Study on the fouling mechanism and cleaning method in the treatment of polymer flooding produced water with ion exchange membranes

Abstract

The complex interactions between organic and inorganic foulants in polymer flooding produced water (PFPW) play a significant role in membrane fouling characteristics during the treatment processes with ion-exchange membranes (IEMs). In order to ensure the desalination capacity of IEMs during electrodialysis, this work systematically investigated the fouling mechanism and cleaning properties with different synthetic solutions as feed water. The results demonstrated that the desalination rates of the IEMs decreased by 39.73%, 43.05%, 45.81% and 52.72% when fouled by HPAM, HPAM-inorganic (i.e., CaCl₂ and NaHCO₃), oil emulsions and oil–HPAM-inorganic, respectively. The results of membrane resistances and SEM images indicated that organic foulant (i.e., HPAM) and inorganic components have a synergistic effect on the fouling of IEMs. The membrane cleaning method using acid–base-sodium dodecyl benzene sulfonate (SDBS) was proposed here to recover the performance of the IEMs after being fouled by feed solution containing oil–HPAM-inorganic compounds. The desalination rate of the IEMs after membrane cleaning increased from 39.62% to 81.39%. This indicated that the acid–base cleaning alone eliminated the inorganic precipitation and gel layer, and the subsequent SDBS cleaning removed the dominant oil emulsion layer.