To explore alternative mechanisms for phosphorus recovery, the elemental composition of harvested biomass was characterized. The phosphorus content in algal biomass has been shown to vary across species and also within species as a function of their physiological state. The phosphorus content in microalgal cells is often around 1% of dry weight under limited phosphorus availability but may be as high as 3-10% dry weight when the microalgae achieve luxury uptake of phosphorus. The average phosphorus content of harvested biomass across the full focus period was 3.2 ± 0.7% (5 th /50 th /95 th percentiles of 2.2%/3.6%/4.0%; n = 32; Figure ), further suggesting partial phosphorus recovery via luxury uptake, surface adsorption, or precipitation of phosphorus.