Remediation Of Soils Highly Contaminated By Polycyclic Aromatic Hydrocarbons By Using Biodiesel Leaching And Microorganisms

Polycyclic aromatic hydrocarbons(PAHs)are a class of ubiquitous persistent organic pollutants in environment.They have done harm to human health.Most PAHs are hydrophobic compounds because of their low water solubility,special physical properties and electrochemical stability.Hence,they can exist and be accumulated in soils.Soil contaminated with PAHs is a common environmental problem in many countries.Therefore,the remediation of soils contaminated with PAHs is an urgent task.Ultrasonic and vibration extraction were used as two kinds of sample extraction pre-treatment methods.of samples purified,silica gel column and organic membrane purification methods were used to purify samples before entering the chromatographic analysis.This study used biodiesel,which is novel as a washing agent, to remediate the highly contaminated soil and the spiked soil contaminated with high PAHs.For comparison,this study also chose methanol and soybean oil as washing agents.Mixed degrading bacteria have been adopted to remediate the polycyclic aromatic hydrocarbons contaminated soil.The results show that:Ultrasonic extraction and vibration were of no significant difference between the sample extract pre-treatment results.Two kinds of purification methods can clean sample and reduce the impurity peak-to-interference analysis of polycyclic aromatic hydrocarbons well.Biodiesel has a higher removal rate on polycyclic aromatic hydrocarbons than removal rate of chosing methanol and soybean oil as washing agents in the contaminated soils.For the high concentration of artificial contaminated soils,the removal rate can reach more than 68%,For the gas plant, the removal rate can reach at 21%～70%. Leaching with biodiesel is effective to PAHs with high molecular weights.Leaching with biodiesel to remove polycyclic aromatic hydrocarbons in the soils is feasible.After ten weeks of degradation, total degradation rate to soils contaminated by polycyclic aromatic hydrocarbons can reach at 40% or more, which shows screening bacteria is a very effective mixture of polycyclic aromatic hydrocarbons degrading bacteria.With the rings increasing in the number of polycyclic aromatic hydrocarbons, microbial degradation efficiency becomes lower.The more rings of polycyclic aromatic hydrocarbons and the greater toxicity, bio-availability is lower.