Additional evidence of polyphosphate accumulation was seen in EDS measurements, which showed a higher phosphorus content in granules than in biomass (i.e., cell components away from granules) and indicated a positive relationship between phosphorus and cation content (Figure ); a positive correlation between phosphorus and cation content is consistent with past studies analyzing polyphosphate accumulating organisms. Finally, the dominant taxa at this date was Scenedesmus spp. (discussed below), which is capable of polyphosphate accumulation. In periods of low biomass phosphorus content (e.g., 1.3% on August 16, 2022), no granules were observed (Figures ). Beyond polyphosphate accumulation, high pH at the surface of microalgal cells (due to inorganic carbon fixation) may have facilitated inorganic phosphorus precipitation on the cell surfaces or within extracellular polymeric substance (EPS) even at low total phosphorus concentrations. This mechanism of phosphorus recovery, however, was not as readily apparent. ). Bright particles in (A) and (B) represent highly localized, elevated concentrations of phosphorus and metals that appear as granules within cells.