Co-Authors: Normand Brais

The recent coronavirus pandemic has made it clear that airborne pathogens can spread rapidly and widely via indoor environments. Indoor environments are highly vulnerable to airborne contamination and reducing indoor disease transmission by immunizing buildings on a large scale should reduce epidemic spread and have an effect similar to that of vaccinating the population to produce herd immunity. This study examines how effective such an approach might be. Air disinfection systems comprised of filtration and ultraviolet germicidal irradiation (UVGI) are evaluated in conjunction with building air exchange rates for a variety of building types and operating conditions using the NIST CONTAM program. Viruses are modeled as being released from infected individuals who move throughout the buildings and who move from building to building. The Wells-Riley infection transmission model is adapted to predict new infections and epidemic spread. A model city consisting of two million people and a concomitant array of buildings – commercial office buildings, schools, shops, malls, residences, apartments, stadiums, etc. – is used as a basis to examine the epidemiological spread of SARS matched to existing data. The results are then compared with increasing levels of building immunization, and increasing percentages of immunized buildings, to examine the effects of retrofitted UVGI + filtration systems in each type of building. Overall results of increasing levels of building immunization are also compared with predicted levels of increasing immunization of the population with vaccines.

Co-Authors: Richard Vincent, Jeroen ter Stege, Marc de Samber, Rob van Asselt, Adrie de Vries, David Woodward

We report on a multifactorial comparison of upper room UVC 254nm and full room far-UVC 222nm irradiation of airborne pathogens. The applied UVC wavelength determines both the GUV efficiency and feasibility of use in certain occupied indoor spaces. At a molecular level, the UVC interaction with pathogens, such as SARS-CoV-2, can lead to different inactivation mechanisms depending on the wavelength. This is due to the optical absorption characteristics of the constituent pathogen (macro) molecules, such as RNA/DNA nucleotides and (spike) proteins. Further, the aerosol particle is of importance as the aerosol size not only changes over time but also can contain various concentrations of macromolecules which further influence the absorption characteristics. This may result in different susceptibility factors for 254nm and 222nm. On a system level, the maximum achievable UVC fluence rate will determine the pathogen inactivation rate and consequently the equivalent Air Change per Hour (eqACH) and Clean Air Delivery Rate (CADR). We will show that the essential trade-off between maximum achievable fluence rate and safety threshold limit values (TLVs) is fundamentally different between an indirect upper room vs a direct full room irradiation concept. This will be illustrated by some typical application examples using CFD simulations to validate the overall GUV efficiency, including physical parameters like room dimensions and ceiling height, as well as different airflow patterns. Finally, total cost of ownership, including energy consumption, the GUV system cost, installation and maintenance cost is driving the acceptance of GUV in a wide range of applications ranging from medical, to educational and public buildings. The multifactorial comparison will demonstrate that durable air cleaning is possible with wise energy use without sacrificing health benefits.

Co-Authors: Andrea Rocchetti, Nicola Andreini, Guglielmo Vaccaro, Giulia Santi, Paolo Bucaioni, Adriano Milazzo, Lorenzo Talluri

A mechanical ventilation system (MVS) that supplies sanitized air is an effective way to ensure high air quality for indoor environments. In this work, an accurate methodology for the design of a UV sanitation section of an air handling unit (AHU) is proposed. The objective is to define the characteristics and number of UV-C lamps that, given a section and a length of AHU, let to obtain a certain sanitation target (defined by IUVA protocols for a specific pathogen). First is necessary to model the irradiation field of the lamps, evaluating the direct radiation and the diffuse reflective one from channel walls. Radiative heat transfer theory for view factors between the points of the mesh (that represents the particles of the pathogens), lamps and walls is used. This approach is similar to the one proposed by W.J.Kowalski. The software Matlab has been employed for calculations. Known the irradiance for each point, the received UV dose is evaluated by multiplying the total irradiance for the residence time in a cell of the mesh. To exactly calculate the residence time, a computational fluid dynamics analysis made with the open-source software Open Foam has been conducted. The same evaluation lets to define the airflow pressure loss due to the presence of the lamps. The developed code represents therefore a valid tool to adequately design, through the optimization of irradiance distribution and the minimization of pressure loss, a UV sanitation section both for new MVSs or for the old ones revamping.

Co-Authors: Aaron Leber, Jennifer Pagan, Mitch Hansen

Ultraviolet (UV) disinfection has increasingly been used in place of chemical treatment methods in municipal water and wastewater treatment over the past 40 years. Nearly all municipal UV systems utilize either medium or low-pressure mercury lamp technology. More advanced control systems, sensors and power monitoring have increased their reliability; however, physical limits in lamp efficiency, lifetime and risk of lamp-breakage are key limiting factors to current UV systems.

