Eco electrogenic integrated systems for sustainable bioremediation of textile dye wastewater

Abstract

One of the major concerns of environmental pollution is the release of harmful untreated and recalcitrant textile dye polluted wastewater into the pure aquatic ecosystems. One of the credible methods for resolving this issue is the bioelectrochemical systems (BES), the application of which offers energy-effective remediation of textile dye wastewater. One of the well-studied BESs for the effective treatment of textile dye wastewater is the microbial fuel cell (MFC). The MFC system, along with its advantages, comes with its fair share of limitations, like the use of expensive proton exchange membranes (PEM). Integration of MFC system with another treatment system such as constructed wetland (CW) can ease the limitations of both the technologies in the standalone operation. The current study involved the eco-electrogenic treatment of textile dye wastewater in CW-MFC along with the characterization of electrode-enriched microbial community structures in the lab-scale and pilot-scale systems. Lab scale CW-MFC system planted with Fimbristylis dichotoma reduced chemical oxygen demand (COD) by 70 ± 2% and American Dye Manufacturer s Institute (ADMI) colour index by 82.2 ± 1.7% of textile dye wastewater in closed-circuit condition. The COD and ADMI reduction were found to be 7.4% and 9% higher as compared to standalone constructed wetland (CW) system respectively. Similarly, the lab-scale CW-MFC system accomplished maximum power density of 198.8 mW/m2, which was 85.6 ± 2.47% greater than control system. Treatment of textile dye wastewater in the CW-MFC system decrease the oxidative stress to the Oreochromis niloticus as revealed Quantitative reverse transcription PCR (qRT-PCR). The textile dye wastewater degradation and bioelectricity generation is very much dependent on the bacteria enriched at the electrode regions of CW-MFC system. Therefore, to evaluate the effect of bioaugmentation of pre-enriched bacterial in the pilot-scale CW-MFC system, bacterial community DC5 enriched in the textile dye wastewater from dye poll