AWWA JAW61251

As part of the proposed Stage 2 Disinfectants/Disinfection Byproducts Rule (Stage 2 D/DBPR), utilities will have to reassess the location of samples collected for DBP compliance monitoring. This is complicated by the various trends observed for the different classes of DBPs in distribution systems, as well as within each class, and by the fact that different subclasses of haloacetic acids (HAAs) are expected to peak at different locations because of their different chemical properties. The results described here give utilities additional knowledge and tools to help them select their sampling locations for DBP monitoring as part of the proposed Stage 2 D/DBPR. To carry out the work, simulated distribution systems (annular reactors) were placed in two parallel trains at the effluent of a fullscale treatment plant: one train received chlorinated water and the other chloraminated water. Each train was composed of two annular reactors in series. The upstream annular reactor received water with a disinfectant residual, and the downstream annular reactor received dechlorinated or dechloraminated water. The effect of DBP contact with biofilm formed in the absence of corrosion byproducts, with and without a chlorine or chloramine residual, was addressed in both cold and warm waters. Trihalomethanes (THMs) and HAAs continued to form in the distribution system in the presence of a free chlorine residual but remained relatively unchanged in the presence of a chloramine residual. In the absence of a chlorine residual, some of the HAA species remained unchanged in cold water but were degraded in warm water. Other HAA species showed different trends in the absence of a disinfectant residual, but in general, concentrations remained unchanged. In the absence of a disinfectant residual (either free chlorine or chloramines), THM concentrations remained relatively unchanged. Includes 23 references, table, figures.