5th international cong res s on ultraviolet technolog...

Thanks to our Primary Sponsor:

Amsterdam, The Netherlands21-23 September, 2009

NH Grand Hotel Krasnapolsky

5th International Congress on Ultraviolet

Technologies

http://www.iuva.org

http://www.wedeco.com

5th UV World Congress Schedule at a GlanceAmsterdam - 2009

Primary Sponsor: ITT Water & Wastewater

- REGISTRATION DESK HOURS -

Sunday, 20 September 2009

12:00 - 17:00Exhibitor Set-Up in Exhibit Hall

14:00 - 16:00Manufacturer’s Council Meeting

18:00 - 21:00 IUVA Board Meeting

Monday, 21 September 2009

9:00 - 10:00Welcome Coffee, Please join us in the Grand Ballroom

10:00 - 12:30Opening Plenary Session

12:30 - 13:30World Congress Luncheon

13:30 - 15:10Session A1 - Drinking Water TreatmentSession B1 - Component Design (sensors, lamps, reactors)Session C1 - Waste Water

15:10 - 15:55Coffee Break

15:55 - 17:35Session A2 - Drinking Water TreatmentSession B2 - Component Design (CFD) Session C2 - Photochemistry

17:35 - 19:30Welcome Reception, Grand BallroomPlease join us at the conclusion of today’s technical sessions for refreshments & hors d'oeuvres.

Tuesday, 22 September 2009

9:00 - 10:15Session A3 - Advanced OxidationSession B3 - Certification / ValidationSession C3 - Photochemistry


10:50 - 12:30Session A4 - Advanced OxidationSession B4 - Certification / ValidationSession C4 - Photobiology

12:30 - 13:30World Congress Luncheon

13:30 - 15:10Session A5 - Advanced OxidationSession B5 - UV MeasurementSession C5 - Photobiology


15:55 - 17:35Session A6 - Water Disinfection / Water ReuseSession B6 - Biofouling and RegrowthSession C6 - Photobiology

19:00 - 23:00President’s Banquet

SUNDAY12:00 - 16:00

MONDAY8:00 - 12:30

13:30 - 17:00

TUESDAY8:00 - 12:30

Wednesday, 23 September 2009

8:00 - 16:00UV Technical Tour (includes transport & lunch)

9:00 - 16:00Regulatory Workshop - Drinking Water (includes lunch)

I N T E R N A T I O N A L U L T R A V I O L E T A S S O C I A T I O N

PLEASE NOTE THAT THE DESK WILLNOT BE OPEN DURING LUNCH, BUT

WILL OTHERWISE BE AVAILABLE FORALL OF YOUR WORLD CONGRESS

NEEDS. THANK YOU!

INTERNATIONAL ULTRAVIOLET ASSOCIATIONPO Box 28154 Scottsdale, AZ 85255 USA

T: +1 480.544.0105 F: +1 480.473.9068 www.iuva.org

http://www.iuva.org


http://docs.iuva.org/Regulatory_Workshop_Amsterdam.pdf

http://www.iuva.org

http://www.iuva.org/sites/default/files/2009%20technical%20tour.pdf

IUVA 5th UV World Congress – 21-22 September, 2009 – Amsterdam, The Netherlands

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Dear Participant,

Thank you for joining us at the International Ultraviolet Association’s 5th UV World Congress, being held this year at the NH Grand Hotel Krasnapolsky, in Amsterdam, The Netherlands. We are pleased that you have chosen to attend this event. This year is particularly special as the IUVA celebrates its 10th Anniversary. We have come a long way from out humble beginnings, and the future is bright. In addition to an outstanding and truly global technical program, the 5th World Congress features supplemental events - a UV Regulatory Workshop as well as a UV Technical Tour - that provides an inside look at some of The Netherlands’ most advanced Drinking Water Plants.

UV directly improves our quality of life. The strong technical contributions of this year’s speakers will make that abundantly clear. We proudly present this diverse and comprehensive look at UV, and thank our talented speakers for their time and effort. Special thanks to our plenary speakers, Dr. Don Bursill of Australia, Dr. Urs von Gunten of Switzerland, and Dr. Joop Kruithof of The Netherlands who will round out the technical program with their insights.

We especially wish to acknowledge the work of Professor Dr. Regina Sommer, who coordinated all of the sessions as well as organized all of the abstracts and papers for this unique technical program, with the assistance of the Technical Review Committee listed below. Additionally, we greatly appreciate the local insight of our Organizing Committee, also listed below. Many thanks to our hosts, Evides and PWN, for inviting us into their showcased facilities as well as to EAWAG for hosting this year’s UV Regulatory Workshop in partnership with the IUVA. Thanks also to our Primary Conference Sponsor, ITT Water & Wastewater. We greatly appreciate the support of all of our generous exhibitors and sponsors, who make this World Congress possible.

Welcome and enjoy!

Linda Gowman, Ph.D., P.Eng. IUVA President Technical Program Committee Chair - Prof. Dr. Regina Sommer, Medical University Vienna - Dr. Andreas Kolch, HYTECON GmbH - Joop C. Kruithof, Ph. D., Wetsus Centre for Sustainable Water Technology - Professor James P. Malley, Jr., Ph. D., University of New Hampshire - Paul Overbeck, IUVA - Diana Schoenberg, IUVA

Local Organizing Committee - Joop C. Kruithof, Ph. D., Wetsus Centre for Sustainable Water Technology - Guus F. IJpelaar, Royal Haskoning

WELCOME MESSAGE & ORGANIZING COMMITTEE


ORAL PRESENTATIONS

Monday 21 September 2009 9:00 – 10:00 Welcome Coffee, Grand Ballroom

General Opening Session – Monday 21 September, 2009 St. John’s Room 1 & 2 10:00 12:30 Welcome by Linda Gowman Ph.D., P.Eng. Guest Speakers: Prof. Don Bursill, Prof. Urs von Gunten and Joop C. Kruithof, Ph.D.

12:30 – 13:30 Luncheon, Winter Garden Session A1 – Drinking Water Treatment – Monday 21 September, 2009 St. John’s Room 2 Start End Title Authors Affiliations

13:30 13:55 UV in Drinking Water Treatment – Issues for the Next Decade - 2010 to 2020

James P. Malley, Jr. University of New Hampshire

13:55 14:20 UV System Technology Selection for Metro Vancouver’s Coquitlam UV Disinfection Project

Christopher R. Schulz1, Ayman Shawwa1, and Inder Singh2

1CDM Inc., 2Metro Vancouver

14:20 14:45 Metro Vancouver’s New 1,200 MLD Coquitlam UV Disinfection Facility – an Example of Innovative and Sustainable Design

Inder Singh Metro Vancouver

14:45 15:10 San Francisco Uses a Design-Build Approach to Implement a 315-MGD UV Disinfection Facility

Michael L. Price1, Bijan Ahmadzadeh2, Matthew Moughamian1, and Jamal Awad1

1MWH Americas, Inc., 2San Francisco Public Utilities Commission

Session B1 – Component Design – Monday 21 September, 2009 St. John’s Room 1 Start End Title Authors Affiliations

13:30 13:55 Sustainability and Disinfection: How to Incorporate Life Cycle Assessment into Wastewater Disinfection Design

Gary L. Hunter1, Ed Kobylinski1, Leonard W. Casson2, and Ben Freese1

1Black & Veatch, 2University of Pittsburgh

13:55 14:20 Medium Pressure Mercury Lamps for AOP/TOC

Alex Voronov, M. Kessler, and R. Dreiskemper

Heraeus Noblelight GmbH

14:20 14:45 Comparison Testing of ‘Spot’ vs. ‘Pellet’ LPHO UV Lamps

Michael J. Santelli1 and James R. Bolton2

1Light Sources, Inc., 2Bolton Photosciences Inc.

14:45 15:10 Renaissance of Medium Pressure Lamps Driven by High Frequency Lamp Driver

Alex Voronov1, Volker Adam1, G. van Eerden2, and T. Telgenhof2

1Heraeus Noblelight GmbH, 2Nedap Light Controls

Session C1 – Waste Water – Monday 21 September, 2009 Volmer Room 1 & 2

Start End Title Authors Affiliations

13:30 13:55 A Practical Case Study for Wastewater UV Disinfection: Evaluation of Quartz Sleeve Mechanical Wiping System Performance & Resultant Fouling Factors

Bruno Ferran, Wei Yang, and Robert Kelly

Infilco Degremont, Inc. - Degremont North American Research & Development Center

13:55 14:20 Comparing UV Validation of Waste Water UV Reactors Using USEPA Drinking Water and NWRI/AwwaRF Guidance

Harold Wright1, Andrew Salveson1, and Suzie Sarkis2

1Carollo Engineers, 2Environmental Health Unit, Public Health Branch, Department of Human Services

14:20 14:45 Bioassays for Secondary Wastewater UV Systems – Is a Standard Possible?

Matthias Boeker ITT Water & Wastewater U.S.A. / WEDECO Products

15:10 – 15:55 Coffee Break, Grand Ballroom

TECHNICAL PROGRAM


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Session A2 – Drinking Water Treatment – Monday 21 September, 2009 St. John’s Room 2


15:55 16:20 State of the Art of Production of Harmful Disinfection By-Products: Fact or Fiction

Joop C. Kruithof1,

Bram J. van der Veer2

and Bram Martijn3

1Wetsus Centre for Sustainable Water Technology, 2Evides Water Company, 3PWN Waterleidingbedrijf, Noord-Holland

16:20 16:45 Comparison of Ozone and UV Disinfection Processes Within the Scope of the Dutch Risk Analysis for Pathogens

Bram J. van der Veer1, P.W.M.H. Smeets2 and J.C. van Dijk3

1Evides Water Company, 2KWR Watercycle Research Institute, 3Delft University of Technology

16:45 17:10 Water Purification for Developing Countries, Design and Results

Tonnie Telgenhof Oude Koehorst NEDAP Light Controls

17:10 17:35 Public Water Works: How Safe is UV Disinfected Drinking Water? Quality Management Once and Now

Regina Sommer1, Alexander Cabaj2, Georg Hirschmann3, Thomas Haider4 and Alexander Kirschner1

1Medical University Vienna, Hygiene-Institute2Departement of Medical Physics, Veterinary Medical University Vienna 3Arsenal Research Vienna 4Medical University Vienna, Institute of Environmental Health

Session B2 – Component Design – Monday 21 September, 2009 St. John’s Room 1


15:55 16:20 Design of Hydraulically Optimized UV Systems Using CFD

Bas Wols1,2, J.A.M.H. Hofman1,2,3, E.F. Beerendonk1, W.S.J. Uijttewaal2, and J.C. van Dijk2

1KWR Watercycle Research Institute 2Delft University of Technology 3Waternet

16:20 16:45 The Impact of Refraction on the Radiation Field in UV Photoreactors

Azita Soleymani, Domenico Santoro, and Mike Sasges

Trojan Technologies, Inc.

16:45 17:10 CFD Analysis of UV-Disinfection Systems M. Hunze and Arthur Schubert FlowConcept GmbH

17:10 17:35 CFD as a Tool to Predict Certification Results (DVGW, ÖVGW, SVGW)

Christoph Dicks AQUAFIDES GmbH

Session C2 – Photochemistry – Monday 21 September, 2009 Volmer Room 1 & 2


15:55 16:20 Determination of the Quantum Yield of the Ferrioxalate and KI/KIO3 Actinometers and a Method for the Calibration of Radiometer Detectors

James R. Bolton1, Mihaela I. Stefan2, Ping-Shine Shaw3, and Keith R. Lykke3

1Bolton Photosciences, Inc., 2Trojan Technologies, Inc., 3National Institute of Standards and Technology (NIST)

16:20 16:45 Kinetics and Quantum Yield Analysis for Vacuum UV (VUV) Photoreactors

Gustavo E. Imoberdorf and Madjid Mohseni

University of British Columbia

16:45 17:10 Efficiency Of Surface and Air Disinfection from Bacterial and Fungal Microflora Under the Effect of Continuous and Impulse UV Irradiation

Vladimir I. Sigaev1, A.V.Vorobyov1, A.D.Tolchinsky1, S.G.Shashkovsky2, S.N.Uspenskaya1, A.N.Varfolomeyev1, I.A.Zhelayev2, and E.V.Zvyuagina1

1SFES "Research Centre for Toxicology and Hygienic Regulation of Biopreparations” at FMBA RF 2Bauman Moscow State Technical University

17:35 – 19:30 Welcome Reception, Grand Ballroom


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Tuesday 22 September 2009

Session A3 – Advanced Oxidation – Tuesday 22 September, 2009 St. John’s Room 2


9:00 9:25 Potential for Advanced Oxidation Processes (AOPs) in Disinfection and Simultaneous Emerging Contaminants Removal: a Review

Cosima Sichel Siemens Water Technologies

9:25 9:50 Efficacy of UV Advanced Oxidation and Direct Photolysis Processes in a Drinking Water Utility with Full-Scale Granular Activated Carbon

Deborah H. Metz1, Maria Meyer1, Ramesh Kashinkunti1 and Erwin F. Beerendonk2

1Greater Cincinnati Water Works 2KWR - Watercycle Research Institute

9:50 10:15 UV/H2O2 AOP for Water Treatment: Fundamentals and Full-Scale Applications

Christian Williamson, Mihaela I. Stefan, Alan Royce, Adam Festger and Neil Brown

Trojan Technologies

Session B3 – Certification / Validation – Tuesday 22 September, 2009 St. John’s Room 1


9:00 9:25 UV Reactor Challenges with a High Resistance Surrogate for Adenovirus Credit

Brian Petri1 and Conrad Odegaard2

1Trojan Technologies 2GAP Enviromicrobial Services Ltd.

9:25 9:50 How the UVDGM 2006 Impacts UV Disinfection System Performance

Matthias Boeker ITT Water & Wastewater, U.S.A.

9:50 10:15 Impact of Biodosimetry-Based Validation on UV System Design Specifications

Bryan Townsend and Gary Hunter

Black & Veatch

Session C3 – Photochemistry – Tuesday 22 September, 2009 Volmer Room 1 & 2


9:00 9:25 Effectiveness of Ultraviolet Irradiation in Dechlorination as Influenced by Ultraviolet Transmittance

MP Astuti1, Rongjing Xie2 and MJ Gomez2

1Water Distribution and Network Department 2Centre for Advanced Water Technology Public Utilities Board of Singapore

9:25 9:50 Investigation on the Generation Amount of Nitrite During UV Irradiation Using Medium-Pressure UV Lamps

Nobuhito Yasui1 and Naoyuki Kamiko2

1Ritsumeikan University, Department of Integrated Science and Engineering 2Ritsumeikan University, Department of Environmental System Engineering

9:50 10:15 Intensification of Photocatalytic Process for Industrial Wastewater Treatment with a “Solid” UV Reactor

Jiang Yu, Dan Zhang Qiuxin Yang and Dandan Huang

Beijing University of Chemical Technology



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10:50 11:15 Reduction of Trietazine from Groundwater by UV

Barrie Holden and Angela Richardson

Anglian Water Services, Ltd.

11:15 11:40 Impact of Advanced Pretreatment on the Feasibility of UV/H2O2 Treatment for Degradation of Organic Micropollutants

Ashlee Fuller1, Bram Martijn2, Joop C. Kruithof3 and James P. Malley, Jr.1

1University of New Hampshire 2PWN Water Supply Company North Holland3Wetsus Centre for Sustainable Water Technology

11:40 12:05 Simultaneous Disinfection and Trace Organic Oxidation: Performance and Cost Comparisons Between Advanced Oxidation Technologies

Jeff Bandy1,2, Andy Salveson2 and Tavy Wade2

1Duke University 2Carollo Engineers

12:05 12:30 New DBD Lamp Combines the Advantages of the LP and MP UV Lamps for UV/H2O2 Oxidation

E.F. Beerendonk1, L. J.J.M. Janssen1, D.J.H. Harmsen1, D.H. Metz2, A.H. Knol3, J. Geboers4, G.F. IJpelaar1,5

1KWR, Watercycle Research Institute 2Greater Cincinnati Water Works 3Duinwaterbedrijf Zuid-Holland 4Philips Lighting BV 5Royal Haskoning

Session B4 – Certification / Validation – Tuesday 22 September, 2009 St. John’s Room 1


10:50 11:15 Biodosimetry of a Full-Scale UV Disinfection System to Achieve Regulatory Approval for Drinking Water Disinfection

Bruno Ferran, Wei Yang and Robert Kelly

Infilco Degremont, Inc.

11:15 11:40 Closing the Gap Between Certification (DVGW, ÖVGW, SVGW) and PSS?

Christoph Dicks AQUAFIDES GmbH

Session C4 – Photobiology – Tuesday 22 September, 2009 Volmer Room 1 & 2


10:50 11:15 Enhanced Effectiveness of Medium-Pressure UV Lamps on Human Adenovirus and its Possible Mechanism

Gwy-Am Shin1, Jung-Keun Lee1 and Karl G. Linden2

1University of Washington 2University of Colorado at Boulder

11:15 11:40 UV Reactor Challenges with Adenovirus: A Comparison of Adenovirus and MS2 Inactivation in Low Pressure and Medium Pressure UV Reactors

Brian Petri1, Karl Linden2 and Jeanette Thurston3

1Trojan Technologies 2University of Colorado, Boulder 3United States Department of Agriculture

11:40 12:05 A Genomic Model for Predicting the Ultraviolet Susceptibility of Viruses and Bacteria

Wladyslaw Jan Kowalski Immune Building Systems, Inc.

12:05 12:30 Impact of Antecedent Cultivation Conditions on the UV-C Resistance of Escherichia coli and Spores of Bacillus subtilis

Margarete Bucheli-Witschel, Claudio Bassin, Bernhard Roos and Thomas Egli

Eawag, Swiss Federal Institute of Aquatic Science and Technology

12:30 – 13:30 Luncheon, Winter Garden


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13:30 13:55 Selecting Removal Goals for Advanced Oxidation with UV and Hydrogen Peroxide

Jeff Neemann, Bryan Townsend, Bob Hulsey and Gary Hunter

Black & Veatch

13:55 14:20 UV Treatment for the Reduction of Metaldehyde in Surface Waters

Barrie Holden1, Ella Lamming1 and Alan Royce2

1Anglian Water Services, Ltd. 2Trojan Technologies

14:20 14:45 Genotoxicity Study on UV/H2O2 Treated Surface Water Using Comet and SCE Assay

Eric Penders1, Bram J. Martijn2, Wim Hoogenboezem1 and Gerrit M. Alink3

1Het Waterlaboratorium 2PWN Water Supply Company North Holland 3Wageningen University

14:45 15:10 Formation and Removal of Genotoxic Activity During UV/H2O2-GAC Treatment of Drinking Water

Minne B. Heringa1, D.J.H. Harmsen1, A.A Reus2, C.A.M. Krul2, A.H. Knol3, D.H. Metz4, E.F. Beerendonk1 and G.F. IJpelaar1

1KWR, Watercycle Research Institute 2TNO Quality of Life 3Duinwaterbedrijf Zuid-Holland 4Greater Cincinnati Water Works

Session B5 – UV Measurement – Tuesday 22 September, 2009 St. John’s Room 1


13:30 13:55 Measurement of the UV Output and Efficiency of Medium Pressure UV Lamps

James R. Bolton1, Keith Bircher2 and Brad Crawford2

1Bolton Photosciences, Inc. 2Calgon Carbon Corporation

13:55 14:20 Comparison of the Microbicidal Efficiency of Low Pressure and of Medium Pressure Mercury Lamps

Alexander Cabaj1, Regina Sommer2 and Thomas Haider3

1Veterinary University Vienna 2Medical University Vienna 3Institut für Umwelthygiene Medizinische Universität Wien

14:20 14:45 Comparison of UV Power Measurement of Low Pressure UV-lamps by a worldwide Round Robin Test

Volker Adam, Martin Kessler and Ralf Dreiskemper

Heraeus Noblelight, GmbH

14:45 15:10 Implementation of the European Directive on Optical Radiation Safety Takes Place in May 2010

Fokko P. Wieringa1,2 1TNO Science & Industry 2Scientific Advisory Board of Radtech Europe



13:30 13:55 Chlorine and UV Disinfection of Selected Antibiotic-Resistant Strains of Escherichia coli

Michael R. Templeton1, Francine Oddy1, Wing-kit Leung2 and Michael Rogers1

1Imperial College London 2Centre for Environmental Policy, Imperial College London

13:55 14:20 Activity of Various Catabolic Functions in UV-C Irradiated Escherichia coli

Margarete Bucheli-Witschel, Anna Ehlert, Yves Meur and Thomas Egli

Eawag, Swiss Federal Institute of Aquatic Science and Technology

14:20 14:45 Preliminary Study on Whole-Phase Control of Photoreactivation After UV Disinfection

Meiting Guo1, Hongying Hu2 and Jian Chen2

1Tsinghua University 2Fujian Newland EnTech Co., Ltd.

14:45 15:10 The Biological Safety of Model Distribution System Following UV

Sun Wenjun, Liu Wenjun, Cui Lifeng and Zhu Wanpeng

Tsinghua University



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Session A6 – Water Disinfection Reuse – Tuesday 22 September, 2009 St. John’s Room 2


15:55 16:20 Progress and Experiences of Ultraviolet Application to Water Related Treatment Processes in Singapore

Rongjing Xie,1, JY Hu2, M. Koh3, E Quek1, SN Xiu2, YJ Xing1, MJ Gomez1, Y Fu1, AN Puah1 and H Seah1

1Technology and Water Quality Office, Public Utilities Board of Singapore 2National University of Singapore 3Water Distribution and Network Department, Public Utilities Board of Singapore

16:20 16:45 Approach for Achieving Sustainable Operation of the 2BGD Catskill/Delaware UV Disinfection Facility

Matthew T. Valade1, Steven Farabaugh1, Paul D. Smith2 and Gary Kroll3

1Hazen and Sawyer 2NYC Department of Environmental Protection 3CDM

16:45 17:10 Practical Considerations of Applying UV Technology for Reuse Water Disinfection

Wayne Lem and Jennifer Muller Trojan Technologies

17:10 17:35 UV Disinfection for Reuse of Drain Water in Horticulture

Nico Enthoven Priva B.V.

Session B6 – Biofouling and Regrowth– Tuesday 22 September, 2009 St. John’s Room 1


15:55 16:20 Biofouling Control in Water by UV and AOP Pretreatment

Hadas Mamane1, Anat Lakretz1, Eliora Z. Ron2 and Tali Harif

1School of Mechanical Engineering, Tel Aviv University 2Life Sciences, Tel Aviv University

16:20 16:45 Combined Aging and Fouling Index Provides Efficient UV System Operation and Maintenance

Mark Heath and Harold Wright

Carollo Engineers, P.C.

16:45 17:10 Effect of Low Pressure UV on the Regrowth Potential of Drinking Water

Peter van der Maas1, Jantinus Bruins1 and Dirk van der Woerdt2

1Waterlaboratorium Noord 2Waterbedrijf Groningen

17:10 17:35 Disinfection of Biofilm in Tube Lumens with UVC Light Emitting Diodes (LED)

Jimmy Bak1, Søren D. Ladefoged2, Michael Tvede2, Tanja Begovic1 and Annette Gregersen2

1DTU Fotonik 2Rigshospitalet



15:55 16:20 Inhibition of Algae Growth in a Sight Pond with Ultraviolet Irradiation

Jian Chen2, Meiting Guo1 and Hongying Hu2

1Tsinghua University 2Fujian Newland EnTech Co., Ltd.

16:20 16:45 Response of Marine and Fresh Water Algae to UV

Liu Wenjun, Sun Wenjun and Liu Che

Tsinghua University

16:45 17:10 UV Treatment Against Indigenous Microcystis Species and its Potential to Cause Microcystin Release and Change of Aquatic Biota

Hiroshi Sakai1, Kumiko Oguma1, Hiroyuki Katayama1 and Shinichiro Ohgaki1

University of Tokyo

17:10 17:35 UV as an Ecological Invasion Barrier: UV Inactivation of Myxobolus cerebralis, VHSV, and Marine Phytoplankton

Brian Petri1, Linda Sealey1, Ron Hedrick2, John Lumsden3 and Charlie Trick4

1Trojan Technologies 2University of California, Davis 3University of Guelph 4University of Western Ontario

19:00 – 23:00 Banquet, Winter Garden


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POSTER PRESENTATIONS

Monday May 04, 2009 Grand Ballroom, PM Coffee


15:10 15:55 How UV Disinfection Can Help to Address Declining Groundwater Supply

Matthias Boeker ITT Water & Wastewater, U.S.A.

15:10 15:55 Evaluation and comparison of UV lamps Norbert Bodenhausen AQUAFIDES GmbH

Tuesday May 05, 2009 Grand Ballroom, AM Coffee


10:15 10:50 The UV Industry “down under” in Oz, warts and all!

