Bacteriophages as model organisms for monitoring the microbiological quality of the effluent of a wastewater treatment plant

摘要: The discharge of treated wastewater in surface water and its reuse in agriculture requires a good microbiological quality of the effluent, in order to protect the environment and the public health. The use of bacterial indicators for monitoring the microbiological quality of the effluent is not always adequate, since pathogens, such as enteroviruses, are more resistant to natural inactivation and to treatment processes. Therefore, the use of bacteriophages as indicators has been studied recently. In this study an effort was made to correlate the number of bacterial indicators with the presence of three groups of bacteriophages; somatic coliphages, F-RNA specific phages and phages of Bacteroides fragilis, in raw and treated sewage and septage. Samples of each treatment stage of two sewage treatment plants in Athens, in a 2-year period, were collected monthly, and analyzed for total coliforms, E. coli, intestinal enterococci and the three groups of bacteriophages. A clear correlation between the number of bacterial indicators and the presence of bacteriophages was observed. E. coli and enterococci concentrations of 103 cfus/100ml consist a threshold for the presence of somatic coliphages in wastewater. E. coli concentrations of 106 cfus/100ml and enterococci of 105 cfus/100ml consist a threshold for the presence of F-specific bacteriophages, and E. coli and enterococci concentrations of 106 cfus/100ml consist a threshold for the presence of B. fragilis phages.