In this study a membrane bioreactor (MBR) has been studied experimentally for the treatment of oil field wastewater (produced water). This type of wastewater is characterised with relativity moderate to high amount of salt and oil. The normal bacteria which are growing in conventional activated sludge and MBR cannot withstand at these adverse conditions, therefore it is necessary to be adapted. In this study, different samples from sea sediment in Bushehr (south of Iran) were analysed and different groups of bacteria were isolated and adapted for surveying under high salinity conditions. The performance and efficiency of these bacteria in the degradation of model oil has been studied. The results showed that the bacterial consortium can degrade two models of hydrocarbons (hexadecane and phenanthrene) in the presence of salt very effectively. The adapted bacteria were cultivated later in the feed tank of a submerged hollow fiber MBR. The performance of the system, membrane permeability and the rate and extent of oil biodegradability have been studied under different operating conditions. The results showed that the MBR system could be very effective in the removing of oil from produced water. (C) 2009 Elsevier B.V. All rights reserved.