Revolutionary wetland system cleans up pollution in cold areas efficiently.
A two-stage subsurface constructed wetland system was studied in a cold area of northeast China. By using special materials and temperature protection, the system efficiently removed pollutants like COD, BOD5, SS, NH4(+) -N, and TP. The outflow had low concentrations of these pollutants, showing stable removal effects. This two-stage system overcomes the limitations of a single system and improves pollution removal efficiency.