Modeling the sustainability of a ceramic water filter intervention

January 23, 2014 · 0 comments

Modeling the sustainability of a ceramic water filter intervention. Water Res. 2014 Feb 1;49:286-99. doi: 10.1016/j.watres.2013.11.035.

Mellor J, et al.

Ceramic water filters (CWFs) are a point-of-use water treatment technology that has shown promise in preventing early childhood diarrhea (ECD) in resource-limited settings. Despite this promise, some researchers have questioned their ability to reduce ECD incidences over the long term since most effectiveness trials conducted to date are less than one year in duration limiting their ability to assess long-term sustainability factors. Most trials also suffer from lack of blinding making them potentially biased.

This study uses an agent-based model (ABM) to explore factors related to the long-term sustainability of CWFs in preventing ECD and was based on a three year longitudinal field study. Factors such as filter user compliance, microbial removal effectiveness, filter cleaning and compliance declines were explored. Modeled results indicate that broadly defined human behaviors like compliance and declining microbial effectiveness due to improper maintenance are primary drivers of the outcome metrics of household drinking water quality and ECD rates.

The model predicts that a ceramic filter intervention can reduce ECD incidence amongst under two year old children by 41.3%. However, after three years, the average filter is almost entirely ineffective at reducing ECD incidence due to declining filter microbial removal effectiveness resulting from improper maintenance. The model predicts very low ECD rates are possible if compliance rates are 80-90%, filter log reduction efficiency is 3 or greater and there are minimal long-term compliance declines. Cleaning filters at least once every 4 months makes it more likely to achieve very low ECD rates as does the availability of replacement filters for purchase. These results help to understand the heterogeneity seen in previous intervention-control trials and reemphasize the need for researchers to accurately measure confounding variables and ensure that field trials are at least 2-3 years in duration. In summary, the CWF can be a highly effective tool in the fight against ECD, but every effort should be made by implementing agencies to ensure consistent use and maintenance.

Intermittent versus continuous operation of biosand filters

January 23, 2014 · 1 comment

Intermittent versus continuous operation of biosand filters. Water Res. 2014 Feb 1;49:1-10. doi: 10.1016/j.watres.2013.11.011.

Authors: Young-Rojanschi, et al.

The biosand filter is a household-scale point-of-use water filtration system based on slow sand filtration, but modified for intermittent operation. Studies on slow sand filters show that intermittent operation reduces filter effectiveness. However, continuous versus intermittent operation of biosand filters has never been compared. Eight 10-cm diameter columns were constructed to represent field biosand filters.

Five were operated intermittently with a 24-h residence period, while the remaining three were operated continuously. Continuous operation of the filters resulted in significantly better reduction of Escherichia coli (3.71 log10 versus 1.67 log10), bacteriophage MS2 (2.25 log10 versus 0.85 log10), and turbidity (96% versus 87%). Dissolved oxygen levels at 5 and 10 cm of media depth in intermittent filters reached an average of 0 mg/L by 24 h of residence time on day 60 of the experiment. A simple numerical model was developed to describe E. coli removal during ripening from days 0-58 for continuously operated versus intermittent filters.

This research confirms that although biosand filters were developed for intermittent operation, the filters perform significantly better when operated continuously. However, both operational modes resulted in a significant reduction of microbial indicators.

Public Health and Social Benefits of at-house Water Supplies

January 15, 2014 · 0 comments

Public Health and Social Benefits of at-house Water Supplies, 2013. DfID.

Authors – Barbara Evans, et al.

Abstract – We carried out a mix of secondary and primary research to examine the hypothesis that access to an at-house water supply will deliver significantly greater health, social and economic benefits than those derived from a shared public water supply. Our research was based on a mix of literature review and field-base case studies. Fieldwork was carried out in three countries; Ghana, South Africa and Vietnam and used a mix of data collection methods, specifically a three-part household questionnaire, which included anthropometric measures and the measurement of water collection journeys, natural group discussions, and contextual checklists.

The relationship between water source, water usage and health and social outcomes is complex and mitigated by a range of contextual and intermediate factors. A fundamental challenge in comparing outcomes of at-house supplies with shared supplies lies with wealth as a confounder. In our analysis we were able to account for wealth effects to some extent because of the detailed household information we were able to collect. Nonetheless these challenges are significant.

In our research we focused on a two-step approach, looking at the relationship between distance to source and volumes of water consumed followed by an analysis of volumes of water carried/consumed and the health and social outcomes including hygiene practices. In this way we reduced the effect of wealth and other broader social contextual factors in the analysis. This was supplemented by the analysis of the relationship between source-type and water quality.

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Enteric Pathogens in Stored Drinking Water and on Caregiver’s Hands in Tanzanian Households

January 15, 2014 · 0 comments

Enteric Pathogens in Stored Drinking Water and on Caregiver’s Hands in Tanzanian Households with and without Reported Cases of Child Diarrhea. PLoS One, Jan 2014.

