UV Solutions 2019 Quarter 3

2019 Quarter 3

Practical Approaches to AOP Systems Roles for LEDs in Healthcare UV Technology for CSOs Disinfection of Drinking Water

Official Publication of the International Ultraviolet Association

Save the date!

2020 IUVA Americas Conference March 8-11 • Disney Coronado Springs Resort in Orlando, Florida The focus of this conference is to present the recent advancements in technology and research addressing the environmental, health and treatment process challenges of today, as well as to discuss the current trends in UV regulations and new applications.

• In addition to expanded networking opportunities and workshops, IUVA will have two conference tracks and a special pavilion on the exhibit floor.

• Expect the latest information on multiple applications, including developing areas, such as healthcare, and food and beverage safety, in addition to the various applications within water and a focus on UV LEDs. • The call for presentation abstracts is open until Oct. 11. Those interested in presenting may visit iuva.org/AC20-Call-For-Abstracts.

To learn more, visit iuva.org/2020-Americas-Conference.

Co-located with the 2020 RadTech UV+EB Technology Expo and Conference

contents

2019 Quarter 3

Featured articles of a Reactor Containing UV LEDs for the Disinfection 17 Validation of Municipal Drinking Water The time for UV-C LEDs for municipal water treatment is coming fast. To fully embrace this new technology, existing standards must be updated.

by Olivier Autin, lead research scientist, Typhon Treatment Systems James R. Bolton, president, Bolton Photosciences

26 How to Address CSO Events with UV Technology

As frequent, heavy rainfall becomes more common, flooded sewer events will continue to be a concern for communities that have a combined sewer system.

by Patrick Bollman, P.E., UV product specialist, Evoqua Water Technologies

LED Irradiation for the Inactivation of Biofilm-bound 30 UV-C Pseudomonas Aeruginosa Bacteria With the potential to harbor dangerous pathogens, bacteria found in biofilms is a growing concern for the food and healthcare industries.

by Kyle D. Rauch, Stephanie Gora, Carolina Ontiveros and Graham Gagnon, Centre for Water Resource Studies, Dalhousie University, Halifax, NS, Canada

36 What is Going On with the Grade A Pasteurized Milk Ordinance?

The Grade A Pasteurized Milk Ordinance (PMO) is written around a specific UV technology and ignores recognized science – an issue that needs to be addressed given the potential market and public health implications.

by Harold Wright, chief technologist-UV disinfection, Carollo Engineers

is There No Standard Unit Similar to Lighting Products 39 Why for Radiant Output of UV Lamps?

Among the many applications and UV technologies, the UV wavelengths of interest are all over the “UV map.”

by R.W. Stowe, UV applications engineering consultant, Heraeus Noblelight America LLC

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Practical Information on Sizing and Design Approaches for UV AOP Systems Various factors must be considered when selecting a UV AOP system for any given application.

by Nathan Moore, Ph.D. candidate, University of Toronto Erin Mackey, project manager and technical specialist, water and reuse, Brown and Caldwell, Inc. Kati Bell, managing director of water strategy, Brown and Caldwell, Inc.

49 Critical Roles for Germicidal LEDs in Healthcare Delivery Facilities

Germicidal UV-C light is increasingly being embraced as an effective method for preventing the spread of hospital pathogens.

by Peter Gordon, VP of business development, Bolb Corporation

Departments

Executive Operating Committee Oliver Lawal President Jutta Eggers, Ph.D. Ian Mayor-Smith EMEA Co-Vice Presidents

Kumiko Oguma, Ph.D. Asia Vice President

Chip Blatchley, Ph.D. Americas Co-Vice President

Gary Hunter, P.E., Treasurer Jennifer Osgood, P.E., PMP, BCEE Secretary Ron Hofmann, Ph.D. President-Elect

Katherine Bell Immediate Past President

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

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Association News Operators Corner Application Highlight UV Industry News Calendar/Ad Index

Editorial Board

Editor-in-Chief

Jim Bolton

Jim Malley editorinchief@iuva.org

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 Atlantium Technologies

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 www.uvsolutionsmag.com.

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

785.271.5801

Managing Editor Brittany Willes

Advertising/Sales Janet Dunnichay

2019 Quarter 3

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FROM THE IUVA PRESIDENT

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Oliver Lawal IUVA president / president and CEO, AquiSense Technologies Contact: oliver.lawal@ aquisense.com 859.869.4700

am coming to the end of my two-year term as IUVA president: Time flies when you’re having fun!

I’m honored to be handing over the reins to the very capable hands of Professor Ron Hofmann, University of Toronto. Shortly, we will announce a new president-elect, and thus, the cycle continues.

These changes inevitably create new opportunities within the executive operating committee and board of directors, and I would urge those of you with an interest to step forward and become involved in shaping the direction of the organization. Our organization remains very active on many fronts: events, committees/task forces and this wonderfully evolving publication, UV Solutions.

The Young Professionals, under the direction of Nathan Moore, is a vibrant group seeking to establish connections across all organization types represented within IUVA. If you’re younger than 35, then don’t be shy – get involved.

We have several events coming up around the globe, including the UV Workshop as part of the EPA Small Systems Workshop in Cincinnati, Ohio, in September and the IUVA Workshop in Bangkok, Thailand, in November.

Our task force model continues to expand with efforts continuing in the area of Hospital Acquired Infections and Food & Beverage applications. Newer areas related to LED technology, MP lamp measurement and materials compatibility are establishing themselves. A major new partnership with the National Water Research Institute (NWRI) is expected to commence before the end of this year. We continue to encourage all those willing to contribute to come forward and dedicate your time and expertise.

I am humbled to have had the opportunity to serve in this capacity over the past two years. I have witnessed firsthand the passion shared by so many capable people with a common goal to advance “the sciences, engineering and applications of ultraviolet technologies to enhance the quality of human life and to protect the environment.” I am grateful for the strong support of Gary Cohen, Mickey Fortune and James Kerich through all the organization’s administrative issues. I look forward to continued involvement and thank you all for your contributions.

FROM THE EDITOR-IN-CHIEF

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ith the support of IUVA and Peterson Publications, we are happy to present to you this issue of UV Solutions – Innovations for Industry, Public Health and the Environment. We are excited to introduce a new magazine feature – Operators Corner – focusing on challenges faced and lessons learned from owners and operators of UV technology systems. The inaugural Operators Corner focuses on UV technology in water reuse applications.

Jim Malley UV Solutions editor-in-chief / University of New Hampshire

In this issue, readers also will find articles related to LEDs in healthcare and a full-scale LED application case study. Be sure not to miss the updates for the active IUVA committees, including Food and Beverage and Healthcare. We also include regular IUVA Association News updates and will routinely devote part of that space to news from the Young Professionals of UV technology. This issue also includes an article focused on a pasteurized milk ordinance to underscore the importance of activities, discussions and peer review in the food and beverage area.

UV Solutions brings a broad array of information and applications in the field of UV technology to one concise quarterly publication that is worth your time. Please read and enjoy! If you would like to submit technical content for consideration of publication, please submit papers to editorinchief@iuva.org. We also welcome your feedback and suggestions as part of our goal of continuously improving UV Solutions.

Readers, please note that the information provided in UV Solutions 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 that does not necessarily reflect, nor is there any implied or expressed guarantee of its content by, IUVA.

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FOCUS ON FOOD AND BEVERAGE SAFETY

Ultraviolet Light Explores New Science for Food and Beverage

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IUVA Food and Beverage Safety Working Group

Contact: Tatiana Koutchma, Ph.D. Agriculture Agri-Food Canada, at Tatiana.

Koutchma@ agr.gc.ca

ompared to water and wastewater treatments, air disinfection and surface decontamination, the application of UV light for food and beverage products is a relatively new and challenging area. Effective UV treatment for food applications requires alternative approaches to those normally employed for water or air treatment due to absorption and scattering or surface effects that are significantly higher than that of water or air.

practical knowledge about UV light with current food applications and challenges, evaluation of UV systems performance, recommendations for systems design, selection of commercial UV sources, and validation and outlooks for future successful applications. Furthermore, only a few books are available about UV radiation and its industrial applications in water and air treatment, sanitation or any other general aspects that can be related to food applications.

UV light can be effective in treating UV transparent or semi-transparent liquids, such as clarified juices and soft drinks, but is less effective in treating turbid liquids with particulates (e.g., apple cider and orange juice) where UV light is strongly absorbed, scattered or reflected. A systematic approach to evaluating UV light technology as an alternative pasteurization, shelf life extension or disinfection method entails consideration of the properties and composition of the food product to be treated; characteristics and correct choice of the UV radiation source; microbial efficiency against pathogenic and spoilage organisms; effects on quality, enzymes and nutrients content; modeling; and commercial and economical aspects, including process validation and regulatory approvals.

Ultraviolet Light in Food Technology: Principles and Applications now has an updated, second edition that will greatly benefit the food industry, UV technology providers, academia and researchers in the area of nonthermal technologies. The goal of the second amended edition is to integrate fundamental and applied knowledge of UV light generation and propagation in foods and to bring together new available information on UV light processing by summarizing findings of the published studies with commercial applications and regulatory approvals. In addition, it analyzes the concerns and challenges associated with applications of UV light for food in terms of safety and regulatory acceptance.

Recent research on advances in science and engineering of UV light technology have demonstrated that UV treatments hold considerable promise in food processing as an alternative to traditional thermal treatment for liquid products such as juices and soft drinks or ingredients such as water, sugar syrups, whey protein and raw eggs.

It also is promising for pre-processing of raw materials or dry ingredients, post-processing of ready-to-eat meals, shelf life extension method of fresh produce and dry sanitation method in food plants and facilities.

In spite of numerous reports, reviews and manuscripts that are available on particular aspects of UV applications for foods, no recent monograph is available that integrates modern fundamental and

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The book covers technology aspects associated mainly with continuous UV light. This includes numerous technology developments from the last 10 years since the first edition has been published.

This edition is intended to provide food engineers, technologists, scientists, and undergraduate and graduate students working in research, development and operations with broad updated and readily accessible information on the science and applications of UV light technology. This book represents the most comprehensive and ambitious undertaking about UV technology for foods that exists to date.

To access the second edition of Ultraviolet Light in Food Technology: Principles and Applications, visit www.crcpress.com/Ultraviolet-Light-in-FoodTechnology-Principles-and-Applications/ Koutchma/p/book/9781138081420. n uvsolutionsmag.com

FOCUS ON HEALTHCARE/UV DISINFECTION

Expanding Outreach to Other Organizations Interested in UV

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ince the last issue, there has been a tremendous amount of outreach activity focused on expanding the visibility and credibility of UV healthcare technologies and efficacy standards.

In June, the Association for Professionals in Infection Control and Epidemiology (APIC)1 held its annual conference in Philadelphia, Pennsylvania, where 23 exhibitors displayed healthcare disinfection UV devices. With such a significant presence on the exhibition floor, one would think there would be comparable visibility in the presentations and poster sessions, but there was not. The only presentation was by Dr. John Boyce, and even though it was held at 6 a.m., more than 250 people came to hear him talk on “Latest Environmental Cleaning and Disinfection Practices,” where the benefits and issues with latest UV technologies were highlighted.

It is believed the significant attendance and the number of exhibitors demonstrate the viability and interest in UV, enough to warrant increased podium time in future conferences.

Also in June, Sam Guzman and Dr. Richard Martinello presented an overview of IUVA and uvsolutionsmag.com

the Healthcare Working Group’s efforts to two American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)2 Technical Committees, TC 9.6 Healthcare Facilities and TC 2.9 Ultraviolet Air and Surface Treatment at the ASHRAE Annual Conference held in Kansas City, Kansas. The Healthcare/UV Working Group efforts resonated with both groups, and both were amenable to discussing joint efforts. In TC 2.9, further joint discussions were put to a vote, and there was unanimous agreement to do so. Thanks to that and ongoing efforts by Guzman, discussions are being held on collaborations with ASHRAE on developing efficacy standards through ASHRAE’s director of technology and senior manager of standards.

IUVA Healthcare/UV Working Group

Contact: Troy Cowan director, Vision Based Consulting, at troy@ visionbasedconsulting.us

More recently, the Healthcare Working Group has been approached by representatives of the Internaional Organization for Standardization (ISO)3 Technical Committee TC142 “Cleaning equipment for air and other gases” to discuss possible collaboration with them, as well. The group has been invited to attend ISO’s 15th annual meeting in Atlanta, Georgia, Sept. 23-26; Options are being explored to present an overview to them continued on page 10

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FOCUS ON HEALTHCARE/UV DISINFECTION continued from page 9

as well and explore collaboration options. A pre-conference get-acquainted meeting is scheduled for Sept. 20 to help understand how ISO could fit into the picture at this early stage.

New challenges for efficacy standards and their application Every day, new UV products are being marketed as disinfecting devices, some even touted as being able to sterilize (i.e., able to kill all organisms exposed to the device). Many are LED-based and utilize wavelengths other than 254 nm (the Hg-based underpinning for most “k” value and fluence value tables now in use to estimate likely pathogen reductions). This greatly complicates estimating their efficacy using normal “k” value calculations.

As an example: Sunuv S1 Factory Directly Mobile Sterilizer/ Phone Sanitizer/UV Sterilizer Box for Jewelry/Key4 (395 nm/280 nm dual light source; reports 99.99% E. coli kill).

Many products are handheld and hand-activated, meaning the distance from the treated surface will vary, and the amount of time the surface is treated also will vary. Examples of these include: • Room and Hospital UV Sterilization 254 nm Ozone

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Free UV Sanitizer5 (a portable, tabletop batterypowered device) • Horicreate UV-C Micro Instant Sterilizer, Portable UV Sterilizer6 (a handheld, battery-powered device) • Clean Trust Household Disinfection UV Sterilizer Device7 (handheld device for sterilizing glasses, toothbrushes, etc.)

