Benzene removal with vertical-flow constructed treatment wetlands

Paul E. Eke, Miklas Scholz

Research output: Contribution to journalArticlepeer-review


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%; orthophosphate-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 degrees 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). (c) 2007 Society of Chemical Industry.

Original languageEnglish
Pages (from-to)55-63
Number of pages9
JournalJournal of chemical technology and biotechnology
Issue number1
Publication statusPublished - Jan 2008


  • aggregate
  • biodegradation
  • constructed treatment wetland
  • hydrocarbon
  • Phragmites australis
  • volatilization
  • OIL
  • SOIL


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