title: Screening and evaluation of biosurfactant-producing strains isolated from oilfield wastewater.
abstract: The six biosurfactant-producing strains, isolated from oilfield wastewater in Daqing oilfield, were screened. The production of biosurfactant was verified by measuring the diameter of the oil spreading, measuring the surface tension value and emulsifying capacity against xylene, n-pentane, kerosene and crude oil. The experimental result showed three strains (S2, S3, S6) had the better surface activity. Among the three strains, the best results were achieved when using S2 strain. The diameter of the oil spreading of the biosurfactant produced by S2 strain was 14 cm, its critical micelle concentration (CMC) was 21.8 mg/l and the interfacial tension between crude oil and biosurfactant solution produced by S2 strain reduced to 25.7 mN/m. The biosurfactant produced by S2 strain was capable of forming stable emulsions with various hydrocarbons, such as xylene, n-pentane, kerosene and crude oil. After S2 strain treatment, the reduction rate of oil viscosity was 51 % and oil freezing point reduced by 4 °C.
authors.affiliation: Provincial Key Laboratory of Oil and Gas Chemical Technology, College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing, 163318 Heilongjiang China.
authors.forename: Jianghong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Provincial Key Laboratory of Oil and Gas Chemical Technology, College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing, 163318 Heilongjiang China.
authors.forename: Yitong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Life Sciences, Xiamen University, Xiamen, 361005 Fujian China.
authors.forename: Ruidan
authors.initials: R
authors.lastname: Xu
authors.affiliation: Provincial Key Laboratory of Oil and Gas Chemical Technology, College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing, 163318 Heilongjiang China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Jia
keywords: Biosurfactant; Critical micelle concentration (CMC); Emulsification activity; Interfacial tensions; Surface tension