A hybrid membrane-aerated biofilm reactor (MABR) system, combining the advantages of MABR process and the deep treatment of ozone-biological activated carbon (O-3-BAC), was used in the treatment of oil-field wastewater. The effects of aeration pressure and feed flow rate of MABR and retention times of O-3-BAC were investigated. The results showed that at the optimal conditions, the effluent concentrations of COD, oil, TN and NH4+-N were 45 mg/l, 2.7 mg/l, 6.8 mg/l and 2.8 mg/l, respectively, achieving the requested discharge standards of oil-field wastewater. In this study, it proved that hydrolytic acidification and aerobic oxidation could be completed in the same MABR process. As calculated, in the BAC process, only 25.2% of organic matters remained on the activated carbon and the others were degraded by the microbes of the BAC. Comparing with traditional activated carbon, BAC could prolong the usage period much longer in this study. Therefore the hybrid MABR process is a promising technology for oil-field wastewater treatment. (C) 2014 Elsevier B.V. All rights reserved.