Lagrangian actinometry (reactor testing involving dyed microspheres) has been introduced as a
new method for quantitative characterization of the performance of ultraviolet (UV) reactor systems (Blatchley et al.,
2005, 2006 a,b,c). Dyed microspheres allow for measurement of the dose distribution delivered by a UV
reactor system for a given set of operating conditions. Dyed microspheres have been successfully applied
for UV dose distribution measurement in reactors ranging in size from bench-scale to the largest reactors
known; microspheres have also been used to measure dose delivery in monochromatic systems as well as
polychromatic reactors.
The goal of this study was to define the benefits of reactor validation and characterization using
dyed microspheres. While reactor testing by dyed microspheres has clear advantages over other
methods, it is evident that existing methods (such as biodosimetry and numerical simulation) can be
used to complement microsphere measurements. Therefore, the benefits of the combined application of
these three methods is also discussed, as well as suggestions for their combined use in future reactor
validation efforts.
METHOD DESCRIPTION
The dyed microspheres used in validation and characterization of UV reactor systems include a
surface-conjugated dye that undergoes a permanent photochemical change when subjected to UV
radiation. This photochemical reaction transforms the non-fluorescent parent molecule into a brightly
fluorescent, stable photoproduct, thereby allowing particle-specific dose measurements to be collected.
Introduction of a population of microspheres upstream of a UV system, with downstream sample
collection and subsequent analysis allows for dose distribution measurement.
Lagrangian actinometry tests were conducted on full-scale UV reactors at the UV Validation and
Research Center (Johnstown, NY) and at the demonstration-scale facility of the Metropolitan Water
District of Southern California (LaVerne, CA). Testing at the New York facility involved a Wedeco
K143HP low-pressure, high-output reactor; tests at the MWD facility involved a Calgon Sentinel medium
pressure reactor. Microspheres tests were conducted in parallel with biodosimetry experiments on both
reactor systems over a range of operating conditions. For each operating condition,
replicate samples of microspheres were collected for analysis. As such, the data for these experiments
allows for an examination of the repeatability of the microspheres assay and the resulting assessment of
reactor behavior. Includes 4 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.9 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 60 |
| Published : | 06/01/2007 |
