Research on Seven Hydrophytes' Removal Effect on Nitrogen and Phosphorus in Eutrophic Water

Outdoor pot experiments were conducted to investigate seven hydrophytes' removal effect on nitrogen and phosphorus in eutrophic water.Results indicated that all of the seven species grew well in the constructed wetlands,and showed excellent nitrogen and phosphorus removal capacities.When SRP and TP influent concentrations ranged from 0.5 to 1.25 mg/L,and 0.6 to 1.3 mg/L,respectively,SRP and TP removal efficiencies of each hydrophyte showed a consistent trend with the fluctuation of influent concentrations,and SRP removal rates were somewhat higher than TP removal rates.Among the seven hydrophytes,Lythrum salicaria Linn has the best SRP and TP removal capacities.When compared with the unplanted pot,Lythrum salicaria Linn increased the average SRP and TP removal rates by 12.15%and 14.36% respectively,while SRP and TP removal efficiencies of Phragmites communis only increased by 8.61% and 6.73%.As for TN removal performance,there was significant difference among the seven hydrophytes.After comparing with the unplanted pot,Scirpus validus Vahl showed most excellent TN removal capacity,it increased average TN removal rates by 18.19%,while 17.84% for Typha angustifolia Linn,16.0% for Phragmites communis,14.85% for Canna generalis,12.6%for Acorus tatarinowii Schott,7.93% for Iris wilsonii Wright and 7.56% for Lythrum salicaria Linn respectively.The research showed that Scirpus validus Vahl,Typha angustifolia Linn and Phragmites communis have the potentiality to be used as constructed wetland hydrophytes to remove nitrogen and phosphorus pollutants in northern China.