Iain F Johnson Tenix Alliance Pty Ltd

10:15 10:50 Practical aspects of de-chloraminisation of public swimming pool water by means of Ultraviolet irradiation

Rob van Esch Siemens Water Technologies


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Monday 13:30-13:55 – Drinking Water Treatment – A1-1 St. John’s Room 2

UV in Drinking Water Treatment – Issues for the Next Decade (2010-2020)

James P. Malley, Jr., Ph.D.

University of New Hampshire

The interest and application of UV technologies to drinking water treatment was reignited in the 1990’s by two important events, first the growing global concern of waterborne disease outbreaks caused by Cryptosporidium parvum oocysts, and second the findings in the late 1990’s that prior studies evaluating the effectiveness of UV for cysts did not use accurate means of measuring inactivation; and when based upon mouse infectivity studies that UV disinfection was a very cost effective method for inactivation of both Cryptosporidium oocysts as well as Giardia cysts. These findings along with a myriad of new drinking water regulations that were finalized in the U.S. and elsewhere during the period 2000 through 2006 spurred steady growth in the number of drinking water treatment facilities using UV disinfection to the present. This is expected to continue throughout the period 2010-2020 in part since many of the regulations finalized in 2006 call for full compliance by water utilities by 2012 to 2014. In the past decade, UV based advanced oxidation processes have received renewed interest. In many parts of the world, the need for water reuse either directly or indirectly has resulted in treatment facilities needing to find cost effective technologies that can remove low levels of organic micro-pollutants such as NDMA, 1,4 dioxane, atrazine and other compounds present in these reuse waters. The ability of UV-H2O2 processes to effectively cost effectively remove 1 to 1.5 logs of NDMA by direct photolysis and similar removals for 1, 4 dioxane by hydroxyl radical pathways has made this a very attractive technology for treatment plants such as the first two at the PWN facilities in The Netherlands, the GWR facility in southern California, USA, plants in southeast Queensland, Australia and several other in the design and construction phases. Interest in UV based AOPs was further inspired by growing concerns of trace levels of pharmaceuticals and personal care products (PPCPs) as well as endocrine disrupting compounds (EDCs) being found in numerous water supplies and widely reported in the Associated Press in April 2008.

As the first decade of this millennium draws to a close, the purpose of this paper is to present emerging research as well as prognosticate where the field of UV treatment for drinking water will likely go in the next decade (2010-2020). The paper will discuss efforts to improve the energy efficiency of UV technologies in a world that is becoming ever more sensitive to global climate change, carbon footprint, water footprint and the need for sustainable technologies. These improvements will be related to advances in understanding UV reactor dose delivery and validation. The paper will look at several efforts to develop new UV lamp technologies such as UV-LEDs. UV technologies and potential for unwanted by-products from their use with a particular focus on the potential for by-products from UV based AOPs will also be reviewed. The paper will conclude with speculation on which UV applications in drinking water that will likely grow.

ORAL PRESENTATIONS


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UV System Technology Selection for Metro Vancouver’s

Coquitlam UV Disinfection Project

Chris Schulz, P.E.1, Ayman Shawwa, P.E., Ph.D.2 and Inder Singh, MASc., P.Eng3

1. CDM Inc., 555 17th St., Suite 1100, Denver, Colorado 80202, United States of America 2. CDM Inc., Walnut Creek, California, United States of America 3. Metro Vancouver, British Columbia, Canada

Metro Vancouver (MV) is moving forward with the design of a new 1,200 ML/day (315 US mgd) UV Disinfection Facility for the unfiltered Coquitlam water supply to meet Health Canada’s new requirements for 3-log Cryptosporidium inactivation. To select a UV system that will provide high disinfection performance cost effectively, medium-pressure (MP) and low-pressure high output (LPHO) UV systems were evaluated based on the following criteria: disinfection performance, fouling risk and cost. Three UV equipment manufacturers (Trojan, ITT-WEDECO and Calgon) submitted technical and cost information for two MP and two LPHO UV systems in response to a technical request for information. The manufacturers submitted UV system designs based on validation testing results or computational fluid dynamics (CFD) modeling projections to achieve the 3-log Cryptosporidium target using T1 phase or MS2 phage as the validation test organism. Life-cycle costs (LCC) of the proposed UV systems were calculated based on UV equipment and operation and maintenance (O&M) costs for 10- and 12-unit train configurations. As expected, LCC of UV systems designed to meet a T1 RED (reduction equivalent dose) were 30 to 40 percent lower than those based on MS2 RED design. The impact of more frequent off-line chemical cleaning of LPHO UV system on O&M cost was significant. For example, the NPV of ITT-WEDECO’s LPHO UV system was 123 percent higher than Calgon’s MP UV system based on T1 RED due to higher chemical cleaning and disposal costs associated with off-line cleaning practices (the MP UV system is equipped with an automatic wiper system). Disinfection performance of the proposed UV systems was evaluated using a UV Cost Analysis Tool (UVCAT) computer model. UVCAT analysis included predictions of the number of operating unit-trains, power consumption, dose-pacing efficiency, and Cryptosporidium log inactivation as a function of design flow and UV transmittance (UVT). UVCAT results confirmed that all proposed UV systems could meet the UV dose delivery requirement for 3-log Cryptosporidium inactivation for the full range of design flow and UVT and with a 10-unit train configuration. The UVCAT model simulation indicated that LPHO UV systems, which have a large number of low wattage lamps, have more efficient power turndown and they can provide more efficient dose-pacing compared to MP UV systems. The risk associated with lamp sleeve was evaluated for the Coquitlam UV system by performing demonstration-scale tests on LPHO and MP reactors. Pilot test results indicated significant fouling of LPHO UV lamp sleeves. The annual O&M cost of the LPHO UV system that utilizes off-line chemical cleaning was approximately $300,000 higher than that of MP UV systems and the LPHO UV system with an on-line mechanical cleaning system. Based on the findings of the UV systems evaluation, and especially the results of the demonstration-scale fouling study, the UV equipment procurement documents for the Coquitlam UV disinfection Project will include a base bid restricted to MP UV systems and an alternate bid allowing LPHO UV systems if they come equipped with a wiper system.


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Metro Vancouver’s New 1,200 MLD Coquitlam UV Disinfection Facility – An Example of Innovative and Sustainable Design

Inder Singh, MASc., P.Eng.

Metro Vancouver, 4330 Kingsway, Burnaby, British Columbia, Canada V5H 4G8 Metro Vancouver delivers water to over two million people in the Lower Mainland region of British Columbia Canada. The Coquitlam Lake source is one of the Region’s three primary water sources and a new 1,200 million litre per day UV facility is in the design phase to meet Health Canada disinfection requirements for Cryptosporidium inactivation. Improvements to the existing ozonation process are also planned to control disinfection by-product formation in the distribution system and enhance UV transmission of the raw water through oxidation of organics.

This presentation will provide an overview of the technical challenges faced in developing the detailed design for an unfiltered, gravity fed supply system, which is required to respond to dynamic downstream demand fluctuations. The project needs to be able to mitigate an unexpectedly high sleeve fouling rate discovered during demo-scale pilot testing. No new hydraulic grade line constraints are to be introduced into the system, which will restrict future supply capabilities. Also, an efficient UV system configuration is required to maintain existing operational flexibility and N+1 redundancy for all critical process related functions.

The new UV disinfection facility is being implemented with Metro Vancouver’s Sustainable Region Initiative in mind. A triple-bottom-line evaluation balancing economic, environmental and social aspects was used to determine whether specific design concepts would be incorporated into the project. Located in a protected watershed area, the UV plant layout was carefully selected to minimize footprint and reduce environmental impact. Sustainable opportunities investigated for the project will be discussed, highlighting specific engineering innovations related to the UV treatment process.

This presentation will be of interest to UV equipment manufacturers, consultants, as well as water utilities that are in the process of implementing, or considering a large scale UV application. The presentation will provide a water utility’s perspective of the key elements defining a successful project outcome.


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San Francisco Uses a Design-Build Approach To Implement a 315-MGD UV Disinfection Facility

Michael L. Price1, Bijan Ahmadzadeh2, Matthew Moughamian1 and Jamal Awad1

1. MWH Americas, Inc. 2. San Francisco Public Utilities Commission

The San Francisco Public Utilities Commission (SFPUC) is implementing UV disinfection for its unfiltered Hetch Hetchy Aqueduct (HHA) supply in compliance with the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). The HHA, which originates in Yosemite National Park about 200 miles away, currently receives chlorination at the Tesla Portal, as the only disinfectant. The LT2ESWTR requires all unfiltered supplies to employ two disinfectants, and each one must meet the full disinfection requirements of at least one target organism (i.e., Giardia, viruses, or Cryptosporidium).

In addition to schedule constraints (compliance with the LT2ESWTR by March 31, 2012), the HHA can be shut down for only a few weeks every winter. Plus construction requires procurement of several large valves up to 144-inch diameter, several hundred feet of large diameter piping, and UV disinfection equipment for the third largest installation in North America. After considering a number of options, including construction management at-risk, design-build open-book, and traditional design-bid-build, it was decided to use the design-build lump sum approach in which the design-build team would submit a firm bid to SFPUC.

A preliminary design including a set of comprehensive design criteria and specifications for major equipment and construction components was prepared. The selection process included a pre-qualification step in which three design-build teams were evaluated and invited to submit proposals. By San Francisco city ordinance, 65% of the overall scoring is based on the lump sum bid price. The remainder of the selection process was based on qualifications. PCL Constructors, with Stantec as the design subcontractor, was selected.

The project implementation has generated many lessons learned, some of which are related to:

Determining the optimum balance between prescriptive specifications and performance criteria

Developing evaluated bid criteria including life-cycle costs

Deciding whether to prescribe UV technology (i.e., low-pressure high-output vs. medium pressure) or to pre-select an equipment vendor prior to the design-build bid phase

Developing requirements for optimization of the system as part of the design-build contract

Judging how much leeway to give the design-build bidders in making changes to the preliminary design concepts

These and other issues were successfully resolved through perseverance, numerous detailed technical discussions among the project team, and by employing staff familiar with the technology, design-build procurement, and large facility operations. This presentation will be beneficial to utilities that are considering implementation of UV technology to meet disinfection requirements and must comply with significant project constraints.


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Monday 13:30-13:55 – Component Design – B1-1 St. John’s Room 1

Sustainability and Disinfection: How to Incorporate Life Cycle Assessment into Wastewater Disinfection Design

Gary Hunter, P.E.1,Ed Kobylinski, P.E.1, Leonard W. Casson2 and Ben Freese2

1. Black & Veatch, 8400 Ward Parkway, Kansas City, MO 64114 2. University of Pittsburgh

The dramatic rise in energy and chemical costs is spurring additional focus on optimizing efficiency of wastewater disinfection processes. At the same time, sustainability of disinfection in an increasingly-urbanized world will depend in part on the ability to reuse treated effluent as a resource instead of a waste product. Following the terrorist attacks of September 11, 2001, and devastation of Hurricane Katrina, the engineering design paradigm was broadened to include safety, security and a response to all hazards. The “3-S Design Concept” for drinking water and wastewater infrastructure systems was developed, as shown below, in response to this paradigm shift.

Safety o Public Health Protection Through Regulatory Compliance o Workers and Surrounding Community Protection

Security – “All Hazards” o Vulnerability Assessments o Emergency Response/Operation Plans

Sustainability o Infrastructure Design Support Systems o Environmental Considerations

Therefore the “3-S Design Concept” can be used to provide practical guidance for the design and operation of disinfection processes and treatment systems in today’s economic environment in a manner that embraces sustainable solutions that benefit future generations instead of short-sighted solutions with hidden future costs.

This presentation will provide practical methods for integrating safety, security and sustainability in the selection, design and operation of wastewater disinfection systems.

Gary Hunter is a senior wastewater process engineer with Black & Veatch. In that role he is responsible for wastewater disinfection projects through out the world. Currently he is apart of design teams looking at disinfection technology at 10 different facilities in the State of Missouri. Mr. Hunter holds a BSCE and MSCE from Brigham Young University. He is a PE in the State of Kansas.


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Medium Pressure Mercury Lamps for AOP/TOC

A. Voronov, M. Kessler and R. Dreiskemper

Heraeus Noblelight GmbH, Heraeus Str. 12-14, 63450 Hanau, Germany

Removing of organic and inorganic materials from water or air flows by means of UV light emitted by Low Pressure Mercury Lamps (LPML) is a slow running process, especially, if thorough purification is required. The reason for that is a low photon flux density produced by LPML. A Medium Pressure Mercury Lamp (MPML) provides an approximately 30-fold photon flux density, but it emits effectively only in the UV-C spectral range. In many cases the VUV-emission is necessary to obtain an effective TOC reduction. The VUV-emission of MPML below 200 nm is suppressed by the lamp material. Another disadvantage of MPML was a rather short lifetime – 3000 to 5000 hrs. Recent progress in the lifetime of MPMLs (more than 10000 hrs) opens new possibilities to establish MPML in AOP. The enhanced VUV-emission of MPML is achieved by a special quartz material. The paper presents the spectral and electrical parameters of MPML with the VUV-feature. The application for air and water treatment is discussed.


Comparison Testing of ‘Spot’ vs. ‘Pellet’ LPHO UV Lamps

Michael J. Santelli1 and James R. Bolton2

1. Light Sources, Inc., 37 Robinson Blvd., Orange, Connecticut, 06477 2. Bolton Photosciences, Inc.

Two types of amalgam low pressure high output lamps (one with a ‘spot’ amalgam and another with a ‘pellet’ amalgam) have been examined in a simulated UV reactor with a quartz sleeve and water flowing outside the quartz sleeve. These lamps were operated at 100%, 80% and 60% full power. It was found that the ‘pellet’ type amalgam lamps had superior performance at reduced power levels as compared to the ‘spot’ type lamps.


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Renaissance of Medium Pressure Lamps Driven by High Frequency Lamp Driver

A. Voronov1, V. Adam1, G. van Eerden2 and T. Telgenhof2

1. Heraeus Noblelight GmbH, Heraeusstr. 12-14, 63450 Hanau Germay 2. Nedap Light Controls, Groenlo, The Netherlands

Medium Pressure (MP) lamps are widely used in different industrial technologies such as printing for ink curing or in water treatment for disinfection. The MP lamps have very high UV-power density in comparison to Low Pressure (LP) lamps, acceptable efficiency of app. 15% but have a pretty short lifetime of only a few thousand hours. The main reason for lamp aging or failure is sputtering of electrodes, which in turn blackens the quartz envelope.

The physical mechanism of sputtering is analyzed and investigated. It is shown that the main contribution to sputtering is due to the ignition phase of the lamp and the operation at a mains frequency of (50 or 60 Hz). The usage of High Frequency Electronic Lamp Drivers (HFLD) solves such problems due to modulation of the current in the start phase and operation at high frequency (>20 kHz).

The results of field tests with a large number of units (MP lamp with HFLD) have demonstrated and proven high reliability of units which results in increasing of lamp lifetime to 10,000 hrs with the UVC-output depreciation of less than 15%. A comparison with Low Frequency Lamp Drivers (LFLD) was also carried out. Some physical reasons are discussed as to why LFEB do not achieve a low sputtering rate in MP lamps and such high efficiencies.

Additional advantages of High Frequency Lamp Drivers like constant lamp power and integrated communication intelligence are discussed together with the results of a benchmark test. This will also include a specific overview of power quality issues and the superior performance of HFLD’s with regard to overall efficiency, Power Factor, and Total Harmonic Distortion.


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Monday 13:30-13:55 – Waste Water – C1-1 Volmer Room 1 & 2

A Practical Case Study for Wastewater UV Disinfection:

Evaluation of Quartz Sleeve Mechanical Wiping System Performance & Resultant Fouling Factors


Infilco Degremont, Inc. - Degremont North American Research & Development Center 510, East Jackson Street, Richmond, VA 23219

It is well documented that Quartz sleeve fouling can adversely impact the efficacy of a UV disinfection system by absorbing a large fraction of the emitted UV-C output. Fouling is an issue that is more predominant with the UV disinfection of wastewater although drinking water applications can also experience significant fouling depending on the mineral content of the source water or the type of UV lamp used. Wastewater UV reactors are typically equipped with a mechanical and/or chemical cleaning system to provide operators with a means of controlling Quartz sleeve fouling and thereby preserving optimum disinfection performance.

In 2008, an extensive test campaign was undertaken to evaluate and optimize the performance of an automated mechanical wiping system for a wastewater UV reactor that uses low-pressure high-output amalgam lamps arranged in a vertical array. Initially, several wiper technologies were evaluated in terms of drag force generated and consistency of drag over the length of the Quartz sleeves. The optimal wiper design was selected and utilized to conduct an initial fouling test using a commercial UV reactor submerged in “synthetic wastewater”. Water quality parameters that were used as possible predictors of fouling were temperature, alkalinity, pH, total dissolved solids and cation concentration, in particular Fe (III) and Ca (II). The “synthetic wastewater” was prepared via continuous injection of chemicals such as sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), Calcium Chloride (CaCl2) and Ferric Chloride (FeCl3) with the feed rate adjusted to promote various levels of fouling potential. The transmittance from three sleeves was monitored throughout the course of the testing. Two of the sleeves were equipped with a wiper while one had no wiper to serve as a reference for the non-wiped condition. After one month of continuous operation at two wipes per day, the transmittance of the sleeves without wipers dropped by 40% while that of the wiped sleeves remained at 95%, which is very close to the baseline obtained with new / clean sleeves. The result from this initial fouling study looks very promising as it represents a clear improvement from the default 0.80 fouling factor that has been used to date to size UV systems.

A third party fouling study is currently ongoing in a full-scale field application in order to validate the cleaning performance of this new wiper technology in accordance with the UV Disinfection Guidelines for Drinking Water and Water Reuse (NWRA/AwwaRF2003).

This paper focuses on a review of the study results and corresponding fouling factors. The impact of key parameters on cleaning efficiency, including tolerance on quartz sleeve outside diameter, water quality, wiper wear and wiping frequency, as measured during the initial and third party validation testing are presented in detail.


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Comparing UV Validation Using USEPA Drinking Water and NWRI/AwwaRF Guidance

Harold Wright1, Andrew Salveson1 and Suzie Sarkis2

1. Carollo Engineers, 12592 West Explorer Avenue, Suite 200, Boise, ID 83702

2. Environmental Health Unit, Public Health Branch, Department of Human Services, 50 Lonsdale Street, Melbourne VIC 3000

The Problem. Regulators in Australia have recently requested that UV reactors used in wastewater reuse applications are validated in accordance with the USEPA UV Disinfection Guidance Manual (UVDGM) as opposed to the NWRI/AwwaRF UV Guidelines. However, the USEPA UV Guidelines were specifically developed for drinking water UV technologies.

Goals and Objectives. The primary goal of this work was to validate wastewater UV reactors in accordance with the USEPA UVDGM. The objectives were to identify key differences between NWRI/AwwaRF and USEPA Guidance and develop methods for validating wastewater UV reactors in accordance with the UVDGM.

Identifying the Problem. Key differences between the Guidelines include:

Target Pathogens and UV Dose Requirements. The NWRI/AwwaRF Guidelines specify UV dose criteria of 50, 80 and 100 mJ/cm2 for 5-log poliovirus inactivation with wastewaters treated with reverse osmosis, membrane filtration, and media filtration, respectively. In contrast, the UVDGM specifies UV doses for 0.5 to 4.0 log inactivation of Cryptosporidium, Giardia and adenovirus. While 22 mJ/cm2 is required for 4-log Giardia and Cryptosporidium inactivation, 186 mJ/cm2 is specified for 4 log adenovirus inactivation.

Validation Test Microbe and the RED Bias. The NWRI/AwwaRF Guidelines specify that UV reactors are validated using MS2 phage. In contrast, the UVDGM states that any microbe with a well-defined UV dose-response curve, such as MS2 or T1 phage, can be used. However, differences between the UV dose-response of the test microbe and the target pathogen must be accounted for using an RED Bias Uncertainty factor. Those factors are tabulated in the UVDGM as a function of target pathogen log inactivation, test microbe UV sensitivity, and UVT. The factors were developed for commercial UV reactors that have been optimized for the UVT that occurs with drinking water applications (i.e. 80 to 98%). Those factors are excessive when applied to UV reactors used in reuse applications because those reactors are optimized for lower UVT (i.e. UVTs from 55 to 80%). The tables also only go down to 65%.

Collimated Beam Dose Calculation. Both the NWRI/AwwaRF Guidelines and the UVDGM specify how to calculate the UV dose delivered by the collimated beam apparatus. However, the UVDGM approach uses factors not included by the NWRI/AwwaRF Guidelines. Because of these differences, the UV dose calculated using the NWRI/AwwaRF approach is greater than that calculated using the UVDGM.

The NWRI/AwwaRF Guidelines specify that the UV dose response of MS2 phage must be fitted with a linear function and fall within defined prescribed bounds. The linear fit does not account for the curvature of the MS2 phage UV dose-response and the bounds allow a large error in the relation between measured log inactivation and RED. In contrast, the UVDGM specifies QA/QC criteria for the collimated beam UV dose calculation and a fit to the UV dose-response that accounts for any observed shoulders or tailing.


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Uncertainty Factors. Both the NWRI/AwwaRF Guidelines and the UVDGM specify application of uncertainty factors. With the NWRI/AwwaRF Guidelines, the uncertainty is defined as the lower 75th percentile of the log inactivation measured through the reactor. In contrast, the UVDGM specifies use of a validation factor that relates the measured RED to the pathogen dose credit. The validation factor includes the RED bias uncertainty described above as well as the uncertainty of the dose monitoring algorithm, the uncertainty of the UV sensors used to monitor lamp output, and the uncertainty of the UV dose-response curve of the test microbe.

The Solution. Through UVDGM validation conducted at the Portland UV validation facility and NWRI/AwwaRF validation conducted in California, the following approaches are proposed:

UVDGM RED bias uncertainty factors for Cryptosporidium, Giardia, and adenovirus credit can be conservatively extrapolated to lower UVTs. UV validation data can be analyzed to define RED bias factors specific to a UV technology and pathogen UV dose requirement.

Collimated beam UV dose calculations should account for all relevant factors. UV dose-response data should be fit using functions that account for tailing and shoulders. Measured UV dose response should fit within bounds established through round robin UV dose-response studies. Bounds need to be tighter than those in the NWRI/AwwaRF Guidelines.

Monitoring algorithms used by reuse reactors should use UV sensor measurements and account for all uncertainties that significantly impact the predicted UV dose.


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Bioassays for Secondary Wastewater UV Systems – Is a Standard Possible?

Matthias Boeker

ITT Water & Wastewater U.S.A. / WEDECO Products 14125 South Bridge Circle, Charlotte, NC 28273

With the rapid acceptance and implementation of ultraviolet as a superior process for wastewater disinfection more and more engineers are faced with the challenge of designing systems that meet their clients’ disinfection requirements. While calculated ultraviolet sizing models, such as point source summation, have been widely used in many regions of the world, an alternate method utilizing biological verification (bioassay) is gaining acceptance with many engineers and regulators within the wastewater industry.

For water reuse applications the choice of challenge organism and testing protocol has been clearly defined within the NWRI/AwwaRF 2003 Guidelines for Drinking Water and Water Reuse. For secondary wastewater applications this organism and protocol are not appropriate, resulting in manufacturers conducting bioassays with no homogeneous protocol, often using native Fecal Coliforms. However, the use of Fecal Coliforms for bioassays has been shown to be unsuitable due to within-day variability of the microbe populations.

An alternate approach supported by the US EPA UVDGM 2006 was taken for the validation of the WEDECO TAK55 HP UV system. Two challenge organisms were utilized, T1 and Q-beta bacteriophage, in order to bracket the UV sensitivity of typical bacterial wastewater indicator organisms, such as fecal coliforms and E. coli.

The result of this validation approach is the development of performance models utilized for the prediction of head loss, power consumption and disinfection performance. Utilizing a validation approach that is based on the UVDGM results in a design tool to safely and accurately design UV systems to attain required disinfection goals, while accounting for the site-specific UV dose-response of the target organism. Therefore this validation approach has the potential to become the new industry standard.

Expected Learning Outcomes:

Participants will be able to understand the different options to design a UV system for secondary wastewater

After the presentation, participants will know the application of the US EPA UVDGM 2006 to the process of validation testing of UV equipment for wastewater


21


State of the Art of Production of Harmful Disinfection By-Products:

Fact or Fiction

Joop C. Kruithof1, Bram J. Martijn2 and Bram J. van der Veer 3

1. Wetsus Centre for Sustainable Water Technology, P.O. Box 1113, 8900 CC, Leeuwarden, The Netherlands 2. PWN Water Supply Company North Holland, P.O. Box 2113, 1990 AC Velserbroek,

The Netherlands 3. EVIDES Water Company, P.O. Box 4472, 3006 AL Rotterdam, The Netherlands

Since the beginning of the last century, chlorine has been used for the disinfection of drinking water. Originally, people were very reluctant against the use of chlorine, “a poisonous chemical”, but soon drinking water chlorination was generally accepted without any attention for potential harmful aspects.

