潜流构建湿地氮素转化运移的理论模型研究

构建湿地中氮素的主要存在形态为有机氮和无机氮，无机态氮主要包括氨态氮和硝态氮两种形态。一方面，这些氮素之间通过矿化、氨同化、硝化、反硝化、吸附交换、植物吸收等物理、化学及生物学过程相互联系并相互转化；另一方面在构建湿地污水处理系统中，从进水到出水，这些不同形态的氮素又随多孔介质中的饱和流发生运移。根据氮素的转化机理和溶质运移理论，以构建湿地中氮素的溶质运移模型为基础，将氮素转化的机理过程作为源汇项包括到基本模型中，由不同形态氮素的运移转化模型相联合形成构建湿地中氮素转化运移的理论模型系统。根据文献调研，给出模型系统参数的参考值，并简要介绍了模型系统的计算机语言求解方法。该模型为深入研究构建湿地中污水脱氮综合机理提供工具，其结果为以脱氮为目的的构建湿地的设计提供科学参考。

Theory Model Based on Transformation Mechanisms and Solute ransportation of Nitrogen in Subflow Constructed Wetlands

In constructed wetlands, the main occurrence formation of nitrogen includes organic nitrogen and inorganic nitrogen, and the inorganic nitrogen includes ammonia nitrogen and nitrate nitrogen. The different formation of nitrogen is transformed reciprocally through some physical, chemical and biological process, such as mineralization, ammonia and nitrate nitrogen assimilation, nitrification, denitrification, adsorption and exchange of ammonia nitrogen, plant uptake, plant decaying and origanic nitrogen sedimentation. Furthermore, in constructed wetlands used by wastewater treatment, the nitrogen solutes are transported by saturated Darcy flow and dispersion flow in porous medium. According to transformation mechanisms and solute transportation of nitrogen in constructed wetlands, the theory model of nitrogen transformation and transportation is based on solute transportation equations, and mechanism courses of nitrogen transformation are included in the basic transportation equations as source items and sink items. The state variables of mathematical model include organic, ammonia, nitrate, and plant uptake nitrogen in constructed wetlands. Furthermore, the reference value of model parameters is given according to literature, and solution approach of how to use MATLAB to solve the model is given. This model can be used to estimate quantificationally nitrogen removal efficiency by different nitrogen transformation process and different influence factors, which can give quantificational parameter for the design of constructed wetlands, such as HLR(Hydraulic Load Ratio), HRT(Hydraulic Retention Time), Length of constructed wetlands, etc.