Radical-mediated decomposition and polymerization for rapid humification and pollutant removal of livestock manure

To address the environmental risks posed by large-scale livestock manure generation and limitations of current resource recovery methods, such as prolonged processing durations and high energy demand, this study developed an artificial humification process utilizing a CaO-activated persulfate (PS) system, which efficiently converts livestock manure into humus-rich products while achieving effective pollution control. Under optimized conditions involving the addition of 3.4 wt% PS and 6 wt% CaO, followed by a 40-minute treatment period, the humic acid (HA) and fulvic acid (FA) contents in the processed chicken manure reached 19.94% and 16.24%, respectively. Mechanistic analysis revealed that sulfate radical (SO₄·^-) and hydroxyl radical (·OH) drive the humification process through degradation-polymerization pathways, involving reactions such as oxygenation, deamination, and Maillard-type processes. The PS/CaO system enabled simultaneous removal of antibiotic resistance genes and pathogens, as well as immobilization of heavy metals. When applied to potted wheat, PS/CaO-treated chicken manure significantly increased plant fresh weight by up to 77.96% compared to the control group, while also improving acidic soil conditions, as evidenced by an increase in soil pH from 5.75 to 7.27. Life cycle assessment validated the improved environmental compatibility of this method compared to conventional technologies. Overall, this work achieves concurrent environmental and agricultural benefits through a single, integrated approach.