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Bioremediation of Crude Oil Contaminated Soil with Immobilized Microorganism

Author: HuWenWen
Tutor: XingBaoShan
School: Ocean University of China
Course: Environmental Science
Keywords: Immobilized Soil Oil pollution Microbial Remediation Indigenous degrading bacteria
CLC: X53
Type: Master's thesis
Year: 2010
Downloads: 234
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Abstract

In oil exploration and mining, transportation, storage and refining process, inevitably there will be a large number of crude oil and crude oil products spilled or leaking on the ground, resulting in a large area of ??oil pollution of the soil, causing serious harm to the ecological environment. Petroleum hydrocarbon substances with high biological toxicity, the residual long time in the environment and harm the growing concern how to effectively repair a contaminated environment. Microbial remediation of low-cost, on-site treatment of contaminated soil or water, to minimize the concentration of pollutants and adverse environmental impact, more and more research in this area. Especially in the study of how to improve the effectiveness of degrading bacteria has become a hot spot of international research. Therefore, improving the reproductive efficiency and ease of agents magnify the production and preservation of hydrocarbon degrading bacteria in the soil, transportation, take the microbial immobilization approach is important. Long-term oil-contaminated soil from the Yellow River Delta in domesticated enrichment crude oil has good degradation effect indigenous hydrocarbon degrading mixed strains in liquid medium containing a high concentration of crude oil the tested bacteria Department for crude oil resistant and Degradation ability by separating the pure culture, the three dominant strain was identified were: Corynebacterium (Microbacterium foliorum), eat-alkanes the Gordon the bacteria (Gordonia alkanivorans) and the Mesorhizobium (Mesorhizobium) the four natural polysaccharide carrier material degradation petroleum hydrocarbon mixed strains prepared as immobilized particles, by the difficulty of preparing immobilized particles, the mechanical strength, mass transfer resistance and other properties of the test, and ultimately select the operation simple and mechanical strength and mass higher quality alginate as vector Celite was added, and sodium alginate in order to improve the mechanical strength and mass transfer resistance of the immobilized particles, through the determination immobilized reaction time influence on the microbial activity of the immobilized particles The preparation conditions of the immobilized particles, and ultimately determine, i.e. using celite solution of 6% sodium alginate -2% (w / v) as the carrier, with an equal volume of physiological saline suspension of the degrading bacteria mixed with acid burette Hourly drops into 0.1 M CaCl2 solution, the immobilized reaction 12h, measured and this method has a higher immobilization efficiency of 92.25%. using scanning electron microscopy to observe the microscopic structure of the immobilized particles, the interior of the particle was a cellular network like structures, most degrading bacteria are entrapped in the pores within the attached growth, the particle porosity abundant, conducive to the transmission of oxygen, moisture and substrate, immobilized bacteria and to be able to provide sufficient space to grow, its carrier within growth and reproduction of favorable conditions. Three inoculum size diatomite alginate immobilized particles and sodium alginate immobilized particles added to the crude oil crude oil contaminated soil degradation experiments, adjust the soil moisture and N and P content to the desired level, respectively, the same vaccination free of bacteria as a control. The results showed that the degrading bacteria immobilized bacteria significantly higher than the equivalent amount of bacteria free Degradation of advantages, especially in the beginning of the experiment, inoculated with bacteria immobilized soil TPH degradation rate in the experiment of 20 days had reached 27.29% , 29.83% and 27.56%, respectively, higher than the the same inoculation amount of free bacteria 12.43%, 10.10% and 6.43%, the number of degrading bacteria in the soil Add immobilized bacteria than adding free bacteria soil orders of magnitude higher than the 1.20 to 1.53 . Low inoculum size immobilized bacteria (IL, group) and reflects the high and vaccination amount of free bacteria (FH group) stronger degradation advantage, 20 days, the degradation rate of the former than the latter up 6.1%; 30 days, each experimental group the number of degrading bacteria and microbial activity to stabilize crude oil degradation rate tends to slow. In addition, the carrier will not damage the soil structure, suitable for long-term large area of ??petroleum contaminated soil on-site repair. By preliminary test on the the immobilized particles preservation conditions, the immobilized degrading bacteria at 4 ℃ were stored in sterile water and three protective agents 20% skim milk, 20% glycerol, liquid paraffin, results show that sterile Water is the best storage media, can maintain the biological activity and particle traits degrading bacteria in at least three weeks. The results of this experiment immobilized microorganisms in the large-scale soil restoration application provides a new theoretical basis.

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CLC: > Environmental science, safety science > Environmental pollution and its prevention > Soil Contamination and Control
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