 on public health, UVC light has been increasingly implemented across the globe. Depending on the application, UVC light, however, should always be used when the specific dosages and treatment times can be satisfied.

About the author
As Market Development Manager, Americas, James Peterson is responsible for the strategic direction of Crystal IS products focused on water markets. He develops business models for UVC emitters and ensures these product lines meet specific customer needs in water markets. Prior to Crystal IS, Peterson co-founded Vital Vio, a company that designs, engineers and manufactures LED lighting systems that reduce bacteria and other organisms from at-risk environmental surfaces.

About the company
Crystal IS, an Asahi Kasei company, is a manufacturer of high-performance UVC LEDs. The company’s products are suitable for monitoring, disinfection and sterilization in a variety of applications, including commercial and consumer POU water purification, as well as infection control in air and on surfaces in healthcare industries. For more information, visit cisuvc.com.

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