Mechanistic analysis of soft colloid filtration

Membrane filtration is an essential process for clean water production and waste water treatment. Micro- and nanoporous synthetic membranes are the key in filtration processes by retaining natural and colloidal matter that forms a fouling layer, often called the cake layer. This cake layer is one of the most severe problems in membrane filtration since the continuously growing layer steadily decreases filtration performance thereby increasing energy demand. The understanding of the cake layer build-up is important in order to be able to tune its morphology and thereby decrease the decline of filtration performance. Until now, research has been mainly focussing on the macroscopic effects of fouling, such as enhancing the membrane material, coatings, backwashing and chemical cleaning. Microscopic studies have been conducted utilizing microfluidics to transfer the problem to a controlled, reproducible environment. Yet, the very formation of the cake layer build-up is still not fully understood. This thesis presents the microscopic investigation of the cake layer build-up in microfluidic channels.