Screening And Degradation Characteristics Of Bacteria For The Remediation Of Petroleum Hydrocarbon Pollutants Under Arsenic Stress

Petroleum products are the main energy for industrial production and daily life,which not only bring benefits to human beings,but also pose a serious threat to soil environment.Petroleum hydrocarbon is the main pollutant in petroleum.The area of petroleum hydrocarbon contaminated soil in China is nearly 4.8 million hm².Petroleum hydrocarbon pollution in soil has become an urgent environmental problem to be solved in the remediation of organic contaminated sites.As heavy metal-organic complex pollution is the most common in actual contaminated sites,it is of great engineering significance to carry out remediation research on complex contaminated sites.In this study,the soil of an arsenic-petroleum hydrocarbon complex contaminated site in Hubei Province was isolated and purified,and the bacterial species were identified by 16S r DNA sequencing technology.The growth and degradation characteristics of the degrading bacteria were analyzed,and the remediation effect of degrading bacteria on the complex contaminated soil was verified.The main conclusions are as follows:（1）Seven strains of petroleum hydrocarbon degrading bacteria were isolated under arsenic stress using diesel as the only carbon source.After 16S r DNA sequence analysis,They were identified as Acinetobacter sp.,Pseudomonas.aeruginosa,Acinetobacter.Baumannii,Acinetobacter.Junii,Acinetobacter.Oleivorans,Delftia.tsuruhatensis and Chryseobacterium.Hungaricum.Among them,strain JYZ-03 has the highest degradation efficiency of petroleum hydrocarbon,so it is selected as the main research object.（2）The degradation rate of JYZ-03 to petroleum hydrocarbon was 84.05%after7 days of culture in MSM medium containing 1%diesel oil.The optimum growth conditions were p H 7,30℃,salinity 0.1%and initial inoculation amount 2%.Pb²⁺had a certain effect on the degradation of petroleum hydrocarbons.When the concentration of Pb²⁺was lower than 75 mg/L,the degradation efficiency of petroleum hydrocarbons did not change significantly.When the concentration of Pb²⁺was higher than 75 mg/L,the degradation efficiency decreased significantly.As（V）has no significant effect on the degradation of petroleum hydrocarbons,and there is no significant difference in the degradation rate in the range of 0～300 mg/L.（3）The degradation efficiency of JYZ-03 was different for different carbon paraffins.The degradation rate of middle and long carbon chain n-alkanes in diesel oil is the highest,in which the degradation rate of middle carbon chain alkanes(C₁₁～C₂₅)is 75%-100%,the degradation rate of long chain alkanes(C₂₆～C₃₈)is3.11%～17.55%,the degradation rate of branched alkane is 63.18%and phytane is70.52%,respectively.The degradation rates of naphthalene and phenanthrene were36.62%and 26.71%,respectively.The degradation rate of JYZ-03 and JYZ-04strains was higher than that of JYZ-03 single strain,which showed a synergistic effect.The higher the concentration of petroleum hydrocarbons,the more obvious the coordination effect.（4）Strain JYZ-03 has good bioremediation effect on soil contaminated by petroleum hydrocarbon.The content of residual petroleum hydrocarbons was less than 1000 mg/kg after 30 days of remediation for the single contaminated soil and arsenic-petroleum hydrocarbon combined contaminated soil with petroleum hydrocarbon concentration of 4103.88 mg/kg and 4342.95 mg/kg,respectively.In the process of petroleum hydrocarbon degradation,catalase activity increased first and then decreased,and reached the highest value after 16 days,while dehydrogenase activity decreased gradually with the extension of restoration time.