Water purification with a biosand filter in Tanzania : A minor field study - Karagwe District, Tanzania

In Karagwe district in northwest Tanzania, the non-governmental organisation Mavuno is working with water scarcity and drinking-water quality issues within the local community. Mavuno started a boarding school for girls in Chonyonyo village in the district in January 2016. The school is self-sufficient of water and relies on rainwater as a raw water source. The main objective of this study was to investigate water purification with a biosand filter, built of local materials at the Chonyonyo school. The filter performance was analysed by studying the reduction of indicator organisms in the filtered water. The knowledge obtained should be transferred to employees at Mavuno, allowing them to independently operate the biosand filter and analyse the water quality. The study was done as a Minor field study with support from SIDA, in collaboration with Swedish Engineers without borders and Mavuno. The study includes a literature review and a field study where a biosand filter was built and tested. After construction, the biosand filter was operated for 6 weeks during which water samples were collected and analysed. Water samples were collected from the influent raw rainwater and effluent filtered water. The microbial properties of the water samples were investigated by analysis of the indicator organisms total coliform bacteria, e.coli and enterococci. The analysis was performed with the QuantiTray-2000® and most probable number (MPN) method from IDEXX Laboratories. Additionally, temperature and pH was measured on all water samples. The water quality of the samples was compared to Swedish, Tanzanian and WHO guideline values. The water quality analysis showed that the raw water in the rainwater tank at Chonyonyo school did not have safe drinking-water quality with regards to the levels of total coliform bacteria and enterococci. The pH in the rainwater tank was high (mean value 10.1) and did not meet the Tanzanian standards for drinking-water, while it was satisfactory acco
biosand filter, water purification, Tanzania, Karagwe