Simultaneous removal of antibiotics and recovery of phosphate in urine by ferrate(VI)-peracetic acid: The critical role of iron species

Efficient treatment technologies for recovering phosphorus from human urine while simultaneously eliminating antibiotics are crucial due to the potential threats posed by co-existing antibiotics to public health and water quality. Herein, we systematically investigated the application and underlying mechanism of peracetic acid (PAA) and ferrate(VI) for urine treatment. The PAA-Fe(VI) system retained its rapidity and efficacy in degrading antibiotics in hydrolyzed urine. The results showed a strong selectivity of the PAA-Fe(VI) system towards contaminants with electron-rich moieties. The reactive iron species (Fe(V)/Fe(IV)) played a significant role in sulfamethoxazole (SMX) degradation by PAA-Fe(VI). Theoretical calculations revealed a preference for coordination between reactive iron species and O1 of PAA. The coordination led to a reduction in the energy gap compared to free iron, suggesting an enhancement in the stability and oxidation capacity of reactive iron species facilitated by PAA. Furthermore, toxicity analysis revealed a notable decrease in the toxicity of degradation products following treatment with the PAA-Fe(VI) process. Elemental analysis confirmed successful phosphorus loading onto the precipitation, primarily attributed to adsorptive interactions with in-situ formed Fe(III). Overall, this study presents a novel strategy for simultaneously eliminating antibiotics and recovering phosphorus resources from urine, thereby expanding the practical application of the PAA-Fe(VI) system in urine treatment.