A Blending of Old and New School for Reclaimed Water Disinfection in Arizona

In 1998, to meet the challenges of low-level coliform and DBP regulations related to Aquifer Storage and Recovery (ASR), the City of Glendale (Arizona) installed an open channel medium pressure (MP) UV system. The selected UV system has been encumbered with ballast and lamp failures, resulting in substantial O&M effort and cost. Further, the O&M staff clean and bleach the UV channel weekly to reduce algae buildup within the channel. The objective of the work to be presented here is to find a disinfection technology that will reliably meet the stringent coliform and DBP requirements for Glendale. This technology should result in a reduced O&M cost and effort from staff and decrease the potential for permit violations related to DBPs. Ozone, UV, and chlorine all readily attain non-detect total coliform at low doses with existing filtration approach. Powdered Activated Carbon is able to reduce the DBP precursors and DBPs significantly.