潜流-表面流复合人工湿地的河道水质净化效果

Purification effect of integrated subsurface-surface flow constructed wetland on the river water

针对太湖流域的小河道水环境污染普遍较重的现状,结合潜流和表面流人工湿地系统技术的优点,设计并制作了阶梯式的复合人工湿地系统,前端采用潜流,后端采用表面流,试验区种植密度为25株/m2的茭草,研究其组合工艺对河道水质的净化效果,以期为河道人工湿地的设置提供技术参数。结果表明,复合人工湿地系统具有较强的污染物去除能力,HRT为3.4d时,7—12月对TN、TP、NH+4-N和高锰酸盐指数的平均去除率分别达到了64.3%、63.9%、74.6%、51.1%,较同期相同HRT下潜流人工湿地去除率分别提高了12.1、10.6、1.8、5.1百分点。其中,前端0.25距离分数的去除率占各自总去除率的74.5%～91.2%。

Based on the environmental conditions of Lake Taihu main inflow rivers and the current situation of water pollution, the ladder-type structured wetland which integrating the advantages of subsurface flow with surface flow wetland systems was designed. The front end of wetland was subsurface flow, back-end was the surface flow, and Zizania caduciflora was planted in test area under the density of 25 strains/mz. The purification effect of established wetland for polluted water was investigated, according to the analyzing results, technical parameters for constructing wetland were provided. The results indicated that the integrated constructed wetland had perfect purification efficiency, under the hydraulic retention time of 3.4 d, the average removal rate of TN, TP, NH＋-N and permanga- nate index were 64.3%, 63.9% ,74.6% and 51.1% respectively during July to December. Compared with those of subsurface flow constructed wetland operated in the same period, the removal rates of TN, TP, NH4＋-N and perman- ganate index were improved by 12.1, 10.6, 1.8 and 5.1 percent respectively. In the first 0.25 distance fraction, the pollutant removal rate occupied 74.5%-91.2% of the total.