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Improvements to the wastewater treatment plant with an artificial wetland

By IW:LEARN

November 27^th, 2025

Interview with Gustavo Alvarado, Civil Engineer from the Secretariat of the Cartagena Convention, with contributions from ALIARSE, the implementing organisation in Costa Rica.

El Mora is a rural district of Turrialba, Costa Rica; a mountainous area known for its extensive cheese production and the presence of the colossal Turrialba volcano, which gives the region its name.

The community, comprised of approximately 570 houses, is known for its organisation and strong sense of responsibility and commitment to managing the community water system. They understand their responsibility to operate and subsequently maintain the system that will be built and actively promote water conservation within the community. Their efforts range from visits by kindergarten children to home plumbing workshops. This proactive attitude is essential for ensuring the sustainability of the infrastructure and maintaining the project over time. As a result, the people of El Mora have become active participants in the GEF CReW+ project.

Turrialba, Costa Rica. Photo: Joseph Piña/Unsplash.

What is the existing problem and how does the project address these challenges?

“The existing treatment plant is operated by the El Mora Community Water and Sewerage System Management Association (ASADA) in Turrialba and is currently operational. However, water treatment levels can be substantially improved. Therefore, the GEF CReW+ project seeks to optimize the treatment plant and simultaneously construct a pilot plant using nature-based technology—an artificial wetland—to demonstrate that a simple and easy-to-operate technology is an appropriate and feasible solution for reducing pollutants reaching the Caribbean Sea.

ASADA El Mora has transformed its experience into a living source of learning. More than two decades of continuous work have allowed them not only to improve their service but also to share their knowledge with other ASADAs, generating collaborative networks and mutual strengthening.

In 2025, this trajectory positioned ASADA as a key player in the GEF CReW+ project, a regional initiative that seeks to improve wastewater management in Latin America and the Caribbean. Its role was fundamental in the development of a Horizontal Flow Constructed Wetland, a nature-based solution that complements the existing treatment plant and now directly benefits 2,000 people.

But beyond the infrastructure, this wetland represents a commitment to public health, environmental protection, and water security. It is also a concrete measure of adaptation to climate change, demonstrating how sustainable solutions can emerge from the local level.”

Wastewater Treatment Plant, ASADA El Mora. Photo: Crew+.

What does the intervention involve?

“The basic idea behind this intervention is to construct an artificial wetland at the outlet of the existing operating reactor, providing additional treatment to improve the quality of the treated water. As this is a pilot project, monitoring data will be collected to document its implementation and facilitate the replication of this technology in other projects in the Costa Rican Caribbean.

The magnitude of the impact is tangible: the wetland in El Mora treats approximately 365 m³ of wastewater per day, which is equivalent to more than 133,000 m³ of water per year that is prevented from polluting the Aquiares River and, consequently, the watersheds that drain into the Caribbean Sea. Every cubic meter treated represents a direct contribution to the health of the community, the protection of ecosystems, and the strengthening of local water security, reaffirming the value of investing in nature-based solutions that originate from and are sustained by the communities themselves.”

How can we see the concepts of Integrated Water Resources Management applied in this project?

“This project, like Integrated Water Resources Management, aims to implement simple, easy-to-operate technologies based on natural processes that do not depend on spare parts that must be purchased abroad, nor on the use of electricity for their operation.

By further refining the effluent from the treatment plant before it reaches the Aquiares River, this project improves the river's water quality, making it suitable for recreational, agricultural, and other activities, thus promoting a circular water economy in the Turrialba area.”

How is the sustainability of this intervention guaranteed?

“The El Mora case demonstrates that when solutions are designed based on the realities of the communities, with the active participation of local stakeholders, the results are more sustainable, replicable, and transformative. The wetland is not just an engineering project; it is a symbol of what can be achieved when we work together with vision, commitment, and trust.”

About the project

GEF CReW+: An integrated approach to water and wastewater management using innovative solutions and promoting financing mechanisms in the Wider Caribbean Region, is a partnership project funded by the Global Environment Facility (GEF) that is being co-implemented by the Inter-American Development Bank (IDB) and the United Nations Environment Programme (UNEP) in 18 countries of the Wider Caribbean Region (WCR). This project builds upon its previous successful phase “The Caribbean Regional Fund for Wastewater Management (CReW)” project (2011-2017). GEF CReW+ is being executed by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, the Organisation of the American States (OAS) and the Secretariat of the Cartagena Convention (CAR/RCU) on behalf of the IDB and UNEP respectively.