Bioremediation of textile dyeing industry effluent from small-scale industries using a microbial consortium of Bacillus sp., Escherichia coli, and Aspergillus niger

Dyes are the visible contaminants that are released from the textile industries. Decontamination of textile dye effluents using microbes is environmentally viable over chemical, physical and other mechanical methods. Bacteria, fungi, yeast, and algae have synergistic metabolic activities that alter the chromogen and degrade the absorbed dye color. This work was aimed at investigating the dye decolorization potential of a mixed microbial culture (MMC) obtained from different soil and sludge samples. A single dye (Direct Blue 53) was used for comparison studies. The MMC were incubated for 9 days in mineral salt medium with dye and the absorbance of its filtrate at 647 nm (Blue dye) and 308 nm (Industrial dye) was noted down for every 22 h. The color removal efficiency (CRE) by MMC were 47.04%, 46.77%, 45.21%, and 35.02% for soil of textile dyeing unit (DS), sludge from STP (SE) soil (SS) from drying bed of STP and sludge from membrane reactor of dyeing unit (DE) respectively. Further, the maximum CRE of 98.35% was recorded by microbial culture from drying bed soil of STP (SS), followed by microbial culture from STP sludge (SE) was 97.96%, textile dyeing unit soil (DS) of 96.99%, and sludge form membrane reactor of dyeing unit (DE) was 96%. Bacillus sp. isolated from eco-bio block was tested against the blue dye and gave color removal of about 89.25%. The study concluded that the microbe present in soil obtained from the dyeing unit is naturally acclimatized to the dye waste and hence shows highest dye removal efficiency.