To ensure the safety of drinking water, ozone (O
3) has been extensively applied in drinking water treatment plants to further remove natural organic matter (NOM). However, the surface water and groundwater near the coastal areas often contain high concentrations of bromide ion (Br
?). Considering the risk of bromate (BrO
3?) formation in ozonation of the sand-filtered water, the inhibitory efficiencies of hydrogen peroxide (H
2O
2) and ammonia (NH
3) on BrO
3? formation during ozonation process were compared. The addition of H
2O
2 effectively inhibited BrO
3? formation at an initial Br
? concentration amended to 350 µg/L. The inhibition efficiencies reached 59.6 and 100% when the mass ratio of H
2O
2/O
3 was 0.25 and > 0.5, respectively. The UV
254 and total organic carbon (TOC) also decreased after adding H
2O
2, while the formation potential of trihalomethanes (THMsFP) increased especially in subsequent chlorination process at a low dose of H
2O
2. To control the formation of both BrO
3? and THMs, a relatively large dose of O
3 and a high ratio of H
2O
2/O
3were generally needed. NH
3 addition inhibited BrO
3? formation when the background ammonia nitrogen (NH
3N) concentration was low. There was no significant correlation between BrO
3? inhibition efficiency and NH
3 dose, and a small amount of NH
3N (0.2 mg/L) could obviously inhibit BrO
3? formation. The oxidation of NOM seemed unaffected by NH
3 addition, and the structure of NOM reflected by synchronous fluorescence (SF) scanning remained almost unchanged before and after adding NH
3. Considering the formation of BrO
3? and THMs, the optimal dose of NH
3 was suggested to be 0.5 mg/L.
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