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Mercury-free UVC disinfection – Asahi Kasei demonstrates how Crystal IS UVC LED technology can be applied to achieve higher disinfection efficiency in water treatment than conventional mercury lamp systems

New York, Tokyo, and Düsseldorf, 5 October 2022 – Asahi Kasei, a diversified Japanese multinational company, and subsidiary Crystal IS have concluded in a bacterial performance test, an experimental Klaran™ WR water treatment reactor demonstrated over 75% higher performance than a traditional low pressure mercury lamp system using an equivalent power consumption level.

  • Klaran™ WR experimental water treatment reactor demonstrated over 75% higher performance than a traditional mercury lamp system in a bacterial performance test.
  • The Klaran™ WR reactor provides a lighter weight, smaller size, longer lasting and safer alternative to mercury lamps.
  • Asahi Kasei and Crystal IS advancements in UVC LED technology contribute to sustainability in society and are an important step towards actualizing a mercury-free world.

Klaran™ WR is an inline Point of Use (PoU) water treatment reactor (Fig. 1, left) which combines Crystal IS’ UVC LEDs based on aluminum nitride (AlN) substrates (Fig. 1, right), with Asahi Kasei’s R&D capability in the design and application of optics and fluid-dynamics.

Minamata Convention limits use of mercury

While conventional UV water treatment systems have used mercury lamps as a light source, nations around the world adopted stricter regulations after the Minamata Convention on Mercury became effective in 2017, due to the hazards that mercury poses to health and the environment. UVC LEDs have been developed as a mercury-free light source featuring small size, light weight, and flexibility in design. A key milestone speeding the transition to this modern light source is demonstrating that the disinfection performance, power efficiency and value of the new LED technology can fully meet or exceed the incumbent mercury lamp.

UVC LEDs as modern light sources

While it is widely understood and accepted that UVC LED’s instant on-off capability offers a significant advantage and better alignment with actual consumer use than an “always on” mercury lamp system, a question remained whether an equivalent powered LED system could demonstrate equivalent disinfection performance as a low-pressure mercury lamp system. The experimental Klaran™ WR reactor was developed to demonstrate that UVC LEDs can achieve just this.

Test with UVC LEDs versus mercury lamps

A standard Klaran™ WR was enhanced and modified to operate with the same power consumption level (6 W) as a comparable mercury lamp system (Fig. 2). Both systems were tested using water at a flow rate of 8 liters per minute (2.1 gallons per minute), with a UV transmittance of 97% at 265 nm and dosed with the addition of approximately 10⁶ CFU/mL of E. coli, a common gram-negative, facultative anaerobic, rod-shaped bacterium, for testing. As there is no established testing method for this type of comparison, Asahi Kasei devised the testing method and contracted an independent laboratory to perform the evaluation. Water quality samples recorded after 2 minutes steady operation with both systems were compared (Fig. 3), demonstrating how the Klaran™ WR had over 2 LRV (logarithmic reduction value) better performance than the mercury lamp system. Put another way, the Klaran™ WR system reduced E. Coli in the water to 1/100 of the level of the water disinfected by the mercury lamp system.

Table 1 The experimental Klaran™ water treatment reactor and the mercury lamp system

Product Power consumption Weight Dimensions
Experimental Klaran™ WR 6 W 125 g Ø51 mm × 115 mm
Conventional mercury lamp system 6 W 400 g Ø52 mm × 265 mm

It is Asahi Kasei’s belief that by replacing mercury lamps in water treatment systems with Crystal IS UVC LEDs, it will contribute to the realization of a mercury-free world and meet the global need for energy efficiency and safer water. In addition to water treatment system, Crystal IS will apply the various advantages of UVC LEDs to expand the application of UVC LEDs in surface and air disinfection.

About Crystal IS
Crystal IS, an Asahi Kasei company, and ISO 9001:2015 certified, is a pioneer in the development and commercialization of Aluminum Nitride substrates and UVC LEDS. Aluminum Nitride’s wide bandgap capability means that devices grown on Aluminum Nitride can more effectively (technically and economically) emit at the deeper ultraviolet (UVC) wavelengths than devices grown on sapphire. Crystal IS products are used to produce high performance UVC LEDs for environmental monitoring and disinfection in a variety of applications that enhance and sustain life and living around the world.

For more information, visit

About Asahi Kasei
The Asahi Kasei Group contributes to life and living for people around the world. Since its foundation in 1922 with ammonia and cellulose fiber businesses, Asahi Kasei has consistently grown through the proactive transformation of its business portfolio to meet the evolving needs of every age. With more than 46,000 employees around the world, the company contributes to a sustainable society by providing solutions to the world’s challenges through its three business sectors of Material, Homes, and Health Care. Its Materials sector, comprised of Environmental Solutions, Mobility & Industrial, and Life Innovation, includes a wide array of products from battery separators and biodegradable textiles to engineering plastics and sound solutions.

For more information, visit and Asahi Kasei is also dedicated to sustainability initiatives and is contributing to reaching a carbon neutral society by 2050. To learn more, visit

Company Contact North America:
Asahi Kasei America, Inc.
Jon Todd
39475 W. Thirteen Mile Road, Suite 201, Novi, MI 48377

Crystal IS, Inc.
Britt Hafner
70 Cohoes Avenue, Green Island, NY 12183

Company Contact Europe:
Asahi Kasei Europe GmbH
Sebastian Schmidt
Fringsstrasse 17, 40221 Düsseldorf
Tel: +49 (0) 211-3399-2058