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2019 Quarter 4

UV-C Effectiveness in Healthcare Environments UV LEDs for Food Applications Advantages of Low-Pressure Lamps Validating UV Technology

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2019 Quarter 4

Featured articles Effectiveness and the ‘Canyon Wall Effect’ of Textured Healthcare 14 UV-C Environment Surfaces When it comes to textured surfaces in healthcare environments, it is important to understand how the “canyon wall effect” affects processes of disinfection.

by Maya Jaffe, biomedical engineering student, Georgia Institute of Technology

18 UV Degradation Effects in Materials – An Elementary Overview

For manufacturers and users of UV-C disinfection equipment, it is extremely useful to have a good understanding of the potential degradation effects that can come from UV-C exposure.

by Chris Rockett, production and applications engineer, LightSources, Inc.

Low-Pressure Lamps – Offering Many Advantages 23 UV Across Multiple Platforms UV technology for low-pressure lamps is constantly evolving, offering innovative advantages for a wide range of applications.

by Wiebke Breideband, project manager-marketing, Heraeus Noblelight GmbH

Overview of UV Disinfection Technologies 29 Market for Food Safety Applications To best approach the problem of food safety, the true magnitude of the problem must first be addressed.

by Molly McManus, regional sales manager, AquiSense Technologies Kayla Doerzbacher, applications engineer, AquiSense Technologies

33 The Quest for UV Treatment Validation

With UV treatment becoming more popular for pasteurizing juices and other beverages, more accessible information about UV is needed.

by Chris Hartman, founder and president, Headwater Food Hub

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O Treatment: The Ultimate Solution for the Degradation 40 UV/H of Pyrazole 2


In 2015, high concentrations of pyrazole were found in the river Meuse, leading to the pursuit of effective solutions for existing drinking water treatment plants.

by Bram J. Martijn, team manager-research and development, PWN Water Supply Company Joop C. Kruithof, Ph.D., Wetsus European Center of Excellence for Sustainable Water/Technology


Executive Operating Committee Ron Hofmann, Ph.D President

Jutta Eggers, Ph.D. Ian Mayor-Smith EMEA Co-Vice Presidents

Kumiko Oguma, Ph.D. Asia Vice President

Ernest “Chip” Blatchley Ted Mao Americas Co-Vice Presidents

Gary Hunter, P.E., Treasurer Richard Joshi Secretary Jennifer Osgood, P.E., PMP, BCEE President-Elect Oliver Lawal

6 6 8 10

President’s Letter From the Editor-in-Chief Focus on Healthcare and UV Disinfection Focus on Food and Beverage Safety

12 36 38 46

Association News Operators Corner UV Industry News Calendar/Ad Index

Editorial Board


Jim Bolton

Jim Malley

Bolton Photosciences Inc.

Professor Ezra Cates Clemson University

Christine Cotton, P.E. ARCADIS

Samuel S. Jeyanayagam, Ph.D., P.E., BCEE CH2M Hill Professor James P. Malley, Jr., Ph.D. University of New Hampshire Jennifer Pagan Aquisense Technologies

Phyllis B. Posy PosyGlobal

Harold Wright Carollo Engineers

Published by:

UV Solutions (print version) (ISSN 1528-2017) is published quarterly by the International Ultraviolet Association, Inc. An online version is posted on

2150 SW Westport Dr., Suite 101 Topeka, KS 66614

Opinions expressed in this publication may or may not reflect the views of the Association and do not necessarily represent official positions or policies of the Association or its members.

Graphic Designer Kelly Adams


Managing Editor Brittany Willes

Advertising/Sales Janet Dunnichay

Immediate Past President

2019 Quarter 4




Ron Hofmann IUVA president / professor, University of Toronto Contact: ron. hofmann@ 416.946.7508

t is a pleasure to write my first message for UV Solutions as the new president of the IUVA. My first order of business is to offer my profound thanks to Oliver Lawal for having served as president for the last 2½ years. Under his leadership, the association has undergone a period of substantial but exciting change. There has been a major effort to broaden the scope of the different sectors beyond our traditional focus on water disinfection. For example, IUVA has made a remarkable effort to establish a presence in the area of healthcare-associated infections (HAI). A working group of more than 40 volunteers is focused on educational efforts, organizing workshops and identifying ways that the IUVA can bring some of its expertise to the world of HAI. A similar initiative is growing in the area of UV applications in the food and beverage industry. This working group, also including over 40 participants, held a webinar on the topic last January that had more than 180 audience members, and the group attended a NIST/USDA workshop in October. The IUVA Americas conference next March will have sessions dedicated solely to these new focus areas, and many other activities are being planned. Of course, the IUVA continues to target its traditional area of water treatment. The last two years have seen some important activities in this sector. A group of IUVA volunteers worked to prepare a response to the “Innovative Approaches for Validation of UV Disinfection Reactors” document for the US EPA. Another group of volunteers helped to create and deliver a series of workshops targeting US state regulators to help them better understand the process of interpreting UV reactor validation reports. These are part of an ongoing commitment by the IUVA to help better equip regulators with the information needed to be more confident in approving UV disinfection systems. At present, the complexity of the science and engineering is a real barrier to more widespread adoption of UV disinfection. All these activities lead to exciting times for the IUVA. As a volunteer organization, none of this is possible without members becoming involved and engaged. I encourage you to stay updated on the various IUVA activities and initiatives through UV Solutions. If there is a topic that you feel passionate about, please reach out to the IUVA to become involved.



Jim Malley UV Solutions editor-in-chief / University of New Hampshire Contact: editorinchief@

ith the support of IUVA and Peterson Publications, we are happy to present this fourth issue of UV Solutions – Innovations for Industry, Public Health and the Environment. The recently introduced section, Operators Corner, continues in this issue with a thought-provoking article on systems that ensure UV performance. This issue also includes cutting-edge articles related to air and surface treatment – read about the “canyon wall effect” in surface disinfection for healthcare environments – as well as the UV technology market in food applications and the photodegradation of organic contaminants such as pyrazole. Take note of updates for the active committees including food and beverage and healthcare, as well as other news. UV Solutions brings a broad array of information and applications in the field of UV technology in one concise quarterly publication – please read and enjoy! The ads make it possible to publish the magazine, so please support the advertisers by visiting their websites or contacting them for further information. If you are a marketing manager in a UV company, we encourage you to advertise. You will not only attract direct sales but also enhance your image in the UV community. Contact Janet Dunnichay at to receive the UV Solutions Media Kit. Those interested in submitting technical content for consideration of publication in UV Solutions please submit papers to Jim Malley, editor-in-chief. We also welcome feedback and suggestions as part of the goal of continuously improving UV Solutions, so do not hesitate to reach out. Readers, please note that the information provided in UV Solutions is reviewed by one technical editor and by a professional publications staff, but it is not subjected to a rigorous peer review process. Authors provide information in an open and collaborative manner with opinions, conclusions and recommendations presented from their perspectives and experiences, which does not necessarily reflect, nor is there any implied or expressed guarantee of its content, by IUVA.

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International Standards Organization Seeks IUVA’s UV-C Expertise


IUVA Healthcare/UV Working Group

Troy Cowan director, Vision Based Consulting

UVA’s Healthcare/UV Working Group was invited by a representative of the International Organization for Standardization (ISO) Technical Committee 142 to attend its 15th Plenary Meeting at ASHRAE headquarters in Atlanta, Georgia, in late September. Professor Yongheng Huang, convener of the ISO/TC142/WG2 (cleaning equipment for air and other gases/UV-C technology) invited the group after learning about its efficacy standards initiative. Huang reached out in hopes that IUVA and ISO/TC142 could work to promote the standardized application of UV disinfection in the health field of air disinfection, an ISO priority focus. Focused on “Standards: the world’s common language,” ISO is an independent, nongovernmental international organization that manages a global network of standards-making bodies (members) across 164 countries. Each member is identified by ISO as the foremost standards organization in their respective country, with only one member per country. In the US, the designated national standard-making body is the American National Standards Institute (ANSI). As one of ISO’s more than 300 technical committees, ISO/TC142 is charged with managing ISO standards covering “Cleaning Equipment for Air and Other Gases.” There are 20 full participating members on ISO/TC142 (see Table 1). These members influence ISO standards development and strategy by participating and voting in ISO technical and policy meetings. Within ISO/TC 142, there are now 12 working groups. Working Group 2 (WG2), led by Huang, is responsible for the formulation of methods and standards for UV application in air disinfection and purification. At Huang’s request, IUVA’s Healthcare/UV Working Group briefed the ISO/TC142/WG2 panel

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Figure 1. From left, Professor Yongheng Huang and Troy Cowan, IUVA, brief ISO/TC142-WG2 on healthcare/UV issues. Table 1. ISO/TC142 member countries and their standards organizations ( committee/52624.html) Austria (ASI)

Ireland (NSAI)

Belgium (NBN)

Italy (UNI)

Brazil (ABNT)

Japan (JISC)

Canada (SCC)

Korea, Republic of (KATS)

China (SAC)

Netherlands (NEN)

Denmark (DS)

Spain (AENOR)

Finland (SFS)

Sweden (SIS)

France (AFNOR)

Switzerland (SNV)

Germany (DIN)

United Kingdom (BSI)

India (BIS)

United States (ANSI)

on IUVA as an organization, on its Healthcare/ UV Working Group and on its efficacy standards initiative specifically. Efforts were addressed around the need to have one standardized set of inactivation dosage values for specific pathogens at particular UV wavelengths of interest. The presentation was well received and resulted in ISO/TC142/WG2 recommending a new proposed ISO work item to address the need for a standard on “Measuring UV Dose Required

to Inactivate Selected Microorganisms Using Different UV Wavelengths.” The proposed recommendation was discussed with ISO/ TC142’s chairman, Riccardo Romanò, and the manager and secretariat, Anna Martino. It was agreed that the recommendation would be presented to the next day’s Plenary Session for consideration. Additionally, as not all the other ISO/TC-142 members were familiar with the IUVA or its current efforts, Martino suggested that a short introductory presentation on IUVA could prove beneficial to both the ISO members and IUVA. During the Plenary Session, both the recommendation and an introduction to IUVA were presented and well received. Several questions were entertained about the proposed testing protocols and some concerns expressed about how the biological aspects would be handled. The overall sense of the floor seemed positive toward the recommendation, but considering the opportunity to have a better understanding, it was agreed to prepare a more detailed presentation of the proposal to be submitted in the near future. During the session, several commented on how much they appreciated IUVA’s input and the value its UV technical expertise would bring to future deliberations. Representatives then discussed the possibility of having IUVA apply to be a liaison organization, enabling IUVA to work with ISO/ TC142 as a technical resource. ISO/TC142 already has three such liaison organizations, including the International Commission on Illumination, which also is liaison to at least 30 other ISO technical committees. The option of becoming a liaison organization was presented to the IUVA Board of Directors in early November. The board, noting that the working group is about to convert to an IUVA task force, urged that the liaison application process be incorporated into the new task force’s proposed deliverables and budget request, to be reviewed and approved by the executive committee and the board. If approved, it then can apply to ISO/TC142, as proposed. Why is this important? Having IUVA board backing on this next step is essential to being credible when its application is reviewed by the ISO/TC142 members. If then approved by ISO/TC142, IUVA will begin working within ISO, giving its new task force and IUVA insights into multiple regulatory areas impacting and being impacted by UV technologies. Just related to healthcare alone, a dozen

Table 2. ISO list of healthcare/UV-related technical committees ( Technical Committee

# Published Standards

# Standards in Process

ISO/TC106 (Dentistry)



ISO/TC142 (Cleaning equipment for air and other gases)



ISO/TC247 (Water quality)



ISO/TC172 (Optics and photonics)



ISO/TC194 (Biological and clinical evaluation of medical devices)



ISO/TC198 (Sterilization of healthcare products)



ISO/TC205 (Building environment design)



ISO/TC207 (Environmental management)



ISO/TC210 (Quality management for medical devices)



ISO/TC212 (Clinical lab testing and in vitro diagnostic test systems)



ISO/TC274 (Light and lighting)



ISO/TC304 (Healthcare organization management)



ISO technical committees that IUVA could impact have been identified (see Table 2). The IUVA Healthcare/UV Working Group extends its thanks to Huang for his invitation and acting on his belief that through cooperation ISO/TC142 and IUVA can jointly develop international standards for UV disinfection and make active efforts to promote the science, engineering and application of UV technology. Bottom line: The IUVA Healthcare/UV Working Group (task force) will be working on informing more ISO representatives about IUVA’s work in healthcare and in their respective countries. Providing IUVA information and expertise to the ISO members will help expand IUVA’s sphere of influence while enhancing overall membership. n Through the IUVA Healthcare/UV Working Group, endeavors are being made to promote the acceptance of UV disinfecting technologies as a credible, valued part of environmental management throughout the healthcare industry. In this column, the UV community will be updated on these efforts and the latest information on UV technology as it pertains to the healthcare industry. Contact: Troy Cowan,

2019 Quarter 4



UV LEDs for Food Applications from Farms to Kitchen IUVA Food and Beverage Safety Working Group Contact: Tatiana Koutchma, Ph.D. senior scientist, Agriculture and Agrifood Canada, Guelph Research and Development Center, at Tatiana. Koutchma@ Peter E. Gordon, MSEE VP of business development, Bolb Corporation, Livermore, California, at p.gordon@


he IUVA Food and Beverage Safety Working Group has announced the availability of the first edition of the monograph, Ultraviolet LED Technology for Food Applications from Farms to Kitchens.

