处理低污染河水的湿地内氮迁移转化过程模拟

为了明确以低污染河水为原水的人工湿地中的主要脱氮机制以及氮素的归趋形式,以洱海流域邓北桥湿地工程为研究对象,根据湿地内发生的生物反应、物理吸附以及沉淀等过程,建立了生态动力学模型,模拟湿地中氮素的迁移转化. 结果显示,所建模型能较好地模拟出水中ρ(NH₄+-N)、ρ(NO₃--N)、ρ(ON)(ON为有机氮)的变化趋势,效率系数(R)分别为50.2%、67.6%、81.2%. 通过对湿地氮素迁移转化与去除量的模拟结果分析,确定了湿地除氮的主要机制为硝化、反硝化、植物吸收. 反硝化作用可以去除进水中50.0%的TN,植物吸收可以去除进水中11.0%的TN,底泥则可以吸附进水中3.5%的TN. 模拟得到硝化速率平均值、反硝化速率平均值、植物吸收氮速率平均值分别为0.234、0.438、0.050 g/(m3·d). 

Simulation of Nitrogen Transfer Processes in a Constructed Wetland for a Lightly Contaminated River

A constructed wetland is an effective treatment process for a lightly contaminated river. In order to quantify the main nitrogen removal mechanism and nitrogen transfer processes in a constructed wetland, an eco-dynamic model including various bio-reactions, physical adsorption and sedimentation was established to simulate the nitrogen removal process in Dengbeiqiao constructed wetland. The simulation results showed that the calibrated model could generally address the concentration variations for organic nitrogen, NH₄+-N and NO₃--N. The model efficiencies of simulating organic nitrogen, NH₄+-N and NO₃--N, were 81.2%, 67.6% and 50.2%. The simulation for the nitrogen transfer showed that the major nitrogen removal mechanisms in the constructed wetland were nitrification, denitrification and plant uptake. The denitrification and plant uptake could remove 50.0% and 11.0% of the total nitrogen, respectively. In addition, sediment adsorption accounted for 3.5% of the total nitrogen removal. The average reaction rates of nitrification, denitrification and plant uptake were 0.234,0.438 and 0.050 g/(m3·d) respectively.