低磷浓度下鸟粪石结晶成粒及反应器流态模拟杨露

2016,36(4)1017~1026ChinaEnvironmentalScience,,*(,,200092)(MAP),MAP.50mg/L,MAP:pH9.0,1:8.MAP0.56mm,4.95cm3/h,99.9%.MAP,CFD(Fluent6.3).:MAP,,,.,,MAP.CFDX703A10006923(2016)04101710Struvitepelletcrystallizationatlowphosphorusconcentrationandfluidizationsimulationofthereactor.YANGLu,PINGQian,LIYong-mei*(StateKeyLaboratoryofPollutionControlandResourcesReuse,CollegeofEnvironmentalScienceandEngineering,TongjiUniversity,Shanghai200092,China).ChinaEnvironmentalScience,2016,36(4)1017~1026AbstractInordertoexpandtheapplicationfieldofstruvite(MAP)pelletcrystallizationtechnology,theoptimalconditionsforstruvitepelletformationatlowphosphorusconcentrationswereinvestigated.Resultsshowthatthephosphorusconcentrationover50mg/Lwouldbebetterforapplicationofthistechnology.Theoptimalconditionsforstruvitepelletformationwereasfollows:pH=9.0andphosphorustonitrogenmolarratio=1:8.Undertheconditions,theaveragesizeofharvestedstruviteparticlereached0.56mm,thevolumegrowthratewas4.95cm3/handthestruvitepurityreached99.9%.InordertofurtheroptimizeMAPformationinthefluidizedbedreactor,CFDsoftware(Fluent6.3)wasusedtosimulatetheflowfedtothereactor.Itturnedoutthatthebottom-uphydraulicclassificationwasformedobviouslyinthegrowingzoneofthecrystallizer.Velocityinthecross-sectionwasrelativelyuniform,whichisbeneficialtostruviteformation.Butsomeadverseconditionssuchasdeadzone,vortexesandcirculationloopswerealsopresentinthesettlingandinfluentzones.Therefore,itisnecessarytoimprovetheconnectionbetweenthegrowingzoneandsettlingzoneaswellasthedistributionofinletpipestoobtainhigh-qualityMAPpellets.Keywordsstruvitepelletcrystallizationlow-phosphorusconcentrationoptionalconditionspelletqualityCFDsimulation.,,[13].(MgNH4PO46H2O,MAP,)[45].Yoshino[6],92%;[7]MAP,90.5%.MAP,,,MAP,,,,MAP[8].,20150730863(2011AA060902)*,[e-mail]101836,100mg/L.,100mg/L.,,MAP.Rahaman[9],MAP,,.,MAP,MAP,CFDMAP,.11.1,MAP.,PO43P30~110mg/L,NH4+N113~181mg/L,Mg2+25.7~93.8mg/L,0.25mol/L.(Na2HPO412H2O),(NH4Cl)(MgCl26H2O),.1.2(1),pH4.,5.80L[10].,MAP.,.4d,24h,NH4+NPO43PMg2+,,MAP.MAP,pHMAP.[7]:140mL/min,HRT41min,400cm/min,4d,PO43:NH4+:Mg2+=1:6:1.1,pH8.2.150gMAP[(22030μm)],MAP[11].pHpHPPP1MAPFig.1Schematicdiagramofthebenchscalestruvitepelletcrystallizationreactor1.3MAPNH4+N(UV754),PO43P(UV754),Mg2+Ca2+(AgilentICP720ES).4d.MAP[7]:,MAP,(1):812iiiiabw(1):aibi;wi41019.MAP[12]:MAP=MAPc100%NnMm(2):MAPMAP;nNNH4+N;MMAPMAP;mcMAP.PHREEQC,(SEM,PHLIPSXL30)X(EDX,PHLIPSFD1C80)MAP.1.41.4.1Gambit2.4MAP(2).,,.,34024,26203.