Simultaneous elimination of antibiotics resistance genes and dissolved organic matter in treatment wetlands: Characteristics and associated relationship

Abstract Constructed wetlands (CWs) are widely used for treating swine wastewater containing antibiotic resistance genes (ARGs). However, the relation between ARGs removal and dissolved organic matter (DOM) characteristics in CWs remains unknown. This study aimed to assess the removal of ARGs and the dynamitic transformation of DOM from anaerobically-digested swine wastewater in biochar-based CWs with and without forced aeration. Incorporating biochar and aeration into CWs could promote the ARGs (tetA, tetM, tetO, tetW) elimination (0.53–2.14 log) under various influent strengths. Compared with non-aerated CWs, aerated CWs improved the target ARGs removal, while biochar-based CWs without aeration increased the proliferation of ARGs (tetA, tetO, tetW). More accumulation of ARGs was found especially in non-aerated CWs with biochar. Fluorescence excitation-emission spectrophotometry with parallel factor analysis revealed that DOM, mainly including humic-like, protein-like and tryptophan-like components, was significantly reduced with a higher removal efficiency (72.2%) in biochar-based CWs with aeration. Moreover, DOM removal showed an obvious correlation with the elimination of ARGs, except tetW, which might not be influenced by the humification processes. The evolution of microbial communities in different CWs indicated that Actinobacteria, Proteobacteria and Bacteroidetes might play an important role in ARGs and DOM removal. This study could provide new insights on the mechanism of ARGs and DOM elimination by biochar-based CWs with aeration for treating swine wastewater.