Improving Slow Sand Filters for Communities with Low Incomes and Limited Water Access

摘要

Slow sand filtration is an inexpensive and efficient way to obtain potable water, but therernare aspects of the filter’s construction and function that need to be improved (e.g., preparation ofrnthe sand) so that it can be used in communities with low incomes and limited water access.rnDevelopment of a process to prepare the sand in a way in which less water and time is consumedrnwill be beneficial to members of these communities. Although no data appears to be available inrnthe literature, field experience of the authors indicates that huge amounts of water are requiredrnfor sand washing. A new procedure was developed in which ten 19 L containers, 8.0 L of waterrnand a fabric bag were used to clean approximately 6 L of sand, which is approximately one halfrnof the sand needed for a point-of-use filter. The effectiveness of the procedure was determinedrnby measuring the turbidity of the water passing through the cleaned sand. Further processing ofrnthe cleaning water by sedimentation allowed 78% of its reuse. This procedure will furtherrnincrease the use of slow sand filters in communities with low incomes and limited water accessrnwith a corresponding increase in public health.