Abstract:The ecological system with hydroponic macrophytes experimental devices were constructed to treat the secondary effluent of a sewage treatment. For the most COD and NO3--N have been effectively removed in the effluent, NO3--N was selected as study target pollutant.In the condition of the HRT of anaerobic zone 10~18h, the system hydraulic loading 1.33m3/(m3×d), no additional carbon add, and the empty slot running, NO3--N removal rate is 10.80%. However, with Eichhornia crassipes which exudates dissolved organic carbon (DOC) planted in the device, NO3--N removal rate can be increased to 15.89%. While with sulfur added, autotrophic denitrification process can help the NO3--N removal rate increased to 37.80%. When glucose were added, TN and NO3--N removal rate can reach 87.20% and 93.21%, and the effluent concentration dropped to 2.2 mg/L and 1.04mg/L respectively.