The reduction of petroleum hydrocarbons in soil under saline conditions using ultrasound.

Salts (i.e. NaCl) and hydrocarbons are common soil pollutants found at contaminated sites generated by the oil and gas industry, and such pollutants pose serious risks to the environment and human health. In this study, a series of laboratory experiments were conducted to identify the properties influencing interactions of crude oil, dissolved salt, and soil particles and to evaluate the effectiveness of ultrasonic technology as a useful remediation technique for treating mixed soil contaminants. A sample of soil (sand, clay and muskeg) equivalent to 30 ml volume was spike with 1 to 2% of crude oil (volume: volume). Two salinity categories (no salt and 0.14 M salt added) were selected and the soil slurry was irradiated for up to 40 minutes using a 20 kHz ultrasonic probe operating at an intensity of 400 W/m². The change in crude oil concentration was measured in treated samples by gas chromatograph. The results indicated that the application of ultrasound generally increased the removal of hydrocarbons by a maximum of approximately 50% observed in sand. In contrast, the presence of salt significantly reduced the removal of hydrocarbons.