Research Papers

Displaying 51 - 60 of 89
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.
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.
There is enough evidence to state that ceramic filters are an effective form of HWT. There is not enough evidence for biosand filters, as more long term studies are required. The evidence suggests that SODIS, chlorination, and coagulation-chlorination are not effective in the long term.