Modeling of a new UV test cell for evaluation of lamp fluence rate effects in regard to water treatment, and comparison to collimated beam tests

Grapperhaus, Michael; Schaefer, R.; Linden, Karl G.

doi:10.1139/s06-064

Cited by 4 publications

(4 citation statements)

References 2 publications

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“…The UV fluence was determined using a Monte Carlo approach. This approach uses the geometric ray trace program OptiCAD, which includes the detailed geometry, the lamp emission spectrum, and all aspects of light propagation, absorption, and reflection, and which is detailed in Grapperhaus et al (4). Inactivation differences between the CB and HI setups are a measure of irradiance-induced inactivation.…”

Section: Methodsmentioning

confidence: 99%

Enhanced UV Inactivation of Adenoviruses under Polychromatic UV Lamps

Linden

Thurston

Schaefer

et al. 2007

Appl Environ Microbiol

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Adenovirus is recognized as the most UV-resistant waterborne pathogen of concern to public health microbiologists. The U.S. EPA has stipulated that a UV fluence (dose) of 186 mJ cm ؊2 is required for 4-log inactivation credit in water treatment. However, all adenovirus inactivation data to date published in the peer-reviewed literature have been based on UV disinfection experiments using UV irradiation at 253.7 nm produced from a conventional low-pressure UV source. The work reported here presents inactivation data for adenovirus based on polychromatic UV sources and details the significant enhancement in inactivation achieved using these polychromatic sources. When full-spectrum, medium-pressure UV lamps were used, 4-log inactivation of adenovirus type 40 is achieved at a UV fluence of less than 60 mJ cm ؊2 and a surface discharge pulsed UV source required a UV fluence of less than 40 mJ cm ؊2 . The action spectrum for adenovirus type 2 was also developed and partially explains the improved inactivation based on enhancements at wavelengths below 230 nm. Implications for water treatment, public health, and the future of UV regulations for virus disinfection are discussed.UV disinfection is a well-accepted technology for inactivation of bacterial and protozoan pathogens. Until recently, UV was also considered a viable technology for disinfection of viruses. At UV fluences (doses) typically used in water disinfection, UV is very effective (Ͼ4-log inactivation) against almost all known pathogenic viruses, with the one exception of adenoviruses (5). Adenovirus has been recently listed on the U.S. EPA Candidate Contaminant List, which indicates that it is a high priority for possible future regulation and is known or anticipated to occur in public water systems, but significant data gaps need to be addressed before regulation can be invoked. According to recently published U.S. EPA regulations (17), the inactivation of adenoviruses to a level of 4 log requires a UV fluence of 186 mJ cm Ϫ2 , based on an 80% credible interval, as presented in the Draft UV Disinfection Guidance Manual (16). The U.S. EPA-regulated UV fluence for inactivation of all viruses is now based on the conservative case of adenoviruses. Yates et al. (18) provide an excellent review of the issues surrounding the UV inactivation of adenovirus.Although data sets for UV inactivation of adenovirus differ moderately, they all place adenovirus as the most UV-resistant health-related virus known. However, all peer-reviewed published studies to date have been performed using a low-pressure (LP) mercury vapor UV lamp source characterized by a monochromatic output in the UV range at 253.7 nm. Based on these LP UV irradiation studies, the UV fluence necessary to achieve 4-log inactivation of adenovirus varies from 120 to approximately 180 mJ cm Ϫ2 . For adenovirus type 5 (Ad5), the required UV fluence is 160 to 170 mJ cm Ϫ2 (1), which is similar to those required for Ad1 (9), Ad2 (1, 5), Ad6 (9), and Ad40 and Ad41 (8). However, there are two studies that repo...

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Section: Methodsmentioning

confidence: 99%

Enhanced UV Inactivation of Adenoviruses under Polychromatic UV Lamps

Linden

Thurston

Schaefer

et al. 2007

Appl Environ Microbiol

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“…The reactor configuration will determine how the UV reaches microorganisms and consequently its efficacy (Gómez-López et al 2005a), which depends on the overall average germicidally weighted fluence, food matrix (Gómez-López et al 2005b), and hydrodynamics (Sauer and Moraru 2009;Artíguez et al 2011;Hsu and Moraru 2011). The difference between a collimated system (Orlowska et al 2013) and an industrial reactor such as a thin-film device (Chaine et al 2012) is notorious (Grapperhaus et al 2007). It must be stated that the industrial adaptation of laboratory results for CW UV light technology is a three-step process.…”

Section: Reactor Configurationmentioning

confidence: 99%

An Approach to Standardize Methods for Fluence Determination in Bench-Scale Pulsed Light Experiments

Gómez‐López

Bolton²

2016

Food Bioprocess Technol

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“…Li et al (2012), amongst others (Sommer et al, 1996), have highlighted the importance of accurate modelling of reflections by internal chamber walls, which should be taken into account by an effective optical fluence model. Grapperhaus et al (2007) used an alternative approach, using a commercial ray tracing program (OptiCAD™) to model fluence in a quasi-collimated beam apparatus, accounting for ray attenuation by the water plus absorption, scattering or reflection by chamber walls. The software modelled the total light absorption within the sample, but did not provide information on fluence uniformity, which is essential for the design of effective UV-LED chambers.…”

Section: Introductionmentioning

confidence: 99%