The fouling behavior in MBR affected by the ragging phenomenon was characterized by the fast increase of the TMP values. It was caused by the rags attached to the membranes which were not removed through the backwashing or recovery cleanings. However, the modification of operational conditions, such as the reduction of the operational flux or the MLSS concentration, achieved improvements on the fouling rates profile. On the contrary, the increase of filamentous bacteria in the activated sludge negatively affected the fouling behavior. Finally, a strategy based on an optimized mechanical pre-treatment with flocculants addition showed promising results for ragging prevention.