Xing Li, Purdue University
Authors: Ernest R. Blatchley
8:30 AM - 9:00 AM

Many factors are known to affect the performance of UV disinfection systems. Important among these are the kinetics of microbial inactivation (i.e., dose-response behavior). This research was conducted to quantify variability in UV dose-response behavior of ambient indicator microbes in municipal secondary effluents, and the factors that contribute to this variability. Secondary effluent samples were collected from three medium to large municipal wastewater treatment plants (WWTP) over a period of one year. UV254 dose-response behavior and initial concentration (N0) of three commonly used bacterial indicators (E. coli, fecal coliform, and Enterococcus) and a viral indicator group (somatic and F-specific coliphage) were measured. Corresponding water quality and operating characteristics (TSS, turbidity, BOD, NO2, NO3, NH3, DO, flow rate, precipitation) were also quantified. The results from bacterial dose-response behavior experiments indicated that existing UV disinfection systems that have been implemented using conventional design criteria are likely to be over-designed; this suggests that UV disinfection systems could be improved to reduce environmental impact and operating costs. A two-population model was used to describe bacterial UV dose-response behavior; the inactivation rate parameters from this model were significantly correlated to N0 for all three of the studied bacterial indicators. This suggests that initial bacterial concentration may influence the kinetics of bacterial inactivation. The results of the measurements with ambient phage illustrate the behavior of this indicator group, both in terms of natural variability in their UV dose-response behavior, and their sensitivity relative to other waterborne viruses. These data suggest that ambient coliphage may represent a promising surrogate for virus inactivation in municipal wastewater applications.

Bill Sotirakos, Carollo Engineers
Authors: Andrew Salveson and Edward Wicklein
9:00 AM - 9:30 AM

The first large implementation of ultraviolet (UV) systems occurred in the 1990’s and early 2000’s. These systems, while many were effective, where plagued with challenges, black box design, oversized, undersized, poor hydraulics, inefficient systems, blind controls, and on and on. Across the US, these original pioneering systems are breaking down. Parts are no longer available and new systems offer substantial advantages to operations, permit reliability, and cost. The result is broad scale replacements of installed systems, with each site facing their own particular challenges and opportunities.

Our collective UV knowledge base has grown tremendously since the 1990’s:

• Data data data, we now know the value of data, both collimated beam testing and extensive UV transmittance (UVT) data, resulting in predictable UV performance seasonally, weekly, daily, and even diurnally.
• UV systems are now designed around a validated dose, not a calculated dose.
• UV systems are fully validated, following one of a select few internationally recognized protocols. There is no more guessing of efficiency or capacity, the validation tells the tale of performance.
• System sizing now is intended to match the plant effluent requirements as oppose to an arbitrary dose setpoint with little relevance to the target organisms.
• System controls are vastly improved, using calibrated sensor technologies that allow for a clear understanding of real-time dose delivery
• UVT analyzers, while still problematic, are much improved
• Hydraulic impacts, including water level impacts or approach and exit flow hydrodynamics, are understood through detailed use of computational fluid dynamics (CFD).
  
  Our paper will work through a number of these retrofits, demonstrating the successful replacement of first generation systems with state of the art systems. We will review the replacement technologies, the hydraulic challenges (and fixes), construction sequencing, and startup successes.

Carolina Ontiveros, Dalhousie University
Authors: Stephanie L. Gora, Kyle D. Rauch, Rich Simons, Jennifer Pagan, Amina Stoddart, Graham A. Gagnon
8:30 AM - 9:00 AM

