Understanding the factors influencing the
formation of disinfection by-products in drinking
water: Quantification and Characterisation of
aquatic humic substances
Huma Sanawar, Josephine Treacy, Paul Vesey
Department of Applied Science; School of Science, Engineering and Information Technology
School of the Built Environment; Limerick Institute of Technology
Email: huma.sanawar@lit.ie; josephine.treacy@lit.ie; paul.vesey@lit.ie
Humic acids form a significant fraction of aquatic natural organic matter (NOM). They are
known to react with disinfectants during the production of drinking water. Thereby, humic
acids act as major precursors to hazardous disinfection by-products (DBPs). Information on
the complex chemical structures of humic acids is unresolved and the mechanism of DBP
formation is unclear. This research focuses on understanding the extent of DBPs formation
under different treatment and source water conditions, including the NOM character of
abstraction waters. This poster will explain how humic acids, in the presence of
disinfectants, can form toxic by-products such as trihalomethanes (THMs) and haloacetic
acids (HAAs). The quantification of humic acids in water using a liquid-liquid extraction
procedure followed by UV-Visible spectrophotometric analysis at 520 nm will be described.
Humic acids will also be characterised by Infrared Spectroscopy in an effort to understand
the molecular nature of NOM in source waters. The importance of characterisation and
quantification of humic acids to prevent the formation of DBPs will be demonstrated in this
poster. This research will provide support for the regulation of disinfectant by-products with
regard to the EU Drinking Water Directive and public health issues.