Process‐train profiles of NOM through a drinking water treatment plant

Abstract

The aims of this study were to track variations in natural organic matter (NOM) and bromide (Br‐) through various treatment processes (coagulation, sand filtration, ozonation, and biological activated carbon [BAC]) comprising a process train in a full‐scale drinking water treatment plant, to describe seasonal variations of NOM and Br‐ and to investigate disinfection by–products (DBPs) formation associated with NOM and Br‐ changes. In addition, relationships between chlorination DBPs and NOM properties were evaluated. Samples were collected from one French water treatment plant across treatment processes comprising a process train and throughout different seasons. NOM profiles were defined using various methods, including ultraviolet (UV) absorbance spectra, nonionic resin fractionation, and high‐performance liquid chromatography/size exclusion chromatography with UV absorbance and on‐line dissolved organic carbon detection. Coagulation was found to strongly affect the molecular weight distribution of NOM. However, ozonation has more impact on aromaticity and imparts hydrophilic properties. Changes in NOM properties through sand filtration and BAC were relatively small. Br‐ passed conservatively through the process train except for ozonation and BAC processes. Both trihalomethanes (61%) and haloacetic acids (69%) were significantly reduced through the treatment processes.