| Comparison research of different constructed wetland types to treat lake Wulihu water was carried out. Under the condition of the loading rates 0.8 m3/(m2·d), the removal efficiencies of the vertical flow wetland(VFW), subsurface flow wetland(SFW) and free surface wetland(FSW) had the following results: To ammonia nitrogen (NH+4-N) the average removal rates were 33.2%, 27.4% and 14.1%, respectively; To total nitrogen (TN) the average removal rates were 52.3%, 50.1% and 19.2%, respectively; To total phosphorus (TP) the average removal rates were 58.8%, 57.9% and 26.3%, respectively; To permanganate index the average removal rates were 37.2%, 38.3% and 14.8%, respectively; To chlorophyll a (Chl-a) the average removal rates were 86.9%, 96.1% and 55.3%, respectively. Obviously, VFW and SFW are more effective than FSW at treating eutrophicated water such as Lake Wulihu which with characters of low organically pollution and with high nitrogen and phosphorus pollution, and the VFW is the most effective on the removal of NH+4-N, TN and TP. SFW is the most effective on the removal of permanganate index and Chl-a. The effluent stability of VFW is better than SFW, and the SFW is better than FSW. |
