Biosand filters in Ghana contribute to a 60% overall reduction in diarrhoeal disease
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Eric Fewster
11-Feb-2013
An 8-month randomized controlled trial of the plastic biosand filter was performed in 6 rural communities in Tamale, Ghana, during 2008 by Stauber et al (2012). The trial was carried out in order to assess reductions in diarrheal disease and improvements in household drinking water quality. During the study, the longitudinal prevalence ratio for diarrhoea comparing households that received the filter to households that did not receive it was 0.40 (95% confidence interval: 0.05, 0.80), suggesting an overall diarrheal disease reduction of 60%. Further details are available here.
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Over 47% reduction in diarrhoea risk: new health impact studies on the BSF
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Eric Fewster
30-Nov-2009
A few health impact studies are starting to emerge on the biosand filter. These look at how much impact the filters have on diarrhoea in real life situations. So far, results are encouraging and confirm the anecdotal evidence that many of us hear from sand filter users in the field. Two studies carried out in the Dominican Republic and Kenya showed a reduction in diarrhoea risk of 47% and 54%, indicating a significant protective effect of the BSF against waterborne diarrheal disease. More information here.
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The effect of pause time on water quality: new research out
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Eric Fewster
28-Nov-2009
Research published by the University of North Carolina has confirmed the importance of residence time of water in a filter. Regarding the daily amount of water put through the filter, they found that microbial reductions were greater with a greater residence time within the filter, especially for water retained in the filter bed overnight. The researchers showed this through taking samples of filtered water at various stages when the filter was re-started after pause time – a significant drop in filtrate quality was noted after the pore volume threshold had been filtered. This showed that water that had been sitting in the filter during pause time had a much better quality, and this seems to be largely due to the increased contact time for biological and chemical processes in the sand. More information here.
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The effect of hydraulic loading on microbial removal: new research out
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Eric Fewster
28-Nov-2009
Following a call for research by biosandfilter.org, researchers at the University of California, Davis, answered the challenge to look at the effect of hydraulic loading on filter efficiency. Lab and field research looked at the effect of pause time on efficiency at removing viruses, bacteria and turbidity, as well as other parameters that influence flow rate and therefore residence time, namely hydraulic loading and sand size. They confirmed previous findings about the impact of pause time on water quality, but they also tested filters with varying levels of hydraulic loading above the sand surface (10, 20 and 30 cm) and two sand sizes (0.17 mm and 0.52 mm). They found that bacteria and virus removal was significantly better for filters with finer sand and those with lower head, independently from each other and for both short and long term residence times, but that results were enhanced with longer residence times. The best combination was 0.17 mm sand with 10 cm head over longer residence times. More information available here.
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On-site trainings carried out in Afghanistan and Somaliland
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Eric Fewster
28-Nov-2009
BushProof carried out biosand filter trainings for Tearfund in Kabul, Afghanistan in November 2008 and for Caritas in Hargeisa, Somaliland in March 2009. Over 30 NGO and government staff were trained as a result, and the trainings were well received.
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Training successfully carried out in Kenya from 17 - 21 December 2007
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Eric Fewster
21-Jul-2007
BushProof successfully held a training in household biosand filtration for 5 participants in Machakos, Kenya between 17 - 21 December 2007.
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BushProof helps Tearfund start bio-sand filter project
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Eric Fewster
23-Jun-2006
Tearfund has introduced bio-sand filters in Uvira, Democratic Republic of Congo, following a 5-day training organised by BushProof. Cholera is a serious problem in the area, as well as other water-related diseases, and it is hoped that these filters will provide a real health improvement to local people. The filters are being sold and it is hoped that sustainability will be achieved through sufficient local demand. More information is available here.
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Successful biosand filter training implemented in Kenya
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Eric Fewster
15-Dec-2005
BushProof has recently organised a 5-day training course in bio-sand filtration (BSF) in Kenya, for a number of local and international participants. The aim of the course was to fully prepare participants to start successful bio-sand filter projects in their own areas. The training was held on the site of a successful ongoing BSF project.
The training proved to be very practical and included hands-on construction of filters as well as field visits to install and commission the units in village households. The course focused on finding solutions for the particular environments from where the participants originated. In addition, theoretical sessions provided a firm grounding in filtration processes, highlighting previous research and project evaluations. Participants that wanted to learn more about scientific details involving bio-sand filters were given all opportunity to do so. Every participant received a CD which contains a wealth of information on (scientific) material regarding bio-sand filtration. In 2006, BushProof is planning additional BSF courses. Detailed course description and booking forms are available here.
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Bio-sand filter: Academic research needed
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Eric Fewster
24-Jun-2005
BushProof, the owner of BioSandFilter.org has been in contact with the University of North Carolina regarding developing detailed research parameters for areas it believes are gaps in the current knowledge base regarding intermittent biosand filtration. The research that has been carried out since September 2004 by the University of North Carolina has sought to evaluate the effectiveness of the bio-sand filter at removing individual pathogens, such as E. coli and certain viruses and bacteriophages. While the filter's effectiveness has been widely studied using indicator bacteria (such as E. coli), data on individual pathogen removal is scarce. This research will therefore add valuable knowledge on the effectiveness of intermittent filtration to the knowledge base. The fact that an estimated 100 thousand filters are already in use, makes this study all the more relevant.
The initial findings of the research found that:
- Ripening time varies, probably due to influent water quality
- Between 95-98% reduction was achieved of E. coli in a ripened filter
- About 80-90% virus reductions were observed in a ripened filter
- Filter performance and filtrate water quality are influenced by water dosing pause period and volume: greater retention time in a ripened filter leads to greater microbial reduction
In addition to this ongoing research, BushProof has been advocating the need to research the effect of hydraulic loading rates on pathogen removal. BushProof intends to carry out some field studies on the effect of this on field filters, but is trying to encourage research institutions to look into the effect of hydraulic loading rate on pathogen removal where bio-secure laboratory facilities are more readily available.
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Bio-sand filter solution in emergency situations
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Adriaan Mol
02-Mar-2005
BushProof provided technical support to a Medair project in Madagascar in late 2004. The Swiss based NGO used the improved round sand filters for a crisis response project following a destructive cyclone in two coastal zones. Within a few months more than 600 families received a sand filter, providing safe drinking water to several thousand people.
In Eastern Congo, a bio-sand filter project was recently started by Tear Fund. Due to insecurity, a filter training could not take place at the project site. However, several Congolese staff travelled to Kenya where they were trained by BushProof experts in the art of bio-sand filtration. The project area is often insecure, but a bio-sand filter ensures that clean water remains available, even if it's not possible to venture far outside the village.
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