Case Study: Flagstaff, AZ

June 29, 2009

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•Case Study: Flagstaff, AZ

By Veolia Water Solutions & Technologies

The Challenge
In order to achieve more stringent effluent limits, the City of Flagstaff worked with Black and Veatch to upgrade the Wildcat Hill Wastewater Treatment Facility, located in northern Arizona. The facility produces a high quality effluent, as well as reclaimed water, which is distributed throughout the region to construction companies and golf courses. The remaining treated water is discharged into the Rio de Flag Creek. The plant has a design influent annual average flow of 6.0 MGD.

Plant Overview
The Wildcat Hill Wastewater Treatment Facility consists of Primary, Secondary, and Tertiary treatment. The primary treatment includes two (2) bar screens and a grit removal chamber, followed by four (4) clarifiers. Secondary treatment previously consisted of biofilters. These were replaced with a Kruger AnoxKaldnes Hybas™ system, which consists of media, air grids, screens and screen supports. The effluent leaving the Hybas enters five (5) secondary clarifiers. Traveling bridge media filters were previously utilized for tertiary treatment, followed by chlorination and dechlorination. Two (2) Kruger Hydrotech Discfilters were installed to provide for filtration in the new design.