BACKGROUND: Gachsaran oil field is one of the largest oil fields in southern Iran and vast amounts of hydrocarbon contaminants are generated every year. Work is urgently required to devise effective methods to treat the produced water and high TPH content oily sludge under conditions that mimic the oil field. Bioremediation as an environmentally friendly and relatively cost-effective technique was examined in the present research. A continuous membrane bioreactor (CMBR) and bio-slurry processes were utilized to treat the produced water and oily sludge, respectively. RESULTS: The ability of consortium (GACH-1) for degradation of crude oil under extreme conditions revealed that GACH-1 is able to grow at crude oil concentrations up to 11.3% (w/v), temperatures up to 73 degrees C, salinities up to 15.4%, and in the pH range 4-10. The results obtained from the CMBR tests demonstrated that although the COD of influent changed from 1800-2100mgL(-1), the COD of permeate was maintained at less than 125mgL(-1), which was equivalent to a removal efficiency of 94%. In the case of oily sludge, TPH content was reduced by 31.2% after bioremediation for 90 days. CONCLUSION: Based on this approach, the consortium GACH-1 will be useful in clean-up of petroleum contamination in the Gachsaran oil field. (C) 2016 Society of Chemical Industry