Aquatic Macrophytes in Constructed Wetlands: A Fight against Water Pollution

Abstract

There is growing concern among health institutions worldwide to supply clean water to their populations, especially to more vulnerable communities. Although sewage treatment systems can remove most contaminants, they are not efficient at removing certain substances that can be detected in significant quantities even after standard treatments. Considering the necessity of perfecting techniques that can remove waterborne contaminants, constructed wetland systems have emerged as an effective bioremediation solution for degrading and removing contaminants. In spite of their environmentally friendly appearance and efficiency in treating residual waters, one of the limiting factors to structure efficient artificial wetlands is the choice of plant species that can both tolerate and remove contaminants. For sometimes, the chosen plants composing a system were not shown to increase wetland performance and became a problem since the biomass produced must have appropriated destination. We provide here an overview of the use and role of aquatic macrophytes in constructed wetland systems. The ability of plants to remove metals, pharmaceutical products, pesticides, cyanotoxins and nanoparticles in constructed wetlands were compared with the removal efficiency of non-planted systems, aiming to evaluate the capacity of plants to increase the removal efficiency of the systems. Moreover, this review also focuses on the management and destination of the biomass produced through natural processes of water filtration. The use of macrophytes in constructed wetlands represents a promising technology, mainly due to their efficiency of removal and the cost advantages of their implantation. However, the choice of plant species composing constructed wetlands should not be only based on the plant removal capacity since the introduction of invasive species can become an ecological problem.

Constructed Wetlands to Face Water Scarcity and Water Pollution Risks: Learning from Farmers’ Perception in Alicante, Spain

“…As transition zones between terrestrial and aquatic environments [39], CWs are perceived as a cost-effective (low-cost and straightforward construction, operation and maintenance reduced costs, or energy biomass production) [40] and ecological and sustainable technology for treating different types of wastewater without the input of fossil fuels [41]. Likewise, CWs can contribute to flooding risk mitigation, stormwater runoff management, and increase water supply [42] by constituting an alternative option to conventional wastewater treatment plants (WWTPs) [43].…”

Ecosystem services provided by freshwater macrophytes

“…The maintenance of a clear-water state by submerged macrophytes helps improve water quality in relation to eutrophication, but macrophytes benefits for water quality goes beyond this aspect. The concentrations of several inorganic and organic pollutants, including trace metals, atrazine, pharmaceuticals, pesticides and nanoparticles (Srivastava et al, 2008;Dhote & Dixit, 2009;Guimara ˜es et al, 2011;Kochi et al, 2020;Dias et al, 2021), only to cite some examples, reduce in the presence of macrophytes. The mechanisms explaining this ESs are beyond the scope of this review, but they are related to direct (e.g., absorption) and indirect (e.g., changes in the environment features, providing habitat for bacteria etc.)…”

Phytoremediation by ornamental plants: a beautiful and ecological alternative

“…Usually, in CWs, aquatic macrophytes species are used. These species are considered important ecological indicators, but different from ornamental species, there is a difficulty in allocating biomass at the end of the cycle (Kochi et al 2020). Moreover, after the uptake of significant numbers of contaminants, aquatic plants begin to senesce and rot, releasing the elements back to the water column, increasing their concentration again (Wang et al 2021).…”