AWWA WQTC62519

Several water systems throughout the United States failed to comply with the Stage 1 Disinfectants/Disinfection Byproduct Rule (D/DBP Rule) this past year. With the Stage 2 D/DBP Rule scheduled to be promulgated by the end of this year (2005), even more utilities will be out of compliance with DBP regulations in the future unless significant operational or treatment changes are implemented. Conversion to chloramines has been the fall-back for many utilities. However, chloramines are not necessarily the answer for all utilities, especially those concerned about security issues, wastewater nitrogen levels, increased distribution system operations, health affects associated with nitrogenous DBPs, or siting ammonia storage and feed facilities. The purpose of this paper is to briefly discuss DBP control options and present results from a case study that bought DBPs under control without switching to chloramines. The control options examined include: lowering applied chlorine dose; altering pH in the distribution system; implementing operational changes to decrease detention time in the distribution system; using chlorine dioxide as a pre-oxidant; and, converting to chloramines. The study demonstrated that THM and HAA levels can be reduced to varying degrees (10 to 40%) depending on the control option employed and the characteristics of the source water. Interestingly, all options reduced THM and HAA levels to different extents. For example, chlorine dioxide reduced THM levels by as much as 40%, but usually had very little effect on HAA levels, whereas lowering the applied chlorine dose had a greater effect on HAA levels. Includes tables, figures.