Study On Improving Water Quality Of Scenic Water By Constructed Wetland

Purification of artificial scenic water using rainwater and reclaimed water as resource by constructed wetland was studied in this paper.Many factors were studied to explain the results of the research into water body purification by constructed wetland in this paper such as the effects of contamination removal, optimum hydraulic loading rate, effects of season, analysis of ways of contamination removal, connection of contamination concentration in effluent of constructed wetland and area loading, strengthen of constructed wetland in winter, effect of water quality improvement and so on.The following results were proved through the experimental study:(1) The removal efficiencies of P, N, COD, turbidity and algae in the wetland were fairly good. The maximal removal rates of TP, NO₃^- -N, NH₄⁺-N, TN, COD, turbidity and algae were respectively 66%, 97.5%, 42.9%, 40.9%, 80%, 96.7%, 99%.(2) With an increasing hydraulic loading rate, the removal rates of NH₄⁺-N increased, while other removal rates of contamination decreased. The removal efficiencies of contaminants in wetland were changed as seasons alternated. For example, the removal rate of TP is 34% higher in summer than in winter, and the removal rate of TP is 27% higher in summer than in winter.(3) When the constructed wetland was used to remove TP, the experimental results proved that the maximal removal speed of TP was 5.66 g/ (m²Â·d) when the hydraulic loading was 1.2m/d. When constructed wetland was used in denitrification. The maximal removal speeds of NH₄⁺-N, NO₃^--N and TN were respectively 23.87 g/ (m²Â·d), 35.91 g/ (m²Â·d) and 54.58 g/ (m²Â·d) when he hydraulic loading was 0.9m/d.(4) The removal efficiencies of P and N could be enhanced when constructed wetland was covered by plants in winter. The removal rates of TP and NH₄⁺-N by wetland covered with plants were twice as the blank wetland', and the removal rate of TN was three times as the blank wetland'. However, there was no difference in NO₃^--N's removal between the plants covered wetland and the blank wetland. Plants covering can be one method to improve the removal efficiencies of contaminants in the constructed wetland in winter by reducing the heat loss.(5) Constructed wetland was a main way to remove pollutants in water. The quality removed by constructed wetland was 52.6-88.6% and 62.3-98.7% in all removed pollutants, the average quality was 67.78% and 77.32%.(6) Under the contion of this experiment, COD, TN and TP released when Lythrum salicaria rotted were respectively 46.02mg/g, 0.98mg/g and 0.4mg/g(7) The biomass in the middle of constructed wetland was higher then the forward and back part of constructed wetland in summer; The biomass in the forward part of constructed wetland was the highest in winter. The nitrication was: the forward nitrication > the middle nitrication > the back nitrication.We can conclude that the constructed wetland performed quite well in treating scenic water through the experimental study. It could be a new way for purification of scenic water.