基于计算流体力学（Computational Fluid Dynamics, CFD）方法，对气升循环分体式膜生物反应器（Airlift external circulation membrane bioreactor, AL EC MBR）的关键结构参数与水力学参数的相关关系进行了模拟、优化和敏感性分析。研究结果表明，增加气液混合高度和曝气元件数量可提高混合液的混合程度及膜面流速、剪切力分布的均匀性，有利于膜污染控制；曝气器位置升高会使MBR流场分布的均匀性下降；混合液粘度的增加会降低混合液循环流速，但使膜组件中气液混合流的均匀度提高。在MBR膜组件中存在着混合液流速和剪切力分布中部区域高外部区域低的不均匀性，这种不均匀性是导致膜有效利用面积降低和水处理成本升高的重要流体力学因素。
关键词：计算流体力学；气升循环分体式膜生物反应器；构型优化；敏感性分析；膜污染控制

Simulation and optimization of airlift external circulation membrane bioreactor (AL EC MBR) was performed using computational fluid dynamics (CFD) in this paper. Four cases of MBRs withdifferent configurat- ions were simulated and the sensitivity analysis of their impacts on the velocity, shear stress, circulation rate of mixture in the MBRwere presented. The results showedthat larger distance from diffusers to membrane modules(height of gas-liquid mixing zone)was helpful to improvethe velocity and shear stress at the membrane surfaces for membrane fouling control;the distribution of shear stress at the membrane surface in the membrane tank with 3 diffusers wasmore uniformthan that with2 diffusers;higher position of the diffusers wouldresult inmore fluid dead zones under the diffusers in the membrane tank.It was also notedthat higher viscosityof the mixture in the 
MBR will lower the circulation rate between the membrane unit and the aeration tank, but on the contrary,the distribution of air-liquidflowingover the membrane surfaces appeared moreuniform.However, the fluid velocity and wall shear stress are always higher at the centralsheets and much lower at the side ones in membranemodule.Thenon-uniformity of gas-liquid flow though the channelsbetween the membrane sheets isone major reason to lose effectivefiltration area of membranes,to lose productivity of treated water and to result in high energy consumptionforMBR application. 

[1] 杨文静, 樊耀波, 徐国良, 等. 膜生物反应器操作条件对EPS含量及膜污染的影响[J]. 膜科学与技术, 2010, 30(06): 41-48.
[2] Judd S, Judd C. The MBR Book——Principles and Applications of Membrane Bioreactors for Water and Wastewater Treatment[M]. UK: Elsevier, 2011.
[3] Meng F G, Chae S R, Drews A, et al. Recent advances in membrane bioreactors (MBRs): Membrane fouling and membrane material[J]. Water Research, 2009, 43(6): 1489-1512.
[4] Brannock M, Wang Y, Leslie G. Mixing characterisation of full-scale membrane bioreactors: CFD modelling with experimental validation[J]. Water Research, 2010, 44(10): 3181-3191.
[5] Naessens W, Maere T, Ratkovich N, et al. Critical review of membrane bioreactor models – Part 2: Hydrodynamic and integrated models[J]. Bioresource Technology, 2012, 122: 107-118.
[6] 张德良. 计算流体力学教程[M]. 北京: 高等教育出版社, 2010.19-34.
[7] 谢龙汉，赵新宇，张炯明. Ansys CFX流体分析及仿真[M]. 北京: 电子工业出版社, 2012. 1-2.
[8] Ghidossi R, Veyret D, Moulin P. Computational fluid dynamics applied to membranes: State of the art and opportunities[J]. Chemical Engineering and Processing, 2006, 45(6): 437-454.
[9] Böhm L, Drews A, Prieske H, et al. The importance of fluid dynamics for MBR fouling mitigation[J]. Bioresource Technology, 2012, 122: 50-61.
[10] Ndinisa N V, Fane A G, Wiley D E, et al. Fouling control in a submerged flat sheet membrane system: Part II - Two-Phase flow characterization and CFD simulations[J]. Separation Science and Technology, 2006, 41(7): 1411-1445.
[11] Ratkovich N R, Nopens I. Modelling hydrodynamics in MBR systems using computational fluid dynamics [A]. IWA North American Membrane Research Conference, Abstracts[C]. 2008.
[12] E. Nguyen Cong Duc C L. CFD applied on MBR system[A]. 1st CFD Modeling for MBR Applications“From the fibre to the plant”[C], Berlin, Germany, 2007. 48-53.
