Updating the Approaches in the NWRI/AwwaRF UV Guidelines: The Impacts of Water Quality and Recirculation Mode Testing on UV Validation

The NWRI/AwwaRF “Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse” (the Guidelines) are widely followed, but some of the guidance relating to UV reactor validation is unnecessarily restrictive in light of new advances in testing methodology that have emerged since the Guidelines were written. This paper addresses two of these issues: appropriate water sources and flow modes for testing. We did comparative full scale UV reactor tests that showed that bioassay-based measurements of UV reactor performance were independent of water source (waste water versus potable water adjusted to the same UVT) and flow mode (flow-through versus recirculation mode).