Has the Moment Finally Arrived for LEDs in Municipal Water Treatment?

About the author:

Mitch Hansen is marketing manager for AquiSense Technologies. Dr. Rich Simons, Ph.D., is head of application science for AquiSense Technologies. Oliver Lawal is CEO for AquiSense Technologies, Dr. Jennifer Pagan, Ph.D., is chief technical officer and co-founder for Aquisense Technologies. They can be reached at [email protected] or 859.869.4700.

Mitch Hansen, PhD.; Rich Simons; Oliver Lawal, PhD.; Jennifer Pagan

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Ultraviolet light emitting diode (UV LED) technology has been growing consistently year-over-year with an estimated compound annual growth rate (CAGR) of 22% through 2027 (Allied Market Research). With installations in an ever-expanding list of new and existing water treatment applications, UV-C LED technology is making itself a firm technology creator and disruptor. The benefits of this technology provide some insight into its ability to create new applications for disinfection, while the advancement of system design and power efficiency allow this technology to grow in the already-existing commercial, industrial and municipal markets.

For those unfamiliar with the UV disinfection process, UV photons penetrate deep into microbial pathogens and damage their DNA, thus making it unable to replicate and therefore unable to infect a host. UV disinfection is a proven technology for chemical-free disinfection, has a decades-long track record, and has a variety of environmental and economic benefits.

Benefits of UV technology:

Chemical-free disinfection;
No disinfection by-products as can occur with chemical treatment;
Universal pathogen inactivation;
Potential for smaller footprint (due to shorter contact time);
No break-through risk as can occur with filtration technology; and
Potential for lower carbon footprint across lifecycle.

UV-C LEDs Creating New Applications

UV-C LEDs provide the same benefits as conventional UV disinfection with the added features of solid-state technology that visible LEDs are known for today. They provide benefits such as compact design, high power density, instant on/off, and unlimited cycling, which lead to UV-C LEDs being an obvious choice for point-of-use (POU) disinfection applications. Over the last several years, various POU devices with integrated UV-C LED technology have been commercialized. As the UV-C LED technology has improved, more and more applications developed, with point-of-entry (POE) LED systems coming to market in 2019. This in turn has led to the drive for still larger flow applications.

Additive benefits of UV-C LEDs:

Mercury-free construction;
Inherently more robust construction;
Instant on/off operation;
Unlimited power cycling;
Wavelength selectivity to enable more efficient inactivation mechanism; and
Flexible power options from low voltage DC to high voltage AC.

UV-C LED-based systems have been implemented into products and processes for the last several years. It is highly likely that water from a newer water dispenser, was water treated by UV-C LEDs. One case study to look at would be an integration by Mitsubishi Electric, who manufacture residential hot-water systems. The development team wanted to reduce the risk of pathogen growth in a recirculating hot-water system and turned to UV-C LED technology for the answer. Mitsubishi have deployed well over 100,000 UV-C LED systems Japanese consumer market of the past few years. The ever-growing list of applications adopting UV-C LEDs for smaller installations signifies a new normal in the water treatment market and indicates continual growth for the foreseeable future.

Municipal Applications Current State of UV-C LEDs

Whereas the commercialization of both POU and POE applications has been largely additive to the overall UV market, UV-C LEDs are starting to emerge as a disrupter into the more established market for municipal and industrial water treatment. There are currently three manufacturers who have demonstrated UV-C LED municipal disinfection systems: Metawater in Japan, Typhon in the U.K., and AquiSense Technologies in the U.S. Though only a handful of units have been installed to date, there are plans to install more municipal and industrial systems in 2022.

One such municipal drinking water treatment product is the PearlAqua Tera, with the first installation recently made in the U.S. south-west, to a utility well known for innovative solutions in water delivery.

Full commissioning and on-site validation will occur in Q1 2022, with more orders scheduled for delivery through the year in both North America and Asia. The PearlAqua Tera, designed and manufactured by AquiSense Technologies exploits the operational benefits specific to LEDs, including robust design, mercury free construction and low cost of ownership. By applying UV-C LED technology and a specialized design it provides chemical-free disinfection in a small, self-contained unit. The PearlAqua Tera system features automatic on/off switching in addition to advanced thermal and power management. The first PearlAqua Tera installation provides a disinfection barrier with flowrates up-to 2 million gallons per day (mgd) or 7,500 cubic meters per day.

The Tera system uses configurable LED lamp arrays based on target UV Dose needed or as flowrates vary. These arrays also provide online UV intensity monitoring. The Pearl Aqua Tera was designed as a product platform and not a one size fits all solution. Therefore, almost every aspect of the design from the flange diameter, LED count, and reactor length, to the LED drive power can be tuned to the specifics of the application, all while maintaining the core technical knowledge to drive the highly efficient design, peak disinfection performance and operational efficiency.

This first installation in the south-west specified a high degree of UV power control across a wide operational range; as such two independent UV-C LED lamp arrays were installed, each with addressable sub-arrays. Using advanced computational methods, every aspect of the reactor was assessed to provide a uniform fluence delivery to the drinking water passing through.

A series of integrated sensors across the lamp modules feed back real-time information on lamp performance and health, whilst a calibrated DVGW-compliant UV sensor provides information on the optical environment within the reactor. As is standard with systems of this size, these data and more are collected and interpreted by a local PLC, which has full access to control the UV-C LED arrays at any instant.

The utilities are keen to evaluate disinfection performance in comparison to an existing conventional mercury-lamp based UV system. They are also interested in long term operational performance and risk mitigation from failure events, such as lamp breakage.

Introduction of the PearlAqua Tera and other systems in the U.K. and Japan to the municipal drinking water treatment market may signal the fall of yet another ‘will never happen’ moment claimed by those who doubt the growth and potential of UV-C LED systems.

Future State of LEDs

With the first installation of a UV-C LED municipal drinking water system in North America behind us, the question remains, “is this a single application, or are there signs of the technology taking hold?” The answer is in the list of deliveries expected. In 2022 alone there are plans for six more installations in North America and two more in the Asia-Pacific region for municipal and industrial applications. The fact that there are almost 10 installations of a newly founded treatment technology in their first year is a testament to the market demand for mercury-free UV solutions.

One indicator that municipalities and companies are bullish on UV-C LEDs is the operating expenses and capital expenses compared to other UV technologies. LED based systems have the potential to have lower operational costs than mercury-based systems based on an EPRI funded study involving contributions from the US EPA, Black and Veatch and Washington University (EPRI). Given the advantages of UV-C LED technology and the potential cost benefits, it is no wonder why some are so interested in getting started with this technology.

Given the benefits of UV disinfection technology and the additive benefits LEDs provide, it provides a clear picture of what this market has in store for the future. The past several years have offered UV-C LED technology a launching point into new POU and POE applications where conventional UV systems were not found. The market is currently at a tipping point where UV-C LED disinfection technology has become competitive with conventional mercury-based technologies.