Other products purport to use UV to disinfect soft and/or irregular surfaces to fairly high levels (sometimes described as sterilizing). Examples include: • Good Performance 254 nm UV light sterilizer for herbal spices powder8 • Family Health Ultraviolet Light Germ Bacteria UV Killer Glove Underwear Sterilizer and Dryer9 • Patent CE Certification High Technology Clothes Hanger with UV Sterilizer for Home Use10 While it will be challenging, a standard can be developed that would enable the standardized testing and performance measurement of these and similar devices to ensure that they perform as advertised. Such a standard would not only be effective in helping the industry self-regulate, but also aid federal and other governmental organizations in developing credible procurement specifications (e.g., for use uvsolutionsmag.com

in the Veterans Affairs hospital system) and in ferreting out potentially fraudulent and misleading practices (e.g., as done by the Federal Trade Commission (FTC).

Healthcare conference The Healthcare Working Group is planning to hold a conference Jan. 14-15, 2020, at the National Institute of Standards and Technology (NIST)11 headquarters in Gaithersburg, Maryland.

This conference will continue discussions started at the Sept.

27 workshop at the Yale School of Medicine. The goal of this conference will be to promote: • innovation in the effective use of UV-C and other light spectra for disinfection in healthcare settings and its implementation, • safe healthcare and facilitate industry ability to support safe healthcare, and • productive discussions, networking, research and business relationships related to the use of light technologies for disinfection in healthcare settings.

light and challenges impacting broader implementation of light technologies for disinfection in healthcare. All will lead to a proposed release of a draft efficacy standard for UV disinfection devices. n Special thanks to these contributing authors • Dr. Richard Martinello, associate professor of medicine (infectious diseases) and of pediatrics, Yale School of Medicine • Dr. Cameron Miller, research chemist, National Institute of Standards and Technology • Sam Guzman, regional manager, American Ultraviolet 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.

For full list of references, www.uvsolutionsmag.com.

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ASSOCIATION NEWS Meet the IUVA YP Committee The IUVA Young Professionals (YP) Committee works to increase interest and involvement in the IUVA and UV industry among YPs (students and professionals younger than 35 or with less than five years of experience post-graduation in UV-related industry) and to allow YPs to actively contribute to the IUVA. Natalie Hull, co-chair (internal) – guides the committee in accomplishing its vision and objectives.

Hull’s group focuses on understanding and optimizing engineered water treatment (including UV disinfection) for sustainable control of water microbiomes.

Nathan Moore, co-chair (external) – liaises with the IUVA executive operating committee. He is working toward a doctorate in civil engineering at the University of Toronto studying the by-products of UV-based AOPs. Dana Pousty, conference coordinator – leads YP contributions and initiatives at IUVA conferences. Her research focuses on improving the efficiency of novel UV LED systems.

Dan Spicer, communications and engagement coordinator – maintains committee email and social media accounts. He works with OEM customers throughout the Americas and Oceania on UV-C lamp related projects for water and surface disinfection applications.

Solutions quarterly. He is working toward his Ph.D. in civil engineering at Dalhousie with a focus on UV treatment in domestic wastewaters.

Ran Yin, strategic growth coordinator – plans and executes strategic initiatives to grow the IUVA YP community. His research focuses on developing UV-based AOPs for advanced water treatment.

Molly McManus, IUVA YP representative for North American conferences – supports the IUVA conference team and coordinates YP events. Her work has taken her to six countries for projects varying from water fountains to space exploration.

The IUVA YP committee was made a voting member at the IUVA board meeting at the 2019 World Congress in Sydney.

The committee is very excited to have the opportunity to officially represent the YPs at future board meetings.

Those looking to become more involved with YPs or who have ideas/concerns to present to the board should contact the committee.

To stay up to date on YP initiatives, make sure to follow the committee on social media (@IUVAYP) or email (iuvayp@ iuva.org) by scanning the QR codes below.

Kyle Rauch, technical communications coordinator – drafts content related to the IUVA YPs for UV

IUVA Workshop a Success At the request of the Region 6 office of the EPA, the Association of State Drinking Water Administrators (ASDWA) helped plan a workshop in Dallas, Texas, last May focusing on issues of interest to Region 6 states and water systems, such as basic water chemistry, disinfection, DBPs and lead.

ASDWA invited the IUVA Education Committee to organize a workshop with two coordinated sessions. The morning session was presented by Chip Blatchley of Purdue University and was organized to include subsessions that provided an introduction and summary of the law of photochemistry, followed by a subsession in which the principles of UV disinfection kinetics and the concept of UV dose were summarized. The morning session concluded with a summary of the steps involved in reactor validation. The afternoon session was titled “Reviewing UV Validation Test

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Reports” and was prepared and conducted by Christopher Schulz of CDM Smith. Schulz guided the attendees through the logistics behind reactor validation, organization of the validation process and report preparation and also allowed them to spend time examining real reports, generously provided by Calgon and WEDECO. Some 20 attendees, representing drinking water primacy agencies from Texas and Oklahoma, had the opportunity to become familiar and comfortable with UV and UV validation reports. Coordination and participation by ASDWA in this event was key, as they are the national organization that supports state regulatory agencies.

IUVA once again will offer a workshop with ASDWA at the upcoming 16th Annual EPA Drinking Water Workshop at the Duke Energy Convention Center. For more information, visit www.epa.gov/water-research/16th-annual-epa-drinkingwater-workshop. uvsolutionsmag.com

Celebrating Dr. Linda Gowman Dr. Linda Gowman (IUVA president 2007-2009) has spent the past 20 years as a leader in UV technology and research, setting a high bar for integrity and showing tremendous leadership on many important projects and services. Dr. Gowman received her undergraduate training in mechanical engineering, specializing in biophysics, graduating with an MSc before completing a mechanical engineering doctorate. Dr. Gowman is a longtime professional engineer with years of management/executive engineering leadership and business experience, most of it while at Trojan Technologies, Inc., in London, Ontario, Canada.

Dr. Gowman served as a strong president for the IUVA during a time of transition when international financial markets had all but collapsed. She worked tirelessly to ensure that the public statements made on behalf of the UV technology field were both rigorously based on sound science and free of the subtle biases that creep into such public statements in support of a particular UV manufacturer. She set a very high bar for IUVA in this regard, and the fact that she did so while serving as Trojan’s chief technology officer was observed with respect by many in the industry and served to strengthen the credibility of the IUVA. There is no better way to fully appreciate the respect, admiration and achievements of Dr. Gowman than through comments provided by colleagues and longtime associates.

“Dr. Gowman was one whose passion for uncompromising standards attracted global interest for new ways of tackling disinfection options as well as dealing with complex micro pollutants. She never wavered in her resolve to keep raising the bar as time demanded. For that, and her cheerful professionalism, we will always remain grateful.” – Hank Vander Laan, founder and past president, Trojan Technologies “Whether working with colleagues or delivering a presentation before those who could benefit from new insights to a problem and a better definition of its solution, Dr. Gowman succeeds in conveying the understanding needed to produce results with the highest possible impact. Many have benefited from her mobilizing style of leadership.” – Dr. Bill Cairns, past chief scientist, Trojan Technologies uvsolutionsmag.com

“My first of many professional interactions with Dr. Gowman was in 2002-2003 during the multi-party UV validation of equipment for the US large-scale 180 MGD DBO (the first of its kind) contract for the UV disinfection facility at Cedar Water Treatment Plant in Seattle, Washington. This was a highprofile project with no margin for error.

Thanks in part to Dr. Gowman, that project solidified a drinking water UV market in the US and continues excellent performance after 15 years. I feel very fortunate to call her colleague, mentor and friend.” – Dr. Jim Malley, founding president of IUVA and professor of civil and environmental engineering, University of New Hampshire “In working with Dr. Gowman for more than two decades, she has always been a person of singular integrity and courage, believing that we can aspire to whatever we put our hands and minds to with diligence, insight, professionalism and graciousness.

She has always shown concern and investment in the people around her, acting as a mentor, encourager and sponsor.” – Wes From, vice president, research and development, Trojan Technologies “Dr. Gowman is a visionary leader and holistic thinker with unwavering integrity. Her sense of humor and genuine care of people have touched many people and made it fun working and spending time with her.” – Dr. Ted Mao, chief technology officer, Trojan Technologies “Dr. Gowman has been an inspiring leader to me and many of my colleagues. Her encouragement was constant, and I am extremely grateful I could name her as one of my career coaches during my tenure at Trojan.” – Dr. Domenico Santoro, senior research scientist, Trojan Technologies “Dr. Gowman has capably served the industry for many years, always working to ensure that the science of UV treatment was rigorously researched and that the capabilities and the boundaries of UV treatment were clearly articulated.” – Marv DeVries, past president, Trojan Technologies Congratulations to Dr. Gowman and best wishes for retirement! n 2019 Quarter 3

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OPERATORS CORNER

Water Reuse Systems Professor James P. Malley, Jr., Ph.D.

UV Solutions editor-in-chief Contact: jim.malley@ unh.edu

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hen looking at UV facilities that achieve advanced oxidation through the addition of hydrogen peroxide and UV doses in the range of 1,000 to 10,000 mJ/cm2, three important aspects must be considered. These facilities are selected, designed, installed and operated to meet water reuse criteria. These criteria often include maximizing viral inactivation (e.g., 6+ log removal) while consistently achieving greater than 1.2-log reduction of NDMA and 1,4-dioxane as the surrogates for contaminants of emerging concern.

UV transmittance monitoring and dose control There is a wide array of commercially available online ultraviolet transmittance (UVT) monitors.

Monitoring the percent UVT is a key aspect of optimizing the operation of UV technologies in most applications. In water reuse, since the delivered UV dose is significant, the proper selection, maintenance and operation of the UVT monitors can translate to significant power and cost savings. It is important for a facility to understand what its online UVT monitor is measuring, how accurately and how precisely. It is just as important to understand how the UVT monitoring input signal affects the overall dosage control algorithm of the UV equipment and/or the facilities’ supervisory control and data acquisition (SCADA) system.

Working with five full-scale water reuse facilities has revealed the following points of interest. All were able to follow manufacturer guidelines for proper maintenance and calibration of the UVT monitors.

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In two facilities, the range of the UVT monitor and how the SCADA system responded were not well understood and not optimized. Specifically, the UVT monitor would often result in ramping up the system to full UV lamp power when it reached a low-end set point – such as 85% UVT. This was in spite of the pilot testing and design of the advanced oxidation process (AOP) system to allow for a minimum UVT of 75%.

A related observation was that four of the five facilities were not outfitted with the latest available dosage control software.

In two cases, an upgrade was not possible without major technology changes. Collectively, attention to these details saved some facilities an average of 15% in annual UV power use, and one facility achieved a 35% savings.

Hydrogen peroxide dosage and control When UV AOPs involving hydrogen peroxide addition are used, there is a balancing act between UV dose (power use) and hydrogen peroxide concentration added. The goal is to provide enough radical oxidation to achieve the desired treatment goals.

Most systems find that the hydrogen peroxide aspects have a larger impact on annual costs and warrant optimization.

Optimization can be achieved by ensuring accurate methods and monitoring of the hydrogen peroxide concentration

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There is a wide array of commercially available online ultraviolet transmittance (UVT) monitors. Monitoring the percent UVT is a key aspect of optimizing the operation of UV technologies in most applications. after addition and after the UV unit. Three facilities noted significant batch-to-batch variation in the hydrogen peroxide bulk chemical purchased and fed into the system. Four of the five facilities had initial problems selecting a sensitive, precise and accurate method of measuring the hydrogen peroxide in the water.

One facility noted that the analytical method precision varied for samples taken before and after the UV unit. Specifically, the influent samples had more variability than the effluent samples. continued on page 16

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OPERATORS CORNER continued from page 15

All facilities employed online hydrogen peroxide monitors capable of measuring in the 0 to 200 mg/L range initially.

Two facilities have tried three different monitors each and continue to look at new advances. All systems noted the monitors needed frequent calibration and maintenance for optimum dose control. Most systems typically saw values of 20 mg/L or less, with average value being 7.2 mg/L. Three of the five facilities did not rely upon the meter readings alone and used them solely as a check to ensure a minimum dose achieved. One facility fitted its system with monitors that were more sensitive to the low range of hydrogen peroxide of 0.05 to 20 mg/L and relied upon those readings to adjust dose.

Three of the four facilities were looking at better ways of dosing hydrogen peroxide. One was using its historical data mining to adjust dosing to a condition in which the hydrogen peroxide concentration after the UV unit was within a 95% confidence interval of the hydrogen peroxide concentration before the UV unit.

Another was having success operating at a ratio of hydrogen peroxide concentration after the UV unit to the hydrogen

peroxide concentration before the UV unit of 0.85 +/- 0.05 based on its historical data. One facility reported a 20% cost savings in hydrogen peroxide after more careful attention to dose monitoring and control.

UV lamp health and breakage Due to the increased UV dose needed for AOPs in water reuse, most of the facilities have a relatively large number of UV lamps per design flows. Each of the facilities has experienced a limited and acceptable number of difficulties with lamps (e.g., short life, failure to ignite, electrode arcing problems) and with ballasts (mostly cooling issues and not received in working order), but most were corrected by working closely with the equipment providers. All facilities encourage users to perform frequent lamp and sleeve checks.

It was somewhat surprising, upon reviewing the data, that all the facilities experienced online lamp breakage for a variety of reasons most consistent with those identified in the 2006 EPA Ultraviolet Disinfection Guidance Manual (UVDGM).

The number of lamp breaks per hours of lamp usage and population served were still well below initial estimates made in 2006 EPA UVDGM. Though lamp breaks are rare, they do occur and can be serious. Facility managers and operators need to know what to do for offline and online lamp breaks.

All UV facilities should have approved standard operating procedures in place for lamp breakage.

Operators must be trained on how to safely and thoroughly treat and remove the mercury from the system or, as a minimum, be able to safely isolate the reactor and contain the mercury until qualified hazardous materials cleanup personnel arrive.

By looking at the available data and studies conducted for mercury, mercury vapor is easily absorbed first through the lungs, secondly through the dermal layer and then poorly through the gastrointestinal tract.

Therefore, the greatest risk is to the operators and technicians working in the drinking water treatment facility and cleaning up the lamp break, and not the consumers drinking the treated water. n Operators Corner focuses on the practical aspects and lessons learned by the owners, providers and operators 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 jim.malley@unh.edu.

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DRINKING WATER DISINFECTION

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ight-emitting diodes (LEDs) have attracted a great deal of attention in the UV world. The advantages of UV LEDs over traditional mercury lamps are now well established. However, until recently, their low output power has limited them to small-scale, point-of-use applications.

