GNF - Green Filter Burundi

Green Filter in Burundi

Adequate treatment of sewage water originating from a boarding school


Idea/aim of the project

A green filter will be constructed to ensure the adequate treatment of sewage water originating from a boarding school (500 pupils) in the village of Mutumba, thus reducing the risk of waterborne diseases and reducing the discharge of contaminated water into Lake Tanganyika.


Facing the reality of an increasing faecal pollution of the water bodies in the world, this pilot project aims to offer a realistic, simple and eco-friendly alternative for wastewater treatment in Burundi. It is planned to construct a real scale green filter pilot able to treat domestic sewage generated in a 500 students boarding school near the lake (around 2 km), and near Gitaza (about 5 km), in Mutumba.


Green filters are efficient and cost-effective wastewater treatment systems for small villages and rural areas. They consist on a pre-treatment unit (decanter and sifter) and a primary treatment unit (grease traps and primary settling tank), followed by very long but shallow and narrow canals that work as a superficial flow constructed wetland. The performance of the treatment is about 85 % to 90 % for BOD*1, COD*2, grease and oils, and suspended solids. Elimination of nutrients and coliform bacteria fluctuate between 45 to 55 % and 98 to 99 % respectively. Recently, this system have been successfully installed and operated in developing countries located in tropical regions of North, Central and South America.

Problem description

At least 1.8 billion people globally use a source of drinking water that is fecally contaminated and more than 80 per cent of wastewater resulting from human activities is discharged into rivers or sea without any pollution removal. The UN Sustainable Development Goals establish that universal and equitable access to safe and affordable drinking water shall be granted for all by 2030. That is an enormous challenge especially in rural and remote regions of developing countries where drinking water supply is inadequate and remarkably scarce. Schools, children's homes and even hospitals often do not have reliable access to clean water. Additionally, treating sewage is often expensive and difficult in developing countries. Therefore the population is dependent on the use of contaminated sources such as lakes, rivers or polluted wells often causing chronic and very severe water-related diseases. Contaminated water is also a frequent cause of infant death in developing countries. The crucial role of access to clean water in accomplishing the needed socio-economic development goals is widely recognized.

BOD*1: biochemical oxygen demand


COD*2: chemical oxygen demand

 The situation on site
 The green filter is finished and is now ready to filter the dirty water
 The water pump finally facilitates access to clean water
 Map of Lake Tanganyika

Project period:


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October 2017 – December 2018




Association Biraturaba


Alfred Kärcher SE & Co. KG