Until now, there was not a single reference source of information or monograph available that would integrate modern fundamental and practical knowledge about UV LED light with current food applications and their challenges.

This edition, edited by Tatiana Koutchma, Ph.D., is intended to provide UV LED manufacturers; food design, production and safety engineers, technologists and scientists; government agencies and regulatory officials; as well as undergraduate and graduate students working in research, development and operations, with broad and readily accessible information on the available science, existing and potential applications to food production of UV LED technology. This book represents the most comprehensive and ambitious undertaking on the subject to date.

Therefore, as the first edition of the book in the area of food production and processing, Ultraviolet LED Technology for Food Applications from Farms to Kitchens will benefit the food industry, academia, researchers and manufacturers of equipment in this rapidly developing area of UV LED technology.

Although knowledge on aspects of UV LED applications for curing and point of use consumeroriented drinking water treatment proliferates, there is limited information about its applicability to enhance the operational efficiencies through the food production supply chain.

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As more innovations take advantage of the unique properties of near UV and UV LEDs, they will offer numerous unique approaches to safety of food production. This manuscript will focus on UV LED technology and its unique properties and advantages. It also will summarize the developments and advancement in application areas starting from preharvest, produce production and horticulture, post-harvest sanitation, post-processing storage and consumer safety, as well as point-of-use and preparation applications.

After a brief introduction of LED technology and history of its development, the first chapter will review unique advantages of LEDs for foods and economical, energy saving and sustainability aspects of LED applications for foods. The second chapter discusses the features of manufacturing technology of LED light sources from chips to LED systems in visible and UV range. The focus of chapters three and four is the review of current research and applications of LEDs in horticulture and crop production, postharvest preservation and produce storage. In chapter five, the next steps of adaptation of UV LED for safety applications by the food industry are discussed. This chapter reviews the germicidal action of UV-A, UV-B, UV-C and blue light, existing research and first reported applications of UV LEDs against foodborne pathogens at multiple wavelengths. Understanding of bacterial action spectra also is discussed to provide basis for optimization of the most effective treatment using single or wavelength combinations. Considerations for UV LED treatment of fresh produce with some reported effects on quality and nutritional attributes are included. The considerations of the current technological state and summary of established and potential applications of LEDs

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Although knowledge on aspects of UV LED applications for curing and POU consumer-oriented drinking water treatment proliferates, there is limited information about their applicability to enhance the operational efficiencies through the food production supply chain. in food production, processing and safety conclude the first edition of the book. A second edition is already in the works, tracking solution implementation. n The IUVA Food and Beverage Safety Working Group explores the latest updates on the science-based validation and commercialization of UV-C technology for plant growth stimulation or suppression, nutrition enhancement, fungicide and pesticide reduction, wash water sanitation and postharvest disinfection, as well as use for nonthermal, low UV-T beverage treatment. FOOD & BEVERAGE


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2019 Quarter 4

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ASSOCIATION NEWS IUVA Announces New President, President-Elect and Executive Operating Committee Members The International Ultraviolet Association (IUVA) is pleased to welcome Ron Hofmann, professor at the University of Toronto, as its new president, serving a two-year term. Hofmann assumes the position from Oliver Lawal, president of AquiSense, who is now the association’s Hofmann immediate past president. Jennifer Osgood, associate, project management and commercial leader, CDM Smith, has been named president-elect.


Additionally, Richard Joshi, director at atg UV Technology in the United Kingdom, is now the IUVA secretary; Ted Mao, vice president, research, at Trojan Technologies, has been added as the IUVA co-vice president of the Americas.

IUVA Forms Task Force for UV LED Disinfection Systems An IUVA task force has been formed to construct guidelines regarding UV LED water disinfection systems to enable greater clarity on system performance across the global UV LED water disinfection system market. The task force will seek input from relevant stakeholders, including academic subject matter experts and researchers, UV LED water treatment equipment manufacturers, manufacturers with research and development efforts in UV LED water treatment, UV LED device manufacturers, and validation and regulatory experts across the world. The first step in this process is determining the scope of the guidelines so they are useful but not too prescriptive across the global UV LED water disinfection system market. The task force is being led by Gordon Knight, Ph.D., IUVA task force leader and technical adviser; and Natalie Hull, Ph.D., IUVA task force chair. Those interested in contributing are asked to respond to either the leader or chair by Jan. 10, 2020. For more information, contact Gordon Knight at or Natalie Hull at Updates from the IUVA YP Committee The IUVA Young Professionals Committee is excited for the upcoming IUVA conferences. Much is planned for Americas 2020, including a YP social event, a community outreach event and a panel discussion with a group of senior-level UV professionals. The committee also is in the initial planning phases for events at ICULTA 2020 in Berlin.

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YP Spotlights The young professionals in the UV community are incredibly talented, and the YP Committee would like to spotlight the following two YPs. Brelon May received his B.S. in chemical engineering from Clarkson University in 2013 and his Ph.D. in materials science and engineering from the Ohio State University in 2019. His dissertation focused on the development of nanowirebased UV LEDs. He created the first UV LED directly on flexible metal, which could enable drastic cost reductions. He also worked on increasing efficiency of these May LEDs through improving device uniformity and unique processing schemes. His publications have been recognized as top stories by NSF Science360 News, featured in Semiconductor Today, selected as editorial picks in various peer-reviewed journals and resulted in multiple presentation awards at international conferences. May is now a postdoctoral researcher at the National Renewable Energy Laboratory, working on combining dissimilar material systems to enable substrate reuse for solar cells. Ataollah Kheyrandish is a postdoctoral research fellow and seasonal lecturer at the University of British Columbia. His experience in the UV LED industry started in 2013, and it has led to developing a standard method to characterize UV LEDs and a proposed protocol for UV dose determination of UV LEDs for water treatment applications. In addition to developing the operational protocols, he Kheyrandish created an optical simulator to estimate radiation patterns of UV LEDs. His co-authored work has been published in peer-reviewed journals, as well as UV Solutions and IUVA News. The YP Committee exists to increase interest and involvement in the IUVA and UV industry among young professionals (YPs), defined as students and professionals less than 35 years old or with less than five years of experience post-graduation in UV-related industries, government or academia. For more information or to get more involved, follow the committee on Twitter and Facebook (@IUVAYP) or email for updates on upcoming events and initiatives. n

Celebrating Dr. Bertrand Dussert The IUVA congratulates Bertrand Dussert, Ph.D., on decades of contributions to UV technology and wishes him well as he moves on to other career pursuits. A former IUVA president, Dussert has spent more than 20 years as a leader in UV technology. Dussert joined the UV industry in the mid-’90s as platform specialist for oxidative processes-commercial development at Calgon Carbon Corporation in Pittsburgh, Pennsylvania. While at Calgon, he led an initiative to expand the company’s offering into oxidation technologies/ processes. Eventually, he became the R&D senior group leader-advanced ultraviolet technologies for Calgon. This was a landmark time for UV in drinking water, as Dussert co-directed the research project – along with other IUVA members, Jim Bolton and Jennifer Clancy – which led to the discovery that UV is readily effective for the inactivation of Cryptosporidium oocysts and Giardia cysts. This work planted a seed that eventually would grow into the IUVA. More recently, Dussert held several management roles with two global leaders in the UV industry: Siemens Water Technologies (previously USFilter, then Vivendi) and Xylem, Inc. (Wedeco is a Xylem brand). He also founded Dussert Consulting, LLC, which has focused primarily on providing consulting services ranging from new product development to technology evaluation and product portfolio management for cutting-edge and cost-effective UV technologies used for municipal, industrial, commercial and residential applications. Dussert’s service to IUVA has been exemplary since he joined the IUVA Board of Directors in 2001. From 2005 to 2007, he chaired the Manufacturers’ Council and was instrumental in bringing together competitors and coordinating projects with the aim of benefiting the industry overall. From 2011 to 2012, after his term as IUVA president, he held the role of Americas hub director, promoting and implementing programs with the goal of long-term growth in North, Central and South America. He also has been a tireless ambassador for UV technologies, and IUVA specifically, while part of the American Water

Works Association (AWWA) Disinfection Committee, the AWWA Standards Council Committee for UV and the WEF Disinfection & Public Health Committee. Those who have worked with Dussert speak highly of his technical ability and praise his character and communication skills. Alex Mofidi, senior project manager at Confluence Engineering stated: “Dr. Dussert is one of the jewels of the water industry. It was because of his help that I was able to begin my investigations of UV disinfection and photolysis while I was at MWD of Southern California. His knowledge is highly robust, providing him expertise in many process applications, and I always look forward to working with him.” Steve Naylor, vice-president at ANDalyze, Inc., points out: “Bertrand has been a mentor in many ways. His natural professionalism, etiquette and work ethic are rare in today’s workforce. Despite his well-known presence in the business of water treatment, specifically ultraviolet disinfection, he makes everyone he interacts with feel important. I valued all the opportunities we had to work together and would recommend him to join any team.” Glen Holden of Evoqua Water Technologies stated: “He has a unique and expansive understanding of the UV global technologies and water disinfection markets, the competitive products, and the regional/global regulatory and market drivers. He has an excellent reputation with customers, sales channels, regulators and key influence centers. He is highly respected across global and regional markets as well as by his peers and co-workers. Andreas Kolch, a past IUVA president, added: “During my tenure as president, Dr. Dussert served as the head of the Manufacturer’s Council, where he effectively pushed things forward based on his extraordinary diplomatic talent. It is always a pleasure to work with Dr. Dussert while he keeps constantly focused on what needs to be achieved.” Well done indeed. Congratulations, Dr. Dussert! n

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UV-C Effectiveness and the ‘Canyon Wall Effect’ of Textured Healthcare Environment Surfaces


Maya Jaffe biomedical engineering student, Georgia Institute of Technology

isualize a hiker walking all day in a 100 m deep canyon beneath a cloudless sky. All morning, the floor of the canyon is shady but there is visible light reflected off the canyon walls (Figure 1a). For a while around noon, the floor of the canyon is brightly bathed in direct sunshine (Figure 1b). As the afternoon progresses, the sun drops behind the canyon ridge, and the hiker is again in the shade. Now imagine that the Earth stops rotating at 9 a.m.. The sun will never be directly above the canyon; as such, the floor of the canyon and most of the canyon walls will never be exposed directly to sunshine (Figure 1a). Further, imagine that the walls absorb all the light with no reflection. The canyon floor will be darker than the darkest night. Next, picture a slightly textured surface with a small trough/peak difference of 0.1 mm (10-4m),

akin to a human fingerprint. From the perspective of a 1.0-micron (10-6m) diameter Staphylococcus aureus, that slightly textured surface is just like the hiker in that 100 m deep canyon. Most viruses are an order of magnitude smaller than bacteria, implying that they reside in a 1,000 m deep canyon. The phenomenon that textured surfaces shadow bacteria/viruses when light is not shone directly above the surface is called the “canyon wall effect.” Healthcare surfaces such as a floor, a chair, a sitting stool, a formica countertop, an over-bed table and a stainless-steel mayo stand are all textured. Few are mirror-smooth. Thus, it is important to understand the canyon wall effect in the context of how UV lamp orientation on textured surfaces affects the kill rate of contaminants. Furthermore, most of these surfaces are oriented horizontally

Figure 1a (left). The canyon at 9 a.m. Figure 1b (right). The canyon at noon.

