STAKEHOLDERS WORKSHOP St Mary's Pastoral Centre , Nakuru 27th May 2010 Topic: Fluoride, Fluorosis and Defluoridation by Linda Korir CDN WQ Catholic Diocese of Nakuru, Water Quality Section

CATHOLIC DIOCESE OF NAKURU (Water Quality Program ) It is a development program under Catholic Diocese of Nakuru It is one of the subsection in the water program the others are water drilling and water supply Established in 1998 to research, develop and implement an appropriate technology for fluoride removal Most of the drilled bore hole had high fluoride content exceeding the recommended WHO guideline of 1.5 mgF/L

Fluorosis No medical cure Prevention

Fluoride in the world > 200 Mio. people live in fluorotic areas CDN WQ > 200 Mio. people live in fluorotic areas

Kenya Map Showing Boreholes with Fluoride Concentrations at Differing levels Key <1.5mgF/L 1.5-2.5mgF/L >2.5mgF/L

Defluoridation Technology Bone char technology has been in use since 1998 There was a problem of the lifespan of the filter This lead to the development of the Ca phosphate based contact precipitation method to prolong filter life The technology is promising and full scale implementation started in 2006-Kenya Further requirement for research has lead to the CDN WQ – Eawag collaboration Joint research, documentation and dissemination CDN WQ has the lead

How contact precipitation works (CP) Contact precipitation (CP) PO4 Ca F Ca PO4 Pellets CDN F Bone char 1991 1996 2004 – 2006 2006 to date First scientific publication on CP and its ability to remove fluoride (Christoffersen et al., 1991) Pilot plant in Tanzania. Due to high maintenance effort plant was abandoned (Dahi, 1996) CDN WQ develops pellets Field and laboratory testing

Production of filter materials Crushing Sieving Washing Curing Washing Sprinkling

Laboratory experiments PVC columns with 260 ml filter material; Contact Precipitation (CP), Pellets:Bonechar ratio of 3:1; Pellet size:2-6.3mm; Bone Char(BC) size:1- 4mm Flowrate 10Bv/day Distilled Water spiked with 6mgF/l used at Eawag and Natural ground water with 6.2 mgF/l used in Kenya

Research findings Column experiments show a variation in uptake capacity between 0.5 mg/g – 4.3 mg/g depending on experimental conditions

Household Filter (Defluoridation only)

Household filter (Combined Filter)

Institutional Filter

Community Filter

Remote Area Filter

Results: Community Filter Design modified reduced phosphate concentrations in the outlet Approximately 1000m3 treated until 1.5 mgF/L(WHO guideline) The difference in design on laboratory scale and field brings about the differences in the uptake capacity (20% lower in the field than in the laboratory)

Summary and conclusions The technology is promising and filter life is prolonged by 3-6 times The maintenance cost of such filters is reduced Contact precipitation is complex with adsorption, dissolution and precipitation reactions. Optimization is currently ongoing so as to enhance filter performance

THANK YOU