UV light emitting diodes (UV LEDs) are a promising technology for point of use (POU) drinking water treatment because of their ability to switch on and off instantaneously and their smaller footprint compared to conventional UV lamps. Multiple flow through tap-mounted UV LED drinking water treatment units have entered the market in recent years, but to date, few of these have been critically evaluated by a third party and/or been validated according to existing standards. Seven commercially available UV LED POU drinking water treatment units were evaluated under controlled laboratory conditions. Biodosimetry curves were developed at peak wavelengths of 260, 268, and 285 nm using T1 virus and a collimated UV LED apparatus. In agreement with previous studies, viral inactivation rate was highest at 268 nm and lowest at 285 nm. Biodosimetry experiments were conducted on each of the units at its rated flow rate. The UV dose delivered by each unit was calculated based on the amount of T1 inactivation achieved. E. coli challenge testing was conducted on each unit at its rated flow rate to determine whether it could achieve the inactivation claims made by its manufacturer. Some units were more effective than others but none of them consistently met their manufacturer’s inactivation claims. Experiments examining the impacts of lower and higher flow rates and UVT on the performance and energy efficiency of the units are ongoing and will also be discussed in this presentation.

Natalie Hull, The Ohio State University
Authors: Zanna Leciejewski
10:30 AM - 11:00 AM

To optimize UV-C treatment of cyanobacterial toxins, we treated microcystin-LR (mc-LR) with 222 nm emitted by a novel KrCl excimer lamp or 254 nm emitted by a conventional low-pressure (LP) mercury lamp. Because mc-LR has higher absorbance at low wavelengths, we hypothesized the novel excimer lamp would be more effective than LP lamps. Degradation of mc-LR spiked into distilled water was compared to degradation of mc-LR spiked into natural water samples from the Cuyahoga River and Lake Erie to quantify the extent that natural organic matter interfered with mc-LR degradation. Before and after UV exposure, toxin concentration in samples was quantified by ELISA (enzyme-linked immunosorbent assay) and UPLC (ultra-performance liquid chromatography). These methods with different detection mechanisms were used to compare the degradation of mc-LR from two chemical perspectives. In distilled water exposed to the highest UV dose (160 mJ / cm^2), the excimer lamp degraded mc-LR to 15% and 7.5% of the original concentration (measured by ELISA and UPLC, respectively), while the LP lamp degraded mc-LR to 50% and 40% of the original concentration. In spiked natural samples, mc-LR degradation by the excimer lamp was similar in Lake Erie water (6% and 9%) to Cuyahoga River water (10% and 8%). Overall, the novel excimer lamp was ~4X as effective as the conventional LP lamp at degrading microcystin-LR, making UV a more feasible option for treating harmful algal blooms.

Amy Wilson Miller, Crystal IS
Authors: Richard M. Mariita
11:00 AM - 11:30 AM

As increased population and urbanization continues to strain municipal, environmental and healthcare systems, disinfection routines become more critical. For example, deteriorating water and air quality is heightened by the upsurge of antibiotic-resistant superbugs. As a result of increased risks, UVC LEDs are gaining popularity as an alternate technology in disinfection of air, water and surfaces. The performance of these devices has increased quickly in the last several years and we are seeing market adoption in these applications.

In a recent study, Crystal IS evaluated the water disinfection efficacy of UVC LEDs as demonstrated through microbiological challenge testing on various key microorganisms at different conditions. Using different water disinfection reactor designs containing UVC LEDs, log reduction values of microorganisms such as P. aeruginosa, E. coli, and Bacteriophage Qβ were measured. The impact of flow rate, UV Transmittance (UVT), reactor design, and quantity, wavelength, and power output of UVC LEDs was demonstrated with regards to disinfection of different microorganisms

In addition, testing was performed at beginning of life and at after 30,000L of continuous operation of UVC LED reactors. Comparison of results at these two points in time revealed no meaningful degradation in UVC LED disinfection performance, as demonstrated using various water disinfection reactor designs.

During this presentation, the study and small reactor that achieved reduction values of greater than 4 log at a flow rate of 2 L/min, using only two lower power LEDs from the Klaran line of UVC-LEDs, will be discussed. Similar results were achieved before and after 30,000 L (250 hours) of continuous operation.

