Far-UVC-activated calcium peroxide facilitates simultaneous antibiotic removal and carbon recovery from waste...

Antibiotic residues in waste activated sludge (WAS) require effective removal to reduce ecological risks and improve the safety of sludge resource recovery. This study evaluated 222 nm far-UVC-activated calcium peroxide (CaO₂) pretreatment for simultaneous antibiotic removal and carbon recovery from WAS, using sulfamethoxazole (SMX) as a model antibiotic. Far-UVC and CaO₂ exhibited a synergistic effect, achieving 80% apparent SMX removal within 240 min at a CaO₂ dosage of 0.1 g/g TS. Mechanistically, continuous CaO₂ hydrolysis induced sludge disintegration and alkalization (pH = 9.55). This dual-action not only co-released the entrapped SMX and endogenous dissolved organic matter (DOM) into the aqueous phase but also shifted SMX toward its highly photo- and radical-susceptible deprotonated state. Consequently, efficient far-UVC photolysis of slowly released H₂O₂ and DOM-mediated sensitization unlocked an abundant reactive species cascade (dominated by HO• and ¹O₂), which efficiently degraded SMX and its intermediates to minimize potential ecological risks. From a practical standpoint, the process effectively buffered complex matrix interferences, degrading 13 indigenous multi-class antibiotics in real sludge (with removal efficiencies of up to 89%) while yielding a 1.4-fold increase in energy efficiency compared to far-UVC alone. Furthermore, far-UVC/CaO₂ enhanced WAS solubilization and subsequent anaerobic fermentation, increasing volatile fatty acids (VFAs) production to 3.8 times that of the control. Metagenomic profiling indicated enrichment of hydrolytic and acidogenic microbial populations and functional genes related to substrate hydrolysis and VFA formation, supporting enhanced carbon recovery from antibiotic-containing WAS.