pilot field comparison of traditional alum flocculation ...web.mit.edu/watsan/kenyainfo/2. research...
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Pilot field comparison of traditional Pilot field comparison of traditional alum flocculation, chlorination, and alum flocculation, chlorination, and combined flocculationcombined flocculation--chlorination chlorination
pointpoint--ofof--use water treatment on use water treatment on drinking water quality in Western drinking water quality in Western
KenyaKenya•• John A. CrumpJohn A. Crump11, George O. Okoth, George O. Okoth22, Laurence Slutsker, Laurence Slutsker22, Bruce H. Keswick, Bruce H. Keswick33, Stephen P. Luby, Stephen P. Luby11
•• FoodborneFoodborne andand DiarrhealDiarrheal Diseases Branch, Division of Bacterial andDiseases Branch, Division of Bacterial and MycoticMycotic Diseases, National Center for Infectious Diseases, Centers for Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USADisease Control and Prevention, Atlanta, Georgia 30333, USA11
•• Kenya Medical Research Institute/United States Centers for DiseaKenya Medical Research Institute/United States Centers for Disease Control and Preventionse Control and Prevention KisianKisian Field Station, PO Box 1578,Field Station, PO Box 1578, KisumuKisumu, Kenya, Kenya22
•• Procter & Gamble Health Sciences Institute, 8700 Mason MontgomerProcter & Gamble Health Sciences Institute, 8700 Mason Montgomery Road, Mason, Ohio 45040, y Road, Mason, Ohio 45040, USAUSA33
•• John A. Crump, MB, ChB, DTM&HJohn A. Crump, MB, ChB, DTM&H•• Foodborne and Diarrheal Diseases BranchFoodborne and Diarrheal Diseases Branch•• Division of Bacterial and Mycotic DiseasesDivision of Bacterial and Mycotic Diseases•• National Center for Infectious DiseasesNational Center for Infectious Diseases•• Centers for Disease Control and PreventionCenters for Disease Control and Prevention•• Atlanta, GA 30333Atlanta, GA 30333•• United States of AmericaUnited States of America•• Tel +1Tel +1--404404--639639--22062206•• Fax +1Fax +1--404404--639639--22052205•• EE--mail [email protected] [email protected]
Woman collects drinking water from a turbid pond Woman collects drinking water from a turbid pond AsemboAsembo, Western Kenya, Western Kenya
BackgroundBackground•• 1.11.1 billion persons lack access to improved waterbillion persons lack access to improved water
•• DiarrhealDiarrheal disease kills >2 million persons disease kills >2 million persons annuallyannually
•• ‘‘PointPoint--ofof--use’ approaches to improving drinking use’ approaches to improving drinking waterwater
-- Require little infrastructureRequire little infrastructure
-- Are suited to rural settingsAre suited to rural settings
-- Empower individuals to make water safe for Empower individuals to make water safe for theirtheir familiesfamilies
•• ‘‘PointPoint--ofof--use’ disinfectants (e.g., sodium use’ disinfectants (e.g., sodium hypochloritehypochlorite) are likely to perform poorly for ) are likely to perform poorly for highlyhighly turbid source turbid source waterwater
AimAim
•• ToTo compare the effect on water quality compare the effect on water quality indicators of traditional alum flocculation, indicators of traditional alum flocculation, chlorination, and combined flocculationchlorination, and combined flocculation--chlorination (chlorination (PPuurr A and A and PPuurr B) pointB) point--ofof--use use water treatment on drinking water quality in water treatment on drinking water quality in Western KenyaWestern Kenya over a range of source water over a range of source water turbiditiesturbidities
