Abstract
Bio remediation is one of the ways to recover contaminated soils: it activates the microbes in soils and enhances bio-degradation processes by injecting air or nutrient solutions into contaminated soils. In this study, oil contaminated soils were remediated by injecting a nutrient solution into the soils. Effluent solution was analyzed and residual oil was extracted after the experiment in order to evaluate the remediation efficiency. Two injection rates, one using saturation and the other using unsaturation were tested to observe the saturation-induced differences in the flow regime. The resultant residual oil concentration showed that the unsaturated remediation process was more effective than saturation. This result is opposite to that of the in-situ application by the companies. The difference is most likely because dispersion was more dominant than convection, creating an effective distribution of the nutrient solution. In conclusion, the proposed remediation process and slow injection rate have advantages over the fast injection process because of its improved remediation results, lower cost and lower required nutrients, and reduced environmental impact due to lower groundwater leakage.
