Science and Education Publishing International Journal of Environmental Bioremediation & Biodegradation 2 3 2014 05 08 Microbial Decolorization and Degradation of Remazol Black & Mordant Orange by Microbial Consortia Isolated from Common Effluent Treatment Plant 117 124 EN Maulin P Shah Industrial Waste Water Research Laboratory, Division of Applied & Environmental Microbiology, Enviro Technology Limited, Ankleshwar, Gujarat, India Kavita A Patel IJEBB2014234 10.12691/ijebb-2-3-4 2013 12 30 2014 05 08 2014 05 08 Azo dyes are xenobiotic and recalcitrant against biodegradation, causing environmental problems. Under certain environmental conditions, microorganisms can transform dyes to non-coloured products or completely mineralize them. In the present study, the first attempt on dye decolourisation potentials of local microbial consortia isolated from dye contaminated soils in common effluent treatment plant were determined against two azo dyes. Decolourisation rate and kinetics were monitored by spectrophotometry under different conditions. Effect of process parameters: pH, dye concentration and inoculums size on dye decolourisation rate was optimised using the full factorial design. Microbial growth and decolourisation rate were higher in shaking than static conditions. The bacterial consortium gave highest decolourisation of 91.86% for Remazol Black and 93.75% for Mordant Orange within 48 hours in shaking cultures; 57.78% and 62.06% respectively after 48 hours under static condition, followed by the mixed and fungal consortium. Kinetics studies revealed the bacteria consortia had highest tendency towards decolourisation, with a greater half live value for Remazol Black (13.97 hours) than for Mordant Orange (10 hours). pH out of the range 7.2-8 and dye concentrations above 100mg/l reduced decolourisation rate by the bacteria consortia while increasing inoculums size increased it. Optimum decolourisation was achieved when pH and dye concentrations were kept low while the inoculums size was high.