Figure 10: Changes in populations of Escherichia coli and viruses ( ) in treated water relative to the initial populations ( ) as a function of specific energy release (J cm−3) during the treatment. Potable water with a conductivity μS cm−1 was used.  Hz. The initial ( ) concentration of E. coli was 106 colony-forming units mL−1 and that of coliphages 107 plaque-forming units mL−1. (1)  E. coli; (2) coliphages.