UV-C LED

​Light-emitting diodes (LEDs) are semiconductor devices composed of multiple layers of substrate materials. They can be designed to accept a wavelength input and emit UV-C photons to stop bacterial replication.

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UV-C LEDs perform the same functions as conventional mercury-vapour lamps but offer many advantages.

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Environmentally friendly – conventional UV lamps contain heavy metals that are difficult to handle and costly to dispose of safely.  

Small design footprint – LEDs are much more compact than their mercury-vapour counterparts, making them easier to integrate into innovative designs.  

 

Instant-on/off – UV-C LEDs turn on instantly, so there is no warm-up time, unlike mercury-vapour lamps. 

 

Unlimited cycling – on/off cycles do not affect the life of the LEDs, meaning there is no limit to lamp cycling.  

 

Temperature-independent – LEDs can emit photons from a different surface than their heat. They can be designed so that, when UV-C LEDs are used for water purification, they do not transfer heat into the water.

 

Wavelength selection – One of the greatest benefits of UV-C LEDs is that users can configure them to select a specific wavelength that maximizes absorption by the chosen microorganism.

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How Does UV-C LED Disinfection Work?

Different types of UV-C disinfection can work depending on the scale of the solution being implemented. However, the principles of how UV-C disinfection works remain the same.  An LED emits a preselected wavelength with a small amount of electricity. The LED then emits UV-C photons that penetrate the water and damage nucleic acids in the microorganism's DNA.  As these cells cannot replicate, the harmful microorganism becomes inactive. As a result, UV-C LEDs deliver high-intensity radiation that kills bacteria in seconds, and their effectiveness is measured in LOGs.

 

UV LED Disinfection Technology

​Ultraviolet disinfection technology has been the star performer in water and air treatment over the past two decades, due in part to its ability to provide treatment without the use of harmful chemicals.  UV refers to wavelengths that lie between visible light and X-rays on the electromagnetic spectrum. The UV range can be further divided into UV-A, UV-B, UV-C, and Vacuum-UV. The UV-C portion represents wavelengths from 200 nm to 280 nm, the wavelength used in our LED disinfection products.  UV-C photons penetrate cells and damage the nucleic acid, rendering them incapable of reproduction or microbiologically inactive. This process occurs in nature; the sun emits UV rays that perform this way.

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UV Disinfection Process

​At AquiSense Technologies, they use Light Emitting Diodes to generate high levels of UV-C photons.  The rays are directed at viruses, bacteria, and other pathogens in water and air, or on surfaces, to render them harmless in seconds.

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Applications of UV-C LEDs

​There are many applications where UV-C LEDs are being tested to see whether they can become a solution not just to current disinfection challenges but to our future ones, too.  Drinking water disinfection, purification, and treatment are areas where the technology is gaining traction, as it is chemical-free, poses no risk of creating harmful by-products, effectively inactivates pathogens, and requires very low maintenance.  In addition to water, UV-C LEDs provide disinfection for both air and surfaces. UV-C LED air purifiers for HVAC (heating, ventilation, and air conditioning) are increasingly used in the commercial landscape.

There are numerous applications, from residential to commercial, healthcare, transport, life sciences, defence, and emergency response, where UV-C LEDs are finding new uses:  Market Segment Example Applications UV-C LED system benefits: Top 3 important attributes valued by the segment

ResidentialPOE, Appliances, Faucets. Ultra-compact footprint, Plug and play (e.g. easy to retrofit), Low power draw

Commercial: food and beverage service, Water dispensers and fountains. Ultra-compact footprint, Low power draw, No water heating.  HealthcareHAI control, Dialysis, DentalMercury-free, Chemical-free, Durable (e.g. vibration resistance)

Transportation, RV and boating, Automotive, Aviation, Space, Chemical-free, Durable, Lightweight Life Sciences,
Bio-pharma, Ultrapure water, Point-of-use distribution, Mercury-free, Chemical-free.  Defence/Emergency Response: Personal hydration, Remote treatment, Ultra-compact footprint, Lightweight, Durable (e.g. vibration resistance)

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UV LED Benefits

In much the same way that LEDs have revolutionized the display and lighting industries, UV-C LED technology is poised to deliver new, improved, and expanded solutions for both air and water treatment. Dual barrier, post-filtration protection is now available where mercury-based systems could not previously have been conceivably used.

Attribute: Conventional Mercury Lamp, UV-C LED, Product Implication

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Mercury Content: 5- 200 mg. None. Safe disposal – no special handling

 

Lifetime: 5,000 – 15,000 hours.  10,000 hours - Flexible operation

 

On/Off Cycles: Max. 4 per day

 

Unlimited, intermittent-flow friendly

 

Warm-up Time: Up to 15 minutes, Instantaneous, Extended replacement intervals

 

Operating Surface Temp.100-600 °C Same as process water. Zero-flow friendly does not promote fouling

 

Architecture, Cylindrical tube, Point source, Versatile implementation

 

Durability: Fragile glass tube, Rugged semiconductor, Versatile operation

WavelengthPolychromatic (200-300nm) Monochromatic (254 nm)Selectable (250-300nm)No wasted energy & targeted performance

 

Power Supply 110-240V AC, 6- 30V DC Battery/Solar option

 

LEDs emit light at a specific wavelength using a small amount of electricity. Depending on the LED's composition, it can produce infrared, visible, and now UV-C wavelengths.  The side view of the LED shows that as power passes through the LED layers, it activates the desired wavelength.  The LED is then packaged to allow for electrical connection, thermal management, and physical protection. This helps maintain efficiency for the LED output and lamp life.  These LEDs can then be integrated into various systems to treat water, air, and surfaces. These systems also work with the LED packaging to disperse heat and improve the efficiency of the disinfection process.

