The relationship between disinfection by-product formation and structural characteristics of humic substances in chloramination

The influence of structural characteristics of humic substances on disinfection by-product (DBP) formation was investigated for seven humic substances isolated from aquatic and terrestrial sources. The structural characterizations included C-13 nuclear magnetic resonance (C-13 NMR) spectroscopy and ultraviolet (UV) spectroscopy. The aqueous humic substances were chloraminated at pH 7.0 and 8.5. with and without the presence of the bromide ion, and analyzed for total organic halogen (TOX), trihalomethanes (THMs). and haloacetic acids (HAAs). Aromatic contents determined by C-13 NMR and differential UV absorbance at 254 nm statistically correlated with TOX formation for the humic Substances investigated at p < 0.08. In contrast, a lack of correlation was observed for THM and HAA formation and these parameters. This paper also compiles relevant literature and discusses the contrasting reaction response of DBP precursor material to chlorination and chloramination.