Crude Oil-Contaminated Soil Treatment and Oil Recovery through Micro-Emulsion Washing

Abstract

Removal of crude oil from oil-contaminated soil using a micro-emulsion (ME) washing method was carried out in this work. The influence of the oil/water ratio on the phase behavior of the ME was studied by the phase diagram. As the oil/water ratio (V o/V w) increased, Winsor type I ME presented and the phase state of the system remained unchanged. Comparison between the original and the recovered crude oil and soil samples was done. It is found that the ME treatment has little influence on the physical and chemical properties of the soil. The recovered crude oil has higher saturation fraction, lower aromatic, resin, and asphaltene content, and lower density and viscosity and belongs to light crude oil. Experiments on effects of diesel oil amount, temperature, reusing times, and scaling-up were carried out using the selected three types of ME formulation. The optimal ME formulation for the de-oiling of crude oil contaminated soil is w(SDBS) = 10%, w(n-butanol) = 4.8%, w(NaCl) = 0.8%, and w(diesel) = 13.6%. The most suitable temperature for treating oily soil by ME is 35–50 °C, and the treating effect is still stable when the capacity is scaled up by 6000 times.