Skip to main content

Research Repository

Advanced Search

Wetland treatment at extremes of pH: A review

Koiv, M.; Mayes, W. M.; Mayes, Will; Batty, L. C.; Younger, P. L.; Jarvis, A. P.; Kõiv, M.; Vohla, C.; Mander, U.


M. Koiv

L. C. Batty

P. L. Younger

A. P. Jarvis

M. Kõiv

C. Vohla

U. Mander


Constructed wetlands are an established treatment technology for a diverse range of polluted effluents. There is a long history of using wetlands as a unit process in treating acid mine drainage, while recent research has highlighted the potential for wetlands to buffer highly alkaline (pH > 12) drainage. This paper reviews recent evidence on this topic, looking at wetlands treating acidic mine drainage, and highly alkaline leachates associated with drainage from lime-rich industrial by-products or where such residues are used as filter media in constructed wetlands for wastewater treatment. The limiting factors to the success of wetlands treating highly acidic waters are discussed with regard to design practice for the emerging application of wetlands to treat highly alkaline industrial discharges. While empirically derived guidelines (with area-adjusted contaminant removal rates typically quoted at 10 g Fe m 2 /day for influent waters pH > 5.5; and 3.5-7 g acidity/m 2 /day for pH > 4 to < 5.5) for informing sizing of mine drainage treatment wetlands have generally been proved robust (probably due to conservatism), such data exhibit large variability within and between sites. Key areas highlighted for future research efforts include: (1) wider collation of mine drainage wetland performance data in regionalised datasets to improve empirically-derived design guidelines and (2) obtaining an improved understanding of nature of the extremophile microbial communities, microbially-mediated pollutant attenuation and rhizospheral processes in wetlands at extremes of pH. An enhanced knowledge of these (through multi-scale laboratory and field studies), will inform engineering design of treatment wetlands and assist in the move from the empirically-derived conservative sizing estimates that currently prevail to process-based optimal design guidance that could reduce costs and enhance the performance and longevity of wetlands for treating acidic and highly alkaline drainage waters. © 2008 Elsevier B.V. All rights reserved.


Mayes, W. M., Batty, L. C., Younger, P. L., Jarvis, A. P., Kõiv, M., Vohla, C., & Mander, U. (2009). Wetland treatment at extremes of pH: A review. The Science of the total environment, 407(13), 3944-3957.

Journal Article Type Article
Acceptance Date Jun 25, 2008
Online Publication Date Aug 15, 2008
Publication Date Jun 15, 2009
Print ISSN 0048-9697
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 407
Issue 13
Pages 3944-3957
Keywords Wetland; Acid mine drainage; Alkaline filter media; Passive remediation
Public URL
Publisher URL