Concentration and inactivation of bacteria, spores, viruses, andprotozoa from large volumes of drinking water

摘要

A single sample concentration and recovery procedure that can be used for bacteria, protozoa,rnand viruses will greatly improve the ability of water utilities and other agencies to respond torncontamination events. However, it is critical to minimize exposure of sample collectors tornpotential biological and chemical hazards in contaminated water. Therefore, the objective of thisrnstudy was to develop a pathogen detection approach comprising inactivation of microorganismsrnby ultraviolet (UV) light irradiation in a flow through device followed by ultrafiltration (UF) tornconcentrate the sample. Small-scale, low-pressure, flow-through UV lamps achieved inactivationrnlevels of 3-log10 with a UV dose of 35 mJ/cm2 for MS-2 compared to 4-log10 at 140 mJ/cm2 forrnB. subtilis spores. Consequently, a dose of 200 mJ/cm2 was selected as a target that shouldrnprovide an acceptable level of operator safety in the event of contaminated samples beingrncollected. UF involved recirculation of 100 L spiked drinking water samples through 65Krnhollow-fiber capsules, providing a concentration factor of 133 – 1,000 . Average recoveryrnefficiencies were 68% for MS-2, 76% for echovirus 1, 60% for B. subtilis spores, 57% forrnSalmonella typhimurium, 86% for Cryptosporidium parvum, and 56% for Encephalitozoonrnintestinalis. Non-UV irradiated concentrates were compatible with all conventional culturingrnmethods, infectivity assays, and microscopic detection methods. This work demonstrated thernfeasibility of inactivating pathogens using a small-scale UV device and simultaneous recovery ofrnviruses, protozoa, bacteria, and spores from large volumes of drinking water by UF. Currentrnwork involves integrating the UV and UF units into a single system, assessing the impact of UVrnirradiation on the ability to detect target pathogens by culture-independent molecular methods,rnand evaluating whether doses that are high enough to destroy chemical contaminants willrninterfere with molecular detection of pathogens.