Light Emitting Diodes (LEDs) that emit in the UV range are a relatively new evolution in solid-state LED technology development. The potential to use UV-LEDs in the treatment of water has long promised all the benefits of UV disinfection – absence of chemicals, ease of use, pathogen specific targeting. However, historically their use has been limited to low flow systems as a consequence of high cost, low operating efficiency and engineering development needs. There are estimated to be close to 500,000 operating small-scale UV-C LED systems globally. As these systems have evolved over the past years, there is an increasing sophistication with the product design elements to handle criteria such as; photon distribution, flow efficiency, and thermal management. In addition the system manufacturing methods have evolved to manage semi-automated product assembly. These developments, together with increasing improvements in UV-LED efficiency have enabled larger water treatment products to be engineered. There have been two documented larger scale municipal sized UV-LED water treatment system pilot installations over the past few years and this paper builds on the enabling criteria for those systems. This paper then adds details of a new municipal installation completed in 2022, the first of its type in North America. The PearlAqua Tera system is installed at Las Vegas Valley Water District. This system seeks to resolve some of the limitations of traditional UV systems; fragile glass lamps, on/off switching limitations, warm-up time restrictions, frustrating maintenance, sand separators (for mercury lamp breakage protection), and bulky wiping systems – offering immediate and long-term cost savings throughout installation and operation. At 2 MGD, this system is operating on a well head and disinfection performance data will be shared. The paper will follow how the progression of LED performance and price known as Haitz’s Law (similar to Moore’s Law in computing) - as the efficiency of UV-C LEDs goes up, the price per lumen comes down. The engineering challenges to scale from 1 gpm to the installed rate of 2 MGD is significant, but shown to be achievable. It will also outline how the operating conditions and water matrix parameters differ with LED technology by outlining design conditions of a further 6 installations planned for 2022. Ultimately many in the UV industry consider UV-LED technology to be viable only when municipal scale systems are installed. This paper will show that this time is upon us – size does indeed matter.

Co-Authors: Mahyar Mohaghegh Montazeri, Fariborz Taghipour

UV-LEDs are replacing conventional UV lamps in the water disinfection applications as they have several advantages such as being mercury free, having a small footprint and instant on/off ability. However, limited studies were done on the UV-LED water disinfection systems in real extreme conditions. We have designed and fabricated a high-flow UV-LED water disinfection reactor and performed a field study of the system by connecting it to the secondary effluent of a municipal wastewater treatment plant (Annacis island, Delta, BC), operating 24/7 with 20 LPM flow rate of extreme quality water. As expected, the low UV transmittance (55-64%) and high turbidity (4-10 NTU) considerably affected the performance of the system. Also, biofouling and chemical fouling was observed over the reactor walls and the protective windows. However, the regions exposed to the higher UV Dose (higher fluence rate, slower flow velocity) were found to be less prone to the biofouling formation. Chemical deposition was observed over the protective window and the extent of deposition was found to be correlated with the UV fluence rate profile. This showed the effect of UVC in promoting the formation of scaling over the protective windows when water contains high levels of calcium and iron. After 22 days of field testing, the UV transmittance of protective windows dropped by around 60%, and the radiant power of the UV-LEDs dropped by 40% (in accordance with their lifespan) which resulted in 67% drop in the reduction equivalent dose of the reactor. This study showed the need for periodic maintenance of UV-LED water disinfection systems, by replacing UV-LEDs and cleaning (or replacing) protective windows when exposed to low water quality conditions.

Co-Authors: Alister Renton, Matt Simpson

All the promises placed in UV LEDs for the disinfection of water have been proven in recent years at point of use scale with a number of reputable companies leading the way in this space. However, there is still some scepticism in the capacity of UV LEDs to compete with conventional mercury lamps at municipal scale due to the relatively low wall plug efficiency and high cost of LEDs in comparison to mercury vapor lamps. In this presentation, we are showing an energy comparison between a low-pressure mercury vapor lamp system and a UV LED alternative for the disinfection of drinking water. The water treatment works studied was a small borehole in the North of England. The UV systems were designed for a maximum flow capacity of 2.7 MLD (0.7 MGD), a minimum UVT of 95% and a UV dose of 40 mJ/cm2. The UV LED reactor was validated in 2020 under the UVDGM guidelines. Whilst the mercury system showed better energy performances when comparing the design parameters (criteria often used for decision making purposes), the dynamic nature of water treatment works (the fact that flow and UVT are often far from worst-case design conditions) and the capacity to vary the output power of UV LEDs instantly showed that using existing UV LEDs (technology available in 2022), UV LED systems could compete from the first day of installation with the mercury alternative during continuous operation.

Co-Authors: Susan Andrews, Ron Hofmann

In full advanced treatment (FAT) for water reuse (i.e., reverse osmosis (RO) and advanced oxidation process (AOP)), chloramines are often added before RO to prevent its fouling. More than 50% of these chloramines may pass through the RO and then react with free chlorine that is applied for downstream UV-chlorine AOP. The chlorination of a mono/dichloramine mixture causes the chlorine/chloramine species to evolve in a timescale in the order of dozens of seconds, such that the exact speciation when the water enters the UV reactor can be very different depending on the timing, and the subsequent UV-chlor(am)ine efficiency may vary. Although kinetic models for breakpoint chlorination exist, they generally lack validation for timescales involving the first tens of seconds of the reaction, and at pH 5–6 which is relevant to RO permeate. In this study, published models were reconstructed and verified against experimental results reported in the literature to compare their performances. Currently, breakpoint chlorination experiments are being conducted under water reuse relevant conditions to further validate the reported kinetic models. The concentrations of free chlorine, monochloramine, and dichloramine are closely monitored spectroscopically at the beginning of the reaction, and second order rate constants are optimized based on experimental results. The outcome of this work will be an assessment of the accuracy of existing models and a validated model to simulate the chlorine/chloramine speciation, especially for the timescales and low pH conditions of RO permeate that are relevant to water reuse treatment.

