In this work, the resistances-in-series plus critical flux models are used as a simple but efficient tool in order to describe and predict the dynamic performance of a reverse osmosis membrane process, aimed for the tertiary treatment of two-phase olive mill wastewater (OMW2ST). To overcome the uncertainty of fouling, engineers overdesign the membrane plants by using wide safety margins that trigger the costs sensibly. One approach to answer the investor’s need to trust membrane technology is to guarantee that fouling will be strongly inhibited or avoided. Within this context, concentration polarization and fouling could be accurately addressed by the applied models. Similar concentration polarization and fouling build-up rate on the selected membrane was found in the operating pressure range 15-25 bar (1.20 × 10-1 -1.41 × 10-1 h-1), but increased over 5 times (6.42 × 10-1 h-1) upon incrementing the transmembrane pressure up to 35 bar. Moreover, concentration polarization decreased 22.6% and the fouling build-up rate became reduced 45.5% with an increase of the crossflow up to 5.09 m s-1 upon negligible energy penalty, also avoiding irreversible fouling. Finally, significantly minor fouling (52.5-56.2% reduction) was attained at the lowest temperature, regularly experienced during the olive oil production campaign.