Study of ultrasonic-assisted ozone treatment on oil recovery wastewater from polymer flooding

Polymer flooding technology is a promising method to improve the oil recovery rate. However, a large amount of polymer in the oil recovery wastewater makes the wastewater appear high viscosity. In this study, the effect of ultrasonic treatment, ozone treatment and ultrasonic-assisted ozone treatment on viscosity and polymer concentration of the wastewater was investigated experimentally. Firstly, with the ultrasonic treatment of 10 minutes, the viscosity and polymer concentration of wastewater was reduced by 96.56% and 55.64% respectively. With the ozone treatment of 10 minutes, the viscosity and polymer concentration of wastewater was reduced by 13.44% and 82.60% respectively. This indicates that ultrasound is more efficient for viscosity reduction while ozone is more efficient for polymer degradation. With the treatment of 1-minute ozonation and 3-minutes ultrasound sequentially, the viscosity and polymer concentration of wastewater were reduced by 95.80% and 75.64% respectively. Moreover, when the wastewater was treated by 3-minutes ultrasound and 1-minute ozonation sequentially, the viscosity and polymer concentration of wastewater were reduced by 95.14% and 92.31% respectively. In conclusion, ultrasonic-assisted ozone is an effective way for polymer degradation and viscosity reduction, which is much helpful for the treatment of oil recovery wastewater form polymer flooding.