景观型人工湿地污水处理系统构建及植物脱氮效应研究

Construction of a Landscaping-type Wetland System for Wastewater Treatment and Analysis of Plant Denitrifying Effect

将15种景观植物,其中包括4种陆生木本植物引入人工湿地,用于构建景观型人工湿地污水处理系统.该实验系统由12个独立处理单元组成,其中包括由4个平行处理单元构成的一级处理系统及由8个处理单元构成的二级跌流系统.对植物在各处理单元中的氮积累特征及植物氮吸收对系统脱氮贡献率进行研究,结果表明,在进水TN浓度为37.5-55.6 mg/L时,植物吸收脱氮贡献率仅为1%3%,其不能准确反映植物在系统中的重要作用.因此,本研究采用植物脱氮效应（有植物与无植物系统脱氮的差异）来衡量植物在处理系统中的综合作用,其包括植物吸收贡献及植物与根际微生物、填料基质的协同效应之和,分析表明,植物协同效应占系统脱氮效应的80%以上.

A pilot landscaping-type wetland system for wastewater treatment was constructed by introduction of 15 selected ornamental plant species（including 4 terrestrial plant species）.The pilot system consists of 2 sequenced treatment units and 12 sub-units,i.e.,a primary treatment unit with 4 parallel cells and a secondary treatment unit with 8 subsurface flow cells.Designed experiments were conducted in the established system to investigate the characteristics of nitrogen accumulation in different plants and the contribution of plant nitrogen uptake to total nitrogen removal of the constructed wetland system.The result shows that the direct contribution by plant uptake to the total nitrogen removal is low,ca.1%-3% within the nitrogen concentration range 37.5-55.6 mg/L in the influent.Plant uptake does not fully reflect the important role of the plant species in the constructed wetland system for wastewater treatment as the function of the plant should include further its interaction with microorganisms and wetland fillers by enhancing microbial activities and filler adsorption capacities.The plant denitrifying effect,defined as the difference in nitrogen removal rates between units with and without plants,has been used to represent the contribution in nitrogen removal due to presence of plant in the system.The plant denitrifying effect thus includes both the plant nitrogen uptake and the interaction effect of plant with microorganisms and wetland fillers,the later being found to account for more than 80% of the total nitrogen removal in the established treatment system.