In 1973 this situation changed completely when Rook showed the production of trihalomethanes (THM’s), suspect carcinogens for humans. Originally maintenance of chlorination was pursued, restricting the formation of disinfection by-products (DBP’s) by optimizing the chlorine use and the removal of the produced DBP’s by granular activated carbon (GAC) filtration. Much attention has also been paid to the removal of DBP-precursors.

Worldwide standards have been set for chlorination by-products. To satisfy these standards, measures have been taken to restrict the use of chlorine. For primary disinfection there was a shift from chlorination to ozonation. Also for ozonation formation of many DBP’s was established. These organic reaction products proved to be biologically degradable compounds rather than suspect carcinogen. The formation of the inorganic DBP bromate was established but ignored. The focus switched from toxicity to regrowth and regrowth control by post treatment of the ozonated water. For many years ozone was accepted as the ideal alternative for chlorine. This situation changed completely when Kurokawa showed that the inorganic ozonation by-product bromate was a suspect human carcinogen. Also for safety chlorination purposes, alternatives for chlorine were pursued. In the United States, DBP formation was restricted replacing post chlorination The related nitrification problems were generally accepted. However, recently it was shown that chloramination also may cause DBP-formation i.e. production of nitrosodimethylamine (NDMA). In The Netherlands, production of biologically stable water is pursued, so safety disinfection can be avoided completely. Nevertheless some water companies use a low dose of chlorine dioxide. Harmful organic DBP’s of chlorine dioxide have not been observed yet. Of importance may be the production of the inorganic DBP’s chlorate and especially chlorite. Therefore, chlorine dioxide use is limited to 0.2 mg/L.

The presence of Cryptosporidium oöcysts has had a big impact on drinking water disinfection. Under practical conditions chlorine is unable to inactivate Cryptosporidium. Ozone can inactivate Cryptosporidium but in most cases bromate formation is prohibitive. It is shown that UV disinfection can inactivate Cryptosporidium at a very low UV dose. Until now, no harmful organic DBP’s have been found. A point of interest is the reduction of nitrate into nitrite.

Besides the disinfection, organic contaminant control has gained a lot of attention with a focus on pesticides, endocrine disruptors, pharmaceuticals, taste and odour, etc. Within this framework, much attention has been paid to the application of ozone, either in combination with GAC filtration (O3-GAC) or with H2O2 and GAC (O3/H2O2 – GAC). Once again, no harmful organic DBP’s have been established until now. About ten years ago, bromate formation caused a switch from ozone to UV based processes (UV-GAC, UV/H2O2 – GAC).

This paper describes the state of the art regarding DBP issues in The Netherlands. Attention will be paid to mutagenicity, regrowth and the formation of individual DBP’s such as bromate and nitrite.


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Comparison of Ozone and UV Disinfection Processes Within the Scope of the Dutch Risk Analysis for Pathogens

Bram J. van der Veer1, P.W.M.H. Smeets2 and J.C. van Dijk1, 3

1. Evides Water Company, PO Box 4472, 3006 AA Rotterdam, The Netherlands

2. KWR Watercycle Research Institute, PO Box 1072, 3430 BB Nieuwegein, the Netherlands

3. Delft University of Technology, Faculty of Civil Engineering and Geosciences, PO Box 5048, 2600 GA Delft, the Netherlands

Introduction

Since 2002 a risk analysis for pathogens in drinking water is a statutory regulation in the Netherlands. The risk criterion is one infection per 10,000 inhabitants per year, which can be simplified as a threshold concentration of one pathogen in 833 m3 drinking water (protozoa, bacteria and viruses). This paper demonstrates how this new criterion changed the view on disinfection processes in the Netherlands. The aim of this study was to determine which type of disinfection process was more adequate to achieve the risk criterion: UV disinfection, taking place in a few seconds, or ozone, with contact times of at least five minutes.

Comparison of UV and ozone disinfection

The inactivation of coliforms at two comparable treatment systems was evaluated. Both systems treat the same raw water by coagulation, filtration and disinfection. However WTP Baanhoek applies ozone disinfection whereas WTP Berenplaat uses UV disinfection. In order to maintain the required level of 5.2 log disinfection, adequate process automation, including UV dose pacing and ozone CT control, is applied. UV lamp and ballast failures are compensated by switching the remaining lamps to maximum power. In case of low ozone residual concentrations (CT’s) during 10 minutes, the ozone disinfection process switches to a standby contactor.

The effects of such incidents on the yearly achieved disinfection, as well as the effects of normal operation conditions were quantified. Deviations in the disinfection processes were monitored by logging UV reactor lamp power and ozone residual and CT. This showed that only incidents in ozonation lead to a decrease of disinfection efficacy. Indicator organisms before and after disinfection were monitored daily to assess disinfection under normal conditions. Frequency-consequence plots (Hirschberg et al, Smeets) of indicator organism concentrations clearly showed that UV disinfection was more effective than ozone, despite the high number of non-detects after both disinfection processes.

Conclusions

These investigations showed that risk analysis criteria cannot be met by basing process control on monitored indicator organisms in drinking water. Adequate process control is required, and UV is the best controllable process. UV disinfection allows a more strict control of disinfection conditions than ozone, during both normal operation and process incidents. In view of these results, and due to the ozone-bromate issue, Evides Water Company decided to replace the (older) ozone installations by UV disinfection.


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Water Purification for Developing Countries, Design and Results

T. Telgenhof Oude Koehorst

Nedap Light Controls, PO Box 101, 7140 AC Groenlo, The Netherlands

Access to safe water is a fundamental human need and therefore a basic human right (Kofi Annan). This was bottom line the target we had at Nedap during our search for a “pure and simple” solution for drinking water systems. During the start of the project following challenges were set for this system for rural areas: usage of present water sources, multi barrier process, storage of water (limited) and most important low costs. In addition also requirements for transportation and maintenance of the system were highlighted. An innovative water purification device that combines well-established solar energy systems and UV water treatment technology has the potential to bring low-cost, safe water to millions in the developing world. The design of the purification system (it was named Naïade) will be presented together with the industrialization and the type testing at several institutes. Furthermore the field tests will be discussed and results shown, together with the proposed improvements for the system. The Naïade developed by Nedap, is a standalone, solar-powered water purification unit which can be set up and operational within 30 minutes. No special infrastructure is required and a single unit can meet the water requirements of between 250 and 350 people at an estimated cost of around € 1,50 per person per year. This means a break through in cost terms for drinking water purification systems making it a viable option for developing countries. The portability and simplicity of the system should also prove particularly useful in conflict zones or areas hit by natural disasters where a damaged or interrupted water supply can quickly lead to the outbreak of diseases. The 2-step bag filter together with the UV reactor have shown to fulfill the required disinfection rate. The solar panel with the battery back-up, provide sufficient energy for safe operation during day and even at night. Several hundreds of units are in operation at this moment worldwide. The results and experiences so far will be shared in this presentation. Also the big challenge to bring this solution for improved drinking water and therefore life expectancy, to the developing countries is one of the topics.


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Public Water Works: How Safe is UV Disinfected Drinking Water? Quality Management Once and Now

Regina Sommer1, Alexander Cabaj2, Georg Hirschmann3, Thomas Haider4 and Alexander Kirschner1

1. Medical University Vienna, Clinical Institute of Hygiene and Medical Microbiology, Water Hygiene, A-1095 Vienna, Kinderspitalgasse 15, Austria 2. Departement of Medical Physics, Veterinary Medical University, A-1210 Vienna, Austria 3. Arsenal Research, A-1210 Wien, Giefinggasse 2, Austria 4. Medical University Vienna, Institute of Environmental Health, A-1095 Vienna, Austria

UV irradiation with low pressure mercury lamps (wave length 253,7 nm) is the most commonly used technique for drinking water disinfection in Austria. Already since 1955 UV plants are permitted for water disinfection in public water supplies. In the first Austrian National standard published in 1983 a UV-253,7 nm fluence of at least 250 J/m² was stipulated. Advanced scientific knowledge, e.g. the findings on the higher UV sensitivity of viruses, provoked a raise of the minimum UV fluence to 300 J/m² (1989) and to 400 J/m² (1993), respectively. All these prescribed values for the UV fluence were solely based on the specifications and calculations of the manufacturers. There were no objective criteria to ascertain the efficacy of the UV disinfection plants and no possibility of an independent check of the proper function of the UV plant during practical operation. In view of the facts mentioned above, it was necessary to develop and establish standard protocols for the validation of UV disinfection systems. This has been carried out by three organizations (US Environmental Protection Agency, 2006; German Association for Gas and Water, 2006; Austrian Standards Institute, 2001 and 2003). These international standards have in common a minimum fluence (expressed as Reduction Equivalent Fluence) of 400 J/m² (253,7 nm) measured by means of biodosimetry. Moreover a UV radiometer (sensor) traceable to official specifications (measuring unit W/m²; UV-253,7 nm) is demanded. Since the economic and physical life of UV disinfection plants is usually several decades, different quality classes of UV plants are in operation in public water works, to date. The aim of our investigation was to measure the disinfection efficacy of a non-certified UV system installed in a public water work serving 10.000 people, which met the state-of-the-art of 1994.

A UV disinfection plant (4 low pressure mercury lamps) of a public water work was carefully demounted and transported to the UV Test Facility in Vienna. The UV plant was implemented at the water work in 1994. The manufacturer guaranteed at that time a UV fluence of 400 J/m² for the given water flow and corresponding UV transmittances of the water (maximum flow 57,8 m³/h; UVT 80% / flow 43,2 m³/h; UVT 45%). The technical installation at the test facility simulated the situation on site. For the biodosimetric measurement the water flow and the UV transmittances of the water were adjusted according to the guaranteed minimum/maximum values as well as the usually occurring conditions on site (43 m³/h; UVT 87%).

The investigation was performed according to ÖNORM M 5873-1. UV-253,7 nm calibrated spores of Bacillus subtilis were used as biodosimeter. Each operating condition was tested twice. This procedure resulted in 5 log-concentrations before and 5 log-concentrations after UV irradiation for each test point, of which the arithmetic mean was calculated (log No: before irradiation, log N: after irradiation). By calculating log N minus log N0, the reduction at the test point was determined. The reductions were converted by using the calibration curve into Reduction Equivalent Fluences, REF, J/m².


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The results of the measurements of the Reduction Equivalent Fluence are presented in table 1. Both, the guaranteed specifications of the manufacturer as well as the usual operating conditions of the UV plant were far below the minimum Reduction Equivalent Fluence of 400 J/m², which is considered necessary for safe UV drinking water disinfection. The results clearly demonstrate, that UV systems which are not in accordance with the state-of-the-art quality requirements (US-EPA:2006; DVGW:2006; ÖNORM M 5873:1996/2001/2003) can not be regarded as safe in terms of drinking water disinfection. At present no method exists to directly determine the disinfection efficacy of UV systems during practical operation. Thus, a validation of each type of commercial UV plant and the determination of the admissible operating range as well as the control of the UV irradiance by means of a calibrated UV sensor, which allows checks against official specifications, are prerequisites for a safe UV disinfection.

Quality management programs for drinking water supply systems (e.g. hazard analysis and critical control point concepts, HACCP; water safety plan proposed by the World Health Organisation) should consider the operating parameters of disinfection systems as critical control points.

Table 1. Measured Reduction Equivalent Fluence under variation of UV transmittance and water flow at the end of the utilisation period of the UV lamps of a commercial UV disinfection plant demounted from a public water work and installed at the UV Test Facility Vienna (the data represent the mean of two test runs, 5 measurements before and after UV each; analysis of the samples for cfu were performed in triplicate).

Test point

Water flow [m³/h]

UV- Transmittance of

the water [%] 10 cm; 253,7 nm

Biodosimeter mean

concentration before UV

log [cfu/L] No

Biodosimeter mean concentration after

UV log [cfu/L] N

Reduction log [No/N]

Mean REF* [J/m²]

system-control

12,45 86 < 1 < 1 - -

A1 58,48 86 7,09 ± 0,01 6,77 ± 0,03 0,32 114

A2 43,16 87 7,15 ± 0,04 6,58 ± 0,07 0,57 160

A3 43,12 45 7,14 ± 0,04 6,90 ± 0,03 0,24 99

system control

43,12 44 - 7,16 - -

* REF, Reduction Equivalent Fluence


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Design of Hydraulically Optimized UV Systems Using CFD

B.A. Wols1,2, J.A.M.H. Hofman1,2, E.F. Beerendonk1, W.S.J. Uijttewaal2 and J.C. van Dijk2

1. KWR Watercycle Research Institute, P.O. Box 1072, 3430 BB Nieuwegien, The Netherlands

2. Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands 3. Waternet, Provincialeweg 21, 1108 AA Amsterdam, The Netherlands

The efficacy of UV systems is largely determined by hydraulics. The hydraulics have a big impact on the UV dose distribution, which determines the disinfection and/or oxidation performance. By assuming a dose distribution, for example a (shifted) exponential distribution, it can be shown that narrowing the dose distribution may lead to a reduction in energy consumption of 25% to 50%. So the benefits of optimizing the hydraulics which narrows the dose distribution, are substantial. For a proper estimation of the dose distribution in a UV system, knowledge on the transfer and mixing processes is essential. Computational Fluid Dynamics (CFD) is a powerful tool to simulate these processes. In combination with a particle tracking routine and an irradiation model, the UV dose distribution can be calculated with considerable accuracy.

An assessment is made of the energy efficacy of several types of UV reactors. The removal of Bacillus Subtilis as well as the oxidation of Atrazine with an injection of 10mg/L H2O2 is considered (for a UV-transmittance of water of 80%). Reactors used in practice as well as new concepts are taken into account. These types include (Figure 1): conventional systems with UV lamps placed perpendicular to the flow; systems with alternating orientations of the lamps; annular systems with a varying lamp diameter and helical flow swirling around the lamp; systems with lamps outside the reactor; systems with a hydraulically optimized lamp shape (wing shape or grid in front). A CFD model is constructed for each reactor type, from which the dose distribution is determined (Figure 2). The efficacy in terms of disinfection or oxidation can then be predicted.

The weak points in the UV systems are related to the parts of water that travel at the largest distance from the lamps. At these locations, usually close to the walls, irradiation levels are low due to adsorption of UV light in water. For example, the weak points in the annular system are the particles that remain close to the outer diameter. Increasing the width of the lamp leads to a small increase in disinfection efficacy, as the irradiation field is more uniform. For the same reason, the UV system with alternating lamp orientations shows a wide dose distribution. The system with a helical flow around the lamp therefore has a higher disinfection efficacy due to the increased mixing. The optimized bench-scale reactor shows good results, because the staggered lamp positions force all the parts of the flow to travel closely to at least one lamp. For a good reactor design, it is important that all the particles reach the area close to the lamps, which can be achieved by increasing the mixing in the system and/or manipulate the main flow. This can be examined by the CFD calculations, which form an essential tool for new design and optimization of UV reactors.


27


The Impact of Refraction on the Radiation Field in UV Photoreactors

Azita Soleymani, Domenico Santoro and Mike Sasges

Trojan Technologies

Computational Fluid Dynamics has been shown to be a powerful tool for predicting the fluid flow in ultraviolet photoreactors. Numerous manufacturers, academics and consultants are using CFD to model UV reactors, and the predicted performance has been shown to be well correlated with the measured performance of full-scale reactors. The performance of a UV reactor is a function not only of the fluid flow but also of the radiation field. These two functions must be convolved correctly to predict the dose distribution and ultimately the Reduction Equivalent Dose of a UV reactor. While considerable focus has been placed on accurate flow modeling, less attention has been placed on accurate radiation modeling.

There are a number of codes available to predict the Fluence rate (“intensity”) field in a UV reactor. The CFD code “Fluent”, from Ansys Corporation, includes the “Discrete Ordinates” (DO) model, which is capable of solving the radiative transport equation (RTE) in a fluid medium and thus providing an estimation of fluence rate distribution in a UV reactor. The Point Source Summation model is sometimes used to calculate the radiation field. Recognizing the shortcomings of these models, Trojan Technologies has developed its own in-house radiation code. In this paper, these models will be compared in simple CFD simulations, and also compared against experimental measurements.

It is shown that a simple application of the D.O. model can lead to significant deviations from the true radiation field, arising from several factors. Methods are described for minimizing these errors, at a cost of increased computational load. Similarly, the PSS model can also lead to significant errors. The Trojan model is shown to agree well with experimental measurements.


28


CFD Analysis of UV-Disinfection Systems

M. Hunze and Arthur Schubert

FlowConcept GmbH, Vahrenwalder Str. 7, D-30165 Hannover

CFD (Computational Fluid Dynamics) is a helpful tool for system design and system optimization. Its use has a long tradition in many application fields as the automotive or the chemical industry. In the field of drinking water preparation and water treatment it has been used, however, since a few years, and supports to receive a better understanding of the processes occurring within the several systems and to optimize them with respect to their efficiency.

The field where UV-disinfection systems are applied comprises inter alia units for drinking water preparation, waste water treatment, water preparation for swimming pools, preparation of ultra pure water for electronics industry, ballast water treatment, and special purposes in the pharmaceutical industry. The reactors of all these different application fields are characterized by their own purpose and need an adequate design and operation. When designing such a system its quality can be only evaluated not until before a prototype exists. The design procedure, however, can be supported by the use of a suitable CFD-program. This program allows testing several variants and modifications which can be evaluated with respect to their influence on the system conditions. So that at the end of this design process the prototype will be an already optimized system.

This article describes a 3-dimensional model which is suitable to compute the flow field, the radiation intensity field, and the disinfection process of UV-disinfection units. The process approaches are all calibrated by a number of measurements over the past years and the developed model is characterized by a high quality with respect to the approximation of the system conditions.

Selected examples from practice will be demonstrated to show the benefit of using the model.


29


CFD as a Tool to Predict Certification Results (DVGW, ÖVGW, SVGW)

Christoph Dicks

AQUFIDES GmbH During the last decade CFD have developed into a powerful tool to develop UV systems and to predict their performance. But how can we judge the improvements CFD provided to product development? A systematic approach is needed. The product development team of AQUAFIDES, which has experience of more than 10 years with CFD for UV systems, has developed a system to make these improvements transparent. The impulse for this system came from a discussion between the product development team and the group management regarding the contribution of CFD to the success of the company. Nowadays this system is used internally to evaluate the quality of the work of the product development team, to make risk assessments and to make even financial decisions.

To measure the reliability of the predicted performance the results of the certification with DVGW, ÖVGW and SVGW can be used as a benchmark. Certification with DVGW, ÖVGW and SVGW is a biodosimetric simulation of the real performance of UV systems within in a standardized framework. It is globally the most stringent biodosimetric test regime. The variation of the biodosimetric test itself is considered as well in addition to other factors, which may influence the results like UVC output of lamps etc.

Based on the AQUAFIDES series of UV systems for drinking water disinfection, which have been certified with Arsenal and ÖFI in Vienna in 2008 and 2009, detailed results will be presented which show the predicted performance and the achieved performance. Details of the systematic approach will be presented and the improvements made with CFD to predict UV system performance in 2008 and 2009. One case for a risk assessment and a financial decision will be presented as an example. In addition to the results some critical factors to improve the reliability of CFD to predict the performance will be presented as well.

It can be concluded that the system provides transparency to an important aspect of product development for UV systems, which so far could only be judged in a systematic way. In addition it shows the increasing importance of CFD for product development in a global environment, which is asking more and more for various kinds of independent certification UV system performance.


30

Monday 15:55-16:20 – Photochemistry – C2-1 Volmer Room 1 & 2

Determination of the Quantum Yield of the Ferrioxalate and KI/KIO3 Actinometers and a Method for the Calibration of Radiometer Detectors

James R. Bolton1, Mihaela I. Stefan2, Ping-Shine Shaw3 and Keith R. Lykke3

1. Bolton Photosciences Inc., 628 Cheriton Cres., NW, Edmonton, AB, Canada, T6R 2M5; 2. Trojan Technologies, Inc., 3020 Gore Rd., London, ON, Canada N5V 4T7 3. National Institute of Standards and Technology (NIST), Gaithersburg, MD, 20899

If the quantum yield of a photochemical reaction is known, the yield of the photochemical product (or the depletion of the absorbing reactant) can be used to determine the photon flux entering a solution or incident on a surface. Such a photochemical reaction is called an ‘actinometer’. The most popular actinometer in the ultraviolet wavelength range is the ferrioxalate actinometer, involving the photochemical reaction

2 Fe(C2O4)33- + hv 2 Fe2+ + 5 C2O4

2– + 2 CO2

After exposure of a ferrioxalate solution to UV light (e.g., at 254 nm) the Fe2+ generated can be assayed by a colorimetric method in which the Fe2+ is complexed with o-phenanthroline. In a recent study, the quantum yield for the ferrioxalate actinometer has been determined to be 1.41 at 254 nm (Goldstein and Rabani, 2008).

Another popular actinometer for UV light at 254 nm is the KI/KIO3 actinometer, based on the photochemical reaction:

8 I– + IO3– + 3 H2O + hv 3 I3

– + 6 OH–

The I3– can be easily assayed from its absorbance at 352 nm. The advantage of this actinometer is that it can

be used in room light, since it is not sensitive to light above 320 nm. The quantum yield for the KI/KIO3 actinometer has been determined to be 0.73 at 254 nm (Rahn et al., 2003)

The use of a standard actinometer is a very convenient and reliable method to calibrate radiometer detectors. However, if such calibrations are to be traceable to acceptable national standards, such as the National Institute of Standards and Technology (NIST), the quantum yields must be determined accurately directly against the standard light source at NIST.

We have utilized lasers at NIST coupled with standard detectors to study these actinometers. The lasers are tunable in the range 210 – 3000 nm with a bandwidth of <0.1 nm and a power in the 100 mW range. The quantum yields for the ferrioxalate and KI/KIO3 actinometers have been determined as a function of wavelength and temperature. The results will be presented in the full paper.

References

Goldstein, S., Rabani, J, The ferrioxalate and iodide-iodate actinometers in the UV region, J. Photochem. Photobiol. A - Chemistry. 193,(1), 50-55 (2008).

Rahn, R.O., Stefan, M.I., Bolton, J.R., Goren, E., Shaw, P.-S. and Lykke, K., Quantum Yield of the Iodate-Iodide Actinometer: Dependence on Wavelength and Concentration, Photochem. Photobiol., 78(2), 148-152 (2003).


31


Kinetics and Quantum Yield Analysis for Vacuum UV (VUV) Photoreactors

Gustavo E. Imoberdorf and Madjid Mohseni

Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, B.C. Canada V6T 1Z3

UV based advanced oxidation processes (AOPs) are promising technologies for the treatment of recalcitrant organic contaminants in water. One such AOP relies on vacuum UV (VUV) irradiation and consists of exposing water to the radiation generated by VUV lamps, which emit radiation at wavelengths lower than 200 nm. During the irradiation process, high energy VUV photons promote photolysis of water, producing highly oxidizing hydroxyl radicals (HO), which can partially oxidize or mineralize the organic matter. Analysis and modeling of VUV-aqueous systems are generally very difficult because of the very many reactions that occur simultaneously. The complexity of the reacting system is partially a consequence of the high reactivity of the free radicals formed by the photolysis of water, and the subsequent reactions between the radical species and the stable chemical species. More than 30 reactions are known to occur during VUV photolysis of pure liquid water only (Gonzalez et al., 2004). In addition, there are numerous other reactions involving the organic compounds of interest as well as natural organic matter (NOM). Hence, understanding the reaction mechanism along with the radiation flux distribution in a given reactor geometry is key in designing effective VUV reactor and determining the efficacy of process. The focus of this study was to evaluate and model the degradation of a model organic compound in an annular photoreactor, equipped with a mercury vapour VUV source emitting at 185 nm and 254 nm. The modeling work incorporated the most important reactions due to the photolysis of pure water by VUV as well as the reactions between the model organic compound and the radical species formed in the system. The 185 nm radiation flux emitted by the VUV lamp was determined using the cis-trans cyclooctene photoisomerisation actinometric technique (Schuchmann et al., 1981). Potassium iodide/potassium iodate actinometric technique (Rahn, 1997) was used to determine the radiation flux at 254 nm. The radiation field within the reactor was modeled by solving the radiation transfer equation, incorporating Monte Carlo (MC) method for evaluating the photon absorption distribution. The combination of the kinetic model and the radiation model helped determine the overall quantum yield of the mineralization of the organic compounds in the VUV photoreactor. In this presentation, we will discuss the approach in developing the models and present the results along with the analysis of the quantum yields and energetic requirements of the system. We will also present the role played by inorganic compounds and minerals in the radiation field distribution within the VUV photoreactor. Bibliography: Gonzalez, M.G., Oliveros, E., Woerner, M., Braun, A.M. (2004) Vacuum-ultraviolet photolysis of aqueous reaction

systems” J. Photochem. Photobiol., C: Photochemistry Reviews, 5(3), 225-246.