Olya Keen, UNC Charlotte
Authors: James Bolton, Marta Litter, Keith Bircher and Thomas Oppenländer
10:30 AM - 11:00 AM

In the recent decades, electrical energy per order (EEO) has been widely used as a way to characterize the efficiency of advanced oxidation processes (AOPs). Due to a number of misconceptions about the parameter and incomplete reporting of the testing data, many EEO results were not usable as reported. As a result, the AOP industry has moved to avoid the parameter altogether.

The goal of this presentation is to summarize the results of the recent IUPAC task force effort on standardizing EEO and clarifying some factors that affect it, in the effort to improve the usefulness of the parameter.

Additionally, a new parameter, UV dose/log, was proposed in the recent years for a more unambiguous comparison of reactors and bench-scale to full-scale scale-up. This talk will discuss this parameter as an alternative to EEO.

Kireev Sergey, Scientific and Production Enterprise "Melitta", Lt
Authors: Sergey Shashkovskiy, Konstantin Tumashevich
11:00 AM - 11:30 AM

Such tasks as: purification from a wide range of microorganisms (viruses, bacteria, spores) and parasitic organisms; disposal of dissolved in water and volatile organic compounds; stimulation of advanced oxidation processes (AOP), allowing to achieve a deep purification rate keep the use of continuous spectrum UV sources up-to-date.

Medium-pressure mercury lamps are most often used as a source of a continuous spectrum in the UV region. Pulsed UV lamps have recently been used along with them, which have high radiation intensity and a pulsed action nature.

The use of such lamps in various fields requires knowledge of the absolute values of spectrum response of the lamps. However, existing methods are either too time-consuming or don’t allow to obtain the absolute values of the energy linked to the object in the necessary spectral ranges. Besides that, the record of pulsed radiation is a separate complex photometric task.

A technique for recording the absolute spectral distribution of constant and pulsed action pattern sources has been suggested, justified and tested. The technique consists in the joint use of a spectrometer recording the relative spectral distribution and a photodiode sensor with an integrating circuit with a known absolute spectral sensitivity, which fall into the spectral sensitivity range of the spectrometer. The technique can significantly simplify and speed up recording radiation process over the entire sensitivity range of the spectrometer, as well as calculate the radiation energy in any part of it.

Mariana Lanzarini-Lopes, Arizona State University
Authors: Paul Westerhoff, Francois Perreault
1:30 PM - 2:00 PM

Ultraviolet (UV) radiation purifies water without the need of chemicals. UV Light emitting Diodes (LEDs) are gaining traction over conventional and toxic mercury lamps. However, these christmas light sized lamps result in a small surface area of irradiation, creating a barrier for its adaptation into disinfection technologies. UV-C side emitting optical fibers (SEOF) have the potential to increase light distribution from UV LEDs by 600 times. We have previously fabricated UV-C SEOF by modifying end emitting optical fibers (i.e. light guides). Attaching silica nanoparticles to the surface of the optical fiber glass core, enables the guided light to leave perpendicular to the fiber’s axis. This light can then be used for disinfection. Now we seek to understand the disinfection potential of these optical fibers by placing them in a dense culture of Pseudomonas aeruginosa spread on a LB agar plate. The area where there is no visual growth of microorganisms is reported as the inactivation zone (IZ). These results were obtained for different (i) optical fiber scattering coefficients and (ii) exposure times. There is a linear increase in IZ with exposure time until a maximum IZ (MIZ) is reached. The MIZ ranged from 2 cm to 4 cm for lower to higher scattering coefficient respectively. Additionally, lower scattering coefficient resulted in consistent IZ through the length of the optical fiber due to lower attenuation. This work will educate the density of optical fibers needed for a disinfection reactor design. Implementing UVC SEOFs into reactors will increase light distribution from UV LEDs and advance light driven water treatment technologies.

