Bioventing Study And Microbial Condition Analysis Of Soil Polluted By Hydrocarbon

Bioventing technology is a kind of rising technology using in unsaturated soil remediation polluted by organic contamination. This remediation technology has already been successfully used in European and American countries while in China it still remains in laboratory research stage. In this paper, a place in Tianjin Binhai area is chosen to be the pilot experiment field. Geology and hydrology of this field are studied. Structures and physical and chemical properties of underground soil are analyzed with drilling method. Soil column is used to study the permeability of field soil with Darcy Law of porous medium. Latent permeability of single-phase is calculated to be and effective osmotic coefficient under different air-water saturation and are calculated to be 5.780×10-12m2 in single-phase saturation situation. Curve of relative air permeability changing with water saturation is gained in two-phase steady flow. Pilot Bioventing extraction and inspection system are built on the base of lab studies. Well EW1 is validated to be the main venting well by field hydro mechanical analysis and the best venting rate is 34.0m3/h with influencing radius ROI 4m.Simulating contamination isooctane and nutritious salts are poured into the pilot field during simulation pollution process. Original quantity of aboriginal bacteria is studied to be 107 per gram dry soil by flat counting method. During polluting process, density of aboriginal bacteria sharply drops and then rise up to its original level. Obviously the aboriginal bacteria have adaptability to hydrocarbon contamination. 4 kinds of bacteria are observed and separated from the soil solution. 1#, the preponderant bacterium of the four is confirmed to be Pseudomonas sp. MTR-61 after lab research.In this paper, three-dimensional air floating and soil contamination wiping off model of pilot BV system are built on the base of transform of Darcy Law and Bessel function. In this paper, fractional airflow F(R) is bring forward and developed as the standard parameter to determine the influencing radius ROI. A validation is taken to test the model with data gained from pilot experiment by using BIOVENT software. The validation result shows that models built in this paper can well describe the hydrodynamics and soil contamination wiping off condition in real BV operation system. A simulation forecast of a presumptive fuel leaking pollution case is done by using models validated above. Different operation conditions like single and multiple well, successive and intermittent operation and different biodegradation rates are compared during simulation forecast to optimize BV operation condition.