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

2. 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

3. Fluorosis
No medical cure
Prevention

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

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

6. 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

7. 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

8. Production of filter materials
Crushing
Sieving
Washing
Curing
Washing
Sprinkling

9. 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

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

11. Household Filter (Defluoridation only)

12. Household filter (Combined Filter)

13. Institutional Filter

14. Community Filter

15. Remote Area Filter

16. 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)

17. 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

18. THANK YOU