Study On Capability And Effect Of Biosurfactant On Off Shore Petroleum Degradation

Three biosurfactant-producing positive strains are screened from surface sludge of the aeration tank in Guangzhou petroleum chemical plant and secondary sedimentation tank in Liede sewage treatment plant, namely S5 S6 and S10. S5 and S6 are identified as Pseudomonas sp., S10 as Bacillus sp..The results indicate that: temperature 20℃-30℃, initial seeding dosage 2%, and pH 8-9 are the optimal conditions for S6 to produce surfactant. Addition of MgCl₂ (1.0%) is propitious to biosurfactant production, and glucose and peptone are the best tested C and N sources for inducement of biosurfactant production. The orthogonal experiment results show that, the optimal culture ingredients for cell mass and biosurfactant production are: glucose 20g/L, NH₄NO₃ 10g/L, KH₂PO₄ 4g/L, NaCl 10g/L, pH7.0-7.5; glucose 10g/L, NH₄NO₃ 2g/L, KH₂PO₄ 2g/L, NaCl 5g/L, pH8.0 respectively.After 14d 4℃ conservation, oil displacement activity of the centrifuged culture is fairly strong. And after 30min water bath (50-90℃), the surfactant activity of the culture is maintained at about 60% contrast to the control group. The upper foam surfactant activity is stronger than the culture ifself, but its lasting period is quite short.After 20d biodegradation, in the co-addition group of PDB and centrifuged surfactant culture, petroleum degradation rate in the simulated seawater can achieve 72%, and 78% in the freshwater. It is also suggested that, addition of centrifuged surfactant culture or S6 cell mass can alter petroleum distribution in the simulated coast.Patterns of ultraviolet spectrophotometer indicate that, complicated compound with wavelength 220nm-260nm and 380nm-450nm is effectual component for the biosurfactant. Surface active matter maintaining the stability of surface activity locates mainly within the cell or on the surface of the cellular wall. There is no obvious inhibition for strain growth and fissiparism deriving from the biosurfactant.