Effects of organic matter, ammonia, bromide, and hydrogen peroxide on bromate formation during water ozonation

Abstract

Ozone is widely applied for disinfection in drinking water treatment and the disinfection by-product bromate would be produced during the ozonation of bromide-bearing water. Hydrogen peroxide (H₂O₂) addition could effectively control the formation of bromate. However, the bromate depression performance would be impacted by water qualities. In this study, typical source water containing bromide in eastern China was selected to investigate bromate depression effect under different organic matter, ammonia and bromide concentrations during the H₂O₂-O₃ process. The results display that organic matter, ammonia and bromide concentration could influence the formation of bromate significantly. As tyrosine was applied to increase the dissolved organic carbon (DOC) concentration of source water by 2.0 and 3.0 mg/L, the total concentration of bromate produced decreased gradually as the H₂O₂/O₃ (g/g) doses increased from 0 to 1.0 and bromate concentration could be controlled below 10 μg/L as H₂O₂/O₃ (g/g) was 0.5 and 1.0. As ammonia concentration increased by 0.1 and 0.5 mg/L, lower H₂O₂/O₃ (g/g) doses would lead to an increase in bromate generation. As more H₂O₂ was added in water, the bromate formation would be suppressed. The increase of bromide concentration induced higher bromate formation. When the bromide concentration increased by 50 and 200 μg/L, bromate concentration was 10.7 μg/L and 41.2 μg/L respectively at the H₂O₂/O₃ (g/g) of 1.0, higher than the standard level. As 200 μg/L of bromide was added to the water, bromate concentration increased significantly and then decreased as H₂O₂/O₃ (g/g) increased and more H₂O₂ would be needed for bromate control.

Keywords: Ammonia; Bromate; Drinking water; Hydrogen peroxide; Organic matter; Ozone.