Yuri Lawryshyn, University of Toronto
Authors: NA
8:30 AM - 9:00 AM

The combined variable (CV), defined as the ratio of the power output percent (based on sensor readings) divided by the flow rate and organism sensitivity, has been shown to provide a strong linear relationship between it and the log inactivation of a given UV reactor and has gained acceptance in estimating UV reactor performance based on bioassay data. The CV approach stems from the fact that the log inactivation (LogI) for a single microbial path will be directly proportional to the UV lamp intensity and inversely proportional to the flow rate and organism sensitivity. The main purpose of this talk is to review the theoretical aspects of the CV approach. The theory is developed by conceptualizing a simple UV reactor with multiple particle trajectories whose effective water layers, defined as the average distance between the particle and the lamp sleeve, are assumed to be random variables and the impact of the variance of the effective water layers on the CV approach is examined. Specifically, the talk will discuss the theoretical merit of the approach, theoretical aspects related to non-linear microbial kinetics and the theory associated with putting reactors in series. Results of numerical experiments supporting the theory will be presented. While certain aspects of this work have already been presented by the author, the talk serves as a review of previous presentations with adjustments made for recently discovered aspects of the theory.

Nikhil Sangwan, Purdue University
Authors: Nikhil Sangwan, Yousra M. Ahmed, Ernest R. Blatchley III
9:00 AM - 9:30 AM

The United States Environmental Protection Agency (EPA) requires UV disinfection reactors used in public water systems (PWS) to be validated and regularly monitored for the mandated minimum performance. Large PWS often employ the Calculated Dose Approach, one of the two dose monitoring approaches mentioned in the EPA’s Ultraviolet Disinfection Guidance Manual, as it allows optimization of operating costs. It involves development and application of an empirically-derived equation to estimate the Reduction Equivalent Dose as a function of operating conditions. Although the equation currently being used for this purpose has its origin in CFD-based UV dose models, it does not adequately capture the relevant fluid mechanics and optics. Moreover, this approach yields a single dose value for a given set of operating conditions and ignores inherent stochasticity. We propose an alternative approach that addresses these limitations by making use of a function that scales dose distributions across a wide range of operating conditions. It involves the use of dimensionless groups of variables that describe fundamental, measurable aspects of reactor design and operation. Output of the model is an estimate of the dose distribution delivered by the reactor, which is an inherent characteristic of the system. These results can be integrated with appropriate microbial kinetic expressions to estimate reactor performance. Preliminary testing of this approach on two large-scale and one bench-scale reactors has shown promising results. Besides being computationally inexpensive, we believe that this approach better captures the underlying physics and stochasticity, and thus has potentially great utility for UV disinfection industry.

Marko Hofmann, Seoul Viosys Co., Ltd
Authors: Carlton Gibson
8:30 AM - 8:45 AM

Flexible UVC LED system design based on WICOP LED Technology

In recent years, as in the early days of visible LED technology, there has been a competitive chase to achieve the highest single chip output powers. Having seen the massive market adoption of mid power visible LED technology over high power LEDs, Seoul Viosys and Sensor Electronic Technology have focused on manufacturability, versatility and long life-time UVC LEDs. UVC wafer integrated chip on package [WICOP] technology has the potential to change the landscape of UVC LED based systems by increasing design flexibility and offering unparalleled value [$/mW] to the system manufacturer.

Customized WICOP on board [WOB] solutions can be designed and manufactured using the same tools and assembly technologies as standard SMD PCB products.

We will share design guide lines for robust and scalable UV LED systems to meet today’s challenges and still being compatible with standard PCB design rules.

We will review WOB designs such as high power density [>1000mW/cm2] configurations for flowing water, skin treatment and surface curing applications as well as high uniformity concepts for disinfection and horticulture applications. Considerations for thermal management, real world performance data and system life-time evaluation methodologies will be explained.

Peter Gordon, Bolb Incorporated
Authors: none
8:45 AM - 9:00 AM

High Wall Plug Efficiency, deep ultra-violet emitting light-emitting diodes based on proprietary device structure breakthroughs, namely a transparent and highly conductive P layer, enable novel germicidal photonic platforms which now exhibit considerably higher Germicidal Performance Application ( GPA) proficiencies than legacy low WPE LEDs and 254 nm LP lamps in specific implementations. A high GPA coupled with significant solution footprint reduction, as well as installation, operational, and electrical cost savings, and are important attributes since light in the range of 262-278 nm generated by LEDs disrupts the DNA or RNA of infectious pathogens as well as spoilage organisms more effectively than conventional reliance on light from 254 nm emitters. Such Germicidal LEDs (GLEDs) now positioned to enable wide deployment of non-chemical, non-touch, germicidal applications where footprint, cost, and ease of implementation matter. The implications of such availability has accelerated adoption in Drinking Water Safety, HAI Prevention, Horticulture, Food Security, and Air Purification. Such applications will be discussed including suggested configurations and use approaches, validation methods, and ongoing instant verification of efficacy techniques.

