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A theoretical approach is described in this paper for modeling dose delivery and measured UV intensity in an ideal and non-ideal annular reactor equipped with either a low-pressure or medium-pressure mercury arc lamp. Plots of Reduction Equivalent Dose versus measured intensity are used to demonstrate two approaches to monitoring UV dose delivery. One approach uses a UV intensity setpoint to guarantee dose delivery. The other uses a UV intensity and a UV transmittance setpoint together to guarantee dose delivery. The monitoring approach used by a UV reactor is shown to influence the protocol used to validate that reactor and the interpretation of validation results. UV intensity sensor placement and spectral response is shown to impact reactor performance efficiency, dose monitoring, and reactor validation. An optimal sensor location can be defined for each monitoring approach. The optimal position with the intensity setpoint method depends on the dose distribution of the reactor. The UV sensitivity of the challenge microbe influences the UV intensity setpoint used to guarantee a given UV dose. With polychromatic UV systems, the absorbance spectrum of the water and the spectral response of the UV intensity sensor influence the UV intensity setpoint. Differences in the spectrum of water absorbance are minimized if the sensor spectral response is restricted to the germicidal range. Includes 4 references, tables, figures.

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Edition: Vol. - No. Published: 01/01/2001 Number of Pages: 16File Size: 1 file , 260 KB