Research On Remediation Of Petroleum-contaminated Soil By White-rot Fungi

The 12d degradation rate of crude oil in the medium was chosen as the objective of the study through single factor experiment,in order to study the effect of culture conditions?temperature,table speed,inoculation amount,pH?and ingredients of medium(natural material leachate,Cu²⁺,Mn²⁺,guaiacol)on the degradation of crude oil by white-rot fungi,and determine the best culture conditions and ingredients of medium which were suitable for the degradation of crude oil by white-rot fungi;Based on the conclusion above,designing experiment scheme by single factor experiment and response surface method,to further explore the influence of NH₄NO₃ concentration,Tween80,sawdust ingredient amount,H₂O₂on the degradation of crude oil by white-rot fungi,and determine the best degradation conditions combination of the highest degradation rate in the medium;Flowerpot experiments were used to simulate the in-situ remediation of oil contaminated soil by white-rot fungi,in order to study the influence of moisture content,surfactant,sawdust,salt concentration,plowingfrequency,pH on remediation effect of oil contaminated soil by white-rot fungi,and obtain the best environmental conditions of soil which were suitable for the remediation;By regularly measuring soil crude oil content,breath intensity,enzyme activity,bacteria,fungi,actinomycetes number,the white-rot fungi effects on the biological characteristics of soil and the correlation between crude oil degradation rate and biological characteristics were studied,in addition,white-rot fungi and indigenous bacteria interactions could also been analyzed.The results show that:?1?When 10g/L sawdust leachate,0.3mmol/L Cu²⁺,0.4mmol/L Mn²⁺,0.9mmol/L guaiacol was added in medium,and the culture conditions were controlled at temperature of 30?,table speed of 150rpm,inoculation amount of 15%,pH of 4.5,the degradation rate of crude oil in 12 days by white-rot fungi can reach up to 45.15%.?2?The optimal conditions according to the single factor experiment and the response surface model were sawdust ingredient amount of 9.45g/L,Tween80 concentration of 0.32g/L and NH₄NO₃concentration of 0.18g/L,H₂O₂ concentration of 250mg/L,under which the theoretical value of crude oil degradation rate reached 54.09%by 12d bioremediation,and the validation value was 53.65%,the regression effect of model was obvious.?3?When the environmental conditions of soil were controlled at moisture content of 30%,Tween80 dosage of 0.2%,sawdust dosage of 3.0%,the degradation rate of crude oil in 35 days by white-rot fungi was30.26%,based on this,when the salt concentration and pH were respectively adjusted to 0.5%and 5.0,the degradation rate of crude oil in 35 days by white-rot fungi could reach up to33.83%.?4?The degradation rate of crude oil in 35 days of the soil which contained white-rot fungi and indigenous bacteria could reach 32.96%,higher than 3.72%of the soil which only contain indigenous bacteria.During the remediation,the breath intensity,the activities of dehydrogenase,catalase,laccase,manganese peroxidase,and the number of bacteria,fungi,actinomycetes were increased,the biological characteristics of oil contaminated soil were improved obviously,soil microbial quantity and dehydrogenase activity were highly correlated with the degradation rate of crude oil,correlation coefficient were respectively0.996,0.973.White-rot fungi and indigenous bacteria showed a trend from competition to synergy during the repair process.