Purification Effect of Ecological Ditch-pond Wetland System on Farmland Drainage in the Erhai Lake Basin
In order to explore the nitrogen and phosphorus removal effect and application prospect of ecological ditch-pond wetland system on farmland drainage in the Erhai basin,the ecological ditch-pond wetland system was constructed in situ to intercept and purify farmland tail water.Based on the analysis of the concentration characteristics of COD,TN,TP and NH4+-N in the influent and effluent of the system during the rainy season,dry season and the whole year,an improved grey pattern recognition model and a comprehensive average pollution index were introduced to comprehensively evaluate the water purification effect of the system.The results showed that the ecological ditch-pond wetland system has played an effective role in purifying TN,NH4+-N,TP and COD in farmland drainage.The annual removal rates of TN and COD were 15.20％～69.59％and 4.46％～61.90％,respectively.The lowest concentration of effluent could reach class Ⅱ standards of surface water environmental quality,and the average annual effluent NH4+-N and TP could reach class Ⅱ and Ⅲ standards of surface water quality,respectively.In the rainy season and dry season,the average effluent of the system was Class Ⅲ and Ⅳ,respectively,and the annual average effluent could reach the Class Ⅲ standard of surface water quality.The removal of TN and COD in farmland drainage was an important factor affecting the change of effluent quality.The study showed that ecological ditch combined with pond wetland could obviously improve the removal efficiency of nitrogen,phosphorus and COD in farmland drainage in the basin,and the annual average effluent of the system could reach the class Ⅲ standard of surface water environmental quality.At the same time,it has the characteristics of stable operation and environmental and economic benefits,and has a certain prospect of popularization and application in the Erhai basin.
the Erhai lake basinagricultural non-point source pollutiongray-mode identification modelecological ditchpond wetland
NETL
NSTL
万方数据
