Study on Surface Flow Constructed Wetland Treating Slightly Polluted River Water in the High Latitude and Cold Region

Surface flow wetland with Reed planted in it was employed to treat micro-polluted water in Xinkai river, and effects of temperature, hydraulic retention time and growth of plants on the performance of surface flow wetland were studied. The results showed that COD removal of surface flow wetland was influenced by growth of plants and temperature, hydraulic retention time affected the performance of surface flow wetland obviously. NH4+-N removal of surface flow wetland was excellent and stable. Most of the area of the wetland system was under anaerobic or anoxic, Concentration of NO2--N and NO3--N in effluent stayed low. The denitrification was fully conducted but nitrification became a constraining factor. TP removal performance of surface flow wetland was ordinary. When Temperature was greater than 16°C, the hydraulic retention time was greater than the 3d and plants grew well, removal efficiencies of CODNH4+-N and TP were 22.45%,70.10% and 55.80% with concentration below 30.21mg/L1.82mg/L and 0.36mg/L, and the standards of Surface Water Grade V were satisfied.