A wastewater treatment system, including: an equalization tank arranged to receive wastewater; a flow tube including an interior space bounded by at least one side wall of the flow tube; a plurality of media particles disposed within the interior space; and a pump arranged to pump the wastewater from the equalization tank to the flow tube. The plurality of media particles has a mean diameter of at least 4 millimeters. The wastewater is arranged to drain to the equalization tank through the plurality of media particles and the interior space. The flow tube is arranged to reduce a concentration of an organic contaminant in the wastewater.