Study On Biodegradation Characteristics Of Petroleum-contaminated Soil In Permafrost Region Of Qinghai-Tibet Plateau

It is of great significance to explore the mechanism of petroleum hydrocarbon bioremediation in low temperature and cold environment for the ecological environment treatment and protection in permafrost regions.Based on the petroleum hydrocarbon pollution in the permafrost regions of the Qinghai-Tibet Plateau,this paper mainly studies the biodegradation characteristics and enhanced treatment technologies of petroleum hydrocarbon pollutants in frozen soil areas by constructing low-temperature and high-efficiency petroleum hydrocarbon-degrading functional microorganisms.The indoor simulation experiment of bioremediation of petroleum hydrocarbon contaminated soil was carried out.The main research results are as follows:1.Petroleum hydrocarbon pollutants have significant effects on the composition and structure of microbial communities in plateau permafrost regions.The community diversity of petroleum-degrading functional bacteria in petroleum-contaminated soils is higher than that in background soils.High-throughput sequencing results showed that the bacterial community composition was similar in the background soil samples?TS and MS samples?.Relatively speaking,the bacterial community structure of petroleum hydrocarbon contaminated soil samples?SDO and SLO samples?was significantly different;The abundance of bacteria in the contaminated soil sample?SLO?was the highest,followed by the background soil sample,and the bacterial flora in the diesel contaminated soil sample?SDO?was the lowest.2.The results of the degradation test of petroleum hydrocarbons?diesel,engine oil?showed that the low-temperature petroleum hydrocarbons?diesel,engine oil?initially constructed had higher activity in degrading symbiotic bacteria,and higher for petroleum hydrocarbons at low temperatures.Degradation performance.The study showed that the cumulative degradation rate of diesel oil reached 63%after 20 days at low temperature of10°C,and the degradation rate was 52.75%after 30 days of oil test group.3.The laws of biodegradation of petroleum hydrocarbons?diesel,engine oil?are similar.At the beginning of the experiment,the average degradation rate of petroleum hydrocarbons?diesel,engine oil?was higher than that at the end of the experiment.The degradation of low-carbon hydrocarbons was relatively higher than that of complex high-carbon hydrocarbons;the organisms of experimental microorganisms for petroleum hydrocarbons?diesel,motor oil?most of the degradation kinetic equations conform to the first-order reaction kinetics model.At low temperature of 10°C,the degradation rate of petroleum hydrocarbons with higher concentration is smaller and the half-life is relatively longer.The degradation rate constant of diesel bacteria is greater than that of oil bacteria.The bioremediation cycle of diesel pollution is shorter under the same environmental conditions.4.The application of additives such as electron acceptor?H₂O₂?and surfactant?Tween-80?has significant effects on the degradation of petroleum hydrocarbons?diesel and motor oil?.The effects of different additives on the degradation performance of petroleum hydrocarbons have difference.Lower concentration of H₂O₂ strengthens the biodegradation of petroleum hydrocarbons?diesel,engine oil?,high concentration of H₂O₂ inhibits the degradation of petroleum hydrocarbon microorganisms;Tween-80 with too high or too low concentration weakens petroleum hydrocarbons?diesel,engine oil?degradation effect,suitable concentration of Tween-80 promotes the biodegradation of petroleum hydrocarbons?diesel,motor oil?;the application of immobilized microbial agents enhances the effectiveness of microbial degradation of petroleum hydrocarbons,and the immobilization of different materials to petroleum The degradation effects of hydrocarbons are different.Among the immobilized microbial agents in this experiment,activated carbon filter cotton fixed bacteria had the best degradation effect on petroleum hydrocarbons?diesel and motor oil?,followed by wheat straw fixed bacteria and chemical fiber spinning fixed bacteria.5.Humidity and nutrient ratio have a significant impact on the degradation of petroleum hydrocarbons?oil?.The soil moisture content of too high or too low inhibits the biodegradation of petroleum hydrocarbons?oil?,and the suitable soil moisture content enhances the biodegradation effect of petroleum hydrocarbons?oil?;the nutrient salt of lower nitrogen to phosphorus ratio helps microbes to oil Biodegradation of hydrocarbons.After 60d test,when the design moisture content is 25%,the degradation effect of oil is the best.When the water content of this test is higher or lower than 25%,the degradation rate of soil petroleum hydrocarbon?oil?is reduced;the ratio of test nutrient salt is N/P=6,the degradation rate of the oil is the largest,and the improvement of the nutrient level of the test soil enhances the biodegradation of petroleum hydrocarbons?oil?.6.Through the indoor simulation test of petroleum hydrocarbon?oil?contaminated soil bioremediation,it is verified that the oil-degrading functional microorganisms constructed in this study have the application potential of field test;the conditioning agent and the tillage of soil petroleum hydrocarbons?oil?Degradation has a promoting effect.