This article originally appeared in Water Quality Products magazine 2020 issue as "Bright Future"
Ultraviolet (UV) disinfection technology is a growing topic in the water treatment field. With new applications, certifications and design concepts, UV technology is constantly evolving. For decades, UV disinfection has been done with a conventional mercury vapor lamp, so most research and certifications were set up around this lamp type. UV light emitting diodes (UV LEDs) are drastically different from mercury vapor lamps and therefore enable new disinfection applications. The benefits of UV LEDs include:
- Mercury-free. This allows for disinfection in markets with material restrictions;
- Compact footprint. This enables it to integrate into existing products or systems;
- Instant on/off. This creates flexible operation;
- Unlimited cycling. This allows for intermittent use;
- Temperature independent. This results in no effect on treated water;
- Wavelength selection. The systems are able to select wavelength based on target pathogen; and
- Long replacement intervals. LED life is only effected when systems are active.
Traditional UV technology has limited certain applications. The larger footprint, limited cycling and on/off times require for a narrow list of possible installations. With UV LEDs, this list grows exponentially, opening new design possibilities, which push research and development to extend the limits of the technology. The sections below will review the integration aspect of UV LED disinfection systems and how the location of this technology can provide an added value proposition for the integrating product or system.
Ultraviolet LEDs are gaining traction in water dispensing and water-cooling applications to provide enhanced user safety. While UV LED technology has several benefits, exploiting these attributes takes expertise, experience and engineering know-how. Teams who have studied UV LED devices, designed UV LEDs systems and understand UV disinfection offer added insight for advanced disinfection solutions. There are a few installation concepts to keep in mind when integrating UV LED systems.
This method leaves the disinfection outside the device or process, leaving an opening for bacteria growth at any point in the system. The UV LED system is easier to replace, but with lamp lifetimes of up to 10,000 hours, the need to replace is less frequent when compared to conventional mercury lamps. For example, 5,000 hours ‘on’ time at 2 LPM equals 600,000 liters of water served to clients. Inlet disinfection can also make installations easier as there is no need for a system redesign or remodeling of the original product. However, installing the UV LED system at the inlet can make a more cumbersome system as components are now exposed and more likely to be damaged or disconnected.
In Process Disinfection
Integrating a UV LED system offers added benefits. Besides the UV component being protected, the amount of contamination possible between the point of dispense and the disinfection system has been greatly reduced. This takes advantage of UV LED systems that are compact and designed for instant on/off automation. One drawback is this type of installation does not prevent retrograde contamination or bacteria growing up the pipeline from the point of use.
Point of Consumption Disinfection
Point of consumption applications offer the most protection for contamination in a product or system. By placing a UV LED system at the point of consumption, manufacturers take advantage of last mile protection and defense against external contaminants. This type of UV disinfection system cannot exist without the compact size and instantaneous on/off benefits of UV LEDs. While this design allows the most benefits to the product or system it is integrated into, it is also the most challenging to design and only a few applications currently exist that offer true UV LED point of consumption disinfection. Retrograde contamination happens when bacteria from external sources contaminates the system, growing up the pipeline into the system. Intermittent UV cycling offers disinfection at the outlet, preventing growth.
While it is important to review the possibilities of UV LED technology, it is also important to review what is being implemented in the market right now. One manufacturer, OASIS International, noted harmful bacteria in drinking water has become a rising concern. Water-borne bacteria, such as Pseudomonas aeruginosa (biofilm), Cryptosporidium (Crypto) and E. coli can multiply in plumbing systems, becoming a public health hazard. According to the U.S. Centers for Disease Control (CDC), for the past two decades, Crypto has been recognized as one of the most common causes of waterborne disease from recreational water and drinking water in humans in the U.S.
AquiSense Technologies designed a UV LED system for point of consumption disinfection for OASIS International. The system provides OASIS bottle fillers with instantaneous disinfection with a pathogen inactivation rating of 99.99%. The system offers smart operation with 15-minute “UV on-intervals” to keep the dispense point disinfected.
Another application for point-of-use UV LED disinfection comes from SUEZ Water Technologies and Solutions. The company required disinfection at the point of dispense for their lab water products. Due to the precision needed in laboratory equipment, SUEZ noted the importance of providing disinfected water from their products. UV LED technology solved their problem by allowing disinfection right at the point of dispense. SUEZ chose to integrate UV LED technology into their lab water purifying products due to benefits, including compact footprint, instant on, low power use and the UV LED system outlet functional as a dispense head.
While UV LED technology is still new to the disinfection industry, NSF International has already taken the necessary steps to provide certification possibilities. For years, the NSF Standard 55 has been exclusively for low pressure mercury vapor lamps However, in September 2019, NSF published a new NSF Standard 55 that allowed for UV LED systems to be certified. The specific requirement for 254 nm was broadened to a range from 240 to 300 nm. NSF also established a target microorganism reduction level as an alternative to a UV-dose value, in order to simplify the newly adapted certification and added two new UVT modifier chemicals to permit for more consistent UV Transmittance, meaning percentage of light that passes through the water, across the UV-C spectrum, creating a stable and reliable testing method.
UV LED technology has a bright future in the disinfection market. The growing possibilities for clean water from UV LED technology provides added protection for more and more water dispensing products. Each application requires a unique level of disinfection. Depending on the internal space available, the need for replacement and the level of disinfection, each system could require any of these integration options. UV LED systems provide flexible disinfection options for any need.