Book Description
Two groups of disinfection byproducts (DBPs) currently regulated in drinking water are trihalomethanes (THMs) and haloacetic acids (HAAs). The objective of this research was to better understand how the water treatment processes employed at four smaller municipal water treatment utilities affects THM and HAA formation by measuring the removal of organic precursors through each major treatment process and by studying the concentrations formed as part of normal treatment and distribution. Major results of this study include the observation that significant organic DBP precursor removal generally only occurs in a single treatment process; sedimentation/ precipitation and activated carbon adsorption processes early in treatment were identified as most effective for the utilities studied in this research, with removals of 50-95%of incoming organic precursor material observed. The Missouri River utility examined in greater detail is also of interest because of periodic high incorporation of bromide present in source water; these bromine-substituted THMs are of additional concern due to their greater mass and potential human health risks. Conventional treatment was found ineffective at altering bromide incorporation into THMs, only decreasing available organic material. Both seasonal and long-term variations in bromine-substituted THMs were observed, with higher apparent bromide concentrations noted during periods of lower river flow rate. Bromide was also found in THMs at upstream Missouri River water utilities, indicating that many in the region could be affected by these changes over time.