Comparison of Normal and Reverse‐Graded Filtration

Abstract

The objective of this study was to investigate the performance of an experimental sand filter operated in the conventional manner, and to compare this performance with a filter identical in all respects except that the grading sequence was reversed. The reverse grading was established by constructing a setting of sand with finest sizes at the base and coarsest on top, and by hydraulically transferring the contents of a conventional sand bed from one filter to another, thereby reversing the sequence of grading.