A critical review of trihalomethane and haloacetic acid formation from natural organic matter surrogates

Disinfection by-products (DBPs) in drinking water, including trihalomethanes (THMs) and haloacetic acids (HAAs), arise from reactions of natural organic matter (NOM) with chlorine and other disinfectants. The objective of this review was to investigate relationships between the molecular properties of NOM surrogates and DBP formation using data collated for 185 compounds. While formation of THMs correlated strongly with chlorine substitution, no meaningful relationships existed between compound physicochemical properties and DBP formation. Thus non-empirical predictors of DBP formation are unlikely in natural waters. Activated aromatic compounds are well known to be reactive precursors; in addition DBP formation from β-dicarbonyl, amino acid and carbohydrate precursors can be significant. Therefore effective DBP control strategies need to encompass both hydrophobic and hydrophilic NOM components, as well as consider data from NOM surrogates in the context of knowledge from representative treatment scenarios. In future experiments, employing surrogates of NOM is likely to remain a powerful tool in the search for unknown precursors and in understanding their response to various disinfection conditions