CDN WQ

Catholic Diocese of Nakuru, Water Quality Section

STAKEHOLDERS WORKSHOP

St Mary's Pastoral Centre , Nakuru 27th May 2010

Topic: Fluoride, Fluorosis and Defluoridation

by Linda Korir

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 supplyEstablished in 1998 to research, develop and implement an appropriate technology for fluoride removalMost 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

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

CaPO4

F

Bone char

FCaPO4

Pellets

Contact precipitation (CP)

CDN

How contact precipitation works (CP)

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

Curing

Washing

Sprinkling

Crushing

Sieving

Washing

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

0

1

2

3

4

5

6

0 100 200 300 400 500 600 700

Treated water in eBV (-)

Flu

ori

de

(m

g/L

)

BC-GW CP-GW

BC-DW CP-DW

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)

Breakthrough community filter

0

2

4

6

0 50 100 150 200 250 300 350

eBV (-)

F o

utl

et (

mg

/L)

0

20

40

60

PO

4 o

utl

et (

mg

/L)

Fluoride

Phosphate

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