The Parkson TumbleOx™ Bioreactor consists of a treatment tank(s) containing a series of slowly rotating drums. Each drum is partially filled with loose media which freely tumbles inside the five-foot diameter drum as it rotates. A thin biofilm grows on the media and provides biological treatment. The unique media design maximizes surface area for biological growth and also aerates the wastewater as the drum turns, providing dissolved oxygen for the micro-organisms. The system components include the rotating drum, plastic media, and the bearings and simple drive mechanism to slowly rotate the drum. No supplemental aeration system is required.