Fate of human enteric viruses, coliphages, and Clostridium perfringens during drinking-water treatment.
The elimination of human enteric viruses, coliphages, and Clostridium perfringens was studied during a conventional complete drinking-water treatment process. The respective concentrations (geometric mean) of these microorganisms in 100-L samples of river water were, respectively, as follows: viruses, 79 mpniu (most probable number of infectious units) per 100 L, coliphages, 6565 pfu (plaque-forming units) per 100 L. and clostridia, 11,349 cfu (colony-forming units) per 100 L. After predisinfection, flocculation with alum, and settling, human enteric viruses were not detected in any of the 100-L samples (less than 4 mpniu/100 L), but coliphages were detected in 7 of 14 samples and clostridia in 15 of 16 samples. In filtered water samples, human enteric viruses were detected in 2 of 31 samples, coliphages in 10 of 33, and clostridia in 17 of 33. Finished water was free of human enteric viruses (0/162 samples), but coliphages were detected in one sample (1.5 pfu/100 L) and clostridia in three, at 1.0, 4.1, and 7.0 cfu/100 L. It thus appears that coliphages and clostridia, which are present in larger numbers than viruses in river water and which may have similar resistance to drinking-water treatments, may be useful for estimating the level of treatment attained when large volumes of water (1000 L or greater) are sampled.
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Centre de recherche en virologie, Institut Armand-Frappier, Université du Québec, Laval, Canada.
D003016:Clostridium perfringens / Q000302:isolation & purification*; D003090:Coliphages / Q000302:isolation & purification*; D004770:Enterovirus / Q000302:isolation & purification*; D004769:Enterovirus Infections / Q000382:microbiology; D005374:Filtration; D006801:Humans; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D014881:Water Supply