Ni(II), Cr(VI), Cu(II) and nitrate removal by the co-system of Pseudomonas hibiscicola strain L1 immobilized on peanut shell biochar

At present, the improvement of nitrate and mixed heavy metals removal in wastewater by microorganism are urgently needed. Previous studies have shown that Pseudomonas hibiscicola strain L1 exhibited Ni(II) removal ability under aerobic denitrification. In this study, the characteristics of the free strain L1, peanut shell biochar (PBC) and further the cosystem of strain L1 immobilized on PBC were investigated for the removal of Ni(II), Cr(VI), Cu(II) and nitrate in mixwastewater. The results illustrated that strain L1 could remove 15.51% - 32.55% of Ni(II) (20-100 mg.L-1), and removal ratios by co-systemwere ranked as Ni(II) (81.17%) > Cu(II) (45.84%) > Cr(VI) (38.21%). Scanning ElectronMicroscope (SEM), X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) images indicated that the strain L1 immobilized well on PBC and had vigorous biological activity; the crystals of Ni(OH)(2), Cu(OH)(2) and CrO(OH) etc. were formed on surface of co-system with various functional groups participated in. In Sequential Batch Reactor (SBR), the pollutant removal ratios by co-system were higher than that by free strain L1. This study illustrated that the co-system of strain L1 immobilized on PBC was qualified to be applied for practical scenarios of effective heavy metal removal of electroplating mix-wastewater.

Automated summary

This study investigated the removal ability of strain L1 and its immobilized system on PBC for heavy metals and nitrate in mix wastewater. The results showed that the immobilized system had a higher removal efficiency for Ni(II), followed by Cu(II), while the removal efficiency for Cr(VI) was the lowest. SEM, XRD, and FTIR analyses indicated the formation of crystals on the surface of the immobilized system, with various functional groups participating in the removal process. In the Sequential Batch Reactor, the removal efficiency of pollutants by the immobilized system was higher than that of the free strain L1.