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Nicaragua Report 1993 | Water Purification | Drinking Water

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FINAL REPORT NICARAGUA HOUSEHOLD WATER SUPPLY AND TESTING PROJECT by David H. Manz1, Byron Buzunis2 and Carlos Morales3 December 1993 1 Associate Professor, Department of civil Engineering, and Senior Research Associate, Division of International Development of the International Centre of the University of Calgary, Calgary, Alberta, Canada, T2N lN4. T.N.(403) 220-5503. FAX (403) 2827026. Graduate student, Department of civil Engineering, University of Calgary, Calgary, Alberta, Canada, T2N
  FINAL REPORT NICARAGUA HOUSEHOLD WATER SUPPLY AND TESTING PROJECT byDavid H. Manz 1 , Byron Buzunis 2 and Carlos Morales 3  December 1993 1 Associate Professor, Department of civil Engineering, and Senior ResearchAssociate, Division of International Development of the InternationalCentre of the University of Calgary, Calgary, Alberta, Canada, T2N lN4.T.N.(403) 220-5503. FAX (403) 2827026. 2 Graduate student, Department of civil Engineering, University of Calgary,Calgary, Alberta, Canada, T2N lN4. 3 Environmental health consultant, Pan American Health Organization,Nicaragua. 1  1.0 IntroductionWater suitable for drinking is often very difficult to find or produce in the rural areas of  Nicaragua. Though considerable progress has been made to ensure that potable water isavailable to cities and towns, up to 88% of the population outside of major population centresare unable to access safe drinking water. Virtually 100% of farm households have no accessto safe drinking water. It is estimated that 48% of the entire population of Nicaragua cannot be adequately served by any existing or proposed potable water supply programs. Choleraepidemics are common and devastating to the communities in which they occur. (Personalcommunication with PAHO(Nicaragua), Nicaragua Ministry of Health (MINSA) and Nicaragua Ministry of Water and Sanitation (INAA) staff.)2.0 Technical BackgroundA serious problem facing those who wish to assist the rural communities in obtaining suitabledrinking water is the selection of the technology to be used. The technology chosen must notonly perform its intended purpose, it must be affordable, culturally acceptable and very wellunderstood by the people who will be using it. In short, the technology must be appropriateand sustainable. Despite the existence of a vast knowledge base on water supply developmentand treatment, only a few solutions may be recommended for use in rural communities.Uncontaminated water supplies may be obtained from borehole wells and springs. However,to be affordable the costs for construction, operation and maintenance need to be shared by aninformed and organized community .These water supplies may be contaminated, andfrequently are, if they are not operated correctly.In situations where uncontaminated water cannot be found, treatment is the only availablesolution. The water can be boiled but fuel may be expensive or unavailable. Chemicals suchas chlorine and iodine, commonly used for water disinfection, may be considered expensiveand sometimes undesirable (taste, odour etc.). Simple water filters, such as recommended bythe World Health Organization 1987 and common to many peoples of the world, are notintended to and cannot provide the quality of treatment necessary to produce pathogen freewater ..0 Slow sand filtration, (SSP), has been successfully used for water treatment since the mid-nineteenth century, Huisman and Wood 1974. It was developed to economically treat largeamounts of water which would then be available for distribution. Removal rates of total andfaecal bacteria vary between 99 to loo percent, Bellamy et al. 1985a and Bellamy et al.1985b. (It is important to note that the bacteria responsible for cholera, Vibrio Cholerae, isvery similar to E. coli bacteria, (faecal coliform bacteria), with respect to its shape, size andhow it lives and can be expected to be removed at rates very similar to E. coli.) Removalrates of viruses are reported to vary between 99.9 to 100 percent depending on filter design,Hendricks and Bellamy 1991. Removal rates of cysts of Giardia and Cryptosporidium, whichare both resistant to disinfection, are reported to be greater than 99.99 percent, Bellamy et al.1985a and Schuler and Ghosh 1991. Removal of schistosome cercariae, the cause of schistosomiasis, is estimated to be 100 percent, Bernarde and Johnson 1970. Concentration of total or E. coli bacteria measured in terms of number of bacteria per 100 ml. of sample areused as measures of potential contamination of water by pathogenic organisms. Slow sand 2  filters will significantly reduce turbidity, colour, and concentrations of mercury, cadmium,chromium, lead, iron and manganese, Erb et al. 1982 and Seppan 1992. Communitiesthroughout the world with populations ranging from as few as fifty people to those withseveral million people are using SSP technology successfully. SSP technology~ has never  been successful~ adapted for use by individual households such as those found in the ruralareas of Nicaragua.The reasons for the