Question

High rated trickling filter and its classifications

Answer 1

Trickling Filter also known as percolating or sprinkling filter is like a well having depth up to about 2m and filled with some granular media. The sewage is sprinkled over the media which percolates through filter media and is collected through the under-drainage system.

Classification-

Low Rate Filters-
They are also known as standard rate or conventional rate filters. The settled sewage is applied to the filter bed and after trickling through it, passes through the final sedimentation tank for removal of most of the stabilized solids.

High Rate Filters-
In case of high rate trickling filters the settled sewage is applied at much higher rate than for the low rate filter. The high rate filters of modern advancements also function on the same lines and having the same construction detail but with the difference that provision is made in them for recirculation of sewage through the filter by pumping a part of the trickling filter effluent to the primary settling tank and re-passing it through filter.