Analysis of fluid-dynamical and physico-chemical aspects of capillary membrane backwashing

在水处理中，使用由内而外死端驱动的UF-/ MF-毛细管膜的膜过滤的应用呈指数增长。因此，仍然是广泛未开发的领域的所需的过滤过程具有提高过滤过程的效率的高潜力。为了优化的过滤过程中，这也应该尽量减少不可逆的膜污染，一个改进的基本理解的机制，这是相关的颗粒和污垢层的分离和运输从由内而外死端驱动的毛细管膜，是必要的。为了系统地阐明这些机制，以及过滤（目标导向的污垢层积累）和过滤实验将在特定的操作条件下进行，特别设计的实验室设备。所获得的结果（在什么条件下，污染层的哪些部分将从毛细管膜的哪个区域分离）将被用作用于毛细管膜中的多相流的CFD支持的数值模拟的工艺参数。多相流建模基于欧拉-欧拉方法，考虑了作用在运动的非布朗颗粒上的最重要的力。此外，流体动力学壁效应，颗粒相互作用（碰撞和团聚）以及颗粒集体的孔隙率将被考虑。一个免费的开源OpenFOAM和商业软件CFX 12将被应用，以比较两个框架从数值的角度来看，并有助于验证结果。所获得的知识，将应用于开发优化的毛细管的不同几何形状的毛细管的毛细管条件。将使用用于长期实验的自动化商业膜系统来验证优化的膜分离模式。

The application of membrane filtration with Inside-Out Dead-End driven UF-/ MF- capillary membranes increases in water treatment exponentially. Thereby the required backwash process, which still is a widely unexplored field, has a high potential to enhance the efficiency of the filtration process. In order to optimize the backwash process, which should also minimize irreversible membrane fouling, an improved fundamental comprehension of the mechanisms, which are relevant for the detachment and transport-out of particles and fouling layers from Inside-Out Dead-End driven capillary membranes, is necessary. For a systematic elucidation of these mechanisms as well filtration (target-oriented build-up of fouling layers) and backwash experiments will be performed under defined operation conditions with especially designed laboratory plants. The obtained results (which parts from the fouling layer will detach under what conditions and from which zone of the capillary membrane) will be used as process parameters for a CFD supported numerical simulation of multiphase flow in capillary membranes. The multiphase flow modelling bases on the Euler-Euler method considering the most important forces acting on moving non-Brownian particles. Additionally, hydrodynamic wall effects, particle interactions (collisions and agglomeration) as well was porosity of particle collectives will be regarded. A free open source OpenFOAM and the commercial software CFX 12 will be applied in order to compare both frameworks from the numerical point of view and contribute to the validation of the results. The attained knowledge of backwash mechanisms will be applied to develop optimized backwash conditions with regard to different geometries of the capillary. The optimized backwash modes will be verified using an automated commercial membrane system for long-term experiments.