CFD在环境工程领域的应用

1、CFD在环境工程领域的应用WhatHowBackgroundandWhyConclusionAcknowledgementMenuChinas Ministry of Environmental Protection, 2016. China environmental state bulletin of 2015The second water resource (China State Council, 2016):10.8 million m3/d wastewater were reclaimed in 2023.n2010.7 million m3/d wastewater were

2、 reclaimed i15.Background & WhyHigher ratio of wastewater reuse can beeCxopunetrcyted TreatedReclaimedReusedReuse ratioChina14023128.6%America132401410.6%EU116-2.782.4%Israel0.92-0.7682.5%Japan40-0.521.3%4treatmenPollutantst Spplaenctial gradestandardFirst gradeStandard AFirst gradeStandard BSecond

3、gradestandardCODCr30506080BOD56102030Ammonia1.5(3)/3(5)5/88/1515/20TN10/15152025TP0.30.51.01.0SS5102030Color15303040Oil1.01.03.05.0Petroleum0.51.03.05.0LAS0.30.51.02.0Discharge standard of pollutants for urban wastewaterAvailable treatment technologies (Ozgun, 2013; Zhang, 2016):Membrane bioreactors

4、Conventional activated sludgeEmerging technologies: anammox, aerobic granular sludge,MBfRMore restrict discharge standard is going to be issued(China State Council,2016):Background & WhyStrengthens of MBRSmall footprintHigher biomass concentrationHighly-improved effluent quality WLeesasksnleusdsgees

5、 porfoMdBucRtionHigher operation costLower efficiency of nutrients removalA case in BeijingCapacity of MBR 800,000 m3/d by2015,Reclaimed water 39,700,000 m3/d by 2015.CFD modelling &simulationBackground & Why36.18%9.53%11.99%8.20% 7.22% 3.87% 10.84% 0.43%0.13% 3.48% 6.66%Feed pumpAir compressor1.47%

6、ScreenAgitationExternal recirculationInternal recirculationSuctionNon-production Sludge dryingReclaimed water Sludge dewatering MCCComposition of energy consumption of anA2/O-MBR in Qinghe reclaim water plantCFDapproachesforenergy saving & better water qualityConfiguration modificationProcess adjust

7、mentBio-kinetics integrationBackground & WhyWhat MBR configuration modificationYang, et al, watermatex IWA, 2015Yan, et al, Bioresource technology, 2015VSWithout membrane moduleWith membrane moduleWithout membrane moduleWith membrane moduleWhat MBR configuration modification气含率存在差异LrL rU=2gh 1 KBRKB

8、MKAMAr Ad20.5AMK= cBMK= dKBR = al dcArAc AdAb0 c 1e1 d 10, 0 e 1b1 a 10, 0 b 1Pearson correlation analysisDifferent scenarios:Module heightMembrane heightBioreactor height hLMembrane spaceYang, et al, IWA water conference,2016What MBR configuration modificationPearson correlation analysis for liquid

9、 velocity in the riser and membrane shearviscosityTKEVOF_rV_wStrain_rateShear_StressArAdAcAbd_ch_Lh_Dh_EAd_AbAr_AcAr_Adviscosity1TKE-.864*1VOF_r-.389.562*1V_w.686*-.706*-.0971Strain_rate-.833*.623*.323-.486*1Shear_Stress-.806*.962*.632*-.672*.500*1Ar-.853*.957*.503*-.777*.677*.877*1Ad-.459.582*.350-

10、.233.445.551*.557*1Ac-.640*.685*.244-.737*.421.611*.741*-.0451Ab-.206.143.128-.274.301.157.165.026.2271L/d_c-.890*.967*.488*-.785*.701*.889*.996*.543*.747*.1611h_L-.283.181-.314-.521*.393.087.294.045.404.711*.2861h_D-.093.046-.706*-.371.094-.132.188.029.258-.166.183.485*1h_E-.093.046-.706*-.371.094-

11、.132.188.029.258-.166.183.485*1.000*1Ad/Ab-.263.412.212-.035.185.371.380.848*-.179-.457.370-.365.128.1281Ar/Ac.263-.199.083.414-.065-.166-.231.532*-.819*-.182-.251-.324-.207-.207.572*1Ar/Ad.304-.488*-.185.198-.262-.465-.463-.791*-.075-.126-.434-.225-.144-.144-.605*-.2971The parameters which are cons

12、idered to be significantly correlated to liquid velocity in the riser are Ad/Ab, Ar/Ad, Ar/Ac, L/dc, hL for Newtonian fluid.However, only Ar, Ac, L/dc, hL were found to be correlated to liquid velocity for Non- Newtonian.Further study is needed to address the discrepancy.What MBR configuration modif

13、icationWhat Operation optimizationOperating conditionsOperating rangeMLSS (g/L)6.0-18.0Air flowrate (m3/h)1.0-2.0Bubble diameter (mm)1.0-5.0Table 1 Operating conditions and corresponding ranges used for the design of experimentsFig. 3 PSD and PSW factorFig. 4 Viscosity-shear rate rheologyWhat Operat

14、ion optimizationN o r m a l % P r o b a b i l i t yNormal Plot of Residuals-3.00-2.002.003.0019590807050302010599N o r m a l % P r o b a b i l i t yNormal Plot of Residuals-2.00-1.000.001.00Internally Studentized Residuals2.0019590807050302010599N o r m a l %P r o b a b i l i t y-1.000.001.00Interna

