The release of wastewater from textile dyeing industrial sectors is a huge concern with regard to pollution as the treatment of these waters is truly a challenging process. Hence, this study investigates the triazo bond Direct Blue 71 (DB71) dye decolorization and degradation dye by a mixed bacterial culture in the deficiency source of carbon and nitrogen. The metagenomics analysis found that the microbial community consists of a major bacterial group of Acinetobacter (30%), Comamonas (11%), Aeromonadaceae (10%), Pseudomonas (10%), Flavobacterium (8%), Porphyromonadaceae (6%), and Enterobacteriaceae (4%). The richest phylum includes Proteobacteria (78.61%), followed by Bacteroidetes (14.48%) and Firmicutes (3.08%). The decolorization process optimization was effectively done by using response surface methodology (RSM) and artificial neural network (ANN). The experimental variables of dye concentration, yeast extract, and pH show a significant effect on DB71 dye decolorization percentage. Over a comparative scale, the ANN model has higher prediction and accuracy in the fitness compared to the RSM model proven by approximated R2 and AAD values. The results acquired signify an efficient decolorization of DB71 dye by a mixed bacterial culture.
Pilot-scale constructed wetlands planted with Scirpus grossus, were used to investigate the effects of applying a three-rhizobacterial consortium (Bacillus cereus strain NII, Bacillus subtilis strain NII and Brevibacterium sp. strain NII) on the growth of S. grossus and also on the accumulation of iron (Fe) and aluminium (Al) in S. grossus. The experiment includes constructed wetlands with the addition of 2% of the consortium rhizobacteria and without the consortium rhizobacteria addition (acting as control). During each sampling day (0, 5, 10, 15, 20, 25, 30, 42, 72 and 102), plant height, concentration of Fe and Al and sand microbial community were investigated. The results for the constructed wetland with the addition of consortium rhizobacteria showed the growth of S. grossus increased significantly at 26% and 29% for plant height and dry weight, respectively. While the accumulation of Fe and Al in S. grossus were enhanced about 48% and 19% respectively. To conclude, the addition of the rhizobacteria consortium has enhanced both the growth of S. grossus and the metal accumulation. These results suggesting that rhizobacteria has good potential to restore Fe and Al contaminated water in general and particularly for mining wastewater.