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The Study Of Remediation Of Polycyclic Aromatic Hydrocarbons (PAHs)Contaminated Soil With Potassium Permanganate

Posted on:2016-10-20Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y ChuanFull Text:PDF
GTID:2191330473962993Subject:Environmental engineering
Abstract/Summary:PDF Full Text Request
With the increased awareness of the environmental protection and worsening conditions of eco-environment, the current station and the hazard of soil pollution are getting more attention in recent years. At present, the main attention of soil remediation is focused on the treatment of heavy mental in soil. And the oil and pesticides were regards as important pollutants in organic contaminated soil. The Polycyclic Aromatic Hydrocarbons (PAHs) are the difficult degradable organic pollutants with carcinogenic effects. Soil is medium which is the important to the accumulation and transfer of PAHs. That will threaten the ecosystem heavily and affect the health of human beings with food chain. So, it is important to find a reasonable and effective technology to remediate the PAHs-contaminated soil.This paper chose three typical PAHs as target pollutants that were Anthracene(Ant), Pyrene(Pry) and Benzo[a]pyrene(Bap), and potassium permanganate system was used to remediate the PAHs-contaminated soil. It is hoped to supply basic data for engineering projects.Firstly, the study of pretreatment of organic contaminated soil was learnt to optimize the process of ultrasonic extraction. Taking the soil sample freeze-drying from 4 to 24 hours, the recovery of PAHs was raised to 80.11%. The recovery of PAHs was 70.36% when the extraction time was set as 30 minutes that would get a better recovery as well as avoid the the trouble caused by high temperature during ultrasonic extraction. After making a further comparative study, the recovery of Ant, Pry and Bap were 94.55%,91.29% and 88.56% with soxhlet extraction, and by using ultrasonic extraction the recovery of Ant, Pry and Bap were 92.21%,85.24% and 80.22%, respectively. The results show that the recovery efficiency of soxhlet extraction was higher than ultrasonic extractions’. But the gaps of two extraction methods were close.Secondly, to provide evidence for subsequent experiments, this paper tested the theoretical demand of potassium permanganate per unit mass soil. And Soil Permanganate Index(SPI) of 28.12 grams of potassium permanganate per kilogram of soil was obtained with improved experimental method. Based on the SPI, the effect of ratio of water to soil, reaction temperature and reaction time on the removel yield of PAHs was investigated, respectively. Results show that when the ratio of water to soil was raised form 0.5 to 3.0, the reaction temperature was raised from 30℃ to 55℃ and the reaction time raised from 0.5 to 3.5 hours,the removel yield of PAHs were 67.76%,47.30% and 59.42%, respectively.On the basis of the results of SPI and above reaction factors, the uniform design method was used to study the effect of reaction factors on the removel yield of PAHs in further. A regression equation between the reaction conditions and removal yield of PAHs was established by using DPS (Data Process System) software. The results of three times random verifications implied that the regression equation owns a fitting error of less than 5%, which means the regression equation owning excellent ability of forecast. The results showed that the interaction of ratio of water to soil and reaction temperature is the most important factor for the potassium permanganate system. Moreover, the best condition of oxidation experiment was gained. It meant that when the ratio of water to soil was 3.2, reaction temperature was 60 ℃, reaction time was 5 hours and the dose of KMnO4 was 0.225 g KMnO4/10g soil, the removel yield of PAHs would maximize. The verifications experiment implied that with the parameters showed above the removel yield of PAHs reached 85.36%, that meant the goal of optimization was gained.Lastly, the ingredient of waste fluid came from the remediation of PAHs-contaminated soil by using KMnO4 was investigated by GC-MS. Results indicated that PAHs and other potential risk environmental pollutants were not detected in effluent after liquid-liquid extraction. And 2-methyl acetone might be the degradation product. In addition, the changes in pH value, organic matter content and soil particle size analysis were studied after the PAHs-contaminated soil oxidizing with KMnO4. The results conclude that the organic matter content was fell by 47.44%, but pH value and soil particle size had less changes after remediation.
Keywords/Search Tags:uniform design, potassium permanganate, polycyclic aromatic hydrocarbons, soil
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