To date, commercialized tertiary wastewater treatment technologies for phosphorus management have been limited to enhanced biological phosphorus removal (EBPR), chemical polishing, and membranes. EBPR can be a lower cost among these options but cannot reliably treat below 0.3 mg•L -1 total phosphorus. Though chemical polishing with coagulants (typically aluminum sulfate or ferric chloride) can achieve more stringent effluent limits, significant addition of these chemicals generates large quantities of sludge that are difficult to treat, are expensive to landfill, and that represent a recalcitrant precipitate that make phosphorus recovery challenging. Additionally, reliably achieving very low phosphorus effluent concentrations (e.g., <0.1 mg-P•L -1 ) requires coagulant dosing that is significantly higher than predicted by stoichiometric quantities due to numerous side reactions, and the stoichiometric disparity increases substantially as target effluent phosphorus concentrations decrease. Once precipitated, phosphorus-recovery from chemical polishing sludge requires chemical extraction and/or thermal approaches at very high temperatures (1,000 to 2,000 °C). As an alternative to bacteria-driven luxury uptake in EBPR and to chemical polishing, microalgae can achieve phosphorus recovery -including organic phosphorus that is otherwise recalcitrant in conventional WRRFs -through assimilation into new biomass, luxury uptake (as polyphosphate), and surface adsorption. If algal treatment systems can be engineered to reliably meet effluent nutrient permits, they have the potential to leverage waste phosphorus for CO2 fixation, to enable the recovery of phosphorus from harvested biomass, and to serve as a feedstock for the production of renewable bioproducts and biofuels in support of a circular economy. Phototrophic wastewater treatment processes continue to be developed in both attached growth and suspended growth configurations. Attached growth systems, such as the revolving algal biofilm (RAB) and the rotating algal biofilm reactor , grow mixed communities as biofilms and often cycle them between (i) submerged conditions for nutrient uptake and (ii) atmospheric conditions to support gas exchange (including CO2 uptake) and exposure to light. Recent characterization of RAB systems across the Midwest U.S. has demonstrated the potential for luxury phosphorus uptake (as polyphosphate) in RAB communities. Polyphosphate -along with polyhydroxyalkanoates and glycogen -is a key biopolymer in the rhythm of (chemotrophic) EBPR systems, helping polyphosphate accumulating organisms to balance growth across cycling environmental conditions. Although it is not apparent that polyphosphate serves to balance cellular metabolism in light-driven wastewater treatment systems (as in EBPR systems), the storage and mobilization of carbohydrates has been shown to help balance activity across lightdark cycling of suspended growth algae cultures. This past work, however, focused on diel lighting with laboratory-scale cultures, whereas intensive wastewater treatment systems can cycle algae between light and dark conditions at timescales of minutes or hours (faster than day-night cycles) and will select for their own mixed communities of microorganisms. It is important, therefore, that we continue to elucidate the role of biopolymers -including polyphosphate and storage carbohydrates -in real-world installations of phototrophic wastewater treatment systems.