Comparison of removal performance of two surrogates for pathogenic waterborne viruses, bacteriophage Qβ and MS2, in a coagulation–ceramic microfiltration system

The removal performance of two surrogates for pathogenic waterborne viruses, F-specific RNA bacteriophages Qβ and MS2, was evaluated during the coagulation–ceramic microfiltration process. River water spiked with these bacteriophages was used to investigate differences in their behaviors. Infectious and total (infectious + inactivated) bacteriophage concentrations were measured by plaque forming unit and real-time reverse transcription–polymerase chain reaction methods, respectively. Removal of infectious Qβ and MS2 was similar under each coagulation condition. Approximately 6-log reduction was achieved for both bacteriophages at 1.08 mg-Al/L of coagulant dose and 5-min coagulation time. At least 4-log reduction occurred even when coagulant dose and coagulation time were reduced to 0.54 mg-Al/L and 1.8 s, respectively. In contrast, removal of total Qβ and MS2 differed markedly. Removal of total MS2 was approximately 2-log larger than that of total Qβ, possibly owing to selective interaction with the cake layer, although the particle diameters and electrophoretic mobilities of Qβ and MS2 were similar. The total number of bacteriophages retained in the microfiltration compartment after 4-h filtration was similar for Qβ and MS2, but there were approximately 3 log fewer infectious Qβ than infectious MS2, probably owing to the difference in sensitivity to the virucidal activity of aluminum coagulant.