Characterization of microbial community and resistance gene (CzcA) shifts in up-flow constructed wetlands-microbial fuel cell treating Zn (II) contaminated wastewater

[Display omitted] •First report on Zn (II) containing wastewater treatment in a CW-MFC.•The expression of CzcA increased with increasing Zn (II) concentration.•Proteobacteria was the dominant host bacteria of CzcA gene.•Microorganisms exerted anti-stress effects to Zn (II) contaminated wastewater. The main aim of this work was to characterize the microbial community structure and resistance gene (CzcA) shifts in up-flow constructed wetlands-microbial fuel cell (CW-MFC) treating Zn (II) contaminated wastewater. Two CW-MFC devices were operated, i.e. the experimental group (EG) treating Zn (II) wastewater, and the control group (CG) treating Zn (II)-free wastewater. The results showed the CW-MFC combination exhibited good removal efficiency on Zn (II), while the average voltage, the power density and the removal rates (TP, TN, NH4+-N and COD) significantly reduced (p