Abstract: A wastewater treatment system includes a vessel and a plurality of media canisters contained in series therein. The vessel provides for linear flow of wastewater through the canisters for treating and removing contaminants. The canisters contain seal means to form a fluid tight seal against the inner wall of the vessel. The linear flow provides for increased flow rates and more efficient treatment and removal of contaminants. A method of using the treatment system to treat wastewater to remove or neutralize one or more contaminants therein is also described.