supplementation of inorganic phosphate enhancing t

1、SupplementationofinganicphosphateenhancingtheremovalefficiencyoftannerysludgebneCrthroughbioleachingGuanyuZhengLixiangZhouDepartmentofEnvironmentalEngineeringCollegeofResourcesEnvironmentalSciencesNanjingAgriculturalUniv

2、ersityNanjingJiangsuProvince210095ChinaarticleinfoArticlehisty:Received27March2011Receivedinrevisedfm14July2011Accepted25July2011Availableonline2August2011Keywds:BioleachingTannerysludgeNutrientsInganicphosphateabstractF

3、ouringanicmineralnutrientsincludingNH4KMg2solubleinganicphosphate(Pi)wereinvestigatedtorevealthepotentiallimitingnutrientsftannerysludgebioleachingprocessdrivenbyAcidithiobacillusspeciesthefeasibilityofsupplementingtheli

4、mitingnutrientstoacceleratetannerysludgebioleachingwasstudiedinthepresentstudy.ItwasfoundthattheconcentrationofPiwaslowerthan3.5mgLthroughoutthewholebioleachingprocesswhichisthemostprobablerestrictingnutrientftanneryslud

5、gebioleaching.FurtherexperimentsrevealedthatthedeficiencyofPicouldseriouslyinfluencethegrowthofAcidithiobacillusthiooxidansloweritsoxidizationcapacityfS0thelimitingconcentrationofPifthegrowthofA.thiooxidanswas6mgL.Thelow

6、concentrationofsolublePiinsludgematrixwasresultedfromtheextremelystrongsbingbindingcapacityoftannerysludgefphosphate.Thesupplementationofmethan1.6gLKH2PO4intotannerysludgebioleachingsystemcouldeffectivelystimulatethegrow

7、thofAcidithiobacillusspeciesenhanceCrremovalratefurthershtentannerysludgebioleachingperiodfrom10daysto7days.Therefeinganicphosphatesupplementationisaneffectivefeasiblemethodtoacceleratetannerysludgebioleachingprocesstheo

8、ptimumdosageofKH2PO4was1.6gLftannerysludgewith5.1%oftotalsolids.2011ElsevierLtd.Allrightsreserved.1.IntroductionCr(III)compoundsareextensivelyusedintanningprocesstoprotectleatheragainstmicrobialdegradationmoisturesweatso

9、on(Erdem2006Zhengetal.2009).HoweveralargeamountofchromiumstillremainsinthetanneryAcidithiobacillusspecies.FinstanceNiemelaetal.(1994)foundthatammoniumamendment(6mM)couldsignificantlyenhanceFe2oxidationduringbioleachingof

10、asulfidicblackschistewhileitisreptedbyHuguesetal.(2008)thatavailableammoniumionwascriticaltobothbacterialgrowthbioleachingefficiencyduringcontinuousbioleachingofapyriteconcentrateinstirredreactswhichresultedfromacombinat

11、ionoffactssuchaslessprecipitatefmationdecreasedbacterialattachmenttothepyritesurface.Besidesthelackofinganicphosphate(Pi)mayalsogreatlyinfluencethebioleachingofminerals(Rawlings2002)sincephosphusplaysanessentialpartofcel

12、lstructuremetabolismfmingpartofnucleicacidsphospholipidslipopolysacidesnucleotidecofactssomeproteinswhereitisincpatedthroughposttranslationalmodification(Veraetal.2008).Otherstudiesdemonstratedthatunderphosphatestarvatio

13、ncircumstancesA.ferrooxidansreduceditsgrowthratecapacityofoxidizingferrousironfixingCO2(SeegerJerez1993a1993bVarelaetal.1998)polyphosphate(polyP)whichexistsinA.ferrooxidanscellsisinvolvedinafunctionalheavymetaltolerancem

14、echanismfthebacterium(AlvarezJezez2004).Alltheseresultsilluminatedthatthemajminnutrientrequirementse.g.NPKMghavethepossibilitiesofaffectingbioleachingprocessesdrivenbyAcidithiobacillusspeciesnutrientsamendmentmightbeafea

15、sibleapproachtoenhancebioleachingefficiency.ThereisahighcontentofnutrientsincludingNPtracemetalsexistinginsludgematrix(CouillardMercier1993)soitisusuallydeemedthatAcidithiobacillusspeciescouldeasilymeettheirnutrientsrequ

16、irementwithoutanyextrainganicnutrientssupplementsduringsludgebioleachingprocesses.HowevernotallnutrientsinsludgecanbereadilyutilizedbyAcidithiobacillusspeciessincesomenutrientsarenotpresentindissolvedinganicfmwhichcanbeu

17、sedbytheobligatechemolithotrophicautotrophs(Varelaetal.1998).InfactChoietal.(2009)haverevealedthatmostphosphuswaseitherbiologicallyboundtomicroganismsphysicochemicallyboundtometalssuchasFeAlinsewagesludgesolublephosphusw