Application of the Al2O3-PVDF nanocomposite tubular ultrafiltration (UF) membrane for oily wastewater treatment and its antifouling research

Nanocomposite tubular ultrafiltration (UF) membrane Al2O3-PVDF was prepared by the phase-inversion method. Oily wastewater of Daqing oilfield was treated by PVDF and Al2O3-PVDF tubular ultrafiltration membranes, respectively. The membrane water permeations of the UF process were analyzed. Retentions of chemical oxygen demand (COD) and total organic carbon (TOC) were more than 90% and 98%, respectively. The results indicate that after UF treatment, oil content was below 1 mg/L, suspended solids content was below 1 mg/L, and solid particle median diameters were less than 2 μm. The quality of the permeation water met the requirement by oilfield injection or drainage. Fouled membranes and washed membranes were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and fouled membranes were backwashed with different solutions. Results show that the addition of nano-sized alumina particles improved membrane antifouling performance, and the flux recovery ratio of modified membranes reached 100% washing with 1 wt% of OP-10 surfactant solution (pH 10).