AWWA WQTC62552

A single sample concentration and recovery procedure that can be used for bacteria, protozoa, and viruses will greatly improve the ability of water utilities and other agencies to respond to contamination events. However, it is critical to minimize exposure of sample collectors to potential biological and chemical hazards in contaminated water. Therefore, the objective of this study was to develop a pathogen detection approach comprising inactivation of microorganisms by ultraviolet (UV) light irradiation in a flow through device followed by ultrafiltration (UF) to concentrate the sample. Small-scale, low-pressure, flow-through UV lamps achieved inactivation levels of 3-log₁₀ with a UV dose of 35 mJ/cm² for MS-2 compared to 4-log₁₀ at 140 mJ/cm² for B. subtilis spores. Consequently, a dose of 200 mJ/cm² was selected as a target that should provide an acceptable level of operator safety in the event of contaminated samples being collected. UF involved recirculation of 100 L spiked drinking water samples through 65K hollow-fiber capsules, providing a concentration factor of 133 ¿¿¿¿¿¿¿¿ 1,000. Average recovery efficiencies were 68% for MS-2, 76% for echovirus 1, 60% for B. subtilis spores, 57% for Salmonella typhimurium, 86% for Cryptosporidium parvum, and 56% for Encephalitozoon intestinalis. Non-UV irradiated concentrates were compatible with all conventional culturing methods, infectivity assays, and microscopic detection methods. This work demonstrated the feasibility of inactivating pathogens using a small-scale UV device and simultaneous recovery of viruses, protozoa, bacteria, and spores from large volumes of drinking water by UF. Current work involves integrating the UV and UF units into a single system, assessing the impact of UV irradiation on the ability to detect target pathogens by culture-independent molecular methods, and evaluating whether doses that are high enough to destroy chemical contaminants will interfere with molecular detection of pathogens. Includes 12 references, tables, figures.