The effects of Fe–Mn oxide and TiO2/α-Al2O3 on the formation of disinfection by-products in catalytic ozonation

• The addition of Fe–Mn oxide in HCOP resulted in faster decomposition rates of dissolved ozone than TiO2/α-Al2O3.
• The use of Fe–Mn oxide in HCOP could obtain a higher Rct value than the use of TiO2/α-Al2O3 and ozonation alone.
• The Fe–Mn oxide catalyst could obtain a greater decrease in the formation of DBPs than the TiO2/α-Al2O3 catalyst in HCOP.
• The use of biofiltration after HCOP greatly enhanced the reduction of DBPs formation.

The catalytic activity of Fe–Mn oxide and TiO2/α-Al2O3 catalysts toward the ozonation of natural organic matter (NOM) and a model compound (p-chlorobenzoic acid, pCBA) was investigated in a heterogeneous catalytic ozonation process (HCOP). The monitored parameters in this study included pCBA, dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254), trihalomethanes (THMs), and nine haloacetic acids (HAA9). The Fe–Mn oxide catalyst significantly enhanced the decomposition (kd) of dissolved ozone (O3) and promoted the formation of hydroxyl radicals in the HCOP to a greater extent than did the TiO2/α-Al2O3 catalyst. Both catalysts (Fe–Mn oxide and TiO2/α-Al2O3) used in the HCOP showed better performance with regard to removal efficiency of DOC and UV254 than adsorption and ozonation. Moreover, the Fe–Mn oxide catalyst had higher removal efficiencies for DOC and UV254 in both the HCOP and adsorption than those of the TiO2/α-Al2O3 catalyst. The removal efficiency associated with UV254 was significantly higher than that associated with DOC. The results show that the use of Fe–Mn oxide and TiO2/α-Al2O3 in catalytic ozonation could effectively remove the precursors of disinfection by-products (DBPs), resulting in the formation of fewer THMs and HAA9. In addition, biofiltration of the HCOP treated water can further increase the removal efficiency of DPB precursors, with the type of catalyst used being less important.