Full-Scale UV-LED Validation with Organism-Specific Dose Determination

UV-LED technology, utilizing light-emitting diodes (LED) to produce UVC light, has been demonstrated as a promising technology for drinking water applications. The absence of a validated UV-LED reactor or a validation protocol may limit its application. The first full-scale UV-LED₂₈₀ reactor in the Americas was installed at a municipal well for <i>Legionella pneumophila</i> disinfection. USEPA guidance was used to design validation bench- and full-scale tests with two surrogates (MS2 and T1UV). Full-scale parameters were varied over relevant ranges (893-1000 GPM, 90-99% UVT₂₈₀, 12-100% power levels, and varying LED₂₈₀ bank operation) to understand effects on performance. The Calculated Dose Approach successfully generated <i>L. pneumophila</i>-tailored UV intensity setpoints and a validated reduction equivalent dose (RED) monitoring equation. Validated <i>L</i>. <i>pneumophila</i> REDs of 3.7-47 mJ/cm² were found through the incorporation of an <i>L. pneumophila</i> UV sensitivity factor in the equation, not only reducing RED over/underestimation but also removing the need for UVDGM bias factors. The UV-LED₂₈₀ REDs exceeded the requirements under a variety of extreme conditions. Although this study successfully demonstrates a UV-LED₂₈₀ reactor and validation approach, guidance specifically addressing UV-LED would provide clarity and assurance to utilities seeking to implement and receive treatment credit with this promising new technology.