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and airborne bacteria are more likely to land on a horizontal rather than a vertical surface. UV disinfection in the hospital environment Contaminated surfaces in a hospital room play a significant role in increasing the risk of infection for the patient and the healthcare worker who disinfects the room. Traditional mechanisms of cleaning, such as liquid disinfectants, are inadequate and often will miss large numbers of contaminants that could cause hospital-acquired infections (HAIs). According to the CDC, in 2015, there were 687,000 HAIs in US hospitals, and 72,000 patients that had an HAI died while hospitalized. In patient rooms with inadequate cleaning, the risk for HAIs from pathogens such as Clostridium difficile (C. diff) and Staphylococcus aureus (MRSA) is greatly increased.

Figure 2. Comparison of textured vs. smooth tiles used in experiments

These pathogens can survive on surfaces for a long period of time and often are contracted by healthcare workers while disinfecting. Therefore, there is a need for more effective and no-touch systems of disinfection to reduce the spread of HAIs to patients as well as healthcare workers. This is the appeal of UV disinfection systems. Shadowing is a recognized limitation of UV disinfection and is often solely thought of at the macroscopic level with objects in the way and the need to reposition the emitter to reach both sides of a target object. Additionally, surfaces may be horizontal, vertical or anywhere in between. Many objects, such as an anesthesia machine, have multiple surfaces at various orientations. Shadowing also occurs on a microscopic level, as shown through the canyon wall effect. Currently, the vast majority of UV-C emitters in use are stationary and vertical in orientation, much like the sun stuck at 9 a.m. Unlike visible light, UV-C reflects very poorly off most surfaces, leaving the bacteria to be effectively shielded and protected like a soldier in a trench. Is the ‘canyon wall effect’ real or purely theoretical? The canyon wall effect was explored in a series of three experiments described briefly here, positioning the UV lamp at varying orientations to disinfect textured and smooth tiles.

A solution of live Staphylococcus aureus was prepared, and 10 x 10 cm plastic tiles were inoculated with identical aliquots of the solution. As shown in Figure 2, a group of tiles was mirror-smooth and another group was textured. Experiment No. 1 exposed inoculated smooth and textured tiles to identical UV-C doses with stationary lamps parallel to and above the tiles. The tiles then were cultured and no difference in kill rates on smooth vs. textured surfaces was found. This is analogous to the hiker with the sun stuck at high noon. Experiment No. 2 exposed inoculated smooth and textured tiles to the same UV-C dose and distance as experiment No. 1, but positioned the stationary lamps in a vertical orientation, perpendicular to the horizontal tiles. The tiles were cultured, and it was found that for smooth surfaces, the kill rate was >150 times greater with the lamps parallel and above than with the lamps vertical and to the side. For a textured surface, the kill rate was >500 times greater with the lamps parallel and above than with the lamps vertical and to the side. This is analogous to the hiker with the sun stuck at 9 a.m. Experiment No. 3 exposed one group of textured tiles with stationary lamps above and parallel to the tiles and a second continued on page 16

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group of textured tiles but moved the lamps across the tiles with exactly the same UV-C dose. The tiles were cultured, and it was found that motion between the UV-C source and target increased the kill rate about 2.5 times. Summary of the investigations As a result of the experiments, it was deduced that the “canyon wall effect” is real. A UV-C source oriented parallel to and passing parallel to a textured target surface is at least 1,250 times more effective than a stationary UV-C source perpendicular to the target surface at the identical UV-C dose. Analysis The “canyon wall effect” is the submillimeter combination of shadowing and of varying angles of incidence as the UV-C light strikes a textured surface. Without dissecting the dual particle and wave nature of light, suffice it to say that photons may be thought of as much smaller than bacteria and analogies of a hiker in a canyon are reasonable and instructive approximations. The orientation of the UV light makes a very significant difference in the kill rates of contaminants on surfaces in hospital rooms.

Unlike visible light, UV-C reflects very poorly off most surfaces, leaving the bacteria to be effectively shielded and protected like a soldier in a trench. Practical implications of the ‘canyon wall effect’ Understanding the “canyon wall effect” has real-world implications on the design and implementation of optimized UV disinfection devices. Like the sun traversing over a canyon, UV-C sources oriented parallel and moving parallel to the target surface can improve kill rates by a factor of more than 1,000. n This article was completed under the direction of Arthur Kreitenberg, Ph.D., co-founder and chief technology officer of Germ Falcon. Kreitenberg can be contacted at Contact: Maya Jaffe,

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NIST headquarters

Workshop on UV Disinfection Technologies and HealthcareAssociated Infections Jan. 14-15, 2020 National Institute of Standards and Technology (NIST) headquarters in Gaithersburg, Maryland This meeting, sponsored by NIST and the International Ultraviolet Association (IUVA), will examine measurement, standards, technology and data research needs to promote innovation in the effective use and implementation of UV-C technology in healthcare settings for the reduction and prevention of healthcare-associated infections (HAIs).

To learn more, visit



UV Degradation Effects in Materials – An Elementary Overview Chris Rockett

production and applications engineer, LightSources, Inc.


s ultraviolet (UV) radiation consists of photons with high energy relative to visible light, it can cause degradation in the form of physical and chemical changes in susceptible materials. The degradation effects of UV are of concern to designers and users of a wide variety of materials that are intended for use and storage outdoors and thereby exposed to sunlight. Accordingly, the published data on material degradation by UV is almost exclusively relevant to that present in sunlight at the earth’s surface, as this represents such a large economic impact.

However, UV-C, the subclass of UV radiation with wavelengths between 200 and 280 nm, is not present in terrestrial sunlight because wavelengths lower than ~300 nm are absorbed by the ozone layer in the upper atmosphere. Therefore, published data on materials’ degradation by UV-C is minimal. As a crudely demonstrative example, a search in Google Scholar for “UV degradation” results in over three million hits, while “UV-C degradation” results in only around 19,000 hits. Granted, sunlight-induced damage may be a reasonable predictor for what could be expected to occur with UV-C exposure, but the high-energy UV-C photons can have unique effects that cannot always be predicted by solar UV exposure.

18 | UVSolutions

Knowledge of the effects of UV-C exposure on various materials is useful to manufacturers and users of UV-C disinfection and photochemical equipment. The intent of this article is to give an overview of the broad classes of materials and an explanation of their susceptibility (or lack thereof) to UV-induced degradation. Such an overview must start with a basic lesson in materials science, explaining the three broad classes of materials as classified by their atomic bonding characteristics. Metals are characterized by metallic bonding, which is defined by tightly packed atoms arranged in a periodic lattice structure all sharing a “cloud” of delocalized electrons. Because of their highly mobile electrons, metals are good conductors of electricity and heat, and readily interfere with electromagnetic radiation such as light and radio waves. This explains why metals are never transparent and almost always reflect light to some degree. Metals are almost entirely unaffected by UV because of the availability of free electrons to absorb photon energy without undergoing energy transitions or bond dissociation. There is some published evidence1 of increases in the corrosion rates of metals immersed in water exposed to UV, but the results are of questionable significance,

and the metals that seem to be most susceptible are not good candidates for immersion anyway. These effects are hypothesized to be related to photoelectric effects between the surface oxide layer and the underlying metal. Suffice it to say that for nearly all applications, metals can be considered impervious to UV degradation. Ceramics are characterized primarily by ionic bonding, the attraction of positively and negatively charged ions arranged in a periodic lattice structure. Most ceramics are metal oxides, though some ceramics are nitrides, borides and carbides that exhibit strong covalent bonding. In contrast to metals, ceramic ions have tightly bound electrons, hence they have a high bond strength, withstand extreme temperatures, are usually extremely chemically inert and are strong electrical insulators. It is this high bond strength and chemical inertness that make ceramics completely unaffected by UV exposure (see Endnote). Polymers comprise a wide variety of materials that are characterized by the entanglement and interconnection of long molecules (a.k.a. polymer “chains”), which themselves exhibit covalent bonding, typically between organic (i.e., carbon-containing) constituents. Covalent bonding is the sharing of electrons between two or more atoms in order to satisfy the constituent atoms’ propensity to fill their outermost electron orbitals (i.e., a satisfied valence shell). Covalent sharing of electrons is localized (i.e., electron mobility is limited to the nearest bonding atoms), in contrast with metallic bonding, so polymers are almost always electrical insulators and poor conductors of heat. Covalent bonds between organic constituents are also relatively weak compared to metallic and ionic bonds. Therefore, most polymers are susceptible to degradation by UV-C exposure. The high-energy photons

have enough energy to promote electrons to higher energy levels and, thereby, dissociate or enable oxidation of covalent bonds. In general, polymers with carbon-carbon double bonds are more susceptible to UV-induced chemical changes. The reality is that no material exhibits any single, pure type of bonding – they all share some characteristics of other types of bonding. One material exhibiting a combination of ionic and covalent bonding that is of great importance to the UV industry is amorphous silica (SiO2), known by many names such as quartz glass, fused quartz, fused silica or simply by the common misnomer quartz. Fused silica exhibits a random arrangement of silicon and oxygen atoms lacking long-range periodicity, hence the term “amorphous” is used to describe its microstructure. Understanding the basics of chemical bonding, microstructure and electron interactions with optical radiation, it can be understood why some materials are susceptible to UV-degradation and others not. Hence, this discussion will be limited to glass and polymeric materials. UV damage mechanisms explained In glass – The dominant mechanism of UV degradation in fused silica is related to the impurities that are inevitably present in the glass, for example, metals such as iron. These metallic atoms have electrons that can be promoted to higher energy levels or freed from the atom so they are available to interfere with electromagnetic radiation, forming so-called “color-centers” and causing a reduction of UV-transparency in the glass over time, which is called solarization. There are continued on page 20

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UV DEGRADATION EFFECTS continued from page 19

also intrinsic atomic defects in silica, unrelated to impurities, such as non-bonded silicon and oxygen atoms that have some absorption in the vacuum-UV (VUV) and UV-C portion of the spectrum. These tend to be more significant in ultra-pure synthetic silica vs. naturally derived quartz glass. As a sidenote, when considering the gradual loss of UV-C output from a low-pressure mercury lamp over time, the formation of mercury oxide on the inside surface of the lamp body is a much more significant degradation effect than solarization of the glass. In polymers – Since most polymers consist of covalently bonded organic constituents, most are susceptible to damage by UV. The most basic and prevalent UV damage mechanism in polymers is called chain scission by photolysis – the breaking of long chains into shorter ones by the direct action of high-energy photons breaking the “backbone” of the molecule. This reduction in molecular weight of a polymer almost always results in a degradation of physical properties such as strength and ductility and a degradation of aesthetic properties such as color and texture. Degradation of polymers also can release by-products into the surrounding environment (e.g., outgassing), which can be problematic for a variety of reasons. Other UV-induced damage mechanisms in polymers include the formation of radicals – atoms or molecules with unpaired electrons that are highly reactive – when chemical bonds are broken. These radicals will react with other available bonds nearby and cause scission or degradation of the polymer molecules. Bonds dissociated by UV are also prone to reaction with available oxygen or water, usually at the surface of the polymer, causing the degradation mechanisms of oxidation and hydrolysis, respectively. These several degradation mechanisms have been explained separately, but, in fact, they occur in combination and often synergistically. The basic premise is always that the absorption of highenergy UV photons can promote electrons to higher energy levels and dissociate chemical bonds, causing chemical and microstructural changes in the material. Some familiar examples of UV-induced polymer degradation are the yellowing and “chalking” of PVC pipes installed outdoors, the fading of colors in signage and posters that are exposed to the sun, the chalking and embrittlement in the insulation of wires that are exposed to sunlight or in a UV-C system, and, of course, sunburn. Skin consists of polymers, specifically a protein called collagen. And, if magnified even further, it can be seen that the nuclei of all cells contain long polymer molecules called DNA. The UV-induced damage of DNA is the basis for UV disinfection.

