Groundwater provides the only realistic water supply option in many rural areas across the globe, providing good water quality and showing resistance to droughts. However, there is very little hydrogeological input with scientific evidence on groundwater quality, posing a risk to groundwater use. The East African Rift Valley region is characterised by high availability of fluoride in surface water and groundwater. It is one of the regions where we record the highest fluoride concentration in the world (Ethiopia 1.3–300 mg/L; Kenya up to 180 mg/L; Tanzania up to 70 mg/L).
Geological insight into fluoride contamination
The EU-funded FLOWERED project wished to develop a sustainable water management system in areas affected by fluoride contamination in water, soils and food in specific test areas of the East African Rift Valley countries (Ethiopia, Kenya, Tanzania). “Our goal was to generate sustainable and suitable strategies for water use,” explains project coordinator Giorgio Ghiglieri. Considering that geological and hydrogeological conditions influence water contamination, project partners investigated the chemistry of the groundwater in these countries. They discovered that the fluoride level of the East African Rift Valley groundwater varied markedly from place to place. This was due to different factors that influenced fluoride mobility and concentration, including the time of interaction of groundwater with fluoride-rich minerals and other geogenic factors. “Obtaining hydrogeological information of an area can help local or government agencies build wells that intercept good quality water,” emphasises Ghiglieri. The FLOWERED scientific approach is based on detailed knowledge of the geological and hydrogeological setting that affects water contamination. Geological, hydrogeological, hydro-chemical, geophysical and hydrological investigations contributed to the localisation of safe groundwater in the study areas. This was a prerequisite for implementing sustainable water management, as well as for water sanitation and agricultural purposes. Furthermore, the project highlighted that protracted crop irrigation with fluoride-contaminated water considerably affects the quality of the soil and leads to fluoride uptake by crops, elevating the concentration in edible parts of maize, tomato and bean. This poses further risks to human and livestock health.
A defluoridation device
FLOWERED designed and developed a defluoridation device that consists of a 20 L tank and a recirculating pump that mixes the water and octacalcium phosphate. The device is powered by a car battery and uses a fixed amount of octacalcium phosphate for every defluoridation cycle. Testing the prototype in rural areas of Tanzania demonstrated a decrease in fluoride to levels below the World Health Organization limit in just 2 hours. Importantly, it shows no secondary negative effects on water quality and only costs around USD 220. To implement the FLOWERED water sanitation approach, partners conducted a survey to explore which psychological and demographic determinants influence the consumption of fluoride-free water. Results were encouraging and emphasised the importance of raising awareness via educational programmes about the danger of consuming untreated water. Therefore, international or regional interventions should aim to mitigate the defluoridation cost and ensure access to clean water as per the UN Millennium Development Goals. Overall, FLOWERED provided important results on water contamination and its impact on human health, agriculture and livestock. “We confirmed that fluoride contamination of water requires mitigation measures that depend on scientific knowledge and evidence, political commitment and support of the population,” concludes Ghiglieri. Fostering these efforts will be paramount for groundwater management in countries affected by water contamination.
FLOWERED, fluoride, groundwater, defluoridation, water contamination, octacalcium phosphate, East African Rift Valley