Co-Authors: Dave MacNevin

UV Advanced Oxidation Processes (UVAOPs) using peroxide or chlorine play a critical role in potable reuse projects, reducing the concentration of many low molecular weight chemical compounds that may pass through reverse osmosis treatment. Key issues for the regulation of direct potable reuse include the handling of spikes of organic chemicals (California) and chemicals that may be difficult to remove or act as precursors to disinfection byproduct formation (Florida). This presentation combines the results of several potable reuse feasibility studies, supplemented with pilot test data to provide an expansive risk framework, sifting through hundreds of chemical compounds, to identify potential vulnerabilities in UVAOP treatment, shortlisting the few chemicals most likely to penetrate a UVAOP treatment process. These lists of unregulated compounds were evaluated in this screening process

• URCIS/SDWIS/FED (Rounds 1 and 2)
• UCMR 1/2/3/4/5)
• NPDES ‘Organic Toxic Pollutant’ )
• USEPA Drinking Water Standards (Regulated) and Unregulated Chemicals with Health Advisories)
• Compounds Identified in Howe et al 2019

Co-Authors: Dave MacNevin

Since 2004, 100 acres of wetlands at the Green Cay Nature Center in Palm Beach County, FL have purified over 11 billion gallons of nutrient-rich water sourced from the nearby Southern Region Water Reclamation Facility (SRWRF), before replenishing the local water table. In late 2020, the Palm Beach County Water Utilities Department initiated Green Cay Phase 2, a visionary project crafting a constructed ‘springs -type’ ecosystem reminiscent of Florida’s world-famous natural springs. This project will extend the legacy of the original Green Cay project, transforming dozens of acres of historic farmland into a new nature park. The difference in this project will be a 2 million gallon per day (mgd) advanced water purification facility (AWPF), with a state-of-the-art learning center, feeding the spring with crystal-clear water that is safe for kayaking and fishing. This project is on track to be one of the first advanced reuse facilities permitted under Florida’s updated water reuse rules. The advanced water purification process train includes ultrafiltration, reverse osmosis (RO), breakpoint chlorination for ammonia oxidation, UV advanced oxidation, and water stabilization. This presentation will provide an overview of the project with a focus on results from advanced oxidation in the AWPF pilot study.

Key areas of discussion in the presentation will include the following:

• Best practices when using breakpoint chlorination for ammonia oxidation prior to UVAOx, to minimize interference with UVAOx process and control DBPs. )
• Comparison of UV peroxide, UV chlorine, and UV chloramine operations)
• Results of 1,4-dioxane UVAOx challenge testing)
• Results of mutagenicity and toxicity testing on finished water after UVAOx)

Co-Authors: LADWP

Many Los Angeles Department of Water and Power (LADWP) groundwater production wells in the San Fernando Basin are impacted by contamination caused by various commercial and industrial activities. Without comprehensive containment and groundwater basin remediation, the City will significantly lose the ability to use this valuable local resource within the next decade. To restore the groundwater basin and ensure the supply of high quality renewable water resources for the City, LADWP is undertaking a program to evaluate and implement groundwater remediation throughout the SFB. This 10 year program of up to $600M will greatly improve local renewable water supplies for the City. Construction and testing for the first wellfield, North Hollywood West, is well underway and illustrates the complexity of trying to test the various components that make up the treatment train. Challenges have included water re-route/mitigation due to long lead times for pumping equipment, GAC offline operations, and UV AOP equipment testing with chemicals. This presentation will cover the challenges and the lessons learned on the testing phases for the facility to be successfully transitioning into commissioning.

Co-Authors: IUVA Task Force Members-Impact of UV-C on Material Degradation

The UV-C disinfection equipment market is projected to have a greater than 10% CAGR over the next five years. Growth factors for the industry include heightened awareness related to the global pandemic and application expansion due to technological advancements in UV-C sources. Increased use of UV-C based disinfection in nascent applications within air and surface disinfection has raised the probability of UV-C exposure on materials not traditionally used in UV applications. Of particular concern is the impact on polymeric materials which are used ubiquitously in building, transportation, medical, and pharmaceutical environments. Historical knowledge of UV exposure effects on polymers have naturally focused on the terrestrial solar spectrum which excludes wavelengths in the UV-C regime. As global interest and use of UV-C increases, the investigation of the impact UV-C exposure has on polymer materials is increasingly important. The IUVA, as a non-profit supporter of UV technologies, has several active task forces to examine topics of importance to the field of UV. This presentation will exhibit the latest update from the IUVA task force examining the impact of UV-C on material degradation. Starting in March of 2021, this task force has examined the effects seen on various polymers exposed to three different UV sources, 222nm filtered KrCl excimer, low pressure Hg, and UV-C LED. Several analytical methods were used to compare control and UV-C exposed polymer samples. These methods include stress/strain, color and gloss, optical microscopy, reflectivity, haze, transmission, and flame retardancy. Duplicate test sites were used for the analysis. Round one of testing was conducted on unformulated polymers and completed in November of 2021. Round two of testing was conducted using commercial grade polymers; this testing will conclude by June of 2022.

Co-Authors: Akhil Bhasin, Tanat Maichan, Luis Gomez, Gerardo Olivares

The outbreak of a novel coronavirus (COVID-19) in December 2019 had resulted in a pandemic bringing many operations across the globe to a halt. To reduce the virus transmissions during air travel, the aviation industry determined to implement additional cleaning and disinfectant procedures along with the existing standard practices. However, the frequent and extensive use of the disinfectant products established a need to understand the long-term effects of disinfectant procedures on the aircraft interiors. This study explores the impact of long-term exposure of UltraViolet-C (UV-C) irradiation on various aircraft cabin interior materials. In this research program, three ultraviolet-c irradiations with peak emissions at 253.4 nm, 222 nm, and 280 nm were evaluated. The virus inactivation dosage was determined based on literature review as 40 mJ/cm2 at 253.4 nm, 3 mJ/cm2 at 222 nm, and 37.5 mJ/cm2 at 280 nm configurations. With single ultraviolet-c treatment dose as the baseline, cumulative dosages were calculated to represent one year, four years, and eight years worth of UV-C exposure assuming one treatment per day. Six different types of unreinforced thermoplastics and one fiberglass composite material were exposed to long-term ultraviolet-c irradiation. Post the exposure, the specimens were evaluated for changes.

