Study On Degradation Characteristicsand Immobilization Of Bohai Gulfdiesel Degradation Microorganisms

With the development of oil industry and the prosperity of the marine transportation, oil has caused severely polluted for marine environments. In order to get rid of the oil from the marine environment, scientists from many countries have sought the safe and high efficiency techniques. Currently, the common remediation methods for oil pollution include physical, chemical and bioremediation technique. Bioremediation is a method using living microorganisms to remove organic pollutants and it is a cost-effective, high efficiency and environmentally friendly approach to disposal polluted sites. Therefore,more and more researches studies on bioremediation. Microbial fuel cell(MFC) was a new type of fuel cell device that can degradation of organic matter by microorganisms, and it is possible to generate electricity using bacteria while accomplishing waste water treatment. Microorganism immobilization technology is conductive to the storage, transportation and application of diesel degradation bacteria, therefore it has potential development prospect in the bioremediation of various pollutants.The microbial fuel cells were constructed firstly using Bohai Bay mud as the microbial source in this paper. The MFC’s maximum voltage was 363 m V. The strains were isolated from the anode surface of MFC using separation and purification methods with three enrichment medium(2216E、SRB、LB), 21、26 and 15 single strain were screened, respectively.Secondly, isolated the diesel degrading bacterial from marine sediment samples.We enrichment of the sample in a culture medium with diesel oil as sole energy and carbon source, and obtained three strains(L5、E2). Determination of the nucleotide sequence showed that three isolated strains closed to the genera of Arthrobacter. Meanwhile, the growth characteristics of the strains were tested. The result showed that the optimal growth conditions for three strains: temperature 25-30 °C, p H 7.5-8, salinity 2-3 %.The study was undertaken to assess the single factor for biodegradation of diesel, included of concentration of diesel、p H、temperature and the effects of salt concentration. The result showed that the optimum conditions of strain L5 were 25 °C, p H 7.5 and 3 % salt concentration; strain E2 had the best biodegradation under the conditions as below: 30 °C, p H of 8 and 3 % salt concentration. According to single factor experiment and orthogonal experiment, the strain L5 degraded a maximum of 49.14 % the diesel oil. This was followed by 46.47 % by E2.The immobilizing of screened strain was researched further in this study. This study is based on Artemia cyst shell as adsorption carrier, sodium alginate as the embedding material to prepare a size of 3-5 cm immobilized microorganisms. The microstructure of artemia cysts shell with strains was characterized and the mass transfer of the immobilized particles prepared under different conditions was also analyzed. The result showed that artemia cyst shell have good load for bacterial, and the immobilized particles with artemia cyst shell had greater mass transfer than the particles without artemia cyst shell. The experiment revealed that the immobilized microbial cells degradation rate(45-50 %) were greater than the free cells(40-45 %).