Removal of hexavalent chromium from wastewater using magnetotactic bacteria

Biological methods for wastewater treatment are efficiently, ecofriendly. In the present study, removal of hexavalent chromium (Cr6+) was evaluated in a batch-stirred system using magnetotactic bacteria which were cultivated by employing a novel culture method. Temperature, contact time, pH, microorganism concentration, the initial concentration of Cr6+ and co-existing ions (Co2+ and Cu2+) which affect the removal of Cr6+ were investigated. In addition, electric and magnetic fields were applied to the system to detect their effects on the removal of Cr6+. A removal efficiency (RE) of 77% by living cells was obtained within 10 min at pH 6.00, 29 °C. It indicated that Co2+ and Cu2+ as well as the application of an electric field facilitated the removal of Cr6+, while the application of a magnetic field hindered the process. The equilibrium adsorption data were better fitted to Langmuir isotherm model. A mechanism for the removal of Cr6+ by magnetotactic bacteria was proposed based on the findings. The present results show that Cr6+ can be successfully removed by magnetotactic bacteria and are valuable for improving the process of heavy metal removal by magnetotactic bacteria.