Typhon Treatment Systems was founded in 2014 with the sole purpose of developing UV LED technologies to treat higher, continuous flow rates of water to suit municipal and industrial scale applications. At the time many felt this was too early, but the rapid development of UV LEDs over the last four years has enabled Typhon to validate its first system, the BIO-310, in July 2018. This article presents the results of the validation of the BIO-310 LED UV reactor (Figure 1).

The reactor was validated according to the US Environmental Protection Agency Ultraviolet Disinfection Guidance Manual (UVDGM 2006) with some adaptations from the more recent paper “Innovative Approaches for Validation of Ultraviolet Disinfection Reactors for Drinking Water Systems” (Wright 2018).

FEATURED ARTICLE

Validation of a Reactor Containing UV LEDs for the Disinfection of Municipal Drinking Water

Olivier Autin lead research scientist, Typhon Treatment Systems

James R. Bolton

president, Bolton Photosciences

The reactor The reactor design was optimized using optical modeling to maximize the light transmission into the flow cell.

The reactor is composed of a Ø300 mm x 1.2 m-long quartz tube surrounded by an array of 1,000 lighting units, each comprising an LED light source and reflector that directs the light to an optimized focal point, resulting in a near uniform irradiance through the full cross-section of the reactor (Figure 2).

Twenty lighting units form a ring around the perimeter, with 50 rings along the length of the reactor delivering an even UV dose distribution. LG Innotek UV-C LEDs emitting a peak wavelength at 275 nm continued on page 18

Figure 1 (left). The Typhon BIO-310 UV Reactor.

Figure 2 (right). Light penetration through the reactor for near uniform dose distribution.

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DRINKING WATER DISINFECTION continued from page 17

and an optical power of 100 mW at 350 mA were used for the validation. Although the wall plug efficiency of UV-C LEDs is still low in comparison to conventional LP mercury lamp systems, the much higher reactor efficiency compensates to improve the overall efficiency of the system. The choice of supplier was based on selecting LEDs with the highest output power available at the time of validation.

where BRED is the RED bias factor; Bpoly is the polychromatic bias factor; and Uval is the uncertainty of validation expressed as a percentage of the RED.

The methodology The UVDGM validation method was followed, using the calculated UV dose approach. The validation testing was conducted at Cumwhinton Water Treatment Works in the north of England, with the challenge water taken after conventional filtration (i.e., coagulation/clarification/rapid gravity filtration). The water had a UV-T 254 of around 97% and was not chlorinated.

Uval = (UIN2 + UDR2 + US2)0.5 (3)

SuperHume was used as the UV absorber in order to adjust the UV-T of the water, and MS2 was used as the challenge microorganism. Twenty-seven conditions were tested, consisting of permutations of the following conditions: • Flow rate: 80, 125 and 250 m3/h • UV-T: 90%, 95% and 98% UV-T (at 275 nm) • Output power: 34%, 74% and 100% of the full output power

Master equation The calculated UV dose approach in the UVDGM involves determining the RED for a series of test conditions using a challenge microorganism (MS2 was used in this study) and then fitting to a master equation. For this study, a master equation derived from one in the “Innovative Approaches” paper (Wright 2018) was selected, as it appeared to best fit the data:

Calculated UV dose approach The US EPA Long-term Two Enhanced Surface Water Treatment Regulations (LT2ESWTR 2006) focuses on the treatment of Cryptosporidium, Giardia and viruses.

In the case of UV disinfection, minimum UV doses are specified for various log removal factors. For drinking water, often Cryptosporidium is the most important target for which the required UV doses are given in Table 1.

Table 1. Validated UV dose F (mJ/cm2) for inactivation of Cryptosporidium (LT2ESWTR 2006)

log(N0/N)

0.5 1.0

F (mJ/cm2) 1.6

2.5

1.5

2.0 2.5 3.0

3.9 5.8 8.5 12

3.5

4.0

15

22

The 2006 UVDGM states that the experimental reduction equivalent dose (RED) is given by: RED = Validated UV dose × VF (1) where VF is the validation factor given by: VF = BRED × Bpoly × (1 + Uval)

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(2)

For monochromatic light sources (e.g., the 275 nm UV LED), Bpoly is 1.0. Uval can be expanded as:

where UIN = uncertainty of interpolation; UDR = uncertainty of the UV dose – response; and US = uncertainty of the UV sensors.

According to the UVDGM, if US <10% and UDR < 30%, they can be set to zero, as was the case in the study, so Uval = UIN.

(4)

where UVA is the absorption coefficient (cm–1) of the water at 275 nm; DL is the UV dose per log of the test microorganism (MS2); S/S0 is the sensor factor, where S is the sensor reading and S0 is the sensor reading at full power; Q is the flow rate (m3/h); and A, B, C, D and E are the fit parameters.

The experimental RED data must be fit to equation 4 with the fitting constants determined by a nonlinear regression analysis using the solver function in Excel.

Restrictions must be applied so that C + D×UVA + E×UVA2 ≤ 1.0 and its derivative (D + 2*E×UVA) ≤ 0. A linear regression of RED vs. RED(calc), forced through zero, should have a slope within 2% of 1.00 and an R2 > 0.95.

It was found that, among all conditions, the relative error (∆RED/RED) is random and not a function of RED, so it is assumed that the quantity

U´IN = t × SD´

(5) uvsolutionsmag.com

adequately represents the uncertainty, where SD´ is the standard deviation of the relative differences between measured and predicted REDs as determined from the RED vs. RED(calc) correlation, and t is the factor (t = 2.05) that determines the 95% confidence level. Then

(6)

REDs from the UV dose–response curve For each of the 27 test conditions, four influent and four effluent samples were taken – timed so that a given effluent sample was taken from the same water as that for a given influent sample. The test conditions were organized into three sets – one for each UV-T. For each set, water was taken loaded with MS2 (but untreated by UV) for the purpose of carrying out a UV dose-response analysis (see Figure 3 for an example). These data then were fit to a quadratic equation as shown in Figure 3.

The UVDGM – and the “Innovative Approaches” paper – recommends plotting UV dose vs. log inactivation (N0/N) to allow conversion of the effluent/influent data to RED. However, this approach is believed to be flawed because, in regression analysis, it is assumed that all the error is in the independent variable – which is not the case for the recommended procedure. Instead, the UV dose-response fit equation was used to generate a large set of log(N0/N) vs. UV dose values. A LOOKUP function then was used to select an appropriate RED for each log(N0/N) from the effluent/ influent set of data.

RED data analysis The experimental REDs were then fitted to the master equation (Equation 4). The resulting fit is shown in Figure 4.

From the limits at the 95% level, the uncertainty factor UIN is determined as 0.294.

These BRED values are a linear function of the UV-T: BRED = -0.05224×UV-T+6.3151 = 6.3151–5.224×10–UV-A (7) Hence, the validation factor is: VF = (6.3151 – 5.224 × 10–UV-A)(1 + UIN)

(8)

On insertion into equation 4, one obtains the equation for the validated RED: (9)

This equation was solved for several pairs of Q and UV-T and for 3.0, 3.5 and 4.0-logs inactivation of Cryptosporidium.

The results are given in Figure 5. The arrows indicate the ranges of UV-T and Q for which the UV reactor is certified to deliver 3.0, 3.5 and 4.0-logs Cryptosporidium inactivation.

This work represents what is believed to be the first thirdparty validation of an LED UV system using the UVDGM guidelines. The BIO-310 reactor was validated for 2 to 4-log continued on page 20

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

RED bias factor Table 2 is obtained from Appendix G of the UVDGM. Table 2. RED bias factors vs. UV-T

UVT

DL/mJ cm-2

BRED

90%

20.26

1.61

95%

21.54

1.26

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.

98%

22.18

1.19

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. www.uvlampconsulting.com

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DRINKING WATER DISINFECTION continued from page 19

Figure 3. Plot of log(N0/N) for MS2 from collimated beam samples vs. UV dose

60 MS2 Slope = 1.00 Upper CL Lower CL

50

RED / mJ cm2

40

30

20

10

0

0

10

20

30 RED(calc) / mJ cm-2

40

50

60

Figure 4. Comparison of the experimental REDs to the REDs [(RED(calc)] calculated from the master equation. The dotted lines (small dots) are the upper and lower confidence limits at the 95% level.

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Cryptosporidium inactivation for flow rates up to 250 m3 h-1 and UV-T in the range 90 to 98%.

The primary objective of this work was to validate the reactor against specific design criteria: a maximum flow rate of 250 m3 h-1, a minimum UV-T of 95% and a target of 3-log Cryptosporidium inactivation, which was successfully achieved (Figure 5).

While many skeptics still see large-scale UV LED water treatment as not being competitive against conventional mercury lamp systems, some technology is believed to be capable of competing for specific applications on a whole life cost basis.

However, it is fair to say that a few experimental issues caused a negative impact on the RED bias factor and the uncertainty of validation. Correcting these issues would have a significant positive impact on the validated performance.

Today, initial capital costs tend to be slightly higher for LED UV technologies (arising from low wall plug efficiencies (WPE) and comparatively high $/mW costs), but it is well accepted that the WPE will keep increasing – leading to lower energy costs and longer lifetimes at every end-of-life of the previous set – whilst the cost per UV LED is expected to decrease significantly.

Additionally, in the year since the validation testing took place, the output power of commercially available UV-C LEDs has more than doubled.

In addition, since UV LEDs are solid-state devices, driven by current with an unlimited turndown potential, UV dose monitoring becomes a powerful tool.

Therefore, the next challenge is to revalidate the system with the more powerful UV-C LEDs and refined experimental procedures enabling an extension of the validated range of operation to lower UV-Ts and higher flow rates, thus increasing the system’s potential as a viable Cryptosporidium barrier and opening up opportunities as a primary disinfection barrier as shown in Figure 6.

Being able to adjust S/S0 (in the dose monitoring equation) in real time (every 100 ms) when a change in operational conditions is observed (i.e., flow rate or UV-T) enables one to maintain the required UV dose while minimizing the energy consumption. This feature on its own can reduce energy consumption by more than 40%. continued on page 22

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DRINKING WATER DISINFECTION continued from page 21

Figure 5. Validation ranges of UV-T and Q for 3.0, 3.5 and 4.0-logs Cryptosporidium inactivation

Figure 6. Current validation range of UV-T and Q for 4.0-logs Cryptosporidium inactivation and predicted validation ranges after revalidation for 4.0 logs Cryptosporidium inactivation and for primary disinfection (40 mJ cm-2)

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uvsolutionsmag.com

However, while the US EPA allows the validation of UV LED systems based on existing guidelines (UVDGM and “Innovative Approaches for Validation of Ultraviolet Disinfection Reactors for Drinking Water Systems”), it has been suggested that new – specific to UV LEDs – documentations would be required for UV LED systems to comply with European standards (DVGW, ÖNORM), a process that could take years to put in place.

Until recently it has been believed that the use of UV-C LEDs for municipal water treatment was still a few years away, but its time is coming fast.

In order to allow this market to develop, encourage new entrants and for end users to take advantage of such innovative solutions, it is vital that existing standards are updated/ amended to embrace the new technology. n Contact: Olivier Autin, oautin@typhontreatment.com; James R. Bolton, jbolton@boltonuv.com References

LT2ESWTR 2006 Long-term 2 Enhanced Surface Water Treatment Regulations https://www.epa.gov/dwreginfo/long-term-2-enhancedsurface-water-treatment-rule-documents US Environmental Protection Agency, Washington, DC.

Today, initial capital costs tend to be slightly higher for LED UV technologies [arising from low wall plug efficiencies (WPE) and comparatively high $/mW costs], but it is well accepted that the WPE will keep increasing – leading to lower energy costs and longer lifetimes at every end of life of the previous set – while the cost per UV LED is expected to decrease significantly.

UVDGM 2006 Ultraviolet Disinfection Guidance Manual https://nepis. epa.gov/Exe/ZyPDF.cgi?Dockey=600006T3.txt US Environmental Protection Agency, Washington, DC. Wright, Harold 2018, Innovative Approaches to UV Validation with Appendixes Nov 2018 Draft Final, private communication.

UV Solutions is seeking article submissions.

News releases, product announcements, application notes and more are welcome.

Email editorinchief@iuva.org. uvsolutionsmag.com

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APPLICATION HIGHLIGHT

Figure 1. A lab technician checks water samples under UV light in the plant’s lab. The Payson plant has consistently met the nondetectable effluent E. coli limit for ARIZONA TITLE 18 Class A+ reuse effluent. Photos courtesy of Enaqua.

For Water Reuse, UV Solution Brings Consistent Results to City Article provided courtesy of Enaqua,

a Grundfos company

W

ater is scarce and in high demand in the mountain desert town of Payson, Arizona. As a result, the city reuses its water. It sends the cleaned wastewater to a public recreational lake and then onward for irrigating green areas in public parks, golf courses and schools. Therefore, it is vital that the water is treated correctly and thoroughly, or else it would put people’s health at risk.

Payson’s wastewater treatment plant uses a non-contact UV system in its last stage of treatment. The system is designed with water flowing through light-transmitting activated fluoropolymer (AFP™) tubes and with the UV lamps placed on the outside of the tubes. The UV disinfection system is designed without the use of expensive amalgam lamps and quartz sleeves, providing a lamp replacement time of less than one minute. Intelligent flow, level pacing and the use of non-amalgam LPHO lamps provide energy savings up to 60%. The system serves the plant’s needs for low maintenance, low energy use and dependable disinfection.

“In a day-to-day operation, it runs. We don’t have to touch it, and it does its job,” said Garrett Goldman, district manager, Northern Gila County Sanitary District.

The situation and challenge Payson, population 15,000, sends nearly all its wastewater to the American Gulch Wastewater Reclamation and Reuse Facility on the edge of town. It is operated by the Northern Gila County Sanitary District.

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The five-stage Bardenpho plant treats the wastewater biologically.

After the effluent has been treated, the plant sends it out to Green Valley Lake in the center of Payson – a popular area for boating and fishing.

The water also is distributed to golf courses, parks, schools and the local cemetery for lawns, lakes and irrigation, said Chief Operator David Millien.

