Simultaneous reduction of nitrate and Cr(VI) by Pseudomonas aeruginosa strain G12 in wastewater

The interference of toxic heavy metals in the process of microbial aerobic denitrification is a hot issue in industry wastewater treatment in recent years. In this study, a multifunctional aerobic denitrifying bacterium Pseudomonas aeruginosa G12 isolated from sewage sludge was used to explore the simultaneous removal ability to NO3--N and Cr(VI) in wastewater by a series of batch experiments. The results showed that G12 could effectively remove NO3--N (500 mg L-1) and Cr(VI) (10 mg L-1) by 98% and 93%, respectively. Meanwhile, the study found that the strain G12 had the potential to adapt to the complex external environment, including different carbon resources, nitrogen sources, and the coexisting heavy metals (Mn2+ and Cu2+). The strain G12 also had the considerable tolerance to initial NO3--N (100-700 mg L-1) and Cr(VI) (1-20 mg L-1) concentrations. The instrument analysis methods-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), from the molecular level, further confirmed that the strain G12 could remove NO3--N by aerobic denitrification, and the reduced functional groups (amino group, amide group, hydroxyl group and carboxyl group) on the surface of bacteria could transform Cr(VI) to Cr(III) (mainly CrCl3). This study will offer a promising new microbial resource for nitrogen and Cr(VI) removal in industry wastewater treatment.