Marko Hofmann, Seoul Viosys Co. LTD
Authors: Mr. Jae Hak Jeong
9:00 AM - 9:15 AM

Clean air is an essential good. Unfortunately air quality is getting worse and the pollution increases. To improve indoor air quality, filters and ionizers have been the technology of choice over the past decades. Seoul Viosys researchers have performed extensive testing to develop a cost effective and safe method to improve indoor air quality without generating harmful byproducts. We will explain our test parameters and share results on the removal of VOCs, such as Formaldehyde and Ammonia as well as odors originating from produce and fish or meat products (e.g. Trimethylamine and Methyl Mercaptan). UV LEDs in combination with optimizedTiO₂ Photocatalysts can be used in numerous applications and have the ability to significantly improve the quality of the air we all breathe. This technology has also the capability to reduce the concentration of airborne pathogens in environments that are prone to such pollutants. Seoul Viosys will present an outlook on UV LED andTiO₂ deodorization technology and explain the main design parameters that have to be considered during the development phase of a chemical free, non-toxic and environmentally friendly deodorization system.

Elliot Kreitenberg, Dimer LLC
Authors: None
9:15 AM - 9:30 AM

INTRODUCTION TO PROBLEM:

Routine disinfection of human occupied spacecraft interiors is currently performed by crewmembers using disinfectant wipes. This method suffers several disadvantages including marginal effectiveness, chemical toxicity, launch and return of wipes. Crewmembers may spend up to 4 very expensive hours per week in an arduous and dreaded task. A novel yet viable method and device are described using a unique integration of evolving technologies.

SOLUTION:
The “GermRover” is a smaller than shoe box sized device with strategically located UVC-LED arrays. Sensors determine the position, orientation and velocity of the platform. An on-board microprocessor activates propellers to control these parameters and LED powering. Disinfection time estimate is 1 hour per module, and performed during crew sleep time. A docking station recharges the onboard battery. Earth-based drones require the vast majority of their stored energy to remain aloft. Drones in a microgravity environment are freed of battery weight constraints and can use the energy for the payload, in this case powering the UVC-LEDs. Spaceflight certified LEDs are already on orbit. The GermRover may also be used in a hand-held mode for specific surface disinfection, including food prior to consumption. This technology was a 2018 NASA iTech innovation award winner.

APPLICATION:
The International Space Station has an immediate need for an effective, chemical-free, disposables-free, crew independent, consistent and reliable method for interior disinfection. The GermRover meets these criteria. A prototype will be part of the presentation. Beyond ISS, planned human-occupied spacecraft for LEO and interplanetary will predictably require such disinfection technologies.

Sunny Kim, Neotec
Authors: Woo Chul Hwang, Sun Baek Kim
9:30 AM - 9:45 AM

Conventionally, ultraviolet (UV) light sources (lamps) for large capacity UV disinfection system are configured to evenly distribute UV dose for all streamlines. Also, the UV light sources must withstand above a certain level of hydrodynamic pressure and the configuration of fouling control device must be considered. Cylindrical shape, currently applied in mercury UV lamp design, is one of the structures that satisfy all these requirements. UV-C light-emitting diodes (LEDs) fixed on a flat printed circuit board (PCB) plate meet the above requirements and UV-C LED lamp modules were designed in a cylindrical shape to have a light distribution profile similar to the one for mercury lamp reactors. Optical and biological tests were conducted to compare a UV-C LED lamp module with a mercury UV lamp reactor.

Zhe Sun, Purdue University
Authors: Zhi Zhou, Ernest R. Blatchley III
10:30 AM - 11:00 AM

