几种湿地植物净化生活污水COD、总氮效果比较

以无植被、基质为河砂的潜流型人工湿地为对照，研究了石菖蒲、灯心草和蝴蝶花3种类型植被、基质均为河砂的潜流型人工湿地净化生活污水COD、总氮的效果．结果表明，在污水COD浓度小于200mg·L^-1、总氮浓度小于30mg·L^-1的低浓度范围里，无植被的人工湿地和有植被的人工湿地对污水中COD、总氮均有很好的去除效果，两者差异不大，其COD去除率均达90％以上，总氮的去除率达80％以上．随着污水中COD和总氮浓度的增加，无植被人工湿地和有植被人工湿地去除COD和总氮的效果均有不同程度下降，两者差异明显，有植被的人工湿地能维持较高的COD、总氮的去除效果，无植被的人工湿地COD和总氮去除效果下降很快，植被在人工湿地系统去除污水COD和总氮过程中起着重要的作用．在整个试验阶段，石菖蒲植被人工湿地COD和总氮平均净化效率分别为80．46％和77．77％、灯心草人工湿地分别为75．53％和71．17％、蝴蝶花人工湿地分别为70．50％和66．38％，无植被人工湿地分别为61．39％和55．81％．同无植被人工湿地COD和总氮净化效果相比，石菖蒲植被人工湿地净化效果最好；其次为灯心草植被人工湿地，再次为蝴蝶花植被人工湿地．不同类型植被的人工湿地净化污水中COD和总氮的效果与其生物量关系密切，这与植被系统吸收同化有机物质和总氮数量、根际微生物分解有机物质和硝化-反硝化作用有关。

Purification efficiency of several wetland macrophytes on COD and nitrogen removal from domestic sewage

In order to investigate the role of wetland macrophytes in waster water purification and to select appropriate native filter plants in constructed wetland, three vertical-flow constructed wetlands were built with river sands as the substrates of Acorus gramineus, Juncus effusus and Iris japonica, and one without plant as the control. Investigation on the removal of COD and total nitrogen (TN) from domestic sewage showed that within lower concentrations of COD (<200 mg x L(-1)) and TN (<30 mg x L(-1)), more than 90% of COD and 80% of TN were removed from domestic sewage in all constructed wetlands. When the concentration of COD and TN increased, the purification efficiency of all constructed wetlands decreased to some extent. The constructed wetlands with macrophytes had a higher efficiency than control. Among the three constructed wetlands with macrophytes, the one with Acorus gramineus had an average purification efficiency of 80.46% for COD and 77.77% for TN, that with Juncus effusus was 75.53% for COD and 71.17% for TN, and the one with Iris japonica was 70.50% for COD and 66.38% for TN. The constructed wetland without vegetation had an average purification efficiency of 61.39% for COD and 55.81% for TN. Acorus gramineus was more capable of removing COD and TN than Juncus effusus and Iris japonica. Vegetation biomass was the main factor affecting the removal rate of COD and nitrogen, because it significantly correlated with the ability of absorbing organic substance and nitrogen, and with the nitrification and denitrification around roots.