Research Of Straw Immobilized Microorganisms On The Repairing Of Petroleum-contaminated Soil By Humic Acid Strengthening

In order to study the strengthen effect of humic acid on the repairing of petroleum-contaminated soil with straw immobilized microorganisms,this topic discusses the experiment and analysis from the following four aspects.(1)By adding the adoption of humic acid to adjust humic acid content in petroleum contaminated soil,the carbon content,nitrogen content and phosphorus content,and the changes of moisture content in the soil joining different content of humic acid were analysised in 30 days.The effect of humic acid content of petroleum contaminated soil was also studied.(2)The petroleum-contaminated soil samples were inoculated in the same concentration of indigenous microorganisms,immobilized microorganisms.Regulate the humic acid content of soil samples by adding different quality of humic acid to 0mg/g(do not adding any humic acid),10mg/g,50mg/g,100mg/g,150mg/g.The soil samples were placed in the constant temperature foster box(regulate the temperature to 28℃,50% humidity)for 30 days.Determined the soil sample every 6 days,the microbial biomass in the soil samples,through the combination of petroleum hydrocarbon content in the soil sample and dehydrogenase content,were analyzed changing trend.The growth of the petroleum hydrocarbon degradation microorganisms in the soil samples and indigenous microorganisms with high efficient degradation bacteria,the influence of the interaction between immobilized microorganisms were analysised(3)Using the response surface method to conclusion that the optimum experimental conditions of straw immobilized microorganisms carrier were decomposition rate 32.5%,temperature 27.3℃,pH7.5.The humic acid content producing by straw carrier decomposing in 60 days was 763.08μg/g.(4)Strengthen the low oil bioremediation of petroleum-contaminated soil by using humic acid under the condition of the response surface optimization determination in 30 days.The results show that:(1)When soil humic acid content is 100mg/g,the soil water storage was best,and under the soil moisture content was low,the most conducive to adjust petroleum contaminated soil C/N and available phosphorus content,the polyphenol oxidase and dehydrogenase were increased,at the same time the microbial decomposition of H2O2 was also increased on the soil.(2)Vaccination straw immobilized microorganisms of soil samples quantity was higher than vaccination free high efficient degradation bacteria soil samples,and when the soil humic acid content was 100mg/g,the microscopic growth to steady growth.High efficient degradation bacteria within 30 days after immobilized in the petroleum hydrocarbon degradation rate up to 48.2%,7.2 percent more than free degrading immobilized microorganisms’,11.3 percent more than indigenous microorganisms’.And it could be within 6-30 days maintaining high degradation rate.Dehydrogenase activity was also larger than other soil samples.(3)Using the response surface method for decomposing and optimum experimental conditions of immobilized microorganism carrier of straw was 32.5% moisture content,temperature of 27.3℃,pH 7.5,humic acid content produced by straw carrier in 60 days was 763.08μg/g.(4)Soil initial petroleum hydrocarbon content was 2.3%~3.0%,the regulating soil humic acid content is 100mg/g,and in the most conducive to straw decomposing and environment conditions,petroleum hydrocarbon degradation rate in 30 days could reach 27.6%,13.6 percent higher than the soil sample under the condition of the environment,7.3 percent higher than the soil sample under the condition just consider the growth condition of microorganisms.In summary,the content of humic acid in the soil is 100mg/g,could play a role in strengthening the straw with immobilized microbial remediation of petroleum-contaminated soil.