Co-Authors: Oliver Lawal, Anne-Marie Dixon

Cleanroom surfaces are being degraded by chemical disinfection. This is a serious problem throughout the industry. Additionally, SporKlenz and similar sporicidal agents are creating a major HVAC concern - air handlers are corroded, ductwork seals are breaking down creating leaks - all resulting in the loss of air changes and pressurization. Constant removal of the residual from the disinfectants is also creating a humidity issue and risk for mold in the rooms and behind the wall systems. Additionally, safety issues arise from slips and falls on the wet floor surfaces and electrical issues can occur from chemical liquid drips into wall receptacles. The ability to use an alternate method for microbial elimination will reduce these risks. Ultraviolet (UV) disinfection has been widely used in place of chemical treatment methods in municipal water and wastewater treatment over the past 40 years. UV has also seen an increased use as both a replacement and a companion disinfection tool in surface disinfection for medical and residential applications. There are a number of fundamental advantages that will be outlined and also some challenges also when used in a GMP environment. The challenges are not least of which related to the core FDA regulation known as USP 1072. Light Emitting Diodes (LEDs) that emit in the UV range offer some interesting potential to overcome some of the operational challenges. This potential will be explored in the context of the unique requirements of GMP environments. Ultimately the implementation of UV technology within a GMP environment will need to be progressed carefully, methodically and with full scientific rigor in order for the basis for acceptance by FDA. This paper will outline some concepts for a path to support this new science and reduction, or potential elimination of, chemical disinfectants in a GMP environment. These concepts include characterization of UV Dose response of the target organisms outlined in USP1072.

Co-Authors:

In our daily lives, we encounter multiple surfaces that have been previously touched by someone else. High-touch surfaces are found everywhere. We have self-checkout at the grocery store. We have options to order our meals on a touch-screen prior to getting in line. There is the pin pad on the point-of-sale device at 1000’s of retail outlets. When traveling we are encouraged to “check-in” at a kiosk prior to engaging a live person. All these surfaces have recently been touched by someone else and are not routinely cleaned and if they have been there is a high likelihood that the instructions on the liquid cleaning products they are using were not followed. In 2019 and 2020 a comparison of UVC disinfection versus enhanced liquid disinfection practices on these high-touch surfaces was done. The settings included a sports stadium, 5 airports and 6 retail / pharmacy locations in 8 USA states, Canada and Australia. The results will be presented along with a discussion on the many challenges of implementing a UVC solution, on a high-touch surface, in a public space.

Co-Authors: Christos Christodoulatos, Andrew Mai, Benjamin Smolinski and Xiaoguang Meng

Nitroglycerin (NG) is an organic nitrate ester manufactured for use in double-base gun and rocket propellants; as such, wastewater streams from industrial base facilities (i.e. energetic-laden wastewater) often carry NG concentrations which can be enhanced due to solvent residuals. Although advanced oxidation processes (AOPs) have been widely studied and successfully applied to the treatment of persistent organic pollutants and explosive compounds (e.g. nitrotoluenes, nitramines and nitrophenols) NG degradation by AOPs in energetic laden-wastewater has yet to be explored. In the present study, NG-contaminated wastewater streams as well as NG synthetic solutions were treated using UV-assisted persulfate (PS), hydrogen peroxide (H2O2) and photo-fenton techniques. The selected AOPs were investigated by comparing the degradation efficiency for NG on a bench scale under different parametric conditions (i.e. pH, oxidant dosage). Results from degradation of NG in mixed solutions with other NG-deriving compounds such as dinitroglycerin (DNGs) and mononitrogliceryn (MNGs) will be also presented. The degradation kinetics of NG under different treatment conditions following identification and quantification of the carbon/nitrogen by-products will be discussed. Overall, the experimental results obtained from application of selected processes showed that UV/PS was the most effective technique in achieving degradation of NG both in both synthetic solution and wastewater.

Co-Authors: Mahsa Masjoudi, Madjid Mohseni

Vacuum-UV (VUV) irradiation at 185 nm of water is a potential advanced oxidation process (AOP) for in-situ generation of hydroxyl radicals (OH•) through direct photolysis of water molecules. In the context of water treatment for potable reuse purposes, VUV AOP is proposed as a promising alternative treatment downstream of the reverse osmosis process. Under such conditions, chloramines – used as an antifouling agent for the membrane surfaces – are usually present in the AOP feed water and could possibly get involved in the VUV photoreactions. In addition, free chlorine can be added into the AOP reactor as a commonly used chemical oxidant to promote generation of reactive radical species. In this study, treatment of 1,4-dioxane – a micropollutant of concern in potable reuse trains – has been investigated in the VUV and VUV/chlorine processes with chloramine present in the water matrix. Both free chlorine and chloramine species were shown to possess high absorption coefficients in the VUV range and result in significant attenuation of 185 nm photons. At the same time, thanks to their high quantum yield, they contribute to generation of radical species through direct photolysis reactions, with the resulting impact significantly higher removal of 1,4-dioxane with VUV-based AOPs compared to that offered by UV-AOP treatment. A kinetic model was also developed to better understand the mechanisms of the involved reactions and predict concentration profiles for different radical species under experimental conditions. Overall, introducing the 185 nm irradiation component shows great potentials for enhancing the treatment efficiency of micropollutants, such as 1,4-dioxane, in potable reuse trains. However, further studies need to be carried out for optimizing the design of VUV reactors and addressing the limitations of photon penetration into the contaminated waters to better exploit this technology.

