Biosand Water Filters Research Articles

Potential of ceramic and biosand water filters as low-cost point-of-use water treatment options for household use in Nigeria

Abstract Many households in Nigeria lack access to safe drinking water. Sixty-three percent (63%) of the nation's population live in rural areas where only 3% of households have access to safely managed drinking water. This suggests an urgent need for intervention to offer sustainable solutions to drinking water needs at household levels. An operational research was commissioned by the United Nations Children's Fund (UNICEF) Nigeria to generate evidence to inform and guide Water, Sanitation and Hygiene (WASH) programming on household water quality. This involved an assessment of local manufacturing of household water filters; factors influencing social acceptability and market opportunities for clay and biosand water filters in Nigeria. Implementation of the research recommendations by the filter factories resulted in improved bacterial removal efficiency (>97%) in filters. Factors such as filter design and efficiency were shown to influence acceptability of filters, which influenced the price at which users were willing to pay for the filters in the study areas. The market research indicated low popularity of the filters due to lack of promotion and marketing of the water filters. The research outcomes show great potential for sustainability and marketability of clay and biosand water filters for household water treatment in Nigeria.

Modeling Improved Performance of Reduced-Height Biosand Water Filter Designs

Point-of-use biosand water filters are widely distributed in undeveloped or developing regions due to their water treatment success and low-cost design, but two gaps remain in the basic technology: (1) the filter body is oversized relative to its contaminant removal performance, and (2) the heavy design largely excludes difficult to reach locations in need of clean water solutions. Here, we model design modifications to the v.10 Centre for Affordable Water and Sanitation Technology biosand filter using a reduced filter height, increased biolayer area, and conserved reservoir volume. We compare the hydraulic characteristics (dynamic velocity and head pressure) and percent contaminant removal of bacteria Escherichia coli and virus MS2 of the modified designs to the traditional control design using a finite element approximation of Darcy’s law with discrete time steps and a slow-sand filtration model. We demonstrate that a reduced-height design has a greater impact on contaminant removal compared to the traditional design (largely due to the increased residence time from the decreased flow rate inside the filter). For example, our 70% reduced-height filter design removed 99.5% and 73.93% of E. coli and MS2, respectively, where the traditional filter design removed 62.81% and 27.6%, respectively. Reduced-height designs should be pursued as a viable solution to improve filter performance while allowing for alternative construction techniques with greater end-user accessibility compared to the traditional design.

Water treatment in rural Guatemala: factors associated with the use of biosand water filters

Abstract Point-of-use water filters are a means to provide clean water vital to the health of people in developing countries. The factors that influence the adoption of this technology include hygiene knowledge, health beliefs related to the use of new technology, and technical issues with using the filter (e.g., water taste and breakage). This study examines how people in Mayan communities in rural Guatemala perceived biosand filters they had received and what factors related to their filter use. Based on the survey and interviewer observations, approximately 53% were regular filter users, 28% were irregular filter users, and 19.4% were non-filter users. The observational data revealed that actual filter use is lower than self-reported use, reflecting complexities in the adoption of technology. One such complexity can be seen in the connection between health beliefs and behavior. The belief that believing drinking filtered water is salubrious does not necessarily coincide with filter use, but education and hygienic practices correlated with regular filter use. Furthermore, regular users typically depend on family members for a daily reminder to use the filter, suggesting that education should foster peer support as well as imparting knowledge.

Participant responses to a water treatment intervention in rural Guatemala

Each year, 1.1 billion people suffer from disease, dehydration, and malnutrition fueled by waterborne pathogens. Although point-of-use water filters are a viable solution, effectiveness requires consistent use. As collaborators in international development projects, social workers are poised to address service barriers through their focus on multilevel practice and a relentless emphasis on culturally competent practice. This article describes an illustrative case of a water remediation project in rural Guatemala where social work researchers collaborated with engineers to understand how users appraised the project. We present a content analysis of interviews conducted in 20 households in the Boca Costa and Highland regions of rural Guatemala that received bio-sand water filters, which revealed a diverse group of filter users, with varying motivations and constancy patterns. Our study demonstrates how talking to people is essential to understanding their use of technology and how other objective measures—such as the wetness of the sand—can be helpful in interpreting results. It also shows that within the developing context, people vary in their need for additional supports as they adopt new health-promoting activities.