15、lly Studentized ResidualsNormal Plot of Residuals-2.00-1.000.001.00Internally Studentized Residuals2.0019590807050302010599N o r m a l %P r o b a b i l i t yNormal Plot of Residuals-3.00-2.00-1.000.00Internally Studentized Residuals1.002.0019590807050302010599(a)shear stress(b)NBV(c)strain rate(d)DO

16、What Operation optimizationOptimal targetsShear stress (Pa)NBV(m s-1J-1)Strain rate (s-1)Aeration intensity2.001.002.00Bubble diameter4.324.974.97MLSS18000.003000.003000.00ResponseShear stress3.140.550.78NBV3.21e-81.24e-77.79e-8Strain rate118.17152.50191.37DO(mg L-1)2.002.633.55Table 3 Optimal opera

17、ting conditions and response values for each one of the membrane scouring indicesWhat Operation optimization9000.006000.00 1.002.003.004.005.003.503.002.502.001.501.000.50S h e a rs t r e s sB: Bubble diameter18000.0015000.0012000.00C: MLSS(a)S t r a inR a te9000.006000.00 1.002.003.004.005.002.00E-

18、084.00E-086.00E-088.00E-081.00E-07N o r m a n i s e d b a c k t r a n s p o rB: Bubble diameter18000.0015000.0012000.00C: MLSS(b)1808.00160(c)6.501405.001203.501002.00800.5018000.005.006000.001.0015000.004.009000.002.0012000.003.0012000.003.00C: MLSS9000.006000.001.002.00B: Bubble diameterC: MLSS150

19、00.0018000.005.004.00B: Bubble diameterD O(d)What Operation optimizationPropensityShear stress=NBVShear stressNBVNBVShear stressOptimal targetsShear stressShear stressShear stressNBVNBVNBVAeration intensity1.282.001.00Bubble diameter4.273.454.20MLSS10274.1818000.005945.36ResponseShear stress1.693.05

20、1.03NBV6.11e-83.46e-89.70e-8Strain rate125.93118.14134.75DO2.623.083.16Desirability0.310.570.41Table 4 Optimal operating conditions and response values considering the maximization of multiple responsesWhat Operation optimizationWhat Operation optimizationDiagram of the Integrated airlift A/O-MBRGeo

21、metry andoperation parametersWhatsnew ?ItemsParametersScale100.0 L/dHRT14.0hSRT20.0dFlat sheet membraneSinap-25-PVDF,pore size0.1mOperation flux10.5LMHAeration intensity0.5 (SAD 25), 1.0 (SAD50), 1.5 (SAD 75) m3/hConnectinghole diameter10.0mmImpellersDouble straight oar 60 rpmw: d: D= 0.25: 1.00: 1.

22、25Key concerns ?Diameter: 10 mmWhat MBR process innovationXYZAerationtank Anoxic tankMembranemoduleReflow holeOutflow hole600mmMembranesheet25 (0.5 m3/h)SAD50 (1.0 m3/h)75 (1.5 m3/h)Fig. 3. Configuration of the airlift recirculation A/O-MBRWhat MBR process innovationArea-weighted average water veloc

23、ity (left) and species concentration (right) at the cross section of reflow holeWork flow of CFD study for membrane bioreactorWhat MBR process innovationLocal flow profile of water velocity (left) and water streamline (right) in the AEC-MBR at SAR50Yang, Bioresource technology, 2016What MBR process

24、innovationYang, Bioresource technology, 2016What MBR process innovationHydrodynamics and spatial distributionof species and scalarsParametersTable 3 Performances of the AEC-MBR at different aeration intensitiesSAR 25SAR 50SAR 754.980. 300.080.2 20.050. 101.961.082.360.110.520.2895.6Average DO in oxi

25、c unit (mg L-1)0.970.14 b3.100.24Average DO in anoxic unit (mg L-1)0.0040.0 40.020.1 3Average ammonia in oxic unit (mg L-1)0.110. 160.080. 13Average ammonia in anoxic unit (mg L-1)4.361.1 33.411.19 Average NOX in oxic unit (mg L-1)2.720. 182.870. 17Average NOX in anoxic unit (mg L-1)0.100.1 40.160.2

26、 1 Removal ratio of total nitrogen (%)94.894.6Recirculation ratio (%)103613061531Average shear stress (Pa)0.90.6 c1.20. 81.40.8Yang, Bioresource technology, 2016What MBR process innovationFig. 6 Effects of aeration intensity on membrane surface shear stress with maximum on m1b, minimum on m5a and av

27、erage of all membrane surfacesFig. S1 Shear stress-shear rate nonlinear curve fitting for activated sludge (MLSS = 7.5 g/L, T=20) in the AEC-MBRWhat MBR process innovationShear stress on the membrane surface for (a) no dosing, b) Fe(II) added toprimary anoxic zone, c) Fe(II) added to membrane zone.S

28、hear stress distribution on membrane surface along the membrane width(x) at different heights (z) for different dosing scenariosLiu, Water Res.,2015What MBR process innovation500 t/d MBRLiu, IWAConf., 2016What MBR process innovationPlan view of full-scale A2/O-MBR and CFD modelling prospectiveWhat F

29、ull-scale WWTP simulationFlow streamline in a pilot-scale A2/O- MBRSpecies fraction distribution in a pilot- scale A2/O-MBRA full model for pilot- and full-scale MBR will be done for the simulation of both of the hydrodynamics and water qualitiesWhat Full-scale WWTP simulationDifferent diffuser patterns effect on flow field,adapt from Gresch, 2011.Effect of membrane dealing on flowReactor configuration study.field, adapt from Wang, 2010.from Kang, 2010.Mixing condition of different MBR WWPT, adapt from Wang, 2010.Examples of full-scale MBRB