Evaluation of integrated anaerobic–aerobic biofilm reactor for degradation of azo dye methyl orange

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 (3 h 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.