Sustainable phosphorus recovery and starch-protein-rich biomass generation from wastewater via duckweed

Escalating phosphorus (P) pollution and resource scarcity underscore the urgent need for sustainable wastewater treatment and nutrient recovery systems. However, systematic research on P-removal efficiency and its recovery across concentrations under mixotrophic conditions is still lacking. In this study, Spirodela polyrhiza was used to investigate the physiological responses to P-containing simulated wastewater with respect to its efficacy for pollutant removal and the potential for simultaneous biomass recovery. Our results indicate that S. polyrhiza achieved a maximum total P-removal efficiency of 93.78% at 17 mg/L P, while exhibiting high adaptive plasticity. Under P deficiency, carbon was preferentially allocated to starch accumulation (up to 214 mg/g DW), while elevated P levels stimulated protein and lipid synthesis. The biomass was also enriched with essential minerals, including P, K, Mg, and Zn, supporting its potential use as animal feed, biofuel feedstock, or biofertilizer. This synergistic approach offers a practical pathway to advance the circular bioeconomy and address pressing environmental challenges related to nutrient pollution and resource scarcity.