Optimization of Nitrogen and Phosphorus Removal in Vertical Subsurface Flow Constructed Wetlands by Using Polypropylene Pellet as Part of Substrate
聚丙烯小球对人工垂直潜流湿地氮磷去除性能的优化研究

Constructed wetlands experiments were conducted by using shale and Typha latifolia L as vertical subsurface flow constructed wetland substrate and plant for eutrophic Jin River water treatment, and replace part of shale with polypropylene pellet to investigate its effect on nitrogen and phosphorus removal. In this study, hydraulic loading rate was equal to 800mm/d; theoretic residence time was equal to 12 h. During the entire running period, maximal monthly mean ammonia-nitrogen (NH4+-N), total nitrogen (TN), soluble reactive phosphorus (SRP) and total phosphorus (TP) removal rates were observed in August 2006. In contrast to the full shale used wetland, polypropylene pellet enhanced ammonia-nitrogen, total nitrogen, soluble reactive phosphorus and total phosphorus removal: 13.38%, 8.9%, 9.29%, and 8.25%. After finishing the experiment, aboveground plant biomass (stems and leaves) of Typha latifolia L was harvested, and its weight and nutrient content (total nitrogen and total phosphorus) were measured. Analysis of aboveground plant biomass indicated that polypropylene pellet restrains the increase in biomass but stimulates assimilation of nitrogen and phosphorus into stems and leaves. The subsequent harvesting of the plants resulted in the additional removal of total nitrogen and phosphorus of about 29.382g.m-2 and 13.469g.m-2, respectively.