Degradation Characteristics And Repair Technology Of Petroleum Hydrocarbons In Soil

The oil spill in the process of mining,transportation and refining will cause serious pollution to the ecological environment.When the oil pollutants exceed the environmental load,the contaminated soil cannot function as a normal self-cleaning function,and the accumulated petroleum hydrocarbons will eventually cause harm to humans through the food chain.Microbial remediation is an environmentally friendly,practical and efficient pollutant treatment technology.It has many advantages such as simplicity,economy and no secondary pollution.It has become the main technology for the repair of oil-contaminated soil at home and abroad,and has broad development.prospect.The paper studied oil-contaminated soil in northern Shaanxi as a research object,and studied the removal of petroleum hydrocarbons in soils with different organic matter content and fine sand without organic matter.The results show that the "adsorption lock" effect of soil organic matter on petroleum hydrocarbon pollutants is the main reason for the slow degradation rate of petroleum hydrocarbons in the later stage of oil-contaminated soil remediation by microbial methods.Separate oil and polycyclic aromatic hydrocarbons were used as the sole carbon source,and 9 petroleum hydrocarbon degrading bacteria were selected from petroleum contaminated soil by enrichment culture and plate scribing separation method,numbered T1,T2.....T9;and 7 strains.Polycyclic aromatic hydrocarbon degrading bacteria,numbered P1,P2.....P7.The degradation performance of the selected functional degrading bacteria was determined by 15 d liquid phase degradation experiments.The results showed that the degradation rate of total petroleum hydrocarbons in the aqueous phase of 9 petroleum hydrocarbon degrading bacteria was between 31.25 and 39.35%.Good degradation effect;the degradation rate of polycyclic aromatic hydrocarbons in the aqueous phase of the 7 polycyclic aromatic hydrocarbon degrading bacteria was between 23.11 and 82.7%,and the P1,P3 and P7 strains were stable and efficient in the degradation of polycyclic aromatic hydrocarbons.The nine petroleum hydrocarbon degrading bacteria selected were all Sphingobacterium sp.,and the three polycyclic aromatic hydrocarbon degrading bacteria were all Curtobacterium sp.A laboratory simulation study on oil-contaminated soil was carried out using a nutrient droplet irrigation method.The results show that the drip irrigation of regular nitrogen and phosphorus nutrient solution can better remove petroleum hydrocarbons in the soil.After 150 days of repair,the removal rate of petroleum hydrocarbons can reach 53.53%.The effect is better than the one-time supplementation of nitrogen and phosphorus nutrient solution(150 d petroleum hydrocarbon removal rate is 31.96%).The results of high-throughput sequencing showed that the abundance of actinomycetes in the soil of drip irrigation nutrient solution increased,and the abundance of Proteobacteria,Acidophilus,Bacteroides and thick-walled bacteria decreased.At the genus level,drip irrigation increased the relative abundance of Nocardia and Rhodococcus.Drip irrigation of nitrogen and phosphorus nutrient solution into petroleum-contaminated soil can cause significant changes in soil microbial community structure and diversity.The biodegradation effect of petroleum hydrocarbons is positively correlated with the soil microbial richness,and the uniformity of the flora has little effect on the degradation of petroleum hydrocarbons.