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City of Phoenix
Phoenix, Arizona, USA

In anticipation of more stringent effluent nitrogen limits, the City of Phoenix decided to upgrade secondary treatment facilities at one of its wastewater treatment facilities.

Malcolm Pirnie designed a retrofit of the activated sludge facilities. They used an original biological nutrient removal (BNR) process―the first application in this type of large treatment plant. Developed specifically for effectiveness with the area’s warm wastewaters, this application achieves critical nitrogen removal on a daily basis.

As a result of the innovative BNR process and other physical and operational changes, the treatment plant now produces high-quality effluent suitable for beneficial reuse. The Pirnie team implemented all the improvements without reducing the level of treatment capacity or interrupting plant operations. The team also integrated the improvements with long-range plans for odor and air emission control—an important step towards a sustainable environment in this desert community.