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| Nitrogen Removal from Heavily Polluted River Water by a Series of Simulated Vertical-Flow Constructed Wetlands |
| Received:June 26, 2014 |
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| KeyWord:series vertical-flow constructed wetlands;river water;nitrogen;hydraulic load;hydrophyte |
| Author Name | Affiliation | E-mail | | LI Ke | School of Chemical and Environmental Engineering, China University of Mining and Technology(Beijing), Beijing 100083, China
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China | | | JIA Jian-li | School of Chemical and Environmental Engineering, China University of Mining and Technology(Beijing), Beijing 100083, China | | | LU Shao-yong | State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China | lushy2000@163.com | | WAN Zheng-fen | State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China | |
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| Abstract: |
| Constructed wetland is a cost-effective technique to treat contaminated water. Here a series of simulated vertical-flow constructed wetlands(four groups of three stage columns, each column measuring 90 cm in height, 9.5 cm in diameter, and packed with gravels of particle size from 4.4 to 26.4 mm in a height of 80 cm) planted with Phragmites communis were developed to treat water from Qinghe River of Beijing under greenhouse conditions. Effects of two hydraulic loads, three stages of series connection and vegetation on nitrogen removal rates were observed for 144 days. The influent water contained total nitrogen(TN) 3.42~17.99 mg·L-1, with an average of 12.36±4.65 mg·L-1, and ammonia nitrogen 0.91~9.89 mg·L-1, with an average of 5.92±3.34 mg·L-1. The TN removal rates were significantly higher under hydraulic load of 0.2 m3·m-2·d-1 than under 0.4 m3·m-2·d-1. The TN removal rates also had significant difference between one stage and three stage column systems(P<0.05), but had no difference in multistage column systems(P>0.05). The presence of hydrophytes significantly promoted nitrogen removal(P<0.05). Overall, the three stage column system with hydrophytes under hydraulic load of 0.2 m3·m-2·d-1 had the highest removal rate of TN and ammonia nitrogen, in which the ammonia nitrogen removal rate was 85.74%, and the average ammonia nitrogen in the effluent was 0.43 mg·L-1, below the grade-Ⅱstandard of surface water. Considering the removal efficiency and actual costs, two stage column systems with hydrophytes would be recommended. |
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