Comparative Bioremediation Performance of Indigenous Bacillus paramycoides KUHKSN-01 and Acinetobacter indicus KUHKSN-02 in the Removal of Heavy Metals from Textile-Industry Effluent

Abstract

Textile manufacturing generates wastewater containing persistent heavy metals that can accumulate in ecosystems and pose human-health risks. This study compared the multi-metal remediation performance of two indigenous bacterial strains, Acinetobacter indicus KUHKSN-02 and Bacillus paramycoides KUHKSN-01, in raw and diluted textile-effluent matrices under sterile monoculture and non-sterile bioaugmented configurations during 96 h of static incubation. Residual filtered aqueous concentrations of Fe, total Cr, Cu, Zn, Pb, Ni, Cd, and Mn were determined by atomic absorption spectroscopy. Across matched configurations, B. paramycoides produced lower residual concentrations than A. indicus. The lowest residual concentrations occurred in the non-sterile diluted-effluent configuration bioaugmented with B. paramycoides (URTE50+B): 0.35 ± 0.08 mg/L Fe, 0.08 ± 0.02 mg/L total Cr, 0.09 ± 0.02 mg/L Cu, 0.12 ± 0.03 mg/L Zn, 0.025 ± 0.01 mg/L Pb, 0.02 ± 0.01 mg/L Ni, 0.010 ± 0.003 mg/L Cd, and 0.05 ± 0.01 mg/L Mn. When calculated against the corresponding untreated diluted-effluent control, removal efficiencies ranged from 87.5% to 95.2%. The residual concentrations were below the Central Pollution Control Board general standards applied for discharge into inland surface waters. Non-sterile bioaugmented configurations produced lower residual concentrations than the corresponding sterile monocultures; however, because an incubated native-community-only control was not included, this difference should be interpreted as a configuration effect rather than conclusive evidence of microbial synergy. The results identify indigenous bacterial bioaugmentation as a promising laboratory-scale approach for reducing the filtered aqueous concentrations of multiple metals in textile effluent.