AWWA ACE54343

This research was initiated to develop new methods for proper estimation of effective germicidal dose for both monochromatic and polychromatic ultraviolet (UV) sources. Two accepted UV dose measurement methods, chemical actinometry (CA) and mathematical modeling were investigated along with biodosimetry. Uridine and potassium iodide actinometers were both employed in the UV dose quantification experiments. Mathematical analyses were then conducted by combining specific UV lamp emission spectra with the fraction of light absorbed by the CAs at each wavelength and obtaining a lamp correction factorto modify the CA measured dose. The result is the true incident dose in the 200-300 nm (germicidal) range. Water sample absorbance spectra were also incorporated into this calculation to reflect the impact of water absorbance on the dose and obtain an average dose of UV. The average dose was then weighted by the DNA absorbance spectra to yield the relative germicidal effective dose, which may adequately represent the germicidal disinfection efficiency of the UV lamp. Results show that combined with mathematical analyses, chemical actinometers provided a close match with the radiometer method for both incident and germicidal intensity estimations (within 95% confidence interval of each other). Dose values obtained using biodosimetry (i.e., Bacillus subtilis microbial challenges) were used as a benchmark for comparison. Compared with biodosimetry, results suggest that incorporated with math-analysis, CA dose prediction may be more accurate and will properly reflect the germicidal effective portion of polychromatic UV emission. This method has potential to develop into aflexible and convenient way to measure germicidal UV dose provided by any monochromatic or polychromatic UV lamp. Includes 10 references, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2001

Number of Pages:

8

File Size:

1 file , 300 KB