| In the process of petroleum producing, store transport, refine processing and using,because of the reasons of accident, not normal operation and overhaul and so on, there willhave petroleum hydrocarbon spilling over and emission, which inevitably result inenvironmental pollution. Remediation of contaminated environment is imperative. Microbialremediation technology is an efficient, safe, low cost remediation technology on oil pollution.But free microorganism in susceptible to external factors in the actual environment pollution.it is difficult to give full play to the role of degradation. Immobilization technology formicroorganism can effectively shield the indigenous bacteria competition and protect againstexternal adverse factors through the microbial immobilization in independent microenvironment, thus improving the degradation rate of petroleum pollutants.so it has enormouspotential.In this thesis the environmental friendly immobilized bacteria and its effect on removalof oil were studied, including screening degradation strains, optimization of growthconditions; selection of immobilization carrier, optimization conditions of immobilizationand oil removal effect of immobilized microorganism, etc.1) Crude oil from Shengli oil field adopted the four component analysis, the results wasas follows:33.2%saturated hydrocarbon,30%aromatic hydrocarbon12.1%asphaltene and24.7%, A, the oil is heavy crude oil, because of the relatively higher content of asphaltenesand colloid. Content determination of total petroleum hydrocarbons was measured by UVspectrophotometry method and gravimetric method. The two methods have good accuracyand precision, the recoveries were101.6%±2.0%method was used for aromatichydrocarbons in petroleum hydrocarbon. Aromatic components show the characteristicabsorption in the ultraviolet region, the absorption intensity is proportional with the contentof aromatic hydrocarbons. The composition of petroleum hydrocarbon is more complex.Microbial degradation of petroleum hydrocarbon was studied in this paper. Consideringthatthe complex composition of petroleum hydrocarbon, the uncertainty of biodegradationmechanism, the differences in the degradation degree of the oil components, in order to fully characterized the changes in total hydrocarbon usingmicrobial degradation, the gravimetricmethod for determination of total petroleum hydrocarbons was adopted in this thesis.2)According to the domesticationd and screening of petroleum hydrocarbon degradingstrains1#、2#、R5preserved in our laboratory we found that oil degrading strain2#has betterdegradation effect than others. We then logically optimized the conditions by exploring theeffects of salinity, pH and other conditions affecting their growth. The optimum conditionsfor the target strains growthshows that: The growth condition of pH at6.0-8.0; the approprtepH was7.0; the growth condition of concentration of salt(NaCl)between0.25%-1.5%aregood, the optimum concentration is0.5%can grow in; the optimum is, the optimum growthcell age is16h, the optimum degradation time is4-5weeks.3)immobilization methods:100mL medium containing immobilized materials wascarrier into the conical flask(250mL)5%target bacteria was inoculated in the medium afteractivation, the conical flask was placed in shakinge table for appropriate hours, Theprecipitate was collected by centrifugation, the lower sediment was washed with saline2times to affoed the desiredimmobilized bacteria get. The evaluation of preparation conditionsof immobilized microbial agent are as followsThe immobilization of oil degrading strain2#on a variety of carrier by absorption hasbeen studied.The oil removal rate of pine needles (oil removal rate of37.5%) and thecorresponding biological activated carbon(oil removal rate43.5%) is better than that of corncob(corn cob microbial oil removal rate of32.7%) and the corresponding biologicalactivated carbon(the corn cob charcoal agent oil removal rate of40.5%) The grass(grassagent oil removal rate of28%) peat inoculants oil removal rate of34%is the worst material;The oil removal effect of biological carbon agent is better than that of its precursor. Becausethe corn cob is easier to obtain, we choose corn cob for the following study onimmobilization parameters. The microorganisms agents washing with saline(corn cob agentoil removal rate of34.2%) the corncob charcoal agent oil removal rate of38.9%is betterthan those without washing(corn cob agent oil removal rate of26.5%) the corncob charcoalagent oil removal rate28.1%the optimum burning temperature is300°C, and the optimumlength of time is4hours.(oil removal rate was45.6%) The optimum carrier’spercentage(carrier quality/medium volume) is6%(oil removal rate of33%) the effect of other percentage is pooer(2%oil removal rate of28.1%),0.5%oil removal rate of28%;1.5%oil removal rate of27%;2.5%oil removal rate of19.4%;3%oil removal rate of16.8%;3.5%oil removal rate of16.8%. the smaller the particle size of carrier is, the higheroil removal rate is(less than200) mesh(oil removal rate of48.4%)>80-200mesh(oilremoval rate of42.6%)>30-80mesh(oil removal rate of38.9%)>30mesh(oil removal rateof33.9%).The optimum length of immobilization time was18h (oil removal rate of47.6%), the oilrate of other length(6h,12h,24h,36h,48h) is worse effective(32.8%-40.0%). The optimalspeed of shaker is160rpm(oil removal rate of50.7%) compared with other speed(80rpm(40.5%),120rpm (45.4%),200rpm(46.4%), the best immobilization temperature is30°C(oil removal rate of47.6%), the other corresponding temperature and their oil removal ratewere as follow:15°C (40.5%)，20°C (42.8%),25°C (44%),35°C (47.4%),40°C (43.4%).4)The optimum immobilized microorganism agent is obtained that: the carrier usingcorncob activated carbon, the size of smaller than200meshes, the carrier’s percentage of1g/100mL, immobilized time length of18h,160rpm,30°C, washing with saline.Thedegradation rate of5g/L crude oil medium in one week is47.6%under the optimumcondition, the microbial quantity of microorganism agentis5.8×109CFU/g. |
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