The objective of this work was to elucidate key drivers of phosphorus removal in a fullscale EcoRecover system, including the role of stored carbohydrates to support phosphorus uptake under dark conditions and the potential for polyphosphate accumulation. The EcoRecover system was deployed as a tertiary treatment process to achieve effluent total phosphorus concentrations below new water quality-based permit limits of 0.12 mg-P•L -1 (monthly) and 0.04 mg-P•L -1 (6-month average) for the full forward (design) flow of 568 m 3 •day -1 (150,000 gal•day -1 ).