Methods and MaterialsMethods and Materials•• 30 water sources30 water sources
•• Six treatmentsSix treatments-- Combined flocculationCombined flocculation--chlorination product yielding ~3.5 chlorination product yielding ~3.5
mg/L free chlorine (mg/L free chlorine (PPuurr A)A)-- Combined flocculationCombined flocculation--chlorination product yielding ~2.0 chlorination product yielding ~2.0
mg/L free chlorine (mg/L free chlorine (PPuurr B)B)-- Locally produced water disinfectant yielding ~5.0 mg/L Locally produced water disinfectant yielding ~5.0 mg/L
free chlorine (free chlorine (KlorinKlorin))-- Locally available alum Locally available alum flocculant flocculant ~100 g for 60 seconds~100 g for 60 seconds-- Alum + Alum + KlorinKlorin-- Untreated controlUntreated control
10 high turbidity (>100 NTU)
10 medium turbidity (10-100 NTU)
10 low turbidity (<10 NTU)
•• TurbidityTurbidity measured by measured by HachHach 2100P Portable2100P PortableTurbidimeter Turbidimeter ((HachHach Company, Loveland, CO) Company, Loveland, CO)
•• Free and total chlorine concentration measured Free and total chlorine concentration measured byby HachHach Portable DR/890 Colorimeter (Portable DR/890 Colorimeter (HachHachCompany, Loveland, CO) Company, Loveland, CO)
•• pH measured by pH measured by IQ 150 Handheld pH Meter (IQ IQ 150 Handheld pH Meter (IQ Scientific Instruments Inc, San Diego, CA)Scientific Instruments Inc, San Diego, CA)
•• E. E. colicoli concentration measured by concentration measured by Colilert Colilert QuantitrayQuantitray 2000 system (IDEXX Laboratories 2000 system (IDEXX Laboratories Incorporated, Westbrook, ME) Incorporated, Westbrook, ME)
OutcomesOutcomes
Point-of-use water treatments evaluated
Combined Combined flocculationflocculation--
chlorination productchlorination product
Sodium Sodium hypochlorite 1%hypochlorite 1%
Alum ‘Alum ‘dawadawa’’
Turbid water after treatment with Pur
ResultsResultsBefore treatment, turbidity and Before treatment, turbidity and Escherichia Escherichia colicoli concentrations were highest in pond concentrations were highest in pond water, followed by stream, river, lake, spring, water, followed by stream, river, lake, spring, and borehole waterand borehole water
Turbidity by untreated source water Turbidity by untreated source water typetype, , Asembo Asembo and Gem, 2002and Gem, 2002
1
10
100
1,000
Pond Stream River Lake Spring Borehole
Mea
n N
TU
E. E. colicoli concentration by untreated source concentration by untreated source waterwater type, type, Asembo Asembo and Gem 2002and Gem 2002
1
10
100
1,000
10,000
Pond Stream River Lake Spring Borehole
Mea
n C
FU
/100
mL*
*WHO guideline <1 E. coli CFU/100 mL
Turbidity by untreated source water Turbidity by untreated source water type, type, Asembo Asembo and Gem, 2002and Gem, 2002
1
10
100
1,000
Pond Stream River Lake Spring Borehole
Mea
n N
TU
Visual impact of water treatments on highly turbid source water
Untreated Untreated controlcontrol
KlorinKlorin PPuurr BB PPuurr AA AlumAlum Alum + Alum + KlorinKlorin
Effect of water treatments on turbidity Effect of water treatments on turbidity byby turbidity, turbidity, Asembo Asembo and Gem, 2002and Gem, 2002
1
10
100
1,000
Pur A* Pur B* Klorin Alum Alum +Klorin
Untreatedcontrol
Mea
n N
TU
Low turbidity (n=10)Low turbidity (n=10)
Medium turbidity (n=10)Medium turbidity (n=10)
High turbidity (n=10)High turbidity (n=10)
*Includes two water sources where one sachet of Pur failed to form floc
