AWWA ACE68690

The objective of this paper is to examine the control of precursors for various emerging N- and C-DBPs and how that compares with the control of THM precursors. A full-scale survey of 16 U.S. drinking water treatment plants (DWTPs) was conducted in 2006 and 2007 (each plant was sampled once or twice). The focus of this study was on DWTPs that treated wastewater and/or algal impacted water, which are sources of precursors for N-DBPs. All of the DWTPs in this study treated surface water. DWTPs sampled used a range of treatment processes (coagulation, lime softening, ultrafiltration, filtration with granular activated carbon [GAC]) and disinfectants (chlorine [Cl₂], chlorine dioxide, chloramines [NH₂Cl], ozone, UV). The sample sites were in various geographical regions of the U.S. Analytical parameters are detailed in this paper, along with study results. A summary of the study indicated that utilities have installed and modified treatment practices to control the formation of regulated DBPs (e.g., THMs). In this study, DBPFP tests were conducted on samples from different points in the surveyed plants. These tests not only showed the removal or destruction of DBP precursors with various unit processes, but the contribution of certain processes to increasing DBPFP (e.g., use of certain polymers increasing NDMAFP; ozonation increasing TCNMFP). In order to balance the control of regulated DBPs with that of emerging DBPs of health concern, utilities will need to optimize a series of various unit processes to minimize the formation of a wide range of DBPs. Includes 20 references, tables, figures.