Design of an Intermittent Biosand Filter Amended with Oyster Shell Powders for the Improvement of Household Water Quality in Sub-Saharan Africa and Madagascar

Abstract

Access to safe drinking water and the wide spread of water-borne diseases are major challenges in Sub-Saharan Africa and Madagascar. Based on this, a water purification models has been developed which can use on a local scale. It consists of an intermittent biosand filter amended with oyster shell powders designed from local materials. The performance of the filter was evaluated through physicochemical and bacteriological analyses using standardized methods on raw polluted well water with previously determined initial D0 characteristics. The effectiveness of the designed filter was assessed and a filtration operation was carried out over a monitoring period of 13 days (D13) prior to 7 days of acclimatization of the system. With a filtration rate of 0.75l/h-1, there is a very strong reduction in turbidity from 35.59NTU to 0 NTU and in BOD5 from 125mg/l to 2mg/l. More so, bacteriological analyses reveal a progressive and complete decrease from D0 to D13 of fecal coliforms from 9000 CFU/100ml to 0 CFU/100ml; total coliforms from 6,000 CFU/100 ml to 0 CFU/100 ml and fecal streptococci from 10,800 CFU/100 ml to 0 CFU/100 ml. Compared to the classic ceramic filter, no significant difference in the Duncan test is reported for the highlighted parameters. This filter presents potential among other water treatment methods at the local scale for reducing the risks of water-borne diseases and achieving Sustainable Development Goal 6 in developing countries.