Eco-electrogenic treatment of dyestuff wastewater using constructed wetland-microbial fuel cell system with an evaluation of electrode-enriched microbial community structures

[Display omitted] •CW-MFC-2 was more efficient than standalone CW for treatment of dyestuff wastewater.•Dyes present in wastewater increased the eco-electricity output in CW-MFC-2 system.•Anodic microbial community of CW-MFC-2 system was dominated by Desulfobulbus genus.•Treated wastewater reduced oxidative stress response gene expression in tilapia. This work studied eco-electrogenic treatment of real dyestuff wastewater along with characterization of electrode-enriched microbial community structures in Fimbristylis dichotoma planted closed-circuit constructed wetland-microbial fuel cell (CW-MFC) system. The CW-MFC-2 (experimental system) achieved 82.2 ± 1.7% ADMI removal and 70 ± 2% COD reduction; that were found to be 9% and 7.4% higher than the standalone constructed wetland (CW) system (bioremediation control) respectively. Likewise, the CW-MFC-2 system achieved maximum power density of 198.8 mW/m2, which was 85.6 ± 2.47% higher than the CW-MFC-1 system (eco-electricity control). Quantitative reverse transcription PCR (qRT-PCR) assays revealed significant down-regulation of hepatic oxidative stress response biomarker genes in Oreochromis niloticus exposed to CW-MFC-2 system treated dyestuff wastewater as compared with untreated wastewater. The biofilms associated with the anode and cathode of the CW-MFC-2 system exhibited selective enrichment of electrochemically active and dye degrading microbial communities.