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

Mitigating antibiotics during struvite (MgNH 4 PO 4 ·6H 2 O) 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 (•SO 4 - 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.