北运河贯穿京津冀，是十三五期间海河流域水系改善的重点，后续即将建设水质净化示范工程。通过监测北运河城区段水体中氨氮、总磷、COD浓度变化，分析北运河城区段水质的时空变化特征。以北运河河道水为试验原水，开展试验研究不同水生植物、不同覆盖面积比例下、不同水力停留时间对北运河原水中氨氮、总磷、COD的去除效率。筛选出优势的植物种类-水葱；测试得到水葱在覆盖面积比例为25%、50%、67%的工况下对氨氮、总磷、COD的去除率及变化规律；在水力停留时间为24 h时，水葱在25%覆盖面积比例下对北运河水体中氨氮、总磷、COD去除率可以达到39.5%、65.2%、45.9%，水力负荷参数分别为0.49、0.15、17 mg/(L·d)，效果较好，且能够兼顾示范工程造价。

The north canal, which runs through the Beijing-Tianjin-Hebei Region, is the focus of the improvement of the Haihe River Basin during the 13th five-year plan period and will be followed by a water purification demonstration project. By monitoring the concentration of ammonia nitrogen, total phosphorus and COD in the water of the north canal city section, the spatial and temporal characteristics of water quality in the north canal city section are analyzed. By taking the river water of north canal as raw water, the experiment is carried out to study the removal efficiency of ammonia nitrogen, total phosphorus and COD in the raw water of north canal under different aquatic plants, different coverage area ratio and different hydraulic residence time. the dominant plant species - water onion is selected. The removal rate and change rule of ammonia nitrogen, total phosphorus and COD are obtained under the conditions of coverage area proportion of 25%, 50% and 67%. When the hydraulic residence time is 24 h, the removal rate of ammonia nitrogen, total phosphorus and COD in the water body of the north canal can reach 39.5%, 65.2% and 45.9% with the proportion of 25% covered area, and the hydraulic load parameters are 0.49, 0.15 and 17 mg/(L·d), respectively. The results are good and the demonstration project cost can be taken into account.