Research Papers

Displaying 71 - 80 of 89
E. coli removal was higher in the initial filter effluent (corresponding to water which had remained in the filter during the residence period) than filter effluent later in the filter run.
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.
Bacterial removal in BSFs is affected by ripening stage (best after 30 days) and pour volume. Viral removal varies based on the specific virus.
Water remaining in the pore space of the BSF during the pause time had higher removal than water which did not. Higher removal was also seen with lower dosing volumes (And thus lower flow rates).
An experimental slow sand filter was able to remove nitrate without significantly increasing nitrite, but at very low flow rates (0.015 to 0.6 m/h). Nitrite accumulation increased with flow rate. Most removal occurred at the top of the filter.
The Kanchan filter is a modified BSF which can remove arsenic. It has high acceptability and sustained use in Nepal (83% of >1000 filters still in use after 1 year)
Development and dissemination of Kanchan™ Arsenic Filter in rural Nepal; Ngai, T.K.K.; Murcott, S.; Shrestha, R.R.; Dangol, B.; Maharjan, M., 2006
The Kanchan arsenic filter is a successful technology that was designed to use locally available materials in Nepal, and was optimised for local cultural and socio-economic conditions.
E. coli removal from BSFs in the lab varied from 63-99%, and in the field from 0-99.7%. Factors such as stage of filter ripening, residence period, dosing volume, and other operational parameters were thought to contribute to this variability.
The biosand filters used in the filoed study, that had been in use for an average of 2.5 years, showed an overall bacterial removal efficiency of 98.5% and a turbidity reduction from an average of 6.2 NTU in source water to samples to 0.9 NTU in the filtered water. Additioanlly, participants were generally satisfied with them.

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