“The district really focuses on providing high-quality water for the community,” he said.

“So, we’re responsible for the safety of the community.”

Figure 2. Chief Operator David Millien holds up a rack of UV lights from one of the Enaqua noncontact UV reactors.

Goldman added: “If our treatment process is not working correctly, we are putting the entire community at risk. The noncontact UV disinfection system is the final stage in our treatment process. It’s what kills all of the ‘bad bugs’ in the treated water. If it’s not working correctly, we are polluting the environment.”

The solution In the mid-2010s, the plant expanded its treatment capacity and upgraded its biological treatment processes. As part of these upgrades, the plant needed to replace its aging, vesseltype UV systems.

Enaqua’s noncontact UV reactors were installed in October 2015. Since that time, the Payson plant has consistently met the Environmental Protection Agency’s regulations, as well as the nondetectable effluent E. coli limit for ARIZONA TITLE 18 Class A+ reuse effluent. This water quality standard requires effluent E. coli limits of 4/7 samples nondetectable and single sample maximum of 23.0 CFU/100 ml.

“We’ve been in compliance with our permits for years, with no violations, and we want to keep it that way,” said Goldman.

The outcome “All in all, everybody is really pleased with the system,” said Millien.

He said the operators appreciate the minimal time needed for cleaning and maintenance. The noncontact technology means that the effluent runs through AFP tubes, with the UV lamps uvsolutionsmag.com

housed around the AFP tubes in the dry body of the reactor, never coming in contact with the effluent.

“With the noncontact system, maintenance is really minimum. We do a back-flush on the cooling system once a week, which takes about 20 minutes, and that’s when the guys wipe down the unit to keep the dust and stuff off. That’s about it,” Millien said.

The Payson plant has two Enaqua reactors, and each is designed to handle up to 3.5 million gallons of effluent a day (13,250 m3/day). Each reactor has three banks of UV lights per channel, but typically the plant operates only two banks, due to the system’s efficient design and flexibility.

“With the three stages, we were already saving about 20% to 30% on the electricity compared to the old UV system,” said Millien. “And now we’ve shut off another stage, so we’re running at two-thirds of what was designed. We’re pleased and even looking into running just one stage. So, there’s more savings possible.”

The Northern Gila County Sanitary District put a big focus on energy efficiency and savings during the plant’s expansion.

A bank of solar panels operates the treatment plant during the daytime on sunny days, Millien added.

According to Goldman, “The more we can keep our operation and maintenance cost down is a benefit to our ratepayers.

And that is our one goal: to provide the best service at the lowest cost to our ratepayers. We don’t have to touch it, and it does its job.” n 2019 Quarter 3

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FEATURED ARTICLE

COMBINED SEWER OVERFLOWS

How to Address CSO Events with UV Technology Patrick Bollman, P.E.

UV product specialist, Evoqua Water Technologies

A

ccording to a study released by Water Resources Research1 in June 2019, heavy downpours have become more common since the middle of the last century, especially in North America, Europe and Asia. More frequent heavy rain will have implications up and down the ecosystem, from farmers contending with delayed plantings and flooded fields to communities grappling with the effects of high rivers, landslides and flooded sewers.

Flooded sewer events have become a growing concern for the more than 850 communities2 in the US that have a combined sewer system, in which a city’s wastewater and stormwater drain into the same treatment system. Under normal circumstances, this system works exactly as intended: rainwater, domestic sewage and industrial wastewater are all treated appropriately. But during peak flow events – such as a hurricane or tropical storm or even a sudden rush of snow melt – the flow can exceed the hydraulic capacity of the wastewater treatment plant or the collection system that transports the flow to the plant. Mature communities and cities, which have large amounts of concrete, asphalt and other impermeable surfaces, also have fewer places for that water to go. The result? Untreated overflow into a nearby body of water.

These overflows – called combined sewer overflows (CSOs) – are a priority water pollution concern for communities with combined sewer systems3; they contain a variable mix of untreated human and industrial waste, water polluted by running over city surfaces, and debris and scoured materials that build up in

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the collection system during dry weather periods. Combined, that water contains chemicals, pathogenic microorganisms, viruses and other pollutants that can adversely affect water quality and human and wildlife health.

Disinfection methods: chlorine vs. UV Because wastewater has so much potential to increase pollutant levels and even spread disease, disinfection procedures are imperative. Traditionally, most municipalities use chlorine for disinfection because of its effectiveness and flexibility of supply, from chlorine gas to chlorine compounds in solid or liquid form. It’s cost-effective, reliable and well established.

However, chlorine treatment methods have their drawbacks.

In addition to the danger potentially caused by any improper storage, shipping or handling, chlorine residuals are toxic to aquatic life even at low concentrations. Moreover, when chlorine is added to wastewater, it can alter organic matter by forming disinfection byproducts that can be dangerous themselves. Recognizing the toll on both the environment and on long-term public health, the EPA has established regulations governing residual chlorine limits and disinfection by-products.

Chlorine control is also difficult during CSO events. Like many chemical disinfectants, chlorine treatments must be calibrated to the amount and quality of the water being treated. CSO events, however, occur intermittently and vary widely in flow rate, which makes it difficult to strike the correct balance between disinfectant and flow. In order to cope with stormwater’s high flows, high suspending solids volume and variable temperature, chlorine systems can require4 long contact times. In addition, some CSO outlets are in remote areas that may require automated disinfection systems.

To avoid chlorine’s complexities, many municipalities are turning to UV disinfection. An estimated5 1 billion gallons of stormwater and wastewater per day are being treated with UV disinfection in North America, Europe, Asia and Australia.

Unlike chemical treatment processes, UV disinfection only applies light to water, altering the DNA of pathogenic organisms – such as E. coli, salmonella and the rotavirus, and the bacteria that cause cholera and typhoid fever, respectively – to prevent replication without adding anything further to the water.

UV treatment also is capable of inactivating Giardia and Cryptosporidium, two pathogens of concern. Unlike chlorine methods, UV disinfection does not create any chlorinated by-products and does not require chemical storage or metering pumps to be effective. Additionally – and critically for the unpredictability of CSOs – UV disinfection’s effectiveness is not reliant on water temperature or pH. uvsolutionsmag.com

They contain a variable mix of untreated human and industrial waste, water polluted by running over city surfaces, and debris and scoured materials that build up in the collection system during dry weather periods.

For systems with finite footprints, UV also requires less space than a chlorine system would. Because there are no additives, UV disinfection eliminates the need for (and the risk of) handling and storing toxic and corrosive chemicals. The equipment itself – medium-pressure lamps in closed vessel reactors – also has a smaller footprint and a quicker start-up time.

Testing the efficacy of a UV system also has become straightforward, thanks to the advent of bioassay techniques, which have been well established for drinking water and are now being evaluated for wastewater testing. A bioassay test introduces nonpathogenic organisms into the fluid stream before it hits the UV system. System variables, including flow, power loads, water transmittance and lamp intensity, are all carefully calibrated and recorded, and water samples are taken before and after the water is disinfected. From there, the samples are sent to an analyzing laboratory, and the system’s ability to disinfect can be compared to the manufacturer’s specifications.

As with all systems, UV disinfection performs better under some circumstances than others. The right UV intensity must be applied to the water for enough time to destroy the pathogens – and suspended solids absorb and scatter UV rays. Low-quality stormwater can have high levels of total suspended solids (TSS), requiring municipalities to factor that into the amount of UV equipment/power that is required to properly treat the water.

UV system design By their nature, CSOs can be more unpredictable than typical water flows, both in flow rate and in composition. Before a system is put in place, analysis should be done to determine the water quality that the UV system would need to treat so that the correct equipment can be put in place.

There are two generic designs available for UV disinfection: noncontact, which suspends lamps away from the wastewater, continued on page 28

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COMBINED SEWER OVERFLOWS continued from page 27

and contact, which uses lamps encased in a quartz sleeve or thimble that is submerged at all times. There are two main types of contact designs: open channel (both horizontal and vertical) and closed vessel.

An open channel system typically submerges lamps arranged parallel to the horizontal water flow, suspended from a selfsupporting stainless-steel structure. While initially effective, this design has some significant drawbacks. Water level and speed control are vital to this system’s success, which is often achieved through a sliding gate mechanism. However, these mechanisms are prone to blockage and require frequent maintenance. If the channel is undersized in any way, the water will move through the system too quickly for proper disinfection – a problem made even worse if the channel is designed for typical weather flows and not peak wet weather flows.

Channel design can also create dead zones, which leads to short circuiting (a water layer above the lamps) and pockets of untreated water, and head-loss and overflow problems caused by flow straighteners. Finally, open channel systems can lead to burned skin or eyes or inhalation risks of airborne enteric viruses if proper precautions are not taken by operators.

Given these drawbacks, closed vessel systems have emerged as a newer technology poised to replace older systems and utilized in new UV disinfection systems. This method puts UV lamps in a sealed disinfection chamber that can be used in gravity or pressurized systems. The closed pipe protects the operator from being exposed to wastewater and UV light alike, and generally uses fewer lamps and consumable components in a smaller footprint, frequently reducing capital and/or operating costs of the project. UV chambers can be installed directly into a pipe network, eliminating the need for concrete channels and making it easy to retrofit the technology into already existing open channels or chlorine contact basins.

UV disinfection in action The city of Rushville, Indiana, is in a rural area southeast of Indianapolis. Like 120 other communities in the state, Rushville has a combined sewer and often experienced CSOs in extreme weather situations. Because its system was not originally designed to treat stormwater in addition to wastewater, the flow would exceed the hydraulic capacity of the wastewater treatment plant, forcing the plant to bypass untreated wastewater, which would discharge into the nearby Flat Rock River, which is part of the watershed of the Mississippi River. Because of these discharges, Rushville was found to be in violation of the Clean Water Act.

28 | UVSolutions

Evoqua’s ETS UV closed vessel medium pressure SW1250-20 UV reactor

The Indiana Department of Environmental Management granted Rushville 15 years to eliminate the overflow with milestones that it needed to meet every five years. In order to meet those milestones, Rushville reexamined its wastewater treatment protocols. Like many municipalities, it had been using a chlorine disinfection system, but the growing awareness of the adverse environmental impacts caused by chlorine and its by-products has led to increasingly restrictive chlorine residual requirements that are difficult to meet. Rushville decided to replace its chlorine system with a UV system to realize the benefits of reduced risk to plant operators and the surrounding environment and more effective elimination of chlorine-resistant pathogens such as Giardia and Cryptosporidium.

Rushville chose a closed vessel ETS UV system to treat the plant’s wastewater and its CSOs, making any excess water discharge into the river safe. Rushville chose this system because of its compact design, which makes routine maintenance easier; unique product features, such as low-voltage automatic wipers to keep quartz sleeves clean and reduce fouling; and a short lead time from purchase order to delivery to site.

Because of the nature of closed vessel systems – and the fact that it did not need any new structures constructed – the entire project was designed to minimize cost and impact to ratepayers. Critical for Rushville’s CSO needs, the system is fully automated to respond to variable flow and water quality without wasting any energy. uvsolutionsmag.com

“The combination of solutions we selected to mitigate the risk associated with CSOs is the first of its kind in the state of Indiana,” said Les Day, city utilities facility manager. “The compact design of the ETS-UV disinfection system did not require the addition of a structure to house the equipment.

Receiving effective disinfection without the use of chemicals allows us to put our best foot forward to protect the Flat Rock River.”

To achieve optimal results, Rushville’s system also included the application of cloth-media disk filters (CMDFs) – making it the first completed project in the US to use CMDFs combined with UV disinfection for CSO treatment. The filters serve two main purposes: improve transmittance of the wastewater/ stormwater and reduce the total suspended solids. Suspended solids can shield or embed coliforms as they pass by the UV lamps, thus reducing the effectiveness as these coliforms will not be exposed to the UV light.

excellence from the American Council of Engineering Companies (ACEC) of Indiana.

Today, Rushville’s system remains operational, and the city remains on track to meet its compliance schedules.

Conclusion Untreated CSO events present a real environmental hazard surrounding overflow sites, and the risk of CSO events is likely to increase over the coming years. To avoid adverse environmental impacts and censures from local environmental protection agencies, municipalities are reevaluating the methods they use to ensure that upsets from CSO events are mitigated. n Contact Patrick Bollman, patrick.bollman@evoqua.com For full list of references, www.uvsolutionsmag.com.

view

this

article

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Thanks to these results, Rushville met its CSO compliance schedule five years early and met the future lower phosphorous discharge limits three years early. In recognition of these results, the city of Rushville – along with Donohue, the engineers behind the project, and Bowen, the general contractor – received a 2018 Merit Award for engineering

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FEATURED ARTICLE

IRRADIATION OF BIOFILM

Figure 1. Biofilm formation over time

UV-C LED Irradiation for the Inactivation of Biofilm-bound Pseudomonas Aeruginosa Bacteria Kyle D. Rauch, Stephanie Gora,

B

iofilms are ubiquitous in nature and have the potential to harbor dangerous, opportunistic pathogens. Biofilms form when planktonic bacteria come into contact with a wetted surface and begin to release extracellular polymeric substances (EPS), allowing them to adhere to the solid substrate (Figure 1). Once the bacteria have adhered, they begin to replicate and increase EPS production, thickening the layer of the biofilm and securing the structure to the substrate.

Carolina Ontiveros The EPS matrix provides protection against common disinfection methods and makes disinfection of

microorganisms encased in the biofilm increasingly difficult. This increased challenge to disinfection

and Graham becomes even more problematic when opportunistic pathogens (e.g. Pseudomonas aeruginosa and Gagnon Legionella pneumophila) find refuge in the biofilms. Infections acquired from biofilm-bound bacteria can Centre for Water Resource Studies, Dalhousie University, Halifax, NS, Canada

cause severe illness and even death in individuals with compromised immune systems.1 Biofilm-bound bacteria have been associated with 80% of bacterial infections in the US2 and are a common concern for food and healthcare industries.

