The interest in using polyvinylidene fluoride (PVDF) membrane in order to separate casein and serum proteins has been raised due to its significant stability. However, the high hydrophobicity of PVDF membrane causes severe fouling during filtration processes. Ozonation, a surface modification process in which polar groups would be formed on the membrane surface, is widely known for its high efficiency. In the present study, the main objective was to optimize the ozonation parameters to reach the minimum fouling while the maximum mechanical strength could be retained. The contact angle of a water droplet on the membrane surface decreased from 73.5° to 50.4° after the treatment of the membrane at the optimal gaseous phase ozonation. This indicates an increase in the hydrophilicity of the treated membrane. Also, filtration performance demonstrated a lower fouling occurrence on the treated membrane as compared to the untreated one. Although gaseous ozonation yielded a slightly better performance in comparison to the aqueous treatment, the membrane treated with aqueous phase ozonation was benefited from conserving its mechanical strength. Activated carbon helped decreasing the contact angle and fouling as compared to the non-catalytic aqueous treatment while the tensile strength was not affected