By Mitch Hansen and Hunter Lear

This article reviews ultraviolet (UV) disinfection technology for water treatment and the two main types of lamps (conventional mercury and light emitting diodes [LEDs]). The process UV light disinfects will be reviewed and the science behind it will be briefly explained. The article will discuss the benefits of UV LEDs for water treatment and will focus on the point-of-entry applications specifically with one UV LED point-of-entry system in particular.

Focusing on the Spectrum
UV-C disinfection technology has been a growing tool for water, air, and surface (typically in hospitals such as tables or other high-touch surfaces) treatment for decades. Driven by increased need for infection control and a sensitivity for over-reliance on chemical use, the UV-C disinfection market is in a good position for steady growth. This technology is a shining star in the disinfection world as it provides consistent and reliable disinfection without the common issues seen with traditional chemical disinfection, such as by-product formation and species-specific resistance.

One of the exciting topics that has been a discussion point in recent years, is the maturity and implementation of UV-C LEDs for disinfection. This new technology functions the same way conventional UV-C lamps in terms of disinfection, but with a variety of different operational features. The excitement around this new technology can be seen in the estimated compound annual growth rate (CAGR) of 20% for UV-C LEDs, verses 5.5% for the overall UV market.

What are UV-C LEDs? How do they differ from conventional UV mercury-vapor lamps? And are there any case studies of this new technology? Before we answer those questions, we need to review UV disinfection in general.

The Basics of UV
UV light is a type of radiation that can be found in the electro­magnetic spectrum and is measured in nanometers (nm). Invisible to the human eye, UV is an effective disinfectant due to their unique ability inactivate a cell’s DNA.

There are four ranges to UV light: UV-A, UV-B, UV-C, and Vacuum-UV.

  • UV-A: Otherwise known as black light, it has the longest wavelength, ranging between 315nm to 400nm.
  • UV-B: Known as the medium wavelength, it ranges between 280nm and 315nm.
  • UV-C: The shortest wavelength, it ranges between 200nm and 280nm.

UV-C is germicidal, meaning it can be used effectively as a dis­infectant to inactivate microorganisms, such as bacteria and viruses. When the DNA of microorganisms absorbs UV light, it stops them from being able to reproduce, thereby preventing their ability to harm a human host. With UV, nothing is added to the water, meaning after the disinfection process, it has no negative effect to the environment.

Currently UV lamps used in point-of-entry (POE) applications tend to use mercury vapor lamps to produce UV-C light. These UV systems can range from a few gallons per minute (GPM) to several tens of GPM. These systems tend to have a large footprint and require annual maintenance. The cost of operation for conventional systems comes from the annual lamp replacement, system cleaning, and continuous power consumption.

Limitations of conventional UV technology include:

  • Use of mercury and fragile quartz tubes.
  • Limited on/off cycles.
  • Low power density and large footprint.
  • Reaches 100-600° C when in operation.
  • Limitations on wavelengths.

A Bright Future with UV-C LEDs
Over the years, advancements have been made in UV LEDs and their implementation into water treatment systems to the point where they have become viable for POE water treatment applications. UV-C LEDs open many capabilities in regard to system engineering when compared to their mercury counterparts.

For the residential or industrial user, a noticeable benefit would be the savings in electricity. In a recent installation of a specific UV-C LED system for POE applications, the user reported up to 88% energy savings when compared to the mercury lamp that they had used previously. These savings not only result in cost savings for the user, but there is also the added environmental benefit. The energy savings can be contributed to another benefit of UV-C LEDs, which is their ability to be cycled on and off an unlimited number of times. There is also no warmup time for UV-C LEDs, meaning that water treatment begins with the startup of the LEDs.

Improvements with UV LED technology include:

  • Mercury-free devices.
  • Instant on/off and unlimited cycling.
  • Robust and durable designs.
  • High power density and compact size.
  • Lightweight and reduced number of parts.
  • No heat transfer (meaning no to limited fouling and scaling).

Another important advantage of UV-C LED systems is longer lamp life. The UV-C LED installation mentioned above has a 5-year lifetime before lamp replacement. This is based on average household usage. With the ability to turn off the LEDs when not in use, lifetime is driven entirely by usage hours, and therefore can be extended if usage is low. The tested UV-C LED disinfection system provides additional energy and lifetime savings with the unique feature of dynamic power control, which provides optimum performance across all flowrates. When a lower flowrate is detected, the system adapts and lowers power consumption. This feature is made possible with advanced design and LED technology.

