Primary Study For Petroleum Pollutants Biodegradation And Biosurfactant Production

In the process of crude oil extraction and refining, large quantities of petroleum pollutants were produced, it is estimated that 10~9 tons petroleum was poured into underground water, ground water and soil through various approach in one year. Petroleum pollution bring a great danger to ocean fishery resource, destroy the natural structure of soil and affect the ecological balance.Bioremediation of petroleum pollutants possessed such merits as low cost, good effect and no second contamination. Many developed countries have applied such method into petroleum pollutants decontamination, this method also should be a good choice in our courtry in petroleum pollutants decontamination field.In this study, a excellent degradation bacterium was obtained from crude oil contaminated soil, its degradability to crude oil was investigated in water and soil slurry status, the experimental results showed that: (1) it was a high efficient petroleum degradation bacterium, it can endure 20g/L petroleum concentration, the degradation effect was remarkably, in very acid and alkali environment, the degradation rate was 66.1% in pH9.0. (2) the bacterium degrade saturates, aromatics and resin very well, degradation rate of such three components was similar each other, it was 42.95%,43.85%,44.5% respectively in 18 days, while asphalt degradation rate was only 5.55% in the same time. (3) the degradation rate reached 55.81% with high crude oil as sole carbon source which contain 63.5% resin and asphalt at 30℃ in pH9.0. (4) in 100g petroleum /Kg soil concentration, the degradation rate was 38.85% in 45 days, the degradation effect was obviously, this bacterium is one of the best degradation bacteria found nowadays.During degradation period, petroleum was emulsified obviously, according to such phenomenon, further studies were carried out. The results showed that: (1) the bacterium produced biosurfactant in the process of degradation and surface tension decreased greatly, after 12 days degradation, surface tension decreased to 45. 59mN/m from initial 71. 5mN/m. (2) the biosurfactant was glycolipid type which was consisted of monosaccharides, disaccharides or trisaccharides group and fatty acid group which were combined by ester bond. (3) glycolipid biosurfactant can decrease oil-water interfacial tension greatly after it was recombined with other chemical additives, the emulsification capability of such glycolipid was excellent. (4) inoptimal condition, the biosurfactant concentration can reach 2.2g/L in 150h with 20g/L tetradecane as sole carbon source, the biosurfactant concentration was stable at 165~220mg/L with 20g/L crude oil as sole carbon source. The bacterium can better adapt to environment and the glycolipid was a high efficient surfactant, if the molecule configuration of this surfactant was ascertained and its yield was further improved, it has a great hope to be used as detergent or be used in microorganism enhanced oil recovery field, etc.