Abstract

In this study, bacteria Bacillus cereus and Bacillus xiamenensis were used for the biosorption of Cd (II) and Cr (VI) from wastewater. The effects of contact time, pH, and metal ion concentration on the biosorption of Cd (II) and Cr (VI) were studied. The minimum inhibitory concentration (MIC) exhibited by Bacillus cereus was 6 mM for Cd (II) and 7 mM for Cr (VI), and that of Bacillus xiamenensis was 8 mM for Cd (II) and 7 mM for Cr (VI). Bacillus xiamenensis achieved a maximum uptake of 90.70% for Cr (VI) and 84.32% for Cd (II), while Bacillus cereus achieved a maximum uptake of 96.87% for Cr (VI) and 92.15% for Cd (II) in 60 min. The maximum adsorption capacities of Bacillus xiamenensis for Cd (II) and Cr (VI) were 150.02 and 201.2 mg/g, respectively, while the values for Bacillus cereus were 180.76 and 273.49 mg/g for Cd (II) and Cr (VI), respectively. The isotherm study showed that the biosorption data of Cd (II) and Cr (VI) fitted well with the Freundlich isotherm model. The results revealed that Bacillus cereus and Bacillus xiamenensis exhibited promising potential for the removal of Cd (II) and Cr (VI) from metal-contaminated water.