Rahn, R. O. (1997) Potassium iodide as a chemical actinometer for 254 nm radiation: use of iodate as an electron scavenger. Photochem. Photobiol. 66, 450–465.

Schuchmann, H. von Sonntag, -P., C., Srinivasan, R. (1981), Quantum yields in the photolysis of cis-cyclooctene at 185 nm, J. Photochem. 15, 159–162.


32


Efficiency of Surface and Air Disinfection from Bacterial and Fungal Microflora Under the Effect of Continuous and Impulse UV Irradiation

V.I.Sigaev1, A.V.Vorobyov1, A.D.Tolchinsky1, S.G.Shashkovsky2, S.N.Uspenskaya1,

A.N.Varfolomeyev1, I.A.Zhelayev 2 and E.V.Zvyuagina1

1. SFES "Research Centre for Toxicology and Hygienic Regulation of Biopreparations" at FMBA RF, Serpukhov 2. State Educational Institution of Higher Professional Training “Bauman Moscow State Technical University” (SRI EM, structural unit of Bauman MSTU), Moscow Low-pressure mercury lamps which are an efficient source of continuous bactericidal UV light with a wavelength of 254 nm are used as classic UV sources at disinfection of surfaces and air.

Currently pulsed xenon lamps are one of alternative sources of biocide UV irradiation. Operating principle of xenon lamps is based on irradiation of objects by impulses of continuous radiation within the wavelength range of 200-4000 nm. Intensity of pulse sources’ irradiation in UV range is 105 times higher as compared to monochromatic sources and reaches the level of 200-1000 kW/m2. Xenon is a chemically inert gas, therefore such lamps are environmentally safe. Efficient use of new sources of biocide UV irradiation in UV decontamination systems should be based on the results of experimental studies on assessment of different nature UV irradiation efficiency for typical microflora present on surfaces and in air.

The work objective is to conduct comparative studies of efficiency of bacterial and fungal microflora exposure to continuous and pulsed UV light.

Cells of Escherihia coli bacteria, spores of Bacillus thuringiensis bacteria and spores of Aspergillus niger fungus were used in the studies as representatives of bacterial and fungal microflora at initial level of contamination of surfaces 104-107 CFU/cm2 and air 104-107 CFU/m3. Study of efficiency of decontamination by UV irradiation was conducted using test models represented by plastic Petri dishes (diameter 40 mm) with a thin layer of biocontaminant suspension 1 ml of microorganisms’ working suspension was placed into a Petri dish forming a layer of 0.7 mm. Assessment of UV irradiation antimicrobial effect on air microflora was conducted in a 150 L static aerosol chamber. Generation of bacterial aerosols in the working volume of chamber was conducted using Collison generator. Aerosol sampling was performed using liquid aerosol samplers – whirl impingers.

Pulsed Xe-lamp type INP 5/120 (Russia) and Hg-quartz bactericidal lamp TUV15W/G1578 (Netherlands) were used as UV sources. Range of UV surface irradiation doses was 80-8000 J/m2, and air irradiation - 300-30000 J/m3.

Comparative studies of sensitivity of Escherihia coli bacteria cells, Bacillus thuringiensis bacteria spores, and Aspergillus niger fungi spores, both on surface and in aerosol state, to continuous (Hg-lamp) and pulsed (Xe-lamp) UV irradiation under the same energy deposition were conducted. It was detected that for all species of microorganisms used in the works Xe-lamps’ pulse continuous-spectrum irradiation possesses higher biocide activity as compared to monochromatic irradiation of Hg-lamp.

Threshold surface energy doses of pulse UV irradiation were shown to be 7-30 times lower (depending on microflora species) than continuous irradiation doses at equal levels of disinfection.


33

Tuesday 9:00-9:25 – Advanced Oxidation – A3-1 St. John’s Room 2

Potential for Advanced Oxidation Processes (AOPs) in Disinfection and Simultaneous Emerging Contaminants Removal: a Review

C. Sichel

Siemens Water Technologies-Wallace and Tiernan GmbH, Auf der Weide 10, Günzburg, Germany

Within the last years many research works showed the suitability of advanced oxidation processes for many types of water treatment (Malato et al. 2007). The generation of the highly reactive radicals, used for oxidation of the compounds can be obtained with the help of UVC and solar UV energy. The solar applications are often used with focus to low cost applications, while the UVC-based AOPs permit the use of a wild field of established processes. UVC AOPs can generate OH. radicals when the light is absorbed by photocatalysts like the semiconductor TiO2, or photoactive dye. Short wave UVC light can also be directly absorbed by H2O2 in the UV/H2O2 AOP process. Another well known AOP is the UVC-based Fenton process: UV/H2O2/Fe(II). Due to the iron chemistry the Fenton reaction has its best performance at pH 2.8. Ozone is also used as AOP in combination with UV and/or H2O2. Especially disinfection applications show increasing numbers of publications in the last years (Scopus, 2008). AOPs are interesting for the elimination of microorganisms due to the disinfecting properties of the UV light itself. In UVC disinfection the light is absorbed by the DNA of microorganisms and then rapid inactivation takes place. Therefore an AOP actually is added value to the conventional UV disinfection regarding its final disinfection yield and velocity.

Generally a new challenge for water treatment is the occurrence of emerging contaminants (ECs) that have been measured within the last years not only in the US (Kolping et al. 2002, but also in Europe (BfG, Germany, 2007). ECs include pesticides, hormones and medical drugs that can disturb the human endocrine system and therefore are referred to as endocrine disrupting chemicals (EDCs) These substances enter the water streams as a result of their use in agriculture or, in the case of pharmaceuticals, as a consequence of increasing human consumption. Unfortunately EDs are often non biodegradable and can only partly be eliminated in conventional water treatments (Vieno et al. 2007). Therefore they can accumulate in water reuse systems and ground waters, etc. To evaluate existing adverse effects of EDs and needs for restriction the EU initiated a program called the Community Strategy for Endocrine Disrupters and the USEPA the Endocrine Disruptor Screening Program. Final outcomes of these investigations are expected to be published in the coming years. Nevertheless already today preoccupation can be felt about the effect these substances might have for the health of consumers.

This paper reviews the potential of AOPs for the combination of both treatment goals i.e. disinfection and simultaneous removal of ECs, reporting on existing experiences and successful application from the scientific literature.


34


Efficacy of UV Advanced Oxidation and Direct Photolysis Processes in a Drinking Water Utility with Full-Scale Granular Activated Carbon

Deborah H. Metz1, Maria Meyer1, Ramesh Kashinkunti1 and Erwin F. Beerendonk2

1. Greater Cincinnati Water Works 2. KWR - Watercycle Research Institute

Direct UV photolysis and UV/H2O2 advanced oxidation processes have the potential to degrade a wide-range of organic micro-pollutants with varying effectiveness. Effective direct photolysis depends upon the UV absorption spectra of the contaminant and the emission spectra of the UV lamps as well as other water quality parameters. The addition of H2O2 to the process greatly increases the effectiveness. UV photolysis of H2O2 is rapid creating hydroxyl radicals which react non-selectively with organic compounds yielding carbonaceous free radicals. These radicals rapidly react with dissolved oxygen to form peroxyl-radicals, which break down to oxyl-radicals which further break down to other radicals, which initiate continuing radical-based reactions until terminated.1 The efficiency of the UV/H2O2 process is dependent upon the rate of formation of hydroxyl radicals, the presence and concentrations of hydroxyl radical scavengers and other water quality parameters. Low-pressure (LP) and medium-pressure (MP) UV lamps both emit wavelengths capable of creating hydroxyl radicals. However, MP technology is more energy-intensive and produces a broad-spectrum of UV wavelengths, thus achieving direct photolysis at multiple wavelengths. LP lamps primarily emit UV at 253.7 nm, and only achieve direct photo-degradation at this wavelength.

Greater Cincinnati Water Works (GCWW) is designing a 908,500-m3/d (240-MGD) UV disinfection facility, and additionally wished to determine the efficacy of UV/H2O2 for reducing the concentration of organic contaminants. Therefore, GCWW joined an international collaboration to determine if LP and MP UV/H2O2 and direct photolysis could effectively degrade micro-pollutants in GCWW’s conventionally treated (CONV) and GAC treated (post-GAC) waters. A year-long pilot study was completed using a 208-L/min (55-gpm) pilot facility with Aquionics LP and MP reactors followed by GAC columns. The most economical placement of the UV disinfection facility was after the full-scale GAC facility, because the UVT of GAC effluent was 93-98% as compared to 83-95% in the CONV water. However, it was hypothesized that GAC would provide a beneficial barrier against the synthetic organic contaminant degradation byproducts, disinfection byproduct precursors and biologically available carbon potentially produced by UV/H2O2. Thus both lamp technologies were studied for CONV and post-GAC waters.

Contaminants were selected based on Ohio River detections, chemical structure and bench-scale test results for UV/H2O2 and photolysis. The contaminants spiked into the pilot were atrazine, metolachlor, MTBE, MIB, ibuprofen, gemfibrozil, and 17-a-ethinylestradiol. H2O2 was added at 10 mg/L, and the reactor doses were set to target an 80% atrazine degradation.

Quarterly degradation results, energy efficiency data and GAC effluent data will be presented, for which the following general conclusions were drawn.

UV/H2O2 is a viable technology for reduction of micro-pollutants for GCWW; direct photolysis is of limited value.

Energy consumption required to degrade each contaminant varied

o Less energy was required in post-GAC water versus CONV water.

o Less energy was required by LP reactor versus MP reactor.

UV/H2O2 followed by GAC reduced all contaminants below detection limits.


35

GAC without UV/H2O2 also produced excellent results with over 300 run days.

The full-scale UV disinfection facility will include flexibility to install UV/H2O2 in the future.

1. Linden, K.G., et al., “Innovative UV Technologies to Oxidize Organic and Organoleptic Chemicals.” American Water Works Research Foundation Report. (2004).

Example Reactor Effluent Degradation Utilizing Post GAC Plant Water

Contaminant Degradation - Post GAC UV/H2O2

Medium Pressure Reactor

0%

20%

40%

60%

80%

100%

Atrazin

e

MTBE

Metol

achlo

rM

IB

17-a-e

thynyle

strad

iol

Gemfibro

zil

Ibupr

ofen

Deg

rad

atio

n (

%)

Fall 2007

Winter 2008

Spring 2008

Summer 2008

Contaminant Degradation - Post GAC UV/H2O2

Low Pressure Reactor

0%

20%

40%

60%

80%

100%

Atrazin

e

MTB

E

Metol

achlor M

IB

17-a-

ethy

nyles

tradio

l

Gemfib

rozil

Ibup

rofe

n

Deg

rad

atio

n (

%)

Fall 2007

Winter 2008

Spring 2008

Summer 2008

GACRunday

GAC Eff.Type Atrazine Metolachlor MTBE1 MIB2 EES3

Gemfibrozil Ibuprofen

35 Medium Press <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L35 Low Press <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L35 Control 1 <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L35 Control 2 <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L



286 Medium Press <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L286 Low Press <0.1 µg/L <0.1 µg/L <0.2 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L286 Control 1 <0.1 µg/L <0.1 µg/L 0.31 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L286 Control 2 <0.1 µg/L <0.1 µg/L 0.26 µg/L <2.0 ng/L <5 ng/L <0.1 µg/L <0.5 µg/L

1. methyl tertiary butyl ether

2. 2-methyl-isoborneal3.17-a-ethynylestradiol

GAC Effluent Concentrations


36


UV/H2O2 AOP for Water Treatment: Fundamentals and Full-Scale Applications

Christian Williamson, Mihaela Stefan, Alan Royce, Adam Festger and Neil Brown

Trojan Technologies

The occurrence of chemical micropollutants in drinking water sources at levels ranging from nanograms (ng) to micrograms (μg) per liter has been documented in the scientific literature. These findings have been driven by the combination of increasing environmental stress together with significant advances in analytical instrumentation and method development. Subsequently, drinking water regulations, enforced by environmental and human health protection agencies around the world, are continuously becoming more stringent. To give only a few examples, nitrosamines have been added to the USEPA’s contaminant candidate list (CCL2) given their potent potential human carcinogenicity (10-6 risk level at 0.7 ng/L for N-Nitrosodimethylamine), pesticides are limited in drinking water in the European Community countries to 0.1 μg/L each and not more than 0.5 μg/L in total, the WHO provisional guideline value for total microcystin LR (free and cell bound), a highly potent hepatotoxin released into the surface water bodies during the algae blooms, is 1 μg/L (rounded figure) in drinking water.

In response to the occurrence, detection and regulation of chemical contaminants, drinking water providers are challenged to respond with sustainable, cost-effective treatment technologies. Increasingly, UV and the UV/H2O2 advanced oxidation processes are being employed for treatment of a variety of water contaminants both microbial and chemical in nature. In this paper the fundamental principles upon which UV alone and UV/H2O2 processes are selected in full-scale drinking water applications will first be discussed. The role of the micropollutant chemical structure and of its (photo) chemical kinetic parameters will be emphasized, along with the various environmental parameters that influence the efficiency of the process.

Full-scale UV system performance and kinetic model predictions will be presented and discussed for a wide variety of micropollutants such as nitrosamines, pesticides, taste-and-odor causing compounds and algal toxins, industrial solvents, pharmaceuticals and endocrine disruptors, in connection with their specific photostability and reactivity toward the hydroxyl radical.

The ability to model the UV light-based water treatment with accuracy is a must for the UV equipment manufacturers in order to provide the customer with process performance guarantees.


37

Tuesday 9:00-9:25 – Certification / Validation – B3-1 St. John’s Room 1

UV Reactor Challenges with a High Resistance Surrogate for Adenovirus Credit

Brian Petri1 and Conrad Odegaard2

1. Trojan Technologies, 2. GAP Enviromicrobial Services Ltd.

Adenovirus has been shown to have a high resistance to low pressure UV, and although not reported in any drinking water outbreaks, it has been chosen to define the UV dose requirements for virus credit in the US EPA LT2 ESWTR. For 4-log virus credit in the LT2 ESWTR, a low pressure UV dose of 186 mJ/cm2 is required, which corresponds to a point resistance of 46.5 mJ/cm2/log. UV reactors must be bioassay validated to achieve credit per the LT2 ESWTR, but currently available challenge microorganisms are not able to demonstrate these high dose values. For example, the most common (and coincidentally most UV-resistant) challenge microorganism is MS2 bacteriophage, which ranges in resistance from 18-25 mJ/cm2/log. To obtain 4 log virus credit, the dose demonstration target of at least 186 mJ/cm2 corresponds to 7.4-10.3 log reductions of MS2 depending on its resistance, which is operationally very difficult to do at any reasonable scale.

We set out to find a highly UV resistant microorganism that could be cultured to high titers, for doing practical demonstrations of high UV resistances. We used spores of the fungus Aspergillus niger, and characterized them with a low pressure UV collimated beam. Typical resistance values measured using a collimated beam as part of a reactor challenge were approximately 100 mJ/cm2 for 1 log inactivation, and 325 mJ/cm2 for 2 log inactivation. We used a culture with a titer of > 10^10 CFU/100mL to do full scale challenges of a residential scale low pressure UV reactor (up to 68 L/min flow) and a municipal drinking water scale medium pressure UV reactor (up to 2100 L/min flow). Coefficients of variation for triplicate samples were under 2.6%. We successfully demonstrated reduction equivalent doses > 300 mJ/cm2 using the A. niger spores, making these spores a viable choice for high dose UV reactor challenges such as those required to achieve multi-log virus credit for the LT2 ESWTR.


38

Tuesday 9:25-9:50 – Certification / Validation – B3-2 St. John’s Room 1

How the UVDGM 2006 Impacts UV Disinfection System Performance

Matthias Boeker

ITT Water & Wastewater U.S.A. / WEDECO Products, 14125 South Bridge Circle, Charlotte, NC 28273

UV disinfection of drinking water is a safe and reliable way to protect public health from waterborne diseases. Since UV light has the ability to destroy pathogenic microorganisms within seconds, it has been widely implemented in many water treatment facilities throughout the world.

The key design criterion for UV disinfection is an appropriate UV dose. In North America the vast majority of existing UV installations has been designed to apply a UV dose of 40 mJ/cm2, based on a validation in accordance with either European standards or the Draft USEPA UV Design Guidance Manual 2003.

The Final USEPA UV Disinfection Guidance Manual 2006 introduced a new validation protocol and UV dose requirements in the range of 1.5 to 22 mJ/cm2 for 0.5 to 4.0 log inactivation of Cryptosporidium and Giardia.

These different UV dose requirements have created some confusion in the industry and the reliability of UV disinfection was sometimes questioned.

This paper describes the design approach of the UVDGM 2006 and reviews the impact of the new validation protocol on the performance of UV disinfection systems.

Expected Learning Outcomes:

Participants will be able to understand the design approach of the UVDGM 2006 After the presentation, participants will know the requirements for validation testing according to UVDGM

2006 and the impact on UV system capacity


39

Tuesday 9:50-10:15– Certification / Validation – B3-3 St. John’s Room 1

Impact of Biodosimetry-Based Validation on UV System Design Specifications

Bryan R. Townsend1 and Gary Hunter2

1. Black & Veatch, 8520 Cliff Cameron Drive, Suite 210, Charlotte, NC 28269 2. Black & Veatch, 8400 Ward Parkway, Kansas City, MO 64114

UV systems for secondary wastewater applications are currently designed and operated using a variety of techniques, ranging from mathematically-derived intensity and flow distribution models to biodosimetry based validation testing. Comparing UV system designs proposed by various manufacturers is not an easy task and can be host to a high level of uncertainty and error since engineers evaluating such designs are not typically comparing equivalent approaches. The development of a standardized, modified wastewater validation protocol has gained the support of engineering consultants, UV manufactures, UV testing facilities and the UV Manufacturer's Council of the International Ultraviolet Association. Further fuelled by the results of recent UV system validations that have been conducted in accordance with modified testing protocols based on the UV Disinfection Guidance Manual (UVDGM), the need for a modernized protocol for the validation, sizing and operation of UV systems for the disinfection of secondary wastewater effluent has become increasingly evident.

Although the development of a modified validation protocol is an important first step in the advancement of wastewater UV system design, it is one of several key components to the successful implementation of improved methods for more accurate and reliable UV system design and operation. An increasing amount of design specifications are allowing for or require UV system sizing based on validation testing, however, many of these specifications do not properly address requirements that should be applied to the design and operation of UV systems based on biodosimetry-derived performance models. Many concepts that are key to the proper application of biodosimetry results for UV system design are commonly overlooked or misunderstood, potentially resulting in under or over design of UV systems and inadequate or inefficient operating strategies.

Although the UVDGM was developed for validation, design and operation of UV systems disinfecting surface water for potable applications, many of the concepts and procedures can and should be applied for wastewater applications. Two examples of these extremely important, yet commonly overlooked or misapplied design requirements include RED bias and the selection of a proper design UV dose. This presentation will address these and other design requirements and tactics that should be considered to appropriately size UV systems based on biodosimetry-derived performance equations. Fully understanding these concepts and the impact of various validation approaches on UV system design will equip engineers with the added knowledge to develop proper specifications for safe, accurate and efficient design of UV systems that will attain required disinfection goals, while accounting for the site-specific UV dose-response requirements of the target microorganism.

REFERENCES

USEPA. 2006. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced

Surface Water Treatment Rule; EPA 815-R-06-007 (Washington, D.C.: United States Environmental Protection Agency, Office of Water).


40

Tuesday 9:00-9:25 – Photochemistry – C3-1 Volmer Room 1 & 2

Effectiveness of Ultraviolet Irradiation in Dechlorination as Influenced by Ultraviolet Transmittance

MP Astuti1, RJ Xie2 and MJ Gomez2

1.Water Distribution and Network Department, 2. Centre for Advanced Water Technology Public Utilities Board of Singapore, 80/82 Toh Guan Road East, Singapore 608575

Under various circumstances, treatment is required to remove free residual- and total -chlorine left behind after

chlorination. Among several dechlorination options, UV irradiation, the latest available approach, has been claimed

to outperform the other methods as it does not use chemicals. UV dechlorination, which involves the formation and

consumption of free hydroxyl radicals with strong oxidation potential, uses photonic energy from the low pressure

high output (LPHO) or medium pressure (MP) UV lamp to break down chemical bond of the residual chlorine

and/or other chemical compounds. Little information, however, is available on chlorine removal efficiency under

different treatment conditions. The objectives of this project are: (1) to evaluate the effect of LPHO UV irradiation

on dechlorination, and (2) to investigate the influence of operation conditions, including UV fluence which is

partially related to UV transmittance at 254 nm, on chlorine removal efficiency.

The results showed that under UV irradiation degradation of both free residual- and total-chlorine followed a first

order kinetics and that the chlorine removal efficiency is enhanced with increases in UV fluence and/or in UVT

(Table 1). The kinetics allows the calculation of decay rates in water. The rates suggested that monochromatic UV

would be more effective to remove total-chlorine, whilst polychromatic UV is more effective in the removal of free

residual-chlorine. The maximum UV fluence applied in this study (513 mJ/cm2), however, resulted in only

25% reduction of total-chlorine concentration. Therefore, a much greater UV fluence than 513 mJ/cm2 would be

required to achieve 100% chlorine removal. The chlorine removal efficiency significantly decreased with decreases

in UVT value of the treated water, suggesting that water with poor quality would result in low efficiency of UV

dechlorination due to the presence of scavenge agents. DPD (N,N-diethyl-p-phenylenediamine) has been the most

widely used method for analyzing free residual- and total-chlorine in water. However, the presence of coffee-a

substance used to adjust UVT, or any other UV light absorbing substances, may have interfered with the DPD

colorimetric measurements. Calibration, therefore, would be required to determine the actual chlorine

concentrations in the water samples that contain these colour absorbing substances/scavenge agents.


41

Tuesday 9:25-9:50– Photochemistry – C3-2 Volmer Room 1 & 2

Investigation on the Generation Amount of Nitrite

During UV Irradiation Using Medium-Pressure UV Lamps

Nobuhito YASUI1, Naoyuki KAMIKO2

1. Department of Integrated Science and Engineering, Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japan

2. Department of Environmental System Engineering, College of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japan

When UV disinfection reactor is installed to water supply, it is required to understand quantitatively the generation amount of hazardous disinfection by-products which may be generated during UV disinfection in order to supply safe drinking water. By-products generated by UV irradiation are mainly nitrite and bromate. These substances cause health damage. In water quality standard for drinking water in Japan, as total of nitrate-nitrogen and nitrite-nitrogen must be less than 10 mg/L. (Guideline value of nitrite-nitrogen is less than 0.05 mg/L ). WHO regulated safe water stand as 3 mg/L of nitrite. However, in the present, there are few examples which discussed the generation amount of by-products for UV irradiation. Especially, the clearly evaluation of generation amount does not exist when using a medium pressure UV lamp.

In this study, nitrite was focused on as by-product. In order to quantify the generation amount, the concentration of nitrite after UV irradiation was measured, and the generation mechanisms were discussed. In consideration of actual UV disinfection, tap water was used as sample water. The experiment was conducted by batch type reactor and the potassium nitrate which is the precursor of nitrite and humic acid as dissolved organic matter were added in sample water. As the experimental conditions, the initial concentration of potassium nitrate and humic acid, UV dose rate and pH were changed. The concentration of nitrite and residual chlorine were measured after UV irradiation. UV dose rate was measured using UV meter whose detector main wavelength was 254 nm.

From the concentration change of residual chorine, it turned out that the residual chorine concentration was decreased by UV irradiation. This decrease trend was expressed by first order reaction. From the experimental results, in all experiment when pH of sample was 7, nitrite was not generated for several minutes and after that, generation amount increased in proportion to irradiation time. It was considered that this result was caused by the influence of the residual chlorine concentration in tap water. On the other hand, when pH of sample was 10, the generation amount of nitrite increased as compared with pH 7. These results were the same trend as low pressure UV lamp. Moreover, also the generation inhibition of nitrite was not confirmed. Since the OH ion of sample increased, the generation amount of OH radical by UV irradiation seemed to have increased, and it was considered that the reaction was exceeded by OH radical than generation inhibition of the residual chlorine.

The generation of nitrite was assumed that all the wavelength of UV were involving. And UV dose irradiated to samples was calculated in consideration of distribution of wave lengths of medium pressure lamp, absorbance distribution of sample and wavelength distribution of the detector of UV meter. In result, the sum value of the product of these three distributions is corresponding to UV dose rate on the surface of the sample. The generation rate of nitrite was investigated using the calculated UV dose rate.


