Screening Of The Predominant Bacteria For Degradation Of Petroleum And Studying Of Their Characters

Petroleum pollution is one of the most biggest environmental problems in the world. The methods and techniques for removing these pollutants from our environment have been developed by many researchers. So far, bio-methods, especially bioremediation, is known as the most efficient technique, with the advantages of high efficiency, economic, free of second pollution and wide application compared with other chemical and physical treatments. Therefore, the study on bioremediation of oil-pollutants is bound to be useful.This paper has show up some of the important information about petroleum pollution and corresponding methods for removing petroleum from environment, especially, there is more detailed information about the petroleum biodegradation method. Based on the above information , it is clear that to purifying petroleum from environment, the important thing is to get good strains and to understand their degradation characters,then we can use them in pratical treating engineering. So, screening petroleum strains from environemt samples and studying their degradation characters are the main content of this thesis.A group of predominant strains for decomposing oil have been isolated from the oil-polluted soil, which can be cultivated only with the petroleum as the sole carbon source;we selected four of them and a group of mixed strains for further study. Experiments have been carried out to abtain the best conditions for petroleum degradation in the laboratory;we study the influence of various factors on the degradation of petroleum in slurry bio-reaction;the tentative experinment for remediation of the oil-polluted soil have also been carried out.Four predominant strains and a group of fixed strains for decomposing oil have been isolated from the oil-polluted soil of some oil field in ShanBei, experiments have been carriedout to study their degradability in the laboratory, the main results of this paper are listed as following: pH is a very important environmental factor for the growth of microorganisms, the strains are favorite of the moderate or alkalescence condition. Inorganic ions play very significant roles in the degradation of oil by microorganisms, the removing rate of petroleum is 38.40% when the bacteria \# exists, which is 14.35% higher than the comparison. The role of microelements is complicated, including accelerating effects and restraining effects. Mn2+ has obvious accelerating effects on the degradation by bacteria 3 , the removing rate of petroleum is 38.12%, but has restraining effects on the degradation by bacteria 3#, the removing rate of petroleum is 31.86%, the removing rate of the comparison is 33.27%. The slurry bio-reaction results show that the factors have different influences on the biodegradation of oil, the order of the degree of influence is: the quality of nitrogen, pH, the quality of phosphor, the species of microorganisms, the intensity of pollutants;the most suitable level of the factors are: the intensity of pollutants=3%, the initial pH=6, the species of strain is 3#, C:N=100:3, C:P=100:0.6. The result of the remediation on the oil-polluted soil inoculated the naturally mixed strains suggests that the quality of oil in soil declined significantly in the room temperature after 47 days, the removing rate of petroleum is35.38%, the removing rate of the comparison is 26.80%;the removing rate of petroleum of the sample inoculated assembled bacterias is 36.88%, while the removing rate of the comparison is 26.66%. The result of the experiment shows that the screened bacterias have good effects on the removing of petrolenm-pollutants in the appropriate conditions, which has reference meaning to the actual bio-remediation of petrolenm pollutants.