Studies on Effects of Several Wetland Plants on Eutrophic Water Purification

Abstract

Effectiveness of combinations of seven different ecotypes of wetland plants including Thalia dealbata, Iris tectorum, Acorus calamus,Zizania aquatica, Nymphaea tetragona,Georgi, Myriophyllum aquaticum, Thalia dealbata purifying water was investigated by hydrostatic simulation experiment method. The research showed that combinations of various wetland plants had significant purification effects on eutrophic water body, plant community was stable, and plants grew well. Chemical Oxygen Demand (COD) removal efficiencies of various combinations were higher than 97%, and 25.9% higher than that of the blank control group; the average highest total phosphorus (TP) removal efficiency of plant combinations was 97.6%. Compared with COD and TP, Total nitrogen( TN)removal efficiency was lower, ranging from 90.4% to 83.1%.Different wetland plants had different purification effectiveness for different pollutant. The combination N+Z+A+ZI had the highest TNremoval efficiency, reaching 90.4%. Combinations N+Z+A+ZI and N+Z respectively won the first and second place in the disposal of TP,reaching 99.68%, 99.34%. For Chemical Oxygen Demand COD removal, the combination N+Z+C+T did the best and the highest removal efficiency reached 97.6%. Fuzzy comprehensive evaluation method is used to select the following combinations with stronger capacities of removing N and P in sewage: N+Z+A+ZI, N+Z, N+Z+C+T. They can be promoted and applied in purification of eutrophic water body in ecological projects.