Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Microbiology

In the present study two different types of synthetic dyes were tested. These dyes were Brilliant Blue R-250(triphenylmethane class) and Congo Red (azo class). Based on the preliminary experimental results Congo Red was chosen as a model synthetic dye to be decolorized and/or degraded by microorganisms. Congo red is a synthetic azo-dye with many industrial applications. The effluents containing azo dyes cause several environmental hazards and thus should be treated prior to their discharge. The present work investigates the possible use of a novel microbial consortium from sheep compost for the decolorization of Congo red dye. The effect of different parameters including temperature, aeration, accumulative dye loading, inoculum concentration, dye concentration and contact time on dye decolorization were investigated. It was observed that 30{u00B0}C was the best incubation temperature for CR decolorization. Also, the results revealed that in the presence of oxygen the microorganisms cannot degrade the dye. Three microbial consortia were used and it was noticed that more than 75% of Congo red (25 mg/L) was decolorized by Mix. No.3 and mix. No. 2 but only 13% for mix. No. 1 at an inoculum rate of 2.5% (v/v). The decolorization efficiency of mix. No. 3 decreased from 95% to 62% when the dye concentration increased from 100 to 500mg/L while for mix. No. 2 and mix. No. 1, it decreased from71% to 33% and from 26% to 14%, respectively. The maximum decolorization for 500 mg/L Congo Red by mix. No. 3 was about 98% after24 h incubation) while the time required for the maximum decolorization for mix. No. 2 and mix. No. 1 was increased to 78h.The kinetic results suggested that the decolorization of Congo red by the studied consortium follows the first order kinetic model

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