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.