Accepted Article Biosurfactant production for enhancing the treatment of produced water and bioremediation of oily sludge under the conditions of Gachsaran oil field Masoud Rahbari-Sisakht, a,* Abdolrasoul Pouranfard, b Parviz Darvishi b and Ahmad Fauzi Ismail c,* a Chemical Engineering Department, Islamic Azad University, Gachsaran branch, Gachsaran, Iran b Chemical Engineering Department, School of Engineering, Yasouj University, Yasouj, Iran c Advanced Membrane Technology Research Center (AMTEC), Universiti Teknologi Malaysia, 81310, Skudai, Johor, Malaysia. *Corresponding authors Email: rahbari@iaug.ac.ir (Masoud Rahbari-Sisakht) Tel: +98 74 3233 3533, Fax: +98 74 3233 2003 afauzi@utm.my (Ahmad Fauzi Ismail) Tel: +60 7-553 5592, Fax: +60 7-553 5925 Abstract BACKGROUND Gachsaran oil field is one of the largest oil fields in southern Iran and vast amounts of hydrocarbon contaminants are generated every year. It is urgent to devise effective methods to treat the produced water and high TPH content oily sludge at the conditions mimic the oil field. Bioremediation as an environmentally friendly and relatively cost-effective technique was examined in the present research. 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°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 1800-2100 mg/l, the COD of permeate was maintained less than 125 mg/l 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. This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/jctb.5081