Interrelated Resistance Mechanisms in Fouling Layers on Reverse Osmosis Membranes for Water Treatment

污垢通常被认为是反渗透（RO）膜过滤中永久性性能损失的主要原因。然而，结垢的程度和影响对于所有过滤情况并不相同，而是取决于确定相应结垢层的具体性质的许多不同因素。污垢层的单独组成和空间结构又决定了导致过滤系统的污垢相关性能损失的阻力机制。主要的阻力机制之一是通过在膜表面上形成或多或少致密的污垢层而提高的水力渗透阻力;另一个是由于分离而在膜表面处发生的固有存在的极化过程的强化而引起的进料侧渗透压增加。在经典的串联电阻模型中，水力和极化相关效应被视为独立的过程。然而，最近的研究表明，这些机制之间存在显着的相互作用，这可能会导致污垢层的整体阻力的加强或减弱。因此，这些基本相互作用的知识可用于通过控制污垢层的组成和/或结构来显著降低由污垢层引起的阻力。因此，这是预期的系统研究的目的，以确定和调查不同的污垢相关的阻力机制之间的相互作用，在依赖的组合物和结构的特征污垢层，并量化其对整体阻力的实际相关的过滤条件下的效果。这是通过应用基于CFD的模型理论和定义的实验室实验相结合来实现的。

Fouling is commonly regarded as the main cause for the permanent performance loss in membrane filtration by reverse osmosis (RO). Nevertheless, the extent and the effects of fouling are not identically pronounced for all filtration situations but are dependent on a number of different factors that determine the specific properties of the respective fouling layer. The individual composition and the spatial structure of the fouling layer, in turn determine the resistance mechanisms that are responsible for the fouling related performance loss of a filtration system. One of the major resistance mechanisms is the hydraulic permeation resistance raised by the formation of a more or less dense fouling layer on the membrane surface; another is the increased feed-side osmotic pressure induced by an intensification of the intrinsically existing polarization processes that occur at the membrane surface as a result of the separation. In classical Resistance-in-Series models hydraulic and polarization related effects are considered as separate processes. Recent studies, however, indicate that significant interactions exist between these mechanisms, which can either lead to a strengthening or weakening of the overall resistance of a fouling layer. The knowledge of these fundamental interactions could therefore be used to substantially reduce the resistance caused by fouling layers by controlling their composition and / or structure. It is, thus, the aim of the anticipated systematical studies to identify and investigate the interactions between different fouling related resistance mechanisms in dependence of the composition and structure of characteristic fouling layers and to quantify their effect on the overall resistance under filtration conditions of practical relevance. This is achieved by applying a combination of CFD-based model theory and defined laboratory experiments.