Authors – Mia Catharine Mattioli, et al.

Abstract – Background: Diarrhea is one of the leading causes of mortality in young children. Diarrheal pathogens are transmitted via the fecal-oral route, and for children the majority of this transmission is thought to occur within the home. However, very few studies have documented enteric pathogens within households of low-income countries.

Methods and Findings: The presence of molecular markers for three enteric viruses (enterovirus, adenovirus, and rotavirus), seven Escherichia coli virulence genes (ECVG), and human-specific Bacteroidales was assessed in hand rinses and household stored drinking water in Bagamoyo, Tanzania. Using a matched case-control study design, we examined the relationship between contamination of hands and water with these markers and child diarrhea. We found that the presence of ECVG in household stored water was associated with a significant decrease in the odds of a child within the home having diarrhea (OR = 0.51; 95% confidence interval 0.27–0.93). We also evaluated water management and hygiene behaviors. Recent hand contact with water or food was positively associated with detection of enteric pathogen markers on hands, as was relatively lower volumes of water reportedly used for daily hand washing. Enteropathogen markers in stored drinking water were more likely found among households in which the markers were also detected on hands, as well as in households with unimproved water supply and sanitation infrastructure.

Conclusions: The prevalence of enteric pathogen genes and the human-specific Bacteroidales fecal marker in stored water and on hands suggests extensive environmental contamination within homes both with and without reported child diarrhea. Better stored water quality among households with diarrhea indicates caregivers with sick children may be more likely to ensure safe drinking water in the home. Interventions to increase the quantity of water available for hand washing, and to improve food hygiene, may reduce exposure to enteric pathogens in the domestic environment.

School-based intervention: evaluating the role of water, latrines and hygiene education on trachoma

January 6, 2014 · 1 comment

School-based intervention: evaluating the role of water, latrines and hygiene education on trachoma and intestinal parasitic infections in Ethiopia. Journal of Water, Sanitation and Hygiene for Development, 2013 (In press)

Bizu Gelaye, Abera Kumie, Nigusu Aboset, Yemane Berhane and Michelle A. Williams

Department of Epidemiology, University of Washington School of Public Health, Seattle, WA, USA E-mail: bgelaye@hsph.harvard.edu

Department of Epidemiology, Harvard School of Public Health, 677 Huntington Ave, K 501, Boston, MA, 02115 USA
Faculty of Medicine, Addis Ababa University, Addis Ababa, Ethiopia
Addis Continental Institute of Public Health, Addis Ababa, Ethiopia
Family Health International, Addis Ababa, Ethiopia

Abstract - We sought to evaluate the impact of a hygiene and sanitation intervention program among school-children to control active trachoma and intestinal parasitic infections. This longitudinal epidemiologic study was conducted among 630 students in rural Ethiopia. Baseline and follow-up surveys were conducted to evaluate the impact of a three pronged intervention program: (i) construction of ventilated improved pit latrines; (ii) provision of clean drinking water; and (iii) hygiene education. Socio-demographic information was collected using a structured questionnaire. Presence of trachoma and intestinal parasitic infections were evaluated using standard procedures.

At baseline, 15% of students had active trachoma, while 6.7% of them were found to have active trachoma post-intervention (p < 0.001). Similar improvements were noted for parasitic infections. At baseline, 7% of students were reported to have helminthic infections and 30.2% protozoa infections. However, only 4% of students had any helminthic infection and 13.4% (p < 0.001) of them were found to have any protozoa infection during follow-up surveys. Improvements were also noted in students’ knowledge and attitudes towards hygiene and sanitation.

In summary, the results of our study demonstrated that provision of a comprehensive and targeted sanitation intervention program was successful in reducing the burden of trachoma and intestinal parasitic infection among schoolchildren.

Mechanisms of post-supply contamination of drinking water

January 6, 2014 · 0 comments

Mechanisms of post-supply contamination of drinking water in Bagamoyo, Tanzania. Journal of Water and Health Vol 11 No 3 pp 543–554, 2013.

Angela R. Harris, Jennifer Davis and Alexandria B. Boehm

Environmental and Water Studies, Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA E-mail: angelaharris@stanford.edu
Woods Institute for the Environment, Stanford University, Stanford, CA 94305, USA

Abstract – Access to household water connections remains low in sub-Saharan Africa, representing a public health concern. Previous studies have shown water stored in the home to be more contaminated than water at the source; however, the mechanisms of post-supply contamination remain unclear. Using water quality measurements and structured observations of households in Bagamoyo, Tanzania, this study elucidates the causal mechanisms of the microbial contamination of drinking water after collection from a communal water source.

The study identifies statistically significant loadings of fecal indicator bacteria (FIB) occurring immediately after filling the storage container at the source and after extraction of the water from the container in the home. Statistically significant loadings of FIB also occur with various water extraction methods, including decanting from the container and use of a cup or ladle. Additionally, pathogenic genes of Escherichia coli were detected in stored drinking water but not in the source from which it was collected, highlighting the potential health risks of post-supply contamination.