Adenovirus is among the most UV-resistant waterborne human pathogens and plays an important role in the regulations for virus inactivation established by U.S. Environmental Protection Agency. Due to the risk of human exposure and difficulty in the adenovirus culture method, microbial surrogates that are more easily cultured and safer to work with may be preferred. In this work, the algal virus Paramecium bursaria chlorella virus (PBCV-1) was studied as a surrogate for adenovirus in validation of UV reactors. Similar to adenovirus, PBCV-1 is double-stranded DNA virus, but is safer to work with and easier to culture. We characterized the UV dose-response behavior of PBCV-1 to monochromatic UV radiation at 254 nm, as well as the UV dose-response behavior at other UV wavelengths (i.e., action spectrum from 214 nm to 289 nm) using a collimated beam system equipped with a medium-pressure Hg lamp and narrow bandpass optical filters. In addition, UVC-induced viral DNA damage was evaluated by a real-time quantitative PCR. The results showed that a UV254 dose of 120 mJ/cm2 resulted in roughly 5-log10 units of reduction of PBCV-1, which is within the range of UV254 sensitivity reported for adenoviruses. The inactivation action spectrum showed that PBCV-1 inactivation, similar to the action spectrum of adenovirus, was favored at wavelengths below ca. 240 nm, with an optimum being observed among the measured wavelengths at 214 nm. Therefore, PBCV-1 appears to represent a potential surrogate of adenovirus for UV treatment performance tests at various wavelengths. More broadly, this research points to opportunities to apply algal viruses as surrogates for human pathogens. These viruses are non-pathogenic to humans, easy to culture, and prevalent in nature.

Yuri Lawryshyn, University of Toronto
Authors: NA
11:00 AM - 11:30 AM

The combined variable (CV), defined as the ratio of the power output percent (based on sensor readings) divided by the flow rate and organism sensitivity, has been shown to provide a strong linear relationship between it and the log inactivation of a given UV reactor and has gained acceptance in estimating UV reactor performance based on bioassay data. One aspect that the author considered previously was the use of the CV for reactors in series. Theoretical arguments were presented that showed that putting two reactors in series and multiplying the validated CV value by a factor of two should produce conservative (safe) system performance estimates. However, numerically, the CV fitting approach that is currently recommended did not always work and non-conservative scenarios were presented. In this work, we present further advancement in the issue of putting reactors in series. The current work supports the previous theory and shows that a multiplication of the CV by a factor of two, for the case of two reactors is series, is acceptable under certain circumstances. However, we further expand the models and show that the empirical fit used in the CV equation approach has limitations with respect to extrapolation – as would be the case in placing reactors in series. Guidelines to deal with the limitations are presented.

Richard Martinello, Yale School of Medicine
Authors: Co-authors will be added at a later date
10:30 AM - 11:00 AM

Ultraviolet-C (UVC) devices have been shown to reduce the incidence of certain healthcare-associated infections by up to 35%, yet there are many science-based needs that must be addressed to optimally support the wide-spread adoption and use of the technology. The National Institute of Standards and Technology (NIST) has engaged with the International Ultra Violet Association (IUVA) to explore how standards and measures of device disinfection efficacy, reliability, operations and durability may help address these needs. Leveraging this partnership is essential to implement standards through federal participation in the development and use of voluntary consensus standards and in conformity assessment activities. The issues were recently discussed at the NIST campus in Gaithersburg, Maryland during a special workshop event with several panel sessions focused on a number of important and timely topics including the fundamentals of UVC disinfection, biological and light measurements, the impact on microbes in the environment and healthcare associated infections. This presentation will provide an overview of the panels and their outputs. It will include recommendations for a path forward to develop standards and guidance related to healthcare disinfection applications for UV technology. A discussion on how to achieve the development of standard methods for validating UV device performance and test guidelines for efficacy measurements through best measurement practices of both physical and biological media will be presented.

Arthur Kreitenberg, Dimer, LLC
Authors: Maya Jaffe
11:00 AM - 11:30 AM

Background:

Germicidal UVC can effectively disinfect healthcare surfaces, but frequently touched and contaminated fabric privacy curtains are a challenge. Textured and absorbent fabric provides pathogens shadowed “shelters” from UVC exposure.

Hypothesis:

10x and 20x usual UVC exposure on both sides of curtain fabric with lamps in motion can achieve a log₃ kill of Staphylococcus aureus.

Materials & Methods:

Non-antimicrobial hospital curtain fabric was cut and mounted onto frames allowing test surfaces of 10x10cm squares. The frames were laid horizontally and inoculated on one side with drops of solution containing Staph and allowed to dry. A UVC lamp mounted on a linear actuator was passed horizontally over the fabric at a rate delivering 15.5 mJ/cm² per pass. One group (n=6) received 4 passes (62 mJ/cm²) and the second group 8 passes (124 mJ/cm²). The process was repeated to the other side of the fabric providing 10 and 20 times the usual log3 dose. Baird Parker contact plates (Hardy Diagnostics P16) were used to culture the inoculated side of the fabric and incubated for 36 hours at 35°C. CFU’s were counted and compared to unexposed fabric results.

