Distinct performance and mechanism of microbial fuel cells-constructed wetland and direct-enchanced constructed wetland for levofloxacin removal

Abstract

There is an urgent need to investigate the distinct performance and mechanism of traditional constructed wetland (CW), microbial fuel cells-constructed wetland (MFC-CW) and direct-enchanced constructed wetland (ECCW) for antibiotics removal. To address this issues, three kinds of CWs were bulit and distinct performance and mechanism for levofloxacin (LVFX) removal was expored in this study. MFCCW, ECCW achieved high LVFX removal efficiencies compared with traditional constructed wetland (96.0 % in MFCCW, 95.0 % in ECCW and 91.2 % in CW) and the biodegradation was the key contributor (90.7 %-95.3 %). MFCCW is better capable to stimulate microbial activity and strengthen the removal effect of LVFX. MFCCW performed well in reducing the effluent's ecotoxicity (dehydrogenase activity) and antibiotic resistance genes (ARGs). ARGs were mainly distributed in the anode region of MFCCW while accumulating in the cathode region of ECCW. Atribacteria, Chlorobi, Synergistetes and Firmicutes significicant effect on the efficiencies of TN, NH₄⁺, and LVFX. The core node for microbial community interaction in CW was only Pseudomonas in Proteobacteria (OTU4537). While MFCCW included Opitutae_vadinHA64 (OTU3153) in Verrucomicrobia, Desulfomicrobium (OTU3629) in Proteobacteria, and Actinobacteria Gaiellales (OTU4206), and ECCW included Mesotoga (OTU1104) in Thermotogae, Syntrophus (OTU3207) in Proteobacteria and Emticicia (OTU3788) in Bacteroidetes. MFCCW and ECCW increased the abundance of critical microbial communities, and the microbial communities were more closely related. This study improved the understanding of the molecular mechanisms underlying the enhancement of CW by the two bioelectrochemical methods.