Abstract: An apparatus for facilitating the separation of organic materials from a fluid and for promoting the gas exchange from the fluid is provided. The apparatus includes a column having an interior chamber extending between a first end and a second end of the column. A plenum is situated circumferentially about the second end of the column. At a junction between the plenum and the interior chamber, an annulus is provided to permit the plenum to be in fluid communication with the interior chamber. An external port is provided for communication with the plenum. A column of media may be provided in the interior chamber through which fluid to be treated may flow.