20 | UVSolutions

The degradation effects of UV are of concern to designers and users of a wide variety of materials that are intended for use and storage outdoors and thereby exposed to sunlight. Prevention or mitigation of UV degradation Understanding the mechanisms of UV degradation gives insight into how to prevent or reduce its effects. The methods of preventing/retarding UV degradation (a.k.a. UV-stabilization) can be separated into several categories: Inherently UV-resistant polymers Some polymers withstand UV exposure better than others. The reasons for this are too complicated to elucidate here, but they are related to the above-mentioned aspects of the types of organic bonds that are present. Since C=C double bonds are particularly susceptible to UV photolysis, it makes sense to choose polymers with fewer of these bonds, therefore polyolefins such as polyethylene can be a good choice. There is a class of high-performance engineering polymers called fluoropolymers that exhibit excellent UV resistance. Common examples of fluoropolymers are polytetrafluoroethylene (PTFE), fluorinated ethylenepropylene (FEP) and polyvinylidene fluoride (PVDF). DuPont’s trademark Teflon has become a genericized name for all fluoropolymers. These polymers derive their exceptional performance from the unique characteristics and strength of the carbon-fluorine bond. In addition to having superior performance and properties such as high-temperature stability, high dielectric strength and extreme chemical inertness, fluoropolymers are exceptionally resistant to UV degradation. Accordingly, PTFE or FEP are almost always used for wire insulation on UV lamps or in UV equipment. Of course, with their high performance comes high prices – fluoropolymers are among the most expensive polymers. UV-absorbing additives (organic or inorganic) and radical scavengers Inorganic additives – As discussed earlier, inorganic compounds are rarely affected by UV exposure. Therefore, it stands to reason that adding inorganic filler to a polymer should help improve UV stability by absorbing UV photons and thereby reducing the damage to polymer bonds. The most common inorganic materials used for UV stabilization are

carbon black (soot, essentially) and oxide ceramics, such as aluminum oxide or titanium dioxide. The tradeoff with using such fillers is that they have to be included in relatively highvolume percentages and will alter the physical properties of the polymer as well as its color, though they also can impart other useful properties, such as abrasion resistance. For example, polymers filled with carbon black will necessarily be black in color. Organic additives – There are numerous categories, including antioxidants, UV absorbers, quenchers and radical scavengers. It would be beyond the scope of this article to identify and explain all these various chemicals, but they generally rely on the following principles for their UV-stabilizing effect: • UV absorption – These molecules absorb strongly in the UV spectrum and dissipate the photon energy either by turning it into heat or emitting it at longer wavelengths (fluorescence). • Radical scavenging – These molecules will preferentially react with radicals that are created by photochemical or oxidative changes, thereby neutralizing them before they can do further damage to the polymer chains. Organic additives can be added to polymers at much lower concentrations than inorganic fillers to achieve the desired UV stabilization. In fact, many such additives also assist in preventing oxidation during high-temperature processing and normal use of the polymer, so they are often added regardless of anticipated UV exposure. However, such additives are expensive, can alter properties and processability of certain polymers, and some are potentially harmful to human health. Shielding and coating A simple method of preventing UV degradation of an object is to protect it with a barrier that is impenetrable to UV photons. This could be as simple as shading with a thin layer of aluminum foil or another material that is impervious to UV. When simple shielding or shading is not possible, an alternative is to apply a coating that absorbs or reflects UV. Many paints contain UV-protecting additives like those described above. Furthermore, a paint that contains metallic particles can be a very effective UV barrier, although the polymer binders in said paint could themselves be subject to UV degradation.

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continued on page 22

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UV DEGRADATION EFFECTS continued from page 21

ISO 9001:2015 Registered

High-performance paints that are used outdoors often contain PVDF and are known for excellent gloss- and color-retention. One could potentially avoid the drawbacks of bulk polymer additives by instead using a UV-stabilizing coating on the surface of the polymer. Conclusions It is the author’s opinion that the greatest effect in prevention of UV degradation will occur as a result of following two basic principles: 1. Good design – that which minimizes the UV exposure of sensitive and critical components through the simple principle of shielding. 2. Good materials selection – choose suitable and, preferably, inherently UV-resistant materials when UV exposure cannot be avoided.

n HID/MPUV UVC & UVA - Press seal - Neck down vacuum seal

n Low Pressure UVC

- Hard Quartz, Linear, Compact & Bent - Soft Glass - Linear & Compact - Amalgam - Spot & Pellet Technology (240W-1200W) {T5 to T12 dia.}

n UVC Lamps 185 nm, 254 nm n UVB Lamps 295 nm, 310 nm, 320 nm n UVA Lamps 350 nm, 369 nm n Actinic Lamps 421 nm n Low Pressure UVC, UVB, UVA Sub Miniature CCFL’s (3.0mm to 6.0 mm dia. )

The latter principle leaves a salient question: What are suitable choices of materials for UV-exposed applications? The available literature on prevention of UV degradation is scattered and difficult to search for or often just lacking. A concise and well-organized handbook for choosing appropriate materials for UV exposure would be a valuable tool in the UV industry and beyond. It is this question that leads to a recommendation that a task force should be formed dedicated to studying and compiling the body of knowledge on UV-stable – and UV-susceptible – materials as well as performing experimentation where published knowledge is lacking. The goal of said task force would be to publish a list of approved materials shown to hold up well against UV-C degradation and perhaps a “never use” list of ones that are poorly suited for UV applications. Endnote: The author can find no published evidence of UV degradation of ceramics but would be very interested to hear of any. n Reference Exposure_to_Ultraviolet_Light Contact: Chris Rockett,

The IUVA task force model is designed to facilitate targeted activities, in lieu of traditional committees. Those interested in participating in an IUVA task force on materials, please contact Gary Cohen at

22 | UVSolutions

I_Germicidal_UVSolutions_2019_95x254 mm Vert 4th quarter .indd 1 7/15/2019 2:03:50 PM


UV Low-Pressure Lamps – Offering Many Advantages Across Multiple Areas


ltraviolet light is often used when contaminated water, air and surfaces need to be disinfected and cleaned safely. The advantages of this technology are that it is extremely economical, reliable and durable, as well as environmentally friendly. Different types of lamps can be used to generate UV light. One variation that has been established on the market for a long time is the so-called low-pressure lamp – no news, right? That is deceptive. The technology is constantly undergoing innovative developments. Not without reason, because the technology still offers the most advantages for areas such as disinfection of packaging materials, disinfection of volatile organic compounds (VOC) in the air and water, odor degradation in the air, and surface activation. Low-pressure lamps for surface treatment – packaging disinfection The high-power UV low-pressure quartz lamp offers efficiency for the disinfection of packaging materials. Up to 40% of the electrical power is used as UV-C radiation 254 nm for applications such as the disinfection of water or exhaust air. But it is also used especially in the disinfection of packaging materials, because it delivers a comparatively high, efficient UV output. Especially with filling and packaging systems, which have a constant speed of the treadmill and keep running for a long time, its use pays off. The emitters consume comparatively little energy. Thus, electricity costs can be saved.

Wiebke Breideband project managermarketing, Heraeus Noblelight GmbH

For example, a new development was presented to the market recently: The BlueLight® Hygienic System. Especially for use in filling lines for pasty, powdery and liquid foods, the system with low-pressure lamps offers the most powerful UV output of all the products on the market. Energy savings of up to continued on page 24

Typical lifetime diagram

UV output %

100 Heraeus Longlife Amalgam Lamp 90 %


Amalgam Lamp with conventional coating 70 %


Conventional Amalgam Lamp 50 %


usefull UV-Dose




4 000

8 000

12 000

16 000

lifetime hours

Long-life coating allows amalgam lamps to achieve up to 90% UV-C output.

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UV LOW-PRESSURE LAMPS continued from page 23

90% can be achieved compared to medium-pressure systems – and this with reliability in killing germs (3-log reduction). To reach this target, special high-power UV lamps were developed and tested on the reference germ Asp. Bras. This was done according to the Mechanical Engineering Industry Association (VDMA) regulations. The lamps have a service life of up to 5,000 hours. Application in the food industry The use of high-energy UV light reduces the bacterial load on packaging material surfaces by up to 99.9% to 99.999%. This significantly improves the shelf life of food such as yogurt, quark or milk. Only a few seconds of intensive, yet cold, UV light is enough to render spoilage pathogens – such as bacteria, yeast or fungi – harmless. The irradiation with UV light is – in comparison to chemical and thermal procedures – a particularly reliable, economical and, most of all, environmentally friendly and dry method. Therefore, it is suitable for the processing of organic products or milk powder. Ultraviolet light in the wavelength range of 254 nm is more energetic than the terrestrial UV light of the sun.

This particularly short-wave UV light destroys the DNA of microorganisms. Viruses are inactivated within seconds, and microorganisms such as bacteria, yeasts and fungi are killed using an environmentally friendly method without adding chemicals. For a whole range of microorganisms, the lethal dose of UV radiation is known, after which the cell can no longer maintain its metabolism and can no longer reproduce. Due to the cell wall structures, the lethal dose for the various pathogens varies. Bacteria such as salmonella and coli bacteria have a comparatively thin cell wall. They are, therefore, extremely UV-sensitive, can hardly shield the UV light and are very quickly inactivated. The lethal UV dose is an important parameter for the design of a suitable UV solution. The speed of the machine, the geometry and shape of the packaging material – e.g., cup, can or sealing film – are further criteria for the design of an effective UV disinfection system. The required UV dose is calculated from the irradiance (intensity) of the lamp multiplied by the irradiation duration. The intensity of the UV irradiation, in turn, depends on the distance between the module and the packaging material. In addition, the UV intensity of the lamp decreases with increasing operating hours. At the end of the lamp's service life, there must still be a sufficiently high UV intensity to ensure a corresponding disinfection output and the necessary lethal UV dose within the defined irradiation time. Experiments with yogurt filling, for example, have shown that cups with a depth of 150 mm can be effectively sterilized within four seconds and sealing foil sterilized within two seconds with the same intensity. UV disinfection is mainly used for food contact surfaces of packaging materials of acid-fresh milk products stored in the cold chain – such as yogurt or kefir – in order to improve their shelf life. Dairies benefit from significantly fewer returns of spoiled goods saving time, effort and money for their disposal. Features of amalgam lamps The long-life amalgam lamp is an extremely long-lasting, high-performance low-pressure lamp. It achieves up to 10 times the UV power density of classic low-pressure mercury lamps and can even be used at high ambient temperatures of up to 90°C. The lamp can be used in a wide range of applications. Amalgam lamps are also insensitive to temperature fluctuations. The unique long-life coating prevents the transmission loss of the quartz glass, which is annoying with conventional UV lamps, and keeps the UV

24 | UVSolutions

output at a continuously high level. While the UV output of an uncoated UV lamp drops by 50% after only 8,000 hours of operation, amalgam lamps with long-life coating can achieve up to 90% of the UV-C output power even after 16,000 hours of operation (see chart on page 23). The result is an almost constant disinfection effect over the entire service life of the lamp and the associated savings in energy, maintenance and service intervals. Application in air disinfection Microorganisms in the air – such as viruses, bacteria, yeasts and molds – occur particularly in highly frequented areas such as airports, medical practices, hospitals, etc. They endanger the health of people, contaminate raw materials or spoil food. UV radiation reliably reduces germs and improves hygiene and storage conditions. In order to reduce the germ level in the long term, the germcontaminated air can be disinfected in the supply air ducts. Short-wave UV radiation, especially, has a strong bactericidal continued on page 26

ZED Ozone Generator

Short-wave UV radiation is well suited for disinfection.


