Characterization of microbial community and resistance gene (CzcA) shifts in up-flow constructed wetlands-microbial fuel cell treating 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 < 0.05). The microbial community structure showed that the Zn (II) significantly reduced the abundance of some functional genus (p < 0.05), such as Ochrobactrum, Nitrosomonas, Pseudomonas and Dechloromonas. Zn (II) inhibited the microbial richness in the anode, but it played a positive role in the cathode. Anew, the expression of the CzcA in the CW-MFC was promoted by Zn (II), particularly in the cathode.