Survival of bacterial indicator species and bacteriophages after thermal treatment of sludge and sewage.
The inactivation of naturally occurring bacterial indicators and bacteriophages by thermal treatment of a dewatered sludge and raw sewage was studied. The sludge was heated at 80 degrees C, and the sewage was heated at 60 degrees C. In both cases phages were significantly more resistant to thermal inactivation than bacterial indicators, with the exception of spores of sulfite-reducing clostridia. Somatic coliphages and phages infecting Bacteroides fragilis were significantly more resistant than F-specific RNA phages. Similar trends were observed in sludge and sewage. The effects of thermal treatment on various phages belonging to the three groups mentioned above and on various enteroviruses added to sewage were also studied. The results revealed that the variability in the resistance of phages agreed with the data obtained with the naturally occurring populations and that the phages that were studied were more resistant to heat treatment than the enteroviruses that were studied. The phages survived significantly better than Salmonella choleraesuis, and the extents of inactivation indicated that naturally occurring bacteriophages can be used to monitor the inactivation of Escherichia coli and Salmonella.
Mocé-Llivina
Laura
L
Department of Microbiology, Faculty of Biology, University of Barcelona, Avenida Diagonal 645, 08028 Barcelona, Spain.
Muniesa
Maite
M
Pimenta-Vale
Hugo
H
Lucena
Francisco
F
Jofre
Juan
J
D001419:Bacteria / Q000254:growth & development*; D001435:Bacteriophages / Q000254:growth & development*; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000254:growth & development; D004770:Enterovirus / Q000254:growth & development; D006358:Hot Temperature; D007202:Indicators and Reagents; D012722:Sewage / Q000382:microbiology* / Q000821:virology*; D014865:Waste Disposal, Fluid / Q000379:methods
D007202:Indicators and Reagents; D012722:Sewage