Abstract: A filtration apparatus includes a container (24) that surrounds at least one rapidly rotating membrane pack (32, FIG. 2) and stationary turbulators (36A, 36B ) slightly spaced from the membrane pack surfaces to leave thin gaps (40A, 40B ) between them, which obtains the advantages of both series-connected and parallel-connected systems. A feed conduit (82) connects the radially outer ends (110) of the gaps, to carry feed fluid into and out of each gap, with radially outward flow (94) near the pack surfaces, causing radially inward flow (102) near the surfaces of the turbulators. The turbulators have recesses that leave projections to promote fluid shear at the membrane surfaces. A motor shaft (314) supported on motor bearings, has a motor housing fixed to the container. The motor shaft extends into the container and holds the membrane pack to spin it, so only the motor bearings (316, 318) support all rotating parts.