AWWA WQTC69345

The City of Arlington began experiencing atypical water quality problems in 1999 with the introduction of ozonation and biofiltration to the conventional treatment processes. These problems included high chloramine residual decay rates, and system nitrification and manganese in the finished water that were linked to water produced at the Pierce-Burch South Water Treatment facility. After reviewing existing data and literature, and pilot plant and "bottle" testing, it was determined that improvements could be made to the water quality through treatment plant modifications in both design and process that included the following: modifications to the chemical feed points; process changes to how plant biofilters are operated; and, changing the biofilter backwash to non-chloraminated water. Includes table, figures.