Kireev Sergey, Scientific and Production Enterprise "Melitta", Lt
Authors: Sergey Shashkovskiy, Konstantin Tumashevich
2:00 PM - 2:30 PM

The synergistic effect of irradiation of the investigated subject simultaneously with several wavelength ranges allows to increase the efficiency of the photo-induced process compared to monochromatic exposure. Besides that, the use of high-intensity radiation sources leads to an increase of the photochemical reaction rate, which is an additional advantage in areas such as environment processing in the flow systems. The flash lamps have all these properties. The use of flash lamps in fields like medicine, food processing, photochemical technology, shows great opportunities for its use. High specific characteristics, as well as developed analytical and numerical models for optimizing lamp operating modes make it possible to effectively use them in flow systems. The developed measuring techniques for electrical and radiation parameters, as well as the pulsed nature of the effect allow to accurately calculate the photo-induced effect depending on the transferred radiation dose.

This research paper presents the electrical and radiation parameters of flashing lamps with an average electrical power of 200 W to 1 kW. The energy deposition efficiency in the plasma, calculated from the ratio of the energies dissipated in the lamp and the circuit, was about 90% for all modes, which indicates good matching of the circuits with the plasma generation. The current density in all the investigated lamps was higher than 4 kA/cm2; it made possible to achieve luminance temperatures above 7kK and efficiently convert electrical energy into radiant.

Felix Becker, ZED Ziegler Electronic Devices GmbH
Authors: Dr. Felix Becker, Dr. Peter Kornetzky, Sascha Krenzer, Steffen Krahnert Dr. Rolf Ziegler, Karin Ziegler
1:30 PM - 1:45 PM

Vacuum ultra violet (VUV) radiation can photo split oxygen molecules. A freed oxygen atom combines with another oxygen molecule to form a molecule of ozone. A common used way for production of ozone applies low-pressure mercury vapor lamps. Such lamps emit radiation with wavelengths of 185 nm (efficiency 6-11 %) and 254 nm (efficiency 30-40 %). Only the VUV radiation at the mercury resonance line with a wavelength of 185 nm can be used to produce ozone. A more efficient and mercury-free method of ozone generation could be the use of excimer lamps based on dielectric-barrier discharges with peak wavelength of 172 nm (efficiency 20-40 %). Particularly, when they are supplied with narrow high-voltage pulses and a sufficiently high frequency. Both methods of VUV induced ozone production are sensitive to environmental conditions, i. e. air humidity. This paper compares established systems based on low-pressure VUV lamps and novel excimer systems in terms of ozone production per hour, efficiency, time course of VUV radiation and the influence of environmental conditions to the ozone production. The results show clearly the benefits of excimer systems. Additionally, the “ZED Ozone Generator – ZO3gen” is presented – a simple and efficient solution for an economical ozone generation.

Arthur Kreitenberg, Dimer LLC
Authors: Maya Jaffe
1:45 PM - 2:00 PM

Introduction:
Textured surfaces are ubiquitous in the healthcare setting and provide pathogens shadowed “shelters” from germicidal UVC exposure. Like the sun passing over and exposing a deep canyon floor, a textured surface may be more efficiently disinfected with UVC lamps in motion than lamps that remain stationary.

Hypothesis:
At the same UVC dose, a greater reduction of viable bacteria is achieved with parallel lamps in motion than parallel stationary lamps.

Materials & Methods:
Disinfected ABS 10cm x 10cm textured tiles were inoculated with a Staph aureus solution, allowed to dry and arranged horizontally around a UVC meter (Intl Light Technologies). UVC mercury lamps (UVHammer) were positioned horizontally & stationary 1.1m directly above the tiles (n=8) and exposed to 6.0(±0.1) mJ/cm². Quantitative Baird Parker contact plates (Hardy Diagnostics) were then used to culture the tiles. The process was repeated with the lamps passing over the tiles repeatedly at a rate of approximately 30 meters per minute, until a 6.0(±0.1) mJ/cm² exposure was measured. CFUs were counted 36 hours after incubation at 35°C.

Results:

CFUs per plate(n=8):

1. UVC Lamps in motion are approximately 2.5 x more effective than stationary lamps for disinfecting textured surfaces, at the same UVC dose.
2. UVC measurement alone is unreliable on a textured surface as germicidal level depends on lamp motion.

