Purification effects of reeds, canna and coleus in constructed wetland on reclaimed water

To analysis the removal effects of three plants on nitrogen,phosphorus and COD in reclaimed water,reeds(Phragmites australis),canna(Canna indica),and coleus(Mentha haplocalyx) was planted in a subsurface flow constructed wetland.The results showed that: ①The removal effect of reeds on ammonia nitrogen was the best,and the removal rate can reach 85.43%.The removal rates of reeds and canna on nitrate-nitrogen were higher than that of coleus and control group.The TN removal rate was 76.30% with reeds,76.19% with canna,61.60 % with coleus,and 46.99% with contrast group,respectively.②The average removal rate of coleus on total phosphorus and active phosphorus were 51.11% and 71.89%,respectively,better than that of canna and reed.③The COD removal efficiency of the three test groups were similar and higher than that of the control group.The removal efficiency of canna group was best,which could reach 77.76%.