Bacterial Bioremediation of Textile Azo Dyes – A Review

ABSTRACT Textile industries consume a considerable amount of water in their manufacturing processes. Considering both the volume and the effluent composition, the textile industry is rated as the most polluting among the industrial sectors. Important pollutants in textile effluents are mainly recalcitrant organics, dyes, toxicants, inhibitory compounds, surfactants, chlorinated compounds and salts. Improper textile effluent disposal into the aquatic systems affects the aesthetic merit, water transparency and gas solubility of the water bodies leading to the reduction in sunlight penetration which in turn, decreases the photosynthetic activity, reduces dissolved oxygen concentration, depicts toxic ef-fect on aquatic flora and fauna. In addition, many synthetic azo dyes and their metabolites are toxic, carcinogenic and mu-tagenic leading to potential health hazards to the mankind. Therefore treatment of industrial effluent containing aromatic compounds becomes necessary prior to their final discharge into the environment. Physico-chemical methods have major limitations such as economically unfeasible, unable to remove the recalcitrant azo dyes and their metabolites, involves complicated procedures, more energy consumption and chemical usage. Whereas biodecolorization has been proposed as eco-friendly, generates less sludge and less expensive