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Lagrangian actinometry (reactor testing involving dyed microspheres) has been introduced as anew 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 UVreactor system for a given set of operating conditions. Dyed microspheres have been successfully appliedfor UV dose distribution measurement in reactors ranging in size from bench-scale to the largest reactorsknown; microspheres have also been used to measure dose delivery in monochromatic systems as well aspolychromatic reactors.The goal of this study was to define the benefits of reactor validation and characterization usingdyed microspheres. While reactor testing by dyed microspheres has clear advantages over othermethods, it is evident that existing methods (such as biodosimetry and numerical simulation) can beused to complement microsphere measurements. Therefore, the benefits of the combined application ofthese three methods is also discussed, as well as suggestions for their combined use in future reactorvalidation efforts.METHOD DESCRIPTIONThe dyed microspheres used in validation and characterization of UV reactor systems include asurface-conjugated dye that undergoes a permanent photochemical change when subjected to UVradiation. This photochemical reaction transforms the non-fluorescent parent molecule into a brightlyfluorescent, stable photoproduct, thereby allowing particle-specific dose measurements to be collected.Introduction of a population of microspheres upstream of a UV system, with downstream samplecollection and subsequent analysis allows for dose distribution measurement.Lagrangian actinometry tests were conducted on full-scale UV reactors at the UV Validation andResearch Center (Johnstown, NY) and at the demonstration-scale facility of the Metropolitan WaterDistrict of Southern California (LaVerne, CA). Testing at the New York facility involved a WedecoK143HP low-pressure, high-output reactor; tests at the MWD facility involved a Calgon Sentinel mediumpressure reactor. Microspheres tests were conducted in parallel with biodosimetry experiments on bothreactor 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 experimentsallows for an examination of the repeatability of the microspheres assay and the resulting assessment ofreactor behavior. Includes 4 references, tables, figures.

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Edition: Vol. - No. Published: 06/01/2007 Number of Pages: 60File Size: 1 file , 1.9 MB