Phosphorus bioavailability and recycling potential in various organic Waste: Assessment by enzymatic hydrolysis and 31P NMR

Phosphorus(P) recycling from waste streams is crucial to mitigate the P depletion crisis. P forms and contents in organic waste are critical for determining the recycling method and efficiency. We constructed an approach to characterize P forms in seven organic waste by combining chemical sequential extraction, enzymatic hydrolysis, and nuclear magnetic resonance(NMR). Livestock manure and straw exhibited a higher active P(H₂O-P&NaHCO₃-P)(70.54%-84.40% and 65.78%-85.26% of total P) than sewage sludge(18.22%) and food waste(43.90%). Enzymatic hydrolysis revealed over 10% P in the so-called active P of corn(11.30%) and rice straw(13.32%) was phytate-like P, which is not bioavailable. These findings indicate the chemical sequential extraction inaccurately gauges bioavailable-P and underscores the need to convert phytate into plant-available P in recycling processes(biogas, composting), especially for crop straws and chicken manure. This work introduces a novel methodological framework for assessing P potential bioavailability in organic waste, providing fundamental knowledge for the P recycling process optimization.