Effect of plants in constructed wetlands for organic carbon
and nutrient removal: a review of experimental factors contributing
to higher impact and suggestions for future guidelines
João M. Jesus
Anthony S. Danko
Received: 13 October 2017 / Accepted: 7 December 2017 / Published online: 18 December 2017
Springer-Verlag GmbH Germany, part of Springer Nature 2017
Constructed wetland is a proven technology for water pollution removal, but process mechanisms and their respective contri-
bution are not fully understood. The present review details the effect of plants on removal efficiency of constructed wetlands by
focusing on literature that includes experiments with unplanted controls for organic carbon and nutrient (N and P) removal. The
contribution of plant direct uptake is also assessed. Although it was found that several studies, mostly at laboratory or pilot scales,
showed no statistical differences between planted and unplanted controls, some factors were found that help maximize the effect
of plants. This study intends to contribute to a better understanding of the significance of the effect of plants in a constructed
wetland, as well as to suggest a set of experimental guidelines in this field.
Keywords Constructed wetlands
Impact of plants
Constructed wetlands (CWs) have been applied worldwide as
a treatment option for a great variety of industrial and domes-
tic wastewaters such as tannery (Calheiros et al. 2012), mu-
nicipal (Jinadasa et al. 2008), and aquaculture (Jesus et al.
2014), to name a few. As a greener and cheaper alternative
to more traditional and centralized treatment options, con-
structed wetlands play a major role in controlling inputs of
contaminants into both fresh and marine water ecosystems.
However, this technology has yet to be fully understood,
that is, while its removal efficiency is proven, the mechanisms
by which treatment is achieved, as well as their respective
contribution, remain associated with a high degree of uncer-
tainty. One of such aspects refers to the degree of significance
of the effect of plants in promoting treatment: although it is
known that vegetation has a positive effect (Vymazal 2011),
doubts remain on how significant the effect of plants is to the
treatment (Karathanasis et al. 2003; Lee and Scholz 2007;Fia
et al. 2014;Marchandetal.2014).
One way to quantify the significance of the effect of the
plants is to make comparisons with unplanted controls.
However, in research articles that have such controls, compar-
isons are often qualitative, i.e., it is only highlighted whether
or not plant systems outperformed unplanted controls (Kaseva
2004; Klomjek and Nitisoravut 2005; Calheiros et al. 2007).
Even review papers such as that of Vymazal (2011)onlyre-
port comparisons on relative terms such as positive, negative,
or no effect of plant presence.
Furthermore, other reviews often evaluate the potential of
different plant species without taking into account the removal
observed in the unplanted control. Although it is important
(Brisson and Chazarenc, 2009), this perspective is limited to
comparisons of the whole system (plant and substrate), not
isolating the effect of plants.
In many situations, taking into consideration the unplanted
controls can provide a very different perspective on plant
Responsible editor: Philippe Garrigues
* Maria-Teresa Borges
Centre for Natural Resources and the Environment (CERENA),
Department of Mining Engineering, University of Porto, Rua Dr.
Roberto Frias s/n, 4200-465 Porto, Portugal
Biology Department, Science Faculty, Porto University (FCUP), Rua
Campo Alegre s/n, 4169-007 Porto, Portugal
CIIMAR, University of Porto, Terminal de Cruzeiros do Porto de
Leixões, Av. General Norton de Matos s/n,
4450-208 Matosinhos, Portugal
Environmental Science and Pollution Research (2018) 25:4149–4164