Cleaning water-filtering material - by downward flush of water produced by sudden release of internal air pressure

摘要

The accumulated soil in a column of water filtering material occupying the central region of a vertical cylindrical casing with a body of water above the material but sepd. from the upper cap by a cushion of compressed air is removed by a sudden downward flush of that water caused by the rapid release of pressure in a further cushion of compressed air inside the base of the casing. The resulting sediment is allowed to settle, e.g. over a period of hours during the next filtering cycle, before the settled solids are removed through a base outlet. The sequence is repeated by first feeding compressed air into the lower cushion area. Only a small amt. of water is lost in each flushing operation which mainly involves merely a change in water location.