Abstract: Double-sided, self-cleansing media, and systems incorporating the same for a rotating biological contactor, are described. The media include a disk having cone-shaped members extending perpendicularly from both major faces thereof. Two or more disks lock together, axially about a rotating central shaft, by connecting cone-shaped members spaced throughout the disk surface having a socket at their base to receive the top of the corresponding connecting cone-shaped member on the adjacent disk. The cone-shaped members, by virtue of their length, space the disks a desired distance. Disk segments can link to one another along either straight and/or curved connection portions thereof. The geometry of the media provides free passage of the air and water during each revolution, and while the base disk slices through the air and water, the projecting cone-shaped members enter the air and water perpendicular to the direction of rotation and are washed clear of excess biomass during each rotation.