Membrane biological reactors (MBRs) present an innovative and important advancement in the treatment of wastewater. MBRs provide better effluent quality coupled with a smaller footprint when compared to conventional secondary treatment. However, efficiency and performance of MBRs is strongly hindered by membrane fouling. Previous research has shown that plasma modified membranes have a reduced fouling propensity. Accordingly, research was completed on the modification of plyethersulfone (PES) membranes to determine if modified membranes provide an increase in both effluent flux and fouling resistance when treating wastewater. Modified and unmodified membrane properties and behaviour were evaluated with emphasis on physico-chemical and morphological properties, fouling behaviour of individual fibres and on-site pilot plant studies. Review of numerous membrane characteristics and successful short-term fouling results show that the O 2-Plasma membrane modification had great potential. Long-term pilot studies revealed that the O2-Plasma membrane behaved unfavourably and was impacted by fouling. Further research is required before the goal of increased flux and reduced fouling through membrane modification is achieved.