There is also a potential for space savings with UV-C LED systems. With UV-C LEDs having just a fraction of the foot­print of a mercury lamp, they can be incorporated into smaller devices. This reduction in footprint is made possible by the LED technology offering a UV power output density several factors higher than conventional UV lamps, allowing for more compact lamp designs and system design. For POE applications, this means a smaller device that can be easily plumbed into an existing water purification system. UV-C LED systems also do not require a ballast, therefore further saving space.

Solutions with UV-C LED Systems
Smaller POE devices could allow UV water treatment to be installed in residential and commercial settings where it has not been possible in the past. UV-C LED POE systems, because of their small footprint and lower electrical consumption, can also be installed in developing nations to aid in their water treatment.

With increasingly more homes being built in wildland-urban interface areas in places like the American West, the need for in-home water treatment is increasing. Many homeowners are taking advantage of the advancements in UV-C LED treatment technology. The above-mentioned UV-C LED disinfection system, rated for up to 12 GPM, is easily plumbed in line with recommended prefiltration due to its small footprint and simple installation. The integrated flow switch allows for instant UV-C activation upon flow detection and unlimited on/off cycling at no degradation to lamp lifetime. After installation and power supply, each lamp module can provide up to 5,000 hours of water treatment, or about 5 years for most home users.

The tested UV-C LED disinfection system also features LED indicator lights that provide power, flow, and error messages to users. This is paired with smart features and internal monitoring to ensure the unit functions as expected. These features include power regulation, temperature management, temperature monitoring, and intensity monitoring.

Case Studies
While UV-C LED water treatment systems are still new to some applications, several thousands have been installed worldwide. Below are two relevant case studies that showcase the POE application of this technology. Several of these units have been installed and operating for several years now.

Kreis Haus
A UV-C LED POE system has been implemented in the Kreis Haus located in Feldbach, Switzerland. The intent of the home is to provide a real-world experience in a home that is entirely built from the circular economy. The home includes the latest innovations in construction and sustainability. The home is open to the public for tours, consultations, and most importantly, overnight stays to experience all the innovations.

The house collects rainwater from the roof and processes it into drinking water using a combination of filters and the specified UV-C LED POE system. This kind of rainwater processing can be implemented into other homes that lack access to treated water.

Learn more at https://www.zhaw.ch/en/lsfm/institutes-centres/iunr/ecotechnologies-and-energy-systems/ecotechnology/wastewater/kreis-haus/.

Ironmark Tiny Homes
UV-C LED systems have also made an appearance in fully equipped tiny homes from the Ironmark Group, located in Australia. The mission of Ironmark is to provide eco-friendly and sustainable living with affordable options for their customers. This off-grid unit makes clever use of space, fitting many rooms into the compact footprint. The specified UV-C LED water disinfection system ensures all water entering each tiny home is clean and safe to use. Ironmark has installed roughly 50 POE units in their homes and 700 point-of-use (POU) units for integration into tiny homes and other Ironmark applications.

Learn more at https://www.ironmarktinyhomes.com.au/.

Conclusion
The technology behind the UV-C disinfection industry is constantly evolving, and UV-C LED treatment is no exception. For years, it was stated that UV-C LEDs would take decades to reach the capabilities of conventional UV-C lamps—that is no longer the case. The rapid improvements of UV-C LEDs have allowed this newer and more efficient technology to match and outperform traditional treatment technologies in many ways. Not only that, but the potential of this emerging applied science is larger than ever, with many new participants entering the UV-C LED realm.

Whether the motivation is more sustainable living, resource independence, or simply peace-of-mind, UV-C LEDs provide a range of unique features that provide POE applications with clean and reliable water. LED technology is here and can provide customers the protection they need.

Reference
https://mordorintelligence.com/industry-reports/uv-led-market

About the authors
Mitch Hansen is the Marketing Manager for AquiSense with 6 years of experience in the UV LED market. He holds a master’s degree in communication to aid in the promotion of UV LED technology to ex­isting markets.

Hunter Lear is a Senior Global Application Engineer for AquiSense. She holds a degree in environmental engineering and has experience in the hydrology and sustainability fields.

About the company
AquiSense is laser-focused on UV-C LED disinfection innovation. We work with leading manufacturers to evaluate, then integrate, the best available UV-C LED sources into products that solve real world problems in water, air, and surface applications. We work collaboratively with commercial partners across multiple industries, deploying our expertise and patented designs. Whether the need is for instant mercury-free disinfection of water, pathogen reduction in air flows, or high accuracy sensing, we have solutions available.

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