In a clinical setting, biofilms can contaminate a wide range of infrastructure, tools and devices including, but not limited to, showerheads, hot water storage, dental water lines, endoscopes, catheters, pacemakers and prosthetic heart valves etc.3 P. aeruginosa infections acquired in the clinical setting have been shown to increase the rate of illness and death rates of patients.4,5

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In the food industry, meat, dairy, fish, poultry and produce are all at risk of biofilm contamination that can arise at any point from farming to consumption. Major risks of contamination stem from the product coming into contact with tainted process water, work surfaces and equipment.2 Contamination of food products can ultimately cause serious health consequences if the food is consumed and also can cause financial losses for a company through increased spoilage and loss of product.3 Biofilms are also a common concern in the water industry, as they can form on water treatment process equipment (e.g. membrane Figure 2. Factors examined for optimization of UV-C LED treatment of CDC biofilm filters), distribution system reactor coupons coated in P. aeruginosa biofilms infrastructure, premise plumbing, water storage tanks and secondary storage One study has shown that this is likely due to the high cellular containers. The results of previous studies suggest that density within the EPS matrix, which leads to increased opportunistic pathogens, including Legionella, can grow attenuation of the UV light through the depth of the biofilm.10 inside of biofilm-dwelling hosts (e.g. protozoa) in drinking Furthermore, the complex EPS matrix also may provide water infrastructure.6 These risks often are exacerbated shielding effects.14 in remote and/or decentralized applications where water treatment technology is limited and the maintenance of A previous study suggests that a control strategy that first onsite drinking water systems is the responsibility of disrupts or dissolves the EPS matrix using surfactant should residents or building owners with minimal training (e.g. be adopted, as it will increase the penetration of chemical Farenhorst et al.7). disinfectants.15 A similar method potentially could be employed to allow for better penetration of UV-C irradiation In the food, healthcare and water sectors, many biofilm control into biofilms. strategies have been implemented, including chemical control with such agents as sodium hypochlorite, hydrogen peroxide, The objectives of this work were to develop a standard protocol peracetic acid and ozone2; however, introduction to chemical for inactivating P. aeruginosa in biofilms with a UV-C LED agents eventually may lead to the development of resistant collimated beam apparatus, compare inactivation from UV-C microbial populations.8,9 Other types of control methods â&#x20AC;&#x201C; irradiation to commercial disinfecting wipes and investigate such as ultrasonication, phages, enzymatic solutions, UV/ the impacts that the application of commercial disinfecting H2O2 and UV/Cl2 â&#x20AC;&#x201C; also have been employed to mitigate wipes before UV-C irradiation have on inactivation. biofilms.2 UV-C LED method development UV irradiation alone also has been studied by many researchers The methodologies employed in previous studies focused with varying results.10,11 The different methods employed by on the application of UV for biofilm mitigation reflecting the researchers applying UV irradiation in different niche the industry-specific questions being addressed by the applications may have given rise to the inconsistent results. researchers who developed the experiments and apparatus.

However, common across these studies is the finding that As a result, it is difficult to compare and generalize the much higher UV fluences are required to achieve similar results of these studies. A robust and repeatable method was levels of inactivation of biofilm-bound microorganisms continued on page 32 compared to planktonic (free floating) microorganisms.10,12,13 uvsolutionsmag.com

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IRRADIATION OF BIOFILM continued from page 31

Next, treatment was optimized with the UV-C LED collimated beam apparatus (Aquisense Technologies, Kentucky, US) based on three factors: the number of coupons being treated, rotation vs. no rotation and UV intensity (Figure 2). The study found that increased inactivation was achieved when samples were rotated at 5 RPM and that the number of coupons and intensity of the UV-C LEDs had no impact on inactivation. Thus, it was decided to treat three coupons at a time with a rotation of 5 RPM at the highest possible intensity for the remainder of the study.

Scraping and swabbing were compared as biofilm recovery methods and hand mixing, vortexing, sonicating and stomaching as biofilm resuspension methods. The materials and settings used for the different recovery methods were adapted from a previous study examining efficient biofilm removal from annular reactor coupons.18 The resuspended samples were enumerated on tryptic soy agar (TSA) plates at 37°C for 18 to 24 hours. We determined the combination of recovery and resuspension methods that gave the Figure 3. Standardized protocol for growth, treatment, recovery and analysis of Pseudomonas aeruginosa biofilms during UV-C LED inactivation highest yield of P. aeruginosa cells and experiments used it in the remainder of the study. A summary of the recommended standard developed for growing, treating and recovering biofilms for method for UV-C LED treatment of P. aeruginosa biofilms is UV-C LED inactivation experiments. A full description of outlined in Figure 3. this standardized method can be found in Gora, et al.16 Experimental A CDC biofilm reactor and the method developed by the US The 265 nm UV-C LED used in this study was characterized EPA17 were employed to grow stable P. aeruginosa (PA01) and found to have a peak wavelength of 268 nm and an biofilms on polycarbonate coupons. The growth process FWHM of 11.5 nm. The intensity of the UV-C light delivered included two stages designed to encourage biofilm adhesion to the samples was determined by measuring the average and maturation. In the first stage, 500 mL of nutrient-rich intensity over the treatment field of the three coupons with media was inoculated with 1 mL of a highly concentrated P. a USB4000 spectrometer equipped with a DET4-200-850 aeruginosa stock and maintained at room temperature for 24 detector (Ocean Optics Inc., Florida, US). hours. This stage ensured the bacteria adhered to the surface of Intensity measurements were collected with a 0.5 cm spatial the coupon and initialized biofilm formation. resolution at the surface of the coupons. The total intensity In the second stage, the nutrient-rich media was fed slowly into under the spectrum of the UV-C LED was collected by the reactor at approximately 10 mL/min at room temperature integrating the peak from 220 nm to 300 nm for each point in for an additional 24 hours. This stage allowed the attached the treatment field. Once the average intensity was measured, the exposure times required to achieve UV fluences ranging biofilm to develop and mature.

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from 0 to 12 mJ/cm2 were calculated by dividing the required fluence by the average intensity.

P. aeruginosa biofilms were grown on polycarbonate coupons in a CDC biofilm reactor using the above method. Following growth, treatment with UV-C LED irradiation, common disinfectant wipes or a combination of wiping followed

by UV-C LED irradiation was applied to the contaminated coupons. UV fluences between 0 and 60 mJ/cm2 were applied using a UV-C LED collimated beam apparatus (Aquisense Technologies).

For the wiping treatments, a conventional disinfecting wipe (Cavi-Wipes, Metrex; Orange, California, US) were used in either a single pass or contacted with the surface for 15 seconds. Isopropyl alcohol (17.2%) and ammonium chloride (0.28%) are the active ingredients in Cavi-Wipes.

Results and discussion Inactivation from UV treatment alone was shown to plateau at approximately 1.3-log reduction after a UV fluence of 8 mJ/ cm2 (data not shown, see publication for kinetics16). This was not entirely unexpected, as the inactivation of biofilm-bound microorganisms has been shown to require significantly higher fluences compared to free floating planktonic cells.

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The different methods employed by the researchers during the application of UV irradiation in different niche applications may have given rise to the inconsistent results.

For example, research has shown that a fluence of approximately 4 mJ/cm2 can achieve a similar log inactivation of 2 log in a pure suspension of planktonic P. aeruginosa.19 When examining indigenous bacterial communities in catheters, it was shown that the UV fluence required to achieve 4 log inactivation in the biofilm community was 10 times greater than that of the resuspended biofilm.10 In another study, authors examined UV-C LED inactivation of P. aeruginosa in biofilms formed on catheters and found that a 4-log inactivation could be achieved with a fluence of 7.9 mJ/cm2.20 continued on page 34

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IRRADIATION OF BIOFILM continued from page 33

Figure 4. Combined treatment with commercial disinfectant wipes and UV-C LEDs had potential synergistic impacts on P. aeruginosa (*one replicate had >7.8 log reduction)

Treatment with commercial disinfecting wipes alone resulted in minimal differences between the single pass and the 15-second contact time and saw a slightly increased disinfection potential when compared to UV-C LED treatment alone.

However, when used in combination with UV-C LED irradiation, synergistic effects were observed. For example, a 2.3-log reduction was achieved with a single pass of the commercial disinfecting wipe, and when a 12 mJ/cm2 fluence was applied to the biofilm a 1.3-log reduction was achieved.

When the two methods were used in combination, the resulting plates contained too few colonies to count, indicating that more than 7.8-log inactivation was achieved. This suggests that up to 4.2-log inactivation was potentially related to synergistic effects between the wiping and UV-C LED treatments.

It was hypothesized that these effects may have occurred because the wiping treatment disrupted the biofilm and

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Figure 5. Potential applications for UV-C LED-based biofilm prevention and biofilm mitigation control strategies in clinical and food settings

decreased any shielding effect the EPS matrix may have been providing to the cells (see Figure 4).

Interactions between the residual chemicals from the wipes and UV-C irradiation also may have contributed to the improvement in inactivation. The mechanism(s) underlying uvsolutionsmag.com

the synergistic effects reported here is the focus of current research into biofilm prevention and mitigation on surfaces.

This study demonstrated that the effectiveness of treating polycarbonate surfaces contaminated with P. aeruginosa biofilms was greatly improved by wiping with commercial disinfecting wipes followed by UV-C LED irradiation.

While these findings may not be appropriate for all the areas where biofilm control strategies may be required (Figure 5), it is believed that the protocol presented will allow researchers to examine how factors such as active ingredients in disinfecting wipes, substrate materials, bacterial species and UV wavelengths impact the inactivation of biofilmbound microorganisms.

Conclusion This study examined the best method to systemically treat P. aeruginosa biofilms grown on polycarbonate coupons with a UV-C LED collimated beam apparatus. The method developed from this work provides a robust, bench-scale protocol to investigate inactivation responses of biofilm-bound bacteria that could be adapted for other industry-specific needs. This study also investigated the effectiveness of commonly used isopropanol disinfectant wipes on biofilm mitigation and the impacts of combing the wipes with UV-C LED irradiation.

When the two methods were combined, a 7.9-log reduction in P. aeruginosa was achieved, well above the reductions observed for either treatment alone. The mechanisms behind these synergistic effects were not explored in this study, but it is hypothesized that the increased reduction in cells was likely due to mechanical and/or chemical disruption of the EPS matrix prior to the application of UV-C irradiation.

This hypothesis is currently being tested in the laboratory.

The findings from this study suggest a two-stage treatment approach combining disinfectant wipes and UV-C LED irradiation could prove to be highly effective for biofilm control on surfaces. n Contact: Kyle D. Rauch, kyle.d.rauch@dal.ca; Stephanie Gora, stephanie.gora@dal.ca; Carolina Ontiveros, carolina. ontiveros@dal.ca; Graham Gagnon, graham.gagnon@dal.ca For full list of references, www.uvsolutionsmag.com.

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FEATURED ARTICLE

PASTEURIZED MILK ORDINANCE

What is Going On with the Grade A Pasteurized Milk Ordinance?

Harold Wright

chief technologistUV disinfection, Carollo Engineers

T

he Grade A Pasteurized Milk Ordinance (PMO), published by the Food and Drug Administration (FDA), provides standards and requirements for Grade A milk production and processing. The standards are recommended by the National Conference on Interstate Milk Shipments (NCIMS), whose members include state and local regulatory agencies and representatives from the industry. The PMO is revised every two years, with the latest revision in 2017.

The 2017 revision provides a list of criteria required for water treated with UV light to be considered equivalent to pasteurized water. Those criteria include the following requirements: • UV light shall be applied so that the entire volume of water receives at least the following dose when used as pasteurized water. ºº Low-pressure UV at 2,537 Angstrom (254 nm) at 186,000 microwatt-seconds per square centimeter or a 4-log adenovirus equivalent. ºº Medium-pressure UV at 120,000 microwatt-seconds per square centimeter or a 4-log adenovirus equivalent.

The UV dose of 186 mJ/cm2 specified for LPHO UV systems is the validated UV dose required by the US EPA’s Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) for 4-log adenovirus inactivation. The basis for the UV dose of 120 mJ/cm2 is not defined by the PMO. It is clearly not a validated dose for adenovirus credit, as defined by the LT2ESWTR and the US EPA’s UV Disinfection Guidance Manual (UVDGM), because such a dose would not provide 4-log adenovirus inactivation credit. Given past work comparing MS2 and adenovirus reduction equivalent doses with full-scale reactors, the 120 mJ/cm2 is likely an MS2 RED measured during UV validation testing.

Does an MS2 RED of 120 mJ/cm2 delivered by a MP UV reactor achieve 4-log adenovirus inactivation credit? It is known that RED bias and action spectra (wavelength response) differences (Figure 1) impact continued on page 38

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validation can go away with the application of the UV reactor in the field because of lamp aging and fouling effects and changing water quality. Lamp aging and fouling both have a greater impact at lower wavelengths. An increase in nitrate will lower UV dose delivery at wavelengths below 240 nm but have negligible impact on UV dose delivery above 240 nm.

Commercial UV sensors currently used by many commercial MP systems are not designed to monitor low wavelength UV light. Hence, the low wavelength benefits may not occur with the application, but the UV sensors will not indicate that is the case.

Figure 1. Large differences observed with the action spectra (relative wavelength response) of MS2 phage and adenovirus. The action spectra is normalized to 1.0 at 253.7 nm.

the RED measured during validation with two different microbes. If one were to conduct validation of an MP reactor using MS2 phage and adenovirus, the adenovirus RED measured at given flow, UV-T and lamp output would have a greater value than the MS2 RED. The magnitude of that difference would depend on the UV reactor design and its validation. The width of the dose distribution delivered by the UV reactor, which depends on UV-T and the hydraulics through the reactor, would determine the magnitude of the RED bias affect. The type of quartz sleeve used by the reactor, the UV absorbance spectrum of the water and the relative spacing of MP lamps within the UV reactor would determine the magnitude of the action spectra affect, especially at wavelengths less than 240 nm (Linden et al., 2015).

Because the difference between the MS2 and adenovirus RED depends on the UV reactor design and its validation, one might observe that a given UV reactor delivers an MS2 RED of 60 mJ/cm2 when it delivers an adenovirus RED of 186 mJ/cm2, while another UV reactor delivers an MS2 RED of 150 mJ/cm2 when that reactor delivers an adenovirus RED of 186 mJ/cm2. Clearly, specification of a RED of 120 mJ/ cm2 is specific to one reactor technology and its validation.

