Research Papers

Displaying 41 - 50 of 88
A BSF which was modified by placing a layer of iron-oxide coated sand inside the filter bed removed E.coli better than a standard BSF. The difference was largest towards the beginning of the filter run.
A household-scale sand filter was developed and tested in Pakistan. In the field test it removed 97% E.coli, Total Coliforms, and turbidity. (Not a BSF)
Households which were using BSF had 61% less diarrhoea. After one year, 90% of BSF's were still in use, and were removing 88.4% of E. coli.
Iron oxide amended biosand filters for virus removal; Bradley, I.; Straub, A.; Maraccini, P.; Markazi, S.; Nguyen, T.H., 2011
BSFs that were modified to have a layer of media where iron was mixed with the sand performed better than regular BSF at removing viruses. However, over a long time period (>200 days) even the regular filter reached 4 log 10 removal (99.99%).
Nitrification, denitrification, and ammonification occur in BSF. This can be a problem when influent water is very high in nitrogen (and very low in oxygen), as nitrite and nitrate levels may increase to dangerous levels.
Experiments in a lab found that a dual media column with a layer of manganese oxide coated sand and a layer of iron hydroxide coated sand was better at removing zinc than a column with just iron hydroxide coated sand. Both were better than a plain sand column at removing bacteria.
Improving Household Drinking Water Quality: Use of BioSand Filters in Cambodia; WorldBank, W.S.P.; Laing, K.; Sobsey, M.; Stauber, C., 2010
This study found that 88% of surveyed users sustained use of their BSFs (6 months to 8 years after implementation), had 95% E. coli reduction and 47% less diarrhoea. However, recontamination of water after filtration was an issue.
Small scale community and household approaches to water supply and treatment (Biosand filters, Ceramic filters, Chlorine, etc) each have their place in the provision of water to urban and peri-urban slums. Each has features making it appropriate in different settings.
A filter with coarser sand performed worse than one with finer sand, and a filter with a layer of iron filings in the media performed better than a regular filter.
In a study in Nicaragua, 77% of filters were still in use after 12 months. The filters removed 80% of E. coli, but there was recontamination in the storage buckets so the overall improvement was only 48%.