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| Purification efficiency of pollutants in farmland runoff by the ecological ditch and its configuration scale |
| Received:June 13, 2024 |
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| KeyWord:ecological ditch;farmland runoff;nitrogen;phosphorus;configuration scale |
| Author Name | Affiliation | E-mail | | ZHANG Yingying | Institute of Agricultural Resources and Environmental Sciences, Jiangsu Academy of Agricultural Sciences
Key Laboratory of AgroEnvironment in Downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China | | | LI Min | School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China | | | PAN Wuyi | School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China | | | WANG Yan | Institute of Agricultural Resources and Environmental Sciences, Jiangsu Academy of Agricultural Sciences
Key Laboratory of AgroEnvironment in Downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China | | | JIANG Zhihui | Institute of Agricultural Resources and Environmental Sciences, Jiangsu Academy of Agricultural Sciences
Key Laboratory of AgroEnvironment in Downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China | | | SU Guodong | Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | LIU Haiqin | Institute of Agricultural Resources and Environmental Sciences, Jiangsu Academy of Agricultural Sciences
Key Laboratory of AgroEnvironment in Downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China | | | ZHANG Zhiyong | Institute of Agricultural Resources and Environmental Sciences, Jiangsu Academy of Agricultural Sciences
Key Laboratory of AgroEnvironment in Downstream of Yangtze Plain, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China | jaaszyzhang@126.com |
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| Abstract: |
| Ecological ditch is an important part of control technology system of agricultural non-point source pollution in south China water network area. The appropriate scale of ecological ditch corresponding to farmland area has not been determined yet. 3 ditches of the same specification have been reconstructed to ecological ditches by setting up wet plants, biofilm carrier boxes and ecological filter dams. The 3 ecological ditch treatments with different enhanced purification measures were set up, including the treatment of wet plants, one biofilm carrier box with one ecological filter dams（D1）; the treatment of wet plants, two biofilm carrier boxes with two ecological filter dams（D2）；the treatment of wet plants, three biofilm carrier boxes with three ecological filter dams（D3）. Meanwhile, the influent flows of the ditches were controlled. Purification efficiencies of different treatment ecological ditches on pollutants from farmland runoff were compared, the variations of pollution flux on the time and space scale were analyzed, and the appropriate scale of ecological ditch corresponding to unit farmland area were discussed. The results showed the removal efficiencies of TN, NH4+-N, TP and COD in the ecological ditches were respectively 33.9%-49.1%, 37.8%-42.9%, 29.3%-42.0% and 60.0%-78.1%, meanwhile the removal efficiencies of TN and TP in D2 and D3 were higher. The pollutant fluxes of TN and COD in the effluent of D2 and D3 were significantly lower than D1, while there was no significant difference among the pollutant fluxes of NH4+-N and TP in the effluent of the 3 ecological ditches. The average TN and TP concentrations was reduced down to 2 mg ·L-1 and 0.2 mg ·L-1 at the point of 85.4 m and 57.3 m along the ditch of D3, respectively. Moreover, the required length of D3 was the shortest one among the 3 ecological ditches. Under the flow experiment conditions with daily rainfall of 60 mm·d-1 and TN concentration reduction of 4.64 mg·L-1, 1 m3 ecological ditch with the configuration facilities of D3 can treat the drainage from 19 m2 farmland. In follow-up studies, the enhanced purification measures of wet plants, three biofilm carrier boxes with three ecological filter dams（D3）should be applied according to local conditions, and the ecological ditches and catchment ponds and branches should be effectively combined, comprehensive purification efficiency of ecological ditches and catchment ponds and branches should be considered to estimate the configuration scale of“farmlands-ditches-ponds-rivers”as a whole. |
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