Persulfate-based radical-induced oxidative humification of chicken manure and simultaneous removal of pollutants

Livestock manure is a valuable organic fertilizer, however, current treatment methods encounter challenges such as slow biological fermentation and high-cost abiotic processes. Hence, this study developed an ethylenediaminetetraacetic acid (EDTA)-enhanced Fe⁰ activated persulfate (PS) technology aimed at accelerating the humification of manure. The addition of 2 mL of 0.75 M PS, 0.6 g of Fe⁰ and 0.3 g of EDTA to 10 g of chicken manure achieved substantial humification within 40 min, with fulvic acid and humic acid contents reaching 5.26 % and 8 %, respectively. FTIR and XPS revealed that the treatment transformed organic molecular structures from long-chain aliphatics into unsaturated aromatic and heterocyclic compounds. Reactive oxygen species analysis indicated that the humification process was driven by free radical-mediated oxidation and polymerization reactions. In addition to promoting humification, the technology simultaneously removed pollutants, passivating 77.25 % of bioavailable copper and 35.44 % of bioavailable zinc, and degrading antibiotic resistance genes and hormones. Pot experiments confirmed that the humification products enhanced wheat growth, with 73 % increase in fresh biomass compared to control, while improving weakly alkaline soil through 0.98 pH reduction and 3.84 % organic matter increase. This dual-functional strategy enables rapid manure humification and simultaneous pollutant removal, presenting a promising approach for organic waste management.