Mitigating tetracyclines in struvite recovery from swine wastewater by respectively applying unactivated and activated peroxymonosulfate oxidation.

Mitigating antibiotics during struvite (MgNH4PO4·6H2O) recovery from swine wastewater is critical to preventing the spread of antibiotic resistance. In this study, unactivated peroxymonosulfate (PMS) and ultraviolet activated peroxymonosulfate (UV/PMS) oxidations were employed to degrade tetracyclines (TCs) during struvite recovery by using synthetic and real wastewaters, respectively. Results demonstrated that UV/PMS possessed higher TCs removal efficiency (93.72 %-96.74 %) in synthetic wastewater than PMS. Unexpectedly, the unactivated PMS process showed higher efficiency (54.58 %-64.92 %) than the radical-based UV/PMS process (51.35 %-61.72 %) in real wastewater, leading to lower TCs residue in recovered struvite. This unexpected result can be attributed to the abundant dissolved organic matters (DOM) in real wastewater acting as a scavenger for radicals (•SO4- and •HO), thereby inhibiting the UV/PMS system. Nevertheless, the non-radical PMS pathway selectively targeted electron-rich lipid-like and protein DOM components that preferentially complex with TCs, as revealed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Furthermore, fractionated DOM with different molecular weight cut-offs confirmed the targeted attack occurred in the high molecular weight DOM (FDOM1) with electron-rich fraction where TCs were concentrated. This study elucidated the critical role of DOM in different oxidation pathways and highlights that non-radical mechanisms represent a more selective and effective approach for pollutant degradation in DOM-rich environments, providing a novel strategy for safer nutrient recovery.