Importance

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Abstract

An active filter system having a filter bed formed from at least one layer of filter media and a method of operating the active filter system to filter water or wastewater. The filter media includes a plurality of plastic particles coated with an active material. Preferably, the active material is removed from the plastic particles by directing influent (i.e., untreated water) upwardly though the filter bed for a predetermined period of time. While the influent is directed upwardly through the filter bed, air is periodically directed upwardly through the filter bed so that the washing cycle includes a plurality of combined air and influent stages and a plurality of influent only stages. The coated plastic filter media particles have a specific gravity less than the specific gravity of the influent as well as the specific gravity of the combined air and influent washing fluid so that the coated plastic filter media remains buoyant during the washing cycle.

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First Claim