[Removal of oil in the lake water in Daqing area using subsurface constructed wetland]

Based on the water quality and climate of the oil contaminated lake in Daqing area, four simulated subsurface wetland systems were constructed in the field to study their removal effect of oil in lake water, including the gravel bed, the gravel-reed bed, the slag-reed bed and the slag bed. The research lasted about 360 d, including five periods: the start up period, the microorganism adding period, the slow-releasing carbon sources adding period, the low temperature period and the normal operation period. During the study, oil removal efficiency of the four units are 24.7%,28.4%, 45.9% and 42.9% respectirely, and the slag unit shows better than gravel unit. The adding of microorganism and slow-releasing carbon sources markedly improves the oil removal. The application of plant in the wetland system also promotes the oil removal. In all the four simulated subsurface wetland systems, 70% of the oil removal attributes to the adsorption effect.