Anaerobic Fermentation for Ceftriaxone Sodium Degradation in Excess Sludge: pH-Dependent Performance, Metabolite Formation, and Microbial Community Dynamics

The accumulation of ceftriaxone sodium (CTX), a third-generation cephalosporin antibiotic, in wastewater and sludge poses significant environmental and health risks, necessitating effective degradation strategies. This study investigated anaerobic fermentation of excess sludge (12,000-14,000 mg/L) spiked with 15 mg/L CTX under varying pH conditions (4, 7, 10, 12) to evaluate sludge reduction, metabolite formation, and microbial community dynamics. Results demonstrated that pH 10 yielded optimal performance, achieving a 62.09% sludge reduction rate, 129.35 mg/L NH₄⁺-N release, and 1,485.84 mg/L volatile fatty acid (VFA) production, alongside efficient CTX degradation via hydrolysis and deamination pathways. Microbial analysis revealed dominant phyla (Proteobacteria, Bacteroidota, Chloroflexi) and genera (Ellin6067, Caldilinea) under pH 4-10, while extreme alkalinity (pH 12) favored Firmicutes but reduced functional diversity. The findings highlight pH 10 as the optimal condition for balancing CTX removal, sludge reduction, and resource recovery, offering a practical pretreatment approach for antibiotic-laden sludge in wastewater treatment.