A Study On Bioremediation Of Phenanthrene-polluted Soil By Aged Refuse Addition

Due to the incomplete combustion of various fossil fuels,wood,paper and other hydrocarbons containing hydrocarbons and the oil spill in the exploitation,production and transportation,the content of polycyclic aromatic hydrocarbons(PAHs)in the soil increased.PAHs in soil have high stability,persistance,toxicity and accumulation effect,which have been widely concerned by environmental science researchers.At the same time,aged refuse is of a loose structure,good hydraulic conductivity and rich in a large number of micro-organisms,is an excellent biological media,therefore,the aged refuse addition has a good application prospect and practical significance in bioremediation of PAHs-contaminated soil.This paper used artificially formulated phenanthrene-polluted soil to study the effects of aged refuse addition on bioremediation of different concentrations of phenanthrene-polluted soil and the strengthening mechanism of aged refuse were researched by sterilization experiment and adding nutrient materials.The results of the study are as follows:The concentration test results showed that:?The total microbial biomass in the soil increased rapidly with the time,from the 13th day of bioremediation it began to degrade,when the concentration of phenanthrene in the soil was 50?400mg/kg,the total microbial biomass was not significantly correlated with the concentration of phenanthrene in the soil.?The activity of polyphenol oxidase in the soil decreased first with the time,and increased slightly at the 39th day of bioremediation,and then decreased,when the concentration of phenanthrene in soil was 50?400mg/kg,the activity of polyphenol oxidase was not significantly correlated with the concentration of phenanthrene in the soil.?The germination rate of wheat seeds in different soil was different between 75%and 95%,and the difference of gap of root elongation inhibition and the difference of elongation inhibition rate were also small,when the concentration of phenanthrene was 50?400mg/kg,the soil ecotoxicity was less affected by the concentration of phenanthrene in the soil.?The bioremediation kinetics of phenanthrene showed that the bioremediation rate of phenanthrene was not that different in different soil,and the bioremediation constant was between 0.434 and 0.637.When the concentration of phenanthrene was 50?400mg/kg,the bioremediation rate of phenanthrene was not significantly correlated with the concentration of phenanthrene in soil.?When the concentration of phenanthrene in the soil is less than 400mg/kg,aged refuse has a better advantage in the bioremediation of high concentrations of phenanthrene soil.The mechanism test results showed that:?The total microbial biomass in the soil which added aged refuse was significantly higher than that in natural bioremediation soil,indicating that the addition of aged refuse can promote the growth of microorganisms in soil.?In the first 39 days of bioremediation,the activity of polyphenol oxidase in the soil which added aged refuse was lower,mainly due to the competition between microorganisms,but from the 49th day on the activity of polyphenol oxidase is higher.?After the bioremediation,the ecotoxicity monitoring of the soil which added aged refuse is improved better than that of the soil without adding aged refuse.? It can be seen from the bioremediation kinetics that the addition of nutrients can promote the bioremediation of phenanthrene,but the effect is lower than that of adding aged refuse,and the effect of adding sterilized aged refuse is greater than that of adding non-sterilized aged refuse.Indicating that aged refuse promotes phenanthrene bioremediation is associated with the nutrients it contains,but not with the microbes.?From the microbial diversity,it can be seen that the number of bacteria and fungi in the soil increased by 2.75 and 8.92 times after the addition of aged refuse.For bacteria,the chaol index increased 0.78 times and the Shannon index increased 0.20 times,indicating that species and community diversity were improved.For fungi,the chaol index decreased by 0.44 times and the Shannon index decreased by 0.53 times,indicating that the species and community diversity reduced.