Inthisstudymicrobialreductionofjarosite[KFe3(SO4)2(OH)6],acommonsecondarymineralinacidminedrainage(
AMD)area,wasconductedwithadissimilatoryironreducingbacteriumShewanellaputrefaciens CN32andasulfatereducingbacteriumDesulfovibriovulgarisunderneutralanaerobicconditionsinnon-
growthmedia.Wetchemistry,X-raydiffraction(
XRD)andscanningelectronicmicroscopy(SEM)wereusedtoanalyzethereducedironconcentration,mineralcompositionandmorphologyofthesolidphases.
Itwasobservedthatjarositewasfairlystableunderanaerobicconditionswithout
microbes.BothfacultativeS.putrefaciens CN32andstrictanaerobicD .vulgaris werecapableofreducingthecrystallized
Fe3+ injarosite.Undersimilarconditions,D .vulgarisshowedmuchhighercapabilitytoreducecrystallizedFe3+ withafinal
bioreductionextentof16.80%.IncontrastS.putrefaciensCN32canonlyreduce0.37%ofFe3+injarosite.Anthraquinone-2,
6-disulfonate(AQDS)canenhanceFe3+ reductioninD .vulgarisinoculatedsystemswithafinalbioreductionextentof24.30%.
NodiagnosticspectrumotherthanthoseofjarositewasobservedinchemicalcontrolandS.putrefaciensCN32inoculatedsystems.
InD .vulgarisinoculatedsystems,onlyspectrumofsideriteandjarositeweredetectedwithoutthepresenceofAQDS.In
thepresenceofAQDS,jarositepeakswerereplacedbypeaksofsideriteandvivianite.Theelementalanalysisbyenergydispersivespectrometer(
EDS)coupledwithSEMalsoconfirmedthepresenceofsideriteinD .vulgarisinoculatedsystems.WeproposethatthehigherFe3+
reductionextentwithD .vulgarisresultedfromthepresenceofSO42- injarosite,whichcanbereducedtoH2SbyD
.vulgaris.H2S,astrongreductant,subsequentlyenhancedFe3+ reductionextent.Theobservationofvivianitemightresultfromthedegradationofyeastextractionwhichproducedphosphate.
Theresultsclearlydemonstratethehighpotentialofmicrobialreductionofjarositeunderneutral,
anaerobicandoligotrophicconditions.Attentionshouldbepaidtothemicrobialactivitiesandthesecondarymineralizationwhenconsideringjarositeasacandidatematerialtoremoveh
eavymetalsor
storetheradioactivehazards.
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