Bäckström M
Division of Sanitary Engineering, Department of Environmental Engineering, Luleå University of Technology, Sweden.
Water Sci Technol. 2002;45(7):41-9.
Particle trapping in nine different grassed swales was measured successfully with a standardised runoff event simulation procedure. The percentage of total suspended solids removed ranged from 79 to 98%. It was found that sedimentation processes, rather than grass filtration governed the overall particle trapping efficiency. The highest particle trapping efficiency was observed in the field swales with dense, fully developed turf. A high infiltration rate was beneficial for the particle trapping and an increased swale length made it possible for smaller particles to be captured. A densely vegetated, ten metre long swale, receiving a stormwater flow of 1.0 litres per second, may capture a majority of the waterborne particles with settling velocities larger than 0.1 metres per hour. A simple model of particle trapping efficiency in grassed swales was developed and tested. It was found that mean swale residence time could be used as a design parameter for particle removal in grassed swales. The suggested exponential relationship between mean swale residence time and particle settling velocity associated with a certain trapping efficiency is so far only valid for a limited range of swale designs and residence times.
采用标准化径流事件模拟程序成功测量了九条不同草地洼地的颗粒截留情况。总悬浮固体的去除率在79%至98%之间。研究发现，控制整体颗粒截留效率的是沉淀过程，而非草地过滤。在具有茂密、发育完全草皮的实地洼地中观察到了最高的颗粒截留效率。高入渗率有利于颗粒截留，而增加洼地长度则使捕获更小颗粒成为可能。一条植被茂密、长10米、接收每秒1.0升雨水径流的洼地，可能会捕获大部分沉降速度大于每小时0.1米的水中颗粒。开发并测试了一个草地洼地颗粒截留效率的简单模型。研究发现，平均洼地停留时间可用作草地洼地颗粒去除的设计参数。到目前为止，平均洼地停留时间与具有一定截留效率的颗粒沉降速度之间建议的指数关系仅在有限的洼地设计和停留时间范围内有效。
