AWWA WQTC58987

To minimize the disinfection byproduct (DBP) formation, three relatively inexpensive optimization options are available to plants that chlorinate prior to or at the rapid mix that include: lowering the level of chlorine added; moving the point of chlorination; and, switching to a different disinfectant/oxidant. Prior bench and pilot studies by the authors have found evidence that DBP formation can be controlled through these optimization options. However, the results of these studies would be more valuable to utilities if the scale-up from bench- to pilot- to full-scale processes were established. The objectives of this study were to develop an optimization methodology for preoxidation conditions with respect to DBP formation, and to develop a scale-up approach for bench to pilot to full-scale processes. Experiments were conducted at the bench- and pilot-scale for two Boulder, Colorado water treatment plants: the Betasso Water Treatment Plant (BWTP), and the 63rd Street Water Treatment Plant (63rd WTP). The bench scale was found to accurately represent the pilot plant with respect to turbidity, TOC, chlorine demand and DBPs formed when comparing the same dose conditions and similar operating temperatures. In addition, the full-scale plant at the BWTP was also well simulated by the pilot and bench results. Comparing the bench and pilot DBP results for the BWTP source water yield an average error of 6 ug/L for both clear-well and 24-hour total trihalomethane (TTHM) formation for all dose scenarios. The range of TTHM values for the clear-well was 27-49 ug/L, and for 24-hour TTHM it was: 39-72 ug/L. Comparing the bench and pilot results to the fullscale BWTP yielded a 24-hour TTHM of 60 and 51 to 61, for the single dose scenario that the full-scale plant was operating under. Includes 3 references, tables, figures.