Influence of chlortetracycline as an antibiotic residue on nitrous oxide emissions from wastewater treatment

Strengthening the removal of antibiotics in wastewater treatment plants is a research focus, but whether antibiotics affect nitrous oxide (N2O) emissions from wastewater treatment remains to be determined. In this study, the effect of chlortetracycline (CTC) on N2O emissions in anaerobic/oxic/anoxic sequential batch reactors was investigated. Experimental results show that CTC promotes N2O emissions during biological nutrient removal. The addition of 0.1 mg/L CTC increased the N2O emission factor by 41.4% compared to the control. Mechanism exploration shows that CTC stimulates the release of extracellular polymeric substance (EPS) and binds to it, the generated EPS-CTC conjugates hinder or expand the mass transfer channel, which intensifies the electronic competition between oxidoreductases and the substrate competition between microorganisms, resulting in incomplete denitrification and nitrite accumulation, thereby increasing N2O emissions.