Co-Authors: Jean-Claude Bonzongo

Poly and Per-fluorinated Alkyl Substances (PFAS) are widespread in the environment, and their adverse effects have stimulated research on possible ways to prevent and control environmental pollution. Of great interest is the need for complete degradation of these substances from contaminated environmental matrices. For aqueous effluents, wastewater treatment plants (WWTPs) tend to behave as major vectors of PFAS to water resources, because WWTPs are not designed to efficiently degrade and remove these pollutants. Several treatment techniques have been proposed so far for removal of PFAS from contaminated waters using novel degradative technologies requiring extreme conditions or high costs. An advanced oxidation process (AOP) of UV irradiation technology has shown promising results. In this technique, a wavelength of 185 nm has universally improved degradation while sulfate radicals in acidic conditions and hydrated electrons in basic conditions have shown high oxidizing power. Under 185 nm UV irradiation, PFOA has been found to completely degrade using a mixture of Ga2O3/PMS within 1 hour while a TiO2/PMS mixture also completely degraded PFOA after 8 hours. PFOS can almost be completely degraded 98% by UV irradiating sulfite producing hydrated electrons in basic conditions. Preparing these technologies to also degrade the emerging GenX and shorter chain compounds is necessary. The aim of these technologies is to be both efficient and effective at degrading PFAS lowering the possible treated concentration so any upcoming regulations can be feasible while it is also simple enough to be retrofitted into previous plants to ensure safe discharges in the future.

Co-Authors: None

The far UV-C light technology has drawn significant interest thanks to its competitive efficacy in both photobiological safety and inactivation of airborne pathogens, mainly in indoor spaces. Microplasma flat lamp and its far UV-C lighting fixtures have been developed based on the confinement of a weakly-ionized, atmospheric pressure, low-temperature plasma in a microscale cavity technology. The technology has been found not only to be ideal for far UV-C radiation at 222 nm (the formation of KrCl* excimer) but also in the potential of utilization flexibility. To date, the lamp provides a compact, flat form factor (having a lamp thickness of less than a few millimeters) that significantly improves the utilization efficiency of photons in a variety of applications (and its performance evolves for the new applications). At a controlled UV fluence according to the TLVs specified by ACGIH, the microplasma lamps demonstrated anti-microbial advantages over conventional germicidal techniques in several germicidal tests and actual applications. The scientist and engineers at Eden Park along with several commercial partners has demonstrated fixtures that is suitable for many novel applications. As a result of the efforts, at least a dozen different products have been introduced in the last two years (during the pandemic), mainly for the prevention of SARS-CoV-2 transmission. Furthermore, some future application has been proposed (developed) for its uses in the post-pandemic era. The progress of the current applications as well as the preparation for future applications of the post-pandemic will be introduced in this presentation.

Co-Authors: None

Excitation of luminescent material by electrons is a well understood technology with a low-cost and scalable approach to generating photons. Deep Light Photonics. Inc has developed a proprietary formulation of phosphors that produces polychromatic emission in the UV-C regime with four peak wavelengths at 232nm, 242nm, 261nm and 272nm without the use toxic materials.

The eUV® device operates in high-current pulse mode with a 100us pulse width and a repetition rate of up to 1.25kHz across a 20 cm^2 emission area. Optical output greater than 400mW has been measured. Lamps can also be combined into arrays for even greater area coverage and optical power. Biological testing from 10 cm in a 60 second exposure has demonstrated a 4.1 log reduction of e-coli and a 2.4 log reduction of MRSA.

With polychromatic emission there are multiple ways to inactivate pathogens effecting their DNA, RNA or protein structure with different UV-C wavelengths. Every microorganism has a different vulnerability to wavelengths in the UV-C spectrum – the pathogen’s particular action spectrum.

tTe device can be used for UV curing, food processing, cannabis growing facilities and surface cleaning. Air flow applications include odor control, sterilization and food preservation. There are many potential applications for water, including pools and spas, aquaculture, life sciences, wastewater, drinking water and water reclamation. All without the risk of leaking toxic materials into the environment; clean and green.

Co-Authors: Matthew Stevenson

NS Nanotech’s solid-state disinfection products emit far-UVC light to continuously deactivate airborne coronavirus and numerous other air- and surface pathogens. With a spectrum wavelength range from 200-to-230 nanometers, far-UVC light is safer to use around people for disinfection than traditional UVC light at 254nm and longer wavelengths. At the IUVA conference Industrial Showcase, we will demonstrate our ShortWaveLight™ Emitter, the world's first solid-state source of far-UVC light for manufacturers of disinfection systems, and the ShortWaveLight™ Purifier, a personal portable desktop far-UVC purifier for consumers

With its patented solid-state nitride semiconductor design, the ShortWaveLight™ Emitter runs cool, has a small form factor, and benefits from cost advantages of standard solid-state manufacturing processes. Designed for manufacturers developing far-UVC applications in a broad variety of vertical markets, it is uniquely differentiated from non-solid-state far-UVC excimer lamps based on older gas-plasma technologies that run at higher temperatures and have larger form factors than our emitters. Our presentation will feature far-UVC disinfection applications being developed for transportation, hospitality, education, and other vertical markets by manufacturing partners who joined our Evaluation Program prior to first shipments in the second half of 2022.

