Method for backwashing water processing systems

Abstract

In a method for backwashing a water processing system using a buoyant filter layer constrained under wire mesh screen extending across a processing vessel, a water surface level in the processing vessel is lowered below the wire mesh screen. Air is subsequently released from under the buoyant filter layer to separate substances clogging the filter layer, while allowing the release of air out of said vessel from an upper part thereof. By lowering the water surface level below the upper wire mesh screen, the filter material is allowed to move more freely because the filter material is not restricted by the wire mesh screen from making upward movement. Hence, when air is released from under the filter layer, the filter material can move uniformly over the entire filter layer, and the clogging substances such as SS captured by the filter material and the biological film formed on the surface of the filter material can be favorably removed without damaging the filter material. The removed clogging substances may be allowed to precipitate in a lower part of the processing vessel so that they can be readily removed out of the processing vessel from an eject port provided in a lower part of the processing vessel, or may be drawn out of the processing vessel along with backwashing water into a precipitating vessel so that the clogging substances may be separated in the precipitating vessel.

Dependencies are inferred from the claim text.