Research on Phosphorus Removal in Artificial Wetlands by Plants and Their Photosynthesis

摘要

ABSTRACT Urban rainfall runoff pollution has become a major reason for water eutrophication problem in the process of urbanization in China, while phosphorus is a significant restrictive factor that influences primary productivity of freshwater system. It's rather significant to conduct phosphorus control in waste water with engineering measures. This research, based on material balance research of phosphorus in artificial wetlands, HRT (hydraulic retention time) and analysis of wetland plant photosynthesis and removal rate of phosphorus, simulates purification of phosphorus in urban runoff sewage by artificial wetland system. Experiment shows that removal rate of total phosphorus in urban runoff sewage by artificial wetland system reaches 42.23%-60.89%, and contribution rate in removal of phosphorus which is assimilated and absorbed by plants is 14.74%; contribution rate in removal of phosphorus which is accumulated and absorbed by substrates is 43.22%; contribution rate in removal of phosphorus which is absorbed by means like microorganisms is 2.93%. Pollutant absorption by substrates is a process of dynamic equilibrium. With extension of HRT, phosphorus removing effect of wetlands present an increasing and then decreasing tendency; Net photosynthetic rate and TP removal rate of canna and reed have significant positive correlation, and correlation coefficients are respectively 0.941(P<0.001) and 0.915(P<0.05). Substrates and plants are main pathways for phosphorus removal of artificial wetlands, covering 95% of the total removing effect.