Guozhong Wu;Frédéric Coulon;Yue-Wei Yang;Hong Li;Hong Su

Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China);Department of Environmental Science and Technology, School of Applied Sciences, Cranfield University, Cranfield MK43 0AL (UK);School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China;National Engineering Research Centre for Distillation Technology, Tianjin 300072 (China)

solvent extraction;weathered;000;bioremediation;petroleum hydrocarbons;this stud

This study aimed to evaluate the efficacy, practicality and sustainability of a combined approach based on solvent extraction and biodegradation to remediate the soils contaminated with high levels of weathered petroleum hydrocarbons. The soils used in this study were obtained from the Shengli Oilfield in China, which had a long history of contamination with high concentrations of petroleum hydrocarbons. The contaminated soils were washed using a composite organic solvent consisting of hexane and pentane (4:1, v/v) and then bioremediated in microcosms which were bioaugmentated with Bacillus subtilis FQ06 strains and/or rhamnolipid. The optimal solvent extraction conditions were determined as extraction for 20 min at 25 degrees C with solvent-soil ratio of 6:1 (v/w). On this basis, total petroleum hydrocarbon was decreased from 140 000 to 14 000 mg kg(-1), which was further reduced to < 4 000 mg kg(-1) by subsequent bioremediation for 132 d. Sustainability assessment of this integrated technology showed its good performance for both short- and long-term effectiveness. Overall the results encouraged its application for remediating contaminated sites especially with high concentration weathered hydrocarbons.