treatment of soil contaminated with crude-oil using biosurfactants

soil pollution has become one of the main concerns which because of containing chemical and hazardous materials, alerts the whole environment, and finding solutions to overcome this problem would be very important. many ways have been discovered and examined for soil treatment and one of the most applicable methods is soil washing. in this research, the effect of saponin biosurfactant in crude-oil removal by the concentration of 10000 and 30000 ppm in a column soil sample have been analyzed. the experimental parameters and their value levels investigated were: concentration of surfactant solutions (0.05, 0.1 and 0.2%-mass); ph (7, 9 and 11); alkali (naoh) and polymer (xanthan gum) (0.6 and 0.1%-mass) and (0.7 and 0.2%-mass) respectively, as additions for optimum results in case of excessive efficiency evaluation. results showed that the optimum washing condition for ph was found to be 11 for all the surfactant solutions. and the optimum concentration of surfactant solution for 10000 ppm pollution was 0.1%-mass and for 30000 ppm pollution 0.2%-mass and crude-oil removal efficiency were 69% and 72% respectively. alkali and polymer in amount of 0.7 and 0.2%-mass (for naoh and xanthan gum respectively) caused the efficiency mount to 71% and 75%. tph is used as the criterion of this experiment.