Lab and pilot study on treatment of volatile organic compounds contaminated underground water with air stripping method

The effects of different gas-water ratios on the removal efficiency of three typical volatile organic compounds (VOCs), 1,2-dichloroethane, benzene and chloroform, in underground water were evaluated with air stripping tower in laboratory. Results showed that the removal efficiencies were above 89%, 93% and 95% for 1,2-dichloroethane, benzene and chloroform, respectively, under the condition of 20 ℃ and gas-water ratio of 60∶1. Base on the laboratory study, an enlarged stripping tower was designed and used for pilot study on the influences of gas-water ratio, water temperature, VOCs concentration and different VOCs compounds on the removal efficiency. The pilot study results indicated that gas-water ratio and water temperature significantly influenced the removal efficiency of the three VOC compounds. Under the condition of 20 ℃ and gas-water ratio of 75∶1, the removal efficiencies of 1,2-dichloroethane, benzene and chloroform were all higher than 99.7%, which reached the design target values. The off-gas from stripping tower was treated by dielectric barrier discharge (DBD) low temperature plasma plus granular activated carbon (GAC).