Aeration to Promote Nitrification in Constructed Wetlands

• Published in: Environmental technology Vol. 20; no. 1; pp. 69 - 75
• Main Authors: Cottingham, P. D., Davies, T. H., Hart, B. T.
• Format: Journal Article
• Language: English
• Published: London Taylor & Francis Group 01.01.1999; Selper
• Subjects: aeration; Applied sciences; Biological and medical sciences; Biological treatment of waters; Biotechnology; Constructed wetlands; denitrification; Environment and pollution; Exact sciences and technology; Freshwater; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; nitrification; nitrogen removal; Phragmites australis; Pollution; reed beds; Wastewaters; Water treatment and pollution; Monocotyledones; Phragmites australis; Biological purification; Aeration; Reed; Gramineae; Artificial medium; Angiospermae; Nitrification; Denitrification; Spermatophyta; Waste water purification; Wetland
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593332008616794

As part of a three year study of the use of reed beds for the treatment of wastewater, two pilot scale constructed wetlands (30m × 5m), one planted with Phragmites australis and the other serving as an unplanted control, were used to treat primary domestic sewage. This paper describes an experiment conducted to test the hypothesis that increasing available oxygen by aeration of the wastewater in the treatment beds could increase nitrification, and hopefully nitrogen removal rates. Prior to aeration, the influent nitrogen load in the wastewater passing through the beds was reduced by approximately 45% and 10% in the planted and control beds respectively. With aeration of the wastewater as it passed through each bed, nitrogen removal was approximately 51% and 20% for the planted and control beds respectively. High rates of nitrification were recorded for the planted bed with aeration, but removal of nitrogen by denitrification was limited, probably because of the absence of a suitable carbon source (indicated by low BOD 5 concentrations). High nitrification rates were not recorded in the unplanted control bed. The higher BOD 5 concentration measured in this bed may have caused increased competition for available oxygen between heterotrophic bacteria and the relatively slow-growing nitrifying bacteria, resulting in lower rates of nitrification but more efficient denitrification.