AWWA WQTC62504

With the approach of the Stage 2 D/DBP Rule and its requirement for compliance with locational running annual average (LRAA) disinfection byproduct (DBP) maximum contaminant levels, it is necessary for many utilities to take a closer look a DBP control in the distribution system. Salt Lake City Public Utilities Department (SLCPUD) has undertaken a series of pilot studies at Parleys Treatment Plant to determine what technologies would be best suited to this end. Of the three treatment plants owned and operated by SLCPUD, Parleys is the major contributor to distribution system DBPs. The first study, described in this paper, tested the capabilities of conventional enhanced coagulation treatment to reduce DBP levels. Future studies are planned to look at other technologies. It is difficult to know what direction future DBP regulations will take. At one point it seemed likely that they would push toward continual lowering of maximum contaminant levels for total trihalomethanes (TTHM) and haloacetic acid 5 (HAA5) to the 40 µg/L and 30 µg/L marks respectively. Today it seems more likely that future regulations will focus on individual DBP species within TTHM and HAA5. The purpose of this pilot study was to test the limits of conventional treatment, and the focus was on TTHM and HAA5, which are currently regulated. There will be some discussion of the individual DBP species in the results, but the goals of the study were set with respect to TTHM and HAA5. Includes 4 references, tables, figures.