We will also demonstrate our own consumer product, the portable desktop ShortWaveLight™ Purifier. Shaped like a pyramid and about the size of a coffee mug, it is available for pre-order on our ShortWaveLight.com Shopify e-commerce site for consumers who want to constantly disinfect their personal airspace and workspace.

Co-Authors:

Many UV-based disinfection solutions are not sustainable in that they can't be used in the presence of the occupants due to the health concern on UV irradiation over dosage. This presentation will review four award-winning disinfection products that showcases the best use of visible light or UV or both for sustainable air or surface disinfection in order to highlight that the key benefits to users lies not on the technologies themselves but the best application engineering.

The first product is a UV-free Air-sanitizing Desktop Lamp using air-permeable lampshade coated with a high-density photocatalyst material that can be effectively activated by visible white LED light source for providing a sustainable air-disinfection without harm for any personal indoor space.

The second product is a self-cleaning anti-microbial film doped with a high-density photocatalyst material that can be effectively activated by any indoor lighting (i.e., without using any UV light source). When this film is applied to any surfaces, it provides 30-day effective surface disinfection, even for the high-touch surfaces, resulting a huge labor savings and a sustainable surface disinfection protection, without relying on any UV light source.

The third product is an air-sanitizing ceiling-mount troffer fixture with its air-filter coated with a high-density photocatalyst material that is hyper-activated by UVA LED in the hidden air tunnel for providing sustainable, low-maintenance air disinfection protection.

The fourth product is an overbed lighting fixture for patient rooms and it comes with an UVC T5 lamp for supporting germicidal lighting operation mode, and safe-guarded by trifold safety mechanisms for prevention UVC exposure: motion senor, siren alarm, and flashing warning light. So the germicidal lighting can be operated safely even with a UVC light source for air and surface disinfection. The air-disinfection and the surface disinfection won't be performed continuously, but routinely, suitable for a patient room applications.

Third party test data for these four products will be presented to show their antimicrobial effectiveness.

Co-Authors: Dr. Richard Robinson, Yijing Liu, Najmus Mahfooz, Oscar Rosas-Mejia

There is a continuing need for evidence-based engineering controls to reduce transmission of SARS-CoV-2 and other pathogens as the world prepares for better response to pandemics after COVID-19. Although ultraviolet (UV) light is known to inactivate coronaviruses, conventional UV lamps contain toxic mercury and emit wavelengths (254 nm) that are more hazardous to humans than krypton chlorine excimer lamps emitting 222 nm (UV222). Culture and molecular assays were used to quantitate dose response for disinfection and molecular damage of SARS-CoV-2 solution exposed to UV222. Culture assays (plaque infectivity to vero host) demonstrated more than 99.99% disinfection of SARS-CoV-2 after a UV222 dose of 8 mJ/cm2 (pseudo-first order rate constant = 0.64 cm2/mJ). Immediately after UV222 treatment, RT-qPCR assays targeting the nucleocapsid (N) gene demonstrated ~10% contribution of N gene damage to disinfection kinetics, and an ELISA assay targeting the N protein demonstrated no contribution of N protein damage to disinfection kinetics. Molecular results suggest other molecular damage contributed more to disinfection. After 3 days incubation with host cells, RT-qPCR and ELISA kinetics of UV222 treated SARS-CoV-2 were similar to culture kinetics and with improved ability to detect infectious virus, suggesting validity of using molecular assays to measure UV disinfection without plaque assays. These data provide quantitative disinfection kinetics which can inform implementation of UV222 for preventing transmission of COVID-19.

Co-Authors: Haiying Cui

Like all coronaviruses, SARS-CoV-2 is extremely sensitive to inactivation by exposure to UVC radiation. Given the history of Ultraviolet Germicidal Irradiation (UVGI) systems and their demonstrated effectiveness for reducing transmission of other airborne pathogens, there is strong evidence to indicate that UVGI systems will be effective for reducing the risk of transmission of SARS-CoV-2. A set of interconnected numerical models was developed to examine this issue in quantitative terms. Basic principles of material balance were applied to develop models to predict the dynamic behavior of airborne SARS-CoV-2 in indoor settings with common UVGI configurations, including traditional Upper-Room UVGI, systems based on contained UV sources (i.e., air cleaners), and “Whole-Room” configurations that have been applied for Far UVC sources. These models were used to develop estimates of the time-dependent and steady-state concentrations of infective SARS-CoV-2 in a wide range of indoor settings. The results of these model predictions were used as input to a Quantitative Microbial Risk Assessment (QMRA) to provide estimates of the risk of disease transmission for each of these scenarios in the presence and absence of the UVGI device. The results of these calculations provide a quantitative link between the operating characteristics of a UVGI system and the corresponding reduction of disease transmission. More broadly, these tools provide a framework for simulation of the effects of UVGI systems on the risk of transmission of other airborne pathogens. Moreover, this framework can be easily modified to accommodate other, or additional treatment technologies.

