On the design of sustainable antifouling system for the crossflow filtration of oily water systems: A multicontinuum and CFD investigation of the periodic feed pressure technique

Abstract

The problem of fouling is considered a major reason for deteriorating the performance of porous membranes. Even though the accumulations of materials at the membrane surface are inevitable, efforts are continuously spent to minimize their drawbacks. Several techniques have been tested to minimize the problem of fouling. Some of these methods, however, confront some technical difficulties that make their use unfeasible. For example, in polymeric-type membranes, back flushing may result in the loss of bonding between the active and the support layers resulting thereby to the disintegration of the membrane. Recently, an interestingly new approach has been proposed that minimizes the problem of fouling and maintains the integrity of the membrane. The so-called periodic feed pressure technique, PFPT, cleans the surface of the membrane by reducing the adherence of the droplets to the membrane giving the chance to the crossflow field to sweep off pinned droplets. In this work, some of the features of the PFPT technique are highlighted using results from CFD simulation. Then we further investigate the PFPT technique in the realm of the multicontinuum modeling approach in which both the emulsion and the membrane are treated as overlapping continua. The behavior of the membrane is studied considering different transmembrane pressure values to highlight the fates of the different oil continua upon interacting with membrane continua. From the CFD highlights, it is found that during the half cycle when the TMP is set to zero, oil droplets at the surface of the membrane becomes unstable and it becomes easier for the crossflow field to dislodge them. The multicontinuum study, on the other hand, provides macroscopic analysis on the effects of different TMP cycles on important macroscopic parameters that influence the design, including the rejection capacity of membranes.