STUDIES ON PARTICLE CHARACTERISTICS AND PRESSURE DROP IN GRANULAR MEDIA FILTRATION

Abstract

Rapid gravity granular media filters are widely used in the water and wastewater treatment industries. Regular backwashing to clean the filters is a vital part of their efficient operation. In the present study, emphasis was given on the removal of fine suspension particle by filtration through low cost coarse media. A set up was made in the laboratory and filtration process was proceeded. The media taken was the mixed bed of Calcite-Anthracite, Calcite-Garnet & Anthracite-Garnet. Clay was added in a definite amount (20 mg l-1) in tap water and this suspension was used. Samples at regular intervals were collected and analyzed. Also, the effect of pressure drop was taken into consideration. Results obtained indicated_that the removal efficiency was best observed in the case of "Calcite-Garnet" as compared to "Anthracite-Garnet" and "Calcite-Anthracite" mixed beds. At 500 mm bed height, at a flow rate of 30 dm3 the removal efficiency of Calcite-Garnet was found to be 99.99%, of Anthracite-Garnet it was 99.85 % and of Calcite-Anthracite it was found 99.5% at time interval of 60 min. Studies on the effect of different parameter on the removal performance of fine suspended particle shows that a smaller particle size, a greater filter depth, shorter cycle time gave an advantage in removal efficiency.