This is problematic because UV requirements should be independent of any commercial technology and its validation.

It is also known from Water Research Foundation (WRF) Project 4376 that low wavelength benefits realized during uvsolutionsmag.com

This issue is addressed in the final report of WRF Project 4376 (Linden et al., 2015). This report states that the validation factor for MP systems should include an action spectrum correction factor (ASCF). Appendix C of the report provides tables of ASCFs when MS2 REDs measured during validation are used to show 4-log adenovirus inactivation credit. For a UV system equipped with synthetic quartz, those ASCF values range from 0.89 to 1.79. Appendix D of the report provides tables of ASCFs when adenovirus REDs measured during validation are used to show 4-log adenovirus inactivation credit. For a UV system equipped with synthetic quartz, those ASCF values range from 1.06 to 5.49.

The UVDGM states that the required RED for disinfection credit is calculated as: Required RED = Required Dose × Validation Factor where the required dose is specified by the LT2ESWTR. With inclusion of the ASCF, the validation factor (VF) for MP systems is calculated as: VF = BRED × BPoly × ASCF × (1 + UVal)

where BRED is the RED bias; BPoly is the polychromatic bias; and Uval is the uncertainty of validation.

Per the UVDGM, if MS2 REDs are used to show adenovirus log inactivation credit, the RED bias is set to 1.0. The polychromatic bias of many MP systems also can be set to continued on page 38

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PASTEURIZED MILK ORDINANCE continued from page 37

1.0, per the UVDGM. The uncertainty of validation with MS2 is around 3% for an MS2 RED near 186 mJ/cm2. If the ASCF values given in WRF Project 4376 vary from 0.89 to 1.79, then the MS2 REDs for 4 log adenovirus vary from 171 to 343 mJ/cm2, well above an MS2 RED of 120 mJ/cm2.

The ratio of these numbers to the value of 120 mJ/cm2 ranges from 1.42 to 2.85.

In other words, an MP UV system operating with a UV disinfection application to deliver an MS2 RED of 120 mJ/ cm2 based on validation could, in actual fact, be delivering an adenovirus validated dose ranging from 42 to 85 mJ/ cm2 – values that achieve only 0.58 to 1.64 adenovirus log inactivation credit.

The PMO UV dose requirements are impacting the use of UV disinfection systems in other markets. For example, a UV specification in the beverage market calls for a UV dose of 186 mJ/cm2 for low pressure, high output (LPHO) systems but only 120 mJ/cm2 for MP systems. No reference is made to adenovirus; hence, these requirements are being generalized in other markets.

Other comments on the PMO The PMO specifies that “There shall be one (1) sensor for each UV lamp.” This requirement prevents the use of LPHO UV systems that would be considered acceptable for potable drinking water applications. This requirement was put in place to address uncertainty with UV dose monitoring that occurs with LPHO systems that use one UV sensor to monitor multiple lamps.

The irony with this requirement is that under-dosing that can occur because one UV sensor monitors more than one lamp is typically less than 20%, which is much less under-dosing that can occur because the UV sensor does not properly monitor low wavelength UV dose delivery.

The PMO also states that all particles passing through the UV reactor receive the minimum dose. This language is essentially stating that the minimum UV dose of the UV dose distribution delivered by the reactor must meet the UV dose requirement, as opposed to the RED. All reactors, without exception, deliver a UV dose distribution, and the RED measured during validation is not the minimum UV dose of the dose distribution. Hence, this requirement cannot be demonstrated by UV systems that have been validated using microspheres, since microspheres measure the UV reactor's dose distribution.

accurately. However, the UVDGM describes validated UV dose monitoring algorithms that do not require an online UV-T analyzer. As described in Section D.2.1 of the UVDGM, with an optimally placed UV sensor, there is a single relation between UV dose delivery and the UV sensor readings that can be used to define a UV dose monitoring algorithm that does not require a UV-T monitor.

There are many UV systems on the market that have validation algorithms that use this approach to define operation for 4-log adenovirus credit. This requirement of the PMO prevents those systems from participating in this market. n Contact: Harold Wright, HWright@carollo.com

Last, the PMO requires that all UV systems use a real time UV-T analyzer to assure that the dose is always calculated

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STANDARD UNIT OF MEASUREMENT FEATURED ARTICLE

Why is There No Standard Unit Similar to Lighting Products for Radiant Output of UV Lamps?

T

he visible portion of the output (luminous flux) of lamps used for illumination is expressed in lumens, a measure of the total quantity of visible light emitted by a source. This is possible because the output is measured only in the wavelength response range of the human eye. This response is defined as the photopic luminosity function (Figure 1). Illuminance is the luminous flux incident per unit area, measured in lux (lm/m2). So, if a photometer’s response is filtered or electronically weighted to mimic the eye response, its measurement is proportional to the output in lumens. (One will almost always find the output in lumens printed on the package of lighting products.)

R.W. Stowe UV applications engineering consultant, Heraeus Noblelight America LLC

As most visible light sources emit radiant energy outside of the visible range, the total radiant output power (radiant flux) of a visible lighting source is expressed in watts. With lumens as a measure of weighted visible output, we can describe the efficacy of lighting products in lumens per input watt (while efficiency is total radiant output watts per input watt).

Figure 1. The response of a typical human eye to light. (The 1931 CIE photopic luminosity function)

So, why don’t we just do the same thing to describe the UV output of UV lamps? Because there is no “standard” response curve for reference! Among the many applications and UV technologies, the UV wavelengths of interest are all over the “UV map.” To name a few, organisms, cells, photoinitiators and radiachromic compounds respond to UV, but each in its own range of responsivity, or action spectrum. Consequently, meaningful measurements are made in different wavelength bands of interest, typically defined by upper and lower wavelength.

Generally, UV is divided into three spectral regions: UVC (200 to 280 nm), UVB (280 to 320 nm) and UVA (320 to 400 nm). This is convenient, but not precise: These regions are not strictly defined and actually vary in different technologies. [A fourth range is the VUV (100 to 200 nm) or vacuum UV, which does not transmit through air, so is not usually of interest in terrestrial industrial applications.]

UV literature is rich with graphs of the spectral distribution of UV sources, including medium-pressure mercury, medium-pressure mercury with additives, low-pressure mercury, amalgam, xenon flash and UV LEDs. The spectral range is anywhere between 200 and 450 nm.

What band of interest would we use to specify radiant exposure? And, what bandwidth? Of course, in UV applications, a combination of photoinitiator response and optical thickness of the film determines the band(s) of interest. continued on page 40

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STANDARD UNIT OF MEASUREMENT continued from page 39

have reproducible irradiance measurements in watts/cm2.

UV-A Filter vs. Metal Halide Spectrum 1.2

Power in UV-A Band 12.1 W/m2

What tools?

Essentially, there are two electronic types of radiometric tools available – spectroradiometers and filter/detector radiometers.

Spectroradiometers – with fine resolution over the entire UV range, a “square” response and selectable upper and lower wavelengths – are ideal but can be costly and physically difficult to adapt to UV configurations.

Relative Magnitude

1 UV-A = 10% Metal Halide 0.8

0.6

0.4

Power Under UV-A Filter 7.1 W/m2

0.2

0 250

270

290

310

330

350

370

390

410

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450

Wavelength (nm) Figure 2. Filter/detector response vs. UV irradiance (From Schmutz, L.E., Spectroradiometry in UV Curing)

Filter/detector radiometers are the most common type and are more convenient to use. There are several forms: probes, wands, meters with interchangeable detachable sensors and completely portable “pucks.”

All of these instruments are radiometers, as they measure only irradiance, in watts/cm2. A few have internal clocks and can integrate irradiance data over time to report exposure (“dose”) in joules/cm2. A combination of internal components determines the sensitivity and response band of each instrument.

Here’s where things get fuzzy.

Virtually all f/d radiometers have a “soft” spectral response profile (Figure 2).

Wavelength, nm

Ideally, the photoinitiator absorption spectra (an indicator of action spectra) would be a guide, but even that gets complex.

Bandwidth, the range from lower to upper wavelength, is a matter of interpretation.

Some manufacturers define the wavelength range at the 10% response points, while others more commonly use the 50% points.

The radiant units that we measure are in watts. However, unlike lumens, there is no assumed or defined spectral range.

If we select and define the wavelength band of interest by upper and lower wavelength limits, Λ1 to Λ2, we hope to

A modest review of several commercial UV radiometers reveals a variation of the named bands among manufacturers and models, illustrated in Figure 3. (For a fair comparison, all bands were normalized to the 50% points.)

Figure 3. Spectral response bands of several commercial UV radiometers; each band characterized at 50% response wavelengths

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ISO 9001:2015 Registered

Figure 4. Filter/detector response vs. broadband UV irradiance

So, in UV technology, we not only don’t have a “standard” wavelength reference as we do in lighting technology, but the reference varies with the radiometer chosen.

Knowing a radiometer’s response band is important.

Reporting radiometer data without the band data (or identification of manufacturer and model) would lead to differences in data or reproducibility – except when comparisons are made with the same or same type of radiometer.

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In UV technology, we not only don’t have a “standard” wavelength reference as we do in lighting technology, but the reference varies with the radiometer chosen.

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It’s difficult to understand why – in reports, articles and even in technical papers – measured wavelength bands often are not reported with data.

This may be surprisingly common in UV technology, but that’s what we do. n Contact: R.W. Stowe, d.stowe@heraeus.com

www.light-sources.com

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INDUSTRY NEWS

Bridgeport Magnetics Introduces ULTRASWEEP for Surface Disinfection Bridgeport Magnetics Group, Inc., Shelton, Connecticut, introduced ULTRASWEEP, a low-cost solution for UV-C ultraviolet surface disinfection. ULTRASWEEP is permanently installed in locations with a high risk of touch transferred infections. Target areas include operating rooms, intensive care units, emergency departments and other highrisk patient rooms. During a sterilization cycle, the radiation source travels along a 10 ft. diameter circle. The UV-C emitters are mounted opposite the drive end and travel almost imperceptibly while covering surfaces with germicidal UV radiation from alternating directions. For more information, visit www.bridgeportmagnetics.com.

World’s First Installation of Ultraviolet LED Water Treatment Equipment Typhon Treatment Systems Ltd., Penrith, United Kingdom, won an order to install its UV LED technology at a 28 megaliter-per-day (mld) drinking water treatment plant in the northwest of England. The facility, owned by regional water company United Utilities, will be the first location in the world to install municipal-scale UV LED water treatment technology. The energy-saving, low maintenance, mercuryfree equipment is being installed to upgrade the plant’s ability to treat for chlorine-resistant pathogens like Cryptosporidium.

The equipment will be fully integrated into the existing control and monitoring system. Continuous feedback and UV LED output control ensure accurate, energy-efficient UV dose during operation. Installation and commissioning are expected for early 2020. For more information, visit www. typhontreatment.com.

Gigahertz-Optik Develops Laser Detector Gigahertz-Optik, Amesbury, Massachusetts, recently developed the ISD-1.6-SP pulsed laser detector with 16 mm diameter integrating sphere for integration of laser modes and beam profile. Because of its very small diameter, the temporal pulse deformations (pulse-stretching effect of integrating spheres) are small compared to those with larger diameters. As a result, pulses of a few nanoseconds pulse length are hardly deformed and can be measured in a time-resolved manner. For more information, visit www.gigahertz-optik.com.

42 | UVSolutions

Connect with Water Professionals from All Over the World at Aquatech With more than 928 exhibitors, a visitor attendance of 20,490 from 140 countries and 1,100 Amsterdam International Water Week (AIWW) conference delegates, Aquatech offers four days filled with inspiration and innovation. Aquatech Amsterdam 2019, Nov. 5-8, will provide the perfect platform to network, exchange ideas and do business. Finding new ways to share knowledge and best practices has never been more important in the world of water technology. Aquatech Amsterdam is more than just an exhibition. In 2019, visitors will discover the latest trends, developments and solutions to mitigate water challenges. Discover the guided tours, seminars, co-located events, theme and country pavilions, and social events. For more information, visit www. aquatechtrade.com.

Water Research Foundation Recognizes Achievements in the Water Sector The Water Research Foundation (WRF) has awarded the 2019 Dr. Pankaj Parekh Research Innovation Award to Dr. Karl Linden, Mortenson Professor in Sustainable Development, University of Colorado Boulder. The Dr. Pankaj Parekh Research Innovation Award honors researchers who have advanced the science of water through WRF-sponsored Linden projects. Linden has served as a principal investigator on WRF research projects for more than 20 years, including several significant ultraviolet (UV) disinfection-related projects. Most recently, he led a team that developed action spectra correction factors for UV inactivation of Cryptosporidium and other pathogens. He has also served as a project advisory committee member on diverse project topics. He has demonstrated research innovation and knowledge that can be applied by utilities and other end users to protect public health. For more information, visit www. waterworld.com.

World’s Smallest UV LED System Validated AquiSense Technologies, Erlanger, Kentucky, became the world’s first UV LED supplier to be tested against US Environmental Protection Agency (EPA) protocols for its PearlAqua Micro range. The PearlAqua was verified

by Hull Consulting, LLC, in compliance with US EPA microbiological performance protocols. The PearlAqua Micro is the world’s smallest UV system. The system offers benefits to the customer through LED current sensing and UV intensity monitoring, as well as a variety of other design benefits. The PearlAqua Micro is designed to be integrated at the point of use for superior disinfection. The system is validated to US EPA protocols to meet the microbiological performance with flow rates from 0.1 to 10.0 LPM. This validation provides reduction equivalent dose (RED), in uvsolutionsmag.com

selecting the right configuration for their application, flow rate, microbiological performance and UV dose. For more information, visit www.aquisense.com.

Proximity Team Receives Recognition Steve Reinecke of Proximity Systems, Tomball, Texas, was honored recently with the Don Walker Award during the HISA Health Informatics Conference (HIC). Reinecke, and Proximity, were recognized for submitting the best clinical case study abstract, “Evaluating the Use of UV-C Light Devices in a Clinical Setting to Reduce Pathogens on Computer Workstations.” Winners were selected Reinecke based on a peer review score, as well as a presentation during the conference. For more information, visit www.proximitysystems.com/uvclean.

