A membrane device, comprising: two or more membrane cassettes disposed in a stack of membrane cassettes, each membrane cassette comprising a top porous metal membrane and a bottom porous metal membrane disposed on respective sides of a support frame, the support frame including two symmetric half frames, a top half frame and a bottom half frame, wherein the top porous metal membrane attaches to the top half frame and the bottom porous membrane attaches to the bottom half frame, wherein further each of the top half frame and the bottom half frame comprising at least one front depression and at least one rear depression positioned on respective front and rear faces of the half frames (202, 204), wherein the front and rear depressions (206, 208) are such that, when the half frames (202, 204) are coupled together, they form together a plurality of front and rear permeate or sweep flow slots (210,212), each of the top half frame and the bottom half frame further comprising at least one left side depression and at least one right side depression, wherein the left side and right side depressions (214, 216) are such that, when the half frames (202, 204) are coupled together, they form together a plurality of left side and right side feed flow slots (218, 220), the plurality of permeate or sweep flow slots (210,212) and the plurality of feed flow slots (218, 220) being located on respective sides of the membrane device with flow channels that transport selected fluids across the surfaces of the porous membranes (302, 304) in the membrane cassettes during operation that provide separation or filtration of particulates or molecules of a selected size from the fluids introduced into the membrane device. two or more membrane cassettes disposed in a stack of membrane cassettes, each membrane cassette comprising a top porous metal membrane and a bottom porous metal membrane disposed on respective sides of a support frame, the support frame including two symmetric half frames, a top half frame and a bottom half frame, wherein the top porous metal membrane attaches to the top half frame and the bottom porous membrane attaches to the bottom half frame, wherein further each of the top half frame and the bottom half frame comprising at least one front depression and at least one rear depression positioned on respective front and rear faces of the half frames (202, 204), wherein the front and rear depressions (206, 208) are such that, when the half frames (202, 204) are coupled together, they form together a plurality of front and rear permeate or sweep flow slots (210,212), each of the top half frame and the bottom half frame further comprising at least one left side depression and at least one right side depression, wherein the left side and right side depressions (214, 216) are such that, when the half frames (202, 204) are coupled together, they form together a plurality of left side and right side feed flow slots (218, 220), the plurality of permeate or sweep flow slots (210,212) and the plurality of feed flow slots (218, 220) being located on respective sides of the membrane device with flow channels that transport selected fluids across the surfaces of the porous membranes (302, 304) in the membrane cassettes during operation that provide separation or filtration of particulates or molecules of a selected size from the fluids introduced into the membrane device.