Reduction in phytotoxicity of a textile wastewater against Vigna radiata using Citrobacter sp. M41 in a bioaugmented packed bed column bioreactor

The current research was carried out to devise a biological strategy to remediate dyes and metal ions from textile wastewater. For this purpose, Citrobacter sp. M41 was isolated from a textile wastewater sample. This strain efficiently decolorized > 90 % of the added reactive black-5 (RB5) dye using yeast extract as a C source at 8.5 pH and 30 degrees C in mineral salt medium containing a mixture of metals (Pb2+, Ni2+ and Cd2+). Moreover, M41 showed > 90 % decolorization of RB5 beside > 80 % concurrent removal of hexavalent Chromium [Cr(VI)]. Furthermore, the granulated corncob and its biochar bioaugmented with M41 and filled within packed bed column based bioreactors efficiently (>90 %) removed the RB5 and Cr(VI) from a textile wastewater. The M41 bioaugmented corncob biochar resulted into a 60.8 %, 57.8 % and 68.7 % decrease in chemical oxygen demand (COD), electrical conductivity (EC) and total dissolved solids (TDS) of the wastewater, respectively. A phytotoxicity study conducted by using mung bean (Vigna radiata) as a test crop indicated that the treated synthetic wastewater was relatively less toxic as compared with the untreated wastewater. Therefore, it can be concluded that Citrobater sp. M41 is an important bio-resource for treatment of textile effluent polluted with azo dyes and Cr(VI).