(AspectRatio:4)(EquiAngleSkew:0.35)(MidAngleSkew:0.01)[13],.1.4.2Fluent6.3.Re3732.1,(2300Re4000),Re200,RNGk[14],12.(b)(d)(c)(e)XOYO(a)YX2MAPFig.2Geometrybasedmodelingandmeshingofthefluidizedbedcrystallizera:;b:;c:;d:;e:1Table1Modelsettingsofsinglephaseflow,RNGkSIMPLE1053425NH4+NPO43P,v=0.083m/sMg2+,v=0.033m/s,v=0.625m/s,998.2kg/m30.001003Pas1020362Table2Modelsettingsofsolidliquidtwophaseflow,RNGkphaseCoupledSimpleGidaspow103NH4+NPO43P,v=0.083m/sMg2+,v=0.033m/s,v=0.625m/s,998.2kg/m30.001003Pas1700kg/m31572kg/m30.92500mm22.1MAP20406080100120110905070PO43--P(mg/L)PO43--P(mg/L)3020304050607080PO43--P(%)3PO43PFig.3TheremovalofPO43Patdifferentphosphorusconcentrations2.1.13.,PO43P,PO43P24.33mg/L.3,,MAP,,,,MAP,,,[15].30mg/L,,,1.22cm3/h,0.02mm/d;50mg/L,0.5mm,MAP,98.7%(3).,MAP,50mg/L.3MAPTab.3GrowthofMAPatdifferentphosphorusconcentrationsPO43P(mg/L)(mm)(mm/d)(cm3/h)(%)300.270.021.2298.6500.470.073.1698.7700.630.115.5097.1900.740.148.6599.61100.880.1713.8896.9410212.1.2(50mg/L),PO43P(4).4,,MAP,MAP,,.,,,MAP.,MAP,pH,,NH4+pH,MAP[1617].1:4,0.5cm3/h,1:8,1.96cm3/h.MAP0.425mm,97.9%(4).MAP,P/N1:8.1:41:51:61:71:80102030405060708090(%)P/NNH4+-NPO43--PMg2+4Fig.4TheremovalefficienciesofPO43P,NH4+NandMg2+atdifferentP/Nmolarratios4MAPTable4GrowthofMAPatdifferentP/NmolarratiosP/N(mm)(mm/d)(cm3/h)(%)1:40.3030.020.599.21:50.3210.030.6298.91:60.3090.020.9198.71:70.4150.051.5599.81:80.4250.051.9697.92.1.3pHpH,PO43PMg2+(5).pHMAP3(NH4+PO43Mg2+),.pH,;pH,NH4+[18].pH8.2~9.0,pH,,MAP,[19];pH9.0~9.8,,pH,(5).pH9.0,(0.56mm)(4.95cm3/h),,pH=9.0(50mg/L)MAP.01020304050607080901009.89.49.08.6(%)pHNH4+-NPO43--PMg2+8.25pHFig.5TheremovalefficienciesofPO43P,NH4+NandMg2+atdifferentpHs5pHMAPTable5GrowthofMAPatdifferentpHspH(mm)(mm/d)(cm3/h)(%)8.20.4250.041.9697.88.60.5950.094.6399.89.00.5630.084.9599.89.40.6260.096.2798.69.80.6090.096.5197.22.2MAP2.2.1PHREEQC102236MAP,97.2%,P2O550.3%,[20].,MAP99%,PHREEQC,:Mg(OH)2(Ca3(PO4)2xH2O,ACP)CaMg(CO3)2CaCO3.pH,,PHREEQC(6),pH,Mg(OH)2ACPCaMg(CO3)2CaCO3,MAPpH9.0,.[21]100mg/LMAP.2.2.2pHMAP(SEM),7.MAP,,LeCorre[22].pH,,.pH9.8,,MAP.,(pH=9.0),MAP,.,MAP,.-1.5-1.0-0.50.00.51.01.52.02.53.03.54.04.55.05.56.09.89.49.08.6SIMAPACPCaCO3Mg3(PO4)2Mg(OH)2CaMg(CO3)28.2pH6PHREEQCFig.6SimulationresultsofPHREEQC7pHMAPSEMFig.7SEMimagesoftheMAPatdifferentpHs410238(pH=9.0,=1:8)MAPEDXFig.8EDXimagesofMAPundertheoptimalconditions(pH=9.0,P/Nmolarratios=1:8)6EDXTable6QuantitativeanalysisofMAPbyEDX(%)(%)Ca0.370.17P16.599.61Mg16.7112.33C9.3513.97O56.9863.92100.00100.002.2.3MAP(pH=9.0,=1:8)MAPEDX,8:MAPCaMgOPC