42

Tuesday 9:50-10:15– Photochemistry – C3-3 Volmer Room 1 & 2

Intensification of Photocatalytic Process for Industrial Wastewater Treatment with a “Solid” UV Reactor

Jiang Yu, Dan Zhang, Qiuxin Yang and Dandan Huang

Research Group of Environmental Catalyst & Separation Process, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China

New developments in the variety of fields to meet the ever-increasing requirements of human beings have also led to the presence of new compounds in the effluent streams of processing plants, which are not readily degraded by the conventional effluent treatment methods. The focus on waste minimization and water conservation in recent years has also resulted in the production of concentrated or toxic residues. Photocatalysis is an attractive technology with the potential to degrade the new toxic chemicals, bio-refractory compounds, pesticides, etc. either partially or fully, and receives an impressive amount of exposure in the open literature. However, industrial implementation remains limited due to scale up problems and the design of photoreactors. Three issues are essential: photon transfer limitations, mass transfer limitations and photocatalyst surface refreshment. The low photocatalytic efficiency could be related to that the lack of agreement on how to quantify this efficiency, in particular with respect to the photoreactor configuration. And also, there is the absence of examples where the laboratory photocatalysis set-up successfully has been scaled up to an industrially relevant scale. Furthermore, the complexity and high concentration of pollutants in industrial easily lead to photocatalyst deactivation.

Usually, the photoreactor with a line UV lamp is used, and impossible to make any breakthroughs on optimization of mass transfer, photon transfer and photocatalyst surface refreshment. In this work, a concept of “solid” UV source is put forward and used to design a new photoreactor. The “solid” UV source can be concluded as collectives of small ball UV lamp fixed in a reactor with microwave irradiation assistant. In this “solid” UV source system, each small ball UV lamp can be regarded as a “point” UV source. While the effluent passing through the aperture among the “point” UV source can be preceded easily without the limitation of mass transfer and photon transfer, and at the moment the photocatalyst surface can refreshed by the microwave irradiation.

Finally, a primary result showed that the “solid” UV photoreactor fixed in a household microwave oven had at least 3 times photocatalytic performance in comparison of application of traditional line UV photoreactor with using 20mg/L of a methyl orange solution as a sample. Therefore, more focus on the introduction of a small ball light emitting sources with outfield intensification is likely to be the way forward.


43

Tuesday 10:50-11:15– Advanced Oxidation – A4-1 St. John’s Room 2

Reduction of Trietazine from Groundwater by UV

Barrie Holden and Angela Richardson

Anglian Water Services Ltd., Peterborough, United Kingdom

Anglian Water Services (AWS) is the largest of the UK’s water utility companies regarding geographical area. The region is dominated by arable agriculture which presents several water quality challenges including nitrates and pesticides. Fifty percent of AWS’s raw waters originate from groundwater aquifers, some of which are located in remote rural location with minimal surrounding infrastructure and subject to strict planning regulations. One such location is subject to levels of trietazine and bentazone above the EU legislated limit of 0.1µg/l. The conventional treatment for groundwater pesticides in AWS has been granular activated carbon (GAC) but due to the location of this borehole site this could have presented logistical problems.

Ultraviolet (UV) was therefore considered as an alternative treatment strategy. Pilot trials were conducted on site with low and medium pressure UV systems by just photolysis and also with hydrogen peroxide to create an advanced oxidation process. Following the positive outcome of the trials a cost benefit analysis was carried out compared to GAC. Based on this information a 3.5 Mld full scale 72 lamp Trojan UV low pressure system was designed, installed and commissioned by Dec 2006. The plant has duty / stand by reactors as this is a critical source. Based on a %UVT of 96% the plant was designed to reduce a maximum trietazine concentration of 0.20µg/l by a target value of 75% producing water below the legislated limit. Initial performance of the plant reduced trietazine from 0.2 µg/l to 0.06µg/l. The design criteria for bentazone was a 15% reduction, this presented less of a problem as this pesticide was oxidised to <0.02 µg/l by final chlorination. Due to the high nitrate in the water medium pressure UV system and the use of AOP process were discounted due to the impact, cost and control of the final chlorination system.

The paper and presentation will provide details of the pilot trials, process selection, basic cost analysis, full scale design and subsequent operational performance. Since installation of the UV system there has been continued increase in pesticides in the raw water. The change in water quality has taken the installed UV treatment capacity out of the initial design envelope. This has meant a change in operation of the UV current system providing less resilience for the supply of water into distribution. The options and proposed remedial strategies to alleviate this situation in the future will also be discussed.


44


Impact of Advanced Pretreatment on the Feasibility of UV/H2O2 Treatment for Degradation of Organic Micropollutants

Ashlee L. Fuller1, Bram J. Martijn2,

Joop C. Kruithof3, and James P. Malley1

1. University of New Hampshire, 398 Gregg Hall, 35 Colovos Rd. Durham, New Hampshire, USA 2. PWN Water Supply Company North Holland, P.O. Box 2113, 1990 AC Velserbroek, The Netherlands 3. Wetsus Centre for Sustainable Water Technology, P.O. Box 1113, 8900 CC, Leeuwarden, The Netherlands

More and more advanced oxidation with UV/H2O2 is considered as a best available technology for organic contaminant control. However the energy consumption of the process is an important issue. Already in PWN’s collaborative research with UV-supplier Trojan, it was shown that understanding of the kinetics and application of CFD resulted in a reactor design that reduced the power consumption by more than 40% compared to a standard reactor design for conventional disinfection purposes.

Although the required energy consumption of UV/H2O2 is still very substantial, the process has proven to be economically feasible for organic contaminant control purposes such as NDMA degradation (Orange County), taste and odour removal (Aurora) and as a non selective barrier against organic micropollutants (PWN). The economical feasibility would increase significantly with reduced energy consumption and make this technology more attractive to solve a wider range of water treatment problems.

A significant reduction of the energy consumption can be achieved by a strong improvement of the UV-transmittance of the raw water by advanced pretreatment. In a preliminary research effort the composition of the UV absorbing compounds was analyzed. The most important UV absorbing compounds in raw IJssel Lake water are DOC and nitrate. The DOC content (6.5 mg/L) is rather stable over the year. There is a strong seasonal variation of the nitrate content (1-14 mg nitrate/L).

Both DOC and nitrate content can be lowered by pretreatment. In the current situation, conventional pretreatment (CSF) is applied. CSF lowers the DOC from 6.5 mg/L to 4.2 mg/L. Nitrate removal by CSF is insignificant. Currently, PWN researches the feasibility to replace the existing conventional pretreatment of her surface water treatment facility in Andijk with ion exchange in combination with ultrafiltration (IX-UF).

Compared to conventional pretreatment, ion exchange improves the water quality in terms of UV transmittance, extended DOC removal (to 1.0 mg/L) and significant nitrate removal (to 0.2 – 4.0 mg nitrate/L). This improves the conditions for post UV/H2O2 treatment. The scavenging of OH-radicals is reduced and, since PWN applies medium pressure UV-lamps, UV photolysis of micropollutants and H2O2 to generate OH radicals become more favourable.

The degradation of organic micropollutants has been studied in collimated beam experiments. Nitrosodimethylamine (NDMA) is selected as a reference compound sensitive for UV photolysis while 1,4-dioxane is selected as a reference compound sensitive for OH-radical oxidation only. Quantum yield for NDMA and reaction rate constant for 1,4-dioxane have been determined in milliQ water. The constants are in good agreement with literature.

As already mentioned before the water matrix has a strong impact on the conversion of micropollutants. Both competition for UV radiation (NDMA) and competition for OH-radical scavenging (1,4-dioxane) were heavily impacted by the water matrix. By far the best results were achieved after IX-MF with the lowest DOC and nitrate content. These results were confirmed by pilot research. Compared to CSF, the EE/O for IX-UF treated water was reduced with about 50%.


45


Simultaneous Disinfection and Trace Organic Oxidation: Performance and Cost Comparisons Between Advanced Oxidation Technologies

AS PART OF WRF-02-009: STUDY OF INNOVATE TREATMENT ON RECLAIMED WATER

Jeff Bandy1,2, Andy Salveson2 and Tavy Wade2

1. Department of Civil and Environmental Engineering, Duke University, Durham, NC 2. Carollo Engineers, Walnut Creek, CA

The combination of UV, O3, and/or H2O2 in advanced oxidation processes (AOPs) generates highly reactive, unselective oxidants, such as hydroxyl and superoxide radicals, which simultaneously destroy recalcitrant organic contaminants, reduce estrogenicity, and inactivate a wide range of microbial targets. Secondary treated wastewater, which contains many disinfection by-product (DBP) precursors, has been a particularly appropriate candidate for UV disinfection, which rapidly kills bacteria and does not produce DBPs. However, UV/ H2O2 may not be the most efficient way to generate hydroxyl radicals. The objectives of this project are to (1) demonstrate simultaneous high disinfection and trace organic microconstituent oxidation performance of advanced oxidation and (2) provide a cost comparison of AOP options for recycled water disinfection.

Bench-scale disinfection and micropollutant destruction tests were performed at Duke University using media filtered secondary effluent from nine utilities in North America. Inactivation of indigenous coliform bacteria, aerobic spore-forming bacteria, and spiked MS2 coliphage and enteric viruses was determined using methods from literature, Standard Methods, and ISO protocols. The destruction and transformation of individual compounds were measured by solid phase extraction and GC analysis, and the total estrogenicity of the treated samples (measured as estradiol equivalent quotient, EEQ) was determined by the yeast estrogen screen (YES) bioassay. Bench-scale technologies included O3, O3/H2O2, LP/MPUV, LPUV/H2O2, and LPUV/PAA and pilot scale treatment technologies included O3, O3/H2O2, TiO2/UV, LPUV/H2O2, MPUV/H2O2, and MPUV/PAA. Reduction of indigenous coliform, spiked coliphage, spiked N-nitrosodimethylamine (NDMA), EEQ, and background microconstituents was determined for the pilot technologies. High-quality “tertiary recycled” water, meeting California’s strict Title 22 regulations, was the benchmark for the disinfection efficacy of the tested technologies.

UV fluences often used for AOP applications can exceed 400 mJ cm-2, so complete inactivation of nearly all indigenous microorganisms can be expected. However, the cost of such high UV doses limits potential application. Conversely, O3 readily oxidizes microconstituents at low doses, but disinfection by O3 requires much higher doses, especially for cysts and spores. Therefore, the UV AOP studies in this project were designed to examine the UV AOP capacity for microconstituent destruction at reduced fluence levels.

This study has shown that the various disinfection/oxidation systems (UV and ozone based) are viable options to reach the desired objectives of destruction of >90% of EEQ and Title 22 disinfection requirements. Of the tested technologies, ozonation was the least expensive, and TiO2/UV was the most expensive, however further testing and filtration credit can reduce costs substantially. However, operational characteristics (i.e., upstream filter performance, UVT, oxidant demand, etc.) must be analyzed in order to establish the most appropriate treatment technology.


46


New DBD Lamp Combines the Advantages of the LP and MP UV Lamps for UV/H2O2 Oxidation

E.F. Beerendonk1, L.J.J.M. Janssen1, D.J.H. Harmsen1, D.H. Metz2,

A. H. Knol3, J. Geboers4 and G.F. IJpelaar1,5

1. KWR Watercycle Research Institute, P.O. Box 1072, 3430 BB Nieuwegein, the Netherlands, tel. +31 306069673

2. Greater Cincinnati Water Works, 5651 Kellogg Avenue, Cincinnati, Ohio 45228-1123, USA, tel. +1 513 624 5658

3. Duinwaterbedrijf Zuid-Holland, P.O. Box 34, 2270 AA Voorburg, the Netherlands, tel. +31 703577728

4. Philips Lighting BV, Zwaanhoefstraat 2, 4702 LC Roosendaal, the Netherlands, tel. +31 165577240

5. Royal Haskoning, P.O. Box 151, 6500 AD Nijmegen, the Netherlands, tel. +31 243284405

The fact that new and more polar contaminants are detected is a concern of many water utilities world wide. To ensure the production of safe drinking water, utilities are looking for new, effective technologies to remove these contaminants. When utilities consider new technologies, effectiveness is primary, but also costs and by-product formation are important issues.

A few years ago, UV/H2O2 based Advanced Oxidation has been introduced in drinking water treatment practice. The application of this technology is evaluated by examining the degradation efficacy for a wide range of contaminants using medium-pressure (MP) and low-pressure (LP) lamps. Although the characteristics of the existing mercury lamps with respect to output and energy efficiency are different, both lamps are highly used in practice for both disinfection and oxidation treatment. However, both lamps show some disadvantages that can be resolved by a new technology.

The new DBD lamp under development with Philips has features which demonstrate both advantages of the MP lamp as well as the LP mercury lamp. The high output density of the DBD

lamp, which is an advantage of MP lamps to build compact UV systems, will be combined with the energy efficiency comparable to the LP lamp.

Now the question remains what the performance of the DBD lamp is with respect to its use in the UV/H2O2 process for water treatment?

Approach Since the major mechanism in the UV/H2O2 process is the degradation of contaminants by in-situ produced hydroxyl radicals, it is essential to understand how hydroxyl radicals are formed by the individual lamp techniques (MP, LP and DBD). The performance of the UV lamps for the treatment of emerging substances in water was compared by calculating the photon flow absorbed by H2O2; calculating the production of hydroxyl radicals through the conversion of para-chloro benzoic acid and measuring the degradation of selected substances with collimated beam and flow through bench unit.


47

Results From the calculations, it is shown that the DBD lamp is effective in producing photons that are absorbed by H2O2. Secondly, the collimated beam results demonstrate that pCBA is effectively converted for all UV lamps. However, the contribution of direct photolysis to pCBA conversion varies significantly between these lamps. Correcting the data for the contribution of direct photolysis, it can be concluded that the DBD lamp produces significantly more radicals than the MP and comparable to the LP mercury lamps.

Finally, some emerging substances were selected for degradation tests in collimated beam and bench tests. Substances ranging from natural and synthetic hormones to pesticides are effectively degraded by the UV/H2O2 process. The energy requirements of the LP and DBD lamp are similar, but lower than for the MP lamp.

Figure 1: Degradation of some emerging substances in collimated beam tests at 600 mJ/cm2 and a H2O2 dose of 10 mg/L: MP-UV/H2O2 ( ), DBD-UV/H2O2 ( ) and LP-UV/H2O2 ( ).

Figure 2: EEO for some emerging substances in Bench scale tests with a H2O2 dose of 10 mg/L:

MP-UV/H2O2 ( ), DBD-UV/H2O2 ( ) and LP-UV/H2O2 ( ).

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48


Biodosimetry of a Full-Scale UV Disinfection System to Achieve Regulatory Approval for Drinking Water Disinfection


Infilco Degremont, Inc. - Degremont North American Research & Development Center, 510 East Jackson Street, Richmond, VA 23219

Using ultraviolet (UV) as a mean of drinking water disinfection dates back to 1916 in the USA. However, since the discovery in the late 1990's that chlorine resistant pathogens such as Cryptosporidium and Giardia could be effectively inactivated by ultraviolet radiation, the disinfection of drinking water using UV technology has been the focus of increasing attention from municipalities and water treatment professionals in the world. Both the US EPA Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) and the DVGW W294 dictate that for a DWTP to receive credit for UV inactivation of these pathogens, validation testing must be performed to demonstrate that the UV reactor equipment delivers the required dose (40 mJ/cm2) or a certain level of log inactivation.

In 2008 an extensive bioassay validation program was undertaken at the UV Validation and Research Center of New York (UV Center) in Johnstown, New York in order to validate the performance of a large medium pressure cross-flow in-line UV reactor for the disinfection of drinking water. With the objective to generate test data that can be used for efficient sizing per the DVGW and US EPA guidelines a novel bioassay testing approach was followed using two surrogate microorganisms (i.e.T1 and MS2 phage) to challenge test the UV reactor.

Because T1 and MS2 phage exhibit a significant difference in terms of sensitivity to UV-C irradiation the bioassay test data was used to determine a more realistic RED bias uncertainty safety factor per the USEPA UVDGM for dose monitoring in the field. The objective of this paper is to review the results obtained from this bioassay testing.

The results obtained from the UV Intensity setpoint test runs will be submitted to the DVGW for review and approval in an attempt to bridge the gap between two very different bioassay methods, which are actually designed to address the same fundamental requirement: Conservatively validate the disinfection performance of a UV reactor to protect public safety.

This paper focuses on reviewing the test results and the impact of key parameters on the disinfection performance as measured during bioassay validation testing. Key parameters to be discussed include sensor to sleeve distance, lamp UV output and UV sensitivity of the challenge microorganism. Differences in terms of test protocol and results between the two bioassay methods will be highlighted. Careful consideration of the parameters outlined above is a vital component of any reactor validation program, ensuring that UV reactors can deliver the proper UV dose over a wide range of water quality and flow conditions experienced at water treatment facilities throughout the world.


49


Closing the Gap Between Certification (DVGW, ÖVGW, SVGW) and PSS?

Christoph Dicks

AQUAFIDES GmbH

PSS is a relative simple formula for the design, evaluation and comparison of UV systems regarding the performance of disinfection. The formula was developed more than 20 years ago in the absence of modern tools like computational fluid dynamics (CFD) etc. Therefore it is nowadays well know that PSS can just be used to assess a first UV system performance approximation. Certification of UV drinking water systems with DVGW, ÖVGW and SVGW is a biodosimetric test of the real performance of UV systems within in a standardized framework. It is globally the most stringent biodosimetric test regime.

PSS flows are the theoretical maximum flow a UV system could achieve if all cm³ flowing through a UV system are exposed to the same UV dose. UV systems for drinking water which are produced as of today operate relatively far away from this theoretical maximum comparing the PSS data and certification data of several UV system suppliers. To get close to this ideal situation is one of the major challenges for the development of UV systems to make UV disinfection as energy efficient as possible, which is key for the long term success of UV disinfection.

Based on the AQUAFIDES series of UV systems for drinking water disinfection, which have been certified with Arsenal and ÖFI in Vienna in 2008 and 2009, detailed results will be presented, which show that the disinfection performance of state of the art UV systems can come relative close to the PSS value for these systems, if the hydraulics of the UV systems are optimized with tools like CFD, which result in reduced power consumption per disinfected m³.

Based on the gathered data it can be concluded that it is possible to get close to the theoretical optimum PSS, but only if the hydraulics of the UV systems are optimized significantly with tools like CFD.


50

Tuesday 10:50-11:15 – Photobiology – C4-1 Volmer Room 1 & 2

Enhanced Effectiveness of Medium-Pressure UV Lamps on Human Adenovirus and its Possible Mechanism

Gwy-Am Shin1, Jung-Keun Lee1 and Karl G. Linden2

1. Department of Environmental and Occupational Health Sciences, University of Washington. 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105-6099, USA 2. Civil, Environmental, and Architectural Engineering, University of Colorado at Boulder. 428 UCB, Boulder, CO 80309, USA

We determined the kinetics and extent of inactivation of a human adenovirus (adenovirus 2 (Ad2)) by both low- and medium-pressure (LP and MP) UV in order to verify the enhanced effectiveness of polychromatic UV technologies on human adenoviruses and elucidate a possible mechanism for the enhanced effectiveness. Ad2 were suspended in phosphate buffered saline (PBS, pH 7.2) to give a final concentration of ~10

6 50 % Tissue Culture Infectious Dose (TCID50)/mL. A small volume (5 mL) was aliquoted to a 60X15 mm cell culture dish and irradiated with UV doses (both LP and MP) typically used in water and wastewater treatment processes. Finally, UV-irradiated samples were serially diluted 10-fold and assayed onto A549 cells grown in 24-well cell culture plates using TCID50 method.

The results of our study show that MP UV is 2.1-2.6 times more effective (in terms of log10 inactivation) against Ad2 than LP UV in the UV doses tested. The calculated UV dose to achieve 4 log10 inactivation of Ad2 was 63 and 160 mJ/cm2 by MP and LP UV, respectively. Also, our results indicate that there are different levels of repair activity in UV-irradiated Ad2 depending on the UV technologies used. That is, there was a considerable restoration of infectivity of UV-irradiated Ad2 after LP UV irradiation, but no apparent restoration of infectivity of UV-irradiated Ad2 after MP UV irradiation. Therefore, the enhanced effectiveness of MP UV on Ad2 is likely due to its ability to inhibit the repair process in UV-irradiated Ad2. It appears that MP UV would be a more preferred UV technology over LP UV because MP UV is more effective against adenoviruses than LP UV in the UV dose range typically used in water and wastewater treatment processes.


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UV Reactor Challenges with Adenovirus: A Comparison of Adenovirus and MS2 Inactivation in Low Pressure and Medium Pressure UV Reactors

Brian Petri1, Karl Linden2 and Jeanette Thurston3

1. Trojan Technologies 2. University of Colorado, Boulder 3. United States Department of Agriculture

Adenovirus has been shown to have a high resistance to low pressure (LP) UV, and although not reported in any drinking water outbreaks, it has been chosen to define the UV dose requirements for virus credit in the US EPA LT2 ESWTR. Recently Linden and co-authors reported that Adenovirus can be inactivated with lower UV doses when using medium-pressure (MP) polychromatic lamps. Working with Adenovirus Type 2, we verified the decreased UV-resistance of Adenovirus to MP light sources compared to LP light sources using MP and LP collimated beams. In addition, we challenged LP and MP UV reactors with Adenovirus Type-2, in full scale challenges in a specially-controlled facility.

MP germicidal UV dose is determined by weighting measured polychromatic lamp output with an appropriate action spectrum. Typically, germicidally-weighted MP UV doses produce the same levels of inactivation that LP UV doses do. Adenovirus is the only known example of a microbe showing different responses to germicidal MP and LP UV doses. By broad filtering of MP light sources, Linden showed that some of the MP “benefits” were due to wavelengths longer than 254 nm, and that some were due to wavelengths shorter than 254 nm. In real disinfection applications, naturally occurring organic matter in water supplies can preferentially absorb short MP wavelengths and remove some of the “benefits” measured in laboratory experiments. In simple terms, viruses following streamlines farther from MP UV light sources will be exposed to lower amounts of the beneficial short wavelengths.

Linden and co-authors challenged a MP UV reactor and demonstrated its ability to inactivate Adenovirus, but demonstrations of performance “benefits” due to MP technology were indirect. We built upon the former work by doing both LP and MP reactor challenges, to show real-life performance with both technologies, and by doing tests together with both Adenovirus and MS2. MS2 is a well characterized UV challenge surrogate, that responds similarly to germicidal MP and LP UV doses. The ratio of Adenovirus to MS2 inactivation in the LP reactor tests, was by definition, comparable to the LP CB resistances. However, the ratio of Adenovirus to MS2 inactivation in the MP reactor tests was higher, showing that some of the MP “benefits” were delivered in the MP reactor tests. We tested gradients of UVT, to show that the ratio changed as the result of more or less short wavelength filtering, and we tested different MP UV reactors to show that those with smaller effective water layers delivered greater MP “benefits”. Our work confirmed that MP “benefits” do exist for Adenovirus inactivation, and that those “benefits” are delivered using actual UV reactors. Comparisons of LP and MP UV reactors showed this directly, and comparisons of Adenovirus and MS2 inactivation showed the magnitudes of the “benefits” in real life reactors.


52


A Genomic Model for Predicting the Ultraviolet Susceptibility of Viruses and Bacteria

Wladyslaw J. Kowalski, PE, PhD

Immune Buildings Systems, Inc.