Peter Kornetzky, ZED Ziegler Electronic Devices GmbH
Authors: Dr. Peter Kornetzky, Thomas Rathgen, Dr. Rolf Ziegler, Karin Ziegler
2:00 PM - 2:15 PM

The performance of low-pressure amalgam lamps is strongly dependent on temperature conditions. Small changes of environmental temperature can result in a drastic drop of UV output with considerable impact on disinfection performance. This effect will be even more significant when a lamp is operated in the dimmed mode. As a result, the UV output can become unpredictable. The reason lies in the temperature dependency of the mercury pressure.

ZED addresses this problem with the “PPT – Perfect Performance Tool”. The PPT is an electronic lamp socket for out-of-arc lamps. It compensates the impact of dimming or water temperature fluctuations on the vapor pressure by the loop-control of the amalgam temperature. A lamp equipped with PPT produces a constant UV output for a wide range of water temperature. Particularly, the performance in cold water is increased. Predictable and stable UV outputs are realized for all dimming levels and the full temperature range.

The PPT is an autonomous system, which is directly mounted at the lamp. An additional power source or extra wiring are not needed. The power for the electronic system is supplied as a part of the lamp power by a compatible electronic ballast. Due to the minimized variation in UV output, a substantial amount of energy might be saved since the amount of “over-dosing” can be reduced when designing UV disinfection systems.

PPT makes low-pressure amalgam lamps predictable and stable with an UV output that is independent from water temperature for all dimming levels.

Eric Oh, Photon Wave Co., Ltd.
Authors: Kyoung Hoon Kim
2:15 PM - 2:30 PM

We present high performance and reliable 265nm UVC LED. As well known, the sterilization effect of UV light is the most effective around at 265nm wavelength, which comes from UV light absorption nature of DNA chains. However, in order to make shorter UV emission with III-Nitride materials, higher Al content in AlGaN structure is necessary, which used to result in poor optical and electrical quality in LED devices.

This is the reason why 270~280nm UVC LEDs have been widely used in the beginning stage of UVC LED development, which shows similar sterilization effect as UV Lamps (~253nm). Currently, Photon Wave has achieved highly efficient 265nm UVC LED thanks to a couple of breakthroughs.

Photon Wave has been established in year 2016, based in near Seoul, South Korea. It is UV LED specialized manufacturer from EPI wafers to Packages, working with UV LEDs experts.

Recently, 265nm UVC LED with output of >40mW at 350mA driving current is ready in product line-up by adopting self-aligned growth technology and chip design, contributing optical and electrical improvements. Operating voltage is lower than 6V (typ. ~5.7V) with greater than 2.0% of wall plug efficiency (WPE).

In this forum, we will introduce Photon Wave’s 265nm UVC LED in details and future work to enhance further. Also, advantages of 265nm UVC light for sterilization application will be represented showing experimental result of wavelength versus sterilization effect.

Scott Alpert, Hazen and Sawyer
Authors: Scott M. Alpert, Erin Mackey, Damon Roth, Bertrand Dussert

In 2017, AWWA’s Disinfection Committee developed the fifth edition of the AWWA Water Utility Disinfection Survey to capture current disinfection practices and trends for utilities in the United States. Since March 1978, the drinking water community has reflected on disinfection practices in the United States every ten years through thes, which affords the drinking water industry to better understand how best practices and new technologies emerge over time and to evaluate how regulatory compliance and technological innovation impact adoption of alternative disinfectants. The objective of this poster is to highlight the survey results relevant to UV disinfection and that are of most interest to the UV community. The proposed authors represent the AWWA Disinfection Committee working group that led the development of the survey and analysis of the results. The 2017 Survey focused on the disinfection technologies used, or currently being considered for use, by the respondents, including free chlorine, chloramines, chlorine dioxide, UV, and ozone. From the survey responses, UV growth is driven in part by the need for compliance with EPA’s LT2ESWTR. Improvements in system design, decreasing capital costs, and more energy efficient lamps are encouraging growth. One of the goals of the survey was to identify the major benefits and challenges associated with each disinfection technology. The main identified benefit of using UV over other disinfectants is its ability to inactivate Cryptosporidium. Additional benefits included DBP control, chemical-free process, reliability, and small footprint. Similar to ozone, one of the major challenges associated with UV is training of the operators during the start-up period due to their lack of familiarity with the equipment. Although utilities indicated they are focused on costs, there are many other factors driving disinfection decisions including regulatory requirements, DBP formation, and ability to meet multiple objectives Utilities that have moved towards alternate disinfectants such as chlorine dioxide, ozone, and UV treatment expressed fewer concerns about regulatory issues and more concerns about operations and maintenance. A poster presentation will allow the authors to graphically highlight UV disinfection trends, benefits, and challenges identified within the survey. Attendees of the poster session will gain a better understanding of how UV disinfection is perceived by utilities compared to other alternative disinfectants and what challenges need to be addressed by the UV community for further adoption of the technology.

