High-Rate Filtration in Polymer-Treated Sand Bed

Abstract

The performance of a deep-bed sand filter was investigated for removal of bentonite particles with an average equivalent spherical diameter of 1.3μm. The filter internal diameter was 16.51 cm and the packing depth was 0.61m. The bed was operated at high loading rates (5 to 35 gpm/ft² or 0.204 to 1.43 m³/min/m²) with and without application of concentrated polymer (Dearborn Aquafloc-418) solution precoats. The feed solids concentration was varied from 50 ppm to 200 ppm. Filter performance was improved using the precoated media. The applied polymer precoat concentration was found to influence both the solids removal efficiency and the bed pressure drop.