Abstract: According to the composition and content of soil vapour extraction (SVE) tail pollutants in gas station soil, firstly, different concentrations of petroleum hydrocarbons were used to domesticate, enrich and screen petroleum hydrocarbon degrading microorganisms in activated sludge, and a total of 7 high-quality petroleum hydrocarbon degrading bacteria were isolated. Secondly, biodegradation experiment was carried out using the mixed degrading bacteria. After 180 days of biodegradation of artificially prepared simulated petroleum hydrocarbon contaminated soil (initial concentration 1 400 μg/g), the total biodegradation rate of petroleum hydrocarbons was more than 86%. Finally, the mixed degradation bacteria were used to degrade the real contaminated soil (initial concentration 1 532.3 μg/g) in the target gas station. The results showed that the mass fraction of total petroleum hydrocarbons in the truly contaminated soil was reduced to 342.6 μg/g (230 d) by the mixed microbial, which was lower than the risk-based assessment standard of Kansas in the United States (total petroleum hydrocarbon content in non-residential land was less than 450 μg/g), and the total biodegradation rate could reach 77.6%.

Key words: petroleum hydrocarbon contaminated site, microbial degrading bacteria, site remediation, soil vapour extraction