不同水生植物净化污染水源水的试验研究

选择大薸、浮叶眼子菜、萍蓬草、香菇草、花叶芦竹、芦竹和常绿鸢尾共7种水生植物为供试植物,通过静态水培试验,考察各种水生植物对模拟污水中氨氮、硝态氮、总磷、铁和锰的去除率和去除能力,并对污染物的去除机理进行了分析,以期筛选出净化污水的优势植物。结果表明,水生植物对氨氮和硝态氮的去除率分别为21.18%～27.25%和32.65%～45.92%。水生植物对磷的去除率为10.57%～25.81%,其中香菇草和浮叶眼子菜尤为突出,去除率分别为25.81%和25.31%。水生植物可以促进水体中还原性物质Fe2＋、Mn2＋的氧化,降低水体中铁和锰的浓度。与铁相比,水生植物对锰去除的促进作用比较明显。两类水生植物对不同污染物的去除能力存在较大差异,浮水植物对污染物的去除能力明显强于挺水植物,为挺水植物的3.15～5.64倍。

Effects of Hydrophytes on the Purification of Polluted Water

In this study,seven hydrophytes：Pistia stratiotes L.,Potamogeton natans L.,Nuphar pumilum（Hoffm.） DC.,Hydrocotyle vulgaris,Arundo donax var.Versicolor,Arundo donax,Iris gerinanica were selected and fed by simulated polluted water containing NH＋4-N,NO-3-N,phosphate,Fe2＋ and Mn2＋ as the main contaminants.The removal efficiency and removal capacity of tested hydrophytes were studied in the lab.Furthermore,the removal mechanism was discussed.It was found that the removal efficiency of hydrophyte systems for NH＋4-N and NO-3-N was 21.18%~27.25% and 32.65%~45.92%,respectively.The results indicated that the predominant mechanism for the removal of NH＋4-N and NO-3-N was most likely due to hydrophytes tissue uptake.The removal efficiency of hydrophyte systems for total phosphorus was 10.57%~25.81% and among the seven tested plants Potamogeton natans L.and Hydrocotyle vulgaris provided relatively higher removal efficiency with the removal efficiency of 25.81% and 25.31%,respectively.The roots of hydrophytes were able to release oxygen and/or oxidants into the rhizosphere,resulting in the oxidation of Fe2＋ and Mn2＋ and the precipitation of iron oxide or hydroxides from water.Moreover,comparing with Fe2＋,Mn2＋ was found to be more easily to be oxidized in hydrophyte systems.It was demonstrated that the removal capacities of floating plants were 3.15~5.64 times of emergent plants and that under identical conditions,floating plants were much more powerful in remediation of polluted water.