Tertiary filter

A method of operating a filter apparatus including a backwashing of a pile filter media comprising:

• providing a pile filter media comprised of a plurality of fiber bundles on a fabric backing;
• flowing effluent containing entrained solids through the pile filter media in a first direction between the fiber bundles and then through the fabric backing causing the fiber bundles of said filter media to lay flat;
• backwashing said pile fabric with a suction assembly comprising a suction head and an adjacent faceplate;
• wherein said suction head and said adjacent faceplate are spaced from said filter media by a distance such that the fibers of the fiber bundle, even when in their extended and erect position, is such that substantially no fibers are drawn into contact with the suction head and faceplate such that the suction assembly does not exert mechanical pressure on said filter media;
• said backwashing further comprising first flowing dirty effluent between said faceplate and the laid flat filter media in a position beneath, and in a direction parallel to, said faceplate and thereafter creating a second flow direction by exposing the fiber bundles to said suction head thereby causing said fiber bundles to stand erect thereby releasing entrained solids on, and between, said fiber bundles to be carried away from the fiber bundles in a direction perpendicular to said first flowing direction;
• and
• further comprising rotating said suction head about a horizontal axis over substantially the entire surface of said filter media.