Constructed wetlands: a promising wastewater treatment system for small localities. Experiences from Latin America

Constructed wetlands: a promising wastewater treatment system for small localities. Experiences from Latin America

Wetlands can serve as natural wastewater treatment systems

Concentrating on experiences with constructed wetland schemes in Central and South America, this report provides an overview of how constructed wetlands serve as natural wastewater treatment systems. It focuses especially on the subsurface horizontal flow type — a technology that has high potential for small and medium-size communities because of its simplicity, performance reliability, and low operation and maintenance requirements.

The report stresses the importance of adequate arrangements for operation and maintenance to guarantee the long-term treatment performance of the constructed wetland scheme. Furthermore, community participation and complementary actions such as promoting hygiene are crucial elements for sustainable wastewater treatment projects and maximization of health and environmental benefits. Subsurface horizontal flow constructed wetland systems are a feasible technical option for the treatment of wastewater from small to medium-size communities; however, adequate water supply and wastewater recollection systems are an important prerequisite for constructed wetland schemes. Overall, sustainable operation and maintenance remains the primary challenge.

Experiences with constructed wetland technology in several countries of Central and South America over the past years have provided a number of specific lessons including:

  • capacity building and training are required to ensure that local institutions and organisations can carry out design and construction. Design standards based on local experiences would help to disseminate the technology and to avoid basic design and construction errors
  • when a municipality does not have the water and sanitation responsibility, the community must be organised to manage operation and maintenance of the system, as well as fee collection. This task will require building the capacity of community-based organisations and local authorities to manage the treatment plant successfully
  • demand and user participation - in general, the implementation of constructed wetland systems for treatment of wastewater must be based on the genuine demand of users
  • the reuse of treated wastewater can contribute to the sustainability of the treatment system. If the appropriate health and environmental protection measures and good agricultural practices are taken into account, the reuse of wastewater can help to conserve water, protect the environment, and generate income.
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