The results of the study confirm that storage containers and extraction utensils introduce microbial contamination into stored drinking water, and suggest that further research is needed to identify methods of water extraction that prevent microbial contamination of drinking water.

The Challenge of Promoting Interventions to Prevent Disease in Impoverished Populations

December 27, 2013 · 0 comments

The Challenge of Promoting Interventions to Prevent Disease in Impoverished Populations in Rural Western Kenya. Am Jnl Pub Health, Dec 2013.

Katharine Schilling, et al.

Poverty is a critical social determinant of health. A particular approach toward mitigating inequitable access to health services in Kenya has been through a community-based distribution program implemented by the Safe Water and AIDS Project (SWAP) that has achieved modest uptake of public health interventions. To explore reasons for modest uptake, we asked program participants about child health problems, daily tasks, household expenditures, and services needed by their communities.

Respondents identified child health problems consistent with health data and reported daily tasks, expenses, and needed services that were more related to basic needs of life other than health. These findings highlight the challenges of implementing potentially self-sustaining preventive interventions at scale in poor populations in the developing world.

Introducing Efficient Low Cost Smoked Pots for Water Purification

December 27, 2013 · 0 comments

Introducing Efficient Low Cost Smoked Pots for Water Purification for Developing Countries. Hydrol Current Res 2013, 4:2.

D Chung, et al.

Ceramic materials are easy to make using most African soils. They have been used for a long time mainly for cooking and water storage. However, in other low income economies these clay ceramic filters have been shown to have the potential of being improved by being embedded with carbonaceous materials for water purification. In this research we have produced efficient physiological and biological gravity operated smoked pots for water purification. We used well calculated volume ratios of black clay, red and sand soils (B:R:S) and soil balls; All these were baked at different smoke infusing kiln temperatures for efficient water purification.

We analyzed water purification efficiencies of the pot ceramics and the trickling rates at different conditions. We isolated the best B:R:S to be the 40:40:20. We found significant reductions in turbidity (99.95%), salinity (21.42%), microbial populations, total dissolved solutes (TDS) (17.19%), pH (1.39%) and electrical conductivity (EC) (16.92%). These ceramics can be crucial for common or nomadic communities in sub-Saharan rural areas and in times of disaster to guarantee a cheap continued supply of clean potable water for better health amongst the low income earning societies.

Water Safety and Inequality in Access to Drinking-water between Rich and Poor Households

December 27, 2013 · 0 comments

Water Safety and Inequality in Access to Drinking-water between Rich and Poor Households. Env Sci Tech, Dec 2013.

H Yang, et al.

While water and sanitation are now recognized as a human right by the United Nations, monitoring inequality in safe water access poses challenges. This study uses survey data to calculate household socio-economic-status (SES) indices in seven countries where national drinking-water quality surveys are available. These are used to assess inequalities in access as indicated by type of improved water source, use of safe water, and a combination of these.

In Bangladesh, arsenic exposure through drinking-water is not significantly related to SES (p = 0.06) among households using tubewells, whereas in Peru, chlorine residual in piped systems varies significantly with SES (p < 0.0001). In Ethiopia, Nicaragua, and Nigeria, many poor households access nonpiped improved sources, which may provide unsafe water, resulting in greater inequality of access to “safe” water compared to “improved” water sources. Concentration indices increased from 0.08 to 0.15, 0.10 to 0.14, and 0.24 to 0.26, respectively, in these countries. There was minimal difference in Jordan and Tajikistan.

Although the results are likely to be underestimates as they exclude individual-level inequalities, they show that use of a binary “improved”/”unimproved” categorization masks substantial inequalities. Future international monitoring programmes should take account of inequality in access and safety.

Increasing acceptance of chlorination for household water treatment: observations from Bangladesh

December 27, 2013 · 1 comment

Increasing acceptance of chlorination for household water treatment: observations from Bangladesh. Waterlines, Apr 2013.

S. Flanagan, et al.

Point-of-use water treatment, especially chlorination, is an effective intervention to reduce diarrhoea, a leading cause of death for children under five. Yet success in chlorination uptake has been limited. One obstacle is objection to treated water’s taste/odour. Protective chlorine residuals that are not offensive to users require accurate dosing – a challenge in practice. Further, taste sensitivity may be different for populations never exposed to chlorinated water.

Here, household chlorination trials in Bangladesh similarly revealed dissatisfaction with treated water due to taste and odour, although attempts to quantifychlorine sensitivity disputed the dissatisfaction at lower residuals. A granular activated carbon (GAC) filter fitted to the spigot of a covered tank removed the remaining chlorine residual prior to drinking and increased user satisfaction. Such a filter removes taste as a barrier and allows over-dosing contaminated water to ensure disinfection, with implications for areas with high source water variability and for emergency situations.

 

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