Applications of a bacterial consortium in biological treatment of RR120 and textile dye effluents

The sustainable approaches for bioremediation of dyes have attracted the attention of researchers due to their safety. However, the biologically treated samples pose problems with their disposal as a result of their huge quantity and possible ecotoxicity. In the current study, the efficacy of pre-grown cell mass and immobilized cells of bacterial consortium, named as RAR, were evaluated for biological treatment of dyes and textile effluent. The efficiency of treatment was determined based on the BOD, COD and TOC of the effluent samples. The free cells of consortium RAR could decolorize RR120 in 2.25h. The pre-grown cell mass decolorized 25 continuous batches of 50ppm RR120 dye rapidly. Among the two matrices used for immobilization (agar and alginate), the cells immobilized in 6% Ca-alginate matrix showed better efficiency for decolorization of RR120 (~85%; 6 batches) and textile effluent (~88%; 6 batches) with a retention time of 6h. The decolorized samples, treated using above methods, were further tested for their effect on survival, growth and/or phenotypic characteristics of various biological indicators of toxicity. The treated samples supported seed germination, propagation of daphnia, bioluminescence activity and antibiotic production by agriculturally important bacteria indicating the effective degradation of textile effluents into non-toxic end products. Hence, the techniques suggested in this study may be efficiently improvised for safe and effective biological treatment of textile effluents on a larger scale.