Drinking water treatment by multistage filtration on a household scale: Efficiency and challenges

Universalising actions aimed at water supply in rural communities and indigenous populations must focus on simple and low-cost technologies adapted to the local context. In this setting, this research studied the dynamic gravel filter (DGF) as a pre-treatment to household slow-sand filters (HSSFs), which is the first description of a household multistage filtration scale to treat drinking water. DGFs (with and without a non-woven blanket on top of the gravel layer) followed by HSSFs were tested. DGFs operated with a filtration rate of 3.21 m3 m−2.d−1 and HSSFs with 1.52 m3 m−2.d−1. Influent water contained kaolinite, humic acid and suspension of coliforms and protozoa. Physical-chemical parameters were evaluated, as well as Escherichia coli, Giardia spp. cysts and Cryptosporidium spp. oocyst reductions. Removal was low (up to 6.6%) concerning true colour, total organic carbon and absorbance (λ = 254 nm). Nevertheless, HMSFs showed turbidity decrease above 60%, E. coli reduction up to 1.78 log, Giardia cysts and Cryptosporidium oocysts reductions up to 3.15 log and 2.24 log, respectively. The non-woven blanket was shown as an important physical barrier to remove solids, E. coli and protozoa. [Display omitted] •Household Multistage Filter removed over 60% of turbidity and 1.5 log of E. coli.•Dynamic Gravel Filter was an effective pre-treatment for household slow-sand filter.•Blanket improved the filtered water in gravel filter and household slow-sand filter.•Household Multistage Filter achieved more than 3 log of Giardia cyst reduction.•Household Multistage Filter obtained more than 2 log of Cryptosporidium oocyst reduction.