lack of development of SSP for individual household use may only beguessed at. Typically research is directed towards the development of technology whichwould benefit the greatest portions of the population. Intermittent use of SSP, which would be normal for individual households, seriously reduces the performance of larger scalecontinuous flow slow sand filter, (CFSSF), water treatment facilities, Paramasivan et al.1980. CFSSF's are never designed to be intermittently operated.3.0 Project DevelopmentIn the fall of 1991 research into intermittently operated slow sand filters, (IOSSP),was initiated in the Department of Civil Engineering of the University of Calgary, Lee 1991.The results of this research supported new theories regarding the mechanisms responsible for the removal of pathogenic organisms from water by slow sand filtration. Initial positiveresults and the development of an inexpensive portable laboratory also in the Department of Civil Engineering of the University of Calgary, Dean 1992, convinced the Pan AmericanHealth Organization, (P AHO), through the Centro Latinoamericano de Perinato1ogia yDessarollo Humano, (CLAP), to invest US $10,000 from one of its projects known asProyecto de Desarollo de la Salud Perinatal, (DESAPER) into a pilot IOSSF technologyevaluation project in Nicaragua. DESAPER is funded by the Canadian InternationalDevelopment Agency, (CIDA), and is co-administered by the Division of InternationalDevelopment of the University of Calgary and CLAP. DESAPER has two projects in Nicaragua, one in Nandaime and the other in Tipitapa. After discussions with DESAPER, itwas decided to locate the pilot project in Nandaime.Subsequent to the successful initiation of the pilot project, an additional U.S. $8000 was provided to expedite its evaluation and continue research into the IOSSP technology.4.0 Objectives of Pilot ProjectThe objectives of the pilot project were to establish a water quality testing laboratory at thehospital in Nandaime, a small city located approximately 65 km southeast of Managua, andfield test the performance of the IOSSP household water treatment units at selected locationsin the surrounding rural community. The laboratory was needed to support the field research.5.0 Project PlanHospital Rommel Carrasquilla, located in Nandaime was visited March 1 -5, 1993 to meet thehospital director and other interested personnel involved either directly or indirectly with 3  D~APER. An assessment of local laboratory and field-testing requirements and potential sitesfor the location of the household water filters were identified.Both the INAA and MINSA regional laboratories were willing to assist in the project. TheINAA laboratory was selected because it was using the membrane filtration technique similar to that being located at the hospital. (The MINSA laboratory uses the multiple tubefermentation technique.)An assessment was made of materials available to construct the filters. Adequate sand andgravel materials could be located in the Nandaime area and suitable containers, pipes, valvesand other required supplies could be found in local hardware stores or those in Managua.Local concrete building block factories were visited to evaluate their manufacturing skilllevel. This information was needed to design future inexpensive concrete versions of thehousehold water filter.6.0 Project Implementation6.1 LaboratoryA portable incubator and supplies necessary to perform approximately 100 tests to quantifythe concentration of faecal coliform bacteria using the membrane filter method were broughtfrom the University of Calgary to the hospital in Nandaime May 10, 1993. During the firstweek the laboratory was established and six hospital staff were trained in the laboratory useand procedures for taking samples of water. The Chief of the INAA Water Quality ControlLaboratory, Region IV, located in Granada acted as a resource person to the hospital staff during the pilot project period. The laboratory equipment and supplies cost approximatelyU.S. $2800.A copy of the laboratory equipment required and the detailed laboratory instructions and procedures may be found in Annex A.6.2 Household water filter units6.2.1 DesignThe design of the intermittently operated household filter is shown on the following sketch.The filter consists of a cylindrical container approximately one meter in height and 40 cm indiameter (plastic barrel), a 10 cm layer of washed coarse gravel which surrounds a perforateddrain pipe leading out of the filter container to a tap, a 50 cm layer of washed fine sand, adiffusing basin, surface drain and cover. The sand should have similar physical characteristicsto that used in continuously operated slow sand filters; that is, effective size between 0.15 to0.3 mm and uniformity coefficient less than 5 though any local fine sand from a fairly cleansource could probably be used successfully. The tap is located such that a container to receivethe treated water may be located below it. The surface drain is located approximately 5 cmabove top of the sand. The diffusing basin must be large enough to cover at least 80 % of the 4
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