Bio-precipitation Of Antimony From Wastewater By Sulfate-reducing Bacteria:Effect Of Coexisting Ferrous Ion

Antimony is a widely distributed toxic element,which is harm to human by food chain.However,China is rich in antimony mineral resources,and a large amount of mining causes serious pollution.The surrounding water,atmosphere and soil have been seriously polluted by antimony.Therefore,it is urgent to deal with Sb-contaminated wastewater.There are many shortcomings in the traditional treatment methods,in recent years,biological treatment with sulfate-reducing bacteria?SRB?have been considered as a promising method for the Sb removal due to its low cost and high efficiency.In this study,mixed SRB were selected and domesticated from landfill leachate by selective medium,the microorganisms were mainly composed of Desulfovibrio.Escherich and Clostridium.Meanwhile.effect of pH and temperature on reducing Sb by SRB was investigated.Based on that,the effects of ferrous ion?Fe????on the treatment of Sb by sulfate reducing bacteria were studied by analyzing the microbial biomass,the change of sulfate concentration,the change of pH value and the enzyme activity.The effects of Fe???on sediments were studied by X-ray photoelectron spectroscopy.This study concludes as follows:the optimum conditions of on reducing Sb by SRB were as follows:temperature at 35-40?,initial pH value 6.0-7.0,and the antimony removal rate could reach more than 80%;Fe???strengthened the biological precipitation of sulfate-reducing bacteria by shortening the adaptation period of sulfate-reducing bacteria,promoting the growth and metabolism of bacteria,and enhancing the activity of related enzymes,moreover,the enhancement of Fe???related to its concentration.SRB+Fe???systems displayed higher Sb?V?removal efficiency?93.25%,with initial Fe???concentration of 100 mg/L?than that of SRB system?81.41%?.X-ray photoelectron spectroscopy results showed that soluble Sb?V?could be transformed into stable and insoluble compound?Sb₂S₃?,and it was oxidized by air,however Fe???could prevent Sb₂S₃from being oxidized by air.The experiment demonstrates that Fe???+ SRB could be considered as an efficient way for reducing Sb and even other heavy metals.