An electrochemical membrane biofilm reactor for removing sulfonamides from wastewater and suppressing antibiotic resistance development: Performance and mechanisms.

Sulfonamides, such as sulfadiazine (SDZ), are frequently detected in water and wastewater with their toxic and persistent nature arousing much concern. In this work, a novel electrochemical membrane biofilm reactor (EMBfR) was constructed for the removal of SDZ whilst suppressing the development of antibiotic resistance genes (ARGs). Results showed that the EMBfR achieved 94.9% removal of SDZ, significantly higher than that of a control membrane biofilm reactor (MBfR) without electric field applied (44.3%) or an electrolytic reactor without biofilm (77.3%). Moreover, the relative abundance of ARGs in the EMBfR was only 32.0% of that in MBfR, suggesting that the production of ARGs was significantly suppressed in the EMBfR. The underlying mechanisms relate to (i) the change of the microbial community structure in the presence of the electric field, leading to the enrichment of potential aromatic-degrading microorganisms (e.g., Rhodococcus accounting for 51.0% of the total in the EMBfR compared to 10.0% in the MBfR) and (ii) the unique degradation pathway of SDZ in the EMBfR attributed to the synergistic effect between the electrochemical and biological processes. Our study highlights the benefits of EMBfR in removing pharmaceuticals from contaminated waters and suppressing the development (and transfer) of ARGs in the environment.