Reductions of E. coli, echovirus type 12 and bacteriophages in an intermittently operated household-scale slow sand filter

Iron oxide amended biosand filters for virus removal

“…BSFs remove greater than 99.9% of Giardia cysts and Cryptosporidium oocysts [18]. Bacterial concentrations are reduced 70-99.99%, depending on biofilm development and time of sampling [13,[19][20][21]. The improved water quality has been attributed to at least 20% reductions in frequency of diarrheal illness in studies conducted in the Dominican Republic [20] and Kenya [22].…”

“…The improved water quality has been attributed to at least 20% reductions in frequency of diarrheal illness in studies conducted in the Dominican Republic [20] and Kenya [22]. However, both field and laboratory research has identified a critical shortcoming: BSFs are not highly effective in removing viruses [13].…”

“…Pasteurized primary wastewater effluent from a local wastewater treatment plant was used to establish a biofilm in the MS2 experiments, as previously suggested by Elliott et al [13]. Treated wastewater effluent from the same treatment plant was used to conduct rotavirus experiments with high levels (20 mg/L TOC) of natural organic matter (NOM).…”

“…Sand was manually sieved using the appropriate meshes. The effective sand size was similar to that used previously in research and practice [12,13]. One filter was amended with iron by adding 5.54 kg of a mild steel nail (40 mm length, 2 mm diameter, "bright" finish) mixed evenly throughout the top 20 cm of the filter media, excluding the layer of fine sand.…”

“…The biofilm is credited with the enhanced removal of suspended solids and pathogens through mechanical trapping, adsorption, predation, and natural death. Development of the biofilm results in greater removal of suspended solids and pathogens, but its development also reduces flow rates [13][14][15].…”