Isolation And Identification Of A Nickel-resistant Strain And Its Characterization And Mechanism Of Nickel Removal

Heavy metal pollution has been one of the three major water pollution kinds at present, andhas brought tremendous threaten to human’s healthy. As a new wastewater treatment technology,biological treatment technology has become research hotspot and frontier of environmentalcontrol in recent years. A nickel-resistant strain was isolated from sewage with highconcentration of heavy metal ions. Identification, phylogenetic analysis, growth characteristicand biosorption properties of the strain were investigated in this paper. Meanwhile, theadsorption mechanism was explored in depth by a series of modern analysis technologies.An highly nickel-resistant strain, named as JMUZJ-1, was isolated from complex sewage ina hardware factory in Zhangzhou, Fujian province. The strain possesses the capability of Ni2+resistance up to400mg·L-1. Based on the analysis of physiological,16S rDNA sequence andbiochemical characteristics of the strain, JMUI-1was identified as Stenotrophomonas sp.The optimal growth conditions of the strain is pH7.0,30℃and0.5%NaCl. The strain hashigh resistance to heavy metals such as Ni2+, Zn2+, Cu2+, Cd2+and Cr6+, with the followingresistance order: Zn2+> Ni2+> Cu2+> Cr6+> Cd2+. At the same time, the plasmid detectionexperiment indicated that strain JMUZJ-1has no plasmid, and that heavy metal resistance genesare located in the genome.Strain JMUZJ-1had good adsorption performance. The removal rates of10mg·L-1nickel(II)were all above90%after treated by1.5g·L-1biomass for120min at pH6.0～8.0,25～40℃.The adsorption process is affected by many factors such as adsorption time, pH value, initialnickel concentration, bacteria dosage, temperature and co-existing ions.Kinetic adsorption data obtained were fit better to the pseudo-second-order kinetic model;Langmuir model were the better-fitting model for the biosorption of nickel(II) onto the strain.The values of separation factor (RL) for equilibrium were between0and1, proving nickel(II)adsorption occurs effectively.Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM),energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction(XRD) and UV spectroscopy scanning were used to study Ni2+adsorption mechanism. Theresults show that the main adsorption mechanism of the strain consists of surface complexation,ion exchange and so on. There is no reduction-oxidation reaction in the adsorption process, and the amorphous phase compounds are generated after Ni2+adsorption. In addition, theextracellular polymeric substance of the strain might involve in Ni2+adsorption.The strain JMUZJ-1could adsorb rapidly Ni2+ions in the wastewater, and it is carried out atnormal temperature because of little effect by temperature. Therefore, there will be broaddevelopment and application prospects to use the strain as biosorbent to treat low concentratenickel wastewater.