B cost-efficient ozone generation B 172nm excimer technology B longlife surface electrodes

Production efficiency [g/kWh]

140 120


100 80 60 40 20 0

6 5 Ozone production [g/h]


low-pressure mercury system

air ozone

ZED Excimer ZO3gen


4 3 2 1 0

ZED Ziegler Electronic Devices GmbH | Langewiesen, In den Folgen 7 | D-98693 Ilmenau | Germany phone (++49)3677 468 03 0 | fax (++49)3677 468 03 19 | |

low-pressure mercury system

ZED Excimer ZO3gen

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UV LOW-PRESSURE LAMPS continued from page 25

Lamps constructed with synthetic quartz offer maximum ozone emissions.

effect. It is absorbed by the DNA of microorganisms and destroys structure. In this way the living cells are inactivated. Gain for the customer of a professional solution A great benefit of using UV amalgam technology is the long life of the lamp, which reduces the maintenance effort – and this does not apply only to the UV lamp. The emitted radiation also keeps the air filters free of deposits. Consequently, filter replacement must also be carried out much less frequently, saving time and material costs. UV experts also can use special tools to carry out a simulation in order to precisely calculate the UV requirement and then adjust the lamp design. This enables reliable disinfection of the air volume over a wide area. Feature of ozone-generating NIQ lamps The ozone-generating vacuum UV lamps ensure photooxidation in the 185 nm wavelength range and photolyze, destroy and neutralize the molecules of fats and odors. Lamps with long-life coating can allow an efficacy time of 10,000 hours, even in high-temperature environments up to 80°C. If the fluorescent tube of the lamp is made of ozonegenerating quartz glass, vacuum ultraviolet (UVU) radiation is additionally emitted at a wavelength of 185 nm. This can

26 | UVSolutions

be increased by a suitable combination of different quartz materials and lamp technology, so that the VUV output is five times that of a classic low-pressure lamp with the same lamp dimensions. The synthetic quartz used in the construction of the lamp enables maximized 185 nm photon transmission, leading to maximized ozone emissions. Photolytically cracked molecules and ozone play an important role in reducing odors and VOCs in the air. Application in odor reduction High-energy UV photons can break down problematic compounds into environmentally friendly components. Vacuum UV radiation with a wavelength of 185 nm breaks down long-chain molecules by direct photolysis. At the same time, the UV radiation generates highly reactive free radicals like excited oxygen, ozone and OH from the surrounding air. They react with organic molecules such as fats or aromatic substances. The same process can be found in nature when pollutants are broken down in the air. UV oxidation is used, for example, to break down fats and odors in kitchen exhaust hoods, to reduce pollutants in industrial exhaust air, to clean wastewater or to clean surfaces. For example, a corresponding solution consisting of a sugar beet processor was tested. During processing, sugar beets pass through various stations starting with sugar syrup, which is crystallized to later produce white sugar. Further

processing then produces molasses. This manufacturing process, however, causes a very characteristic odor, which can be perceived over a long period of time and at a great distance – to the annoyance of the surrounding neighborhood. After detailed calculations by the specialist staff, a significant odor reduction was achieved with a UV module with 16 highperformance amalgam lamps and the optimum arrangement of the lamps in the exhaust air duct – confirmed by the local authorities and delighting neighbors. Surface activation with ozone-generating bulbs Intensive UV light treatment can prepare surfaces to make coating processes more efficient. In the UV pretreatment of surfaces, special light sources are used that can generate highradiation components in the low wavelength spectral range below 200 nm, usually with a high-energy radiation of 185 nm. A special feature is the so-called quartz reflective coating (QRC) reflector that ensures the UV radiation reaches the object to be emitted in an even more targeted and reliable manner. Application for surface activation continued on page 28

Many options, one leading concept 8.3 billion liters of clean water a day for the Big Apple

Problematic compounds can be broken down into environmentally friendly components using high-energy UV photons.

World leader in UV lamp driver technology

Nedap lamp driver technology is used in world’s most advanced drinking water and wastewater treatment plants. 

High efficiency

UL Approved

Analog and digital controls

Pre-programmed lamp characteristic settings for optimal lamp life

Nedap Unimulti: Intelligent multiple lamp and rack mounted solution for low pressure lamps 90 - 1000W

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UV Solutions

Hardened, long-life UV detectors, LED and instruments UV SiC detectors, hybrid sensors & hardened probes

UV LOW-PRESSURE LAMPS continued from page 27

High-energy UV photons are capable of breaking molecular bonds on irradiated surfaces. The open binding sites strive to achieve a chemically stable state as quickly as possible. The oxygen from the atmosphere, for example, or ozone formed by UV radiation from the surrounding oxygen, serve as reaction partners. The open bonds are saturated by atoms and radicals formed from them, and new compounds are formed on the surface. As a result of UV treatment in a normal ambient atmosphere, the formation of hydroxyl, carbonyl and/or carboxyl groups can be detected by attenuated total reflection (ATR) and X-ray photoelectron spectroscopy (XPS) measurements. This gives the surfaces a higher polar character, which affects both the contact angle and the surface energy.

High output, long life UVC LEDs

Especially in the coating and printing market, pretreatment is a real benefit because it is particularly important that the inks and varnishes can be applied in a matter of seconds to be resistant to scratches and abrasion, as well as solvents.

At the end of the lamp’s service life, there must still be a sufficiently high UV intensity to ensure a corresponding disinfection output.

Radiometers for UV & Erythemal measurement

(cell phone-based)

- Safester

UVC dose instrument – PearlLab Beam

Gain for customer if going for professional solution A high-quality UV radiation source with QRC allows a much more efficient UV output than an aluminum reflector. The reflectivity of QRC is higher at low wavelengths, and it is applied directly on the bulb. Therefore, the UV light is directly guided to the focal point without additional, potentially misted, surfaces – quartz-air, air-aluminum. Conclusion The advantages of UV technology are numerous including, but not limited to, energy and cost savings. Systems such as The BlueLight® Hygienic System offer powerful UV output, increasing the potential for maximum disinfection. n Contact: Wiebke Breideband, | 617-566-3821 | 28 | UVSolutions


Market Overview of UV Disinfection Technologies for Food Safety Applications


he first step to appreciating food safety is understanding the magnitude of the problem. Foodborne illness has a much larger reach than many people realize. Besides the obvious threat to human safety, food safety also impacts the environment and the global economy. Human health Assigning numbers to the human health aspect of food safety is sobering, to say the least. According to the Centers for Disease Control and Prevention (CDC), 48 million people suffer from food poisoning every year in the US1. Expanding out to a global scale, the World Health Organization (WHO) estimates there are 600 million cases of foodborne illness every year2, and 420,000 of those cases result in death – 30% of the victims are younger than 52. Most foodborne illnesses are diarrheal types, specifically norovirus and campylobacter2. Norovirus, specifically, is common on leafy greens, fresh fruit and some types of seafood3. Environmental impact The next level of food safety is protecting the environment where food is grown. Employing

better food safety practices not only protects human health but decreases the amount of food wasted every year. Nearly one-third of all global food goes to waste every year4, yet 69% of all fresh water goes to agriculture5. Water scarcity, defined as the demand for fresh water outweighing the fresh water resource, affects 1.2 billion people worldwide, or about 20% of the population6. Technically, there is enough fresh water to meet the world’s demands, but much of it is polluted, mismanaged or wasted6. For example, the discharge of used water – whether municipal or industrial – could be a large part of the water scarcity solution. Countries considered to be wealthy treat only 70% of their used water, while low-income countries treat less than 10%7. According to the United Nations, an estimated 80% of all used water is not treated before it is discharged to the environment7.

Molly McManus

regional sales manager, AquiSense Technologies

Kayla Doerzbacher applications engineer, AquiSense Technologies

This massive amount of unusable discharge puts additional pressure on water resources by polluting clean water sources. Consider the tragedy of Minamata City, Japan. In 1956, convulsing children were being rushed to hospitals while their ability to walk and speak simultaneously deteriorated8.

Graph 1 continued on page 30

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OVERVIEW OF UV FOR FOOD SAFETY continued from page 29

Doctors were baffled and paired with a university research group in hopes of finding the cause of what became known as Minamata Disease. Heavy metal poisoning eventually was found to be the culprit, and the source was easily identified as industrial discharge from the Chisso Corporation chemical factory8. To this day, Chisso has paid more than $86 million in restitution and worked to clean the city8. Minamata is a unique example due not only to the obvious severity of the problem, but because the responsible parties were held accountable and worked to restore their community. There are hundreds of cities like Minamata in lower-income countries that continue to operate unchecked.   Economic stability A less obvious effect of poor food safety is economic stability. According to a United States Department of Agriculture study, foodborne illnesses cost the US economy $15.6 billion every year in lost wages9. The top five illnesses are shown in the chart on page 29. Please note the chart does not represent the true cost of illness, as it does not account for healthcare costs, medication, company losses, etc. Exacerbated water scarcity has led to the full collapse of once thriving areas. The Aral Sea, shown in 1964 and 2018, once supported a vast fishing industry in Kazakhstan and Uzbekistan. Starting in 1991, the Soviet Union rerouted the Amu Darya River for irrigation and essentially cut off the water supply to the Aral Sea10. Once the fourth largest lake in the world, 80% of the sea had evaporated by 2005, and 60,000 fishing jobs had left the region10. Residents have all but abandoned the area, so now only ship graveyards remain as a testament to what was. Role of UV technology in food safety There are more than 250 known foodborne illnesses1. Of these, none of them is 100% resistant to UV-C disinfection but they require differing UV doses. UV-C disinfection is currently utilized in a variety of food surface applications: surfaces, brines, sugar syrups, alternatives to pasteurization in milk processing and water processing. While a great technology, traditional, gas-discharge UV disinfection technology isn’t without limitations. Traditional systems require a lengthy warm-up time before they can disinfect properly. This not only delays the treatment process but requires the system to consume energy prior to treatment. Conversely, a UV-C LED system has a nearly instantaneous start-up, so treatment is faster and more energy efficient. Being a solid-state technology, LEDs are more robust than their gas-discharge counterparts and can withstand

30 | UVSolutions

A comparison of the Aral Sea in 196410 and 2018.11

Photo from the Kazakhstan Travel and Tourism blog12

multiple power cycles without their aging being accelerated. Traditional technologies can only handle about five power cycles a day before their lifetime starts to deteriorate. This, combined with a long warm-up time, eliminates the option of using traditional systems for intermittent applications while LED systems are perfectly suited for them. Traditional systems also heat liquid as they treat it, while LED technology has decoupled light and heat so light shines from the front of an LED while heat exits through the back of the LED. This simple change significantly reduces the time and cost associated with maintaining a UV system, as fouling is significantly reduced when heat is removed. UV-C LED systems also are immune to fluid temperature. Traditional systems do not operate properly if the fluid is too hot or too cold, while LEDs give optimal performance regardless of temperature. This, combined with LEDs not heating fluid during treatment, enables UV disinfection to be used in applications where heat is not wanted – such as frozen food applications. Current state of UV-C LED technology UV-C LED technology has been rapidly improving over the last 20 years. Graph 2 on page 31 shows how the output of

Graph 2 (left) and Graph 3 (right)

commercially available UV-C LEDs has steadily increased over the last two decades. The number of UV-C LED manufacturers also has increased. UV-C LED technology also is following Haitz’s Law, so the price per mW is decreasing while the output is increasing. Graph 3 illustrates the falling prices.

