This study was to investigate the mineralization of wastewater containing methyl orange (MO) in integrated anaerobic-aerobic biofilm reactor with coconut fiber as bio-material. Different aeration periods (3h in phase 1 and 2; 3, 6 and 15 h in phase 3; 24 h in phase 4 and 5) in aerobic chamber were studied with different MO concentration 50, 100, 200, 200 and 300 mg/L as influent from phase 1-5. The color removals estimated from the standard curve of dye versus optical density at its maximum absorption wavelength were 97%, 96%, 97%, 97%, and 96% and COD removals were 75%, 72%, 63%, 81%, and 73% in phase 1-5, respectively. The MO decolorization and COD degradation followed first-order kinetic model and second-order kinetic model, respectively. GC-MS analysis indicated the symmetrical cleavage of azo bond and the reduction in aromatic peak ensured the partial mineralization of MO.
Microbial fuel cells (MFCs) represent an emerging technology that focuses on power generation and effluent treatment. This review compiles articles related to MFCs using azo dye as the substrate. The significance of the general components in MFCs and systems of MFCs treating azo dye is depicted in this review. In addition, degradation of azo dyes such as Congo red, methyl orange, active brilliant red X-3B, amaranth, reactive blue 221, and acid orange 7 in MFCs are summarized. Further exploration and operational modification are suggested to address the challenges of complete removal of azo dye with maximum power generation in an MFC. In addition, a sequential treatment system with MFCs is suggested for complete mineralization of azo dye.