Peter Gordon, IUVA, Keith Warriner, and Mahdiyeh Hassani, University of Guelph

Fresh produce remains a significant food safety issue associated with foodborne illness outbreaks and an established vehicle for pesticides. The post-harvest wash step designed to remove contamination has been found to spread both microbial and chemical hazards across batches. Consequently, there is a need for technologies that can act as firewall between the field and consumer to address food safety issues. To this end, a decontamination technology based on Advanced Oxidation Process (AOP) has been developed and validated. AOP generates reactive, but short-lived, free-radicals that inactivate microbes (viral, bacterial and fungal) and degrades pesticides. The most common AOP format is through the generation of hydroxyl radicals by the UV-C mediated decomposition of ozone and hydrogen peroxide, although other radical sources such as hypochlorous acid can be applied. The AOP process is performed by passing the produce to be decontaminated through a hydrogen peroxide mist then into a chamber housing UV-C (254 nm) and ozone (174 nm) lamps. Validation trials applied Response Surface Modelling (RSM) to optimize the treatment to ensure optimal microbial reduction without changing the quality attributes of the produce being treated. To date a diverse range of produce types from grapes, apples, cantaloupe, lettuce amongst others. The operating parameters to decontaminate produce was product specific. For example, a 5 log reduction of Listeria monocytogenes on and within apples, was achieved through applying 3.0 % v/v hydrogen peroxide, 1.6 mg ozone and 54 mJ cm² UV-C. The same log reduction of Listeria on lemons was achieved using 1.8% v/v hydrogen peroxide, 2.2 mg ozone and 68 mJ/cm². AOP treatment was found to degrade the pesticide chlorpyrifos on apples by 1.68 ppm (1680 ppb) and could also be applied to disinfect surfaces such as encountered on reusable plastic crates.

Rachel Gehr, Purdue University

The prevalence of per- and polyfluoroalkyl substances (PFAS) in drinking water has become a source of concern due to their toxicity and recalcitrance toward conventional water treatment methods. While several treatment processes have proven to be effective for defluorination of PFAS by cleaving the C-F bond, toxicity may be increased due to the formation of intermediates. This study investigates the stepwise approach of coupling vacuum UV (VUV) treatment with sulfite for complete degradation of PFAS without forming toxic intermediates through 1) generating a reducing environment to reduce fluorine to fluoride by aqueous electrons, and 2) inducing an oxidizing environment by VUV to promote carboxyl groups for subsequent defluorination. This alternation between oxidizing and reducing environments is achieved by periodic adjustment of solution pH. Increasing pH promotes reducing conditions for defluorination by hydrated electrons and decreasing pH induces an oxidizing environment by the hydrogen atom to promote carboxyl groups. Future experiments include the addition of hydrogen peroxide for increased hydroxyl radical production and improved defluorination efficiency. Experiments are conducted on representative PFAS from prominent subgroups, including perfluoroalkyl sulfonic acids, carboxylic acids, and fluorotelomer alcohols. In this study, the alternation between oxidizing and reducing environments is evaluated to determine its effect on achieving complete defluorination of PFAS in drinking water sources.