Post on 11-Dec-2015
transcript
KATHERINE WESTPHALMPH CANDIDATE, 2008
The Effectiveness and Sustainability of a Low-cost Water Filter in Removing
Pathogens during Long-term Household Use
EARL WALL, M.S., KELLOGG SCHWAB, PHD., M.S.
Ceramic Water Filter (CWF)
Technology developed in Guatemala in 1981
Potters for Peace promotes CWF
Filters are produced by local organizations
Manufactured in 23 factories throughout 20 countries
Worldwide over 300,000 soldOrganizations promoting
CWF include Save the Children, UNICEF and Oxfam
CWF production
Made from locally available clay, screened combustible material (sawdust or rice husks) and water
Pressed into bucket shape with a hydraulic press
Fired for 8-12 hours in Mani Kiln
Filtration flow rate (1-2.5 Ltr/hr)
Painted with colloidal silver
Sold with plastic receptacle and spigot for $15 (small) and $20 (large)
Background
Research to date - Non-peer reviewed studies have found:
CWF removes between 98-100% bacteria effective in removing protozoa although the virus
removal is minimal
Concerns – Effectiveness of the filter to remove water-borne
pathogens Possible quality control issues within and between
manufacturing facilities
Research objectives
Quantify the effectiveness of the CWF to remove water-borne pathogens in the laboratory and in the field
Evaluate the long-term sustainability of the CWF
Determine if the CWF should be promoted by organizations as a POU water treatment system
Study design
3 Parts:
1.Laboratory – o tested bacteria, virus and
protozoa removal of 24 CWFs from Honduras
2.Field survey - o a cross-sectional survey of
households in Nicaragua that received a CWF
3.Field assessment –o in-situ tests of CWF
effectiveness to remove bacteria
Research findings
Laboratory (15 CWFs with silver) –
Field – 53% (23/43) of filters removed 100% of E. coli78% (34/43) of filters removed > 95% E. coli 9.3% (4/43) of households had more E. coli in filtered
water than pre-filtered water
C W F L aboratory US E PA
S tandardsB acteria 3.22 - 6.06 6.0Virus 0.27 - 1.85 4.0Protozoa 2.47 - 2.97 3.0
L og 10 R educ tion Values
Research findings
Cross-sectional survey (167 households) – 48.5% of households had stopped using filter daily Among households not using the CWF, the primary reasons
were : broken spigot ( 58.0%) broken ceramic filter (40.7%) broken receptacle (30.9%)
Even among households using the CWF, 31.4% had a broken spigot
Only 26.3% of households knew where to purchase CWF spare parts
86% of households reported that the CWF provided enough water for their family to drink
All households surveyed liked the taste of the filtered water The majority of households reported that they liked the CWF
because it cleaned the water and kept their family healthy
Sustainability
Social/Cultural People like the taste of the filtered water and appearance of the
filter Households consider the CWF beneficial enough to pay for it
Economic Provides employment for local potters A one-time cost if unit does not break
Technical Effectiveness –
Significantly reduces bacteria and protozoa in water Does not effectively remove viruses and there is no residual protection
Durability – The ceramic filter, spigot and receptacle are fragile and break easily Spare parts are not readily available
Environmental Uses locally available materials and fuel efficient kilns for firing
filters
Conclusions
Laboratory - CWF improves the quality of water but it does not
consistently remove water-borne pathogens to meet USEPA standards
Field - In general, the CWF improves household water quality Without modifications to the spigot and receptacle,
long-term sustainability will not be achieved
Overall - Necessary to consider the social, economic and
environmental constraints of a country before defining water quality standards
Recommendations
CWF - Adaptations to the spigot and/or receptacle of the CWF Increase availability of CWF replacement parts
Research - Compare effectiveness of filters across production sites Longitudinal study of diarrheal prevalence comparing
households with a CWF to those without
Quality assurance - Establish QA protocols for CWF production Develop a certification process for locally-produced
CWFs