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Complete biodegradation of azo dye in an integrated microbial fuel cell-aerobic system using novel bacterial consortium

Das, A., Mishra, S.
International journal of environmental science and technology 2019 v.16 no.2 pp. 1069-1078
Fourier transform infrared spectroscopy, azo dyes, biodegradation, decolorization, effluents, fuels, gas chromatography-mass spectrometry, inoculum, microbial fuel cells, phototoxicity, toxic substances, ultraviolet-visible spectroscopy
In the present work, a commercially used azo dye Remazol navy blue was completely degraded into less toxic intermediates in an integrated microbial fuel cell-aerobic system. A novel defined bacterial consortium comprising of organisms isolated from dye contaminated wastewater has been used as inoculum for this study. As compared to the traditional static incubation method, a rapid decolorization of Remazol navy blue was noticed in the anodic chamber of microbial fuel cell. In low to moderate dye concentrations (25–100 mg/L), almost complete decolorization of Remazol navy blue was achieved within 12 h of microbial fuel cell operation. The first-order kinetic constant of Remazol navy blue decolorization (k) in microbial fuel cell was found to be considerably higher than that of static incubation condition (Kₛₜₐₜᵢc (0.3041) < KMFC (0.5697)). Microbial fuel cells external resistance is found to be a key parameter affecting the reductive decolorization of Remazol navy blue dye with a resistance of 1000 Ω as the optimum giving maximum efficiency. Dye degradation products from each stage of the integrated microbial fuel cell-aerobic system have been analyzed through different analytical techniques such as UV–Vis spectroscopy, Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry analysis. These studies illustrate the reductive degradation of Remazol navy blue in microbial fuel cell treatment stage into different toxic intermediates which were further degraded into simpler compounds in the successive aerobic treatment stage. Phototoxicity study confirms the less toxic nature of the treated effluents as compared to the parent dye.