A mathematical model is presented to explain the UV inactivation kinetics of viruses and bacteria in terms of specific genomic sequences that have a high potential for photodimerization and photoproduct formation. The absorption of ultraviolet light by the nucleic acids and proteins in DNA and RNA induces cross-links that form dimers and other photoproducts. The specific sequences with high dimerization potential include doublets of thymine-thymine (TT), thymine-cytosine (TC), cytosine-cytosine (CC), and triplets composed of one purine and a pyrimidine doublet in various permutations (ATT, ATC, ACC, GTT, GTC, GCC, etc.). The complete genomes of 45 animal viruses and bacteriophages, and 28 bacteria, were evaluated using base-counting software to establish the frequency of occurrence of each dimerizable doublet and triplet. Three models were developed, one for single-stranded RNA viruses in the A conformation, one for double-stranded DNA viruses in the B conformation, and one for bacteria in the B DNA conformation. These theoretical models are based upon the standard model of UV inactivation kinetics as proposed by Setlow, Carrier, Hanawalt, Smith and Wang from the 1960s, and the later refinements of the model by Becker and Wang in the 1980s. The recent publication of complete genomic sequences for many important pathogens has allowed the existing theory of UV inactivation to be tested to a level of statistical significance not previously possible, and the analyses presented offer good corroboration of the standard model. The model treats the sequence frequencies as probabilities proportioned by their estimated relative lethality. The probability density map of the susceptible target sites is distributed in a spherical model of a DNA or RNA molecule of which a circular cross-section is exposed to UV irradiation. The probability density is correlated with extensive data sets of water-based inactivation D90 values (UV doses for 90% inactivation) culled inclusively from the literature. Multiplication factors (constants) were established to define the relative lethality of each type of potential dimer via curve fitting, and results are in reasonable agreement with published values for photoproduct frequencies of occurrence. D90 values from 48 data sets were used to represent 22 RNA viruses in the RNA model, which had an r2 value of about 65%. Some 61 data sets were used to represent 23 DNA viruses in the DNA model and this model achieved an r2 of about 50%. Some 57 data sets were used to represent the bacteria, which had a lower r2 of about 33%. The lower r2 value for DNA viruses is likely due to the greater photoprotective and repair mechanisms of the larger viral genomes and their nucleocapsids, and a similar explanation can be made for the bacteria, which have thick cell walls and cytoplasm to provide more photoprotection. Methods for extrapolating results to airborne disinfection processes at various relative humidities are addressed. The photoprotective effects of UV-absorbing nucleocapsids and cell walls, and from light-scattering effects are discussed and presented as part of a more general and complete hypothetical model that may lead to greater predictive accuracy. Predictions of ultraviolet inactivation D90 values and UV rate constants are presented for dozens of viruses and bacteria important in air, water, and surface disinfection applications that have not previously been analyzed for UV susceptibility in laboratory experiments.


53


Impact of Antecedent Cultivation Conditions on the UV-C Resistance of Escherichia coli and Spores of Bacillus subtilis

Margarete Bucheli-Witschel, Claudio Bassin, Bernhard Roos and Thomas Egli

Eawag, Swiss Federal Institute of Aquatic Science and Technology; Department of Environmental Microbiology

Überlandstrasse 133; P.O. Box 611; CH-8600 Dübendorf, Switzerland

Growth conditions determine the composition and physiological state of microorganisms. Consequently, they have a significant impact on the resistance of bacteria towards disinfectants such as irradiation with UV-C light at 254 nm. The influence of antecedent cultivation conditions on the UV-C susceptibility was studied in two microorganisms, i.e. in spores of B. subtilis, the test organism for biodosimetric testing of UV disinfection devices in Germany and Austria, as well as in E. coli, a typical model organism in drinking water microbiology.

For spores of B. subtilis ATCC 6633 we investigated how the composition of the sporulation medium affected UV-C resistance; the starting point was the medium proposed in the German standards for biodosimetric testing of UV devices (DVGW W294-2, 2006). The concentrations of divalent cations in the medium, especially the concentrations of Ca2+ and Mn2+, turned out to be the main factor determining spore resistance. By varying the concentrations of these cations we were able to reproducibly produce spores with different UV-C resistance. It was shown in B. cereus that omitting Ca2+ from the sporulation medium resulted in spores with a low content of dipicolinic acid (DPA), a molecule that is known to act as photosensitizer making spores in aqueous solution more UV-C sensitive. However, DPA concentrations in spores of B. subtilis appeared not to be influenced in the same way. Moreover, UV-C resistance did not correlate with the amount of DPA found in the spores.

UV-C resistance of E. coli was examined as a function of medium composition, nutrient limitation, and specific growth rate during antecedent cultivation. Medium composition only slightly influenced UV resistance, whereas specific growth rate greatly affected it. The reduction by UV-C irradiation at 60 J m-2 varied up to about four decades in cells which had been cultivated at different specific growth rates. E. coli cells grown in chemostat culture at a dilution rate between 0.2 h-1 and 0.3 h-1 were the most susceptible to UV-C, while cells cultivated at lower or higher specific growth rate showed an increased resistance. The highest UV-C resistance had non-growing cells from the stationary phase of a batch culture. Experiments with an rpoS_ mutant indicated that the alternative sigma factor RpoS, which is the global regulator of the general stress response in E. coli, is also involved in the UV-C resistance in cells growing at low specific growth rates and stationary phase cells. The elevated UV-C resistance observed for E. coli grown at high specific growth rates might be due to an increased amount of DNA per cell.

Our results stress the necessity to exactly define and describe antecedent growth conditions when testing UV-C inactivation of microorganisms. In particular, growth conditions should be chosen, which more closely approximate the situation in raw water used for drinking water production.


54


Selecting Removal Goals for Advanced Oxidation with UV and Hydrogen Peroxide

Jeff Neemann1, Bryan Townsend2, Bob Hulsey1 and Gary Hunter1

1. Black & Veatch, Kansas City, Missouri 2. Black & Veatch, Charlotte, North Carolina

For many utilities, taste and odor control represents an important aesthetic aspect of water treatment. Ozone has long been seen as one of the most effective technologies for taste and odor control as it removes MIB and geosmin and can be made even more effective if used in conjunction with hydrogen peroxide (H2O2). While UV is a very powerful disinfectant, at the doses for disinfection, it does not oxidize taste and odor compounds such as MIB and Geosmin. In order to react with MIB and Geosmin, hydrogen peroxide must be added just prior to the UV reactor, a method that is called an advanced oxidation process (AOP). The UV light reacts with the hydrogen peroxide to form hydroxyl radicals, which are a strong oxidant that react with taste and odor causing compounds. While taste and odor control can be achieved with UV/H2O2, it comes at a cost, as the power required to operate in an AOP mode can be over five to ten times the power needed for typical Cryptosporidium disinfection.

Selecting and understanding the AOP design parameters and their impact on the equipment sizing is very important. Key parameters include the target percent removal of the taste and odor compounds, the flow rate during an event, the duration of the event, and the design UV transmittance (UVT). All of these can substantially impact the sizing and ultimately the cost. Selecting conservative parameters for the percent removal, event duration, and UVT can lead to a very large system that might not be cost competitive with other taste and odor control methods.

Other considerations for the design of the system include selection of lamp type, optimization of peroxide use versus energy, selection of a fouling factor, selection of an end of lamp life factor, meeting a process guarantee, and conducting full-scale performance testing. A medium pressure system would typically be smaller and have lower capital cost, however, a low pressure high output system would use less power, which could result in lower operating cost. A challenge when designing without extensive water quality data is to select a fouling factor and end of lamp life factor that is conservative to ensure the system would meet the performance guarantee, but not too conservative so as to oversize the system and drive up the capital cost. Another challenge is considering in the design how to conduct a full-scale performance test to demonstrate compliance.

This presentation will show three different project examples and compare and contrast their design approaches and how selecting the design parameters impacted the equipment sizing. The capital and operating costs projections for the full-scale treatment scenarios will be presented and compared and the sensitivity of the costs to MIB/Geosmin concentrations and duration of taste and odor event will be discussed.


55


UV Treatment for the Reduction of Metaldehyde in Surface Waters

Barrie Holden1, Ella Lamming1 and Alan Royce2

1. Anglian Water Services Ltd., Peterborough, United Kingdom 2. Trojan Technologies, London, ON, Canada

Anglian Water Services (AWS) is the largest of the UK’s water utility companies in terms of geographical area. The region is dominated by arable agriculture which from which is derived several water quality challenges including the presence of nitrate and pesticides. Following privatisation in 1989, AWS installed multi-barrier treatment systems utilising granular activated carbon (GAC) and ozone for the reduction of pesticides in its surface water treatment plants. This strategy was found to be robust and efficient for the removal of then-detected pesticides and other micropollutants.

However, in 2008 other pesticides previously not detected were found in raw surface waters. Further, metaldehyde and clopyralid, two of the emerging pesticides studied, are not removed effectively by GAC/ozone. Metaldehyde and clopyralid are permitted for use by the Pesticide Safety Directive and in most cases are comparatively more polar and therefore easier for the farmer to apply. Metaldehyde and clopyralid are extensively used throughout the region for such crops as oilseed rape and wheat to control slugs and thistles respectively. They have low risk to human health and low environmental impact at typical application rates. Due to their extensive use, however, these pesticides migrate into water courses at levels exceeding EU legislated limit for pesticides (0.1µg/L). Their presence in waters used for potable supply, and the inability of ozone/GAC to remove the compounds, has required that other treatment options be investigated. A promising treatment technology is treatment with ultraviolet (UV) light and hydrogen peroxide, a process known as UV advanced oxidation or simply UV-oxidation

The Innovation Department of AWS is working closely with Trojan Technologies and has carried out several experiments to demonstrate the efficacy of UV-oxidation for the treatment of various emerging pesticides. This work involved both the performance of treatability screening trials as well as the determination of the fundamental kinetic parameters controlling the UV-oxidation of metaldehyde. From this initial work direct UV photolysis was found not to be an effective treatment mechanism. The combination of UV and hydrogen peroxide, however, effectively destroyed metaldehyde.

Further investigation of the reduction of metaldehyde and clopyralid with UV and UV / H2O2 are currently being carried out on low and medium pressure pilot plants treating water from one of AWS reservoirs. Results from these investigations will be presented. Further, based on pilot scale results combined with experience in sizing full-scale UV-oxidation systems, a comparison with current GAC/ozone treatment will be determined including potential cost implications, design criteria and required process stream for implementation at full scale.

Bench-Scale UV Metaldehyde Destruction Results

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25 30 35 40 45 50

UV Treatment Time, min

Lo

g R

edu

ctio

n o

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etal

deh

yde

Post RGF - 10 ppm H2O2 Post GAC - 10 ppm H2O2 Post RGF - 0 ppm H2O2 Post GAC - 0 ppm H2O2


56


Genotoxicity Study on UV/H2O2 Treated Surface Water Using Comet and SCE Assay

Eric J.M. Penders1, Bram J. Martijn2, Wim Hoogenboezem1 and Gerrit M. Alink3

1. Het Waterlaboratorium, P.O. Box 734, 2003RS Haarlem, The Netherlands 2. PWN Water Supply Company North Holland, P.O. Box 2113, 1990 AC Velserbroek, The Netherlands 3. Wageningen University, P.O. Box 8000, 6700 EA Wageningen, The Netherlands

PWN Water Supply Company North Holland, one of the leading water supply companies in The Netherlands, produces water for over 1.5 million inhabitants with an annual production of 100 million m3. Part of this production concerns direct surface water treatment, using advanced processes like membrane filtration or UV/H2O2 treatment. In the 1998, PWN was the first water supply company in the world to apply ultra filtration and reverse osmosis in a full scale drinking water treatment plant. In 2004, PWN was world wide the first water supply company to implement full-scale UV/H2O2 treatment. By UV/ H2O2 treatment, organic micropollutants (i.e. residuals of pharmaceuticals, pesticides) are degraded into biodegradable compounds. Granular Activated Carbon (GAC) filters are installed after the UV/H2O2 treatment prevents as a safety barrier against biodegradable (AOC) and harmful (nitrite) compounds and to degrade the excess of H2O2.

In water treatment processes where compounds are transformed, the formation of genotoxic compounds is a potential problem. Until now, laboratory tests like the Ames test or Comet assay are used for the detection of mutagens. Some results using the Ames TA98 and Comet assay (using lymphocytes as “sensor”) will be presented in this study. Because of the low sensitivity of these laboratory tests, a procedure to concentrate water samples is required. A major drawback of concentrating a water sample is the possible loss (or inadequate adsorption) of hydrophilic compounds. A different approach for measuring mutagens and genotoxic compounds in treated waters is presented, using the Comet assay and a sister chromatide exchange assay (SCE) while no concentration procedures are required. These methods have shown to be sensitive enough to demonstrate genotoxicity in raw river Rhine surface water (Alink et al., 2007) and show the effect of drinking water treatment steps such as UV/H2O2 treatment and GAC filtration. This paper shows some results of the study that was performed with this method at the PWN’s surface water treatment facility at Andijk.

G.M. Alink, J.T.K. Quik, E.J.M. Penders, A. Spenkelink, S.G.P. Rotteveel, J.L. Maas and W. Hoogenboezem. Genotoxic effects in the Eastern mudminnow (Umbra pygmaea L.) after exposure to Rhine water using the SCE and Comet assay; a comparison between 1978 and 2005. Mutation Research 631, 2007, pages 93 - 100


57


Formation and Removal of Genotoxic Activity During UV/H2O2-GAC Treatment of Drinking Water

M. B. Heringa1, D.J.H. Harmsen1, A.A Reus2, C.A.M. Krul2, A.H. Knol3, D.H. Metz4, E.F. Beerendonk1 and G.F. IJpelaar1

1. KWR Watercycle research institute, PO Box 1072, 3430 BB Nieuwegein, the Netherlands 2. TNO Quality of Life, Zeist, the Netherlands 3. Duinwaterbedrijf Zuid-Holland, Voorburg, the Netherlands 4. Greater Cincinnati Water Works, Cincinnati, Ohio, USA

Introduction and rationale

Several studies have shown that UV/H2O2 treatment followed by granulated activated carbon (GAC) filtration is effective for the removal of various organic compounds like pesticides and drugs in water (Kruithof, 2007). As a result, water utilities have introduced the combination of these processes for the production of potable water. However, until now it was unknown whether or not UV/ H2O2 treatment may lead to the formation of (geno)toxic byproducts, as is the case with ozonation (e.g. von Gunten and Hoigne, 1994) and chlorination (e.g. Rook, 1974; Richardson, 2007). To fill this knowledge gap, this study focused on the effect of UV/H2O2 treatment with and without GAC filtration on the genotoxic activity of the treated water.

Experimental design

Water from the river Meuse (the Netherlands) and from the Ohio river (USA), pretreated by coagulation and rapid sand filtration (see table 1 for water quality parameters), was treated with UV/H2O2 in a pilot reactor, using both low pressure (LP) and medium pressure (MP) UV lamps. Samples were extracted and concentrated by solid phase extraction (SPE) with Oasis HLB and analyzed for genotoxicity using the Comet assay with HepG2 cells and the Ames II assay with the TAMix and TA98 strain with and without metabolic activation (S9).

Table 1. Water quality parameters of pre-treated river Meuse and Ohio water after coagulation and rapid sand filtration.

Nitrate pH Alkalinity TOC 1 UV-T254

(mg NO3-/L) (mg HCO3

-/L (mg C/L) (%, cm-1)

Meuse

LP lamp

8.0 8.09 148 3.8 79

Meuse

MP lamp

5.8 7.06 151 3.9 78

Ohio 3.1 7.7 93.3 1.95 90.6

1 Measured as NPOC: Non-Purgeable Organic Carbon


58

Results and discussion

An increase in genotoxicity was observed after UV/H2O2 treatment in some samples from the pilot setups in the Ames II assay. (Specific results will be presented at the meeting as they were still confidential at the time of abstract submission). The observed genotoxic activity was not due to residual H2O2 or sulfite used to quench residual H2O2, as pretreated water with similar levels of H2O2 and sulfite did not give any significant response in the Ames II (figure 1).

After GAC filtration no genotoxic response was detected, with the absolute response actually being lower than that of the original pretreated source water. Therefore, no health risks are expected as long as GAC filtration follows UV/H2O2 treatment.

0

5

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Figure 1: Results of Ames II tests with TA98 (grey bars) and TAMix (white bars) with (striped bars) and without (empty bars) S9 on extracts of the pre-treated Meuse water with and without additions of H2O2 (10 mg/L) and NaSO3 (100 mg/L) in experiments with low-pressure (LP) and medium pressure (MP) lamps. Bars denote average values, error bars denote standard deviations (n = 3).

References

Von Gunten, U. and Hoigne, J. (1994) Environ. Sci. Technol. 28 (7), 1234-1242.

Kruithof, J.C. et al. (2007) Ozone: Sci. Engin. 29(4), 273-280.

Richardson, S.D. et al. (2007) Mutat. Res. 636(1-3), 178-242.

Rook, J.J. (1974) Wat. Treatment Exam. 23 (2) 234-243.


59

Tuesday 13:30-13:55 – UV Measurement – B5-1 St. John’s Room 1

Measurement of the UV Output and Efficiency of Medium Pressure UV Lamps

James R. Bolton, Ph.D.1, Keith Bircher2 and Brad Crawford2

1. Bolton Photosciences Inc. 2. Calgon Carbon Corporation

A method is proposed for the measurement of the UV output of medium pressure (MP) UV lamps.

This method is based on the recently adopted IUVA Protocol for the measurement of the UV output of low pressure (LP) UV lamps, but in addition, provision has to be made for the fact that MP UV lamps have a spectral emission over a broad range of wavelengths. This requires measurement of the relative spectral irradiance of the lamp and a determination of the sensitivity of the radiometer detector over the wavelengths for which the detector has a significant sensitivity. The UV output (200 – 300 nm) and efficiency were measured for two new 10 kW MP UV lamps. The results were an ‘unweighted’ efficiency (200 – 300 nm) of 18.5% relative to the electrical power across the lamp and 17.5% relative to electrical power from the wall. The corresponding ‘germicidal efficiencies were 14.2% and 13.4%, respectively.


60


Comparison of the Microbicidal Efficiency of Low Pressure and of Medium Pressure Mercury Lamps

Alexander Cabaj1, Regina Sommer2 and Thomas Haider3

1. Veterinary University Vienna 2. Medical University Vienna 3. Institut fur Umwelthygiene Medizinische Universitat Wien

The definition of the physical term “fluence” as a measure of the “dose” for low pressure Hg-lamps and also for medium pressure Hg-lamps is quite straight forward because no biological weighting functions are involved. The physical, unweighted fluence Ho (or fluence rate E0) may be calculated from the spectral fluence Ho,λ(λ) (or spectral fluence rate Eo,λ(λ)).

But, if the biological efficiency shall be taken into account, the appropriate weighting functions must be used and the microbicidally weighted fluence Ho,λ,mic(λ) (or the microbicidally weighted fluence rate Eo,λ,mic(λ)) can be calculated from the following formulas:

400

200

mic,omic,o,

400

200

mic,omic,o, d)(s)(E)(Eord)(s)(H)(H

where smic is the microbicidal weighting function of interest, normalized to 1 at maximum.

If the aim is to express if the emission spectrum of a UV-lamp is suitable for use with a process which has a special biological weighting function, a microbicidal index of effectiveness imic can be applied which is defined by:

400

200400

200

micmic

d)(E

)(E)(ewhered)(s)(ei , )(e is the normalized spectral irradiance,

normalized in such way that the area below the curve is 1:

400

200

1d)(e .

The value of imic does not depend on the absolute value of the spectral irradiance, only the relative spectral irradiance is of relevance, one could say “the shape” of the spectrum is the relevant factor. When the whole spectrum of the radiation is in a wavelength-region where smic(λ)=1 then the microbicidal index of effectiveness is 1. But, in general imic is smaller than 1. In other words: imic gives the relative amount of the microbicidally weighted spectrum compared to the unweighted spectrum. Using imic it is possible to compare spectra of UV-lamps with respect to the efficiency of the radiation to inactivate microorganisms. Thereby only relative spectra are used, the absolute spectral distribution is not used for this calculation. It is clear that the ideal UV-lamp for disinfection purposes would be one with only one UV-line with wavelength equal to the wavelength of maximum sensitivity of the microorganism. In reality this is not achievable and therefore imic in general is smaller than 1 for real lamps.

Results We applied this concept especially in order to be able to make a decision which type of UV-lamp is more efficient for disinfection, low pressure or medium pressure Hg-lamps. Of course the electrical efficiency also must be taken into account and has high influence on the overall efficiency.

References Austrian National Standard PRESTANDARD ÖNORM M 5873-2:2003


61


Comparison of UV Power Measurement of Low Pressure

UV-lamps by a worldwide Round Robin Test

Volker Adam, Martin Kessler and Ralf Dreiskemper

Heraeus Noblelight GmbH, Heraeusstrasse 12 -14, 63450 Hanau, Germany

Facing the challenge of designing UV systems to meet specific disinfection requirements has become increasingly more complex with the various lamp technologies and configurations available. Whether the chosen design method is a calculated sizing model, such as point source summation, or biological verification, it is important to adhere to strictly defined experimental protocols and quality controls. This is most apparent when considering technology comparisons from different manufacturers. In particular the lamp output measurement procedure used can significantly affect the outcome of measurement results. If the tests are conducted under identical protocols, a proper and fair comparison between competing lamps is feasible. Therefore the IUVA Manufacturers Council organized a taskforce in 2007, with the aim of preparing a consistent method for the determination and benchmarking of UV lamp output from monochromatic (254 nm) lamps operated by a corresponding power supply (ballast). The goal was for this method to be used for testing and comparing testing results from different laboratories. As a further step the taskforce arranged an intercomparison program for laboratory testing of a sample batch of LPM lamps in a number of locations in Europe and North America. This round robin test will help determine the suitability of this testing method and provide an indication of the measurement uncertainty. This paper outlines the lamp measurement method drafted by the task force and subsequently published in the IUVA News. In addition this paper will present the method and the results of the LPML intercomparison program.


62


Implementation of the European Directive on Optical Radiation Safety Takes Place in May 2010

F.P. Wieringa1,2

1. TNO Science and Industry, P.O. Box 155, 2600 AD, DELFT, the Netherlands 2. Scientific Advisory Board of Radtech Europe

Directive 2006/25/EC of the European Parliament and of the Council of 5 April 2006 on the minimum health and safety requirements regarding the exposure of workers to risks arising from physical agents (artificial optical radiation) is the 19th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC.

At the latest by May 10th 2010 this EU-Directive will have to be implemented by all EU-member states. It adopts the already existing ICNIRP limit values for the ultraviolet, visible and infrared range which are internationally recognized as best practice.

Legal implications for employers, utilizing optical radiation sources that present a possible hazard, are:

• determination of health risk for employees • restriction of exposure • medical support • training and information for employees

For IUVA-members the UV-range is most relevant. Human UV-exposure can lead to acute effects (skin: erythema; eyes: photokeratitis) and long term effects (skin: accelerated skin aging, basal cell carcinoma, squamous cell carcinoma, malignant melanoma; eyes: cataract).

For the effective radiant exposure Heff (weighted dose) the daily exposure (8 h) limit value is 30 J m-2 with an additional requirement that the unweighted UVA-dose HUVA shall not exceed a daily exposure limit value of 104 J m-2.

The implementation of the new EU-Directive is facilitated by EN 14255, a four part series of European standards. The first part of this series is EN 14255-1 "Measurement and assessment of personal exposures to incoherent optical radiation - Part 1: Ultraviolet radiation emitted by artificial sources in the workplace", which was published in March 2005.

Several EU-countries have published informative guidance documents and/or software tools in their national language. Furthermore, a European informative non-binding guide to the new EU-Directive is in preparation.


63


Chlorine and UV Disinfection of Selected Antibiotic-Resistant Strains of Escherichia coli

Michael R. Templeton1, Francine Oddy1, Wing-kit Leung2 and Michael Rogers1

1. Department of Civil and Environmental Engineering, Imperial College London South Kensington campus, London, United Kingdom SW7 2AZ 2. Centre for Environmental Policy, Faculty of Natural Sciences, Imperial College London South Kensington campus, London, United Kingdom SW7 2AZ

It has been reported that there is sometimes a greater proportion of antibiotic-resistant bacteria in treated water and wastewater effluents compared to the proportion in untreated water and wastewater, suggesting that treatment may somehow select for antibiotic-resistant survivors (Meckes 1982; Iwane 2001 et al.; Kim and Aga 2007). Several explanations have been proposed for this observation, such as a special phenotypic tolerance to disinfection (Seyfried and Fraser, 1980) or protective capsule formation by antibiotic-resistant organisms (Reilly and Kippin, 1981). On the other hand, other studies have reported no effect or inconsistent effects of treatment on the selective survival of antibiotic-resistant bacteria post-treatment. For example, Bell et al. (1983) observed a decrease in antibiotic-resistant faecal coliform bacteria in short-term retention lagoons and mechanical treatment plants but an increase in these bacteria in long-term retention lagoons. Mezrioui and Baleux (1994) reported an increase in the percentage of antibiotic-resistant Escherichia coli during treatment in an aerobic lagoon, but no change in the percentage before and after an activated sludge process. Iwane et al. (2001) observed an increase in the percentage of ampicillin-resistant coliform bacteria after conventional wastewater treatment but a decrease in tetracycline-resistant bacteria. Kim et al. (2006) demonstrated an influence of changes in activated sludge process operating conditions on the fate of antibiotic-resistant bacteria in wastewater treatment. The impact of disinfectants on antibiotic-resistant organisms has not been widely researched. This bench-scale study investigated whether strains of Escherichia coli that are resistant to two common types of antibiotics, ampicillin and trimethoprim, possess increased resistance to two common disinfectants in water and wastewater treatment, free chlorine and low pressure ultraviolet disinfection, relative to an antibiotic-sensitive strain of E. coli that was isolated from sewage sludge. Ampicillin and trimethoprim were selected to represent two important classes of antibiotics, β-lactams and dihydrofolate reductase inhibitors, respectively, which operate against bacteria via different mechanisms. Trimethoprim-resistant E. coli 018 was more resistant to chlorination than ampicillin-resistant E. coli 145 and antibiotic-sensitive E. coli (Fig. 1). The differences between the chlorine dose-response of the strains, while statistically significant under the chlorine Ct values and different pH ranges tested in this study (95% confidence level), would be negligible for the much higher chlorine Ct values that are typically applied in practice. Neither ampicillin-resistant nor trimethoprim-resistant E. coli demonstrated increased resistance to low pressure UV disinfection versus the antibiotic-sensitive isolate of E. coli over the UV dose range that was considered (Fig. 2). Overall, therefore, the results of this study suggest that these disinfectants likely do not select for ampicillin-resistant nor trimethoprim-resistant survivors during water and wastewater treatment. Bibliography

Bell, J.B., Elliott, G.E. and Smith, D.W. 1983. Influence of sewage treatment and urbanization on selection of multiple resistance in fecal coliform populations. Applied and Environmental Microbiology 46: 227-232.

