GNF - Green Filter in four Latin American Countries

Green Filters in four Latin American Countries

Innovative Wetlands (Green Filter) as a cost-effective measure to improve water and living conditions of people in rural areas in four Latin American countries


How does a Green Filter work.

 How does a green filter work.


Pollution and eutrophication are big threats to all our water bodies. In almost all developing countries, domestic untreated sewage flows into rivers, lakes, lagoons and generally into the landscape. This issue becomes of large relevance in isolated rural areas where the discharge of wastewater from communities generates not only an enormous environmental problem - stressing the ecological balance of aquatic ecosystems - but also a humanitarian challenge, as local residents suffer the consequences of inadequate sanitary and hygiene conditions. Although being implemented in Colombia, Paraguay, Mexico and Nicaragua, and in five different scenarios, the problems to be tackled with this project share the same ground, the lack of efficient wastewater treatment technologies in households and public facilities is leading to a severe deterioration of the living conditions of the inhabitants, who specially in poor rural communities dependent on the use of surface water. This unsatisfactory waste water situation has also massive negative effects on ecosystem services (for example, water and biodiversity) on site. In rural areas these problems cannot be solved as in industrialized countries by central, technical wastewater treatment plants because of high construction and operating costs.


Against this background, the "natural" way to treat wastewater in constructed wetlands represents a plausible and viable alternative. Following an innovative biomimicry approach, the so called Green Filter is a cost effective solution to sewage treatment based on natural processes of contaminant degradation in wetlands. This technology and its advantages have successfully been proven in four different communities in Colombia. Following the same strategy this technology will be transfer to Nicaragua, Mexico and Paraguay as well as to a new filter in Colombia.

Project Goals

The aim of the project is the immediate improvement of living conditions of the poorer rural population in the five regions. By transferring cost efficient technologies and strategies on waste water management, successfully tested and implemented in rural areas of Colombia, the measures will significantly ameliorate the sanitation and hygiene situation of more than 2,200 people in the five communities and will have an indirect positive effect on more than 7,000 people. The project’s aim is also to provide the communities with the skills, knowledge and equipment required for the maintenance and the further self-sufficient development of the wastewater treatment facilities. The pilot plants represent an efficient mode of operation and to convince local policy makers in municipalities, contributing to dissemination of the technology and improvement the living conditions of other people in rural areas. With the involvement of municipalities, environmental authorities and public service suppliers, the project also aims to influence the wastewater treatment policies on the different countries in a regional and/or national level.


Green filters are characterized by low investment, operating and maintenance costs and are independent of electricity and chemical additives. They are an economically and ecologically measure for the improvement of poor people’s lives in rural areas, natural water ecosystems and ecosystem services (drinking water, cleaning, hygiene, irrigation, biodiversity, livestock, fish). The measures will be focused on installing capacity and bringing the knowledge and technology to demonstrate that this is a viable alternative tool to solve the sanitation problem in the four countries. The design and construction of the filters will allow the different project sites to achieve the minimum permissible parameters in terms of waste water pollutants established in their legislations. The measures within the project a have long-term positive impact on the social, health, economic and environmental situation of these poor people. The six main activities can be summarised as:

  • Construction of five green filter and two toilet units
  • Capacity building and training
  • Environmental education and awareness
  • Monitoring of water quality
  • Transfer of knowledge, network work and influence on political framework conditions
  • Green Filter Latin America Conference
 Water pre and post filter
 Green Filter at Lagoon Fúquene, Colombia
 Water Hyacinth
 Green Filter Colombia - Handbook (in Spanish and English)

The technical parameters of all planned filters are:

 The technical parameters of all planned filters are:

Main Funding:

 German Federal Ministry for Economic Cooperation and Development (BMZ)


 Alfred Kärcher GmbH & Co. KG

Project Duration:


Project Countries: 







Project Partners:

September 2016 - April 2019


Colombia, Mexico, Paraguay, Nicaragua


German Federal Ministry for Economic Cooperation and Development (BMZ)


Alfred Kärcher SE & Co. KG


Fundación Humedales, Colombia
Instituto Corazón de la Tierra, Mexico
Fundación Cuenca Lerma Lago Chapala Santiago A.C., Mexico
Fundación Moisés Bertoni, Paraguay 

Fundación Amigos del Rio San Juan FUNDAR, Nicaragua