@article{
author = "Blatchley III, Ernest and Shen, Chengyue and Naunović, Zorana and Lin, Lian-Shin and Lyn, Dennis and Robinson, J. Paul and Ragheb, Katherine and Gregori, Gerald and Bergstrom, Donald and Fang, Shiyue and Guan, Yousheng and Jennings, Kristofer and Gunaratna, Nilupa",
year = "2006",
abstract = "Lagrangian actinometry represents a new method of photochemical reactor characterization. The method is based on an
application of dyed microspheres, which were developed by attachment of E-5- 2-methoxycarbonylethenyl cytidine hereafter referred
to as S to polystyrene microspheres. S is a nonfluorescent molecule that when subjected to ultraviolet UV irradiation yields a single
product, 3- -D-ribofuranosyl-2,7-dioxopyrido 2,3-d pyrimidine hereafter referred to as P, which displays a strong fluorescence signal.
Dyed microspheres were subjected to UV irradiation under a collimated beam and using a single-lamp, monochromatic low pressure Hg,
continuous-flow reactor. In parallel with these experiments, a biodosimetry experiment was conducted using Bacillus subtilis spores as the
challenge organism. Particle-specific fluorescence intensity measurements were conducted on samples from the collimated-beam experiments and the flow-through reactor experiments by flow cytometry. Estimates of the dose distribution delivered by the flow-through
reactor for each operating condition were developed by deconvolution of data resulting from flow cytometry analysis of these samples. In
conjunction with these experiments, a numerical model was developed to simulate the behavior of the reactor system. A commercially
available computational fluid dynamics package was used to simulate the flow field, while line-source integration was used to simulate the
irradiance field. A particle-tracking algorithm was employed to interrogate the flow and irradiance field simulations for purposes of
developing particle-specific Lagrangian estimates of dose delivery. Dose distribution estimates from the microspheres assays and the
numerical simulations were combined with the measured dose–response behavior of B. subtilis spores to yield estimates of spore
inactivation in the flow-through experiments. For the range of operating conditions used in these experiments, predictions of spore
inactivation based on dose distribution estimates from both methods were in good agreement with each other, and with the measured spore
inactivation behavior. Lagrangian actinometry is capable of yielding accurate, detailed measurements of dose delivery by continuous-flow
UV systems. This method represents a substantial improvement over existing experiment-based methods of UV reactor characterization
e.g., biodosimetry in that it yields a measurement of the dose distribution for a given operating condition. This method also represents
an improvement over existing methods for validation of numerical simulations. Specifically, because this method yields a measurement of
the dose distribution, it is possible to compare these measurements with predicted dose distributions from the numerical simulation. The
combined application of biodosimetry, numerical modeling, and Lagrangian actinometry represents an extremely robust approach to
reactor characterization and validation.",
journal = "Journal of Environmental Engineering. ASCE / American Society of Civil Engineers",
title = "Dyed microspheres for quantification of UV dose distributions: Photochemical reactor characterization by Lagrangian actinomety",
number = "11",
volume = "132",
doi = "10.1061/(ASCE)0733-9372(2006)132:11(1390)"
}