Iwane, T., Urase, T. and Yamamoto, K. 2001. Possible impact of treated wastewater discharge on incidence of antibiotic resistant bacteria in river water. Water Science and Technology 43: 91-99.


64

Kim, S., Jensen, J.N., Aga, D.S. and Weber, A.S. 2006. Fate of tetracycline resistant bacteria as a function of activated sludge process organic loading and growth rate. Water Science and Technology 55: 291-297.

Kim, S. and Aga, D.S. 2007. Potential ecological and human health impacts of antibiotics and antibiotic-resistant bacteria from wastewater treatment plants. Journal of Toxicology and Environmental Health, Part B 10: 559-573.

Meckes, M.C. 1982. Effect of UV-light disinfection on antibiotic-resistant coliforms in wastewater effluents. Applied and Environmental Microbiology 43: 371-377.

Mezrioui, N. and Baleux, B. 1994. Resistance patterns of E.coli strains isolated from domestic sewage before and after treatment in both aerobic lagoon and activated sludge. Water Research 28: 2399-2406.

Reilly, J.K. and Kippin, J.S. 1981. Interrelationship of Bacterial Counts with Other Finished Water Quality Parameters within the Distribution System. EPA-600/S2-81-035. USEPA, Cincinnati, Ohio.

Seyfried, P.L. and Fraser, D.J. 1980. Persistence of Pseudomonas aeruginosa in chlorinated swimming pools. Canadian Journal of Microbiology 26: 350-355.

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Figure 1. Comparison of chlorine dose-response for trimethoprim-resistant E. coli 018, ampicillin-resistant E. coli

145, and the antibiotic-sensitive E. coli isolate from sewage sludge. pH = 7.0, n = 3.

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Figure 2. Comparison of UV dose-response for trimethoprim-resistant E. coli 018, ampicillin-resistant E. coli 145, and the antibiotic-sensitive E. coli isolate from sewage sludge. n = 3.


65


Activity of Various Catabolic Functions in UV-C Irradiated Escherichia coli

Margarete Bucheli-Witschel, Anna Ehlert, Yves Meur and Thomas Egli

Eawag, Swiss Federal Institute of Aquatic Science and Technology; Department of Environmental Microbiology, Überlandstrasse 133; P.O. Box 611; CH-8600 Dübendorf, Switzerland

It is generally accepted that the effectiveness of UV disinfection is due to UV light between 240 and 300 nm because DNA molecules have an absorption maximum at 265 nm. Hence, UV irradiation induces the formation of DNA damages, in particular the formation of the DNA photoproducts cyclobutan pyrimidine dimer (CPD) and 6-4 photoproduct. The accumulation of DNA damages leads to an inhibition of transcription and replication and thus prevents the cells from multiplying. However, little is known on additional effects of UV irradiation on cellular functions. Therefore, we studied the impact of UV-C irradiation on the metabolic activity of E. coli cells that had been cultivated on a complex medium (LB) into stationary phase. Activity of catabolic functions in non-irradiated control cells as well as in UV-C irradiated (400 J m-2) bacteria was analysed with a respiration assay based on BIOLOG AN Microplates. The BIOLOG AN Microplate performs 95 discrete substrate utilisation tests simultaneously, thereby providing a characteristic reaction pattern called a metabolic fingerprint. In the test wells, oxidation of an organic substrate results in colour formation due to the reduction of a tetrazolium salt. Monitoring the colour formation as a function of time enables quantification of the activity level for individual substrates.

While oxidation of several sugars such as D-fructose or α-D-glucose was not significantly affected by UV-C irradiation, oxidation of organic acids, amino acids and peptides as well as nucleotides was markedly reduced upon irradiation. All together, even after exposure to 400 J m-2 UV-C many catabolic pathways were still active though at a reduced level.

Currently, further experiments based on respiration measurements in an oxygen electrode as well as ATP determination upon substrate addition are performed to support the results from the monitoring with the BIOLOG microplates.


66


Preliminary Study on Whole-Phase Control of Photoreactivation after UV Disinfection

Meiting Guo1, Hongying Hu1 and Jian Chen2

1. ESPC State Key Joint Laboratory, Department of Environmental Science & Engineering, Tsinghua University,Beijing, China 2. Fujian Newland EnTech Co., Ltd

Ultraviolet disinfection becomes an alternative to chlorine disinfection for its advantages of wide-range inactivation and safe operation. However, photoreactivation has one significant shortcoming, which weakens the high inactivation efficiency (Hijnen, 2006). How to control photoreactivation after UV disinfection, while keeping advantages of UV, is becoming a popular topic. Photoreactivation of microorganisms after UV disinfection experiences three main phases: photoreactivation startup, photoreactivation phase and stationary phase. It is important to control the maximum photoreactivation. Three strategies regarding to three phases are suggested here. First, reduce the initial microorganism concentration through strengthening disinfection effect. Second, inhibit photoreactivation with delaying to light. Third, cut down maximum microorganism number by secondary disinfection, like applying chlorine. The objective of this research was to investigate the possibilities and optimization of controlling photoreactivation according to above strategies.

E. coli was used as test microorganism. Collimated beam apparatus, equipped with a low pressure UV lamp (40 W), was used for UV exposure experiments. A sunlight lamp (20W, F20T12, Philips, USA) was used as the light source for photoreactivation. Three strategies were embodied experimentally here. One was to investigate photoreactivation level after higher UV dose irradiation （40 and 80 mJ/cm2） or peroxide acid (PAA) addition with concentrations of 1-3 mg/L. The other was to delay UV irradiated water samples exposing to sunlight for photoreactivation. The third was to add chlorine into UV disinfected water samples before photoreactivation. The ratio of the concentration (in CFU/mL) of the repaired microorganisms (Np-Ni ) and irradiated microorganisms (N0-Ni) , which was called percentage photoreactivation, was used to evaluate the effect of photoreactivation. Survival, which was defined as Np/Ni, was also used.

The experimental results showed that, UV dose, as high as 80 mJ/cm2, could control percentage photoreactivation of E. coli at 6.1×10-4%. PAA, added before UV, could produce hydroxyl radicals to enhance disinfection efficiency. PAA of 3 mg/L helped UV to reduce percentage photoreactivation below 10-4%. Delaying to exposure on photoreactivating light for 24 h could inhibit percentage photoreactivation of E. coli to 0.3%. Combination with chlorine could inactivate bacteria during its photoreactivation. Chlorine of 3 mg/L was the lowest concentration to inhibit photoreactivation for 24 h in the study situation. PAA/UV and UV/chlorine were suggested for application. It was indicated that, photoreactivation could be and should be controlled during its whole phase of photoreactivation to ensure the water safety for reclamation.


67


The Biological Safety of Model Distribution System Following UV

Sun Wenjun, Liu Wenjun, Cui Lifeng, Zhu Wanpeng

Department of Environmental Science and Engineering, Tsinghua University, Beijing, 10084

Water distribution system biofilms is a public health concern as they are potential sources of pathogenic bacteria and indicator organisms. It has been demonstrated that potential pathogens have the ability to survive, reproduce, and form biofilms under potable water conditions. UV’s inability to have an enduring disinfecting effect on the distribution system is one of the most important factors which limit its applications in drinking water treatment. Hence, most waterworks employing UV disinfection usually add chemical disinfectants such as chlorine or chloramine after the application of UV in order to sustain the disinfecting effect in the distribution system.

The overall goal of this research is to estimate the controlling effect of UV and its combined disinfection manners for the biofilm of a model distribution system. Also, the specific objectives of this research are to characterize (1) the impact of chlorine residual on the HPC concentration in the model distribution system following UV, (2) the selectivity of UV for the microbiologic population on different pipe materials, and (3) characteristic of the bacteria which is very chorine resistant in the model distribution system.

In this experiment, it used biological annular reactor (BAR) to simulate the model distribution system. For the measurement of biofilm, it used molecular biology methods such as PCR-DGGE and FISH to analysis the microbiological composition and other characteristics of biofilm.

The results showed that: (1) The residual chlorine of 0.35mg/L could control the HPC concentration of bulk fluid below 500CFU/mL. On the other hand, when HPC was above 3.5 log, the chlorine residual was 0 for adding chlorine systems. Likewise, the biofilm could keep growing with a low residual chlorine level. (2) For 4 different coupon materials (U-PVC, PVC, copper, stainless steel), the number and composition of biofilm was different. PVC had the most of microbe species while stainless steel had the least for the model distribution system following UV. UV disinfection could control the microbe species of biofilm in the model distribution system, (3) Even though the chlorine residual concentration is 0.8mg/L, there were still hundreds of HPC in the biofilm and fluid of model distribution system. These species of microorganism might be very chlorine resistive. The inactivation rate for one species of bacterium which was separated form the model distribution system was under 10% even the chlorine CT value above 700mgmin/L. However, UV had good controlling effect for it.


68

Tuesday 15:55-16:20 – Water Disinfection Reuse – A6-1 St. John’s Room 2

Progress and Experiences of Ultraviolet Application to Water Related Treatment Processes in Singapore

RJ Xie1, JY Hu2, M. Koh3, E Quek1, SN Xiu2, YJ Xing1,

MJ Gomez1, Y Fu1, AN Puah1 and H Seah1

1. Technology and Water Quality Office, Public Utilities Board of Singapore 2. Dept of Environmental Engineering, National University of Singapore 3. Water Distribution and Network Department, Public Utilities Board of Singapore

For drinking water disinfection, water reclamation for reuse, and removal of trace organic contaminants, ultraviolet

(UV) irradiation (in combination with an oxidant) is becoming one of the preferred processes for improved water

quality. Singapore’s experience of UV applications to water related processes include (1) disinfection of secondary

effluent for safe use at water reclamation plant, (2) treatment of RO permeate as final barrier for pathogen removal

in NEWater production process (i.e., water of potable standard primarily for industrial use), (3) primary

disinfection in drinking water production for pathogen removal and improved water quality, and (4) advanced

oxidation for mineralization of trace organic compounds. Pilot studies were conducted prior to full-scale

applications to different treatment processes. For all pilot studies, MS2 coli-phage was used as an indicator

organism to evaluate the effectiveness of UV disinfection. While direct UV irradiation (i.e., for secondary effluent

disinfection, NEWater production and drinking water primary disinfection) are in full-scale stage, advanced

oxidation is currently at pilot-scale testing stage.

In NEWater production, UV unit operation (both low pressure high output – LPHO and medium pressure UV

lamps) which followed the RO treatment train and functions as a reliable last barrier to waterborne organisms.

Tests using spiked MS2 coli-phage showed that a 6-log killing rate was achieved without much difficulty. For

drinking water production, UV was first evaluated as a primary disinfectant in a pilot test programme that involved

four types of UV reactors (two with low pressure high output, or LPHO, and two with medium pressure, or MP,

UV lamps) and two types of feed water (filtrate from a fast sand filter and product from an ultrafiltration at

waterworks). In evaluating different UV reactors for drinking water disinfection, electric power consumption was

recorded and split into two portions, i.e., power for energizing the UV reactor and its local control panel and power

for pump and control equipment as well as accessories (Figure 1). For LPHO system, the energy for powering UV

reactor accounted for 26-27% of total power consumption while the value for MP system is 12-19% apparently

because LPHO systems consumes much less energy than MP systems. Preliminary assessment showed that to treat

the same amount of water to a comparable level of pathogen removal, MP UV systems uses about at least

50% more energy than the LPHO ones. Depending on the types of UV reactors, the results showed 2-6 log removal

of MS2 coli-phage corresponding to calculated UV doses of 40-275 mJ/cm2 (Figure 2).


69


Approach for Achieving Sustainable Operation of the 2 BGD Catskill/Delaware UV Disinfection Facility

Matthew T. Valade, P.E.1, Steven Farabaugh1, Paul D. Smith, P.E. 2 and Gary Kroll, P.E.3

1. Hazen and Sawyer, P.C. 2. New York City Department of Environmental Protection 3. CDM

Recent advances in testing methods are being applied to the validation of NYC’s Catskill/Delaware UV equipment. These advanced methods will allow the full scale facility to operate in a more sustainable manner with up to 60% reduction in operating power requirements (and corresponding reduction in CO2 emissions) and savings over $1 million annually.

The design of the Catskill/Delaware UV disinfection facility has been on-going since 2001 and has been conducted concurrent with the development of the LT2ESWTR. The intent of the LT2 Rule is to ensure protection of public health, particularly regarding infection by Cryptosporidium. NYCDEP has specifically undertaken the design and construction of the Cat/Del UV facility in order to meet the requirements of LT2. Because the design and LT2 rule development were performed concurrently, relatively conservative design criteria were required in order to ensure the UV disinfection facility would meet the requirements of the anticipated rule. Specifically, these design criteria are the dose and capacity of the UV reactor, both of which directly affect the size of the UV units and therefore the footprint of the UV disinfection facility.

Until recently, the industry standard in the United States for establishing disinfection effectiveness through validation testing of a UV reactor was through using a surrogate microbe of MS-2. Other countries have used various other surrogates, although it was felt that MS-2 was the easiest and best surrogate to use to conservatively estimate disinfection effectiveness for larger capacity UV units. Only recently (i.e. post-2005) have other, more efficient surrogates (i.e. reduce the RED bias) been identified and used for validating UV equipment in the US. Prior to the final draft of the Guidance Manual being published, requirements for an RED close to 40 mJ/cm2 were expected to be required to achieve 3-log inactivation of Cryptosporidium. Therefore, 40 mJ/cm2 was used as the design basis for the Catskill/Delaware UV facility design. However, final revisions of the Guidance Manual were made in 2006 changing how the RED bias was determined and allowing for validation with surrogates, such as Q-beta, that could significantly reduce the RED bias of a UV unit. More recently, advances in the application of non-biological surrogates such as dyed microspheres (DMS) which provided a greater understanding of the treatment characteristics of a reactor have been made.

NYCDEP is currently conducting additional validation testing with DMS and other surrogates that will allow for increased certainty of the applied dose, while reducing the power required to achieve proper disinfection by over 2,400 kW-hrs per day – enough energy to power over 1,000 homes. This paper will present the approach NYC is taking to ensure a sustainable operation of the Cat/Del facility and results of the validation testing. Recommendations will be made to help other utilities considering UV treatment design and operate in the most efficient way possible.


70


Practical Considerations of Applying UV Technology for Reuse Water Disinfection

Wayne Lem and Jennifer Muller

Trojan Technologies Inc., 3020 Gore Road, London, Ontario, Canada N5V 4T7

Water scarcity has become a growing issue globally. Many citities in the world are experiencing water stress, i.e., deterioration in water quality and growing shortage in water quantity. Reuse of treated municipal wastewater offers an attractive solution to the water stress problem. The treated wastewater can be reused for the purpose of irrigation, landscaping, toilet flushing, car washing, industrial use, etc. Since people are in direct or indirect contact with reuse wastewater, its proper disinfection is critical for protecting public health. Chlorine is used for disinfecting wastewater for reuse purposes, but there are two issues associated with chlorine disinfection. First, it has been well established in the literature that chlorine disinfection forms disinfection byproducts, such as THMs, HAAs and NDMA. These byproducts can cause both acute and long-term health effects. Second, chlorine is ineffective in disinfecting Cryptosporidium. In many parts of the world, Cryptosporidium is commonly found in municipal wastewater even after conventional treatment [1]. A Cryptosporidium outbreak in Milwaukee, USA, in 1993 affected 403,000 people.

Ultraviolet (UV) disinfection is effective in controling a broad spectrum of pathogens including chlorine-resistant Cryptosporidium. It is also environmentally friendly in that no harmful byproducts are formed. UV disinfection of wastewater for reuse purposes has been successfully applied for decades in large scale treatment plants in North America and recently on a global scale. This paper will provide an overview of UV technology for reuse applications, related regulations, experiences, and the associated costs and benefits. Practical considerations for successfully implementing UV technology for reuse applications will be presented along with a case study/design example for a recent UV installation in California, USA.

Reuse water is wastewater that has been treated to high standards and can be used again for applications such as irrigation, landscaping, toilet flushing, car washing, and industrial use. Given the potential for public exposure with this water the disinfection and water quality standards for reuse water can be similar to drinking water standards. Hence, there are stringent equipment and sizing requirements.

This paper will briefly review the history and the basis for setting wastewater reuse regulatory disinfection targets. The paper will discuss the regulatory requirements of upstream treatment processes, water quality parameters, dose targets, and UV equipment related to specific requirements such as equipment redundency, scale-up and sizing, 3rd party bioassay validation as well as the validation of lamp aging and fouling. Practical considerations for successful implementation of UV will be disscussed to address the following questions:

Does UV work for meeting reuse disinfection standards? Is UV cost effective? What is the dose target for reuse? How do upstream processes and water quality affect UV reactor performance? What are reactor design and selection considerations? How do you prove that the UV reactor works? Why is third-party validation needed?

Data and case studies will be presented to address these questions. In summary, with proper design and implementation, UV technology is a cost effective solution for the application of disinfecting reuse wastewater.

References [4] J.L. Clancy, K.G. Linden, R.M. McCuin, “Cryptosporidium occurrence in wastewaters and control using UV disinfection”, IUVA News, Vol. 6, No. 3, September 2004.


71


UV Disinfection for Reuse of Drain Water in Horticulture

Nico Enthoven

Priva B.V.

Worldwide there is a growing scarcity of suitable water for horticulture. Also cost of fertilizers is increasing and drain water with fertilizers may cause environmental problems. These are three strong arguments for the reuse of drain water in horticulture.

Reuse of drain water enlarges the risk that the number of plant pathogens increases dramatically. A requirement for recirculation is thus a proper disinfection of drain water for all plant pathogens which may distribute through the water.

UV-C light is a well known and very suitable way of disinfecting water, but with horticultural water specific aspects have to be taken into account:

the UV transmittance is in most cases much lower (T10 10-50%) than in clean water the drain water may contain a lot of particles which have to be removed before disinfection different cultures may be affected by different pathogens, like bacteria, nematodes, fungi and viruses each pathogen type has its own disinfection dose for a certain disinfection level

Priva has over the years cooperated with partners and official institutes like PPO (now part of Wageningen University) to establish proper disinfection conditions for a log 3 reduction of recirculation water with UV disinfectors. Minimum doses UV-C light (from either low pressure lamps or medium pressure lamps) have been established for several important plant pathogens (like nematodes, specific fungi and specific viruses). PPO-WUR has created a list of relevant pathogens for different cultures, so that for each specific culture disinfection doses can be set high enough for proper disinfection but not higher than required for inactivation of all possibly dangerous pathogens.

The equipment developed has been designed such that a minimum intensity of 5mW/cm2 is guaranteed throughout the UV chamber. Intensity of UV-C light and flow (and thus residence time) can be varied automatically to optimise capacity and energy requirements depending on the water quality and the required dose of UV light. As horticultural water contains fertilizers which may accumulate on the quartz tube, automatic cleaning by a wiper, assisted by a small amount of acid is possible without interrupting the disinfection process.

UV intensity should be controlled continuously as is flow, to ensure proper disinfection at optimal conditions for capacity and energy.

Investigations with UV oxidation have shown that slightly lower doses UV are possible by adding hydrogen peroxide (H2O2) before the disinfection. We are now searching for other possible advantageous effects of the combination of UV and H2O2, like reducing the levels of residual pesticides.

UV disinfection of horticultural water thus enables safe reuse of drain water and in this way can contribute to substantial savings of water and fertilizers and decrease the pollution of the environment.


72

Tuesday 15:55-16:20 – Biofouling and Regrowth – B6-1 St. John’s Room 1

Biofouling Control in Water by UV and AOP Pretreatment

Hadas Mamane1, Anat Lakretz1, Eliora Z. Ron2 and Tali Harif

1. School of Mechanical Engineering, Tel Aviv University, Tel-Aviv, 69978, Israel 2. Life Sciences, Tel Aviv University, Tel-Aviv, 69978, Israel

Biofouling is the generally accepted term for the unwanted deposition of microorganisms on various surfaces (Flemming, 2002), affecting membrane filtration technologies and water treatment and supply facilities. Common oxidative disinfectants are most frequently applied to disinfect drinking water and used as a residual disinfectant to prevent biofilm formation in distribution systems. However, the risk of elevated levels of harmful disinfection by-products, formation of easily biodegradable organic substances and damage to polyamide desalination membranes in membrane filtration systems has given rise to consider alternatives for biofilm control. Ultra-violet (UV) light irradiation is being increasingly applied as a primary disinfection process for water without forming residual disinfection byproducts produced with chlorine disinfection. UV disinfection is indeed effectively used for inactivation of planktonic cells; however, this information may not be relevant when evaluating UV as a strategy to control biofouling. Very few published studies have considered application of UV based technologies as a potential pre-treatment technology for biofouling control (Rand et al., 2007). The main objective of the proposed research is to evaluate a new pretreatment technique for biofouling control using (a) polychromatic UV light and (b) the combination of polychromatic UV and hydrogen peroxide (UV/H2O2) advanced oxidation process (AOP) used to form the highly reactive hydroxyl radicals. The ability of a biofilm model organism Pseudomonas aeruginosa to form biofilms was assessed by the ability of cells to adhere to well made of polystyrene by the microtitier plate assay. The plates were stained with Gentian Violet (GV) solution that was further extracted from adhering cells and absorbance was determined with a plate reader at 600 nm. Biofilm formation percentage for each treatment (UV source, H2O2 alone, or the combined UV/H2O2 process) was calculated relatively to the mean average of the original sample that was not treated, and which constituted the 100%.

Results showed that biofilm formation strongly relies upon initial bacterial concentration, and thus is UV fluence-dependent. More over, the addition of H2O2 to the UV treatment only slightly impacted inactivation of planktonic model microorganism compared to UV alone. However addition of H2O2 to the UV treatment (even at low H2O2 concentration) resulted in a greater ability in reducing the biofilm potential compared to UV alone at the similar fluences, therefore a residual effect may be necessary for biofouling control.

Depending on the outcome of this study, validation and verification of these processes may lead to step-change advances in water treatment by means of a UV and AOP pilot scale operating system for the goal of biofouling control.

Bibliography

Flemming, H. C. (2002) Biofouling in water systems – cases, causes and countermeasures. Appl. Microbiol. Biotechnol., 59, 629–640

Rand, J.L., Hofmann, R., Alam, M.Z.B., Chauret, C., Cantwell, R., Andrews, R. C. and Gaynon, G. A. (2007) A field study evaluation for mitigating biofouling with chlorine dioxide or chlorine integrated with UV disinfection. Water Res. 41(9), 1939-1948.


73


Combined Aging and Fouling Index Provides Efficient UV System Operation and Maintenance

Mark Heath and Harold Wright

Carollo Engineers

Drinking water UV disinfection systems are currently installed in more than 300 utilities across Canada and the United States. With drinking water applications, UV system maintenance involves lamp replacement and quartz sleeve cleaning. Because utility operators do not have tools for quantifying the degree of lamp aging and fouling over time, they often replace lamps and clean quartz sleeves in accordance with UV vendors recommendations. While UV sensor readings respond to lamp aging and fouling, they are also impacted by changing water UVT and ballast power settings. Hence, a key challenge quantifying lamp aging and fouling is decoupling the impacts of changing UV transmittance (UVT), ballast power settings, lamp aging, and fouling on UV sensor readings. The presentation will discuss the methods used to achieve this objective using a calculated combined aging and fouling (CAF) index, defined as the ratio of the UV sensor readings divided by a reference UV sensor reading, S0. The reference UV sensor reading, S0, is defined as the reading expected with new lamps and a clean UV reactor. The value of S0 varies with UVT and ballast power setting with a relation that is either obtained from the validation report or from on-site testing. This paper will show how UV sensor readings alone provide deceptive information on lamp aging and fouling. It will provide theory that explains why the CAF index solves this issue and examples of how to characterize the S0 relation using validation reports and field studies. Last, the presentation will show examples of CAF index values calculated for several utilities across North America and discuss how these utilities will use the CAF index data to change their UV system maintenance schedules.


