AWWA WQTC65788

AWWA WQTC65788 Who Needs RED? An Empirical Method for Validating the Log-Inactivation of a UV Reactor Thereby Eliminating the Need for RED and RED Bias
Conference Proceeding by American Water Works Association, 11/01/2007

Bircher, Keith G.; Wright, Harold

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Ultraviolet (UV) reactors are validated by determining the Reduction Equivalent Dose (RED)that they supply at a given operating condition. A new method is described whereby the log-inactivationof any organism affected by a UV reactor can be predicted as a function of the flowrate, the UV sensor value, the UV transmittance of the water, and the UV sensitivity of theorganism as determined by collimated beam tests. (The UV sensitivity is the dose required perlog inactivation.)The method can be used to compute directly the log inactivation of a target organism by a reactor, without consideration of RED or RED bias. Therefore for a target organism such asCryptosporidium, the reactor system controls would be programmed to calculate the log-inactivationdirectly based on the flow, UV transmittance and UV sensitivity of the targetorganism (Cryptosporidium) with uncertainty values subtracted. Includes reference, figures.