Combining Solvent Extraction and Bioremediation for Removal of 3 Weathered Petroleum in Soil

7 1 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China) 8 2 Department of Environmental Science and Technology, School of Applied Sciences, Cranfield 9 University, Cranfield MK43 0AL (UK) 10 3 National Engineering Research Centre for Distillation Technology, Tianjin 300072 (China) 11 a Present address: Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China) 12 13 ABSTRACT 14 15 This study aimed to remediate a highly contaminated soil with weathered petroleum using an 16 integrated technology combining solvent extraction and biodegradation. Soils were washed using a 17 composite organic solvent consisted of hexane and pentane (4:1 v/v) and then bioremediated in 18 microcosms which were bioaugmentated with Bacillus subtilis FQ06 strains and/or rhamnolipid. The 19 optimal solvent extraction conditions were determined as extraction for 20 min at 25 °C with 20 solvent-soil ratio of 6:1 (v/w). On this basis, total petroleum hydrocarbon was decreased from 140,000 21 to 14,000 mg kg, which was further reduced to < 4000 mg kg by subsequent bioremediation for 22 132 days. Sustainability assessment of this integrated technology showed its good performance for 23 both shortand long-term effectiveness. Overall results encouraged its application for remediating 24 contaminated sites especially with high concentration weathered hydrocarbons. 25 26