FreeSpace – Reducing Membrane Fouling by Exploiting Hydrodynamic Effects

Fundamental research to exploit hydrodynamic effects to reduce membrane fouling by introducing special arrangements of novel feed spacer geometries in combination with non-regular membrane surface-pattern

Nanofiltration (NF) and Reverse Osmosis (RO) membranes are highly selective towards salts, micro-pollutants and other emerging contaminants, allowing effective treatment of industrial and municipal effluents as well as desalination of brackish water and seawater. However, membrane fouling is a major limitation, leading to an increase in pressure drop, lower membrane flux and higher overall operational costs of membrane filtration plants. In order to mitigate membrane fouling, adapting the geometry of the feed spacers and membrane surface patterns has been studied among other approaches.

In this DFG-funded research project, we aim to investigate synergistic influences of membrane surface patterning and feed spacer geometry on fluid dynamics and particle deposition mechanisms in the feed channel at certain operating conditions. This research will promote our understanding of fundamental design criteria that determine the overall module performance. With this understanding, special arrangements of feed spacer and surface pattern geometries will be designed. This novel development concept is believed to allow for higher process efficiency, longer module lifespan, and less energy consumption.

Biofouling, the accumulation of microorganisms and subsequent biofilm growth on the membrane, is of particular concern in NF and RO systems. Therefore, in order to understand the spatial and temporal evolution of biofouling on surface-patterned membranes, we perform accelerated biofouling experiments with semi-synthetic feed water. A pre-defined protocol allows conducting biofouling experiments in a well-defined and reproducible manner.

In parallel to this experimental approach, we create a CFD model of the fluid dynamics in the feed channel with surface-patterned membranes. CT scans of feed spacers assure an accurate representation of their geometry. With this CFD model, we plan to investigate the macro-scale flow in the whole feed channel as well as the micro-scale flow in direct vicinity of the membrane surface patterns.