Purification efficiency of constructed wetland system withLolium perenne, Coix lacryma-jobi and Canna edulis
菩提子/美人蕉-黑麦草人工湿地生态工程净化效果研究

In this paper,the purification efficiencies of constructed wetland system located in Hangzhou with effluent ultimately flowing into the West Lake were studied and the purification efficiency of this system under condition of different hydraulic loadings and at different seasons was examined.Results showed that: the total removal rates were 40%-50% for the total nitrogen(TN),chemical oxygen demand(COD) and biochemical oxygen demand(BOD_5),60%-70% for total phosphorus(TP) and above 90% for NH_4-N.Under condition of similar hydraulic loading,the purification efficiency of the system in Spring and Summer was higher than in Autumn and Winter,the minimum removal rates was maintained at 30% for TN,60% for TP,40% for COD and 35% for BOD_5.In the same season,under the different hydraulic loadings,ranging from 200 to 1200 mm/d,there was no remarkable variation in purification efficiency.