When Eco-engineered wetlands Works with Nature

Minh-Phuong Thi Duong

Ton Duc Thang University, Vietnam

23-07-2026

© Wix

The world produces an estimated 259.5 billion cubic metres of wastewater each year. Yet only about 63% is collected, and roughly half is treated (Jones et al., 2021). The rest can carry nutrients, pathogens, metals, pharmaceuticals, and other contaminants into rivers, soils, and groundwater.

One response may be to build treatment systems that work more like ecosystems.

Constructed wetlands are engineered environments containing water, plants, porous substrates, and microbial communities. As wastewater moves through them, particles settle, contaminants attach to soil or gravel, microorganisms break down organic matter, and plants support chemical and biological processes around their roots. Unlike many conventional treatment plants, these systems can operate with relatively low energy and chemical inputs while creating green spaces and supporting biodiversity (Waly et al., 2022).

Their apparent simplicity, however, should not be mistaken for technological stagnation.

Modern eco-engineered wetlands increasingly combine natural processes with carefully targeted enhancements. Vertical-flow units can introduce oxygen and support nitrification, while horizontal subsurface-flow beds provide anoxic conditions that enable denitrification. Placed sequentially, these systems can remove pollutants that either unit would struggle to address alone. Some hybrid wetlands have achieved removal rates above 90% for organic pollution and substantial reductions in nutrients and pathogens (Remmas et al., 2026).

New substrates are also improving performance. Biochar can capture nutrients, metals, and organic contaminants, while recycled concrete can bind phosphorus. Zeolite can remove ammonium, and activated carbon can trap micropollutants (Fernandez et al., 2022). In one study, combining several adsorptive materials achieved approximately 91% removal of chemical oxygen demand and more than 90% removal of copper, nickel, and zinc.

Yet innovation introduces a difficult balancing problem.

Adding pumps, aeration, photocatalysts, electrodes, nanoparticles, or reactive substrates can make wetlands more compact and effective. But every enhancement also adds energy requirements, maintenance needs, costs, and possible environmental risks. A system intended to imitate nature can gradually become another complex mechanical plant decorated with reeds.

This matters because infrastructure decisions are rarely easy to reverse (Vuong, 2026). Once municipalities invest in a particular design, train personnel, establish regulations, and build supply chains around it, the system begins reinforcing itself. Even if better options later emerge, replacing the established approach can be more difficult than avoiding unsuitable designs from the beginning.

The challenge, therefore, is not to choose between “natural” and “engineered” treatment as absolute alternatives. It is to identify how much intervention is necessary for a particular wastewater type, climate, land constraint, and discharge standard.

A rural community treating domestic wastewater may benefit from a simple wetland using local plants and gravel. An industrial site facing strict contaminant limits may require hybrid stages and specialized media. Cold climates may justify bioaugmentation or targeted aeration, but not necessarily continuous energy-intensive operation.

Constructed wetlands are most promising when engineering strengthens ecological processes rather than replacing them. Their future depends on designing systems that remain adaptable, locally appropriate, and conscious of the long-term pathways created by today’s technical choices (Vuong and Nguyen, 2026).

References

Fernandez-Gatell, M., et al. (2022). Microbial activity enhancement in constructed wetlands operated as bioelectrochemical systems. Chemosphere, 287, 132383. https://doi.org/10.1016/j.chemosphere.2021.132383

Jones, E. R., et al. (2021). Country-level and gridded estimates of wastewater production, collection, treatment and reuse. Earth System Science Data, 13, 237-254. https://doi.org/10.5194/essd-13-237-2021

Overton, O. C., et al. (2023). Wetland removal mechanisms for emerging contaminants. Land, 12, 472. https://doi.org/10.3390/land12020472

Remmas, N., et al. (2026). Eco-engineered wetlands: exploring nature-based innovations for sustainable effluent treatment. Current Opinion in Environmental Sustainability, 83, 101669. https://doi.org/10.1016/j.cosust.2026.101669

Waly, M. M., et al. (2022). Thomson Constructed wetland for sustainable and low-cost wastewater treatment. Land, 11, 1388. https://doi.org/10.3390/land11091388

Vuong, Q. H. (2026). Once the Door Swings Shut. http://books.google.com/books/about?id=Qur0EQAAQBAJ 

Vuong, Q. H., and Nguyen, M. H. (2026). The Sage's Empty Purse: An Entropy-Based Theory of Value Formation. https://books.google.com/books/about?id=mRv1EQAAQBAJ