Case studies The combination of increased output with decreasing prices allows UV-C LED systems to be used in a variety of applications. The following four processes currently utilize UV-C LED solutions. continued on page 32


2008 First UV LED Reactor Prototype

First UV LED Beta System Pe


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First UV LED Commercial Product

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First UV LED NSF 55-2019 System ™



First UV LED PoE System

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Over a Decade of Firsts | | +1.859.869.4700

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OVERVIEW OF UV FOR FOOD SAFETY continued from page 31



I: Conveyor Disinfection Problem: Pathogens on conveyor belt can spread quickly to all fruit being processed. Goals: Disinfect belt while in use. Key Design Parameters: System must be mounted under the conveyor belt, produce little heat and allow for intermittent and continuous operation. Solution: UV LED array II: Commercial Steam Oven Problem: Pathogens in low temperature steam ovens can



quickly contaminate the oven. Goals: Disinfect inlet water as to prevent pathogens being introduced into the system. Key Design Parameters: Solution must achieve a 4-log target pathogen reduction, support intermittent flow operation and be retrofittable into a small space in a warm environment. Solution: PearlAqua Micro III: Juice Dispenser Problem: Pathogens in juice dispenser process can contaminate product. Goals: Disinfect the juice at the point of use. Key Design Parameters: System must achieve a 4-log target pathogen reduction, support on-demand flow patterns and be retrofittable. Solution: PearlAqua Micro IV: Refrigerator Air Circulation Problem: Bacteria spread from one food to another. Goal: Disinfect the air without heating the air. Key Design Parameters: System must not obstruct storage space, produce low amounts of heat and allow intermittent operation. Solution: Air filter paired with UV LED array The point Food safety should never be taken lightly. It is imperative to remain diligent in efforts to more effectively grow and protect food. UV-C LED technology allows a new generation of disinfection systems to be used in ways previously inaccessible to UV technology. Failure to embrace these new technologies will not only hinder food safety but prevent the industry from moving forward. n For the full list of references, view this article at Contact: Molly McManus,; Kayla Doerzbacher,

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The Quest for UV Treatment Validation


o set the stage, it is perhaps helpful to review some of the basic science – indeed, very basic. This article looks at the issue of UV treatment from an engineering and project management perspective, not from a microbiology or food science background. The author has had the privilege to work with some of the best scientists in this field as, together, they have honed their efforts to test and validate UV treatment processes.

As interest in UV treatment grows ... there is a need for more accessible information about UV.

Chris Hartman

founder and president, Headwater As interest in UV treatment grows – and more and Food Hub

more individuals and businesses seek better and more healthful, efficient and affordable means to pasteurize juices and other beverages – there is a need for more accessible information about UV. Specifically, information that would provide a window into the current understanding of the effectiveness of UV treatment technology across a wide range of beverages. Additionally, how to best validate a process that utilizes UV treatment technology as part of a food safety plan would be immensely helpful. Background Thermal energy moves reliably through materials, perhaps uniquely to each material, but reliably. With some mixing and a certain amount of time, one can safely assume that all the material has reached a certain temperature. Pathogens, yeasts and molds reliably die at certain temperatures. Documenting that a material was at a certain temperature – above that in which pathogens survive – for a certain amount of time is a reassuring way to validate the food safety process engaged. continued on page 34

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UV TREATMENT VALIDATION continued from page 33

Likewise, pressure almost immediately moves through a fluid material, consistently and quickly dispersing, and reliably delivering its impact throughout. Pathogens, yeasts and molds reliably die at certain pressures. Documenting that a material was at a certain pressure (above that in which pathogens survive) for a certain amount of time also is a reassuring way to validate the food safety process engaged.

Meanwhile, members of the founding FPE engineering team were working with UV light in the microchip manufacturing process. During a conversation, over cider and doughnuts, the idea to use UV as an alternative to thermal pasteurization was hatched. Design and prototyping began immediately. Years were spent running trials on evolving UV treatment technology.

UV, alternatively, is governed as it moves into materials, if it moves into them at all. The level of UV transmittance within any given material has physical and chemical variables at play. Absorption, shadowing and quenching are all possible ways in which UV light waves are halted or otherwise made ineffective. The opaqueness of a liquid to normal, visible light is a good starting point to imagine UV transmittance, but the correlation is limited. Clear water, for example, which is UV-transparent, is effectively treated using UV. A juice made of beet, kale or cucumber is another story.

Delivering the appropriate dose of UV to the apple cider, requiring assurance that the appropriate UV exposure was delivered throughout the cider, was the initial design and engineering challenge. Innovation and experimentation led to a process that combined thin film flow and turbulence to create adequate UV exposure and effective pathogen reduction in the cider. However, the second design and engineering challenge became the more complicated issue to overcome: How to monitor, maintain and record that UV dose so as to have a process that could be confirmed and, thus, validated. It was the development of sophisticated sensors, monitoring software and control systems – coupled with thousands of experimental trials – that led to the first FDA-approved UV treatment process for the pasteurization of apple cider.

It is possible to show the ways in which UV light waves deactivate pathogens, yeasts and mold – not the same as the kill achieved with heat or pressure, but rather mutation of the DNA, blocking viable reproduction. However, it cannot be confidently assumed that UV light waves are contacting pathogens, yeasts and mold throughout a liquid, as can be done with temperature and pressure. Herein lies the challenge of UV treatment in general and of UV treatment validation specifically. That, as it were, is the stage. Next is the quest. UV for pasteurization In collaboration with Randy Worobo, Ph.D., at Cornell University, work has been done for more than 20 years testing UV as an effective means with which to pasteurize beverages. This work began with apple cider. In 1998, after an E. coli contamination, the FDA began to mandate that apple cider must either be pasteurized or a warning label – with a skull and crossbones-type message – must be placed on the container. Thermal pasteurization was not only an expensive capital investment for small- and mid-sized cider mills to consider, it was widely accepted that heating the cider up to a pasteurizing temperature would diminish the flavor and texture.

The scientific path to validation followed the usual scientific method. Many trials were run using UV to kill a surrogate pathogen. Using live pathogens for the initial phase of frequent experimentation is costly and slow. However, once the 5-log reduction of those surrogate pathogens was achieved – the gold standard in effective treatment – a correlation study was required to verify that the surrogate pathogen behaved the same way live pathogens would during the UV treatment process in that juice. Although it was likely that they would, the responsible scientist, of course, would want to see that validated. The initial experimentation and validation studies were done on a “lab machine” – a version of equipment that would never be used in a commercial setting. Thus, it was acceptable to run live pathogens through it. The correlation study was important in that way too, because – although the necessary pathogen reduction using UV treatment equipment was shown – each specific machine built for commercial use had to be verified, validating that it behaved as expected in reducing pathogens. Since this machine was intended for commercial use, that validation had to be done with the surrogate pathogens.

The validation trial had three steps: Initial experimentation to show that UV treatment effectively created a 5-log reduction in surrogate pathogens in the lab machine; a correlation study to show that live pathogens behaved in the same manner; and a final validation study using surrogate pathogens within the machine designed and built for commercial use. This is still the case for apple cider. Despite the hundreds of machines built and validated, the scientific and regulatory confidence does not exist to validate these machines based on consistent design and build standards. The validation report after a round of treatment is not simply that a certain temperature or pressure was sustained for a certain amount of time; it is a more complicated calculation that connects UV transmittance and dwell time, and documents microjoules per square centimeter of UV energy. Each CiderSure processing unit, the UV treatment technology specific to the apple cider industry, is individually validated with apple cider that has been spiked with the E. coli surrogate. The process outcome is subsequently analyzed to confirm that the desired 5-log reduction is achieved. Although it is possible to monitor UV transmittance and control flow to assure the proper dwell time – the associated UV dose and effective treatment overall – the “black box” nature of this type of process monitoring does not instill trust within the regulatory community. To build that trust, each machine must show that it works to reduce pathogens in the specific juice it is certified to treat before it can be commissioned in the field. Indeed, after a certain amount of time – every three years – the machine must be revalidated to make sure it is still performing as intended. Looking ahead In the last several years there has been an explosion of interest in alternatives to thermal pasteurization. The cold-pressed juice industry, and the general movement in the beverage industry for more “clean label” approaches to production, has pushed the innovation around UV’s utilization beyond apple cider. High-pressure pasteurization is a common choice alternative, but it is extremely expensive and is not glass bottle friendly. The initial design and engineering challenge around successfully using UV to treat apple cider has evolved.

Vegetable and fruit juice blends, nut milks and other consumable liquids – some with only a fraction of the UV transmittance level of apple cider – are being successfully treated with UV. The validation process for these treatment plans, however, is the same as for apple cider. Initial experimentation to see if surrogate pathogen deactivation can be achieved, live pathogen correlation studies and then actual validation of the machine intended for commercial use with the specific juice intended for production – using a surrogate pathogen – is still the standard process. The validation is on that machine, with that juice. Any change in recipe or desire to produce additional juices leads to new validation requirements. And, after a certain amount of time, this all must be repeated. As UV’s utility continues to be developed as an alternative form of pasteurization, the process of validation will also continue to develop. Scientific rigor and confidence in a food safety process will necessarily lead the way. There is still clearly work to be done to understand what variables are at play that can be monitored and reported on that give confidence that a UV system is appropriately and successfully working. Headwater Food Hub technology looks at real-time UV transmittance and flow rate and calculates UV dosage accordingly. Other technologies look at viscosity, fluid dynamics and calculate surface exposure probabilities. Everyone can point to UV dosage levels that successfully deactivate pathogens, yeasts and mold. Everyone can also see the unique nature of that dose, unique to specific juices and machine configurations. Conclusion Right now, process validation requires replicating the exact process, on actual pathogens, and confirming its effectiveness. As deeper understanding develops on the ways and means of UV treatment, there will be an important, ongoing quest for a more efficient and overarching process for validation. Like all good quests, there is some uncertainty on the outcome. However, the beverage manufacturing industry and the scientific community are sending some of their best people on that quest. n Contact: Chris Hartman,


UV Lamp Breakage: Investigation and Response Jennifer Osgood, PE, PMP, BCEE

associate, CDM Smith Contact: osgoodjl@


hile UV reactor lamp breakage occurrence is uncommon, if lamp breakage does occur, utilities need to have a plan in place and understand the consequences. Conducting a mercury release analysis provides insight into the measurable public health risk associated with lamp breakage. Observations and insight associated with UV reactor lamp breakage are covered within this article. Lamp breakage may occur outside a UV reactor. Typically, this type of incident is associated with replacing lamps. Mercury is in a liquid phase. The primary risk posed is to workers that may come in contact with the spilled mercury. Mercury vacuums are available for clean-up. However, proper procedures and training are necessary to safely contain the mercury. Lamp breakage also may occur while the UV reactor is online. Typically, this type of incident occurs while water is flowing through the reactor. Online lamp breakages occur due to any one of the following reasons: Incorrectly manufactured sleeves or faulty design, wiper mechanism issues, software error leading to an overheating, power surge, debris, burst main downstream of the plant that resulted in a significant increase in flow rate through the system, control logic fault caused the flow control valve to open unexpectedly quickly, or excessive rate of flow increase resulted in an exceedance of the maximum flow rating through a single UV reactor. When the reactor is online, mercury is in a vapor state due to the high temperatures. Mercury maximum contaminant limits (MCL) are currently set at a concentration of 2 Âľg/L in the US and 1 Âľg/L in Canada.

