Effective Ozonation of Secondary Effluents with Initial Ozone Demand

It is clarified that the ozone consumption during the initial stage of ozonation before dissolved ozone appears is the same value as that during the initial 20 seconds in batch mode experiment. This initial ozone consumption was defined as initial ozone demand (IOD) in this study. IOD of secondary effluent was shown to be 0.3–0.5 mgO3/mgC0. More than 90% of 17β-estradiol (E2) was reduced, and formation of ozonation by-products was controlled within this ozone demand. This state can be also characterized by reduction of the values of UV254, fluorescence intensity at 345 nm (Excitation)/435 nm (Emission) and that at 240 nm/435 nm to 0.06 /cm, 35 and 15, respectively.