Research Papers

Displaying 61 - 70 of 89
Field Evaluation of Long-Term Performance and Use of Biosand Filters in Posoltega, Nicaragua; Vanderzwaag, J.C.; Atwater, J.W.; Bartlett, H.; Baker, D., 2009
Long-term performance of filters 3 and 8 years old was good, with 96% removal of E.coli, but due to poor construction only 10% of households were still using their BSFs.
Decentralized systems for potable water and the potential of membrane technology; Peter-Varbanets, M.; Zurbrügg, C.; Swartz, C.; Pronk, W., 2009
A comprehensive review of the potential of membrane technologies in HWTS.
A model of the cost-benefit ratios for various intervention options for reducing cholera found that digging a borehole, installing BSFs, or school-based vaccination programs are usually better than community-based vaccination programs.
More work is needed to optimize the Kanchan filter for arsenic removal. Water flows too quickly through the nail bed, so that no difference was found in influent arsenic levels and those in the filter standing head after flowing through the nails.
The authors of the Chiew et al. (2009) paper defend their methodology and results against criticisms. Differences between their results and others are likely due to water quality differences.
Children in households with a BSF had 54% less diarrhoea than in control households.
The methodology used by Sobsey et al. (2008) to rank HWTS options was flawed. A "silver-bullet" approach is not appropriate, as complex local conditions must be accounted for.
Sobsey et al. defend their 2008 paper from criticism. Their evaluation was just a starting point based on available data, but all HWTS methods need more research.
E. coli removal in slow sand filters is related to ripening time, temperature, biological activity, media grain size and empty bed contact time (related to flow rate and sand depth). The quantity of protists (a type of micro-organism) in the schmutzdecke was strongly associated with E. coli removal and may indicate predation as a key mechanism.
Week-by-week microscopy images of a biolayer developing in a slow sand filter are presented.

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