Pilot-scale plant investigation of blocking mechanism in oily wastewater from refinery processes treatment by polymeric membrane filtration

Treatment of the oily and greasy wastewater of Tehran refinery using a microfiltration and ultrafiltration systems were experimentally studied. Investigations have been done to specify the mechanisms of membrane blocking for MF GRM and UF GRM, based on constant pressure filtration law and Hermia’s hypothesis. This paper presents the performances of MF GRM and UF GRM polymeric membranes with hydrophilic surface using synthetic feed and wastewater effluent of API unit in refinery’s processes. A comparison was made under optimum operating condition in a laboratory scale system in cross flow mode. After correlating the experimental results with the models data, the mechanisms of blocking have been found. The mechanism for MF GRM is intermediate blocking at the beginning of filtration, however, then changes to cake model at the end of filtration. The mechanism for UF GRM is a combination of pore blocking and standard blocking from the beginning of filtration and cake model at the end of filtration, SEM image of membrane cross-section and surface can help us in making the final decision about the actual mechanism of blockage.