Conducting a mercury release analysis provides insight into the measurable public health risk associated with lamp breakage.

Mercury release calculations determine the magnitude of mercury plume concentration in finished water for different lamp breakage scenarios. These calculations should be based on mercury mass in the vapor phase. Mercury mass in liquid and vapor phase in operating UV lamps depends on lamp type and operating pressure and temperature. Mercury mass in the vapor phase may be treated as proprietary information by the UV reactor manufacturer. If so, one may need to rely on ideal gas law values based on pressure and temperature to calculate. Lamp breakage scenarios associated with mercury release calculations should consider the appropriate post UV configuration, such as a pipeline release scenario: UV systems discharge directly into the distribution system, i.e., no finished water storage buffer between the UV system and first customer; or a clearwell release scenario: UV systems followed by a finished water clearwell or storage reservoir prior to first customer. There also are several lamp breakage scenarios: one lamp, one reactor; all lamps, one reactor; and all lamps, all in-service reactors. The UV knowledge base (2010) outlines a step-by-step response plan for online lamp breakage. Bold font indicates medium-pressure (MP) activities only. Non-bold font indicates MP and low-pressure, high-output (LPHO) activities 1. Close valve sufficiently downstream of reactor to contain initial mercury release (LPHOcontainment of the initial releases likely not needed because mercury concentrations are orders of magnitude below the MCL). 2. Close upstream and downstream reactor isolation valves.

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3. Divert water contained in the conduit to waste, MERSORBÂŽ (or equal mercury absorbent) treatment or storage. 4. Sample conduit water before and after treatment as needed. 5. Flush conduit and bring back online. 6. Pump contaminated water in reactor to a MERSORBÂŽ column for treatment. 7. Sample reactor water before and after treatment. 8. Clean up reactor. Remove quartz shards, liquid mercury and lamp parts. 9. Inspect other sleeves. Replace broken and damaged sleeves and lamps. 10. Flush reactor with dilute acid solution HCl followed by water 11. Verify mercury concentrations in standing water are acceptable. 12. Bring reactor back online. A site-specific UV lamp breakage response plan should describe operating procedures, sample locations, frequency of sampling, if any treatment and disposal is needed, and proper clean-up and disposal of the mercury, based on industry best practices. Sampling locations downstream of the reactor should be selected based on the concentration profiles predicted using a model.

Due to the larger mercury concentration in vapor phase, MP UV reactor lamp breakage poses higher risk when compared to LPHO reactor lamp breakage. For a pipeline mercury release scenario, flow appears to have minimal impact on mercury dilution concentrations and plume displacement increases at lower flows (i.e., longer detention time). For a clearwell mercury release scenario, the peak mercury concentrations are typically similar in baffled and unbaffled clearwells; however, the plume displacement profile is extended in unbaffled clearwells. Clearwell volume dilution calculations, adjusted by baffle factor, may underestimate the peak mercury concentrations and length of the plume displacement. Computational fluid dynamic model or tracer test results provide a more accurate prediction of downstream mercury dilution impacts. n Operators Corner focuses on the practical aspects and lessons learned by the owners, operators and providers of UV technology. Authors for these articles are solicited from individuals operating full-scale UV facilities around the globe. Those interested in submitting an applied article please contact

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INDUSTRY NEWS ICULTA 2020 Comes to Berlin ICULTA 2020 is the second in a row of conferences on ultraviolet light emitting diodes (UV LEDs) and their multiple applications. It brings together experts from science and industry to meet and discuss related issues. The conference gets its unique character by covering the entire value chain: It will highlight state-of-the-art UV LED technology, integration of UV LEDs into modules and systems, and focus on their application in industry and research. Opportunities and challenges with respect to applications in water treatment, advanced oxidation processes, air and surface disinfection will be discussed, as well as emerging applications in the areas of medicine, life sciences, curing, sensing, horticulture, analytics and other fields. ICULTA 2020 will be April 26-29, 2020, at the MELIÃ Hotel in Berlin, Germany. For more information, visit

First UV-C LED Product Certified to NSF/ANSI 55-2019 Standard AquiSense Technologies, Erlanger, Kentucky, claimed the world’s first NSF Component Certification for the newly updated NSF/ANSI 55-2019 standard for its PearlAqua Micro range. The PearlAqua Micro was certified by NSF International in compliance with the new NSF/ANSI 55 Standard for Material Safety and Structural Integrity. The NSF/ANSI 55-2019 standard has recently been updated to address the unique technical differences of LED technology compared to traditional mercury gas-discharge lamp technology. Following very shortly will be microbiological performance certification by NSF. This will provide additional verification to the already completed third-party microbiological validation completed on the PearlAqua Micro range, showing supplemental bacterial treatment of drinking water supplies. This provides a strong final barrier and “last-mile” protection to many applications. For more information, visit UV Pure Exhibits Hallett at WEFTEC UV Pure, Toronto, Canada, exhibited the new Hallett, which was launched earlier this year, while exhibiting at WEFTEC, an annual industry event showcasing technologies and innovations related to water quality. The 2019 edition was in

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Have a new product ready to launch? A website redesign? New additions to staff? Send press releases to late September in Chicago, Illinois. UV Pure received positive feedback regarding the various new features and technology updates in the new Hallett, including: the new Hallett 1000, UV Pure’s largest model yet, which can handle flows up to 100 US gpm; improved dual UV sensor array design with quadsensor models available; better temperature management with built-in purge valve and available lamp heaters; color touchscreen; and remote start. For more information, visit 2020 IWA Water Congress to Report on Sustainable Goals The 2020 IWA World Water Congress & Exhibition will be Oct. 18-23, 2020, in Copenhagen, Denmark. It will bring together core water sector groups, such as those focused on urban water and urban water services, as well as participants from industry and agriculture, architects and urban planners, soil and groundwater experts and hydrologists, social scientists, the ICT sector, the financial sector and others. This edition of the World Water Congress & Exhibition will report on the water sector progress on the Sustainable Development Goals (SDGs). The emphasis will be on SDG6, which is dedicated to water and sanitation. The event also will highlight and explore the interwoven relation of water with all 17 of the global SDGs. Participants will analyze, discuss and highlight solutions in high-level summits, case study presentations and examples of implementation and cooperation driving the fulfilment of the SDGs. For more information, visit Water and Wastewater Pipes Market Study: Steel Pipes Projected for Significant Sales Hike According to a study, the water and wastewater pipes market is projected to grow at ~5% CAGR in the forecast period. Increasing investments for the enhancement of wastewater treatment infrastructure in developing countries are expected to propel the growth of the water and wastewater pipes market. According to the analysis, rising demand for water supply and distribution, as well as sewage and drainage management

in urban and rural centers, along with the increasing demand for uninterrupted supply of water is driving the growth of the water treatment sector. This, in turn, is set to directly contribute to the growth of the water and wastewater pipes market. Furthermore, stringent rules and regulations implemented by governments for industrial wastewater treatment, recycling and reuse are contributing to the growth of the water and wastewater pipes market. For more information, visit

systems to disinfecting the water that astronauts drink on the International Space Station. For more information, visit Singapore Water Convention to Focus on Innovation The Water Convention 2020 is the technology pillar in the Singapore International Water Week program. The Water Convention 2020 will focus on strategy, innovation and ready solutions for potable water delivery, wastewater management, and water quality and health. Discussions and debates over strategic approaches and innovations that are necessary to sustain the resiliency and livability of cities for the future remain as key focus areas. The Water Convention technical program serves as a platform for sharing knowledge, engaging discussions and debates among water leaders and practitioners through high quality presentations showcasing sustainable technological solutions, processes and management strategies that address current and emerging water issues. For more information, visit

American Air & Water®, Inc. Partners with Don Ryan Center American Air & Water®, Inc., of Hilton Head Island, South Carolina, has partnered with the Don Ryan Center for Innovation (DRCI) in Bluffton, South Carolina, to help launch its patented lighting and disinfection product, PrismUV™. American Air & Water has been specializing in the research, development, marketing and sales of germicidal air, surface and water disinfection systems for nearly 20 years, and with its new PrismUV™ product will now move into the arena of smart light technology. For more information, visit UV-C LED Technology Plays Increasing Role in Key Aerospace Projects AquiSense Technologies, based in Erlanger, Kentucky, has participated in 10 aerospace projects. In 2015 AquiSense was selected to participate in BIOWYSE, a Horizon 2020 project dedicated to designing and testing a water monitoring and treatment system for next-generation manned space stations. Since then, several other aerospace projects have looked for water treatment technology from AquiSense. These projects include product design and hardware supply to both private space companies, such as Bigelow Aerospace, Thales Alenia Space Italia, KBR Wyle, Aero Sekur and various NASA groups, including those at the Jet Propulsion Laboratory, Johnson Space Center and Marshall Space Flight Center. These projects range from keeping growth systems clean in space-bound greenhouses to decreasing the maintenance burden from nuisance biofilm formation in enclosed

Enaqua Installs Noncontact UV System at St. George Water Reclamation Facility The St. George Water Reclamation Facility (SGWRF) in St. George, Utah, has operated two UV systems for approximately 15 to 20 years. Due to age, serviceability and availability of parts for the existing UV systems, St. George planned on replacing them as part of upgrades to its facility. Enaqua provided a self-contained UV reactor in an enclosed pilot trailer and a technical protocol for the pilot testing. Using the protocol, SGWRF staff performed a threemonth pilot study. The pilot study was done in summer because the existing UV systems experience biofouling from algae and Bryozoa during summer months. The successful pilot testing assured SGWRF staff that Enaqua’s noncontact UV system would be an excellent candidate to replace existing UV systems. For more information, visit n 2019 Quarter 4

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UV/H2O2 Treatment: The Ultimate Solution for the Degradation of Pyrazole


n July 9, 2015, Water Supply Company Limburg (WML) noticed the presence of a high concentration of an unknown compound in the water of the river Meuse1.

Bram J. Martijn

team managerresearch and development, PWN Water Supply Company

Joop C. Kruithof

Ph.D., Wetsus European Center of Excellence for Sustainable Water/ Technology

KWR Water Cycle Research Institute showed that the unknown pollutant, LC Aqua-033, was pyrazole, present in a concentration higher than the signal/reporting value of the Dutch drinking water regulation of 1 µg/L. The emission of pyrazole in the river Meuse was caused by a malfunctioning wastewater treatment plant at the industrial site of Chemelot in Geleen, Netherlands. One of the companies at this complex produces acrylonitrile, which causes significant emissions of pyrazole. Pyrazole can be removed through biological wastewater treatment. Malfunctions at the plant led to pyrazole being discharged in the Meuse for several months in high concentrations. In August 2015, the presence of pyrazole also was observed in the river Rhine in even higher concentrations. The presence of pyrazole in the Rhine caused a water intake stop from the Lek Canal (river Rhine water), serving water supply companies PWN and Waternet2. This time, the presence of pyrazole was caused by the wastewater discharge of an acrylonitrile production plant located at Chempark Dornagen, Cologne, Germany. Figure 1. Chromatogram showing the presence of No toxicological data for pyrazole were unknown compound LC Aqua-033 available3. A provisional guideline of 15 µg/L was set. Additionally, a water quality standard of 3 µg/L was set for the presence of pyrazole in surface water used for the production of drinking water4. Presence of pyrazole in Dutch drinking water sources Since August 2015, the Dutch water supply companies have developed a pyrazole monitoring program. The results are summarized in Figure 2. In August 2015, the pyrazole concentration in the Ijssel Lake amounted to 4 µg/L. The pyrazole concentration decreased as a function of time and became below a concentration of 0.5 µg/L since November 2018. Initially the pyrazole concentration in Ijssel Lake exceeded the signal value of 1 µg/L and even the water quality standard of 3 µg/L. Since November 2018, neither guideline value has been exceeded. The concentration in the Lek Canal followed the same trends. The concentrations in the Afgedamde Maas were significantly lower.