WEFTEC 2019 Comes to Chicago WEFTEC offers water quality professionals the best in water quality education and training Sept. 21-25 in Chicago.

Recognized as the largest annual water quality exhibition in the world, the show floor provides access to cutting-edge technologies, serves as a forum for domestic and international business opportunities, and promotes invaluable peer-topeer networking among registrants. A wide range of topics and focus areas allow registrants to design their own unique learning experience while earning up to 16.5 professional development hours (PDHs) for continuing education units and eight general contact hours per day visiting the exhibition.

An increasing number of abstract submittals from experts in the water quality field results in a world-class program of technical sessions and workshops that address a diverse and comprehensive list of contemporary water and wastewater issues and solutions. For more information, visit www. weftec.org.

UV Pure Achieves New Safety Certification UV Pure, Toronto, Canada, achieved two important safety certifications for key models in its line of third-generation Hallett™ systems. The Hallett 1000 systems have achieved NWRI/USEPA UVDGM 2006 certification, and the Hallett 500PN and 750PN systems have achieved NSF/ANSI 55A certification. Each model was submitted to a battery of tests over a period of three to six months to ensure the systems perform as promised and meet technical requirements, such as maintaining minimum UV dose levels and ensuring there is no leaching from any parts in the system. These NWRI/ USEPA and NSF/ANSI certifications are crucial in signaling that UV Pure technology meets globally recognized safety standards. For more information, visit www.uvpure.com. n

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www.boselec.com | uv@boselec.com 617-566-3821 | shop.boselec.com 2019 Quarter 3

| 43

FEATURED ARTICLE

SIZING AND DESIGN FOR UV AOP

Figure 1. Ultraviolet light-based advanced oxidation process. Courtesy of the Region of Peel.

Practical Information on Sizing and Design Approaches for UV AOP Systems Nathan Moore

Ph.D. candidate, University of Toronto

Erin Mackey

project manager and technical specialist, water and reuse, Brown and Caldwell, Inc.

Kati Bell

managing director of water strategy, Brown and Caldwell, Inc.

S

electing an ultraviolet light-based advanced oxidation process (UV AOP) for a specific application begins with a clear treatment goal (e.g., 90% destruction of 1,4-dioxane) and ends with manufacturer(s) recommending a UV reactor system that will achieve that goal for specified design conditions of flow, UV-T and background water quality. Among these points, there is the consideration of various factors that govern which reactor is most cost-effective from a capital and operations and maintenance (O&M) cost perspective.

The typical design engineer rarely has access to the models that equipment manufacturers use to determine the required size of equipment systems to meet treatment objectives. This can yield challenges for design engineers when the procurement processes required by many utilities often require competitive bids as part of the equipment selection process. This article aims to define common UV AOP bid language and terminology and clarify the approaches that are used in sizing UV AOP systems to support the designer in communications with manufacturers for UV AOP equipment sizing, selection and procurement.

Mechanism of UV AOP contaminant destruction The mechanism of contaminant destruction by UV AOP is a combination of direct UV photolysis (UV light breaking down contaminants directly) and oxidation of contaminants by radicals (generated via the photolysis of the oxidant). To be effective, photons must be absorbed by the contaminant molecule and/ or the hydrogen peroxide molecule. Generally, the most important factors impacting the efficiency of a UV AOP are UV transmittance (UV-T) of the water, scavenging characteristics (from nitrate, natural organic matter and alkalinity), pH, temperature and the activator chemical and dose.

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H2O2 H2O2 H2O2

Figure 2. Example of collimated beam data for various UV doses and hydrogen peroxide doses for 1,4-dioxane removal for a specific water source

Sizing UV AOP equipment systems Considering that the water quality cannot be changed, the sizing of a UV AOP system is limited to two key factors: the UV dose (fluence) and the oxidant dose. Manufacturers utilize water quality factors, along with proprietary models, to determine the optimal UV AOP sizing and operation of their systems (applied UV dose and oxidant dose). These differing approaches can make direct comparison of the performance and costs of various UV AOP systems a difficult endeavor.

This difficulty is primarily because of the determination of UV dose, which, with respect to a full-scale reactor, is the reduction equivalent dose (RED). Thus, UV dose is normalized (or weighted) by the chemical or biological actinometer such that there are many different types of UV doses (e.g., MS2 dose, NDMA dose, H2O2 dose, atrazine dose, etc.). Because most practitioners are accustomed to the term UV dose as it relates to disinfection, there can be confusion because the same reactor under identical flow conditions can have different delivered UV dose values based upon the target contaminant.

There are two general approaches that have arisen in development of UV AOP equipment sizing. The first is development and use of a reactor-specific deterministic model that uses an empirically measured scavenging factor (dependent upon site-specific water quality) to determine combinations of UV and oxidant doses that will meet the treatment objective. The second is a purely empirical approach uvsolutionsmag.com

that leverages a laboratory data set to determine the minimum UV dose and oxidant concentration required to achieve the treatment objective, coupled with a reactor validation using the target contaminant as the actinometer. In either case, the manufacturer will need water quality data and the treatment objective to size a reactor and develop a cost proposal.

Deterministic modeling using a scavenging factor Because of the challenges of actinometry at high UV REDs, some manufacturers have developed deterministic models that account for the many factors that must be considered in sizing a UV AOP reactor. These equations account for the kinetics of photosensitized reactions where UV light is absorbed by an oxidant to form a radical R∙ (e.g., OH∙), which then reacts with a contaminant. These radicals may also react with scavengers and, when a steady state approximation is applied, the kinetics can be simplified considerably: R = SF × n × RB In this equation, R is the rate of contaminant degradation, SF is the scavenging factor (s-1), and n is the number of RB radicals formed from the photolysis of oxidant activator, B (Collins and Bolton, 2016). In this approach, the scavenging factor is determined experimentally according to methods such as those outlined in Rosenfeldt and Linden (2007). continued on page 46

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SIZING AND DESIGN FOR UV-AOP continued from page 45

In this approach, the manufacturer combines water quality information (Table 1) with a reactor model to calculate contaminant destruction across the reactor. Manufacturers who use this approach can quickly assess the range of operating conditions that are needed using the model and the laboratory-determined scavenging factor. The benefit of this approach is that the model can be used to assess the impact of changes in the site-specific scavenging factor on equipment sizing and required oxidant dose.

Minimum UV and oxidant doses Water samples from a specific site can be used in collimated beam testing to evaluate a matrix of UV REDs and oxidant doses to determine the minimum required UV RED and oxidant doses required to meet the performance objective for a target contaminant (Figure 2). The minimum required values to achieve the desired treatment objective then can be used for equipment sizing based on the manufacturerâ&#x20AC;&#x2122;s UV validation models.

Because the relationship of log removal as a function of UV dose is linear, Bircher (2011) introduced the dose per log (DL) concept, which some manufacturers have found useful in the scale-up of bench-scale results to full-scale UV reactors.

Table 1. Factors that affect the required UV system power per log removal

Reactor-specific

Application-specific

Lamp type (e.g., low- vs. medium-pressure)

Target contaminant (concentration and reaction rates with radicals)

Lamp spacing

UV-T

Lamp orientation

pH

Path length of light in reactor

Temperature

UV reactor hydraulics

Scavenging capacity (concentration of scavengers) Flow rate Activator chemical (type and concentration)

However, the UV dose calculations for these applications do differ from disinfection applications. In the AOP application, the UV dose required per log removal is calculated based on the absorbance of the oxidant or target contaminant.

Thus, DL is a water quality parameter describing the number of photons needed to be absorbed by the activator chemical to destroy 90% of the target contaminant in a site-specific water. It is proportional to the number of photons required to be absorbed by the activator and can be used as a relative indicator of how easy it is to achieve the treatment objective for various contaminants in a site-specific water. For example, a more recalcitrant target contaminant will require more radicals in order to be degraded and thus will have a higher DL. Anything in the water that interferes with the AOP (e.g., radical scavengers) will lead to a higher DL. Because the DL is solely a property of the water being treated (including the target contaminant and activator chemical), the DL calculated using a lab- or bench-scale test will be the same as the DL for a full-scale reactor treating the same water.

Operations cost of a UV AOP system The initial equipment capital is only part of the cost that should be considered with respect to budgeting and selecting a UV AOP system. There are annual O&M costs that include cost of electricity consumption and demand charges, chemical oxidant, replacement parts and O&M labor. While

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the approach to conducting a full life-cycle evaluation of a UV AOP system is similar to a UV disinfection system, which has been presented elsewhere (Bell and Goldman, 2015), there are differences in calculation of annual power and oxidant costs that are worth highlighting here.

Because UV AOP involves a considerable input of electrical energy, the cost of electricity may become a major factor in the overall treatment costs and selection of a system. There are figures-of-merit that have been developed to reflect the efficiency of a given reactor in terms of the electrical energy in driving the degradation processes (Collins and Bolton, 2016).

First is the concept of electrical energy dose (EED), which is defined as the electrical energy (kWh) consumed per unit volume (e.g., 1 m3 or 1,000 gal) of water treated. Electrical energy per order (EEO; Bolton, et al. 2001), recommended by the Photochemistry Commission of International Union of Pure and Applied Chemistry (IUPAC), also has been widely used.

EEO describes the efficiency of a UV AOP technology as the amount of electricity needed to be given to the lamps to produce enough radicals to ultimately destroy 90% (1-log) of the target contaminant in a unit volume of water. The term is typically expressed in units of kWh/m3-log or kWh/kgal-log.

It is notable that EEO is not the same for every UV reactor or every water for a given reactor.

Rather, it depends on several reactor- and application-specific factors, including the hydraulic and optical design of a reactor, which also affects the AOP efficiency, and, thus, EEO and power cost. Importantly, the EEO for a system is also specific to the type and concentration of the activator chemical used because different chemicals absorb photons, produce radicals and scavenge radicals with different efficiencies.

Therefore, to use the DL to arrive at an EEO the manufacturer or utility would need to do collimated beam testing on a representative water sample to determine the contaminant degradation as a function of UV dose, noting that the method for calculating UV dose varies by lamp type (low- vs. medium-pressure), as is well described elsewhere (Bircher, 2015). The DL is the inverse slope of the graph of UV dose vs. log contaminant destruction.

The manufacturer then would use a reactor model to calculate the UV dose applied through the reactor and combine that with the DL to calculate the size and cost of the proposed reactor for treating the utilityâ&#x20AC;&#x2122;s water. However, if a manufacturer instead opts for full-scale testing using water from the installation site, which is generally impractical, it is not necessary to explicitly determine the DL since it will continued on page 48

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SIZING AND DESIGN FOR UV-AOP continued from page 47

be accounted for when measuring how much UV power is needed to destroy the target contaminant in that water.

Case studies Ultimately, regardless of the sizing approach used, sitespecific water quality information is necessary to size and design a UV AOP system. The following section highlights two case studies demonstrating how theses approaches have been successfully applied for different UV technologies to design and operate full-scale UV AOP systems.

Celina, Ohio, Drinking Water Treatment Plant (WTP) The Celina, Ohio, WTP’s source water can be high in algal toxins, such as microcystin, as well as the taste and odor compounds 2-methylisoborneol (MIB) and geosmin.

A Calgon Carbon Sentinel® UV AOP system was installed in 2017 to provide an additional barrier for these compounds, as well as for virus disinfection. The system – consisting of two trains, each with two Sentinel® 12 UV reactors – can be run in disinfection mode for 4-log virus inactivation or AOP mode for microcystin or MIB treatment. Each UV reactor has three 4-kW medium-pressure UV lamps and is designed to treat three MGD with four to 15 mg/L of hydrogen peroxide added when in oxidation mode. The control strategy uses the UV sensitivity or DL in the equation for the reactor developed in validation.

Where logi is the log removal of microcystin or MIB or the log inactivation of virus, UV-A is the UV absorbance of the water, S/S0 is the relative lamp output as measured by the UV sensor and Q is flow.

For AOP, DL is dependent on the water quality but independent of reactor technology or hydraulic efficiency and is calculated from the UV absorbance (as a proxy for TOC), pH and concentration of dosed hydrogen peroxide. This equation can be used for AOP because the peroxide-weighted fluence (dose) is approximately equal to the germicidal weighted dose.

Terminal Island Water Reclamation Plant (WRP) The UV AOP for the Terminal Island WRP uses two K143 12/17 UV reactors manufactured by Xylem-Wedeco. Each reactor is partitioned into 17 rows of 12 lamps in series. The reactors were designed using the DL method for reduction of 1,4-dioxane with a target of 0.5-log 1,4-dioxane reduction.

Knowing the DL from the bench- and pilot-scale testing allows selection of a real-time UV dose. The algorithm used for the

48 | UVSolutions

Regardless of the approach, it is important to capture both the equipment capital and the O&M costs to reflect the total lifecycle cost of a UV AOP system.

K143 has been verified by computational fluid dynamics and confirmed with collimated beam testing.

As noted, water quality is important given the potential for scavenging of hydroxyl radicals, and to monitor delivery of UV dose, the system controller uses UV intensity, UV-T and flow to calculate the power input required to achieve the target UV dose.

Recommendations for UV AOP specification Several different approaches and terms are used in the design and sizing of UV AOP systems. Regardless of the approach, it is important to capture both the equipment capital and the O&M costs to reflect the total lifecycle cost of a UV AOP system for meeting a given treatment performance objective.

An equipment specification can be developed to support bids using multiple approaches by defining the treatment objective, e.g., 0.5-log removal of 1,4-dioxane, and allowing the UV vendors to size their equipment to meet this requirement.

Once the cost proposal has been obtained for a manufacturersized system, the engineer can utilize liquidated damages or other performance guarantee approaches to ensure that the power consumption and hydrogen peroxide doses for the UV AOP operations do not exceed the manufacturer’s bid for power consumption or oxidant dose (i.e., the owner’s costs do not exceed the guarantee specified in the bid). n The authors gratefully acknowledge Calgon Carbon Corporation and Xylem-Wedeco for providing the case studies presented here.

Contact: Nathan Moore, Nathan.moore@mail.utoronto.ca; Erin Mackey, emackey@brwncald.com; Kati Bell, kbell@ brwncald.com For full list of references, www.uvsolutionsmag.com.

