Transcript Document

Health benefits of point-of-use
water treatment systems
Bettina Genthe
2 October 2012
Links of poor water and sanitation
services to poverty
• In addition to direct health effects, the United Nations
Millennium Declaration confirmed the central role of water and
sanitation in sustainable development and the major contribution
expanded access to safe drinking water and adequate sanitation
can make to poverty alleviation (WHO, 2004).
• The poor bear the brunt of inadequate water services more than
those with money in financial terms too. They pay high prices
where water is sold, yet often have unreliable supplies, and so
do not get value for money as do the rich. The poor are also less
able to adopt strategies to lower risk where water supply is
unreliable, such as investing in storage or treatment technologies
• The World Health Organization (WHO) concluded that there
was now “conclusive evidence that simple, acceptable,
low-cost interventions at the household and community
level are capable of dramatically improving the microbial
quality of household stored water and reducing the
attendant risks of diarrheal disease and death” (WHO,
2007).
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Economic benefits of improvements in
drinking water quality
• According to the WHO assessment (2004), achieving the water and
•
•
sanitation MDG target would bring economic benefits, ranging from
US$3 to US$34 per US$ invested, depending on the region.
Additional improvement of drinking-water quality, such as point-ofuse disinfection, in addition to access to improved water and
sanitation would lead to a benefit ranging from US$5 to US$60 per
US$1 invested.
In addition, health and the socio-economic benefits accrue when
improving access to safe water supply and sanitation.
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Cost of diarrhoea in Olifants catchment
Description
Number of people
< RDP (Low service level)
Direct health costs
>RDP (High service level)
Direct health costs
(R3 769)
2 223 427
(R 3 349)
1 164 244
2 220 151
210 636
Estimated diarrhoea
incidences
# of cases treated
Average Treatment costs
Total Direct Health costs
(8%)
177 612
(5%)
10 532
R 3 769
R 3 349
R 669 419 899
R 35 270 978
Total number of people 3 387 671
Total direct cost R704 690 877 (R208 per person)
The Economic Burden of Diarrhoeal Disease in the Olifants
WMA, SA. Steyn M, Maherry A and Genthe, B 2011
Economic burden of diarrhoea
Pollution Prevention is
cheaper than
Treatment
Image
Providing people with
>RDP level water is
cheaper than the cost
of Diarrhoea
© CSIR 2010 Slide #
Cause of death
• South Africa is one of a few countries globally where the
under five mortality rate has increased rather than
decreased (60 per 1,000 live births in 1990 to 66 per 1,000
live births in 2003) (UNICEF, 2005). Diarrhoeal disease is
the third largest cause of death among children under the
age of five in South Africa.
• Fewtrell et al., (2007) quantified the health impact in
countries with incomplete water and sanitation coverage.
They estimated that services related to water, sanitation and
hygiene (WSH) are responsible for between 70 and 90% of
diarrhoea in areas where coverage is below 98%.
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South Africa
• Approx 12% of population have no improved water supply nor
sanitation
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Types of point of use systems
• Solar disinfection (SODIS)
• Filters
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• Chemical disinfection
• Biosand filter
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Combination approach Amadrum
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Effectiveness of the various Point-of-Use systems
Intervention
Result Log reduction
SODIS
Viruses 2- 3 log
Bacteria 4 log
Parasites 4 log
Viruses 3-4
Bacteria 3-4 log
Parasites 2-3 log
Viruses 5 log
Bacteria 8 log
Parasites 4 log
Chlorination
Floc filter + disinfect (PuR)
&WaterMaker – produced in
SA
Ceramic filter candles
Ceramic Pot filters
Sand Filtration (BioSand)
Virus 0.5 log
Bacteria 4 log
Parasites 3 log
Virus 0.5 log
Bacteria 4 - 7 log
Parasites 2 - 5 log
Virus 0.5 log
Bacteria 2 log
Parasites 1 log
Diarrhoeal disease reduction by technology
source Sobsey et al 2008
Technology
Diarrhoeal reduction
SODIS
31% (26%-37%)
Disinfection and safe storage
37% (25%- 48%)
Coagulation /chlorination
31% (18%- 42%)
Ceramic candle filtration
63% (51%-72%)
Ceramic pot filters
46% (29%-59%)
Biosand filter
47% (21%-64%)
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Advantages and disadvantages of
point-of-use water quality interventions
Advantages of combined
treatment systems
Highly effective against all waterborne
pathogens.