Results:

Jennifer Osgood & Chris Schulz, CDM Smith
Authors: Jennifer Osgood, Chris Schulz
1:30 PM - 2:00 PM

Utilities with UV systems need to address lamp breakage and assessing the potential of mercury release. The potential for UV lamp breakage, impacts of mercury releases into the finished water supply, and mitigation measures to respond to ultraviolet lamp breakage events are considerations for treatment plant operations. The presentation will summarize the results including a summary of mercury release analyses for MP and LPHO UV reactors for a pressurized pipeline system and a post-UV clearwell system at water treatment plants.

Paul Swaim, Jacobs
Authors: Joseph Zalla, Sean Menk, Michelle De Haan, Chad Busch, Roger McClain
2:00 PM - 2:30 PM

Park City Municipal Corporation (PCMC) in Utah has selected UV disinfection as a key disinfection barrier at two different water treatment plants serving the community of less than 10,000 people. PCMC and Jacobs have installed a UV disinfection system at its small Creekside Water Treatment Plant (Creekside) as part of implementing treatment necessitated by re-classification as groundwater under the direct influence of surface water. The 1,000 gallon per minute UV system has been operating to achieve disinfection credit for more than a year. PCMC and Jacobs are also completing the design for the new 3Kings Water Treatment Plant (3KWTP), a 5,000 gpm facility with surface water treatment capability. The UV system will provide a barrier for Giardia (and Cryptosporidium) for two mine tunnel waters and one spring water source. The 3KWTP is being implemented on a tightly constrained site, with full conventional treatment to be built between two holes of the municipal golf course. The use of UV disinfection allowed the chlorine contactor to be reduced in size significantly to better fit on the site. This presentation will review both projects as case studies, discuss the drivers for using UV disinfection, and describe the UV facilities design and operation.

Oliver Lawal, AquiSense Technologies
Authors: Dr. Jennifer Pagan, Dr. Rich Simons
1:30 PM - 2:00 PM

UV-C LED devices get a lot of attention for their specific characteristics: form factor, emission spectrum, power output, efficiency, etc. However, they are merely one component in a complete UV water disinfection product—batteries in an electric car, if you like. Ultimately, it is the UV system that must deliver the required log reduction, and while wavelength and power are important, they are only part of the story.

Tens of thousands of UV-C LED systems have been produced over the past year and the rate of production is growing exponentially. In the absence of suitable regulations or industry guidelines the responsibility for design, production, and operational quality largely sits with manufacturer. Manufacturers are taken on their word that their products meet their marketing claims and a pyramid of trust is built from the LED manufacturer, through each link of the supply chain to the end user, with no rigorous framework for oversight or accountability.

How should standards be applied with this new technology? Why is this even a question? What is wrong with applying existing UV technology regulations to UV-C LED technology? Blindly applying inappropriate regulations is problematic. So, also, is ignoring regulations entirely. By doing so we undermine the credibility of this new technology and limit implementation by serious professionals.

This paper outlines a holistic view of the various elements necessary for safe technology implementation, including:

• Microbiological Verification
• Materials Compatibility
• Safety Compliance
• Functional Operation Verification
• Production Process Verification

Mike Blumenstein, NSF International
Authors: Rick Andrew
2:00 PM - 2:30 PM

NSF International recently issued an important update to NSF/ANSI 55 – Ultraviolet Microbiological Water Treatment Systems. Historically, only treatment systems using a low-pressure mercury lamp were able to be certified, as the performance test method was a biodosimetry test. A new test method has been developed for alternative UV sources, including LED diodes, allowing certification of systems emitting UV light across the entire range of 240 nm to 300 nm.

In 2014 the NSF Joint Committee on Drinking Water Treatment Units charged their UV Task Group with developing a new test method for alternative UV systems. Because LED diodes can be tuned to emit UV radiation at any wavelength, the new test protocol had to abandon the biodosimetry approach and simply be a demonstration of inactivation of the test organism.

After considerable discussion, research, and laboratory validation testing, the task group arrived at the Qβ coliphage virus as the challenge organism. This virus was chosen because of its ease of use, fairly linear dose-response curve, and because it is a conservative surrogate for rotavirus, which has been the benchmark for UV inactivation of viruses.

Systems with a UV sensor and alarm must be tested at the alarm set-point UV transmittance, so another important consideration was identification of UV absorbing compounds that cover the entire wavelength range of 240 nm to 300 nm. The task group found that the best option is a combination of vanillin and SuperHume® in a ratio of 1.0 mg vanillin to 0.02 mL SuperHume®.

This new test method provides an important means of validating new alterative UV systems as they become more commonplace in the market.