Approach to Biological Treatment of Tannery Effluent in Bangladesh

Dyes are the most important group of synthetic colorants. They are generally considered as xenobiotic compounds which are very recalcitrant to biodegradation. Some dyes and some of their N-substituted aromatic bio-transformation products are toxic and/or carcinogenic and therefore these dyes are considered to be environmental pollutants and health hazards. In comparison with chemical treatment of dye containing tannery effluent, biological treatment is considered to be the most economical and efficient. In this work, attempts were made to degrade these dyes aerobically and anaerobically. The organisms which were efficient in degrading the dyes are isolated from different sections of tannery wastewater treatment plant. They are identified and characterized by analyzing their morphological, cultural and biochemical features. Then the efficiency of dye degradation by individual microorganism and by consortium was analyzed in presence of various co-substrates and under various environmental factors. It was found that mixed cultures of bacteria(consortia)from tannery effluent worked efficiently in degrading the dye whereas fungal consortia was not so efficient than a single strain.