Investigation of enhanced biological dye removal of colored wastewater in a lab-scale biological activated carbon process

Abstract

In this study, the influence of bacteria and activated carbon adjacent was investigated on treatment and decolorization of synthetic wastewater in a Biological Activated Carbon process. Pseudomonas putida was selected as a bacterial strain capable of degrading aromatic compounds and Acid Blue 92 was used as model azo dye. The optimum conditions for environmental factors affecting decolorization of azo dye was achieved from series of batch experiments. At 25 °C and pH7 the highest efficiency was obtained. At concentration of 20 mg L−1 in batch process, more than 90 % of Acid Blue 92 was reduced in color within just 3 h under optimum conditions. Dual-beam UV–Visible spectrometry and plate assay confirmed biodegradation of the dye by P.putida. The optimum values were then used for continues process. It was found that flow rate and thereby retention time has a critical role in biofilter efficiency. A lab-scale submerged downflow GAC column was sustained by bacterial strain to form the biofilter. About 70 % decolorization was obtained in continuous biological activated carbon process within 2 h with 60 mL h−1 flow rate while adsorption of dye reached the equilibrium and no further dye removal observed. Our results suggest the potential use of P. putida in azo dye decolorization. The combination of activated carbon adsorption and biodegradation by bacterial strains capable of degrading xenobiotic proved to be a promising technique for treatment of dye-contaminated wastewater.