The analysis of the long-term performance of a full-scale ozone facility in France confirms the
ability of ozonation to consistently achieve stringent regulations: for a 10-year period, the
residual coliform concentrations being consistently less than 100 E.coli/100 mL, and this in 98%
of the samples for the last 2 years, despite the variations of flow rate, suspended solids
concentrations, TSS (Figure 4a) and initial concentrations of E.coli (Figure 4b). In this full-scale
ozonation facility, the variations of TSS in filtered effluent were relatively low with a geometric
mean of 1.7 mg/L, median 1.2 mg/L, maximum value of 9.6 mg/L and less than 4 mg/L in 90%
of samples. In addition, no Salmonella have been detected in any of the analysed samples of
disinfected effluents. This high disinfection performance was achieved with low TODs of 2.5-5
mg/L, which is 25-50% of the design ozone dose. In average, 4 log removal of E.coli was
achieved with very low residual concentrations of