Benzene removal with vertical‐flow constructed treatment wetlands |
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Authors: | Paul E Eke Miklas Scholz |
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Affiliation: | Institute for Infrastructure and Environment, School of Engineering and Electronics, William Rankine Building, Mayfield Road, The King's Buildings, The University of Edinburgh, Edinburgh EH9 3JL, UK |
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Abstract: | BACKGROUND: Twelve vertical‐flow experimental wetlands have been constructed using different compositions, and were operated in batch‐flow mode to reduce pumping costs. Six wetlands were located indoors and six outdoors. Benzene was used as a representative example substance to assess the removal of low molecular weight petroleum compounds. RESULTS: Findings indicate that the constructed wetlands remove benzene (inflow of approximately 1.3 g L?1) from hydrocarbon‐contaminated wastewater streams with better indoor (controlled environment) than outdoor treatment performances. Overall mean removal efficiencies for the experimental rig placed outside were as follows: benzene 85%, chemical oxygen demand (COD), 70%; ammonia‐nitrogen, 83%; nitrate‐nitrogen, 88%; ortho‐phosphate‐phosphorus, 58%. In comparison, removal efficiencies for the experimental rig placed indoors were higher: benzene 95%, COD, 80%; ammonia‐nitrogen, 90%; nitrate‐nitrogen, 94%; ortho‐phosphate‐phosphorus, 66%. Benzene removal was predominantly due to volatilization after 1 day of retention time. CONCLUSION: The use of aggregates (sand and gravel) and the presence of Phragmites australis (Cav.) Trin. ex Steud. resulted in no significant difference in terms of benzene, redox potential, dissolved oxygen, 5‐day at 20 °C N‐allylthiourea biochemical oxygen demand, COD and nutrients removal. Statistical differences were assessed by analysis of variance and Tukey HSD tests (P < 0.05). Copyright © 2007 Society of Chemical Industry |
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Keywords: | aggregate biodegradation constructed treatment wetland hydrocarbon Phragmites australis volatilization |
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