A demonstration of enhanced biological phosphorus (P) removal (EBPR) in one battery at the Stickney WRP was performed using existing plant infrastructure. The site-specific EBPR process was developed by creating anoxic (A), anaerobic (An), and aerobic (O) zones, referred as AAnO, in the return activated sludge (RAS), influent mixing channels, and aeration tanks, which would favor the growth of and luxury P uptake by phosphate-accumulating organisms (PAOs). The demonstration study included five phases (I-V) and focused on operational changes that could be made without investing in additional infrastructure. The test battery has been well outperforming control (non-EBPR) batteries with respect to P removal throughout the study, and effluent total P (TP) from the converted battery has generally improved through each of the first four phases. The whole Stickney plant was converted to AAnO process in Phase V. The average TP of plant outfall was below 1 milligram per liter (mg/L) as monthly average after 5 months of full conversion.