Peanut shell biochar immobilized Pseudomonas hibiscicola strain L1 to remove electroplating mixed-wastewater

Mixed electroplating wastewater is in urgent need of eco-friendly and effective treatment. In this study, Pseudomonas hibiscicola L1 strain (strain L1) immobilized in peanut shell biochar (PBC) was effective in the simultaneous removal of Ni(II), Zn(II), Cu(II), Cr(VI) and ammonia nitrogen from mixed electroplating wastewater. PBC improves the biological activity of strain L1. Compared with single PBC and free strain L1, the biochar-immobilized strain L1 had higher removal ratios. The biochar immobilized strain L1 showed excellent removal of Cu(II) (94.92%) > Zn(II) (91.46%) > ammonia nitrogen (79.90%) > Ni(II) (77.02%) > Cr(VI) (34.40%). Scanning electron microscopy (SEM) results showed that strain L1 was well immobilized on PBC with strong bioactivity. X-ray diffractometry (XRD) showed the formation of crystals of Zn(OH)2, Cu(OH)2, CrO(OH) and Ni(OH)2, etc. Fourier transform infrared spectroscopy (FTIR) revealed the formation of multiple functional groups on the surface of the biochar immobilized strain L1. In addition, the highest removal ratios for Ni(II), Zn(II), Cr(VI), Cu(II) and ammonia nitrogen in the sequencing batch reactor (SBR) were 78.70%, 94.57%, 59.70%, 92.50% and 98.81% by biochar immobilized strain L1, respectively. Therefore, biochar immobilized strain L1 has good application potential in treating mixed electroplating wastewater.