AlthoughAlthough KlorinKlorin delivers a higher chlorine dose delivers a higher chlorine dose compared to compared to PPuurr A, free chlorine levels measured A, free chlorine levels measured 30 minutes after water treatment were higher for 30 minutes after water treatment were higher for
PPuurr A compared to A compared to Klorin Klorin alonealone
Effect of water treatments on free Effect of water treatments on free chlorinechlorine, , AsemboAsembo and Gem, 2002and Gem, 2002
0.0
0.5
1.0
1.5
Pur A Pur B Klorin Alum Alum +Klorin
Untreatedcontrol
Med
ian
fre
e C
l-m
g/L
*
*Measured 30 minutes after treatment
Effect of water treatments on pHEffect of water treatments on pHAsemboAsembo and Gem, 2002and Gem, 2002
0
2
4
6
8
Pur A Pur B Klorin Alum Alum +Klorin
Untreatedcontrol
Mea
n p
H
pH 7.0
AlumAlum--based treatments lower pH substantiallybased treatments lower pH substantially
Effect water treatments on Effect water treatments on E. E. colicoliconcentration, concentration, Asembo Asembo and Gem, 2002and Gem, 2002
1
10
100
1,000
10,000
Pur A Pur B Klorin Alum Alum +Klorin
Untreatedcontrol
Mea
n C
FU
/100
mL
*
*WHO guideline <1 E. coli CFU/100 mL
Proportion waters with <1 Proportion waters with <1 E. E. colicoli/100 /100 mLmLafterafter treatment, treatment, Asembo Asembo and Gem, 2002and Gem, 2002
0
20
40
60
80
100
Pur A Pur B Klorin Alum Alum +Klorin
Untreatedcontrol
% w
ith <
1 E
. co
li/10
0 m
L
Low turbidity (n=10)Low turbidity (n=10)
Medium turbidity (n=10)Medium turbidity (n=10)
High turbidity (n=10)High turbidity (n=10)
OnlyOnly treatments that combined flocculation and treatments that combined flocculation and chlorination performed well in highchlorination performed well in high--turbidity turbidity waterswatersTreatmentsTreatments that included disinfectant performed well in that included disinfectant performed well in lowlow-- and mediumand medium--turbidity turbidity waterswaters
ConclusionsConclusions•• PPuurr AA
-- Mitigates turbidityMitigates turbidity-- Achieves <1 Achieves <1 E. E.
colicoli/100 mL in even /100 mL in even highhigh--turbidity waterturbidity water
-- Maintains neutral pHMaintains neutral pH
•• PPuur Br B-- Mitigates turbidityMitigates turbidity-- Achieves <1 Achieves <1 E. E.
colicoli/100 /100 mLmL in lowin low--and mediumand medium--turbidity turbidity waterwater
-- Maintains neutral pHMaintains neutral pH
•• Alum aloneAlum alone-- Mitigates turbidityMitigates turbidity-- Lowers Lowers E.E. colicoli concentration, concentration,
but not to <1/100but not to <1/100 mL mL -- Lowers pHLowers pH
•• KlorinKlorin alonealone-- No impact on turbidityNo impact on turbidity-- Achieves <1 Achieves <1 E.E. colicoli/100/100 mLmL in in
lowlow-- and mediumand medium--turbidity turbidity waterwater
-- Does not render highDoes not render high--turbidity turbidity water potablewater potable
•• Alum +Alum + KlorinKlorin-- Mitigates turbidityMitigates turbidity-- Achieves <1 Achieves <1 E.E. colicoli/100/100 mLmL in in
highhigh--turbidity waterturbidity water-- Lowers pHLowers pH
Ongoing health outcome studyOngoing health outcome study•• Launched in Launched in Asembo Asembo and Gem, Western Kenya, 2003and Gem, Western Kenya, 2003
•• 600600 homes (>6,500 persons) randomly assigned to homes (>6,500 persons) randomly assigned to useuse-- PPuurr A , orA , or
-- KlorinKlorin, or, or
-- Traditional practices Traditional practices
•• 2020 week durationweek duration-- MainMain outcomesoutcomes
-- Diarrhea prevalence (especially of children <2 years)Diarrhea prevalence (especially of children <2 years)
-- Intervention acceptabilityIntervention acceptability
-- Water Water qualityquality