The effect of various water parameters on ammonia's ability to reduce bromate formation during ozonation

Ammonia has been shown to reduce bromate formation by reacting with free bromine to form bromamines, thereby blocking two of the three bromate formation pathways. However, bromate formation continues in the third pathway regardless of ammonia addition. In this study, ammonia was more effective at reducing bromate formation when the reaction between natural organic matter (NOM) and bromamines was slower (slower bromamine decay).; It was found that increasing alkalinity had an overriding effect on ammonia's effectiveness, regardless of the dissolved organic carbon concentration, the H₂O₂ production or bromamine decay. Also, the effectiveness of ammonia increased linearly as the change (due to ozonation of NOM) in specific ultraviolet absorbance (SUVA₂₅₄, SUVA₂₈₀) and ultraviolet absorbance ratio (UVA₂₅₄/UVA₂₀₅) values decreased and the SUVA₂₈₀ value (unozonated NOM) decreased.; In practice, this could lead to using values of alkalinity and SUVA ₂₅₄, SUVA₂₈₀, and UVA₂₅₄/UVA₂₀₅ as indicators of ammonia's potential effectiveness as a bromate minimization strategy.