Interactions Between Bromine and Natural Organic Matter

Abstract

Bromine reacts quickly with natural organic matter (NOM) to form bromide and organo-bromine species. Bromine consumption by NOM occurs rapidly and the pseudo first order rate constants for bromine decomposition are on the order of 0.12 to 1.3x10-3 s-1 (DOC = 3 mg/L, pH = 7.5, and bromine dose = 5 μm); values decrease for preozonated NOM (0.11 to 0.24x10-3 s-1). Based on multiple pH experiments, both hypobromous acid (HOBr) and hypobromite (OBr-) appear to react with equally with NOM under experimental conditions in this study. Bromine reduction by NOM appears to contribute to 80% of the reaction, while bromine incorporation into NOM accounts for the remaining 20%. The formation of organo-bromine species was noted to be extremely rapid (< 5 minutes) for DOC = 3 mg/L, pH = 7.5, and bromine dose = 5 μm. Overall, reactions between bromine and NOM may significantly influence the formation of disinfection by-products (DBPs) such as bromate during ozonation of bromide containing waters.