Properties of sediment NOM collected from a drinking water reservoir in South China, and its association with THMs and HAAs formation

SummaryThe natural organic matter (NOM) from the sediment elutriate, which was obtained from a drinking water reservoir in South China, was fractionated into four fractions by using XAD-8 and XAD-4 resin. Dissolved organic carbon (DOC) as well as UV absorbance at 254 nm (UV254) and specific UV254 (SUV254) were used to quantify and characterize the NOM of raw sediment elutriate and the fractions. Formation of disinfection by-products (DBPs), i.e. trihalomethanes (THMs) and haloacetic acids (HAAs) were also investigated. Results showed that lots of organic matter can be liberated from the sediment during suspension. Hydrophilic organic matter (HiM) accounted for 50.7% of the DOC, followed by hydrophobic acid (HoA) (21.3%), transphilic organic matter (TPH) (15.2%) and other hydrophobic substances (HoS) (12.9%). Different from DOC distribution, the highest UV254 and SUV254 were detected in HoA, while the least were observed in HiM. All the organic fractions were good DBPs precursors. The hydrophobic fractions (HoS and HoA) were more important precursors of CHCl3 and TCAA as compared to other fractions, and UV254 was a good indicator for trichloroacetic acid (TCAA) formation. While for the hydrophilic fraction, relative higher dichloroacetic acid (DCAA) yields were observed, and DOC were good index for its formation.

► Properties of sediment NOM and the associated THMs and HAAs formation.
► Importance of sediment to be the source of DBPs precursors in drink source water.
► Chemical difference among chloroform, DCAA and TCAA precursors.