Potential for efficient microbial remediation of Cr(VI) in wastewater using Deinococcus wulumuqiensis R12

Aims: This study aimed to investigate the potential of Deinococcus wulumuqiensis R12 (D. wulumuqiensis R12) as a bioadsorbent for Cr(VI) removal from aqueous solutions. Methods and results: Effects of various factors, including initial concentration of Cr(VI), pH, adsorbent dosage, and time were explored. The maximal Cr removal efficiency was achieved by adding D. wulumuqiensis R12 to the solution at pH 7.0 for 24 h, with an initial Cr concentration of 7 mg l-1. Characterization of bacterial cells showed that Cr was adsorbed to the surface of D. wulumuqiensis R12 by combining with functional groups, such as carboxyl and amino groups on the surface. Furthermore, D. wulumuqiensis R12 was able to keep its bioactivity in the presence of Cr and tolerate Cr concentrations as high as 60 mg l-1. Conclusions: Deinococcus wulumuqiensis R12 demonstrates a comparatively high adsorption capacity for Cr(VI). Under the optimized conditions, the removal ratio reached 96.4% with 7 mg l-1 Cr(VI), and the maximal biosorption capacity was 2.65 mg g-1. More importantly, it was found that D. wulumuqiensis R12 still had strong metabolic activity and maintained its viability after adsorbing Cr(VI), which is beneficial for biosorbent stability and reuse. Significance and impact of the study Since D. wulumuqiensis R12 has excellent adsorption capacity for Cr(VI) in aqueous solution without causing secondary pollution, it has the potential to become a new type of green heavy metal adsorbent.