1 Effect of oil-degrading bacteria on geotechnical properties of 1 crude oil contaminated sand 2 3 Hossein Soltani-Jigheh 1, * , Hamed Vafaei Molamahmood 2 , Taghi Ebadi 3 , Ali Abolhasani Soorki 4 4 5 1 Associate professor, Department of Civil Engineering, Azarbaijan Shahid Madani 6 University, Tabriz, Iran, +984131452592, hsoltani@azaruniv.ac.ir 7 8 2 M.Sc. student, Department of Civil Engineering, Azarbaijan Shahid Madani University, 9 Tabriz, Iran, +989354230134, hvmunlimited@gmail.com 10 11 3 Faculty of Civil and Environmental Engineering, Amirkabir University of Technology, 12 Tehran, Iran, +982164543031, tebadi@aut.ac.ir 13 14 4 ACECR-Research Institute of Applied Sciences, Tehran, Iran, +982122431944, 15 a.abolhasani.s@gmail.com 16