[13] E. Nguyen Cong Duc C L, B. Lesjean, K. Essemiani, B. Hohman,. CFD applied to Membrane Bioreactor Upstream R&D Industrial application[A]. 2st CFD Modeling for MBR Applications“From the fibre to the plant”[C], Ghent, Belgium, 2008. 65-71.
[14] Liu W, Jordan E, Kippax V, et al. Using Computational Fluid Dynamics (CFD) and Particle Image Velocimetry (PIV) To Characterize Air and Water Two Phase Plug Flow Membrane Clean System[J]. Proceedings of the Water Environment Federation, 2009, 2009(14): 2798-2811.
[15] Brannock M W D, De Wever H, Wang Y, et al. Computational fluid dynamics simulations of MBRs: Inside submerged versus outside submerged membranes[J]. Desalination, 2009, 236(1-3): 244-251.
[16] Khalili-Garakani A, Mehrnia M R, Mostoufi N, et al. Analyze and control fouling in an airlift membrane bioreactor: CFD simulation and experimental studies[J]. Process Biochemistry, 2011, 46(5): 1138-1145.
[17] Drews A, Prieske H, Meyer E L, et al. Advantageous and detrimental effects of air sparging in membrane filtration: Bubble movement, exerted shear and particle classification[J]. Desalination, 2010, 250(3): 1083-1086.
[18] Drews A, Prieske H, Kraume M. Optimierung der Blasen- und Zirkulationsströmung in Membranbelebungsreaktoren[J]. Chemie Ingenieur Technik, 2008, 80(12): 1795-1801.
[19] Prieske H, Drews A, Kraume M. Prediction of the circulation velocity in a membrane bioreactor[J]. Desalination, 2008, 231(1-3): 219-226.
[20] Martinelli L, Guigui C, Line A. Characterisation of hydrodynamics induced by air injection related to membrane fouling behaviour[J]. Desalination, 2010, 250(2): 587-591.
[21] 李辉. 曝气位置对一体式膜生物反应器操作性能的影响[D]: [学位论文]. 呼和浩特: 内蒙古工业大学, 2009. 30-37.
[22] 于艳, 樊耀波, 徐国良, 等. 计算流体力学对膜生物反应器水力学特征的模拟研究[J]. 膜科学与技术, 2011, 31(04): 9-16.
[23] 樊耀波, 徐慧芳, 郭海明. 气升循环分体式膜生物反应器污水处理与回用技术[J]. 环境污染治理技术与设备, 2004, 5(7): 70-75.
[24] 北京民生源生态技术有限责任公司. 公司简介[EB/OL]. [2012-11-04].
http://www.bjmsy.com/company/.
[25] 黄琪晨.佛山冯了性药业引进中科院气升式膜生物反应器技术[EB/OL]. 南方日报, 2008[2012-10-20]. http://www.shuigongye.com/News/20088/A-938E-D15F84EDA149.html.2008.
[26] 樊耀波, 杨问波. H或h循环管分置式膜生物反应器. 中国, CN 1318320C[P].2007.5.30.
[27] Wang Z, Wu Z, Yin X, et al. Membrane fouling in a submerged membrane bioreactor (MBR) under sub-critical flux operation: Membrane foulant and gel layer characterization[J]. Journal of Membrane Science, 2008, 325(1): 238-244.
[28] Belfort G, Davis R H, Zydney A L. The behavior of suspensions and macromolecular solutions in crossflow microfiltration[J]. Journal of Membrane Science, 1994, 96(1-2): 1-58.
[29] 敏感性分析[EB/OL].百度百科, [2012-10-20].
 http://baike.baidu.com/view/26508.htm.
[30] Jiang T, Kennedy M D, Yoo C, et al. Controlling submicron particle deposition in a side-stream membrane bioreactor: A theoretical hydrodynamic modelling approach incorporating energy consumption[J]. Journal of Membrane Science, 2007, 297(1-2): 141-151.
[31] 李刚. 气升循环分体式膜生物反应器相关机理及工艺优化研究[D]: [学位论文]. 北京: 中国科学院研究生院, 2006. 38-75.
[32] 田恒斗, 金良安, 丁兆红, 等. 液体中气泡上浮与传质过程的耦合模型[J]. 化工学报, 2010, 61(1): 15-21.