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LEDs IN HEALTHCARE FEATURED ARTICLE

Critical Roles for Germicidal LEDs in Healthcare Delivery Facilities

I

nfectious diseases are caused by various pathogens: vegetated bacteria, bacterial spores, virions and fungus. Once transferred upon or introduced into a susceptible patient’s body, these pathogens – some of which are now antibiotic-resistant – replicate and can cause an infection and illness, sometimes resulting in great discomfort and even death. Pathogens find their way to victims by way of contaminated food, suspect water, aerosolized pathogens floating in air or attached to dust and skin flakes, human contact with pathogen-contaminated surfaces, or human-to-human contact made during patient care. The preponderance and the associated danger of infectious pathogens in a healthcare delivery environment has been shown to be severely problematic. In 2011, 721,800 healthcare-associated infections (HAIs) were reported in the US, with more than 7,500 deaths and an estimated cost to the healthcare system of $30 to $40 billion annually.1

Peter Gordon

VP of business development, Bolb Corporation

The reduction of HAIs has subsequently become a top priority for healthcare facilities, with the highest emphasis placed on effective environmental hygiene. Almost $10 billion per year is spent on hand hygiene, decontamination of high-touch environmental surfaces, and on sanitizing portable biomedical devices, data-recording tablet computers and diagnostic equipment in order to sever pathogen transmission pathways in US hospitals. However, many studies have shown that all three processes are often inadequate. For example, a study in 2008 found that 50% or more of high-touch surfaces may be routinely missed during daily cleaning.2 The improper choosing or misuse of expensive and, at times, toxic cleaning chemicals can result in inadequate disinfection; environmental surfaces and equipment remain contaminated with pathogens, exposing patients and healthcare workers to pathogen transfer from contact with such contaminated surfaces. Such slovenly coverage greatly raises the risk for the transmission of pathogens to patients, visitors and healthcare workers and the resultant manifestation of HAIs. Alternative approaches for achieving and maintaining the highest levels of environmental hygiene in hospitals are sorely needed continued on page 50

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LEDs IN HEALTHCARE continued from page 49

Gooseneck lamp configuration. Courtesy of LiTeProducts LLC. Feature 1500: Switchable from UV-C mode to V mode, sequentially or in combination. Feature 1502: UV-C LED emitters and drive electronics focused on a specific target.

Feature 1504: 405 nm LED emitters and drive electronics focused on a specific target. Feature 1506: Mode selection and timer; 360-degree movement and occupancy sensor override. Feature 1510: Articulated adjustable length arm for aiming, and securing in place, the optical output of LED emitter toward the targeted inactivation area. Feature 1520: Configurable reflective lamp shade for guiding and directing light onto surfaces.

to prevent such spread of hospital pathogens. There is clearly an unmet need for effective methods of pathogen inactivation on targeted surfaces that can be conveniently implemented to reduce dangerous pathogen loads.

Potential for germicidal light-based solutions One method that has been gaining momentum is the episodic use, efficacy and convenience of germicidal ultraviolet (UV-C) light applied to environmental cleaning of unoccupied hospital rooms and operating theaters. It has become more established in recent years, showing very promising results.3 However, the deployment of the assortment of no-touch ultraviolet disinfection systems on the market do have acknowledged operational limits.

For example, they can only be operated episodically in unoccupied space due to human safety requirements and are only validated for use on hard surfaces.4 As a result, hightraffic areas, fast turnaround places, hard-to-reach surfaces and unforeseen use of equipment due to unanticipated procedures and accidental spillages pose a particular

50 | UVSolutions

challenge to fully taking advantage of the benefits of such high powered germicidal light surface disinfection delivery systems, limiting their wider deployment.

In response to this utilization gap, a series of published research raised the possibility of using germicidal visible light wavelengths for continuous sanitation of environmental surfaces during room occupancy. The most effective wavelength for this technique differs from the effective wavelength for UV-C. It resides in the blue part of the visible spectrum, with peak activity at a wavelength of approximately 405 nm, and its use is being positioned as a means to cull the pathogen counts and assist keeping accessible hard surfaces cleaner in between manual chemical treatment.5 It is claimed that absorption of 405 nm light by intracellular molecules induces production of reactive oxygen species, and this causes inactivation of pathogens. This kill method has been verified, and it has been acknowledged that the inactivation rate of 405 nm is much lower than that of UV-C for the same applied dose, but a much longer dwell time is required to achieve a meaningful degree of reduction.6,7 uvsolutionsmag.com

Given the stated use of 405 nm light during room occupancy â&#x20AC;&#x201C; as an operational departure from use of UV-C in unoccupied space â&#x20AC;&#x201C; it is vitally important that exposure to 405 nm has been demonstrated to be harmless to humans, with a possible exception for interruption of sleep/wake cycles. Germicidal 405 nm light falls outside of the unsafe for human exposure UV wavelength band and, as a result, OSHA does not consider 405 nm problematic and publishes no guidance on skin exposure limits. Published papers have demonstrated the safety and efficacy for use of 405 nm light to reduce acne vulgaris infections located deep within skin pores,8 and the FDA has issued 510K market clearance for medical treatment devices based upon these findings.9 These are clear indicators of skin safety.

Therefore, the overhead light fixtures populated with 405 nm emitters can be used during room occupancy. However, for completeness, it also is important to note that OSHA does set limits for eye exposure to 405 nm light, and any use of 405 nm light must be tested to conform to the other available international standards.10 After a trial safety and efficacy validation, one US hospital has implemented the approach in ceiling fixtures, attempting to suppress pathogen loads on operating theater and patient care room continued on page 52

Conventional lamp and UV-C LED emitters. Image courtesy of Bolb Corporation.

Your OEM Specialist for

Lamp Drivers Control Units UV Monitoring UV Measurement UV-C Lamp Optimization

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 | info@z-e-d.com | www.z-e-d.com

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LEDs IN HEALTHCARE continued from page 51

surfaces during healthcare worker and recovering patient occupancy.11 Each independent approach, episodic use of UV-C or continuous use of 405 nm, has its time and place, benefits and tradeoffs,12 entrenched supporters and detractors.

Not surprisingly, there is no coordination or crossover of implementation, even though there should be, to the benefit of patients and hospital environmental services workers, and as a cost containment approach. To the detriment of all such stakeholders, no bridge has yet been constructed.

However, one innovative approach that holds great promise has been suggested as a critical first span.13 It outlines the coupling of the established benefits of the UV-C, between room occupancy episodic mode (UV-C mode), with the burgeoning visible light, during room occupancy continuous suppression mode (V mode). The objective is to more fully maximize germicidal light acceptance and greatly reduce pathogen loads on critical surfaces to the benefit of patients and hospital administrators alike. Such a dual mode system, with the ability to switch between modes either by planned scheduling or by opportunity, offers high potential for enhanced efficacy and convenience, and would certainly result in a higher degree of surface sanitation on demand or 24/7 than currently achieved, leading to more patient and worker protection and greater cost savings.

Almost $10 billion per year is spent on hand hygiene, decontamination of high-touch environmental devices, and on sanitizing portable biomedical devices, data-recording tablet computers and diagnostic equipment in order to sever pathogen transmission pathways in US hospitals. germicidal lamps, so arrays of them must be placed very close to the target surface to produce high surface intensity, which limits their positioning and coverage.

However, even with these current operational limits, GLEDs are being positioned to be the next wave in the LED lighting revolution. They present a new technological solution with enormous potential, episodically, for control of accumulated pathogen levels.

Use of germicidal LEDs for a dual mode system Germicidal light-emitting diodes (GLED) are promising as a new source for pathogen inactivation in healthcare settings.14 Although, to date, LEDs emitting in the ultraviolet range have only been nominally explored for their implementation soundness and veracity of claims,15 with only cursory coverage given to their possible benefits,16 GLED-based emitters – like their white light emitting counterparts – are small, robust, relatively low cost, require no warm-up time and contain no toxic elements.

As GLEDs emitting in the ultraviolet range (UV-C LED) continue to exhibit improved wall plug efficiencies, the case for deployment of such devices to address HAI reduction will become even more compelling.17

In addition, GLEDs enable flexible mechanical design over rigid, straight, conventional low-pressure mercury germicidal lamps and their required bulky ballasts, allowing more flexible and configurable light delivery to specific target areas. These attributes make them an ideal light source for the more mundane single wavelength solutions and – since they can additionally emit light at multiple individual wavelengths, providing fine tuning and selectivity – they are well suited for the envisioned, value added, dual germicidal wavelength/dual mode surface treatment solution.

Similar studies, concerned with food safety, have been conducted with LEDs operating in the visible region (405 nm, 464 nm)19, and, most relevant to the premise of combinatory dual mode action, the effectiveness of using combinations of UV-C and visible light germicidal lamps to inactivate pathogens can be traced back to a 1978 paper by Tyrrell and Peak.20

Problematically, the specific challenge with GLEDs is that they are still weak emitters compared to conventional

52 | UVSolutions

Many studies have analyzed the response of different microbial strains to UV-C LED irradiation, as well as the effectiveness of UV-C LEDs with interleaving of LEDs emitting in the bactericidal UV-C range from 255 and 280 nm.18

But only recently published was follow-up work that took advantage of the advent of easier to experiment with arrays of GLED sources and the compelling indicator of the importance of sequential order on efficacy for extending the shelf life of cut produce.21 uvsolutionsmag.com

care equipment, diagnostic equipment, or chairs, tables and beds – as long as the uniform intensities requirements are met.22

Nimble and targeted disinfection

Optimized wavelengths High intensity

Solid-state

Compact

Non-toxic

Smart

Residue-free

Robust

Summary of attributes of germicidal LEDs applied to healthcare delivery facilities

However, the specific, situational and operational advantages of a dual mode approach in healthcare settings have yet to be verified. Such a solution combining 405 nm LEDs, for their safer yet weaker efficacy in a continuous pathogen suppression capacity (V mode) with UV-C LEDs, taking advantage of their greater efficacy – avoiding their inherent harmful effects on human vision and skin – for the heavy lifting episodic pathogen reduction mode (UV-C mode) will be ground-breaking.

One possible configuration The aim of the solution is the delivery of germicidal light emitted by LEDs to the entire surface area of various irregular shaped objects that are specifically designated pathogen hotspots and troublesome to keep clean high-touch areas. The illumination would be achieved by unique use of targeted illuminating LED arrays of selected wavelengths situationally, depending on the nature of the work environment.

The range of the system may be up to one meter away from the dual emitters in order to cover larger targets but not be too great to avoid intruding on occupied space. The targeted inactivation areas illuminated by such a sanitizing system could be square, rectilinear, polygonal, circular or elliptical, and it may not necessarily be planar.

Similar to the well-understood mechanics of germicidal UV-C inactivation of pathogens, the effectiveness of the visible light-emitting fixture in inactivating pathogens on a surface depends on the dose of germicidal light irradiating the surface. The number of pathogens inactivated by either UV-C or visible light will vary with the irradiance and the length of exposure, so rigorous efficacy testing, using the most up-to-date microbiological challenge practices, must be undertaken.23 Placement of the dual wavelength emitter coupled with a timed exposure generated by UV-C LEDs and visible light accomplishing repeatable, consistent and accurate surface sanitation, would introduce less restrictive operational requirements, safer work conditions for nurses, and overall greener and healthier facilities. The implementation is an ideal utilization taking advantage of the attributes of GLEDs summarized in the graphic on this page.

Conclusion The application of a dual operational mode, germicidal, LED-based decontamination system to optimize surface sanitation of portable biomedical, data-recording tablet computers and diagnostic equipment in acute care settings could help achieve the long-term goal of protecting recovering patients from exposure to infectious pathogens. It would improve patient outcomes by providing a safer environment of care and lowering the rates of HAIs. Additionally, the deployment of such systems could further protect healthcare workers, specifically nurses, from exposure to the same set of infectious pathogens, providing a cleaner and safer workplace during patient interaction.

Finally, such solutions would offer cost savings to hospital management seeking to lower reliance on toxic antimicrobial agents and chemicals and the administration of increasingly pathogen-resistant antibiotics. n Contact: Peter E. Gordon, pgordon511@yahoo.com For full list of references, www.uvsolutionsmag.com.

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CALENDAR OF EVENTS Sept. 21-25, 2019 WEFTEC 2019 Chicago, Illinois weftec.org

Nov. 5-8, 2019 Aquatech Amsterdam, Netherlands aquatechtrade.com

Sept. 24-26, 2019 16th annual EPA Drinking Water Workshop Cincinnati, Ohio epa.gov/water-research

Nov. 18-19, 2019 IUVA Symposium: Workshop of UV Light and Ozone-Based Technologies for Water Treatment and Reuse Bangkok, Thailand iuva.org

Oct. 15-16, 2019 RadTech Europe Munich, Germany radtech-europe.com

AD INDEX 2020 IUVA Americas Conference.............. iuva.org/2020-Americas-Conference................................ 3 Allanson Lighting Technologies Inc.......... allanson.com..................................................................................11 American Air and Water................................. prismuv.com................................................................................ 35 American Ultraviolet......................................... americanultraviolet.com........................................................ 33 AquiSense Technologies................................. aquisense.com.............................................................................21 Boston Electronics............................................ boselec.com................................................................................ 43 DOWA...................................................................... ultraviolet-led.com.....................................................................15 Enaqua.................................................................... enaqua.com.................................................................................... 7 eta plus.................................................................... eta-uv.com................................................................................... 35 GenUV..................................................................... geni-uv.com.................................................................................. 16 IUVA.......................................................................... iuva.org.......................................................................................... 47 Light Sources....................................................... light-sources.com...................................................................... 41 Nedap...................................................................... nedap-uv.com............................................................................ 29 Neotec UV............................................................. neotecuv.com........................................................................... IBC Philips....................................................................... philips.com/uvpurification.................................................. BC Ushio......................................................................... ushio.com................................................................................... IFC UV Lamp Consulting........................................ uvlampconsulting.com............................................................ 19 UV Pure................................................................... uvpure.com.................................................................................. 23

UV Solutions......................................................... uvsolutionsmag.com............................................................... 23 UV-Technik............................................................. uvtechnik.com............................................................................46 ZED........................................................................... z-e-d.com.......................................................................................51

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