Review of biosand water filters

Diarrhoeal diseases are a global public health burden, killing 1.8 million people annually. Diarrhoea disproportionately affects children and those in poverty. Most diarrhoeal cases can be prevented through safe drinking water and basic hygiene and sanitation measures, with drinking water interventions having the most impact on reducing diarrhoeal disease. A meta-evaluation of studies assessing a specific household water treatment method, the biosand water filter, was completed. Results from the meta-evaluation illustrated that biosand water filters improve drinking water quality and reduce diarrhoeal disease. However, short follow-up times and inconsistent measures are a concern. Furthermore, there is no generally accepted field method for determining biosand water filter effectiveness that is useable in low-resource communities. This study adds to understanding of biosand water filters.

Bacterial adaptation and performance of household biosand water filters in differing temperatures

The household biosand filter (BSF) is a highly utilized point-of-use water treatment tool. The effect of ambient temperature on the ability of the BSF to remove microbes from water is unclear. Model filters were distributed among different temperature-controlled laboratories and dosed daily with surface water amended with sewage. Comparison of the total coliform and Escherichia coli counts in the influent versus effluent revealed an immediate drop in the removal efficiencies of filters held in colder rooms. This performance difference, however, became less pronounced over the course of the experiment until no significant performance difference was detected between filters regardless of their ambient temperature, perhaps due to microbial adaptation within the BSFs. Subsequently, two-thirds of the filters were exposed to freezing temperatures, thawed, and re-tested for microbial removal. All filters exposed to freezing temperatures showed significant drops in microbial removal compared to control filters. Filters exposed to the most extreme temperatures showed the greatest drop in performance.

Biosand water filters for floating villages in Cambodia: safe water does not prevent recontamination

Water for Cambodia used biosand filters (BSFs) to provide microbiologically safe drinking water for people in Moat Khla floating village in 2010 and 2011. All 189 families use the lake, which by World Health Organization (WHO) standards is deemed unsafe for drinking water. Surveys from December 2010 to February 2011 compared 40 families using BSFs and 40 families not using BSFs. Over 92% of BSF households and 90% of non-BSF households were using high-risk lake source water (>100 colonies Escherichia coli/100 mL). Only 2.5% of BSF households had filtered water with bacteria in the high-risk range and only 5% of these 40 households showed recontamination in their storage water. Forty percent of non-BSF households had high-risk bacteria levels in their stored water, and most used no treatment. Storage water for non-BSF families showed a significant reduction in mean log10E. coli levels compared to their lake source water. Stored water for non-BSF families showed recontamination even for UV-treated water and boiled river water. Recontamination occurs in both groups but is much less for BSF households highlighting the value of proper storage containers used by BSF households and the need for water and sanitation education for floating villages in Cambodia.

The effect of increasing grain size in biosand water filters in combination with ultraviolet disinfection

With sand less than 0.70 mm often difficult to source in the field, it is of interest to study larger grained sand for use in biosand water filters (BSF). This study examined how sand grain size affects biological sand water filtration and how the combination of biological sand filtration and ultraviolet (UV) disinfection affects drinking water quality. Two BSFs were built: a control with maximum grain size, dmax = 0.70 mm and an experimental with grain sizes ranging from 0.70 mm to dmax = 2.0 mm. Untreated water was passed through each BSF daily. Results show Escherichia coli and turbidity removal characteristics of the control and experimental BSFs were not significantly different from one another. Both BSFs produced water that met World Health Organization (WHO) drinking water guidelines for turbidity, and although E. coli reduction was over 98% for each BSF, a high initial bacteria concentration resulted in effluent levels above WHO guidelines. Subsequently, effluent from each BSF was placed in clear plastic bottles under UV light, after which water from each BSF met E. coli guidelines. The data yielded promising results for using larger sand in BSFs, but longer duration studies with more data points are needed.