Co-Authors: Ramin Farnood; Benoit Barbeau

The COVID-19 virus is dangerous to work with. Furthermore, expelled droplets are small, on the order of 0.6-2.4 microns in diameter (Yang et al. 2007). Because experimental work in this area is so challenging, computer modelling can be a useful tool to improve our understanding of surface disinfection. The Monte Carlo Simulation used here is based experiments with B. subtilis spores and bacteriophage in dried saliva exposed UV light. A two-population UV disinfection model is used, where one population represents the disinfection of individual organisms, and the other represents organism protected in aggregates. The faction of organisms in aggregates ranges from 2-15%, based on the experimental results. The rate constant for aggregates is smaller than that of induvial organisms, ranging 5-15% of its value. The MCS model was executed 10,000 times to account for the variability in these model parameters. The overall rate constant used was that of the COVID-19 virus. Based on the MCS results, we predict that one-log reduction of the COVID-19 virus in dried saliva droplets can be achieved at a UV fluence of just 8 mJ/cm2. At this fluence, the probability of achieving a two-log reduction is 15%. The fluence must be increased five-fold to 40 mJ/cm2 to ensure a two-log reduction. At this higher fluence, the probability of three-log reduction is 51%. Overall, after a relatively easy first log reduction, there is evidence of tailing in the UV dose-response of organisms contained in dried saliva droplets.

Co-Authors: Dr. Natalie Hull

The presence of antibiotic resistant bacteria (ARB) and the horizontal gene transfer (HGT) of antibiotic resistant genes (ARG) in water environments pose a threat to human health. Ultraviolet (UV) irradiation is an advantageous disinfection method because it produces fewer potentially toxic disinfection byproducts than oxidative technologies, and it damages nucleic acids which can inhibit HGT of ARG. This work compares the treatment efficiency of different UV wavelengths (222 nm and 254 nm) for inactivating multidrug antibiotic resistant B. subtilis strain 1A189, damaging intracellular and extracellular ARG, and inhibiting HGT of intracellular and extracellular ARG using non-resistant strain 1A1 as the recipient. Disinfection efficiency increased with UV dose for both wavelengths, but the 222 nm wavelength was more effective than 254 (k = 0.0318 cm2/mJ and 0.0298 cm2/mJ respectively). ARG damage quantified by polymerase chain reaction (qPCR) increased with UV dose for both UV wavelengths. Although extracellular ARG damage was similar between wavelengths, intracellular ARG damage was greater by 222 nm than 254 nm. Intracellular and extracellular ARG damage increased with increasing amplicon length for both wavelengths. For HGT of extracellular ARG, log10 reduction of HGT increased with UV dose, and the inhibition effect was stronger by 222 nm (k = 0.0139 cm2/mJ at 222 nm and k = 0.0091 cm2/mJ at 254 nm). Overall, these comparisons demonstrate the superior mechanistic efficacy of 222 nm over 254 nm UV for disinfecting ARB and for damaging and inhibiting transfer of ARG.

Co-Authors: Shigeharu Yamauchi

UV Technology has been around for many, many years. Of course, the majority of this is via traditional technologies like mercury lamps or xenon lamps. While UV LEDs have been commercialized for over 20 years, with UVC LEDs the past 5 years, unfortunately the technology has been very niche to date, with education on the technology being far too limited or stretched for marketing purposes. With that said, UV LEDs for disinfection is still happening now, for water, air, surface, and more. Without the proper education though, confusion and failures will occur, unnecessarily jeopardizing the inevitable technology adoption. While visible LEDs have now become the de-facto in our everyday lives (i.e. general lighting, automotive, backlighting, etc.), there are many lessons learned over the past 20 years of their adoption that must be addressed and considered as UV LED adoption rates grow. With the ramped-up efforts towards the Minamata Convention and ban on mercury devices, now is the time to invest in education, understanding of the pros / cons and ultimately launching of GUV LED systems. Nichia plans to give an educational “LED 101 session” addressing the history of UV LEDs, the construction methodologies, the terminology, the reliability and breakdown mechanisms, the performance roadmaps and several examples of how UV LEDs, specifically UVC LEDs should and should not be implemented today in germicidal applications.

Co-Authors: Sun Young Moon, Young-Jin Kim

Since the outbreak of the COVID-19 pandemic, people have concerned about public health and personal hygiene more and more. LG Electronics Inc. has expanded application of UV-C LEDs to enhance the sanitary function of the home appliances accordingly. Especially the UVnano, which is LG’s UVGI technology, was adopted to the whole residential and commercial air conditioners for the production of clean and comfortable air. In this study, we optimized the irradiation system of UV-C LEDs for the effective disinfection of the surfaces inside the air conditioners, and verified their performance. We identified the reduction of the test bacteria depending on the exposed UV dose when the types of bacteria, surface materials, irradiance, incident angles are varied, and obtained the correlation estimating the reduction of the bacteria. Disinfection efficiencies on surfaces can be known by the optical simulation of irradiance, and the optimum position of irradiation and exposure time can be obtained as well. We designed the UV-C LED modules considering their disinfection performance, lifetimes, reliability of UV exposed parts, safety requirement, structural constraints. The fans or pre-filters of the air conditioners were selected as the target parts, since they are often exposed to the humid environment or outdoor air and vulnerable to microbial contamination. Disinfection efficiencies over 99.99% could be obtained on the representative sampling points of the target parts from the whole tested air conditioners including the stand, wall-mounted split, cassette, and ducted type air conditioners. Although the product test was conducted on the air blowing mode, we confirmed that the disinfection efficiencies were not significantly different when the test was conducted on the cooling mode. Currently, we are doing the study expanding the correlation formula for estimating the UV germicidal reduction of other bacteria and coronaviruses including the SARS-CoV-2.

