UV-LEDs proven to kill coronaviruses, finds study

Ultraviolet light-emitting diode technology can kill coronaviruses and new applications could open up for water systems, a new study has found.

Investigating disinfection efficiency

Ultraviolet light-emitting diodes (UV-LEDs) can kill coronaviruses cheaply and efficiently and new applications could open up for water systems, a new study has found.

It is hoped the findings from a “world first” investigation could accelerate the use of UV-LED bulbs in air conditioning, robotic, vacuum and water systems to “efficiently disinfect large surfaces and spaces”.

Researchers from Tel Aviv University investigated the disinfection efficiency of a virus from the family of coronaviruses.

More than 99.9 per cent of the coronaviruses were destroyed using the technology in less than 30 seconds, according to the team.

Although a different variation of coronavirus was tested, it is expected to be identical in how it reacts to UV compared to the Sars-CoV-2 strain, currently responsible for the global pandemic.

The study was led by Prof. Hadas Mamane, head of the environmental engineering program at the School of Mechanical Engineering.

“The disinfection systems based on LED bulbs, however, can be installed in the ventilation system and air conditioner.”

She said that current methods of disinfection, such as chemical spraying, require physical manpower, as well as time needed for the chemical to act on the surface. “The disinfection systems based on LED bulbs, however, can be installed in the ventilation system and air conditioner, for example, and sterilize the air sucked in and then emitted into the room,” she said.

UV-LED in water

Historically UV-LED systems have been limited to low flow, or personal use water treatment products on the market.

In contrast, mercury lamp UV technology has been the go-to, dominant force for utility-scale treatment systems.

The adoption of UV-LED at scale has been impacted by technology cost and efficiency. Yet, in line with Haitz’s Law, named after scientist Roland Haitz (1935-2015), it’s predicted that LEDs will halve in cost and double in light output every two years.

A project being led by United Utilities in the UK is being seen as a milestone in the UV-LED journey to show it can operate at large scale for municipal applications.

Furthermore, at the end of 2019, an international standard on drinking water treatment was updated following developments and the roll-out of UV-LED technology.

Finding the optimal wavelength

In the Tel Aviv University study, the optimal wavelength for killing the coronavirus was tested using a disinfection system provided by US firm, AquiSense Technologies.

It was found that a length of 285 nanometers was almost as efficient in disinfecting the virus as a wavelength of 265 nanometers.

This result is significant, said the researchers, because the cost of 285 nm LED bulbs is “much lower” than that of 265 nm bulbs, and the former are also “more readily available”.

"Whenever there’s a national news article there’s always a reason why the non-water people are wrong."

“We killed the viruses using cheaper and more readily available LED bulbs.”

Commenting on the technology choice for the study, Prof. Mamane added: “But no less important, we killed the viruses using cheaper and more readily available LED bulbs, which consume little energy and do not contain mercury like regular bulbs.”

The study was conducted in collaboration with Prof. Yoram Gerchman of Oranim College, Dr. Michal Mandelboim, the director of the National Center for Influenza and Respiratory Viruses at Sheba Medical Center at Tel HaShomer, and Nehemya Friedman from Tel Hashomer.

The article was published in the Journal of Photochemistry and Photobiology B: Biology.