Can be applied to high turbidity waters,
and waters with high pH and low
temperatures
Provides a residual level of free chlorine
Disadvantages
Expensive (initial cost of US$510/household for vessel + annual
operating cost of US$3555/household/year).
Filter cloth may not be appropriate
Low production
capacity10L/day/household
No need for highly skilled labour, so only Cultural resistance - chlorine taste of
the water.
moderate level of training required,
Visually observable improvement in
Dependence on supply of materials
water quality (turbidity reduction).
Advantages of Ceramic
Candle Filters
Disadvantages-
Highly effective against most
waterborne pathogens
Operate consistently regardless of
turbidity
No addition of chemicals to the water.
Therefore absence of tastes and
odours
+ Easy to use and maintain,
+ Visual observation of the water
quality improvement (turbidity
reduction).
+ High levels of user acceptability.
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- Low viral removal.
- No residual protection,
-Relatively high cost if produced in
developed countries:
- Low production capacity (20L/day, or
0.5-2L/h, depending on the filter and
the turbidity of water).
- Breakage is possible.
- Systems require regular cleaning to
restore normal flow rate (each week
or two weeks).
- Candles must be changed (life
expectancy of 6 months to 2 years).
Advantages of Ceramic Filter
Pots
Disadvantages
Reduction of diarrhoea 46% in filter users vs
non users (Brown 2006)
Rate of discontinuation of filter use
Low virus removal
Improved water quality for bacteria and
protozoan parasite removal
Performance not consistent
Low filtration rate insufficient drinking water
for an average household.
Sustainable and transferable technology
Risk of recontamination of water
Easy to use and maintain
Advantages of SODIS
Proven reduction of viruses, bacteria, and
protozoa in water;
Disadvantages
need for pretreatment of waters of higher turbidity
limited volume of water that can be treated
Proven reduction of diarrheal disease incidence
Acceptability to users
No cost to the user after obtaining the plastic
bottles;
Minimal change in taste of the water; and,
recontamination is unlikely.
length of time required to treat water; or not
reaching T for disinfection if cloudy / cold
community motivation and training for users on
how to correctly and consistently use SODIS
South African-Zim-Kenyan study
ceramic filters
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Southern African study ceramic candle filters
• filtration reduced the risk of all types of diarrhoea by approx 80%.
• The reduction was most marked for bloody diarrhoea.
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Testing of water at community level
At community level, after initial characterising of the water, chemical
tests are not necessary for community testing as the chemical
quality does not vary significantly over time.
• Microbiological testing is important to ensure that contamination
of the drinking water has not occurred.
• This can be checked easily making use of a field microbiological
test called the H2S strip test.
• Black H2S producing bacteria present
• No H2S producing bacteria
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Sustainability criteria
(source Sobsey 2008)
Technology
Quantity
Quality
Ease
of use
Cost
Supply
chain
Overall
score
Disinfection
3
1
3
3
1
11
Coagulation/chlorination
2
3
1
1
1
8
SODIS
1
1
1
3
2
9
Ceramic filters
2
3
2
3
2
12
Biosand filters
3
3
2
2
3
13
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Conclusion
•
•
The World Health Organization (WHO)
concluded that there was
“conclusive evidence that simple, acceptable,
low-cost interventions at the household and
community level are capable of dramatically
improving the microbial quality of household
stored water and reducing the risks of
diarrheal disease and death” (WHO, 2007).
© CSIR 2007
www.csir.co.za