AWWA WQTC71367

In this research, both Lagrangian actinometry (LA) and biodosimetry were employed to evaluate reactor performance and assess reactor credit for inactivation of recalcitrant microorganisms (i.e., nominal ultraviolet (UV) doses in the 200-400 mJ/cm² range). A 3-LPHO-lamp reactor was validated by LA and biodosimetry at the Gloversville - Johnstown Joint Wastewater Treatment Facility in New York. Three different sizes of dyed microspheres (DMS) (6, 10 and 15 mm) and spores of a native strain of Bacillus pumilus were employed in the test. These challenge particles were imposed on the reactor at four different flow rates from 25 to 200 GPM. At higher flow rates, the results of LA and biodosimetry agreed well with each other. At lower flow rates, the results were more variable. At the lowest flow rate, 25 GPM, a broad dose distribution from approximately 100 to 500 mJ/cm² was characterized. The results of these experiments also indicated that LA appears to be sufficiently sensitive and responsive to quantify unsteady behavior in reactor performance. When operated at the lowest flow rate, the behavior of the 3-lamp reactor became unsteady. Replicate microsphere samples illustrated the magnitude of this unsteadiness and its implications with respect to reactor performance. Includes 3 references, tables, figures.