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| Removal of nitrogen and phosphorus from farmland drainage by ecological ditch-wetland system |
| Received:April 17, 2018 Revised:July 09, 2018 |
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| KeyWord:ecological ditch;wetland;nitrogen;phosphorus;farmland drainage;non-point source pollution |
| Author Name | Affiliation | | ZHU Jin-ge | State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China | | ZHANG Xiao-jiao | Nanjing Zhongke Water Environment Engineering Co., Ltd, Nanjing 210016, China | | LIU Xin | University of Chinese Academy of Sciences, Beijing 100049, China | | GUO Xi-ya | University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: |
| In order to better understand the effect of ecological interception systems on removal of nitrogen and phosphorus from farmland drainage, an ecological ditch-wetland system was constructed to treat the farmland drainage during the fertilization period. The results showed that the ditch-wetland system effectively purified drainage water with an average TN, NH4+-N, and TP concentration of 23.45 mg·L-1, 19.87 mg·L-1, and 0.341 mg·L-1, respectively. The lowest concentration in the outflow met the class V requirement for TN and the class Ⅳ requirement for NH4+-N defined in the surface water environmental quality standards (SWQS). The average concentration of TP in the outflow met the class Ⅲ requirement. The removal rates of TN, NH4+-N, and TP were 49.95%, 48.55%, and 53.22% respectively with the ecological ditch, and 18.4%, 9.43%, and 23.35% respectively with the constructed wetland, resulting in total removal rates of 59.6%, 51.69%, and 60.92% respectively. Our results indicated that constructing the wetland at the end of ecological ditch effectively increased the removal efficiency of nitrogen and phosphorus. The system is simple to use and presents environmental and economic benefits. Thus, the results of this case study can be applied to the ecological interception of similar type of farmland drainage generated east of Taihu Lake. |
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