建立人工湿地的目的及条件 随机间歇运行条件下人工湿地中磷的去除机制

　　摘 要：通过试验研究，考察了随机间歇进水运行条件下，水平潜流人工湿地对模拟径流中磷的去除效果与机制。结果表明：在随机间歇进水、进水表观水力停留时间为36 h的运行条件下，水平潜流人工湿地对模拟城市径流中总磷的去除率为59.3%，年平均去除负荷为13.826 g?m-2?a-1；对溶解性磷的去除率为29.8％，年平均去除负荷为3.310 g?m-2?a-1。植物吸收对模拟径流中总磷的去除贡献较小，但对溶解性磷的去除作用显著，植物对磷的年吸收量为1.816 g?m-2?a-1，分别占人工湿地对磷的年总去除量的13.2％和溶解性磷去除量的54.85％；磷在填料固体累积物中的沉积和填料对磷的直接吸附是人工湿地的主要除磷机制，磷在人工湿地填料固体累积物内的年储留量为5.372 g?m-2?a-1，占人工湿地对磷的年总去除量的38.9%，填料直接吸附去除的磷为6.640 g?m-2?a-1，占人工湿地年磷总去除量的48.0%。
　　关键词：人工湿地；磷；径流处理；随机间歇运行
　　中图分类号：X703
　　文献标志码：A
　　文章编号：1674-4764（2012）04-0105-06
　　Phosphorus Removal Mechanisms in Constructed Wetland under Stochastic Intermittent Inflow
　　XIAO Haiwen, ZHAI Jun, WANG Tao, LU Guanbin
　　(Key Laboratory of Three Gorges Reservoir Regions Eco-Environment, Ministry of Education, Chongqing 400045, P.R.China)
　　Abstract:Phosphorus removal and is mechanisms by horizontal subsurface(HSSF) constructed wetland to treat simulated runoff under stochastic inflow condition have been investigated based on an experiment study. The results indicate that under stochastic inflow condition and with constant inflow rate of nominal hydraulic retention time of 36 h, the removal rate of the experimental HSSF constructed wetland for total phosphorus(TP) and total phosphorus(DTP) are 59.3% and 29.8％ respectively, and the yearly removal load for TP and DTP are 13.826 and 3.310 g?m-2?a-1 respectively. Removal of phosphorus by macrophytes assimilation is 1.816 g?m-2?a-1, which makes up 13.2％ of the TP removal and 54.85％of the TDP removal in the constructed wetland. It is indicated that macrophytes assimilation is not the main mechanism for the removal of total phosphorus while it has significant effect on the removal of dissolved phosphorus. The main mechanism for phosphorus removal by the constructed wetland are phosphorus retention in sediments accumulated in the substrates and adsorption by the substrates. The yearly phosphorus retention in sediments accumulated in the substrates is 5.372 g?m-2?a-1, which contributes to 38.9% of the total phosphorus removal. And yearly phosphorus adsorption by the substrates is 6.640 g?m-2?a-1 , which contributes to 48.0% of the total phosphorus removal.
　　Key words:constructed wetland; phosphorus; runoff treatment; stochastic intermittent inflow
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　　随着点源污染控制水平的提高，面源污染对我国水环境的威胁日益突出。人工湿地作为一种废水生态处理技术，以其能随机间歇运行、抗冲击负荷能力强、无复杂操控设施等优势在农业径流及城市径流污染控制中的应用日益受到关注，现已成为面源污染中氮、磷等营养盐控制的重要技术对策之一［1-3］。虽然自20世纪初，第一个人工湿地建成运行至今，人工湿地在除磷方面的研究取得了重大进展［4］,但这些研究绝大多数都建立在连续流进水、水质水量相对恒定的常规稳态运行基础之上，这与雨水径流处理随机间歇进水，水质水量波动的运行条件有本质的差别。而在实际运行中，由于降雨导致的特殊的运行条件，径流处理人工湿地往往表现出与常规废水处理人工湿地明显相异的磷去除规律［5-8］。目前，针对径流处理人工湿地实际运行条件对磷去除规律的研究较少，径流处理人工湿地随机间歇运行下的磷去除机制并不明确，使得人工湿地在面源污染、富营养化控制领域的进一步应用受到很大限制。