Abstract: Rotary disc filtration devices and filtration processes using those devices are disclosed. The devices have one or more fluid filtration gaps into which fluid to be filtered into permeate and retentate is placed. Each fluid filtration gap is defined by a disc and a filter, one of which rotates with respect to the other. The filter is carried on a filter member. The discs and interleaved filter members may be suspended from the top of the device, the top may rest on a vessel containing the fluid to be filtered, the discs may be attached to a single shaft for rotation, and the filter members may be suspended from a sleeve around the shaft, which sleeve keeps the filters centered with respect to the discs. Removal of the device's top removes the discs and filter members together, facilitating maintenance. Each filter member may have a peripheral lip and the lips of adjacent filter members may be sufficiently close to one another to substantially restrict the flow of retentate out of the fluid filtration gap.