Biosorption and bioreduction of aqueous chromium (VI) by different Spirulina strains

Spirulina has emerged as a promising microorganism for the treatment of industrial heavy metal ions in wastewater due to their simplicity of cultivation and harvesting, rich functional binding groups, and high bioreductive activity during the uptake process. While the capacities of biosorption and bioreduction for heavy metal ions differ significantly among various algal strains. Therefore, the physiological characteristics were investigated to identify the different Spirulina strains, and the chromium (VI) adsorption capacities of the algal strains were also evaluated. In this study, it was found that algal strains YCX2643 and CLQ1848 performed higher removal efficiency (86.5% and 83.7%) than the other four Spirulina strains (59.4%, 56.3%, 65.6%, and 66.5%, respectively). Moreover, the mechanisms of chromium (VI) ions binding and biotransformation in the Spirulina cell were scrutinized by FTIR (Fourier transform infrared) spectroscopy and scanning electron microscopy (SEM), and it indicated that the varieties of cellular components involved in high binding affinity may cause the higher biosorption and bioreduction of aqueous chromium (VI) in algal strains YCX2643 and CLQ1848, which could be used as promising biosorbents in the removing heavy metal pollutants from wastewaters.