A Study On Enhanced Microbial Remediation Of Pyrene Contaminated Soil By Aged Refuse

With the increasing use of petroleum and its products,a large number of polycyclic aromatic hydrocarbons(PAHs)produced in the process of oil exploitation,refining,transportation and combustion have become one of the most common hydrophobic and refractory organic compounds widely distributed in the environment.Remediation of PAHs contaminated soil has been a hot issue for experts and scholars.The aged refuse is a very superior biological medium,which can provide excellent microbial living environment for the degradation of pollutants in the soil,and is suitable for the degradation of heavy metals and toxic organic matter in the soil.Therefore,this paper chooses pyrene as the soil contaminant.Through the data collection,laboratory simulation experiment and data analysis,studying the effect of aged refuse on the remediation of pyrene-contaminated soil and the mechanism of aged refuse enhanced microbial remediation of pyrene-contaminated soil.Aged refuse enhanced microbial remediation PAHs contaminated soil provide theoretical basis and technical support.The main research conclusions are as follows:1?Experimental study on remediation of contaminated soil with different concentrations of pyrene by aged refuseshow that:(1)Degradation kinetics of pyrene with different concentrations in the soil followed first-order kinetics.Whenthe concentration of pyrene was 200mg/kg,the degradation rate and degradation rate constant were the largest,the half-life was the shortest,and the degradation rate constant and half-life were0.0252 d-1 and 27.51d,respectively;(2)Different concentrations of pyrene had no significant effect on the activity of FDA hydrolase;(3)At the stage,the activity of polyphenol oxidase was inhibited significantlywhentheinitial concentration of pyrene in the soil was 400 mg/kg;(4)Different concentrations of pyrene caused certain toxic effectson growth of wheat seeds,but had no obvious effect on the wheat seed germination rate;theroot and stem elongation of wheat seeds inhibition rate was positively correlated with the concentration of pyrene;According to the ecological toxicity index of wheat seeds,the bioremediation result was best with aged refuse addition when the initial concentration ofpyrene in the soil was 200mg/kg.The best remediation concentration of mineralized refuse for pyrene contaminated soilwas 200mg/kg;(5)200mg/kg is the optimum concentration of pyrene-contaminated soil in this study.2?The results of different treatments of pyrene contaminated soil show that:(1)The activity of FDA hydrolase and polyphenol oxidase in CK3 group(adding aged refuse)and CK2 group(adding sterilized aged refuse)were higher than CK1 group(Purely contaminated soil)and CK4 group(adding exogenous nutrients),The activity of FDA hydrolase in soil of CK3 group was higher than that of CK2 group,which indicated that the microbes in the aged refuse had a significant effect on the improvement of soil FDA hydrolase activity;(2)Thegermination rate of wheat seeds in the four treatment groups did not changebefore and afterthe bioremediation,indicating that adding aged refuse did not affect the germination rate of wheat seeds.Beforethe restoration,the inhibition rate of root elongation and stem elongation of CK3 group were significantly lower than those of other treatment groups,and both of them showed the promotion of root and stem elongation,the germination index was also higher than that of other treatment groups,indicatingthat aged refuse in the early restoration of the soilto show the role of the reduction of soil toxicity,root and stem growth also on the mineralized soil system to adapt to the state;(3)The degradation rate and degradation rate constant of pyrene in CK3 group was higher than other treatment groups,andthe half-life was the shortest;(4)The addition of aged refuse significantly changed the community structure of microbes,increased the total number of bacteria,fungi and microorganisms,increased the richness and diversity of bacterial communities,but reduced the diversity of fungal communities and there is no significant effect on the fungal community structure.This study can broaden the ideas and ways of soil organic pollution remediation and provide guidance for pyrene-contaminated soil remediation.