生态工程综合治理系统对农业小流域氮磷污染的治理效应

以典型农业小流域——开慧河流域源区为研究对象,基于研究区农业面源污染的主要排放特征,建立以生态湿地为主的小流域面源污染生态工程综合治理系统,重点探讨其对水体氮磷污染物的去除效果.结果表明,畜禽养殖业是开慧河流域源区水体氮磷污染物的主要来源,需要重点防控.组合生态湿地处理工程对农村分散式生活与养殖混合废水总氮(TN)、总磷(TP)的平均去除率为87. 1%和90. 9%;多级人工湿地拦截工程对农田排水与分散式养殖混合废水TN、TP的平均去除率为85. 7%和84. 9%;景观型生态湿地净化工程对末端汇水区水体中TN、TP的去除率在27. 1%～67. 4%和13. 3%～81. 5%之间.整个生态工程综合治理系统对流域TN和TP污染物的总拦截量分别为5 292 kg·a~(-1)和1 054 kg·a~(-1),占研究区农业面源TN、TP总污染负荷的35. 3%和43. 6%.因此,构建的生态工程综合治理系统对流域农业面源氮磷污染具有较好的治理效应,适合在我国南方小流域水环境治理中推广应用.

Nitrogen and Phosphorus Removal by Integrated Ecological Engineering Treatment System in a Small Agricultural Watershed

Based on the discharge characteristics of agricultural non-point source pollution in the headstream region of the Kaihui River-a typical small agricultural watershed, an integrated ecological engineering treatment system (IEETS) was constructed with ecological wetland as the core unit to control the pollution. The nitrogen (N) and phosphorus (P) removal performances of the IEETS were discussed in this study. The results showed that the dominant source of N and P in the study area was livestock and poultry breeding, which was urgent to control. The monitoring results indicated that the ecological wetland treatment project resulted in average total nitrogen (TN) and total phosphorus (TP) removal rates of 87.1% and 90.9%, respectively, when treating mixed decentralized domestic and swine wastewater treatment. The multi-stage constructed wetlands had an average of 85.7% of TN and 84.9% of TP removal for mixed farmland drainage and decentralized swine wastewater. The removal rates for landscape-based ecological wetland were within the range of 27.1%-67.4% for TN and 13.3%-81.5% for TP in the catchment terminal water. The total interception amount of TN and TP by the IEETS was 5292 kg·a^-1 and 1054 kg·a^-1, accounting for 35.3% and 43.6% of total pollution loads in the headstream region, respectively. These findings illustrated that the IEETS presents promising treatment results on non-point source pollution, and is suitable for widespread applications to wastewater treatment in small watersheds of southern China.