Deciphering the response of biological nitrogen removal to gadolinium and sulfamethoxazole combined pollution: Performance, microbial community, and antibiotic resistance genes

摘要

Magnetic resonance imaging detection and the clinical treatment of bacterial infections in hospitals cause gadolinium and antibiotics to enter wastewater treatment plants (WWTPs). However, there remains missing information regarding the combined pollution of gadolinium and antibiotics in WWTPs. In this study, 50 mu g/L of gadolinium (Gd(III)) and 500 mu g/L of sulfamethoxazole (SMX) are selected to study their effects on the biological nitrogen removal performance, the microbial community structure, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs). The results demonstrated that Gd(III) and SMX combined pollution had an evident effect on denitrification, and elevated the abundance of ARGs by the increasing the abundance of intl1 in the MGEs. Moreover, Gd(III) inhibited the denitrification and decreased the abundance of ARGs. The distance heatmap showed that the typical nitrogen removal genes had a negative correlation with ARGs. This study highlights the effects of Gd(III) and SMX, both alone and coexisting, on nitrogen removal mechanisms, as well as the fate of ARGs and MGEs.

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