潜流人工湿地除氮的生态动力学模拟

Simulation of Nitrogen Removal in Subsurface Flow Constructed Wetland

对某潜流人工湿地建立生态动力学模型,利用MATLAB编程模拟湿地中氮素的迁移转化过程,确定了主要除氮机制。模拟结果显示,该模型能较好地模拟出水中有机氮、氨氮和硝态氮浓度的变化趋势和范围。进一步进行氮素质量平衡分析可知,该人工湿地的主要除氮机制为硝化、反硝化和植物吸收,有机氮、氨氮和硝态氮的总去除率为60.53%,其中反硝化过程去除43.10%,植物吸收去除13.98%,沉淀去除3.45%。

As a new technology of sewage treatment,constructed wetland has been accepted in many countries because of its high nitrogen-removal efficiency,low cost,simple operation,landscaping and so on.However,it is difficult to quantify the different nitrogen-removal processes,thus unable to attribute nitrogen-removal rate to substrate,plants and microorganism without mathematical model.We established an eco-dynamic model for a subsurface flow constructed wetland to investigate and quantify nitrogen transfer processes between water,matrix and plant.In the model,mineralization,nitrification,denitrification,plant take-up,microbial assimilation,precipitation,regeneration and decay processes were considered.Mass balance method is the core in building the mathematical model.The state variables in the model are aqueous species nitrogen（Org-N,NH4-N,NO3-N） nitrogen in matrix（N-gravel） and nitrogen in plan（N-Plants）.MATLAB programming was used to solve the mathematical model.The key mechanism of nitrogen removal was identified based on the simulation results.It was showed that the calibrated model could generally reproduce the patterns of concentration variations for organic nitrogen,NH4-N and NO3-N.Further mass balance analysis showed that the major nitrogen removal mechanisms in the constructed wetland were nitrification,denitrification and plant uptake.The total removal efficiency for organic nitrogen,NH4-N and NO3-N was 60.53%,of which denitrification process accounted for 43.10%,plant uptake 13.98%,sedimentation removal 3.45%.