Synergistic Removal Of Sb(?) From Water By Iron Filings-iron Bacteria-sulfate Reducing Bacteria

Antimony is a recognized toxic and carcinogenic metalloid element.Antimony pollution has seriously damaged the ecological environment and human health.Considering the high cost of chemical synthesis of iron oxides to treat antimony mine wastewater and the competitive adsorption of a large number of sulfates,the antimony removal by sulfate reducing bacteria?SRB?faces the problem that dissolved oxygen inhibits microbial activity.The project uses cheap iron chips to treat antimony mine wastewater,makes full use of the biogenic ferrite minerals of chemoautotrophic iron bacteria to adsorb antimony?V?efficiently,and takes into account the ability of SRB biological precipitation to remove antimony in the microenvironment consisting of iron chips and iron bacteria.High-throughput macrogenomic microbial sequencing,X-ray diffraction?XRD?,infrared spectroscopy?FTIR?,scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?were used to characterize antimony removal products.The mechanism of antimony removal by iron filings-iron bacteria-sulfate reducing bacteria?SRB?was discussed by comparing the effects of different systems.The main results and conclusions are summarized as follows:?1?Enterobacter is the main component of iron bacteria screened,which has good oxidation effect on Fe²⁺ions.The strain is red-brown bulge on the medium plate containing ammonium ferric citrate.It has metallic luster under sufficient light conditions,and the colony has the characteristics of rough surface and uneven edges.The strain of sulfate reducing bacteria?SRB?mainly contains Desulfovibrio.The strain has good ability to reduce SO₄^2-ions and is black on solid medium containing iron.The diameter of round colony is 1-3 mm.It has good light transmittance,Gram staining is positive,no spores,the strain is arc,doing wave motion,size is?0.4-0.5?×?2.0-2.3?um.?2?The effects of pH value,dosage,temperature,initial concentration and coexisting ions on the antimony removal performance of three different systems were investigated by comparing the antimony removal experiments of iron filings,iron filings-iron bacteria and iron filings-iron bacteria-sulfate reducing bacteria?SRB?.The results show that the removal of antimony?V?by iron chips is better under acidic conditions,but the removal of antimony?V?by iron chips is not good because of the inhibition effect of SO₄^2-coexisting ions.In the antimony removal experiment of iron chips-iron bacteria coexisting system,the release of Sb?V?occurs at the later stage of the reaction and the removal rate is 60%,which is due to the instability of the product;and iron chips-iron bacteria-sulfate also results in the removal of antimony?V?.The removal rate of 500 ml 20mg/LSb?V?by SRB combined antimony removal system was 98.7%with the same dosage and microbial inoculation under the condition of deoxidization,and no release occurred in the later stage of the reaction.This system not only effectively solves the inhibition of SO₄^2-ion on antimony removal by iron chips in the experiment of antimony removal by iron chips alone,but also solves the release phenomenon of antimony removal by iron chips-iron bacteria coexistence system,which shows the superiority of synergistic antimony removal by iron chips-iron bacteria-sulfate reducing bacteria.?3?By comparing the antimony removal products of three systems:iron filings,iron filings-iron bacteria and iron filings-iron bacteria-sulfate reducing bacteria,SEM,FTIR,XRD and XPS,the main components of antimony removal products from iron filings are FeSb₂O₆,and the main components of antimony removal products from iron filings-iron bacteria are FeSb₂O₆ and FeSbO₄,while the above two products are also produced in the antimony removal products of iron filings-iron bacteria-sulfate reducing bacteria.At the same time,Sb₂S₃ and Sb₂OS₂ were also found,which indicated that there was not only the reaction between iron oxide and antimony,but also the sedimentation process of sulfide to antimony in the system.