Co-Authors: W.J. Shin, N. Benter, B.K. Park, N. Morgenbrod, Y.M. Yoon

Through the COVID-19 pandemic, general consumers' interest in deodorization and sterilization is increasing. According to LEDinside, a specialized LED market research organization, the UV LED market is predicted to grow rapidly to more than $1.0 bn in 2024. [1] So considering this market size, UV LED is expected to be applied to various fields of daily life in the future. In addition, the request for deodorization and sterilization of automotive interiors by consumers is increasing. In the case of UV-A wavelength (400 - 315 nm), it is used as a deodorization func-tion together with a photocatalytic filter, and is particularly widely applied to air purifiers and refrigerators. In the case of UV-C wavelength (280 - 100 nm), it is used as a physical method to sterilize bacteria and viruses, and especially, it is widely applied to our real-life home appliances such in water treatment and air conditioning systems. Beside Home appliances and various technical treatment applications, UV is ap-plied to maintain a more purified vehicle interior. Nevertheless, conventional UV light sources such as mercury UV lamps have a short lifespan, big dimensions and environmental problems, making it difficult to apply them to automobiles. The article introduces the basics of the UV functions as well as the practical applica-tion of automobiles. We will present research results of deodorization (UV-A + photo catalyst) and sterilization (UV-C) proven through various tests by applying the technology of Violeds (UV LEDs), an environmental-friendly and high-lifetime device.

Co-Authors: Carenco, Alain S, National Institute of Health and Medical Research

In the environment of health care faculties, the concerns over disinfection cost and presence of antibiotic resistant organisms impose a constant challenge on the efficiency, usefulness and relevance of the surface decontamination methods. Rapid, broad action decontamination may be often necessary in the context of health care or laboratory work. Chemical disinfection is current broadly used solution. Using purely physical UV-LED treatment can become a viable alternative for reduction risk of bacteria and virus transmission through surfaces. The advantages of UV-LEDs such as no mercury, no chemicals, organic, dry, ecological and microbiologically safe applications drive the interest and growth of their applications in hospitals. The Trilogy LED technology that uses combination of multiple wavelengths at 265 and 285 nm, offers a high disinfection efficacy, can decrease treatment time and potentially increase safety of decontamination in hospitals. The STERILUV device can be successfully introduced to disinfect and prepare rooms, surfaces of tables and chairs and prevent cross contamination through contact surfaces. LEDs portable devices can disinfect frequently touched surfaces of sinks, taps, toilet surfaces, handles, staircase handrails, and doors during a few seconds of light exposure. This study will present results of the evaluation of disinfection efficiency of different LEDs portable devices from manufacturers in France on contact surfaces in hospitals and provide recommendations on their uses. The reduction of total microflora from 1 to 2.5 log after a few seconds of exposure at the distance of roughly 20-25 cm was confirmed after microbiological testing at INSERM (National Institute of Health and Medical Research, France).

Co-Authors: W.J. Shin, N. Benter, B.K. Park, N. Morgenbrod, Y.M. Yoon

Through the COVID-19 pandemic, general consumers' interest in deodorization and sterilization is increasing. According to LEDinside, a specialized LED market research organization, the UV LED market is predicted to grow rapidly to more than $1.0 bn in 2024. [1] So considering this market size, UV LED is expected to be applied to various fields of daily life in the future. In addition, the request for deodorization and sterilization of automotive interiors by consumers is increasing. In the case of UV-A wavelength (400 - 315 nm), it is used as a deodorization func-tion together with a photocatalytic filter, and is particularly widely applied to air purifiers and refrigerators. In the case of UV-C wavelength (280 - 100 nm), it is used as a physical method to sterilize bacteria and viruses, and especially, it is widely applied to our real-life home appliances such in water treatment and air conditioning systems. Beside Home appliances and various technical treatment applications, UV is ap-plied to maintain a more purified vehicle interior. Nevertheless, conventional UV light sources such as mercury UV lamps have a short lifespan, big dimensions and environmental problems, making it difficult to apply them to automobiles. The article introduces the basics of the UV functions as well as the practical applica-tion of automobiles. We will present research results of deodorization (UV-A + photo catalyst) and sterilization (UV-C) proven through various tests by applying the technology of Violeds (UV LEDs), an environmental-friendly and high-lifetime device.

Ultraviolet Germicidal Irradiation (UVGI) is a proven method of disinfection for both bacterial and viral pathogens. Since the acceleration of the COVID-19 pandemic caused by SARS-CoV-2, the industry has witnessed significant technological innovation and an influx of new light source technologies, devices, and disinfectant enclosures. To increase knowledge of germicidal efficacy for UV irradiation methods, a digital validation of performance can provide confidence from an accurate assessment of in-situ irradiance and dose measurements. When UV-C sources are installed in enclosures and rooms, challenges arise that should be digitally monitored to ensure germicidal efficacy is sustained. These challenges include 1) under and over-dosing due to non-uniformities of UV-C distribution, 2) poorly understood room/chamber dynamics and reflectance, 3) shadowing, and 4) sensor, material, and source degradation. Labsphere has introduced a series of smart UV-C irradiance sensors and meters for R&D and OEM applications that specifically address these issues. In this talk, we discuss our approach to reducing common errors contributing to sensor measurement uncertainty including sensor directional response, calibration, degradation, and application modeling. With a unique near cosine reception approach, these detectors include an exceptional f2 directional response making them ideal for deployment in rooms, chambers, and duct systems.