THE BIOLOGICAL RESTORATION OF OIL-POLLUTED SOIL
REN Lei & HUANG Ting-lin (School of Environmental and Municipal Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China)
The biological restoration techniques of oil-polluted soil is efficient,safe and easy to manage. Starting from the principle of biodegradation of oil-pollutant in soil, the new development of the technical measures and engineering methods, which enhance the effect of the biodegradation, is summarized in the present review. On this base, the direction of the progress of biological restoration technique is analyzed. The biological species that can degrade the oil-pollutant in soil are introduced in detail. The study shows that some new bacteria such as pseudomonas, bacterium, flavobacterium and micrococcus are segregated or incubated incessantly. The discussion of the biochemical principle of biodegradation of oil-pollutant in soil is given. It is considered that the study of the relationship between the degradation rate and the species of hydrocarbon is important. Hydrocarbons with branching structures generally reduce the biodegradation rate, and aromatic compounds are degraded more slowly than alkanes. The factors determining the rates of oil biodegradation in soil include the microbial community, temperature, humidity, pH value, oxygen, the quantity of nutrition and trace elements. All kinds of biological restoration techniques of oil-polluted soil are divided into two groups. One is ex-site technique, and the other is in-site technique. The land-farming,biopiles and composting constitute ex-site technique. The in-site techniques involve enhanced in-site biological restoration technique and vegetation-restoration technique. Many technical measures are developed to enhance the efficiency of biological restoration techniques of oil-polluted soil. It is noticed that using techniques such as favorable micro-organism, oxidant and surfactant are more and more popular. Finally, the trend of the biological restoration technique of oil-polluted soil is presented. There will be more and more new technology for use in this field. As biological restoration techniques become sophisticating, they will be used wider and wider. This is good for the protecting of ecological environment of the world.