Cluster Randomized Controlled Trial of the Plastic BioSand Water Filter in Cambodia

About half of the rural population of Cambodia lacks access to improved water; an even higher percentage lacks access to latrines. More than 35,000 concrete BioSand Water filters (BSF) have been installed in the country. However, the concrete BSF takes time to produce and weighs hundreds of pounds. A plastic BSF has been developed but may not perform to the same benchmarks established by its predecessor. To evaluate plastic BSF performance and health impact, we performed a cluster randomized controlled trial in 13 communities including 189 households and 1147 participants in the Angk Snoul district of Kandal Province from May to December 2008. The results suggest that villages with plastic BSFs had significantly lower concentrations of E. coli in drinking water and lower diarrheal disease (incidence rate ratio 0.41, 95% confidence interval: 0.24-0.69) compared to control villages. As one of the first studies on the plastic BSF in Cambodia, these are important findings, especially in a setting where the concrete BSF has seen high rates of continued use years after installation. The study suggests the plastic BSF may play an important role in scaling up the distribution/implementation of the BSF, potentially improving water quality and health in the region.

Malaria, Intestinal Parasitic Infection, Anemia, and Malnourishment in Rural Cameroonian Villages with an Assessment of Early Interventions

Malaria, water-borne diarrheal diseases, and geohelminth infections, combined with severe malnutrition ravage entire villages throughout subSaharan Africa. The Bawa Health Initiative (BHI) is a 501c(3) non-profit organization with the goal of implementing a comprehensive public health program in an attempt to address these problems in a series of rural villages located in the West Province of Cameroon, Africa. Interventions include the provision of permethrin-treated bed nets to reduce the transmission of malaria, the installation of biosand water filters to reduce the prevalence of water-borne diseases, and a geohelminth control program utilizing mass treatment with albendazole. This study details the results of surveys conducted to monitor the success of the interventions. Since implementation of interventions, the number of clinical cases of malaria, diarrheal disease and typhoid has decreased, the prevalence of water-borne protozoan parasites has decreased, the prevalence and intensities of geohelminth infections has significantly decreased, and the prevalence of anemia has significantly decreased. When viewed in its entirety, these data show that the comprehensive approach to public health challenges in these villages initiated by BHI has been extremely successful. However, much work remains to be done. The primary purpose of this paper is to further inform academicians, students, and the general public about the continuing problems associated with these diseases and to describe and assess the effectiveness of some current interventions being used to combat them.

Prevalence of Waterborne Protozoan Parasites in Two Rural Villages in the West Province of Cameroon

The prevalence of the waterborne protozoan parasites Entamoeba histolytica/dispar, Giardia lamblia, and Cryptosporidium parvum were investigated in Nloh and Bawa, 2 rural agrarian villages in the West Province of Cameroon, Africa. The purpose of this study was to gather baseline data prior to the installation of biosand water filters in Nloh and to determine the prevalence of these parasites in Nloh and Bawa. Human stool samples were collected during June 2007, (85 from Nloh and 114 from Bawa) and tested utilizing the Triage Micro Parasite Panel® for the presence of the aforementioned protozoans. In Nloh, prevalences of E. histolytica/dispar, G. lamblia, and C. parvum were 15.7%, 14.5%, and 3.6%, respectively; and 7.1%, 1.8%, and 0.0% in Bawa, respectively. There were no significant differences in prevalence among age groups or between genders. The prevalence of G. lamblia was significantly lower in Bawa than in Nloh. However, no significant difference was detected in the prevalences of E. histolytica/dispar between Nloh and Bawa.

Microbial and chemical assessment of ceramic and BioSand water filters in rural Cambodia

Unless significant advances are made in the water and sanitation sector, it is unlikely that Cambodia will meet the United Nations Millennium Development Goal (MDG) target #7 for water and sanitation. Point-of-use technologies (POU), also termed “household water treatment technologies”, have been identified as successful options for providing safe water to rural households. Ceramic water filters and BioSand filters are two major POU technologies that are currently implemented across Cambodia. This paper presents data on the microbial performance of these two technologies in the field on various Cambodian source waters. In addition, data are presented on the occurrence of nitrite in treated water. Results showed that 61% and 88% of BioSand filters and ceramic filters, respectively, produced water in the low risk range for E. coli as defined by the WHO (0–10 CFU/100 mL). In addition, 83% of BioSand filters and 75% of ceramic filters were not meeting the WHO guideline value for chronic exposure to nitrite in drinking water (0.2 mg/L).