Cr+6 REMOVAL BY INDIGENOUS BACTERIA IN CONJUNCTION WITH DIFFERENT BIOWASTE MATERIALS: AN ECOFRIENDLY APPROACH

Abstract

Two Cr+6 reducing bacterial strains previously isolated from tannery effluents were used in the present study and identified as Pseudomonas aeruginosa Rb-1 and Ochrobacterum intermedium (Rb-2) by 16S rRNA sequencing. Different biowaste materials (waste tea leaves, carrot juice pulp, dry leaves of eucalyptus and rice husk) were assessed for sorption / removal of Cr +6 from aqueous solution of K 2 Cr 2 O 4 . Feasibility of mono and mixed cultures of indigenous bacterial strains was evaluated for Cr +6 removal in conjunction with different biowaste materials. Among all tested biowastes materials, waste tea leaves showed optimum removal of Cr +6 from metal solution alone (77.1%) as well as in combination with bacterial strains (99.4%) after 720 minutes of contact time. Mixed culture of bacterial strains was found to be more efficient in Cr +6 removal than monoculture. The contact time of 720 minutes, pH 7, biomass concentration of 2.5 gram 100 mL -1 , 37˚C and shaking speed of 100 rpm were found to be most optimum for optimum Cr +6 sorption alone as well as in combination with bacterial strains. Fourier transform infrared spectroscopy revealed that carboxyl, amino and OH groups present on the waste tea leaves played a significant role in the binding of Cr +6 ions with the biomass. The present study is unique in this respect that this approach involve both living and non-living materials and we could not find any report documenting such findings up to our knowledge.

Biological treatment of hazardous heavy metals by Streptomyces rochei ANH for sustainable water management in agriculture

“…For agitation speed, Batool and Hasnain 51 indicated that the biosorption of Cr 6+ is highly affected by the speed of agitation where moderate speeds (100–120 rpm) facilitate proper contact between the biomass and the metal ions in the aqueous solution compared with static conditions. Furthermore, a decrease in metal removal efficiency at higher speeds (up to 500 mg/l) may be a consequence of the vortex phenomenon attributed to the reduction of the contact between biomass active sites and metal ions 52 .…”