Immobilizing Of Heavy Metals In Sediments Contaminated By Nonferrous Metals Smelting Plant Sewage With Sulfate Reducing Bacteria And Micro Zero Valent Iron

Biological treatment method using sulfate reducing bacteria(SRB)is considered as the most promising alternative for heavy metals stabilization and immobilization due to its low cost and high efficiency.In this study,a series of immobilization experiments were conducted with heavy metals contaminated aquifer sediment under three conditions:combined sulfate reduction bacteria with micro zero valent iron(mFe0+SRB),individual sulfate reduction bacteria(SRB)or micro zero valent iron(mFe0)only.The aim of this study was to investigate the immobilization efficiency of Cu,Cd,Zn,Pb under these three conditions(mFe0+SRB,SRB,mFe°).The results presented that the performance of leaching toxicity of mFe0+SRB was much better than any single component,the removal efficiencies of Cu,Cd,Zn,Pb(mFe0+SRB)were 100%,98.5%,90.69%,100%,respectively.The stability of the treated results were also evaluated with sequential metal extractions experiments,Cu,Cd,Zn,Pb were found to form more stable mineral phases(for example,residual fraction and oxidizable fraction)in mFe0+SRB conditions.The biological diversity of sediments were analyzed by poly-merase chain reaction-denature gradient gel electrophoresis(PCR-DGCGE)-X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)were used to characterize the mineral phases of treated sediment According to XRD and XPS characterization,heavy metal may existed in the form of FeO,FeOOH,PbCd,PbZn,ZnS,Zn,CdO,CuZn,and CuS.The data demonstrate that mFe0+SRB could be considered as an efficient way for the immobilization of heavy metals.