The COD concentrations of PFS coagulation treated effluent were diluted 213 mg/L, 599 mg/L and 905 mg/L. The other conditions were 3.0 g/L of H2O2, 2.4 g/L of FeSO4 and pH 4.0. The affections of initial COD concentrations to Fenton reaction rate were examined, which could be seen in Fig. 6 and Table 2.