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

In Latin America, only 13.7 percent of the collected wastewater receives treatment before it is discharged to the environment or reused in agriculture (WHO and PAHO 2001). Efforts to mitigate negative environmental impacts and reduce public health risks require the development of low-cost wastewater treatment technologies that effectively eliminate wastewater contaminants and are simple to operate and maintain.
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 ability of this wetland to reduce pathogens renders the effluent suitable for irrigation of certain crop species if additional health and environmental protection measures are taken. This report describes several experiences with constructed wetland schemes in Central and South America: a full-scale pilot plant in Nicaragua, a community-managed constructed wetland scheme in El Salvador, and other systems in Colombia, Brazil, and Peru.
Although the report focuses on technology issues, it stresses the importance of adequate arrangements for operation and maintenance to guarantee the long-term treatment performance of the constructed wetland scheme. Furthermore, it presents examples of community participation and complementary actions such as promoting hygiene are crucial elements for sustainable wastewater treatment projects and maximization of health and environmental benefits.