AWWA WQTC71487 Wavelength-Dependent UV Dose Response of Three Different Types of Dyed Microspheres for Lagrangian Actinometry

Conference Proceeding by American Water Works Association, 11/01/2009

Chan, Po-Shun; Blatchley, Ernest R., III; Shen, Chengyue; Scheible, O. Karl; Holdman, Cheryl; Robinson, J. Paul

Full Description

Validation of ultraviolet (UV) reactors using Lagrangian Actinometry (LA) has been successfullyapplied to several large-scale UV reactors for drinking water disinfection. The primaryadvantage of LA is the ability of the method to yield a measurement of the UV-dosedistribution of the reactor. An accurate measurement of the UV dose distribution can be usedto provide an accurate prediction of reactor performance relative to any photochemicalendpoint for which accurate UV dose-response behavior is known.In order to separate dyed microspheres (DMS) from background particles, it isdesired to provide DMS with larger sizes and higher fluorescence intensity. Three types ofmicrospheres with different diameters (nominally 5, 10 and 15 m) and surface coatingmaterials were tested. The 10 and 15 m DMS were better separated from backgroundparticles in flow cytometry.In this research, action spectra of three different types of DMS were also established.The collimated MP source and bandpass optical filters used in these experiments allowedmeasurement of wavelength-dependent dose-response behavior for all three DMS types overthe entire germicidal UV spectrum for UV doses in the range of 0-450 mJ/cmsup2/sup. Internal(microsphere) standards were applied for all samples to calibrate the measurements in flowcytometry. The action spectra of three different types of DMS were similar and wavelengthsbetween 240 to 280 nm showed higher efficiency. A dose of 450 mJ/cmsup2/sup at the most sensitivewavelength gave mean FI increases of 50, 700 and 400 units for 5, 10 and 15 m DMS,respectively. The 10 m DMS provided the greatest sensitivity to UV radiation at allwavelengths. The higher sensitivity of DMS can improve not only the separation frombackground particles but also determination of dose distribution. Includes 6 references, table, figures.

Product Details

Edition: Vol. - No. Published: 11/01/2009 Number of Pages: 10 File Size: 1 file , 920 KB