Effects of thermal treatment on halogenated disinfection by-products in drinking water

The influence of heating or boiling on the formation and behavior of disinf ection by-products (DBPs) was investigated in DBP-spiked reagent water, mun icipal tap water, and synthetic water containing chlorinated aquatic humic substances, Thermal cleavage of larger halogenated species leads to both fo rmation of smaller chlorinated molecules (including THMs and HAAs) and dech lorination of organics. In parallel with their formation from larger molecu les, THMs can be volatilized, and this latter process dominates the change in their concentration when water is boiled. HAAs are not volatile, but the y can be destroyed by chemical reactions at elevated temperatures, with the net effect being loss of trihalogenated HAAs and either formation or loss of less chlorinated HAAs. Although other identifiable DBPs can be generated at slightly elevated temperatures, in most cases their concentrations decl ine dramatically when the solution is heated. (C) 2001 Elsevier Science Ltd . All rights reserved.