Phosphorus can be removed from wastewater biologically, chemically, or through a combination of the two. In this study, we applied environmental life-cycle assessment to develop a metric with which decision-makers can compare processes. Two phosphorus-removal scenarios were contrasted-one based on a desktop-level design and one based on full-scale operational data. To achieve 0.5 mg/L effluent phosphorus (desktop design), a biological-only process would incur 5.2% less effect on global warming potential, as contrasted with a chemical-only process. At an effluent quality of 0.1 mg/L (full-scale facilities), where a biological process augmented with chemicals was contrasted with a chemical-only process, the relative gap increases to 13.2%. As chemical usage increased, the adverse environmental effect of chemical treatment only increased. The results of this study suggest that best practices would center phosphorus removal first on the biological process, with chemical processes added only as necessary.