Li Linfeng, Li Yinghao, Biswas Dilip Kumar, Nian Yuegang, Jiang Gaoming
Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, PR China.
Bioresour Technol. 2008 Apr;99(6):1656-63. doi: 10.1016/j.biortech.2007.04.001. Epub 2007 May 25.
Three parallel units of pilot-scale constructed wetlands (CWs), i.e., vertical subsurface flow (VSF), horizontal subsurface flow (HSF) and free water surface flow (FWS) wetland were experimented to assess their capabilities in purifying eutrophic water of Taihu Lake, China. Lake water was continuously pumped into the CWs at a hydraulic loading rate of 0.64 m d(-1) for each treatment. One year's performance displayed that average removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH(4)(+)-N), nitrate nitrogen (NO(3)(-)-N), total nitrogen (TN) and total phosphorous (TP) were 17-40%, 23-46%, 34-65%, 20-52% and 35-66%, respectively. The VSF and HSF showed statistically similar high potential for nutrients removal except NH(4)(+)-N, with the former being 14% higher than that of the latter. However, the FWS wetland showed the least effect compared to the VSF and HSF at the high hydraulic loading rate. Mean effluent TP concentrations in VSF (0.056 mg L(-1)) and HSF (0.052 mg L(-1)) nearly reached Grade III (0.05 mg L(-1) for lakes and reserviors) water quality standard of China. Wetland plants (Typha angustifolia) grew well in the three CWs. We noted that plant uptake and storage were both important factors responsible for nitrogen and phosphorous removal in the three CWs. However, harvesting of the above ground biomass contributed 20% N and 57% P of the total N and P removed in FWS wetland, whereas it accounted for only 5% and 7% N, and 14% and 17% P of the total N and P removed in VSF and HSF CWs, respectively. Our findings suggest that the constructed wetlands could well treat the eutrophic lake waters in Taihu. If land limiting is considered, VSF and HSF are more appropriate than FWS under higher hydraulic loading rate.
对三个中试规模的人工湿地平行单元进行了试验，即垂直潜流（VSF）、水平潜流（HSF）和自由水面流（FWS）湿地，以评估它们净化中国太湖富营养化水体的能力。以0.64 m d(-1)的水力负荷率将湖水连续泵入各人工湿地单元进行处理。一年的运行结果表明，化学需氧量（COD）、氨氮（NH(4)(+)-N）、硝态氮（NO(3)(-)-N）、总氮（TN）和总磷（TP）的平均去除率分别为17 - 40%、23 - 46%、34 - 65%、20 - 52%和35 - 66%。除NH(4)(+)-N外，VSF和HSF在去除营养物质方面表现出统计学上相似的高潜力，前者比后者高14%。然而，在高水力负荷率下，FWS湿地与VSF和HSF相比效果最差。VSF（0.056 mg L(-1)）和HSF（0.052 mg L(-1)）的平均出水TP浓度几乎达到中国湖泊和水库水质Ⅲ类标准（0.05 mg L(-1)）。湿地植物（狭叶香蒲）在这三种人工湿地中生长良好。我们注意到植物吸收和储存是这三种人工湿地去除氮和磷的重要因素。然而，地上生物量的收获对FWS湿地中去除的总氮和总磷贡献了20%的氮和57%的磷，而在VSF和HSF人工湿地中，地上生物量收获分别仅占去除总氮和总磷的5%和7%的氮，以及14%和17%的磷。我们的研究结果表明，人工湿地能够很好地处理太湖的富营养化湖水。如果考虑土地限制，在较高水力负荷率下，VSF和HSF比FWS更合适。
