Process of washing a filter having at least two layers of filter media, particularly for seawater

摘要

Process of washing a filter (F) having at least two layers of filter media for raw water containing components that tend to form cakes (M) or "mud balls" which are generally agglomerated on the filter surface, especially for seawater, being supported layers of filter media by a floor (6) comprising through holes and provided with nozzles (6a) allowing injection of air and / or wash water flowing water above down through the layers and being recovered treated water in the lower part of the filter, which comprises at the top at least one drain for collecting washing water, wherein the following successive steps are performed: a / a step of preparing the legacy whereby raw water is closed, and depressurization of the filter is secured when the latter works under pressure; b / the flat water drops in the filter; c / air is blown only in the lower pressure filter, through the air from below the filter layers and causing, particularly friction reducing particulate cake; d / rinsing with water alone, bottom-up, which allows to separate the media and to the surface particles, the time of rinsing with short enough water so that the water plane stops below the level of the edge is effected upper drain collecting washing water; and / emptied again water filter evacuation at the bottom; f / are repeated at least once steps c / d / e /, and proceeds to a final rinse by passing a quantity of backwash water injected into the bottom of the filter and discharged from the top of the filter by a conduit (14).