Patent ID: 7470372

Claim:
A method of treating an influent with a treatment device, comprising the steps of: passing the influent radially inwardly through a porous media to treat the influent, and passing the treated influent radially into an internal volume that is surrounded by said porous media, and then passing the treated influent axially in said internal volume in a first direction to an outlet; preventing the porous media from entering said internal volume; passing a pressurized backwash fluid axially in said internal volume in a second direction, opposite said first direction; using an orifice restriction located within said internal volume to define respective upper and lower portions of said internal volume; forcing the pressurized backwash fluid into said internal volume so that a portion of the pressurized backwash fluid is forced through said orifice and into the upper portion of the internal volume and into the porous media to create a drag force on an upper portion of the porous media, and a remainder of the pressurized backwash fluid in the lower portion of said internal volume is forced into the porous media and thereby bypasses said orifice, whereby a drag force is imparted on a lower portion of the porous media; and fluidizing respective portions of the porous media when the drag force exerted thereon by the pressurized backwash fluid is greater than a buoyant weight of the respective portion of the porous media.