Cladophora can mitigate the shock of glyphosate-containing wastewater on constructed wetlands coupled with microbial fuel cells. (December 2022) - Xu, Fei
Abstract: This study investigated the performance of constructed wetlands coupled with microbial fuel cells (CW-MFCs) treating agricultural wastewater containing glyphosate ( N -phosphonomethyl glycine, PMG), and the use of Cladophora as a cathode plant in this system. Ten devices were divided into Cladophora groups (CGs) and no Cladophora groups (NGs), with five PMG concentrations (0, 10, 25, 50, and 100 mg/L). PMG removal efficiency significantly decreased with increasing PMG ( P < 0.01 ) and was higher in CG devices than in NG devices at low PMG concentrations (<50 mg/L). The removal efficiency of chemical oxygen demand (COD) and NH 4 + in CGs was significantly higher than in NGs ( P < 0.01 ). The highest power densities of 6.37 (CGs) and 6.26 mW/m 2 (NGs) were obtained at 50 mg/L PMG, and the average voltage was significantly higher in CGs than in NGs ( p < 0.01 ). Moreover, PMG had a negative effect on the enrichment of electrochemically active bacteria, but Cladophora could mitigate this effect. The abundance of the resistance gene epsps was stabilized; The phnJ gene increased with increasing PMG in NGs and was downregulated at high PMG concentration in CGs, indicating better microbial adaptation to PMG in CGs throughout the experiment. Graphical abstract: Image 1 Highlights: The increase in C, N, and P from PMG affected wastewater treatment efficiency. Cladophora contributed to bioelectricity generation and water purification in CW-MFCs. Relative abundance of EAB was apparently promoted in the presence of Cladophora. Resistance genes were upregulated in NGs but decreased in CGs with increasing PMG.