Characterization of disinfection by-product precursors from Missouri streams

Abstract

The NOM contained in drinking water sources reacts with Cl2 to generate THMs and HAAs. THMs and HAAs are regulated by EPA because they pose a health hazard. The nature of the DBP precursors is complex and not well understood. UV and Fluorescence spectroscopy were used to characterize NOM from thirty eight Missouri state streams, and the relationship with the THM and HAA formation potentials was investigated. The samples that were collected during the months of March, June and Sept-October of 2006 were found to contain more allochthonous NOM than Autochthonous NOM as shown by fluorescence Index. Three fluorophores: humic-like, fulvic-like and protein-like were recognized from fluorescence scans and PARAFAC model components. During the spring (March) high flows carried NOM of high aromatic rings, as shown by UVA254, which are THMs and HAAs precursors. However, during the summer the generation of the total DBPs was the highest. Chloroform was the dominant THMs species, and TCAA and DCAA were the dominant HAAs species. The protein-like materials as well as humic-like substances generate THMs and HAAs. Finally, northeastern Missouri samples generated UVA254, DBPs and fluorophores maxima.