梯级河滩湿地模型对受污染河水氮磷和COD_(Cr)的净化效果

Purification effect of N、P and COD_(Cr) of cascaded surface flow wetland model on polluted river water

在贾鲁河畔构建3组并联的梯级河滩湿地模型,引种9种不同类型的湿地植物进行筛选试验,将湿地模型串联运行比较研究3种不同植物配置的梯级湿地对受污染河水的净化效果,在此基础上设定12h和24h等两组不同水力滞留时间,研究延长滞留时间对水质净化效果的影响。试验结果表明:对氮磷和有机物的去除效果挺水植物明显好于沉水植物,其中茭草(Zizania caduciflora)、荆三棱(Scirpus fluviatilis)和狭叶香蒲(Typha angustifolia)去除效果最好;沉水植物和挺水植物对氨氮的去除表现好于浮叶植物;延长水力滞留时间对改善水质净化效果明显,滞留时间由12h延长到24h后,TN、TP、氨氮和CODCr去除率分别提高10.2%、21.7%、30.2%和12.9%,对氨氮的净化效果改善最为明显;挺水植物+沉水植物+浮叶植物组合较单纯挺水植物组合在对氨氮和TN去除效果方面表现出较明显的优势,主要是由于不同类型湿地植物所营造的好氧、厌氧环境提高了对氨氮和TN去除效果。研究结果证明在湿地植被组建中,根据进水水质,应灵活选择植物种类,进行合理的植物配置,可提高湿地的净化效果。

A model of cascaded surface flow wetlands was constructed in the Jialu River floodplain to assess the removal efficiency of various aquatic plants with different hydraulic loading rates.Our results indicated that for the removal of nitrogen,phosphorus and organic matter,the emergent plants such as Zizania caduciflora,Scirpus fluviatilis and Typha angustifolia were better than the sub-merged plants.Submerged plants and emergent plants are better than the floating-leaved plants on the removal of ammonia nitrogen.Increases in hydraulic retention time led to the improvements of water quality.Removal rates of total nitrogen,total phosphorus,ammonia and CODcr increased by 10.2%、21.7%、30.2% and12.9%,respectively,when hydraulic retention time increased from 12 h to 24 h.Wetlands grown with a combination of submerged,emergent and floating-leaved plants show significantly higher removal rates of nutrients,especially total nitrogen and ammonia nitrogen,than the wetlands grown with emergent plants only.This study demonstrated that wetland design with different combinations of aquatic plants can ultimately improve the effectiveness of nitrogen removal.