A 0.22m polyethersulfone microfiltration membrane was modified using acrylic acid irradiated with UV light. The degree of grafting (DG) was confirmed by FTIR spectroscopy, which varied from 21 to 568g/cm2 for differing irradiation times and initial monomer concentrations. The contact angle of the modified membranes was at least 10 less than the unmodified PES membrane. Modification filled the pores with copolymer, and decreased the permeability of the membrane. However, following the filtration of E. coli, and membrane cleaning, the flux recovery was 100% for the modified membranes and only 50% for the unmodified membranes. Thus, the modification helped in showing reversible biofouling and higher flux recovery.