This study was conducted to investigate the retention and distribution of Cu, Pb, Cr, and Zn in a hybrid constructed wetland (CW) that consists of both vertical baffled flow wetlands (VBFWs) and horizontal subsurface flow wetlands (HSSFs) with unique flow regimes and oxygen distribution. The heavy metal concentrations in water, sediments, and plant tissues in the hybrid CW were analysed. The removal of heavy metals from the water stream in the monitoring period was not statistically significant. Metal concentrations in the sediments generally decreased along the wastewater treatment process. The reductive anaerobic condition in the VBFW may promote the sulphate reduction and form highly insoluble Cu, Pb, and Zn sulphides, resulting in the higher concentration of the bivalent cations in the VBFW sediments than the corresponding values in the HSSF; however, the aerobic and anoxic environments in the HSSF enhanced the removal of Cr with the co-precipitation of iron and manganese oxides, and their hydroxides. Metal concentrations in plant tissues were not significantly influenced by the concentrations in sediments, while roots contained statistically higher metal concentrations than stems and leaves. The sediments stored 94.01, 86.31, 95.85, and 89.51% of the total Cu, Pb, Cr, and Zn retained in the hybrid CW system, respectively, while only small fractions (<10%) were accumulated in the harvestable macrophyte tissues. It is important to clean not only the accessible sediments in free water surface tank and ponds but also the embedded sediments in vegetated beds for the sustainable removal of heavy metals.
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Research Article|
May 01 2013
Retention and distribution of Cu, Pb, Cr, and Zn in a full-scale hybrid constructed wetland receiving municipal sewage
Haiwen Xiao;
Haiwen Xiao
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
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Shengli Zhang;
Shengli Zhang
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
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Jun Zhai;
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
E-mail: zhaijun@cqu.edu.cn
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Qiang He;
Qiang He
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
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Adriaan Mels;
Adriaan Mels
2Wageningen University, Sub-department of Environmental Technology, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
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Kejia Ning;
Kejia Ning
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
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Jie Liu
Jie Liu
1Chongqing University, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Chongqing 400045, China
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Water Sci Technol (2013) 67 (10): 2257–2264.
Article history
Received:
August 25 2012
Accepted:
January 24 2013
Citation
Haiwen Xiao, Shengli Zhang, Jun Zhai, Qiang He, Adriaan Mels, Kejia Ning, Jie Liu; Retention and distribution of Cu, Pb, Cr, and Zn in a full-scale hybrid constructed wetland receiving municipal sewage. Water Sci Technol 1 May 2013; 67 (10): 2257–2264. doi: https://doi.org/10.2166/wst.2013.121
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