Gel layer formation on membranes in Membrane Bioreactors

The widespread application of membrane bioreactors (MBRs) for municipal wastewater treatment is hampered by membrane fouling. Fouling increases energy demand, reduces process performance and creates the need for more frequent (chemical) membrane cleaning or replacement. Membrane fouling in MBRs is known to be caused by several membrane fouling mechanisms. Extracellular polymeric substances (EPS) play a major role during fouling development. However, EPS concentration in the bulk solution can not be generally used as an indicator for fouling propensity. The term “EPS” comprises several types of compounds, originating from the biomass: proteins, polysaccharides, nucleic acids, lipids and other polymeric substances. In this thesis, several findings are described concerning the role and behaviour of EPS during membrane fouling in MBRs.