美人蕉根系对不同基质结构水平潜流人工湿地水力特性的影响

为了研究植物根系对不同基质结构潜流人工湿地水力特性的影响,根据填料渗透系数,分别设置单层及多层基质结构潜流人工湿地小试实验系统,以美人蕉作为湿地植物,在植物栽种前与成熟后对两系统分别开展示踪试验研究.实验结果表明,美人蕉根系对于单层结构人工湿地水力特性有较明显的改善作用,有效体积从0.49提高到了0.53,短路值由0.60降低到0.41,水力效率提高最大由43%提高到59%.比较而言,植物根系对多层结构湿地有效体积和短路值有轻微负面影响,而对水力效率则有明显的改善作用(由64%提高到83%).此外,植物成熟后,两人工湿地系统中示踪剂回收率均有所下降,其中,单层结构湿地降低较显著,回收率由72%降到62%.可见,植物根系对系统水力特性有较大影响,应在人工湿地设计过程中给予考虑.

Effect of canna roots on the hydraulic characteristics of the horizontal subsurface flow constructed wetlands with different matrix structures

In order to investigate the effect of plant roots on the hydraulic characteristics of the horizontal subsurface flow constructed wetlands (HSCWs) with different matrix structures, two small-scale HSCWs with mono- and multi-layer matrix structures were built according to the hydraulic conductivities of the filling. Canna was used as mesophytia, and trace tests were carried out before and after canna planting. The results showed that the hydraulic performance was improved significantly with the presence of canna roots in the mono-layer HSCW. The effective volume increased from 0.49 to 0.53, the short-circuiting ratio decreased from 0.60 to 0.41, and the hydraulic efficiency was enhanced from 43% to 59%. In contrast, the presence of plant roots had a slight negative effect on the effective volume and the short-circuiting ratio, and a great effect on the hydraulic efficiency (increased from 64% to 83%). Furthermore, a reduction of the tracer recovery rate was observed in both of the two mature HSCWs, especially in the mono-layer system with a decreasing from 72% to 62%.Itwas obvious that the hydraulic performances were significantly influenced by the presence of plant roots, which should be considered in the constructed wetlands design.