Water Science and Technology (Dec 2023)
Bioremediation of Cr(VI) using indigenous bacterial strains isolated from a common industrial effluent treatment plant in Vishakhapatnam
Abstract
The present study focuses on removing hexavalent chromium (Cr(VI)) using indigenous metal-resistant bacterial strains isolated from a common industrial effluent treatment plant, a contaminated site in Vishakhapatnam. Three high metal-resistant isolates were screened by growing them in nutrient agar media containing different Cr(VI) concentrations for 24 h at 35 ± 2 °C. The three strains’ minimum inhibitory concentrations of Cr(VI) were examined at neutral pH and 35 ± 2 °C temperature. Morphological, biochemical, and molecular characterizations were carried out, and the strains were identified as Bacillus subtilis NITSP1, Rhizobium pusense NITSP2, and Pseudomonas aeruginosa NITSP3. Elemental composition and functional group analysis of the native and metal-loaded cells were done using energy-dispersive spectroscopy and Fourier-transform infrared spectroscopy, respectively. The operating conditions were optimized using a one-factor-at-a-time analysis. When compared with three bacterial isolates, maximum Cr(VI) removal (80.194 ± 4.0%) was observed with Bacillus subtilis NITSP1 with an initial Cr(VI) concentration of 60 mg/L, pH 7.0, an inoculum size of 2% (v/v), and an incubation period of 24 h. The logistic model was used to predict the variation of biomass growth with time. The present study can be extended to remove heavy metals from industrial wastewater in an environmental-friendly manner. HIGHLIGHTS Cr(VI), being ranked 17th in the Agency for Toxic Substances and Disease Registry's list, was eliminated via a microbial route.; Three metal-resistant bacterial strains that were isolated from a common industrial effluent treatment plant in Vishakhapatnam, India, effectively removed Cr(VI).; Energy-dispersive spectroscopy and Fourier-transform infrared spectroscopy confirmed the metal-binding capability.; The logistic model predicted biomass growth variations over time. Bacillus subtilis NITSP1 exhibited the highest Cr(VI) removal.;
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