Anaerobic co-metabolic degradation of ceftriaxone sodium: Performance and mechanism

Ceftriaxone sodium (CTX) is a typical β-lactam antibiotic in pharmaceutical wastewater. Although traditional biological treatments are low-cost and eco-friendly, antibiotics usually inhibit microorganisms, resulting in limited treatment performance. The biological co-metabolism process provides carbon sources and energy for microorganisms through co-substrate addition, thereby producing enzymes or cofactors to enhance the degradation of refractory pollutants. Therefore, the present study aimed to investigate the degradation performance of CTX through anaerobic biological co-metabolism. A simple co-metabolic substrate (i.e., glucose, 80 mg L−1) was added into an anaerobic-activated sludge system, and its mechanism was explored in terms of the variations in extracellular polymeric substances, microbial structure, and resistance genes. Additionally, the possible degradation pathways of CTX were described. The results showed that the degradation efficiency of CTX (200 mg L−1) was only about 35% within 8 h in the control group, while it increased to 67.6% in the experimental group with glucose. Chloroflexi, Actinobacteria, Bacteroidetes ADurb.Bin123, and Bacteroidales were the predominant bacterial species in the system. Additionally, the types of enzymes and the relative abundance of β-lactam resistance genes in the co-metabolic system significantly increased by 7 and 0.77%, respectively. Furthermore, nine primary anaerobic CTX biodegradation products were detected, indicating the existence of three possible degradation pathways. Overall, the study results provide a novel approach to treating CTX-containing wastewater.