74


Effect of Low Pressure UV on the Regrowth Potential of Drinking Water

Peter van der Maas1, Jantinus Bruins1 and Dirk van der Woerdt2

1. Waterlaboratorium Noord, PO Box 26, 9470 AA Zuidlaren, The Netherlands 2. Waterbedrijf Groningen, PO Box 24, 9700 AA Groningen, The Netherlands

Low pressure UV (LP-UV) is widely used for drinking water disinfection. Contrary to medium pressure, low pressure UV is reported (IJpelaar et al., 2001) to produce insignificant amounts of Assimilatory Organic Carbon (AOC). Based on that it may be assumed that LP-UV does not affect the regrowth potential. Therefore, it is expected that LP-UV can be applied in drinking water treatment without the need for post treatment (IJpelaar et al., 2007), e.g. by biological activated carbon or slow sand filtration. This paper shows (to the best of our knowledge for the first time) that low pressure UV increases both the AOC formation and the regrowth potential significantly at a relatively low dose of 40 mJ.cm-2.

Low pressure UV disinfection (Trojan UVLogic 18 AL50, capacity 625 m3/h) is applied at drinking water facility De Punt (Groningen, The Netherlands) as the final treatment step, i.e. just before the clean water reservoirs. The UV dose amounts 40 mJ.cm-2

. Monitoring the Biofilm Formation Rate (BFR) of the influent and effluent of the UV reactors, shows that LP-UV increases the BFR from circa 1.4 to circa 12 pg. ATP.cm-2.d-1 (Fig. 1), probably under influence of the AOC concentration (Van der Kooij et al., 2003), which elevated from 12 (before UV disinfection) to 19 g Ac-C/l as an average (Fig. 2). These results imply that low pressure UV substantially elevates the regrowth potential during drinking water treatment under the local conditions. This is unwanted since regrowth might lead to higher concentrations of pathogens, e.g. Aeromonas and Legionella, in the distribution networks.

At present, additional research is carried out to determine the factors that cause the elevated AOC formation and the increased BFR, e.g. water and/or lamp characteristics. Results will be presented in the full paper.

References

IJpelaar, G.F. and Beerendonk, E.F. (2001). Vorming van nevenproducten bij UV-desinfectie - vergelijking van diverse UV-stralers op laboratoriumschaal, Kiwa report BTO 2001.193 (C) (in Dutch).

IJpelaar, G.F., Harmsen, D.H.J. and Heringa, M. (2007). UV disinfection and UV/H2O2 oxidation: by-product formation and control. Techneau, D2.4.1.1. http://www.techneau.org/fileadmin/files/Publications/Publications/Deliverables/D2.4.1.1.pdf

Van der Kooij, D., Vrouwenvelder, J.S. and Veenendaal, H.R. (2003). Elucidation and control of biofilm formation processes in water treatment and distribution using the unified biofilm approach. Wat. Sci. Technol., 47(5), 83-90.

http://www.techneau.org/fileadmin/files/Publications/Publications/Deliverables/D2.4.1.1.pdf


75


Disinfection of Biofilm in Tube Lumens with UVC Light Emitting Diodes (LED)

Jimmy Bak1, MD Søren D. Ladefoged2, MD Michael Tvede3,

Tanja Begovic1and Annette Gregersen2

1. DTU Fotonik 2. Nephrological Clinic 3. Department of Clinical Microbiology

Infections caused by biofilm in indwelling catheters, especially in long term central venous catheters (CVC), are recognized to be responsible for high morbidity and mortality among patients and costly for the healthcare system. We had shown earlier that the viable bacteria present in mature biofilm formed on the inner surface of urinary catheters could be reduced by ultra violet light exposure in the wavelength range between 250-280 nm (UVC). Very high doses (~15 kJ m-2) delivered by a mercury lamp were necessary for disinfection (99.9 %) of the most heavily contaminated urinary catheter examined ex-vivo. Our observations suggested that if UV light were to be used as a future method for preventing biofilm formation in indwelling catheters the light treatment should be administered frequently starting at the time of catheter placement where the biofilm is thin and transparent.

The major reason for the high doses for necessary for disinfecting the urinary catheters was that the mature biofilm besides cells contained absorbing and scattering particulates, which made the biofilm opaque. We demonstrate the potential of UVC light emitting diodes (LED) for disinfection purposes in catheter like tubes contaminated with new biofilm. It is shown that UVC Light propagation is possible through both teflon and catheter tubes (silicone). The disinfection efficiency of the diodes is demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. Biofilms are grown in tubes in length of 10 (teflon, silicone) and 20 cm (teflon) during three days using a flow system. Tubes for control and for UVC treatment were contaminated in parallel. Biofilm were sampled from the total inner surface of the tubes. Colony counts on the control samples were between 5105 – 1.3109 CFU/ml. The disinfection rates obtained were in the range 96 – 100 %. The applied UVC doses corresponded to treatment times between 15 – 300 min. Disinfection was obtained in 10 cm teflon tubes exposed in 30 min (detection limit < 5 CFU/ml). The same result was obtained for a 20 cm teflon tube exposed in 300 min. The disinfection rate was 96 % for the 20 cm tube if the dose was reduced to 30 min. A logCFU reduction of 4 was observed for a 10 cm peritoneal dialysis catheter tube (silicone) with 300 min exposure. Differences between the tubes are dependent on the differences in length and type of material. The UVC light is transmitted six times more efficiently in teflon than in silicone tubes of equal length (10 cm). The germicidal effect to obtain a 99.99 % killing rate for the biofilm (~78 J m-2) is comparable to that for the planktonic bacteria. We conclude that there is a potential for LED UVC light sources for disinfection if they are used on thin biofilms.


76


Inhibition of Algae Growth in a Sight Pond with Ultraviolet Irradiation

Jian Chen1, Meiting Guo2 and Hongying Hu

1. Fujian Newland EnTech Co., Ltd 2. ESPC State Key Joint Laboratory, Department of Environmental Science & Engineering, Tsinghua University, Beijing, China

The uncontrolled growth of algae caused by eutrophication of water bodies is becoming a serious problem in many countries today. Development of high effective、safe and economical algae control technologies is very important for guaranteeing the safety and landscaping of water environment without complex wastewater treatment facilities. With the development of ultraviolet (UV) technology, UV systems are applied more and more for microorganism control effectively and economically. It's well-known that UV light also can penetrate membrane of algae, causing damage to DNA and inhibiting the replication. The aim of this study was trying to investigate the effect of inhibiting algae by ultraviolet irradiation.

A city sight pond with the water surface area of 1,500 m2 in a recreation place, where is located in southern China, was taken as the test target. Some of discharge inlets introduce municipal wastewater into this pond, resulting in very heavy and odour water blooms of algae due to high concentrations of nitrogen and phosphorus. A set of UV irradiation system with 8 kw power consumption, was equipped beside the pond. Water was pumped from one side of the pond, went through the UV system, then was discharged back to the other side (Fig. 1).

After irradiation treatment for 40 hours, the growth of algae was obviously inhibited. The total algae number was lowered down to 3.3×107 cells/L from 7.8×108 cells/L, with a removal ratio of 96%. Cyanophyta and chlorophyta were the predominant algae phylums and they were more sensitive to ultraviolet light, with removal ratios of 97% and 88%, respectively. The chlorophyll was deduced with a reduction ratio of 99%, from 0.648 mg/L to 0.006 mg/L(Fig. 2). The UV water transmittance (UVT) increased from 15% to more than 70%. Improvement of UVT not only indicated the effect of growth inhibition of algae, but also improved and strengthened UV irradiation. Total phosphorus decreased from 1.86 mg/L to 0.63 mg/L(Fig. 3), while no significant change of total nitrogen was detected. It was hypothesized that phosphorus was removed with injured algae. The dissolved oxygen increased from 0.4 mg/L to 8 mg/L, indicating better environment for life in water (Fig. 4).

The results indicated here that, inhibiting algae growth with UV light is effective. It is possible to promote this technology for algae control in water bodies. But the treatment capacity design and operation conditions are still needed to be investigated.


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Response of Marine and Fresh Water Algae to UV

Liu Wenjun, Sun Wenjun and Liu Che

Tshingua University

The introduction of invasive marine species into non-native environments via ballast water discharge by marine vessels poses a serious biopollution threat. Shipping transfers approximately three to five billion tons of ballast water internationally each year. Therefore, it is a challenge to find an environmentally friendly ballast water treatment technique that can effectively reduce the potential for this biopollution threat while adhering to the safety, time, cost, and space constraints of the shipping industry. UV technologies have become attractive options for water disinfection processes in order to address increasing concerns regarding the inactivation of Cryptosporidium parvum and Giardia lamblia. Likewise, UV disinfection effectively deactivates and destroys both bacteria and viruses. Moreover, it does not form any disinfection by-products under regular disinfection doses. Therefore, UV disinfection is a feasible technique for ballast water treatment. However, generally, algae are UV resistant and the ballast water pre-treatment process could not remove all the micro algae sometimes, so it is meaningful to know the response of regular algae in ballast water to UV. In this study, it chose 16 kinds of algae which are abundant in Chinese ports, including 8 kinds of marine algae and 8 kinds of fresh water algae. After incubated in the lab, it used low-pressure collimated beam for UV irradiation. The UV doses were chose as 0, 100, 200, 300 and 400mJ/cm2.The algae after UV irradiation were cultured in dark incubator to simulate the ballast tank environment. The algae concentration was counted using microscope after 5 days. The results showed that: For marine algae, the plain sequence of UV resistance is Pyrrophyta> Chlorophyta> Bacillariophyta> stain flagellate. When UV dose is 300mJ/cm2, the inactivation rate of Heterosigma akashiwo(Hada)Hada is 100%, the inactivation rate of Skeletonema costatum and Dunaliella saline (Dunal) Teodoresco are higher than 80%, the inactivation rate of Nitaschia closterium minutissima Allen et Nelson is higher than 50%, the inactivation rate of Phaeodactylum tricornutum Bohlin is higher than 30%. UV can enhance the growth of Nitaschia closterium minutissima Allen et Nelson, Platymonas helgolandica Kylin and Pyramidomonas in some UV doses. For fresh water algae, the plain sequence of UV resistance is Cryptophyta> Chlorophyta> Bacillariophyta> Cyanophyta. When UV dose is 300mJ/cm2, the inactivation rate of Chlamydomonas microsphaera, Cyclotella meneghiniana and Microcystis aeruginosa is higher than 50%, the inactivation rate of Nitzschia palea. is higher than 30%. UV can enhance the growth of Chlamydomonas microsphaera and Fragilaria capucina in some UV doses. In sum, UV inactivation for algae is not so effective as most micro-organism. For some kinds of algae, UV can not work at all even in a high disinfection dose. Also, UV can enhance the growth of some kinds of algae in some UV doses. So if use UV as the ballast water disinfection process, the pre-treated process should load most algae removal assignment.


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UV Treatment Against Indigenous Microcystis Species and its Potential to Cause Microcystin Release and Change of Aquatic Biota

Hiroshi SAKAI, Kumiko OGUMA, Hiroyuki KATAYAMA and Shinichiro OHGAKI1

Dept. of Urban Engineering, The University of Tokyo

Several strains of cyanobacteria are known to cause water bloom problems in lakes and reservoirs. Some strains of cyanobacteria produce undesirable odorous compounds such as 2-methylisoborneol (2-MIB) and geosmin, while another strain is known to produce toxic compounds such as microcystin. In addition, landscape of the lake is impaired by the water bloom. In this study, UV treatment was applied because of the absence of significant residual effects. A medium-pressure UV treatment system was applied to lake water suffering from algal bloom to assess the growth inhibition of indigenous Microcystis species. UV exposure was already proved to be effective against pure culture and indigenous algae in a laboratory scale. Accordingly, this study focused on the practical aspects, (i) growth inhibitory effects against target indigenous algae, (ii) potential to cause microcystin release and change of aquatic biota during treatment.

A 500 L of lake water was treated by Medium-pressure UV reactor (BM2100W, Ebara, 2100W), which was placed at a lakeside of the Yamashita-Ike lake in the Kyushu island, Japan. Three UV exposure conditions was set including no exposure, short-time exposure (500L/90sec), and long-time exposure (500L/300sec). UV fluence was 40.6 mJ/cm2 or 135 mJ/cm2 for short or long time exposure, respectively, determined using F-specific RNA coliphage Qβ as a biodosimeter. Each sample was incubated for 14 days in a 500L tank in the field after UV exposure under the eaves. During incubation, concentration of nutrients, microcystin, and the number of phytoplankton and zooplankton were investigated. Bacterial community change was also monitored using Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique at molecular DNA basis.

There was a difference in Microcystis cell number between UV-irradiated samples and non irradiated samples. Non-irradiated sample reached maximum cell number during incubation, only within 1-3 days. Contrary, it took 6 days and 10-14 days for the cells with short time and long time exposure, respectively. This delay of irradiated cells could be attributed to growth inhibitory effect. Difference in the cell number between irradiated and non-irradiated cells at day 3 was 0.27 log and 1.12 log for short time and long time UV exposure, respectively. UV effects were also surveyed for microcystin release and change of aquatic biota. Microcystin concentration in the bulk water was temporarily increased only after the long time UV exposure, possibly due to the release of microcystin from dead cells of Microcystis. Change of aquatic biota was monitored by the number of phytoplankton (blue-green algae, green algae, and diatom) and zooplankton. The number of phytoplankton and zooplankton were changed during incubation with different trends of cell number profiles for different planktonic species. A bacterial community change was analyzed from the image of PCR-DGGE result. The degree of change was increased as UV fluence was increased.

The results of this study indicated that medium pressure UV system was effective against indigenous Microcystis species, at a UV fluence of 135 mJ/cm2. It was also shown that a certain care needs to be taken for concentration of microcystin and aquatic biota change during UV treatment.


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UV as an Ecological Invasion Barrier: UV Inactivation of Myxobolus cerebralis, VHSV, and Marine Phytoplankton

Brian Petri1 , Linda Sealey1, Ron Hedrick2, John Lumsden3 and Charlie Trick4

1. Trojan Technologies 2. University of California, Davis 3. University of Guelph 4. University of Western Ontario

UV has been successfully applied to the inactivation of viruses, bacteria and protozoans in municipal drinking water, wastewater and reuse applications, and much is known about its effectiveness for inactivating pathogens in these classes. UV is now being used in other applications with similar and new classes of pathogens.

We have been investigating the effectiveness for UV to inactivate a variety of new pathogens that could be classed together as ecological invaders. They cause harm to natural aquatic populations, or to the ecology of aquatic ecosystems, and are often spread anthropogenically. This paper will show examples of our studies, also highlighting the need for understanding the proper metrics of inactivation of new pathogens, as demonstrated in the evolution of knowledge of UV inactivation of Cryptosporidium.

Whirling disease of salmonid fish is caused by Myxobolus cerebralis, a myxozoan parasite with a two host life cycle. Through infectivity studies of the different spore forms with their respective hosts, we demonstrated the effectiveness for UV to inactivate them and prevent the spread of whirling disease to and from hatcheries. This work superseded earlier work that had much higher UV dose requirements because vital stain methods overestimated the UV requirements. VHSV is a virus that infects a broad range of fish species, and was recently introduced to the Great Lakes where it caused numerous fish kills of many species. We demonstrated the UV dose-response characteristics of VHSV. We also examined the UV dose-response characteristics of a number of marine phytoplankton, possible candidates for spreading by ballast water. We compared a number of methods to demonstrate the effects of UV. Together these studies show the wide applicability of UV, to inactivate many pathogens in many applications, but reinforce the need for using the correct metrics.


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Poster Session 1 – Monday 15:20 – 15:55 Grand Ballroom

Evaluation and Comparison of UV Lamps

Norbert Bodenhausen, Christoph Dicks and Fritz Stadler

AQUAFIDES GmbH

A UV lamp is the heart of a UV system like an engine within a car.

The development of a new type of UV lamp, the change of lamp suppliers, quality control in production or procurement are just some reasons to evaluate or compare UV lamps.

Due to the importance of the performance of the UV lamps for the overall performance of a UV system this subject is still and will always be an important subject for the UV industry.

AQUAFIDES group integrates the production of UV lamps and production of UV systems.

UV lamps for AQUAFIDES UV systems and for UV systems of various other suppliers are produced. This integrated strategy offers the opportunity to focus the UV lamp team and the UV system team on one common goal – the overall performance of UV systems. One important element regarding this goal is the honest and transparent communication of the performance and the limits of the performance of UV lamps based on the various, real conditions UV systems operate under. This communication must be based on reliable data.

Therefore AQUAFIDES operates a UV lamp test facility since almost two years, which is able to evaluate and compare low pressure UV lamps in water with the ballast and quartz tube, which fits to these lamps. The test facility can operate at different temperatures between 0 °C and 70 °C. Different types of UV sensors like ÖVGW sensor, DVGW sensor or other sensors can be used. The lamp test facility is able to simulate UV systems of AQUAFIDES and other UV system suppliers. Regular calibrations of the various components of the test facility ensure exact data. It will be presented how to design a UV lamp test facility, how to set up the right test environment and how to run a test properly.

Highlights of the findings during the last two years will be presented based on the gathered data. It can be concluded that the knowledge about the real performance of UV lamps under real conditions UV systems operate under is still not sufficient for our industry and this results in the risk that UV as a reliable disinfection method may risk its reputation.


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Poster Session 2 – Monday 15:20 – 15:55 Grand Ballroom

How UV Disinfection Can Help to Address Declining Groundwater Supply

Matthias Boeker1 and Katie Cook 2

1. ITT Water & Wastewater U.S.A., 14125 South Bridge Circle, Charlotte, NC 28273 2. ITT Water & Wastewater U.S.A., 501 TechneCenter Drive, Milford, OH 45150

In 2001, due to increases in growth in new developing areas, the Clovis City Council approved the construction of a new water reuse facility for the city. The goal of this new facility was to create a tertiary treatment system, consisting of a multi-stage treatment and filtration process. Because the system will be capable of treating the wastewater to high quality “reuse” standards, the water will be able to be reused for irrigation and recreation purposes.

CH2M Hill was selected as the engineering consultant for this project. The facility is anticipated to be operational by November 2008, with final completion by December 2008. The overall project delivery is being carried out by CH2M Hill Constructors under a design build contract. The facility will be capable of treating ultimately 8.3 million gallons per day (MGD), consisting in phases of 2.8 MGD each.

In November 2006 – through a highly selective bidding process – ITT Water & Wastewater was awarded the contract to supply their WEDECO UV disinfection equipment. The bid, considering both capital and overall operation and maintenance costs, determined overall the most cost-effective UV system solution to be WEDECO LBX-series involving low pressure, high intensity technology.

In order to meet the high water quality reuse standards required for the City of Clovis, the UV system was required to meet National Water Research Institute’s (NWRI’s) “Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse.” These NWRI standards require the units to be validated to a range of UV transmittances and doses, thereby providing the required disinfection of a minimum of 5-log poliovirus inactivation and a 7-day geometric mean of less than 2.2 total coliforms per 100 mL. ITT Water & Wastewater’s WEDECO LBX-series units underwent full NWRI validation in Portland, Oregon. The results were used in the design of the UV system for the City of Clovis, making it the first closed vessel low pressure, high intensity installation in accordance with NWRI protocol in the world.

The UV system for the facility is designed initially to treat a peak flow of 6.4 MGD. It is composed of a total of eight (8) closed vessel units, arranged in four trains of two units each. With three trains duty and one standby, the required redundancy is met per NWRI protocol. The number of units in operation and the lamp output will both be capable of being automatically varied; ensuring proper disinfection will be met regardless of influent flow or water quality.

This presentation will continue to focus further on the design of the UV system for the City of Clovis. It will describe in more detail the required NWRI validation protocol, and will give specifics on the status of this “first of its kind” installation.


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Poster Session 3 – Tuesday 10:15 – 10:50 Grand Ballroom

The UV Industry “down under” in Oz, Warts and All!

Iain Johnson

Tenix Alliance Pty Ltd. This paper provides an overview of the humble beginnings of the UV industry in Australia, the players in the market place then and now, and the lessons learnt along the way.

It discusses the increase for inclusion of UV Water disinfection systems in secondary effluent treatment prior to discharge throughout the mid 1980’s to early 2000.

With the emergence in Australia for Potable Water disinfection using validated UV technology for Cryptosporidium and Giardia inactivation, the paper discusses innovative methods of UV disinfection in a number of Water Treatment Plants in South Australia and the largest Potable Water installation in Australia (300MLD).

As the Australian continent continues to experience severe drought (and local bush fires) the inclusion of water recycling plants (WRP) in the country’s water management strategy has become a necessity. This paper illustrates how and presents the drivers for why UV equipment is integrated into these plants. A number of systems are featured. These include WRP for direct potable water use (Advanced Oxidation Technology [AOT]) and third pipe (Class A recycled water line) inclusion into residences.

In conclusion the future trends for UV Disinfection are discussed in conjunction with other technologies to provide a sustainable and environmentally friendly future for the people of Australia. The Author – Iain Johnson, member IUVA

Iain has served in the Australian water industry for 38 years with the last 16 years majoring in Ultraviolet Water Disinfection Equipment. He was involved with the design, manufacture and installation of twenty UV installations throughout the east coast of Australia. A further twenty five systems were installed when his own former company represented Wedeco UV. Iain then joined United Group Infrastructure as a Senior Process Mechanical Engineer where he was involved with a number of UV systems including the largest Drinking Water UV installation in Australia. Today Iain is in a similar role with Tenix Alliance which is a leading partner to infrastructure asset owners in Australia and New Zealand.

References

Manufacturers: ITT Wedeco, Calgon UV (represented in Aust by Liquitek Pty Ltd), Trojan UV (represented in Aust by Aquatec Maxcon Pty Ltd), Berson UV (represented in Aust by CST WASTEWATER SOLUTIONS Pty Ltd), Australian Ultraviolet Services (AUVS), Orica (Formally Ultraviolet Technology of Australasia [UVTA])

Contractors: United Group Infrastructure, Tenix Alliance, Gibson Island Water Alliance (Western Corridor Recycle Water Project), Tarago ReConnect

End Users / Specifiers: Department of Commence (NSW), GHD, MWH, ActewAGL, Country Energy Makay Regional Council, Sydney Water, Central Highlands Water, Yarra Valley Water, Melbourne Water, United Utilities, Gold Coast Water


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Poster Session 4 – Tuesday 10:15 – 10:50 Grand Ballroom

Practical Aspects of De-Chloraminisation of Public

Swimming Pool Water by Means of Ultraviolet Irradiation

Rob van Esch

Siemens Water Technologies In the water treatment segment Ultraviolet light has an outstanding reputation as it comes to the disinfection of microorganism. The usage of UV for water disinfection is an excellent and reliable method in applications were no re-infection can occur. In case of a swimming pool we are dealing with open water and pool users which are unintentional infecting the water. Therefore a disinfection method has been specified for public swimming pools which has a residual disinfection capacity such as Chlorine. Pool users not only infect the water but also pollute the water with hairs, skin, saliva, urine, make-up, skin creams and much more, this in combination with the free Chlorine which is present in the water reacts to combined Chlorine, also known as Chloramines, or Trihalomethane THM.

Chloramines can be divided in three types:

Monochloramine NH2Cl Dichloramine NHCl2 Trichloramine NCl3

It is known that Trichloramine is volatile and causes not only the penetrating smell which is confused by pool users with the strong odour of chlorine but is also responsible for the irritation of eyes, skin and slime producing organs. Further the Trichloramine can be responsible for the corrosion of steel constructions of a pool hall.

Tests have been done in several European pools showing that Chloramines can be effectively oxidised by UV irradiation were the medium pressure UV lamps showed a higher effectiveness than low pressure UV lamps. The test results will be presented and explained. The absorption spectra of Mono-, Di- and Trichloramine will be discussed and used to explains the higher effectiveness of the medium pressure UV lamps.

The tested UV systems preformed very well which resulted in much better Chloramine levels in the pool water because of which the fresh water intake for each pool user was strongly reduced (legal minimum quantities were respected) which resulted in very short payback times of the investments.

Also measurements on THM (trihalomethane) levels in the pool water were part of the monitored parameter which will be presented in relation to the used UV source (low or medium pressure UV lamps).

Auteur:

Ing. Rob van Esch

Rob is a Project and Sales Manager for UV at Siemens Water Technologies. Rob started working in the UV disinfection industry in 1988 as R&D Manager UV, in the years after he was active as Engineering Manager UV and Sales Manager for f.i. large drinking water UV disinfection projects in the Netherlands. Rob received his technical education at the higher professional school in Eindhoven, The Netherlands, and graduated as electro technical engineer.


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