 

Types of UV-C LED Disinfection Systems

​UV-C LED technology is now being used in water-dispensing and water-cooling applications and requires expertise, experience, and significant engineering knowledge to integrate.  To date, three types of disinfection system concepts have been developed for integrating UV-C LED systems. 

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UV LED Inlet Installation

For pre-existing water systems, the disinfection process is often left outside the device, creating an opening for bacteria to grow at any point in the system. In the inlet model, the UV-C LED is easy to replace and will last considerably longer than its mercury-vapour counterpart.  While there is no need to redesign existing systems, the trade-off of having an inlet system is that the components are visible and are therefore more susceptible to damage.

 

In Process Disinfection

In this configuration, UV-C LEDs are integrated into the current system. This setup has several benefits: the UV-C LED component is protected, contamination between the unit and the dispenser is significantly reduced, and the model takes advantage of the LEDs' compact nature.  The one major drawback of the in-process disinfection model is its susceptibility to retrograde contamination and bacterial growth upstream in the pipeline.

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Point of Consumption Disinfection

​This system offers the greatest protection by leveraging the full capabilities of UV-C LED technology. Installed at the point of consumption, the system features an instant on/off switch.  ​Point-of-Consumption disinfectant systems offer the greatest benefits, but due to the complexity and expense of the new system, they are the most difficult to design and install.  They can become contaminated by an external source, where bacteria can grow through the pipe into the system. This can be prevented by the regular cycling of the system.

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Disinfection of Drinking Water

​One area where UV-C LEDs are proving to be successful is in the disinfection of drinking water.  UV-C LEDs are being used to disinfect drinking water at various points in the treatment cycle, from source to consumption. It can take a few seconds for the water to become clean in a UV-C model, and the new technology allows LEDs to be placed at different points to ensure decontamination.

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It works initially when a water reservoir is exposed to multiple high-powered LEDs that disinfect the water. They emit powerful UV-C photons in the range of 200 – 280nm that pass through the water, preventing bacteria in the water from reproducing.  ​Many newer systems have taken advantage of LEDs' compact size to disinfect at the end stage of the drinking water journey, ensuring complete disinfection.

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What is LOG reduction?

​LOG reduction measures how thoroughly a decontamination process reduces contamination.  For example, a 1-log reduction means the number of bacteria is 10 times smaller; a 2-log reduction means it is 100 times smaller; a 3-log reduction means it is 1,000 times smaller; and so on.  To put this into perspective, if a surface had 100,000 microbes, it would take a 5-log reduction to bring the number down to just 1.

 

Water Treatment and Pathogen Control

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A recent paper published in Science of the Total Environment examined various microbial disinfection methods for UV-LED water treatment systems. It found that UV-C LEDs were more effective at inactivating pathogens and reducing energy consumption than UV-LEDs across a wider wavelength range.

As UV-C LEDs can select various wavelengths to target specific microorganisms in infected water and deactivate them, different pathogens and bacteria stop replicating when exposed to specific wavelengths.

 

UV LED Benefits: Mercury-free

​Although UV disinfection is generally considered safer than chemical disinfection, all conventional UV lamps typically use between 5 and 200 mg of mercury per lamp.  These UV lamps require routine replacement and are susceptible to breakage during transportation, handling, and operation. UV LEDs are mercury-free and provide a safer alternative. This has created new markets for UV disinfection, where traditional mercury-based UV lamps have been banned for safety reasons (e.g., in medical devices and space).

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Conventional UV lamps hold their mercury either in liquid form (more common in medium-pressure lamps) or as an amalgam (more common in low-pressure, high-output lamps). Amalgam UV lamps contain solid “spots” which consist of an alloy of mercury and another element, such as indium or gallium. Liquid mercury lamps can be hazardous both during operation and when off. While the lamp is operating, the mercury vaporizes; if the lamp is broken, mercury vapour is easily dissolved into the treated product. Accidents and improper procedures increase the risk of exposure to people and the local environment.

 

UV-C LEDs do contain small amounts of elements such as the metals gallium and magnesium, and the metalloids silicon and boron (although boron is not predominantly used). These metals and or metalloids are bound within a stable crystal structure and cannot leach into the environment. The inherently stable crystal structure of an LED ensures that UV-C LEDs are highly robust against mechanical or environmental shock.

 

UNEP Minamata Convention

​The Minamata Convention on Mercury was initiated by the United Nations Environmental Programme (UNEP) to protect human health and the environment from anthropogenic emissions and releases of mercury. UNEP has set the goal of phasing mercury out of production by 2020.

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Although the Minamata Convention does not specifically prohibit the manufacture and sale of UV mercury-vapour lamps, it will generally promote the more widespread adoption of alternative technologies. Potential responses may include the following actions:  Corporations that use UV systems in products or manufacturing processes (e.g., white goods, beverages, microelectronics, life sciences) may implement best practices by selecting an LED option under the influence of the Minamata Convention, rather than through enforcement.  Original Equipment Manufacturers that currently employ conventional mercury lamps may face a conflict with mercury-based products in their own environmental policies and, under Minamata regulations, may begin transitioning to develop new products using mercury-free light sources.

Municipalities may also follow suit by adopting UV-C LEDs, though they are more likely to take longer to do so.

 

There will always be a percentage of people who will look for “eco-friendly” product options. As the Minamata Convention raises awareness of mercury's effects, it inherently affects the use of mercury-based lamps without banning the sale or manufacture of these lamps.

Regulators will likely have a slow transition from mercury to UV-C LED lamps. Regulators will always look for viable alternatives to mercury, as it is their mandate to steer technology toward the most holistic solution.