Slow sand filtration has been recognized as one of the effective methods of drinking water production in the rural areas of developing countries. In this study, a series of laboratory scale experiments was carried out to study the effects of fine sand size on water filter performance. Two kinds of fine sand, sand A (diameter: 0.5 to 1.18mm) and sand B (diameter: 0 to 1.18mm), were employed. Basic experimental unit was an acrylic rectangular tank, 60cm in length, 20cm in width and 70cm in height. Five compartments were arranged in a way to maximize water purification streamline. Significant improvement was made by applying for the sand B (diameter: 0 to 1.18mm) compared to the sand A (diameter: 0.5 to 1.18mm). It was found that water filter using sand B was capable of removing more than 85 % suspended solids and 81% turbidity, which were remarkably higher than those when using sand A. Good removal efficiencies for colour, iron, manganese, COD, bacteria and faecal coliform were 82%, 91%, 93%, 85%, 93% and 100% respectively at sand B. Further investigation about the removal efficiency at different stages of unit processes with sand B demonstrated that most of turbidity, colour, Fe, Mn and fecal coliform were effectively removed after sand bag screening and slow sand filtration. Mean percentage removals were 72%, 64%, 79%, 78% and 93%, respectively. ACF played an important role for remaining particles removal. The resulting removal efficiencies after ACF adsorption for turbidity, colour, Fe and Mn were 12%, 27.3%, 13% and17%, respectively.
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