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Figure 3. Experimental flow diagram and schematic collimated beam apparatus

Figure 2. Pyrazole concentration in river Meuse, Rhine and Ijssel Lake from August 2015 to August 2019

Pyrazole removal/degradation by drinking water treatment processes The concentration of pyrazole can be lowered by removal processes such as granular activated carbon (GAC) filtration, reverse osmosis (RO), and by degradation processes such as ozonation and advanced oxidation by O3/H2O2 or UV/H2O2 treatment. By GAC filtration, the pyrazole removal amounted 16 to 35%5. Reverse osmosis caused a pyrazole removal of 65 to 80%6. For pyrazole concentrations initially reported, these processes will not be able to lower the pyrazole concentration below the signal value of 1 µg/L. The effect of ozonation proved to be very low (<10%). By far the best results were achieved by advanced oxidation by O3/H2O2/UV and UV/H2O2 treatment. A degradation of more than 90% was achieved, lowering the pyrazole concentration below the signal value7. Advanced oxidation seems to be the silver bullet for pyrazole degradation. Therefore, the degradation of pyrazole by both LP and MP UV/H2O2 treatment will be pursued in this article. Experimental set-up and procedure Two collimated beam apparatuses housing a low-pressure UV lamp and a medium-pressure UV lamp were used. The UV fluence rate was determined by two radiometers. One radiometer was equipped to measure the fluence rate of monochromatic light from the LP UV lamp, the other to measure the fluence rate of polychromatic light from the MP UV lamp. Sample volumes of 55 mL were irradiated during a calculated time to achieve the required fluence rate using Bolton’s spreadsheet for UV dose calculation8. A control sample was stirred without irradiation for the time required to reach the highest UV fluence. After the irradiation time, catalase was added to the samples to quench the excess H2O2. Pyrazole was quantified using UPLC-Triple Quadrupole Mass Spectrometry.

Reagents and water types Analytical grade pyrazole (98%) was purchased and 30% w/w H2O2 was diluted to concentrations of 3 g/L and 30 g/L. Calculated volumes of these stock solutions were added to the water samples to obtain concentrations of 6 mg/L and 50 mg/L H2O2 respectively. A stock solution of bovine liver catalase (activity 12,800 U/mg) 39,800 U/mL was prepared. From this solution 10 µL was added to the 55 mL samples to quench H2O2. MilliQ water was produced using a Millipore Advantage A10 Water Purification system with Q-GardT1 + continued on page 42

UV Expert Consulting: Karl Platzer • Oliver Lawal • Fred van Lierop • Michael Santelli • Henry Kozlowski • Dr. Jim Bolton • Walter Blumenthal Validated

CFD Simulation to identify opportunities for improvement

We are a multidisciplinary team of UV experts each with an average of 20 years of experience. Our main fields of expertise: traditional UV Lights & future LED solutions. 3rd party UV-Lamp-System Evaluation = Trust for the OEM, the lamp producer and the end-user Karl Platzer - Consulting M&A Business Development LLC.

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PYRAZOLE DEGRADATION continued from page 41

Figure 4. Panel A, left: Molar absorption coefficient of pyrazole, hydrogen peroxide and nitrate. Panel B, right: Spectral emittance of an LP and MP lamp.

Quantum TEX cartridge with a pore size of 0.22 Âľm. Pretreated Ijssel Lake water treated by coagulation, sedimentation and rapid sand filtration was collected from water treatment plant Princess Juliana. The nitrate concentration of the water was 10 mg/L, the HCO3- and CO32- concentrations were 151 and 0 mg/L respectively. Samples with 40 Âľg/L pyrazole spiked in milliQ and pretreated Ijssel Lake water were prepared by Het Water Laboratorium, The Netherlands. This pyrazole concentration was chosen to enable measurement of 3-log degradation based on the limit of quantification of the analytical method. Results UV absorption spectra The molar absorption coefficients of pyrazole, hydrogen peroxide and nitrate as a function of the wavelengths are presented in Figure 4, Panel A. The absorption spectrum of pyrazole shows that pyrazole can be degraded by MP UV photolysis and not by LP UV photolysis, because, at a wavelength of 254 nm emitted by a LP UV lamp, the molar absorption of pyrazole is negligible. Pretreated Ijssel Lake water absorbs more photons emitted by the MP UV lamp compared to the absorption of photons emitted by the LP UV lamp. This has a strong impact on the competition for photons between the water matrix and H2O2 for MP and LP UV lamps. Among the water matrix constituents, besides natural organic matter (NOM), nitrate plays an

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Figure 5. Pyrazole degredation as a function of the irradiation time in milliQ by LP and MP UV lamps without and with dosage of 6 and 50 mg/L H2O2

Figure 6. Pyrazole degredation as a function of the irradiation time in pretreated Ijssel Lake water by LP and MP UV lamps without and with a dosage of 6 and 50 mg/L H2O2

important role. The NOM and the 10 mg/L nitrate present in pretreated Ijssel Lake water create a competition for photons, especially in the wavelength range of 200 to 240 nm. In pretreated Ijssel Lake water, the production of hydroxyl radicals is hampered by the competition for photons between H2O2 and nitrate because in the wavelength range 200 to 240 nm the molar absorption coefficient of nitrate is much higher than of H2O2. Therefore, in pretreated Ijssel Lake water, pyrazole degradation will be significantly slower than in milliQ.

The reaction time amounted to 700 seconds for MP UV and 3,000 seconds for LP UV/H2O2 treatment. The time-based reaction rate constants for the pyrazole degradation are presented in Table 1.

Pyrazole degradation as a function of the reaction time The degradation of pyrazole by UV photolysis and UV/ H2O2 treatment with LP and MP UV lamps for H2O2 dosages of 6 and 50 mg/L is presented as a function of the irradiation time in milliQ (Figure 5) and pretreated Ijssel Lake water (Figure 6).

Pyrazole degradation as a function of the UV fluence The LP UV lamp power output is much lower than the MP UV lamp power output, causing a much longer reaction time for the LP UV experiments. For a better comparison, the pyrazole degradation is also plotted as a function of the UV fluence. The degradation of pyrazole as a function of the UV fluence by UV photolysis and by UV/H2O2 treatment with LP UV and MP UV for H2O2 doses of 6 and 50 mg/L is presented in milliQ (Figure 7) and pretreated Ijssel Lake water (Figure 8).

By LP UV photolysis, no pyrazole degradation was observed in milliQ, contrary to MP UV photolysis by which a 3-log degradation was observed after 1,100 seconds. By both LP and MP UV/H2O2 treatment, pyrazole was degraded very effectively. By MP UV/H2O2 treatment, pyrazole was degraded for 3-log after a reaction time of 150 seconds for both H2O2 doses. By LP UV/H2O2 treatment, the reaction time to reach 3-log degradation was much longer: 1,800 seconds for 6 mg/L H2O2 and 1,200 seconds for 50 mg/L H2O2.

The table confirms the absence of degradation by LP photolysis and a significantly faster conversion by MP photolysis. Compared to the conversion in milliQ, the degradation in pretreated Ijssel Lake water is more than one order of magnitude lower.

continued on page 44

Compared to the degradation in milliQ, the reaction times in pretreated Ijssel Lake water were much longer. A 3-log degradation was achieved for an H2O2 dose of 50 mg/L only. Table 1. Time-based pseudo first order reaction rate constants (k x 10-4s-1) for pyrazole degradation in milliQ and pretreated Ijssel Lake water



0 mg/L H2O2

6 mg/L H2O2

50 mg/L H2O2





Pretreated Ijssel Lake water








Pretreated Ijssel Lake water




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PYRAZOLE DEGRADATION continued from page 43

Once again, by LP UV photolysis, no pyrazole degradation was observed in milliQ, while by MP UV photolysis a 2-log degradation was achieved at a UV fluence of 1,200 mJ/cm2. By both LP and MP UV/H2O2 treatment, pyrazole was degraded effectively, although the UV fluences for LP UV/ H2O2 treatment were significantly higher. By LP UV/H2O2 treatment 3-log degradation was achieved for a UV fluence of 150 and 300 mJ/cm2 for 6 mg/L H2O2 and 50 mg/L H2O2 respectively. For MP UV/H2O2 treatment these UV fluences amounted to 100 and 150 mJ/cm2 respectively. Figure 7. Pyrazole degradation as a function of the UV fluence in milliQ by LP and MP UV lamps without and with a dosage of 6 and 50 mg/L H2O2

Figure 8. Pyrazole degradation as a function of the fluence in pretreated Ijssel Lake water by LP and MP UV lamp without and with a dosage of 6 and 50 mg/L H2O2

Figure 9. Radical exposure ROH,UV (Ms cm2 mJ-1) for pyrazole degradation in milliQ and pretreated Ijssel Lake water by LP UVand MP UV/H2O2 treatment

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Compared to the degradation in milliQ, the UV fluences in pretreated Ijssel Lake water were significantly higher. A 3-log degradation was once again achieved only for an H2O2 dose of 50 mg/L. The required UV fluence was higher for MP UV/ H2O2 treatment than for LP UV/H2O2 treatment. The UV fluence amounted to 400 mJ/cm2 for LP UV/H2O2 treatment and 600 mJ/cm2 for MP UV/ H2O2 treatment. The fluence rate-based reaction rate constants for the pyrazole degradation are presented in Table 2. Once again, the absence of pyrazole degradation by LP UV photolysis was confirmed, while a significant degradation of pyrazole by MP UV photolysis was observed. In milliQ for MP UV/ H2O2 treatment, the fluence-based rate constants were larger than the LP UV/H2O2-based rate constants. The differences were 34% and 19% for H2O2 doses of 6 and 50 mg/L respectively. The same trend was observed in pretreated Ijssel Lake water for a H2O2 dose of 6 mg/L. However, for a H2O2 dose of 50 mg/L, the fluence-base rate constant was larger applying LP UV lamps. Impact of the water matrix on radical exposure To study the effect of the water matrix on LP UV and MP UV/H2O2 treatment, the OH radical exposure for the observed pyrazole degradation was calculated (see Figure 9)9. In milliQ, the ROH,UV values for MP UV/H2O2 treatment were larger than for LP UV/H2O2 treatment for both H2O2 doses. For pretreated Ijssel Lake water, the ROH,UV values were roughly 1,5-log unit lower than in milliQ water. However, in pretreated Ijssel Lake water, ROH,UV values were larger for LP UV/H2O2 treatment for both H2O2 dosages.

0 mg/L H2O2

6 mg/L H2O2

50 mg/L H2O2




In summary, it can be concluded that the required pyrazole degradation can be achieved by advanced oxidation. Both MP and LP UV/H2O2 treatment can achieve the required degradation under economically feasible conditions. MP UV treatment is slightly more attractive by the contribution from UV photolysis. Also, in extensive pretreated water MP UV/ H2O2 treatment is more favorable. In heavily polluted water, LP UV/H2O2 treatment may be more attractive. n

Table 2. Fluence-based pseudo first order reaction rate constants (k x 10-4/cm2/mJ) for pyrazole degradation in milliQ and pretreated Ijssel Lake water

milliQ LP UV




Acknowledgements: The authors thank Suyash Mandal for his work at PWNT for his master thesis on which this paper is based.





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Contact: Bram J. Martijn,; Joop C. Kruithof,

Pretreated Ijssel Lake water


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Pretreated Ijssel Lake water



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UV Solutions 2019 Quarter 4  

Official Publication of the International Ultraviolet Association

UV Solutions 2019 Quarter 4  

Official Publication of the International Ultraviolet Association