| Diesel is one of the most used fuel in transportation. And it causes soil contamination in the course of processing, unreasonable waste disposal as well as the accident occurred, particularly underground storage tank leakage. Bioventing is an in situ forced oxidative soil remediation technology which combined soil vapor extraction (SVE) with biodegradation. It has broad application prospects of soil contamination caused by underground storage tank leakage due to its high-performance, low treatment cost and tail gas treatment cost, compared with SVE. In this paper, the combination method of indoor column in which five factors(initial diesel concentration, venting mode, pore volume number during soil venting, soil moisture content and the ratio of carbon, nitrogen and phosphate) were considered and sand box experiment was used to study the remediation of diesel contamination sand soil by bioventing. In addition, the microbiology experiment was carried out to enrich, separate, screen and identify by means of molecular biology to indigenous dominant bacteria in the sand box, and its degradation characteristics were analyzed. The main results were as follows.(1) Initial diesel concentration and soil moisture content have main effects on the remediation of diesel contaminated soil by bioventing, then the ratio of carbon, nitrogen and phosphate and pore volume number during soil venting. Venting mode has the weakest effect. When 40mg oil /g soil of diesel concentration, air injecting from the bottom of column, 4 vk·d of the pore volume number during soil venting, 100:20:1 of the ratio of carbon, nitrogen and phosphate and soil water content for 20% of the maximum of soil water holding capacity, that would reach a larger removal rate.(2) Volatilization is mainly influenced by pore volume number during soil venting and soil moisture content, the balance and distribution curve of residual TPH is""type, and the maximun percentage which occupied the overall removal rate of TPH is 22.8%, and the minimum is only 3.8%. Gravity is mainly influenced by initial diesel concentration, soil moisture content and the ratio of carbon, nitrogen and phosphate, the balance and distribution curve of residual TPH is"single peak"type. In addition to venting mode, the other factors affect the biodegradation, the balance and distribution curve of residual TPH is"bimodal"type, and the maximun percentage in the overall removal rate of TPH is 68.4%, the minimum is 29.4%.(3) The original equilibrium state and the sand adsorption of diesel was broken under the vacuum extraction from extraction well on the top of sand box. Diesel contaminants in the soil (mainly volatile components) occurred migration and diffusion in horizontal and vertical direction, and the vertical migration and diffusion was more obvious. (4) Four diesel-degrading strains (B-1, B-2, B-3, B-4) in the sand box, which grew by diesel as only carbon sources were obtained. The results of morphological observation and identification of molecular biology showed these strains belong to Microbacterium sp., Brevundimonas sp., Pseudomonas sp., Pseudomonas sp., respectively. Strain B-3 and strain B-4 have homology of 97% based on phy-logenetic analysis.(5) Under the optimum culture conditions which is pH 7.5 and a temperature of 35℃, degradation characteristics of strain B-3 and strain B-4 were studied. The degradation rate of strain B-3 was obviously higher than that of strain B-4 for different initial diesel concentration. Especially, when the diesel concentration (v/v) was 1.5%, the degradation rate of strain B-3 was 60.98%, increased by 23.8% than that of strain B-4.
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