Membrane biological reactors (MBRs) have a great future in the treatment of wastewater. MBRs have a smaller foot print when compared to conventional secondary treatment, yet have better effluent quality, which includes the removal of pathogens. However, the efficiency and performance of MBRs is strongly hindered by membrane fouling. Previous research has shown that plasma modified membranes have reduced fouling potential. Accordingly, research was completed on the modification of polyethersulfone (PES) membranes to determine if the modified membranes provide an increase in both effluent flux and fouling resistance when treating wastewater. Comparisons were made of modified and unmodified membrane properties and behaviour, with emphasis on physico-chemical and morphological properties, "single-strand" fouling studies and on-site pilot plant studies. Review of the various membrane characteristics and the successful short term simulation results show that the O-2-plasma membrane had great potential. However, the long term pilot test revealed that the O-2-plasma membrane behaved worse than the unimodified membrane and was impacted by fouling. Further study is required before the goal of increased flux and fouling is achieved.