55-A Low Cost Filtration Technique for Silty Water Recharge

Abstract

A laboratory experiment was conducted to test the effectiveness of using locally available cheap materials as a pre-filter for surface water prior to artificial recharge. Double knitted hassein cloth and coconut coir compacted by hand pressure were arranged in cylindrical fashion and used to remove a major portion of silt load from water prior to it passing through a sand filter. Silted water of various concentrations was allowed to pond around the filter assembly and the filtrate was collected between the various filter components. Of the various layers of hassein cloth and thickness of coconut coir studied, 4 layers of hassein cloth and 15 cm thickness of coconut coir (compacted to 93 kg/m3) were found to be most suitable as a prefilter to a sand filter. In combination they removed about 75% of the silt load of influent water having concentrations up to 400 ppm. For the optimum combination, an empirical equation was developed to predict the filtrate suspension load for any influent suspension load up to 400 ppm and any rate of filtration through cloth-coir and sand.