Research on the degradation of petroleum hydrocarbons on the effect of microbial activity in oil-contaminated sites

Abstract

Microbe is the principal part of microbial biodegradation of soil petroleum hydrocarbons, so how to adjust the environmental conditions of the contaminated site and enhance its activity is the key to improving the efficiency of oil degradation. By collecting the original oil-contaminated soil taken in an oil deposit in Northeast and measuring soil microbial activity and indicators of environmental factors, this article discuss the microbial activity's impact on the degradation of oil pollutants, combined with natural attenuation testing. The results show that the soil of contaminated sites is contaminated by petroleum hydrocarbon at different levels, of which the highest content of petroleum hydrocarbon is up to 7.10 mg/kg. Oil mainly contains alkanes, benzene and other light components. Through natural attenuation monitoring, petroleum hydrocarbon content of the sampling points decreases obviously, of which the maximum degradation rate is point T5 that reaches 73%. Soil respiration, the overall microbial activity, decreased from 66.1875mg/kg to 47.8475mg/kg. As far as the enzyme is concerned, the dehydrogenase plays a significant role in the microbial biodegradation of petroleum hydrocarbons, whose activity strength positively correlates with the degradation rate. In the degradation of oil components, the relevance between FDA hydrolase activity and the oil components is the most significant. The stronger FDA hydrolysis activity is, the stronger the ability of biodegradation of each component is. In addition, through analyzing the site soil conditions, PH is in the range of 7.25 ∼ 8.13, the nutritional level far below the required one of biodegradation of petroleum hydrocarbons (C∶N = 10∶1), and soil moisture content lower than the optimum conditions for microbial growth and metabolism. Therefore, it is greatly significant to adjust the soil pH, increase nutrient levels and the regulation of other environmental factors which can increase microbial activity, accelerate the degradation of petroleum hydrocarbons, and enhance the role of soil protection action to groundwater.